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 strscpy(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 * @extended: Denotes whether console is extended or not.
87 * @np: The netpoll structure for this target.
88 * Contains the other userspace visible parameters:
89 * dev_name (read-write)
90 * local_port (read-write)
91 * remote_port (read-write)
92 * local_ip (read-write)
93 * remote_ip (read-write)
94 * local_mac (read-only)
95 * remote_mac (read-write)
97 struct netconsole_target {
98 struct list_head list;
99 #ifdef CONFIG_NETCONSOLE_DYNAMIC
100 struct config_item item;
107 #ifdef CONFIG_NETCONSOLE_DYNAMIC
109 static struct configfs_subsystem netconsole_subsys;
110 static DEFINE_MUTEX(dynamic_netconsole_mutex);
112 static int __init dynamic_netconsole_init(void)
114 config_group_init(&netconsole_subsys.su_group);
115 mutex_init(&netconsole_subsys.su_mutex);
116 return configfs_register_subsystem(&netconsole_subsys);
119 static void __exit dynamic_netconsole_exit(void)
121 configfs_unregister_subsystem(&netconsole_subsys);
125 * Targets that were created by parsing the boot/module option string
126 * do not exist in the configfs hierarchy (and have NULL names) and will
127 * never go away, so make these a no-op for them.
129 static void netconsole_target_get(struct netconsole_target *nt)
131 if (config_item_name(&nt->item))
132 config_item_get(&nt->item);
135 static void netconsole_target_put(struct netconsole_target *nt)
137 if (config_item_name(&nt->item))
138 config_item_put(&nt->item);
141 #else /* !CONFIG_NETCONSOLE_DYNAMIC */
143 static int __init dynamic_netconsole_init(void)
148 static void __exit dynamic_netconsole_exit(void)
153 * No danger of targets going away from under us when dynamic
154 * reconfigurability is off.
156 static void netconsole_target_get(struct netconsole_target *nt)
160 static void netconsole_target_put(struct netconsole_target *nt)
164 #endif /* CONFIG_NETCONSOLE_DYNAMIC */
166 /* Allocate new target (from boot/module param) and setup netpoll for it */
167 static struct netconsole_target *alloc_param_target(char *target_config)
170 struct netconsole_target *nt;
173 * Allocate and initialize with defaults.
174 * Note that these targets get their config_item fields zeroed-out.
176 nt = kzalloc(sizeof(*nt), GFP_KERNEL);
180 nt->np.name = "netconsole";
181 strscpy(nt->np.dev_name, "eth0", IFNAMSIZ);
182 nt->np.local_port = 6665;
183 nt->np.remote_port = 6666;
184 eth_broadcast_addr(nt->np.remote_mac);
186 if (*target_config == '+') {
191 /* Parse parameters and setup netpoll */
192 err = netpoll_parse_options(&nt->np, target_config);
196 err = netpoll_setup(&nt->np);
209 /* Cleanup netpoll for given target (from boot/module param) and free it */
210 static void free_param_target(struct netconsole_target *nt)
212 netpoll_cleanup(&nt->np);
216 #ifdef CONFIG_NETCONSOLE_DYNAMIC
219 * Our subsystem hierarchy is:
221 * /sys/kernel/config/netconsole/
236 static struct netconsole_target *to_target(struct config_item *item)
239 container_of(item, struct netconsole_target, item) :
244 * Attribute operations for netconsole_target.
