1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * linux/drivers/net/netconsole.c
5 * Copyright (C) 2001 Ingo Molnar <mingo@redhat.com>
7 * This file contains the implementation of an IRQ-safe, crash-safe
8 * kernel console implementation that outputs kernel messages to the
11 * Modification history:
13 * 2001-09-17 started by Ingo Molnar.
14 * 2003-08-11 2.6 port by Matt Mackall
18 * 2003-09-07 rewritten with netpoll api
21 /****************************************************************
23 ****************************************************************/
25 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
28 #include <linux/init.h>
29 #include <linux/module.h>
30 #include <linux/slab.h>
31 #include <linux/console.h>
32 #include <linux/moduleparam.h>
33 #include <linux/kernel.h>
34 #include <linux/string.h>
35 #include <linux/netpoll.h>
36 #include <linux/inet.h>
37 #include <linux/configfs.h>
38 #include <linux/etherdevice.h>
40 MODULE_AUTHOR("Maintainer: Matt Mackall <mpm@selenic.com>");
41 MODULE_DESCRIPTION("Console driver for network interfaces");
42 MODULE_LICENSE("GPL");
44 #define MAX_PARAM_LENGTH 256
45 #define MAX_PRINT_CHUNK 1000
47 static char config[MAX_PARAM_LENGTH];
48 module_param_string(netconsole, config, MAX_PARAM_LENGTH, 0);
49 MODULE_PARM_DESC(netconsole, " netconsole=[src-port]@[src-ip]/[dev],[tgt-port]@<tgt-ip>/[tgt-macaddr]");
51 static bool oops_only = false;
52 module_param(oops_only, bool, 0600);
53 MODULE_PARM_DESC(oops_only, "Only log oops messages");
56 static int __init option_setup(char *opt)
58 strlcpy(config, opt, MAX_PARAM_LENGTH);
61 __setup("netconsole=", option_setup);
64 /* Linked list of all configured targets */
65 static LIST_HEAD(target_list);
67 /* This needs to be a spinlock because write_msg() cannot sleep */
68 static DEFINE_SPINLOCK(target_list_lock);
71 * Console driver for extended netconsoles. Registered on the first use to
72 * avoid unnecessarily enabling ext message formatting.
74 static struct console netconsole_ext;
77 * struct netconsole_target - Represents a configured netconsole target.
78 * @list: Links this target into the target_list.
79 * @item: Links us into the configfs subsystem hierarchy.
80 * @enabled: On / off knob to enable / disable target.
81 * Visible from userspace (read-write).
82 * We maintain a strict 1:1 correspondence between this and
83 * whether the corresponding netpoll is active or inactive.
84 * Also, other parameters of a target may be modified at
85 * runtime only when it is disabled (enabled == 0).
86 * @np: The netpoll structure for this target.
87 * Contains the other userspace visible parameters:
88 * dev_name (read-write)
89 * local_port (read-write)
90 * remote_port (read-write)
91 * local_ip (read-write)
92 * remote_ip (read-write)
93 * local_mac (read-only)
94 * remote_mac (read-write)
96 struct netconsole_target {
97 struct list_head list;
98 #ifdef CONFIG_NETCONSOLE_DYNAMIC
99 struct config_item item;
106 #ifdef CONFIG_NETCONSOLE_DYNAMIC
108 static struct configfs_subsystem netconsole_subsys;
109 static DEFINE_MUTEX(dynamic_netconsole_mutex);
111 static int __init dynamic_netconsole_init(void)
113 config_group_init(&netconsole_subsys.su_group);
114 mutex_init(&netconsole_subsys.su_mutex);
115 return configfs_register_subsystem(&netconsole_subsys);
118 static void __exit dynamic_netconsole_exit(void)
120 configfs_unregister_subsystem(&netconsole_subsys);
124 * Targets that were created by parsing the boot/module option string
125 * do not exist in the configfs hierarchy (and have NULL names) and will
126 * never go away, so make these a no-op for them.
