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/module.h> 21 #include <linux/slab.h> 22 #include <linux/user_namespace.h> 23 #include <linux/socket.h> 24 #include <linux/skbuff.h> 25 #include <linux/netlink.h> 26 #include <net/sock.h> 27 #include <net/net_namespace.h> 28 29 30 u64 uevent_seqnum; 31 char uevent_helper[UEVENT_HELPER_PATH_LEN] = CONFIG_UEVENT_HELPER_PATH; 32 static DEFINE_SPINLOCK(sequence_lock); 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 static DEFINE_MUTEX(uevent_sock_mutex); 40 #endif 41 42 /* the strings here must match the enum in include/linux/kobject.h */ 43 static const char *kobject_actions[] = { 44 [KOBJ_ADD] = "add", 45 [KOBJ_REMOVE] = "remove", 46 [KOBJ_CHANGE] = "change", 47 [KOBJ_MOVE] = "move", 48 [KOBJ_ONLINE] = "online", 49 [KOBJ_OFFLINE] = "offline", 50 }; 51 52 /** 53 * kobject_action_type - translate action string to numeric type 54 * 55 * @buf: buffer containing the action string, newline is ignored 56 * @len: length of buffer 57 * @type: pointer to the location to store the action type 58 * 59 * Returns 0 if the action string was recognized. 60 */ 61 int kobject_action_type(const char *buf, size_t count, 62 enum kobject_action *type) 63 { 64 enum kobject_action action; 65 int ret = -EINVAL; 66 67 if (count && (buf[count-1] == '\n' || buf[count-1] == '\0')) 68 count--; 69 70 if (!count) 71 goto out; 72 73 for (action = 0; action < ARRAY_SIZE(kobject_actions); action++) { 74 if (strncmp(kobject_actions[action], buf, count) != 0) 75 continue; 76 if (kobject_actions[action][count] != '\0') 77 continue; 78 *type = action; 79 ret = 0; 80 break; 81 } 82 out: 83 return ret; 84 } 85 86 #ifdef CONFIG_NET 87 static int kobj_bcast_filter(struct sock *dsk, struct sk_buff *skb, void *data) 88 { 89 struct kobject *kobj = data; 90 const struct kobj_ns_type_operations *ops; 91 92 ops = kobj_ns_ops(kobj); 93 if (ops) { 94 const void *sock_ns, *ns; 95 ns = kobj->ktype->namespace(kobj); 96 sock_ns = ops->netlink_ns(dsk); 97 return sock_ns != ns; 98 } 99 100 return 0; 101 } 102 #endif 103 104 static int kobj_usermode_filter(struct kobject *kobj) 105 { 106 const struct kobj_ns_type_operations *ops; 107 108 ops = kobj_ns_ops(kobj); 109 if (ops) { 110 const void *init_ns, *ns; 111 ns = kobj->ktype->namespace(kobj); 112 init_ns = ops->initial_ns(); 113 return ns != init_ns; 114 } 115 116 return 0; 117 } 118 119 /** 120 * kobject_uevent_env - send an uevent with environmental data 121 * 122 * @action: action that is happening 123 * @kobj: struct kobject that the action is happening to 124 * @envp_ext: pointer to environmental data 125 * 126 * Returns 0 if kobject_uevent_env() is completed with success or the 127 * corresponding error when it fails. 128 */ 129 int kobject_uevent_env(struct kobject *kobj, enum kobject_action action, 130 char *envp_ext[]) 131 { 132 struct kobj_uevent_env *env; 133 const char *action_string = kobject_actions[action]; 134 const char *devpath = NULL; 135 const char *subsystem; 136 struct kobject *top_kobj; 137 struct kset *kset; 138 const struct kset_uevent_ops *uevent_ops; 139 u64 seq; 140 int i = 0; 141 int retval = 0; 142 #ifdef CONFIG_NET 143 struct uevent_sock *ue_sk; 144 #endif 145 146 pr_debug("kobject: '%s' (%p): %s\n", 147 kobject_name(kobj), kobj, __func__); 148 149 /* search the kset we belong to */ 150 top_kobj = kobj; 151 while (!top_kobj->kset && top_kobj->parent) 152 top_kobj = top_kobj->parent; 153 154 if (!top_kobj->kset) { 155 pr_debug("kobject: '%s' (%p): %s: attempted to send uevent " 156 "without kset!\n", kobject_name(kobj), kobj, 157 __func__); 158 return -EINVAL; 159 } 160 161 kset = top_kobj->kset; 162 uevent_ops = kset->uevent_ops; 163 164 /* skip the event, if uevent_suppress is set*/ 165 if (kobj->uevent_suppress) { 166 pr_debug("kobject: '%s' (%p): %s: uevent_suppress " 167 "caused the event to drop!