From: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>

Date: Mon, 27 Jan 2020 19:01:59 +0000

Subject: [PATCH] virtiofsd: Prevent multiply running with same

 vhost_user_socket

MIME-Version: 1.0

Content-Type: text/plain; charset=UTF-8

Content-Transfer-Encoding: 8bit

virtiofsd can run multiply even if the vhost_user_socket is same path.

  ]# ./virtiofsd -o vhost_user_socket=/tmp/vhostqemu -o source=/tmp/share &

  [1] 244965

  virtio_session_mount: Waiting for vhost-user socket connection...

  ]# ./virtiofsd -o vhost_user_socket=/tmp/vhostqemu -o source=/tmp/share &

  [2] 244966

  virtio_session_mount: Waiting for vhost-user socket connection...

  ]#

The user will get confused about the situation and maybe the cause of the

unexpected problem. So it's better to prevent the multiple running.

Create a regular file under localstatedir directory to exclude the

vhost_user_socket. To create and lock the file, use qemu_write_pidfile()

because the API has some sanity checks and file lock.

Signed-off-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

  Applied fixes from Stefan's review and moved osdep include

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

(cherry picked from commit 96814800d2b49d18737c36e021c387697ec40c62)

---

 tools/virtiofsd/fuse_lowlevel.c |  1 +

 tools/virtiofsd/fuse_virtio.c   | 49 ++++++++++++++++++++++++++++++++-

 2 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/tools/virtiofsd/fuse_lowlevel.c b/tools/virtiofsd/fuse_lowlevel.c

index 440508a6ec..aac282f278 100644

--- a/tools/virtiofsd/fuse_lowlevel.c

+++ b/tools/virtiofsd/fuse_lowlevel.c

@@ -18,6 +18,7 @@

 #include <assert.h>

 #include <errno.h>

+#include <glib.h>

 #include <limits.h>

 #include <stdbool.h>

 #include <stddef.h>

diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c

index e7bd772805..b7948def27 100644

--- a/tools/virtiofsd/fuse_virtio.c

+++ b/tools/virtiofsd/fuse_virtio.c

@@ -13,11 +13,12 @@

 #include "qemu/osdep.h"

 #include "qemu/iov.h"

-#include "fuse_virtio.h"

+#include "qapi/error.h"

 #include "fuse_i.h"

 #include "standard-headers/linux/fuse.h"

 #include "fuse_misc.h"

 #include "fuse_opt.h"

+#include "fuse_virtio.h"

 #include <assert.h>

 #include <errno.h>

@@ -743,6 +744,42 @@ int virtio_loop(struct fuse_session *se)

     return 0;

 }

+static void strreplace(char *s, char old, char new)

+{

+    for (; *s; ++s) {

+        if (*s == old) {

+            *s = new;

+        }

+    }

+}

+

+static bool fv_socket_lock(struct fuse_session *se)

+{

+    g_autofree gchar *sk_name = NULL;

+    g_autofree gchar *pidfile = NULL;

+    g_autofree gchar *dir = NULL;

+    Error *local_err = NULL;

+

+    dir = qemu_get_local_state_pathname("run/virtiofsd");

+

+    if (g_mkdir_with_parents(dir, S_IRWXU) < 0) {

+        fuse_log(FUSE_LOG_ERR, "%s: Failed to create directory %s: %s",

+                 __func__, dir, strerror(errno));

+        return false;

+    }

+

+    sk_name = g_strdup(se->vu_socket_path);

+    strreplace(sk_name, '/', '.');

+    pidfile = g_strdup_printf("%s/%s.pid", dir, sk_name);

+

+    if (!qemu_write_pidfile(pidfile, &local_err)) {

+        error_report_err(local_err);

+        return false;

+    }

+

+    return true;

+}

+

 static int fv_create_listen_socket(struct fuse_session *se)

 {

     struct sockaddr_un un;

@@ -758,6 +795,16 @@ static int fv_create_listen_socket(struct fuse_session *se)

         return -1;

     }

+    if (!strlen(se->vu_socket_path)) {

+        fuse_log(FUSE_LOG_ERR, "Socket path is empty\n");

+        return -1;

+    }

+

+    /* Check the vu_socket_path is already used */

+    if (!fv_socket_lock(se)) {

+        return -1;

+    }

+

     /*

      * Create the Unix socket to communicate with qemu

      * based on QEMU's vhost-user-bridge