netconsole.c

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/*
 *  linux/drivers/net/netconsole.c
 *
 *  Copyright (C) 2001  Ingo Molnar <[email protected]>
 *
 *  This file contains the implementation of an IRQ-safe, crash-safe
 *  kernel console implementation that outputs kernel messages to the
 *  network.
 *
 * Modification history:
 *
 * 2001-09-17    started by Ingo Molnar.
 * 2003-08-11    2.6 port by Matt Mackall
 *               simplified options
 *               generic card hooks
 *               works non-modular
 * 2003-09-07    rewritten with netpoll api
 */

/****************************************************************
 *      This program is free software; you can redistribute it and/or modify
 *      it under the terms of the GNU General Public License as published by
 *      the Free Software Foundation; either version 2, or (at your option)
 *      any later version.
 *
 *      This program is distributed in the hope that it will be useful,
 *      but WITHOUT ANY WARRANTY; without even the implied warranty of
 *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *      GNU General Public License for more details.
 *
 *      You should have received a copy of the GNU General Public License
 *      along with this program; if not, write to the Free Software
 *      Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 ****************************************************************/

#include <linux/mm.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/console.h>
#include <linux/moduleparam.h>
#include <linux/string.h>
#include <linux/netpoll.h>
#include <linux/inet.h>
#include <linux/configfs.h>

MODULE_AUTHOR("Maintainer: Matt Mackall <[email protected]>");
MODULE_DESCRIPTION("Console driver for network interfaces");
MODULE_LICENSE("GPL");

#define MAX_PARAM_LENGTH    256
#define MAX_PRINT_CHUNK     1000

static char config[MAX_PARAM_LENGTH];
module_param_string(netconsole, config, MAX_PARAM_LENGTH, 0);
MODULE_PARM_DESC(netconsole, " netconsole=[src-port]@[src-ip]/[dev],[tgt-port]@<tgt-ip>/[tgt-macaddr]");

#ifndef MODULE
static int __init option_setup(char *opt)
{
    strlcpy(config, opt, MAX_PARAM_LENGTH);
    return 1;
}
__setup("netconsole=", option_setup);
#endif  /* MODULE */

/* Linked list of all configured targets */
static LIST_HEAD(target_list);

/* This needs to be a spinlock because write_msg() cannot sleep */
static DEFINE_SPINLOCK(target_list_lock);

struct netconsole_target {
    struct list_head    list;
#ifdef  CONFIG_NETCONSOLE_DYNAMIC
    struct config_item  item;
#endif
    int         enabled;
    struct netpoll      np;
};

#ifdef  CONFIG_NETCONSOLE_DYNAMIC

static struct configfs_subsystem netconsole_subsys;

static int __init dynamic_netconsole_init(void)
{
    config_group_init(&netconsole_subsys.su_group);
    mutex_init(&netconsole_subsys.su_mutex);
    return configfs_register_subsystem(&netconsole_subsys);
}

static void __exit dynamic_netconsole_exit(void)
{
    configfs_unregister_subsystem(&netconsole_subsys);
}

/*
 * Targets that were created by parsing the boot/module option string
 * do not exist in the configfs hierarchy (and have NULL names) and will
 * never go away, so make these a no-op for them.
 */
static void netconsole_target_get(struct netconsole_target *nt)
{
    if (config_item_name(&nt->item))
        config_item_get(&nt->item);
}

static void netconsole_target_put(struct netconsole_target *nt)
{
    if (config_item_name(&nt->item))
        config_item_put(&nt->item);
}

#else   /* !CONFIG_NETCONSOLE_DYNAMIC */

static int __init dynamic_netconsole_init(void)
{
    return 0;
}

static void __exit dynamic_netconsole_exit(void)
{
}

/*
 * No danger of targets going away from under us when dynamic
 * reconfigurability is off.
 */
static void netconsole_target_get(struct netconsole_target *nt)
{
}

static void netconsole_target_put(struct netconsole_target *nt)
{
}

#endif  /* CONFIG_NETCONSOLE_DYNAMIC */

/* Allocate new target (from boot/module param) and setup netpoll for it */
static struct netconsole_target *alloc_param_target(char *target_config)
{
    int err = -ENOMEM;
    struct netconsole_target *nt;

    /*
     * Allocate and initialize with defaults.
     * Note that these targets get their config_item fields zeroed-out.
     */
    nt = kzalloc(sizeof(*nt), GFP_KERNEL);
    if (!nt)
        goto fail;

    nt->np.name = "netconsole";
    strlcpy(nt->np.dev_name, "eth0", IFNAMSIZ);
    nt->np.local_port = 6665;
    nt->np.remote_port = 6666;
    memset(nt->np.remote_mac, 0xff, ETH_ALEN);

