Following the cited commit, __udp_gso_segment() writes single MSS length
in the UDP header.
The cited patch doesn't account for the fact that the last segment could
be a GSO skb by itself. This could happen when the size of the packet is
a multiple of MSS, hence the first segment is also the last one (there
is no need for a remainder skb).
When the post-loop segment is a GSO skb, assign the single MSS length in
the UDP header.
Fixes: b10b446ce7 ("udp: gso: Use single MSS length in UDP header for GSO_PARTIAL")
Reported-by: Matthew Schwartz <matthew.schwartz@linux.dev>
Closes: https://lore.kernel.org/all/6c3fb15e-711d-4b8d-b152-e03d9b05293f@linux.dev/
Tested-by: Matthew Schwartz <matthew.schwartz@linux.dev>
Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
Signed-off-by: Gal Pressman <gal@nvidia.com>
Link: https://patch.msgid.link/20260518062250.3019914-3-gal@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The cited commit started using msslen for uh->len, but still uses newlen
to adjust uh->check. Although the checksum is ignored in most cases due
to the hardware offload, __udp_gso_segment attempts to maintain the
correct one. Fix uh->check and adjust it by the right value.
Additionally, after the fix, newlen becomes assigned and unused before
the loop. The code can be simplified a bit if mss adjustment is dropped,
so that newlen becomes equal to msslen before the loop, and msslen can
be also dropped, saving a few lines of code.
This brings us back to one variable, drops an unneeded arithmetic for
mss, and fixes the UDP checksum.
Fixes: b10b446ce7 ("udp: gso: Use single MSS length in UDP header for GSO_PARTIAL")
Signed-off-by: Alice Mikityanska <alice@isovalent.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Gal Pressman <gal@nvidia.com>
Link: https://patch.msgid.link/20260518062250.3019914-2-gal@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
IPv6 is no longer a module, we no longer need to export these symbols.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Fernando Fernandez Mancera <fmancera@suse.de>
Link: https://patch.msgid.link/20260402174430.2462800-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Since UDP and UDP-Lite had dedicated socket hash tables for
each, we have had to pass the pointer down to many socket
lookup functions.
UDP-Lite gone, and we do not need to do that.
Let's fetch net->ipv4.udp_table only where needed in IPv4
stack: __udp4_lib_lookup(), __udp4_lib_mcast_deliver(),
and udp_diag_dump().
Some functions are renamed as the wrapper functions are no
longer needed.
__udp4_lib_err() -> udp_err()
__udp_diag_destroy() -> udp_diag_destroy()
udp_dump_one() -> udp_diag_dump_one()
udp_dump() -> udp_diag_dump()
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20260311052020.1213705-15-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This patch enhances GSO segment handling by properly checking
the SKB_GSO_DODGY flag for frag_list GSO packets, addressing
low throughput issues observed when a station accesses IPv4
servers via hotspots with an IPv6-only upstream interface.
Specifically, it fixes a bug in GSO segmentation when forwarding
GRO packets containing a frag_list. The function skb_segment_list
cannot correctly process GRO skbs that have been converted by XLAT,
since XLAT only translates the header of the head skb. Consequently,
skbs in the frag_list may remain untranslated, resulting in protocol
inconsistencies and reduced throughput.
To address this, the patch explicitly sets the SKB_GSO_DODGY flag
for GSO packets in XLAT's IPv4/IPv6 protocol translation helpers
(bpf_skb_proto_4_to_6 and bpf_skb_proto_6_to_4). This marks GSO
packets as potentially modified after protocol translation. As a
result, GSO segmentation will avoid using skb_segment_list and
instead falls back to skb_segment for packets with the SKB_GSO_DODGY
flag. This ensures that only safe and fully translated frag_list
packets are processed by skb_segment_list, resolving protocol
inconsistencies and improving throughput when forwarding GRO packets
converted by XLAT.
Signed-off-by: Jibin Zhang <jibin.zhang@mediatek.com>
Fixes: 9fd1ff5d2a ("udp: Support UDP fraglist GRO/GSO.")
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260126152114.1211-1-jibin.zhang@mediatek.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
In GSO_PARTIAL segmentation, set the UDP length field to the single
segment size (gso_size + UDP header) instead of the large MSS size.
This provides hardware with a template length value for final
segmentation, similar to how tunnel GSO_PARTIAL handles outer headers
in UDP tunnels.
This will remove the need to manually adjust the UDP header length in
the drivers, as can be seen in subsequent patches.
This was suggested by Alex in 2018:
https://lore.kernel.org/netdev/CAKgT0UcdnUWgr3KQ=RnLKigokkiUuYefmL-ePpDvJOBNpKScFA@mail.gmail.com/
Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
Signed-off-by: Gal Pressman <gal@nvidia.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20260125121649.778086-2-gal@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Remove is_ipv6 from napi_gro_cb and use sk->sk_family instead.
This frees up space for another ip_fixedid bit that will be added
in the next commit.
udp_sock_create always creates either a AF_INET or a AF_INET6 socket,
so using sk->sk_family is reliable. In IPv6-FOU, cfg->ipv6_v6only is
always enabled.
