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tun: add device name(iff) field to proc fdinfo entry

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A file descriptor opened for /dev/net/tun and a tun device are
connected with ioctl.  Though understanding the connection is
important for trouble shooting, no way is given to a user to know
the connected device for a given file descriptor at userland.

This patch adds a new fdinfo field for the device name connected to
a file descriptor opened for /dev/net/tun.

Here is an example of the field:

    # lsof | grep tun
    qemu-syst 4565         qemu   25u      CHR             10,200       0t138      12921 /dev/net/tun
    ...

    # cat /proc/4565/fdinfo/25
    pos:	138
    flags:	0104002
    iff:	vnet0

    # ip link show dev vnet0
    8: vnet0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 ...

changelog:

    v2: indent iff just like the other fdinfo fields are.
    v3: remove unused variable.
        Both are suggested by David Miller <davem@davemloft.net>.

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Masatake YAMATO 2014-01-29 16:43:31 +09:00 committed by David S. Miller
parent 52efcea59e
commit 93e14b6d77
1 changed files with 26 additions and 1 deletions
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27
drivers/net/tun.c
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@ -69,6 +69,7 @@
#include <net/netns/generic.h>
#include <net/rtnetlink.h>
#include <net/sock.h>
#include <linux/seq_file.h>
#include <asm/uaccess.h>
@ -2228,6 +2229,27 @@ static int tun_chr_close(struct inode *inode, struct file *file)
return 0;
}
#ifdef CONFIG_PROC_FS
static int tun_chr_show_fdinfo(struct seq_file *m, struct file *f)
{
struct tun_struct *tun;
struct ifreq ifr;
memset(&ifr, 0, sizeof(ifr));
rtnl_lock();
tun = tun_get(f);
if (tun)
tun_get_iff(current->nsproxy->net_ns, tun, &ifr);
rtnl_unlock();
if (tun)
tun_put(tun);
return seq_printf(m, "iff:\t%s\n", ifr.ifr_name);
}
#endif
static const struct file_operations tun_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
@ -2242,7 +2264,10 @@ static const struct file_operations tun_fops = {
#endif
.open = tun_chr_open,
.release = tun_chr_close,
.fasync = tun_chr_fasync
.fasync = tun_chr_fasync,
#ifdef CONFIG_PROC_FS
.show_fdinfo = tun_chr_show_fdinfo,
#endif
};
static struct miscdevice tun_miscdev = {