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|
- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * linux/fs/namespace.c
- *
- * (C) Copyright Al Viro 2000, 2001
- *
- * Based on code from fs/super.c, copyright Linus Torvalds and others.
- * Heavily rewritten.
- */
- #include <linux/syscalls.h>
- #include <linux/export.h>
- #include <linux/capability.h>
- #include <linux/mnt_namespace.h>
- #include <linux/user_namespace.h>
- #include <linux/namei.h>
- #include <linux/security.h>
- #include <linux/cred.h>
- #include <linux/idr.h>
- #include <linux/init.h> /* init_rootfs */
- #include <linux/fs_struct.h> /* get_fs_root et.al. */
- #include <linux/fsnotify.h> /* fsnotify_vfsmount_delete */
- #include <linux/file.h>
- #include <linux/uaccess.h>
- #include <linux/proc_ns.h>
- #include <linux/magic.h>
- #include <linux/memblock.h>
- #include <linux/proc_fs.h>
- #include <linux/task_work.h>
- #include <linux/sched/task.h>
- #include <uapi/linux/mount.h>
- #include <linux/fs_context.h>
- #include <linux/shmem_fs.h>
- #include <linux/mnt_idmapping.h>
- #if defined(CONFIG_KSU_SUSFS_SUS_MOUNT) || defined(CONFIG_KSU_SUSFS_TRY_UMOUNT)
- #include <linux/susfs_def.h>
- #endif
- #ifdef CONFIG_KDP_NS
- #include <linux/kdp.h>
- #endif
- #include "pnode.h"
- #include "internal.h"
- #ifdef CONFIG_KSU_SUSFS_SUS_MOUNT
- extern bool susfs_is_current_ksu_domain(void);
- extern bool susfs_is_current_zygote_domain(void);
- static DEFINE_IDA(susfs_mnt_id_ida);
- static DEFINE_IDA(susfs_mnt_group_ida);
- #define CL_ZYGOTE_COPY_MNT_NS BIT(24) /* used by copy_mnt_ns() */
- #define CL_COPY_MNT_NS BIT(25) /* used by copy_mnt_ns() */
- #endif
- #ifdef CONFIG_KSU_SUSFS_AUTO_ADD_SUS_KSU_DEFAULT_MOUNT
- extern void susfs_auto_add_sus_ksu_default_mount(const char __user *to_pathname);
- bool susfs_is_auto_add_sus_ksu_default_mount_enabled = true;
- #endif
- #ifdef CONFIG_KSU_SUSFS_AUTO_ADD_SUS_BIND_MOUNT
- extern int susfs_auto_add_sus_bind_mount(const char *pathname, struct path *path_target);
- bool susfs_is_auto_add_sus_bind_mount_enabled = true;
- #endif
- #ifdef CONFIG_KSU_SUSFS_AUTO_ADD_TRY_UMOUNT_FOR_BIND_MOUNT
- extern void susfs_auto_add_try_umount_for_bind_mount(struct path *path);
- bool susfs_is_auto_add_try_umount_for_bind_mount_enabled = true;
- #endif
- /* Maximum number of mounts in a mount namespace */
- static unsigned int sysctl_mount_max __read_mostly = 100000;
- static unsigned int m_hash_mask __read_mostly;
- static unsigned int m_hash_shift __read_mostly;
- static unsigned int mp_hash_mask __read_mostly;
- static unsigned int mp_hash_shift __read_mostly;
- static __initdata unsigned long mhash_entries;
- static int __init set_mhash_entries(char *str)
- {
- if (!str)
- return 0;
- mhash_entries = simple_strtoul(str, &str, 0);
- return 1;
- }
- __setup("mhash_entries=", set_mhash_entries);
- static __initdata unsigned long mphash_entries;
- static int __init set_mphash_entries(char *str)
- {
- if (!str)
- return 0;
- mphash_entries = simple_strtoul(str, &str, 0);
- return 1;
- }
- __setup("mphash_entries=", set_mphash_entries);
- static u64 event;
- static DEFINE_IDA(mnt_id_ida);
- static DEFINE_IDA(mnt_group_ida);
- static struct hlist_head *mount_hashtable __read_mostly;
- static struct hlist_head *mountpoint_hashtable __read_mostly;
- static struct kmem_cache *mnt_cache __read_mostly;
- static DECLARE_RWSEM(namespace_sem);
- static HLIST_HEAD(unmounted); /* protected by namespace_sem */
- static LIST_HEAD(ex_mountpoints); /* protected by namespace_sem */
- struct mount_kattr {
- unsigned int attr_set;
- unsigned int attr_clr;
- unsigned int propagation;
- unsigned int lookup_flags;
- bool recurse;
- struct user_namespace *mnt_userns;
- };
- /* /sys/fs */
- struct kobject *fs_kobj;
- EXPORT_SYMBOL_GPL(fs_kobj);
- /*
- * vfsmount lock may be taken for read to prevent changes to the
- * vfsmount hash, ie. during mountpoint lookups or walking back
- * up the tree.
- *
- * It should be taken for write in all cases where the vfsmount
- * tree or hash is modified or when a vfsmount structure is modified.
- */
- __cacheline_aligned_in_smp DEFINE_SEQLOCK(mount_lock);
- static inline void lock_mount_hash(void)
- {
- write_seqlock(&mount_lock);
- }
- static inline void unlock_mount_hash(void)
- {
- write_sequnlock(&mount_lock);
- }
- static inline struct hlist_head *m_hash(struct vfsmount *mnt, struct dentry *dentry)
- {
- unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES);
- tmp += ((unsigned long)dentry / L1_CACHE_BYTES);
- tmp = tmp + (tmp >> m_hash_shift);
- return &mount_hashtable[tmp & m_hash_mask];
- }
- static inline struct hlist_head *mp_hash(struct dentry *dentry)
- {
- unsigned long tmp = ((unsigned long)dentry / L1_CACHE_BYTES);
- tmp = tmp + (tmp >> mp_hash_shift);
- return &mountpoint_hashtable[tmp & mp_hash_mask];
- }
- #ifdef CONFIG_KSU_SUSFS_SUS_MOUNT
- // Our own mnt_alloc_id() that assigns mnt_id starting from DEFAULT_SUS_MNT_ID
- static int susfs_mnt_alloc_id(struct mount *mnt)
- {
- int res = ida_alloc_min(&susfs_mnt_id_ida, DEFAULT_SUS_MNT_ID, GFP_KERNEL);
- if (res < 0)
- return res;
- mnt->mnt_id = res;
- return 0;
- }
- #endif
- static int mnt_alloc_id(struct mount *mnt)
- {
- int res = ida_alloc(&mnt_id_ida, GFP_KERNEL);
- if (res < 0)
- return res;
- mnt->mnt_id = res;
- return 0;
- }
- static void mnt_free_id(struct mount *mnt)
- {
- #ifdef CONFIG_KSU_SUSFS_SUS_MOUNT
- // We should first check the 'mnt->mnt.susfs_mnt_id_backup', see if it is DEFAULT_SUS_MNT_ID_FOR_KSU_PROC_UNSHARE
- // if so, these mnt_id were not assigned by mnt_alloc_id() so we don't need to free it.
- if (unlikely(mnt->mnt.susfs_mnt_id_backup == DEFAULT_SUS_MNT_ID_FOR_KSU_PROC_UNSHARE)) {
- return;
- }
- // Now we can check if its mnt_id is sus
- if (unlikely(mnt->mnt_id >= DEFAULT_SUS_MNT_ID)) {
- ida_free(&susfs_mnt_id_ida, mnt->mnt_id);
- return;
- }
- // Lastly if 'mnt->mnt.susfs_mnt_id_backup' is not 0, then it contains a backup origin mnt_id
- // so we free it in the original way
- if (likely(mnt->mnt.susfs_mnt_id_backup)) {
- // If mnt->mnt.susfs_mnt_id_backup is not zero, it means mnt->mnt_id is spoofed,
- // so here we return the original mnt_id for being freed.
- ida_free(&mnt_id_ida, mnt->mnt.susfs_mnt_id_backup);
- return;
- }
- #endif
- ida_free(&mnt_id_ida, mnt->mnt_id);
- }
- /*
- * Allocate a new peer group ID
- */
- static int mnt_alloc_group_id(struct mount *mnt)
- {
- #ifdef CONFIG_KSU_SUSFS_SUS_MOUNT
- int res;
- // Check if mnt has sus mnt_id
- if (mnt->mnt_id >= DEFAULT_SUS_MNT_ID) {
- // If so, assign a sus mnt_group id DEFAULT_SUS_MNT_GROUP_ID from susfs_mnt_group_ida
- res = ida_alloc_min(&susfs_mnt_group_ida, DEFAULT_SUS_MNT_GROUP_ID, GFP_KERNEL);
- goto bypass_orig_flow;
- }
- res = ida_alloc_min(&mnt_group_ida, 1, GFP_KERNEL);
- bypass_orig_flow:
- #else
- int res = ida_alloc_min(&mnt_group_ida, 1, GFP_KERNEL);
- #endif
- if (res < 0)
- return res;
- mnt->mnt_group_id = res;
- return 0;
- }
- /*
- * Release a peer group ID
- */
- void mnt_release_group_id(struct mount *mnt)
- {
- #ifdef CONFIG_KSU_SUSFS_SUS_MOUNT
- // If mnt->mnt_group_id >= DEFAULT_SUS_MNT_GROUP_ID, it means 'mnt' is also sus mount,
- // then we free the mnt->mnt_group_id from susfs_mnt_group_ida
- if (mnt->mnt_group_id >= DEFAULT_SUS_MNT_GROUP_ID) {
- ida_free(&susfs_mnt_group_ida, mnt->mnt_group_id);
- mnt->mnt_group_id = 0;
- return;
- }
- #endif
- ida_free(&mnt_group_ida, mnt->mnt_group_id);
- mnt->mnt_group_id = 0;
- }
- /*
- * vfsmount lock must be held for read
- */
- static inline void mnt_add_count(struct mount *mnt, int n)
- {
- #ifdef CONFIG_SMP
- this_cpu_add(mnt->mnt_pcp->mnt_count, n);
- #else
- preempt_disable();
- mnt->mnt_count += n;
- preempt_enable();
- #endif
- }
- /*
- * vfsmount lock must be held for write
- */
- int mnt_get_count(struct mount *mnt)
- {
- #ifdef CONFIG_SMP
- int count = 0;
- int cpu;
- for_each_possible_cpu(cpu) {
- count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_count;
- }
- return count;
- #else
- return mnt->mnt_count;
- #endif
- }
- #ifdef CONFIG_KSU_SUSFS_SUS_MOUNT
- static struct mount *alloc_vfsmnt(const char *name, bool should_spoof, int custom_mnt_id)
- #else
- static struct mount *alloc_vfsmnt(const char *name)
- #endif
- {
- struct mount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL);
- if (mnt) {
- int err;
- #ifdef CONFIG_KSU_SUSFS_SUS_MOUNT
- if (should_spoof) {
- if (!custom_mnt_id) {
- err = susfs_mnt_alloc_id(mnt);
- } else {
- mnt->mnt_id = custom_mnt_id;
- err = 0;
- }
- goto bypass_orig_flow;
- }
- #endif
- err = mnt_alloc_id(mnt);
- #ifdef CONFIG_KSU_SUSFS_SUS_MOUNT
- bypass_orig_flow:
- #endif
- if (err)
- goto out_free_cache;
- #ifdef CONFIG_KDP_NS
- err = kdp_mnt_alloc_vfsmount(mnt);
- if (err)
- goto out_free_cache;
- #endif
- if (name) {
- mnt->mnt_devname = kstrdup_const(name,
- GFP_KERNEL_ACCOUNT);
- if (!mnt->mnt_devname)
- goto out_free_id;
- }
- #ifdef CONFIG_SMP
- mnt->mnt_pcp = alloc_percpu(struct mnt_pcp);
- if (!mnt->mnt_pcp)
- goto out_free_devname;
- this_cpu_add(mnt->mnt_pcp->mnt_count, 1);
- #else
- mnt->mnt_count = 1;
- mnt->mnt_writers = 0;
- #endif
- INIT_HLIST_NODE(&mnt->mnt_hash);
- INIT_LIST_HEAD(&mnt->mnt_child);
- INIT_LIST_HEAD(&mnt->mnt_mounts);
- INIT_LIST_HEAD(&mnt->mnt_list);
- INIT_LIST_HEAD(&mnt->mnt_expire);
- INIT_LIST_HEAD(&mnt->mnt_share);
- INIT_LIST_HEAD(&mnt->mnt_slave_list);
- INIT_LIST_HEAD(&mnt->mnt_slave);
- INIT_HLIST_NODE(&mnt->mnt_mp_list);
- INIT_LIST_HEAD(&mnt->mnt_umounting);
- INIT_HLIST_HEAD(&mnt->mnt_stuck_children);
- #ifdef CONFIG_KDP_NS
- kdp_set_mnt_userns(((struct kdp_mount *)mnt)->mnt, &init_user_ns);
- #else
- mnt->mnt.mnt_userns = &init_user_ns;
- #endif
- }
- return mnt;
- #ifdef CONFIG_SMP
- out_free_devname:
- kfree_const(mnt->mnt_devname);
- #endif
- out_free_id:
- mnt_free_id(mnt);
- out_free_cache:
- kmem_cache_free(mnt_cache, mnt);
- return NULL;
- }
- /*
- * Most r/o checks on a fs are for operations that take
- * discrete amounts of time, like a write() or unlink().
- * We must keep track of when those operations start
- * (for permission checks) and when they end, so that
- * we can determine when writes are able to occur to
- * a filesystem.
- */
- /*
- * __mnt_is_readonly: check whether a mount is read-only
- * @mnt: the mount to check for its write status
- *
- * This shouldn't be used directly ouside of the VFS.
- * It does not guarantee that the filesystem will stay
- * r/w, just that it is right *now*. This can not and
- * should not be used in place of IS_RDONLY(inode).
- * mnt_want/drop_write() will _keep_ the filesystem
- * r/w.
- */
- bool __mnt_is_readonly(struct vfsmount *mnt)
- {
- return (mnt->mnt_flags & MNT_READONLY) || sb_rdonly(mnt->mnt_sb);
- }
- EXPORT_SYMBOL_GPL(__mnt_is_readonly);
- static inline void mnt_inc_writers(struct mount *mnt)
- {
- #ifdef CONFIG_SMP
- this_cpu_inc(mnt->mnt_pcp->mnt_writers);
- #else
- mnt->mnt_writers++;
- #endif
- }
- static inline void mnt_dec_writers(struct mount *mnt)
- {
- #ifdef CONFIG_SMP
- this_cpu_dec(mnt->mnt_pcp->mnt_writers);
- #else
- mnt->mnt_writers--;
- #endif
- }
- static unsigned int mnt_get_writers(struct mount *mnt)
- {
- #ifdef CONFIG_SMP
- unsigned int count = 0;
- int cpu;
- for_each_possible_cpu(cpu) {
- count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_writers;
- }
- return count;
- #else
- return mnt->mnt_writers;
- #endif
- }
- static int mnt_is_readonly(struct vfsmount *mnt)
- {
- if (mnt->mnt_sb->s_readonly_remount)
- return 1;
- /* Order wrt setting s_flags/s_readonly_remount in do_remount() */
- smp_rmb();
- return __mnt_is_readonly(mnt);
- }
- /*
- * Most r/o & frozen checks on a fs are for operations that take discrete
- * amounts of time, like a write() or unlink(). We must keep track of when
- * those operations start (for permission checks) and when they end, so that we
- * can determine when writes are able to occur to a filesystem.
- */
- /**
- * __mnt_want_write - get write access to a mount without freeze protection
- * @m: the mount on which to take a write
- *
- * This tells the low-level filesystem that a write is about to be performed to
- * it, and makes sure that writes are allowed (mnt it read-write) before
- * returning success. This operation does not protect against filesystem being
- * frozen. When the write operation is finished, __mnt_drop_write() must be
- * called. This is effectively a refcount.
- */
- int __mnt_want_write(struct vfsmount *m)
- {
- struct mount *mnt = real_mount(m);
- int ret = 0;
- preempt_disable();
- mnt_inc_writers(mnt);
- /*
- * The store to mnt_inc_writers must be visible before we pass
- * MNT_WRITE_HOLD loop below, so that the slowpath can see our
- * incremented count after it has set MNT_WRITE_HOLD.
- */
- smp_mb();
- might_lock(&mount_lock.lock);
- #ifdef CONFIG_KDP_NS
- while (READ_ONCE(((struct kdp_mount *)mnt)->mnt->mnt_flags) & MNT_WRITE_HOLD) {
- #else
- while (READ_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD) {
- #endif
- if (!IS_ENABLED(CONFIG_PREEMPT_RT)) {
- cpu_relax();
- } else {
- /*
- * This prevents priority inversion, if the task
- * setting MNT_WRITE_HOLD got preempted on a remote
- * CPU, and it prevents life lock if the task setting
- * MNT_WRITE_HOLD has a lower priority and is bound to
- * the same CPU as the task that is spinning here.
- */
- preempt_enable();
- lock_mount_hash();
- unlock_mount_hash();
- preempt_disable();
- }
- }
- /*
- * After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will
- * be set to match its requirements. So we must not load that until
- * MNT_WRITE_HOLD is cleared.
- */
- smp_rmb();
- if (mnt_is_readonly(m)) {
- mnt_dec_writers(mnt);
- ret = -EROFS;
- }
- preempt_enable();
- return ret;
- }
- /**
- * mnt_want_write - get write access to a mount
- * @m: the mount on which to take a write
- *
- * This tells the low-level filesystem that a write is about to be performed to
- * it, and makes sure that writes are allowed (mount is read-write, filesystem
- * is not frozen) before returning success. When the write operation is
- * finished, mnt_drop_write() must be called. This is effectively a refcount.
- */
- int mnt_want_write(struct vfsmount *m)
- {
- int ret;
- sb_start_write(m->mnt_sb);
- ret = __mnt_want_write(m);
- if (ret)
- sb_end_write(m->mnt_sb);
- return ret;
- }
- EXPORT_SYMBOL_GPL(mnt_want_write);
- /**
- * __mnt_want_write_file - get write access to a file's mount
- * @file: the file who's mount on which to take a write
- *
- * This is like __mnt_want_write, but if the file is already open for writing it
- * skips incrementing mnt_writers (since the open file already has a reference)
- * and instead only does the check for emergency r/o remounts. This must be
- * paired with __mnt_drop_write_file.
- */
- int __mnt_want_write_file(struct file *file)
- {
- if (file->f_mode & FMODE_WRITER) {
- /*
- * Superblock may have become readonly while there are still
- * writable fd's, e.g. due to a fs error with errors=remount-ro
- */
- if (__mnt_is_readonly(file->f_path.mnt))
- return -EROFS;
- return 0;
- }
- return __mnt_want_write(file->f_path.mnt);
- }
- /**
- * mnt_want_write_file - get write access to a file's mount
- * @file: the file who's mount on which to take a write
- *
- * This is like mnt_want_write, but if the file is already open for writing it
- * skips incrementing mnt_writers (since the open file already has a reference)
- * and instead only does the freeze protection and the check for emergency r/o
- * remounts. This must be paired with mnt_drop_write_file.
- */
- int mnt_want_write_file(struct file *file)
- {
- int ret;
- sb_start_write(file_inode(file)->i_sb);
- ret = __mnt_want_write_file(file);
- if (ret)
- sb_end_write(file_inode(file)->i_sb);
- return ret;
- }
- EXPORT_SYMBOL_GPL(mnt_want_write_file);
- /**
- * __mnt_drop_write - give up write access to a mount
- * @mnt: the mount on which to give up write access
- *
- * Tells the low-level filesystem that we are done
- * performing writes to it. Must be matched with
- * __mnt_want_write() call above.
- */
- void __mnt_drop_write(struct vfsmount *mnt)
- {
- preempt_disable();
- mnt_dec_writers(real_mount(mnt));
- preempt_enable();
- }
- /**
- * mnt_drop_write - give up write access to a mount
- * @mnt: the mount on which to give up write access
- *
- * Tells the low-level filesystem that we are done performing writes to it and
- * also allows filesystem to be frozen again. Must be matched with
- * mnt_want_write() call above.
- */
- void mnt_drop_write(struct vfsmount *mnt)
- {
- __mnt_drop_write(mnt);
- sb_end_write(mnt->mnt_sb);
- }
- EXPORT_SYMBOL_GPL(mnt_drop_write);
- void __mnt_drop_write_file(struct file *file)
- {
- if (!(file->f_mode & FMODE_WRITER))
- __mnt_drop_write(file->f_path.mnt);
- }
- void mnt_drop_write_file(struct file *file)
- {
- __mnt_drop_write_file(file);
- sb_end_write(file_inode(file)->i_sb);
- }
- EXPORT_SYMBOL(mnt_drop_write_file);
- /**
- * mnt_hold_writers - prevent write access to the given mount
- * @mnt: mnt to prevent write access to
- *
- * Prevents write access to @mnt if there are no active writers for @mnt.
- * This function needs to be called and return successfully before changing
- * properties of @mnt that need to remain stable for callers with write access
- * to @mnt.
- *
- * After this functions has been called successfully callers must pair it with
- * a call to mnt_unhold_writers() in order to stop preventing write access to
- * @mnt.
- *
- * Context: This function expects lock_mount_hash() to be held serializing
- * setting MNT_WRITE_HOLD.
- * Return: On success 0 is returned.
- * On error, -EBUSY is returned.
- */
- static inline int mnt_hold_writers(struct mount *mnt)
- {
- #ifdef CONFIG_KDP_NS
- kdp_set_mnt_flags(((struct kdp_mount *)mnt)->mnt, MNT_WRITE_HOLD);
- #else
- mnt->mnt.mnt_flags |= MNT_WRITE_HOLD;
- #endif
- /*
- * After storing MNT_WRITE_HOLD, we'll read the counters. This store
- * should be visible before we do.
- */
- smp_mb();
- /*
- * With writers on hold, if this value is zero, then there are
- * definitely no active writers (although held writers may subsequently
- * increment the count, they'll have to wait, and decrement it after
- * seeing MNT_READONLY).
- *
- * It is OK to have counter incremented on one CPU and decremented on
- * another: the sum will add up correctly. The danger would be when we
- * sum up each counter, if we read a counter before it is incremented,
- * but then read another CPU's count which it has been subsequently
- * decremented from -- we would see more decrements than we should.