Signed-off-by: Richard Gobert <richardbgobert@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250923085908.4687-2-richardbgobert@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Commit b40c5f4fde ("udp: disable inner UDP checksum offloads in
IPsec case") tried to fix checksumming in UFO when the packets are
going through IPsec, so that we can't rely on offloads because the UDP
header and payload will be encrypted.
But when doing a TCP test over VXLAN going through IPsec transport
mode with GSO enabled (esp4_offload module loaded), I'm seeing broken
UDP checksums on the encap after successful decryption.
The skbs get to udp4_ufo_fragment/__skb_udp_tunnel_segment via
__dev_queue_xmit -> validate_xmit_skb -> skb_gso_segment and at this
point we've already dropped the dst (unless the device sets
IFF_XMIT_DST_RELEASE, which is not common), so need_ipsec is false and
we proceed with checksum offload.
Make need_ipsec also check the secpath, which is not dropped on this
callpath.
Fixes: b40c5f4fde ("udp: disable inner UDP checksum offloads in IPsec case")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Since "net: gro: use cb instead of skb->network_header", the skb network
header is no longer set in the GRO path.
This breaks fraglist segmentation, which relies on ip_hdr()/tcp_hdr()
to check for address/port changes.
Fix this regression by selectively setting the network header for merged
segment skbs.
Fixes: 186b1ea73a ("net: gro: use cb instead of skb->network_header")
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250705150622.10699-1-nbd@nbd.name
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Use DEFINE_MUTEX() to initialize udp_tunnel_gro_type_lock.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250707091634.311974-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Commit a1e40ac5b5 ("net: gso: fix udp gso fraglist segmentation after
pull from frag_list") detected invalid geometry in frag_list skbs and
redirects them from skb_segment_list to more robust skb_segment. But some
packets with modified geometry can also hit bugs in that code. We don't
know how many such cases exist. Addressing each one by one also requires
touching the complex skb_segment code, which risks introducing bugs for
other types of skbs. Instead, linearize all these packets that fail the
basic invariants on gso fraglist skbs. That is more robust.
If only part of the fraglist payload is pulled into head_skb, it will
always cause exception when splitting skbs by skb_segment. For detailed
call stack information, see below.
Valid SKB_GSO_FRAGLIST skbs
- consist of two or more segments
- the head_skb holds the protocol headers plus first gso_size
- one or more frag_list skbs hold exactly one segment
- all but the last must be gso_size
Optional datapath hooks such as NAT and BPF (bpf_skb_pull_data) can
modify fraglist skbs, breaking these invariants.
In extreme cases they pull one part of data into skb linear. For UDP,
this causes three payloads with lengths of (11,11,10) bytes were
pulled tail to become (12,10,10) bytes.
The skbs no longer meets the above SKB_GSO_FRAGLIST conditions because
payload was pulled into head_skb, it needs to be linearized before pass
to regular skb_segment.
skb_segment+0xcd0/0xd14
__udp_gso_segment+0x334/0x5f4
udp4_ufo_fragment+0x118/0x15c
inet_gso_segment+0x164/0x338
skb_mac_gso_segment+0xc4/0x13c
__skb_gso_segment+0xc4/0x124
validate_xmit_skb+0x9c/0x2c0
validate_xmit_skb_list+0x4c/0x80
sch_direct_xmit+0x70/0x404
__dev_queue_xmit+0x64c/0xe5c
neigh_resolve_output+0x178/0x1c4
ip_finish_output2+0x37c/0x47c
__ip_finish_output+0x194/0x240
ip_finish_output+0x20/0xf4
ip_output+0x100/0x1a0
NF_HOOK+0xc4/0x16c
ip_forward+0x314/0x32c
ip_rcv+0x90/0x118
__netif_receive_skb+0x74/0x124
process_backlog+0xe8/0x1a4
__napi_poll+0x5c/0x1f8
net_rx_action+0x154/0x314
handle_softirqs+0x154/0x4b8
[118.376811] [C201134] rxq0_pus: [name:bug&]kernel BUG at net/core/skbuff.c:4278!
[118.376829] [C201134] rxq0_pus: [name:traps&]Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP
[118.470774] [C201134] rxq0_pus: [name:mrdump&]Kernel Offset: 0x178cc00000 from 0xffffffc008000000
[118.470810] [C201134] rxq0_pus: [name:mrdump&]PHYS_OFFSET: 0x40000000
[118.470827] [C201134] rxq0_pus: [name:mrdump&]pstate: 60400005 (nZCv daif +PAN -UAO)
[118.470848] [C201134] rxq0_pus: [name:mrdump&]pc : [0xffffffd79598aefc] skb_segment+0xcd0/0xd14
[118.470900] [C201134] rxq0_pus: [name:mrdump&]lr : [0xffffffd79598a5e8] skb_segment+0x3bc/0xd14
[118.470928] [C201134] rxq0_pus: [name:mrdump&]sp : ffffffc008013770
Fixes: a1e40ac5b5 ("gso: fix udp gso fraglist segmentation after pull from frag_list")
Signed-off-by: Shiming Cheng <shiming.cheng@mediatek.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
If any address or port is changed, update it in all packets and recalculate
checksum.
