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- // SPDX-License-Identifier: GPL-2.0
- /*
- * linux/fs/proc/inode.c
- *
- * Copyright (C) 1991, 1992 Linus Torvalds
- */
- #include <linux/cache.h>
- #include <linux/time.h>
- #include <linux/proc_fs.h>
- #include <linux/kernel.h>
- #include <linux/pid_namespace.h>
- #include <linux/mm.h>
- #include <linux/string.h>
- #include <linux/stat.h>
- #include <linux/completion.h>
- #include <linux/poll.h>
- #include <linux/printk.h>
- #include <linux/file.h>
- #include <linux/limits.h>
- #include <linux/init.h>
- #include <linux/module.h>
- #include <linux/sysctl.h>
- #include <linux/seq_file.h>
- #include <linux/slab.h>
- #include <linux/mount.h>
- #include <linux/bug.h>
- #include "internal.h"
- static void proc_evict_inode(struct inode *inode)
- {
- struct proc_dir_entry *de;
- struct ctl_table_header *head;
- struct proc_inode *ei = PROC_I(inode);
- truncate_inode_pages_final(&inode->i_data);
- clear_inode(inode);
- /* Stop tracking associated processes */
- if (ei->pid) {
- proc_pid_evict_inode(ei);
- ei->pid = NULL;
- }
- /* Let go of any associated proc directory entry */
- de = ei->pde;
- if (de) {
- pde_put(de);
- ei->pde = NULL;
- }
- head = ei->sysctl;
- if (head) {
- RCU_INIT_POINTER(ei->sysctl, NULL);
- proc_sys_evict_inode(inode, head);
- }
- }
- static struct kmem_cache *proc_inode_cachep __ro_after_init;
- static struct kmem_cache *pde_opener_cache __ro_after_init;
- static struct inode *proc_alloc_inode(struct super_block *sb)
- {
- struct proc_inode *ei;
- ei = alloc_inode_sb(sb, proc_inode_cachep, GFP_KERNEL);
- if (!ei)
- return NULL;
- ei->pid = NULL;
- ei->fd = 0;
- ei->op.proc_get_link = NULL;
- ei->pde = NULL;
- ei->sysctl = NULL;
- ei->sysctl_entry = NULL;
- INIT_HLIST_NODE(&ei->sibling_inodes);
- ei->ns_ops = NULL;
- return &ei->vfs_inode;
- }
- static void proc_free_inode(struct inode *inode)
- {
- kmem_cache_free(proc_inode_cachep, PROC_I(inode));
- }
- static void init_once(void *foo)
- {
- struct proc_inode *ei = (struct proc_inode *) foo;
- inode_init_once(&ei->vfs_inode);
- }
- void __init proc_init_kmemcache(void)
- {
- proc_inode_cachep = kmem_cache_create("proc_inode_cache",
- sizeof(struct proc_inode),
- 0, (SLAB_RECLAIM_ACCOUNT|
- SLAB_MEM_SPREAD|SLAB_ACCOUNT|
- SLAB_PANIC),
- init_once);
- pde_opener_cache =
- kmem_cache_create("pde_opener", sizeof(struct pde_opener), 0,
- SLAB_ACCOUNT|SLAB_PANIC, NULL);
- proc_dir_entry_cache = kmem_cache_create_usercopy(
- "proc_dir_entry", SIZEOF_PDE, 0, SLAB_PANIC,
- offsetof(struct proc_dir_entry, inline_name),
- SIZEOF_PDE_INLINE_NAME, NULL);
- BUILD_BUG_ON(sizeof(struct proc_dir_entry) >= SIZEOF_PDE);
- }
- void proc_invalidate_siblings_dcache(struct hlist_head *inodes, spinlock_t *lock)
- {
- struct inode *inode;
- struct proc_inode *ei;
- struct hlist_node *node;
- struct super_block *old_sb = NULL;
- rcu_read_lock();
- for (;;) {
- struct super_block *sb;
- node = hlist_first_rcu(inodes);
- if (!node)
- break;
- ei = hlist_entry(node, struct proc_inode, sibling_inodes);
- spin_lock(lock);
- hlist_del_init_rcu(&ei->sibling_inodes);
- spin_unlock(lock);
- inode = &ei->vfs_inode;
- sb = inode->i_sb;
- if ((sb != old_sb) && !atomic_inc_not_zero(&sb->s_active))
- continue;
- inode = igrab(inode);
- rcu_read_unlock();
- if (sb != old_sb) {
