1 /* 2 * kernel userspace event delivery 3 * 4 * Copyright (C) 2004 Red Hat, Inc. All rights reserved. 5 * Copyright (C) 2004 Novell, Inc. All rights reserved. 6 * Copyright (C) 2004 IBM, Inc. All rights reserved. 7 * 8 * Licensed under the GNU GPL v2. 9 * 10 * Authors: 11 * Robert Love <rml@novell.com> 12 * Kay Sievers <kay.sievers@vrfy.org> 13 * Arjan van de Ven <arjanv@redhat.com> 14 * Greg Kroah-Hartman <greg@kroah.com> 15 */ 16 17 #include <linux/spinlock.h> 18 #include <linux/string.h> 19 #include <linux/kobject.h> 20 #include <linux/export.h> 21 #include <linux/kmod.h> 22 #include <linux/slab.h> 23 #include <linux/socket.h> 24 #include <linux/skbuff.h> 25 #include <linux/netlink.h> 26 #include <linux/uuid.h> 27 #include <linux/ctype.h> 28 #include <net/sock.h> 29 #include <net/net_namespace.h> 30 31 32 u64 uevent_seqnum; 33 #ifdef CONFIG_UEVENT_HELPER 34 char uevent_helper[UEVENT_HELPER_PATH_LEN] = CONFIG_UEVENT_HELPER_PATH; 35 #endif 36 #ifdef CONFIG_NET 37 struct uevent_sock { 38 struct list_head list; 39 struct sock *sk; 40 }; 41 static LIST_HEAD(uevent_sock_list); 42 #endif 43 44 /* This lock protects uevent_seqnum and uevent_sock_list */ 45 static DEFINE_MUTEX(uevent_sock_mutex); 46 47 /* the strings here must match the enum in include/linux/kobject.h */ 48 static const char *kobject_actions[] = { 49 [KOBJ_ADD] = "add", 50 [KOBJ_REMOVE] = "remove", 51 [KOBJ_CHANGE] = "change", 52 [KOBJ_MOVE] = "move", 53 [KOBJ_ONLINE] = "online", 54 [KOBJ_OFFLINE] = "offline", 55 [KOBJ_BIND] = "bind", 56 [KOBJ_UNBIND] = "unbind", 57 }; 58 59 static int kobject_action_type(const char *buf, size_t count, 60 enum kobject_action *type, 61 const char **args) 62 { 63 enum kobject_action action; 64 size_t count_first; 65 const char *args_start; 66 int ret = -EINVAL; 67 68 if (count && (buf[count-1] == '\n' || buf[count-1] == '\0')) 69 count--; 70 71 if (!count) 72 goto out; 73 74 args_start = strnchr(buf, count, ' '); 75 if (args_start) { 76 count_first = args_start - buf; 77 args_start = args_start + 1; 78 } else 79 count_first = count; 80 81 for (action = 0; action < ARRAY_SIZE(kobject_actions); action++) { 82 if (strncmp(kobject_actions[action], buf, count_first) != 0) 83 continue; 84 if (kobject_actions[action][count_first] != '\0') 85 continue; 86 if (args) 87 *args = args_start; 88 *type = action; 89 ret = 0; 90 break; 91 } 92 out: 93 return ret; 94 } 95 96 static const char *action_arg_word_end(const char *buf, const char *buf_end, 97 char delim) 98 { 99 const char *next = buf; 100 101 while (next <= buf_end && *next != delim) 102 if (!isalnum(*next++)) 103 return NULL; 104 105 if (next == buf) 106 return NULL; 107 108 return next; 109 } 110 111 static int kobject_action_args(const char *buf, size_t count, 112 struct kobj_uevent_env **ret_env) 113 { 114 struct kobj_uevent_env *env = NULL; 115 const char *next, *buf_end, *key; 116 int key_len; 117 int r = -EINVAL; 118 119 if (count && (buf[count - 1] == '\n' || buf[count - 1] == '\0')) 120 count--; 121 122 if (!count) 123 return -EINVAL; 124 125 env = kzalloc(sizeof(*env), GFP_KERNEL); 126 if (!env) 127 return -ENOMEM; 128 129 /* first arg is UUID */ 130 if (count < UUID_STRING_LEN || !uuid_is_valid(buf) || 131 add_uevent_var(env, "SYNTH_UUID=%.