Fixes: 9fd1ff5d2a ("udp: Support UDP fraglist GRO/GSO.")
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250426153210.14044-1-nbd@nbd.name
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
It's quite common to have a single UDP tunnel type active in the
whole system. In such a case we can replace the indirect call for
the UDP tunnel GRO callback with a static call.
Add the related accounting in the control path and switch to static
call when possible. To keep the code simple use a static array for
the registered tunnel types, and size such array based on the kernel
config.
Note that there are valid kernel configurations leading to
UDP_MAX_TUNNEL_TYPES == 0 even with IS_ENABLED(CONFIG_NET_UDP_TUNNEL),
Explicitly skip the accounting in such a case, to avoid compile warning
when accessing "udp_tunnel_gro_types".
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/53d156cdfddcc9678449e873cc83e68fa1582653.1744040675.git.pabeni@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Most UDP tunnels bind a socket to a local port, with ANY address, no
peer and no interface index specified.
Additionally it's quite common to have a single tunnel device per
namespace.
Track in each namespace the UDP tunnel socket respecting the above.
When only a single one is present, store a reference in the netns.
When such reference is not NULL, UDP tunnel GRO lookup just need to
match the incoming packet destination port vs the socket local port.
The tunnel socket never sets the reuse[port] flag[s]. When bound to no
address and interface, no other socket can exist in the same netns
matching the specified local port.
Matching packets with non-local destination addresses will be
aggregated, and eventually segmented as needed - no behavior changes
intended.
Restrict the optimization to kernel sockets only: it covers all the
relevant use-cases, and user-space owned sockets could be disconnected
and rebound after setup_udp_tunnel_sock(), breaking the uniqueness
assumption
Note that the UDP tunnel socket reference is stored into struct
netns_ipv4 for both IPv4 and IPv6 tunnels. That is intentional to keep
all the fastpath-related netns fields in the same struct and allow
cacheline-based optimization. Currently both the IPv4 and IPv6 socket
pointer share the same cacheline as the `udp_table` field.
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/41d16bc8d1257d567f9344c445b4ae0b4a91ede4.1744040675.git.pabeni@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Revert "udp_tunnel: use static call for GRO hooks when possible"
This reverts commit 311b36574c.
Revert "udp_tunnel: create a fastpath GRO lookup."
This reverts commit 8d4880db37.
There are multiple small issues with the series. In the interest
of unblocking the merge window let's opt for a revert.
Link: https://lore.kernel.org/cover.1742557254.git.pabeni@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
It's quite common to have a single UDP tunnel type active in the
whole system. In such a case we can replace the indirect call for
the UDP tunnel GRO callback with a static call.
Add the related accounting in the control path and switch to static
call when possible. To keep the code simple use a static array for
the registered tunnel types, and size such array based on the kernel
config.
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/6fd1f9c7651151493ecab174e7b8386a1534170d.1741718157.git.pabeni@redhat.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Most UDP tunnels bind a socket to a local port, with ANY address, no
peer and no interface index specified.
Additionally it's quite common to have a single tunnel device per
namespace.
Track in each namespace the UDP tunnel socket respecting the above.
When only a single one is present, store a reference in the netns.
When such reference is not NULL, UDP tunnel GRO lookup just need to
match the incoming packet destination port vs the socket local port.
The tunnel socket never sets the reuse[port] flag[s]. When bound to no
address and interface, no other socket can exist in the same netns
matching the specified local port.
Matching packets with non-local destination addresses will be
aggregated, and eventually segmented as needed - no behavior changes
intended.
Note that the UDP tunnel socket reference is stored into struct
netns_ipv4 for both IPv4 and IPv6 tunnels. That is intentional to keep
all the fastpath-related netns fields in the same struct and allow
cacheline-based optimization. Currently both the IPv4 and IPv6 socket
pointer share the same cacheline as the `udp_table` field.
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/4d5c319c4471161829f50cb8436841de81a5edae.1741718157.git.pabeni@redhat.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Cross-merge networking fixes after downstream PR (net-6.14-rc6).
Conflicts:
net/ethtool/cabletest.c
2bcf4772e4 ("net: ethtool: try to protect all callback with netdev instance lock")
637399bf7e ("net: ethtool: netlink: Allow NULL nlattrs when getting a phy_device")
No Adjacent changes.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
tcp4_check_fraglist_gro(), tcp6_check_fraglist_gro(),
udp4_gro_lookup_skb() and udp6_gro_lookup_skb()
assume RCU is held so that the net structure does not disappear.
Use dev_net_rcu() instead of dev_net() to get LOCKDEP support.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250301201424.2046477-5-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
In __udp_gso_segment the skb destructor is removed before segmenting the
skb but the socket reference is kept as-is. This is an issue if the
original skb is later orphaned as we can hit the following bug:
kernel BUG at ./include/linux/skbuff.h:3312! (skb_orphan)
RIP: 0010:ip_rcv_core+0x8b2/0xca0
Call Trace:
ip_rcv+0xab/0x6e0
__netif_receive_skb_one_core+0x168/0x1b0
process_backlog+0x384/0x1100
__napi_poll.constprop.0+0xa1/0x370
net_rx_action+0x925/0xe50
The above can happen following a sequence of events when using
OpenVSwitch, when an OVS_ACTION_ATTR_USERSPACE action precedes an
OVS_ACTION_ATTR_OUTPUT action:
1. OVS_ACTION_ATTR_USERSPACE is handled (in do_execute_actions): the skb
goes through queue_gso_packets and then __udp_gso_segment, where its
destructor is removed.
