Randy Dunlap | d410fa4 | 2011-05-19 15:59:38 -0700 | [diff] [blame] | 1 | /* Task credentials management - see Documentation/security/credentials.txt |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 2 | * |
| 3 | * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved. |
| 4 | * Written by David Howells (dhowells@redhat.com) |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or |
| 7 | * modify it under the terms of the GNU General Public Licence |
| 8 | * as published by the Free Software Foundation; either version |
| 9 | * 2 of the Licence, or (at your option) any later version. |
| 10 | */ |
Paul Gortmaker | 9984de1 | 2011-05-23 14:51:41 -0400 | [diff] [blame] | 11 | #include <linux/export.h> |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 12 | #include <linux/cred.h> |
Tejun Heo | 5a0e3ad | 2010-03-24 17:04:11 +0900 | [diff] [blame] | 13 | #include <linux/slab.h> |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 14 | #include <linux/sched.h> |
| 15 | #include <linux/key.h> |
| 16 | #include <linux/keyctl.h> |
| 17 | #include <linux/init_task.h> |
| 18 | #include <linux/security.h> |
Al Viro | 4040153 | 2012-02-13 03:58:52 +0000 | [diff] [blame] | 19 | #include <linux/binfmts.h> |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 20 | #include <linux/cn_proc.h> |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 21 | |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 22 | #if 0 |
Joe Perches | 52aa853 | 2015-09-09 15:36:09 -0700 | [diff] [blame] | 23 | #define kdebug(FMT, ...) \ |
| 24 | printk("[%-5.5s%5u] " FMT "\n", \ |
| 25 | current->comm, current->pid, ##__VA_ARGS__) |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 26 | #else |
Joe Perches | 52aa853 | 2015-09-09 15:36:09 -0700 | [diff] [blame] | 27 | #define kdebug(FMT, ...) \ |
| 28 | do { \ |
| 29 | if (0) \ |
| 30 | no_printk("[%-5.5s%5u] " FMT "\n", \ |
| 31 | current->comm, current->pid, ##__VA_ARGS__); \ |
| 32 | } while (0) |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 33 | #endif |
| 34 | |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 35 | static struct kmem_cache *cred_jar; |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 36 | |
Iulia Manda | 2813893 | 2015-04-15 16:16:41 -0700 | [diff] [blame] | 37 | /* init to 2 - one for init_task, one to ensure it is never freed */ |
| 38 | struct group_info init_groups = { .usage = ATOMIC_INIT(2) }; |
| 39 | |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 40 | /* |
| 41 | * The initial credentials for the initial task |
| 42 | */ |
| 43 | struct cred init_cred = { |
David Howells | 3b11a1d | 2008-11-14 10:39:26 +1100 | [diff] [blame] | 44 | .usage = ATOMIC_INIT(4), |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 45 | #ifdef CONFIG_DEBUG_CREDENTIALS |
| 46 | .subscribers = ATOMIC_INIT(2), |
| 47 | .magic = CRED_MAGIC, |
| 48 | #endif |
Eric W. Biederman | 078de5f | 2012-02-08 07:00:08 -0800 | [diff] [blame] | 49 | .uid = GLOBAL_ROOT_UID, |
| 50 | .gid = GLOBAL_ROOT_GID, |
| 51 | .suid = GLOBAL_ROOT_UID, |
| 52 | .sgid = GLOBAL_ROOT_GID, |
| 53 | .euid = GLOBAL_ROOT_UID, |
| 54 | .egid = GLOBAL_ROOT_GID, |
| 55 | .fsuid = GLOBAL_ROOT_UID, |
| 56 | .fsgid = GLOBAL_ROOT_GID, |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 57 | .securebits = SECUREBITS_DEFAULT, |
Eric Paris | a3232d2 | 2011-04-01 17:08:45 -0400 | [diff] [blame] | 58 | .cap_inheritable = CAP_EMPTY_SET, |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 59 | .cap_permitted = CAP_FULL_SET, |
Eric Paris | a3232d2 | 2011-04-01 17:08:45 -0400 | [diff] [blame] | 60 | .cap_effective = CAP_FULL_SET, |
| 61 | .cap_bset = CAP_FULL_SET, |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 62 | .user = INIT_USER, |
Serge E. Hallyn | 47a150e | 2011-05-13 04:27:54 +0100 | [diff] [blame] | 63 | .user_ns = &init_user_ns, |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 64 | .group_info = &init_groups, |
| 65 | }; |
| 66 | |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 67 | static inline void set_cred_subscribers(struct cred *cred, int n) |
| 68 | { |
| 69 | #ifdef CONFIG_DEBUG_CREDENTIALS |
| 70 | atomic_set(&cred->subscribers, n); |
| 71 | #endif |
| 72 | } |
| 73 | |
| 74 | static inline int read_cred_subscribers(const struct cred *cred) |
| 75 | { |
| 76 | #ifdef CONFIG_DEBUG_CREDENTIALS |
| 77 | return atomic_read(&cred->subscribers); |
| 78 | #else |
| 79 | return 0; |
| 80 | #endif |
| 81 | } |
| 82 | |
| 83 | static inline void alter_cred_subscribers(const struct cred *_cred, int n) |
| 84 | { |
| 85 | #ifdef CONFIG_DEBUG_CREDENTIALS |
| 86 | struct cred *cred = (struct cred *) _cred; |
| 87 | |
| 88 | atomic_add(n, &cred->subscribers); |
| 89 | #endif |
| 90 | } |
| 91 | |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 92 | /* |
| 93 | * The RCU callback to actually dispose of a set of credentials |
| 94 | */ |
| 95 | static void put_cred_rcu(struct rcu_head *rcu) |
| 96 | { |
| 97 | struct cred *cred = container_of(rcu, struct cred, rcu); |
| 98 | |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 99 | kdebug("put_cred_rcu(%p)", cred); |
| 100 | |
| 101 | #ifdef CONFIG_DEBUG_CREDENTIALS |
| 102 | if (cred->magic != CRED_MAGIC_DEAD || |
