net: test for not too small csum_start in virtio_net_hdr_to_skb()

syzbot was able to trigger this warning [1], after injecting a
malicious packet through af_packet, setting skb->csum_start and thus

net: test for not too small csum_start in virtio_net_hdr_to_skb()

syzbot was able to trigger this warning [1], after injecting a
malicious packet through af_packet, setting skb->csum_start and thus
the transport header to an incorrect value.

We can at least make sure the transport header is after
the end of the network header (with a estimated minimal size).

[1]
[ 67.873027] skb len=4096 headroom=16 headlen=14 tailroom=0
mac=(-1,-1) mac_len=0 net=(16,-6) trans=10
shinfo(txflags=0 nr_frags=1 gso(size=0 type=0 segs=0))
csum(0xa start=10 offset=0 ip_summed=3 complete_sw=0 valid=0 level=0)
hash(0x0 sw=0 l4=0) proto=0x0800 pkttype=0 iif=0
priority=0x0 mark=0x0 alloc_cpu=10 vlan_all=0x0
encapsulation=0 inner(proto=0x0000, mac=0, net=0, trans=0)
[ 67.877172] dev name=veth0_vlan feat=0x000061164fdd09e9
[ 67.877764] sk family=17 type=3 proto=0
[ 67.878279] skb linear: 00000000: 00 00 10 00 00 00 00 00 0f 00 00 00 08 00
[ 67.879128] skb frag: 00000000: 0e 00 07 00 00 00 28 00 08 80 1c 00 04 00 00 02
[ 67.879877] skb frag: 00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[ 67.880647] skb frag: 00000020: 00 00 02 00 00 00 08 00 1b 00 00 00 00 00 00 00
[ 67.881156] skb frag: 00000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[ 67.881753] skb frag: 00000040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[ 67.882173] skb frag: 00000050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[ 67.882790] skb frag: 00000060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[ 67.883171] skb frag: 00000070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[ 67.883733] skb frag: 00000080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[ 67.884206] skb frag: 00000090: 00 00 00 00 00 00 00 00 00 00 69 70 76 6c 61 6e
[ 67.884704] skb frag: 000000a0: 31 00 00 00 00 00 00 00 00 00 2b 00 00 00 00 00
[ 67.885139] skb frag: 000000b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[ 67.885677] skb frag: 000000c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[ 67.886042] skb frag: 000000d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[ 67.886408] skb frag: 000000e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[ 67.887020] skb frag: 000000f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[ 67.887384] skb frag: 00000100: 00 00
[ 67.887878] ------------[ cut here ]------------
[ 67.887908] offset (-6) >= skb_headlen() (14)
[ 67.888445] WARNING: CPU: 10 PID: 2088 at net/core/dev.c:3332 skb_checksum_help (net/core/dev.c:3332 (discriminator 2))
[ 67.889353] Modules linked in: macsec macvtap macvlan hsr wireguard curve25519_x86_64 libcurve25519_generic libchacha20poly1305 chacha_x86_64 libchacha poly1305_x86_64 dummy bridge sr_mod cdrom evdev pcspkr i2c_piix4 9pnet_virtio 9p 9pnet netfs
[ 67.890111] CPU: 10 UID: 0 PID: 2088 Comm: b363492833 Not tainted 6.11.0-virtme #1011
[ 67.890183] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[ 67.890309] RIP: 0010:skb_checksum_help (net/core/dev.c:3332 (discriminator 2))
[ 67.891043] Call Trace:
[ 67.891173] <TASK>
[ 67.891274] ? __warn (kernel/panic.c:741)
[ 67.891320] ? skb_checksum_help (net/core/dev.c:3332 (discriminator 2))
[ 67.891333] ? report_bug (lib/bug.c:180 lib/bug.c:219)
[ 67.891348] ? handle_bug (arch/x86/kernel/traps.c:239)
[ 67.891363] ? exc_invalid_op (arch/x86/kernel/traps.c:260 (discriminator 1))
[ 67.891372] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:621)
[ 67.891388] ? skb_checksum_help (net/core/dev.c:3332 (discriminator 2))
[ 67.891399] ? skb_checksum_help (net/core/dev.c:3332 (discriminator 2))
[ 67.891416] ip_do_fragment (net/ipv4/ip_output.c:777 (discriminator 1))
[ 67.891448] ? __ip_local_out (./include/linux/skbuff.h:1146 ./include/net/l3mdev.h:196 ./include/net/l3mdev.h:213 net/ipv4/ip_output.c:113)
[ 67.891459] ? __pfx_ip_finish_output2 (net/ipv4/ip_output.c:200)
[ 67.891470] ? ip_route_output_flow (./arch/x86/include/asm/preempt.h:84 (discriminator 13) ./include/linux/rcupdate.h:96 (discriminator 13) ./include/linux/rcupdate.h:871 (discriminator 13) net/ipv4/route.c:2625 (discriminator 13) ./include/net/route.h:141 (discriminator 13) net/ipv4/route.c:2852 (discriminator 13))
[ 67.891484] ipvlan_process_v4_outbound (drivers/net/ipvlan/ipvlan_core.c:445 (discriminator 1))
[ 67.891581] ipvlan_queue_xmit (drivers/net/ipvlan/ipvlan_core.c:542 drivers/net/ipvlan/ipvlan_core.c:604 drivers/net/ipvlan/ipvlan_core.c:670)
[ 67.891596] ipvlan_start_xmit (drivers/net/ipvlan/ipvlan_main.c:227)
[ 67.891607] dev_hard_start_xmit (./include/linux/netdevice.h:4916 ./include/linux/netdevice.h:4925 net/core/dev.c:3588 net/core/dev.c:3604)
[ 67.891620] __dev_queue_xmit (net/core/dev.h:168 (discriminator 25) net/core/dev.c:4425 (discriminator 25))
[ 67.891630] ? skb_copy_bits (./include/linux/uaccess.h:233 (discriminator 1) ./include/linux/uaccess.h:260 (discriminator 1) ./include/linux/highmem-internal.h:230 (discriminator 1) net/core/skbuff.c:3018 (discriminator 1))
[ 67.891645] ? __pskb_pull_tail (net/core/skbuff.c:2848 (discriminator 4))
[ 67.891655] ? skb_partial_csum_set (net/core/skbuff.c:5657)
[ 67.891666] ? virtio_net_hdr_to_skb.constprop.0 (./include/linux/skbuff.h:2791 (discriminator 3) ./include/linux/skbuff.h:2799 (discriminator 3) ./include/linux/virtio_net.h:109 (discriminator 3))
[ 67.891684] packet_sendmsg (net/packet/af_packet.c:3145 (discriminator 1) net/packet/af_packet.c:3177 (discriminator 1))
[ 67.891700] ? _raw_spin_lock_bh (./arch/x86/include/asm/atomic.h:107 (discriminator 4) ./include/linux/atomic/atomic-arch-fallback.h:2170 (discriminator 4) ./include/linux/atomic/atomic-instrumented.h:1302 (discriminator 4) ./include/asm-generic/qspinlock.h:111 (discriminator 4) ./include/linux/spinlock.h:187 (discriminator 4) ./include/linux/spinlock_api_smp.h:127 (discriminator 4) kernel/locking/spinlock.c:178 (discriminator 4))
[ 67.891716] __sys_sendto (net/socket.c:730 (discriminator 1) net/socket.c:745 (discriminator 1) net/socket.c:2210 (discriminator 1))
[ 67.891734] ? do_sock_setsockopt (net/socket.c:2335)
[ 67.891747] ? __sys_setsockopt (./include/linux/file.h:34 net/socket.c:2355)
[ 67.891761] __x64_sys_sendto (net/socket.c:2222 (discriminator 1) net/socket.c:2218 (discriminator 1) net/socket.c:2218 (discriminator 1))
[ 67.891772] do_syscall_64 (arch/x86/entry/common.c:52 (discriminator 1) arch/x86/entry/common.c:83 (discriminator 1))
[ 67.891785] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)

