| // 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 (dhowells@redhat.com) |
| */ |
| #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> |
| |
| #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 = { |
| .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)); |
| |
| BUG_ON(atomic_read(&cred->usage) != 0); |
| #ifdef CONFIG_DEBUG_CREDENTIALS |
| BUG_ON(read_cred_subscribers(cred) != 0); |
| cred->magic = CRED_MAGIC_DEAD; |
| cred->put_addr = __builtin_return_address(0); |
| #endif |
| BUG_ON(cred == current->cred); |
| BUG_ON(cred == current->real_cred); |
| |
| if (cred->non_rcu) |
| put_cred_rcu(&cred->rcu); |
| else |
| call_rcu(&cred->rcu, put_cred_rcu); |
| } |
| 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_NS(prepare_creds, ANDROID_GKI_VFS_EXPORT_ONLY); |
| |
| /* |
| * 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 |
| |
| 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; |
| } |
| |
| 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 |
| |
| 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); |
| 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 |
| BUG_ON(atomic_read(&new->usage) < 1); |
| |
| 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); |
| rcu_assign_pointer(task->real_cred, new); |
| rcu_assign_pointer(task->cred, new); |
| 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); |
| |
| /* 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) |
| { |
| 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 |
| 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); |
| 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_NS(override_creds, ANDROID_GKI_VFS_EXPORT_ONLY); |
| |
| /** |
| * 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); |
| put_cred(override); |
| } |
| EXPORT_SYMBOL_NS(revert_creds, ANDROID_GKI_VFS_EXPORT_ONLY); |
| |
| /** |
| * 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; |
| |
| new->ucounts = new_ucounts; |
| 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); |
| } |
| |
| /** |
| * 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 __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 */ |