128 static void netconsole_target_get(struct netconsole_target *nt)
130 if (config_item_name(&nt->item))
131 config_item_get(&nt->item);
134 static void netconsole_target_put(struct netconsole_target *nt)
136 if (config_item_name(&nt->item))
137 config_item_put(&nt->item);
140 #else /* !CONFIG_NETCONSOLE_DYNAMIC */
142 static int __init dynamic_netconsole_init(void)
147 static void __exit dynamic_netconsole_exit(void)
152 * No danger of targets going away from under us when dynamic
153 * reconfigurability is off.
155 static void netconsole_target_get(struct netconsole_target *nt)
159 static void netconsole_target_put(struct netconsole_target *nt)
163 #endif /* CONFIG_NETCONSOLE_DYNAMIC */
165 /* Allocate new target (from boot/module param) and setup netpoll for it */
166 static struct netconsole_target *alloc_param_target(char *target_config)
169 struct netconsole_target *nt;
172 * Allocate and initialize with defaults.
173 * Note that these targets get their config_item fields zeroed-out.
175 nt = kzalloc(sizeof(*nt), GFP_KERNEL);
179 nt->np.name = "netconsole";
180 strlcpy(nt->np.dev_name, "eth0", IFNAMSIZ);
181 nt->np.local_port = 6665;
182 nt->np.remote_port = 6666;
183 eth_broadcast_addr(nt->np.remote_mac);
185 if (*target_config == '+') {
190 /* Parse parameters and setup netpoll */
191 err = netpoll_parse_options(&nt->np, target_config);
195 err = netpoll_setup(&nt->np);
208 /* Cleanup netpoll for given target (from boot/module param) and free it */
209 static void free_param_target(struct netconsole_target *nt)
211 netpoll_cleanup(&nt->np);
215 #ifdef CONFIG_NETCONSOLE_DYNAMIC
218 * Our subsystem hierarchy is:
220 * /sys/kernel/config/netconsole/
235 static struct netconsole_target *to_target(struct config_item *item)
238 container_of(item, struct netconsole_target, item) :
243 * Attribute operations for netconsole_target.
246 static ssize_t enabled_show(struct config_item *item, char *buf)
248 return snprintf(buf, PAGE_SIZE, "%d\n", to_target(item)->enabled);
251 static ssize_t extended_show(struct config_item *item, char *buf)
253 return snprintf(buf, PAGE_SIZE, "%d\n", to_target(item)->extended);
256 static ssize_t dev_name_show(struct config_item *item, char *buf)
258 return snprintf(buf, PAGE_SIZE, "%s\n", to_target(item)->np.dev_name);
261 static ssize_t local_port_show(struct config_item *item, char *buf)
263 return snprintf(buf, PAGE_SIZE, "%d\n", to_target(item)->np.local_port);
266 static ssize_t remote_port_show(struct config_item *item, char *buf)
268 return snprintf(buf, PAGE_SIZE, "%d\n", to_target(item)->np.remote_port);
271 static ssize_t local_ip_show(struct config_item *item, char *buf)
273 struct netconsole_target *nt = to_target(item);
276 return snprintf(buf, PAGE_SIZE, "%pI6c\n", &nt->np.local_ip.in6);
278 return snprintf(buf, PAGE_SIZE, "%pI4\n", &nt->np.local_ip);
281 static ssize_t remote_ip_show(struct config_item *item, char *buf)
283 struct netconsole_target *nt = to_target(item);
286 return snprintf(buf, PAGE_SIZE, "%pI6c\n", &nt->np.remote_ip.in6);
288 return snprintf(buf, PAGE_SIZE, "%pI4\n", &nt->np.remote_ip);
291 static ssize_t local_mac_show(struct config_item *item, char *buf)
293 struct net_device *dev = to_target(item)->np.dev;
294 static const u8 bcast[ETH_ALEN] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
296 return snprintf(buf, PAGE_SIZE, "%pM\n", dev ? dev->dev_addr : bcast);
299 static ssize_t remote_mac_show(struct config_item *item, char *buf)
301 return snprintf(buf, PAGE_SIZE, "%pM\n", to_target(item)->np.remote_mac);
305 * This one is special -- targets created through the configfs interface
306 * are not enabled (and the corresponding netpoll activated) by default.
307 * The user is expected to set the desired parameters first (which
308 * would enable him to dynamically add new netpoll targets for new
309 * network interfaces as and when they come up).
