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 char uevent_helper[UEVENT_HELPER_PATH_LEN] = CONFIG_UEVENT_HELPER_PATH; 33 #ifdef CONFIG_NET 34 struct uevent_sock { 35 struct list_head list; 36 struct sock *sk; 37 }; 38 static LIST_HEAD(uevent_sock_list); 39 #endif 40 41 /* This lock protects uevent_seqnum and uevent_sock_list */ 42 static DEFINE_MUTEX(uevent_sock_mutex); 43 44 /* the strings here must match the enum in include/linux/kobject.h */ 45 static const char *kobject_actions[] = { 46 [KOBJ_ADD] = "add", 47 [KOBJ_REMOVE] = "remove", 48 [KOBJ_CHANGE] = "change", 49 [KOBJ_MOVE] = "move", 50 [KOBJ_ONLINE] = "online", 51 [KOBJ_OFFLINE] = "offline", 52 }; 53 54 /** 55 * kobject_action_type - translate action string to numeric type 56 * 57 * @buf: buffer containing the action string, newline is ignored 58 * @len: length of buffer 59 * @type: pointer to the location to store the action type 60 * 61 * Returns 0 if the action string was recognized. 62 */ 63 int kobject_action_type(const char *buf, size_t count, 64 enum kobject_action *type) 65 { 66 enum kobject_action action; 67 int ret = -EINVAL; 68 69 if (count && (buf[count-1] == '\n' || buf[count-1] == '\0')) 70 count--; 71 72 if (!count) 73 goto out; 74 75 for (action = 0; action < ARRAY_SIZE(kobject_actions); action++) { 76 if (strncmp(kobject_actions[action], buf, count) != 0) 77 continue; 78 if (kobject_actions[action][count] != '\0') 79 continue; 80 *type = action; 81 ret = 0; 82 break; 83 } 84 out: 85 return ret; 86 } 87 88 #ifdef CONFIG_NET 89 static int kobj_bcast_filter(struct sock *dsk, struct sk_buff *skb, void *data) 90 { 91 struct kobject *kobj = data; 92 const struct kobj_ns_type_operations *ops; 93 94 ops = kobj_ns_ops(kobj); 95 if (ops) { 96 const void *sock_ns, *ns; 97 ns = kobj->ktype->namespace(kobj); 98 sock_ns = ops->netlink_ns(dsk); 99 return sock_ns != ns; 100 } 101 102 return 0; 103 } 104 #endif 105 106 static int kobj_usermode_filter(struct kobject *kobj) 107 { 108 const struct kobj_ns_type_operations *ops; 109 110 ops = kobj_ns_ops(kobj); 111 if (ops) { 112 const void *init_ns, *ns; 113 ns = kobj->ktype->namespace(kobj); 114 init_ns = ops->initial_ns(); 115 return ns != init_ns; 116 } 117 118 return 0; 119 } 120 121 /** 122 * kobject_uevent_env - send an uevent with environmental data 123 * 124 * @action: action that is happening 125 * @kobj: struct kobject that the action is happening to 126 * @envp_ext: pointer to environmental data 127 * 128 * Returns 0 if kobject_uevent_env() is completed with success or the 129 * corresponding error when it fails. 130 */ 131 int kobject_uevent_env(struct kobject *kobj, enum kobject_action action, 132 char *envp_ext[]) 133 { 134 struct kobj_uevent_env *env; 135 const char *action_string = kobject_actions[action]; 136 const char *devpath = NULL; 137 const char *subsystem; 138 struct kobject *top_kobj; 139 struct kset *kset; 140 const struct kset_uevent_ops *uevent_ops; 141 int i = 0; 142 int retval = 0; 143 #ifdef CONFIG_NET 144 struct uevent_sock *ue_sk; 145 #endif 146 147 pr_debug("kobject: '%s' (%p): %s\n", 148 kobject_name(kobj), kobj, __func__); 149 150 /* search the kset we belong to */ 151 top_kobj = kobj; 152 while (!top_kobj->kset && top_kobj->parent) 153 top_kobj = top_kobj->parent; 154 155 if (!top_kobj->kset) { 156 pr_debug("kobject: '%s' (%p): %s: attempted to send uevent " 157 "without kset!\n", kobject_name(kobj), kobj, 158 __func__); 159 return -EINVAL; 160 } 161 162 kset = top_kobj->kset; 163 uevent_ops = kset->uevent_ops; 164 165 /* skip the event, if uevent_suppress is set*/ 166 if (kobj->uevent_suppress) { 167 pr_debug("kobject: '%s' (%p): %s: uevent_suppress " 168 "caused the event to drop!