247 static ssize_t enabled_show(struct config_item *item, char *buf)
249 return snprintf(buf, PAGE_SIZE, "%d\n", to_target(item)->enabled);
252 static ssize_t extended_show(struct config_item *item, char *buf)
254 return snprintf(buf, PAGE_SIZE, "%d\n", to_target(item)->extended);
257 static ssize_t dev_name_show(struct config_item *item, char *buf)
259 return snprintf(buf, PAGE_SIZE, "%s\n", to_target(item)->np.dev_name);
262 static ssize_t local_port_show(struct config_item *item, char *buf)
264 return snprintf(buf, PAGE_SIZE, "%d\n", to_target(item)->np.local_port);
267 static ssize_t remote_port_show(struct config_item *item, char *buf)
269 return snprintf(buf, PAGE_SIZE, "%d\n", to_target(item)->np.remote_port);
272 static ssize_t local_ip_show(struct config_item *item, char *buf)
274 struct netconsole_target *nt = to_target(item);
277 return snprintf(buf, PAGE_SIZE, "%pI6c\n", &nt->np.local_ip.in6);
279 return snprintf(buf, PAGE_SIZE, "%pI4\n", &nt->np.local_ip);
282 static ssize_t remote_ip_show(struct config_item *item, char *buf)
284 struct netconsole_target *nt = to_target(item);
287 return snprintf(buf, PAGE_SIZE, "%pI6c\n", &nt->np.remote_ip.in6);
289 return snprintf(buf, PAGE_SIZE, "%pI4\n", &nt->np.remote_ip);
292 static ssize_t local_mac_show(struct config_item *item, char *buf)
294 struct net_device *dev = to_target(item)->np.dev;
295 static const u8 bcast[ETH_ALEN] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
297 return snprintf(buf, PAGE_SIZE, "%pM\n", dev ? dev->dev_addr : bcast);
300 static ssize_t remote_mac_show(struct config_item *item, char *buf)
302 return snprintf(buf, PAGE_SIZE, "%pM\n", to_target(item)->np.remote_mac);
306 * This one is special -- targets created through the configfs interface
307 * are not enabled (and the corresponding netpoll activated) by default.
308 * The user is expected to set the desired parameters first (which
309 * would enable him to dynamically add new netpoll targets for new
310 * network interfaces as and when they come up).
312 static ssize_t enabled_store(struct config_item *item,
313 const char *buf, size_t count)
315 struct netconsole_target *nt = to_target(item);
320 mutex_lock(&dynamic_netconsole_mutex);
321 err = kstrtoint(buf, 10, &enabled);
326 if (enabled < 0 || enabled > 1)
328 if ((bool)enabled == nt->enabled) {
329 pr_info("network logging has already %s\n",
330 nt->enabled ? "started" : "stopped");
334 if (enabled) { /* true */
335 if (nt->extended && !console_is_registered(&netconsole_ext))
336 register_console(&netconsole_ext);
339 * Skip netpoll_parse_options() -- all the attributes are
340 * already configured via configfs. Just print them out.
342 netpoll_print_options(&nt->np);
344 err = netpoll_setup(&nt->np);
348 pr_info("network logging started\n");
350 /* We need to disable the netconsole before cleaning it up
351 * otherwise we might end up in write_msg() with
352 * nt->np.dev == NULL and nt->enabled == true
354 spin_lock_irqsave(&target_list_lock, flags);
356 spin_unlock_irqrestore(&target_list_lock, flags);
357 netpoll_cleanup(&nt->np);
360 nt->enabled = enabled;
362 mutex_unlock(&dynamic_netconsole_mutex);
363 return strnlen(buf, count);
365 mutex_unlock(&dynamic_netconsole_mutex);
369 static ssize_t extended_store(struct config_item *item, const char *buf,
372 struct netconsole_target *nt = to_target(item);
376 mutex_lock(&dynamic_netconsole_mutex);
378 pr_err("target (%s) is enabled, disable to update parameters\n",
379 config_item_name(&nt->item));
384 err = kstrtoint(buf, 10, &extended);
387 if (extended < 0 || extended > 1) {
392 nt->extended = extended;
394 mutex_unlock(&dynamic_netconsole_mutex);
395 return strnlen(buf, count);
397 mutex_unlock(&dynamic_netconsole_mutex);
401 static ssize_t dev_name_store(struct config_item *item, const char *buf,
404 struct netconsole_target *nt = to_target(item);
407 mutex_lock(&dynamic_netconsole_mutex);
409 pr_err("target (%s) is enabled, disable to update parameters\n",
410 config_item_name(&nt->item));
411 mutex_unlock(&dynamic_netconsole_mutex);
415 strscpy(nt->np.dev_name, buf, IFNAMSIZ);
