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927 lines
24 KiB
927 lines
24 KiB
/* Task credentials management - see Documentation/security/credentials.txt |
|
* |
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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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* This program is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU General Public Licence |
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* as published by the Free Software Foundation; either version |
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* 2 of the Licence, or (at your option) any later version. |
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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/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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|
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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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struct group_info init_groups = { .usage = ATOMIC_INIT(2) }; |
|
|
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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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}; |
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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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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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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_GRKERNSEC_SETXID |
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cred = (struct cred *) tsk->delayed_cred; |
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if (cred != NULL) { |
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tsk->delayed_cred = NULL; |
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validate_creds(cred); |
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put_cred(cred); |
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} |
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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 (!atomic_inc_not_zero(&((struct cred *)cred)->usage)); |
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|
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rcu_read_unlock(); |
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return cred; |
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} |
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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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|
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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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|
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if (security_cred_alloc_blank(new, GFP_KERNEL) < 0) |
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goto error; |
|
|
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return new; |
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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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* 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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|
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validate_process_creds(); |
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|
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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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|
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old = task->cred; |
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memcpy(new, old, sizeof(struct cred)); |
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|
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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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|
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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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|
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#ifdef CONFIG_SECURITY |
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new->security = NULL; |
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#endif |
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|
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if (security_prepare_creds(new, old, GFP_KERNEL) < 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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|
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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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|
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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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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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atomic_inc(&p->cred->user->processes); |
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return 0; |
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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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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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} |
|
|
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#ifdef CONFIG_KEYS |
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/* new threads get their own thread keyrings if their parent already |
|
* 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; |
|
if (clone_flags & CLONE_THREAD) |
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install_thread_keyring_to_cred(new); |
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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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*/ |
|
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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} |
|
#endif |
|
|
|
atomic_inc(&new->user->processes); |
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p->cred = p->real_cred = get_cred(new); |
|
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(). |
|
*/ |
|
static 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 */ |
|
|
|
gr_set_role_label(task, new->uid, new->gid); |
|
|
|
/* 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; |
|
smp_wmb(); |
|
} |
|
|
|
/* alter the thread keyring */ |
|
if (!uid_eq(new->fsuid, old->fsuid)) |
|
key_fsuid_changed(task); |
|
if (!gid_eq(new->fsgid, old->fsgid)) |
|
key_fsgid_changed(task); |
|
|
|
/* 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) |
|
atomic_inc(&new->user->processes); |
|
rcu_assign_pointer(task->real_cred, new); |
|
rcu_assign_pointer(task->cred, new); |
|
if (new->user != old->user) |
|
atomic_dec(&old->user->processes); |
|
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; |
|
} |
|
#ifdef CONFIG_GRKERNSEC_SETXID |
|
extern int set_user(struct cred *new); |
|
|
|
void gr_delayed_cred_worker(void) |
|
{ |
|
const struct cred *new = current->delayed_cred; |
|
struct cred *ncred; |
|
|
|
current->delayed_cred = NULL; |
|
|
|
if (!uid_eq(current_uid(), GLOBAL_ROOT_UID) && new != NULL) { |
|
// from doing get_cred on it when queueing this |
|
put_cred(new); |
|
return; |
|
} else if (new == NULL) |
|
return; |
|
|
|
ncred = prepare_creds(); |
|
if (!ncred) |
|
goto die; |
|
// uids |
|
ncred->uid = new->uid; |
|
ncred->euid = new->euid; |
|
ncred->suid = new->suid; |
|
ncred->fsuid = new->fsuid; |
|
// gids |
|
ncred->gid = new->gid; |
|
ncred->egid = new->egid; |
|
ncred->sgid = new->sgid; |
|
ncred->fsgid = new->fsgid; |
|
// groups |
|
set_groups(ncred, new->group_info); |
|
// caps |
|
ncred->securebits = new->securebits; |
|
ncred->cap_inheritable = new->cap_inheritable; |
|
ncred->cap_permitted = new->cap_permitted; |
|
ncred->cap_effective = new->cap_effective; |
|
ncred->cap_bset = new->cap_bset; |
|
|
|
if (set_user(ncred)) { |
|
abort_creds(ncred); |
|
goto die; |
|
} |
|
|
|
// from doing get_cred on it when queueing this |
|
put_cred(new); |
|
|
|
__commit_creds(ncred); |
|
return; |
|
die: |
|
// from doing get_cred on it when queueing this |
|
put_cred(new); |
|
do_group_exit(SIGKILL); |
|
} |
|
#endif |
|
|
|
int commit_creds(struct cred *new) |
|
{ |
|
#ifdef CONFIG_GRKERNSEC_SETXID |
|
int ret; |
|
int schedule_it = 0; |
|
struct task_struct *t; |
|
unsigned oldsecurebits = current_cred()->securebits; |
|
|
|
/* we won't get called with tasklist_lock held for writing |
|
and interrupts disabled as the cred struct in that case is |
|
init_cred |
|
*/ |
|
if (grsec_enable_setxid && !current_is_single_threaded() && |
|
uid_eq(current_uid(), GLOBAL_ROOT_UID) && |
|
!uid_eq(new->uid, GLOBAL_ROOT_UID)) { |
|
schedule_it = 1; |
|
} |
|
ret = __commit_creds(new); |
|
if (schedule_it) { |
|
rcu_read_lock(); |
|
read_lock(&tasklist_lock); |
|
for (t = next_thread(current); t != current; |
|
t = next_thread(t)) { |
|
/* we'll check if the thread has uid 0 in |
|
* the delayed worker routine |
|
*/ |
|
if (task_securebits(t) == oldsecurebits && |
|
t->delayed_cred == NULL) { |
|
t->delayed_cred = get_cred(new); |
|
set_tsk_thread_flag(t, TIF_GRSEC_SETXID); |
|
set_tsk_need_resched(t); |
|
} |
|
} |
|
read_unlock(&tasklist_lock); |
|
rcu_read_unlock(); |
|
} |
|
|
|
return ret; |
|
#else |
|
return __commit_creds(new); |
|
#endif |
|
} |
|
|
|
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); |
|
get_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); |
|
|
|
/* |
|
* 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. |
|
* |
|
* Does not take, and does not return holding current->cred_replace_mutex. |
|
*/ |
|
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; |
|
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 |
|
if (security_prepare_creds(new, old, GFP_KERNEL) < 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; |
|
#ifdef CONFIG_SECURITY_SELINUX |
|
/* |
|
* cred->security == NULL if security_cred_alloc_blank() or |
|
* security_prepare_creds() returned an error. |
|
*/ |
|
if (selinux_is_enabled() && cred->security) { |
|
if ((unsigned long) cred->security < PAGE_SIZE) |
|
return true; |
|
if ((*(u32 *)cred->security & 0xffffff00) == |
|
(POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8)) |
|
return true; |
|
} |
|
#endif |
|
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 */
|
|
|