| 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/user_namespace.h> |
| 24 | #include <linux/socket.h> |
| 25 | #include <linux/skbuff.h> |
| 26 | #include <linux/netlink.h> |
| 27 | #include <net/sock.h> |
| 28 | #include <net/net_namespace.h> |
| 29 | |
| 30 | |
| 31 | u64 uevent_seqnum; |
| 32 | #ifdef CONFIG_UEVENT_HELPER |
| 33 | char uevent_helper[UEVENT_HELPER_PATH_LEN] = CONFIG_UEVENT_HELPER_PATH; |
| 34 | #endif |
| 35 | #ifdef CONFIG_NET |
| 36 | struct uevent_sock { |
| 37 | struct list_head list; |
| 38 | struct sock *sk; |
| 39 | }; |
| 40 | static LIST_HEAD(uevent_sock_list); |
| 41 | #endif |
| 42 | |
| 43 | /* This lock protects uevent_seqnum and uevent_sock_list */ |
| 44 | static DEFINE_MUTEX(uevent_sock_mutex); |
| 45 | |
| 46 | /* the strings here must match the enum in include/linux/kobject.h */ |
| 47 | static const char *kobject_actions[] = { |
| 48 | [KOBJ_ADD] = "add", |
| 49 | [KOBJ_REMOVE] = "remove", |
| 50 | [KOBJ_CHANGE] = "change", |
| 51 | [KOBJ_MOVE] = "move", |
| 52 | [KOBJ_ONLINE] = "online", |
| 53 | [KOBJ_OFFLINE] = "offline", |
| 54 | }; |
| 55 | |
| 56 | /** |
| 57 | * kobject_action_type - translate action string to numeric type |
| 58 | * |
| 59 | * @buf: buffer containing the action string, newline is ignored |
| 60 | * @len: length of buffer |
| 61 | * @type: pointer to the location to store the action type |
| 62 | * |
| 63 | * Returns 0 if the action string was recognized. |
| 64 | */ |
| 65 | int kobject_action_type(const char *buf, size_t count, |
| 66 | enum kobject_action *type) |
| 67 | { |
| 68 | enum kobject_action action; |
| 69 | int ret = -EINVAL; |
| 70 | |
| 71 | if (count && (buf[count-1] == '\n' || buf[count-1] == '\0')) |
| 72 | count--; |
| 73 | |
| 74 | if (!count) |
| 75 | goto out; |
| 76 | |
| 77 | for (action = 0; action < ARRAY_SIZE(kobject_actions); action++) { |
| 78 | if (strncmp(kobject_actions[action], buf, count) != 0) |
| 79 | continue; |
| 80 | if (kobject_actions[action][count] != '\0') |
| 81 | continue; |
| 82 | *type = action; |
| 83 | ret = 0; |
| 84 | break; |
| 85 | } |
| 86 | out: |
| 87 | return ret; |
| 88 | } |
| 89 | |
| 90 | #ifdef CONFIG_NET |
| 91 | static int kobj_bcast_filter(struct sock *dsk, struct sk_buff *skb, void *data) |
| 92 | { |
| 93 | struct kobject *kobj = data, *ksobj; |
| 94 | const struct kobj_ns_type_operations *ops; |
| 95 | |
| 96 | ops = kobj_ns_ops(kobj); |
| 97 | if (!ops && kobj->kset) { |
| 98 | ksobj = &kobj->kset->kobj; |
| 99 | if (ksobj->parent != NULL) |
| 100 | ops = kobj_ns_ops(ksobj->parent); |
| 101 | } |
| 102 | |
| 103 | if (ops && ops->netlink_ns && kobj->ktype->namespace) { |
| 104 | const void *sock_ns, *ns; |
| 105 | ns = kobj->ktype->namespace(kobj); |
| 106 | sock_ns = ops->netlink_ns(dsk); |
| 107 | return sock_ns != ns; |
| 108 | } |
| 109 | |
| 110 | return 0; |
| 111 | } |
| 112 | #endif |
| 113 | |
| 114 | #ifdef CONFIG_UEVENT_HELPER |
| 115 | static int kobj_usermode_filter(struct kobject *kobj) |