- * MNT_WRITE_HOLD protects against this scenario, because
- * mnt_want_write first increments count, then smp_mb, then spins on
- * MNT_WRITE_HOLD, so it can't be decremented by another CPU while
- * we're counting up here.
- */
- if (mnt_get_writers(mnt) > 0)
- return -EBUSY;
- return 0;
- }
- /**
- * mnt_unhold_writers - stop preventing write access to the given mount
- * @mnt: mnt to stop preventing write access to
- *
- * Stop preventing write access to @mnt allowing callers to gain write access
- * to @mnt again.
- *
- * This function can only be called after a successful call to
- * mnt_hold_writers().
- *
- * Context: This function expects lock_mount_hash() to be held.
- */
- static inline void mnt_unhold_writers(struct mount *mnt)
- {
- /*
- * MNT_READONLY must become visible before ~MNT_WRITE_HOLD, so writers
- * that become unheld will see MNT_READONLY.
- */
- smp_wmb();
- #ifdef CONFIG_KDP_NS
- kdp_clear_mnt_flags(((struct kdp_mount *)mnt)->mnt, MNT_WRITE_HOLD);
- #else
- mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD;
- #endif
- }
- static int mnt_make_readonly(struct mount *mnt)
- {
- int ret;
- ret = mnt_hold_writers(mnt);
- if (!ret)
- #ifdef CONFIG_KDP_NS
- kdp_set_mnt_flags(((struct kdp_mount *)mnt)->mnt, MNT_READONLY);
- #else
- mnt->mnt.mnt_flags |= MNT_READONLY;
- #endif
- mnt_unhold_writers(mnt);
- return ret;
- }
- int sb_prepare_remount_readonly(struct super_block *sb)
- {
- struct mount *mnt;
- int err = 0;
- /* Racy optimization. Recheck the counter under MNT_WRITE_HOLD */
- if (atomic_long_read(&sb->s_remove_count))
- return -EBUSY;
- lock_mount_hash();
- list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) {
- #ifdef CONFIG_KDP_NS
- if (!(((struct kdp_mount *)mnt)->mnt->mnt_flags & MNT_READONLY)) {
- #else
- if (!(mnt->mnt.mnt_flags & MNT_READONLY)) {
- #endif
- err = mnt_hold_writers(mnt);
- if (err)
- break;
- }
- }
- if (!err && atomic_long_read(&sb->s_remove_count))
- err = -EBUSY;
- if (!err) {
- sb->s_readonly_remount = 1;
- smp_wmb();
- }
- list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) {
- #ifdef CONFIG_KDP_NS
- if (((struct kdp_mount *)mnt)->mnt->mnt_flags & MNT_WRITE_HOLD)
- kdp_clear_mnt_flags(((struct kdp_mount *)mnt)->mnt, MNT_WRITE_HOLD);
- #else
- if (mnt->mnt.mnt_flags & MNT_WRITE_HOLD)
- mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD;
- #endif
- }
- unlock_mount_hash();
- return err;
- }
- static void free_vfsmnt(struct mount *mnt)
- {
- struct user_namespace *mnt_userns;
- #ifdef CONFIG_KDP_NS
- mnt_userns = mnt_user_ns(((struct kdp_mount *)mnt)->mnt);
- #else
- mnt_userns = mnt_user_ns(&mnt->mnt);
- #endif
- if (!initial_idmapping(mnt_userns))
- put_user_ns(mnt_userns);
- kfree_const(mnt->mnt_devname);
- #ifdef CONFIG_SMP
- free_percpu(mnt->mnt_pcp);
- #endif
- #ifdef CONFIG_KDP_NS
- if(((struct kdp_mount *)mnt)->mnt && is_kdp_vfsmnt_cache((unsigned long)((struct kdp_mount *)mnt)->mnt))
- kdp_free_vfsmount(((struct kdp_mount *)mnt)->mnt);
- #endif
- kmem_cache_free(mnt_cache, mnt);
- }
- static void delayed_free_vfsmnt(struct rcu_head *head)
- {
- free_vfsmnt(container_of(head, struct mount, mnt_rcu));
- }
- /* call under rcu_read_lock */
- int __legitimize_mnt(struct vfsmount *bastard, unsigned seq)
- {
- struct mount *mnt;
- if (read_seqretry(&mount_lock, seq))
- return 1;
- if (bastard == NULL)
- return 0;
- mnt = real_mount(bastard);
- mnt_add_count(mnt, 1);
- smp_mb(); // see mntput_no_expire()
- if (likely(!read_seqretry(&mount_lock, seq)))
- return 0;
- if (bastard->mnt_flags & MNT_SYNC_UMOUNT) {
- mnt_add_count(mnt, -1);
- return 1;
- }
- lock_mount_hash();
- if (unlikely(bastard->mnt_flags & MNT_DOOMED)) {
- mnt_add_count(mnt, -1);
- unlock_mount_hash();
- return 1;
- }
- unlock_mount_hash();
- /* caller will mntput() */
- return -1;
- }
- /* call under rcu_read_lock */
- static bool legitimize_mnt(struct vfsmount *bastard, unsigned seq)
- {
- int res = __legitimize_mnt(bastard, seq);
- if (likely(!res))
- return true;
- if (unlikely(res < 0)) {
- rcu_read_unlock();
- mntput(bastard);
- rcu_read_lock();
- }
- return false;
- }
- /*
- * find the first mount at @dentry on vfsmount @mnt.
- * call under rcu_read_lock()
- */
- struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry)
- {
- struct hlist_head *head = m_hash(mnt, dentry);
- struct mount *p;
- hlist_for_each_entry_rcu(p, head, mnt_hash)
- #ifdef CONFIG_KDP_NS
- if (((struct kdp_mount *)(p->mnt_parent))->mnt == mnt && p->mnt_mountpoint == dentry)
- #else
- if (&p->mnt_parent->mnt == mnt && p->mnt_mountpoint == dentry)
- #endif
- return p;
- return NULL;
- }
- /*
- * lookup_mnt - Return the first child mount mounted at path
- *
- * "First" means first mounted chronologically. If you create the
- * following mounts:
- *
- * mount /dev/sda1 /mnt
- * mount /dev/sda2 /mnt
- * mount /dev/sda3 /mnt
- *
- * Then lookup_mnt() on the base /mnt dentry in the root mount will
- * return successively the root dentry and vfsmount of /dev/sda1, then
- * /dev/sda2, then /dev/sda3, then NULL.
- *
- * lookup_mnt takes a reference to the found vfsmount.
- */
- struct vfsmount *lookup_mnt(const struct path *path)
- {
- struct mount *child_mnt;
- struct vfsmount *m;
- unsigned seq;
- rcu_read_lock();
- do {
- seq = read_seqbegin(&mount_lock);
- child_mnt = __lookup_mnt(path->mnt, path->dentry);
- #ifdef CONFIG_KDP_NS
- m = child_mnt ? ((struct kdp_mount *)child_mnt)->mnt : NULL;
- #else
- m = child_mnt ? &child_mnt->mnt : NULL;
- #endif
- } while (!legitimize_mnt(m, seq));
- rcu_read_unlock();
- return m;
- }
- static inline void lock_ns_list(struct mnt_namespace *ns)
- {
- spin_lock(&ns->ns_lock);
- }
- static inline void unlock_ns_list(struct mnt_namespace *ns)
- {
- spin_unlock(&ns->ns_lock);
- }
- static inline bool mnt_is_cursor(struct mount *mnt)
- {
- return mnt->mnt.mnt_flags & MNT_CURSOR;
- }
- /*
- * __is_local_mountpoint - Test to see if dentry is a mountpoint in the
- * current mount namespace.
- *
- * The common case is dentries are not mountpoints at all and that
- * test is handled inline. For the slow case when we are actually
- * dealing with a mountpoint of some kind, walk through all of the
- * mounts in the current mount namespace and test to see if the dentry
- * is a mountpoint.
- *
- * The mount_hashtable is not usable in the context because we
- * need to identify all mounts that may be in the current mount
- * namespace not just a mount that happens to have some specified
- * parent mount.
- */
- bool __is_local_mountpoint(struct dentry *dentry)
- {
- struct mnt_namespace *ns = current->nsproxy->mnt_ns;
- struct mount *mnt;
- bool is_covered = false;
- down_read(&namespace_sem);
- lock_ns_list(ns);
- list_for_each_entry(mnt, &ns->list, mnt_list) {
- if (mnt_is_cursor(mnt))
- continue;
- is_covered = (mnt->mnt_mountpoint == dentry);
- if (is_covered)
- break;
- }
- unlock_ns_list(ns);
- up_read(&namespace_sem);
- return is_covered;
- }
- static struct mountpoint *lookup_mountpoint(struct dentry *dentry)
- {
- struct hlist_head *chain = mp_hash(dentry);
- struct mountpoint *mp;
- hlist_for_each_entry(mp, chain, m_hash) {
- if (mp->m_dentry == dentry) {
- mp->m_count++;
- return mp;
- }
- }
- return NULL;
- }
- static struct mountpoint *get_mountpoint(struct dentry *dentry)
- {
- struct mountpoint *mp, *new = NULL;
- int ret;
- if (d_mountpoint(dentry)) {
- /* might be worth a WARN_ON() */
- if (d_unlinked(dentry))
- return ERR_PTR(-ENOENT);
- mountpoint:
- read_seqlock_excl(&mount_lock);
- mp = lookup_mountpoint(dentry);
- read_sequnlock_excl(&mount_lock);
- if (mp)
- goto done;
- }
- if (!new)
- new = kmalloc(sizeof(struct mountpoint), GFP_KERNEL);
- if (!new)
- return ERR_PTR(-ENOMEM);
- /* Exactly one processes may set d_mounted */
- ret = d_set_mounted(dentry);
- /* Someone else set d_mounted? */
- if (ret == -EBUSY)
- goto mountpoint;
- /* The dentry is not available as a mountpoint? */
- mp = ERR_PTR(ret);
- if (ret)
- goto done;
- /* Add the new mountpoint to the hash table */
- read_seqlock_excl(&mount_lock);
- new->m_dentry = dget(dentry);
- new->m_count = 1;
- hlist_add_head(&new->m_hash, mp_hash(dentry));
- INIT_HLIST_HEAD(&new->m_list);
- read_sequnlock_excl(&mount_lock);
- mp = new;
- new = NULL;
- done:
- kfree(new);
- return mp;
- }
- /*
- * vfsmount lock must be held. Additionally, the caller is responsible
- * for serializing calls for given disposal list.
- */
- static void __put_mountpoint(struct mountpoint *mp, struct list_head *list)
- {
- if (!--mp->m_count) {
- struct dentry *dentry = mp->m_dentry;
- BUG_ON(!hlist_empty(&mp->m_list));
- spin_lock(&dentry->d_lock);
- dentry->d_flags &= ~DCACHE_MOUNTED;
- spin_unlock(&dentry->d_lock);
- dput_to_list(dentry, list);
- hlist_del(&mp->m_hash);
- kfree(mp);
- }
- }
- /* called with namespace_lock and vfsmount lock */
- static void put_mountpoint(struct mountpoint *mp)
- {
- __put_mountpoint(mp, &ex_mountpoints);
- }
- static inline int check_mnt(struct mount *mnt)
- {
- return mnt->mnt_ns == current->nsproxy->mnt_ns;
- }
- /*
- * vfsmount lock must be held for write
- */
- static void touch_mnt_namespace(struct mnt_namespace *ns)
- {
- if (ns) {
- ns->event = ++event;
- wake_up_interruptible(&ns->poll);
- }
- }
- /*
- * vfsmount lock must be held for write
- */
- static void __touch_mnt_namespace(struct mnt_namespace *ns)
- {
- if (ns && ns->event != event) {
- ns->event = event;
- wake_up_interruptible(&ns->poll);
- }
- }
- /*
- * vfsmount lock must be held for write
- */
- static struct mountpoint *unhash_mnt(struct mount *mnt)
- {
- struct mountpoint *mp;
- mnt->mnt_parent = mnt;
- #ifdef CONFIG_KDP_NS
- mnt->mnt_mountpoint = ((struct kdp_mount *)mnt)->mnt->mnt_root;
- #else
- mnt->mnt_mountpoint = mnt->mnt.mnt_root;
- #endif
- list_del_init(&mnt->mnt_child);
- hlist_del_init_rcu(&mnt->mnt_hash);
- hlist_del_init(&mnt->mnt_mp_list);
- mp = mnt->mnt_mp;
- mnt->mnt_mp = NULL;
- return mp;
- }
- /*
- * vfsmount lock must be held for write
- */
- static void umount_mnt(struct mount *mnt)
- {
- put_mountpoint(unhash_mnt(mnt));
- }
- /*
- * vfsmount lock must be held for write
- */
- void mnt_set_mountpoint(struct mount *mnt,
- struct mountpoint *mp,
- struct mount *child_mnt)
- {
- mp->m_count++;
- mnt_add_count(mnt, 1); /* essentially, that's mntget */
- child_mnt->mnt_mountpoint = mp->m_dentry;
- child_mnt->mnt_parent = mnt;
- child_mnt->mnt_mp = mp;
- hlist_add_head(&child_mnt->mnt_mp_list, &mp->m_list);
- }
- static void __attach_mnt(struct mount *mnt, struct mount *parent)
- {
- #ifdef CONFIG_KDP_NS
- hlist_add_head_rcu(&mnt->mnt_hash,
- m_hash(((struct kdp_mount *)parent)->mnt, mnt->mnt_mountpoint));
- #else
- hlist_add_head_rcu(&mnt->mnt_hash,
- m_hash(&parent->mnt, mnt->mnt_mountpoint));
- #endif
- list_add_tail(&mnt->mnt_child, &parent->mnt_mounts);
- }
- /*
- * vfsmount lock must be held for write
- */
- static void attach_mnt(struct mount *mnt,
- struct mount *parent,
- struct mountpoint *mp)
- {
- mnt_set_mountpoint(parent, mp, mnt);
- __attach_mnt(mnt, parent);
- }
- void mnt_change_mountpoint(struct mount *parent, struct mountpoint *mp, struct mount *mnt)
- {
- struct mountpoint *old_mp = mnt->mnt_mp;
- struct mount *old_parent = mnt->mnt_parent;
- list_del_init(&mnt->mnt_child);
- hlist_del_init(&mnt->mnt_mp_list);
- hlist_del_init_rcu(&mnt->mnt_hash);
- attach_mnt(mnt, parent, mp);
- put_mountpoint(old_mp);
- mnt_add_count(old_parent, -1);
- }
- /*
- * vfsmount lock must be held for write
- */
- static void commit_tree(struct mount *mnt)
- {
- struct mount *parent = mnt->mnt_parent;
- struct mount *m;
- LIST_HEAD(head);
- struct mnt_namespace *n = parent->mnt_ns;
- BUG_ON(parent == mnt);
- list_add_tail(&head, &mnt->mnt_list);
- list_for_each_entry(m, &head, mnt_list)
- m->mnt_ns = n;
- list_splice(&head, n->list.prev);
- n->mounts += n->pending_mounts;
- n->pending_mounts = 0;
- __attach_mnt(mnt, parent);
- touch_mnt_namespace(n);
- }
- static struct mount *next_mnt(struct mount *p, struct mount *root)
- {
- struct list_head *next = p->mnt_mounts.next;
- if (next == &p->mnt_mounts) {
- while (1) {
- if (p == root)
- return NULL;
- next = p->mnt_child.next;
- if (next != &p->mnt_parent->mnt_mounts)
- break;
- p = p->mnt_parent;
- }
- }
- return list_entry(next, struct mount, mnt_child);
- }
- static struct mount *skip_mnt_tree(struct mount *p)
- {
- struct list_head *prev = p->mnt_mounts.prev;
- while (prev != &p->mnt_mounts) {
- p = list_entry(prev, struct mount, mnt_child);
- prev = p->mnt_mounts.prev;
- }
- return p;
- }
- /**
- * vfs_create_mount - Create a mount for a configured superblock
- * @fc: The configuration context with the superblock attached
- *
- * Create a mount to an already configured superblock. If necessary, the
- * caller should invoke vfs_get_tree() before calling this.
- *
- * Note that this does not attach the mount to anything.
- */
- struct vfsmount *vfs_create_mount(struct fs_context *fc)
- {
- struct mount *mnt;
- struct user_namespace *fs_userns;
- #ifdef CONFIG_KDP_NS
- struct user_namespace *userns;
- #endif
- if (!fc->root)
- return ERR_PTR(-EINVAL);
- #ifdef CONFIG_KSU_SUSFS_SUS_MOUNT
- // For newly created mounts, the only caller process we care is KSU
- if (unlikely(susfs_is_current_ksu_domain())) {
- mnt = alloc_vfsmnt(fc->source ?: "none", true, 0);
- goto bypass_orig_flow;
- }
- mnt = alloc_vfsmnt(fc->source ?: "none", false, 0);
- bypass_orig_flow:
- #else
- mnt = alloc_vfsmnt(fc->source ?: "none");
- #endif
- if (!mnt)
- return ERR_PTR(-ENOMEM);
- if (fc->sb_flags & SB_KERNMOUNT)
- #ifdef CONFIG_KDP_NS
- kdp_set_mnt_flags(((struct kdp_mount *)mnt)->mnt, MNT_INTERNAL);
- #else
- mnt->mnt.mnt_flags = MNT_INTERNAL;
- #endif
- atomic_inc(&fc->root->d_sb->s_active);
- #ifdef CONFIG_KDP_NS
- kdp_set_mnt_root_sb(((struct kdp_mount *)mnt)->mnt, dget(fc->root), fc->root->d_sb);
- mnt->mnt_mountpoint = ((struct kdp_mount *)mnt)->mnt->mnt_root;
- #else
- mnt->mnt.mnt_sb = fc->root->d_sb;
- mnt->mnt.mnt_root = dget(fc->root);
- mnt->mnt_mountpoint = mnt->mnt.mnt_root;
- #endif
- mnt->mnt_parent = mnt;
- #ifdef CONFIG_KDP_NS
- fs_userns = ((struct kdp_mount *)mnt)->mnt->mnt_sb->s_user_ns;
- if (!initial_idmapping(fs_userns)) {
- userns = get_user_ns(fs_userns);
- kdp_set_mnt_userns(((struct kdp_mount *)mnt)->mnt, userns);
- }
- #else
- fs_userns = mnt->mnt.mnt_sb->s_user_ns;
- if (!initial_idmapping(fs_userns))
- mnt->mnt.mnt_userns = get_user_ns(fs_userns);
- #ifdef CONFIG_KSU_SUSFS_SUS_MOUNT
- // If caller process is zygote, then it is a normal mount, so we just reorder the mnt_id
- if (susfs_is_current_zygote_domain()) {
- mnt->mnt.susfs_mnt_id_backup = mnt->mnt_id;
- mnt->mnt_id = current->susfs_last_fake_mnt_id++;
- }
- #endif
- #endif
- lock_mount_hash();
- #ifdef CONFIG_KDP_NS
- list_add_tail(&mnt->mnt_instance, &((struct kdp_mount *)mnt)->mnt->mnt_sb->s_mounts);
- #else
- list_add_tail(&mnt->mnt_instance, &mnt->mnt.mnt_sb->s_mounts);
- #endif
- unlock_mount_hash();
- #ifdef CONFIG_KDP_NS
- return ((struct kdp_mount *)mnt)->mnt;
- #else
- return &mnt->mnt;
- #endif
- }
- EXPORT_SYMBOL(vfs_create_mount);
- struct vfsmount *fc_mount(struct fs_context *fc)
- {
- int err = vfs_get_tree(fc);
- if (!err) {
- up_write(&fc->root->d_sb->s_umount);
- return vfs_create_mount(fc);
- }
- return ERR_PTR(err);
- }
- EXPORT_SYMBOL(fc_mount);
- struct vfsmount *vfs_kern_mount(struct file_system_type *type,
- int flags, const char *name,
- void *data)
- {
- struct fs_context *fc;
- struct vfsmount *mnt;
- int ret = 0;
- if (!type)
- return ERR_PTR(-EINVAL);
- fc = fs_context_for_mount(type, flags);
- if (IS_ERR(fc))
- return ERR_CAST(fc);
- if (name)
- ret = vfs_parse_fs_string(fc, "source",
- name, strlen(name));
- if (!ret)
- ret = parse_monolithic_mount_data(fc, data);
- if (!ret)
- mnt = fc_mount(fc);
- else
- mnt = ERR_PTR(ret);
- put_fs_context(fc);
- return mnt;
- }
- EXPORT_SYMBOL_GPL(vfs_kern_mount);
- struct vfsmount *
- vfs_submount(const struct dentry *mountpoint, struct file_system_type *type,
- const char *name, void *data)
- {
- /* Until it is worked out how to pass the user namespace
- * through from the parent mount to the submount don't support
- * unprivileged mounts with submounts.