- if (old_sb)
- deactivate_super(old_sb);
- old_sb = sb;
- }
- if (unlikely(!inode)) {
- rcu_read_lock();
- continue;
- }
- if (S_ISDIR(inode->i_mode)) {
- struct dentry *dir = d_find_any_alias(inode);
- if (dir) {
- d_invalidate(dir);
- dput(dir);
- }
- } else {
- struct dentry *dentry;
- while ((dentry = d_find_alias(inode))) {
- d_invalidate(dentry);
- dput(dentry);
- }
- }
- iput(inode);
- rcu_read_lock();
- }
- rcu_read_unlock();
- if (old_sb)
- deactivate_super(old_sb);
- }
- static inline const char *hidepid2str(enum proc_hidepid v)
- {
- switch (v) {
- case HIDEPID_OFF: return "off";
- case HIDEPID_NO_ACCESS: return "noaccess";
- case HIDEPID_INVISIBLE: return "invisible";
- case HIDEPID_NOT_PTRACEABLE: return "ptraceable";
- }
- WARN_ONCE(1, "bad hide_pid value: %d\n", v);
- return "unknown";
- }
- static int proc_show_options(struct seq_file *seq, struct dentry *root)
- {
- struct proc_fs_info *fs_info = proc_sb_info(root->d_sb);
- if (!gid_eq(fs_info->pid_gid, GLOBAL_ROOT_GID))
- seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, fs_info->pid_gid));
- if (fs_info->hide_pid != HIDEPID_OFF)
- seq_printf(seq, ",hidepid=%s", hidepid2str(fs_info->hide_pid));
- if (fs_info->pidonly != PROC_PIDONLY_OFF)
- seq_printf(seq, ",subset=pid");
- return 0;
- }
- const struct super_operations proc_sops = {
- .alloc_inode = proc_alloc_inode,
- .free_inode = proc_free_inode,
- .drop_inode = generic_delete_inode,
- .evict_inode = proc_evict_inode,
- .statfs = simple_statfs,
- .show_options = proc_show_options,
- };
- enum {BIAS = -1U<<31};
- static inline int use_pde(struct proc_dir_entry *pde)
- {
- return likely(atomic_inc_unless_negative(&pde->in_use));
- }
- static void unuse_pde(struct proc_dir_entry *pde)
- {
- if (unlikely(atomic_dec_return(&pde->in_use) == BIAS))
- complete(pde->pde_unload_completion);
- }
- /*
- * At most 2 contexts can enter this function: the one doing the last
- * close on the descriptor and whoever is deleting PDE itself.
- *
- * First to enter calls ->proc_release hook and signals its completion
- * to the second one which waits and then does nothing.
- *
- * PDE is locked on entry, unlocked on exit.
- */
- static void close_pdeo(struct proc_dir_entry *pde, struct pde_opener *pdeo)
- __releases(&pde->pde_unload_lock)
- {
- /*
- * close() (proc_reg_release()) can't delete an entry and proceed:
- * ->release hook needs to be available at the right moment.
- *
- * rmmod (remove_proc_entry() et al) can't delete an entry and proceed:
- * "struct file" needs to be available at the right moment.
- */
- if (pdeo->closing) {
- /* somebody else is doing that, just wait */
- DECLARE_COMPLETION_ONSTACK(c);
- pdeo->c = &c;
- spin_unlock(&pde->pde_unload_lock);
- wait_for_completion(&c);
- } else {
- struct file *file;
- struct completion *c;
- pdeo->closing = true;
- spin_unlock(&pde->pde_unload_lock);
- file = pdeo->file;
- pde->proc_ops->proc_release(file_inode(file), file);
- spin_lock(&pde->pde_unload_lock);
- /* Strictly after ->proc_release, see above. */
- list_del(&pdeo->lh);
- c = pdeo->c;
- spin_unlock(&pde->pde_unload_lock);
- if (unlikely(c))
- complete(c);
- kmem_cache_free(pde_opener_cache, pdeo);
- }
- }
- void proc_entry_rundown(struct proc_dir_entry *de)
- {
- DECLARE_COMPLETION_ONSTACK(c);
- /* Wait until all existing callers into module are done. */
