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934 lines
24 KiB
934 lines
24 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* Task credentials management - see Documentation/security/credentials.rst |
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* |
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* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved. |
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* Written by David Howells ([email protected]) |
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*/ |
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#include <linux/export.h> |
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#include <linux/cred.h> |
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#include <linux/slab.h> |
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#include <linux/sched.h> |
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#include <linux/sched/coredump.h> |
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#include <linux/key.h> |
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#include <linux/keyctl.h> |
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#include <linux/init_task.h> |
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#include <linux/security.h> |
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#include <linux/binfmts.h> |
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#include <linux/cn_proc.h> |
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#include <linux/uidgid.h> |
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|
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#if 0 |
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#define kdebug(FMT, ...) \ |
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printk("[%-5.5s%5u] " FMT "\n", \ |
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current->comm, current->pid, ##__VA_ARGS__) |
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#else |
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#define kdebug(FMT, ...) \ |
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do { \ |
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if (0) \ |
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no_printk("[%-5.5s%5u] " FMT "\n", \ |
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current->comm, current->pid, ##__VA_ARGS__); \ |
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} while (0) |
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#endif |
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|
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static struct kmem_cache *cred_jar; |
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|
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/* init to 2 - one for init_task, one to ensure it is never freed */ |
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static struct group_info init_groups = { .usage = ATOMIC_INIT(2) }; |
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|
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/* |
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* The initial credentials for the initial task |
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*/ |
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struct cred init_cred = { |
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.usage = ATOMIC_INIT(4), |
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#ifdef CONFIG_DEBUG_CREDENTIALS |
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.subscribers = ATOMIC_INIT(2), |
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.magic = CRED_MAGIC, |
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#endif |
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.uid = GLOBAL_ROOT_UID, |
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.gid = GLOBAL_ROOT_GID, |
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.suid = GLOBAL_ROOT_UID, |
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.sgid = GLOBAL_ROOT_GID, |
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.euid = GLOBAL_ROOT_UID, |
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.egid = GLOBAL_ROOT_GID, |
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.fsuid = GLOBAL_ROOT_UID, |
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.fsgid = GLOBAL_ROOT_GID, |
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.securebits = SECUREBITS_DEFAULT, |
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.cap_inheritable = CAP_EMPTY_SET, |
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.cap_permitted = CAP_FULL_SET, |
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.cap_effective = CAP_FULL_SET, |
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.cap_bset = CAP_FULL_SET, |
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.user = INIT_USER, |
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.user_ns = &init_user_ns, |
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.group_info = &init_groups, |
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.ucounts = &init_ucounts, |
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}; |
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|
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static inline void set_cred_subscribers(struct cred *cred, int n) |
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{ |
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#ifdef CONFIG_DEBUG_CREDENTIALS |
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atomic_set(&cred->subscribers, n); |
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#endif |
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} |
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|
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static inline int read_cred_subscribers(const struct cred *cred) |
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{ |
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#ifdef CONFIG_DEBUG_CREDENTIALS |
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return atomic_read(&cred->subscribers); |
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#else |
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return 0; |
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#endif |
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} |
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|
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static inline void alter_cred_subscribers(const struct cred *_cred, int n) |
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{ |
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#ifdef CONFIG_DEBUG_CREDENTIALS |
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struct cred *cred = (struct cred *) _cred; |
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|
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atomic_add(n, &cred->subscribers); |
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#endif |
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} |
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|
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/* |
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* The RCU callback to actually dispose of a set of credentials |
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*/ |
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static void put_cred_rcu(struct rcu_head *rcu) |
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{ |
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struct cred *cred = container_of(rcu, struct cred, rcu); |
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|
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kdebug("put_cred_rcu(%p)", cred); |
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|
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#ifdef CONFIG_DEBUG_CREDENTIALS |
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if (cred->magic != CRED_MAGIC_DEAD || |
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atomic_read(&cred->usage) != 0 || |
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read_cred_subscribers(cred) != 0) |
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panic("CRED: put_cred_rcu() sees %p with" |
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" mag %x, put %p, usage %d, subscr %d\n", |
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cred, cred->magic, cred->put_addr, |
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atomic_read(&cred->usage), |
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read_cred_subscribers(cred)); |
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#else |
