lzo: properly check for overruns
[linux-3.10.git] / lib / kobject_uevent.c
index 12e311d..52e5abb 100644 (file)
  */
 
 #include <linux/spinlock.h>
+#include <linux/string.h>
+#include <linux/kobject.h>
+#include <linux/export.h>
+#include <linux/kmod.h>
+#include <linux/slab.h>
+#include <linux/user_namespace.h>
 #include <linux/socket.h>
 #include <linux/skbuff.h>
 #include <linux/netlink.h>
-#include <linux/string.h>
-#include <linux/kobject.h>
 #include <net/sock.h>
+#include <net/net_namespace.h>
 
-#define BUFFER_SIZE    2048    /* buffer for the variables */
-#define NUM_ENVP       32      /* number of env pointers */
 
-#if defined(CONFIG_HOTPLUG)
 u64 uevent_seqnum;
-char uevent_helper[UEVENT_HELPER_PATH_LEN] = "/sbin/hotplug";
-static DEFINE_SPINLOCK(sequence_lock);
-#if defined(CONFIG_NET)
-static struct sock *uevent_sock;
+char uevent_helper[UEVENT_HELPER_PATH_LEN] = CONFIG_UEVENT_HELPER_PATH;
+#ifdef CONFIG_NET
+struct uevent_sock {
+       struct list_head list;
+       struct sock *sk;
+};
+static LIST_HEAD(uevent_sock_list);
 #endif
 
-static char *action_to_string(enum kobject_action action)
+/* This lock protects uevent_seqnum and uevent_sock_list */
+static DEFINE_MUTEX(uevent_sock_mutex);
+
+/* the strings here must match the enum in include/linux/kobject.h */
+static const char *kobject_actions[] = {
+       [KOBJ_ADD] =            "add",
+       [KOBJ_REMOVE] =         "remove",
+       [KOBJ_CHANGE] =         "change",
+       [KOBJ_MOVE] =           "move",
+       [KOBJ_ONLINE] =         "online",
+       [KOBJ_OFFLINE] =        "offline",
+};
+
+/**
+ * kobject_action_type - translate action string to numeric type
+ *
+ * @buf: buffer containing the action string, newline is ignored
+ * @len: length of buffer
+ * @type: pointer to the location to store the action type
+ *
+ * Returns 0 if the action string was recognized.
+ */
+int kobject_action_type(const char *buf, size_t count,
+                       enum kobject_action *type)
+{
+       enum kobject_action action;
+       int ret = -EINVAL;
+
+       if (count && (buf[count-1] == '\n' || buf[count-1] == '\0'))
+               count--;
+
+       if (!count)
+               goto out;
+
+       for (action = 0; action < ARRAY_SIZE(kobject_actions); action++) {
+               if (strncmp(kobject_actions[action], buf, count) != 0)
+                       continue;
+               if (kobject_actions[action][count] != '\0')
+                       continue;
+               *type = action;
+               ret = 0;
+               break;
+       }
+out:
+       return ret;
+}
+
+#ifdef CONFIG_NET
+static int kobj_bcast_filter(struct sock *dsk, struct sk_buff *skb, void *data)
 {
-       switch (action) {
-       case KOBJ_ADD:
-               return "add";
-       case KOBJ_REMOVE:
-               return "remove";
-       case KOBJ_CHANGE:
-               return "change";
-       case KOBJ_OFFLINE:
-               return "offline";
-       case KOBJ_ONLINE:
-               return "online";
-       case KOBJ_MOVE:
-               return "move";
-       default:
-               return NULL;
+       struct kobject *kobj = data;
+       const struct kobj_ns_type_operations *ops;
+
+       ops = kobj_ns_ops(kobj);
+       if (ops) {
+               const void *sock_ns, *ns;
+               ns = kobj->ktype->namespace(kobj);
+               sock_ns = ops->netlink_ns(dsk);
+               return sock_ns != ns;
        }
+
+       return 0;
+}
+#endif
+
+static int kobj_usermode_filter(struct kobject *kobj)
+{
+       const struct kobj_ns_type_operations *ops;
+
+       ops = kobj_ns_ops(kobj);
+       if (ops) {
+               const void *init_ns, *ns;
+               ns = kobj->ktype->namespace(kobj);
+               init_ns = ops->initial_ns();
+               return ns != init_ns;
+       }
+
+       return 0;
 }
 
