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Commit 93e14b6d authored by Masatake YAMATO's avatar Masatake YAMATO Committed by David S. Miller
Browse files

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



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: default avatarMasatake YAMATO <yamato@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 52efcea5

drivers/net/tun.c

+26 −1
Original line number Diff line number Diff line
@@ -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 = {