- de->pde_unload_completion = &c;
- if (atomic_add_return(BIAS, &de->in_use) != BIAS)
- wait_for_completion(&c);
- /* ->pde_openers list can't grow from now on. */
- spin_lock(&de->pde_unload_lock);
- while (!list_empty(&de->pde_openers)) {
- struct pde_opener *pdeo;
- pdeo = list_first_entry(&de->pde_openers, struct pde_opener, lh);
- close_pdeo(de, pdeo);
- spin_lock(&de->pde_unload_lock);
- }
- spin_unlock(&de->pde_unload_lock);
- }
- static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence)
- {
- struct proc_dir_entry *pde = PDE(file_inode(file));
- loff_t rv = -EINVAL;
- if (pde_is_permanent(pde)) {
- return pde->proc_ops->proc_lseek(file, offset, whence);
- } else if (use_pde(pde)) {
- rv = pde->proc_ops->proc_lseek(file, offset, whence);
- unuse_pde(pde);
- }
- return rv;
- }
- static ssize_t proc_reg_read_iter(struct kiocb *iocb, struct iov_iter *iter)
- {
- struct proc_dir_entry *pde = PDE(file_inode(iocb->ki_filp));
- ssize_t ret;
- if (pde_is_permanent(pde))
- return pde->proc_ops->proc_read_iter(iocb, iter);
- if (!use_pde(pde))
- return -EIO;
- ret = pde->proc_ops->proc_read_iter(iocb, iter);
- unuse_pde(pde);
- return ret;
- }
- static ssize_t pde_read(struct proc_dir_entry *pde, struct file *file, char __user *buf, size_t count, loff_t *ppos)
- {
- typeof_member(struct proc_ops, proc_read) read;
- read = pde->proc_ops->proc_read;
- if (read)
- return read(file, buf, count, ppos);
- return -EIO;
- }
- static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
- {
- struct proc_dir_entry *pde = PDE(file_inode(file));
- ssize_t rv = -EIO;
- if (pde_is_permanent(pde)) {
- return pde_read(pde, file, buf, count, ppos);
- } else if (use_pde(pde)) {
- rv = pde_read(pde, file, buf, count, ppos);
- unuse_pde(pde);
- }
- return rv;
- }
- static ssize_t pde_write(struct proc_dir_entry *pde, struct file *file, const char __user *buf, size_t count, loff_t *ppos)
- {
- typeof_member(struct proc_ops, proc_write) write;
- write = pde->proc_ops->proc_write;
- if (write)
- return write(file, buf, count, ppos);
- return -EIO;
- }
- static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
- {
- struct proc_dir_entry *pde = PDE(file_inode(file));
- ssize_t rv = -EIO;
- if (pde_is_permanent(pde)) {
- return pde_write(pde, file, buf, count, ppos);
- } else if (use_pde(pde)) {
- rv = pde_write(pde, file, buf, count, ppos);
- unuse_pde(pde);
- }
- return rv;
- }
- static __poll_t pde_poll(struct proc_dir_entry *pde, struct file *file, struct poll_table_struct *pts)
- {
- typeof_member(struct proc_ops, proc_poll) poll;
- poll = pde->proc_ops->proc_poll;
- if (poll)
- return poll(file, pts);
- return DEFAULT_POLLMASK;
- }
- static __poll_t proc_reg_poll(struct file *file, struct poll_table_struct *pts)
- {
- struct proc_dir_entry *pde = PDE(file_inode(file));
- __poll_t rv = DEFAULT_POLLMASK;
- if (pde_is_permanent(pde)) {
- return pde_poll(pde, file, pts);
- } else if (use_pde(pde)) {
- rv = pde_poll(pde, file, pts);
- unuse_pde(pde);
- }
- return rv;
- }
- static long pde_ioctl(struct proc_dir_entry *pde, struct file *file, unsigned int cmd, unsigned long arg)
- {
- typeof_member(struct proc_ops, proc_ioctl) ioctl;
- ioctl = pde->proc_ops->proc_ioctl;
- if (ioctl)
- return ioctl(file, cmd, arg);
- return -ENOTTY;
- }