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if (atomic_read(&cred->usage) != 0) |
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panic("CRED: put_cred_rcu() sees %p with usage %d\n", |
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cred, atomic_read(&cred->usage)); |
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#endif |
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|
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security_cred_free(cred); |
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key_put(cred->session_keyring); |
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key_put(cred->process_keyring); |
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key_put(cred->thread_keyring); |
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key_put(cred->request_key_auth); |
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if (cred->group_info) |
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put_group_info(cred->group_info); |
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free_uid(cred->user); |
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if (cred->ucounts) |
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put_ucounts(cred->ucounts); |
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put_user_ns(cred->user_ns); |
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kmem_cache_free(cred_jar, cred); |
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} |
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|
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/** |
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* __put_cred - Destroy a set of credentials |
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* @cred: The record to release |
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* |
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* Destroy a set of credentials on which no references remain. |
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*/ |
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void __put_cred(struct cred *cred) |
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{ |
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kdebug("__put_cred(%p{%d,%d})", cred, |
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atomic_read(&cred->usage), |
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read_cred_subscribers(cred)); |
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|
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BUG_ON(atomic_read(&cred->usage) != 0); |
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#ifdef CONFIG_DEBUG_CREDENTIALS |
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BUG_ON(read_cred_subscribers(cred) != 0); |
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cred->magic = CRED_MAGIC_DEAD; |
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cred->put_addr = __builtin_return_address(0); |
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#endif |
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BUG_ON(cred == current->cred); |
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BUG_ON(cred == current->real_cred); |
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|
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if (cred->non_rcu) |
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put_cred_rcu(&cred->rcu); |
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else |
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call_rcu(&cred->rcu, put_cred_rcu); |
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} |
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EXPORT_SYMBOL(__put_cred); |
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|
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/* |
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* Clean up a task's credentials when it exits |
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*/ |
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void exit_creds(struct task_struct *tsk) |
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{ |
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struct cred *cred; |
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|
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kdebug("exit_creds(%u,%p,%p,{%d,%d})", tsk->pid, tsk->real_cred, tsk->cred, |
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atomic_read(&tsk->cred->usage), |
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read_cred_subscribers(tsk->cred)); |
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|
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cred = (struct cred *) tsk->real_cred; |
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tsk->real_cred = NULL; |
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validate_creds(cred); |
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alter_cred_subscribers(cred, -1); |
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put_cred(cred); |
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|
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cred = (struct cred *) tsk->cred; |
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tsk->cred = NULL; |
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validate_creds(cred); |
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alter_cred_subscribers(cred, -1); |
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put_cred(cred); |
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|
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#ifdef CONFIG_KEYS_REQUEST_CACHE |
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key_put(tsk->cached_requested_key); |
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tsk->cached_requested_key = NULL; |
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#endif |
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} |
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|
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/** |
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* get_task_cred - Get another task's objective credentials |
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* @task: The task to query |
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* |
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* Get the objective credentials of a task, pinning them so that they can't go |
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* away. Accessing a task's credentials directly is not permitted. |
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* |
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* The caller must also make sure task doesn't get deleted, either by holding a |
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* ref on task or by holding tasklist_lock to prevent it from being unlinked. |
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*/ |
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const struct cred *get_task_cred(struct task_struct *task) |
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{ |
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const struct cred *cred; |
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|
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rcu_read_lock(); |
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|
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do { |
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cred = __task_cred((task)); |
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BUG_ON(!cred); |
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} while (!get_cred_rcu(cred)); |
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rcu_read_unlock(); |
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return cred; |
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} |
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EXPORT_SYMBOL(get_task_cred); |
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|
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/* |
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* Allocate blank credentials, such that the credentials can be filled in at a |
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* later date without risk of ENOMEM. |
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*/ |
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struct cred *cred_alloc_blank(void) |
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{ |
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struct cred *new; |
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|