| 103 | atomic_read(&cred->usage) != 0 || |
| 104 | read_cred_subscribers(cred) != 0) |
| 105 | panic("CRED: put_cred_rcu() sees %p with" |
| 106 | " mag %x, put %p, usage %d, subscr %d\n", |
| 107 | cred, cred->magic, cred->put_addr, |
| 108 | atomic_read(&cred->usage), |
| 109 | read_cred_subscribers(cred)); |
| 110 | #else |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 111 | if (atomic_read(&cred->usage) != 0) |
| 112 | panic("CRED: put_cred_rcu() sees %p with usage %d\n", |
| 113 | cred, atomic_read(&cred->usage)); |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 114 | #endif |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 115 | |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 116 | security_cred_free(cred); |
David Howells | 3a50597 | 2012-10-02 19:24:29 +0100 | [diff] [blame] | 117 | key_put(cred->session_keyring); |
| 118 | key_put(cred->process_keyring); |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 119 | key_put(cred->thread_keyring); |
| 120 | key_put(cred->request_key_auth); |
David Howells | 4a5d6ba | 2009-09-14 12:45:39 +0100 | [diff] [blame] | 121 | if (cred->group_info) |
| 122 | put_group_info(cred->group_info); |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 123 | free_uid(cred->user); |
Eric W. Biederman | 0093ccb | 2011-11-16 21:52:53 -0800 | [diff] [blame] | 124 | put_user_ns(cred->user_ns); |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 125 | kmem_cache_free(cred_jar, cred); |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 126 | } |
| 127 | |
| 128 | /** |
| 129 | * __put_cred - Destroy a set of credentials |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 130 | * @cred: The record to release |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 131 | * |
| 132 | * Destroy a set of credentials on which no references remain. |
| 133 | */ |
| 134 | void __put_cred(struct cred *cred) |
| 135 | { |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 136 | kdebug("__put_cred(%p{%d,%d})", cred, |
| 137 | atomic_read(&cred->usage), |
| 138 | read_cred_subscribers(cred)); |
| 139 | |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 140 | BUG_ON(atomic_read(&cred->usage) != 0); |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 141 | #ifdef CONFIG_DEBUG_CREDENTIALS |
| 142 | BUG_ON(read_cred_subscribers(cred) != 0); |
| 143 | cred->magic = CRED_MAGIC_DEAD; |
| 144 | cred->put_addr = __builtin_return_address(0); |
| 145 | #endif |
| 146 | BUG_ON(cred == current->cred); |
| 147 | BUG_ON(cred == current->real_cred); |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 148 | |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 149 | call_rcu(&cred->rcu, put_cred_rcu); |
| 150 | } |
| 151 | EXPORT_SYMBOL(__put_cred); |
| 152 | |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 153 | /* |
| 154 | * Clean up a task's credentials when it exits |
| 155 | */ |
| 156 | void exit_creds(struct task_struct *tsk) |
| 157 | { |
| 158 | struct cred *cred; |
| 159 | |
| 160 | kdebug("exit_creds(%u,%p,%p,{%d,%d})", tsk->pid, tsk->real_cred, tsk->cred, |
| 161 | atomic_read(&tsk->cred->usage), |
| 162 | read_cred_subscribers(tsk->cred)); |
| 163 | |
| 164 | cred = (struct cred *) tsk->real_cred; |
| 165 | tsk->real_cred = NULL; |
| 166 | validate_creds(cred); |
| 167 | alter_cred_subscribers(cred, -1); |
| 168 | put_cred(cred); |
| 169 | |
| 170 | cred = (struct cred *) tsk->cred; |
| 171 | tsk->cred = NULL; |
| 172 | validate_creds(cred); |
| 173 | alter_cred_subscribers(cred, -1); |
| 174 | put_cred(cred); |
David Howells | ee18d64 | 2009-09-02 09:14:21 +0100 | [diff] [blame] | 175 | } |
| 176 | |
David Howells | de09a97 | 2010-07-29 12:45:49 +0100 | [diff] [blame] | 177 | /** |
| 178 | * get_task_cred - Get another task's objective credentials |
| 179 | * @task: The task to query |
| 180 | * |
| 181 | * Get the objective credentials of a task, pinning them so that they can't go |
| 182 | * away. Accessing a task's credentials directly is not permitted. |
| 183 | * |
| 184 | * The caller must also make sure task doesn't get deleted, either by holding a |
| 185 | * ref on task or by holding tasklist_lock to prevent it from being unlinked. |
| 186 | */ |
| 187 | const struct cred *get_task_cred(struct task_struct *task) |
| 188 | { |
| 189 | const struct cred *cred; |
| 190 | |
| 191 | rcu_read_lock(); |
| 192 | |
| 193 | do { |
| 194 | cred = __task_cred((task)); |
| 195 | BUG_ON(!cred); |
| 196 | } while (!atomic_inc_not_zero(&((struct cred *)cred)->usage)); |
| 197 | |
| 198 | rcu_read_unlock(); |
| 199 | return cred; |
| 200 | } |
| 201 | |
David Howells | ee18d64 | 2009-09-02 09:14:21 +0100 | [diff] [blame] | 202 | /* |
| 203 | * Allocate blank credentials, such that the credentials can be filled in at a |
| 204 | * later date without risk of ENOMEM. |
| 205 | */ |
| 206 | struct cred *cred_alloc_blank(void) |
| 207 | { |
| 208 | struct cred *new; |
| 209 | |
| 210 | new = kmem_cache_zalloc(cred_jar, GFP_KERNEL); |
| 211 | if (!new) |
| 212 | return NULL; |
| 213 | |
David Howells | ee18d64 | 2009-09-02 09:14:21 +0100 | [diff] [blame] | 214 | atomic_set(&new->usage, 1); |
