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Commit 1d2ddcfb authored by Jeff Dike's avatar Jeff Dike Committed by Linus Torvalds
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[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: default avatarJeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent fbd55779

arch/um/drivers/chan_user.c

+7 −8
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ 
#include <termios.h>

#include <string.h>

#include <signal.h>

#include <sched.h>

#include <sys/stat.h>

#include <sys/ioctl.h>

#include <sys/socket.h>
@@ -73,7 +74,6 @@ static void winch_handler(int sig) 
struct winch_data {

	int pty_fd;

	int pipe_fd;

	int close_me;

};



static int winch_thread(void *arg)
@@ -84,7 +84,6 @@ static int winch_thread(void *arg) 
	int count, err;

	char c = 1;



	os_close_file(data->close_me);

	pty_fd = data->pty_fd;

	pipe_fd = data->pipe_fd;

	count = os_write_file(pipe_fd, &c, sizeof(c));
@@ -153,15 +152,16 @@ static int winch_tramp(int fd, struct tty_struct *tty, int *fd_out) 
	}



	data = ((struct winch_data) { .pty_fd 		= fd,

				      .pipe_fd 		= fds[1],

				      .close_me 	= fds[0] } );

	err = run_helper_thread(winch_thread, &data, 0, &stack, 0);

				      .pipe_fd 		= fds[1] } );

	/* CLONE_FILES so this thread doesn't hold open files which are open

	 * now, but later closed.  This is a problem with /dev/net/tun.

	 */

	err = run_helper_thread(winch_thread, &data, CLONE_FILES, &stack, 0);

	if(err < 0){

		printk("fork of winch_thread failed - errno = %d\n", errno);

		goto out_close;

	}



	os_close_file(fds[1]);

	*fd_out = fds[0];

	n = os_read_file(fds[0], &c, sizeof(c));

	if(n != sizeof(c)){
@@ -169,13 +169,12 @@ static int winch_tramp(int fd, struct tty_struct *tty, int *fd_out) 
		printk("read failed, err = %d\n", -n);

		printk("fd %d will not support SIGWINCH\n", fd);

                err = -EINVAL;

		goto out_close1;

		goto out_close;

	}

	return err ;



 out_close:

	os_close_file(fds[1]);

 out_close1:

	os_close_file(fds[0]);

 out:

	return err;

arch/um/os-Linux/drivers/tuntap_user.c

+3 −1
Original line number Diff line number Diff line
@@ -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);