[PATCH] uml: close TUN/TAP file descriptors

When UML opens a TUN/TAP device, the file descriptor could be copied into
later, long-lived threads, holding the device open even after the interface is
taken down, preventing it from being brought up again.  This patch makes these
descriptors close-on-exec so that they disappear from helper processes, and
adds CLONE_FILES to a UML helper thread so that the descriptors are closed in
the thread when they are closed elsewhere in UML.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/arch/um/os-Linux/drivers/tuntap_user.c b/arch/um/os-Linux/drivers/tuntap_user.c
index 52945338b64d..87c3aa0252db 100644
--- a/arch/um/os-Linux/drivers/tuntap_user.c
+++ b/arch/um/os-Linux/drivers/tuntap_user.c
@@ -122,6 +122,7 @@ static int tuntap_open_tramp(char *gate, int *fd_out, int me, int remote,
                 return(-EINVAL);
         }
         *fd_out = ((int *) CMSG_DATA(cmsg))[0];
+        os_set_exec_close(*fd_out, 1);
         return(0);
 }
 
@@ -137,7 +138,8 @@ static int tuntap_open(void *data)
                 return(err);
 
         if(pri->fixed_config){
-                pri->fd = os_open_file("/dev/net/tun", of_rdwr(OPENFLAGS()), 0);
+                pri->fd = os_open_file("/dev/net/tun",
+                                       of_cloexec(of_rdwr(OPENFLAGS())), 0);
                 if(pri->fd < 0){
                         printk("Failed to open /dev/net/tun, err = %d\n",
                                -pri->fd);