    /* Parse parameters and setup netpoll */
    err = netpoll_parse_options(&nt->np, target_config);
    if (err)
        goto fail;

    err = netpoll_setup(&nt->np);
    if (err)
        goto fail;

    nt->enabled = 1;

    return nt;

fail:
    kfree(nt);
    return ERR_PTR(err);
}

/* Cleanup netpoll for given target (from boot/module param) and free it */
static void free_param_target(struct netconsole_target *nt)
{
    netpoll_cleanup(&nt->np);
    kfree(nt);
}

#ifdef  CONFIG_NETCONSOLE_DYNAMIC

/*
 * Our subsystem hierarchy is:
 *
 * /sys/kernel/config/netconsole/
 *              |
 *              <target>/
 *              |   enabled
 *              |   dev_name
 *              |   local_port
 *              |   remote_port
 *              |   local_ip
 *              |   remote_ip
 *              |   local_mac
 *              |   remote_mac
 *              |
 *              <target>/...
 */

struct netconsole_target_attr {
    struct configfs_attribute   attr;
    ssize_t             (*show)(struct netconsole_target *nt,
                        char *buf);
    ssize_t             (*store)(struct netconsole_target *nt,
                         const char *buf,
                         size_t count);
};

static struct netconsole_target *to_target(struct config_item *item)
{
    return item ?
        container_of(item, struct netconsole_target, item) :
        NULL;
}

/*
 * Attribute operations for netconsole_target.
 */

static ssize_t show_enabled(struct netconsole_target *nt, char *buf)
{
    return snprintf(buf, PAGE_SIZE, "%d\n", nt->enabled);
}

static ssize_t show_dev_name(struct netconsole_target *nt, char *buf)
{
    return snprintf(buf, PAGE_SIZE, "%s\n", nt->np.dev_name);
}

static ssize_t show_local_port(struct netconsole_target *nt, char *buf)
{
    return snprintf(buf, PAGE_SIZE, "%d\n", nt->np.local_port);
}

static ssize_t show_remote_port(struct netconsole_target *nt, char *buf)
{
    return snprintf(buf, PAGE_SIZE, "%d\n", nt->np.remote_port);
}

static ssize_t show_local_ip(struct netconsole_target *nt, char *buf)
{
    return snprintf(buf, PAGE_SIZE, "%pI4\n", &nt->np.local_ip);
}

static ssize_t show_remote_ip(struct netconsole_target *nt, char *buf)
{
    return snprintf(buf, PAGE_SIZE, "%pI4\n", &nt->np.remote_ip);
}

static ssize_t show_local_mac(struct netconsole_target *nt, char *buf)
{
    struct net_device *dev = nt->np.dev;
    static const u8 bcast[ETH_ALEN] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };

    return snprintf(buf, PAGE_SIZE, "%pM\n", dev ? dev->dev_addr : bcast);
}

static ssize_t show_remote_mac(struct netconsole_target *nt, char *buf)
{
    return snprintf(buf, PAGE_SIZE, "%pM\n", nt->np.remote_mac);
}

/*
 * This one is special -- targets created through the configfs interface
 * are not enabled (and the corresponding netpoll activated) by default.
 * The user is expected to set the desired parameters first (which
 * would enable him to dynamically add new netpoll targets for new
 * network interfaces as and when they come up).
 */
static ssize_t store_enabled(struct netconsole_target *nt,
                 const char *buf,
                 size_t count)
{
    int enabled;
    int err;

    err = kstrtoint(buf, 10, &enabled);
    if (err < 0)
        return err;
    if (enabled < 0 || enabled > 1)
        return -EINVAL;
    if (enabled == nt->enabled) {
        printk(KERN_INFO "netconsole: network logging has already %s\n",
                nt->enabled ? "started" : "stopped");
        return -EINVAL;
    }

    if (enabled) {  /* 1 */

        /*
         * Skip netpoll_parse_options() -- all the attributes are
         * already configured via configfs. Just print them out.
         */
        netpoll_print_options(&nt->np);

        err = netpoll_setup(&nt->np);
        if (err)
            return err;

        printk(KERN_INFO "netconsole: network logging started\n");

    } else {    /* 0 */
        netpoll_cleanup(&nt->np);
    }

    nt->enabled = enabled;

    return strnlen(buf, count);
}

static ssize_t store_dev_name(struct netconsole_target *nt,
                  const char *buf,
                  size_t count)
{
    size_t len;

    if (nt->enabled) {
        printk(KERN_ERR "netconsole: target (%s) is enabled, "
                "disable to update parameters\n",
                config_item_name(&nt->item));
        return -EINVAL;
    }

    strlcpy(nt->np.dev_name, buf, IFNAMSIZ);

