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path: root/include/linux/skbuff.h
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2022-03-03net: ipv6: Get rcv timestamp if needed when handling hop-by-hop IOAM optionMartin KaFai Lau
IOAM is a hop-by-hop option with a temporary iana allocation (49). Since it is hop-by-hop, it is done before the input routing decision. One of the traced data field is the (rcv) timestamp. When the locally generated skb is looping from egress to ingress over a virtual interface (e.g. veth, loopback...), skb->tstamp may have the delivery time before it is known that it will be delivered locally and received by another sk. Like handling the network tapping (tcpdump) in the earlier patch, this patch gets the timestamp if needed without over-writing the delivery_time in the skb->tstamp. skb_tstamp_cond() is added to do the ktime_get_real() with an extra cond arg to check on top of the netstamp_needed_key static key. skb_tstamp_cond() will also be used in a latter patch and it needs the netstamp_needed_key check. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-03-03net: Set skb->mono_delivery_time and clear it after sch_handle_ingress()Martin KaFai Lau
The previous patches handled the delivery_time before sch_handle_ingress(). This patch can now set the skb->mono_delivery_time to flag the skb->tstamp is used as the mono delivery_time (EDT) instead of the (rcv) timestamp and also clear it with skb_clear_delivery_time() after sch_handle_ingress(). This will make the bpf_redirect_*() to keep the mono delivery_time and used by a qdisc (fq) of the egress-ing interface. A latter patch will postpone the skb_clear_delivery_time() until the stack learns that the skb is being delivered locally and that will make other kernel forwarding paths (ip[6]_forward) able to keep the delivery_time also. Thus, like the previous patches on using the skb->mono_delivery_time bit, calling skb_clear_delivery_time() is not limited within the CONFIG_NET_INGRESS to avoid too many code churns among this set. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-03-03net: Clear mono_delivery_time bit in __skb_tstamp_tx()Martin KaFai Lau
In __skb_tstamp_tx(), it may clone the egress skb and queues the clone to the sk_error_queue. The outgoing skb may have the mono delivery_time while the (rcv) timestamp is expected for the clone, so the skb->mono_delivery_time bit needs to be cleared from the clone. This patch adds the skb->mono_delivery_time clearing to the existing __net_timestamp() and use it in __skb_tstamp_tx(). The __net_timestamp() fast path usage in dev.c is changed to directly call ktime_get_real() since the mono_delivery_time bit is not set at that point. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-03-03net: Handle delivery_time in skb->tstamp during network tapping with af_packetMartin KaFai Lau
A latter patch will set the skb->mono_delivery_time to flag the skb->tstamp is used as the mono delivery_time (EDT) instead of the (rcv) timestamp. skb_clear_tstamp() will then keep this delivery_time during forwarding. This patch is to make the network tapping (with af_packet) to handle the delivery_time stored in skb->tstamp. Regardless of tapping at the ingress or egress, the tapped skb is received by the af_packet socket, so it is ingress to the af_packet socket and it expects the (rcv) timestamp. When tapping at egress, dev_queue_xmit_nit() is used. It has already expected skb->tstamp may have delivery_time, so it does skb_clone()+net_timestamp_set() to ensure the cloned skb has the (rcv) timestamp before passing to the af_packet sk. This patch only adds to clear the skb->mono_delivery_time bit in net_timestamp_set(). When tapping at ingress, it currently expects the skb->tstamp is either 0 or the (rcv) timestamp. Meaning, the tapping at ingress path has already expected