2. The segments' data are copied and sent to userspace.
3. OVS_ACTION_ATTR_OUTPUT is handled (in do_execute_actions) and the
same original skb is sent to its path.
4. If it later hits skb_orphan, we hit the bug.
Fix this by also removing the reference to the socket in
__udp_gso_segment.
Fixes: ad405857b1 ("udp: better wmem accounting on gso")
Signed-off-by: Antoine Tenart <atenart@kernel.org>
Link: https://patch.msgid.link/20250226171352.258045-1-atenart@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Detect gso fraglist skbs with corrupted geometry (see below) and
pass these to skb_segment instead of skb_segment_list, as the first
can segment them correctly.
Valid SKB_GSO_FRAGLIST skbs
- consist of two or more segments
- the head_skb holds the protocol headers plus first gso_size
- one or more frag_list skbs hold exactly one segment
- all but the last must be gso_size
Optional datapath hooks such as NAT and BPF (bpf_skb_pull_data) can
modify these skbs, breaking these invariants.
In extreme cases they pull all data into skb linear. For UDP, this
causes a NULL ptr deref in __udpv4_gso_segment_list_csum at
udp_hdr(seg->next)->dest.
Detect invalid geometry due to pull, by checking head_skb size.
Don't just drop, as this may blackhole a destination. Convert to be
able to pass to regular skb_segment.
Link: https://lore.kernel.org/netdev/20240428142913.18666-1-shiming.cheng@mediatek.com/
Fixes: 9fd1ff5d2a ("udp: Support UDP fraglist GRO/GSO.")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20241001171752.107580-1-willemdebruijn.kernel@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
When assembling fraglist GSO packets, udp4_gro_complete does not set
skb->csum_start, which makes the extra validation in __udp_gso_segment fail.
Fixes: 89add40066 ("net: drop bad gso csum_start and offset in virtio_net_hdr")
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20240819150621.59833-1-nbd@nbd.name
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
In commit 10154dbded ("udp: Allow GSO transmit from devices with no
checksum offload") we have intentionally allowed UDP GSO packets marked
CHECKSUM_NONE to pass to the GSO stack, so that they can be segmented and
checksummed by a software fallback when the egress device lacks these
features.
What was not taken into consideration is that a CHECKSUM_NONE skb can be
handed over to the GSO stack also when the egress device advertises the
tx-udp-segmentation / NETIF_F_GSO_UDP_L4 feature.
This will happen when there are IPv6 extension headers present, which we
check for in __ip6_append_data(). Syzbot has discovered this scenario,
producing a warning as below:
ip6tnl0: caps=(0x00000006401d7869, 0x00000006401d7869)
WARNING: CPU: 0 PID: 5112 at net/core/dev.c:3293 skb_warn_bad_offload+0x166/0x1a0 net/core/dev.c:3291
Modules linked in:
CPU: 0 PID: 5112 Comm: syz-executor391 Not tainted 6.10.0-rc7-syzkaller-01603-g80ab5445da62 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
RIP: 0010:skb_warn_bad_offload+0x166/0x1a0 net/core/dev.c:3291
[...]
Call Trace:
<TASK>
__skb_gso_segment+0x3be/0x4c0 net/core/gso.c:127
skb_gso_segment include/net/gso.h:83 [inline]
validate_xmit_skb+0x585/0x1120 net/core/dev.c:3661
__dev_queue_xmit+0x17a4/0x3e90 net/core/dev.c:4415
neigh_output include/net/neighbour.h:542 [inline]
ip6_finish_output2+0xffa/0x1680 net/ipv6/ip6_output.c:137
ip6_finish_output+0x41e/0x810 net/ipv6/ip6_output.c:222
ip6_send_skb+0x112/0x230 net/ipv6/ip6_output.c:1958
udp_v6_send_skb+0xbf5/0x1870 net/ipv6/udp.c:1292
udpv6_sendmsg+0x23b3/0x3270 net/ipv6/udp.c:1588
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg+0xef/0x270 net/socket.c:745
____sys_sendmsg+0x525/0x7d0 net/socket.c:2585
___sys_sendmsg net/socket.c:2639 [inline]
__sys_sendmmsg+0x3b2/0x740 net/socket.c:2725
__do_sys_sendmmsg net/socket.c:2754 [inline]
__se_sys_sendmmsg net/socket.c:2751 [inline]
__x64_sys_sendmmsg+0xa0/0xb0 net/socket.c:2751
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
[...]
</TASK>
We are hitting the bad offload warning because when an egress device is
capable of handling segmentation offload requested by
skb_shinfo(skb)->gso_type, the chain of gso_segment callbacks won't produce
any segment skbs and return NULL. See the skb_gso_ok() branch in
{__udp,tcp,sctp}_gso_segment helpers.
