From 9bd7345212203924046009e29ce3f1515556f989 Mon Sep 17 00:00:00 2001
From: Dmitry Wagin <dmitry.wagin@ya.ru>
Date: Tue, 23 Mar 2021 12:01:15 -0400
Subject: libc: Some enhancements to syslog(3)

- Defined MAXLINE constant (8192 octets by default instead 2048) for
  centralized limit setting up. It sets maximum number of characters of
  the syslog message. RFC5424 doesn't limit maximum size of the message.
  Named after MAXLINE in syslogd(8).
- Fixed size of fmt_cpy buffer up to MAXLINE for rendering formatted
  (%m) messages.
- Introduced autoexpansion of sending socket buffer up to MAXLINE.

MFC after:	1 month
Differential Revision:	https://reviews.freebsd.org/D27205
---
 lib/libc/gen/syslog.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

(limited to 'lib')

diff --git a/lib/libc/gen/syslog.c b/lib/libc/gen/syslog.c
index 19d44db0075a..797c7389d1a2 100644
--- a/lib/libc/gen/syslog.c
+++ b/lib/libc/gen/syslog.c
@@ -57,6 +57,9 @@ __FBSDID("$FreeBSD$");
 
 #include "libc_private.h"
 
+/* Maximum number of characters of syslog message */
+#define	MAXLINE		8192
+
 static int	LogFile = -1;		/* fd for log */
 static int	status;			/* connection status */
 static int	opened;			/* have done openlog() */
@@ -141,7 +144,7 @@ vsyslog1(int pri, const char *fmt, va_list ap)
 	char ch, *p;
 	long tz_offset;
 	int cnt, fd, saved_errno;
-	char hostname[MAXHOSTNAMELEN], *stdp, tbuf[2048], fmt_cpy[1024],
+	char hostname[MAXHOSTNAMELEN], *stdp, tbuf[MAXLINE], fmt_cpy[MAXLINE],
 	    errstr[64], tz_sign;
 	FILE *fp, *fmt_fp;
 	struct bufcookie tbuf_cookie;
@@ -396,9 +399,19 @@ connectlog(void)
 	struct sockaddr_un SyslogAddr;	/* AF_UNIX address of local logger */
 
 	if (LogFile == -1) {
+		socklen_t len;
+
 		if ((LogFile = _socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC,
 		    0)) == -1)
 			return;
+		if (_getsockopt(LogFile, SOL_SOCKET, SO_SNDBUF, &len,
+		    &(socklen_t){sizeof(len)}) == 0) {
+			if (len < MAXLINE) {
+				len = MAXLINE;
+				(void)_setsockopt(LogFile, SOL_SOCKET, SO_SNDBUF,
+				    &len, sizeof(len));
+			}
+		}
 	}
 	if (LogFile != -1 && status == NOCONN) {
 		SyslogAddr.sun_len = sizeof(SyslogAddr);
-- 
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