the skb->tstamp could be 0 and it will get the (rcv) timestamp by ktime_get_real() when needed. There are two cases for tapping at ingress: One case is af_packet queues the skb to its sk_receive_queue. The skb is either not shared or new clone created. The newly added skb_clear_delivery_time() is called to clear the delivery_time (if any) and set the (rcv) timestamp if needed before the skb is queued to the sk_receive_queue. Another case, the ingress skb is directly copied to the rx_ring and tpacket_get_timestamp() is used to get the (rcv) timestamp. The newly added skb_tstamp() is used in tpacket_get_timestamp() to check the skb->mono_delivery_time bit before returning skb->tstamp. As mentioned earlier, the tapping@ingress has already expected the skb may not have the (rcv) timestamp (because no sk has asked for it) and has handled this case by directly calling ktime_get_real(). Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-03-03net: Add skb_clear_tstamp() to keep the mono delivery_timeMartin KaFai Lau
Right now, skb->tstamp is reset to 0 whenever the skb is forwarded. If skb->tstamp has the mono delivery_time, clearing it can hurt the performance when it finally transmits out to fq@phy-dev. The earlier patch added a skb->mono_delivery_time bit to flag the skb->tstamp carrying the mono delivery_time. This patch adds skb_clear_tstamp() helper which keeps the mono delivery_time and clears everything else. The delivery_time clearing will be postponed until the stack knows the skb will be delivered locally. It will be done in a latter patch. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-03-03net: Add skb->mono_delivery_time to distinguish mono delivery_time from ↵Martin KaFai Lau
(rcv) timestamp skb->tstamp was first used as the (rcv) timestamp. The major usage is to report it to the user (e.g. SO_TIMESTAMP). Later, skb->tstamp is also set as the (future) delivery_time (e.g. EDT in TCP) during egress and used by the qdisc (e.g. sch_fq) to make decision on when the skb can be passed to the dev. Currently, there is no way to tell skb->tstamp having the (rcv) timestamp or the delivery_time, so it is always reset to 0 whenever forwarded between egress and ingress. While it makes sense to always clear the (rcv) timestamp in skb->tstamp to avoid confusing sch_fq that expects the delivery_time, it is a performance issue [0] to clear the delivery_time if the skb finally egress to a fq@phy-dev. For example, when forwarding from egress to ingress and then finally back to egress: tcp-sender => veth@netns => veth@hostns => fq@eth0@hostns ^ ^ reset rest This patch adds one bit skb->mono_delivery_time to flag the skb->tstamp is storing the mono delivery_time (EDT) instead of the (rcv) timestamp. The current use case is to keep the TCP mono delivery_time (EDT) and to be used with sch_fq. A latter patch will also allow tc-bpf@ingress to read and change the mono delivery_time. In the future, another bit (e.g. skb->user_delivery_time) can be added for the SCM_TXTIME where the clock base is tracked by sk->sk_clockid. [ This patch is a prep work. The following patches will get the other parts of the stack ready first. Then another patch after that will finally set the skb->mono_delivery_time. ] skb_set_delivery_time() function is added. It is used by the tcp_output.c and during ip[6] fragmentation to assign the delivery_time to the skb->tstamp and also set the skb->mono_delivery_time. A note on the change in ip_send_unicast_reply() in ip_output.c. It is only used by TCP to send reset/ack out of a ctl_sk. Like the new skb_set_delivery_time(), this patch sets the skb->mono_delivery_time to 0 for now as a place holder. It will be enabled in a latter patch. A similar case in tcp_ipv6 can be done with skb_set_delivery_time() in tcp_v6_send_response(). [0] (slide 22): https://linuxplumbersconf.org/event/11/contributions/953/attachments/867/1658/LPC_2021_BPF_Datapath_Extensions.pdf Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-02-26net: neigh: use kfree_skb_reason() for __neigh_event_send()Menglong Dong