Tetsuo Handa | 2edeaa3 | 2011-02-07 13:36:10 +0000 | [diff] [blame] | 215 | #ifdef CONFIG_DEBUG_CREDENTIALS |
| 216 | new->magic = CRED_MAGIC; |
| 217 | #endif |
David Howells | ee18d64 | 2009-09-02 09:14:21 +0100 | [diff] [blame] | 218 | |
| 219 | if (security_cred_alloc_blank(new, GFP_KERNEL) < 0) |
| 220 | goto error; |
| 221 | |
David Howells | ee18d64 | 2009-09-02 09:14:21 +0100 | [diff] [blame] | 222 | return new; |
| 223 | |
| 224 | error: |
| 225 | abort_creds(new); |
| 226 | return NULL; |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 227 | } |
| 228 | |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 229 | /** |
| 230 | * prepare_creds - Prepare a new set of credentials for modification |
| 231 | * |
| 232 | * Prepare a new set of task credentials for modification. A task's creds |
| 233 | * shouldn't generally be modified directly, therefore this function is used to |
| 234 | * prepare a new copy, which the caller then modifies and then commits by |
| 235 | * calling commit_creds(). |
| 236 | * |
David Howells | 3b11a1d | 2008-11-14 10:39:26 +1100 | [diff] [blame] | 237 | * Preparation involves making a copy of the objective creds for modification. |
| 238 | * |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 239 | * Returns a pointer to the new creds-to-be if successful, NULL otherwise. |
| 240 | * |
| 241 | * Call commit_creds() or abort_creds() to clean up. |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 242 | */ |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 243 | struct cred *prepare_creds(void) |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 244 | { |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 245 | struct task_struct *task = current; |
| 246 | const struct cred *old; |
| 247 | struct cred *new; |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 248 | |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 249 | validate_process_creds(); |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 250 | |
| 251 | new = kmem_cache_alloc(cred_jar, GFP_KERNEL); |
| 252 | if (!new) |
| 253 | return NULL; |
| 254 | |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 255 | kdebug("prepare_creds() alloc %p", new); |
| 256 | |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 257 | old = task->cred; |
| 258 | memcpy(new, old, sizeof(struct cred)); |
| 259 | |
| 260 | atomic_set(&new->usage, 1); |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 261 | set_cred_subscribers(new, 0); |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 262 | get_group_info(new->group_info); |
| 263 | get_uid(new->user); |
Eric W. Biederman | 0093ccb | 2011-11-16 21:52:53 -0800 | [diff] [blame] | 264 | get_user_ns(new->user_ns); |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 265 | |
David Howells | bb952bb | 2008-11-14 10:39:20 +1100 | [diff] [blame] | 266 | #ifdef CONFIG_KEYS |
David Howells | 3a50597 | 2012-10-02 19:24:29 +0100 | [diff] [blame] | 267 | key_get(new->session_keyring); |
| 268 | key_get(new->process_keyring); |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 269 | key_get(new->thread_keyring); |
| 270 | key_get(new->request_key_auth); |
David Howells | bb952bb | 2008-11-14 10:39:20 +1100 | [diff] [blame] | 271 | #endif |
| 272 | |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 273 | #ifdef CONFIG_SECURITY |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 274 | new->security = NULL; |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 275 | #endif |
| 276 | |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 277 | if (security_prepare_creds(new, old, GFP_KERNEL) < 0) |
| 278 | goto error; |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 279 | validate_creds(new); |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 280 | return new; |
| 281 | |
| 282 | error: |
| 283 | abort_creds(new); |
| 284 | return NULL; |
| 285 | } |
| 286 | EXPORT_SYMBOL(prepare_creds); |
| 287 | |
| 288 | /* |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 289 | * Prepare credentials for current to perform an execve() |
KOSAKI Motohiro | 9b1bf12 | 2010-10-27 15:34:08 -0700 | [diff] [blame] | 290 | * - The caller must hold ->cred_guard_mutex |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 291 | */ |
| 292 | struct cred *prepare_exec_creds(void) |
| 293 | { |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 294 | struct cred *new; |
| 295 | |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 296 | new = prepare_creds(); |
David Howells | 3a50597 | 2012-10-02 19:24:29 +0100 | [diff] [blame] | 297 | if (!new) |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 298 | return new; |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 299 | |
| 300 | #ifdef CONFIG_KEYS |
| 301 | /* newly exec'd tasks don't get a thread keyring */ |
| 302 | key_put(new->thread_keyring); |
| 303 | new->thread_keyring = NULL; |
| 304 | |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 305 | /* inherit the session keyring; new process keyring */ |
David Howells | 3a50597 | 2012-10-02 19:24:29 +0100 | [diff] [blame] | 306 | key_put(new->process_keyring); |
| 307 | new->process_keyring = NULL; |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 308 | #endif |