417 /* Get rid of possible trailing newline from echo(1) */
418 len = strnlen(nt->np.dev_name, IFNAMSIZ);
419 if (nt->np.dev_name[len - 1] == '\n')
420 nt->np.dev_name[len - 1] = '\0';
422 mutex_unlock(&dynamic_netconsole_mutex);
423 return strnlen(buf, count);
426 static ssize_t local_port_store(struct config_item *item, const char *buf,
429 struct netconsole_target *nt = to_target(item);
432 mutex_lock(&dynamic_netconsole_mutex);
434 pr_err("target (%s) is enabled, disable to update parameters\n",
435 config_item_name(&nt->item));
439 rv = kstrtou16(buf, 10, &nt->np.local_port);
442 mutex_unlock(&dynamic_netconsole_mutex);
443 return strnlen(buf, count);
445 mutex_unlock(&dynamic_netconsole_mutex);
449 static ssize_t remote_port_store(struct config_item *item,
450 const char *buf, size_t count)
452 struct netconsole_target *nt = to_target(item);
455 mutex_lock(&dynamic_netconsole_mutex);
457 pr_err("target (%s) is enabled, disable to update parameters\n",
458 config_item_name(&nt->item));
462 rv = kstrtou16(buf, 10, &nt->np.remote_port);
465 mutex_unlock(&dynamic_netconsole_mutex);
466 return strnlen(buf, count);
468 mutex_unlock(&dynamic_netconsole_mutex);
472 static ssize_t local_ip_store(struct config_item *item, const char *buf,
475 struct netconsole_target *nt = to_target(item);
477 mutex_lock(&dynamic_netconsole_mutex);
479 pr_err("target (%s) is enabled, disable to update parameters\n",
480 config_item_name(&nt->item));
484 if (strnchr(buf, count, ':')) {
486 if (in6_pton(buf, count, nt->np.local_ip.in6.s6_addr, -1, &end) > 0) {
487 if (*end && *end != '\n') {
488 pr_err("invalid IPv6 address at: <%c>\n", *end);
496 nt->np.local_ip.ip = in_aton(buf);
501 mutex_unlock(&dynamic_netconsole_mutex);
502 return strnlen(buf, count);
504 mutex_unlock(&dynamic_netconsole_mutex);
508 static ssize_t remote_ip_store(struct config_item *item, const char *buf,
511 struct netconsole_target *nt = to_target(item);
513 mutex_lock(&dynamic_netconsole_mutex);
515 pr_err("target (%s) is enabled, disable to update parameters\n",
516 config_item_name(&nt->item));
520 if (strnchr(buf, count, ':')) {
522 if (in6_pton(buf, count, nt->np.remote_ip.in6.s6_addr, -1, &end) > 0) {
523 if (*end && *end != '\n') {
524 pr_err("invalid IPv6 address at: <%c>\n", *end);
532 nt->np.remote_ip.ip = in_aton(buf);
537 mutex_unlock(&dynamic_netconsole_mutex);
538 return strnlen(buf, count);
540 mutex_unlock(&dynamic_netconsole_mutex);
544 static ssize_t remote_mac_store(struct config_item *item, const char *buf,
547 struct netconsole_target *nt = to_target(item);
548 u8 remote_mac[ETH_ALEN];
550 mutex_lock(&dynamic_netconsole_mutex);
552 pr_err("target (%s) is enabled, disable to update parameters\n",
553 config_item_name(&nt->item));
557 if (!mac_pton(buf, remote_mac))
559 if (buf[3 * ETH_ALEN - 1] && buf[3 * ETH_ALEN - 1] != '\n')
561 memcpy(nt->np.remote_mac, remote_mac, ETH_ALEN);
563 mutex_unlock(&dynamic_netconsole_mutex);
564 return strnlen(buf, count);
566 mutex_unlock(&dynamic_netconsole_mutex);
570 CONFIGFS_ATTR(, enabled);
571 CONFIGFS_ATTR(, extended);
572 CONFIGFS_ATTR(, dev_name);
573 CONFIGFS_ATTR(, local_port);
574 CONFIGFS_ATTR(, remote_port);
575 CONFIGFS_ATTR(, local_ip);
576 CONFIGFS_ATTR(, remote_ip);
577 CONFIGFS_ATTR_RO(, local_mac);
578 CONFIGFS_ATTR(, remote_mac);
580 static struct configfs_attribute *netconsole_target_attrs[] = {
594 * Item operations and type for netconsole_target.
597 static void netconsole_target_release(struct config_item *item)
599 kfree(to_target(item));
602 static struct configfs_item_operations netconsole_target_item_ops = {
603 .release = netconsole_target_release,
606 static const struct config_item_type netconsole_target_type = {
607 .ct_attrs = netconsole_target_attrs,
608 .ct_item_ops = &netconsole_target_item_ops,
609 .ct_owner = THIS_MODULE,
613 * Group operations and type for netconsole_subsys.
616 static struct config_item *make_netconsole_target(struct config_group *group,
620 struct netconsole_target *nt;
623 * Allocate and initialize with defaults.
624 * Target is disabled at creation (!enabled).
