kernel/linux.git/net/core/lwt_bpf.c, branch v6.6.148

bpf: Update transport_header when encapsulating UDP tunnel in lwt

2026-07-24T14:03:07+00:00

[ Upstream commit 82d7d0adbc678064543e9d254864f6b4ea4a388c ] Currently, bpf_lwt_push_ip_encap() does not update skb->transport_header. When a driver, e.g. ice, reuses the stale skb->transport_header to offload checksum computation to NIC hardware, VxLAN packets encapsulated by bpf_lwt_push_encap() helper may be dropped due to incorrect checksum. Update skb->transport_header in bpf_lwt_push_ip_encap() whenever the encapsulated packet uses UDP, so checksum offload works correctly. Fixes: 52f278774e79 ("bpf: implement BPF_LWT_ENCAP_IP mode in bpf_lwt_push_encap") Cc: Leon Hwang Signed-off-by: Leon Hwang Link: https://lore.kernel.org/r/20260602150931.49629-2-leon.hwang@linux.dev Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin

lwt: Fix return values of BPF xmit ops

2023-08-18T14:05:26+00:00

BPF encap ops can return different types of positive values, such like NET_RX_DROP, NET_XMIT_CN, NETDEV_TX_BUSY, and so on, from function skb_do_redirect and bpf_lwt_xmit_reroute. At the xmit hook, such return values would be treated implicitly as LWTUNNEL_XMIT_CONTINUE in ip(6)_finish_output2. When this happens, skbs that have been freed would continue to the neighbor subsystem, causing use-after-free bug and kernel crashes. To fix the incorrect behavior, skb_do_redirect return values can be simply discarded, the same as tc-egress behavior. On the other hand, bpf_lwt_xmit_reroute returns useful errors to local senders, e.g. PMTU information. Thus convert its return values to avoid the conflict with LWTUNNEL_XMIT_CONTINUE. Fixes: 3a0af8fd61f9 ("bpf: BPF for lightweight tunnel infrastructure") Reported-by: Jordan Griege Suggested-by: Martin KaFai Lau Suggested-by: Stanislav Fomichev Signed-off-by: Yan Zhai Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/0d2b878186cfe215fec6b45769c1cd0591d3628d.1692326837.git.yan@cloudflare.com

bpf, lwt: Fix crash when using bpf_skb_set_tunnel_key() from bpf_xmit lwt hook

2022-04-22T15:45:25+00:00

xmit_check_hhlen() observes the dst for getting the device hard header length to make sure a modified packet can fit. When a helper which changes the dst - such as bpf_skb_set_tunnel_key() - is called as part of the xmit program the accessed dst is no longer valid. This leads to the following splat: BUG: kernel NULL pointer dereference, address: 00000000000000de #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 0 PID: 798 Comm: ping Not tainted 5.18.0-rc2+ #103 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 RIP: 0010:bpf_xmit+0xfb/0x17f Code: c6 c0 4d cd 8e 48 c7 c7 7d 33 f0 8e e8 42 09 fb ff 48 8b 45 58 48 8b 95 c8 00 00 00 48 2b 95 c0 00 00 00 48 83 e0 fe 48 8b 00 <0f> b7 80 de 00 00 00 39 c2 73 22 29 d0 b9 20 0a 00 00 31 d2 48 89 RSP: 0018:ffffb148c0bc7b98 EFLAGS: 00010282 RAX: 0000000000000000 RBX: 0000000000240008 RCX: 0000000000000000 RDX: 0000000000000010 RSI: 00000000ffffffea RDI: 00000000ffffffff RBP: ffff922a828a4e00 R08: ffffffff8f1350e8 R09: 00000000ffffdfff R10: ffffffff8f055100 R11: ffffffff8f105100 R12: 0000000000000000 R13: ffff922a828a4e00 R14: 0000000000000040 R15: 0000000000000000 FS: 00007f414e8f0080(0000) GS:ffff922afdc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000000000de CR3: 0000000002d80006 CR4: 0000000000370ef0 Call Trace: lwtunnel_xmit.cold+0x71/0xc8 ip_finish_output2+0x279/0x520 ? __ip_finish_output.part.0+0x21/0x130 Fix by fetching the device hard header length before running the BPF code. Fixes: 3a0af8fd61f9 ("bpf: BPF for lightweight tunnel infrastructure") Signed-off-by: Eyal Birger Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20220420165219.1755407-1-eyal.birger@gmail.com

net: Don't include filter.h from net/sock.h

2021-12-29T16:48:14+00:00

sock.h is pretty heavily used (5k objects rebuilt on x86 after it's touched). We can drop the include of filter.h from it and add a forward declaration of struct sk_filter instead. This decreases the number of rebuilt objects when bpf.h is touched from ~5k to ~1k. There's a lot of missing includes this was masking. Primarily in networking tho, this time. Signed-off-by: Jakub Kicinski Signed-off-by: Alexei Starovoitov Acked-by: Marc Kleine-Budde Acked-by: Florian Fainelli Acked-by: Nikolay Aleksandrov Acked-by: Stefano Garzarella Link: https://lore.kernel.org/bpf/20211229004913.513372-1-kuba@kernel.org

lwt_bpf: Replace preempt_disable() with migrate_disable()