- */
- if (mountpoint->d_sb->s_user_ns != &init_user_ns)
- return ERR_PTR(-EPERM);
- return vfs_kern_mount(type, SB_SUBMOUNT, name, data);
- }
- EXPORT_SYMBOL_GPL(vfs_submount);
- static struct mount *clone_mnt(struct mount *old, struct dentry *root,
- int flag)
- {
- #ifdef CONFIG_KDP_NS
- struct super_block *sb = ((struct kdp_mount *)old)->mnt->mnt_sb;
- int nsflags;
- struct user_namespace *userns;
- #else
- struct super_block *sb = old->mnt.mnt_sb;
- #endif
- struct mount *mnt;
- int err;
- #ifdef CONFIG_KSU_SUSFS_SUS_MOUNT
- bool is_current_ksu_domain = susfs_is_current_ksu_domain();
- bool is_current_zygote_domain = susfs_is_current_zygote_domain();
- /* - It is very important that we need to use CL_COPY_MNT_NS to identify whether
- * the clone is a copy_tree() or single mount like called by __do_loopback()
- * - if caller process is KSU, consider the following situation:
- * 1. it is NOT doing unshare => call alloc_vfsmnt() to assign a new sus mnt_id
- * 2. it is doing unshare => spoof the new mnt_id with the old mnt_id
- * - If caller process is zygote and old mnt_id is sus => call alloc_vfsmnt() to assign a new sus mnt_id
- * - For the rest of caller process that doing unshare => call alloc_vfsmnt() to assign a new sus mnt_id only for old sus mount
- */
- // Firstly, check if it is KSU process
- if (unlikely(is_current_ksu_domain)) {
- // if it is doing single clone
- if (!(flag & CL_COPY_MNT_NS)) {
- mnt = alloc_vfsmnt(old->mnt_devname, true, 0);
- goto bypass_orig_flow;
- }
- // if it is doing unshare
- mnt = alloc_vfsmnt(old->mnt_devname, true, old->mnt_id);
- if (mnt) {
- mnt->mnt.susfs_mnt_id_backup = DEFAULT_SUS_MNT_ID_FOR_KSU_PROC_UNSHARE;
- }
- goto bypass_orig_flow;
- }
- // Secondly, check if it is zygote process and no matter it is doing unshare or not
- if (likely(is_current_zygote_domain) && (old->mnt_id >= DEFAULT_SUS_MNT_ID)) {
- /* Important Note:
- * - Here we can't determine whether the unshare is called zygisk or not,
- * so we can only patch out the unshare code in zygisk source code for now
- * - But at least we can deal with old sus mounts using alloc_vfsmnt()
- */
- mnt = alloc_vfsmnt(old->mnt_devname, true, 0);
- goto bypass_orig_flow;
- }
- // Lastly, for other process that is doing unshare operation, but only deal with old sus mount
- if ((flag & CL_COPY_MNT_NS) && (old->mnt_id >= DEFAULT_SUS_MNT_ID)) {
- mnt = alloc_vfsmnt(old->mnt_devname, true, 0);
- goto bypass_orig_flow;
- }
- mnt = alloc_vfsmnt(old->mnt_devname, false, 0);
- bypass_orig_flow:
- #else
- mnt = alloc_vfsmnt(old->mnt_devname);
- #endif
- if (!mnt)
- return ERR_PTR(-ENOMEM);
- if (flag & (CL_SLAVE | CL_PRIVATE | CL_SHARED_TO_SLAVE))
- mnt->mnt_group_id = 0; /* not a peer of original */
- else
- mnt->mnt_group_id = old->mnt_group_id;
- if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) {
- err = mnt_alloc_group_id(mnt);
- if (err)
- goto out_free;
- }
- #ifdef CONFIG_KDP_NS
- nsflags = ((struct kdp_mount *)old)->mnt->mnt_flags;
- nsflags &= ~(MNT_WRITE_HOLD|MNT_MARKED|MNT_INTERNAL);
- kdp_assign_mnt_flags(((struct kdp_mount *)mnt)->mnt, nsflags);
-
- atomic_inc(&sb->s_active);
- userns = mnt_user_ns(((struct kdp_mount *)old)->mnt);
- kdp_set_mnt_userns(((struct kdp_mount *)mnt)->mnt, userns);
- if (!initial_idmapping(((struct kdp_mount *)mnt)->mnt->mnt_userns)) {
- userns = get_user_ns(((struct kdp_mount *)mnt)->mnt->mnt_userns);
- kdp_set_mnt_userns(((struct kdp_mount *)mnt)->mnt, userns);
- }
- kdp_set_mnt_root_sb(((struct kdp_mount *)mnt)->mnt, dget(root), sb);
- mnt->mnt_mountpoint = ((struct kdp_mount *)mnt)->mnt->mnt_root;
- #else
- mnt->mnt.mnt_flags = old->mnt.mnt_flags;
- mnt->mnt.mnt_flags &= ~(MNT_WRITE_HOLD|MNT_MARKED|MNT_INTERNAL);
- atomic_inc(&sb->s_active);
- mnt->mnt.mnt_userns = mnt_user_ns(&old->mnt);
- if (!initial_idmapping(mnt->mnt.mnt_userns))
- mnt->mnt.mnt_userns = get_user_ns(mnt->mnt.mnt_userns);
- mnt->mnt.mnt_sb = sb;
- mnt->mnt.mnt_root = dget(root);
- mnt->mnt_mountpoint = mnt->mnt.mnt_root;
- #endif
- mnt->mnt_parent = mnt;
- #ifdef CONFIG_KSU_SUSFS_SUS_MOUNT
- // If caller process is zygote and not doing unshare, so we just reorder the mnt_id
- if (likely(is_current_zygote_domain) && !(flag & CL_ZYGOTE_COPY_MNT_NS)) {
- mnt->mnt.susfs_mnt_id_backup = mnt->mnt_id;
- mnt->mnt_id = current->susfs_last_fake_mnt_id++;
- }
- #endif
- lock_mount_hash();
- list_add_tail(&mnt->mnt_instance, &sb->s_mounts);
- unlock_mount_hash();
- if ((flag & CL_SLAVE) ||
- ((flag & CL_SHARED_TO_SLAVE) && IS_MNT_SHARED(old))) {
- list_add(&mnt->mnt_slave, &old->mnt_slave_list);
- mnt->mnt_master = old;
- CLEAR_MNT_SHARED(mnt);
- } else if (!(flag & CL_PRIVATE)) {
- if ((flag & CL_MAKE_SHARED) || IS_MNT_SHARED(old))
- list_add(&mnt->mnt_share, &old->mnt_share);
- if (IS_MNT_SLAVE(old))
- list_add(&mnt->mnt_slave, &old->mnt_slave);
- mnt->mnt_master = old->mnt_master;
- } else {
- CLEAR_MNT_SHARED(mnt);
- }
- if (flag & CL_MAKE_SHARED)
- set_mnt_shared(mnt);
- /* stick the duplicate mount on the same expiry list
- * as the original if that was on one */
- if (flag & CL_EXPIRE) {
- if (!list_empty(&old->mnt_expire))
- list_add(&mnt->mnt_expire, &old->mnt_expire);
- }
- return mnt;
- out_free:
- mnt_free_id(mnt);
- free_vfsmnt(mnt);
- return ERR_PTR(err);
- }
- static void cleanup_mnt(struct mount *mnt)
- {
- struct hlist_node *p;
- struct mount *m;
- /*
- * The warning here probably indicates that somebody messed
- * up a mnt_want/drop_write() pair. If this happens, the
- * filesystem was probably unable to make r/w->r/o transitions.
- * The locking used to deal with mnt_count decrement provides barriers,
- * so mnt_get_writers() below is safe.
- */
- WARN_ON(mnt_get_writers(mnt));
- if (unlikely(mnt->mnt_pins.first))
- mnt_pin_kill(mnt);
- #ifdef CONFIG_KDP_NS
- hlist_for_each_entry_safe(m, p, &mnt->mnt_stuck_children, mnt_umount) {
- hlist_del(&m->mnt_umount);
- mntput(((struct kdp_mount *)m)->mnt);
- }
- fsnotify_vfsmount_delete(((struct kdp_mount *)mnt)->mnt);
- dput(((struct kdp_mount *)mnt)->mnt->mnt_root);
- deactivate_super(((struct kdp_mount *)mnt)->mnt->mnt_sb);
- #else
- hlist_for_each_entry_safe(m, p, &mnt->mnt_stuck_children, mnt_umount) {
- hlist_del(&m->mnt_umount);
- mntput(&m->mnt);
- }
- fsnotify_vfsmount_delete(&mnt->mnt);
- dput(mnt->mnt.mnt_root);
- deactivate_super(mnt->mnt.mnt_sb);
- #endif
- mnt_free_id(mnt);
- call_rcu(&mnt->mnt_rcu, delayed_free_vfsmnt);
- }
- static void __cleanup_mnt(struct rcu_head *head)
- {
- cleanup_mnt(container_of(head, struct mount, mnt_rcu));
- }
- static LLIST_HEAD(delayed_mntput_list);
- static void delayed_mntput(struct work_struct *unused)
- {
- struct llist_node *node = llist_del_all(&delayed_mntput_list);
- struct mount *m, *t;
- llist_for_each_entry_safe(m, t, node, mnt_llist)
- cleanup_mnt(m);
- }
- static DECLARE_DELAYED_WORK(delayed_mntput_work, delayed_mntput);
- static void mntput_no_expire(struct mount *mnt)
- {
- LIST_HEAD(list);
- int count;
- rcu_read_lock();
- if (likely(READ_ONCE(mnt->mnt_ns))) {
- /*
- * Since we don't do lock_mount_hash() here,
- * ->mnt_ns can change under us. However, if it's
- * non-NULL, then there's a reference that won't
- * be dropped until after an RCU delay done after
- * turning ->mnt_ns NULL. So if we observe it
- * non-NULL under rcu_read_lock(), the reference
- * we are dropping is not the final one.
- */
- mnt_add_count(mnt, -1);
- rcu_read_unlock();
- return;
- }
- lock_mount_hash();
- /*
- * make sure that if __legitimize_mnt() has not seen us grab
- * mount_lock, we'll see their refcount increment here.
- */
- smp_mb();
- mnt_add_count(mnt, -1);
- count = mnt_get_count(mnt);
- if (count != 0) {
- WARN_ON(count < 0);
- rcu_read_unlock();
- unlock_mount_hash();
- return;
- }
- #ifdef CONFIG_KDP_NS
- if (unlikely(((struct kdp_mount *)mnt)->mnt->mnt_flags & MNT_DOOMED)) {
- #else
- if (unlikely(mnt->mnt.mnt_flags & MNT_DOOMED)) {
- #endif
- rcu_read_unlock();
- unlock_mount_hash();
- return;
- }
- #ifdef CONFIG_KDP_NS
- kdp_set_mnt_flags(((struct kdp_mount *)mnt)->mnt, MNT_DOOMED);
- #else
- mnt->mnt.mnt_flags |= MNT_DOOMED;
- #endif
- rcu_read_unlock();
- list_del(&mnt->mnt_instance);
- if (unlikely(!list_empty(&mnt->mnt_mounts))) {
- struct mount *p, *tmp;
- list_for_each_entry_safe(p, tmp, &mnt->mnt_mounts, mnt_child) {
- __put_mountpoint(unhash_mnt(p), &list);
- hlist_add_head(&p->mnt_umount, &mnt->mnt_stuck_children);
- }
- }
- unlock_mount_hash();
- shrink_dentry_list(&list);
- #ifdef CONFIG_KDP_NS
- if (likely(!(((struct kdp_mount *)mnt)->mnt->mnt_flags & MNT_INTERNAL))) {
- #else
- if (likely(!(mnt->mnt.mnt_flags & MNT_INTERNAL))) {
- #endif
- struct task_struct *task = current;
- if (likely(!(task->flags & PF_KTHREAD))) {
- init_task_work(&mnt->mnt_rcu, __cleanup_mnt);
- if (!task_work_add(task, &mnt->mnt_rcu, TWA_RESUME))
- return;
- }
- if (llist_add(&mnt->mnt_llist, &delayed_mntput_list))
- schedule_delayed_work(&delayed_mntput_work, 1);
- return;
- }
- cleanup_mnt(mnt);
- }
- void mntput(struct vfsmount *mnt)
- {
- if (mnt) {
- struct mount *m = real_mount(mnt);
- /* avoid cacheline pingpong, hope gcc doesn't get "smart" */
- if (unlikely(m->mnt_expiry_mark))
- m->mnt_expiry_mark = 0;
- mntput_no_expire(m);
- }
- }
- EXPORT_SYMBOL(mntput);
- struct vfsmount *mntget(struct vfsmount *mnt)
- {
- if (mnt)
- mnt_add_count(real_mount(mnt), 1);
- return mnt;
- }
- EXPORT_SYMBOL(mntget);
- /**
- * path_is_mountpoint() - Check if path is a mount in the current namespace.
- * @path: path to check
- *
- * d_mountpoint() can only be used reliably to establish if a dentry is
- * not mounted in any namespace and that common case is handled inline.
- * d_mountpoint() isn't aware of the possibility there may be multiple
- * mounts using a given dentry in a different namespace. This function
- * checks if the passed in path is a mountpoint rather than the dentry
- * alone.
- */
- bool path_is_mountpoint(const struct path *path)
- {
- unsigned seq;
- bool res;
- if (!d_mountpoint(path->dentry))
- return false;
- rcu_read_lock();
- do {
- seq = read_seqbegin(&mount_lock);
- res = __path_is_mountpoint(path);
- } while (read_seqretry(&mount_lock, seq));
- rcu_read_unlock();
- return res;
- }
- EXPORT_SYMBOL(path_is_mountpoint);
- struct vfsmount *mnt_clone_internal(const struct path *path)
- {
- struct mount *p;
- p = clone_mnt(real_mount(path->mnt), path->dentry, CL_PRIVATE);
- if (IS_ERR(p))
- return ERR_CAST(p);
- #ifdef CONFIG_KDP_NS
- kdp_set_mnt_flags(((struct kdp_mount *)p)->mnt, MNT_INTERNAL);
- return ((struct kdp_mount *)p)->mnt;
- #else
- p->mnt.mnt_flags |= MNT_INTERNAL;
- return &p->mnt;
- #endif
- }
- #ifdef CONFIG_PROC_FS
- static struct mount *mnt_list_next(struct mnt_namespace *ns,
- struct list_head *p)
- {
- struct mount *mnt, *ret = NULL;
- lock_ns_list(ns);
- list_for_each_continue(p, &ns->list) {
- mnt = list_entry(p, typeof(*mnt), mnt_list);
- if (!mnt_is_cursor(mnt)) {
- ret = mnt;
- break;
- }
- }
- unlock_ns_list(ns);
- return ret;
- }
- /* iterator; we want it to have access to namespace_sem, thus here... */
- static void *m_start(struct seq_file *m, loff_t *pos)
- {
- struct proc_mounts *p = m->private;
- struct list_head *prev;
- down_read(&namespace_sem);
- if (!*pos) {
- prev = &p->ns->list;
- } else {
- prev = &p->cursor.mnt_list;
- /* Read after we'd reached the end? */
- if (list_empty(prev))
- return NULL;
- }
- return mnt_list_next(p->ns, prev);
- }
- static void *m_next(struct seq_file *m, void *v, loff_t *pos)
- {
- struct proc_mounts *p = m->private;
- struct mount *mnt = v;
- ++*pos;
- return mnt_list_next(p->ns, &mnt->mnt_list);
- }
- static void m_stop(struct seq_file *m, void *v)
- {
- struct proc_mounts *p = m->private;
- struct mount *mnt = v;
- lock_ns_list(p->ns);
- if (mnt)
- list_move_tail(&p->cursor.mnt_list, &mnt->mnt_list);
- else
- list_del_init(&p->cursor.mnt_list);
- unlock_ns_list(p->ns);
- up_read(&namespace_sem);
- }
- static int m_show(struct seq_file *m, void *v)
- {
- struct proc_mounts *p = m->private;
- struct mount *r = v;
- #ifdef CONFIG_KDP_NS
- return p->show(m, ((struct kdp_mount *)r)->mnt);
- #else
- return p->show(m, &r->mnt);
- #endif
- }
- const struct seq_operations mounts_op = {
- .start = m_start,
- .next = m_next,
- .stop = m_stop,
- .show = m_show,
- };
- void mnt_cursor_del(struct mnt_namespace *ns, struct mount *cursor)
- {
- down_read(&namespace_sem);
- lock_ns_list(ns);
- list_del(&cursor->mnt_list);
- unlock_ns_list(ns);
- up_read(&namespace_sem);
- }
- #endif /* CONFIG_PROC_FS */
- /**
- * may_umount_tree - check if a mount tree is busy
- * @m: root of mount tree
- *
- * This is called to check if a tree of mounts has any
- * open files, pwds, chroots or sub mounts that are
- * busy.
- */
- int may_umount_tree(struct vfsmount *m)
- {
- struct mount *mnt = real_mount(m);
- int actual_refs = 0;
- int minimum_refs = 0;
- struct mount *p;
- BUG_ON(!m);
- /* write lock needed for mnt_get_count */
- lock_mount_hash();
- for (p = mnt; p; p = next_mnt(p, mnt)) {
- actual_refs += mnt_get_count(p);
- minimum_refs += 2;
- }
- unlock_mount_hash();
- if (actual_refs > minimum_refs)
- return 0;
- return 1;
- }
- EXPORT_SYMBOL(may_umount_tree);
- /**
- * may_umount - check if a mount point is busy
- * @mnt: root of mount
- *
- * This is called to check if a mount point has any
- * open files, pwds, chroots or sub mounts. If the
- * mount has sub mounts this will return busy
- * regardless of whether the sub mounts are busy.
- *
- * Doesn't take quota and stuff into account. IOW, in some cases it will
- * give false negatives. The main reason why it's here is that we need
- * a non-destructive way to look for easily umountable filesystems.
- */
- int may_umount(struct vfsmount *mnt)
- {
- int ret = 1;
- down_read(&namespace_sem);
- lock_mount_hash();
- if (propagate_mount_busy(real_mount(mnt), 2))
- ret = 0;
- unlock_mount_hash();
- up_read(&namespace_sem);
- return ret;
- }
- EXPORT_SYMBOL(may_umount);
- static void namespace_unlock(void)
- {
- struct hlist_head head;
- struct hlist_node *p;
- struct mount *m;
- LIST_HEAD(list);
- hlist_move_list(&unmounted, &head);
- list_splice_init(&ex_mountpoints, &list);
- up_write(&namespace_sem);
- shrink_dentry_list(&list);
- if (likely(hlist_empty(&head)))
- return;
- synchronize_rcu_expedited();
- hlist_for_each_entry_safe(m, p, &head, mnt_umount) {
- hlist_del(&m->mnt_umount);
- #ifdef CONFIG_KDP_NS
- mntput(((struct kdp_mount *)m)->mnt);
- #else
- mntput(&m->mnt);
- #endif
- }
- }
- static inline void namespace_lock(void)
- {
- down_write(&namespace_sem);
- }
- enum umount_tree_flags {
- UMOUNT_SYNC = 1,
- UMOUNT_PROPAGATE = 2,
- UMOUNT_CONNECTED = 4,
- };
- static bool disconnect_mount(struct mount *mnt, enum umount_tree_flags how)
- {
- /* Leaving mounts connected is only valid for lazy umounts */
- if (how & UMOUNT_SYNC)
- return true;
- /* A mount without a parent has nothing to be connected to */
- if (!mnt_has_parent(mnt))
- return true;
- /* Because the reference counting rules change when mounts are
- * unmounted and connected, umounted mounts may not be
- * connected to mounted mounts.
- */
- #ifdef CONFIG_KDP_NS
- if (!(((struct kdp_mount *)mnt->mnt_parent)->mnt->mnt_flags & MNT_UMOUNT))
- #else
- if (!(mnt->mnt_parent->mnt.mnt_flags & MNT_UMOUNT))
- #endif
- return true;
- /* Has it been requested that the mount remain connected? */
- if (how & UMOUNT_CONNECTED)
- return false;
- /* Is the mount locked such that it needs to remain connected? */
- if (IS_MNT_LOCKED(mnt))
- return false;
- /* By default disconnect the mount */
- return true;
- }
- /*
- * mount_lock must be held
- * namespace_sem must be held for write
- */
- static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
- {
- LIST_HEAD(tmp_list);
- struct mount *p;
- if (how & UMOUNT_PROPAGATE)
- propagate_mount_unlock(mnt);
- /* Gather the mounts to umount */
- for (p = mnt; p; p = next_mnt(p, mnt)) {
- #ifdef CONFIG_KDP_NS
- kdp_set_mnt_flags(((struct kdp_mount *)p)->mnt, MNT_UMOUNT);
- #else
- p->mnt.mnt_flags |= MNT_UMOUNT;
- #endif
- list_move(&p->mnt_list, &tmp_list);
- }
- /* Hide the mounts from mnt_mounts */
- list_for_each_entry(p, &tmp_list, mnt_list) {
- list_del_init(&p->mnt_child);
- }
- /* Add propogated mounts to the tmp_list */
- if (how & UMOUNT_PROPAGATE)
- propagate_umount(&tmp_list);
- while (!list_empty(&tmp_list)) {
- struct mnt_namespace *ns;
- bool disconnect;
- p = list_first_entry(&tmp_list, struct mount, mnt_list);
- list_del_init(&p->mnt_expire);
- list_del_init(&p->mnt_list);
- ns = p->mnt_ns;
- if (ns) {
- ns->mounts--;
- __touch_mnt_namespace(ns);
- }
- p->mnt_ns = NULL;
- if (how & UMOUNT_SYNC)
- #ifdef CONFIG_KDP_NS
- kdp_set_mnt_flags(((struct kdp_mount *)p)->mnt, MNT_SYNC_UMOUNT);
- #else
- p->mnt.mnt_flags |= MNT_SYNC_UMOUNT;
- #endif
- disconnect = disconnect_mount(p, how);
- if (mnt_has_parent(p)) {
- mnt_add_count(p->mnt_parent, -1);
- if (!disconnect) {
- /* Don't forget about p */
- list_add_tail(&p->mnt_child, &p->mnt_parent->mnt_mounts);
- } else {
- umount_mnt(p);
- }
- }
- change_mnt_propagation(p, MS_PRIVATE);
- if (disconnect)
- hlist_add_head(&p->mnt_umount, &unmounted);
- }
- }
- static void shrink_submounts(struct mount *mnt);
- static int do_umount_root(struct super_block *sb)
- {
- int ret = 0;
- down_write(&sb->s_umount);
- if (!sb_rdonly(sb)) {
- struct fs_context *fc;
- fc = fs_context_for_reconfigure(sb->s_root, SB_RDONLY,
- SB_RDONLY);
- if (IS_ERR(fc)) {
- ret = PTR_ERR(fc);
- } else {
- ret = parse_monolithic_mount_data(fc, NULL);
- if (!ret)
- ret = reconfigure_super(fc);
- put_fs_context(fc);
- }
- }
- up_write(&sb->s_umount);
- return ret;
- }
- static int do_umount(struct mount *mnt, int flags)
- {
- #ifdef CONFIG_KDP_NS
- struct super_block *sb = ((struct kdp_mount *)mnt)->mnt->mnt_sb;
- #else
- struct super_block *sb = mnt->mnt.mnt_sb;
- #endif
- int retval;
- #ifdef CONFIG_KDP_NS
- retval = security_sb_umount(((struct kdp_mount *)mnt)->mnt, flags);
- #else
- retval = security_sb_umount(&mnt->mnt, flags);
- #endif
- if (retval)
- return retval;
- /*
- * Allow userspace to request a mountpoint be expired rather than
- * unmounting unconditionally. Unmount only happens if:
- * (1) the mark is already set (the mark is cleared by mntput())
- * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount]
- */
- if (flags & MNT_EXPIRE) {
- #ifdef CONFIG_KDP_NS
- if (((struct kdp_mount *)mnt)->mnt == current->fs->root.mnt ||
- #else
- if (&mnt->mnt == current->fs->root.mnt ||
- #endif
- flags & (MNT_FORCE | MNT_DETACH))
- return -EINVAL;
- /*
- * probably don't strictly need the lock here if we examined
- * all race cases, but it's a slowpath.