To fix it, force a fallback to software USO when processing a packet with
IPv6 extension headers, since we don't know if these can checksummed by
all devices which offer USO.
Fixes: 10154dbded ("udp: Allow GSO transmit from devices with no checksum offload")
Reported-by: syzbot+e15b7e15b8a751a91d9a@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/000000000000e1609a061d5330ce@google.com/
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://patch.msgid.link/20240808-udp-gso-egress-from-tunnel-v4-2-f5c5b4149ab9@cloudflare.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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 10154dbded ("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: e269d79c7d ("net: missing check virtio")
Cc: stable@vger.kernel.org
Signed-off-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20240729201108.1615114-1-willemdebruijn.kernel@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Today sending a UDP GSO packet from a TUN device results in an EIO error:
import fcntl, os, struct
from socket import *
TUNSETIFF = 0x400454CA
IFF_TUN = 0x0001
IFF_NO_PI = 0x1000
UDP_SEGMENT = 103
tun_fd = os.open("/dev/net/tun", os.O_RDWR)
ifr = struct.pack("16sH", b"tun0", IFF_TUN | IFF_NO_PI)
fcntl.ioctl(tun_fd, TUNSETIFF, ifr)
os.system("ip addr add 192.0.2.1/24 dev tun0")
os.system("ip link set dev tun0 up")
s = socket(AF_INET, SOCK_DGRAM)
s.setsockopt(SOL_UDP, UDP_SEGMENT, 1200)
s.sendto(b"x" * 3000, ("192.0.2.2", 9)) # EIO
This is due to a check in the udp stack if the egress device offers
checksum offload. While TUN/TAP devices, by default, don't advertise this
capability because it requires support from the TUN/TAP reader.
However, the GSO stack has a software fallback for checksum calculation,
which we can use. This way we don't force UDP_SEGMENT users to handle the
EIO error and implement a segmentation fallback.
Lift the restriction so that UDP_SEGMENT can be used with any egress
device. We also need to adjust the UDP GSO code to match the GSO stack
expectation about ip_summed field, as set in commit 8d63bee643 ("net:
avoid skb_warn_bad_offload false positives on UFO"). Otherwise we will hit
the bad offload check.
Users should, however, expect a potential performance impact when
batch-sending packets with UDP_SEGMENT without checksum offload on the
egress device. In such case the packet payload is read twice: first during
the sendmsg syscall when copying data from user memory, and then in the GSO
stack for checksum computation. This double memory read can be less
efficient than a regular sendmsg where the checksum is calculated during
the initial data copy from user memory.
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20240626-linux-udpgso-v2-1-422dfcbd6b48@cloudflare.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
{inet,ipv6}_gro_receive functions perform flush checks (ttl, flags,
iph->id, ...) against all packets in a loop. These flush checks are used in
all merging UDP and TCP flows.
These checks need to be done only once and only against the found p skb,
since they only affect flush and not same_flow.
This patch leverages correct network header offsets from the cb for both
outer and inner network headers - allowing these checks to be done only
once, in tcp_gro_receive and udp_gro_receive_segment. As a result,
NAPI_GRO_CB(p)->flush is not used at all. In addition, flush_id checks are
more declarative and contained in inet_gro_flush, thus removing the need
for flush_id in napi_gro_cb.
This results in less parsing code for non-loop flush tests for TCP and UDP
flows.
To make sure results are not within noise range - I've made netfilter drop
all TCP packets, and measured CPU performance in GRO (in this case GRO is
responsible for about 50% of the CPU utilization).
perf top while replaying 64 parallel IP/TCP streams merging in GRO:
(gro_receive_network_flush is compiled inline to tcp_gro_receive)
net-next:
6.94% [kernel] [k] inet_gro_receive
3.02% [kernel] [k] tcp_gro_receive
patch applied:
4.27% [kernel] [k] tcp_gro_receive
4.22% [kernel] [k] inet_gro_receive
perf top while replaying 64 parallel IP/IP/TCP streams merging in GRO (same
results for any encapsulation, in this case inet_gro_receive is top
offender in net-next)
net-next:
10.09% [kernel] [k] inet_gro_receive
2.08% [kernel] [k] tcp_gro_receive
patch applied:
6.97% [kernel] [k] inet_gro_receive
3.68% [kernel] [k] tcp_gro_receive
Signed-off-by: Richard Gobert <richardbgobert@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20240509190819.2985-3-richardbgobert@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This helper function will be used for TCP fraglist GRO support
Acked-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
GRO-GSO path is supposed to be transparent and as such L3 flush checks are
relevant to all UDP flows merging in GRO. This patch uses the same logic
and code from tcp_gro_receive, terminating merge if flush is non zero.
Fixes: e20cf8d3f1 ("udp: implement GRO for plain UDP sockets.")
Signed-off-by: Richard Gobert <richardbgobert@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Commits a602456 ("udp: Add GRO functions to UDP socket") and 57c67ff ("udp:
additional GRO support") introduce incorrect usage of {ip,ipv6}_hdr in the
complete phase of gro. The functions always return skb->network_header,
which in the case of encapsulated packets at the gro complete phase, is
always set to the innermost L3 of the packet. That means that calling
{ip,ipv6}_hdr for skbs which completed the GRO receive phase (both in
gro_list and *_gro_complete) when parsing an encapsulated packet's _outer_
L3/L4 may return an unexpected value.
