BUG/MEDIUM: logs: segfault writing to log from Lua

Michael Ezzell reported a bug causing haproxy to segfault during startup
when trying to send syslog message from Lua. The function __send_log() can
be called with *p that is NULL and/or when the configuration is not fully
parsed, as is the case with Lua.

This patch fixes this problem by using individual vectors instead of the
pre-generated strings log_htp and log_htp_rfc5424.

Also, this patch fixes a problem causing haproxy to write the wrong pid in
the logs -- the log_htp(_rfc5424) strings were generated at the haproxy
start, but "pid" value would be changed after haproxy is started in
daemon/systemd mode.

include/proto/log.h

@@ -148,11 +148,6 @@ char *lf_ip(char *dst, struct sockaddr *sockaddr, size_t size, struct logformat_
  */
 char *lf_port(char *dst, struct sockaddr *sockaddr, size_t size, struct logformat_node *node);
 
-/*
- * Write hostname, log_tag and pid to the log string
- */
-char *lf_host_tag_pid(char *dst, int format, const char *hostname, const char *log_tag, int pid, size_t size);
-
 
 #endif /* _PROTO_LOG_H */
 

include/types/global.h

@@ -126,7 +126,7 @@ struct global {
 	char *chroot;
 	char *pidfile;
 	char *node, *desc;		/* node name & description */
-	char *log_tag;                  /* name for syslog */
+	struct chunk log_tag;           /* name for syslog */
 	struct list logsrvs;
 	char *log_send_hostname;   /* set hostname in syslog header */
 	char *server_state_base;   /* path to a directory where server state files can be found */

include/types/log.h

@@ -30,7 +30,7 @@
 
 #define NB_LOG_FACILITIES       24
 #define NB_LOG_LEVELS           8
-#define NB_MSG_IOVEC_ELEMENTS   5
+#define NB_MSG_IOVEC_ELEMENTS   8
 #define SYSLOG_PORT             514
 #define UNIQUEID_LEN            128
 

include/types/proxy.h

@@ -346,9 +346,7 @@ struct proxy {
 	struct list logsrvs;
 	struct list logformat; 			/* log_format linked list */
 	struct list logformat_sd;		/* log_format linked list for the RFC5424 structured-data part */
-	char *log_tag;                          /* override default syslog tag */
+	struct chunk log_tag;                   /* override default syslog tag */
-	struct chunk log_htp;			/* a syslog header part that contains hostname, log_tag and pid (RFC3164 format) */
-	struct chunk log_htp_rfc5424;		/* a syslog header part that contains hostname, log_tag and pid (RFC5424 format) */
 	char *header_unique_id; 		/* unique-id header */
 	struct list format_unique_id;		/* unique-id format */
 	int to_log;				/* things to be logged (LW_*) */

src/cfgparse.c

@@ -1659,7 +1659,6 @@ int cfg_parse_global(const char *file, int linenum, char **args, int kwm)
 		else
 			name = hostname;
 
-		/* We'll add a space after the name to respect the log format */
 		free(global.log_send_hostname);
 		global.log_send_hostname = strdup(name);
 	}
@@ -1701,8 +1700,8 @@ int cfg_parse_global(const char *file, int linenum, char **args, int kwm)
 			err_code |= ERR_ALERT | ERR_FATAL;
 			goto out;
 		}
-		free(global.log_tag);
+		chunk_destroy(&global.log_tag);
-		global.log_tag = strdup(args[1]);
+		chunk_initstr(&global.log_tag, strdup(args[1]));
 	}
 	else if (!strcmp(args[0], "spread-checks")) {  /* random time between checks (0-50) */
 		if (alertif_too_many_args(1, file, linenum, args, &err_code))
@@ -2760,8 +2759,7 @@ int cfg_parse_listen(const char *file, int linenum, char **args, int kwm)
 		if (curproxy->conf.uniqueid_format_string)
 			curproxy->conf.uniqueid_format_string = strdup(curproxy->conf.uniqueid_format_string);
 
