syslogd: Add support for FreeBSD -s, secure mode

- Update man page
- Enable -s in default systemd service settings
- Add support for SecureMode, with shutdown()

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

man/syslogd.8

@@ -13,7 +13,7 @@
 .Nd System Log Daemon
 .Sh SYNOPSIS
 .Nm
-.Op Fl ?46Adhnv
+.Op Fl ?46Adhnsv
 .Op Fl b Ar addr[:port]
 .Op Fl b Ar :port
 .Op Fl f Ar file
@@ -180,6 +180,10 @@ The size argument takes optional modifiers; k, M, G.  E.g., 100M is
 The optional number of files kept include both gzipped files and the
 first rotated (not zipped) file.  The default for this, when omitted,
 is 5.
+.It Fl s
+Operate in secure mode.  Do not log messages from remote machines.  If
+specified twice, no network socket will be opened at all, which also
+disables logging to remote machines.
 .It Fl v
 Print
 .Nm

src/socket.c

@@ -97,11 +97,14 @@ eaddr:	free(entry);
 err:	return -1;
 }
 
-static int socket_opts(int sd, int family)
+static int socket_opts(int sd, int family, int secure)
 {
 	socklen_t len, slen;
 	int on = 1;
 
+	if (secure)
+		goto skip;
+
 	/*
 	 * This first one is best-effort only, try to increase receive
 	 * buffer size.  Alert user on failure and proceed.
@@ -113,7 +116,7 @@ static int socket_opts(int sd, int family)
 			ERR("Failed increasing size of socket receive buffer");
 	}
 
-	switch (family) {
+skip:	switch (family) {
 	case AF_INET6:
 		if (setsockopt(sd, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0) {
 			ERR("setsockopt (IPV6_ONLY), suspending IPv6");
@@ -138,6 +141,7 @@ int socket_create(struct addrinfo *ai, void (*cb)(int, void *), void *arg)
 {
 	struct sockaddr_un *sun = (struct sockaddr_un *)ai->ai_addr;
 	mode_t mode = ai->ai_protocol;
+	int secure = ai->ai_flags & AI_SECURE;
 	int type = ai->ai_socktype | SOCK_CLOEXEC | SOCK_NONBLOCK;
 	int sd;
 
@@ -150,13 +154,16 @@ int socket_create(struct addrinfo *ai, void (*cb)(int, void *), void *arg)
 	if (sd < 0)
 		return -1;
 
-	if (socket_opts(sd, ai->ai_family))
+	if (socket_opts(sd, ai->ai_family, secure))
 		goto err;
 
+	if (secure)
+		goto skip;
+
 	if (bind(sd, ai->ai_addr, ai->ai_addrlen) < 0)
 		goto err;
 
-	if (ai->ai_family == AF_UNIX) {
+skip:	if (ai->ai_family == AF_UNIX) {
 		if (chmod(sun->sun_path, mode) < 0)
 			goto err;
 	}

src/syslogd.c

@@ -127,6 +127,7 @@ static int	  family = PF_UNSPEC;	  /* protocol family (IPv4, IPv6 or both) */
 static int	  mask_C1 = 1;		  /* mask characters from 0x80 - 0x9F */
 static int	  send_to_all;		  /* send message to all IPv4/IPv6 addresses */
 static int	  MarkSeq = 0;		  /* mark sequence number */
+static int	  SecureMode;		  /* when true, receive only unix domain socks */
 