Fixes: 9181d6f8a2bb ("net: add more sanity check in virtio_net_hdr_to_skb()")
Signed-off-by: Eric Dumazet <[email protected]>
Reviewed-by: Willem de Bruijn <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

net: tighten bad gso csum offset check in virtio_net_hdr

The referenced commit drops bad input, but has false positives.
Tighten the check to avoid these.

The check detects illegal checksum offload

net: tighten bad gso csum offset check in virtio_net_hdr

The referenced commit drops bad input, but has false positives.
Tighten the check to avoid these.

The check detects illegal checksum offload requests, which produce
csum_start/csum_off beyond end of packet after segmentation.

But it is based on two incorrect assumptions:

1. virtio_net_hdr_to_skb with VIRTIO_NET_HDR_GSO_TCP[46] implies GSO.
True in callers that inject into the tx path, such as tap.
But false in callers that inject into rx, like virtio-net.
Here, the flags indicate GRO, and CHECKSUM_UNNECESSARY or
CHECKSUM_NONE without VIRTIO_NET_HDR_F_NEEDS_CSUM is normal.

2. TSO requires checksum offload, i.e., ip_summed == CHECKSUM_PARTIAL.
False, as tcp[46]_gso_segment will fix up csum_start and offset for
all other ip_summed by calling __tcp_v4_send_check.

Because of 2, we can limit the scope of the fix to virtio_net_hdr
that do try to set these fields, with a bogus value.

Link: https://lore.kernel.org/netdev/[email protected]/
Fixes: 89add40066f9 ("net: drop bad gso csum_start and offset in virtio_net_hdr")
Signed-off-by: Willem de Bruijn <[email protected]>
Acked-by: Jason Wang <[email protected]>
Acked-by: Michael S. Tsirkin <[email protected]>
Cc: [email protected]
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

net: drop bad gso csum_start and offset in virtio_net_hdr

Tighten csum_start and csum_offset checks in virtio_net_hdr_to_skb
for GSO packets.

The function already checks that a checksum requested w

net: drop bad gso csum_start and offset in virtio_net_hdr

Tighten csum_start and csum_offset checks in virtio_net_hdr_to_skb
for GSO packets.

The function already checks that a checksum requested with
VIRTIO_NET_HDR_F_NEEDS_CSUM is in skb linear. But for GSO packets
this might not hold for segs after segmentation.

Syzkaller demonstrated to reach this warning in skb_checksum_help

offset = skb_checksum_start_offset(skb);
ret = -EINVAL;
if (WARN_ON_ONCE(offset >= skb_headlen(skb)))

By injecting a TSO packet:

WARNING: CPU: 1 PID: 3539 at net/core/dev.c:3284 skb_checksum_help+0x3d0/0x5b0
ip_do_fragment+0x209/0x1b20 net/ipv4/ip_output.c:774
ip_finish_output_gso net/ipv4/ip_output.c:279 [inline]
__ip_finish_output+0x2bd/0x4b0 net/ipv4/ip_output.c:301
iptunnel_xmit+0x50c/0x930 net/ipv4/ip_tunnel_core.c:82
ip_tunnel_xmit+0x2296/0x2c70 net/ipv4/ip_tunnel.c:813
__gre_xmit net/ipv4/ip_gre.c:469 [inline]
ipgre_xmit+0x759/0xa60 net/ipv4/ip_gre.c:661
__netdev_start_xmit include/linux/netdevice.h:4850 [inline]
netdev_start_xmit include/linux/netdevice.h:4864 [inline]
xmit_one net/core/dev.c:3595 [inline]
dev_hard_start_xmit+0x261/0x8c0 net/core/dev.c:3611
__dev_queue_xmit+0x1b97/0x3c90 net/core/dev.c:4261
packet_snd net/packet/af_packet.c:3073 [inline]

The geometry of the bad input packet at tcp_gso_segment:

[ 52.003050][ T8403] skb len=12202 headroom=244 headlen=12093 tailroom=0
[ 52.003050][ T8403] mac=(168,24) mac_len=24 net=(192,52) trans=244
[ 52.003050][ T8403] shinfo(txflags=0 nr_frags=1 gso(size=1552 type=3 segs=0))
[ 52.003050][ T8403] csum(0x60000c7 start=199 offset=1536
ip_summed=3 complete_sw=0 valid=0 level=0)

Mitigate with stricter input validation.

csum_offset: for GSO packets, deduce the correct value from gso_type.
This is already done for USO. Extend it to TSO. Let UFO be:
udp[46]_ufo_fragment ignores these fields and always computes the
checksum in software.

csum_start: finding the real offset requires parsing to the transport
header. Do not add a parser, use existing segmentation parsing. Thanks
to SKB_GSO_DODGY, that also catches bad packets that are hw offloaded.
Again test both TSO and USO. Do not test UFO for the above reason, and
do not test UDP tunnel offload.

