wireguard-linux/net/core/flow_dissector.c, branch jd/bump-compilers

net: flow_dissector: use DEBUG_NET_WARN_ON_ONCE

2024-07-18T08:52:17Z

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

2024-07-15T16:14:39Z

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

2024-07-15T16:14:39Z

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

2024-07-15T16:14:38Z

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

2024-07-15T16:14:38Z

Rename skb_flow_dissect_set_enc_addr_type() to skb_flow_dissect_set_enc_control(), and make it set both addr_type and flags in FLOW_DISSECTOR_KEY_ENC_CONTROL. Signed-off-by: Asbjørn Sloth Tønnesen Tested-by: Davide Caratti Reviewed-by: Davide Caratti Link: https://patch.msgid.link/20240713021911.1631517-7-ast@fiberby.net Signed-off-by: Jakub Kicinski

net: ipv4: Add a sysctl to set multipath hash seed

2024-06-12T23:42:11Z

When calculating hashes for the purpose of multipath forwarding, both IPv4 and IPv6 code currently fall back on flow_hash_from_keys(). That uses a randomly-generated seed. That's a fine choice by default, but unfortunately some deployments may need a tighter control over the seed used. In this patch, make the seed configurable by adding a new sysctl key, net.ipv4.fib_multipath_hash_seed to control the seed. This seed is used specifically for multipath forwarding and not for the other concerns that flow_hash_from_keys() is used for, such as queue selection. Expose the knob as sysctl because other such settings, such as headers to hash, are also handled that way. Like those, the multipath hash seed is a per-netns variable. Despite being placed in the net.ipv4 namespace, the multipath seed sysctl is used for both IPv4 and IPv6, similarly to e.g. a number of TCP variables. The seed used by flow_hash_from_keys() is a 128-bit quantity. However it seems that usually the seed is a much more modest value. 32 bits seem typical (Cisco, Cumulus), some systems go even lower. For that reason, and to decouple the user interface from implementation details, go with a 32-bit quantity, which is then quadruplicated to form the siphash key. Signed-off-by: Petr Machata Reviewed-by: Ido Schimmel Reviewed-by: Nikolay Aleksandrov Reviewed-by: David Ahern Link: https://lore.kernel.org/r/20240607151357.421181-3-petrm@nvidia.com Signed-off-by: Jakub Kicinski

net: add and use __skb_get_hash_symmetric_net

2024-06-12T21:33:38Z

Similar to previous patch: apply same logic for __skb_get_hash_symmetric and let callers pass the netns to the dissector core. Existing function is turned into a wrapper to avoid adjusting all callers, nft_hash.c uses new function. Reviewed-by: Willem de Bruijn Signed-off-by: Florian Westphal Reviewed-by: Eric Dumazet Link: https://lore.kernel.org/r/20240608221057.16070-3-fw@strlen.de Signed-off-by: Jakub Kicinski

net: add and use skb_get_hash_net

2024-06-12T21:33:38Z

Years ago flow dissector gained ability to delegate flow dissection to a bpf program, scoped per netns. Unfortunately, skb_get_hash() only gets an sk_buff argument instead of both net+skb. This means the flow dissector needs to obtain the netns pointer from somewhere else. The netns is derived from skb->dev, and if that is not available, from skb->sk. If neither is set, we hit a (benign) WARN_ON_ONCE(). Trying both dev and sk covers most cases, but not all, as recently reported by Christoph Paasch. In case of nf-generated tcp reset, both sk and dev are NULL: WARNING: .. net/core/flow_dissector.c:1104 skb_flow_dissect_flow_keys include/linux/skbuff.h:1536 [inline] skb_get_hash include/linux/skbuff.h:1578 [inline] nft_trace_init+0x7d/0x120 net/netfilter/nf_tables_trace.c:320 nft_do_chain+0xb26/0xb90 net/netfilter/nf_tables_core.c:268 nft_do_chain_ipv4+0x7a/0xa0 net/netfilter/nft_chain_filter.c:23 nf_hook_slow+0x57/0x160 net/netfilter/core.c:626 __ip_local_out+0x21d/0x260 net/ipv4/ip_output.c:118 ip_local_out+0x26/0x1e0 net/ipv4/ip_output.c:127 nf_send_reset+0x58c/0x700 net/ipv4/netfilter/nf_reject_ipv4.c:308 nft_reject_ipv4_eval+0x53/0x90 net/ipv4/netfilter/nft_reject_ipv4.c:30 [..] syzkaller did something like this: table inet filter { chain input { type filter hook input priority filter; policy accept; meta nftrace set 1 tcp dport 42 reject with tcp reset } chain output { type filter hook output priority filter; policy accept; # empty chain is enough } } ... then sends a tcp packet to port 42. Initial attempt to simply set skb->dev from nf_reject_ipv4 doesn't cover all cases: skbs generated via ipv4 igmp_send_report trigger similar splat. Moreover, Pablo Neira found that nft_hash.c uses __skb_get_hash_symmetric() which would trigger same warn splat for such skbs. Lets allow callers to pass the current netns explicitly. The nf_trace infrastructure is adjusted to use the new helper. __skb_get_hash_symmetric is handled in the next patch. Reported-by: Christoph Paasch Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/494 Reviewed-by: Willem de Bruijn Signed-off-by: Florian Westphal Reviewed-by: Eric Dumazet Link: https://lore.kernel.org/r/20240608221057.16070-2-fw@strlen.de Signed-off-by: Jakub Kicinski

