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- // SPDX-License-Identifier: GPL-2.0-or-later
- /* Task credentials management - see Documentation/security/credentials.rst
- *
- * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
- * Written by David Howells ([email protected])
- */
- #include <linux/export.h>
- #include <linux/cred.h>
- #include <linux/slab.h>
- #include <linux/sched.h>
- #include <linux/sched/coredump.h>
- #include <linux/key.h>
- #include <linux/keyctl.h>
- #include <linux/init_task.h>
- #include <linux/security.h>
- #include <linux/binfmts.h>
- #include <linux/cn_proc.h>
- #include <linux/uidgid.h>
- #include <trace/hooks/creds.h>
- #ifdef CONFIG_KDP_CRED
- #include <linux/kdp.h>
- #endif
- #if 0
- #define kdebug(FMT, ...) \
- printk("[%-5.5s%5u] " FMT "\n", \
- current->comm, current->pid, ##__VA_ARGS__)
- #else
- #define kdebug(FMT, ...) \
- do { \
- if (0) \
- no_printk("[%-5.5s%5u] " FMT "\n", \
- current->comm, current->pid, ##__VA_ARGS__); \
- } while (0)
- #endif
- static struct kmem_cache *cred_jar;
- /* init to 2 - one for init_task, one to ensure it is never freed */
- static struct group_info init_groups = { .usage = ATOMIC_INIT(2) };
- /*
- * The initial credentials for the initial task
- */
- struct cred init_cred
- #ifdef CONFIG_KDP_CRED
- __kdp_ro
- #endif
- = {
- .usage = ATOMIC_INIT(4),
- #ifdef CONFIG_DEBUG_CREDENTIALS
- .subscribers = ATOMIC_INIT(2),
- .magic = CRED_MAGIC,
- #endif
- .uid = GLOBAL_ROOT_UID,
- .gid = GLOBAL_ROOT_GID,
- .suid = GLOBAL_ROOT_UID,
- .sgid = GLOBAL_ROOT_GID,
- .euid = GLOBAL_ROOT_UID,
- .egid = GLOBAL_ROOT_GID,
- .fsuid = GLOBAL_ROOT_UID,
- .fsgid = GLOBAL_ROOT_GID,
- .securebits = SECUREBITS_DEFAULT,
- .cap_inheritable = CAP_EMPTY_SET,
- .cap_permitted = CAP_FULL_SET,
- .cap_effective = CAP_FULL_SET,
- .cap_bset = CAP_FULL_SET,
- .user = INIT_USER,
- .user_ns = &init_user_ns,
- .group_info = &init_groups,
- .ucounts = &init_ucounts,
- };
- static inline void set_cred_subscribers(struct cred *cred, int n)
- {
- #ifdef CONFIG_DEBUG_CREDENTIALS
- atomic_set(&cred->subscribers, n);
- #endif
- }
- static inline int read_cred_subscribers(const struct cred *cred)
- {
- #ifdef CONFIG_DEBUG_CREDENTIALS
- return atomic_read(&cred->subscribers);
- #else
- return 0;
- #endif
- }
- static inline void alter_cred_subscribers(const struct cred *_cred, int n)
- {
- #ifdef CONFIG_DEBUG_CREDENTIALS
- struct cred *cred = (struct cred *) _cred;
- atomic_add(n, &cred->subscribers);
- #endif
- }
- /*
- * The RCU callback to actually dispose of a set of credentials
- */
- static void put_cred_rcu(struct rcu_head *rcu)
- {
- struct cred *cred = container_of(rcu, struct cred, rcu);
- kdebug("put_cred_rcu(%p)", cred);
- #ifdef CONFIG_DEBUG_CREDENTIALS
- if (cred->magic != CRED_MAGIC_DEAD ||
- atomic_read(&cred->usage) != 0 ||
- read_cred_subscribers(cred) != 0)
- panic("CRED: put_cred_rcu() sees %p with"
- " mag %x, put %p, usage %d, subscr %d\n",
- cred, cred->magic, cred->put_addr,
- atomic_read(&cred->usage),
- read_cred_subscribers(cred));
- #else
- if (atomic_read(&cred->usage) != 0)
- panic("CRED: put_cred_rcu() sees %p with usage %d\n",
- cred, atomic_read(&cred->usage));
- #endif
- security_cred_free(cred);
- key_put(cred->session_keyring);
- key_put(cred->process_keyring);
- key_put(cred->thread_keyring);
- key_put(cred->request_key_auth);
- if (cred->group_info)
- put_group_info(cred->group_info);
- free_uid(cred->user);
- if (cred->ucounts)
- put_ucounts(cred->ucounts);
- put_user_ns(cred->user_ns);
- kmem_cache_free(cred_jar, cred);
- }
- /**
- * __put_cred - Destroy a set of credentials
- * @cred: The record to release
- *
- * Destroy a set of credentials on which no references remain.
