Patch for problem described in PPW-60 cthulhu: random: container is not properly started

packages/utils/lxc/patches/040-LXC-syslog-patch.patch

@@ -0,0 +1,117 @@
+From 06fc7f827ad90ca567f2df5429c6c903aec32acf Mon Sep 17 00:00:00 2001
+From: Nabil BIZID <nabil.bizid@softathome.com>
+Date: Tue, 24 Sep 2024 20:02:50 +0200
+Subject: [PATCH] log: fix random container syslog logging or startup failures
+ on musl libc
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+During the setup/start of an LXC container, the LXC creates multiple
+forks of the main process for different purposes. Each fork inherits the
+file descriptors (fds) of the parent process.  However, each child
+process closes the list of inherited file descriptors that it does not
+need, as these fds are irrelevant to the child process.  This cleanup of
+fds occurs in the lxc_check_inherited().
+
+If logging to syslog is enabled, the socket used for logging to the
+syslog daemon (through the syslog device: /dev/log) is also closed,
+invalidating the corresponding file descriptor.  LXC uses the standard
+syslog() function to log messages to the syslog daemon.
+
+OpenWrt uses the musl library as its standard C library, and the musl
+implementation of syslog() is not resilient to the invalidation of
+previously obtained file descriptors (through calls to syslog() or
+openlog()).  In contrast, the syslog() implementation in glibc and other
+C libraries is more robust: if an invalid file descriptor is detected,
+those libraries will automatically reopen the connection to the syslog
+device, obtaining a new, valid file descriptor to continue logging.
+
+musl libc, on the other hand, only detects connection loss to the syslog
+device and does not handle cases where the file descriptor itself
+becomes invalid.  This limitation can be seen in the musl implementation
+here: https://git.musl-libc.org/cgit/musl/tree/src/misc/syslog.c#n80.
+musl libc behavior will not change following the answer maintainers:
+https://www.openwall.com/lists/musl/2024/09/26/2
+
+As a result of this behavior in musl, when an LXC child process tries to
+log information using syslog(), it continues to use the invalid file
+descriptor (which was closed earlier).  This primarily results in some
+missing logs without functional impacts, when no other socket or file
+opening operation reuses the same file descriptor value. However, if the
+file descriptor is reused by another process or operation, logs may
+erroneously be written to that file or socket and can lead to container
+creation/startup failure.
+
+This commit aims to prevent forked processes from using invalid syslog
+file descriptors, which can lead to issues such as missing logs or, in
+worse cases, random failures in LXC functionality (e.g., when
+synchronization between LXC processes is disrupted).  It also addresses
+musl's lack of resilience when handling invalid file descriptors.
+
+The changes work by caching the syslog connection information at the
+start and reusing it to reopen the syslog connection after child
+processes close all inherited file descriptors.
+
+Fixes: #4485
+Tested-by: Petr Štetiar <petr.stetiar@prplfoundation.org>
+Signed-off-by: Nabil BIZID <nabil.bizid@softathome.com>
+---
+ src/lxc/log.c | 20 ++++++++++++++++++++
+ 1 file changed, 20 insertions(+)
+
+diff --git a/src/lxc/log.c b/src/lxc/log.c
+index cdd11ff1c..08c9c959c 100644
+--- a/src/lxc/log.c
++++ b/src/lxc/log.c
+@@ -51,6 +51,9 @@ static char log_prefix[LXC_LOG_PREFIX_SIZE] = "lxc";
+ static char *log_fname = NULL;
+ static char *log_vmname = NULL;
+ 
++static bool syslog_initialized = false;
++static int syslog_facility = -EINVAL;
++
+ lxc_log_define(log, lxc);
+ 
+ static int lxc_log_priority_to_syslog(int priority)
+@@ -746,6 +749,8 @@ int lxc_log_syslog(int facility)
+ 	struct lxc_log_appender *appender;
+ 
+ 	openlog(log_prefix, LOG_PID, facility);
++	syslog_initialized = true;
++	syslog_facility = facility;
+ 	if (!lxc_log_category_lxc.appender) {
+ 		lxc_log_category_lxc.appender = &log_appender_syslog;
+ 		return 0;
+@@ -768,13 +773,28 @@ int lxc_log_syslog(int facility)
+ 	return 0;
+ }
+ 
++static void lxc_reconnect_syslog(void)
++{
++	if (syslog_initialized)
++		openlog(log_prefix, LOG_PID, syslog_facility);
++}
++
++static void lxc_force_close_syslog(void)
++{
++	if (syslog_initialized)
++		closelog();
++}
++
++
+ void lxc_log_syslog_enable(void)
+ {
++	lxc_reconnect_syslog();
+ 	wants_syslog = true;
+ }
+ 
+ void lxc_log_syslog_disable(void)
+ {
++	lxc_force_close_syslog();
+ 	wants_syslog = false;
+ }
+ 
+-- 
+2.34.1
+