flow_dissector: add support for tunnel control flags

2024-06-04T09:16:38Z

Dissect [no]csum, [no]dontfrag, [no]oam, [no]crit flags from skb metadata. This is a prerequisite for matching these control flags using TC flower. Suggested-by: Ilya Maximets Signed-off-by: Davide Caratti Reviewed-by: Simon Horman Signed-off-by: Paolo Abeni

ip_tunnel: convert __be16 tunnel flags to bitmaps

2024-04-01T09:49:28Z

Historically, tunnel flags like TUNNEL_CSUM or TUNNEL_ERSPAN_OPT have been defined as __be16. Now all of those 16 bits are occupied and there's no more free space for new flags. It can't be simply switched to a bigger container with no adjustments to the values, since it's an explicit Endian storage, and on LE systems (__be16)0x0001 equals to (__be64)0x0001000000000000. We could probably define new 64-bit flags depending on the Endianness, i.e. (__be64)0x0001 on BE and (__be64)0x00010000... on LE, but that would introduce an Endianness dependency and spawn a ton of Sparse warnings. To mitigate them, all of those places which were adjusted with this change would be touched anyway, so why not define stuff properly if there's no choice. Define IP_TUNNEL_*_BIT counterparts as a bit number instead of the value already coded and a fistful of <16 <-> bitmap> converters and helpers. The two flags which have a different bit position are SIT_ISATAP_BIT and VTI_ISVTI_BIT, as they were defined not as __cpu_to_be16(), but as (__force __be16), i.e. had different positions on LE and BE. Now they both have strongly defined places. Change all __be16 fields which were used to store those flags, to IP_TUNNEL_DECLARE_FLAGS() -> DECLARE_BITMAP(__IP_TUNNEL_FLAG_NUM) -> unsigned long[1] for now, and replace all TUNNEL_* occurrences to their bitmap counterparts. Use the converters in the places which talk to the userspace, hardware (NFP) or other hosts (GRE header). The rest must explicitly use the new flags only. This must be done at once, otherwise there will be too many conversions throughout the code in the intermediate commits. Finally, disable the old __be16 flags for use in the kernel code (except for the two 'irregular' flags mentioned above), to prevent any accidental (mis)use of them. For the userspace, nothing is changed, only additions were made. Most noticeable bloat-o-meter difference (.text): vmlinux: 307/-1 (306) gre.ko: 62/0 (62) ip_gre.ko: 941/-217 (724) [*] ip_tunnel.ko: 390/-900 (-510) [**] ip_vti.ko: 138/0 (138) ip6_gre.ko: 534/-18 (516) [*] ip6_tunnel.ko: 118/-10 (108) [*] gre_flags_to_tnl_flags() grew, but still is inlined [**] ip_tunnel_find() got uninlined, hence such decrease The average code size increase in non-extreme case is 100-200 bytes per module, mostly due to sizeof(long) > sizeof(__be16), as %__IP_TUNNEL_FLAG_NUM is less than %BITS_PER_LONG and the compilers are able to expand the majority of bitmap_*() calls here into direct operations on scalars. Reviewed-by: Simon Horman Signed-off-by: Alexander Lobakin Signed-off-by: David S. Miller