| 116 | { |
| 117 | const struct kobj_ns_type_operations *ops; |
| 118 | |
| 119 | ops = kobj_ns_ops(kobj); |
| 120 | if (ops) { |
| 121 | const void *init_ns, *ns; |
| 122 | ns = kobj->ktype->namespace(kobj); |
| 123 | init_ns = ops->initial_ns(); |
| 124 | return ns != init_ns; |
| 125 | } |
| 126 | |
| 127 | return 0; |
| 128 | } |
| 129 | |
| 130 | static int init_uevent_argv(struct kobj_uevent_env *env, const char *subsystem) |
| 131 | { |
| 132 | int len; |
| 133 | |
| 134 | len = strlcpy(&env->buf[env->buflen], subsystem, |
| 135 | sizeof(env->buf) - env->buflen); |
| 136 | if (len >= (sizeof(env->buf) - env->buflen)) { |
| 137 | WARN(1, KERN_ERR "init_uevent_argv: buffer size too small\n"); |
| 138 | return -ENOMEM; |
| 139 | } |
| 140 | |
| 141 | env->argv[0] = uevent_helper; |
| 142 | env->argv[1] = &env->buf[env->buflen]; |
| 143 | env->argv[2] = NULL; |
| 144 | |
| 145 | env->buflen += len + 1; |
| 146 | return 0; |
| 147 | } |
| 148 | |
| 149 | static void cleanup_uevent_env(struct subprocess_info *info) |
| 150 | { |
| 151 | kfree(info->data); |
| 152 | } |
| 153 | #endif |
| 154 | |
| 155 | /** |
| 156 | * kobject_uevent_env - send an uevent with environmental data |
| 157 | * |
| 158 | * @action: action that is happening |
| 159 | * @kobj: struct kobject that the action is happening to |
| 160 | * @envp_ext: pointer to environmental data |
| 161 | * |
| 162 | * Returns 0 if kobject_uevent_env() is completed with success or the |
| 163 | * corresponding error when it fails. |
| 164 | */ |
| 165 | int kobject_uevent_env(struct kobject *kobj, enum kobject_action action, |
| 166 | char *envp_ext[]) |
| 167 | { |
| 168 | struct kobj_uevent_env *env; |
| 169 | const char *action_string = kobject_actions[action]; |
| 170 | const char *devpath = NULL; |
| 171 | const char *subsystem; |
| 172 | struct kobject *top_kobj; |
| 173 | struct kset *kset; |
| 174 | const struct kset_uevent_ops *uevent_ops; |
| 175 | int i = 0; |
| 176 | int retval = 0; |
| 177 | #ifdef CONFIG_NET |
| 178 | struct uevent_sock *ue_sk; |
| 179 | #endif |
| 180 | |
| 181 | pr_debug("kobject: '%s' (%p): %s\n", |
| 182 | kobject_name(kobj), kobj, __func__); |
| 183 | |
| 184 | /* search the kset we belong to */ |
| 185 | top_kobj = kobj; |
| 186 | while (!top_kobj->kset && top_kobj->parent) |
| 187 | top_kobj = top_kobj->parent; |
| 188 | |
| 189 | if (!top_kobj->kset) { |
| 190 | pr_debug("kobject: '%s' (%p): %s: attempted to send uevent " |
| 191 | "without kset!\n", kobject_name(kobj), kobj, |
| 192 | __func__); |
| 193 | return -EINVAL; |
| 194 | } |
| 195 | |
| 196 | kset = top_kobj->kset; |
| 197 | uevent_ops = kset->uevent_ops; |
| 198 | |
| 199 | /* skip the event, if uevent_suppress is set*/ |
| 200 | if (kobj->uevent_suppress) { |
| 201 | pr_debug("kobject: '%s' (%p): %s: uevent_suppress " |
| 202 | "caused the event to drop!\n", |
| 203 | kobject_name(kobj), kobj, __func__); |
| 204 | return 0; |
| 205 | } |