- */
- lock_mount_hash();
- if (mnt_get_count(mnt) != 2) {
- unlock_mount_hash();
- return -EBUSY;
- }
- unlock_mount_hash();
- if (!xchg(&mnt->mnt_expiry_mark, 1))
- return -EAGAIN;
- }
- /*
- * If we may have to abort operations to get out of this
- * mount, and they will themselves hold resources we must
- * allow the fs to do things. In the Unix tradition of
- * 'Gee thats tricky lets do it in userspace' the umount_begin
- * might fail to complete on the first run through as other tasks
- * must return, and the like. Thats for the mount program to worry
- * about for the moment.
- */
- if (flags & MNT_FORCE && sb->s_op->umount_begin) {
- sb->s_op->umount_begin(sb);
- }
- /*
- * No sense to grab the lock for this test, but test itself looks
- * somewhat bogus. Suggestions for better replacement?
- * Ho-hum... In principle, we might treat that as umount + switch
- * to rootfs. GC would eventually take care of the old vfsmount.
- * Actually it makes sense, especially if rootfs would contain a
- * /reboot - static binary that would close all descriptors and
- * call reboot(9). Then init(8) could umount root and exec /reboot.
- */
- #ifdef CONFIG_KDP_NS
- if (((struct kdp_mount *)mnt)->mnt == current->fs->root.mnt && !(flags & MNT_DETACH)) {
- #else
- if (&mnt->mnt == current->fs->root.mnt && !(flags & MNT_DETACH)) {
- #endif
- /*
- * Special case for "unmounting" root ...
- * we just try to remount it readonly.
- */
- if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN))
- return -EPERM;
- return do_umount_root(sb);
- }
- namespace_lock();
- lock_mount_hash();
- /* Recheck MNT_LOCKED with the locks held */
- retval = -EINVAL;
- #ifdef CONFIG_KDP_NS
- if (((struct kdp_mount *)mnt)->mnt->mnt_flags & MNT_LOCKED)
- #else
- if (mnt->mnt.mnt_flags & MNT_LOCKED)
- #endif
- goto out;
- event++;
- if (flags & MNT_DETACH) {
- if (!list_empty(&mnt->mnt_list))
- umount_tree(mnt, UMOUNT_PROPAGATE);
- retval = 0;
- } else {
- shrink_submounts(mnt);
- retval = -EBUSY;
- if (!propagate_mount_busy(mnt, 2)) {
- if (!list_empty(&mnt->mnt_list))
- umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC);
- retval = 0;
- }
- }
- out:
- unlock_mount_hash();
- namespace_unlock();
- return retval;
- }
- /*
- * __detach_mounts - lazily unmount all mounts on the specified dentry
- *
- * During unlink, rmdir, and d_drop it is possible to loose the path
- * to an existing mountpoint, and wind up leaking the mount.
- * detach_mounts allows lazily unmounting those mounts instead of
- * leaking them.
- *
- * The caller may hold dentry->d_inode->i_mutex.
- */
- void __detach_mounts(struct dentry *dentry)
- {
- struct mountpoint *mp;
- struct mount *mnt;
- namespace_lock();
- lock_mount_hash();
- mp = lookup_mountpoint(dentry);
- if (!mp)
- goto out_unlock;
- event++;
- while (!hlist_empty(&mp->m_list)) {
- mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list);
- #ifdef CONFIG_KDP_NS
- if (((struct kdp_mount *)mnt)->mnt->mnt_flags & MNT_UMOUNT) {
- #else
- if (mnt->mnt.mnt_flags & MNT_UMOUNT) {
- #endif
- umount_mnt(mnt);
- hlist_add_head(&mnt->mnt_umount, &unmounted);
- }
- else umount_tree(mnt, UMOUNT_CONNECTED);
- }
- put_mountpoint(mp);
- out_unlock:
- unlock_mount_hash();
- namespace_unlock();
- }
- /*
- * Is the caller allowed to modify his namespace?
- */
- bool may_mount(void)
- {
- return ns_capable(current->nsproxy->mnt_ns->user_ns, CAP_SYS_ADMIN);
- }
- static void warn_mandlock(void)
- {
- pr_warn_once("=======================================================\n"
- "WARNING: The mand mount option has been deprecated and\n"
- " and is ignored by this kernel. Remove the mand\n"
- " option from the mount to silence this warning.\n"
- "=======================================================\n");
- }
- static int can_umount(const struct path *path, int flags)
- {
- struct mount *mnt = real_mount(path->mnt);
- if (!may_mount())
- return -EPERM;
- if (path->dentry != path->mnt->mnt_root)
- return -EINVAL;
- if (!check_mnt(mnt))
- return -EINVAL;
- #ifdef CONFIG_KDP_NS
- if (((struct kdp_mount *)mnt)->mnt->mnt_flags & MNT_LOCKED)
- #else
- if (mnt->mnt.mnt_flags & MNT_LOCKED) /* Check optimistically */
- #endif
- return -EINVAL;
- if (flags & MNT_FORCE && !capable(CAP_SYS_ADMIN))
- return -EPERM;
- return 0;
- }
- // caller is responsible for flags being sane
- int path_umount(struct path *path, int flags)
- {
- struct mount *mnt = real_mount(path->mnt);
- int ret;
- ret = can_umount(path, flags);
- if (!ret)
- ret = do_umount(mnt, flags);
- /* we mustn't call path_put() as that would clear mnt_expiry_mark */
- dput(path->dentry);
- mntput_no_expire(mnt);
- return ret;
- }
- static int ksys_umount(char __user *name, int flags)
- {
- int lookup_flags = LOOKUP_MOUNTPOINT;
- struct path path;
- int ret;
- // basic validity checks done first
- if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW))
- return -EINVAL;
- if (!(flags & UMOUNT_NOFOLLOW))
- lookup_flags |= LOOKUP_FOLLOW;
- ret = user_path_at(AT_FDCWD, name, lookup_flags, &path);
- if (ret)
- return ret;
- return path_umount(&path, flags);
- }
- SYSCALL_DEFINE2(umount, char __user *, name, int, flags)
- {
- return ksys_umount(name, flags);
- }
- #ifdef __ARCH_WANT_SYS_OLDUMOUNT
- /*
- * The 2.0 compatible umount. No flags.
- */
- SYSCALL_DEFINE1(oldumount, char __user *, name)
- {
- return ksys_umount(name, 0);
- }
- #endif
- static bool is_mnt_ns_file(struct dentry *dentry)
- {
- /* Is this a proxy for a mount namespace? */
- return dentry->d_op == &ns_dentry_operations &&
- dentry->d_fsdata == &mntns_operations;
- }
- static struct mnt_namespace *to_mnt_ns(struct ns_common *ns)
- {
- return container_of(ns, struct mnt_namespace, ns);
- }
- struct ns_common *from_mnt_ns(struct mnt_namespace *mnt)
- {
- return &mnt->ns;
- }
- static bool mnt_ns_loop(struct dentry *dentry)
- {
- /* Could bind mounting the mount namespace inode cause a
- * mount namespace loop?
- */
- struct mnt_namespace *mnt_ns;
- if (!is_mnt_ns_file(dentry))
- return false;
- mnt_ns = to_mnt_ns(get_proc_ns(dentry->d_inode));
- return current->nsproxy->mnt_ns->seq >= mnt_ns->seq;
- }
- struct mount *copy_tree(struct mount *mnt, struct dentry *dentry,
- int flag)
- {
- struct mount *res, *p, *q, *r, *parent;
- if (!(flag & CL_COPY_UNBINDABLE) && IS_MNT_UNBINDABLE(mnt))
- return ERR_PTR(-EINVAL);
- if (!(flag & CL_COPY_MNT_NS_FILE) && is_mnt_ns_file(dentry))
- return ERR_PTR(-EINVAL);
- res = q = clone_mnt(mnt, dentry, flag);
- if (IS_ERR(q))
- return q;
- q->mnt_mountpoint = mnt->mnt_mountpoint;
- p = mnt;
- list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) {
- struct mount *s;
- if (!is_subdir(r->mnt_mountpoint, dentry))
- continue;
- for (s = r; s; s = next_mnt(s, r)) {
- if (!(flag & CL_COPY_UNBINDABLE) &&
- IS_MNT_UNBINDABLE(s)) {
- #ifdef CONFIG_KDP_NS
- if (((struct kdp_mount *)s)->mnt->mnt_flags & MNT_LOCKED) {
- #else
- if (s->mnt.mnt_flags & MNT_LOCKED) {
- #endif
- /* Both unbindable and locked. */
- q = ERR_PTR(-EPERM);
- goto out;
- } else {
- s = skip_mnt_tree(s);
- continue;
- }
- }
- if (!(flag & CL_COPY_MNT_NS_FILE) &&
- #ifdef CONFIG_KDP_NS
- is_mnt_ns_file(((struct kdp_mount *)s)->mnt->mnt_root)) {
- #else
- is_mnt_ns_file(s->mnt.mnt_root)) {
- #endif
- s = skip_mnt_tree(s);
- continue;
- }
- while (p != s->mnt_parent) {
- p = p->mnt_parent;
- q = q->mnt_parent;
- }
- p = s;
- parent = q;
- #ifdef CONFIG_KDP_NS
- q = clone_mnt(p, ((struct kdp_mount *)p)->mnt->mnt_root, flag);
- #else
- q = clone_mnt(p, p->mnt.mnt_root, flag);
- #endif
- if (IS_ERR(q))
- goto out;
- lock_mount_hash();
- list_add_tail(&q->mnt_list, &res->mnt_list);
- attach_mnt(q, parent, p->mnt_mp);
- unlock_mount_hash();
- }
- }
- return res;
- out:
- if (res) {
- lock_mount_hash();
- umount_tree(res, UMOUNT_SYNC);
- unlock_mount_hash();
- }
- return q;
- }
- /* Caller should check returned pointer for errors */
- struct vfsmount *collect_mounts(const struct path *path)
- {
- struct mount *tree;
- namespace_lock();
- if (!check_mnt(real_mount(path->mnt)))
- tree = ERR_PTR(-EINVAL);
- else
- tree = copy_tree(real_mount(path->mnt), path->dentry,
- CL_COPY_ALL | CL_PRIVATE);
- namespace_unlock();
- if (IS_ERR(tree))
- return ERR_CAST(tree);
- #ifdef CONFIG_KDP_NS
- return ((struct kdp_mount *)tree)->mnt;
- #else
- return &tree->mnt;
- #endif
- }
- static void free_mnt_ns(struct mnt_namespace *);
- static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *, bool);
- void dissolve_on_fput(struct vfsmount *mnt)
- {
- struct mnt_namespace *ns;
- namespace_lock();
- lock_mount_hash();
- ns = real_mount(mnt)->mnt_ns;
- if (ns) {
- if (is_anon_ns(ns))
- umount_tree(real_mount(mnt), UMOUNT_CONNECTED);
- else
- ns = NULL;
- }
- unlock_mount_hash();
- namespace_unlock();
- if (ns)
- free_mnt_ns(ns);
- }
- void drop_collected_mounts(struct vfsmount *mnt)
- {
- namespace_lock();
- lock_mount_hash();
- umount_tree(real_mount(mnt), 0);
- unlock_mount_hash();
- namespace_unlock();
- }
- static bool has_locked_children(struct mount *mnt, struct dentry *dentry)
- {
- struct mount *child;
- list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) {
- if (!is_subdir(child->mnt_mountpoint, dentry))
- continue;
- #ifdef CONFIG_KDP_NS
- if (((struct kdp_mount *)child)->mnt->mnt_flags & MNT_LOCKED)
- #else
- if (child->mnt.mnt_flags & MNT_LOCKED)
- #endif
- return true;
- }
- return false;
- }
- /**
- * clone_private_mount - create a private clone of a path
- * @path: path to clone
- *
- * This creates a new vfsmount, which will be the clone of @path. The new mount
- * will not be attached anywhere in the namespace and will be private (i.e.
- * changes to the originating mount won't be propagated into this).
- *
- * Release with mntput().
- */
- struct vfsmount *clone_private_mount(const struct path *path)
- {
- struct mount *old_mnt = real_mount(path->mnt);
- struct mount *new_mnt;
- down_read(&namespace_sem);
- if (IS_MNT_UNBINDABLE(old_mnt))
- goto invalid;
- if (!check_mnt(old_mnt))
- goto invalid;
- if (has_locked_children(old_mnt, path->dentry))
- goto invalid;
- new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE);
- up_read(&namespace_sem);
- if (IS_ERR(new_mnt))
- return ERR_CAST(new_mnt);
- /* Longterm mount to be removed by kern_unmount*() */
- #ifdef CONFIG_KDP_NS
- ((struct kdp_mount *)new_mnt)->mount.mnt_ns = MNT_NS_INTERNAL;
-
- return ((struct kdp_mount *)new_mnt)->mnt;
- #else
- new_mnt->mnt_ns = MNT_NS_INTERNAL;
- return &new_mnt->mnt;
- #endif
- invalid:
- up_read(&namespace_sem);
- return ERR_PTR(-EINVAL);
- }
- EXPORT_SYMBOL_GPL(clone_private_mount);
- int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg,
- struct vfsmount *root)
- {
- struct mount *mnt;
- int res = f(root, arg);
- if (res)
- return res;
- list_for_each_entry(mnt, &real_mount(root)->mnt_list, mnt_list) {
- #ifdef CONFIG_KDP_NS
- res = f(((struct kdp_mount *)mnt)->mnt, arg);
- #else
- res = f(&mnt->mnt, arg);
- #endif
- if (res)
- return res;
- }
- return 0;
- }
- static void lock_mnt_tree(struct mount *mnt)
- {
- struct mount *p;
- for (p = mnt; p; p = next_mnt(p, mnt)) {
- #ifdef CONFIG_KDP_NS
- int flags = ((struct kdp_mount *)p)->mnt->mnt_flags;
- #else
- int flags = p->mnt.mnt_flags;
- #endif
- /* Don't allow unprivileged users to change mount flags */
- flags |= MNT_LOCK_ATIME;
- if (flags & MNT_READONLY)
- flags |= MNT_LOCK_READONLY;
- if (flags & MNT_NODEV)
- flags |= MNT_LOCK_NODEV;
- if (flags & MNT_NOSUID)
- flags |= MNT_LOCK_NOSUID;
- if (flags & MNT_NOEXEC)
- flags |= MNT_LOCK_NOEXEC;
- /* Don't allow unprivileged users to reveal what is under a mount */
- if (list_empty(&p->mnt_expire))
- flags |= MNT_LOCKED;
- #ifdef CONFIG_KDP_NS
- kdp_assign_mnt_flags(((struct kdp_mount *)p)->mnt, flags);
- #else
- p->mnt.mnt_flags = flags;
- #endif
- }
- }
- static void cleanup_group_ids(struct mount *mnt, struct mount *end)
- {
- struct mount *p;
- for (p = mnt; p != end; p = next_mnt(p, mnt)) {
- if (p->mnt_group_id && !IS_MNT_SHARED(p))
- mnt_release_group_id(p);
- }
- }
- static int invent_group_ids(struct mount *mnt, bool recurse)
- {
- struct mount *p;
- for (p = mnt; p; p = recurse ? next_mnt(p, mnt) : NULL) {
- if (!p->mnt_group_id && !IS_MNT_SHARED(p)) {
- int err = mnt_alloc_group_id(p);
- if (err) {
- cleanup_group_ids(mnt, p);
- return err;
- }
- }
- }
- return 0;
- }
- int count_mounts(struct mnt_namespace *ns, struct mount *mnt)
- {
- unsigned int max = READ_ONCE(sysctl_mount_max);
- unsigned int mounts = 0;
- struct mount *p;
- if (ns->mounts >= max)
- return -ENOSPC;
- max -= ns->mounts;
- if (ns->pending_mounts >= max)
- return -ENOSPC;
- max -= ns->pending_mounts;
- for (p = mnt; p; p = next_mnt(p, mnt))
- mounts++;
- if (mounts > max)
- return -ENOSPC;
- ns->pending_mounts += mounts;
- return 0;
- }
- /*
- * @source_mnt : mount tree to be attached
- * @nd : place the mount tree @source_mnt is attached
- * @parent_nd : if non-null, detach the source_mnt from its parent and
- * store the parent mount and mountpoint dentry.
- * (done when source_mnt is moved)
- *
- * NOTE: in the table below explains the semantics when a source mount
- * of a given type is attached to a destination mount of a given type.
- * ---------------------------------------------------------------------------
- * | BIND MOUNT OPERATION |
- * |**************************************************************************
- * | source-->| shared | private | slave | unbindable |
- * | dest | | | | |
- * | | | | | | |
- * | v | | | | |
- * |**************************************************************************
- * | shared | shared (++) | shared (+) | shared(+++)| invalid |
- * | | | | | |
- * |non-shared| shared (+) | private | slave (*) | invalid |
- * ***************************************************************************
- * A bind operation clones the source mount and mounts the clone on the
- * destination mount.
- *
- * (++) the cloned mount is propagated to all the mounts in the propagation
- * tree of the destination mount and the cloned mount is added to
- * the peer group of the source mount.
- * (+) the cloned mount is created under the destination mount and is marked
- * as shared. The cloned mount is added to the peer group of the source
- * mount.
- * (+++) the mount is propagated to all the mounts in the propagation tree
- * of the destination mount and the cloned mount is made slave
- * of the same master as that of the source mount. The cloned mount
- * is marked as 'shared and slave'.
- * (*) the cloned mount is made a slave of the same master as that of the
- * source mount.
- *
- * ---------------------------------------------------------------------------
- * | MOVE MOUNT OPERATION |
- * |**************************************************************************
- * | source-->| shared | private | slave | unbindable |
- * | dest | | | | |
- * | | | | | | |
- * | v | | | | |
- * |**************************************************************************
- * | shared | shared (+) | shared (+) | shared(+++) | invalid |
- * | | | | | |
- * |non-shared| shared (+*) | private | slave (*) | unbindable |
- * ***************************************************************************
- *
- * (+) the mount is moved to the destination. And is then propagated to
- * all the mounts in the propagation tree of the destination mount.
- * (+*) the mount is moved to the destination.
- * (+++) the mount is moved to the destination and is then propagated to
- * all the mounts belonging to the destination mount's propagation tree.
- * the mount is marked as 'shared and slave'.
- * (*) the mount continues to be a slave at the new location.
- *
- * if the source mount is a tree, the operations explained above is
- * applied to each mount in the tree.
- * Must be called without spinlocks held, since this function can sleep
- * in allocations.
- */
- static int attach_recursive_mnt(struct mount *source_mnt,
- struct mount *dest_mnt,
- struct mountpoint *dest_mp,
- bool moving)
- {
- struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns;
- HLIST_HEAD(tree_list);
- struct mnt_namespace *ns = dest_mnt->mnt_ns;
- struct mountpoint *smp;
- struct mount *child, *p;
- struct hlist_node *n;
- int err;
- /* Preallocate a mountpoint in case the new mounts need
- * to be tucked under other mounts.
- */
- #ifdef CONFIG_KDP_NS
- int nsflags;
- smp = get_mountpoint(((struct kdp_mount *)source_mnt)->mnt->mnt_root);
- #else
- smp = get_mountpoint(source_mnt->mnt.mnt_root);
- #endif
- if (IS_ERR(smp))
- return PTR_ERR(smp);
- /* Is there space to add these mounts to the mount namespace? */
- if (!moving) {
- err = count_mounts(ns, source_mnt);
- if (err)
- goto out;
- }
- if (IS_MNT_SHARED(dest_mnt)) {
- err = invent_group_ids(source_mnt, true);
- if (err)
- goto out;
- err = propagate_mnt(dest_mnt, dest_mp, source_mnt, &tree_list);
- lock_mount_hash();
- if (err)
- goto out_cleanup_ids;
- for (p = source_mnt; p; p = next_mnt(p, source_mnt))
- set_mnt_shared(p);
- } else {
- lock_mount_hash();
- }
- if (moving) {
- unhash_mnt(source_mnt);
- attach_mnt(source_mnt, dest_mnt, dest_mp);
- touch_mnt_namespace(source_mnt->mnt_ns);
- } else {
- if (source_mnt->mnt_ns) {
- /* move from anon - the caller will destroy */
- list_del_init(&source_mnt->mnt_ns->list);
- }
- mnt_set_mountpoint(dest_mnt, dest_mp, source_mnt);
- commit_tree(source_mnt);
- }
- hlist_for_each_entry_safe(child, n, &tree_list, mnt_hash) {
- struct mount *q;
- hlist_del_init(&child->mnt_hash);
- #ifdef CONFIG_KDP_NS
- q = __lookup_mnt(((struct kdp_mount *)child->mnt_parent)->mnt,
- #else
- q = __lookup_mnt(&child->mnt_parent->mnt,
- #endif
- child->mnt_mountpoint);
- if (q)
- mnt_change_mountpoint(child, smp, q);
- /* Notice when we are propagating across user namespaces */
- if (child->mnt_parent->mnt_ns->user_ns != user_ns)
- lock_mnt_tree(child);
- #ifdef CONFIG_KDP_NS
- nsflags = ((struct kdp_mount *)child)->mnt->mnt_flags & ~MNT_LOCKED;
- kdp_assign_mnt_flags(((struct kdp_mount *)child)->mnt, nsflags);
- #else
- child->mnt.mnt_flags &= ~MNT_LOCKED;
- #endif
- commit_tree(child);
- }
- put_mountpoint(smp);
- unlock_mount_hash();
- return 0;
- out_cleanup_ids:
- while (!hlist_empty(&tree_list)) {
- child = hlist_entry(tree_list.first, struct mount, mnt_hash);
- child->mnt_parent->mnt_ns->pending_mounts = 0;
- umount_tree(child, UMOUNT_SYNC);
- }
- unlock_mount_hash();
- cleanup_group_ids(source_mnt, NULL);
- out:
- ns->pending_mounts = 0;
- read_seqlock_excl(&mount_lock);
- put_mountpoint(smp);
- read_sequnlock_excl(&mount_lock);
- return err;
- }
- static struct mountpoint *lock_mount(struct path *path)
- {
- struct vfsmount *mnt;
- struct dentry *dentry = path->dentry;
- retry:
- inode_lock(dentry->d_inode);
- if (unlikely(cant_mount(dentry))) {
- inode_unlock(dentry->d_inode);
- return ERR_PTR(-ENOENT);
- }
- namespace_lock();
- mnt = lookup_mnt(path);
- if (likely(!mnt)) {
- struct mountpoint *mp = get_mountpoint(dentry);
- if (IS_ERR(mp)) {
- namespace_unlock();
- inode_unlock(dentry->d_inode);
- return mp;
- }
- return mp;
- }
- namespace_unlock();
- inode_unlock(path->dentry->d_inode);
- path_put(path);
- path->mnt = mnt;
- dentry = path->dentry = dget(mnt->mnt_root);
- goto retry;
- }
- static void unlock_mount(struct mountpoint *where)
- {
- struct dentry *dentry = where->m_dentry;
- read_seqlock_excl(&mount_lock);
- put_mountpoint(where);
- read_sequnlock_excl(&mount_lock);
- namespace_unlock();
- inode_unlock(dentry->d_inode);
- }
- static int graft_tree(struct mount *mnt, struct mount *p, struct mountpoint *mp)
- {
- #ifdef CONFIG_KDP_NS
- if (((struct kdp_mount *)mnt)->mnt->mnt_sb->s_flags & SB_NOUSER)
- #else
- if (mnt->mnt.mnt_sb->s_flags & SB_NOUSER)
- #endif
- return -EINVAL;
- if (d_is_dir(mp->m_dentry) !=
- #ifdef CONFIG_KDP_NS
- d_is_dir(((struct kdp_mount *)mnt)->mnt->mnt_root))
- #else
- d_is_dir(mnt->mnt.mnt_root))
- #endif
- return -ENOTDIR;
- return attach_recursive_mnt(mnt, p, mp, false);
- }
- /*
- * Sanity check the flags to change_mnt_propagation.