GSO packet are almost always CHECKSUM_PARTIAL. USO packets may be
CHECKSUM_NONE since commit 10154dbded6d6 ("udp: Allow GSO transmit
from devices with no checksum offload"), but then still these fields
are initialized correctly in udp4_hwcsum/udp6_hwcsum_outgoing. So no
need to test for ip_summed == CHECKSUM_PARTIAL first.

This revises an existing fix mentioned in the Fixes tag, which broke
small packets with GSO offload, as detected by kselftests.

Link: https://syzkaller.appspot.com/bug?extid=e1db31216c789f552871
Link: https://lore.kernel.org/netdev/[email protected]
Fixes: e269d79c7d35 ("net: missing check virtio")
Cc: [email protected]
Signed-off-by: Willem de Bruijn <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

net: missing check virtio

Two missing check in virtio_net_hdr_to_skb() allowed syzbot
to crash kernels again

1. After the skb_segment function the buffer may become non-linear
(nr_frags != 0), but

net: missing check virtio

Two missing check in virtio_net_hdr_to_skb() allowed syzbot
to crash kernels again

1. After the skb_segment function the buffer may become non-linear
(nr_frags != 0), but since the SKBTX_SHARED_FRAG flag is not set anywhere
the __skb_linearize function will not be executed, then the buffer will
remain non-linear. Then the condition (offset >= skb_headlen(skb))
becomes true, which causes WARN_ON_ONCE in skb_checksum_help.

2. The struct sk_buff and struct virtio_net_hdr members must be
mathematically related.
(gso_size) must be greater than (needed) otherwise WARN_ON_ONCE.
(remainder) must be greater than (needed) otherwise WARN_ON_ONCE.
(remainder) may be 0 if division is without remainder.

offset+2 (4191) > skb_headlen() (1116)
WARNING: CPU: 1 PID: 5084 at net/core/dev.c:3303 skb_checksum_help+0x5e2/0x740 net/core/dev.c:3303
Modules linked in:
CPU: 1 PID: 5084 Comm: syz-executor336 Not tainted 6.7.0-rc3-syzkaller-00014-gdf60cee26a2e #0
Hardware name: Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
RIP: 0010:skb_checksum_help+0x5e2/0x740 net/core/dev.c:3303
Code: 89 e8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 52 01 00 00 44 89 e2 2b 53 74 4c 89 ee 48 c7 c7 40 57 e9 8b e8 af 8f dd f8 90 <0f> 0b 90 90 e9 87 fe ff ff e8 40 0f 6e f9 e9 4b fa ff ff 48 89 ef
RSP: 0018:ffffc90003a9f338 EFLAGS: 00010286
RAX: 0000000000000000 RBX: ffff888025125780 RCX: ffffffff814db209
RDX: ffff888015393b80 RSI: ffffffff814db216 RDI: 0000000000000001
RBP: ffff8880251257f4 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 000000000000045c
R13: 000000000000105f R14: ffff8880251257f0 R15: 000000000000105d
FS: 0000555555c24380(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000002000f000 CR3: 0000000023151000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
ip_do_fragment+0xa1b/0x18b0 net/ipv4/ip_output.c:777
ip_fragment.constprop.0+0x161/0x230 net/ipv4/ip_output.c:584
ip_finish_output_gso net/ipv4/ip_output.c:286 [inline]
__ip_finish_output net/ipv4/ip_output.c:308 [inline]
__ip_finish_output+0x49c/0x650 net/ipv4/ip_output.c:295
ip_finish_output+0x31/0x310 net/ipv4/ip_output.c:323
NF_HOOK_COND include/linux/netfilter.h:303 [inline]
ip_output+0x13b/0x2a0 net/ipv4/ip_output.c:433
dst_output include/net/dst.h:451 [inline]
ip_local_out+0xaf/0x1a0 net/ipv4/ip_output.c:129
iptunnel_xmit+0x5b4/0x9b0 net/ipv4/ip_tunnel_core.c:82
ipip6_tunnel_xmit net/ipv6/sit.c:1034 [inline]
sit_tunnel_xmit+0xed2/0x28f0 net/ipv6/sit.c:1076
__netdev_start_xmit include/linux/netdevice.h:4940 [inline]
netdev_start_xmit include/linux/netdevice.h:4954 [inline]
xmit_one net/core/dev.c:3545 [inline]
dev_hard_start_xmit+0x13d/0x6d0 net/core/dev.c:3561
__dev_queue_xmit+0x7c1/0x3d60 net/core/dev.c:4346
dev_queue_xmit include/linux/netdevice.h:3134 [inline]
packet_xmit+0x257/0x380 net/packet/af_packet.c:276
packet_snd net/packet/af_packet.c:3087 [inline]
packet_sendmsg+0x24ca/0x5240 net/packet/af_packet.c:3119
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg+0xd5/0x180 net/socket.c:745
__sys_sendto+0x255/0x340 net/socket.c:2190
__do_sys_sendto net/socket.c:2202 [inline]
__se_sys_sendto net/socket.c:2198 [inline]
__x64_sys_sendto+0xe0/0x1b0 net/socket.c:2198
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

Found by Linux Verification Center (linuxtesting.org) with Syzkaller

Fixes: 0f6925b3e8da ("virtio_net: Do not pull payload in skb->head")
Signed-off-by: Denis Arefev <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Michael S. Tsirkin <[email protected]>

show more ...

net: add more sanity check in virtio_net_hdr_to_skb()

syzbot/KMSAN reports access to uninitialized data from gso_features_check() [1]

The repro use af_packet, injecting a gso packet and hdrlen == 0

net: add more sanity check in virtio_net_hdr_to_skb()

syzbot/KMSAN reports access to uninitialized data from gso_features_check() [1]

The repro use af_packet, injecting a gso packet and hdrlen == 0.