 /**
  * kobject_uevent_env - send an uevent with environmental data
  *
- * @action: action that is happening (usually KOBJ_MOVE)
+ * @action: action that is happening
  * @kobj: struct kobject that the action is happening to
  * @envp_ext: pointer to environmental data
  *
- * Returns 0 if kobject_uevent() is completed with success or the
+ * Returns 0 if kobject_uevent_env() is completed with success or the
  * corresponding error when it fails.
  */
 int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
-                       char *envp_ext[])
+                      char *envp_ext[])
 {
-       char **envp;
-       char *buffer;
-       char *scratch;
-       const char *action_string;
+       struct kobj_uevent_env *env;
+       const char *action_string = kobject_actions[action];
        const char *devpath = NULL;
        const char *subsystem;
        struct kobject *top_kobj;
        struct kset *kset;
-       struct kset_uevent_ops *uevent_ops;
-       u64 seq;
-       char *seq_buff;
+       const struct kset_uevent_ops *uevent_ops;
        int i = 0;
        int retval = 0;
-       int j;
+#ifdef CONFIG_NET
+       struct uevent_sock *ue_sk;
+#endif
 
-       pr_debug("%s\n", __FUNCTION__);
-
-       action_string = action_to_string(action);
-       if (!action_string) {
-               pr_debug("kobject attempted to send uevent without action_string!\n");
-               return -EINVAL;
-       }
+       pr_debug("kobject: '%s' (%p): %s\n",
+                kobject_name(kobj), kobj, __func__);
 
        /* search the kset we belong to */
        top_kobj = kobj;
-       while (!top_kobj->kset && top_kobj->parent) {
+       while (!top_kobj->kset && top_kobj->parent)
                top_kobj = top_kobj->parent;
-       }
+
        if (!top_kobj->kset) {
-               pr_debug("kobject attempted to send uevent without kset!\n");
+               pr_debug("kobject: '%s' (%p): %s: attempted to send uevent "
+                        "without kset!\n", kobject_name(kobj), kobj,
+                        __func__);
                return -EINVAL;
        }
 
        kset = top_kobj->kset;
        uevent_ops = kset->uevent_ops;
 
-       /*  skip the event, if the filter returns zero. */
+       /* skip the event, if uevent_suppress is set*/
+       if (kobj->uevent_suppress) {
+               pr_debug("kobject: '%s' (%p): %s: uevent_suppress "
+                                "caused the event to drop!\n",
+                                kobject_name(kobj), kobj, __func__);
+               return 0;
+       }
+       /* skip the event, if the filter returns zero. */
        if (uevent_ops && uevent_ops->filter)
                if (!uevent_ops->filter(kset, kobj)) {
-                       pr_debug("kobject filter function caused the event to drop!\n");
+                       pr_debug("kobject: '%s' (%p): %s: filter function "
+                                "caused the event to drop!\n",
+                                kobject_name(kobj), kobj, __func__);
                        return 0;
                }
 
@@ -115,22 +184,17 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
        else
                subsystem = kobject_name(&kset->kobj);
        if (!subsystem) {
-               pr_debug("unset subsytem caused the event to drop!\n");
+               pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the "
+                        "event to drop!\n", kobject_name(kobj), kobj,
+                        __func__);
                return 0;
        }
 
-       /* environment index */
-       envp = kzalloc(NUM_ENVP * sizeof (char *), GFP_KERNEL);
-       if (!envp)
+       /* environment buffer */
+       env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
+       if (!env)
                return -ENOMEM;
 