-		if (defproxy.log_tag)
+		chunk_dup(&curproxy->log_tag, &defproxy.log_tag);
-			curproxy->log_tag = strdup(defproxy.log_tag);
 
 		if (defproxy.conf.uif_file) {
 			curproxy->conf.uif_file = strdup(defproxy.conf.uif_file);
@@ -2843,7 +2841,7 @@ int cfg_parse_listen(const char *file, int linenum, char **args, int kwm)
 		free(defproxy.conf.uniqueid_format_string);
 		free(defproxy.conf.lfs_file);
 		free(defproxy.conf.uif_file);
-		free(defproxy.log_tag);
+		chunk_destroy(&defproxy.log_tag);
 		free_email_alert(&defproxy);
 
 		if (defproxy.conf.logformat_sd_string != default_rfc5424_sd_log_format)
@@ -5852,8 +5850,8 @@ stats_error_parsing:
 			err_code |= ERR_ALERT | ERR_FATAL;
 			goto out;
 		}
-		free(curproxy->log_tag);
+		chunk_destroy(&curproxy->log_tag);
-		curproxy->log_tag = strdup(args[1]);
+		chunk_initstr(&curproxy->log_tag, strdup(args[1]));
 	}
 	else if (!strcmp(args[0], "log") && kwm == KWM_NO) {
 		/* delete previous herited or defined syslog servers */
@@ -7889,52 +7887,16 @@ int check_config_validity()
 		}
 out_uri_auth_compat:
 
-		/* write a syslog header string that contains hostname, log_tag and pid */
+		/* check whether we have a log server that uses RFC5424 log format */
 		list_for_each_entry(tmplogsrv, &curproxy->logsrvs, list) {
-			char *hdr;
+			if (tmplogsrv->format == LOG_FORMAT_RFC5424) {
-			struct chunk *htp;
+				if (!curproxy->conf.logformat_sd_string) {
-			char *host = global.log_send_hostname;
+					/* set the default logformat_sd_string */
-
+					curproxy->conf.logformat_sd_string = default_rfc5424_sd_log_format;
-			switch (tmplogsrv->format) {
+				}
-			case LOG_FORMAT_RFC3164:
-				hdr = logheader;
-				htp = &curproxy->log_htp;
-				host = host ? host : "";
 				break;
-
-			case LOG_FORMAT_RFC5424:
-				hdr = logheader_rfc5424;
-				htp = &curproxy->log_htp_rfc5424;
-				host = host ? host : hostname;
-				break;
-
-			default:
-				continue; /* must never happen */
 			}
-
-			if (htp->str)
-				continue;
-
-			htp->str = lf_host_tag_pid(hdr, tmplogsrv->format, host,
-			                           curproxy->log_tag ? curproxy->log_tag : global.log_tag,
-			                           pid, global.max_syslog_len);
-
-			if ((htp->str == NULL) ||
-			    ((htp->len = htp->str - hdr) >= global.max_syslog_len)) {
-				Alert("Proxy '%s': cannot write a syslog header string that contains "
-				      "hostname, log_tag and pid.\n",
-				      curproxy->id);
-				cfgerr++;
-				goto out_host_tag_pid;
-			}
-
-			htp->str = (char *)malloc(htp->len);
-			memcpy(htp->str, hdr, htp->len);
-			htp->size = 0;
-
-			hdr[0] = 0;
 		}
-out_host_tag_pid:
 
 		/* compile the log format */
 		if (!(curproxy->cap & PR_CAP_FE)) {

src/haproxy.c

@@ -626,7 +626,7 @@ void init(int argc, char **argv)
 		progname = tmp + 1;
 