- */
- static int flags_to_propagation_type(int ms_flags)
- {
- int type = ms_flags & ~(MS_REC | MS_SILENT);
- /* Fail if any non-propagation flags are set */
- if (type & ~(MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE))
- return 0;
- /* Only one propagation flag should be set */
- if (!is_power_of_2(type))
- return 0;
- return type;
- }
- /*
- * recursively change the type of the mountpoint.
- */
- static int do_change_type(struct path *path, int ms_flags)
- {
- struct mount *m;
- struct mount *mnt = real_mount(path->mnt);
- int recurse = ms_flags & MS_REC;
- int type;
- int err = 0;
- if (path->dentry != path->mnt->mnt_root)
- return -EINVAL;
- type = flags_to_propagation_type(ms_flags);
- if (!type)
- return -EINVAL;
- namespace_lock();
- if (type == MS_SHARED) {
- err = invent_group_ids(mnt, recurse);
- if (err)
- goto out_unlock;
- }
- lock_mount_hash();
- for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL))
- change_mnt_propagation(m, type);
- unlock_mount_hash();
- out_unlock:
- namespace_unlock();
- return err;
- }
- static struct mount *__do_loopback(struct path *old_path, int recurse)
- {
- struct mount *mnt = ERR_PTR(-EINVAL), *old = real_mount(old_path->mnt);
- #ifdef CONFIG_KDP_NS
- int nsflags;
- #endif
- if (IS_MNT_UNBINDABLE(old))
- return mnt;
- if (!check_mnt(old) && old_path->dentry->d_op != &ns_dentry_operations)
- return mnt;
- if (!recurse && has_locked_children(old, old_path->dentry))
- return mnt;
- if (recurse)
- mnt = copy_tree(old, old_path->dentry, CL_COPY_MNT_NS_FILE);
- else
- mnt = clone_mnt(old, old_path->dentry, 0);
- #ifdef CONFIG_KDP_NS
- if (!IS_ERR(mnt)) {
- nsflags = ((struct kdp_mount *)mnt)->mnt->mnt_flags & ~MNT_LOCKED;
- kdp_assign_mnt_flags(((struct kdp_mount *)mnt)->mnt, nsflags);
- }
- #else
- if (!IS_ERR(mnt))
- mnt->mnt.mnt_flags &= ~MNT_LOCKED;
- #endif
- return mnt;
- }
- /*
- * do loopback mount.
- */
- static int do_loopback(struct path *path, const char *old_name,
- int recurse)
- {
- struct path old_path;
- struct mount *mnt = NULL, *parent;
- struct mountpoint *mp;
- int err;
- if (!old_name || !*old_name)
- return -EINVAL;
- err = kern_path(old_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path);
- if (err)
- return err;
- err = -EINVAL;
- if (mnt_ns_loop(old_path.dentry))
- goto out;
- mp = lock_mount(path);
- if (IS_ERR(mp)) {
- err = PTR_ERR(mp);
- goto out;
- }
- parent = real_mount(path->mnt);
- if (!check_mnt(parent))
- goto out2;
- mnt = __do_loopback(&old_path, recurse);
- if (IS_ERR(mnt)) {
- err = PTR_ERR(mnt);
- goto out2;
- }
- err = graft_tree(mnt, parent, mp);
- if (err) {
- lock_mount_hash();
- umount_tree(mnt, UMOUNT_SYNC);
- unlock_mount_hash();
- }
- #if defined(CONFIG_KSU_SUSFS_AUTO_ADD_SUS_BIND_MOUNT) || defined(CONFIG_KSU_SUSFS_AUTO_ADD_TRY_UMOUNT_FOR_BIND_MOUNT)
- // Check if bind mounted path should be hidden and umounted automatically.
- // And we target only process with ksu domain.
- if (susfs_is_current_ksu_domain()) {
- #if defined(CONFIG_KSU_SUSFS_AUTO_ADD_SUS_BIND_MOUNT)
- if (susfs_is_auto_add_sus_bind_mount_enabled &&
- susfs_auto_add_sus_bind_mount(old_name, &old_path)) {
- goto orig_flow;
- }
- #endif
- #if defined(CONFIG_KSU_SUSFS_AUTO_ADD_TRY_UMOUNT_FOR_BIND_MOUNT)
- if (susfs_is_auto_add_try_umount_for_bind_mount_enabled) {
- susfs_auto_add_try_umount_for_bind_mount(path);
- }
- #endif
- }
- #if defined(CONFIG_KSU_SUSFS_AUTO_ADD_SUS_BIND_MOUNT)
- orig_flow:
- #endif
- #endif // #if defined(CONFIG_KSU_SUSFS_AUTO_ADD_SUS_BIND_MOUNT) || defined(CONFIG_KSU_SUSFS_AUTO_ADD_TRY_UMOUNT_FOR_BIND_MOUNT)
- out2:
- unlock_mount(mp);
- out:
- path_put(&old_path);
- return err;
- }
- static struct file *open_detached_copy(struct path *path, bool recursive)
- {
- struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns;
- struct mnt_namespace *ns = alloc_mnt_ns(user_ns, true);
- struct mount *mnt, *p;
- struct file *file;
- if (IS_ERR(ns))
- return ERR_CAST(ns);
- namespace_lock();
- mnt = __do_loopback(path, recursive);
- if (IS_ERR(mnt)) {
- namespace_unlock();
- free_mnt_ns(ns);
- return ERR_CAST(mnt);
- }
- lock_mount_hash();
- for (p = mnt; p; p = next_mnt(p, mnt)) {
- p->mnt_ns = ns;
- ns->mounts++;
- }
- ns->root = mnt;
- list_add_tail(&ns->list, &mnt->mnt_list);
- #ifdef CONFIG_KDP_NS
- mntget(((struct kdp_mount *)mnt)->mnt);
- unlock_mount_hash();
- namespace_unlock();
- mntput(path->mnt);
- path->mnt = ((struct kdp_mount *)mnt)->mnt;
- #else
- mntget(&mnt->mnt);
- unlock_mount_hash();
- namespace_unlock();
- mntput(path->mnt);
- path->mnt = &mnt->mnt;
- #endif
- file = dentry_open(path, O_PATH, current_cred());
- if (IS_ERR(file))
- dissolve_on_fput(path->mnt);
- else
- file->f_mode |= FMODE_NEED_UNMOUNT;
- return file;
- }
- SYSCALL_DEFINE3(open_tree, int, dfd, const char __user *, filename, unsigned, flags)
- {
- struct file *file;
- struct path path;
- int lookup_flags = LOOKUP_AUTOMOUNT | LOOKUP_FOLLOW;
- bool detached = flags & OPEN_TREE_CLONE;
- int error;
- int fd;
- BUILD_BUG_ON(OPEN_TREE_CLOEXEC != O_CLOEXEC);
- if (flags & ~(AT_EMPTY_PATH | AT_NO_AUTOMOUNT | AT_RECURSIVE |
- AT_SYMLINK_NOFOLLOW | OPEN_TREE_CLONE |
- OPEN_TREE_CLOEXEC))
- return -EINVAL;
- if ((flags & (AT_RECURSIVE | OPEN_TREE_CLONE)) == AT_RECURSIVE)
- return -EINVAL;
- if (flags & AT_NO_AUTOMOUNT)
- lookup_flags &= ~LOOKUP_AUTOMOUNT;
- if (flags & AT_SYMLINK_NOFOLLOW)
- lookup_flags &= ~LOOKUP_FOLLOW;
- if (flags & AT_EMPTY_PATH)
- lookup_flags |= LOOKUP_EMPTY;
- if (detached && !may_mount())
- return -EPERM;
- fd = get_unused_fd_flags(flags & O_CLOEXEC);
- if (fd < 0)
- return fd;
- error = user_path_at(dfd, filename, lookup_flags, &path);
- if (unlikely(error)) {
- file = ERR_PTR(error);
- } else {
- if (detached)
- file = open_detached_copy(&path, flags & AT_RECURSIVE);
- else
- file = dentry_open(&path, O_PATH, current_cred());
- path_put(&path);
- }
- if (IS_ERR(file)) {
- put_unused_fd(fd);
- return PTR_ERR(file);
- }
- fd_install(fd, file);
- return fd;
- }
- /*
- * Don't allow locked mount flags to be cleared.
- *
- * No locks need to be held here while testing the various MNT_LOCK
- * flags because those flags can never be cleared once they are set.
- */
- static bool can_change_locked_flags(struct mount *mnt, unsigned int mnt_flags)
- {
- #ifdef CONFIG_KDP_NS
- unsigned int fl = ((struct kdp_mount *)mnt)->mnt->mnt_flags;
- #else
- unsigned int fl = mnt->mnt.mnt_flags;
- #endif
- if ((fl & MNT_LOCK_READONLY) &&
- !(mnt_flags & MNT_READONLY))
- return false;
- if ((fl & MNT_LOCK_NODEV) &&
- !(mnt_flags & MNT_NODEV))
- return false;
- if ((fl & MNT_LOCK_NOSUID) &&
- !(mnt_flags & MNT_NOSUID))
- return false;
- if ((fl & MNT_LOCK_NOEXEC) &&
- !(mnt_flags & MNT_NOEXEC))
- return false;
- if ((fl & MNT_LOCK_ATIME) &&
- ((fl & MNT_ATIME_MASK) != (mnt_flags & MNT_ATIME_MASK)))
- return false;
- return true;
- }
- static int change_mount_ro_state(struct mount *mnt, unsigned int mnt_flags)
- {
- bool readonly_request = (mnt_flags & MNT_READONLY);
- #ifdef CONFIG_KDP_NS
- if (readonly_request == __mnt_is_readonly(((struct kdp_mount *)mnt)->mnt))
- #else
- if (readonly_request == __mnt_is_readonly(&mnt->mnt))
- #endif
- return 0;
- if (readonly_request)
- return mnt_make_readonly(mnt);
- #ifdef CONFIG_KDP_NS
- kdp_clear_mnt_flags(((struct kdp_mount *)mnt)->mnt, MNT_READONLY);
- #else
- mnt->mnt.mnt_flags &= ~MNT_READONLY;
- #endif
- return 0;
- }
- static void set_mount_attributes(struct mount *mnt, unsigned int mnt_flags)
- {
- #ifdef CONFIG_KDP_NS
- mnt_flags |= ((struct kdp_mount *)mnt)->mnt->mnt_flags & ~MNT_USER_SETTABLE_MASK;
- kdp_assign_mnt_flags(((struct kdp_mount *)mnt)->mnt, mnt_flags);
- #else
- mnt_flags |= mnt->mnt.mnt_flags & ~MNT_USER_SETTABLE_MASK;
- mnt->mnt.mnt_flags = mnt_flags;
- #endif
- touch_mnt_namespace(mnt->mnt_ns);
- }
- static void mnt_warn_timestamp_expiry(struct path *mountpoint, struct vfsmount *mnt)
- {
- struct super_block *sb = mnt->mnt_sb;
- if (!__mnt_is_readonly(mnt) &&
- (!(sb->s_iflags & SB_I_TS_EXPIRY_WARNED)) &&
- (ktime_get_real_seconds() + TIME_UPTIME_SEC_MAX > sb->s_time_max)) {
- char *buf = (char *)__get_free_page(GFP_KERNEL);
- char *mntpath = buf ? d_path(mountpoint, buf, PAGE_SIZE) : ERR_PTR(-ENOMEM);
- struct tm tm;
- time64_to_tm(sb->s_time_max, 0, &tm);
- pr_warn("%s filesystem being %s at %s supports timestamps until %04ld (0x%llx)\n",
- sb->s_type->name,
- is_mounted(mnt) ? "remounted" : "mounted",
- mntpath,
- tm.tm_year+1900, (unsigned long long)sb->s_time_max);
- free_page((unsigned long)buf);
- sb->s_iflags |= SB_I_TS_EXPIRY_WARNED;
- }
- }
- /*
- * Handle reconfiguration of the mountpoint only without alteration of the
- * superblock it refers to. This is triggered by specifying MS_REMOUNT|MS_BIND
- * to mount(2).
- */
- static int do_reconfigure_mnt(struct path *path, unsigned int mnt_flags)
- {
- struct super_block *sb = path->mnt->mnt_sb;
- struct mount *mnt = real_mount(path->mnt);
- int ret;
- if (!check_mnt(mnt))
- return -EINVAL;
- #ifdef CONFIG_KDP_NS
- if (path->dentry != ((struct kdp_mount *)mnt)->mnt->mnt_root)
- #else
- if (path->dentry != mnt->mnt.mnt_root)
- #endif
- return -EINVAL;
- if (!can_change_locked_flags(mnt, mnt_flags))
- return -EPERM;
- /*
- * We're only checking whether the superblock is read-only not
- * changing it, so only take down_read(&sb->s_umount).
- */
- down_read(&sb->s_umount);
- lock_mount_hash();
- ret = change_mount_ro_state(mnt, mnt_flags);
- if (ret == 0)
- set_mount_attributes(mnt, mnt_flags);
- unlock_mount_hash();
- up_read(&sb->s_umount);
- #ifdef CONFIG_KDP_NS
- mnt_warn_timestamp_expiry(path, ((struct kdp_mount *)mnt)->mnt);
- #else
- mnt_warn_timestamp_expiry(path, &mnt->mnt);
- #endif
- return ret;
- }
- /*
- * change filesystem flags. dir should be a physical root of filesystem.
- * If you've mounted a non-root directory somewhere and want to do remount
- * on it - tough luck.
- */
- static int do_remount(struct path *path, int ms_flags, int sb_flags,
- int mnt_flags, void *data)
- {
- int err;
- struct super_block *sb = path->mnt->mnt_sb;
- struct mount *mnt = real_mount(path->mnt);
- struct fs_context *fc;
- if (!check_mnt(mnt))
- return -EINVAL;
- if (path->dentry != path->mnt->mnt_root)
- return -EINVAL;
- if (!can_change_locked_flags(mnt, mnt_flags))
- return -EPERM;
- fc = fs_context_for_reconfigure(path->dentry, sb_flags, MS_RMT_MASK);
- if (IS_ERR(fc))
- return PTR_ERR(fc);
- fc->oldapi = true;
- err = parse_monolithic_mount_data(fc, data);
- if (!err) {
- down_write(&sb->s_umount);
- err = -EPERM;
- if (ns_capable(sb->s_user_ns, CAP_SYS_ADMIN)) {
- err = reconfigure_super(fc);
- if (!err) {
- lock_mount_hash();
- set_mount_attributes(mnt, mnt_flags);
- unlock_mount_hash();
- }
- }
- up_write(&sb->s_umount);
- }
- #ifdef CONFIG_KDP_NS
- mnt_warn_timestamp_expiry(path, ((struct kdp_mount *)mnt)->mnt);
- #else
- mnt_warn_timestamp_expiry(path, &mnt->mnt);
- #endif
- put_fs_context(fc);
- return err;
- }
- static inline int tree_contains_unbindable(struct mount *mnt)
- {
- struct mount *p;
- for (p = mnt; p; p = next_mnt(p, mnt)) {
- if (IS_MNT_UNBINDABLE(p))
- return 1;
- }
- return 0;
- }
- /*
- * Check that there aren't references to earlier/same mount namespaces in the
- * specified subtree. Such references can act as pins for mount namespaces
- * that aren't checked by the mount-cycle checking code, thereby allowing
- * cycles to be made.
- */
- static bool check_for_nsfs_mounts(struct mount *subtree)
- {
- struct mount *p;
- bool ret = false;
- lock_mount_hash();
- for (p = subtree; p; p = next_mnt(p, subtree))
- #ifdef CONFIG_KDP_NS
- if (mnt_ns_loop(((struct kdp_mount *)p)->mnt->mnt_root))
- #else
- if (mnt_ns_loop(p->mnt.mnt_root))
- #endif
- goto out;
- ret = true;
- out:
- unlock_mount_hash();
- return ret;
- }
- static int do_set_group(struct path *from_path, struct path *to_path)
- {
- struct mount *from, *to;
- int err;
- from = real_mount(from_path->mnt);
- to = real_mount(to_path->mnt);
- namespace_lock();
- err = -EINVAL;
- /* To and From must be mounted */
- #ifdef CONFIG_KDP_NS
- if (!is_mounted(((struct kdp_mount *)from)->mnt))
- goto out;
- if (!is_mounted(((struct kdp_mount *)to)->mnt))
- goto out;
- #else
- if (!is_mounted(&from->mnt))
- goto out;
- if (!is_mounted(&to->mnt))
- goto out;
- #endif
- err = -EPERM;
- /* We should be allowed to modify mount namespaces of both mounts */
- if (!ns_capable(from->mnt_ns->user_ns, CAP_SYS_ADMIN))
- goto out;
- if (!ns_capable(to->mnt_ns->user_ns, CAP_SYS_ADMIN))
- goto out;
- err = -EINVAL;
- /* To and From paths should be mount roots */
- if (from_path->dentry != from_path->mnt->mnt_root)
- goto out;
- if (to_path->dentry != to_path->mnt->mnt_root)
- goto out;
- #ifdef CONFIG_KDP_NS
- /* Setting sharing groups is only allowed across same superblock */
- if (((struct kdp_mount *)from)->mnt->mnt_sb != ((struct kdp_mount *)to)->mnt->mnt_sb)
- goto out;
- /* From mount root should be wider than To mount root */
- if (!is_subdir(((struct kdp_mount *)to)->mnt->mnt_root, ((struct kdp_mount *)from)->mnt->mnt_root))
- goto out;
- /* From mount should not have locked children in place of To's root */
- if (has_locked_children(from, ((struct kdp_mount *)to)->mnt->mnt_root))
- goto out;
- #else
- /* Setting sharing groups is only allowed across same superblock */
- if (from->mnt.mnt_sb != to->mnt.mnt_sb)
- goto out;
- /* From mount root should be wider than To mount root */
- if (!is_subdir(to->mnt.mnt_root, from->mnt.mnt_root))
- goto out;
- /* From mount should not have locked children in place of To's root */
- if (has_locked_children(from, to->mnt.mnt_root))
- goto out;
- #endif
- /* Setting sharing groups is only allowed on private mounts */
- if (IS_MNT_SHARED(to) || IS_MNT_SLAVE(to))
- goto out;
- /* From should not be private */
- if (!IS_MNT_SHARED(from) && !IS_MNT_SLAVE(from))
- goto out;
- if (IS_MNT_SLAVE(from)) {
- struct mount *m = from->mnt_master;
- list_add(&to->mnt_slave, &m->mnt_slave_list);
- to->mnt_master = m;
- }
- if (IS_MNT_SHARED(from)) {
- to->mnt_group_id = from->mnt_group_id;
- list_add(&to->mnt_share, &from->mnt_share);
- lock_mount_hash();
- set_mnt_shared(to);
- unlock_mount_hash();
- }
- err = 0;
- out:
- namespace_unlock();
- return err;
- }
- static int do_move_mount(struct path *old_path, struct path *new_path)
- {
- struct mnt_namespace *ns;
- struct mount *p;
- struct mount *old;
- struct mount *parent;
- struct mountpoint *mp, *old_mp;
- int err;
- bool attached;
- mp = lock_mount(new_path);
- if (IS_ERR(mp))
- return PTR_ERR(mp);
- old = real_mount(old_path->mnt);
- p = real_mount(new_path->mnt);
- parent = old->mnt_parent;
- attached = mnt_has_parent(old);
- old_mp = old->mnt_mp;
- ns = old->mnt_ns;
- err = -EINVAL;
- /* The mountpoint must be in our namespace. */
- if (!check_mnt(p))
- goto out;
- /* The thing moved must be mounted... */
- #ifdef CONFIG_KDP_NS
- if (!is_mounted(((struct kdp_mount *)old)->mnt))
- #else
- if (!is_mounted(&old->mnt))
- #endif
- goto out;
- /* ... and either ours or the root of anon namespace */
- if (!(attached ? check_mnt(old) : is_anon_ns(ns)))
- goto out;
- #ifdef CONFIG_KDP_NS
- if (((struct kdp_mount *)old)->mnt->mnt_flags & MNT_LOCKED)
- #else
- if (old->mnt.mnt_flags & MNT_LOCKED)
- #endif
- goto out;
- if (old_path->dentry != old_path->mnt->mnt_root)
- goto out;
- if (d_is_dir(new_path->dentry) !=
- d_is_dir(old_path->dentry))
- goto out;
- /*
- * Don't move a mount residing in a shared parent.
- */
- if (attached && IS_MNT_SHARED(parent))
- goto out;
- /*
- * Don't move a mount tree containing unbindable mounts to a destination
- * mount which is shared.