Replace kfree_skb() used in __neigh_event_send() with kfree_skb_reason(). Following drop reasons are added: SKB_DROP_REASON_NEIGH_FAILED SKB_DROP_REASON_NEIGH_QUEUEFULL SKB_DROP_REASON_NEIGH_DEAD The first two reasons above should be the hot path that skb drops in neighbour subsystem. Reviewed-by: Mengen Sun <mengensun@tencent.com> Reviewed-by: Hao Peng <flyingpeng@tencent.com> Signed-off-by: Menglong Dong <imagedong@tencent.com> Reviewed-by: David Ahern <dsahern@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-02-26net: ip: add skb drop reasons for ip egress pathMenglong Dong
Replace kfree_skb() which is used in the packet egress path of IP layer with kfree_skb_reason(). Functions that are involved include: __ip_queue_xmit() ip_finish_output() ip_mc_finish_output() ip6_output() ip6_finish_output() ip6_finish_output2() Following new drop reasons are introduced: SKB_DROP_REASON_IP_OUTNOROUTES SKB_DROP_REASON_BPF_CGROUP_EGRESS SKB_DROP_REASON_IPV6DISABLED SKB_DROP_REASON_NEIGH_CREATEFAIL Reviewed-by: Mengen Sun <mengensun@tencent.com> Reviewed-by: Hao Peng <flyingpeng@tencent.com> Signed-off-by: Menglong Dong <imagedong@tencent.com> Reviewed-by: David Ahern <dsahern@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-02-22net: preserve skb_end_offset() in skb_unclone_keeptruesize()Eric Dumazet
syzbot found another way to trigger the infamous WARN_ON_ONCE(delta < len) in skb_try_coalesce() [1] I was able to root cause the issue to kfence. When kfence is in action, the following assertion is no longer true: int size = xxxx; void *ptr1 = kmalloc(size, gfp); void *ptr2 = kmalloc(size, gfp); if (ptr1 && ptr2) ASSERT(ksize(ptr1) == ksize(ptr2)); We attempted to fix these issues in the blamed commits, but forgot that TCP was possibly shifting data after skb_unclone_keeptruesize() has been used, notably from tcp_retrans_try_collapse(). So we not only need to keep same skb->truesize value, we also need to make sure TCP wont fill new tailroom that pskb_expand_head() was able to get from a addr = kmalloc(...) followed by ksize(addr) Split skb_unclone_keeptruesize() into two parts: 1) Inline skb_unclone_keeptruesize() for the common case, when skb is not cloned. 2) Out of line __skb_unclone_keeptruesize() for the 'slow path'. WARNING: CPU: 1 PID: 6490 at net/core/skbuff.c:5295 skb_try_coalesce+0x1235/0x1560 net/core/skbuff.c:5295 Modules linked in: CPU: 1 PID: 6490 Comm: syz-executor161 Not tainted 5.17.0-rc4-syzkaller-00229-g4f12b742eb2b #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:skb_try_coalesce+0x1235/0x1560 net/core/skbuff.c:5295 Code: bf 01 00 00 00 0f b7 c0 89 c6 89 44 24 20 e8 62 24 4e fa 8b 44 24 20 83 e8 01 0f 85 e5 f0 ff ff e9 87 f4 ff ff e8 cb 20 4e fa <0f> 0b e9 06 f9 ff ff e8 af b2 95 fa e9 69 f0 ff ff e8 95 b2 95 fa RSP: 0018:ffffc900063af268 EFLAGS: 00010293 RAX: 0000000000000000 RBX: 00000000ffffffd5 RCX: 0000000000000000 RDX: ffff88806fc05700 RSI: ffffffff872abd55 RDI: 0000000000000003 RBP: ffff88806e675500 R08: 00000000ffffffd5 R09: 0000000000000000 R10: ffffffff872ab659 R11: 0000000000000000 R12: ffff88806dd554e8 R13: ffff88806dd9bac0 R14: ffff88806dd9a2c0 R15: 0000000000000155 FS: 00007f18014f9700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020002000 CR3: 000000006be7a000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> tcp_try_coalesce net/ipv4/tcp_input.c:4651 [inline] tcp_try_coalesce+0x393/0x920 net/ipv4/tcp_input.c:4630 tcp_queue_rcv+0x8a/0x6e0 net/ipv4/tcp_input.c:4914 tcp_data_queue+0x11fd/0x4bb0 net/ipv4/tcp_input.c:5025 tcp_rcv_established+0x81e/0x1ff0 net/ipv4/tcp_input.c:5947 tcp_v4_do_rcv+0x65e/0x980 net/ipv4/tcp_ipv4.c:1719 sk_backlog_rcv