311 static ssize_t enabled_store(struct config_item *item,
312 const char *buf, size_t count)
314 struct netconsole_target *nt = to_target(item);
319 mutex_lock(&dynamic_netconsole_mutex);
320 err = kstrtoint(buf, 10, &enabled);
325 if (enabled < 0 || enabled > 1)
327 if ((bool)enabled == nt->enabled) {
328 pr_info("network logging has already %s\n",
329 nt->enabled ? "started" : "stopped");
333 if (enabled) { /* true */
334 if (nt->extended && !(netconsole_ext.flags & CON_ENABLED)) {
335 netconsole_ext.flags |= CON_ENABLED;
336 register_console(&netconsole_ext);
340 * Skip netpoll_parse_options() -- all the attributes are
341 * already configured via configfs. Just print them out.
343 netpoll_print_options(&nt->np);
345 err = netpoll_setup(&nt->np);
349 pr_info("network logging started\n");
351 /* We need to disable the netconsole before cleaning it up
352 * otherwise we might end up in write_msg() with
353 * nt->np.dev == NULL and nt->enabled == true
355 spin_lock_irqsave(&target_list_lock, flags);
357 spin_unlock_irqrestore(&target_list_lock, flags);
358 netpoll_cleanup(&nt->np);
361 nt->enabled = enabled;
363 mutex_unlock(&dynamic_netconsole_mutex);
364 return strnlen(buf, count);
366 mutex_unlock(&dynamic_netconsole_mutex);
370 static ssize_t extended_store(struct config_item *item, const char *buf,
373 struct netconsole_target *nt = to_target(item);
377 mutex_lock(&dynamic_netconsole_mutex);
379 pr_err("target (%s) is enabled, disable to update parameters\n",
380 config_item_name(&nt->item));
385 err = kstrtoint(buf, 10, &extended);
388 if (extended < 0 || extended > 1) {
393 nt->extended = extended;
395 mutex_unlock(&dynamic_netconsole_mutex);
396 return strnlen(buf, count);
398 mutex_unlock(&dynamic_netconsole_mutex);
402 static ssize_t dev_name_store(struct config_item *item, const char *buf,
405 struct netconsole_target *nt = to_target(item);
408 mutex_lock(&dynamic_netconsole_mutex);
410 pr_err("target (%s) is enabled, disable to update parameters\n",
411 config_item_name(&nt->item));
412 mutex_unlock(&dynamic_netconsole_mutex);
416 strlcpy(nt->np.dev_name, buf, IFNAMSIZ);
418 /* Get rid of possible trailing newline from echo(1) */
419 len = strnlen(nt->np.dev_name, IFNAMSIZ);
420 if (nt->np.dev_name[len - 1] == '\n')
421 nt->np.dev_name[len - 1] = '\0';
423 mutex_unlock(&dynamic_netconsole_mutex);
424 return strnlen(buf, count);
427 static ssize_t local_port_store(struct config_item *item, const char *buf,
430 struct netconsole_target *nt = to_target(item);
433 mutex_lock(&dynamic_netconsole_mutex);
435 pr_err("target (%s) is enabled, disable to update parameters\n",
436 config_item_name(&nt->item));
440 rv = kstrtou16(buf, 10, &nt->np.local_port);
443 mutex_unlock(&dynamic_netconsole_mutex);
444 return strnlen(buf, count);
446 mutex_unlock(&dynamic_netconsole_mutex);
450 static ssize_t remote_port_store(struct config_item *item,
451 const char *buf, size_t count)
453 struct netconsole_target *nt = to_target(item);
456 mutex_lock(&dynamic_netconsole_mutex);
458 pr_err("target (%s) is enabled, disable to update parameters\n",
459 config_item_name(&nt->item));
463 rv = kstrtou16(buf, 10, &nt->np.remote_port);
466 mutex_unlock(&dynamic_netconsole_mutex);
467 return strnlen(buf, count);
469 mutex_unlock(&dynamic_netconsole_mutex);
473 static ssize_t local_ip_store(struct config_item *item, const char *buf,
476 struct netconsole_target *nt = to_target(item);
478 mutex_lock(&dynamic_netconsole_mutex);
480 pr_err("target (%s) is enabled, disable to update parameters\n",
481 config_item_name(&nt->item));
