[ovs-dev] [PATCH v3 3/3] netdev-dpdk: Support user-defined socket attribs

[Aaron Conole]

Currently, when dpdkvhostuser devices are created, they inherit whatever the
running umask and uid/gid of the vswitchd process. This leads to difficulties
when using vhost_user consumers (such as qemu).

This patch introduces two new database entries, 'vhost-sock-owner' to set the
ownership, and 'vhost-sock-perms' to set the permissions bits for the
vhost_user sockets.  These settings apply to all vhost-user sockets.

Signed-off-by: Aaron Conole <aconole at redhat.com>
---
 INSTALL.DPDK.md      |  7 +++++++
 lib/netdev-dpdk.c    | 37 ++++++++++++++++++++++++++++++++++---
 vswitchd/vswitch.xml | 23 +++++++++++++++++++++++
 3 files changed, 64 insertions(+), 3 deletions(-)

diff --git a/INSTALL.DPDK.md b/INSTALL.DPDK.md
index 5407794..0cd4bfe 100644
--- a/INSTALL.DPDK.md
+++ b/INSTALL.DPDK.md
@@ -223,6 +223,13 @@ advanced install guide [INSTALL.DPDK-ADVANCED.md]
      * vhost-sock-dir
      Option to set the path to the vhost_user unix socket files.
 
+     * vhost-sock-owner
+     Option to set the owner of the vhost_user unix socket files.
+
+     * vhost-sock-perms
+     Option to set the file-system permissions of the vhost_user unix socket
+     files.
+
      NOTE: Changing any of these options requires restarting the ovs-vswitchd
      application.
 
diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
index 85b18fd..ffa62c9 100644
--- a/lib/netdev-dpdk.c
+++ b/lib/netdev-dpdk.c
@@ -32,6 +32,7 @@
 #include <getopt.h>
 #include <numaif.h>
 
+#include "chutil.h"
 #include "dirs.h"
 #include "dp-packet.h"
 #include "dpif-netdev.h"
@@ -141,6 +142,10 @@ BUILD_ASSERT_DECL((MAX_NB_MBUF / ROUND_DOWN_POW2(MAX_NB_MBUF/MIN_NB_MBUF))
 static char *cuse_dev_name = NULL;    /* Character device cuse_dev_name. */
 #endif
 static char *vhost_sock_dir = NULL;   /* Location of vhost-user sockets */
+static char *vhost_sock_def_owner = NULL; /* Default owner of vhost-user
+                                             sockets*/
+static char *vhost_sock_def_perms = NULL; /* Default permissions of
+                                             vhost-user sockets */
 
 #define VHOST_ENQ_RETRY_NUM 8
 
@@ -824,6 +829,23 @@ vhost_construct_helper(struct netdev *netdev) OVS_REQUIRES(dpdk_mutex)
 }
 
 static int
+vhost_set_permissions(struct netdev_dpdk *dev) OVS_REQUIRES(dpdk_mutex)
+{
+    int err = 0;
+    if (vhost_sock_def_owner &&
+        (err = ovs_chown_open_file(dev->vhost_id, vhost_sock_def_owner))) {
+        VLOG_ERR("vhost-user socket device ownership change failed.");
+    }
+
+    if (!err && vhost_sock_def_perms &&
+        (err = ovs_chmod_open_file(dev->vhost_id, vhost_sock_def_perms))) {
+        VLOG_ERR("vhost-user socket device permission change failed.");
+    }
+
+    return err;
+}
+
+static int
 netdev_dpdk_vhost_cuse_construct(struct netdev *netdev)
 {
     struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
@@ -879,6 +901,10 @@ netdev_dpdk_vhost_user_construct(struct netdev *netdev)
         err = vhost_construct_helper(netdev);
     }
 
+    if (!err) {
+        err = vhost_set_permissions(dev);
+    }
+
     ovs_mutex_unlock(&dpdk_mutex);
     return err;
 }
@@ -3221,8 +3247,8 @@ dpdk_init__(const struct smap *ovs_other_config)
     VLOG_INFO("DPDK Enabled, initializing");
 
 #ifdef VHOST_CUSE
-    if (process_vhost_flags("cuse-dev-name", xstrdup("vhost-net"),
-                            PATH_MAX, ovs_other_config, &cuse_dev_name)) {
+    process_vhost_flags("cuse-dev-name", xstrdup("vhost-net"),
+                        PATH_MAX, ovs_other_config, &cuse_dev_name);
 #else
     if (process_vhost_flags("vhost-sock-dir", xstrdup(ovs_rundir()),
                             NAME_MAX, ovs_other_config,
@@ -3246,9 +3272,14 @@ dpdk_init__(const struct smap *ovs_other_config)
         free(sock_dir_subcomponent);
     } else {
         vhost_sock_dir = sock_dir_subcomponent;
-#endif
     }
 
+    process_vhost_flags("vhost-sock-owner", NULL, NAME_MAX, ovs_other_config,
+                        &vhost_sock_def_owner);
+    process_vhost_flags("vhost-sock-perms", NULL, NAME_MAX, ovs_other_config,
+                        &vhost_sock_def_perms);
+#endif
+
     argv = grow_argv(&argv, 0, 1);
     argc = 1;
     argv[0] = xstrdup(ovs_get_program_name());
diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml
index fed6f56..05d2a14 100644
--- a/vswitchd/vswitch.xml
+++ b/vswitchd/vswitch.xml
@@ -311,6 +311,29 @@
         </p>
       </column>
 
+      <column name="other_config" key="vhost-sock-owner"
+              type='{"type": "string"}'>
+        <p>
+          Specifies the owner of the vhost-user unix domain socket files.
+        </p>
+        <p>
+          The default is to inherit from the running user and group id's. The
+          argument is specified in the same form as the 'chown' unix utility.
+        </p>
+      </column>
+
+      <column name="other_config" key="vhost-sock-perms"
+              type='{"type": "string"}'>
+        <p>
+          Specifies the permissions for the vhost-user unix domain socket
+          files.
+        </p>
+        <p>
+          The default is derived from the running mask. The argument is
+          specified in the same form as the 'chmod' unix utility.
+        </p>
+      </column>
+
       <column name="other_config" key="n-handler-threads"
               type='{"type": "integer", "minInteger": 1}'>
         <p>
-- 
2.5.5