\n", 168 kobject_name(kobj), kobj, __func__); 169 return 0; 170 } 171 /* skip the event, if the filter returns zero. */ 172 if (uevent_ops && uevent_ops->filter) 173 if (!uevent_ops->filter(kset, kobj)) { 174 pr_debug("kobject: '%s' (%p): %s: filter function " 175 "caused the event to drop!\n", 176 kobject_name(kobj), kobj, __func__); 177 return 0; 178 } 179 180 /* originating subsystem */ 181 if (uevent_ops && uevent_ops->name) 182 subsystem = uevent_ops->name(kset, kobj); 183 else 184 subsystem = kobject_name(&kset->kobj); 185 if (!subsystem) { 186 pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the " 187 "event to drop!\n", kobject_name(kobj), kobj, 188 __func__); 189 return 0; 190 } 191 192 /* environment buffer */ 193 env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL); 194 if (!env) 195 return -ENOMEM; 196 197 /* complete object path */ 198 devpath = kobject_get_path(kobj, GFP_KERNEL); 199 if (!devpath) { 200 retval = -ENOENT; 201 goto exit; 202 } 203 204 /* default keys */ 205 retval = add_uevent_var(env, "ACTION=%s", action_string); 206 if (retval) 207 goto exit; 208 retval = add_uevent_var(env, "DEVPATH=%s", devpath); 209 if (retval) 210 goto exit; 211 retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem); 212 if (retval) 213 goto exit; 214 215 /* keys passed in from the caller */ 216 if (envp_ext) { 217 for (i = 0; envp_ext[i]; i++) { 218 retval = add_uevent_var(env, "%s", envp_ext[i]); 219 if (retval) 220 goto exit; 221 } 222 } 223 224 /* let the kset specific function add its stuff */ 225 if (uevent_ops && uevent_ops->uevent) { 226 retval = uevent_ops->uevent(kset, kobj, env); 227 if (retval) { 228 pr_debug("kobject: '%s' (%p): %s: uevent() returned " 229 "%d\n", kobject_name(kobj), kobj, 230 __func__, retval); 231 goto exit; 232 } 233 } 234 235 /* 236 * Mark "add" and "remove" events in the object to ensure proper 237 * events to userspace during automatic cleanup. If the object did 238 * send an "add" event, "remove" will automatically generated by 239 * the core, if not already done by the caller. 240 */ 241 if (action == KOBJ_ADD) 242 kobj->state_add_uevent_sent = 1; 243 else if (action == KOBJ_REMOVE) 244 kobj->state_remove_uevent_sent = 1; 245 246 /* we will send an event, so request a new sequence number */ 247 spin_lock(&sequence_lock); 248 seq = ++uevent_seqnum; 249 spin_unlock(&sequence_lock); 250 retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)seq); 251 if (retval) 252 goto exit; 253 254 #if defined(CONFIG_NET) 255 /* send netlink message */ 256 mutex_lock(&uevent_sock_mutex); 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 mutex_unlock(&uevent_sock_mutex); 294 #endif 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; 376 377 ue_sk = kzalloc(sizeof(*ue_sk), GFP_KERNEL); 378 if (!ue_sk) 379 return -ENOMEM; 380 381 ue_sk->sk = netlink_kernel_create(net, NETLINK_KOBJECT_UEVENT, 382 1, NULL, NULL, THIS_MODULE); 383 if (!ue_sk->sk) { 384 printk(KERN_ERR 385 "kobject_uevent: unable to create netlink socket!\n"); 386 kfree(ue_sk); 387 return -ENODEV; 388 } 389 mutex_lock(&uevent_sock_mutex); 390 list_add_tail(&ue_sk->list, &uevent_sock_list); 391 mutex_unlock(&uevent_sock_mutex); 392 return 0; 393 } 394 395 static void uevent_net_exit(struct net *net) 396 { 397 struct uevent_sock *ue_sk; 398 399 mutex_lock(&uevent_sock_mutex); 400 list_for_each_entry(ue_sk, &uevent_sock_list, list) { 401 if (sock_net(ue_sk->sk) == net) 402 goto found; 403 } 404 mutex_unlock(&uevent_sock_mutex); 405 return; 406 407 found: 408 list_del(&ue_sk->list); 409 mutex_unlock(&uevent_sock_mutex); 410 411 netlink_kernel_release(ue_sk->sk); 412 kfree(ue_sk); 413 } 414 415 static struct pernet_operations uevent_net_ops = { 416 .init = uevent_net_init, 417 .exit = uevent_net_exit, 418 }; 419 420 static int __init kobject_uevent_init(void) 421 { 422 netlink_set_nonroot(NETLINK_KOBJECT_UEVENT, NL_NONROOT_RECV); 423 return register_pernet_subsys(&uevent_net_ops); 424 } 425 426 427 postcore_initcall(kobject_uevent_init); 428 #endif 429