1 /* Request a key from userspace 2 * 3 * Copyright (C) 2004-2007 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 License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 * 11 * See Documentation/keys-request-key.txt 12 */ 13 14 #include <linux/module.h> 15 #include <linux/sched.h> 16 #include <linux/kmod.h> 17 #include <linux/err.h> 18 #include <linux/keyctl.h> 19 #include <linux/slab.h> 20 #include "internal.h" 21 22 /* 23 * wait_on_bit() sleep function for uninterruptible waiting 24 */ 25 static int key_wait_bit(void *flags) 26 { 27 schedule(); 28 return 0; 29 } 30 31 /* 32 * wait_on_bit() sleep function for interruptible waiting 33 */ 34 static int key_wait_bit_intr(void *flags) 35 { 36 schedule(); 37 return signal_pending(current) ? -ERESTARTSYS : 0; 38 } 39 40 /* 41 * call to complete the construction of a key 42 */ 43 void complete_request_key(struct key_construction *cons, int error) 44 { 45 kenter("{%d,%d},%d", cons->key->serial, cons->authkey->serial, error); 46 47 if (error < 0) 48 key_negate_and_link(cons->key, key_negative_timeout, NULL, 49 cons->authkey); 50 else 51 key_revoke(cons->authkey); 52 53 key_put(cons->key); 54 key_put(cons->authkey); 55 kfree(cons); 56 } 57 EXPORT_SYMBOL(complete_request_key); 58 59 /* 60 * request userspace finish the construction of a key 61 * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>" 62 */ 63 static int call_sbin_request_key(struct key_construction *cons, 64 const char *op, 65 void *aux) 66 { 67 struct task_struct *tsk = current; 68 key_serial_t prkey, sskey; 69 struct key *key = cons->key, *authkey = cons->authkey, *keyring; 70 char *argv[9], *envp[3], uid_str[12], gid_str[12]; 71 char key_str[12], keyring_str[3][12]; 72 char desc[20]; 73 int ret, i; 74 75 kenter("{%d},{%d},%s", key->serial, authkey->serial, op); 76 77 /* allocate a new session keyring */ 78 sprintf(desc, "_req.%u", key->serial); 79 80 keyring = keyring_alloc(desc, current->fsuid, current->fsgid, current, 81 KEY_ALLOC_QUOTA_OVERRUN, NULL); 82 if (IS_ERR(keyring)) { 83 ret = PTR_ERR(keyring); 84 goto error_alloc; 85 } 86 87 /* attach the auth key to the session keyring */ 88 ret = __key_link(keyring, authkey); 89 if (ret < 0) 90 goto error_link; 91 92 /* record the UID and GID */ 93 sprintf(uid_str, "%d", current->fsuid); 94 sprintf(gid_str, "%d", current->fsgid); 95 96 /* we say which key is under construction */ 97 sprintf(key_str, "%d", key->serial); 98 99 /* we specify the process's default keyrings */ 100 sprintf(keyring_str[0], "%d", 101 tsk->thread_keyring ? tsk->thread_keyring->serial : 0); 102 103 prkey = 0; 104 if (tsk->signal->process_keyring) 105 prkey = tsk->signal->process_keyring->serial; 106 107 sprintf(keyring_str[1], "%d", prkey); 108 109 if (tsk->signal->session_keyring) { 110 rcu_read_lock(); 111 sskey = rcu_dereference(tsk->signal->session_keyring)->serial; 112 rcu_read_unlock(); 113 } else { 114 sskey = tsk->user->session_keyring->serial; 115 } 116 117 sprintf(keyring_str[2], "%d", sskey); 118 119 /* set up a minimal environment */ 120 i = 0; 121 envp[i++] = "HOME=/"; 122 envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; 123 envp[i] = NULL; 124 125 /* set up the argument list */ 126 i = 0; 127 argv[i++] = "/sbin/request-key"; 128 argv[i++] = (char *) op; 129 argv[i++] = key_str; 130 argv[i++] = uid_str; 131 argv[i++] = gid_str; 132 argv[i++] = keyring_str[0]; 133 argv[i++] = keyring_str[1]; 134 argv[i++] = keyring_str[2]; 135 argv[i] = NULL; 136 137 /* do it */ 138 ret = call_usermodehelper_keys(argv[0], argv, envp, keyring, 139 UMH_WAIT_PROC); 140 kdebug("usermode -> 0x%x", ret); 141 if (ret >= 0) { 142 /* ret is the exit/wait code */ 143 if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags) || 144 key_validate(key) < 0) 145 ret = -ENOKEY; 146 else 147 /* ignore any errors from userspace if the key was 148 * instantiated */ 149 ret = 0; 150 } 151 152 error_link: 153 key_put(keyring); 154 155 error_alloc: 156 kleave(" = %d", ret); 157 complete_request_key(cons, ret); 158 return ret; 159 } 160 161 /* 162 * call out to userspace for key construction 163 * - we ignore program failure and go on key status instead 164 */ 165 static int construct_key(struct key *key, const void *callout_info, 166 size_t callout_len, void *aux) 167 { 168 struct key_construction *cons; 169 request_key_actor_t actor; 170 struct key *authkey; 171 int ret; 172 173 kenter("%d,%p,%zu,%p", key->serial, callout_info, callout_len, aux); 174 175 cons = kmalloc(sizeof(*cons), GFP_KERNEL); 176 if (!cons) 177 return -ENOMEM; 178 179 /* allocate an authorisation key */ 180 authkey = request_key_auth_new(key, callout_info, callout_len); 181 if (IS_ERR(authkey)) { 182 kfree(cons); 183 ret = PTR_ERR(authkey); 184 authkey = NULL; 185 } else { 186 cons->authkey = key_get(authkey); 187 cons->key = key_get(key); 188 189 /* make the call */ 190 actor = call_sbin_request_key; 191 if (key->type->request_key) 192 actor = key->type->request_key; 193 194 ret = actor(cons, "create", aux); 195 196 /* check that the actor called complete_request_key() prior to 197 * returning an error */ 198 WARN_ON(ret < 0 && 199 !test_bit(KEY_FLAG_REVOKED, &authkey->flags)); 200 key_put(authkey); 201 } 202 203 kleave(" = %d", ret); 204 return ret; 205 } 206 207 /* 208 * link a key to the appropriate destination keyring 209 * - the caller must hold a write lock on the destination keyring 210 */ 211 static void construct_key_make_link(struct key *key, struct key *dest_keyring) 212 { 213 struct task_struct *tsk = current; 214 struct key *drop = NULL; 215 216 kenter("{%d},%p", key->serial, dest_keyring); 217 218 /* find the appropriate keyring */ 219 if (!dest_keyring) { 220 switch (tsk->jit_keyring) { 221 case KEY_REQKEY_DEFL_DEFAULT: 222 case KEY_REQKEY_DEFL_THREAD_KEYRING: 223 dest_keyring = tsk->thread_keyring; 224 if (dest_keyring) 225 break; 226 227 case KEY_REQKEY_DEFL_PROCESS_KEYRING: 228 dest_keyring = tsk->signal->process_keyring; 229 if (dest_keyring) 230 break; 231 232 case KEY_REQKEY_DEFL_SESSION_KEYRING: 233 rcu_read_lock(); 234 dest_keyring = key_get( 235 rcu_dereference(tsk->signal->session_keyring)); 236 rcu_read_unlock(); 237 drop = dest_keyring; 238 239 if (dest_keyring) 240 break; 241 242 case KEY_REQKEY_DEFL_USER_SESSION_KEYRING: 243 dest_keyring = tsk->user->session_keyring; 244 break; 245 246 case KEY_REQKEY_DEFL_USER_KEYRING: 247 dest_keyring = tsk->user->uid_keyring; 248 break; 249 250 case KEY_REQKEY_DEFL_GROUP_KEYRING: 251 default: 252 BUG(); 253 } 254 } 255 256 /* and attach the key to it */ 257 __key_link(dest_keyring, key); 258 key_put(drop); 259 kleave(""); 260 } 261 262 /* 263 * allocate a new key in under-construction state and attempt to link it in to 264 * the requested place 265 * - may return a key that's already under construction instead 266 */ 267 static int construct_alloc_key(struct key_type *type, 268 const char *description, 269 struct key *dest_keyring, 270 unsigned long flags, 271 struct key_user *user, 272 struct key **_key) 273 { 274 struct key *key; 275 key_ref_t key_ref; 276 277 kenter("%s,%s,,,", type->name, description); 278 279 mutex_lock(&user->cons_lock); 280 281 key = key_alloc(type, description, 282 current->fsuid, current->fsgid, current, KEY_POS_ALL, 283 flags); 284 if (IS_ERR(key)) 285 goto alloc_failed; 286 287 set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags); 288 289 if (dest_keyring) 290 down_write(&dest_keyring->sem); 291 292 /* attach the key to the destination keyring under lock, but we do need 293 * to do another check just in case someone beat us to it whilst we 294 * waited for locks */ 295 mutex_lock(&key_construction_mutex); 296 297 key_ref = search_process_keyrings(type, description, type->match, 298 current); 299 if (!IS_ERR(key_ref)) 300 goto key_already_present; 301 302 if (dest_keyring) 303 construct_key_make_link(key, dest_keyring); 304 305 mutex_unlock(&key_construction_mutex); 306 if (dest_keyring) 307 up_write(&dest_keyring->sem); 308 mutex_unlock(&user->cons_lock); 309 *_key = key; 310 kleave(" = 0 [%d]", key_serial(key)); 311 return 0; 312 313 key_already_present: 314 mutex_unlock(&key_construction_mutex); 315 if (dest_keyring) 316 up_write(&dest_keyring->sem); 317 mutex_unlock(&user->cons_lock); 318 key_put(key); 319 *_key = key = key_ref_to_ptr(key_ref); 320 kleave(" = -EINPROGRESS [%d]", key_serial(key)); 321 return -EINPROGRESS; 322 323 alloc_failed: 324 mutex_unlock(&user->cons_lock); 325 *_key = NULL; 326 kleave(" = %ld", PTR_ERR(key)); 327 return PTR_ERR(key); 328 } 329 330 /* 331 * commence key construction 332 */ 333 static struct key *construct_key_and_link(struct key_type *type, 334 const char *description, 335 const char *callout_info, 336 size_t callout_len, 337 void *aux, 338 struct key *dest_keyring, 339 unsigned long flags) 340 { 341 struct key_user *user; 342 struct key *key; 343 int ret; 344 345 user = key_user_lookup(current->fsuid); 346 if (!user) 347 return ERR_PTR(-ENOMEM); 348 349 ret = construct_alloc_key(type, description, dest_keyring, flags, user, 350 &key); 351 key_user_put(user); 352 353 if (ret == 0) { 354 ret = construct_key(key, callout_info, callout_len, aux); 355 if (ret < 0) 356 goto construction_failed; 357 } 358 359 return key; 360 361 construction_failed: 362 key_negate_and_link(key, key_negative_timeout, NULL, NULL); 363 key_put(key); 364 return ERR_PTR(ret); 365 } 366 367 /* 368 * request a key 369 * - search the process's keyrings 370 * - check the list of keys being created or updated 371 * - call out to userspace for a key if supplementary info was provided 372 * - cache the key in an appropriate keyring 373 */ 374 struct key *request_key_and_link(struct key_type *type, 375 const char *description, 376 const void *callout_info, 377 size_t callout_len, 378 void *aux, 379 struct key *dest_keyring, 380 unsigned long flags) 381 { 382 struct key *key; 383 key_ref_t key_ref; 384 385 kenter("%s,%s,%p,%zu,%p,%p,%lx", 386 type->name, description, callout_info, callout_len, aux, 387 dest_keyring, flags); 388 389 /* search all the process keyrings for a key */ 390 key_ref = search_process_keyrings(type, description, type->match, 391 current); 392 393 if (!IS_ERR(key_ref)) { 394 key = key_ref_to_ptr(key_ref); 395 } else if (PTR_ERR(key_ref) != -EAGAIN) { 396 key = ERR_CAST(key_ref); 397 } else { 398 /* the search failed, but the keyrings were searchable, so we 399 * should consult userspace if we can */ 400 key = ERR_PTR(-ENOKEY); 401 