- static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
- {
- struct proc_dir_entry *pde = PDE(file_inode(file));
- long rv = -ENOTTY;
- if (pde_is_permanent(pde)) {
- return pde_ioctl(pde, file, cmd, arg);
- } else if (use_pde(pde)) {
- rv = pde_ioctl(pde, file, cmd, arg);
- unuse_pde(pde);
- }
- return rv;
- }
- #ifdef CONFIG_COMPAT
- static long pde_compat_ioctl(struct proc_dir_entry *pde, struct file *file, unsigned int cmd, unsigned long arg)
- {
- typeof_member(struct proc_ops, proc_compat_ioctl) compat_ioctl;
- compat_ioctl = pde->proc_ops->proc_compat_ioctl;
- if (compat_ioctl)
- return compat_ioctl(file, cmd, arg);
- return -ENOTTY;
- }
- static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
- {
- struct proc_dir_entry *pde = PDE(file_inode(file));
- long rv = -ENOTTY;
- if (pde_is_permanent(pde)) {
- return pde_compat_ioctl(pde, file, cmd, arg);
- } else if (use_pde(pde)) {
- rv = pde_compat_ioctl(pde, file, cmd, arg);
- unuse_pde(pde);
- }
- return rv;
- }
- #endif
- static int pde_mmap(struct proc_dir_entry *pde, struct file *file, struct vm_area_struct *vma)
- {
- typeof_member(struct proc_ops, proc_mmap) mmap;
- mmap = pde->proc_ops->proc_mmap;
- if (mmap)
- return mmap(file, vma);
- return -EIO;
- }
- static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma)
- {
- struct proc_dir_entry *pde = PDE(file_inode(file));
- int rv = -EIO;
- if (pde_is_permanent(pde)) {
- return pde_mmap(pde, file, vma);
- } else if (use_pde(pde)) {
- rv = pde_mmap(pde, file, vma);
- unuse_pde(pde);
- }
- return rv;
- }
- static unsigned long
- pde_get_unmapped_area(struct proc_dir_entry *pde, struct file *file, unsigned long orig_addr,
- unsigned long len, unsigned long pgoff,
- unsigned long flags)
- {
- typeof_member(struct proc_ops, proc_get_unmapped_area) get_area;
- get_area = pde->proc_ops->proc_get_unmapped_area;
- #ifdef CONFIG_MMU
- if (!get_area)
- get_area = current->mm->get_unmapped_area;
- #endif
- if (get_area)
- return get_area(file, orig_addr, len, pgoff, flags);
- return orig_addr;
- }
- static unsigned long
- proc_reg_get_unmapped_area(struct file *file, unsigned long orig_addr,
- unsigned long len, unsigned long pgoff,
- unsigned long flags)
- {
- struct proc_dir_entry *pde = PDE(file_inode(file));
- unsigned long rv = -EIO;
- if (pde_is_permanent(pde)) {
- return pde_get_unmapped_area(pde, file, orig_addr, len, pgoff, flags);
- } else if (use_pde(pde)) {
- rv = pde_get_unmapped_area(pde, file, orig_addr, len, pgoff, flags);
- unuse_pde(pde);
- }
- return rv;
- }
- static int proc_reg_open(struct inode *inode, struct file *file)
- {
- struct proc_dir_entry *pde = PDE(inode);
- int rv = 0;
- typeof_member(struct proc_ops, proc_open) open;
- typeof_member(struct proc_ops, proc_release) release;
- struct pde_opener *pdeo;
- if (!pde->proc_ops->proc_lseek)
- file->f_mode &= ~FMODE_LSEEK;
- if (pde_is_permanent(pde)) {
- open = pde->proc_ops->proc_open;
- if (open)
- rv = open(inode, file);
- return rv;
- }
- /*
- * Ensure that
- * 1) PDE's ->release hook will be called no matter what
- * either normally by close()/->release, or forcefully by
- * rmmod/remove_proc_entry.
- *
- * 2) rmmod isn't blocked by opening file in /proc and sitting on
- * the descriptor (including "rmmod foo </proc/foo" scenario).
- *
- * Save every "struct file" with custom ->release hook.