This incorrect usage leads to a bug in GRO's UDP socket lookup.
udp{4,6}_lib_lookup_skb functions use ip_hdr/ipv6_hdr respectively. These
*_hdr functions return network_header which will point to the innermost L3,
resulting in the wrong offset being used in __udp{4,6}_lib_lookup with
encapsulated packets.
This patch adds network_offset and inner_network_offset to napi_gro_cb, and
makes sure both are set correctly.
To fix the issue, network_offsets union is used inside napi_gro_cb, in
which both the outer and the inner network offsets are saved.
Reproduction example:
Endpoint configuration example (fou + local address bind)
# ip fou add port 6666 ipproto 4
# ip link add name tun1 type ipip remote 2.2.2.1 local 2.2.2.2 encap fou encap-dport 5555 encap-sport 6666 mode ipip
# ip link set tun1 up
# ip a add 1.1.1.2/24 dev tun1
Netperf TCP_STREAM result on net-next before patch is applied:
net-next main, GRO enabled:
$ netperf -H 1.1.1.2 -t TCP_STREAM -l 5
Recv Send Send
Socket Socket Message Elapsed
Size Size Size Time Throughput
bytes bytes bytes secs. 10^6bits/sec
131072 16384 16384 5.28 2.37
net-next main, GRO disabled:
$ netperf -H 1.1.1.2 -t TCP_STREAM -l 5
Recv Send Send
Socket Socket Message Elapsed
Size Size Size Time Throughput
bytes bytes bytes secs. 10^6bits/sec
131072 16384 16384 5.01 2745.06
patch applied, GRO enabled:
$ netperf -H 1.1.1.2 -t TCP_STREAM -l 5
Recv Send Send
Socket Socket Message Elapsed
Size Size Size Time Throughput
bytes bytes bytes secs. 10^6bits/sec
131072 16384 16384 5.01 2877.38
Fixes: a6024562ff ("udp: Add GRO functions to UDP socket")
Signed-off-by: Richard Gobert <richardbgobert@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
GRO has a fundamental issue with UDP tunnel packets as it can't detect
those in a foolproof way and GRO could happen before they reach the
tunnel endpoint. Previous commits have fixed issues when UDP tunnel
packets come from a remote host, but if those packets are issued locally
they could run into checksum issues.
If the inner packet has a partial checksum the information will be lost
in the GRO logic, either in udp4/6_gro_complete or in
udp_gro_complete_segment and packets will have an invalid checksum when
leaving the host.
Prevent local UDP tunnel packets from ever being GROed at the outer UDP
level.
Due to skb->encapsulation being wrongly used in some drivers this is
actually only preventing UDP tunnel packets with a partial checksum to
be GROed (see iptunnel_handle_offloads) but those were also the packets
triggering issues so in practice this should be sufficient.
Fixes: 9fd1ff5d2a ("udp: Support UDP fraglist GRO/GSO.")
Fixes: 36707061d6 ("udp: allow forwarding of plain (non-fraglisted) UDP GRO packets")
Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Antoine Tenart <atenart@kernel.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
UDP GRO validates checksums and in udp4/6_gro_complete fraglist packets
are converted to CHECKSUM_UNNECESSARY to avoid later checks. However
this is an issue for CHECKSUM_PARTIAL packets as they can be looped in
an egress path and then their partial checksums are not fixed.
Different issues can be observed, from invalid checksum on packets to
traces like:
gen01: hw csum failure
skb len=3008 headroom=160 headlen=1376 tailroom=0
mac=(106,14) net=(120,40) trans=160
shinfo(txflags=0 nr_frags=0 gso(size=0 type=0 segs=0))
csum(0xffff232e ip_summed=2 complete_sw=0 valid=0 level=0)
hash(0x77e3d716 sw=1 l4=1) proto=0x86dd pkttype=0 iif=12
...
Fix this by only converting CHECKSUM_NONE packets to
CHECKSUM_UNNECESSARY by reusing __skb_incr_checksum_unnecessary. All
other checksum types are kept as-is, including CHECKSUM_COMPLETE as
fraglist packets being segmented back would have their skb->csum valid.
Fixes: 9fd1ff5d2a ("udp: Support UDP fraglist GRO/GSO.")
Signed-off-by: Antoine Tenart <atenart@kernel.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
If packets are GROed with fraglist they might be segmented later on and
continue their journey in the stack. In skb_segment_list those skbs can
be reused as-is. This is an issue as their destructor was removed in
skb_gro_receive_list but not the reference to their socket, and then
they can't be orphaned. Fix this by also removing the reference to the
socket.
For example this could be observed,
kernel BUG at include/linux/skbuff.h:3131! (skb_orphan)
RIP: 0010:ip6_rcv_core+0x11bc/0x19a0
Call Trace:
ipv6_list_rcv+0x250/0x3f0
__netif_receive_skb_list_core+0x49d/0x8f0
netif_receive_skb_list_internal+0x634/0xd40
napi_complete_done+0x1d2/0x7d0
gro_cell_poll+0x118/0x1f0
A similar construction is found in skb_gro_receive, apply the same
change there.
