kernel/linux.git/net/core/flow_dissector.c, branch v7.0.10

flow_dissector: do not dissect PPPoE PFC frames

2026-05-14T13:31:03+00:00

[ Upstream commit d6c19b31a3c1d519fabdcf0aa239e6b6109b9473 ] RFC 2516 Section 7 states that Protocol Field Compression (PFC) is NOT RECOMMENDED for PPPoE. In practice, pppd does not support negotiating PFC for PPPoE sessions, and the flow dissector driver has assumed an uncompressed frame until the blamed commit. During the review process of that commit [1], support for PFC is suggested. However, having a compressed (1-byte) protocol field means the subsequent PPP payload is shifted by one byte, causing 4-byte misalignment for the network header and an unaligned access exception on some architectures. The exception can be reproduced by sending a PPPoE PFC frame to an ethernet interface of a MIPS board, with RPS enabled, even if no PPPoE session is active on that interface: $ 0 : 00000000 80c40000 00000000 85144817 $ 4 : 00000008 00000100 80a75758 81dc9bb8 $ 8 : 00000010 8087ae2c 0000003d 00000000 $12 : 000000e0 00000039 00000000 00000000 $16 : 85043240 80a75758 81dc9bb8 00006488 $20 : 0000002f 00000007 85144810 80a70000 $24 : 81d1bda0 00000000 $28 : 81dc8000 81dc9aa8 00000000 805ead08 Hi : 00009d51 Lo : 2163358a epc : 805e91f0 __skb_flow_dissect+0x1b0/0x1b50 ra : 805ead08 __skb_get_hash_net+0x74/0x12c Status: 11000403 KERNEL EXL IE Cause : 40800010 (ExcCode 04) BadVA : 85144817 PrId : 0001992f (MIPS 1004Kc) Call Trace: [<805e91f0>] __skb_flow_dissect+0x1b0/0x1b50 [<805ead08>] __skb_get_hash_net+0x74/0x12c [<805ef330>] get_rps_cpu+0x1b8/0x3fc [<805fca70>] netif_receive_skb_list_internal+0x324/0x364 [<805fd120>] napi_complete_done+0x68/0x2a4 [<8058de5c>] mtk_napi_rx+0x228/0xfec [<805fd398>] __napi_poll+0x3c/0x1c4 [<805fd754>] napi_threaded_poll_loop+0x234/0x29c [<805fd848>] napi_threaded_poll+0x8c/0xb0 [<80053544>] kthread+0x104/0x12c [<80002bd8>] ret_from_kernel_thread+0x14/0x1c Code: 02d51821 1060045b 00000000 <8c640000> 3084000f 2c820005 144001a2 00042080 8e220000 To reduce the attack surface and maintain performance, do not process PPPoE PFC frames. [1] https://lore.kernel.org/r/20220630231016.GA392@debian.home Fixes: 46126db9c861 ("flow_dissector: Add PPPoE dissectors") Signed-off-by: Qingfang Deng Link: https://patch.msgid.link/20260415022456.141758-1-qingfang.deng@linux.dev Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: remove '' from skb_flow_get_ports()

2025-02-24T22:27:53+00:00

Only one version of skb_flow_get_ports() exists after the previous commit, so let's remove the useless '__'. Suggested-by: Simon Horman Signed-off-by: Nicolas Dichtel Link: https://patch.msgid.link/20250221110941.2041629-3-nicolas.dichtel@6wind.com Signed-off-by: Jakub Kicinski

flow_dissector: Fix port range key handling in BPF conversion

2025-02-20T02:54:59+00:00

Fix how port range keys are handled in __skb_flow_bpf_to_target() by: - Separating PORTS and PORTS_RANGE key handling - Using correct key_ports_range structure for range keys - Properly initializing both key types independently This ensures port range information is correctly stored in its dedicated structure rather than incorrectly using the regular ports key structure. Fixes: 59fb9b62fb6c ("flow_dissector: Fix to use new variables for port ranges in bpf hook") Reported-by: Qiang Zhang Closes: https://lore.kernel.org/netdev/CAPx+-5uvFxkhkz4=j_Xuwkezjn9U6kzKTD5jz4tZ9msSJ0fOJA@mail.gmail.com/ Cc: Yoshiki Komachi Cc: Jamal Hadi Salim Cc: Jiri Pirko Signed-off-by: Cong Wang Link: https://patch.msgid.link/20250218043210.732959-4-xiyou.wangcong@gmail.com Signed-off-by: Jakub Kicinski