| 309 | |
| 310 | return new; |
| 311 | } |
| 312 | |
| 313 | /* |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 314 | * Copy credentials for the new process created by fork() |
| 315 | * |
| 316 | * We share if we can, but under some circumstances we have to generate a new |
| 317 | * set. |
David Howells | 3b11a1d | 2008-11-14 10:39:26 +1100 | [diff] [blame] | 318 | * |
| 319 | * The new process gets the current process's subjective credentials as its |
| 320 | * objective and subjective credentials |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 321 | */ |
| 322 | int copy_creds(struct task_struct *p, unsigned long clone_flags) |
| 323 | { |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 324 | struct cred *new; |
Serge Hallyn | 18b6e04 | 2008-10-15 16:38:45 -0500 | [diff] [blame] | 325 | int ret; |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 326 | |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 327 | if ( |
| 328 | #ifdef CONFIG_KEYS |
| 329 | !p->cred->thread_keyring && |
| 330 | #endif |
| 331 | clone_flags & CLONE_THREAD |
| 332 | ) { |
David Howells | 3b11a1d | 2008-11-14 10:39:26 +1100 | [diff] [blame] | 333 | p->real_cred = get_cred(p->cred); |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 334 | get_cred(p->cred); |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 335 | alter_cred_subscribers(p->cred, 2); |
| 336 | kdebug("share_creds(%p{%d,%d})", |
| 337 | p->cred, atomic_read(&p->cred->usage), |
| 338 | read_cred_subscribers(p->cred)); |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 339 | atomic_inc(&p->cred->user->processes); |
| 340 | return 0; |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 341 | } |
| 342 | |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 343 | new = prepare_creds(); |
| 344 | if (!new) |
| 345 | return -ENOMEM; |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 346 | |
Serge Hallyn | 18b6e04 | 2008-10-15 16:38:45 -0500 | [diff] [blame] | 347 | if (clone_flags & CLONE_NEWUSER) { |
| 348 | ret = create_user_ns(new); |
| 349 | if (ret < 0) |
| 350 | goto error_put; |
| 351 | } |
| 352 | |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 353 | #ifdef CONFIG_KEYS |
| 354 | /* new threads get their own thread keyrings if their parent already |
| 355 | * had one */ |
| 356 | if (new->thread_keyring) { |
| 357 | key_put(new->thread_keyring); |
| 358 | new->thread_keyring = NULL; |
| 359 | if (clone_flags & CLONE_THREAD) |
| 360 | install_thread_keyring_to_cred(new); |
| 361 | } |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 362 | |
David Howells | 3a50597 | 2012-10-02 19:24:29 +0100 | [diff] [blame] | 363 | /* The process keyring is only shared between the threads in a process; |
| 364 | * anything outside of those threads doesn't inherit. |
| 365 | */ |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 366 | if (!(clone_flags & CLONE_THREAD)) { |
David Howells | 3a50597 | 2012-10-02 19:24:29 +0100 | [diff] [blame] | 367 | key_put(new->process_keyring); |
| 368 | new->process_keyring = NULL; |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 369 | } |
| 370 | #endif |
| 371 | |
| 372 | atomic_inc(&new->user->processes); |
David Howells | 3b11a1d | 2008-11-14 10:39:26 +1100 | [diff] [blame] | 373 | p->cred = p->real_cred = get_cred(new); |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 374 | alter_cred_subscribers(new, 2); |
| 375 | validate_creds(new); |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 376 | return 0; |
Serge Hallyn | 18b6e04 | 2008-10-15 16:38:45 -0500 | [diff] [blame] | 377 | |
| 378 | error_put: |
| 379 | put_cred(new); |
| 380 | return ret; |
David Howells | f1752ee | 2008-11-14 10:39:17 +1100 | [diff] [blame] | 381 | } |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 382 | |
Eric W. Biederman | aa6d054 | 2012-12-14 08:50:54 -0800 | [diff] [blame] | 383 | static bool cred_cap_issubset(const struct cred *set, const struct cred *subset) |
| 384 | { |
| 385 | const struct user_namespace *set_ns = set->user_ns; |
| 386 | const struct user_namespace *subset_ns = subset->user_ns; |
| 387 | |
| 388 | /* If the two credentials are in the same user namespace see if |
| 389 | * the capabilities of subset are a subset of set. |
| 390 | */ |
| 391 | if (set_ns == subset_ns) |
| 392 | return cap_issubset(subset->cap_permitted, set->cap_permitted); |
| 393 | |
| 394 | /* The credentials are in a different user namespaces |
| 395 | * therefore one is a subset of the other only if a set is an |
| 396 | * ancestor of subset and set->euid is owner of subset or one |
| 397 | * of subsets ancestors. |
| 398 | */ |
| 399 | for (;subset_ns != &init_user_ns; subset_ns = subset_ns->parent) { |
| 400 | if ((set_ns == subset_ns->parent) && |
| 401 | uid_eq(subset_ns->owner, set->euid)) |
| 402 | return true; |
| 403 | } |
| 404 | |
| 405 | return false; |
| 406 | } |
| 407 | |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 408 | /** |
| 409 | * commit_creds - Install new credentials upon the current task |
| 410 | * @new: The credentials to be assigned |
| 411 | * |
| 412 | * Install a new set of credentials to the current task, using RCU to replace |