- */
- void __put_cred(struct cred *cred)
- {
- kdebug("__put_cred(%p{%d,%d})", cred,
- atomic_read(&cred->usage),
- read_cred_subscribers(cred));
- #ifdef CONFIG_KDP_CRED
- BUG_ON(kdp_get_usecount(cred) != 0);
- #else
- BUG_ON(atomic_read(&cred->usage) != 0);
- #endif
- #ifdef CONFIG_DEBUG_CREDENTIALS
- BUG_ON(read_cred_subscribers(cred) != 0);
- cred->magic = CRED_MAGIC_DEAD;
- cred->put_addr = __builtin_return_address(0);
- #endif
- #ifdef CONFIG_KDP_CRED
- if(cred == current->cred)
- printk("[KDP] cred->security: 0x%lx\n", (unsigned long) cred->security);
- #endif
- BUG_ON(cred == current->cred);
- BUG_ON(cred == current->real_cred);
- #ifdef CONFIG_KDP_CRED
- kdp_put_cred_rcu(cred, (void *)put_cred_rcu);
- #else
- if (cred->non_rcu)
- put_cred_rcu(&cred->rcu);
- else
- call_rcu(&cred->rcu, put_cred_rcu);
- #endif
- }
- EXPORT_SYMBOL(__put_cred);
- /*
- * Clean up a task's credentials when it exits
- */
- void exit_creds(struct task_struct *tsk)
- {
- struct cred *cred;
- kdebug("exit_creds(%u,%p,%p,{%d,%d})", tsk->pid, tsk->real_cred, tsk->cred,
- atomic_read(&tsk->cred->usage),
- read_cred_subscribers(tsk->cred));
- cred = (struct cred *) tsk->real_cred;
- tsk->real_cred = NULL;
- validate_creds(cred);
- alter_cred_subscribers(cred, -1);
- put_cred(cred);
- cred = (struct cred *) tsk->cred;
- tsk->cred = NULL;
- validate_creds(cred);
- alter_cred_subscribers(cred, -1);
- put_cred(cred);
- #ifdef CONFIG_KEYS_REQUEST_CACHE
- key_put(tsk->cached_requested_key);
- tsk->cached_requested_key = NULL;
- #endif
- trace_android_rvh_exit_creds(tsk, cred);
- }
- /**
- * get_task_cred - Get another task's objective credentials
- * @task: The task to query
- *
- * Get the objective credentials of a task, pinning them so that they can't go
- * away. Accessing a task's credentials directly is not permitted.
- *
- * The caller must also make sure task doesn't get deleted, either by holding a
- * ref on task or by holding tasklist_lock to prevent it from being unlinked.
- */
- const struct cred *get_task_cred(struct task_struct *task)
- {
- const struct cred *cred;
- rcu_read_lock();
- do {
- cred = __task_cred((task));
- BUG_ON(!cred);
- } while (!get_cred_rcu(cred));
- rcu_read_unlock();
- return cred;
- }
- EXPORT_SYMBOL(get_task_cred);
- /*
- * Allocate blank credentials, such that the credentials can be filled in at a
- * later date without risk of ENOMEM.
