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![Kay Sievers](/assets/img/avatar_default.png)
Users can read sysfs files, there is no reason they should not be allowed to listen to uevents. This lets xorg and other userspace programs properly get these messages without having to be root. Signed-off-by: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
336 lines
8.4 KiB
C
336 lines
8.4 KiB
C
/*
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* kernel userspace event delivery
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*
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* Copyright (C) 2004 Red Hat, Inc. All rights reserved.
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* Copyright (C) 2004 Novell, Inc. All rights reserved.
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* Copyright (C) 2004 IBM, Inc. All rights reserved.
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*
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* Licensed under the GNU GPL v2.
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*
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* Authors:
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* Robert Love <rml@novell.com>
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* Kay Sievers <kay.sievers@vrfy.org>
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* Arjan van de Ven <arjanv@redhat.com>
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* Greg Kroah-Hartman <greg@kroah.com>
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*/
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#include <linux/spinlock.h>
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#include <linux/string.h>
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#include <linux/kobject.h>
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#include <linux/module.h>
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#include <linux/socket.h>
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#include <linux/skbuff.h>
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#include <linux/netlink.h>
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#include <net/sock.h>
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u64 uevent_seqnum;
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char uevent_helper[UEVENT_HELPER_PATH_LEN] = CONFIG_UEVENT_HELPER_PATH;
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static DEFINE_SPINLOCK(sequence_lock);
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#if defined(CONFIG_NET)
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static struct sock *uevent_sock;
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#endif
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/* the strings here must match the enum in include/linux/kobject.h */
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static const char *kobject_actions[] = {
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[KOBJ_ADD] = "add",
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[KOBJ_REMOVE] = "remove",
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[KOBJ_CHANGE] = "change",
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[KOBJ_MOVE] = "move",
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[KOBJ_ONLINE] = "online",
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[KOBJ_OFFLINE] = "offline",
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};
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/**
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* kobject_action_type - translate action string to numeric type
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*
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* @buf: buffer containing the action string, newline is ignored
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* @len: length of buffer
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* @type: pointer to the location to store the action type
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*
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* Returns 0 if the action string was recognized.
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*/
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int kobject_action_type(const char *buf, size_t count,
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enum kobject_action *type)
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{
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enum kobject_action action;
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int ret = -EINVAL;
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if (count && (buf[count-1] == '\n' || buf[count-1] == '\0'))
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count--;
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if (!count)
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goto out;
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for (action = 0; action < ARRAY_SIZE(kobject_actions); action++) {
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if (strncmp(kobject_actions[action], buf, count) != 0)
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continue;
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if (kobject_actions[action][count] != '\0')
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continue;
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*type = action;
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ret = 0;
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break;
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}
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out:
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return ret;
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}
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/**
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* kobject_uevent_env - send an uevent with environmental data
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*
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* @action: action that is happening
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* @kobj: struct kobject that the action is happening to
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* @envp_ext: pointer to environmental data
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*
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* Returns 0 if kobject_uevent() is completed with success or the
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* corresponding error when it fails.
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*/
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int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
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char *envp_ext[])
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{
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struct kobj_uevent_env *env;
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const char *action_string = kobject_actions[action];
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const char *devpath = NULL;
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const char *subsystem;
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struct kobject *top_kobj;
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struct kset *kset;
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struct kset_uevent_ops *uevent_ops;
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u64 seq;
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int i = 0;
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int retval = 0;
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pr_debug("kobject: '%s' (%p): %s\n",
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kobject_name(kobj), kobj, __func__);
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/* search the kset we belong to */
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top_kobj = kobj;
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while (!top_kobj->kset && top_kobj->parent)
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top_kobj = top_kobj->parent;
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if (!top_kobj->kset) {
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pr_debug("kobject: '%s' (%p): %s: attempted to send uevent "
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"without kset!\n", kobject_name(kobj), kobj,
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__func__);
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return -EINVAL;
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}
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kset = top_kobj->kset;
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uevent_ops = kset->uevent_ops;
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/* skip the event, if uevent_suppress is set*/
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if (kobj->uevent_suppress) {
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pr_debug("kobject: '%s' (%p): %s: uevent_suppress "
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"caused the event to drop!\n",
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kobject_name(kobj), kobj, __func__);
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return 0;
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}
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/* skip the event, if the filter returns zero. */
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if (uevent_ops && uevent_ops->filter)
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if (!uevent_ops->filter(kset, kobj)) {
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pr_debug("kobject: '%s' (%p): %s: filter function "
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"caused the event to drop!\n",
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kobject_name(kobj), kobj, __func__);
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return 0;
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}
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/* originating subsystem */
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if (uevent_ops && uevent_ops->name)
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subsystem = uevent_ops->name(kset, kobj);
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else
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subsystem = kobject_name(&kset->kobj);
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if (!subsystem) {
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pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the "
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"event to drop!\n", kobject_name(kobj), kobj,
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__func__);
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return 0;
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}
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/* environment buffer */
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env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
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if (!env)
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return -ENOMEM;
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/* complete object path */
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devpath = kobject_get_path(kobj, GFP_KERNEL);
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if (!devpath) {
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retval = -ENOENT;
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goto exit;
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}
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/* default keys */
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retval = add_uevent_var(env, "ACTION=%s", action_string);
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if (retval)
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goto exit;
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retval = add_uevent_var(env, "DEVPATH=%s", devpath);
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if (retval)
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goto exit;
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retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem);
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if (retval)
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goto exit;
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/* keys passed in from the caller */
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if (envp_ext) {
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for (i = 0; envp_ext[i]; i++) {
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retval = add_uevent_var(env, "%s", envp_ext[i]);
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if (retval)
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goto exit;
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}
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}
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/* let the kset specific function add its stuff */
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if (uevent_ops && uevent_ops->uevent) {
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retval = uevent_ops->uevent(kset, kobj, env);
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if (retval) {
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pr_debug("kobject: '%s' (%p): %s: uevent() returned "
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"%d\n", kobject_name(kobj), kobj,
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__func__, retval);
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goto exit;
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}
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}
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/*
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* Mark "add" and "remove" events in the object to ensure proper
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* events to userspace during automatic cleanup. If the object did
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* send an "add" event, "remove" will automatically generated by
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* the core, if not already done by the caller.