- */
- if (!use_pde(pde))
- return -ENOENT;
- release = pde->proc_ops->proc_release;
- if (release) {
- pdeo = kmem_cache_alloc(pde_opener_cache, GFP_KERNEL);
- if (!pdeo) {
- rv = -ENOMEM;
- goto out_unuse;
- }
- }
- open = pde->proc_ops->proc_open;
- if (open)
- rv = open(inode, file);
- if (release) {
- if (rv == 0) {
- /* To know what to release. */
- pdeo->file = file;
- pdeo->closing = false;
- pdeo->c = NULL;
- spin_lock(&pde->pde_unload_lock);
- list_add(&pdeo->lh, &pde->pde_openers);
- spin_unlock(&pde->pde_unload_lock);
- } else
- kmem_cache_free(pde_opener_cache, pdeo);
- }
- out_unuse:
- unuse_pde(pde);
- return rv;
- }
- static int proc_reg_release(struct inode *inode, struct file *file)
- {
- struct proc_dir_entry *pde = PDE(inode);
- struct pde_opener *pdeo;
- if (pde_is_permanent(pde)) {
- typeof_member(struct proc_ops, proc_release) release;
- release = pde->proc_ops->proc_release;
- if (release) {
- return release(inode, file);
- }
- return 0;
- }
- spin_lock(&pde->pde_unload_lock);
- list_for_each_entry(pdeo, &pde->pde_openers, lh) {
- if (pdeo->file == file) {
- close_pdeo(pde, pdeo);
- return 0;
- }
- }
- spin_unlock(&pde->pde_unload_lock);
- return 0;
- }
- static const struct file_operations proc_reg_file_ops = {
- .llseek = proc_reg_llseek,
- .read = proc_reg_read,
- .write = proc_reg_write,
- .poll = proc_reg_poll,
- .unlocked_ioctl = proc_reg_unlocked_ioctl,
- .mmap = proc_reg_mmap,
- .get_unmapped_area = proc_reg_get_unmapped_area,
- .open = proc_reg_open,
- .release = proc_reg_release,
- };
- static const struct file_operations proc_iter_file_ops = {
- .llseek = proc_reg_llseek,
- .read_iter = proc_reg_read_iter,
- .write = proc_reg_write,
- .splice_read = generic_file_splice_read,
- .poll = proc_reg_poll,
- .unlocked_ioctl = proc_reg_unlocked_ioctl,
- .mmap = proc_reg_mmap,
- .get_unmapped_area = proc_reg_get_unmapped_area,
- .open = proc_reg_open,
- .release = proc_reg_release,
- };
- #ifdef CONFIG_COMPAT
- static const struct file_operations proc_reg_file_ops_compat = {
- .llseek = proc_reg_llseek,
- .read = proc_reg_read,
- .write = proc_reg_write,
- .poll = proc_reg_poll,
- .unlocked_ioctl = proc_reg_unlocked_ioctl,
- .compat_ioctl = proc_reg_compat_ioctl,
- .mmap = proc_reg_mmap,
- .get_unmapped_area = proc_reg_get_unmapped_area,
- .open = proc_reg_open,
- .release = proc_reg_release,
- };
- static const struct file_operations proc_iter_file_ops_compat = {
- .llseek = proc_reg_llseek,
- .read_iter = proc_reg_read_iter,
- .splice_read = generic_file_splice_read,
- .write = proc_reg_write,
- .poll = proc_reg_poll,
- .unlocked_ioctl = proc_reg_unlocked_ioctl,
- .compat_ioctl = proc_reg_compat_ioctl,
- .mmap = proc_reg_mmap,
- .get_unmapped_area = proc_reg_get_unmapped_area,
- .open = proc_reg_open,
- .release = proc_reg_release,
- };
- #endif
- static void proc_put_link(void *p)
- {
- unuse_pde(p);
- }
- static const char *proc_get_link(struct dentry *dentry,
- struct inode *inode,
- struct delayed_call *done)
- {
- struct proc_dir_entry *pde = PDE(inode);
- if (!use_pde(pde))
- return ERR_PTR(-EINVAL);
- set_delayed_call(done, proc_put_link, pde);
- return pde->data;
- }
- const struct inode_operations proc_link_inode_operations = {
- .get_link = proc_get_link,
- };
- struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de)
- {
- struct inode *inode = new_inode(sb);
- if (!inode) {
- pde_put(de);
- return NULL;
- }
- inode->i_private = de->data;
- inode->i_ino = de->low_ino;
- inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
- PROC_I(inode)->pde = de;
- if (is_empty_pde(de)) {
- make_empty_dir_inode(inode);
- return inode;
- }
- if (de->mode) {
- inode->i_mode = de->mode;
- inode->i_uid = de->uid;
- inode->i_gid = de->gid;
- }
- if (de->size)
- inode->i_size = de->size;
- if (de->nlink)
- set_nlink(inode, de->nlink);
- if (S_ISREG(inode->i_mode)) {
- inode->i_op = de->proc_iops;
- if (de->proc_ops->proc_read_iter)
- inode->i_fop = &proc_iter_file_ops;
- else
- inode->i_fop = &proc_reg_file_ops;
- #ifdef CONFIG_COMPAT
- if (de->proc_ops->proc_compat_ioctl) {
- if (de->proc_ops->proc_read_iter)
- inode->i_fop = &proc_iter_file_ops_compat;
- else
- inode->i_fop = &proc_reg_file_ops_compat;
- }
- #endif
- } else if (S_ISDIR(inode->i_mode)) {
- inode->i_op = de->proc_iops;
- inode->i_fop = de->proc_dir_ops;
- } else if (S_ISLNK(inode->i_mode)) {
- inode->i_op = de->proc_iops;
- inode->i_fop = NULL;
- } else {
- BUG();
- }
- return inode;
- }
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