- */
- struct cred *cred_alloc_blank(void)
- {
- struct cred *new;
- new = kmem_cache_zalloc(cred_jar, GFP_KERNEL);
- if (!new)
- return NULL;
- atomic_set(&new->usage, 1);
- #ifdef CONFIG_DEBUG_CREDENTIALS
- new->magic = CRED_MAGIC;
- #endif
- if (security_cred_alloc_blank(new, GFP_KERNEL_ACCOUNT) < 0)
- goto error;
- return new;
- error:
- abort_creds(new);
- return NULL;
- }
- /**
- * prepare_creds - Prepare a new set of credentials for modification
- *
- * Prepare a new set of task credentials for modification. A task's creds
- * shouldn't generally be modified directly, therefore this function is used to
- * prepare a new copy, which the caller then modifies and then commits by
- * calling commit_creds().
- *
- * Preparation involves making a copy of the objective creds for modification.
- *
- * Returns a pointer to the new creds-to-be if successful, NULL otherwise.
- *
- * Call commit_creds() or abort_creds() to clean up.
- */
- struct cred *prepare_creds(void)
- {
- struct task_struct *task = current;
- const struct cred *old;
- struct cred *new;
- validate_process_creds();
- new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
- if (!new)
- return NULL;
- kdebug("prepare_creds() alloc %p", new);
- old = task->cred;
- memcpy(new, old, sizeof(struct cred));
- new->non_rcu = 0;
- atomic_set(&new->usage, 1);
- set_cred_subscribers(new, 0);
- get_group_info(new->group_info);
- get_uid(new->user);
- get_user_ns(new->user_ns);
- #ifdef CONFIG_KEYS
- key_get(new->session_keyring);
- key_get(new->process_keyring);
- key_get(new->thread_keyring);
- key_get(new->request_key_auth);
- #endif
- #ifdef CONFIG_SECURITY
- new->security = NULL;
- #endif
- new->ucounts = get_ucounts(new->ucounts);
- if (!new->ucounts)
- goto error;
- if (security_prepare_creds(new, old, GFP_KERNEL_ACCOUNT) < 0)
- goto error;
- validate_creds(new);
- return new;
- error:
- abort_creds(new);
- return NULL;
- }
- EXPORT_SYMBOL(prepare_creds);
- /*
- * Prepare credentials for current to perform an execve()
- * - The caller must hold ->cred_guard_mutex
- */
- struct cred *prepare_exec_creds(void)
- {
- struct cred *new;
- new = prepare_creds();
- if (!new)
- return new;
- #ifdef CONFIG_KEYS
- /* newly exec'd tasks don't get a thread keyring */
- key_put(new->thread_keyring);
- new->thread_keyring = NULL;
- /* inherit the session keyring; new process keyring */
- key_put(new->process_keyring);
- new->process_keyring = NULL;
- #endif
- new->suid = new->fsuid = new->euid;
- new->sgid = new->fsgid = new->egid;
- return new;
- }
- /*
- * Copy credentials for the new process created by fork()
- *
- * We share if we can, but under some circumstances we have to generate a new
- * set.
- *
- * The new process gets the current process's subjective credentials as its
- * objective and subjective credentials
- */
- int copy_creds(struct task_struct *p, unsigned long clone_flags)
- {
- struct cred *new;
- int ret;
- #ifdef CONFIG_KEYS_REQUEST_CACHE
- p->cached_requested_key = NULL;
- #endif
- #ifdef CONFIG_KDP_CRED
- if (!kdp_enable){
- #endif
- if (
- #ifdef CONFIG_KEYS
- !p->cred->thread_keyring &&
- #endif
- clone_flags & CLONE_THREAD
- ) {
- p->real_cred = get_cred(p->cred);
- get_cred(p->cred);
- alter_cred_subscribers(p->cred, 2);
- kdebug("share_creds(%p{%d,%d})",
- p->cred, atomic_read(&p->cred->usage),
- read_cred_subscribers(p->cred));
- inc_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
- return 0;
- }
- #ifdef CONFIG_KDP_CRED
- }
- #endif
- new = prepare_creds();
- if (!new)
- return -ENOMEM;
- if (clone_flags & CLONE_NEWUSER) {
- ret = create_user_ns(new);
- if (ret < 0)
- goto error_put;
- ret = set_cred_ucounts(new);
- if (ret < 0)
- goto error_put;
- }
- #ifdef CONFIG_KEYS
- /* new threads get their own thread keyrings if their parent already
- * had one */
- if (new->thread_keyring) {
- key_put(new->thread_keyring);
- new->thread_keyring = NULL;
- if (clone_flags & CLONE_THREAD)
- install_thread_keyring_to_cred(new);
- }
- /* The process keyring is only shared between the threads in a process;
- * anything outside of those threads doesn't inherit.