*s", UUID_STRING_LEN, buf)) 132 goto out; 133 134 /* 135 * the rest are custom environment variables in KEY=VALUE 136 * format with ' ' delimiter between each KEY=VALUE pair 137 */ 138 next = buf + UUID_STRING_LEN; 139 buf_end = buf + count - 1; 140 141 while (next <= buf_end) { 142 if (*next != ' ') 143 goto out; 144 145 /* skip the ' ', key must follow */ 146 key = ++next; 147 if (key > buf_end) 148 goto out; 149 150 buf = next; 151 next = action_arg_word_end(buf, buf_end, '='); 152 if (!next || next > buf_end || *next != '=') 153 goto out; 154 key_len = next - buf; 155 156 /* skip the '=', value must follow */ 157 if (++next > buf_end) 158 goto out; 159 160 buf = next; 161 next = action_arg_word_end(buf, buf_end, ' '); 162 if (!next) 163 goto out; 164 165 if (add_uevent_var(env, "SYNTH_ARG_%.*s=%.*s", 166 key_len, key, (int) (next - buf), buf)) 167 goto out; 168 } 169 170 r = 0; 171 out: 172 if (r) 173 kfree(env); 174 else 175 *ret_env = env; 176 return r; 177 } 178 179 /** 180 * kobject_synth_uevent - send synthetic uevent with arguments 181 * 182 * @kobj: struct kobject for which synthetic uevent is to be generated 183 * @buf: buffer containing action type and action args, newline is ignored 184 * @count: length of buffer 185 * 186 * Returns 0 if kobject_synthetic_uevent() is completed with success or the 187 * corresponding error when it fails. 188 */ 189 int kobject_synth_uevent(struct kobject *kobj, const char *buf, size_t count) 190 { 191 char *no_uuid_envp[] = { "SYNTH_UUID=0", NULL }; 192 enum kobject_action action; 193 const char *action_args; 194 struct kobj_uevent_env *env; 195 const char *msg = NULL, *devpath; 196 int r; 197 198 r = kobject_action_type(buf, count, &action, &action_args); 199 if (r) { 200 msg = "unknown uevent action string\n"; 201 goto out; 202 } 203 204 if (!action_args) { 205 r = kobject_uevent_env(kobj, action, no_uuid_envp); 206 goto out; 207 } 208 209 r = kobject_action_args(action_args, 210 count - (action_args - buf), &env); 211 if (r == -EINVAL) { 212 msg = "incorrect uevent action arguments\n"; 213 goto out; 214 } 215 216 if (r) 217 goto out; 218 219 r = kobject_uevent_env(kobj, action, env->envp); 220 kfree(env); 221 out: 222 if (r) { 223 devpath = kobject_get_path(kobj, GFP_KERNEL); 224 printk(KERN_WARNING "synth uevent: %s: %s", 225 devpath ?: "unknown device", 226 msg ?: "failed to send uevent"); 227 kfree(devpath); 228 } 229 return r; 230 } 231 232 #ifdef CONFIG_NET 233 static int kobj_bcast_filter(struct sock *dsk, struct sk_buff *skb, void *data) 234 { 235 struct kobject *kobj = data, *ksobj; 236 const struct kobj_ns_type_operations *ops; 237 238 ops = kobj_ns_ops(kobj); 239 if (!ops && kobj->kset) { 240 ksobj = &kobj->kset->kobj; 241 if (ksobj->parent != NULL) 242 ops = kobj_ns_ops(ksobj->parent); 243 } 244 245 if (ops && ops->netlink_ns && kobj->ktype->namespace) { 246 const void *sock_ns, *ns; 247 ns = kobj->ktype->namespace(kobj); 248 sock_ns = ops->netlink_ns(dsk); 249 return sock_ns != ns; 250 } 251 252 return 0; 253 } 254 #endif 255 256 #ifdef CONFIG_UEVENT_HELPER 257 static int kobj_usermode_filter(struct kobject *kobj) 258 { 259 const struct kobj_ns_type_operations *ops; 260 261 ops = kobj_ns_ops(kobj); 262 if (ops) { 263 const void *init_ns, *ns; 264 ns = kobj->ktype->namespace(kobj); 265 init_ns = ops->initial_ns(); 266 return ns != init_ns; 267 } 268 269 return 0; 270 } 271 272 static int init_uevent_argv(struct