626 nt = kzalloc(sizeof(*nt), GFP_KERNEL);
628 return ERR_PTR(-ENOMEM);
630 nt->np.name = "netconsole";
631 strscpy(nt->np.dev_name, "eth0", IFNAMSIZ);
632 nt->np.local_port = 6665;
633 nt->np.remote_port = 6666;
634 eth_broadcast_addr(nt->np.remote_mac);
636 /* Initialize the config_item member */
637 config_item_init_type_name(&nt->item, name, &netconsole_target_type);
639 /* Adding, but it is disabled */
640 spin_lock_irqsave(&target_list_lock, flags);
641 list_add(&nt->list, &target_list);
642 spin_unlock_irqrestore(&target_list_lock, flags);
647 static void drop_netconsole_target(struct config_group *group,
648 struct config_item *item)
651 struct netconsole_target *nt = to_target(item);
653 spin_lock_irqsave(&target_list_lock, flags);
655 spin_unlock_irqrestore(&target_list_lock, flags);
658 * The target may have never been enabled, or was manually disabled
659 * before being removed so netpoll may have already been cleaned up.
662 netpoll_cleanup(&nt->np);
664 config_item_put(&nt->item);
667 static struct configfs_group_operations netconsole_subsys_group_ops = {
668 .make_item = make_netconsole_target,
669 .drop_item = drop_netconsole_target,
672 static const struct config_item_type netconsole_subsys_type = {
673 .ct_group_ops = &netconsole_subsys_group_ops,
674 .ct_owner = THIS_MODULE,
677 /* The netconsole configfs subsystem */
678 static struct configfs_subsystem netconsole_subsys = {
681 .ci_namebuf = "netconsole",
682 .ci_type = &netconsole_subsys_type,
687 #endif /* CONFIG_NETCONSOLE_DYNAMIC */
689 /* Handle network interface device notifications */
690 static int netconsole_netdev_event(struct notifier_block *this,
691 unsigned long event, void *ptr)
694 struct netconsole_target *nt;
695 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
696 bool stopped = false;
698 if (!(event == NETDEV_CHANGENAME || event == NETDEV_UNREGISTER ||
699 event == NETDEV_RELEASE || event == NETDEV_JOIN))
702 spin_lock_irqsave(&target_list_lock, flags);
704 list_for_each_entry(nt, &target_list, list) {
705 netconsole_target_get(nt);
706 if (nt->np.dev == dev) {
708 case NETDEV_CHANGENAME:
709 strscpy(nt->np.dev_name, dev->name, IFNAMSIZ);
713 case NETDEV_UNREGISTER:
714 /* rtnl_lock already held
715 * we might sleep in __netpoll_cleanup()
717 spin_unlock_irqrestore(&target_list_lock, flags);
719 __netpoll_cleanup(&nt->np);
721 spin_lock_irqsave(&target_list_lock, flags);
722 netdev_put(nt->np.dev, &nt->np.dev_tracker);
726 netconsole_target_put(nt);
730 netconsole_target_put(nt);
732 spin_unlock_irqrestore(&target_list_lock, flags);
734 const char *msg = "had an event";
736 case NETDEV_UNREGISTER:
737 msg = "unregistered";
740 msg = "released slaves";
743 msg = "is joining a master device";
746 pr_info("network logging stopped on interface %s as it %s\n",
754 static struct notifier_block netconsole_netdev_notifier = {
755 .notifier_call = netconsole_netdev_event,
759 * send_ext_msg_udp - send extended log message to target
760 * @nt: target to send message to
761 * @msg: extended log message to send
762 * @msg_len: length of message
764 * Transfer extended log @msg to @nt. If @msg is longer than
765 * MAX_PRINT_CHUNK, it'll be split and transmitted in multiple chunks with
766 * ncfrag header field added to identify them.
768 static void send_ext_msg_udp(struct netconsole_target *nt, const char *msg,
771 static char buf[MAX_PRINT_CHUNK]; /* protected by target_list_lock */
772 const char *header, *body;
774 int header_len, body_len;
776 if (msg_len <= MAX_PRINT_CHUNK) {
777 netpoll_send_udp(&nt->np, msg, msg_len);
781 /* need to insert extra header fields, detect header and body */
783 body = memchr(msg, ';', msg_len);
784 if (WARN_ON_ONCE(!body))
787 header_len = body - header;
788 body_len = msg_len - header_len - 1;
792 * Transfer multiple chunks with the following extra header.