| 206 | /* skip the event, if the filter returns zero. */ |
| 207 | if (uevent_ops && uevent_ops->filter) |
| 208 | if (!uevent_ops->filter(kset, kobj)) { |
| 209 | pr_debug("kobject: '%s' (%p): %s: filter function " |
| 210 | "caused the event to drop!\n", |
| 211 | kobject_name(kobj), kobj, __func__); |
| 212 | return 0; |
| 213 | } |
| 214 | |
| 215 | /* originating subsystem */ |
| 216 | if (uevent_ops && uevent_ops->name) |
| 217 | subsystem = uevent_ops->name(kset, kobj); |
| 218 | else |
| 219 | subsystem = kobject_name(&kset->kobj); |
| 220 | if (!subsystem) { |
| 221 | pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the " |
| 222 | "event to drop!\n", kobject_name(kobj), kobj, |
| 223 | __func__); |
| 224 | return 0; |
| 225 | } |
| 226 | |
| 227 | /* environment buffer */ |
| 228 | env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL); |
| 229 | if (!env) |
| 230 | return -ENOMEM; |
| 231 | |
| 232 | /* complete object path */ |
| 233 | devpath = kobject_get_path(kobj, GFP_KERNEL); |
| 234 | if (!devpath) { |
| 235 | retval = -ENOENT; |
| 236 | goto exit; |
| 237 | } |
| 238 | |
| 239 | /* default keys */ |
| 240 | retval = add_uevent_var(env, "ACTION=%s", action_string); |
| 241 | if (retval) |
| 242 | goto exit; |
| 243 | retval = add_uevent_var(env, "DEVPATH=%s", devpath); |
| 244 | if (retval) |
| 245 | goto exit; |
| 246 | retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem); |
| 247 | if (retval) |
| 248 | goto exit; |
| 249 | |
| 250 | /* keys passed in from the caller */ |
| 251 | if (envp_ext) { |
| 252 | for (i = 0; envp_ext[i]; i++) { |
| 253 | retval = add_uevent_var(env, "%s", envp_ext[i]); |
| 254 | if (retval) |
| 255 | goto exit; |
| 256 | } |
| 257 | } |
| 258 | |
| 259 | /* let the kset specific function add its stuff */ |
| 260 | if (uevent_ops && uevent_ops->uevent) { |
| 261 | retval = uevent_ops->uevent(kset, kobj, env); |
| 262 | if (retval) { |
| 263 | pr_debug("kobject: '%s' (%p): %s: uevent() returned " |
| 264 | "%d\n", kobject_name(kobj), kobj, |
| 265 | __func__, retval); |
| 266 | goto exit; |
| 267 | } |
| 268 | } |
| 269 | |
| 270 | /* |
| 271 | * Mark "add" and "remove" events in the object to ensure proper |
| 272 | * events to userspace during automatic cleanup. If the object did |
| 273 | * send an "add" event, "remove" will automatically generated by |
| 274 | * the core, if not already done by the caller. |
| 275 | */ |
| 276 | if (action == KOBJ_ADD) |
| 277 | kobj->state_add_uevent_sent = 1; |
| 278 | else if (action == KOBJ_REMOVE) |
| 279 | kobj->state_remove_uevent_sent = 1; |
| 280 | |
| 281 | mutex_lock(&uevent_sock_mutex); |
| 282 | /* we will send an event, so request a new sequence number */ |
| 283 | retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)++uevent_seqnum); |
| 284 | if (retval) { |
| 285 | mutex_unlock(&uevent_sock_mutex); |
| 286 | goto exit; |
| 287 | } |
| 288 | |
| 289 | #if defined(CONFIG_NET) |
| 290 | /* send netlink message */ |