485 if (strnchr(buf, count, ':')) {
487 if (in6_pton(buf, count, nt->np.local_ip.in6.s6_addr, -1, &end) > 0) {
488 if (*end && *end != '\n') {
489 pr_err("invalid IPv6 address at: <%c>\n", *end);
497 nt->np.local_ip.ip = in_aton(buf);
502 mutex_unlock(&dynamic_netconsole_mutex);
503 return strnlen(buf, count);
505 mutex_unlock(&dynamic_netconsole_mutex);
509 static ssize_t remote_ip_store(struct config_item *item, const char *buf,
512 struct netconsole_target *nt = to_target(item);
514 mutex_lock(&dynamic_netconsole_mutex);
516 pr_err("target (%s) is enabled, disable to update parameters\n",
517 config_item_name(&nt->item));
521 if (strnchr(buf, count, ':')) {
523 if (in6_pton(buf, count, nt->np.remote_ip.in6.s6_addr, -1, &end) > 0) {
524 if (*end && *end != '\n') {
525 pr_err("invalid IPv6 address at: <%c>\n", *end);
533 nt->np.remote_ip.ip = in_aton(buf);
538 mutex_unlock(&dynamic_netconsole_mutex);
539 return strnlen(buf, count);
541 mutex_unlock(&dynamic_netconsole_mutex);
545 static ssize_t remote_mac_store(struct config_item *item, const char *buf,
548 struct netconsole_target *nt = to_target(item);
549 u8 remote_mac[ETH_ALEN];
551 mutex_lock(&dynamic_netconsole_mutex);
553 pr_err("target (%s) is enabled, disable to update parameters\n",
554 config_item_name(&nt->item));
558 if (!mac_pton(buf, remote_mac))
560 if (buf[3 * ETH_ALEN - 1] && buf[3 * ETH_ALEN - 1] != '\n')
562 memcpy(nt->np.remote_mac, remote_mac, ETH_ALEN);
564 mutex_unlock(&dynamic_netconsole_mutex);
565 return strnlen(buf, count);
567 mutex_unlock(&dynamic_netconsole_mutex);
571 CONFIGFS_ATTR(, enabled);
572 CONFIGFS_ATTR(, extended);
573 CONFIGFS_ATTR(, dev_name);
574 CONFIGFS_ATTR(, local_port);
575 CONFIGFS_ATTR(, remote_port);
576 CONFIGFS_ATTR(, local_ip);
577 CONFIGFS_ATTR(, remote_ip);
578 CONFIGFS_ATTR_RO(, local_mac);
579 CONFIGFS_ATTR(, remote_mac);
581 static struct configfs_attribute *netconsole_target_attrs[] = {
595 * Item operations and type for netconsole_target.
598 static void netconsole_target_release(struct config_item *item)
600 kfree(to_target(item));
603 static struct configfs_item_operations netconsole_target_item_ops = {
604 .release = netconsole_target_release,
607 static const struct config_item_type netconsole_target_type = {
608 .ct_attrs = netconsole_target_attrs,
609 .ct_item_ops = &netconsole_target_item_ops,
610 .ct_owner = THIS_MODULE,
614 * Group operations and type for netconsole_subsys.
617 static struct config_item *make_netconsole_target(struct config_group *group,
621 struct netconsole_target *nt;
624 * Allocate and initialize with defaults.
625 * Target is disabled at creation (!enabled).
627 nt = kzalloc(sizeof(*nt), GFP_KERNEL);
629 return ERR_PTR(-ENOMEM);
631 nt->np.name = "netconsole";
632 strlcpy(nt->np.dev_name, "eth0", IFNAMSIZ);
633 nt->np.local_port = 6665;
634 nt->np.remote_port = 6666;
635 eth_broadcast_addr(nt->np.remote_mac);
637 /* Initialize the config_item member */
638 config_item_init_type_name(&nt->item, name, &netconsole_target_type);
640 /* Adding, but it is disabled */
641 spin_lock_irqsave(&target_list_lock, flags);
642 list_add(&nt->list, &target_list);
643 spin_unlock_irqrestore(&target_list_lock, flags);
648 static void drop_netconsole_target(struct config_group *group,
649 struct config_item *item)
652 struct netconsole_target *nt = to_target(item);
654 spin_lock_irqsave(&target_list_lock, flags);
656 spin_unlock_irqrestore(&target_list_lock, flags);
659 * The target may have never been enabled, or was manually disabled
660 * before being removed so netpoll may have already been cleaned up.
