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 <[email protected]>
Index: linux-2.6.15/arch/um/drivers/chan_user.c
===================================================================
--- linux-2.6.15.orig/arch/um/drivers/chan_user.c 2006-01-03 17:39:46.000000000 -0500
+++ linux-2.6.15/arch/um/drivers/chan_user.c 2006-02-06 17:35:47.000000000 -0500
@@ -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 tt
}
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 tt
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;
Index: linux-2.6.15/arch/um/os-Linux/drivers/tuntap_user.c
===================================================================
--- linux-2.6.15.orig/arch/um/os-Linux/drivers/tuntap_user.c 2006-01-03 17:39:46.000000000 -0500
+++ linux-2.6.15/arch/um/os-Linux/drivers/tuntap_user.c 2006-02-06 17:35:47.000000000 -0500
@@ -122,6 +122,7 @@ static int tuntap_open_tramp(char *gate,
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);
-
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