| 291 | list_for_each_entry(ue_sk, &uevent_sock_list, list) { |
| 292 | struct sock *uevent_sock = ue_sk->sk; |
| 293 | struct sk_buff *skb; |
| 294 | size_t len; |
| 295 | |
| 296 | if (!netlink_has_listeners(uevent_sock, 1)) |
| 297 | continue; |
| 298 | |
| 299 | /* allocate message with the maximum possible size */ |
| 300 | len = strlen(action_string) + strlen(devpath) + 2; |
| 301 | skb = alloc_skb(len + env->buflen, GFP_KERNEL); |
| 302 | if (skb) { |
| 303 | char *scratch; |
| 304 | |
| 305 | /* add header */ |
| 306 | scratch = skb_put(skb, len); |
| 307 | sprintf(scratch, "%s@%s", action_string, devpath); |
| 308 | |
| 309 | /* copy keys to our continuous event payload buffer */ |
| 310 | for (i = 0; i < env->envp_idx; i++) { |
| 311 | len = strlen(env->envp[i]) + 1; |
| 312 | scratch = skb_put(skb, len); |
| 313 | strcpy(scratch, env->envp[i]); |
| 314 | } |
| 315 | |
| 316 | NETLINK_CB(skb).dst_group = 1; |
| 317 | retval = netlink_broadcast_filtered(uevent_sock, skb, |
| 318 | 0, 1, GFP_KERNEL, |
| 319 | kobj_bcast_filter, |
| 320 | kobj); |
| 321 | /* ENOBUFS should be handled in userspace */ |
| 322 | if (retval == -ENOBUFS || retval == -ESRCH) |
| 323 | retval = 0; |
| 324 | } else |
| 325 | retval = -ENOMEM; |
| 326 | } |
| 327 | #endif |
| 328 | mutex_unlock(&uevent_sock_mutex); |
| 329 | |
| 330 | #ifdef CONFIG_UEVENT_HELPER |
| 331 | /* call uevent_helper, usually only enabled during early boot */ |
| 332 | if (uevent_helper[0] && !kobj_usermode_filter(kobj)) { |
| 333 | struct subprocess_info *info; |
| 334 | |
| 335 | retval = add_uevent_var(env, "HOME=/"); |
| 336 | if (retval) |
| 337 | goto exit; |
| 338 | retval = add_uevent_var(env, |
| 339 | "PATH=/sbin:/bin:/usr/sbin:/usr/bin"); |
| 340 | if (retval) |
| 341 | goto exit; |
| 342 | retval = init_uevent_argv(env, subsystem); |
| 343 | if (retval) |
| 344 | goto exit; |
| 345 | |
| 346 | retval = -ENOMEM; |
| 347 | info = call_usermodehelper_setup(env->argv[0], env->argv, |
| 348 | env->envp, GFP_KERNEL, |
| 349 | NULL, cleanup_uevent_env, env); |
| 350 | if (info) { |
| 351 | retval = call_usermodehelper_exec(info, UMH_NO_WAIT); |
| 352 | env = NULL; /* freed by cleanup_uevent_env */ |
| 353 | } |
| 354 | } |
| 355 | #endif |
| 356 | |
| 357 | exit: |
| 358 | kfree(devpath); |
| 359 | kfree(env); |
| 360 | return retval; |
| 361 | } |
| 362 | EXPORT_SYMBOL_GPL(kobject_uevent_env); |
| 363 | |
| 364 | /** |
| 365 | * kobject_uevent - notify userspace by sending an uevent |
| 366 | * |
| 367 | * @action: action that is happening |
| 368 | * @kobj: struct kobject that the action is happening to |
| 369 | * |
| 370 | * Returns 0 if kobject_uevent() is completed with success or the |
| 371 | * corresponding error when it fails. |
| 372 | */ |
| 373 | int kobject_uevent(struct kobject *kobj, enum kobject_action action) |
| 374 | { |
| 375 | return kobject_uevent_env(kobj, action, NULL); |
| 376 | } |
| 377 | EXPORT_SYMBOL_GPL(kobject_uevent); |