- */
- if (!(clone_flags & CLONE_THREAD)) {
- key_put(new->process_keyring);
- new->process_keyring = NULL;
- }
- #endif
- #ifdef CONFIG_KDP_CRED
- if (kdp_enable) {
- p->cred = p->real_cred = prepare_ro_creds(new, CMD_COPY_CREDS, (u64)p);
- inc_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
- put_cred(new);
- } else {
- p->cred = p->real_cred = get_cred(new);
- inc_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
- alter_cred_subscribers(new, 2);
- validate_creds(new);
- }
- #else
- p->cred = p->real_cred = get_cred(new);
- inc_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
- alter_cred_subscribers(new, 2);
- validate_creds(new);
- #endif
- return 0;
- error_put:
- put_cred(new);
- return ret;
- }
- static bool cred_cap_issubset(const struct cred *set, const struct cred *subset)
- {
- const struct user_namespace *set_ns = set->user_ns;
- const struct user_namespace *subset_ns = subset->user_ns;
- /* If the two credentials are in the same user namespace see if
- * the capabilities of subset are a subset of set.
- */
- if (set_ns == subset_ns)
- return cap_issubset(subset->cap_permitted, set->cap_permitted);
- /* The credentials are in a different user namespaces
- * therefore one is a subset of the other only if a set is an
- * ancestor of subset and set->euid is owner of subset or one
- * of subsets ancestors.
- */
- for (;subset_ns != &init_user_ns; subset_ns = subset_ns->parent) {
- if ((set_ns == subset_ns->parent) &&
- uid_eq(subset_ns->owner, set->euid))
- return true;
- }
- return false;
- }
- /**
- * commit_creds - Install new credentials upon the current task
- * @new: The credentials to be assigned
- *
- * Install a new set of credentials to the current task, using RCU to replace
- * the old set. Both the objective and the subjective credentials pointers are
- * updated. This function may not be called if the subjective credentials are
- * in an overridden state.
- *
- * This function eats the caller's reference to the new credentials.
- *
- * Always returns 0 thus allowing this function to be tail-called at the end
- * of, say, sys_setgid().
- */
- int commit_creds(struct cred *new)
- {
- struct task_struct *task = current;
- const struct cred *old = task->real_cred;
- kdebug("commit_creds(%p{%d,%d})", new,
- atomic_read(&new->usage),
- read_cred_subscribers(new));
- BUG_ON(task->cred != old);
- #ifdef CONFIG_DEBUG_CREDENTIALS
- BUG_ON(read_cred_subscribers(old) < 2);
- validate_creds(old);
- validate_creds(new);
- #endif
- #ifdef CONFIG_KDP_CRED
- BUG_ON(kdp_get_usecount(new) < 1);
- #else
- BUG_ON(atomic_read(&new->usage) < 1);
- #endif
- get_cred(new); /* we will require a ref for the subj creds too */
- /* dumpability changes */
- if (!uid_eq(old->euid, new->euid) ||
- !gid_eq(old->egid, new->egid) ||
- !uid_eq(old->fsuid, new->fsuid) ||
- !gid_eq(old->fsgid, new->fsgid) ||
- !cred_cap_issubset(old, new)) {
- if (task->mm)
- set_dumpable(task->mm, suid_dumpable);
- task->pdeath_signal = 0;
- /*
- * If a task drops privileges and becomes nondumpable,
- * the dumpability change must become visible before
- * the credential change; otherwise, a __ptrace_may_access()
- * racing with this change may be able to attach to a task it
- * shouldn't be able to attach to (as if the task had dropped
- * privileges without becoming nondumpable).
- * Pairs with a read barrier in __ptrace_may_access().
- */
- smp_wmb();
- }
- /* alter the thread keyring */
- if (!uid_eq(new->fsuid, old->fsuid))
- key_fsuid_changed(new);
- if (!gid_eq(new->fsgid, old->fsgid))
- key_fsgid_changed(new);
- /* do it
- * RLIMIT_NPROC limits on user->processes have already been checked
- * in set_user().