793 * "ncfrag=<byte-offset>/<total-bytes>"
795 memcpy(buf, header, header_len);
797 while (offset < body_len) {
798 int this_header = header_len;
801 this_header += scnprintf(buf + this_header,
802 sizeof(buf) - this_header,
803 ",ncfrag=%d/%d;", offset, body_len);
805 this_chunk = min(body_len - offset,
806 MAX_PRINT_CHUNK - this_header);
807 if (WARN_ON_ONCE(this_chunk <= 0))
810 memcpy(buf + this_header, body + offset, this_chunk);
812 netpoll_send_udp(&nt->np, buf, this_header + this_chunk);
814 offset += this_chunk;
818 static void write_ext_msg(struct console *con, const char *msg,
821 struct netconsole_target *nt;
824 if ((oops_only && !oops_in_progress) || list_empty(&target_list))
827 spin_lock_irqsave(&target_list_lock, flags);
828 list_for_each_entry(nt, &target_list, list)
829 if (nt->extended && nt->enabled && netif_running(nt->np.dev))
830 send_ext_msg_udp(nt, msg, len);
831 spin_unlock_irqrestore(&target_list_lock, flags);
834 static void write_msg(struct console *con, const char *msg, unsigned int len)
838 struct netconsole_target *nt;
841 if (oops_only && !oops_in_progress)
843 /* Avoid taking lock and disabling interrupts unnecessarily */
844 if (list_empty(&target_list))
847 spin_lock_irqsave(&target_list_lock, flags);
848 list_for_each_entry(nt, &target_list, list) {
849 if (!nt->extended && nt->enabled && netif_running(nt->np.dev)) {
851 * We nest this inside the for-each-target loop above
852 * so that we're able to get as much logging out to
853 * at least one target if we die inside here, instead
854 * of unnecessarily keeping all targets in lock-step.
857 for (left = len; left;) {
858 frag = min(left, MAX_PRINT_CHUNK);
859 netpoll_send_udp(&nt->np, tmp, frag);
865 spin_unlock_irqrestore(&target_list_lock, flags);
868 static struct console netconsole_ext = {
869 .name = "netcon_ext",
870 .flags = CON_ENABLED | CON_EXTENDED,
871 .write = write_ext_msg,
874 static struct console netconsole = {
876 .flags = CON_ENABLED,
880 static int __init init_netconsole(void)
883 struct netconsole_target *nt, *tmp;
884 bool extended = false;
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 */
899 netconsole_ext.flags |= CON_PRINTBUFFER;
901 netconsole.flags |= CON_PRINTBUFFER;
904 spin_lock_irqsave(&target_list_lock, flags);
905 list_add(&nt->list, &target_list);
906 spin_unlock_irqrestore(&target_list_lock, flags);
910 err = register_netdevice_notifier(&netconsole_netdev_notifier);
914 err = dynamic_netconsole_init();
919 register_console(&netconsole_ext);
920 register_console(&netconsole);
921 pr_info("network logging started\n");
926 unregister_netdevice_notifier(&netconsole_netdev_notifier);
929 pr_err("cleaning up\n");
932 * Remove all targets and destroy them (only targets created
933 * from the boot/module option exist here). Skipping the list
934 * lock is safe here, and netpoll_cleanup() will sleep.
936 list_for_each_entry_safe(nt, tmp, &target_list, list) {
938 free_param_target(nt);
944 static void __exit cleanup_netconsole(void)
946 struct netconsole_target *nt, *tmp;
948 if (console_is_registered(&netconsole_ext))
949 unregister_console(&netconsole_ext);
950 unregister_console(&netconsole);
951 dynamic_netconsole_exit();
952 unregister_netdevice_notifier(&netconsole_netdev_notifier);
955 * Targets created via configfs pin references on our module
956 * and would first be rmdir(2)'ed from userspace. We reach
957 * here only when they are already destroyed, and only those
958 * created from the boot/module option are left, so remove and
959 * destroy them. Skipping the list lock is safe here, and
960 * netpoll_cleanup() will sleep.
962 list_for_each_entry_safe(nt, tmp, &target_list, list) {
964 free_param_target(nt);
969 * Use late_initcall to ensure netconsole is
970 * initialized after network device driver if built-in.
972 * late_initcall() and module_init() are identical if built as module.
974 late_initcall(init_netconsole);
975 module_exit(cleanup_netconsole);