    /* Get rid of possible trailing newline from echo(1) */
    len = strnlen(nt->np.dev_name, IFNAMSIZ);
    if (nt->np.dev_name[len - 1] == '\n')
        nt->np.dev_name[len - 1] = '\0';

    return strnlen(buf, count);
}

static ssize_t store_local_port(struct netconsole_target *nt,
                const char *buf,
                size_t count)
{
    int rv;

    if (nt->enabled) {
        printk(KERN_ERR "netconsole: target (%s) is enabled, "
                "disable to update parameters\n",
                config_item_name(&nt->item));
        return -EINVAL;
    }

    rv = kstrtou16(buf, 10, &nt->np.local_port);
    if (rv < 0)
        return rv;
    return strnlen(buf, count);
}

static ssize_t store_remote_port(struct netconsole_target *nt,
                 const char *buf,
                 size_t count)
{
    int rv;

    if (nt->enabled) {
        printk(KERN_ERR "netconsole: target (%s) is enabled, "
                "disable to update parameters\n",
                config_item_name(&nt->item));
        return -EINVAL;
    }

    rv = kstrtou16(buf, 10, &nt->np.remote_port);
    if (rv < 0)
        return rv;
    return strnlen(buf, count);
}

static ssize_t store_local_ip(struct netconsole_target *nt,
                  const char *buf,
                  size_t count)
{
    if (nt->enabled) {
        printk(KERN_ERR "netconsole: target (%s) is enabled, "
                "disable to update parameters\n",
                config_item_name(&nt->item));
        return -EINVAL;
    }

    nt->np.local_ip = in_aton(buf);

    return strnlen(buf, count);
}

static ssize_t store_remote_ip(struct netconsole_target *nt,
                   const char *buf,
                   size_t count)
{
    if (nt->enabled) {
        printk(KERN_ERR "netconsole: target (%s) is enabled, "
                "disable to update parameters\n",
                config_item_name(&nt->item));
        return -EINVAL;
    }

    nt->np.remote_ip = in_aton(buf);

    return strnlen(buf, count);
}

static ssize_t store_remote_mac(struct netconsole_target *nt,
                const char *buf,
                size_t count)
{
    u8 remote_mac[ETH_ALEN];

    if (nt->enabled) {
        printk(KERN_ERR "netconsole: target (%s) is enabled, "
                "disable to update parameters\n",
                config_item_name(&nt->item));
        return -EINVAL;
    }

    if (!mac_pton(buf, remote_mac))
        return -EINVAL;
    if (buf[3 * ETH_ALEN - 1] && buf[3 * ETH_ALEN - 1] != '\n')
        return -EINVAL;
    memcpy(nt->np.remote_mac, remote_mac, ETH_ALEN);

    return strnlen(buf, count);
}

/*
 * Attribute definitions for netconsole_target.
 */

#define NETCONSOLE_TARGET_ATTR_RO(_name)                \
static struct netconsole_target_attr netconsole_target_##_name =    \
    __CONFIGFS_ATTR(_name, S_IRUGO, show_##_name, NULL)

#define NETCONSOLE_TARGET_ATTR_RW(_name)                \
static struct netconsole_target_attr netconsole_target_##_name =    \
    __CONFIGFS_ATTR(_name, S_IRUGO | S_IWUSR, show_##_name, store_##_name)

NETCONSOLE_TARGET_ATTR_RW(enabled);
NETCONSOLE_TARGET_ATTR_RW(dev_name);
NETCONSOLE_TARGET_ATTR_RW(local_port);
NETCONSOLE_TARGET_ATTR_RW(remote_port);
NETCONSOLE_TARGET_ATTR_RW(local_ip);
NETCONSOLE_TARGET_ATTR_RW(remote_ip);
NETCONSOLE_TARGET_ATTR_RO(local_mac);
NETCONSOLE_TARGET_ATTR_RW(remote_mac);

static struct configfs_attribute *netconsole_target_attrs[] = {
    &netconsole_target_enabled.attr,
    &netconsole_target_dev_name.attr,
    &netconsole_target_local_port.attr,
    &netconsole_target_remote_port.attr,
    &netconsole_target_local_ip.attr,
    &netconsole_target_remote_ip.attr,
    &netconsole_target_local_mac.attr,
    &netconsole_target_remote_mac.attr,
    NULL,
};