- */
- alter_cred_subscribers(new, 2);
- if (new->user != old->user || new->user_ns != old->user_ns)
- inc_rlimit_ucounts(new->ucounts, UCOUNT_RLIMIT_NPROC, 1);
- #ifdef CONFIG_KDP_CRED
- if (kdp_enable) {
- struct cred *new_ro;
- new_ro = prepare_ro_creds(new, CMD_COMMIT_CREDS, 0);
- rcu_assign_pointer(task->real_cred, new_ro);
- rcu_assign_pointer(task->cred, new_ro);
- } else {
- rcu_assign_pointer(task->real_cred, new);
- rcu_assign_pointer(task->cred, new);
- }
- #else
- rcu_assign_pointer(task->real_cred, new);
- rcu_assign_pointer(task->cred, new);
- #endif
- trace_android_rvh_commit_creds(task, new);
- if (new->user != old->user || new->user_ns != old->user_ns)
- dec_rlimit_ucounts(old->ucounts, UCOUNT_RLIMIT_NPROC, 1);
- alter_cred_subscribers(old, -2);
- /* send notifications */
- if (!uid_eq(new->uid, old->uid) ||
- !uid_eq(new->euid, old->euid) ||
- !uid_eq(new->suid, old->suid) ||
- !uid_eq(new->fsuid, old->fsuid))
- proc_id_connector(task, PROC_EVENT_UID);
- if (!gid_eq(new->gid, old->gid) ||
- !gid_eq(new->egid, old->egid) ||
- !gid_eq(new->sgid, old->sgid) ||
- !gid_eq(new->fsgid, old->fsgid))
- proc_id_connector(task, PROC_EVENT_GID);
- #ifdef CONFIG_KDP_CRED
- if (kdp_enable) {
- put_cred(new);
- put_cred(new);
- }
- #endif
- /* release the old obj and subj refs both */
- put_cred(old);
- put_cred(old);
- return 0;
- }
- EXPORT_SYMBOL(commit_creds);
- /**
- * abort_creds - Discard a set of credentials and unlock the current task
- * @new: The credentials that were going to be applied
- *
- * Discard a set of credentials that were under construction and unlock the
- * current task.
- */
- void abort_creds(struct cred *new)
- {
- #ifdef CONFIG_KDP_CRED
- int ret = 0;
- #endif
- kdebug("abort_creds(%p{%d,%d})", new,
- atomic_read(&new->usage),
- read_cred_subscribers(new));
- #ifdef CONFIG_DEBUG_CREDENTIALS
- BUG_ON(read_cred_subscribers(new) != 0);
- #endif
- #ifdef CONFIG_KDP_CRED
- ret = is_kdp_protect_addr((unsigned long)new);
- if (ret == PROTECT_INIT)
- BUG_ON(atomic_read(init_cred_kdp.use_cnt) < 1);
- else if (ret == PROTECT_KMEM)
- BUG_ON(atomic_read(((struct cred_kdp *)new)->use_cnt) < 1);
- else
- #endif
- BUG_ON(atomic_read(&new->usage) < 1);
- put_cred(new);
- }
- EXPORT_SYMBOL(abort_creds);
- /**
- * override_creds - Override the current process's subjective credentials
- * @new: The credentials to be assigned
- *
- * Install a set of temporary override subjective credentials on the current
- * process, returning the old set for later reversion.
- */
- const struct cred *override_creds(const struct cred *new)
- {
- const struct cred *old = current->cred;
- kdebug("override_creds(%p{%d,%d})", new,
- atomic_read(&new->usage),
- read_cred_subscribers(new));
- validate_creds(old);
- validate_creds(new);
- /*
- * NOTE! This uses 'get_new_cred()' rather than 'get_cred()'.
- *
- * That means that we do not clear the 'non_rcu' flag, since
- * we are only installing the cred into the thread-synchronous
- * '->cred' pointer, not the '->real_cred' pointer that is
- * visible to other threads under RCU.
- *
- * Also note that we did validate_creds() manually, not depending
- * on the validation in 'get_cred()'.