include/net/sock.h:1037 [inline] __release_sock+0x134/0x3b0 net/core/sock.c:2779 release_sock+0x54/0x1b0 net/core/sock.c:3311 sk_wait_data+0x177/0x450 net/core/sock.c:2821 tcp_recvmsg_locked+0xe28/0x1fd0 net/ipv4/tcp.c:2457 tcp_recvmsg+0x137/0x610 net/ipv4/tcp.c:2572 inet_recvmsg+0x11b/0x5e0 net/ipv4/af_inet.c:850 sock_recvmsg_nosec net/socket.c:948 [inline] sock_recvmsg net/socket.c:966 [inline] sock_recvmsg net/socket.c:962 [inline] ____sys_recvmsg+0x2c4/0x600 net/socket.c:2632 ___sys_recvmsg+0x127/0x200 net/socket.c:2674 __sys_recvmsg+0xe2/0x1a0 net/socket.c:2704 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae Fixes: c4777efa751d ("net: add and use skb_unclone_keeptruesize() helper") Fixes: 097b9146c0e2 ("net: fix up truesize of cloned skb in skb_prepare_for_shift()") Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Marco Elver <elver@google.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-02-22net: add skb_set_end_offset() helperEric Dumazet
We have multiple places where this helper is convenient, and plan using it in the following patch. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-02-20net: tcp: use tcp_drop_reason() for tcp_data_queue_ofo()Menglong Dong
Replace tcp_drop() used in tcp_data_queue_ofo with tcp_drop_reason(). Following drop reasons are introduced: SKB_DROP_REASON_TCP_OFOMERGE Reviewed-by: Mengen Sun <mengensun@tencent.com> Reviewed-by: Hao Peng <flyingpeng@tencent.com> Signed-off-by: Menglong Dong <imagedong@tencent.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Reviewed-by: David Ahern <dsahern@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-02-20net: tcp: use tcp_drop_reason() for tcp_data_queue()Menglong Dong
Replace tcp_drop() used in tcp_data_queue() with tcp_drop_reason(). Following drop reasons are introduced: SKB_DROP_REASON_TCP_ZEROWINDOW SKB_DROP_REASON_TCP_OLD_DATA SKB_DROP_REASON_TCP_OVERWINDOW SKB_DROP_REASON_TCP_OLD_DATA is used for the case that end_seq of skb less than the left edges of receive window. (Maybe there is a better name?) Reviewed-by: Mengen Sun <mengensun@tencent.com> Reviewed-by: Hao Peng <flyingpeng@tencent.com> Signed-off-by: Menglong Dong <imagedong@tencent.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Reviewed-by: David Ahern <dsahern@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-02-20net: tcp: use tcp_drop_reason() for tcp_rcv_established()Menglong Dong
Replace tcp_drop() used in tcp_rcv_established() with tcp_drop_reason(). Following drop reasons are added: SKB_DROP_REASON_TCP_FLAGS Reviewed-by: Mengen Sun <mengensun@tencent.com> Reviewed-by: Hao Peng <flyingpeng@tencent.com> Signed-off-by: Menglong Dong <imagedong@tencent.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Reviewed-by: David Ahern <dsahern@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-02-20net: tcp: add skb drop reasons to tcp_add_backlog()Menglong Dong
Pass the address of drop_reason to tcp_add_backlog() to store the reasons for skb drops when fails. Following drop reasons are introduced: SKB_DROP_REASON_SOCKET_BACKLOG Reviewed-by: Mengen Sun <mengensun@tencent.com> Reviewed-by: Hao Peng <flyingpeng@tencent.com> Signed-off-by: Menglong Dong <imagedong@tencent.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Reviewed-by: David Ahern <dsahern@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-02-20net: tcp: add skb drop reasons to tcp_v{4,6}_inbound_md5_hash()Menglong Dong
Pass the address of drop reason to tcp_v4_inbound_md5_hash() and tcp_v6_inbound_md5_hash() to store the reasons for skb drops when this function fails. Therefore, the drop reason can be passed to kfree_skb_reason() when the skb needs to be freed. Following drop reasons are added: SKB_DROP_REASON_TCP_MD5NOTFOUND SKB_DROP_REASON_TCP_MD5UNEXPECTED SKB_DROP_REASON_TCP_MD5FAILURE SKB_DROP_REASON_TCP_MD5* above correspond to LINUX_MIB_TCPMD5* Reviewed-by: Mengen Sun <mengensun@tencent.com> Reviewed-by: Hao Peng <flyingpeng@tencent.com> Signed-off-by: Menglong Dong <imagedong@tencent.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Reviewed-by: David Ahern <dsahern@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-02-07net: udp: use kfree_skb_reason() in __udp_queue_rcv_skb()Menglong Dong
