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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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f85ba78068
When creating a certain types of VPN, NetworkManager will first attempt to find an available tun device by iterating through 'vpn%d' until it finds one that isn't already busy. Then it'll set that to be persistent and owned by the otherwise unprivileged user that the VPN dæmon itself runs as. There's a race condition here -- during the period where the vpn%d device is created and we're waiting for the VPN dæmon to actually connect and use it, if we try to create _another_ device we could end up re-using the same one -- because trying to open it again doesn't get -EBUSY as it would while it's _actually_ busy. So solve this, we add an IFF_TUN_EXCL flag which causes tun_set_iff() to fail if it would be opening an existing persistent tundevice -- so that we can make sure we're getting an entirely _new_ device. Signed-off-by: David Woodhouse <David.Woodhouse@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
89 lines
2.8 KiB
C
89 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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#define IFF_TUN_EXCL 0x8000
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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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