663 netpoll_cleanup(&nt->np);
665 config_item_put(&nt->item);
668 static struct configfs_group_operations netconsole_subsys_group_ops = {
669 .make_item = make_netconsole_target,
670 .drop_item = drop_netconsole_target,
673 static const struct config_item_type netconsole_subsys_type = {
674 .ct_group_ops = &netconsole_subsys_group_ops,
675 .ct_owner = THIS_MODULE,
678 /* The netconsole configfs subsystem */
679 static struct configfs_subsystem netconsole_subsys = {
682 .ci_namebuf = "netconsole",
683 .ci_type = &netconsole_subsys_type,
688 #endif /* CONFIG_NETCONSOLE_DYNAMIC */
690 /* Handle network interface device notifications */
691 static int netconsole_netdev_event(struct notifier_block *this,
692 unsigned long event, void *ptr)
695 struct netconsole_target *nt;
696 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
697 bool stopped = false;
699 if (!(event == NETDEV_CHANGENAME || event == NETDEV_UNREGISTER ||
700 event == NETDEV_RELEASE || event == NETDEV_JOIN))
703 spin_lock_irqsave(&target_list_lock, flags);
705 list_for_each_entry(nt, &target_list, list) {
706 netconsole_target_get(nt);
707 if (nt->np.dev == dev) {
709 case NETDEV_CHANGENAME:
710 strlcpy(nt->np.dev_name, dev->name, IFNAMSIZ);
714 case NETDEV_UNREGISTER:
715 /* rtnl_lock already held
716 * we might sleep in __netpoll_cleanup()
718 spin_unlock_irqrestore(&target_list_lock, flags);
720 __netpoll_cleanup(&nt->np);
722 spin_lock_irqsave(&target_list_lock, flags);
727 netconsole_target_put(nt);
731 netconsole_target_put(nt);
733 spin_unlock_irqrestore(&target_list_lock, flags);
735 const char *msg = "had an event";
737 case NETDEV_UNREGISTER:
738 msg = "unregistered";
741 msg = "released slaves";
744 msg = "is joining a master device";
747 pr_info("network logging stopped on interface %s as it %s\n",
755 static struct notifier_block netconsole_netdev_notifier = {
756 .notifier_call = netconsole_netdev_event,
760 * send_ext_msg_udp - send extended log message to target
761 * @nt: target to send message to
762 * @msg: extended log message to send
763 * @msg_len: length of message
765 * Transfer extended log @msg to @nt. If @msg is longer than
766 * MAX_PRINT_CHUNK, it'll be split and transmitted in multiple chunks with
767 * ncfrag header field added to identify them.
769 static void send_ext_msg_udp(struct netconsole_target *nt, const char *msg,
772 static char buf[MAX_PRINT_CHUNK]; /* protected by target_list_lock */
773 const char *header, *body;
775 int header_len, body_len;
777 if (msg_len <= MAX_PRINT_CHUNK) {
778 netpoll_send_udp(&nt->np, msg, msg_len);
782 /* need to insert extra header fields, detect header and body */
784 body = memchr(msg, ';', msg_len);
785 if (WARN_ON_ONCE(!body))
788 header_len = body - header;
789 body_len = msg_len - header_len - 1;
793 * Transfer multiple chunks with the following extra header.
