Commit c62c0a17 authored by Breno Leitao's avatar Breno Leitao Committed by Paolo Abeni
Browse files

netconsole: Append kernel version to message 



Create a new netconsole runtime option that prepends the kernel version in
the netconsole message. This is useful to map kernel messages to kernel
version in a simple way, i.e., without checking somewhere which kernel
version the host that sent the message is using.

If this option is selected, then the "<release>," is prepended before the
netconsole message. This is an example of a netconsole output, with
release feature enabled:

	6.4.0-01762-ga1ba2ffe946e;12,426,112883998,-;this is a test

Cc: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: default avatarBreno Leitao <leitao@debian.org>
Link: https://lore.kernel.org/r/20230714111330.3069605-1-leitao@debian.org


Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent a7f6eb19

Documentation/networking/netconsole.rst

+10 −1
Original line number Diff line number Diff line
@@ -13,6 +13,8 @@ IPv6 support by Cong Wang <xiyou.wangcong@gmail.com>, Jan 1 2013 


Extended console support by Tejun Heo <tj@kernel.org>, May 1 2015



Release prepend support by Breno Leitao <leitao@debian.org>, Jul 7 2023



Please send bug reports to Matt Mackall <mpm@selenic.com>

Satyam Sharma <satyam.sharma@gmail.com>, and Cong Wang <xiyou.wangcong@gmail.com>
@@ -34,10 +36,11 @@ Sender and receiver configuration: 
It takes a string configuration parameter "netconsole" in the

following format::



 netconsole=[+][src-port]@[src-ip]/[<dev>],[tgt-port]@<tgt-ip>/[tgt-macaddr]

 netconsole=[+][r][src-port]@[src-ip]/[<dev>],[tgt-port]@<tgt-ip>/[tgt-macaddr]



   where

	+             if present, enable extended console support

	r             if present, prepend kernel version (release) to the message

	src-port      source for UDP packets (defaults to 6665)

	src-ip        source IP to use (interface address)

	dev           network interface (eth0)
@@ -125,6 +128,7 @@ The interface exposes these parameters of a netconsole target to userspace: 
	==============  =================================       ============

	enabled		Is this target currently enabled?	(read-write)

	extended	Extended mode enabled			(read-write)

	release		Prepend kernel release to message	(read-write)

	dev_name	Local network interface name		(read-write)

	local_port	Source UDP port to use			(read-write)

	remote_port	Remote agent's UDP port			(read-write)
@@ -165,6 +169,11 @@ following format which is the same as /dev/kmsg:: 


 <level>,<sequnum>,<timestamp>,<contflag>;<message text>



If 'r' (release) feature is enabled, the kernel release version is

prepended to the start of the message. Example::



 6.4.0,6,444,501151268,-;netconsole: network logging started



Non printable characters in <message text> are escaped using "\xff"

notation. If the message contains optional dictionary, verbatim

newline is used as the delimiter.

drivers/net/netconsole.c

+78 −3
Original line number Diff line number Diff line
@@ -36,6 +36,7 @@ 
#include <linux/inet.h>

#include <linux/configfs.h>

#include <linux/etherdevice.h>

#include <linux/utsname.h>



MODULE_AUTHOR("Maintainer: Matt Mackall <mpm@selenic.com>");

MODULE_DESCRIPTION("Console driver for network interfaces");
@@ -84,6 +85,8 @@ static struct console netconsole_ext; 
 *		Also, other parameters of a target may be modified at

 *		runtime only when it is disabled (enabled == 0).

 * @extended:	Denotes whether console is extended or not.

 * @release:	Denotes whether kernel release version should be prepended

 *		to the message. Depends on extended console.

 * @np:		The netpoll structure for this target.