kobj_uevent_env *env, const char *subsystem) 273 { 274 int len; 275 276 len = strlcpy(&env->buf[env->buflen], subsystem, 277 sizeof(env->buf) - env->buflen); 278 if (len >= (sizeof(env->buf) - env->buflen)) { 279 WARN(1, KERN_ERR "init_uevent_argv: buffer size too small\n"); 280 return -ENOMEM; 281 } 282 283 env->argv[0] = uevent_helper; 284 env->argv[1] = &env->buf[env->buflen]; 285 env->argv[2] = NULL; 286 287 env->buflen += len + 1; 288 return 0; 289 } 290 291 static void cleanup_uevent_env(struct subprocess_info *info) 292 { 293 kfree(info->data); 294 } 295 #endif 296 297 static void zap_modalias_env(struct kobj_uevent_env *env) 298 { 299 static const char modalias_prefix[] = "MODALIAS="; 300 int i; 301 302 for (i = 0; i < env->envp_idx;) { 303 if (strncmp(env->envp[i], modalias_prefix, 304 sizeof(modalias_prefix) - 1)) { 305 i++; 306 continue; 307 } 308 309 if (i != env->envp_idx - 1) 310 memmove(&env->envp[i], &env->envp[i + 1], 311 sizeof(env->envp[i]) * env->envp_idx - 1); 312 313 env->envp_idx--; 314 } 315 } 316 317 /** 318 * kobject_uevent_env - send an uevent with environmental data 319 * 320 * @kobj: struct kobject that the action is happening to 321 * @action: action that is happening 322 * @envp_ext: pointer to environmental data 323 * 324 * Returns 0 if kobject_uevent_env() is completed with success or the 325 * corresponding error when it fails. 326 */ 327 int kobject_uevent_env(struct kobject *kobj, enum kobject_action action, 328 char *envp_ext[]) 329 { 330 struct kobj_uevent_env *env; 331 const char *action_string = kobject_actions[action]; 332 const char *devpath = NULL; 333 const char *subsystem; 334 struct kobject *top_kobj; 335 struct kset *kset; 336 const struct kset_uevent_ops *uevent_ops; 337 int i = 0; 338 int retval = 0; 339 #ifdef CONFIG_NET 340 struct uevent_sock *ue_sk; 341 #endif 342 343 pr_debug("kobject: '%s' (%p): %s\n", 344 kobject_name(kobj), kobj, __func__); 345 346 /* search the kset we belong to */ 347 top_kobj = kobj; 348 while (!top_kobj->kset && top_kobj->parent) 349 top_kobj = top_kobj->parent; 350 351 if (!top_kobj->kset) { 352 pr_debug("kobject: '%s' (%p): %s: attempted to send uevent " 353 "without kset!\n", kobject_name(kobj), kobj, 354 __func__); 355 return -EINVAL; 356 } 357 358 kset = top_kobj->kset; 359 uevent_ops = kset->uevent_ops; 360 361 /* skip the event, if uevent_suppress is set*/ 362 if (kobj->uevent_suppress) { 363 pr_debug("kobject: '%s' (%p): %s: uevent_suppress " 364 "caused the event to drop!\n", 365 kobject_name(kobj), kobj, __func__); 366 return 0; 367 } 368 /* skip the event, if the filter returns zero. */ 369 if (uevent_ops && uevent_ops->filter) 370 if (!uevent_ops->filter(kset, kobj)) { 371 pr_debug("kobject: '%s' (%p): %s: filter function " 372 "caused the event to drop!\n", 373 kobject_name(kobj), kobj, __func__); 374 return 0; 375 } 376 377 /* originating subsystem */ 378 if (uevent_ops && uevent_ops->name) 379 subsystem = uevent_ops->name(kset, kobj); 380 else 381 subsystem = kobject_name(&kset->kobj); 382 if (!subsystem) { 383 pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the " 384 "event to drop!