\n", 169 kobject_name(kobj), kobj, __func__); 170 return 0; 171 } 172 /* skip the event, if the filter returns zero. */ 173 if (uevent_ops && uevent_ops->filter) 174 if (!uevent_ops->filter(kset, kobj)) { 175 pr_debug("kobject: '%s' (%p): %s: filter function " 176 "caused the event to drop!\n", 177 kobject_name(kobj), kobj, __func__); 178 return 0; 179 } 180 181 /* originating subsystem */ 182 if (uevent_ops && uevent_ops->name) 183 subsystem = uevent_ops->name(kset, kobj); 184 else 185 subsystem = kobject_name(&kset->kobj); 186 if (!subsystem) { 187 pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the " 188 "event to drop!\n", kobject_name(kobj), kobj, 189 __func__); 190 return 0; 191 } 192 193 /* environment buffer */ 194 env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL); 195 if (!env) 196 return -ENOMEM; 197 198 /* complete object path */ 199 devpath = kobject_get_path(kobj, GFP_KERNEL); 200 if (!devpath) { 201 retval = -ENOENT; 202 goto exit; 203 } 204 205 /* default keys */ 206 retval = add_uevent_var(env, "ACTION=%s", action_string); 207 if (retval) 208 goto exit; 209 retval = add_uevent_var(env, "DEVPATH=%s", devpath); 210 if (retval) 211 goto exit; 212 retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem); 213 if (retval) 214 goto exit; 215 216 /* keys passed in from the caller */ 217 if (envp_ext) { 218 for (i = 0; envp_ext[i]; i++) { 219 retval = add_uevent_var(env, "%s", envp_ext[i]); 220 if (retval) 221 goto exit; 222 } 223 } 224 225 /* let the kset specific function add its stuff */ 226 if (uevent_ops && uevent_ops->uevent) { 227 retval = uevent_ops->uevent(kset, kobj, env); 228 if (retval) { 229 pr_debug("kobject: '%s' (%p): %s: uevent() returned " 230 "%d\n", kobject_name(kobj), kobj, 231 __func__, retval); 232 goto exit; 233 } 234 } 235 236 /* 237 * Mark "add" and "remove" events in the object to ensure proper 238 * events to userspace during automatic cleanup. If the object did 239 * send an "add" event, "remove" will automatically generated by 240 * the core, if not already done by the caller. 241 */ 242 if (action == KOBJ_ADD) 243 kobj->state_add_uevent_sent = 1; 244 else if (action == KOBJ_REMOVE) 245 kobj->state_remove_uevent_sent = 1; 246 247 mutex_lock(&uevent_sock_mutex); 248 /* we will send an event, so request a new sequence number */ 249 retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)++uevent_seqnum); 250 if (retval) { 251 mutex_unlock(&uevent_sock_mutex); 252 goto exit; 253 } 254 255 #if defined(CONFIG_NET) 256 /* send netlink message */ 257 list_for_each_entry(ue_sk, &uevent_sock_list, list) { 258 struct sock *uevent_sock = ue_sk->sk; 259 struct sk_buff *skb; 260 size_t len; 261 262 if (!netlink_has_listeners(uevent_sock, 1)) 263 continue; 264 265 /* allocate message with the maximum possible size */ 266 len = strlen(action_string) + strlen(devpath) + 2; 267 skb = alloc_skb(len + env->buflen, GFP_KERNEL); 268 if (skb) { 269 char *scratch; 270 271 /* add header */ 272 scratch = skb_put(skb, len); 273 sprintf(scratch, "%s@%s", action_string, devpath); 274 275 /* copy keys to our continuous event payload buffer */ 276 for (i = 0; i < env->envp_idx; i++) { 277 len = strlen(env->envp[i]) + 1; 278 scratch = skb_put(skb, len); 279 strcpy(scratch, env->envp[i]); 280 } 281 282 NETLINK_CB(skb).dst_group = 1; 283 retval = netlink_broadcast_filtered(uevent_sock, skb, 284 0, 1, GFP_KERNEL, 285 kobj_bcast_filter, 286 kobj); 287 /* ENOBUFS should be handled in userspace */ 288 if (retval == -ENOBUFS || retval == -ESRCH) 