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new = kmem_cache_zalloc(cred_jar, GFP_KERNEL); |
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if (!new) |
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return NULL; |
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atomic_set(&new->usage, 1); |
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#ifdef CONFIG_DEBUG_CREDENTIALS |
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new->magic = CRED_MAGIC; |
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#endif |
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new->ucounts = get_ucounts(&init_ucounts); |
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|
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if (security_cred_alloc_blank(new, GFP_KERNEL_ACCOUNT) < 0) |
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goto error; |
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|
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return new; |
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|
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error: |
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abort_creds(new); |
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return NULL; |
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} |
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|
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/** |
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* prepare_creds - Prepare a new set of credentials for modification |
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* |
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* Prepare a new set of task credentials for modification. A task's creds |
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* shouldn't generally be modified directly, therefore this function is used to |
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* prepare a new copy, which the caller then modifies and then commits by |
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* calling commit_creds(). |
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* |
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* Preparation involves making a copy of the objective creds for modification. |
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* |
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* Returns a pointer to the new creds-to-be if successful, NULL otherwise. |
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* |
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* Call commit_creds() or abort_creds() to clean up. |
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*/ |
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struct cred *prepare_creds(void) |
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{ |
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struct task_struct *task = current; |
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const struct cred *old; |
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struct cred *new; |
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validate_process_creds(); |
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new = kmem_cache_alloc(cred_jar, GFP_KERNEL); |
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if (!new) |
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return NULL; |
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kdebug("prepare_creds() alloc %p", new); |
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old = task->cred; |
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memcpy(new, old, sizeof(struct cred)); |
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new->non_rcu = 0; |
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atomic_set(&new->usage, 1); |
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set_cred_subscribers(new, 0); |
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get_group_info(new->group_info); |
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get_uid(new->user); |
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get_user_ns(new->user_ns); |
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#ifdef CONFIG_KEYS |
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key_get(new->session_keyring); |
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key_get(new->process_keyring); |
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key_get(new->thread_keyring); |
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key_get(new->request_key_auth); |
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#endif |
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#ifdef CONFIG_SECURITY |
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new->security = NULL; |
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#endif |
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new->ucounts = get_ucounts(new->ucounts); |
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if (!new->ucounts) |
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goto error; |
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if (security_prepare_creds(new, old, GFP_KERNEL_ACCOUNT) < 0) |
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goto error; |
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validate_creds(new); |
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return new; |
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|
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error: |
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abort_creds(new); |
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return NULL; |
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} |
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EXPORT_SYMBOL(prepare_creds); |
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|
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/* |
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* Prepare credentials for current to perform an execve() |
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* - The caller must hold ->cred_guard_mutex |
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*/ |
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struct cred *prepare_exec_creds(void) |
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{ |
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struct cred *new; |
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|
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new = prepare_creds(); |
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if (!new) |
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return new; |
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#ifdef CONFIG_KEYS |
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/* newly exec'd tasks don't get a thread keyring */ |
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key_put(new->thread_keyring); |
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new->thread_keyring = NULL; |
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|
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/* inherit the session keyring; new process keyring */ |
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key_put(new->process_keyring); |
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new->process_keyring = NULL; |
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#endif |
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new->suid = new->fsuid = new->euid; |
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new->sgid = new->fsgid = new->egid; |
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return new; |
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} |
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|
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/* |
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* Copy credentials for the new process created by fork() |
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* |
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* We share if we can, but under some circumstances we have to generate a new |
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* set. |
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* |
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* The new process gets the current process's subjective credentials as its |
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* objective and subjective credentials |
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*/ |
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int copy_creds(struct task_struct *p, unsigned long clone_flags) |