/*
 * Item operations and type for netconsole_target.
 */

static void netconsole_target_release(struct config_item *item)
{
    kfree(to_target(item));
}

static ssize_t netconsole_target_attr_show(struct config_item *item,
                       struct configfs_attribute *attr,
                       char *buf)
{
    ssize_t ret = -EINVAL;
    struct netconsole_target *nt = to_target(item);
    struct netconsole_target_attr *na =
        container_of(attr, struct netconsole_target_attr, attr);

    if (na->show)
        ret = na->show(nt, buf);

    return ret;
}

static ssize_t netconsole_target_attr_store(struct config_item *item,
                        struct configfs_attribute *attr,
                        const char *buf,
                        size_t count)
{
    ssize_t ret = -EINVAL;
    struct netconsole_target *nt = to_target(item);
    struct netconsole_target_attr *na =
        container_of(attr, struct netconsole_target_attr, attr);

    if (na->store)
        ret = na->store(nt, buf, count);

    return ret;
}

static struct configfs_item_operations netconsole_target_item_ops = {
    .release        = netconsole_target_release,
    .show_attribute     = netconsole_target_attr_show,
    .store_attribute    = netconsole_target_attr_store,
};

static struct config_item_type netconsole_target_type = {
    .ct_attrs       = netconsole_target_attrs,
    .ct_item_ops        = &netconsole_target_item_ops,
    .ct_owner       = THIS_MODULE,
};

/*
 * Group operations and type for netconsole_subsys.
 */

static struct config_item *make_netconsole_target(struct config_group *group,
                          const char *name)
{
    unsigned long flags;
    struct netconsole_target *nt;

    /*
     * Allocate and initialize with defaults.
     * Target is disabled at creation (enabled == 0).
     */
    nt = kzalloc(sizeof(*nt), GFP_KERNEL);
    if (!nt)
        return ERR_PTR(-ENOMEM);

    nt->np.name = "netconsole";
    strlcpy(nt->np.dev_name, "eth0", IFNAMSIZ);
    nt->np.local_port = 6665;
    nt->np.remote_port = 6666;
    memset(nt->np.remote_mac, 0xff, ETH_ALEN);

    /* Initialize the config_item member */
    config_item_init_type_name(&nt->item, name, &netconsole_target_type);

    /* Adding, but it is disabled */
    spin_lock_irqsave(&target_list_lock, flags);
    list_add(&nt->list, &target_list);
    spin_unlock_irqrestore(&target_list_lock, flags);

    return &nt->item;
}

static void drop_netconsole_target(struct config_group *group,
                   struct config_item *item)
{
    unsigned long flags;
    struct netconsole_target *nt = to_target(item);

    spin_lock_irqsave(&target_list_lock, flags);
    list_del(&nt->list);
    spin_unlock_irqrestore(&target_list_lock, flags);

    /*
     * The target may have never been enabled, or was manually disabled
     * before being removed so netpoll may have already been cleaned up.
     */
    if (nt->enabled)
        netpoll_cleanup(&nt->np);

    config_item_put(&nt->item);
}

static struct configfs_group_operations netconsole_subsys_group_ops = {
    .make_item  = make_netconsole_target,
    .drop_item  = drop_netconsole_target,
};

static struct config_item_type netconsole_subsys_type = {
    .ct_group_ops   = &netconsole_subsys_group_ops,
    .ct_owner   = THIS_MODULE,
};

/* The netconsole configfs subsystem */
static struct configfs_subsystem netconsole_subsys = {
    .su_group   = {
        .cg_item    = {
            .ci_namebuf = "netconsole",
            .ci_type    = &netconsole_subsys_type,
        },
    },
};

#endif  /* CONFIG_NETCONSOLE_DYNAMIC */

/* Handle network interface device notifications */
static int netconsole_netdev_event(struct notifier_block *this,
                   unsigned long event,
                   void *ptr)
{
    unsigned long flags;
    struct netconsole_target *nt;
    struct net_device *dev = ptr;
    bool stopped = false;

    if (!(event == NETDEV_CHANGENAME || event == NETDEV_UNREGISTER ||
          event == NETDEV_RELEASE || event == NETDEV_JOIN))
        goto done;

