[PATCH v4 10/16] eal: limit maximum runtime directory and socket paths

Stephen Hemminger
2025-12-06T18:45:18Z

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 | 83 +++++++++++++++++++-----------
lib/eal/common/eal_filesystem.h | 13 ++++-
3 files changed, 70 insertions(+), 32 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..dbf749c5b8 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;
@@ -132,15 +132,19 @@ find_pending_request(const char *dst, const char *act_name)
return r;
}

-static void
-create_socket_path(const char *name, char *buf, int len)
+static int
+create_socket_path(const char *name, char *buf, size_t len)
{
const char *prefix = eal_mp_socket_path();

- if (strlen(name) > 0)
- snprintf(buf, len, "%s_%s", prefix, name);
- else
- strlcpy(buf, prefix, len);
+ if (strlen(name) > 0) {
+ if (snprintf(buf, len, "%s_%s", prefix, name) >= (int)len)
+ return -1;
+ } else {
+ if (strlcpy(buf, prefix, len) >= len)
+ return -1;
+ }
+ return 0;
}

RTE_EXPORT_SYMBOL(rte_eal_primary_proc_alive)
@@ -572,6 +576,11 @@ open_socket_fd(void)
snprintf(peer_name, sizeof(peer_name),
"%d_%"PRIx64, getpid(), rte_rdtsc());

+ if (create_socket_path(peer_name, un.sun_path, sizeof(un.sun_path)) < 0) {
+ EAL_LOG(ERR, "peer '%s' socket path too long", peer_name);
+ return -1;
+ }
+
mp_fd = socket(AF_UNIX, SOCK_DGRAM, 0);
if (mp_fd < 0) {
EAL_LOG(ERR, "failed to create unix socket");
@@ -581,8 +590,6 @@ open_socket_fd(void)
memset(&un, 0, sizeof(un));
un.sun_family = AF_UNIX;

- create_socket_path(peer_name, un.sun_path, sizeof(un.sun_path));
-
unlink(un.sun_path); /* May still exist since last run */

if (bind(mp_fd, (struct sockaddr *)&un, sizeof(un)) < 0) {
@@ -599,17 +606,20 @@ 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));
- unlink(path);
+
+ if (create_socket_path(peer_name, path, sizeof(path)) < 0)
+ EAL_LOG(ERR, "file prefix path for peerr '%s' too long", peer_name);
+ else
+ unlink(path);
}

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();
@@ -624,7 +634,12 @@ rte_mp_channel_init(void)
}

/* create filter path */
- create_socket_path("*", path, sizeof(path));
+ if (create_socket_path("*", path, sizeof(path)) < 0) {
+ EAL_LOG(ERR, "file prefix path too long");
+ rte_errno = ENAMETOOLONG;
+ return -1;
+ }
+
rte_basename(path, mp_filter, sizeof(mp_filter));
strlcpy(mp_dir_path, dirname(path), sizeof(mp_dir_path));

@@ -779,14 +794,17 @@ 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;

- snprintf(path, sizeof(path), "%s/%s", mp_dir_path,
- ent->d_name);
- if (send_msg(path, msg, type) < 0)
+ if (snprintf(path, sizeof(path), "%s/%s",
+ mp_dir_path, ent->d_name) >= (int)sizeof(path)) {
+ EAL_LOG(ERR, "Unix domain path %s/%s too long",
+ mp_dir_path, ent->d_name);
+ ret = -1;
+ } else if (send_msg(path, msg, type) < 0)
ret = -1;
}
/* unlock the dir */
@@ -1055,13 +1073,18 @@ 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;

- snprintf(path, sizeof(path), "%s/%s", mp_dir_path,
- ent->d_name);
+ if (snprintf(path, sizeof(path), "%s/%s",
+ mp_dir_path, ent->d_name) >= (int)sizeof(path)) {
+ EAL_LOG(ERR, "Unix domain socket path '%s/%s' too long",
+ mp_dir_path, ent->d_name);
+ rte_errno = ENAMETOOLONG;
+ goto unlock_end;
+ }

/* unlocks the mutex while waiting for response,
* locks on receive
@@ -1200,15 +1223,17 @@ 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;

- snprintf(path, sizeof(path), "%s/%s", mp_dir_path,
- ent->d_name);
-
- if (mp_request_async(path, copy, param, ts))
+ if (snprintf(path, sizeof(path), "%s/%s",
+ mp_dir_path, ent->d_name) >= (int)sizeof(path)) {
+ EAL_LOG(ERR, "Unix domain path %s/%s too long",
+ mp_dir_path, ent->d_name);
+ ret = -1;
+ } else if (mp_request_async(path, copy, param, ts))
ret = -1;
}
/* if we didn't send anything, put dummy request on the queue */
diff --git a/lib/eal/common/eal_filesystem.h b/lib/eal/common/eal_filesystem.h
index 5d21f07c20..2de88d7cc2 100644
--- a/lib/eal/common/eal_filesystem.h
+++ b/lib/eal/common/eal_filesystem.h
@@ -45,10 +45,21 @@ eal_runtime_config_path(void)

/** Path of primary/secondary communication unix socket file. */
#define MP_SOCKET_FNAME "mp_socket"
+
+#ifdef RTE_EXEC_ENV_WINDOWS
+#include <winsock2.h>
+#include <afunix.h>
+#else
+#include <sys/un.h>
+
+/** Maximum length of unix domain socket path. */
+#define UNIX_PATH_MAX (sizeof(((struct sockaddr_un *)0)->sun_path))
+#endif
+
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