[RFC 8/8] eal: limit maximum runtime directory and socket paths

[Stephen Hemminger <stephen@networkplumber.org>]

Linux (and FreeBSD) has a limitation of 108 characters for
any unix domain socket path. Therefore DPDK would not work
if a really large runtime directory was used.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 lib/eal/common/eal_common_config.c |  6 ++++--
 lib/eal/common/eal_common_proc.c   | 18 +++++++++---------
 lib/eal/common/eal_filesystem.h    |  6 +++++-
 3 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/lib/eal/common/eal_common_config.c b/lib/eal/common/eal_common_config.c
index 7fc7611a07..e2e69a75fb 100644
--- a/lib/eal/common/eal_common_config.c
+++ b/lib/eal/common/eal_common_config.c
@@ -6,6 +6,7 @@
 
 #include <eal_export.h>
 #include "eal_private.h"
+#include "eal_filesystem.h"
 #include "eal_memcfg.h"
 
 /* early configuration structure, when memory config is not mmapped */
@@ -24,7 +25,7 @@ static struct rte_config rte_config = {
 };
 
 /* platform-specific runtime dir */
-static char runtime_dir[PATH_MAX];
+static char runtime_dir[UNIX_PATH_MAX];
 
 /* internal configuration */
 static struct internal_config internal_config;
@@ -39,7 +40,8 @@ rte_eal_get_runtime_dir(void)
 int
 eal_set_runtime_dir(const char *run_dir)
 {
-	if (strlcpy(runtime_dir, run_dir, PATH_MAX) >= PATH_MAX) {
+	/* runtime directory limited by maximum allowable unix domain socket */
+	if (strlcpy(runtime_dir, run_dir, UNIX_PATH_MAX) >= UNIX_PATH_MAX) {
 		EAL_LOG(ERR, "Runtime directory string too long");
 		return -1;
 	}
diff --git a/lib/eal/common/eal_common_proc.c b/lib/eal/common/eal_common_proc.c
index 62fd4ba88f..3c4a1850ff 100644
--- a/lib/eal/common/eal_common_proc.c
+++ b/lib/eal/common/eal_common_proc.c
@@ -36,10 +36,10 @@
 
 static RTE_ATOMIC(int) mp_fd = -1;
 static rte_thread_t mp_handle_tid;
-static char mp_filter[PATH_MAX];   /* Filter for secondary process sockets */
-static char mp_dir_path[PATH_MAX]; /* The directory path for all mp sockets */
+static char mp_filter[UNIX_PATH_MAX];   /* Filter for secondary process sockets */
+static char mp_dir_path[UNIX_PATH_MAX]; /* The directory path for all mp sockets */
 static pthread_mutex_t mp_mutex_action = PTHREAD_MUTEX_INITIALIZER;
-static char peer_name[PATH_MAX];
+static char peer_name[UNIX_PATH_MAX];
 
 struct action_entry {
 	TAILQ_ENTRY(action_entry) next;
@@ -78,7 +78,7 @@ struct pending_request {
 		REQUEST_TYPE_SYNC,
 		REQUEST_TYPE_ASYNC
 	} type;
-	char dst[PATH_MAX];
+	char dst[UNIX_PATH_MAX];
 	struct rte_mp_msg *request;
 	struct rte_mp_msg *reply;
 	int reply_received;
@@ -599,7 +599,7 @@ open_socket_fd(void)
 static void
 close_socket_fd(int fd)
 {
-	char path[PATH_MAX];
+	char path[UNIX_PATH_MAX];
 
 	close(fd);
 	create_socket_path(peer_name, path, sizeof(path));
@@ -609,7 +609,7 @@ close_socket_fd(int fd)
 int
 rte_mp_channel_init(void)
 {
-	char path[PATH_MAX];
+	char path[UNIX_PATH_MAX];
 	int dir_fd;
 	const struct internal_config *internal_conf =
 		eal_get_internal_configuration();
@@ -779,7 +779,7 @@ mp_send(struct rte_mp_msg *msg, const char *peer, int type)
 	}
 
 	while ((ent = readdir(mp_dir))) {
-		char path[PATH_MAX];
+		char path[UNIX_PATH_MAX];
 
 		if (fnmatch(mp_filter, ent->d_name, 0) != 0)
 			continue;
@@ -1055,7 +1055,7 @@ rte_mp_request_sync(struct rte_mp_msg *req, struct rte_mp_reply *reply,
 
 	pthread_mutex_lock(&pending_requests.lock);
 	while ((ent = readdir(mp_dir))) {
-		char path[PATH_MAX];
+		char path[UNIX_PATH_MAX];
 
 		if (fnmatch(mp_filter, ent->d_name, 0) != 0)
 			continue;
@@ -1200,7 +1200,7 @@ rte_mp_request_async(struct rte_mp_msg *req, const struct timespec *ts,
 	}
 
 	while ((ent = readdir(mp_dir))) {
-		char path[PATH_MAX];
+		char path[UNIX_PATH_MAX];
 
 		if (fnmatch(mp_filter, ent->d_name, 0) != 0)
 			continue;
diff --git a/lib/eal/common/eal_filesystem.h b/lib/eal/common/eal_filesystem.h
index 5d21f07c20..5371d9f1d6 100644
--- a/lib/eal/common/eal_filesystem.h
+++ b/lib/eal/common/eal_filesystem.h
@@ -45,10 +45,14 @@ eal_runtime_config_path(void)
 
 /** Path of primary/secondary communication unix socket file. */
 #define MP_SOCKET_FNAME "mp_socket"
+
+/** Maximum length of unix domain socket path as defined in sys/un.h */
+#define UNIX_PATH_MAX 108
+
 static inline const char *
 eal_mp_socket_path(void)
 {
-	static char buffer[PATH_MAX]; /* static so auto-zeroed */
+	static char buffer[UNIX_PATH_MAX]; /* static so auto-zeroed */
 
 	snprintf(buffer, sizeof(buffer), "%s/%s", rte_eal_get_runtime_dir(),
 			MP_SOCKET_FNAME);
-- 
2.51.0