-       /* environment values */
-       buffer = kmalloc(BUFFER_SIZE, GFP_KERNEL);
-       if (!buffer) {
-               retval = -ENOMEM;
-               goto exit;
-       }
-
        /* complete object path */
        devpath = kobject_get_path(kobj, GFP_KERNEL);
        if (!devpath) {
@@ -138,92 +202,127 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
                goto exit;
        }
 
-       /* event environemnt for helper process only */
-       envp[i++] = "HOME=/";
-       envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
-
        /* default keys */
-       scratch = buffer;
-       envp [i++] = scratch;
-       scratch += sprintf(scratch, "ACTION=%s", action_string) + 1;
-       envp [i++] = scratch;
-       scratch += sprintf (scratch, "DEVPATH=%s", devpath) + 1;
-       envp [i++] = scratch;
-       scratch += sprintf(scratch, "SUBSYSTEM=%s", subsystem) + 1;
-       for (j = 0; envp_ext && envp_ext[j]; j++)
-               envp[i++] = envp_ext[j];
-       /* just reserve the space, overwrite it after kset call has returned */
-       envp[i++] = seq_buff = scratch;
-       scratch += strlen("SEQNUM=18446744073709551616") + 1;
+       retval = add_uevent_var(env, "ACTION=%s", action_string);
+       if (retval)
+               goto exit;
+       retval = add_uevent_var(env, "DEVPATH=%s", devpath);
+       if (retval)
+               goto exit;
+       retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem);
+       if (retval)
+               goto exit;
+
+       /* keys passed in from the caller */
+       if (envp_ext) {
+               for (i = 0; envp_ext[i]; i++) {
+                       retval = add_uevent_var(env, "%s", envp_ext[i]);
+                       if (retval)
+                               goto exit;
+               }
+       }
 
        /* let the kset specific function add its stuff */
        if (uevent_ops && uevent_ops->uevent) {
-               retval = uevent_ops->uevent(kset, kobj,
-                                 &envp[i], NUM_ENVP - i, scratch,
-                                 BUFFER_SIZE - (scratch - buffer));
+               retval = uevent_ops->uevent(kset, kobj, env);
                if (retval) {
-                       pr_debug ("%s - uevent() returned %d\n",
-                                 __FUNCTION__, retval);
+                       pr_debug("kobject: '%s' (%p): %s: uevent() returned "
+                                "%d\n", kobject_name(kobj), kobj,
+                                __func__, retval);
                        goto exit;
                }
        }
 
-       /* we will send an event, request a new sequence number */
-       spin_lock(&sequence_lock);
-       seq = ++uevent_seqnum;
-       spin_unlock(&sequence_lock);
-       sprintf(seq_buff, "SEQNUM=%llu", (unsigned long long)seq);
+       /*
+        * Mark "add" and "remove" events in the object to ensure proper
+        * events to userspace during automatic cleanup. If the object did
+        * send an "add" event, "remove" will automatically generated by
+        * the core, if not already done by the caller.
+        */
+       if (action == KOBJ_ADD)
+               kobj->state_add_uevent_sent = 1;
+       else if (action == KOBJ_REMOVE)
+               kobj->state_remove_uevent_sent = 1;
+
+       mutex_lock(&uevent_sock_mutex);
+       /* we will send an event, so request a new sequence number */
+       retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)++uevent_seqnum);
+       if (retval) {
+               mutex_unlock(&uevent_sock_mutex);
+               goto exit;
+       }
 
 #if defined(CONFIG_NET)
        /* send netlink message */
-       if (uevent_sock) {
+       list_for_each_entry(ue_sk, &uevent_sock_list, list) {
+               struct sock *uevent_sock = ue_sk->sk;
                struct sk_buff *skb;
                size_t len;
 