Fixes: 5e10da5385 ("skbuff: allow 'slow_gro' for skb carring sock reference")
Signed-off-by: Antoine Tenart <atenart@kernel.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When rx-udp-gro-forwarding is enabled UDP packets might be GROed when
being forwarded. If such packets might land in a tunnel this can cause
various issues and udp_gro_receive makes sure this isn't the case by
looking for a matching socket. This is performed in
udp4/6_gro_lookup_skb but only in the current netns. This is an issue
with tunneled packets when the endpoint is in another netns. In such
cases the packets will be GROed at the UDP level, which leads to various
issues later on. The same thing can happen with rx-gro-list.
We saw this with geneve packets being GROed at the UDP level. In such
case gso_size is set; later the packet goes through the geneve rx path,
the geneve header is pulled, the offset are adjusted and frag_list skbs
are not adjusted with regard to geneve. When those skbs hit
skb_fragment, it will misbehave. Different outcomes are possible
depending on what the GROed skbs look like; from corrupted packets to
kernel crashes.
One example is a BUG_ON[1] triggered in skb_segment while processing the
frag_list. Because gso_size is wrong (geneve header was pulled)
skb_segment thinks there is "geneve header size" of data in frag_list,
although it's in fact the next packet. The BUG_ON itself has nothing to
do with the issue. This is only one of the potential issues.
Looking up for a matching socket in udp_gro_receive is fragile: the
lookup could be extended to all netns (not speaking about performances)
but nothing prevents those packets from being modified in between and we
could still not find a matching socket. It's OK to keep the current
logic there as it should cover most cases but we also need to make sure
we handle tunnel packets being GROed too early.
This is done by extending the checks in udp_unexpected_gso: GSO packets
lacking the SKB_GSO_UDP_TUNNEL/_CSUM bits and landing in a tunnel must
be segmented.
[1] kernel BUG at net/core/skbuff.c:4408!
RIP: 0010:skb_segment+0xd2a/0xf70
__udp_gso_segment+0xaa/0x560
Fixes: 9fd1ff5d2a ("udp: Support UDP fraglist GRO/GSO.")
Fixes: 36707061d6 ("udp: allow forwarding of plain (non-fraglisted) UDP GRO packets")
Signed-off-by: Antoine Tenart <atenart@kernel.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
These structures are used in GRO and GSO paths.
Move them to net_hodata for better cache locality.
v2: udpv6_offload definition depends on CONFIG_INET=y
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20240306160031.874438-12-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
syzbot reported that udp->gro_enabled can be read locklessly.
Use one atomic bit from udp->udp_flags.
Fixes: e20cf8d3f1 ("udp: implement GRO for plain UDP sockets.")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This patch fixes a misuse of IP{6}CB(skb) in GRO, while calling to
`udp6_lib_lookup2` when handling udp tunnels. `udp6_lib_lookup2` fetch the
device from CB. The fix changes it to fetch the device from `skb->dev`.
l3mdev case requires special attention since it has a master and a slave
device.
Fixes: a6024562ff ("udp: Add GRO functions to UDP socket")
Reported-by: Gal Pressman <gal@nvidia.com>
Signed-off-by: Richard Gobert <richardbgobert@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Commit 1fd54773c2 ("udp: allow header check for dodgy GSO_UDP_L4
packets.") checks DODGY bit for UDP, but for packets that can be fed
directly to the device after gso_segs reset, it actually falls through
to fragmentation:
https://lore.kernel.org/all/CAJPywTKDdjtwkLVUW6LRA2FU912qcDmQOQGt2WaDo28KzYDg+A@mail.gmail.com/
This change restores the expected behavior of GSO_UDP_L4 packets.
Fixes: 1fd54773c2 ("udp: allow header check for dodgy GSO_UDP_L4 packets.")
Suggested-by: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Signed-off-by: Yan Zhai <yan@cloudflare.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Move declarations into include/net/gso.h and code into net/core/gso.c
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Stanislav Fomichev <sdf@google.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20230608191738.3947077-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Allow UDP_L4 for robust packets.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Andrew Melnychenko <andrew@daynix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
We will soon introduce an optional per-netns hash table
for UDP.
This means we cannot use udp_table directly in most places.
Instead, access it via net->ipv4.udp_table.
The access will be valid only while initialising udp_table
itself and creating/destroying each netns.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
All gro_complete() handlers are called from napi_gro_complete()
while rcu_read_lock() has been called.
There is no point stacking more rcu_read_lock()
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
All gro_receive() handlers are called from dev_gro_receive()
while rcu_read_lock() has been called.
There is no point stacking more rcu_read_lock()
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This helper is used once, no need to keep it in fat net/core/skbuff.c
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
include/linux/netdevice.h became too big, move gro stuff
into include/net/gro.h
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
GSO expects inner transport header offset to be valid when
skb->encapsulation flag is set. GSO uses this value to calculate the length
of an individual segment of a GSO packet in skb_gso_transport_seglen().
