As a result of the recommendations in RFC 5424, 5425, 5426 set the

maximum syslog message size to 8192 octets.  Restrict UDP sending
to 1180 octets payload to avoid fragmentation.  This is more than
the 1024 we supported before.
Also truncate the line in printline() to exactly 8192 bytes regardless
of visual encoding.  That is a more predictable behavior and makes
testing easier.
Although syslog(3) does not support long messages yet, make sure
that /dev/log can receive them.
OK deraadt@

1 files changed, 17 insertions, 10 deletions

diff --git a/usr.sbin/syslogd/syslogd.c b/usr.sbin/syslogd/syslogd.c
index 0f97bfc2d76..4d4f1b74531 100644
--- a/usr.sbin/syslogd/syslogd.c
+++ b/usr.sbin/syslogd/syslogd.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: syslogd.c,v 1.146 2015/01/31 00:58:35 bluhm Exp $	*/
+/*	$OpenBSD: syslogd.c,v 1.147 2015/02/02 17:27:43 bluhm Exp $	*/
 
 /*
  * Copyright (c) 1983, 1988, 1993, 1994
@@ -53,7 +53,8 @@
  * IPv6, libevent, sending over TCP and TLS by Alexander Bluhm
  */
 
-#define	MAXLINE		1024		/* maximum line length */
+#define MAXLINE		8192		/* maximum line length */
+#define MAX_UDPMSG	1180		/* maximum UDP send size */
 #define MIN_MEMBUF	(MAXLINE * 4)	/* Minimum memory buffer size */
 #define MAX_MEMBUF	(256 * 1024)	/* Maximum memory buffer size */
 #define MAX_MEMBUF_NAME	64		/* Max length of membuf log name */
@@ -98,6 +99,7 @@
 #include <vis.h>
 
 #define MAXIMUM(a, b)	(((a) > (b)) ? (a) : (b))
+#define MINIMUM(a, b)	(((a) < (b)) ? (a) : (b))
 
 #define SYSLOG_NAMES
 #include <sys/syslog.h>
@@ -920,7 +922,7 @@ void
 printline(char *hname, char *msg)
 {
 	int pri;
-	char *p, *q, line[MAXLINE + 1];
+	char *p, *q, line[MAXLINE + 4 + 1];  /* message, encoding, NUL */
 
 	/* test for special codes */
 	pri = DEFUPRI;
@@ -943,13 +945,13 @@ printline(char *hname, char *msg)
 	if (LOG_FAC(pri) == LOG_KERN)
 		pri = LOG_USER | LOG_PRI(pri);
 
-	for (q = line; *p && q < &line[sizeof(line) - 4]; p++) {
+	for (q = line; *p && q < &line[MAXLINE]; p++) {
 		if (*p == '\n')
 			*q++ = ' ';
 		else
 			q = vis(q, *p, 0, 0);
 	}
-	*q = '\0';
+	line[MAXLINE] = *q = '\0';
 
 	logmsg(pri, line, hname, 0);
 }
@@ -1181,13 +1183,13 @@ fprintlog(struct filed *f, int flags, char *msg)
 
 	case F_FORWUDP:
 		dprintf(" %s\n", f->f_un.f_forw.f_loghost);
-		l = snprintf(line, sizeof(line), "<%d>%.15s %s%s%s",
-		    f->f_prevpri, (char *)iov[0].iov_base,
+		l = snprintf(line, MINIMUM(MAX_UDPMSG + 1, sizeof(line)),
+		    "<%d>%.15s %s%s%s", f->f_prevpri, (char *)iov[0].iov_base,
 		    IncludeHostname ? LocalHostName : "",
 		    IncludeHostname ? " " : "",
 		    (char *)iov[4].iov_base);
-		if (l < 0 || (size_t)l >= sizeof(line))
-			l = strlen(line);
+		if (l < 0 || (size_t)l > MINIMUM(MAX_UDPMSG, sizeof(line)))
+			l = MINIMUM(MAX_UDPMSG, sizeof(line));
 		if (sendto(f->f_file, line, l, 0,
 		    (struct sockaddr *)&f->f_un.f_forw.f_addr,
 		    f->f_un.f_forw.f_addr.ss_len) != l) {
@@ -2120,7 +2122,7 @@ unix_socket(char *path, int type, mode_t mode)
 {
 	struct sockaddr_un s_un;
 	char ebuf[512];
-	int fd;
+	int fd, optval;
 	mode_t old_umask;
 
 	memset(&s_un, 0, sizeof(s_un));
@@ -2168,6 +2170,11 @@ unix_socket(char *path, int type, mode_t mode)
 		return (-1);
 	}
 
+	optval = MAXLINE + PATH_MAX;
+	if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &optval, sizeof(optval))
+	    == -1)
+		logerror("cannot setsockopt unix");
+
 	return (fd);
 }