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{ |
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struct cred *new; |
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int ret; |
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|
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#ifdef CONFIG_KEYS_REQUEST_CACHE |
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p->cached_requested_key = NULL; |
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#endif |
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if ( |
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#ifdef CONFIG_KEYS |
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!p->cred->thread_keyring && |
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#endif |
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clone_flags & CLONE_THREAD |
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) { |
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p->real_cred = get_cred(p->cred); |
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get_cred(p->cred); |
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alter_cred_subscribers(p->cred, 2); |
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kdebug("share_creds(%p{%d,%d})", |
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p->cred, atomic_read(&p->cred->usage), |
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read_cred_subscribers(p->cred)); |
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inc_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1); |
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return 0; |
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} |
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|
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new = prepare_creds(); |
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if (!new) |
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return -ENOMEM; |
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|
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if (clone_flags & CLONE_NEWUSER) { |
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ret = create_user_ns(new); |
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if (ret < 0) |
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goto error_put; |
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ret = set_cred_ucounts(new); |
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if (ret < 0) |
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goto error_put; |
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} |
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|
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#ifdef CONFIG_KEYS |
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/* new threads get their own thread keyrings if their parent already |
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* had one */ |
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if (new->thread_keyring) { |
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key_put(new->thread_keyring); |
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new->thread_keyring = NULL; |
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if (clone_flags & CLONE_THREAD) |
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install_thread_keyring_to_cred(new); |
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} |
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|
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/* The process keyring is only shared between the threads in a process; |
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* anything outside of those threads doesn't inherit. |
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*/ |
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if (!(clone_flags & CLONE_THREAD)) { |
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key_put(new->process_keyring); |
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new->process_keyring = NULL; |
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} |
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#endif |
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|
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p->cred = p->real_cred = get_cred(new); |
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inc_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1); |
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alter_cred_subscribers(new, 2); |
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validate_creds(new); |
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return 0; |
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|
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error_put: |
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put_cred(new); |
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return ret; |
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} |
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|
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static bool cred_cap_issubset(const struct cred *set, const struct cred *subset) |
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{ |
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const struct user_namespace *set_ns = set->user_ns; |
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const struct user_namespace *subset_ns = subset->user_ns; |
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|
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/* If the two credentials are in the same user namespace see if |
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* the capabilities of subset are a subset of set. |
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*/ |
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if (set_ns == subset_ns) |
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return cap_issubset(subset->cap_permitted, set->cap_permitted); |
|
|
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/* The credentials are in a different user namespaces |
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* therefore one is a subset of the other only if a set is an |
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* ancestor of subset and set->euid is owner of subset or one |
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* of subsets ancestors. |
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*/ |
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for (;subset_ns != &init_user_ns; subset_ns = subset_ns->parent) { |
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if ((set_ns == subset_ns->parent) && |
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uid_eq(subset_ns->owner, set->euid)) |
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return true; |
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} |
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|
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return false; |
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} |
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|
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/** |
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* commit_creds - Install new credentials upon the current task |
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* @new: The credentials to be assigned |
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* |
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* Install a new set of credentials to the current task, using RCU to replace |
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* the old set. Both the objective and the subjective credentials pointers are |
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* updated. This function may not be called if the subjective credentials are |
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* in an overridden state. |
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* |
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* This function eats the caller's reference to the new credentials. |
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* |
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* Always returns 0 thus allowing this function to be tail-called at the end |
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* of, say, sys_setgid(). |
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*/ |
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int commit_creds(struct cred *new) |
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{ |
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struct task_struct *task = current; |
