Let AF_UNIX connections through the sandbox

Fixes bug 15003; bugfix on 0.2.6.3-alpha.

changes/bug15003

@@ -0,0 +1,3 @@
+  o Major bugfixes (linux seccomp2 sandbox):
+    - Allow AF_UNIX hidden services to be used with the seccomp2 sandbox.
+      Fixes bug 15003; bugfix on 0.2.6.3-alpha.

src/common/sandbox.c

@@ -542,6 +542,11 @@ sb_socket(scmp_filter_ctx ctx, sandbox_cfg_t *filter)
       return rc;
   }
 
+  rc = seccomp_rule_add_3(ctx, SCMP_ACT_ALLOW, SCMP_SYS(socket),
+      SCMP_CMP(0, SCMP_CMP_EQ, PF_UNIX),
+      SCMP_CMP_MASKED(1, SOCK_CLOEXEC|SOCK_NONBLOCK, SOCK_STREAM),
+      SCMP_CMP(2, SCMP_CMP_EQ, 0));
+
   rc = seccomp_rule_add_3(ctx, SCMP_ACT_ALLOW, SCMP_SYS(socket),
       SCMP_CMP(0, SCMP_CMP_EQ, PF_NETLINK),
       SCMP_CMP(1, SCMP_CMP_EQ, SOCK_RAW),