/*
 * kernel userspace event delivery
 *
 * Copyright (C) 2004 Red Hat, Inc.  All rights reserved.
 * Copyright (C) 2004 Novell, Inc.  All rights reserved.
 * Copyright (C) 2004 IBM, Inc. All rights reserved.
 *
 * Licensed under the GNU GPL v2.
 *
 * Authors:
 *      Robert Love             <rml@novell.com>
 *      Kay Sievers             <kay.sievers@vrfy.org>
 *      Arjan van de Ven        <arjanv@redhat.com>
 *      Greg Kroah-Hartman      <greg@kroah.com>
 */

#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 <net/sock.h>
#include <net/net_namespace.h>


u64 uevent_seqnum;
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

/* 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)
{
        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
 * @kobj: struct kobject that the action is happening to
 * @envp_ext: pointer to environmental data
 *
 * 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[])
{
        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;
        const struct kset_uevent_ops *uevent_ops;
        int i = 0;
        int retval = 0;
#ifdef CONFIG_NET
        struct uevent_sock *ue_sk;
#endif

        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)
                top_kobj = top_kobj->parent;

        if (!top_kobj->kset) {
                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 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: '%s' (%p): %s: filter function "
                                 "caused the event to drop!\n",
                                 kobject_name(kobj), kobj, __func__);
                        return 0;
                }

        /* originating subsystem */
        if (uevent_ops && uevent_ops->name)
                subsystem = uevent_ops->name(kset, kobj);
        else
                subsystem = kobject_name(&kset->kobj);
        if (!subsystem) {
                pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the "
                         "event to drop!\n", kobject_name(kobj), kobj,
                         __func__);
                return 0;
        }

        /* environment buffer */
        env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
        if (!env)
                return -ENOMEM;

        /* complete object path */
        devpath = kobject_get_path(kobj, GFP_KERNEL);
        if (!devpath) {
                retval = -ENOENT;
                goto exit;
        }

        /* default keys */
        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, env);
                if (retval) {
                        pr_debug("kobject: '%s' (%p): %s: uevent() returned "
                                 "%d\n", kobject_name(kobj), kobj,
                                 __func__, retval);
                        goto exit;
                }
        }

        /*
         * 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 */
        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 + 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 = 0; i < env->envp_idx; i++) {
                                len = strlen(env->envp[i]) + 1;
                                scratch = skb_put(skb, len);
                                strcpy(scratch, env->envp[i]);
                        }

                        NETLINK_CB(skb).dst_group = 1;
                        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] && !kobj_usermode_filter(kobj)) {
                char *argv [3];

                argv [0] = uevent_helper;
                argv [1] = (char *)subsystem;
                argv [2] = NULL;
                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(env);
        return retval;
}
EXPORT_SYMBOL_GPL(kobject_uevent_env);

/**
 * kobject_uevent - notify userspace by sending an uevent
 *
 * @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
 * corresponding error when it fails.
 */
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 - 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(struct kobj_uevent_env *env, const char *format, ...)
{
        va_list args;
        int len;

        if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
                WARN(1, KERN_ERR "add_uevent_var: too many keys\n");
                return -ENOMEM;
        }

        va_start(args, format);
        len = vsnprintf(&env->buf[env->buflen],
                        sizeof(env->buf) - env->buflen,
                        format, args);
        va_end(args);

        if (len >= (sizeof(env->buf) - env->buflen)) {
                WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n");
                return -ENOMEM;
        }

        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 uevent_net_init(struct net *net)
{
        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;

        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