flow_dissector: Fix handling of mixed port and port-range keys

2025-02-20T02:54:58+00:00

This patch fixes a bug in TC flower filter where rules combining a specific destination port with a source port range weren't working correctly. The specific case was when users tried to configure rules like: tc filter add dev ens38 ingress protocol ip flower ip_proto udp \ dst_port 5000 src_port 2000-3000 action drop The root cause was in the flow dissector code. While both FLOW_DISSECTOR_KEY_PORTS and FLOW_DISSECTOR_KEY_PORTS_RANGE flags were being set correctly in the classifier, the __skb_flow_dissect_ports() function was only populating one of them: whichever came first in the enum check. This meant that when the code needed both a specific port and a port range, one of them would be left as 0, causing the filter to not match packets as expected. Fix it by removing the either/or logic and instead checking and populating both key types independently when they're in use. Fixes: 8ffb055beae5 ("cls_flower: Fix the behavior using port ranges with hw-offload") Reported-by: Qiang Zhang Closes: https://lore.kernel.org/netdev/CAPx+-5uvFxkhkz4=j_Xuwkezjn9U6kzKTD5jz4tZ9msSJ0fOJA@mail.gmail.com/ Cc: Yoshiki Komachi Cc: Jamal Hadi Salim Cc: Jiri Pirko Signed-off-by: Cong Wang Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20250218043210.732959-2-xiyou.wangcong@gmail.com Signed-off-by: Jakub Kicinski

flow_dissector: use RCU protection to fetch dev_net()

2025-02-07T00:14:15+00:00

__skb_flow_dissect() can be called from arbitrary contexts. It must extend its RCU protection section to include the call to dev_net(), which can become dev_net_rcu(). This makes sure the net structure can not disappear under us. Fixes: 9b52e3f267a6 ("flow_dissector: handle no-skb use case") Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250205155120.1676781-10-edumazet@google.com Signed-off-by: Jakub Kicinski