We could fix the issue making gso_features_check() more careful
while dealing with NETIF_F_TSO_MANGLEID in fast path.

Or we can make sure virtio_net_hdr_to_skb() pulls minimal network and
transport headers as intended.

Note that for GSO packets coming from untrusted sources, SKB_GSO_DODGY
bit forces a proper header validation (and pull) before the packet can
hit any device ndo_start_xmit(), thus we do not need a precise disection
at virtio_net_hdr_to_skb() stage.

[1]
BUG: KMSAN: uninit-value in skb_gso_segment include/net/gso.h:83 [inline]
BUG: KMSAN: uninit-value in validate_xmit_skb+0x10f2/0x1930 net/core/dev.c:3629
skb_gso_segment include/net/gso.h:83 [inline]
validate_xmit_skb+0x10f2/0x1930 net/core/dev.c:3629
__dev_queue_xmit+0x1eac/0x5130 net/core/dev.c:4341
dev_queue_xmit include/linux/netdevice.h:3134 [inline]
packet_xmit+0x9c/0x6b0 net/packet/af_packet.c:276
packet_snd net/packet/af_packet.c:3087 [inline]
packet_sendmsg+0x8b1d/0x9f30 net/packet/af_packet.c:3119
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
____sys_sendmsg+0x9c2/0xd60 net/socket.c:2584
___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638
__sys_sendmsg net/socket.c:2667 [inline]
__do_sys_sendmsg net/socket.c:2676 [inline]
__se_sys_sendmsg net/socket.c:2674 [inline]
__x64_sys_sendmsg+0x307/0x490 net/socket.c:2674
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

Uninit was created at:
slab_post_alloc_hook+0x129/0xa70 mm/slab.h:768
slab_alloc_node mm/slub.c:3478 [inline]
kmem_cache_alloc_node+0x5e9/0xb10 mm/slub.c:3523
kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:560
__alloc_skb+0x318/0x740 net/core/skbuff.c:651
alloc_skb include/linux/skbuff.h:1286 [inline]
alloc_skb_with_frags+0xc8/0xbd0 net/core/skbuff.c:6334
sock_alloc_send_pskb+0xa80/0xbf0 net/core/sock.c:2780
packet_alloc_skb net/packet/af_packet.c:2936 [inline]
packet_snd net/packet/af_packet.c:3030 [inline]
packet_sendmsg+0x70e8/0x9f30 net/packet/af_packet.c:3119
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
____sys_sendmsg+0x9c2/0xd60 net/socket.c:2584
___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638
__sys_sendmsg net/socket.c:2667 [inline]
__do_sys_sendmsg net/socket.c:2676 [inline]
__se_sys_sendmsg net/socket.c:2674 [inline]
__x64_sys_sendmsg+0x307/0x490 net/socket.c:2674
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

CPU: 0 PID: 5025 Comm: syz-executor279 Not tainted 6.7.0-rc7-syzkaller-00003-gfbafc3e621c3 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023

Reported-by: [email protected]
Link: https://lore.kernel.org/netdev/[email protected]/
Fixes: 9274124f023b ("net: stricter validation of untrusted gso packets")
Signed-off-by: Eric Dumazet <[email protected]>
Cc: Willem de Bruijn <[email protected]>
Reviewed-by: Willem de Bruijn <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

net: more strict VIRTIO_NET_HDR_GSO_UDP_L4 validation

Syzbot reported two new paths to hit an internal WARNING using the
new virtio gso type VIRTIO_NET_HDR_GSO_UDP_L4.

RIP: 0010:skb_checksum_he

net: more strict VIRTIO_NET_HDR_GSO_UDP_L4 validation

Syzbot reported two new paths to hit an internal WARNING using the
new virtio gso type VIRTIO_NET_HDR_GSO_UDP_L4.

RIP: 0010:skb_checksum_help+0x4a2/0x600 net/core/dev.c:3260
skb len=64521 gso_size=344
and

RIP: 0010:skb_warn_bad_offload+0x118/0x240 net/core/dev.c:3262

Older virtio types have historically had loose restrictions, leading
to many entirely impractical fuzzer generated packets causing
problems deep in the kernel stack. Ideally, we would have had strict
validation for all types from the start.

New virtio types can have tighter validation. Limit UDP GSO packets
inserted via virtio to the same limits imposed by the UDP_SEGMENT
socket interface:

1. must use checksum offload
2. checksum offload matches UDP header
3. no more segments than UDP_MAX_SEGMENTS
4. UDP GSO does not take modifier flags, notably SKB_GSO_TCP_ECN

Fixes: 860b7f27b8f7 ("linux/virtio_net.h: Support USO offload in vnet header.")
Reported-by: [email protected]
Closes: https://lore.kernel.org/netdev/[email protected]/
Reported-by: [email protected]
Closes: https://lore.kernel.org/netdev/[email protected]/
Signed-off-by: Willem de Bruijn <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Acked-by: Jason Wang <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

net: do not allow gso_size to be set to GSO_BY_FRAGS

One missing check in virtio_net_hdr_to_skb() allowed
syzbot to crash kernels again [1]

Do not allow gso_size to be set to GSO_BY_FRAGS (0xffff),

net: do not allow gso_size to be set to GSO_BY_FRAGS

One missing check in virtio_net_hdr_to_skb() allowed
syzbot to crash kernels again [1]

Do not allow gso_size to be set to GSO_BY_FRAGS (0xffff),
because this magic value is used by the kernel.

