fix string overflow warnings

Gcc 10 now gives warnings about possible string overflow and
non-null terminated strings.

Resolve these by introducing strlcpy() and expanding the
size of some path string buffers.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>

6 files changed, 42 insertions, 15 deletions

diff --git a/configure.ac b/configure.ac
index 8b2e2ea..87d0e88 100644
--- a/configure.ac
+++ b/configure.ac
@@ -24,6 +24,7 @@ AC_HEADER_TIME
 dnl Checks for library functions.
 AC_CHECK_FUNCS(gethostname socket strdup uname)
 AC_CHECK_FUNCS(if_nametoindex if_indextoname)
+AC_CHECK_FUNCS(strlcpy strlcat)
 
 AC_SUBST(KERNEL_HEADERS)
 
diff --git a/libbridge/libbridge.h b/libbridge/libbridge.h
index c038b92..962f316 100644
--- a/libbridge/libbridge.h
+++ b/libbridge/libbridge.h
@@ -31,6 +31,9 @@
 extern unsigned int if_nametoindex (const char *__ifname);
 extern char *if_indextoname (unsigned int __ifindex, char *__ifname);
 
+#ifndef HAVE_STRLCPY
+size_t strlcpy(char *dst, const char *src, size_t size);
+#endif
 
 struct bridge_id
 {
diff --git a/libbridge/libbridge_devif.c b/libbridge/libbridge_devif.c
index 2cf78f6..8b7d954 100644
--- a/libbridge/libbridge_devif.c
+++ b/libbridge/libbridge_devif.c
@@ -30,9 +30,9 @@
 
 static FILE *fpopen(const char *dir, const char *name)
 {
-	char path[SYSFS_PATH_MAX];
+	char path[PATH_MAX];
 
-	snprintf(path, SYSFS_PATH_MAX, "%s/%s", dir, name);
+	snprintf(path, PATH_MAX, "%s/%s", dir, name);
 	return fopen(path, "r");
 }
 
@@ -91,7 +91,7 @@ static int get_portno(const char *brname, const char *ifname)
 		goto error;
 
 	memset(ifindices, 0, sizeof(ifindices));
-	strncpy(ifr.ifr_name, brname, IFNAMSIZ);
+	strlcpy(ifr.ifr_name, brname, IFNAMSIZ);
 	ifr.ifr_data = (char *) &args;
 
 	if (ioctl(br_socket_fd, SIOCDEVPRIVATE, &ifr) < 0) {
@@ -119,7 +119,7 @@ static int old_get_bridge_info(const char *bridge, struct bridge_info *info)
 				  (unsigned long) &i, 0, 0 };
 
 	memset(info, 0, sizeof(*info));
-	strncpy(ifr.ifr_name, bridge, IFNAMSIZ);
+	strlcpy(ifr.ifr_name, bridge, IFNAMSIZ);
 	ifr.ifr_data = (char *) &args;
 
 	if (ioctl(br_socket_fd, SIOCDEVPRIVATE, &ifr) < 0) {
@@ -213,7 +213,7 @@ static int old_get_port_info(const char *brname, const char *port,
 		unsigned long args[4] = { BRCTL_GET_PORT_INFO,
 					   (unsigned long) &i, index, 0 };
 	
-		strncpy(ifr.ifr_name, brname, IFNAMSIZ);
+		strlcpy(ifr.ifr_name, brname, IFNAMSIZ);
 		ifr.ifr_data = (char *) &args;
 		
 		if (ioctl(br_socket_fd, SIOCDEVPRIVATE, &ifr) < 0) {
@@ -312,7 +312,7 @@ static int br_set(const char *bridge, const char *name,
 		struct ifreq ifr;
 		unsigned long args[4] = { oldcode, value, 0, 0 };
 
-		strncpy(ifr.ifr_name, bridge, IFNAMSIZ);
+		strlcpy(ifr.ifr_name, bridge, IFNAMSIZ);
 		ifr.ifr_data = (char *) &args;
 		ret = ioctl(br_socket_fd, SIOCDEVPRIVATE, &ifr);
 	}
@@ -373,7 +373,7 @@ static int port_set(const char *bridge, const char *ifname,
 			struct ifreq ifr;
 			unsigned long args[4] = { oldcode, index, value, 0 };
 			
-			strncpy(ifr.ifr_name, bridge, IFNAMSIZ);
+			strlcpy(ifr.ifr_name, bridge, IFNAMSIZ);
 			ifr.ifr_data = (char *) &args;
 			ret = ioctl(br_socket_fd, SIOCDEVPRIVATE, &ifr);
 		}
@@ -429,7 +429,7 @@ int br_read_fdb(const char *bridge, struct fdb_entry *fdbs,
 		struct ifreq ifr;
 		int retries = 0;
 