David Howells | 3b11a1d | 2008-11-14 10:39:26 +1100 | [diff] [blame] | 413 | * the old set. Both the objective and the subjective credentials pointers are |
| 414 | * updated. This function may not be called if the subjective credentials are |
| 415 | * in an overridden state. |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 416 | * |
| 417 | * This function eats the caller's reference to the new credentials. |
| 418 | * |
| 419 | * Always returns 0 thus allowing this function to be tail-called at the end |
| 420 | * of, say, sys_setgid(). |
| 421 | */ |
| 422 | int commit_creds(struct cred *new) |
| 423 | { |
| 424 | struct task_struct *task = current; |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 425 | const struct cred *old = task->real_cred; |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 426 | |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 427 | kdebug("commit_creds(%p{%d,%d})", new, |
| 428 | atomic_read(&new->usage), |
| 429 | read_cred_subscribers(new)); |
| 430 | |
| 431 | BUG_ON(task->cred != old); |
| 432 | #ifdef CONFIG_DEBUG_CREDENTIALS |
| 433 | BUG_ON(read_cred_subscribers(old) < 2); |
| 434 | validate_creds(old); |
| 435 | validate_creds(new); |
| 436 | #endif |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 437 | BUG_ON(atomic_read(&new->usage) < 1); |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 438 | |
David Howells | 3b11a1d | 2008-11-14 10:39:26 +1100 | [diff] [blame] | 439 | get_cred(new); /* we will require a ref for the subj creds too */ |
| 440 | |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 441 | /* dumpability changes */ |
Eric W. Biederman | 078de5f | 2012-02-08 07:00:08 -0800 | [diff] [blame] | 442 | if (!uid_eq(old->euid, new->euid) || |
| 443 | !gid_eq(old->egid, new->egid) || |
| 444 | !uid_eq(old->fsuid, new->fsuid) || |
| 445 | !gid_eq(old->fsgid, new->fsgid) || |
Eric W. Biederman | aa6d054 | 2012-12-14 08:50:54 -0800 | [diff] [blame] | 446 | !cred_cap_issubset(old, new)) { |
David Howells | b945637 | 2009-01-08 11:18:31 +0000 | [diff] [blame] | 447 | if (task->mm) |
| 448 | set_dumpable(task->mm, suid_dumpable); |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 449 | task->pdeath_signal = 0; |
Jann Horn | 122be5a | 2019-05-29 13:31:57 +0200 | [diff] [blame] | 450 | /* |
| 451 | * If a task drops privileges and becomes nondumpable, |
| 452 | * the dumpability change must become visible before |
| 453 | * the credential change; otherwise, a __ptrace_may_access() |
| 454 | * racing with this change may be able to attach to a task it |
| 455 | * shouldn't be able to attach to (as if the task had dropped |
| 456 | * privileges without becoming nondumpable). |
| 457 | * Pairs with a read barrier in __ptrace_may_access(). |
| 458 | */ |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 459 | smp_wmb(); |
| 460 | } |
| 461 | |
| 462 | /* alter the thread keyring */ |
Eric W. Biederman | 078de5f | 2012-02-08 07:00:08 -0800 | [diff] [blame] | 463 | if (!uid_eq(new->fsuid, old->fsuid)) |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 464 | key_fsuid_changed(task); |
Eric W. Biederman | 078de5f | 2012-02-08 07:00:08 -0800 | [diff] [blame] | 465 | if (!gid_eq(new->fsgid, old->fsgid)) |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 466 | key_fsgid_changed(task); |
| 467 | |
| 468 | /* do it |
Vasiliy Kulikov | 72fa599 | 2011-08-08 19:02:04 +0400 | [diff] [blame] | 469 | * RLIMIT_NPROC limits on user->processes have already been checked |
| 470 | * in set_user(). |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 471 | */ |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 472 | alter_cred_subscribers(new, 2); |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 473 | if (new->user != old->user) |
| 474 | atomic_inc(&new->user->processes); |
David Howells | 3b11a1d | 2008-11-14 10:39:26 +1100 | [diff] [blame] | 475 | rcu_assign_pointer(task->real_cred, new); |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 476 | rcu_assign_pointer(task->cred, new); |
| 477 | if (new->user != old->user) |
| 478 | atomic_dec(&old->user->processes); |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 479 | alter_cred_subscribers(old, -2); |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 480 | |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 481 | /* send notifications */ |
Eric W. Biederman | 078de5f | 2012-02-08 07:00:08 -0800 | [diff] [blame] | 482 | if (!uid_eq(new->uid, old->uid) || |
| 483 | !uid_eq(new->euid, old->euid) || |
| 484 | !uid_eq(new->suid, old->suid) || |
| 485 | !uid_eq(new->fsuid, old->fsuid)) |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 486 | proc_id_connector(task, PROC_EVENT_UID); |
| 487 | |
Eric W. Biederman | 078de5f | 2012-02-08 07:00:08 -0800 | [diff] [blame] | 488 | if (!gid_eq(new->gid, old->gid) || |
| 489 | !gid_eq(new->egid, old->egid) || |
| 490 | !gid_eq(new->sgid, old->sgid) || |
| 491 | !gid_eq(new->fsgid, old->fsgid)) |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 492 | proc_id_connector(task, PROC_EVENT_GID); |
| 493 | |
David Howells | 3b11a1d | 2008-11-14 10:39:26 +1100 | [diff] [blame] | 494 | /* release the old obj and subj refs both */ |
