From: Yeonggi Kim <[email protected]>
23e5f18b8 ("MEDIUM: sink: change the sink mode type to PR_MODE_SYSLOG")
tagged a sink's forward_px (the internal proxy backing a "ring" section)
with PR_MODE_SYSLOG "for compat checks" purposes, stating no behavior
change was expected. This unintentionally made ring's internal "server"
line subject to _srv_check_proxy_mode()'s log-backend compatibility
checks, which were only meant for real "mode log" backends.
Internal proxies (PR_CAP_INT) now fall through to the regular "else"
branch, i.e. the generic STREAM-transport check instead of the
family/DGRAM checks meant for log backends. Two independent
consequences follow from this, both regressions introduced by
23e5f18b8:
1. A "ring" section whose server targets a UNIX socket (a common
pattern to feed a local "log-forward" section) is rejected at parse
time with "log server address family not supported for log backend
server", even though this worked fine before 23e5f18b8.
Reproducer:
global
ring buf1
server srv1 /tmp/repro-log-forward.sock
log-forward relay
bind unix@/tmp/repro-log-forward.sock mode 660
log ring@buf1 local0
2. Less visibly, a ring server given a DGRAM address (e.g.
"server s1 [email protected]:1514") was, until now, let through the
log-backend family check (DGRAM is not rejected there) and reaches
connect_server() at runtime, which promptly segfaults in
conn_select_mux_be() -> proto_is_quic() on a NULL proto, since a
ring's forward_px only ever expects a STREAM transport. This patch
also closes that crash, by routing rings back through the regular
STREAM-only check that non-log backends already get.
40eb1dd13 ("BUG/MEDIUM: sink: fix unexpected double postinit of sink
backend") already gives the sink's forward_px the PR_CAP_INT capability
for a related reason (skip the automatic log-backend postinit, since
sink manages it manually). This reuses that same flag to also skip the
log-backend-specific address checks for the same class of proxies,
since they are never real user-configured log backends.
This should be backported up to 3.3, but only where 23e5f18b8 and
40eb1dd13 are backported too - without the latter (which sets
PR_CAP_INT on forward_px), this patch is a silent no-op.
---
src/server.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/src/server.c b/src/server.c
index f8fa20cb8..c8091161e 100644
--- a/src/server.c
+++ b/src/server.c
@@ -3550,9 +3550,15 @@ static int _srv_check_proxy_mode(struct server *srv,
char postparse)
goto out;
}
- if (srv->proxy->mode == PR_MODE_SYSLOG) {
+ if (srv->proxy->mode == PR_MODE_SYSLOG && !(srv->proxy->cap &
PR_CAP_INT)) {
/* log backend server (belongs to proxy with mode log enabled):
- * perform some compatibility checks
+ * perform some compatibility checks. Internal proxies
(PR_CAP_INT,
+ * e.g. a sink's forward_px backing a "ring" section) are
excluded:
+ * they are tagged PR_MODE_SYSLOG for type-awareness purposes
only
+ * (see 23e5f18b8) and are not real user-configured log
backends,
+ * so they may legitimately target a UNIX socket (e.g. to feed a
+ * local "log-forward" section). They still go through the
regular
+ * STREAM-transport check below, in the "else" branch.
*/
/* supported address family types are:
--
2.52.0