\n", kobject_name(kobj), kobj, 385 __func__); 386 return 0; 387 } 388 389 /* environment buffer */ 390 env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL); 391 if (!env) 392 return -ENOMEM; 393 394 /* complete object path */ 395 devpath = kobject_get_path(kobj, GFP_KERNEL); 396 if (!devpath) { 397 retval = -ENOENT; 398 goto exit; 399 } 400 401 /* default keys */ 402 retval = add_uevent_var(env, "ACTION=%s", action_string); 403 if (retval) 404 goto exit; 405 retval = add_uevent_var(env, "DEVPATH=%s", devpath); 406 if (retval) 407 goto exit; 408 retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem); 409 if (retval) 410 goto exit; 411 412 /* keys passed in from the caller */ 413 if (envp_ext) { 414 for (i = 0; envp_ext[i]; i++) { 415 retval = add_uevent_var(env, "%s", envp_ext[i]); 416 if (retval) 417 goto exit; 418 } 419 } 420 421 /* let the kset specific function add its stuff */ 422 if (uevent_ops && uevent_ops->uevent) { 423 retval = uevent_ops->uevent(kset, kobj, env); 424 if (retval) { 425 pr_debug("kobject: '%s' (%p): %s: uevent() returned " 426 "%d\n", kobject_name(kobj), kobj, 427 __func__, retval); 428 goto exit; 429 } 430 } 431 432 switch (action) { 433 case KOBJ_ADD: 434 /* 435 * Mark "add" event so we can make sure we deliver "remove" 436 * event to userspace during automatic cleanup. If 437 * the object did send an "add" event, "remove" will 438 * automatically generated by the core, if not already done 439 * by the caller. 440 */ 441 kobj->state_add_uevent_sent = 1; 442 break; 443 444 case KOBJ_REMOVE: 445 kobj->state_remove_uevent_sent = 1; 446 break; 447 448 case KOBJ_UNBIND: 449 zap_modalias_env(env); 450 break; 451 452 default: 453 break; 454 } 455 456 mutex_lock(&uevent_sock_mutex); 457 /* we will send an event, so request a new sequence number */ 458 retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)++uevent_seqnum); 459 if (retval) { 460 mutex_unlock(&uevent_sock_mutex); 461 goto exit; 462 } 463 464 #if defined(CONFIG_NET) 465 /* send netlink message */ 466 list_for_each_entry(ue_sk, &uevent_sock_list, list) { 467 struct sock *uevent_sock = ue_sk->sk; 468 struct sk_buff *skb; 469 size_t len; 470 471 if (!netlink_has_listeners(uevent_sock, 1)) 472 continue; 473 474 /* allocate message with the maximum possible size */ 475 len = strlen(action_string) + strlen(devpath) + 2; 476 skb = alloc_skb(len + env->buflen, GFP_KERNEL); 477 if (skb) { 478 char *scratch; 479 480 /* add header */ 481 scratch = skb_put(skb, len); 482 sprintf(scratch, "%s@%s", action_string, devpath); 483 484 /* copy keys to our continuous event payload buffer */ 485 for (i = 0; i < env->envp_idx; i++) { 486 len = strlen(env->envp[i]) + 1; 487 scratch = skb_put(skb, len); 488 strcpy(scratch, env->envp[i]); 489 } 490 491 NETLINK_CB(skb).dst_group = 1; 492 retval = netlink_broadcast_filtered(uevent_sock, skb, 493 0, 1, GFP_KERNEL, 494 kobj_bcast_filter, 495 kobj); 496 /* ENOBUFS should be handled in userspace */ 497 if (retval == -ENOBUFS || retval == -ESRCH) 498 retval = 0; 499 } else 500 retval = -ENOMEM; 501 } 502 #endif 503 mutex_unlock(&uevent_sock_mutex); 504 505 #ifdef CONFIG_UEVENT_HELPER 506 /* call uevent_helper, usually only enabled during early boot */ 507 if (uevent_helper[0] && !kobj_usermode_filter(kobj)) { 508 struct subprocess_info *info; 509 510 retval = add_uevent_var(env, "HOME=/"); 511 if (retval) 512 goto exit; 513 retval = add_uevent_var(env, 514 "PATH=/sbin:/bin:/usr/sbin:/usr/bin"); 515 if (retval) 516 goto exit; 517 retval = init_uevent_argv(env, subsystem); 