289 retval = 0; 290 } else 291 retval = -ENOMEM; 292 } 293 #endif 294 mutex_unlock(&uevent_sock_mutex); 295 296 /* call uevent_helper, usually only enabled during early boot */ 297 if (uevent_helper[0] && !kobj_usermode_filter(kobj)) { 298 char *argv [3]; 299 300 argv [0] = uevent_helper; 301 argv [1] = (char *)subsystem; 302 argv [2] = NULL; 303 retval = add_uevent_var(env, "HOME=/"); 304 if (retval) 305 goto exit; 306 retval = add_uevent_var(env, 307 "PATH=/sbin:/bin:/usr/sbin:/usr/bin"); 308 if (retval) 309 goto exit; 310 311 retval = call_usermodehelper(argv[0], argv, 312 env->envp, UMH_WAIT_EXEC); 313 } 314 315 exit: 316 kfree(devpath); 317 kfree(env); 318 return retval; 319 } 320 EXPORT_SYMBOL_GPL(kobject_uevent_env); 321 322 /** 323 * kobject_uevent - notify userspace by sending an uevent 324 * 325 * @action: action that is happening 326 * @kobj: struct kobject that the action is happening to 327 * 328 * Returns 0 if kobject_uevent() is completed with success or the 329 * corresponding error when it fails. 330 */ 331 int kobject_uevent(struct kobject *kobj, enum kobject_action action) 332 { 333 return kobject_uevent_env(kobj, action, NULL); 334 } 335 EXPORT_SYMBOL_GPL(kobject_uevent); 336 337 /** 338 * add_uevent_var - add key value string to the environment buffer 339 * @env: environment buffer structure 340 * @format: printf format for the key=value pair 341 * 342 * Returns 0 if environment variable was added successfully or -ENOMEM 343 * if no space was available. 344 */ 345 int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...) 346 { 347 va_list args; 348 int len; 349 350 if (env->envp_idx >= ARRAY_SIZE(env->envp)) { 351 WARN(1, KERN_ERR "add_uevent_var: too many keys\n"); 352 return -ENOMEM; 353 } 354 355 va_start(args, format); 356 len = vsnprintf(&env->buf[env->buflen], 357 sizeof(env->buf) - env->buflen, 358 format, args); 359 va_end(args); 360 361 if (len >= (sizeof(env->buf) - env->buflen)) { 362 WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n"); 363 return -ENOMEM; 364 } 365 366 env->envp[env->envp_idx++] = &env->buf[env->buflen]; 367 env->buflen += len + 1; 368 return 0; 369 } 370 EXPORT_SYMBOL_GPL(add_uevent_var); 371 372 #if defined(CONFIG_NET) 373 static int uevent_net_init(struct net *net) 374 { 375 struct uevent_sock *ue_sk; 376 struct netlink_kernel_cfg cfg = { 377 .groups = 1, 378 .flags = NL_CFG_F_NONROOT_RECV, 379 }; 380 381 ue_sk = kzalloc(sizeof(*ue_sk), GFP_KERNEL); 382 if (!ue_sk) 383 return -ENOMEM; 384 385 ue_sk->sk = netlink_kernel_create(net, NETLINK_KOBJECT_UEVENT, &cfg); 386 if (!ue_sk->sk) { 387 printk(KERN_ERR 388 "kobject_uevent: unable to create netlink socket!\n"); 389 kfree(ue_sk); 390 return -ENODEV; 391 } 392 mutex_lock(&uevent_sock_mutex); 393 list_add_tail(&ue_sk->list, &uevent_sock_list); 394 mutex_unlock(&uevent_sock_mutex); 395 return 0; 396 } 397 398 static void uevent_net_exit(struct net *net) 399 { 400 struct uevent_sock *ue_sk; 401 402 mutex_lock(&uevent_sock_mutex); 403 list_for_each_entry(ue_sk, &uevent_sock_list, list) { 404 if (sock_net(ue_sk->sk) == net) 405 goto found; 406 } 407 mutex_unlock(&uevent_sock_mutex); 408 return; 409 410 found: 411 list_del(&ue_sk->list); 412 mutex_unlock(&uevent_sock_mutex); 413 414 netlink_kernel_release(ue_sk->sk); 415 kfree(ue_sk); 416 } 417 418 static struct pernet_operations uevent_net_ops = { 419 .init = uevent_net_init, 420 .exit = uevent_net_exit, 421 }; 422 423 static int __init kobject_uevent_init(void) 424 { 425 return register_pernet_subsys(&uevent_net_ops); 426 } 427 428 429 postcore_initcall(kobject_uevent_init); 430 #endif 431