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33dccbb050
Unlike a normal socket path, the tuntap device send path does not have any accounting. This means that the user-space sender may be able to pin down arbitrary amounts of kernel memory by continuing to send data to an end-point that is congested. Even when this isn't an issue because of limited queueing at most end points, this can also be a problem because its only response to congestion is packet loss. That is, when those local queues at the end-point fills up, the tuntap device will start wasting system time because it will continue to send data there which simply gets dropped straight away. Of course one could argue that everybody should do congestion control end-to-end, unfortunately there are people in this world still hooked on UDP, and they don't appear to be going away anywhere fast. In fact, we've always helped them by performing accounting in our UDP code, the sole purpose of which is to provide congestion feedback other than through packet loss. This patch attempts to apply the same bandaid to the tuntap device. It creates a pseudo-socket object which is used to account our packets just as a normal socket does for UDP. Of course things are a little complex because we're actually reinjecting traffic back into the stack rather than out of the stack. The stack complexities however should have been resolved by preceding patches. So this one can simply start using skb_set_owner_w. For now the accounting is essentially disabled by default for backwards compatibility. In particular, we set the cap to INT_MAX. This is so that existing applications don't get confused by the sudden arrival EAGAIN errors. In future we may wish (or be forced to) do this by default. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
88 lines
2.8 KiB
C
88 lines
2.8 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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#include <linux/if_ether.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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#define TUN_VNET_HDR 0x0200
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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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#define TUNSETOFFLOAD _IOW('T', 208, unsigned int)
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#define TUNSETTXFILTER _IOW('T', 209, unsigned int)
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#define TUNGETIFF _IOR('T', 210, unsigned int)
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#define TUNGETSNDBUF _IOR('T', 211, int)
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#define TUNSETSNDBUF _IOW('T', 212, 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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#define IFF_VNET_HDR 0x4000
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/* Features for GSO (TUNSETOFFLOAD). */
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#define TUN_F_CSUM 0x01 /* You can hand me unchecksummed packets. */
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#define TUN_F_TSO4 0x02 /* I can handle TSO for IPv4 packets */
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#define TUN_F_TSO6 0x04 /* I can handle TSO for IPv6 packets */
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#define TUN_F_TSO_ECN 0x08 /* I can handle TSO with ECN bits. */
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/* Protocol info prepended to the packets (when IFF_NO_PI is not set) */
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#define TUN_PKT_STRIP 0x0001
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struct tun_pi {
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__u16 flags;
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__be16 proto;
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};
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/*
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* Filter spec (used for SETXXFILTER ioctls)
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* This stuff is applicable only to the TAP (Ethernet) devices.
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* If the count is zero the filter is disabled and the driver accepts
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* all packets (promisc mode).
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* If the filter is enabled in order to accept broadcast packets
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* broadcast addr must be explicitly included in the addr list.
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*/
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#define TUN_FLT_ALLMULTI 0x0001 /* Accept all multicast packets */
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struct tun_filter {
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__u16 flags; /* TUN_FLT_ flags see above */
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__u16 count; /* Number of addresses */
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__u8 addr[0][ETH_ALEN];
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};
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#endif /* __IF_TUN_H */
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