    spin_lock_irqsave(&target_list_lock, flags);
    list_for_each_entry(nt, &target_list, list) {
        netconsole_target_get(nt);
        if (nt->np.dev == dev) {
            switch (event) {
            case NETDEV_CHANGENAME:
                strlcpy(nt->np.dev_name, dev->name, IFNAMSIZ);
                break;
            case NETDEV_RELEASE:
            case NETDEV_JOIN:
            case NETDEV_UNREGISTER:
                /*
                 * rtnl_lock already held
                 */
                if (nt->np.dev) {
                    __netpoll_cleanup(&nt->np);
                    dev_put(nt->np.dev);
                    nt->np.dev = NULL;
                }
                nt->enabled = 0;
                stopped = true;
                break;
            }
        }
        netconsole_target_put(nt);
    }
    spin_unlock_irqrestore(&target_list_lock, flags);
    if (stopped) {
        printk(KERN_INFO "netconsole: network logging stopped on "
               "interface %s as it ", dev->name);
        switch (event) {
        case NETDEV_UNREGISTER:
            printk(KERN_CONT "unregistered\n");
            break;
        case NETDEV_RELEASE:
            printk(KERN_CONT "released slaves\n");
            break;
        case NETDEV_JOIN:
            printk(KERN_CONT "is joining a master device\n");
            break;
        }
    }

done:
    return NOTIFY_DONE;
}

static struct notifier_block netconsole_netdev_notifier = {
    .notifier_call  = netconsole_netdev_event,
};

static void write_msg(struct console *con, const char *msg, unsigned int len)
{
    int frag, left;
    unsigned long flags;
    struct netconsole_target *nt;
    const char *tmp;

    /* Avoid taking lock and disabling interrupts unnecessarily */
    if (list_empty(&target_list))
        return;

    spin_lock_irqsave(&target_list_lock, flags);
    list_for_each_entry(nt, &target_list, list) {
        netconsole_target_get(nt);
        if (nt->enabled && netif_running(nt->np.dev)) {
            /*
             * We nest this inside the for-each-target loop above
             * so that we're able to get as much logging out to
             * at least one target if we die inside here, instead
             * of unnecessarily keeping all targets in lock-step.
             */
            tmp = msg;
            for (left = len; left;) {
                frag = min(left, MAX_PRINT_CHUNK);
                netpoll_send_udp(&nt->np, tmp, frag);
                tmp += frag;
                left -= frag;
            }
        }
        netconsole_target_put(nt);
    }
    spin_unlock_irqrestore(&target_list_lock, flags);
}

static struct console netconsole = {
    .name   = "netcon",
    .flags  = CON_ENABLED,
    .write  = write_msg,
};

static int __init init_netconsole(void)
{
    int err;
    struct netconsole_target *nt, *tmp;
    unsigned long flags;
    char *target_config;
    char *input = config;

    if (strnlen(input, MAX_PARAM_LENGTH)) {
        while ((target_config = strsep(&input, ";"))) {
            nt = alloc_param_target(target_config);
            if (IS_ERR(nt)) {
                err = PTR_ERR(nt);
                goto fail;
            }
            /* Dump existing printks when we register */
            netconsole.flags |= CON_PRINTBUFFER;

            spin_lock_irqsave(&target_list_lock, flags);
            list_add(&nt->list, &target_list);
            spin_unlock_irqrestore(&target_list_lock, flags);
        }
    }

    err = register_netdevice_notifier(&netconsole_netdev_notifier);
    if (err)
        goto fail;

    err = dynamic_netconsole_init();
    if (err)
        goto undonotifier;

    register_console(&netconsole);
    printk(KERN_INFO "netconsole: network logging started\n");

    return err;

undonotifier:
    unregister_netdevice_notifier(&netconsole_netdev_notifier);

fail:
    printk(KERN_ERR "netconsole: cleaning up\n");

    /*
     * Remove all targets and destroy them (only targets created
     * from the boot/module option exist here). Skipping the list
     * lock is safe here, and netpoll_cleanup() will sleep.
     */
    list_for_each_entry_safe(nt, tmp, &target_list, list) {
        list_del(&nt->list);
        free_param_target(nt);
    }

    return err;
}

static void __exit cleanup_netconsole(void)
{
    struct netconsole_target *nt, *tmp;

    unregister_console(&netconsole);
    dynamic_netconsole_exit();
    unregister_netdevice_notifier(&netconsole_netdev_notifier);

    /*
     * Targets created via configfs pin references on our module
     * and would first be rmdir(2)'ed from userspace. We reach
     * here only when they are already destroyed, and only those
     * created from the boot/module option are left, so remove and
     * destroy them. Skipping the list lock is safe here, and
     * netpoll_cleanup() will sleep.
     */
    list_for_each_entry_safe(nt, tmp, &target_list, list) {
        list_del(&nt->list);
        free_param_target(nt);
    }
}

/*
 * Use late_initcall to ensure netconsole is
 * initialized after network device driver if built-in.
 *
 * late_initcall() and module_init() are identical if built as module.
 */
late_initcall(init_netconsole);
module_exit(cleanup_netconsole);