<feed xmlns='http://www.w3.org/2005/Atom'>
<title>user/sven/linux.git/include/linux/virtio_net.h, branch v6.1.112</title>
<subtitle>Linux Kernel
</subtitle>
<id>https://git.stealer.net/cgit.cgi/user/sven/linux.git/atom?h=v6.1.112</id>
<link rel='self' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/atom?h=v6.1.112'/>
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<updated>2024-09-18T17:23:04Z</updated>
<entry>
<title>net: tighten bad gso csum offset check in virtio_net_hdr</title>
<updated>2024-09-18T17:23:04Z</updated>
<author>
<name>Willem de Bruijn</name>
<email>willemb@google.com</email>
</author>
<published>2024-09-10T21:35:35Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=34aaedb052cb4cb068cb19a34cf6d9cedb9af87f'/>
<id>urn:sha1:34aaedb052cb4cb068cb19a34cf6d9cedb9af87f</id>
<content type='text'>
commit 6513eb3d3191574b58859ef2d6dc26c0277c6f81 upstream.

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/20240909094527.GA3048202@port70.net/
Fixes: 89add40066f9 ("net: drop bad gso csum_start and offset in virtio_net_hdr")
Signed-off-by: Willem de Bruijn &lt;willemb@google.com&gt;
Acked-by: Jason Wang &lt;jasowang@redhat.com&gt;
Acked-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20240910213553.839926-1-willemdebruijn.kernel@gmail.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>net: drop bad gso csum_start and offset in virtio_net_hdr</title>
<updated>2024-08-29T15:30:54Z</updated>
<author>
<name>Willem de Bruijn</name>
<email>willemb@google.com</email>
</author>
<published>2024-07-29T20:10:12Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=f01c5e335fbb7fb612d40f14a3c02e2612a43d3b'/>
<id>urn:sha1:f01c5e335fbb7fb612d40f14a3c02e2612a43d3b</id>
<content type='text'>
commit 89add40066f9ed9abe5f7f886fe5789ff7e0c50e upstream.

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 &gt;= 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/20240723223109.2196886-1-kuba@kernel.org
Fixes: e269d79c7d35 ("net: missing check virtio")
Cc: stable@vger.kernel.org
Signed-off-by: Willem de Bruijn &lt;willemb@google.com&gt;
Link: https://patch.msgid.link/20240729201108.1615114-1-willemdebruijn.kernel@gmail.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>net: more strict VIRTIO_NET_HDR_GSO_UDP_L4 validation</title>
<updated>2024-08-29T15:30:54Z</updated>
<author>
<name>Willem de Bruijn</name>
<email>willemb@google.com</email>
</author>
<published>2023-10-11T14:01:14Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=4316ad9136e05482fb38d254489125edb46fb355'/>
<id>urn:sha1:4316ad9136e05482fb38d254489125edb46fb355</id>
<content type='text'>
commit fc8b2a619469378717e7270d2a4e1ef93c585f7a upstream.

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: syzbot+01cdbc31e9c0ae9b33ac@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/0000000000005039270605eb0b7f@google.com/
Reported-by: syzbot+c99d835ff081ca30f986@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/0000000000005426680605eb0b9f@google.com/
Signed-off-by: Willem de Bruijn &lt;willemb@google.com&gt;
Reviewed-by: Eric Dumazet &lt;edumazet@google.com&gt;
Acked-by: Jason Wang &lt;jasowang@redhat.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>net: missing check virtio</title>
<updated>2024-08-03T06:49:21Z</updated>
<author>
<name>Denis Arefev</name>
<email>arefev@swemel.ru</email>
</author>
<published>2024-06-13T09:54:48Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=5b1997487a3f3373b0f580c8a20b56c1b64b0775'/>
<id>urn:sha1:5b1997487a3f3373b0f580c8a20b56c1b64b0775</id>
<content type='text'>
[ Upstream commit e269d79c7d35aa3808b1f3c1737d63dab504ddc8 ]

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 &gt;= 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) &gt; 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 &lt;0f&gt; 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:
 &lt;TASK&gt;
 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-&gt;head")
Signed-off-by: Denis Arefev &lt;arefev@swemel.ru&gt;
Message-Id: &lt;20240613095448.27118-1-arefev@swemel.ru&gt;
Signed-off-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>net: do not allow gso_size to be set to GSO_BY_FRAGS</title>
<updated>2023-08-23T15:52:35Z</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2023-08-16T14:21:58Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=2e03a92b241102aaf490439aa1b00239f84f530f'/>
<id>urn:sha1:2e03a92b241102aaf490439aa1b00239f84f530f</id>
<content type='text'>
[ Upstream commit b616be6b97688f2f2bd7c4a47ab32f27f94fb2a9 ]