Replace kfree_skb() with kfree_skb_reason() in __udp_queue_rcv_skb(). Following new drop reasons are introduced: SKB_DROP_REASON_SOCKET_RCVBUFF SKB_DROP_REASON_PROTO_MEM Signed-off-by: Menglong Dong <imagedong@tencent.com> Reviewed-by: David Ahern <dsahern@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-02-07net: ipv4: use kfree_skb_reason() in ip_protocol_deliver_rcu()Menglong Dong
Replace kfree_skb() with kfree_skb_reason() in ip_protocol_deliver_rcu(). Following new drop reasons are introduced: SKB_DROP_REASON_XFRM_POLICY SKB_DROP_REASON_IP_NOPROTO Signed-off-by: Menglong Dong <imagedong@tencent.com> Reviewed-by: David Ahern <dsahern@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-02-07net: ipv4: use kfree_skb_reason() in ip_rcv_finish_core()Menglong Dong
Replace kfree_skb() with kfree_skb_reason() in ip_rcv_finish_core(), following drop reasons are introduced: SKB_DROP_REASON_IP_RPFILTER SKB_DROP_REASON_UNICAST_IN_L2_MULTICAST Signed-off-by: Menglong Dong <imagedong@tencent.com> Reviewed-by: David Ahern <dsahern@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-02-07net: ipv4: use kfree_skb_reason() in ip_rcv_core()Menglong Dong
Replace kfree_skb() with kfree_skb_reason() in ip_rcv_core(). Three new drop reasons are introduced: SKB_DROP_REASON_OTHERHOST SKB_DROP_REASON_IP_CSUM SKB_DROP_REASON_IP_INHDR Signed-off-by: Menglong Dong <imagedong@tencent.com> Reviewed-by: David Ahern <dsahern@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-02-07net: netfilter: use kfree_drop_reason() for NF_DROPMenglong Dong
Replace kfree_skb() with kfree_skb_reason() in nf_hook_slow() when skb is dropped by reason of NF_DROP. Following new drop reasons are introduced: SKB_DROP_REASON_NETFILTER_DROP Signed-off-by: Menglong Dong <imagedong@tencent.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-02-07net: skb_drop_reason: add document for drop reasonsMenglong Dong
Add document for following existing drop reasons: SKB_DROP_REASON_NOT_SPECIFIED SKB_DROP_REASON_NO_SOCKET SKB_DROP_REASON_PKT_TOO_SMALL SKB_DROP_REASON_TCP_CSUM SKB_DROP_REASON_SOCKET_FILTER SKB_DROP_REASON_UDP_CSUM Signed-off-by: Menglong Dong <imagedong@tencent.com> Reviewed-by: David Ahern <dsahern@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-01-27Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netJakub Kicinski
No conflicts. Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-01-27net: socket: rename SKB_DROP_REASON_SOCKET_FILTERMenglong Dong
Rename SKB_DROP_REASON_SOCKET_FILTER, which is used as the reason of skb drop out of socket filter before it's part of a released kernel. It will be used for more protocols than just TCP in future series. Signed-off-by: Menglong Dong <imagedong@tencent.com> Reviewed-by: David Ahern <dsahern@kernel.org> Link: https://lore.kernel.org/all/20220127091308.91401-2-imagedong@tencent.com/ Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-01-27net: remove net_invalid_timestamp()Jakub Kicinski
No callers since v3.15. Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-01-21net: skbuff: add size metadata to skb_shared_info for xdpLorenzo Bianconi
Introduce xdp_frags_size field in skb_shared_info data structure to store xdp_buff/xdp_frame frame paged size (xdp_frags_size will be used in xdp frags support). In order to not increase skb_shared_info size we will use a hole due to skb_shared_info alignment. Acked-by: Toke Hoiland-Jorgensen <toke@redhat.com> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org> Link: https://lore.kernel.org/r/8a849819a3e0a143d540f78a3a5add76e17e980d.1642758637.git.lorenzo@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-01-09Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netJakub Kicinski