+               if (!netlink_has_listeners(uevent_sock, 1))
+                       continue;
+
                /* allocate message with the maximum possible size */
                len = strlen(action_string) + strlen(devpath) + 2;
-               skb = alloc_skb(len + BUFFER_SIZE, GFP_KERNEL);
+               skb = alloc_skb(len + env->buflen, GFP_KERNEL);
                if (skb) {
+                       char *scratch;
+
                        /* add header */
                        scratch = skb_put(skb, len);
                        sprintf(scratch, "%s@%s", action_string, devpath);
 
                        /* copy keys to our continuous event payload buffer */
-                       for (i = 2; envp[i]; i++) {
-                               len = strlen(envp[i]) + 1;
+                       for (i = 0; i < env->envp_idx; i++) {
+                               len = strlen(env->envp[i]) + 1;
                                scratch = skb_put(skb, len);
-                               strcpy(scratch, envp[i]);
+                               strcpy(scratch, env->envp[i]);
                        }
 
                        NETLINK_CB(skb).dst_group = 1;
-                       netlink_broadcast(uevent_sock, skb, 0, 1, GFP_KERNEL);
-               }
+                       retval = netlink_broadcast_filtered(uevent_sock, skb,
+                                                           0, 1, GFP_KERNEL,
+                                                           kobj_bcast_filter,
+                                                           kobj);
+                       /* ENOBUFS should be handled in userspace */
+                       if (retval == -ENOBUFS || retval == -ESRCH)
+                               retval = 0;
+               } else
+                       retval = -ENOMEM;
        }
 #endif
+       mutex_unlock(&uevent_sock_mutex);
 
        /* call uevent_helper, usually only enabled during early boot */
-       if (uevent_helper[0]) {
+       if (uevent_helper[0] && !kobj_usermode_filter(kobj)) {
                char *argv [3];
 
                argv [0] = uevent_helper;
                argv [1] = (char *)subsystem;
                argv [2] = NULL;
-               call_usermodehelper (argv[0], argv, envp, 0);
+               retval = add_uevent_var(env, "HOME=/");
+               if (retval)
+                       goto exit;
+               retval = add_uevent_var(env,
+                                       "PATH=/sbin:/bin:/usr/sbin:/usr/bin");
+               if (retval)
+                       goto exit;
+
+               retval = call_usermodehelper(argv[0], argv,
+                                            env->envp, UMH_WAIT_EXEC);
        }
 
 exit:
        kfree(devpath);
-       kfree(buffer);
-       kfree(envp);
+       kfree(env);
        return retval;
 }
-
 EXPORT_SYMBOL_GPL(kobject_uevent_env);
 
 /**
- * kobject_uevent - notify userspace by ending an uevent
+ * kobject_uevent - notify userspace by sending an uevent
  *
- * @action: action that is happening (usually KOBJ_ADD and KOBJ_REMOVE)
+ * @action: action that is happening
  * @kobj: struct kobject that the action is happening to
  *
  * Returns 0 if kobject_uevent() is completed with success or the
@@ -233,76 +332,99 @@ int kobject_uevent(struct kobject *kobj, enum kobject_action action)
 {
        return kobject_uevent_env(kobj, action, NULL);
 }
-
 EXPORT_SYMBOL_GPL(kobject_uevent);
 
 /**
- * add_uevent_var - helper for creating event variables
- * @envp: Pointer to table of environment variables, as passed into
- * uevent() method.
- * @num_envp: Number of environment variable slots available, as
- * passed into uevent() method.
- * @cur_index: Pointer to current index into @envp.  It should be
- * initialized to 0 before the first call to add_uevent_var(),
- * and will be incremented on success.
- * @buffer: Pointer to buffer for environment variables, as passed
- * into uevent() method.
- * @buffer_size: Length of @buffer, as passed into uevent() method.
- * @cur_len: Pointer to current length of space used in @buffer.
- * Should be initialized to 0 before the first call to
- * add_uevent_var(), and will be incremented on success.
- * @format: Format for creating environment variable (of the form
- * "XXX=%x") for snprintf().
+ * add_uevent_var - add key value string to the environment buffer
+ * @env: environment buffer structure
+ * @format: printf format for the key=value pair
  *
  * Returns 0 if environment variable was added successfully or -ENOMEM
  * if no space was available.
  */
-int add_uevent_var(char **envp, int num_envp, int *cur_index,
-                  char *buffer, int buffer_size, int *cur_len,
-                  const char *format, ...)
+int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
 {
        va_list args;
+       int len;
 