| 495 | put_cred(old); |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 496 | put_cred(old); |
| 497 | return 0; |
| 498 | } |
| 499 | EXPORT_SYMBOL(commit_creds); |
| 500 | |
| 501 | /** |
| 502 | * abort_creds - Discard a set of credentials and unlock the current task |
| 503 | * @new: The credentials that were going to be applied |
| 504 | * |
| 505 | * Discard a set of credentials that were under construction and unlock the |
| 506 | * current task. |
| 507 | */ |
| 508 | void abort_creds(struct cred *new) |
| 509 | { |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 510 | kdebug("abort_creds(%p{%d,%d})", new, |
| 511 | atomic_read(&new->usage), |
| 512 | read_cred_subscribers(new)); |
| 513 | |
| 514 | #ifdef CONFIG_DEBUG_CREDENTIALS |
| 515 | BUG_ON(read_cred_subscribers(new) != 0); |
| 516 | #endif |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 517 | BUG_ON(atomic_read(&new->usage) < 1); |
| 518 | put_cred(new); |
| 519 | } |
| 520 | EXPORT_SYMBOL(abort_creds); |
| 521 | |
| 522 | /** |
David Howells | 3b11a1d | 2008-11-14 10:39:26 +1100 | [diff] [blame] | 523 | * override_creds - Override the current process's subjective credentials |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 524 | * @new: The credentials to be assigned |
| 525 | * |
David Howells | 3b11a1d | 2008-11-14 10:39:26 +1100 | [diff] [blame] | 526 | * Install a set of temporary override subjective credentials on the current |
| 527 | * process, returning the old set for later reversion. |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 528 | */ |
| 529 | const struct cred *override_creds(const struct cred *new) |
| 530 | { |
| 531 | const struct cred *old = current->cred; |
| 532 | |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 533 | kdebug("override_creds(%p{%d,%d})", new, |
| 534 | atomic_read(&new->usage), |
| 535 | read_cred_subscribers(new)); |
| 536 | |
| 537 | validate_creds(old); |
| 538 | validate_creds(new); |
| 539 | get_cred(new); |
| 540 | alter_cred_subscribers(new, 1); |
| 541 | rcu_assign_pointer(current->cred, new); |
| 542 | alter_cred_subscribers(old, -1); |
| 543 | |
| 544 | kdebug("override_creds() = %p{%d,%d}", old, |
| 545 | atomic_read(&old->usage), |
| 546 | read_cred_subscribers(old)); |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 547 | return old; |
| 548 | } |
| 549 | EXPORT_SYMBOL(override_creds); |
| 550 | |
| 551 | /** |
David Howells | 3b11a1d | 2008-11-14 10:39:26 +1100 | [diff] [blame] | 552 | * revert_creds - Revert a temporary subjective credentials override |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 553 | * @old: The credentials to be restored |
| 554 | * |
David Howells | 3b11a1d | 2008-11-14 10:39:26 +1100 | [diff] [blame] | 555 | * Revert a temporary set of override subjective credentials to an old set, |
| 556 | * discarding the override set. |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 557 | */ |
| 558 | void revert_creds(const struct cred *old) |
| 559 | { |
| 560 | const struct cred *override = current->cred; |
| 561 | |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 562 | kdebug("revert_creds(%p{%d,%d})", old, |
| 563 | atomic_read(&old->usage), |
| 564 | read_cred_subscribers(old)); |
| 565 | |
| 566 | validate_creds(old); |
| 567 | validate_creds(override); |
| 568 | alter_cred_subscribers(old, 1); |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 569 | rcu_assign_pointer(current->cred, old); |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 570 | alter_cred_subscribers(override, -1); |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 571 | put_cred(override); |
| 572 | } |
| 573 | EXPORT_SYMBOL(revert_creds); |
| 574 | |
| 575 | /* |
| 576 | * initialise the credentials stuff |
| 577 | */ |
| 578 | void __init cred_init(void) |
| 579 | { |
| 580 | /* allocate a slab in which we can store credentials */ |
Vladimir Davydov | 5d09705 | 2016-01-14 15:18:21 -0800 | [diff] [blame] | 581 | cred_jar = kmem_cache_create("cred_jar", sizeof(struct cred), 0, |
| 582 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, NULL); |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 583 | } |
David Howells | 3a3b7ce | 2008-11-14 10:39:28 +1100 | [diff] [blame] | 584 | |
| 585 | /** |
| 586 | * prepare_kernel_cred - Prepare a set of credentials for a kernel service |
| 587 | * @daemon: A userspace daemon to be used as a reference |
| 588 | * |
| 589 | * Prepare a set of credentials for a kernel service. This can then be used to |
| 590 | * override a task's own credentials so that work can be done on behalf of that |
| 591 | * task that requires a different subjective context. |
| 592 | * |
| 593 | * @daemon is used to provide a base for the security record, but can be NULL. |
| 594 | * If @daemon is supplied, then the security data will be derived from that; |
| 595 | * otherwise they'll be set to 0 and no groups, full capabilities and no keys. |
| 596 | * |
| 597 | * The caller may change these controls afterwards if desired. |
| 598 | * |
| 599 | * Returns the new credentials or NULL if out of memory. |
| 600 | * |
| 601 | * Does not take, and does not return holding current->cred_replace_mutex. |