Merge in fixes directly in prep for the 5.17 merge window. No conflicts. Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-01-09net: skb: use kfree_skb_reason() in __udp4_lib_rcv()Menglong Dong
Replace kfree_skb() with kfree_skb_reason() in __udp4_lib_rcv. New drop reason 'SKB_DROP_REASON_UDP_CSUM' is added for udp csum error. Signed-off-by: Menglong Dong <imagedong@tencent.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-01-09net: skb: use kfree_skb_reason() in tcp_v4_rcv()Menglong Dong
Replace kfree_skb() with kfree_skb_reason() in tcp_v4_rcv(). Following drop reasons are added: SKB_DROP_REASON_NO_SOCKET SKB_DROP_REASON_PKT_TOO_SMALL SKB_DROP_REASON_TCP_CSUM SKB_DROP_REASON_TCP_FILTER After this patch, 'kfree_skb' event will print message like this: $ TASK-PID CPU# ||||| TIMESTAMP FUNCTION $ | | | ||||| | | <idle>-0 [000] ..s1. 36.113438: kfree_skb: skbaddr=(____ptrval____) protocol=2048 location=(____ptrval____) reason: NO_SOCKET The reason of skb drop is printed too. Signed-off-by: Menglong Dong <imagedong@tencent.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-01-09net: skb: introduce kfree_skb_reason()Menglong Dong
Introduce the interface kfree_skb_reason(), which is able to pass the reason why the skb is dropped to 'kfree_skb' tracepoint. Add the 'reason' field to 'trace_kfree_skb', therefor user can get more detail information about abnormal skb with 'drop_monitor' or eBPF. All drop reasons are defined in the enum 'skb_drop_reason', and they will be print as string in 'kfree_skb' tracepoint in format of 'reason: XXX'. ( Maybe the reasons should be defined in a uapi header file, so that user space can use them? ) Signed-off-by: Menglong Dong <imagedong@tencent.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-01-09net: openvswitch: Fix ct_state nat flags for conns arriving from tcPaul Blakey
Netfilter conntrack maintains NAT flags per connection indicating whether NAT was configured for the connection. Openvswitch maintains NAT flags on the per packet flow key ct_state field, indicating whether NAT was actually executed on the packet. When a packet misses from tc to ovs the conntrack NAT flags are set. However, NAT was not necessarily executed on the packet because the connection's state might still be in NEW state. As such, openvswitch wrongly assumes that NAT was executed and sets an incorrect flow key NAT flags. Fix this, by flagging to openvswitch which NAT was actually done in act_ct via tc_skb_ext and tc_skb_cb to the openvswitch module, so the packet flow key NAT flags will be correctly set. Fixes: b57dc7c13ea9 ("net/sched: Introduce action ct") Signed-off-by: Paul Blakey <paulb@nvidia.com> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> Link: https://lore.kernel.org/r/20220106153804.26451-1-paulb@nvidia.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2021-12-29Merge tag 'for-net-next-2021-12-29' of ↵Jakub Kicinski
git://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next Luiz Augusto von Dentz says: ==================== bluetooth-next pull request for net-next: - Add support for Foxconn MT7922A - Add support for Realtek RTL8852AE - Rework HCI event handling to use skb_pull_data * tag 'for-net-next-2021-12-29' of git://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next: (62 commits) Bluetooth: MGMT: Fix spelling mistake "simultanous" -> "simultaneous" Bluetooth: vhci: Set HCI_QUIRK_VALID_LE_STATES Bluetooth: MGMT: Fix LE simultaneous roles UUID if not supported Bluetooth: hci_sync: Add check simultaneous roles support Bluetooth: hci_sync: Wait for proper events when connecting LE Bluetooth: hci_sync: Add support for waiting specific