 	/* the process name is used for the logs only */
-	global.log_tag = strdup(progname);
+	chunk_initstr(&global.log_tag, strdup(progname));
 
 	argc--; argv++;
 	while (argc > 0) {
@@ -1335,8 +1335,6 @@ void deinit(void)
 			LIST_DEL(&log->list);
 			free(log);
 		}
-		chunk_destroy(&p->log_htp);
-		chunk_destroy(&p->log_htp_rfc5424);
 
 		list_for_each_entry_safe(lf, lfb, &p->logformat, list) {
 			LIST_DEL(&lf->list);
@@ -1478,7 +1476,7 @@ void deinit(void)
 #endif
 
 	free(global.log_send_hostname); global.log_send_hostname = NULL;
-	free(global.log_tag); global.log_tag = NULL;
+	chunk_destroy(&global.log_tag);
 	free(global.chroot);  global.chroot = NULL;
 	free(global.pidfile); global.pidfile = NULL;
 	free(global.node);    global.node = NULL;

src/log.c

@@ -41,9 +41,29 @@
 #include <proto/ssl_sock.h>
 #endif
 
-const char *log_formats[LOG_FORMATS] = {
+struct log_fmt {
-	[LOG_FORMAT_RFC3164] = "rfc3164",
+	char *name;
-	[LOG_FORMAT_RFC5424] = "rfc5424"
+	struct {
+		struct chunk sep1; /* first pid separator */
+		struct chunk sep2; /* second pid separator */
+	} pid;
+};
+
+static const struct log_fmt log_formats[LOG_FORMATS] = {
+	[LOG_FORMAT_RFC3164] = {
+		.name = "rfc3164",
+		.pid = {
+			.sep1 = { .str = "[",   .len = 1 },
+			.sep2 = { .str = "]: ", .len = 3 }
+		}
+	},
+	[LOG_FORMAT_RFC5424] = {
+		.name = "rfc5424",
+		.pid = {
+			.sep1 = { .str = " ",   .len = 1 },
+			.sep2 = { .str = " - ", .len = 3 }
+		}
+	}
 };
 
 const char *log_facilities[NB_LOG_FACILITIES] = {
@@ -155,12 +175,6 @@ char clf_http_log_format[] = "%{+Q}o %{-Q}ci - - [%T] %r %ST %B \"\" \"\" %cp %m
 char default_tcp_log_format[] = "%ci:%cp [%t] %ft %b/%s %Tw/%Tc/%Tt %B %ts %ac/%fc/%bc/%sc/%rc %sq/%bq";
 char *log_format = NULL;
 
-/* Common printf format strings for hostname, log_tag and pid used in all
- * outgoing syslog messages.
- */
-static char default_host_tag_pid_log_format[] = "%s%s%s[%d]: ";
-static char rfc5424_host_tag_pid_log_format[] = "%s%s%s %d - ";
-
 /* Default string used for structured-data part in RFC5424 formatted
  * syslog messages.
  */
@@ -653,7 +667,7 @@ int get_log_format(const char *fmt)
 	int format;
 
 	format = LOG_FORMATS - 1;
-	while (format >= 0 && strcmp(log_formats[format], fmt))
+	while (format >= 0 && strcmp(log_formats[format].name, fmt))
 		format--;
 
 	return format;
@@ -780,33 +794,6 @@ char *lf_port(char *dst, struct sockaddr *sockaddr, size_t size, struct logforma
 	return ret;
 }
 
-char *lf_host_tag_pid(char *dst, int format, const char *hostname, const char *log_tag, int pid, size_t size)
-{
-	char *ret = dst;
-	char *fmt;
-	int iret;
-
-	switch (format) {
-	case LOG_FORMAT_RFC3164:
-		fmt = default_host_tag_pid_log_format;
-		break;
-
-	case LOG_FORMAT_RFC5424:
-		fmt = rfc5424_host_tag_pid_log_format;
-		break;
-
-	default:
-		return NULL;
-	}
-
-	iret = snprintf(dst, size, fmt, hostname, strlen(hostname) ? " " : "", log_tag, pid);
-	if (iret < 0 || iret > size)
-		return NULL;
-	ret += iret;
-
-	return ret;
-}
-
 /* Re-generate time-based part of the syslog header in RFC3164 format at
  * the beginning of logheader once a second and return the pointer to the
  * first character after it.
@@ -815,6 +802,8 @@ static char *update_log_hdr(const time_t time)
 {
 	static long tvsec;
 	static char *dataptr = NULL; /* backup of last end of header, NULL first time */
+	static struct chunk host = { NULL, 0, 0 };
+	static int sep = 0;
 
 	if (unlikely(time != tvsec || dataptr == NULL)) {
 		/* this string is rebuild only once a second */
@@ -824,10 +813,17 @@ static char *update_log_hdr(const time_t time)
 		tvsec = time;
 		get_localtime(tvsec, &tm);
 