net: flow_dissector: use DEBUG_NET_WARN_ON_ONCE

2024-07-18T08:52:17+00:00

The following splat is easy to reproduce upstream as well as in -stable kernels. Florian Westphal provided the following commit: d1dab4f71d37 ("net: add and use __skb_get_hash_symmetric_net") but this complementary fix has been also suggested by Willem de Bruijn and it can be easily backported to -stable kernel which consists in using DEBUG_NET_WARN_ON_ONCE instead to silence the following splat given __skb_get_hash() is used by the nftables tracing infrastructure to to identify packets in traces. [69133.561393] ------------[ cut here ]------------ [69133.561404] WARNING: CPU: 0 PID: 43576 at net/core/flow_dissector.c:1104 __skb_flow_dissect+0x134f/ [...] [69133.561944] CPU: 0 PID: 43576 Comm: socat Not tainted 6.10.0-rc7+ #379 [69133.561959] RIP: 0010:__skb_flow_dissect+0x134f/0x2ad0 [69133.561970] Code: 83 f9 04 0f 84 b3 00 00 00 45 85 c9 0f 84 aa 00 00 00 41 83 f9 02 0f 84 81 fc ff ff 44 0f b7 b4 24 80 00 00 00 e9 8b f9 ff ff <0f> 0b e9 20 f3 ff ff 41 f6 c6 20 0f 84 e4 ef ff ff 48 8d 7b 12 e8 [69133.561979] RSP: 0018:ffffc90000006fc0 EFLAGS: 00010246 [69133.561988] RAX: 0000000000000000 RBX: ffffffff82f33e20 RCX: ffffffff81ab7e19 [69133.561994] RDX: dffffc0000000000 RSI: ffffc90000007388 RDI: ffff888103a1b418 [69133.562001] RBP: ffffc90000007310 R08: 0000000000000000 R09: 0000000000000000 [69133.562007] R10: ffffc90000007388 R11: ffffffff810cface R12: ffff888103a1b400 [69133.562013] R13: 0000000000000000 R14: ffffffff82f33e2a R15: ffffffff82f33e28 [69133.562020] FS: 00007f40f7131740(0000) GS:ffff888390800000(0000) knlGS:0000000000000000 [69133.562027] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [69133.562033] CR2: 00007f40f7346ee0 CR3: 000000015d200001 CR4: 00000000001706f0 [69133.562040] Call Trace: [69133.562044] [69133.562049] ? __warn+0x9f/0x1a0 [ 1211.841384] ? __skb_flow_dissect+0x107e/0x2860 [...] [ 1211.841496] ? bpf_flow_dissect+0x160/0x160 [ 1211.841753] __skb_get_hash+0x97/0x280 [ 1211.841765] ? __skb_get_hash_symmetric+0x230/0x230 [ 1211.841776] ? mod_find+0xbf/0xe0 [ 1211.841786] ? get_stack_info_noinstr+0x12/0xe0 [ 1211.841798] ? bpf_ksym_find+0x56/0xe0 [ 1211.841807] ? __rcu_read_unlock+0x2a/0x70 [ 1211.841819] nft_trace_init+0x1b9/0x1c0 [nf_tables] [ 1211.841895] ? nft_trace_notify+0x830/0x830 [nf_tables] [ 1211.841964] ? get_stack_info+0x2b/0x80 [ 1211.841975] ? nft_do_chain_arp+0x80/0x80 [nf_tables] [ 1211.842044] nft_do_chain+0x79c/0x850 [nf_tables] Fixes: 9b52e3f267a6 ("flow_dissector: handle no-skb use case") Suggested-by: Willem de Bruijn Signed-off-by: Pablo Neira Ayuso Reviewed-by: Willem de Bruijn Link: https://patch.msgid.link/20240715141442.43775-1-pablo@netfilter.org Signed-off-by: Paolo Abeni

flow_dissector: set encapsulation control flags for non-IP

2024-07-15T16:14:39+00:00

Make sure to set encapsulated control flags also for non-IP packets, such that it's possible to allow matching on e.g. TUNNEL_OAM on a geneve packet carrying a non-IP packet. Suggested-by: Davide Caratti Signed-off-by: Asbjørn Sloth Tønnesen Tested-by: Davide Caratti Reviewed-by: Davide Caratti Link: https://patch.msgid.link/20240713021911.1631517-13-ast@fiberby.net Signed-off-by: Jakub Kicinski

flow_dissector: cleanup FLOW_DISSECTOR_KEY_ENC_FLAGS

2024-07-15T16:14:39+00:00

Now that TCA_FLOWER_KEY_ENC_FLAGS is unused, as it's former data is stored behind TCA_FLOWER_KEY_ENC_CONTROL, then remove the last bits of FLOW_DISSECTOR_KEY_ENC_FLAGS. FLOW_DISSECTOR_KEY_ENC_FLAGS is unreleased, and have been in net-next since 2024-06-04. Signed-off-by: Asbjørn Sloth Tønnesen Tested-by: Davide Caratti Reviewed-by: Davide Caratti Link: https://patch.msgid.link/20240713021911.1631517-12-ast@fiberby.net Signed-off-by: Jakub Kicinski

flow_dissector: set encapsulated control flags from tun_flags

2024-07-15T16:14:38+00:00

Set the new FLOW_DIS_F_TUNNEL_* encapsulated control flags, based on if their counter-part is set in tun_flags. These flags are not userspace visible yet, as the code to dump encapsulated control flags will first be added, and later activated in the following patches. Signed-off-by: Asbjørn Sloth Tønnesen Tested-by: Davide Caratti Reviewed-by: Davide Caratti Link: https://patch.msgid.link/20240713021911.1631517-8-ast@fiberby.net Signed-off-by: Jakub Kicinski

flow_dissector: prepare for encapsulated control flags