However, tcp/udp gro_complete callbacks don't update the
skb->inner_transport_header when processing an encapsulated TCP/UDP
segment. As a result a GRO skb has ->inner_transport_header set to a value
carried over from earlier skb processing.
This can have mild to tragic consequences. From miscalculating the GSO
segment length to triggering a page fault [1], when trying to read TCP/UDP
header at an address past the skb->data page.
The latter scenario leads to an oops report like so:
BUG: unable to handle page fault for address: ffff9fa7ec00d008
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 123f201067 P4D 123f201067 PUD 123f209067 PMD 0
Oops: 0000 [#1] SMP NOPTI
CPU: 44 PID: 0 Comm: swapper/44 Not tainted 5.4.53-cloudflare-2020.7.21 #1
Hardware name: HYVE EDGE-METAL-GEN10/HS-1811DLite1, BIOS V2.15 02/21/2020
RIP: 0010:skb_gso_transport_seglen+0x44/0xa0
Code: c0 41 83 e0 11 f6 87 81 00 00 00 20 74 30 0f b7 87 aa 00 00 00 0f [...]
RSP: 0018:ffffad8640bacbb8 EFLAGS: 00010202
RAX: 000000000000feda RBX: ffff9fcc8d31bc00 RCX: ffff9fa7ec00cffc
RDX: ffff9fa7ebffdec0 RSI: 000000000000feda RDI: 0000000000000122
RBP: 00000000000005c4 R08: 0000000000000001 R09: 0000000000000000
R10: ffff9fe588ae3800 R11: ffff9fe011fc92f0 R12: ffff9fcc8d31bc00
R13: ffff9fe0119d4300 R14: 00000000000005c4 R15: ffff9fba57d70900
FS: 0000000000000000(0000) GS:ffff9fe68df00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff9fa7ec00d008 CR3: 0000003e99b1c000 CR4: 0000000000340ee0
Call Trace:
<IRQ>
skb_gso_validate_network_len+0x11/0x70
__ip_finish_output+0x109/0x1c0
ip_sublist_rcv_finish+0x57/0x70
ip_sublist_rcv+0x2aa/0x2d0
? ip_rcv_finish_core.constprop.0+0x390/0x390
ip_list_rcv+0x12b/0x14f
__netif_receive_skb_list_core+0x2a9/0x2d0
netif_receive_skb_list_internal+0x1b5/0x2e0
napi_complete_done+0x93/0x140
veth_poll+0xc0/0x19f [veth]
? mlx5e_napi_poll+0x221/0x610 [mlx5_core]
net_rx_action+0x1f8/0x790
__do_softirq+0xe1/0x2bf
irq_exit+0x8e/0xc0
do_IRQ+0x58/0xe0
common_interrupt+0xf/0xf
</IRQ>
The bug can be observed in a simple setup where we send IP/GRE/IP/TCP
packets into a netns over a veth pair. Inside the netns, packets are
forwarded to dummy device:
trafgen -> [veth A]--[veth B] -forward-> [dummy]
For veth B to GRO aggregate packets on receive, it needs to have an XDP
program attached (for example, a trivial XDP_PASS). Additionally, for UDP,
we need to enable GSO_UDP_L4 feature on the device:
ip netns exec A ethtool -K AB rx-udp-gro-forwarding on
The last component is an artificial delay to increase the chances of GRO
batching happening:
ip netns exec A tc qdisc add dev AB root \
netem delay 200us slot 5ms 10ms packets 2 bytes 64k
With such a setup in place, the bug can be observed by tracing the skb
outer and inner offsets when GSO skb is transmitted from the dummy device:
tcp:
FUNC DEV SKB_LEN NH TH ENC INH ITH GSO_SIZE GSO_TYPE
ip_finish_output dumB 2830 270 290 1 294 254 1383 (tcpv4,gre,)
^^^
udp:
FUNC DEV SKB_LEN NH TH ENC INH ITH GSO_SIZE GSO_TYPE
ip_finish_output dumB 2818 270 290 1 294 254 1383 (gre,udp_l4,)
^^^
Fix it by updating the inner transport header offset in tcp/udp
gro_complete callbacks, similar to how {inet,ipv6}_gro_complete callbacks
update the inner network header offset, when skb->encapsulation flag is
set.
[1] https://lore.kernel.org/netdev/CAKxSbF01cLpZem2GFaUaifh0S-5WYViZemTicAg7FCHOnh6kug@mail.gmail.com/
Fixes: bf296b125b ("tcp: Add GRO support")
Fixes: f993bc25e5 ("net: core: handle encapsulation offloads when computing segment lengths")
Fixes: e20cf8d3f1 ("udp: implement GRO for plain UDP sockets.")
Reported-by: Alex Forster <aforster@cloudflare.com>
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
If an UDP packet enters the GRO engine but is not eligible
for aggregation and is not targeting an UDP tunnel,
udp_gro_receive() will not set the flush bit, and packet
could delayed till the next napi flush.
Fix the issue ensuring non GROed packets traverse
skb_gro_flush_final().
Reported-and-tested-by: Matthias Treydte <mt@waldheinz.de>
Fixes: 18f25dc399 ("udp: skip L4 aggregation for UDP tunnel packets")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