[1]
general protection fault, probably for non-canonical address 0xdffffc000000000e: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000070-0x0000000000000077]
CPU: 0 PID: 5039 Comm: syz-executor401 Not tainted 6.5.0-rc5-next-20230809-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
RIP: 0010:skb_segment+0x1a52/0x3ef0 net/core/skbuff.c:4500
Code: 00 00 00 e9 ab eb ff ff e8 6b 96 5d f9 48 8b 84 24 00 01 00 00 48 8d 78 70 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e ea 21 00 00 48 8b 84 24 00 01
RSP: 0018:ffffc90003d3f1c8 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 000000000001fffe RCX: 0000000000000000
RDX: 000000000000000e RSI: ffffffff882a3115 RDI: 0000000000000070
RBP: ffffc90003d3f378 R08: 0000000000000005 R09: 000000000000ffff
R10: 000000000000ffff R11: 5ee4a93e456187d6 R12: 000000000001ffc6
R13: dffffc0000000000 R14: 0000000000000008 R15: 000000000000ffff
FS: 00005555563f2380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020020000 CR3: 000000001626d000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
udp6_ufo_fragment+0x9d2/0xd50 net/ipv6/udp_offload.c:109
ipv6_gso_segment+0x5c4/0x17b0 net/ipv6/ip6_offload.c:120
skb_mac_gso_segment+0x292/0x610 net/core/gso.c:53
__skb_gso_segment+0x339/0x710 net/core/gso.c:124
skb_gso_segment include/net/gso.h:83 [inline]
validate_xmit_skb+0x3a5/0xf10 net/core/dev.c:3625
__dev_queue_xmit+0x8f0/0x3d60 net/core/dev.c:4329
dev_queue_xmit include/linux/netdevice.h:3082 [inline]
packet_xmit+0x257/0x380 net/packet/af_packet.c:276
packet_snd net/packet/af_packet.c:3087 [inline]
packet_sendmsg+0x24c7/0x5570 net/packet/af_packet.c:3119
sock_sendmsg_nosec net/socket.c:727 [inline]
sock_sendmsg+0xd9/0x180 net/socket.c:750
____sys_sendmsg+0x6ac/0x940 net/socket.c:2496
___sys_sendmsg+0x135/0x1d0 net/socket.c:2550
__sys_sendmsg+0x117/0x1e0 net/socket.c:2579
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7ff27cdb34d9

Fixes: 3953c46c3ac7 ("sk_buff: allow segmenting based on frag sizes")
Reported-by: syzbot <[email protected]>
Signed-off-by: Eric Dumazet <[email protected]>
Cc: Xin Long <[email protected]>
Cc: "Michael S. Tsirkin" <[email protected]>
Cc: Jason Wang <[email protected]>
Reviewed-by: Willem de Bruijn <[email protected]>
Reviewed-by: Marcelo Ricardo Leitner <[email protected]>
Reviewed-by: Xuan Zhuo <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

linux/virtio_net.h: Support USO offload in vnet header.

Now, it's possible to convert USO vnet packets from/to skb.
Added support for GSO_UDP_L4 offload.

Signed-off-by: Andrew Melnychenko <andrew@d

linux/virtio_net.h: Support USO offload in vnet header.

Now, it's possible to convert USO vnet packets from/to skb.
Added support for GSO_UDP_L4 offload.

Signed-off-by: Andrew Melnychenko <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

net: skip virtio_net_hdr_set_proto if protocol already set

virtio_net_hdr_set_proto infers skb->protocol from the virtio_net_hdr
gso_type, to avoid packets getting dropped for lack of a proto type.

net: skip virtio_net_hdr_set_proto if protocol already set

virtio_net_hdr_set_proto infers skb->protocol from the virtio_net_hdr
gso_type, to avoid packets getting dropped for lack of a proto type.

Its protocol choice is a guess, especially in the case of UFO, where
the single VIRTIO_NET_HDR_GSO_UDP label covers both UFOv4 and UFOv6.

Skip this best effort if the field is already initialized. Whether
explicitly from userspace, or implicitly based on an earlier call to
dev_parse_header_protocol (which is more robust, but was introduced
after this patch).

Fixes: 9d2f67e43b73 ("net/packet: fix packet drop as of virtio gso")
Signed-off-by: Willem de Bruijn <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

net: accept UFOv6 packages in virtio_net_hdr_to_skb

Skb with skb->protocol 0 at the time of virtio_net_hdr_to_skb may have
a protocol inferred from virtio_net_hdr with virtio_net_hdr_set_proto.

Unl

net: accept UFOv6 packages in virtio_net_hdr_to_skb

Skb with skb->protocol 0 at the time of virtio_net_hdr_to_skb may have
a protocol inferred from virtio_net_hdr with virtio_net_hdr_set_proto.

Unlike TCP, UDP does not have separate types for IPv4 and IPv6. Type
VIRTIO_NET_HDR_GSO_UDP is guessed to be IPv4/UDP. As of the below
commit, UFOv6 packets are dropped due to not matching the protocol as
obtained from dev_parse_header_protocol.

Invert the test to take that L2 protocol field as starting point and
pass both UFOv4 and UFOv6 for VIRTIO_NET_HDR_GSO_UDP.

Fixes: 924a9bc362a5 ("net: check if protocol extracted by virtio_net_hdr_set_proto is correct")
Link: https://lore.kernel.org/netdev/CABcq3pG9GRCYqFDBAJ48H1vpnnX=41u+MhQnayF1ztLH4WX0Fw@mail.gmail.com/
Reported-by: Andrew Melnichenko <[email protected]>
Signed-off-by: Willem de Bruijn <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

net: virtio_net_hdr_to_skb: count transport header in UFO

virtio_net_hdr_to_skb does not set the skb's gso_size and gso_type
correctly for UFO packets received via virtio-net that are a little over

net: virtio_net_hdr_to_skb: count transport header in UFO

virtio_net_hdr_to_skb does not set the skb's gso_size and gso_type
correctly for UFO packets received via virtio-net that are a little over
the GSO size. This can lead to problems elsewhere in the networking
stack, e.g. ovs_vport_send dropping over-sized packets if gso_size is
not set.

This is due to the comparison

if (skb->len - p_off > gso_size)

not properly accounting for the transport layer header.

p_off includes the size of the transport layer header (thlen), so
skb->len - p_off is the size of the TCP/UDP payload.

gso_size is read from the virtio-net header. For UFO, fragmentation
happens at the IP level so does not need to include the UDP header.