518 if (retval) 519 goto exit; 520 521 retval = -ENOMEM; 522 info = call_usermodehelper_setup(env->argv[0], env->argv, 523 env->envp, GFP_KERNEL, 524 NULL, cleanup_uevent_env, env); 525 if (info) { 526 retval = call_usermodehelper_exec(info, UMH_NO_WAIT); 527 env = NULL; /* freed by cleanup_uevent_env */ 528 } 529 } 530 #endif 531 532 exit: 533 kfree(devpath); 534 kfree(env); 535 return retval; 536 } 537 EXPORT_SYMBOL_GPL(kobject_uevent_env); 538 539 /** 540 * kobject_uevent - notify userspace by sending an uevent 541 * 542 * @kobj: struct kobject that the action is happening to 543 * @action: action that is happening 544 * 545 * Returns 0 if kobject_uevent() is completed with success or the 546 * corresponding error when it fails. 547 */ 548 int kobject_uevent(struct kobject *kobj, enum kobject_action action) 549 { 550 return kobject_uevent_env(kobj, action, NULL); 551 } 552 EXPORT_SYMBOL_GPL(kobject_uevent); 553 554 /** 555 * add_uevent_var - add key value string to the environment buffer 556 * @env: environment buffer structure 557 * @format: printf format for the key=value pair 558 * 559 * Returns 0 if environment variable was added successfully or -ENOMEM 560 * if no space was available. 561 */ 562 int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...) 563 { 564 va_list args; 565 int len; 566 567 if (env->envp_idx >= ARRAY_SIZE(env->envp)) { 568 WARN(1, KERN_ERR "add_uevent_var: too many keys\n"); 569 return -ENOMEM; 570 } 571 572 va_start(args, format); 573 len = vsnprintf(&env->buf[env->buflen], 574 sizeof(env->buf) - env->buflen, 575 format, args); 576 va_end(args); 577 578 if (len >= (sizeof(env->buf) - env->buflen)) { 579 WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n"); 580 return -ENOMEM; 581 } 582 583 env->envp[env->envp_idx++] = &env->buf[env->buflen]; 584 env->buflen += len + 1; 585 return 0; 586 } 587 EXPORT_SYMBOL_GPL(add_uevent_var); 588 589 #if defined(CONFIG_NET) 590 static int uevent_net_init(struct net *net) 591 { 592 struct uevent_sock *ue_sk; 593 struct netlink_kernel_cfg cfg = { 594 .groups = 1, 595 .flags = NL_CFG_F_NONROOT_RECV, 596 }; 597 598 ue_sk = kzalloc(sizeof(*ue_sk), GFP_KERNEL); 599 if (!ue_sk) 600 return -ENOMEM; 601 602 ue_sk->sk = netlink_kernel_create(net, NETLINK_KOBJECT_UEVENT, &cfg); 603 if (!ue_sk->sk) { 604 printk(KERN_ERR 605 "kobject_uevent: unable to create netlink socket!\n"); 606 kfree(ue_sk); 607 return -ENODEV; 608 } 609 mutex_lock(&uevent_sock_mutex); 610 list_add_tail(&ue_sk->list, &uevent_sock_list); 611 mutex_unlock(&uevent_sock_mutex); 612 return 0; 613 } 614 615 static void uevent_net_exit(struct net *net) 616 { 617 struct uevent_sock *ue_sk; 618 619 mutex_lock(&uevent_sock_mutex); 620 list_for_each_entry(ue_sk, &uevent_sock_list, list) { 621 if (sock_net(ue_sk->sk) == net) 622 goto found; 623 } 624 mutex_unlock(&uevent_sock_mutex); 625 return; 626 627 found: 628 list_del(&ue_sk->list); 629 mutex_unlock(&uevent_sock_mutex); 630 631 netlink_kernel_release(ue_sk->sk); 632 kfree(ue_sk); 633 } 634 635 static struct pernet_operations uevent_net_ops = { 636 .init = uevent_net_init, 637 .exit = uevent_net_exit, 638 }; 639 640 static int __init kobject_uevent_init(void) 641 { 642 return register_pernet_subsys(&uevent_net_ops); 643 } 644 645 646 postcore_initcall(kobject_uevent_init); 647 #endif 648