| 378 | |
| 379 | /** |
| 380 | * add_uevent_var - add key value string to the environment buffer |
| 381 | * @env: environment buffer structure |
| 382 | * @format: printf format for the key=value pair |
| 383 | * |
| 384 | * Returns 0 if environment variable was added successfully or -ENOMEM |
| 385 | * if no space was available. |
| 386 | */ |
| 387 | int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...) |
| 388 | { |
| 389 | va_list args; |
| 390 | int len; |
| 391 | |
| 392 | if (env->envp_idx >= ARRAY_SIZE(env->envp)) { |
| 393 | WARN(1, KERN_ERR "add_uevent_var: too many keys\n"); |
| 394 | return -ENOMEM; |
| 395 | } |
| 396 | |
| 397 | va_start(args, format); |
| 398 | len = vsnprintf(&env->buf[env->buflen], |
| 399 | sizeof(env->buf) - env->buflen, |
| 400 | format, args); |
| 401 | va_end(args); |
| 402 | |
| 403 | if (len >= (sizeof(env->buf) - env->buflen)) { |
| 404 | WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n"); |
| 405 | return -ENOMEM; |
| 406 | } |
| 407 | |
| 408 | env->envp[env->envp_idx++] = &env->buf[env->buflen]; |
| 409 | env->buflen += len + 1; |
| 410 | return 0; |
| 411 | } |
| 412 | EXPORT_SYMBOL_GPL(add_uevent_var); |
| 413 | |
| 414 | #if defined(CONFIG_NET) |
| 415 | static int uevent_net_init(struct net *net) |
| 416 | { |
| 417 | struct uevent_sock *ue_sk; |
| 418 | struct netlink_kernel_cfg cfg = { |
| 419 | .groups = 1, |
| 420 | .flags = NL_CFG_F_NONROOT_RECV, |
| 421 | }; |
| 422 | |
| 423 | ue_sk = kzalloc(sizeof(*ue_sk), GFP_KERNEL); |
| 424 | if (!ue_sk) |
| 425 | return -ENOMEM; |
| 426 | |
| 427 | ue_sk->sk = netlink_kernel_create(net, NETLINK_KOBJECT_UEVENT, &cfg); |
| 428 | if (!ue_sk->sk) { |
| 429 | printk(KERN_ERR |
| 430 | "kobject_uevent: unable to create netlink socket!\n"); |
| 431 | kfree(ue_sk); |
| 432 | return -ENODEV; |
| 433 | } |
| 434 | mutex_lock(&uevent_sock_mutex); |
| 435 | list_add_tail(&ue_sk->list, &uevent_sock_list); |
| 436 | mutex_unlock(&uevent_sock_mutex); |
| 437 | return 0; |
| 438 | } |
| 439 | |
| 440 | static void uevent_net_exit(struct net *net) |
| 441 | { |
| 442 | struct uevent_sock *ue_sk; |
| 443 | |
| 444 | mutex_lock(&uevent_sock_mutex); |
| 445 | list_for_each_entry(ue_sk, &uevent_sock_list, list) { |
| 446 | if (sock_net(ue_sk->sk) == net) |
| 447 | goto found; |
| 448 | } |
| 449 | mutex_unlock(&uevent_sock_mutex); |
| 450 | return; |
| 451 | |
| 452 | found: |
| 453 | list_del(&ue_sk->list); |
| 454 | mutex_unlock(&uevent_sock_mutex); |
| 455 | |
| 456 | netlink_kernel_release(ue_sk->sk); |
| 457 | kfree(ue_sk); |
| 458 | } |
| 459 | |
| 460 | static struct pernet_operations uevent_net_ops = { |
| 461 | .init = uevent_net_init, |
| 462 | .exit = uevent_net_exit, |
| 463 | }; |
| 464 | |
| 465 | static int __init kobject_uevent_init(void) |
| 466 | { |
| 467 | return register_pernet_subsys(&uevent_net_ops); |
| 468 | } |
| 469 | |
| 470 | |
| 471 | postcore_initcall(kobject_uevent_init); |
| 472 | #endif |