Hence the calculation could be comparing a TCP/UDP payload length with
an IP payload length, causing legitimate virtio-net packets to have
lack gso_type/gso_size information.

Example: a UDP packet with payload size 1473 has IP payload size 1481.
If the guest used UFO, it is not fragmented and the virtio-net header's
flags indicate that it is a GSO frame (VIRTIO_NET_HDR_GSO_UDP), with
gso_size = 1480 for an MTU of 1500. skb->len will be 1515 and p_off
will be 42, so skb->len - p_off = 1473. Hence the comparison fails, and
shinfo->gso_size and gso_type are not set as they should be.

Instead, add the UDP header length before comparing to gso_size when
using UFO. In this way, it is the size of the IP payload that is
compared to gso_size.

Fixes: 6dd912f82680 ("net: check untrusted gso_size at kernel entry")
Signed-off-by: Jonathan Davies <[email protected]>
Reviewed-by: Willem de Bruijn <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

virtio_net: Do not pull payload in skb->head

Xuan Zhuo reported that commit 3226b158e67c ("net: avoid 32 x truesize
under-estimation for tiny skbs") brought a ~10% performance drop.

The reason for

virtio_net: Do not pull payload in skb->head

Xuan Zhuo reported that commit 3226b158e67c ("net: avoid 32 x truesize
under-estimation for tiny skbs") brought a ~10% performance drop.

The reason for the performance drop was that GRO was forced
to chain sk_buff (using skb_shinfo(skb)->frag_list), which
uses more memory but also cause packet consumers to go over
a lot of overhead handling all the tiny skbs.

It turns out that virtio_net page_to_skb() has a wrong strategy :
It allocates skbs with GOOD_COPY_LEN (128) bytes in skb->head, then
copies 128 bytes from the page, before feeding the packet to GRO stack.

This was suboptimal before commit 3226b158e67c ("net: avoid 32 x truesize
under-estimation for tiny skbs") because GRO was using 2 frags per MSS,
meaning we were not packing MSS with 100% efficiency.

Fix is to pull only the ethernet header in page_to_skb()

Then, we change virtio_net_hdr_to_skb() to pull the missing
headers, instead of assuming they were already pulled by callers.

This fixes the performance regression, but could also allow virtio_net
to accept packets with more than 128bytes of headers.

Many thanks to Xuan Zhuo for his report, and his tests/help.

Fixes: 3226b158e67c ("net: avoid 32 x truesize under-estimation for tiny skbs")
Reported-by: Xuan Zhuo <[email protected]>
Link: https://www.spinics.net/lists/netdev/msg731397.html
Co-Developed-by: Xuan Zhuo <[email protected]>
Signed-off-by: Xuan Zhuo <[email protected]>
Signed-off-by: Eric Dumazet <[email protected]>
Cc: "Michael S. Tsirkin" <[email protected]>
Cc: Jason Wang <[email protected]>
Cc: [email protected]
Acked-by: Jason Wang <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

net: ensure mac header is set in virtio_net_hdr_to_skb()

Commit 924a9bc362a5 ("net: check if protocol extracted by virtio_net_hdr_set_proto is correct")
added a call to dev_parse_header_protocol() b

net: ensure mac header is set in virtio_net_hdr_to_skb()

Commit 924a9bc362a5 ("net: check if protocol extracted by virtio_net_hdr_set_proto is correct")
added a call to dev_parse_header_protocol() but mac_header is not yet set.

This means that eth_hdr() reads complete garbage, and syzbot complained about it [1]

This patch resets mac_header earlier, to get more coverage about this change.

Audit of virtio_net_hdr_to_skb() callers shows that this change should be safe.

[1]

BUG: KASAN: use-after-free in eth_header_parse_protocol+0xdc/0xe0 net/ethernet/eth.c:282
Read of size 2 at addr ffff888017a6200b by task syz-executor313/8409

CPU: 1 PID: 8409 Comm: syz-executor313 Not tainted 5.12.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack+0x141/0x1d7 lib/dump_stack.c:120
print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:232
__kasan_report mm/kasan/report.c:399 [inline]
kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416
eth_header_parse_protocol+0xdc/0xe0 net/ethernet/eth.c:282
dev_parse_header_protocol include/linux/netdevice.h:3177 [inline]
virtio_net_hdr_to_skb.constprop.0+0x99d/0xcd0 include/linux/virtio_net.h:83
packet_snd net/packet/af_packet.c:2994 [inline]
packet_sendmsg+0x2325/0x52b0 net/packet/af_packet.c:3031
sock_sendmsg_nosec net/socket.c:654 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:674
sock_no_sendpage+0xf3/0x130 net/core/sock.c:2860
kernel_sendpage.part.0+0x1ab/0x350 net/socket.c:3631
kernel_sendpage net/socket.c:3628 [inline]
sock_sendpage+0xe5/0x140 net/socket.c:947
pipe_to_sendpage+0x2ad/0x380 fs/splice.c:364
splice_from_pipe_feed fs/splice.c:418 [inline]
__splice_from_pipe+0x43e/0x8a0 fs/splice.c:562
splice_from_pipe fs/splice.c:597 [inline]
generic_splice_sendpage+0xd4/0x140 fs/splice.c:746
do_splice_from fs/splice.c:767 [inline]
do_splice+0xb7e/0x1940 fs/splice.c:1079
__do_splice+0x134/0x250 fs/splice.c:1144
__do_sys_splice fs/splice.c:1350 [inline]
__se_sys_splice fs/splice.c:1332 [inline]
__x64_sys_splice+0x198/0x250 fs/splice.c:1332
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46

Fixes: 924a9bc362a5 ("net: check if protocol extracted by virtio_net_hdr_set_proto is correct")
Signed-off-by: Eric Dumazet <[email protected]>
Cc: Balazs Nemeth <[email protected]>
Cc: Willem de Bruijn <[email protected]>
Reported-by: syzbot <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

net: check if protocol extracted by virtio_net_hdr_set_proto is correct

For gso packets, virtio_net_hdr_set_proto sets the protocol (if it isn't
set) based on the type in the virtio net hdr, but the

net: check if protocol extracted by virtio_net_hdr_set_proto is correct

For gso packets, virtio_net_hdr_set_proto sets the protocol (if it isn't
set) based on the type in the virtio net hdr, but the skb could contain
anything since it could come from packet_snd through a raw socket. If
there is a mismatch between what virtio_net_hdr_set_proto sets and
the actual protocol, then the skb could be handled incorrectly later
on.