- */
- get_new_cred((struct cred *)new);
- alter_cred_subscribers(new, 1);
- #ifdef CONFIG_KDP_CRED
- if (kdp_enable) {
- volatile unsigned int kdp_use_count = kdp_get_usecount((struct cred *)new);
- struct cred *new_ro;
-
- new_ro = prepare_ro_creds((struct cred *)new, CMD_OVRD_CREDS, kdp_use_count);
- GET_ROCRED_RCU(new_ro)->reflected_cred = (void *)new;
- rcu_assign_pointer(current->cred, new_ro);
- } else
- #endif
- rcu_assign_pointer(current->cred, new);
- trace_android_rvh_override_creds(current, new);
- alter_cred_subscribers(old, -1);
- kdebug("override_creds() = %p{%d,%d}", old,
- atomic_read(&old->usage),
- read_cred_subscribers(old));
- return old;
- }
- EXPORT_SYMBOL(override_creds);
- /**
- * revert_creds - Revert a temporary subjective credentials override
- * @old: The credentials to be restored
- *
- * Revert a temporary set of override subjective credentials to an old set,
- * discarding the override set.
- */
- void revert_creds(const struct cred *old)
- {
- const struct cred *override = current->cred;
- kdebug("revert_creds(%p{%d,%d})", old,
- atomic_read(&old->usage),
- read_cred_subscribers(old));
- validate_creds(old);
- validate_creds(override);
- alter_cred_subscribers(old, 1);
- rcu_assign_pointer(current->cred, old);
- trace_android_rvh_revert_creds(current, old);
- alter_cred_subscribers(override, -1);
- #ifdef CONFIG_KDP_CRED
- if (kdp_enable) {
- if (is_kdp_protect_addr((unsigned long)override)){
- if(GET_ROCRED_RCU(override)->reflected_cred)
- put_cred((struct cred *)GET_ROCRED_RCU(override)->reflected_cred);
- put_cred(override);
- }
- }
- #endif
- put_cred(override);
- }
- EXPORT_SYMBOL(revert_creds);
- /**
- * cred_fscmp - Compare two credentials with respect to filesystem access.
- * @a: The first credential
- * @b: The second credential
- *
- * cred_cmp() will return zero if both credentials have the same
- * fsuid, fsgid, and supplementary groups. That is, if they will both
- * provide the same access to files based on mode/uid/gid.
- * If the credentials are different, then either -1 or 1 will
- * be returned depending on whether @a comes before or after @b
- * respectively in an arbitrary, but stable, ordering of credentials.
- *
- * Return: -1, 0, or 1 depending on comparison
- */
- int cred_fscmp(const struct cred *a, const struct cred *b)
- {
- struct group_info *ga, *gb;
- int g;
- if (a == b)
- return 0;
- if (uid_lt(a->fsuid, b->fsuid))
- return -1;
- if (uid_gt(a->fsuid, b->fsuid))
- return 1;
- if (gid_lt(a->fsgid, b->fsgid))
- return -1;
- if (gid_gt(a->fsgid, b->fsgid))
- return 1;
- ga = a->group_info;
- gb = b->group_info;
- if (ga == gb)
- return 0;
- if (ga == NULL)
- return -1;
- if (gb == NULL)
- return 1;
- if (ga->ngroups < gb->ngroups)
- return -1;
- if (ga->ngroups > gb->ngroups)
- return 1;
- for (g = 0; g < ga->ngroups; g++) {
- if (gid_lt(ga->gid[g], gb->gid[g]))
- return -1;
- if (gid_gt(ga->gid[g], gb->gid[g]))
- return 1;
- }
- return 0;
- }
- EXPORT_SYMBOL(cred_fscmp);
- int set_cred_ucounts(struct cred *new)
- {
- struct ucounts *new_ucounts, *old_ucounts = new->ucounts;
- /*
- * This optimization is needed because alloc_ucounts() uses locks
- * for table lookups.