2020-12-07T19:53:40+00:00

migrate_disable() is just a wrapper for preempt_disable() in non-RT kernel. It is safe to replace it, and RT kernel will benefit. Note that it is introduced since Feb 2020. Suggested-by: Alexei Starovoitov Signed-off-by: Cong Wang Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20201205075946.497763-2-xiyou.wangcong@gmail.com

lwt: Disable BH too in run_lwt_bpf()

2020-12-07T19:53:39+00:00

The per-cpu bpf_redirect_info is shared among all skb_do_redirect() and BPF redirect helpers. Callers on RX path are all in BH context, disabling preemption is not sufficient to prevent BH interruption. In production, we observed strange packet drops because of the race condition between LWT xmit and TC ingress, and we verified this issue is fixed after we disable BH. Although this bug was technically introduced from the beginning, that is commit 3a0af8fd61f9 ("bpf: BPF for lightweight tunnel infrastructure"), at that time call_rcu() had to be call_rcu_bh() to match the RCU context. So this patch may not work well before RCU flavor consolidation has been completed around v5.0. Update the comments above the code too, as call_rcu() is now BH friendly. Signed-off-by: Dongdong Wang Signed-off-by: Alexei Starovoitov Reviewed-by: Cong Wang Link: https://lore.kernel.org/bpf/20201205075946.497763-1-xiyou.wangcong@gmail.com

net: add net available in build_state

2020-03-30T05:30:57+00:00

The build_state callback of lwtunnel doesn't contain the net namespace structure yet. This patch will add it so we can check on specific address configuration at creation time of rpl source routes. Signed-off-by: Alexander Aring Signed-off-by: David S. Miller

net: ipv6_stub: use ip6_dst_lookup_flow instead of ip6_dst_lookup

2019-12-04T20:27:13+00:00

ipv6_stub uses the ip6_dst_lookup function to allow other modules to perform IPv6 lookups. However, this function skips the XFRM layer entirely. All users of ipv6_stub->ip6_dst_lookup use ip_route_output_flow (via the ip_route_output_key and ip_route_output helpers) for their IPv4 lookups, which calls xfrm_lookup_route(). This patch fixes this inconsistent behavior by switching the stub to ip6_dst_lookup_flow, which also calls xfrm_lookup_route(). This requires some changes in all the callers, as these two functions take different arguments and have different return types. Fixes: 5f81bd2e5d80 ("ipv6: export a stub for IPv6 symbols used by vxlan") Reported-by: Xiumei Mu Signed-off-by: Sabrina Dubroca Signed-off-by: David S. Miller

bpf: lwtunnel: Fix reroute supplying invalid dst

2019-10-14T18:43:48+00:00

The dst in bpf_input() has lwtstate field set. As it is of the LWTUNNEL_ENCAP_BPF type, lwtstate->data is struct bpf_lwt. When the bpf program returns BPF_LWT_REROUTE, ip_route_input_noref is directly called on this skb. This causes invalid memory access, as ip_route_input_slow calls skb_tunnel_info(skb) that expects the dst->lwstate->data to be struct ip_tunnel_info. This results to struct bpf_lwt being accessed as struct ip_tunnel_info. Drop the dst before calling the IP route input functions (both for IPv4 and IPv6). Reported by KASAN. Fixes: 3bd0b15281af ("bpf: add handling of BPF_LWT_REROUTE to lwt_bpf.c") Signed-off-by: Jiri Benc Signed-off-by: Alexei Starovoitov Acked-by: Peter Oskolkov Link: https://lore.kernel.org/bpf/111664d58fe4e9dd9c8014bb3d0b2dab93086a9e.1570609794.git.jbenc@redhat.com

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 295

2019-06-05T15:36:38+00:00

Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of version 2 of the gnu general public license as published by the free software foundation this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 64 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Alexios Zavras Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190529141901.894819585@linutronix.de Signed-off-by: Greg Kroah-Hartman