Add option to create clib_socket with group write permissions

Also allow group write as default for CLI socket connections.

Change-Id: I6af1f277f70581358cd9241bf0f5cb0752fe250f
Signed-off-by: Damjan Marion <damarion@cisco.com>
diff --git a/src/vlib/unix/cli.c b/src/vlib/unix/cli.c
index 74dea16..953d133 100644
--- a/src/vlib/unix/cli.c
+++ b/src/vlib/unix/cli.c
@@ -57,6 +57,8 @@
 #include <unistd.h>
 #include <arpa/telnet.h>
 #include <sys/ioctl.h>
+#include <sys/types.h>
+#include <unistd.h>
 
 /** ANSI escape code. */
 #define ESC "\x1b"
@@ -2640,7 +2642,8 @@
       /* CLI listen. */
       unix_file_t template = { 0 };
 
-      s->flags = SOCKET_IS_SERVER;	/* listen, don't connect */
+      s->flags = SOCKET_IS_SERVER |	/* listen, don't connect */
+	SOCKET_ALLOW_GROUP_WRITE;	/* PF_LOCAL socket only */
       error = clib_socket_init (s);
 
       if (error)
diff --git a/src/vppinfra/socket.c b/src/vppinfra/socket.c
index 99b353f..4c23c23 100644
--- a/src/vppinfra/socket.c
+++ b/src/vppinfra/socket.c
@@ -38,6 +38,7 @@
 #include <sys/un.h>
 #include <sys/types.h>
 #include <sys/socket.h>
+#include <sys/stat.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include <netdb.h>
@@ -348,6 +349,14 @@
 	  error = clib_error_return_unix (0, "listen");
 	  goto done;
 	}
+      if (addr.sa.sa_family == PF_LOCAL
+	  && s->flags & SOCKET_ALLOW_GROUP_WRITE)
+	{
+	  struct stat st = { 0 };
+	  stat (((struct sockaddr_un *) &addr)->sun_path, &st);
+	  st.st_mode |= S_IWGRP;
+	  chmod (((struct sockaddr_un *) &addr)->sun_path, st.st_mode);
+	}
     }
   else
     {
diff --git a/src/vppinfra/socket.h b/src/vppinfra/socket.h
index 08e22e7..7503720 100644
--- a/src/vppinfra/socket.h
+++ b/src/vppinfra/socket.h
@@ -58,6 +58,7 @@
 #define SOCKET_IS_SERVER (1 << 0)
 #define SOCKET_IS_CLIENT (0 << 0)
 #define SOCKET_NON_BLOCKING_CONNECT (1 << 1)
+#define SOCKET_ALLOW_GROUP_WRITE (1 << 2)
 
   /* Read returned end-of-file. */
 #define SOCKET_RX_END_OF_FILE (1 << 2)