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 &lt;0f&gt; 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:
&lt;TASK&gt;
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 &lt;syzkaller@googlegroups.com&gt;
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Cc: Xin Long &lt;lucien.xin@gmail.com&gt;
Cc: "Michael S. Tsirkin" &lt;mst@redhat.com&gt;
Cc: Jason Wang &lt;jasowang@redhat.com&gt;
Reviewed-by: Willem de Bruijn &lt;willemb@google.com&gt;
Reviewed-by: Marcelo Ricardo Leitner &lt;marcelo.leitner@gmail.com&gt;
Reviewed-by: Xuan Zhuo &lt;xuanzhuo@linux.alibaba.com&gt;
Link: https://lore.kernel.org/r/20230816142158.1779798-1-edumazet@google.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>net: skip virtio_net_hdr_set_proto if protocol already set</title>
<updated>2021-12-21T02:47:37Z</updated>
<author>
<name>Willem de Bruijn</name>
<email>willemb@google.com</email>
</author>
<published>2021-12-20T14:50:27Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=1ed1d592113959f00cc552c3b9f47ca2d157768f'/>
<id>urn:sha1:1ed1d592113959f00cc552c3b9f47ca2d157768f</id>
<content type='text'>
virtio_net_hdr_set_proto infers skb-&gt;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 &lt;willemb@google.com&gt;
Link: https://lore.kernel.org/r/20211220145027.2784293-1-willemdebruijn.kernel@gmail.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
</entry>
<entry>
<title>net: accept UFOv6 packages in virtio_net_hdr_to_skb</title>
<updated>2021-12-21T02:47:27Z</updated>
<author>
<name>Willem de Bruijn</name>
<email>willemb@google.com</email>
</author>
<published>2021-12-20T14:49:01Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=7e5cced9ca84df52d874aca6b632f930b3dc5bc6'/>
<id>urn:sha1:7e5cced9ca84df52d874aca6b632f930b3dc5bc6</id>
<content type='text'>
Skb with skb-&gt;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 &lt;andrew@daynix.com&gt;
Signed-off-by: Willem de Bruijn &lt;willemb@google.com&gt;
Link: https://lore.kernel.org/r/20211220144901.2784030-1-willemdebruijn.kernel@gmail.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
</entry>
<entry>
<title>net: virtio_net_hdr_to_skb: count transport header in UFO</title>
<updated>2021-11-17T14:50:45Z</updated>
<author>
<name>Jonathan Davies</name>
<email>jonathan.davies@nutanix.com</email>
</author>
<published>2021-11-16T17:42:42Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=cf9acc90c80ecbee00334aa85d92f4e74014bcff'/>
<id>urn:sha1:cf9acc90c80ecbee00334aa85d92f4e74014bcff</id>
<content type='text'>
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-&gt;len - p_off &gt; gso_size)

not properly accounting for the transport layer header.

p_off includes the size of the transport layer header (thlen), so
skb-&gt;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-&gt;len will be 1515 and p_off
will be 42, so skb-&gt;len - p_off = 1473.  Hence the comparison fails, and
shinfo-&gt;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 &lt;jonathan.davies@nutanix.com&gt;
Reviewed-by: Willem de Bruijn &lt;willemb@google.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
</entry>
<entry>
<title>virtio_net: Do not pull payload in skb-&gt;head</title>
<updated>2021-04-06T23:17:57Z</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2021-04-02T13:26:02Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=0f6925b3e8da0dbbb52447ca8a8b42b371aac7db'/>
<id>urn:sha1:0f6925b3e8da0dbbb52447ca8a8b42b371aac7db</id>
<content type='text'>
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)-&gt;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-&gt;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 &lt;xuanzhuo@linux.alibaba.com&gt;
Link: https://www.spinics.net/lists/netdev/msg731397.html
Co-Developed-by: Xuan Zhuo &lt;xuanzhuo@linux.alibaba.com&gt;
Signed-off-by: Xuan Zhuo &lt;xuanzhuo@linux.alibaba.com&gt;
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Cc: "Michael S. Tsirkin" &lt;mst@redhat.com&gt;
Cc: Jason Wang &lt;jasowang@redhat.com&gt;
Cc: virtualization@lists.linux-foundation.org
Acked-by: Jason Wang &lt;jasowang@redhat.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
</entry>
<entry>
<title>net: ensure mac header is set in virtio_net_hdr_to_skb()</title>
<updated>2021-03-31T00:40:46Z</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2021-03-30T23:43:43Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=61431a5907fc36d0738e9a547c7e1556349a03e9'/>
<id>urn:sha1:61431a5907fc36d0738e9a547c7e1556349a03e9</id>
<content type='text'>
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 &lt;edumazet@google.com&gt;
Cc: Balazs Nemeth &lt;bnemeth@redhat.com&gt;
Cc: Willem de Bruijn &lt;willemb@google.com&gt;
Reported-by: syzbot &lt;syzkaller@googlegroups.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
</entry>
</feed>