+		if (unlikely(global.log_send_hostname != host.str)) {
+			host.str = global.log_send_hostname;
+			host.len = host.str ? strlen(host.str) : 0;
+			sep = host.len ? 1 : 0;
+		}
+
 		hdr_len = snprintf(logheader, global.max_syslog_len,
-				   "<<<<>%s %2d %02d:%02d:%02d ",
+				   "<<<<>%s %2d %02d:%02d:%02d %.*s%*s",
 				   monthname[tm.tm_mon],
-				   tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec);
+				   tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec,
+				   host.len, host.str, sep, "");
 		/* WARNING: depending upon implementations, snprintf may return
 		 * either -1 or the number of bytes that would be needed to store
 		 * the total message. In both cases, we must adjust it.
@@ -861,10 +857,10 @@ static char *update_log_hdr_rfc5424(const time_t time)
 		get_localtime(tvsec, &tm);
 
 		hdr_len = snprintf(logheader_rfc5424, global.max_syslog_len,
-				   "<<<<>1 %4d-%02d-%02dT%02d:%02d:%02d%s ",
+				   "<<<<>1 %4d-%02d-%02dT%02d:%02d:%02d%s %s ",
 				   tm.tm_year+1900, tm.tm_mon+1, tm.tm_mday,
-				   tm.tm_hour, tm.tm_min, tm.tm_sec,
+				   tm.tm_hour, tm.tm_min, tm.tm_sec, localtimezone,
-				   localtimezone);
+				   global.log_send_hostname ? global.log_send_hostname : hostname);
 		/* WARNING: depending upon implementations, snprintf may return
 		 * either -1 or the number of bytes that would be needed to store
 		 * the total message. In both cases, we must adjust it.
@@ -924,8 +920,11 @@ void __send_log(struct proxy *p, int level, char *message, size_t size, char *sd
 	int nblogger;
 	char *hdr, *hdr_ptr;
 	size_t hdr_size;
-	struct chunk *htp;
 	time_t time = date.tv_sec;
+	struct chunk *tag = &global.log_tag;
+	static int curr_pid;
+	static char pidstr[100];
+	static struct chunk pid;
 
 	dataptr = message;
 
@@ -937,21 +936,34 @@ void __send_log(struct proxy *p, int level, char *message, size_t size, char *sd
 		if (!LIST_ISEMPTY(&p->logsrvs)) {
 			logsrvs = &p->logsrvs;
 		}
+		if (p->log_tag.str) {
+			tag = &p->log_tag;
+		}
 	}
 
 	if (!logsrvs)
 		return;
 
+	if (unlikely(curr_pid != getpid())) {
+		curr_pid = getpid();
+		ltoa_o(curr_pid, pidstr, sizeof(pidstr));
+		chunk_initstr(&pid, pidstr);
+	}
+
 	/* Send log messages to syslog server. */
 	nblogger = 0;
 	list_for_each_entry(tmp, logsrvs, list) {
 		const struct logsrv *logsrv = tmp;
 		int *plogfd = logsrv->addr.ss_family == AF_UNIX ?
 			&logfdunix : &logfdinet;
+		char *pid_sep1 = NULL, *pid_sep2 = NULL;
 		int sent;
 		int maxlen;
 		int hdr_max = 0;
-		int htp_max = 0;
+		int tag_max = 0;
+		int pid_sep1_max = 0;
+		int pid_max = 0;
+		int pid_sep2_max = 0;
 		int sd_max = 0;
 		int max = 0;
 
@@ -980,13 +992,11 @@ void __send_log(struct proxy *p, int level, char *message, size_t size, char *sd
 		case LOG_FORMAT_RFC3164:
 			hdr = logheader;
 			hdr_ptr = update_log_hdr(time);
-			htp = &p->log_htp;
 			break;
 
 		case LOG_FORMAT_RFC5424:
 			hdr = logheader_rfc5424;
 			hdr_ptr = update_log_hdr_rfc5424(time);
-			htp = &p->log_htp_rfc5424;
 			sd_max = sd_size; /* the SD part allowed only in RFC5424 */
 			break;
 