- */
- if (old_ucounts->ns == new->user_ns && uid_eq(old_ucounts->uid, new->uid))
- return 0;
- if (!(new_ucounts = alloc_ucounts(new->user_ns, new->uid)))
- return -EAGAIN;
- #ifdef CONFIG_KDP_CRED
- set_rocred_ucounts(new, new_ucounts);
- #else
- new->ucounts = new_ucounts;
- #endif
- put_ucounts(old_ucounts);
- return 0;
- }
- /*
- * initialise the credentials stuff
- */
- void __init cred_init(void)
- {
- /* allocate a slab in which we can store credentials */
- cred_jar = kmem_cache_create("cred_jar", sizeof(struct cred), 0,
- SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, NULL);
- #ifdef CONFIG_KDP_CRED
- kdp_cred_init();
- #endif
- }
- /**
- * prepare_kernel_cred - Prepare a set of credentials for a kernel service
- * @daemon: A userspace daemon to be used as a reference
- *
- * Prepare a set of credentials for a kernel service. This can then be used to
- * override a task's own credentials so that work can be done on behalf of that
- * task that requires a different subjective context.
- *
- * @daemon is used to provide a base for the security record, but can be NULL.
- * If @daemon is supplied, then the security data will be derived from that;
- * otherwise they'll be set to 0 and no groups, full capabilities and no keys.
- *
- * The caller may change these controls afterwards if desired.
- *
- * Returns the new credentials or NULL if out of memory.
- */
- struct cred *prepare_kernel_cred(struct task_struct *daemon)
- {
- const struct cred *old;
- struct cred *new;
- new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
- if (!new)
- return NULL;
- kdebug("prepare_kernel_cred() alloc %p", new);
- if (daemon)
- old = get_task_cred(daemon);
- else
- old = get_cred(&init_cred);
- validate_creds(old);
- *new = *old;
- new->non_rcu = 0;
- atomic_set(&new->usage, 1);
- set_cred_subscribers(new, 0);
- get_uid(new->user);
- get_user_ns(new->user_ns);
- get_group_info(new->group_info);
- #ifdef CONFIG_KEYS
- new->session_keyring = NULL;
- new->process_keyring = NULL;
- new->thread_keyring = NULL;
- new->request_key_auth = NULL;
- new->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
- #endif
- #ifdef CONFIG_SECURITY
- new->security = NULL;
- #endif
- new->ucounts = get_ucounts(new->ucounts);
- if (!new->ucounts)
- goto error;
- if (security_prepare_creds(new, old, GFP_KERNEL_ACCOUNT) < 0)
- goto error;
- put_cred(old);
- validate_creds(new);
- return new;
- error:
- put_cred(new);
- put_cred(old);
- return NULL;
- }
- EXPORT_SYMBOL(prepare_kernel_cred);
- /**
- * set_security_override - Set the security ID in a set of credentials
- * @new: The credentials to alter
- * @secid: The LSM security ID to set
- *
- * Set the LSM security ID in a set of credentials so that the subjective
- * security is overridden when an alternative set of credentials is used.
- */
- int set_security_override(struct cred *new, u32 secid)
- {
- return security_kernel_act_as(new, secid);
- }
- EXPORT_SYMBOL(set_security_override);
- /**
- * set_security_override_from_ctx - Set the security ID in a set of credentials
- * @new: The credentials to alter
- * @secctx: The LSM security context to generate the security ID from.
- *
- * Set the LSM security ID in a set of credentials so that the subjective
- * security is overridden when an alternative set of credentials is used. The
- * security ID is specified in string form as a security context to be
- * interpreted by the LSM.
- */
- int set_security_override_from_ctx(struct cred *new, const char *secctx)
- {
- u32 secid;
- int ret;
- ret = security_secctx_to_secid(secctx, strlen(secctx), &secid);
- if (ret < 0)
- return ret;
- return set_security_override(new, secid);
- }
- EXPORT_SYMBOL(set_security_override_from_ctx);
- /**
- * set_create_files_as - Set the LSM file create context in a set of credentials
- * @new: The credentials to alter
- * @inode: The inode to take the context from
- *
- * Change the LSM file creation context in a set of credentials to be the same
- * as the object context of the specified inode, so that the new inodes have
- * the same MAC context as that inode.