- */
- if (IS_MNT_SHARED(p) && tree_contains_unbindable(old))
- goto out;
- err = -ELOOP;
- if (!check_for_nsfs_mounts(old))
- goto out;
- for (; mnt_has_parent(p); p = p->mnt_parent)
- if (p == old)
- goto out;
- err = attach_recursive_mnt(old, real_mount(new_path->mnt), mp,
- attached);
- if (err)
- goto out;
- /* if the mount is moved, it should no longer be expire
- * automatically */
- list_del_init(&old->mnt_expire);
- if (attached)
- put_mountpoint(old_mp);
- out:
- unlock_mount(mp);
- if (!err) {
- if (attached)
- mntput_no_expire(parent);
- else
- free_mnt_ns(ns);
- }
- return err;
- }
- static int do_move_mount_old(struct path *path, const char *old_name)
- {
- struct path old_path;
- int err;
- if (!old_name || !*old_name)
- return -EINVAL;
- err = kern_path(old_name, LOOKUP_FOLLOW, &old_path);
- if (err)
- return err;
- err = do_move_mount(&old_path, path);
- path_put(&old_path);
- return err;
- }
- /*
- * add a mount into a namespace's mount tree
- */
- static int do_add_mount(struct mount *newmnt, struct mountpoint *mp,
- const struct path *path, int mnt_flags)
- {
- struct mount *parent = real_mount(path->mnt);
- mnt_flags &= ~MNT_INTERNAL_FLAGS;
- if (unlikely(!check_mnt(parent))) {
- /* that's acceptable only for automounts done in private ns */
- if (!(mnt_flags & MNT_SHRINKABLE))
- return -EINVAL;
- /* ... and for those we'd better have mountpoint still alive */
- if (!parent->mnt_ns)
- return -EINVAL;
- }
- /* Refuse the same filesystem on the same mount point */
- #ifdef CONFIG_KDP_NS
- if (path->mnt->mnt_sb == ((struct kdp_mount *)newmnt)->mnt->mnt_sb &&
- #else
- if (path->mnt->mnt_sb == newmnt->mnt.mnt_sb &&
- #endif
- path->mnt->mnt_root == path->dentry)
- return -EBUSY;
- #ifdef CONFIG_KDP_NS
- if (d_is_symlink(((struct kdp_mount *)newmnt)->mnt->mnt_root))
- #else
- if (d_is_symlink(newmnt->mnt.mnt_root))
- #endif
- return -EINVAL;
- #ifdef CONFIG_KDP_NS
- kdp_assign_mnt_flags(((struct kdp_mount *)newmnt)->mnt, mnt_flags);
- #else
- newmnt->mnt.mnt_flags = mnt_flags;
- #endif
- return graft_tree(newmnt, parent, mp);
- }
- static bool mount_too_revealing(const struct super_block *sb, int *new_mnt_flags);
- /*
- * Create a new mount using a superblock configuration and request it
- * be added to the namespace tree.
- */
- static int do_new_mount_fc(struct fs_context *fc, struct path *mountpoint,
- unsigned int mnt_flags)
- {
- struct vfsmount *mnt;
- struct mountpoint *mp;
- struct super_block *sb = fc->root->d_sb;
- int error;
- error = security_sb_kern_mount(sb);
- if (!error && mount_too_revealing(sb, &mnt_flags))
- error = -EPERM;
- if (unlikely(error)) {
- fc_drop_locked(fc);
- return error;
- }
- up_write(&sb->s_umount);
- mnt = vfs_create_mount(fc);
- if (IS_ERR(mnt))
- return PTR_ERR(mnt);
- mnt_warn_timestamp_expiry(mountpoint, mnt);
- mp = lock_mount(mountpoint);
- if (IS_ERR(mp)) {
- mntput(mnt);
- return PTR_ERR(mp);
- }
- error = do_add_mount(real_mount(mnt), mp, mountpoint, mnt_flags);
- unlock_mount(mp);
- if (error < 0)
- mntput(mnt);
- return error;
- }
- /*
- * create a new mount for userspace and request it to be added into the
- * namespace's tree
- */
- static int do_new_mount(struct path *path, const char *fstype, int sb_flags,
- int mnt_flags, const char *name, void *data)
- {
- struct file_system_type *type;
- struct fs_context *fc;
- const char *subtype = NULL;
- int err = 0;
- if (!fstype)
- return -EINVAL;
- type = get_fs_type(fstype);
- if (!type)
- return -ENODEV;
- if (type->fs_flags & FS_HAS_SUBTYPE) {
- subtype = strchr(fstype, '.');
- if (subtype) {
- subtype++;
- if (!*subtype) {
- put_filesystem(type);
- return -EINVAL;
- }
- }
- }
- fc = fs_context_for_mount(type, sb_flags);
- put_filesystem(type);
- if (IS_ERR(fc))
- return PTR_ERR(fc);
- if (subtype)
- err = vfs_parse_fs_string(fc, "subtype",
- subtype, strlen(subtype));
- if (!err && name)
- err = vfs_parse_fs_string(fc, "source", name, strlen(name));
- if (!err)
- err = parse_monolithic_mount_data(fc, data);
- if (!err && !mount_capable(fc))
- err = -EPERM;
- if (!err)
- err = vfs_get_tree(fc);
- if (!err)
- err = do_new_mount_fc(fc, path, mnt_flags);
- put_fs_context(fc);
- return err;
- }
- int finish_automount(struct vfsmount *m, const struct path *path)
- {
- struct dentry *dentry = path->dentry;
- struct mountpoint *mp;
- struct mount *mnt;
- int err;
- if (!m)
- return 0;
- if (IS_ERR(m))
- return PTR_ERR(m);
- mnt = real_mount(m);
- /* The new mount record should have at least 2 refs to prevent it being
- * expired before we get a chance to add it
- */
- BUG_ON(mnt_get_count(mnt) < 2);
- if (m->mnt_sb == path->mnt->mnt_sb &&
- m->mnt_root == dentry) {
- err = -ELOOP;
- goto discard;
- }
- /*
- * we don't want to use lock_mount() - in this case finding something
- * that overmounts our mountpoint to be means "quitely drop what we've
- * got", not "try to mount it on top".
- */
- inode_lock(dentry->d_inode);
- namespace_lock();
- if (unlikely(cant_mount(dentry))) {
- err = -ENOENT;
- goto discard_locked;
- }
- rcu_read_lock();
- if (unlikely(__lookup_mnt(path->mnt, dentry))) {
- rcu_read_unlock();
- err = 0;
- goto discard_locked;
- }
- rcu_read_unlock();
- mp = get_mountpoint(dentry);
- if (IS_ERR(mp)) {
- err = PTR_ERR(mp);
- goto discard_locked;
- }
- err = do_add_mount(mnt, mp, path, path->mnt->mnt_flags | MNT_SHRINKABLE);
- unlock_mount(mp);
- if (unlikely(err))
- goto discard;
- mntput(m);
- return 0;
- discard_locked:
- namespace_unlock();
- inode_unlock(dentry->d_inode);
- discard:
- /* remove m from any expiration list it may be on */
- if (!list_empty(&mnt->mnt_expire)) {
- namespace_lock();
- list_del_init(&mnt->mnt_expire);
- namespace_unlock();
- }
- mntput(m);
- mntput(m);
- return err;
- }
- /**
- * mnt_set_expiry - Put a mount on an expiration list
- * @mnt: The mount to list.
- * @expiry_list: The list to add the mount to.
- */
- void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list)
- {
- namespace_lock();
- list_add_tail(&real_mount(mnt)->mnt_expire, expiry_list);
- namespace_unlock();
- }
- EXPORT_SYMBOL(mnt_set_expiry);
- /*
- * process a list of expirable mountpoints with the intent of discarding any
- * mountpoints that aren't in use and haven't been touched since last we came
- * here
- */
- void mark_mounts_for_expiry(struct list_head *mounts)
- {
- struct mount *mnt, *next;
- LIST_HEAD(graveyard);
- if (list_empty(mounts))
- return;
- namespace_lock();
- lock_mount_hash();
- /* extract from the expiration list every vfsmount that matches the
- * following criteria:
- * - only referenced by its parent vfsmount
- * - still marked for expiry (marked on the last call here; marks are
- * cleared by mntput())
- */
- list_for_each_entry_safe(mnt, next, mounts, mnt_expire) {
- if (!xchg(&mnt->mnt_expiry_mark, 1) ||
- propagate_mount_busy(mnt, 1))
- continue;
- list_move(&mnt->mnt_expire, &graveyard);
- }
- while (!list_empty(&graveyard)) {
- mnt = list_first_entry(&graveyard, struct mount, mnt_expire);
- touch_mnt_namespace(mnt->mnt_ns);
- umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC);
- }
- unlock_mount_hash();
- namespace_unlock();
- }
- EXPORT_SYMBOL_GPL(mark_mounts_for_expiry);
- /*
- * Ripoff of 'select_parent()'
- *
- * search the list of submounts for a given mountpoint, and move any
- * shrinkable submounts to the 'graveyard' list.
- */
- static int select_submounts(struct mount *parent, struct list_head *graveyard)
- {
- struct mount *this_parent = parent;
- struct list_head *next;
- int found = 0;
- repeat:
- next = this_parent->mnt_mounts.next;
- resume:
- while (next != &this_parent->mnt_mounts) {
- struct list_head *tmp = next;
- struct mount *mnt = list_entry(tmp, struct mount, mnt_child);
- next = tmp->next;
- #ifdef CONFIG_KDP_NS
- if (!(((struct kdp_mount *)mnt)->mnt->mnt_flags & MNT_SHRINKABLE))
- #else
- if (!(mnt->mnt.mnt_flags & MNT_SHRINKABLE))
- #endif
- continue;
- /*
- * Descend a level if the d_mounts list is non-empty.
- */
- if (!list_empty(&mnt->mnt_mounts)) {
- this_parent = mnt;
- goto repeat;
- }
- if (!propagate_mount_busy(mnt, 1)) {
- list_move_tail(&mnt->mnt_expire, graveyard);
- found++;
- }
- }
- /*
- * All done at this level ... ascend and resume the search
- */
- if (this_parent != parent) {
- next = this_parent->mnt_child.next;
- this_parent = this_parent->mnt_parent;
- goto resume;
- }
- return found;
- }
- /*
- * process a list of expirable mountpoints with the intent of discarding any
- * submounts of a specific parent mountpoint
- *
- * mount_lock must be held for write
- */
- static void shrink_submounts(struct mount *mnt)
- {
- LIST_HEAD(graveyard);
- struct mount *m;
- /* extract submounts of 'mountpoint' from the expiration list */
- while (select_submounts(mnt, &graveyard)) {
- while (!list_empty(&graveyard)) {
- m = list_first_entry(&graveyard, struct mount,
- mnt_expire);
- touch_mnt_namespace(m->mnt_ns);
- umount_tree(m, UMOUNT_PROPAGATE|UMOUNT_SYNC);
- }
- }
- }
- static void *copy_mount_options(const void __user * data)
- {
- char *copy;
- unsigned left, offset;
- if (!data)
- return NULL;
- copy = kmalloc(PAGE_SIZE, GFP_KERNEL);
- if (!copy)
- return ERR_PTR(-ENOMEM);
- left = copy_from_user(copy, data, PAGE_SIZE);
- /*
- * Not all architectures have an exact copy_from_user(). Resort to
- * byte at a time.
- */
- offset = PAGE_SIZE - left;
- while (left) {
- char c;
- if (get_user(c, (const char __user *)data + offset))
- break;
- copy[offset] = c;
- left--;
- offset++;
- }
- if (left == PAGE_SIZE) {
- kfree(copy);
- return ERR_PTR(-EFAULT);
- }
- return copy;
- }
- static char *copy_mount_string(const void __user *data)
- {
- return data ? strndup_user(data, PATH_MAX) : NULL;
- }
- /*
- * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to
- * be given to the mount() call (ie: read-only, no-dev, no-suid etc).
- *
- * data is a (void *) that can point to any structure up to
- * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent
- * information (or be NULL).
- *
- * Pre-0.97 versions of mount() didn't have a flags word.
- * When the flags word was introduced its top half was required
- * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9.
- * Therefore, if this magic number is present, it carries no information
- * and must be discarded.
- */
- int path_mount(const char *dev_name, struct path *path,
- const char *type_page, unsigned long flags, void *data_page)
- {
- unsigned int mnt_flags = 0, sb_flags;
- int ret;
- /* Discard magic */
- if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
- flags &= ~MS_MGC_MSK;
- /* Basic sanity checks */
- if (data_page)
- ((char *)data_page)[PAGE_SIZE - 1] = 0;
- if (flags & MS_NOUSER)
- return -EINVAL;
- ret = security_sb_mount(dev_name, path, type_page, flags, data_page);
- if (ret)
- return ret;
- if (!may_mount())
- return -EPERM;
- if (flags & SB_MANDLOCK)
- warn_mandlock();
- /* Default to relatime unless overriden */
- if (!(flags & MS_NOATIME))
- mnt_flags |= MNT_RELATIME;
- /* Separate the per-mountpoint flags */
- if (flags & MS_NOSUID)
- mnt_flags |= MNT_NOSUID;
- if (flags & MS_NODEV)
- mnt_flags |= MNT_NODEV;
- if (flags & MS_NOEXEC)
- mnt_flags |= MNT_NOEXEC;
- if (flags & MS_NOATIME)
- mnt_flags |= MNT_NOATIME;
- if (flags & MS_NODIRATIME)
- mnt_flags |= MNT_NODIRATIME;
- if (flags & MS_STRICTATIME)
- mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME);
- if (flags & MS_RDONLY)
- mnt_flags |= MNT_READONLY;
- if (flags & MS_NOSYMFOLLOW)
- mnt_flags |= MNT_NOSYMFOLLOW;
- /* The default atime for remount is preservation */
- if ((flags & MS_REMOUNT) &&
- ((flags & (MS_NOATIME | MS_NODIRATIME | MS_RELATIME |
- MS_STRICTATIME)) == 0)) {
- mnt_flags &= ~MNT_ATIME_MASK;
- mnt_flags |= path->mnt->mnt_flags & MNT_ATIME_MASK;
- }
- sb_flags = flags & (SB_RDONLY |
- SB_SYNCHRONOUS |
- SB_MANDLOCK |
- SB_DIRSYNC |
- SB_SILENT |
- SB_POSIXACL |
- SB_LAZYTIME |
- SB_I_VERSION);
- if ((flags & (MS_REMOUNT | MS_BIND)) == (MS_REMOUNT | MS_BIND))
- return do_reconfigure_mnt(path, mnt_flags);
- if (flags & MS_REMOUNT)
- return do_remount(path, flags, sb_flags, mnt_flags, data_page);
- if (flags & MS_BIND)
- return do_loopback(path, dev_name, flags & MS_REC);
- if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE))
- return do_change_type(path, flags);
- if (flags & MS_MOVE)
- return do_move_mount_old(path, dev_name);
- return do_new_mount(path, type_page, sb_flags, mnt_flags, dev_name,
- data_page);
- }
- long do_mount(const char *dev_name, const char __user *dir_name,
- const char *type_page, unsigned long flags, void *data_page)
- {
- struct path path;
- int ret;
- ret = user_path_at(AT_FDCWD, dir_name, LOOKUP_FOLLOW, &path);
- if (ret)
- return ret;
- ret = path_mount(dev_name, &path, type_page, flags, data_page);
- path_put(&path);
- return ret;
- }
- static struct ucounts *inc_mnt_namespaces(struct user_namespace *ns)
- {
- return inc_ucount(ns, current_euid(), UCOUNT_MNT_NAMESPACES);
- }
- static void dec_mnt_namespaces(struct ucounts *ucounts)
- {
- dec_ucount(ucounts, UCOUNT_MNT_NAMESPACES);
- }
- static void free_mnt_ns(struct mnt_namespace *ns)
- {
- if (!is_anon_ns(ns))
- ns_free_inum(&ns->ns);
- dec_mnt_namespaces(ns->ucounts);
- put_user_ns(ns->user_ns);
- kfree(ns);
- }
- /*
- * Assign a sequence number so we can detect when we attempt to bind
- * mount a reference to an older mount namespace into the current
- * mount namespace, preventing reference counting loops. A 64bit
- * number incrementing at 10Ghz will take 12,427 years to wrap which
- * is effectively never, so we can ignore the possibility.
- */
- static atomic64_t mnt_ns_seq = ATOMIC64_INIT(1);
- static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns, bool anon)
- {
- struct mnt_namespace *new_ns;
- struct ucounts *ucounts;
- int ret;
- ucounts = inc_mnt_namespaces(user_ns);
- if (!ucounts)
- return ERR_PTR(-ENOSPC);
- new_ns = kzalloc(sizeof(struct mnt_namespace), GFP_KERNEL_ACCOUNT);
- if (!new_ns) {
- dec_mnt_namespaces(ucounts);
- return ERR_PTR(-ENOMEM);
- }
- if (!anon) {
- ret = ns_alloc_inum(&new_ns->ns);
- if (ret) {
- kfree(new_ns);
- dec_mnt_namespaces(ucounts);
- return ERR_PTR(ret);
- }
- }
- new_ns->ns.ops = &mntns_operations;
- if (!anon)
- new_ns->seq = atomic64_add_return(1, &mnt_ns_seq);
- refcount_set(&new_ns->ns.count, 1);
- INIT_LIST_HEAD(&new_ns->list);
- init_waitqueue_head(&new_ns->poll);
- spin_lock_init(&new_ns->ns_lock);
- new_ns->user_ns = get_user_ns(user_ns);
- new_ns->ucounts = ucounts;
- return new_ns;
- }
- __latent_entropy
- struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns,
- struct user_namespace *user_ns, struct fs_struct *new_fs)
- {
- struct mnt_namespace *new_ns;
- struct vfsmount *rootmnt = NULL, *pwdmnt = NULL;
- struct mount *p, *q;
- struct mount *old;
- struct mount *new;
- int copy_flags;
- #ifdef CONFIG_KSU_SUSFS_SUS_MOUNT
- bool is_zygote_pid = susfs_is_current_zygote_domain();
- int last_entry_mnt_id = 0;
- #endif
- BUG_ON(!ns);
- if (likely(!(flags & CLONE_NEWNS))) {
- get_mnt_ns(ns);
- return ns;
- }
- old = ns->root;
- new_ns = alloc_mnt_ns(user_ns, false);
- if (IS_ERR(new_ns))
- return new_ns;
- namespace_lock();
- /* First pass: copy the tree topology */
- copy_flags = CL_COPY_UNBINDABLE | CL_EXPIRE;
- if (user_ns != ns->user_ns)
- copy_flags |= CL_SHARED_TO_SLAVE;
- #ifdef CONFIG_KSU_SUSFS_SUS_MOUNT
- // Always let clone_mnt() in copy_tree() know it is from copy_mnt_ns()
- copy_flags |= CL_COPY_MNT_NS;
- if (is_zygote_pid) {
- // Let clone_mnt() in copy_tree() know copy_mnt_ns() is run by zygote process
- copy_flags |= CL_ZYGOTE_COPY_MNT_NS;
- }
- #endif
- #ifdef CONFIG_KDP_NS
- new = copy_tree(old, ((struct kdp_mount *)old)->mnt->mnt_root, copy_flags);
- #else
- new = copy_tree(old, old->mnt.mnt_root, copy_flags);
- #endif
- if (IS_ERR(new)) {
- namespace_unlock();
- free_mnt_ns(new_ns);
- return ERR_CAST(new);
- }
- if (user_ns != ns->user_ns) {
- lock_mount_hash();
- lock_mnt_tree(new);
- unlock_mount_hash();
- }
- new_ns->root = new;
- list_add_tail(&new_ns->list, &new->mnt_list);
- /*
- * Second pass: switch the tsk->fs->* elements and mark new vfsmounts
- * as belonging to new namespace. We have already acquired a private
- * fs_struct, so tsk->fs->lock is not needed.
- */
- p = old;
- q = new;
- while (p) {
- q->mnt_ns = new_ns;
- new_ns->mounts++;
- if (new_fs) {
- #ifdef CONFIG_KDP_NS
- if (((struct kdp_mount *)p)->mnt == new_fs->root.mnt) {
- new_fs->root.mnt = mntget(((struct kdp_mount *)q)->mnt);
- rootmnt = ((struct kdp_mount *)p)->mnt;
- #else
- if (&p->mnt == new_fs->root.mnt) {
- new_fs->root.mnt = mntget(&q->mnt);
- rootmnt = &p->mnt;
- #endif
- }
- #ifdef CONFIG_KDP_NS
- if (((struct kdp_mount *)p)->mnt == new_fs->pwd.mnt) {
- new_fs->pwd.mnt = mntget(((struct kdp_mount *)q)->mnt);
- pwdmnt = ((struct kdp_mount *)p)->mnt;
- #else
- if (&p->mnt == new_fs->pwd.mnt) {
- new_fs->pwd.mnt = mntget(&q->mnt);
- pwdmnt = &p->mnt;
- #endif
- }
- }
- p = next_mnt(p, old);
- q = next_mnt(q, new);
- if (!q)
- break;
- #ifdef CONFIG_KDP_NS
- while (((struct kdp_mount *)p)->mnt->mnt_root != ((struct kdp_mount *)q)->mnt->mnt_root)
- #else
- while (p->mnt.mnt_root != q->mnt.mnt_root)
- #endif
- p = next_mnt(p, old);
- }
- #ifdef CONFIG_KSU_SUSFS_SUS_MOUNT
- // current->susfs_last_fake_mnt_id -> to record last valid fake mnt_id to zygote pid
- // q->mnt.susfs_mnt_id_backup -> original mnt_id
- // q->mnt_id -> will be modified to the fake mnt_id
- // Here We are only interested in processes of which original mnt namespace belongs to zygote
- // Also we just make use of existing 'q' mount pointer, no need to delcare extra mount pointer
- if (is_zygote_pid) {
- last_entry_mnt_id = list_first_entry(&new_ns->list, struct mount, mnt_list)->mnt_id;
- list_for_each_entry(q, &new_ns->list, mnt_list) {
- if (unlikely(q->mnt_id >= DEFAULT_SUS_MNT_ID)) {
- continue;
- }
- q->mnt.susfs_mnt_id_backup = q->mnt_id;
- q->mnt_id = last_entry_mnt_id++;
- }
- }
- // Assign the 'last_entry_mnt_id' to 'current->susfs_last_fake_mnt_id' for later use.
- // should be fine here assuming zygote is forking/unsharing app in one single thread.