| 602 | */ |
| 603 | struct cred *prepare_kernel_cred(struct task_struct *daemon) |
| 604 | { |
| 605 | const struct cred *old; |
| 606 | struct cred *new; |
| 607 | |
| 608 | new = kmem_cache_alloc(cred_jar, GFP_KERNEL); |
| 609 | if (!new) |
| 610 | return NULL; |
| 611 | |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 612 | kdebug("prepare_kernel_cred() alloc %p", new); |
| 613 | |
David Howells | 3a3b7ce | 2008-11-14 10:39:28 +1100 | [diff] [blame] | 614 | if (daemon) |
| 615 | old = get_task_cred(daemon); |
| 616 | else |
| 617 | old = get_cred(&init_cred); |
| 618 | |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 619 | validate_creds(old); |
| 620 | |
David Howells | 43529c9 | 2009-01-09 16:13:46 +0000 | [diff] [blame] | 621 | *new = *old; |
Tetsuo Handa | fb2b2a1 | 2011-02-07 13:36:16 +0000 | [diff] [blame] | 622 | atomic_set(&new->usage, 1); |
| 623 | set_cred_subscribers(new, 0); |
David Howells | 3a3b7ce | 2008-11-14 10:39:28 +1100 | [diff] [blame] | 624 | get_uid(new->user); |
Eric W. Biederman | 0093ccb | 2011-11-16 21:52:53 -0800 | [diff] [blame] | 625 | get_user_ns(new->user_ns); |
David Howells | 3a3b7ce | 2008-11-14 10:39:28 +1100 | [diff] [blame] | 626 | get_group_info(new->group_info); |
| 627 | |
| 628 | #ifdef CONFIG_KEYS |
David Howells | 3a50597 | 2012-10-02 19:24:29 +0100 | [diff] [blame] | 629 | new->session_keyring = NULL; |
| 630 | new->process_keyring = NULL; |
David Howells | 3a3b7ce | 2008-11-14 10:39:28 +1100 | [diff] [blame] | 631 | new->thread_keyring = NULL; |
David Howells | 3a50597 | 2012-10-02 19:24:29 +0100 | [diff] [blame] | 632 | new->request_key_auth = NULL; |
David Howells | 3a3b7ce | 2008-11-14 10:39:28 +1100 | [diff] [blame] | 633 | new->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING; |
| 634 | #endif |
| 635 | |
| 636 | #ifdef CONFIG_SECURITY |
| 637 | new->security = NULL; |
| 638 | #endif |
| 639 | if (security_prepare_creds(new, old, GFP_KERNEL) < 0) |
| 640 | goto error; |
| 641 | |
David Howells | 3a3b7ce | 2008-11-14 10:39:28 +1100 | [diff] [blame] | 642 | put_cred(old); |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 643 | validate_creds(new); |
David Howells | 3a3b7ce | 2008-11-14 10:39:28 +1100 | [diff] [blame] | 644 | return new; |
| 645 | |
| 646 | error: |
| 647 | put_cred(new); |
David Howells | 0de3368 | 2009-01-09 16:13:41 +0000 | [diff] [blame] | 648 | put_cred(old); |
David Howells | 3a3b7ce | 2008-11-14 10:39:28 +1100 | [diff] [blame] | 649 | return NULL; |
| 650 | } |
| 651 | EXPORT_SYMBOL(prepare_kernel_cred); |
| 652 | |
| 653 | /** |
| 654 | * set_security_override - Set the security ID in a set of credentials |
| 655 | * @new: The credentials to alter |
| 656 | * @secid: The LSM security ID to set |
| 657 | * |
| 658 | * Set the LSM security ID in a set of credentials so that the subjective |
| 659 | * security is overridden when an alternative set of credentials is used. |
| 660 | */ |
| 661 | int set_security_override(struct cred *new, u32 secid) |
| 662 | { |
| 663 | return security_kernel_act_as(new, secid); |
| 664 | } |
| 665 | EXPORT_SYMBOL(set_security_override); |
| 666 | |
| 667 | /** |
| 668 | * set_security_override_from_ctx - Set the security ID in a set of credentials |
| 669 | * @new: The credentials to alter |
| 670 | * @secctx: The LSM security context to generate the security ID from. |
| 671 | * |
| 672 | * Set the LSM security ID in a set of credentials so that the subjective |
| 673 | * security is overridden when an alternative set of credentials is used. The |
| 674 | * security ID is specified in string form as a security context to be |
| 675 | * interpreted by the LSM. |
| 676 | */ |
| 677 | int set_security_override_from_ctx(struct cred *new, const char *secctx) |
| 678 | { |
| 679 | u32 secid; |
| 680 | int ret; |
| 681 | |
| 682 | ret = security_secctx_to_secid(secctx, strlen(secctx), &secid); |
| 683 | if (ret < 0) |
| 684 | return ret; |
| 685 | |
| 686 | return set_security_override(new, secid); |
| 687 | } |
| 688 | EXPORT_SYMBOL(set_security_override_from_ctx); |
| 689 | |
| 690 | /** |
| 691 | * set_create_files_as - Set the LSM file create context in a set of credentials |
| 692 | * @new: The credentials to alter |
| 693 | * @inode: The inode to take the context from |
| 694 | * |
| 695 | * Change the LSM file creation context in a set of credentials to be the same |
| 696 | * as the object context of the specified inode, so that the new inodes have |
| 697 | * the same MAC context as that inode. |
| 698 | */ |
| 699 | int set_create_files_as(struct cred *new, struct inode *inode) |
| 700 | { |
Seth Forshee | 5f65e5c | 2016-04-26 14:36:24 -0500 | [diff] [blame] | 701 | if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) |
| 702 | return -EINVAL; |
David Howells | 3a3b7ce | 2008-11-14 10:39:28 +1100 | [diff] [blame] | 703 | new->fsuid = inode->i_uid; |
| 704 | new->fsgid = inode->i_gid; |
| 705 | return security_kernel_create_files_as(new, inode); |
| 706 | } |
| 707 | EXPORT_SYMBOL(set_create_files_as); |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 708 | |
| 709 | #ifdef CONFIG_DEBUG_CREDENTIALS |
| 710 | |