-		strncpy(ifr.ifr_name, bridge, IFNAMSIZ);
+		strlcpy(ifr.ifr_name, bridge, IFNAMSIZ);
 		ifr.ifr_data = (char *) args;
 
 	retry:
diff --git a/libbridge/libbridge_if.c b/libbridge/libbridge_if.c
index 9cf4bac..5f3aed1 100644
--- a/libbridge/libbridge_if.c
+++ b/libbridge/libbridge_if.c
@@ -40,7 +40,7 @@ int br_add_bridge(const char *brname)
 		unsigned long arg[3] 
 			= { BRCTL_ADD_BRIDGE, (unsigned long) _br };
 
-		strncpy(_br, brname, IFNAMSIZ);
+		strlcpy(_br, brname, IFNAMSIZ);
 		ret = ioctl(br_socket_fd, SIOCSIFBR, arg);
 	} 
 
@@ -60,7 +60,7 @@ int br_del_bridge(const char *brname)
 		unsigned long arg[3] 
 			= { BRCTL_DEL_BRIDGE, (unsigned long) _br };
 
-		strncpy(_br, brname, IFNAMSIZ);
+		strlcpy(_br, brname, IFNAMSIZ);
 		ret = ioctl(br_socket_fd, SIOCSIFBR, arg);
 	} 
 	return  ret < 0 ? errno : 0;
@@ -75,7 +75,7 @@ int br_add_interface(const char *bridge, const char *dev)
 	if (ifindex == 0) 
 		return ENODEV;
 	
-	strncpy(ifr.ifr_name, bridge, IFNAMSIZ);
+	strlcpy(ifr.ifr_name, bridge, IFNAMSIZ);
 #ifdef SIOCBRADDIF
 	ifr.ifr_ifindex = ifindex;
 	err = ioctl(br_socket_fd, SIOCBRADDIF, &ifr);
@@ -100,7 +100,7 @@ int br_del_interface(const char *bridge, const char *dev)
 	if (ifindex == 0) 
 		return ENODEV;
 	
-	strncpy(ifr.ifr_name, bridge, IFNAMSIZ);
+	strlcpy(ifr.ifr_name, bridge, IFNAMSIZ);
 #ifdef SIOCBRDELIF
 	ifr.ifr_ifindex = ifindex;
 	err = ioctl(br_socket_fd, SIOCBRDELIF, &ifr);
diff --git a/libbridge/libbridge_init.c b/libbridge/libbridge_init.c
index f3a551e..c914971 100644
--- a/libbridge/libbridge_init.c
+++ b/libbridge/libbridge_init.c
@@ -46,7 +46,7 @@ void br_shutdown(void)
 /* If /sys/class/net/XXX/bridge exists then it must be a bridge */
 static int isbridge(const struct dirent *entry)
 {
-	char path[SYSFS_PATH_MAX];
+	char path[PATH_MAX];
 	struct stat st;
 	int ret, saved_errno;
 
@@ -56,7 +56,7 @@ static int isbridge(const struct dirent *entry)
 		    && entry->d_name[2] == '\0')))
 		return 0;
 
-	snprintf(path, SYSFS_PATH_MAX, 
+	snprintf(path, PATH_MAX, 
 		 SYSFS_CLASS_NET "%s/bridge", entry->d_name);
 
 	/* Workaround old glibc breakage.
@@ -161,7 +161,7 @@ static int old_foreach_port(const char *brname,
 				  (unsigned long)ifindices, MAX_PORTS, 0 };
 
 	memset(ifindices, 0, sizeof(ifindices));
-	strncpy(ifr.ifr_name, brname, IFNAMSIZ);
+	strlcpy(ifr.ifr_name, brname, IFNAMSIZ);
 	ifr.ifr_data = (char *) &args;
 
 	err = ioctl(br_socket_fd, SIOCDEVPRIVATE, &ifr);
diff --git a/libbridge/libbridge_misc.c b/libbridge/libbridge_misc.c
index 5791638..9379e93 100644
--- a/libbridge/libbridge_misc.c
+++ b/libbridge/libbridge_misc.c
@@ -48,3 +48,26 @@ int __get_hz(void)
 	const char * s = getenv("HZ");
 	return s ? atoi(s) : HZ;
 }
+
+#ifndef HAVE_STRLCPY
+#ifndef min
+# define min(x, y) ({			\
+	typeof(x) _min1 = (x);		\
+	typeof(y) _min2 = (y);		\
+	(void) (&_min1 == &_min2);	\
+	_min1 < _min2 ? _min1 : _min2; })
+#endif
+
+size_t strlcpy(char *dst, const char *src, size_t size)
+{
+	size_t srclen = strlen(src);
+
+	if (size) {
+		size_t minlen = min(srclen, size - 1);
+
+		memcpy(dst, src, minlen);
+		dst[minlen] = '\0';
+	}
+	return srclen;
+}
+#endif