- // Or should we put a lock here?
- current->susfs_last_fake_mnt_id = last_entry_mnt_id;
- #endif
- namespace_unlock();
- if (rootmnt)
- mntput(rootmnt);
- if (pwdmnt)
- mntput(pwdmnt);
- return new_ns;
- }
- struct dentry *mount_subtree(struct vfsmount *m, const char *name)
- {
- struct mount *mnt = real_mount(m);
- struct mnt_namespace *ns;
- struct super_block *s;
- struct path path;
- int err;
- ns = alloc_mnt_ns(&init_user_ns, true);
- if (IS_ERR(ns)) {
- mntput(m);
- return ERR_CAST(ns);
- }
- mnt->mnt_ns = ns;
- ns->root = mnt;
- ns->mounts++;
- list_add(&mnt->mnt_list, &ns->list);
- err = vfs_path_lookup(m->mnt_root, m,
- name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path);
- put_mnt_ns(ns);
- if (err)
- return ERR_PTR(err);
- /* trade a vfsmount reference for active sb one */
- s = path.mnt->mnt_sb;
- atomic_inc(&s->s_active);
- mntput(path.mnt);
- /* lock the sucker */
- down_write(&s->s_umount);
- /* ... and return the root of (sub)tree on it */
- return path.dentry;
- }
- EXPORT_SYMBOL(mount_subtree);
- SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,
- char __user *, type, unsigned long, flags, void __user *, data)
- {
- int ret;
- char *kernel_type;
- char *kernel_dev;
- void *options;
- kernel_type = copy_mount_string(type);
- ret = PTR_ERR(kernel_type);
- if (IS_ERR(kernel_type))
- goto out_type;
- kernel_dev = copy_mount_string(dev_name);
- ret = PTR_ERR(kernel_dev);
- if (IS_ERR(kernel_dev))
- goto out_dev;
- options = copy_mount_options(data);
- ret = PTR_ERR(options);
- if (IS_ERR(options))
- goto out_data;
- ret = do_mount(kernel_dev, dir_name, kernel_type, flags, options);
- #if defined(CONFIG_KSU_SUSFS_AUTO_ADD_SUS_KSU_DEFAULT_MOUNT) && defined(CONFIG_KSU_SUSFS_HAS_MAGIC_MOUNT)
- // Just for the compatibility of Magic Mount KernelSU
- if (!ret && susfs_is_auto_add_sus_ksu_default_mount_enabled && susfs_is_current_ksu_domain()) {
- susfs_auto_add_sus_ksu_default_mount(dir_name);
- }
- #endif
- kfree(options);
- out_data:
- kfree(kernel_dev);
- out_dev:
- kfree(kernel_type);
- out_type:
- return ret;
- }
- #define FSMOUNT_VALID_FLAGS \
- (MOUNT_ATTR_RDONLY | MOUNT_ATTR_NOSUID | MOUNT_ATTR_NODEV | \
- MOUNT_ATTR_NOEXEC | MOUNT_ATTR__ATIME | MOUNT_ATTR_NODIRATIME | \
- MOUNT_ATTR_NOSYMFOLLOW)
- #define MOUNT_SETATTR_VALID_FLAGS (FSMOUNT_VALID_FLAGS | MOUNT_ATTR_IDMAP)
- #define MOUNT_SETATTR_PROPAGATION_FLAGS \
- (MS_UNBINDABLE | MS_PRIVATE | MS_SLAVE | MS_SHARED)
- static unsigned int attr_flags_to_mnt_flags(u64 attr_flags)
- {
- unsigned int mnt_flags = 0;
- if (attr_flags & MOUNT_ATTR_RDONLY)
- mnt_flags |= MNT_READONLY;
- if (attr_flags & MOUNT_ATTR_NOSUID)
- mnt_flags |= MNT_NOSUID;
- if (attr_flags & MOUNT_ATTR_NODEV)
- mnt_flags |= MNT_NODEV;
- if (attr_flags & MOUNT_ATTR_NOEXEC)
- mnt_flags |= MNT_NOEXEC;
- if (attr_flags & MOUNT_ATTR_NODIRATIME)
- mnt_flags |= MNT_NODIRATIME;
- if (attr_flags & MOUNT_ATTR_NOSYMFOLLOW)
- mnt_flags |= MNT_NOSYMFOLLOW;
- return mnt_flags;
- }
- /*
- * Create a kernel mount representation for a new, prepared superblock
- * (specified by fs_fd) and attach to an open_tree-like file descriptor.
- */
- SYSCALL_DEFINE3(fsmount, int, fs_fd, unsigned int, flags,
- unsigned int, attr_flags)
- {
- struct mnt_namespace *ns;
- struct fs_context *fc;
- struct file *file;
- struct path newmount;
- struct mount *mnt;
- struct fd f;
- unsigned int mnt_flags = 0;
- long ret;
- if (!may_mount())
- return -EPERM;
- if ((flags & ~(FSMOUNT_CLOEXEC)) != 0)
- return -EINVAL;
- if (attr_flags & ~FSMOUNT_VALID_FLAGS)
- return -EINVAL;
- mnt_flags = attr_flags_to_mnt_flags(attr_flags);
- switch (attr_flags & MOUNT_ATTR__ATIME) {
- case MOUNT_ATTR_STRICTATIME:
- break;
- case MOUNT_ATTR_NOATIME:
- mnt_flags |= MNT_NOATIME;
- break;
- case MOUNT_ATTR_RELATIME:
- mnt_flags |= MNT_RELATIME;
- break;
- default:
- return -EINVAL;
- }
- f = fdget(fs_fd);
- if (!f.file)
- return -EBADF;
- ret = -EINVAL;
- if (f.file->f_op != &fscontext_fops)
- goto err_fsfd;
- fc = f.file->private_data;
- ret = mutex_lock_interruptible(&fc->uapi_mutex);
- if (ret < 0)
- goto err_fsfd;
- /* There must be a valid superblock or we can't mount it */
- ret = -EINVAL;
- if (!fc->root)
- goto err_unlock;
- ret = -EPERM;
- if (mount_too_revealing(fc->root->d_sb, &mnt_flags)) {
- pr_warn("VFS: Mount too revealing\n");
- goto err_unlock;
- }
- ret = -EBUSY;
- if (fc->phase != FS_CONTEXT_AWAITING_MOUNT)
- goto err_unlock;
- if (fc->sb_flags & SB_MANDLOCK)
- warn_mandlock();
- newmount.mnt = vfs_create_mount(fc);
- if (IS_ERR(newmount.mnt)) {
- ret = PTR_ERR(newmount.mnt);
- goto err_unlock;
- }
- newmount.dentry = dget(fc->root);
- newmount.mnt->mnt_flags = mnt_flags;
- /* We've done the mount bit - now move the file context into more or
- * less the same state as if we'd done an fspick(). We don't want to
- * do any memory allocation or anything like that at this point as we
- * don't want to have to handle any errors incurred.
- */
- vfs_clean_context(fc);
- ns = alloc_mnt_ns(current->nsproxy->mnt_ns->user_ns, true);
- if (IS_ERR(ns)) {
- ret = PTR_ERR(ns);
- goto err_path;
- }
- mnt = real_mount(newmount.mnt);
- mnt->mnt_ns = ns;
- ns->root = mnt;
- ns->mounts = 1;
- list_add(&mnt->mnt_list, &ns->list);
- mntget(newmount.mnt);
- /* Attach to an apparent O_PATH fd with a note that we need to unmount
- * it, not just simply put it.
- */
- file = dentry_open(&newmount, O_PATH, fc->cred);
- if (IS_ERR(file)) {
- dissolve_on_fput(newmount.mnt);
- ret = PTR_ERR(file);
- goto err_path;
- }
- file->f_mode |= FMODE_NEED_UNMOUNT;
- ret = get_unused_fd_flags((flags & FSMOUNT_CLOEXEC) ? O_CLOEXEC : 0);
- if (ret >= 0)
- fd_install(ret, file);
- else
- fput(file);
- err_path:
- path_put(&newmount);
- err_unlock:
- mutex_unlock(&fc->uapi_mutex);
- err_fsfd:
- fdput(f);
- return ret;
- }
- /*
- * Move a mount from one place to another. In combination with
- * fsopen()/fsmount() this is used to install a new mount and in combination
- * with open_tree(OPEN_TREE_CLONE [| AT_RECURSIVE]) it can be used to copy
- * a mount subtree.
- *
- * Note the flags value is a combination of MOVE_MOUNT_* flags.
- */
- SYSCALL_DEFINE5(move_mount,
- int, from_dfd, const char __user *, from_pathname,
- int, to_dfd, const char __user *, to_pathname,
- unsigned int, flags)
- {
- struct path from_path, to_path;
- unsigned int lflags;
- int ret = 0;
- if (!may_mount())
- return -EPERM;
- if (flags & ~MOVE_MOUNT__MASK)
- return -EINVAL;
- /* If someone gives a pathname, they aren't permitted to move
- * from an fd that requires unmount as we can't get at the flag
- * to clear it afterwards.
- */
- lflags = 0;
- if (flags & MOVE_MOUNT_F_SYMLINKS) lflags |= LOOKUP_FOLLOW;
- if (flags & MOVE_MOUNT_F_AUTOMOUNTS) lflags |= LOOKUP_AUTOMOUNT;
- if (flags & MOVE_MOUNT_F_EMPTY_PATH) lflags |= LOOKUP_EMPTY;
- ret = user_path_at(from_dfd, from_pathname, lflags, &from_path);
- if (ret < 0)
- return ret;
- lflags = 0;
- if (flags & MOVE_MOUNT_T_SYMLINKS) lflags |= LOOKUP_FOLLOW;
- if (flags & MOVE_MOUNT_T_AUTOMOUNTS) lflags |= LOOKUP_AUTOMOUNT;
- if (flags & MOVE_MOUNT_T_EMPTY_PATH) lflags |= LOOKUP_EMPTY;
- ret = user_path_at(to_dfd, to_pathname, lflags, &to_path);
- if (ret < 0)
- goto out_from;
- ret = security_move_mount(&from_path, &to_path);
- if (ret < 0)
- goto out_to;
- if (flags & MOVE_MOUNT_SET_GROUP)
- ret = do_set_group(&from_path, &to_path);
- else
- ret = do_move_mount(&from_path, &to_path);
- out_to:
- path_put(&to_path);
- out_from:
- path_put(&from_path);
- #ifdef CONFIG_KSU_SUSFS_AUTO_ADD_SUS_KSU_DEFAULT_MOUNT
- // For Legacy KSU mount scheme
- if (!ret && susfs_is_auto_add_sus_ksu_default_mount_enabled && susfs_is_current_ksu_domain()) {
- susfs_auto_add_sus_ksu_default_mount(to_pathname);
- }
- #endif
- return ret;
- }
- /*
- * Return true if path is reachable from root
- *
- * namespace_sem or mount_lock is held
- */
- bool is_path_reachable(struct mount *mnt, struct dentry *dentry,
- const struct path *root)
- {
- #ifdef CONFIG_KDP_NS
- while (((struct kdp_mount *)mnt)->mnt != root->mnt && mnt_has_parent(mnt)) {
- #else
- while (&mnt->mnt != root->mnt && mnt_has_parent(mnt)) {
- #endif
- dentry = mnt->mnt_mountpoint;
- mnt = mnt->mnt_parent;
- }
- #ifdef CONFIG_KDP_NS
- return ((struct kdp_mount *)mnt)->mnt == root->mnt && is_subdir(dentry, root->dentry);
- #else
- return &mnt->mnt == root->mnt && is_subdir(dentry, root->dentry);
- #endif
- }
- bool path_is_under(const struct path *path1, const struct path *path2)
- {
- bool res;
- read_seqlock_excl(&mount_lock);
- res = is_path_reachable(real_mount(path1->mnt), path1->dentry, path2);
- read_sequnlock_excl(&mount_lock);
- return res;
- }
- EXPORT_SYMBOL(path_is_under);
- /*
- * pivot_root Semantics:
- * Moves the root file system of the current process to the directory put_old,
- * makes new_root as the new root file system of the current process, and sets
- * root/cwd of all processes which had them on the current root to new_root.
- *
- * Restrictions:
- * The new_root and put_old must be directories, and must not be on the
- * same file system as the current process root. The put_old must be
- * underneath new_root, i.e. adding a non-zero number of /.. to the string
- * pointed to by put_old must yield the same directory as new_root. No other
- * file system may be mounted on put_old. After all, new_root is a mountpoint.
- *
- * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem.
- * See Documentation/filesystems/ramfs-rootfs-initramfs.rst for alternatives
- * in this situation.
- *
- * Notes:
- * - we don't move root/cwd if they are not at the root (reason: if something
- * cared enough to change them, it's probably wrong to force them elsewhere)
- * - it's okay to pick a root that isn't the root of a file system, e.g.
- * /nfs/my_root where /nfs is the mount point. It must be a mountpoint,
- * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root
- * first.
- */
- SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
- const char __user *, put_old)
- {
- struct path new, old, root;
- struct mount *new_mnt, *root_mnt, *old_mnt, *root_parent, *ex_parent;
- struct mountpoint *old_mp, *root_mp;
- int error;
- if (!may_mount())
- return -EPERM;
- error = user_path_at(AT_FDCWD, new_root,
- LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &new);
- if (error)
- goto out0;
- error = user_path_at(AT_FDCWD, put_old,
- LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &old);
- if (error)
- goto out1;
- error = security_sb_pivotroot(&old, &new);
- if (error)
- goto out2;
- get_fs_root(current->fs, &root);
- old_mp = lock_mount(&old);
- error = PTR_ERR(old_mp);
- if (IS_ERR(old_mp))
- goto out3;
- error = -EINVAL;
- new_mnt = real_mount(new.mnt);
- root_mnt = real_mount(root.mnt);
- old_mnt = real_mount(old.mnt);
- ex_parent = new_mnt->mnt_parent;
- root_parent = root_mnt->mnt_parent;
- if (IS_MNT_SHARED(old_mnt) ||
- IS_MNT_SHARED(ex_parent) ||
- IS_MNT_SHARED(root_parent))
- goto out4;
- if (!check_mnt(root_mnt) || !check_mnt(new_mnt))
- goto out4;
- #ifdef CONFIG_KDP_NS
- if (((struct kdp_mount *)new_mnt)->mnt->mnt_flags & MNT_LOCKED)
- #else
- if (new_mnt->mnt.mnt_flags & MNT_LOCKED)
- #endif
- goto out4;
- error = -ENOENT;
- if (d_unlinked(new.dentry))
- goto out4;
- error = -EBUSY;
- if (new_mnt == root_mnt || old_mnt == root_mnt)
- goto out4; /* loop, on the same file system */
- error = -EINVAL;
- if (root.mnt->mnt_root != root.dentry)
- goto out4; /* not a mountpoint */
- if (!mnt_has_parent(root_mnt))
- goto out4; /* not attached */
- if (new.mnt->mnt_root != new.dentry)
- goto out4; /* not a mountpoint */
- if (!mnt_has_parent(new_mnt))
- goto out4; /* not attached */
- /* make sure we can reach put_old from new_root */
- if (!is_path_reachable(old_mnt, old.dentry, &new))
- goto out4;
- /* make certain new is below the root */
- if (!is_path_reachable(new_mnt, new.dentry, &root))
- goto out4;
- lock_mount_hash();
- umount_mnt(new_mnt);
- root_mp = unhash_mnt(root_mnt); /* we'll need its mountpoint */
- #ifdef CONFIG_KDP_NS
- if (((struct kdp_mount *)root_mnt)->mnt->mnt_flags & MNT_LOCKED) {
- kdp_set_mnt_flags(((struct kdp_mount *)new_mnt)->mnt, MNT_LOCKED);
- kdp_clear_mnt_flags(((struct kdp_mount *)root_mnt)->mnt, MNT_LOCKED);
- }
- #else
- if (root_mnt->mnt.mnt_flags & MNT_LOCKED) {
- new_mnt->mnt.mnt_flags |= MNT_LOCKED;
- root_mnt->mnt.mnt_flags &= ~MNT_LOCKED;
- }
- #endif
- /* mount old root on put_old */
- attach_mnt(root_mnt, old_mnt, old_mp);
- /* mount new_root on / */
- attach_mnt(new_mnt, root_parent, root_mp);
- mnt_add_count(root_parent, -1);
- touch_mnt_namespace(current->nsproxy->mnt_ns);
- /* A moved mount should not expire automatically */
- list_del_init(&new_mnt->mnt_expire);
- put_mountpoint(root_mp);
- unlock_mount_hash();
- chroot_fs_refs(&root, &new);
- error = 0;
- out4:
- unlock_mount(old_mp);
- if (!error)
- mntput_no_expire(ex_parent);
- out3:
- path_put(&root);
- out2:
- path_put(&old);
- out1:
- path_put(&new);
- out0:
- return error;
- }
- static unsigned int recalc_flags(struct mount_kattr *kattr, struct mount *mnt)
- {
- #ifdef CONFIG_KDP_NS
- unsigned int flags = ((struct kdp_mount *)mnt)->mnt->mnt_flags;
- #else
- unsigned int flags = mnt->mnt.mnt_flags;
- #endif
- /* flags to clear */
- flags &= ~kattr->attr_clr;
- /* flags to raise */
- flags |= kattr->attr_set;
- return flags;
- }
- static int can_idmap_mount(const struct mount_kattr *kattr, struct mount *mnt)
- {
- #ifdef CONFIG_KDP_NS
- struct vfsmount *m = ((struct kdp_mount *)mnt)->mnt;
- #else
- struct vfsmount *m = &mnt->mnt;
- #endif
- struct user_namespace *fs_userns = m->mnt_sb->s_user_ns;
- if (!kattr->mnt_userns)
- return 0;
- /*
- * Creating an idmapped mount with the filesystem wide idmapping
- * doesn't make sense so block that. We don't allow mushy semantics.
- */
- if (kattr->mnt_userns == fs_userns)
- return -EINVAL;
- /*
- * Once a mount has been idmapped we don't allow it to change its
- * mapping. It makes things simpler and callers can just create
- * another bind-mount they can idmap if they want to.
- */
- if (is_idmapped_mnt(m))
- return -EPERM;
- /* The underlying filesystem doesn't support idmapped mounts yet. */
- if (!(m->mnt_sb->s_type->fs_flags & FS_ALLOW_IDMAP))
- return -EINVAL;
- /* We're not controlling the superblock. */
- if (!ns_capable(fs_userns, CAP_SYS_ADMIN))
- return -EPERM;
- /* Mount has already been visible in the filesystem hierarchy. */
- if (!is_anon_ns(mnt->mnt_ns))
- return -EINVAL;
- return 0;
- }
- /**
- * mnt_allow_writers() - check whether the attribute change allows writers
- * @kattr: the new mount attributes
- * @mnt: the mount to which @kattr will be applied
- *
- * Check whether thew new mount attributes in @kattr allow concurrent writers.
- *
- * Return: true if writers need to be held, false if not
- */
- static inline bool mnt_allow_writers(const struct mount_kattr *kattr,
- const struct mount *mnt)
- {
- return (!(kattr->attr_set & MNT_READONLY) ||
- #ifdef CONFIG_KDP_NS
- (((struct kdp_mount *)mnt)->mnt->mnt_flags & MNT_READONLY)) &&
- #else
- (mnt->mnt.mnt_flags & MNT_READONLY)) &&
- #endif
- !kattr->mnt_userns;
- }
- static int mount_setattr_prepare(struct mount_kattr *kattr, struct mount *mnt)
- {
- struct mount *m;
- int err;
- for (m = mnt; m; m = next_mnt(m, mnt)) {
- if (!can_change_locked_flags(m, recalc_flags(kattr, m))) {
- err = -EPERM;
- break;
- }
- err = can_idmap_mount(kattr, m);
- if (err)
- break;
- if (!mnt_allow_writers(kattr, m)) {
- err = mnt_hold_writers(m);
- if (err)
- break;
- }
- if (!kattr->recurse)
- return 0;
- }
- if (err) {
- struct mount *p;
- /*
- * If we had to call mnt_hold_writers() MNT_WRITE_HOLD will
- * be set in @mnt_flags. The loop unsets MNT_WRITE_HOLD for all
- * mounts and needs to take care to include the first mount.
- */
- for (p = mnt; p; p = next_mnt(p, mnt)) {
- /* If we had to hold writers unblock them. */
- #ifdef CONFIG_KDP_NS
- if (((struct kdp_mount *)p)->mnt->mnt_flags & MNT_WRITE_HOLD)
- #else
- if (p->mnt.mnt_flags & MNT_WRITE_HOLD)
- #endif
- mnt_unhold_writers(p);
- /*
- * We're done once the first mount we changed got
- * MNT_WRITE_HOLD unset.
- */
- if (p == m)
- break;
- }
- }
- return err;
- }
- static void do_idmap_mount(const struct mount_kattr *kattr, struct mount *mnt)
- {
- struct user_namespace *mnt_userns, *old_mnt_userns;
- if (!kattr->mnt_userns)
- return;
- /*
- * We're the only ones able to change the mount's idmapping. So
- * mnt->mnt.mnt_userns is stable and we can retrieve it directly.
- */
- #ifdef CONFIG_KDP_NS
- old_mnt_userns = ((struct kdp_mount *)mnt)->mnt->mnt_userns;
- #else
- old_mnt_userns = mnt->mnt.mnt_userns;
- #endif
- mnt_userns = get_user_ns(kattr->mnt_userns);
- /* Pairs with smp_load_acquire() in mnt_user_ns(). */
- #ifdef CONFIG_KDP_NS
- compiletime_assert_atomic_type(((struct kdp_mount *)mnt)->mnt);
- __smp_mb();
- kdp_set_mnt_userns(((struct kdp_mount *)mnt)->mnt, mnt_userns);
- #else
- smp_store_release(&mnt->mnt.mnt_userns, mnt_userns);
- #endif
- /*
- * If this is an idmapped filesystem drop the reference we've taken
- * in vfs_create_mount() before.