An example where this poses an issue is with the subsequent call to
skb_flow_dissect_flow_keys_basic which relies on skb->protocol being set
correctly. A specially crafted packet could fool
skb_flow_dissect_flow_keys_basic preventing EINVAL to be returned.

Avoid blindly trusting the information provided by the virtio net header
by checking that the protocol in the packet actually matches the
protocol set by virtio_net_hdr_set_proto. Note that since the protocol
is only checked if skb->dev implements header_ops->parse_protocol,
packets from devices without the implementation are not checked at this
stage.

Fixes: 9274124f023b ("net: stricter validation of untrusted gso packets")
Signed-off-by: Balazs Nemeth <[email protected]>
Acked-by: Willem de Bruijn <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

net: be more gentle about silly gso requests coming from user

Recent change in virtio_net_hdr_to_skb() broke some packetdrill tests.

When --mss=XXX option is set, packetdrill always provide gso_typ

net: be more gentle about silly gso requests coming from user

Recent change in virtio_net_hdr_to_skb() broke some packetdrill tests.

When --mss=XXX option is set, packetdrill always provide gso_type & gso_size
for its inbound packets, regardless of packet size.

if (packet->tcp && packet->mss) {
if (packet->ipv4)
gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
else
gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
gso.gso_size = packet->mss;
}

Since many other programs could do the same, relax virtio_net_hdr_to_skb()
to no longer return an error, but instead ignore gso settings.

This keeps Willem intent to make sure no malicious packet could
reach gso stack.

Note that TCP stack has a special logic in tcp_set_skb_tso_segs()
to clear gso_size for small packets.

Fixes: 6dd912f82680 ("net: check untrusted gso_size at kernel entry")
Signed-off-by: Eric Dumazet <[email protected]>
Cc: Willem de Bruijn <[email protected]>
Acked-by: Willem de Bruijn <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

net: check untrusted gso_size at kernel entry

Syzkaller again found a path to a kernel crash through bad gso input:
a packet with gso size exceeding len.

These packets are dropped in tcp_gso_segmen

net: check untrusted gso_size at kernel entry

Syzkaller again found a path to a kernel crash through bad gso input:
a packet with gso size exceeding len.

These packets are dropped in tcp_gso_segment and udp[46]_ufo_fragment.
But they may affect gso size calculations earlier in the path.

Now that we have thlen as of commit 9274124f023b ("net: stricter
validation of untrusted gso packets"), check gso_size at entry too.

Fixes: bfd5f4a3d605 ("packet: Add GSO/csum offload support.")
Reported-by: syzbot <[email protected]>
Signed-off-by: Willem de Bruijn <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

net: stricter validation of untrusted gso packets

Syzkaller again found a path to a kernel crash through bad gso input:
a packet with transport header extending beyond skb_headlen(skb).

Tighten val

net: stricter validation of untrusted gso packets

Syzkaller again found a path to a kernel crash through bad gso input:
a packet with transport header extending beyond skb_headlen(skb).

Tighten validation at kernel entry:

- Verify that the transport header lies within the linear section.

To avoid pulling linux/tcp.h, verify just sizeof tcphdr.
tcp_gso_segment will call pskb_may_pull (th->doff * 4) before use.

- Match the gso_type against the ip_proto found by the flow dissector.

Fixes: bfd5f4a3d605 ("packet: Add GSO/csum offload support.")
Reported-by: syzbot <[email protected]>
Signed-off-by: Willem de Bruijn <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

net: Don't set transport offset to invalid value

If the socket was created with socket(AF_PACKET, SOCK_RAW, 0),
skb->protocol will be unset, __skb_flow_dissect() will fail, and
skb_probe_transport_h

net: Don't set transport offset to invalid value

If the socket was created with socket(AF_PACKET, SOCK_RAW, 0),
skb->protocol will be unset, __skb_flow_dissect() will fail, and
skb_probe_transport_header() will fall back to the offset_hint, making
the resulting skb_transport_offset incorrect.

If, however, there is no transport header in the packet,
transport_header shouldn't be set to an arbitrary value.

Fix it by leaving the transport offset unset if it couldn't be found, to
be explicit rather than to fill it with some wrong value. It changes the
behavior, but if some code relied on the old behavior, it would be
broken anyway, as the old one is incorrect.

Signed-off-by: Maxim Mikityanskiy <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

net: avoid false positives in untrusted gso validation

GSO packets with vnet_hdr must conform to a small set of gso_types.
The below commit uses flow dissection to drop packets that do not.

But it

net: avoid false positives in untrusted gso validation

GSO packets with vnet_hdr must conform to a small set of gso_types.
The below commit uses flow dissection to drop packets that do not.

But it has false positives when the skb is not fully initialized.
Dissection needs skb->protocol and skb->network_header.

Infer skb->protocol from gso_type as the two must agree.
SKB_GSO_UDP can use both ipv4 and ipv6, so try both.

Exclude callers for which network header offset is not known.

Fixes: d5be7f632bad ("net: validate untrusted gso packets without csum offload")
Signed-off-by: Willem de Bruijn <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

net: validate untrusted gso packets without csum offload

Syzkaller again found a path to a kernel crash through bad gso input.
By building an excessively large packet to cause an skb field to wrap.

net: validate untrusted gso packets without csum offload

Syzkaller again found a path to a kernel crash through bad gso input.
By building an excessively large packet to cause an skb field to wrap.

If VIRTIO_NET_HDR_F_NEEDS_CSUM was set this would have been dropped in
skb_partial_csum_set.

GSO packets that do not set checksum offload are suspicious and rare.
Most callers of virtio_net_hdr_to_skb already pass them to
skb_probe_transport_header.

Move that test forward, change it to detect parse failure and drop
packets on failure as those cleary are not one of the legitimate
VIRTIO_NET_HDR_GSO types.