794 * "ncfrag=<byte-offset>/<total-bytes>"
796 memcpy(buf, header, header_len);
798 while (offset < body_len) {
799 int this_header = header_len;
802 this_header += scnprintf(buf + this_header,
803 sizeof(buf) - this_header,
804 ",ncfrag=%d/%d;", offset, body_len);
806 this_chunk = min(body_len - offset,
807 MAX_PRINT_CHUNK - this_header);
808 if (WARN_ON_ONCE(this_chunk <= 0))
811 memcpy(buf + this_header, body + offset, this_chunk);
813 netpoll_send_udp(&nt->np, buf, this_header + this_chunk);
815 offset += this_chunk;
819 static void write_ext_msg(struct console *con, const char *msg,
822 struct netconsole_target *nt;
825 if ((oops_only && !oops_in_progress) || list_empty(&target_list))
828 spin_lock_irqsave(&target_list_lock, flags);
829 list_for_each_entry(nt, &target_list, list)
830 if (nt->extended && nt->enabled && netif_running(nt->np.dev))
831 send_ext_msg_udp(nt, msg, len);
832 spin_unlock_irqrestore(&target_list_lock, flags);
835 static void write_msg(struct console *con, const char *msg, unsigned int len)
839 struct netconsole_target *nt;
842 if (oops_only && !oops_in_progress)
844 /* Avoid taking lock and disabling interrupts unnecessarily */
845 if (list_empty(&target_list))
848 spin_lock_irqsave(&target_list_lock, flags);
849 list_for_each_entry(nt, &target_list, list) {
850 if (!nt->extended && nt->enabled && netif_running(nt->np.dev)) {
852 * We nest this inside the for-each-target loop above
853 * so that we're able to get as much logging out to
854 * at least one target if we die inside here, instead
855 * of unnecessarily keeping all targets in lock-step.
858 for (left = len; left;) {
859 frag = min(left, MAX_PRINT_CHUNK);
860 netpoll_send_udp(&nt->np, tmp, frag);
866 spin_unlock_irqrestore(&target_list_lock, flags);
869 static struct console netconsole_ext = {
870 .name = "netcon_ext",
871 .flags = CON_EXTENDED, /* starts disabled, registered on first use */
872 .write = write_ext_msg,
875 static struct console netconsole = {
877 .flags = CON_ENABLED,
881 static int __init init_netconsole(void)
884 struct netconsole_target *nt, *tmp;
887 char *input = config;
889 if (strnlen(input, MAX_PARAM_LENGTH)) {
890 while ((target_config = strsep(&input, ";"))) {
891 nt = alloc_param_target(target_config);
896 /* Dump existing printks when we register */
898 netconsole_ext.flags |= CON_PRINTBUFFER |
901 netconsole.flags |= CON_PRINTBUFFER;
903 spin_lock_irqsave(&target_list_lock, flags);
904 list_add(&nt->list, &target_list);
905 spin_unlock_irqrestore(&target_list_lock, flags);
909 err = register_netdevice_notifier(&netconsole_netdev_notifier);
913 err = dynamic_netconsole_init();
917 if (netconsole_ext.flags & CON_ENABLED)
918 register_console(&netconsole_ext);
919 register_console(&netconsole);
920 pr_info("network logging started\n");
925 unregister_netdevice_notifier(&netconsole_netdev_notifier);
928 pr_err("cleaning up\n");
931 * Remove all targets and destroy them (only targets created
932 * from the boot/module option exist here). Skipping the list
933 * lock is safe here, and netpoll_cleanup() will sleep.
935 list_for_each_entry_safe(nt, tmp, &target_list, list) {
937 free_param_target(nt);
943 static void __exit cleanup_netconsole(void)
945 struct netconsole_target *nt, *tmp;
947 unregister_console(&netconsole_ext);
948 unregister_console(&netconsole);
949 dynamic_netconsole_exit();
950 unregister_netdevice_notifier(&netconsole_netdev_notifier);
953 * Targets created via configfs pin references on our module
954 * and would first be rmdir(2)'ed from userspace. We reach
955 * here only when they are already destroyed, and only those
956 * created from the boot/module option are left, so remove and
957 * destroy them. Skipping the list lock is safe here, and
958 * netpoll_cleanup() will sleep.
960 list_for_each_entry_safe(nt, tmp, &target_list, list) {
962 free_param_target(nt);
967 * Use late_initcall to ensure netconsole is
968 * initialized after network device driver if built-in.
970 * late_initcall() and module_init() are identical if built as module.
972 late_initcall(init_netconsole);
973 module_exit(cleanup_netconsole);