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const struct cred *old = task->real_cred; |
|
|
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kdebug("commit_creds(%p{%d,%d})", new, |
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atomic_read(&new->usage), |
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read_cred_subscribers(new)); |
|
|
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BUG_ON(task->cred != old); |
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#ifdef CONFIG_DEBUG_CREDENTIALS |
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BUG_ON(read_cred_subscribers(old) < 2); |
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validate_creds(old); |
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validate_creds(new); |
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#endif |
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BUG_ON(atomic_read(&new->usage) < 1); |
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|
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get_cred(new); /* we will require a ref for the subj creds too */ |
|
|
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/* dumpability changes */ |
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if (!uid_eq(old->euid, new->euid) || |
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!gid_eq(old->egid, new->egid) || |
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!uid_eq(old->fsuid, new->fsuid) || |
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!gid_eq(old->fsgid, new->fsgid) || |
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!cred_cap_issubset(old, new)) { |
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if (task->mm) |
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set_dumpable(task->mm, suid_dumpable); |
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task->pdeath_signal = 0; |
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/* |
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* If a task drops privileges and becomes nondumpable, |
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* the dumpability change must become visible before |
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* the credential change; otherwise, a __ptrace_may_access() |
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* racing with this change may be able to attach to a task it |
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* shouldn't be able to attach to (as if the task had dropped |
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* privileges without becoming nondumpable). |
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* Pairs with a read barrier in __ptrace_may_access(). |
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*/ |
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smp_wmb(); |
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} |
|
|
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/* alter the thread keyring */ |
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if (!uid_eq(new->fsuid, old->fsuid)) |
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key_fsuid_changed(new); |
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if (!gid_eq(new->fsgid, old->fsgid)) |
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key_fsgid_changed(new); |
|
|
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/* do it |
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* RLIMIT_NPROC limits on user->processes have already been checked |
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* in set_user(). |
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*/ |
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alter_cred_subscribers(new, 2); |
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if (new->user != old->user || new->user_ns != old->user_ns) |
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inc_rlimit_ucounts(new->ucounts, UCOUNT_RLIMIT_NPROC, 1); |
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rcu_assign_pointer(task->real_cred, new); |
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rcu_assign_pointer(task->cred, new); |
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if (new->user != old->user) |
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dec_rlimit_ucounts(old->ucounts, UCOUNT_RLIMIT_NPROC, 1); |
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alter_cred_subscribers(old, -2); |
|
|
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/* send notifications */ |
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if (!uid_eq(new->uid, old->uid) || |
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!uid_eq(new->euid, old->euid) || |
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!uid_eq(new->suid, old->suid) || |
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!uid_eq(new->fsuid, old->fsuid)) |
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proc_id_connector(task, PROC_EVENT_UID); |
|
|
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if (!gid_eq(new->gid, old->gid) || |
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!gid_eq(new->egid, old->egid) || |
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!gid_eq(new->sgid, old->sgid) || |
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!gid_eq(new->fsgid, old->fsgid)) |
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proc_id_connector(task, PROC_EVENT_GID); |
|
|
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/* release the old obj and subj refs both */ |
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put_cred(old); |
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put_cred(old); |
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return 0; |
|
} |
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EXPORT_SYMBOL(commit_creds); |
|
|
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/** |
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* abort_creds - Discard a set of credentials and unlock the current task |
|
* @new: The credentials that were going to be applied |
|
* |
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* Discard a set of credentials that were under construction and unlock the |
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* current task. |
|
*/ |
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void abort_creds(struct cred *new) |
|
{ |
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kdebug("abort_creds(%p{%d,%d})", new, |
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atomic_read(&new->usage), |
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read_cred_subscribers(new)); |
|
|
|
#ifdef CONFIG_DEBUG_CREDENTIALS |
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BUG_ON(read_cred_subscribers(new) != 0); |
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#endif |
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BUG_ON(atomic_read(&new->usage) < 1); |
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put_cred(new); |
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} |
|
EXPORT_SYMBOL(abort_creds); |
|
|
|
/** |
|
* override_creds - Override the current process's subjective credentials |
|
* @new: The credentials to be assigned |
|
* |
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* Install a set of temporary override subjective credentials on the current |
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* process, returning the old set for later reversion. |
|
*/ |
|
const struct cred *override_creds(const struct cred *new) |
|
{ |
|
const struct cred *old = current->cred; |
|
|
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kdebug("override_creds(%p{%d,%d})", new, |
|
atomic_read(&new->usage), |
|
read_cred_subscribers(new)); |
|
|
|
validate_creds(old); |
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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); |
|
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); |
|
alter_cred_subscribers(override, -1); |
|
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 task_struct *task = current; |
|
const struct cred *old = task->real_cred; |
|
struct ucounts *old_ucounts = new->ucounts; |
|
|
|
if (new->user == old->user && new->user_ns == old->user_ns) |
|
return 0; |
|
|
|
/* |
|
* This optimization is needed because alloc_ucounts() uses locks |
|
* for table lookups. |
|
*/ |
|
if (old_ucounts && old_ucounts->ns == new->user_ns && uid_eq(old_ucounts->uid, new->euid)) |
|
return 0; |
|
|
|
if (!(new->ucounts = alloc_ucounts(new->user_ns, new->euid))) |
|
return -EAGAIN; |
|
|
|
if (old_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 */
|
|
|