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![Pablo Neira Ayuso](/assets/img/avatar_default.png)
This patch adds the following structure: struct netlink_kernel_cfg { unsigned int groups; void (*input)(struct sk_buff *skb); struct mutex *cb_mutex; }; That can be passed to netlink_kernel_create to set optional configurations for netlink kernel sockets. I've populated this structure by looking for NULL and zero parameters at the existing code. The remaining parameters that always need to be set are still left in the original interface. That includes optional parameters for the netlink socket creation. This allows easy extensibility of this interface in the future. This patch also adapts all callers to use this new interface. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: David S. Miller <davem@davemloft.net>
431 lines
10 KiB
C
431 lines
10 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/export.h>
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#include <linux/kmod.h>
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#include <linux/slab.h>
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#include <linux/user_namespace.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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#include <net/net_namespace.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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#ifdef CONFIG_NET
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struct uevent_sock {
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struct list_head list;
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struct sock *sk;
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};
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static LIST_HEAD(uevent_sock_list);
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#endif
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/* This lock protects uevent_seqnum and uevent_sock_list */
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static DEFINE_MUTEX(uevent_sock_mutex);
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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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#ifdef CONFIG_NET
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static int kobj_bcast_filter(struct sock *dsk, struct sk_buff *skb, void *data)
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{
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struct kobject *kobj = data;
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const struct kobj_ns_type_operations *ops;
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ops = kobj_ns_ops(kobj);
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if (ops) {
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const void *sock_ns, *ns;
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ns = kobj->ktype->namespace(kobj);
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sock_ns = ops->netlink_ns(dsk);
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return sock_ns != ns;
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}
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return 0;
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}
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#endif
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static int kobj_usermode_filter(struct kobject *kobj)
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{
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const struct kobj_ns_type_operations *ops;
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ops = kobj_ns_ops(kobj);
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if (ops) {
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const void *init_ns, *ns;
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ns = kobj->ktype->namespace(kobj);
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init_ns = ops->initial_ns();
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return ns != init_ns;
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}
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return 0;
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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_env() 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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const struct kset_uevent_ops *uevent_ops;
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int i = 0;
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int retval = 0;
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#ifdef CONFIG_NET
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struct uevent_sock *ue_sk;
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#endif
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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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mutex_lock(&uevent_sock_mutex);
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/* we will send an event, so request a new sequence number */
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retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)++uevent_seqnum);
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if (retval) {
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mutex_unlock(&uevent_sock_mutex);
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goto exit;
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}
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#if defined(CONFIG_NET)
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/* send netlink message */
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list_for_each_entry(ue_sk, &uevent_sock_list, list) {
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struct sock *uevent_sock = ue_sk->sk;
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struct sk_buff *skb;
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size_t len;
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if (!netlink_has_listeners(uevent_sock, 1))
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continue;
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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_filtered(uevent_sock, skb,
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0, 1, GFP_KERNEL,
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kobj_bcast_filter,
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kobj);
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/* ENOBUFS should be handled in userspace */
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if (retval == -ENOBUFS || retval == -ESRCH)
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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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mutex_unlock(&uevent_sock_mutex);
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/* call uevent_helper, usually only enabled during early boot */
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if (uevent_helper[0] && !kobj_usermode_filter(kobj)) {
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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 sending 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 uevent_net_init(struct net *net)
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{
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struct uevent_sock *ue_sk;
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struct netlink_kernel_cfg cfg = {
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.groups = 1,
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};
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ue_sk = kzalloc(sizeof(*ue_sk), GFP_KERNEL);
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if (!ue_sk)
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return -ENOMEM;
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ue_sk->sk = netlink_kernel_create(net, NETLINK_KOBJECT_UEVENT,
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THIS_MODULE, &cfg);
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if (!ue_sk->sk) {
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printk(KERN_ERR
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"kobject_uevent: unable to create netlink socket!\n");
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kfree(ue_sk);
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return -ENODEV;
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}
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mutex_lock(&uevent_sock_mutex);
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list_add_tail(&ue_sk->list, &uevent_sock_list);
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mutex_unlock(&uevent_sock_mutex);
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return 0;
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}
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static void uevent_net_exit(struct net *net)
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{
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struct uevent_sock *ue_sk;
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mutex_lock(&uevent_sock_mutex);
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list_for_each_entry(ue_sk, &uevent_sock_list, list) {
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if (sock_net(ue_sk->sk) == net)
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goto found;
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}
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mutex_unlock(&uevent_sock_mutex);
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return;
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found:
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list_del(&ue_sk->list);
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mutex_unlock(&uevent_sock_mutex);
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netlink_kernel_release(ue_sk->sk);
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kfree(ue_sk);
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}
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static struct pernet_operations uevent_net_ops = {
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.init = uevent_net_init,
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.exit = uevent_net_exit,
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};
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static int __init kobject_uevent_init(void)
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{
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netlink_set_nonroot(NETLINK_KOBJECT_UEVENT, NL_NONROOT_RECV);
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return register_pernet_subsys(&uevent_net_ops);
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}
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postcore_initcall(kobject_uevent_init);
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#endif
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