- */
- if (!initial_idmapping(old_mnt_userns))
- put_user_ns(old_mnt_userns);
- }
- static void mount_setattr_commit(struct mount_kattr *kattr, struct mount *mnt)
- {
- struct mount *m;
- for (m = mnt; m; m = next_mnt(m, mnt)) {
- unsigned int flags;
- do_idmap_mount(kattr, m);
- flags = recalc_flags(kattr, m);
- #ifdef CONFIG_KDP_NS
- kdp_assign_mnt_flags(((struct kdp_mount *)m)->mnt, flags);
- #else
- WRITE_ONCE(m->mnt.mnt_flags, flags);
- #endif
- /* If we had to hold writers unblock them. */
- #ifdef CONFIG_KDP_NS
- if (((struct kdp_mount*)m)->mnt->mnt_flags & MNT_WRITE_HOLD)
- #else
- if (m->mnt.mnt_flags & MNT_WRITE_HOLD)
- #endif
- mnt_unhold_writers(m);
- if (kattr->propagation)
- change_mnt_propagation(m, kattr->propagation);
- if (!kattr->recurse)
- break;
- }
- touch_mnt_namespace(mnt->mnt_ns);
- }
- static int do_mount_setattr(struct path *path, struct mount_kattr *kattr)
- {
- struct mount *mnt = real_mount(path->mnt);
- int err = 0;
- #ifdef CONFIG_KDP_NS
- if (path->dentry != ((struct kdp_mount *)mnt)->mnt->mnt_root)
- #else
- if (path->dentry != mnt->mnt.mnt_root)
- #endif
- return -EINVAL;
- if (kattr->propagation) {
- /*
- * Only take namespace_lock() if we're actually changing
- * propagation.
- */
- namespace_lock();
- if (kattr->propagation == MS_SHARED) {
- err = invent_group_ids(mnt, kattr->recurse);
- if (err) {
- namespace_unlock();
- return err;
- }
- }
- }
- err = -EINVAL;
- lock_mount_hash();
- /* Ensure that this isn't anything purely vfs internal. */
- if (!is_mounted(&mnt->mnt))
- goto out;
- /*
- * If this is an attached mount make sure it's located in the callers
- * mount namespace. If it's not don't let the caller interact with it.
- * If this is a detached mount make sure it has an anonymous mount
- * namespace attached to it, i.e. we've created it via OPEN_TREE_CLONE.
- */
- if (!(mnt_has_parent(mnt) ? check_mnt(mnt) : is_anon_ns(mnt->mnt_ns)))
- goto out;
- /*
- * First, we get the mount tree in a shape where we can change mount
- * properties without failure. If we succeeded to do so we commit all
- * changes and if we failed we clean up.
- */
- err = mount_setattr_prepare(kattr, mnt);
- if (!err)
- mount_setattr_commit(kattr, mnt);
- out:
- unlock_mount_hash();
- if (kattr->propagation) {
- if (err)
- cleanup_group_ids(mnt, NULL);
- namespace_unlock();
- }
- return err;
- }
- static int build_mount_idmapped(const struct mount_attr *attr, size_t usize,
- struct mount_kattr *kattr, unsigned int flags)
- {
- int err = 0;
- struct ns_common *ns;
- struct user_namespace *mnt_userns;
- struct file *file;
- if (!((attr->attr_set | attr->attr_clr) & MOUNT_ATTR_IDMAP))
- return 0;
- /*
- * We currently do not support clearing an idmapped mount. If this ever
- * is a use-case we can revisit this but for now let's keep it simple
- * and not allow it.
- */
- if (attr->attr_clr & MOUNT_ATTR_IDMAP)
- return -EINVAL;
- if (attr->userns_fd > INT_MAX)
- return -EINVAL;
- file = fget(attr->userns_fd);
- if (!file)
- return -EBADF;
- if (!proc_ns_file(file)) {
- err = -EINVAL;
- goto out_fput;
- }
- ns = get_proc_ns(file_inode(file));
- if (ns->ops->type != CLONE_NEWUSER) {
- err = -EINVAL;
- goto out_fput;
- }
- /*
- * The initial idmapping cannot be used to create an idmapped
- * mount. We use the initial idmapping as an indicator of a mount
- * that is not idmapped. It can simply be passed into helpers that
- * are aware of idmapped mounts as a convenient shortcut. A user
- * can just create a dedicated identity mapping to achieve the same
- * result.
- */
- mnt_userns = container_of(ns, struct user_namespace, ns);
- if (initial_idmapping(mnt_userns)) {
- err = -EPERM;
- goto out_fput;
- }
- /* We're not controlling the target namespace. */
- if (!ns_capable(mnt_userns, CAP_SYS_ADMIN)) {
- err = -EPERM;
- goto out_fput;
- }
- kattr->mnt_userns = get_user_ns(mnt_userns);
- out_fput:
- fput(file);
- return err;
- }
- static int build_mount_kattr(const struct mount_attr *attr, size_t usize,
- struct mount_kattr *kattr, unsigned int flags)
- {
- unsigned int lookup_flags = LOOKUP_AUTOMOUNT | LOOKUP_FOLLOW;
- if (flags & AT_NO_AUTOMOUNT)
- lookup_flags &= ~LOOKUP_AUTOMOUNT;
- if (flags & AT_SYMLINK_NOFOLLOW)
- lookup_flags &= ~LOOKUP_FOLLOW;
- if (flags & AT_EMPTY_PATH)
- lookup_flags |= LOOKUP_EMPTY;
- *kattr = (struct mount_kattr) {
- .lookup_flags = lookup_flags,
- .recurse = !!(flags & AT_RECURSIVE),
- };
- if (attr->propagation & ~MOUNT_SETATTR_PROPAGATION_FLAGS)
- return -EINVAL;
- if (hweight32(attr->propagation & MOUNT_SETATTR_PROPAGATION_FLAGS) > 1)
- return -EINVAL;
- kattr->propagation = attr->propagation;
- if ((attr->attr_set | attr->attr_clr) & ~MOUNT_SETATTR_VALID_FLAGS)
- return -EINVAL;
- kattr->attr_set = attr_flags_to_mnt_flags(attr->attr_set);
- kattr->attr_clr = attr_flags_to_mnt_flags(attr->attr_clr);
- /*
- * Since the MOUNT_ATTR_<atime> values are an enum, not a bitmap,
- * users wanting to transition to a different atime setting cannot
- * simply specify the atime setting in @attr_set, but must also
- * specify MOUNT_ATTR__ATIME in the @attr_clr field.
- * So ensure that MOUNT_ATTR__ATIME can't be partially set in
- * @attr_clr and that @attr_set can't have any atime bits set if
- * MOUNT_ATTR__ATIME isn't set in @attr_clr.
- */
- if (attr->attr_clr & MOUNT_ATTR__ATIME) {
- if ((attr->attr_clr & MOUNT_ATTR__ATIME) != MOUNT_ATTR__ATIME)
- return -EINVAL;
- /*
- * Clear all previous time settings as they are mutually
- * exclusive.
- */
- kattr->attr_clr |= MNT_RELATIME | MNT_NOATIME;
- switch (attr->attr_set & MOUNT_ATTR__ATIME) {
- case MOUNT_ATTR_RELATIME:
- kattr->attr_set |= MNT_RELATIME;
- break;
- case MOUNT_ATTR_NOATIME:
- kattr->attr_set |= MNT_NOATIME;
- break;
- case MOUNT_ATTR_STRICTATIME:
- break;
- default:
- return -EINVAL;
- }
- } else {
- if (attr->attr_set & MOUNT_ATTR__ATIME)
- return -EINVAL;
- }
- return build_mount_idmapped(attr, usize, kattr, flags);
- }
- static void finish_mount_kattr(struct mount_kattr *kattr)
- {
- put_user_ns(kattr->mnt_userns);
- kattr->mnt_userns = NULL;
- }
- SYSCALL_DEFINE5(mount_setattr, int, dfd, const char __user *, path,
- unsigned int, flags, struct mount_attr __user *, uattr,
- size_t, usize)
- {
- int err;
- struct path target;
- struct mount_attr attr;
- struct mount_kattr kattr;
- BUILD_BUG_ON(sizeof(struct mount_attr) != MOUNT_ATTR_SIZE_VER0);
- if (flags & ~(AT_EMPTY_PATH |
- AT_RECURSIVE |
- AT_SYMLINK_NOFOLLOW |
- AT_NO_AUTOMOUNT))
- return -EINVAL;
- if (unlikely(usize > PAGE_SIZE))
- return -E2BIG;
- if (unlikely(usize < MOUNT_ATTR_SIZE_VER0))
- return -EINVAL;
- if (!may_mount())
- return -EPERM;
- err = copy_struct_from_user(&attr, sizeof(attr), uattr, usize);
- if (err)
- return err;
- /* Don't bother walking through the mounts if this is a nop. */
- if (attr.attr_set == 0 &&
- attr.attr_clr == 0 &&
- attr.propagation == 0)
- return 0;
- err = build_mount_kattr(&attr, usize, &kattr, flags);
- if (err)
- return err;
- err = user_path_at(dfd, path, kattr.lookup_flags, &target);
- if (!err) {
- err = do_mount_setattr(&target, &kattr);
- path_put(&target);
- }
- finish_mount_kattr(&kattr);
- return err;
- }
- static void __init init_mount_tree(void)
- {
- struct vfsmount *mnt;
- struct mount *m;
- struct mnt_namespace *ns;
- struct path root;
- mnt = vfs_kern_mount(&rootfs_fs_type, 0, "rootfs", NULL);
- if (IS_ERR(mnt))
- panic("Can't create rootfs");
- ns = alloc_mnt_ns(&init_user_ns, false);
- if (IS_ERR(ns))
- panic("Can't allocate initial namespace");
- m = real_mount(mnt);
- m->mnt_ns = ns;
- ns->root = m;
- ns->mounts = 1;
- list_add(&m->mnt_list, &ns->list);
- init_task.nsproxy->mnt_ns = ns;
- get_mnt_ns(ns);
- root.mnt = mnt;
- root.dentry = mnt->mnt_root;
- #ifdef CONFIG_KDP_NS
- kdp_set_mnt_flags(mnt, MNT_LOCKED);
- #else
- mnt->mnt_flags |= MNT_LOCKED;
- #endif
- set_fs_pwd(current->fs, &root);
- set_fs_root(current->fs, &root);
- }
- void __init mnt_init(void)
- {
- int err;
- #ifdef CONFIG_KDP_NS
- mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct kdp_mount),
- 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, NULL);
- kdp_mnt_init();
- #else
- mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct mount),
- 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, NULL);
- #endif
- mount_hashtable = alloc_large_system_hash("Mount-cache",
- sizeof(struct hlist_head),
- mhash_entries, 19,
- HASH_ZERO,
- &m_hash_shift, &m_hash_mask, 0, 0);
- mountpoint_hashtable = alloc_large_system_hash("Mountpoint-cache",
- sizeof(struct hlist_head),
- mphash_entries, 19,
- HASH_ZERO,
- &mp_hash_shift, &mp_hash_mask, 0, 0);
- if (!mount_hashtable || !mountpoint_hashtable)
- panic("Failed to allocate mount hash table\n");
- kernfs_init();
- err = sysfs_init();
- if (err)
- printk(KERN_WARNING "%s: sysfs_init error: %d\n",
- __func__, err);
- fs_kobj = kobject_create_and_add("fs", NULL);
- if (!fs_kobj)
- printk(KERN_WARNING "%s: kobj create error\n", __func__);
- shmem_init();
- init_rootfs();
- init_mount_tree();
- }
- void put_mnt_ns(struct mnt_namespace *ns)
- {
- if (!refcount_dec_and_test(&ns->ns.count))
- return;
- #ifdef CONFIG_KDP_NS
- drop_collected_mounts(((struct kdp_mount *)ns->root)->mnt);
- #else
- drop_collected_mounts(&ns->root->mnt);
- #endif
- free_mnt_ns(ns);
- }
- struct vfsmount *kern_mount(struct file_system_type *type)
- {
- struct vfsmount *mnt;
- mnt = vfs_kern_mount(type, SB_KERNMOUNT, type->name, NULL);
- if (!IS_ERR(mnt)) {
- /*
- * it is a longterm mount, don't release mnt until
- * we unmount before file sys is unregistered
- */
- real_mount(mnt)->mnt_ns = MNT_NS_INTERNAL;
- }
- return mnt;
- }
- EXPORT_SYMBOL_GPL(kern_mount);
- void kern_unmount(struct vfsmount *mnt)
- {
- /* release long term mount so mount point can be released */
- if (!IS_ERR_OR_NULL(mnt)) {
- real_mount(mnt)->mnt_ns = NULL;
- synchronize_rcu(); /* yecchhh... */
- mntput(mnt);
- }
- }
- EXPORT_SYMBOL(kern_unmount);
- void kern_unmount_array(struct vfsmount *mnt[], unsigned int num)
- {
- unsigned int i;
- for (i = 0; i < num; i++)
- if (mnt[i])
- real_mount(mnt[i])->mnt_ns = NULL;
- synchronize_rcu_expedited();
- for (i = 0; i < num; i++)
- mntput(mnt[i]);
- }
- EXPORT_SYMBOL(kern_unmount_array);
- bool our_mnt(struct vfsmount *mnt)
- {
- return check_mnt(real_mount(mnt));
- }
- bool current_chrooted(void)
- {
- /* Does the current process have a non-standard root */
- struct path ns_root;
- struct path fs_root;
- bool chrooted;
- /* Find the namespace root */
- #ifdef CONFIG_KDP_NS
- ns_root.mnt = ((struct kdp_mount *)current->nsproxy->mnt_ns->root)->mnt;
- #else
- ns_root.mnt = ¤t->nsproxy->mnt_ns->root->mnt;
- #endif
- ns_root.dentry = ns_root.mnt->mnt_root;
- path_get(&ns_root);
- while (d_mountpoint(ns_root.dentry) && follow_down_one(&ns_root))
- ;
- get_fs_root(current->fs, &fs_root);
- chrooted = !path_equal(&fs_root, &ns_root);
- path_put(&fs_root);
- path_put(&ns_root);
- return chrooted;
- }
- static bool mnt_already_visible(struct mnt_namespace *ns,
- const struct super_block *sb,
- int *new_mnt_flags)
- {
- int new_flags = *new_mnt_flags;
- struct mount *mnt;
- bool visible = false;
- down_read(&namespace_sem);
- lock_ns_list(ns);
- list_for_each_entry(mnt, &ns->list, mnt_list) {
- struct mount *child;
- int mnt_flags;
- if (mnt_is_cursor(mnt))
- continue;
- #ifdef CONFIG_KDP_NS
- if (((struct kdp_mount *)mnt)->mnt->mnt_sb->s_type != sb->s_type)
- continue;
- /* This mount is not fully visible if it's root directory
- * is not the root directory of the filesystem.
- */
- if (((struct kdp_mount *)mnt)->mnt->mnt_root != ((struct kdp_mount *)mnt)->mnt->mnt_sb->s_root)
- continue;
- /* A local view of the mount flags */
- mnt_flags = ((struct kdp_mount *)mnt)->mnt->mnt_flags;
- /* Don't miss readonly hidden in the superblock flags */
- if (sb_rdonly(((struct kdp_mount *)mnt)->mnt->mnt_sb))
- mnt_flags |= MNT_LOCK_READONLY;
- #else
- if (mnt->mnt.mnt_sb->s_type != sb->s_type)
- continue;
- /* This mount is not fully visible if it's root directory
- * is not the root directory of the filesystem.
- */
- if (mnt->mnt.mnt_root != mnt->mnt.mnt_sb->s_root)
- continue;
- /* A local view of the mount flags */
- mnt_flags = mnt->mnt.mnt_flags;
- /* Don't miss readonly hidden in the superblock flags */
- if (sb_rdonly(mnt->mnt.mnt_sb))
- mnt_flags |= MNT_LOCK_READONLY;
- #endif
- /* Verify the mount flags are equal to or more permissive
- * than the proposed new mount.
- */
- if ((mnt_flags & MNT_LOCK_READONLY) &&
- !(new_flags & MNT_READONLY))
- continue;
- if ((mnt_flags & MNT_LOCK_ATIME) &&
- ((mnt_flags & MNT_ATIME_MASK) != (new_flags & MNT_ATIME_MASK)))
- continue;
- /* This mount is not fully visible if there are any
- * locked child mounts that cover anything except for
- * empty directories.
- */
- list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) {
- struct inode *inode = child->mnt_mountpoint->d_inode;
- /* Only worry about locked mounts */
- #ifdef CONFIG_KDP_NS
- if (!(((struct kdp_mount *)child)->mnt->mnt_flags & MNT_LOCKED))
- continue;
- #else
- if (!(child->mnt.mnt_flags & MNT_LOCKED))
- continue;
- #endif
- /* Is the directory permanetly empty? */
- if (!is_empty_dir_inode(inode))
- goto next;
- }
- /* Preserve the locked attributes */
- *new_mnt_flags |= mnt_flags & (MNT_LOCK_READONLY | \
- MNT_LOCK_ATIME);
- visible = true;
- goto found;
- next: ;
- }
- found:
- unlock_ns_list(ns);
- up_read(&namespace_sem);
- return visible;
- }
- static bool mount_too_revealing(const struct super_block *sb, int *new_mnt_flags)
- {
- const unsigned long required_iflags = SB_I_NOEXEC | SB_I_NODEV;
- struct mnt_namespace *ns = current->nsproxy->mnt_ns;
- unsigned long s_iflags;
- if (ns->user_ns == &init_user_ns)
- return false;
- /* Can this filesystem be too revealing? */
- s_iflags = sb->s_iflags;
- if (!(s_iflags & SB_I_USERNS_VISIBLE))
- return false;
- if ((s_iflags & required_iflags) != required_iflags) {
- WARN_ONCE(1, "Expected s_iflags to contain 0x%lx\n",
- required_iflags);
- return true;
- }
- return !mnt_already_visible(ns, sb, new_mnt_flags);
- }
- bool mnt_may_suid(struct vfsmount *mnt)
- {
- /*
- * Foreign mounts (accessed via fchdir or through /proc
- * symlinks) are always treated as if they are nosuid. This
- * prevents namespaces from trusting potentially unsafe
- * suid/sgid bits, file caps, or security labels that originate
- * in other namespaces.
- */
- return !(mnt->mnt_flags & MNT_NOSUID) && check_mnt(real_mount(mnt)) &&
- current_in_userns(mnt->mnt_sb->s_user_ns);
- }
- static struct ns_common *mntns_get(struct task_struct *task)
- {
- struct ns_common *ns = NULL;
- struct nsproxy *nsproxy;
- task_lock(task);
- nsproxy = task->nsproxy;
- if (nsproxy) {
- ns = &nsproxy->mnt_ns->ns;
- get_mnt_ns(to_mnt_ns(ns));
- }
- task_unlock(task);
- return ns;
- }
- static void mntns_put(struct ns_common *ns)
- {
- put_mnt_ns(to_mnt_ns(ns));
- }
- static int mntns_install(struct nsset *nsset, struct ns_common *ns)
- {
- struct nsproxy *nsproxy = nsset->nsproxy;
- struct fs_struct *fs = nsset->fs;
- struct mnt_namespace *mnt_ns = to_mnt_ns(ns), *old_mnt_ns;
- struct user_namespace *user_ns = nsset->cred->user_ns;
- struct path root;
- int err;
- if (!ns_capable(mnt_ns->user_ns, CAP_SYS_ADMIN) ||
- !ns_capable(user_ns, CAP_SYS_CHROOT) ||
- !ns_capable(user_ns, CAP_SYS_ADMIN))
- return -EPERM;
- if (is_anon_ns(mnt_ns))
- return -EINVAL;
- if (fs->users != 1)
- return -EINVAL;
- get_mnt_ns(mnt_ns);
- old_mnt_ns = nsproxy->mnt_ns;
- nsproxy->mnt_ns = mnt_ns;
- /* Find the root */
- #ifdef CONFIG_KDP_NS
- err = vfs_path_lookup(((struct kdp_mount *)mnt_ns->root)->mnt->mnt_root, ((struct kdp_mount *)mnt_ns->root)->mnt,
- "/", LOOKUP_DOWN, &root);
- #else
- err = vfs_path_lookup(mnt_ns->root->mnt.mnt_root, &mnt_ns->root->mnt,
- "/", LOOKUP_DOWN, &root);
- #endif
- if (err) {
- /* revert to old namespace */
- nsproxy->mnt_ns = old_mnt_ns;
- put_mnt_ns(mnt_ns);
- return err;
- }
- put_mnt_ns(old_mnt_ns);
- /* Update the pwd and root */
- set_fs_pwd(fs, &root);
- set_fs_root(fs, &root);
- path_put(&root);
- return 0;
- }
- static struct user_namespace *mntns_owner(struct ns_common *ns)
- {
- return to_mnt_ns(ns)->user_ns;
- }
- const struct proc_ns_operations mntns_operations = {
- .name = "mnt",
- .type = CLONE_NEWNS,
- .get = mntns_get,
- .put = mntns_put,
- .install = mntns_install,
- .owner = mntns_owner,
- };
- #ifdef CONFIG_SYSCTL
- static struct ctl_table fs_namespace_sysctls[] = {
- {
- .procname = "mount-max",
- .data = &sysctl_mount_max,
- .maxlen = sizeof(unsigned int),
- .mode = 0644,
- .proc_handler = proc_dointvec_minmax,
- .extra1 = SYSCTL_ONE,
- },
- { }
- };
- static int __init init_fs_namespace_sysctls(void)
- {
- register_sysctl_init("fs", fs_namespace_sysctls);
- return 0;
- }
- fs_initcall(init_fs_namespace_sysctls);
- #endif /* CONFIG_SYSCTL */
- #ifdef CONFIG_KSU_SUSFS_TRY_UMOUNT
- extern void susfs_try_umount_all(uid_t uid);
- void susfs_run_try_umount_for_current_mnt_ns(void) {
- struct mount *mnt;
- struct mnt_namespace *mnt_ns;
- mnt_ns = current->nsproxy->mnt_ns;
- // Lock the namespace
- namespace_lock();
- list_for_each_entry(mnt, &mnt_ns->list, mnt_list) {
- // Change the sus mount to be private
- if (mnt->mnt_id >= DEFAULT_SUS_MNT_ID) {
- change_mnt_propagation(mnt, MS_PRIVATE);
- }
- }
- // Unlock the namespace
- namespace_unlock();
- susfs_try_umount_all(current_uid().val);
- }
- #endif
- #ifdef CONFIG_KSU_SUSFS
- bool susfs_is_mnt_devname_ksu(struct path *path) {
- struct mount *mnt;
- if (path && path->mnt) {
- mnt = real_mount(path->mnt);
- if (mnt && mnt->mnt_devname && !strcmp(mnt->mnt_devname, "KSU")) {
- return true;
- }
- }
- return false;
- }
- #endif
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