Fixes: bfd5f4a3d605 ("packet: Add GSO/csum offload support.")
Fixes: f43798c27684 ("tun: Allow GSO using virtio_net_hdr")
Reported-by: syzbot <[email protected]>
Signed-off-by: Willem de Bruijn <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

net/packet: fix packet drop as of virtio gso

When we use raw socket as the vhost backend, a packet from virito with
gso offloading information, cannot be sent out in later validaton at
xmit path, as

net/packet: fix packet drop as of virtio gso

When we use raw socket as the vhost backend, a packet from virito with
gso offloading information, cannot be sent out in later validaton at
xmit path, as we did not set correct skb->protocol which is further used
for looking up the gso function.

To fix this, we set this field according to virito hdr information.

Fixes: e858fae2b0b8f4 ("virtio_net: use common code for virtio_net_hdr and skb GSO conversion")
Signed-off-by: Jianfeng Tan <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

net: in virtio_net_hdr only add VLAN_HLEN to csum_start if payload holds vlan

Tun, tap, virtio, packet and uml vector all use struct virtio_net_hdr
to communicate packet metadata to userspace.

For

net: in virtio_net_hdr only add VLAN_HLEN to csum_start if payload holds vlan

Tun, tap, virtio, packet and uml vector all use struct virtio_net_hdr
to communicate packet metadata to userspace.

For skbuffs with vlan, the first two return the packet as it may have
existed on the wire, inserting the VLAN tag in the user buffer. Then
virtio_net_hdr.csum_start needs to be adjusted by VLAN_HLEN bytes.

Commit f09e2249c4f5 ("macvtap: restore vlan header on user read")
added this feature to macvtap. Commit 3ce9b20f1971 ("macvtap: Fix
csum_start when VLAN tags are present") then fixed up csum_start.

Virtio, packet and uml do not insert the vlan header in the user
buffer.

When introducing virtio_net_hdr_from_skb to deduplicate filling in
the virtio_net_hdr, the variant from macvtap which adds VLAN_HLEN was
applied uniformly, breaking csum offset for packets with vlan on
virtio and packet.

Make insertion of VLAN_HLEN optional. Convert the callers to pass it
when needed.

Fixes: e858fae2b0b8f4 ("virtio_net: use common code for virtio_net_hdr and skb GSO conversion")
Fixes: 1276f24eeef2 ("packet: use common code for virtio_net_hdr and skb GSO conversion")
Signed-off-by: Willem de Bruijn <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

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net: accept UFO datagrams from tuntap and packet

Tuntap and similar devices can inject GSO packets. Accept type
VIRTIO_NET_HDR_GSO_UDP, even though not generating UFO natively.

Processes are expect

net: accept UFO datagrams from tuntap and packet

Tuntap and similar devices can inject GSO packets. Accept type
VIRTIO_NET_HDR_GSO_UDP, even though not generating UFO natively.

Processes are expected to use feature negotiation such as TUNSETOFFLOAD
to detect supported offload types and refrain from injecting other
packets. This process breaks down with live migration: guest kernels
do not renegotiate flags, so destination hosts need to expose all
features that the source host does.

Partially revert the UFO removal from 182e0b6b5846~1..d9d30adf5677.
This patch introduces nearly(*) no new code to simplify verification.
It brings back verbatim tuntap UFO negotiation, VIRTIO_NET_HDR_GSO_UDP
insertion and software UFO segmentation.

It does not reinstate protocol stack support, hardware offload
(NETIF_F_UFO), SKB_GSO_UDP tunneling in SKB_GSO_SOFTWARE or reception
of VIRTIO_NET_HDR_GSO_UDP packets in tuntap.

To support SKB_GSO_UDP reappearing in the stack, also reinstate
logic in act_csum and openvswitch. Achieve equivalence with v4.13 HEAD
by squashing in commit 939912216fa8 ("net: skb_needs_check() removes
CHECKSUM_UNNECESSARY check for tx.") and reverting commit 8d63bee643f1
("net: avoid skb_warn_bad_offload false positives on UFO").

(*) To avoid having to bring back skb_shinfo(skb)->ip6_frag_id,
ipv6_proxy_select_ident is changed to return a __be32 and this is
assigned directly to the frag_hdr. Also, SKB_GSO_UDP is inserted
at the end of the enum to minimize code churn.

Tested
Booted a v4.13 guest kernel with QEMU. On a host kernel before this
patch `ethtool -k eth0` shows UFO disabled. After the patch, it is
enabled, same as on a v4.13 host kernel.

A UFO packet sent from the guest appears on the tap device:
host:
nc -l -p -u 8000 &
tcpdump -n -i tap0

guest:
dd if=/dev/zero of=payload.txt bs=1 count=2000
nc -u 192.16.1.1 8000 < payload.txt

Direct tap to tap transmission of VIRTIO_NET_HDR_GSO_UDP succeeds,
packets arriving fragmented:

./with_tap_pair.sh ./tap_send_ufo tap0 tap1
(from https://github.com/wdebruij/kerneltools/tree/master/tests)

Changes
v1 -> v2
- simplified set_offload change (review comment)
- documented test procedure

Link: http://lkml.kernel.org/r/<CAF=yD-LuUeDuL9YWPJD9ykOZ0QCjNeznPDr6whqZ9NGMNF12Mw@mail.gmail.com>
Fixes: fb652fdfe837 ("macvlan/macvtap: Remove NETIF_F_UFO advertisement.")
Reported-by: Michal Kubecek <[email protected]>
Signed-off-by: Willem de Bruijn <[email protected]>
Acked-by: Jason Wang <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

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License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.

For non */uapi/* files that summary was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139

and resulted in the first patch in this series.

If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930

and resulted in the second patch in this series.

- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:

SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1

and that resulted in the third patch in this series.

- when the two scanners agreed on the detected license(s), that became
the concluded license(s).

- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.

- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).

- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.

- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct

This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <[email protected]>
Reviewed-by: Philippe Ombredanne <[email protected]>
Reviewed-by: Thomas Gleixner <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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net: Remove all references to SKB_GSO_UDP.

Such packets are no longer possible.

Signed-off-by: David S. Miller <[email protected]>