if (!callout_info) 402 goto error; 403 404 key = construct_key_and_link(type, description, callout_info, 405 callout_len, aux, dest_keyring, 406 flags); 407 } 408 409 error: 410 kleave(" = %p", key); 411 return key; 412 } 413 414 /* 415 * wait for construction of a key to complete 416 */ 417 int wait_for_key_construction(struct key *key, bool intr) 418 { 419 int ret; 420 421 ret = wait_on_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT, 422 intr ? key_wait_bit_intr : key_wait_bit, 423 intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE); 424 if (ret < 0) 425 return ret; 426 return key_validate(key); 427 } 428 EXPORT_SYMBOL(wait_for_key_construction); 429 430 /* 431 * request a key 432 * - search the process's keyrings 433 * - check the list of keys being created or updated 434 * - call out to userspace for a key if supplementary info was provided 435 * - waits uninterruptible for creation to complete 436 */ 437 struct key *request_key(struct key_type *type, 438 const char *description, 439 const char *callout_info) 440 { 441 struct key *key; 442 size_t callout_len = 0; 443 int ret; 444 445 if (callout_info) 446 callout_len = strlen(callout_info); 447 key = request_key_and_link(type, description, callout_info, callout_len, 448 NULL, NULL, KEY_ALLOC_IN_QUOTA); 449 if (!IS_ERR(key)) { 450 ret = wait_for_key_construction(key, false); 451 if (ret < 0) { 452 key_put(key); 453 return ERR_PTR(ret); 454 } 455 } 456 return key; 457 } 458 EXPORT_SYMBOL(request_key); 459 460 /* 461 * request a key with auxiliary data for the upcaller 462 * - search the process's keyrings 463 * - check the list of keys being created or updated 464 * - call out to userspace for a key if supplementary info was provided 465 * - waits uninterruptible for creation to complete 466 */ 467 struct key *request_key_with_auxdata(struct key_type *type, 468 const char *description, 469 const void *callout_info, 470 size_t callout_len, 471 void *aux) 472 { 473 struct key *key; 474 int ret; 475 476 key = request_key_and_link(type, description, callout_info, callout_len, 477 aux, NULL, KEY_ALLOC_IN_QUOTA); 478 if (!IS_ERR(key)) { 479 ret = wait_for_key_construction(key, false); 480 if (ret < 0) { 481 key_put(key); 482 return ERR_PTR(ret); 483 } 484 } 485 return key; 486 } 487 EXPORT_SYMBOL(request_key_with_auxdata); 488 489 /* 490 * request a key (allow async construction) 491 * - search the process's keyrings 492 * - check the list of keys being created or updated 493 * - call out to userspace for a key if supplementary info was provided 494 */ 495 struct key *request_key_async(struct key_type *type, 496 const char *description, 497 const void *callout_info, 498 size_t callout_len) 499 { 500 return request_key_and_link(type, description, callout_info, 501 callout_len, NULL, NULL, 502 KEY_ALLOC_IN_QUOTA); 503 } 504 EXPORT_SYMBOL(request_key_async); 505 506 /* 507 * request a key with auxiliary data for the upcaller (allow async construction) 508 * - search the process's keyrings 509 * - check the list of keys being created or updated 510 * - call out to userspace for a key if supplementary info was provided 511 */ 512 struct key *request_key_async_with_auxdata(struct key_type *type, 513 const char *description, 514 const void *callout_info, 515 size_t callout_len, 516 void *aux) 517 { 518 return request_key_and_link(type, description, callout_info, 519 callout_len, aux, NULL, KEY_ALLOC_IN_QUOTA); 520 } 521 EXPORT_SYMBOL(request_key_async_with_auxdata); 522