 *		Contains the other userspace visible parameters:

 *		dev_name	(read-write)
@@ -101,6 +104,7 @@ struct netconsole_target { 
#endif

	bool			enabled;

	bool			extended;

	bool			release;

	struct netpoll		np;

};
@@ -188,6 +192,15 @@ static struct netconsole_target *alloc_param_target(char *target_config) 
		target_config++;

	}



	if (*target_config == 'r') {

		if (!nt->extended) {

			pr_err("Netconsole configuration error. Release feature requires extended log message");

			goto fail;

		}

		nt->release = true;

		target_config++;

	}



	/* Parse parameters and setup netpoll */

	err = netpoll_parse_options(&nt->np, target_config);

	if (err)
@@ -222,6 +235,7 @@ static void free_param_target(struct netconsole_target *nt) 
 *				|

 *				<target>/

 *				|	enabled

 *				|	release

 *				|	dev_name

 *				|	local_port

 *				|	remote_port
@@ -254,6 +268,11 @@ static ssize_t extended_show(struct config_item *item, char *buf) 
	return snprintf(buf, PAGE_SIZE, "%d\n", to_target(item)->extended);

}



static ssize_t release_show(struct config_item *item, char *buf)

{

	return snprintf(buf, PAGE_SIZE, "%d\n", to_target(item)->release);

}



static ssize_t dev_name_show(struct config_item *item, char *buf)

{

	return snprintf(buf, PAGE_SIZE, "%s\n", to_target(item)->np.dev_name);
@@ -332,6 +351,11 @@ static ssize_t enabled_store(struct config_item *item, 
	}



	if (enabled) {	/* true */

		if (nt->release && !nt->extended) {

			pr_err("Not enabling netconsole. Release feature requires extended log message");

			goto out_unlock;

		}



		if (nt->extended && !console_is_registered(&netconsole_ext))

			register_console(&netconsole_ext);
@@ -366,6 +390,38 @@ static ssize_t enabled_store(struct config_item *item, 
	return err;

}



static ssize_t release_store(struct config_item *item, const char *buf,

			     size_t count)

{

	struct netconsole_target *nt = to_target(item);

	int release;

	int err;



	mutex_lock(&dynamic_netconsole_mutex);

	if (nt->enabled) {

		pr_err("target (%s) is enabled, disable to update parameters\n",

		       config_item_name(&nt->item));

		err = -EINVAL;

		goto out_unlock;

	}



	err = kstrtoint(buf, 10, &release);

	if (err < 0)

		goto out_unlock;

	if (release < 0 || release > 1) {

		err = -EINVAL;

		goto out_unlock;

	}



	nt->release = release;



	mutex_unlock(&dynamic_netconsole_mutex);

	return strnlen(buf, count);

out_unlock:

	mutex_unlock(&dynamic_netconsole_mutex);

	return err;

}



static ssize_t extended_store(struct config_item *item, const char *buf,

		size_t count)

{
@@ -576,10 +632,12 @@ CONFIGFS_ATTR(, local_ip); 
CONFIGFS_ATTR(, remote_ip);

CONFIGFS_ATTR_RO(, local_mac);

CONFIGFS_ATTR(, remote_mac);

CONFIGFS_ATTR(, release);



static struct configfs_attribute *netconsole_target_attrs[] = {

	&attr_enabled,

	&attr_extended,

	&attr_release,

	&attr_dev_name,

	&attr_local_port,

	&attr_remote_port,
@@ -772,9 +830,23 @@ static void send_ext_msg_udp(struct netconsole_target *nt, const char *msg, 
	const char *header, *body;

	int offset = 0;

	int header_len, body_len;

	const char *msg_ready = msg;

	const char *release;

	int release_len = 0;



	if (msg_len <= MAX_PRINT_CHUNK) {

		netpoll_send_udp(&nt->np, msg, msg_len);

	if (nt->release) {

		release = init_utsname()->release;

		release_len = strlen(release) + 1;

	}



	if (msg_len + release_len <= MAX_PRINT_CHUNK) {

		/* No fragmentation needed */

		if (nt->release) {

			scnprintf(buf, MAX_PRINT_CHUNK, "%s,%s", release, msg);

			msg_len += release_len;

			msg_ready = buf;

		}

		netpoll_send_udp(&nt->np, msg_ready, msg_len);

		return;

	}
@@ -792,7 +864,10 @@ static void send_ext_msg_udp(struct netconsole_target *nt, const char *msg, 
	 * Transfer multiple chunks with the following extra header.

	 * "ncfrag=<byte-offset>/<total-bytes>"

	 */

	memcpy(buf, header, header_len);

	if (nt->release)

		scnprintf(buf, MAX_PRINT_CHUNK, "%s,", release);

	memcpy(buf + release_len, header, header_len);

	header_len += release_len;



	while (offset < body_len) {

		int this_header = header_len;