07240fd090
The problem with introducing checksum offload and gso to tun is they
need to set dev->features to enable GSO and/or checksumming, which is
supposed to be done before register_netdevice(), ie. as part of
TUNSETIFF.
Unfortunately, TUNSETIFF has always just ignored flags it doesn't
understand, so there's no good way of detecting whether the kernel
supports new IFF_ flags.
This patch implements a TUNGETFEATURES ioctl which returns all the valid IFF
flags. It could be extended later to include other features.
Here's an example program which uses it:
#include <linux/if_tun.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <err.h>
#include <stdio.h>
static struct {
unsigned int flag;
const char *name;
} known_flags[] = {
{ IFF_TUN, "TUN" },
{ IFF_TAP, "TAP" },
{ IFF_NO_PI, "NO_PI" },
{ IFF_ONE_QUEUE, "ONE_QUEUE" },
};
int main()
{
unsigned int features, i;
int netfd = open("/dev/net/tun", O_RDWR);
if (netfd < 0)
err(1, "Opening /dev/net/tun");
if (ioctl(netfd, TUNGETFEATURES, &features) != 0) {
printf("Kernel does not support TUNGETFEATURES, guessing\n");
features = (IFF_TUN|IFF_TAP|IFF_NO_PI|IFF_ONE_QUEUE);
}
printf("Available features are: ");
for (i = 0; i < sizeof(known_flags)/sizeof(known_flags[0]); i++) {
if (features & known_flags[i].flag) {
features &= ~known_flags[i].flag;
printf("%s ", known_flags[i].name);
}
}
if (features)
printf("(UNKNOWN %#x)", features);
printf("\n");
return 0;
}
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Max Krasnyansky <maxk@qualcomm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
57 lines
1.6 KiB
C
57 lines
1.6 KiB
C
/*
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* Universal TUN/TAP device driver.
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* Copyright (C) 1999-2000 Maxim Krasnyansky <max_mk@yahoo.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#ifndef __IF_TUN_H
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#define __IF_TUN_H
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#include <linux/types.h>
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/* Read queue size */
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#define TUN_READQ_SIZE 500
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/* TUN device flags */
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#define TUN_TUN_DEV 0x0001
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#define TUN_TAP_DEV 0x0002
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#define TUN_TYPE_MASK 0x000f
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#define TUN_FASYNC 0x0010
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#define TUN_NOCHECKSUM 0x0020
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#define TUN_NO_PI 0x0040
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#define TUN_ONE_QUEUE 0x0080
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#define TUN_PERSIST 0x0100
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/* Ioctl defines */
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#define TUNSETNOCSUM _IOW('T', 200, int)
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#define TUNSETDEBUG _IOW('T', 201, int)
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#define TUNSETIFF _IOW('T', 202, int)
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#define TUNSETPERSIST _IOW('T', 203, int)
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#define TUNSETOWNER _IOW('T', 204, int)
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#define TUNSETLINK _IOW('T', 205, int)
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#define TUNSETGROUP _IOW('T', 206, int)
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#define TUNGETFEATURES _IOR('T', 207, unsigned int)
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/* TUNSETIFF ifr flags */
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#define IFF_TUN 0x0001
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#define IFF_TAP 0x0002
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#define IFF_NO_PI 0x1000
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#define IFF_ONE_QUEUE 0x2000
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struct tun_pi {
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unsigned short flags;
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__be16 proto;
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};
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#define TUN_PKT_STRIP 0x0001
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#endif /* __IF_TUN_H */
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