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*/
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if (action == KOBJ_ADD)
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kobj->state_add_uevent_sent = 1;
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else if (action == KOBJ_REMOVE)
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kobj->state_remove_uevent_sent = 1;
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/* we will send an event, so request a new sequence number */
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spin_lock(&sequence_lock);
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seq = ++uevent_seqnum;
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spin_unlock(&sequence_lock);
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retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)seq);
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if (retval)
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goto exit;
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#if defined(CONFIG_NET)
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/* send netlink message */
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if (uevent_sock) {
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struct sk_buff *skb;
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size_t len;
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/* allocate message with the maximum possible size */
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len = strlen(action_string) + strlen(devpath) + 2;
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skb = alloc_skb(len + env->buflen, GFP_KERNEL);
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if (skb) {
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char *scratch;
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/* add header */
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scratch = skb_put(skb, len);
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sprintf(scratch, "%s@%s", action_string, devpath);
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/* copy keys to our continuous event payload buffer */
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for (i = 0; i < env->envp_idx; i++) {
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len = strlen(env->envp[i]) + 1;
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scratch = skb_put(skb, len);
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strcpy(scratch, env->envp[i]);
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}
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NETLINK_CB(skb).dst_group = 1;
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retval = netlink_broadcast(uevent_sock, skb, 0, 1,
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GFP_KERNEL);
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/* ENOBUFS should be handled in userspace */
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if (retval == -ENOBUFS)
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retval = 0;
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} else
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retval = -ENOMEM;
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}
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#endif
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/* call uevent_helper, usually only enabled during early boot */
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if (uevent_helper[0]) {
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char *argv [3];
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argv [0] = uevent_helper;
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argv [1] = (char *)subsystem;
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argv [2] = NULL;
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retval = add_uevent_var(env, "HOME=/");
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if (retval)
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goto exit;
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retval = add_uevent_var(env,
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"PATH=/sbin:/bin:/usr/sbin:/usr/bin");
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if (retval)
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goto exit;
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retval = call_usermodehelper(argv[0], argv,
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env->envp, UMH_WAIT_EXEC);
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}
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exit:
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kfree(devpath);
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kfree(env);
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return retval;
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}
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EXPORT_SYMBOL_GPL(kobject_uevent_env);
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/**
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* kobject_uevent - notify userspace by ending an uevent
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*
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* @action: action that is happening
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* @kobj: struct kobject that the action is happening to
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*
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* Returns 0 if kobject_uevent() is completed with success or the
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* corresponding error when it fails.
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*/
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int kobject_uevent(struct kobject *kobj, enum kobject_action action)
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{
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return kobject_uevent_env(kobj, action, NULL);
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}
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EXPORT_SYMBOL_GPL(kobject_uevent);
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/**
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* add_uevent_var - add key value string to the environment buffer
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* @env: environment buffer structure
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* @format: printf format for the key=value pair
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*
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* Returns 0 if environment variable was added successfully or -ENOMEM
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* if no space was available.
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*/
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int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
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{
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va_list args;
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int len;
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if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
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WARN(1, KERN_ERR "add_uevent_var: too many keys\n");
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return -ENOMEM;
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}
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va_start(args, format);
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len = vsnprintf(&env->buf[env->buflen],
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sizeof(env->buf) - env->buflen,
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format, args);
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va_end(args);
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if (len >= (sizeof(env->buf) - env->buflen)) {
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WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n");
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return -ENOMEM;
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}
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env->envp[env->envp_idx++] = &env->buf[env->buflen];
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env->buflen += len + 1;
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return 0;
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}
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EXPORT_SYMBOL_GPL(add_uevent_var);
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#if defined(CONFIG_NET)
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static int __init kobject_uevent_init(void)
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{
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uevent_sock = netlink_kernel_create(&init_net, NETLINK_KOBJECT_UEVENT,
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1, NULL, NULL, THIS_MODULE);
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if (!uevent_sock) {
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printk(KERN_ERR
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"kobject_uevent: unable to create netlink socket!\n");
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return -ENODEV;
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}
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netlink_set_nonroot(NETLINK_KOBJECT_UEVENT, NL_NONROOT_RECV);
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return 0;
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}
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postcore_initcall(kobject_uevent_init);
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#endif
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