- */
- int set_create_files_as(struct cred *new, struct inode *inode)
- {
- if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid))
- return -EINVAL;
- new->fsuid = inode->i_uid;
- new->fsgid = inode->i_gid;
- return security_kernel_create_files_as(new, inode);
- }
- EXPORT_SYMBOL(set_create_files_as);
- #ifdef CONFIG_DEBUG_CREDENTIALS
- bool creds_are_invalid(const struct cred *cred)
- {
- if (cred->magic != CRED_MAGIC)
- return true;
- return false;
- }
- EXPORT_SYMBOL(creds_are_invalid);
- /*
- * dump invalid credentials
- */
- static void dump_invalid_creds(const struct cred *cred, const char *label,
- const struct task_struct *tsk)
- {
- printk(KERN_ERR "CRED: %s credentials: %p %s%s%s\n",
- label, cred,
- cred == &init_cred ? "[init]" : "",
- cred == tsk->real_cred ? "[real]" : "",
- cred == tsk->cred ? "[eff]" : "");
- printk(KERN_ERR "CRED: ->magic=%x, put_addr=%p\n",
- cred->magic, cred->put_addr);
- printk(KERN_ERR "CRED: ->usage=%d, subscr=%d\n",
- atomic_read(&cred->usage),
- read_cred_subscribers(cred));
- printk(KERN_ERR "CRED: ->*uid = { %d,%d,%d,%d }\n",
- from_kuid_munged(&init_user_ns, cred->uid),
- from_kuid_munged(&init_user_ns, cred->euid),
- from_kuid_munged(&init_user_ns, cred->suid),
- from_kuid_munged(&init_user_ns, cred->fsuid));
- printk(KERN_ERR "CRED: ->*gid = { %d,%d,%d,%d }\n",
- from_kgid_munged(&init_user_ns, cred->gid),
- from_kgid_munged(&init_user_ns, cred->egid),
- from_kgid_munged(&init_user_ns, cred->sgid),
- from_kgid_munged(&init_user_ns, cred->fsgid));
- #ifdef CONFIG_SECURITY
- printk(KERN_ERR "CRED: ->security is %p\n", cred->security);
- if ((unsigned long) cred->security >= PAGE_SIZE &&
- (((unsigned long) cred->security & 0xffffff00) !=
- (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8)))
- printk(KERN_ERR "CRED: ->security {%x, %x}\n",
- ((u32*)cred->security)[0],
- ((u32*)cred->security)[1]);
- #endif
- }
- /*
- * report use of invalid credentials
- */
- void __noreturn __invalid_creds(const struct cred *cred, const char *file, unsigned line)
- {
- printk(KERN_ERR "CRED: Invalid credentials\n");
- printk(KERN_ERR "CRED: At %s:%u\n", file, line);
- dump_invalid_creds(cred, "Specified", current);
- BUG();
- }
- EXPORT_SYMBOL(__invalid_creds);
- /*
- * check the credentials on a process
- */
- void __validate_process_creds(struct task_struct *tsk,
- const char *file, unsigned line)
- {
- if (tsk->cred == tsk->real_cred) {
- if (unlikely(read_cred_subscribers(tsk->cred) < 2 ||
- creds_are_invalid(tsk->cred)))
- goto invalid_creds;
- } else {
- if (unlikely(read_cred_subscribers(tsk->real_cred) < 1 ||
- read_cred_subscribers(tsk->cred) < 1 ||
- creds_are_invalid(tsk->real_cred) ||
- creds_are_invalid(tsk->cred)))
- goto invalid_creds;
- }
- return;
- invalid_creds:
- printk(KERN_ERR "CRED: Invalid process credentials\n");
- printk(KERN_ERR "CRED: At %s:%u\n", file, line);
- dump_invalid_creds(tsk->real_cred, "Real", tsk);
- if (tsk->cred != tsk->real_cred)
- dump_invalid_creds(tsk->cred, "Effective", tsk);
- else
- printk(KERN_ERR "CRED: Effective creds == Real creds\n");
- BUG();
- }
- EXPORT_SYMBOL(__validate_process_creds);
- /*
- * check creds for do_exit()
- */
- void validate_creds_for_do_exit(struct task_struct *tsk)
- {
- kdebug("validate_creds_for_do_exit(%p,%p{%d,%d})",
- tsk->real_cred, tsk->cred,
- atomic_read(&tsk->cred->usage),
- read_cred_subscribers(tsk->cred));
- __validate_process_creds(tsk, __FILE__, __LINE__);
- }
- #endif /* CONFIG_DEBUG_CREDENTIALS */
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