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: Breno Leitao <leitao@debian.org>
Link: https://lore.kernel.org/r/20230714111330.3069605-1-leitao@debian.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/Documentation/networking/netconsole.rst b/Documentation/networking/netconsole.rst
index dd0518e..7a9de05 100644 (file)
--- a/Documentation/networking/netconsole.rst
+++ b/Documentation/networking/netconsole.rst
@@ -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.

diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index 4f4f795..31cbe02 100644 (file)
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -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 @@ out_unlock:
        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 (nt->release) {
+               release = init_utsname()->release;
+               release_len = strlen(release) + 1;
+       }
 
-       if (msg_len <= MAX_PRINT_CHUNK) {
-               netpoll_send_udp(&nt->np, msg, msg_len);
+       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;