@@ -1014,6 +1024,7 @@ void __send_log(struct proxy *p, int level, char *message, size_t size, char *sd
 
 		hdr_max = hdr_size - (hdr_ptr - hdr);
 
+		/* time-based header */
 		if (unlikely(hdr_size >= logsrv->maxlen)) {
 			hdr_max = MIN(hdr_max, logsrv->maxlen) - 1;
 			sd_max = 0;
@@ -1022,15 +1033,49 @@ void __send_log(struct proxy *p, int level, char *message, size_t size, char *sd
 
 		maxlen = logsrv->maxlen - hdr_max;
 
-		if (unlikely(htp->len >= maxlen)) {
+		/* tag */
-			htp_max = maxlen - 1;
+		tag_max = tag->len;
+		if (unlikely(tag_max >= maxlen)) {
+			tag_max = maxlen - 1;
 			sd_max = 0;
 			goto send;
 		}
 
-		htp_max = htp->len;
+		maxlen -= tag_max;
-		maxlen -= htp_max;
 
+		/* first pid separator */
+		pid_sep1_max = log_formats[logsrv->format].pid.sep1.len;
+		if (unlikely(pid_sep1_max >= maxlen)) {
+			pid_sep1_max = maxlen - 1;
+			sd_max = 0;
+			goto send;
+		}
+
+		pid_sep1 = log_formats[logsrv->format].pid.sep1.str;
+		maxlen -= pid_sep1_max;
+
+		/* pid */
+		pid_max = pid.len;
+		if (unlikely(pid_max >= maxlen)) {
+			pid_max = maxlen - 1;
+			sd_max = 0;
+			goto send;
+		}
+
+		maxlen -= pid_max;
+
+		/* second pid separator */
+		pid_sep2_max = log_formats[logsrv->format].pid.sep2.len;
+		if (unlikely(pid_sep2_max >= maxlen)) {
+			pid_sep2_max = maxlen - 1;
+			sd_max = 0;
+			goto send;
+		}
+
+		pid_sep2 = log_formats[logsrv->format].pid.sep2.str;
+		maxlen -= pid_sep2_max;
+
+		/* structured-data */
 		if (sd_max >= maxlen) {
 			sd_max = maxlen - 1;
 			goto send;
@@ -1039,15 +1084,21 @@ void __send_log(struct proxy *p, int level, char *message, size_t size, char *sd
 		max = MIN(size, maxlen - sd_max) - 1;
 send:
 		iovec[0].iov_base = hdr_ptr;
-		iovec[0].iov_len = hdr_max;
+		iovec[0].iov_len  = hdr_max;
-		iovec[1].iov_base = htp->str;
+		iovec[1].iov_base = tag->str;
-		iovec[1].iov_len = htp_max;
+		iovec[1].iov_len  = tag_max;
-		iovec[2].iov_base = sd;
+		iovec[2].iov_base = pid_sep1;
-		iovec[2].iov_len = sd_max;
+		iovec[2].iov_len  = pid_sep1_max;
-		iovec[3].iov_base = dataptr;
+		iovec[3].iov_base = pid.str;
-		iovec[3].iov_len = max;
+		iovec[3].iov_len  = pid_max;
-		iovec[4].iov_base = "\n"; /* insert a \n at the end of the message */
+		iovec[4].iov_base = pid_sep2;
-		iovec[4].iov_len = 1;
+		iovec[4].iov_len  = pid_sep2_max;
+		iovec[5].iov_base = sd;
+		iovec[5].iov_len  = sd_max;
+		iovec[6].iov_base = dataptr;
+		iovec[6].iov_len  = max;
+		iovec[7].iov_base = "\n"; /* insert a \n at the end of the message */
+		iovec[7].iov_len  = 1;
 
 		msghdr.msg_name = (struct sockaddr *)&logsrv->addr;
 		msghdr.msg_namelen = get_addr_len(&logsrv->addr);