Andrew Morton | 74908a0 | 2009-09-17 17:47:12 -0700 | [diff] [blame] | 711 | bool creds_are_invalid(const struct cred *cred) |
| 712 | { |
| 713 | if (cred->magic != CRED_MAGIC) |
| 714 | return true; |
Andrew Morton | 74908a0 | 2009-09-17 17:47:12 -0700 | [diff] [blame] | 715 | #ifdef CONFIG_SECURITY_SELINUX |
Tetsuo Handa | 2edeaa3 | 2011-02-07 13:36:10 +0000 | [diff] [blame] | 716 | /* |
| 717 | * cred->security == NULL if security_cred_alloc_blank() or |
| 718 | * security_prepare_creds() returned an error. |
| 719 | */ |
| 720 | if (selinux_is_enabled() && cred->security) { |
Andrew Morton | 74908a0 | 2009-09-17 17:47:12 -0700 | [diff] [blame] | 721 | if ((unsigned long) cred->security < PAGE_SIZE) |
| 722 | return true; |
| 723 | if ((*(u32 *)cred->security & 0xffffff00) == |
| 724 | (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8)) |
| 725 | return true; |
| 726 | } |
| 727 | #endif |
| 728 | return false; |
| 729 | } |
Randy Dunlap | 764db03 | 2009-09-18 11:06:47 -0700 | [diff] [blame] | 730 | EXPORT_SYMBOL(creds_are_invalid); |
Andrew Morton | 74908a0 | 2009-09-17 17:47:12 -0700 | [diff] [blame] | 731 | |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 732 | /* |
| 733 | * dump invalid credentials |
| 734 | */ |
| 735 | static void dump_invalid_creds(const struct cred *cred, const char *label, |
| 736 | const struct task_struct *tsk) |
| 737 | { |
| 738 | printk(KERN_ERR "CRED: %s credentials: %p %s%s%s\n", |
| 739 | label, cred, |
| 740 | cred == &init_cred ? "[init]" : "", |
| 741 | cred == tsk->real_cred ? "[real]" : "", |
| 742 | cred == tsk->cred ? "[eff]" : ""); |
| 743 | printk(KERN_ERR "CRED: ->magic=%x, put_addr=%p\n", |
| 744 | cred->magic, cred->put_addr); |
| 745 | printk(KERN_ERR "CRED: ->usage=%d, subscr=%d\n", |
| 746 | atomic_read(&cred->usage), |
| 747 | read_cred_subscribers(cred)); |
| 748 | printk(KERN_ERR "CRED: ->*uid = { %d,%d,%d,%d }\n", |
Eric W. Biederman | c9235f4 | 2012-04-23 17:06:34 -0700 | [diff] [blame] | 749 | from_kuid_munged(&init_user_ns, cred->uid), |
| 750 | from_kuid_munged(&init_user_ns, cred->euid), |
| 751 | from_kuid_munged(&init_user_ns, cred->suid), |
| 752 | from_kuid_munged(&init_user_ns, cred->fsuid)); |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 753 | printk(KERN_ERR "CRED: ->*gid = { %d,%d,%d,%d }\n", |
Eric W. Biederman | c9235f4 | 2012-04-23 17:06:34 -0700 | [diff] [blame] | 754 | from_kgid_munged(&init_user_ns, cred->gid), |
| 755 | from_kgid_munged(&init_user_ns, cred->egid), |
| 756 | from_kgid_munged(&init_user_ns, cred->sgid), |
| 757 | from_kgid_munged(&init_user_ns, cred->fsgid)); |
David Howells | e0e8173 | 2009-09-02 09:13:40 +0100 | [diff] [blame] | 758 | #ifdef CONFIG_SECURITY |
| 759 | printk(KERN_ERR "CRED: ->security is %p\n", cred->security); |
| 760 | if ((unsigned long) cred->security >= PAGE_SIZE && |
| 761 | (((unsigned long) cred->security & 0xffffff00) != |
| 762 | (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8))) |
| 763 | printk(KERN_ERR "CRED: ->security {%x, %x}\n", |
| 764 | ((u32*)cred->security)[0], |
| 765 | ((u32*)cred->security)[1]); |
| 766 | #endif |
| 767 | } |
| 768 | |
| 769 | /* |
| 770 | * report use of invalid credentials |
| 771 | */ |
| 772 | void __invalid_creds(const struct cred *cred, const char *file, unsigned line) |
| 773 | { |
| 774 | printk(KERN_ERR "CRED: Invalid credentials\n"); |
| 775 | printk(KERN_ERR "CRED: At %s:%u\n", file, line); |
| 776 | dump_invalid_creds(cred, "Specified", current); |
| 777 | BUG(); |
| 778 | } |
| 779 | EXPORT_SYMBOL(__invalid_creds); |
| 780 | |
| 781 | /* |
| 782 | * check the credentials on a process |
| 783 | */ |
| 784 | void __validate_process_creds(struct task_struct *tsk, |
| 785 | const char *file, unsigned line) |
| 786 | { |
| 787 | if (tsk->cred == tsk->real_cred) { |
| 788 | if (unlikely(read_cred_subscribers(tsk->cred) < 2 || |
| 789 | creds_are_invalid(tsk->cred))) |
| 790 | goto invalid_creds; |
| 791 | } else { |
| 792 | if (unlikely(read_cred_subscribers(tsk->real_cred) < 1 || |
| 793 | read_cred_subscribers(tsk->cred) < 1 || |
| 794 | creds_are_invalid(tsk->real_cred) || |
| 795 | creds_are_invalid(tsk->cred))) |
| 796 | goto invalid_creds; |
| 797 | } |
| 798 | return; |
| 799 | |
| 800 | invalid_creds: |
| 801 | printk(KERN_ERR "CRED: Invalid process credentials\n"); |
| 802 | printk(KERN_ERR "CRED: At %s:%u\n", file, line); |
| 803 | |
| 804 | dump_invalid_creds(tsk->real_cred, "Real", tsk); |
| 805 | if (tsk->cred != tsk->real_cred) |
| 806 | dump_invalid_creds(tsk->cred, "Effective", tsk); |
| 807 | else |
| 808 | printk(KERN_ERR "CRED: Effective creds == Real creds\n"); |
| 809 | BUG(); |
| 810 | } |
| 811 | EXPORT_SYMBOL(__validate_process_creds); |
| 812 | |
| 813 | /* |
| 814 | * check creds for do_exit() |
| 815 | */ |
| 816 | void validate_creds_for_do_exit(struct task_struct *tsk) |
| 817 | { |
| 818 | kdebug("validate_creds_for_do_exit(%p,%p{%d,%d})", |
| 819 | tsk->real_cred, tsk->cred, |
| 820 | atomic_read(&tsk->cred->usage), |
| 821 | read_cred_subscribers(tsk->cred)); |
| 822 | |
| 823 | __validate_process_creds(tsk, __FILE__, __LINE__); |
| 824 | } |
| 825 | |
| 826 | #endif /* CONFIG_DEBUG_CREDENTIALS */ |