-       /*
-        * We check against num_envp - 1 to make sure there is at
-        * least one slot left after we return, since kobject_uevent()
-        * needs to set the last slot to NULL.
-        */
-       if (*cur_index >= num_envp - 1)
+       if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
+               WARN(1, KERN_ERR "add_uevent_var: too many keys\n");
                return -ENOMEM;
-
-       envp[*cur_index] = buffer + *cur_len;
+       }
 
        va_start(args, format);
-       *cur_len += vsnprintf(envp[*cur_index],
-                             max(buffer_size - *cur_len, 0),
-                             format, args) + 1;
+       len = vsnprintf(&env->buf[env->buflen],
+                       sizeof(env->buf) - env->buflen,
+                       format, args);
        va_end(args);
 
-       if (*cur_len > buffer_size)
+       if (len >= (sizeof(env->buf) - env->buflen)) {
+               WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n");
                return -ENOMEM;
+       }
 
-       (*cur_index)++;
+       env->envp[env->envp_idx++] = &env->buf[env->buflen];
+       env->buflen += len + 1;
        return 0;
 }
 EXPORT_SYMBOL_GPL(add_uevent_var);
 
 #if defined(CONFIG_NET)
-static int __init kobject_uevent_init(void)
+static int uevent_net_init(struct net *net)
 {
-       uevent_sock = netlink_kernel_create(NETLINK_KOBJECT_UEVENT, 1, NULL,
-                                           NULL, THIS_MODULE);
+       struct uevent_sock *ue_sk;
+       struct netlink_kernel_cfg cfg = {
+               .groups = 1,
+               .flags  = NL_CFG_F_NONROOT_RECV,
+       };
+
+       ue_sk = kzalloc(sizeof(*ue_sk), GFP_KERNEL);
+       if (!ue_sk)
+               return -ENOMEM;
 
-       if (!uevent_sock) {
+       ue_sk->sk = netlink_kernel_create(net, NETLINK_KOBJECT_UEVENT, &cfg);
+       if (!ue_sk->sk) {
                printk(KERN_ERR
                       "kobject_uevent: unable to create netlink socket!\n");
+               kfree(ue_sk);
                return -ENODEV;
        }
-
+       mutex_lock(&uevent_sock_mutex);
+       list_add_tail(&ue_sk->list, &uevent_sock_list);
+       mutex_unlock(&uevent_sock_mutex);
        return 0;
 }
 
+static void uevent_net_exit(struct net *net)
+{
+       struct uevent_sock *ue_sk;
+
+       mutex_lock(&uevent_sock_mutex);
+       list_for_each_entry(ue_sk, &uevent_sock_list, list) {
+               if (sock_net(ue_sk->sk) == net)
+                       goto found;
+       }
+       mutex_unlock(&uevent_sock_mutex);
+       return;
+
+found:
+       list_del(&ue_sk->list);
+       mutex_unlock(&uevent_sock_mutex);
+
+       netlink_kernel_release(ue_sk->sk);
+       kfree(ue_sk);
+}
+
+static struct pernet_operations uevent_net_ops = {
+       .init   = uevent_net_init,
+       .exit   = uevent_net_exit,
+};
+
+static int __init kobject_uevent_init(void)
+{
+       return register_pernet_subsys(&uevent_net_ops);
+}
+
+
 postcore_initcall(kobject_uevent_init);
 #endif
-
-#endif /* CONFIG_HOTPLUG */