From eaedbdaa0877ec6d0501b8c19ad5175c80764c67 Mon Sep 17 00:00:00 2001
From: Vladislav Grishenko <themiron@mail.ru>
Date: Wed, 12 Sep 2012 18:04:48 +0600
Subject: Fix syslog messages lost if syslogd is temporary busy
Commit 4139fe5aec935ba3f462dcaf6aafb6e5eadf1ab9 fixes SIGSTOPed syslogd issue.
but introduced new one - messages will be lost when socket buffer gets full,
not only if syslogd is stalled, but even if it accepts message slower than
someone sends and possibly leads to security hole, when important messages get
lost as result of attacker flooding.
Patch adds 1 second waiting for socket buffer can accept the message, helps
when syslogd is working hard. If it's stalled/SIGSTOPed, message will be sent
to errout as before. After that, further non-blocking /dev/log connect attempts
will fail immediately with EAGAIN error until syslogd reads some from it.
function old new delta
openlog_intern 259 355 +96
static.tv - 8 +8
.rodata 151 159 +8
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 2/0 up/down: 112/0) Total: 112 bytes
Signed-off-by: Vladislav Grishenko <themiron@mail.ru>
---
libc/misc/syslog/syslog.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/libc/misc/syslog/syslog.c b/libc/misc/syslog/syslog.c
index 72afabb83..1df0d1ae3 100644
--- a/libc/misc/syslog/syslog.c
+++ b/libc/misc/syslog/syslog.c
@@ -126,6 +126,7 @@ openlog_intern(void)
{
int fd;
int logType = SOCK_DGRAM;
+ static const struct timeval tv = { 1, 0 };
fd = LogFile;
if (fd == -1) {
@@ -143,6 +144,9 @@ openlog_intern(void)
if (fd != -1 && !connected) {
if (connect(fd, &SyslogAddr, sizeof(SyslogAddr)) != -1) {
+ /* We want to block send if e.g. syslogd is SIGSTOPed */
+ fcntl(fd, F_SETFL, ~O_NONBLOCK & fcntl(fd, F_GETFL));
+ setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv));
connected = 1;
} else {
if (fd != -1) {
--
cgit v1.2.3