 static int	  RemoteAddDate;	  /* Always set the date on remote messages */
 static int	  RemoteHostname;	  /* Log remote hostname from the message */
@@ -191,7 +192,7 @@ static int addpeer(struct peer *pe0)
 int usage(int code)
 {
 	printf("Usage:\n"
-	       "  syslogd [-46Adnrvh?] [-b :PORT] [-b ADDR[:PORT]] [-f FILE] [-m SEC]\n"
+	       "  syslogd [-46Adnrsvh?] [-b :PORT] [-b ADDR[:PORT]] [-f FILE] [-m SEC]\n"
 	       "                        [-P PID_FILE] [-p SOCK_PATH] [-R SIZE[:NUM]]\n"
 	       "\n"
 	       "Options:\n"
@@ -212,6 +213,9 @@ int usage(int code)
 	       "  -R S[:R]  Enable log rotation.  The size argument (S) takes k/M/G qualifiers,\n"
 	       "            e.g. 2M for 2 MiB.  The optional rotations argument default to 5.\n"
 	       "            Rotation can also be defined per log file in syslog.conf\n"
+	       "  -s        Operate in secure mode, do not log messages from remote machines.\n"
+	       "            If specified twice, no socket at all will be opened, which also\n"
+	       "            disables support for logging to remote machines.\n"
 	       "\n"
 	       "  -?        Show this help text\n"
 	       "  -v        Show program version and exit\n"
@@ -242,7 +246,7 @@ int main(int argc, char *argv[])
 	KeepKernFac = 1;
 #endif
 
-	while ((ch = getopt(argc, argv, "46Ab:dhHf:m:nP:p:R:v?")) != EOF) {
+	while ((ch = getopt(argc, argv, "46Ab:dhHf:m:nP:p:R:sv?")) != EOF) {
 		switch ((char)ch) {
 		case '4':
 			family = PF_INET;
@@ -312,6 +316,10 @@ int main(int argc, char *argv[])
 			parse_rotation(optarg, &RotateSz, &RotateCnt);
 			break;
 
+		case 's':
+			SecureMode++;
+			break;
+
 		case 'v':
 			printf("syslogd v%s\n", VERSION);
 			exit(0);
@@ -393,7 +401,7 @@ int main(int argc, char *argv[])
 	SIMPLEQ_FOREACH(pe, &pqueue, next) {
 		if (pe->pe_name && pe->pe_name[0] == '/')
 			create_unix_socket(pe);
-		else // XXX if (cffwd() && SecureMode <= 1)
+		else if (SecureMode < 2)
 			create_inet_socket(pe);
 	}
 
@@ -540,6 +548,11 @@ static void create_inet_socket(struct peer *pe)
 	}
 
 	for (r = res; r; r = r->ai_next) {
+		if (SecureMode)
+			r->ai_flags |= AI_SECURE;
+		else
+			r->ai_flags &= ~AI_SECURE;
+
 		sd = socket_create(r, inet_cb, NULL);
 		if (sd < 0)
 			continue;
@@ -1907,24 +1920,6 @@ void doexit(int signo)
 	exit(0);
 }
 
-/*
- * Check active rules for action FWD
- */
-static int cffwd(void)
-{
-	struct filed *f;
-	int fwd = 0;
-
-	SIMPLEQ_FOREACH(f, &fhead, f_link) {
-		if (f->f_type == F_FORW      ||
-		    f->f_type == F_FORW_SUSP ||
-		    f->f_type == F_FORW_UNKN)
-			fwd++;
-	}
-
-	return fwd;
-}
-
 /* Create fallback .conf with err+panic sent to console */
 static FILE *cftemp(void)
 {

src/syslogd.h

@@ -111,6 +111,8 @@
 
 #define LIST_DELIMITER    ':' /* delimiter between two hosts */
 
+#define	AI_SECURE	0x8000	/* Tell socket_create() to not bind() */
+
 /* From The Practice of Programming, by Kernighan and Pike */
 #ifndef NELEMS
 #define NELEMS(array) (sizeof(array) / sizeof(array[0]))

syslogd.service.in

@@ -6,7 +6,7 @@ Requires=syslog.socket
 
 [Service]
 Type=simple
-ExecStart=@SBINDIR@/syslogd -n
+ExecStart=@SBINDIR@/syslogd -sn
 StandardOutput=null
 Restart=on-failure