LE subevents Bluetooth: hci_sync: Add hci_le_create_conn_sync Bluetooth: hci_event: Use skb_pull_data when processing inquiry results Bluetooth: hci_sync: Push sync command cancellation to workqueue Bluetooth: hci_qca: Stop IBS timer during BT OFF Bluetooth: btusb: Add support for Foxconn MT7922A Bluetooth: btintel: Add missing quirks and msft ext for legacy bootloader Bluetooth: btusb: Add two more Bluetooth parts for WCN6855 Bluetooth: L2CAP: Fix using wrong mode Bluetooth: hci_sync: Fix not always pausing advertising when necessary Bluetooth: mgmt: Make use of mgmt_send_event_skb in MGMT_EV_DEVICE_CONNECTED Bluetooth: mgmt: Make use of mgmt_send_event_skb in MGMT_EV_DEVICE_FOUND Bluetooth: mgmt: Introduce mgmt_alloc_skb and mgmt_send_event_skb Bluetooth: btusb: Return error code when getting patch status failed Bluetooth: btusb: Handle download_firmware failure cases ... ==================== Link: https://lore.kernel.org/r/20211229211258.2290966-1-luiz.dentz@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2021-12-23Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netJakub Kicinski
include/net/sock.h commit 8f905c0e7354 ("inet: fully convert sk->sk_rx_dst to RCU rules") commit 43f51df41729 ("net: move early demux fields close to sk_refcnt") https://lore.kernel.org/all/20211222141641.0caa0ab3@canb.auug.org.au/ Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2021-12-17net: openvswitch: Fix matching zone id for invalid conns arriving from tcPaul Blakey
Zone id is not restored if we passed ct and ct rejected the connection, as there is no ct info on the skb. Save the zone from tc skb cb to tc skb extension and pass it on to ovs, use that info to restore the zone id for invalid connections. Fixes: d29334c15d33 ("net/sched: act_api: fix miss set post_ct for ovs after do conntrack in act_ct") Signed-off-by: Paul Blakey <paulb@nvidia.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2021-12-17net/sched: flow_dissector: Fix matching on zone id for invalid connsPaul Blakey
If ct rejects a flow, it removes the conntrack info from the skb. act_ct sets the post_ct variable so the dissector will see this case as an +tracked +invalid state, but the zone id is lost with the conntrack info. To restore the zone id on such cases, set the last executed zone, via the tc control block, when passing ct, and read it back in the dissector if there is no ct info on the skb (invalid connection). Fixes: 7baf2429a1a9 ("net/sched: cls_flower add CT_FLAGS_INVALID flag support") Signed-off-by: Paul Blakey <paulb@nvidia.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2021-12-09skbuff: Extract list pointers to silence compiler warningsKees Cook
Under both -Warray-bounds and the object_size sanitizer, the compiler is upset about accessing prev/next of sk_buff when the object it thinks it is coming from is sk_buff_head. The warning is a false positive due to the compiler taking a conservative approach, opting to warn at casting time rather than access time. However, in support of enabling -Warray-bounds globally (which has found many real bugs), arrange things for sk_buff so that the compiler can unambiguously see that there is no intention to access anything except prev/next. Introduce and cast to a separate struct sk_buff_list, which contains _only_ the first two fields, silencing the warnings: In file included from ./include/net/net_namespace.h:39, from ./include/linux/netdevice.h:37, from net/core/netpoll.c:17: net/core/netpoll.c: In function 'refill_skbs': ./include/linux/skbuff.h:2086:9: warning: array subscript 'struct sk_buff[0]' is partly outside array bounds of 'struct sk_buff_head[1]' [-Warray-bounds] 2086 | __skb_insert(newsk, next->prev, next, list); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ net/core/netpoll.c:49:28: note: while referencing 'skb_pool' 49 | static struct sk_buff_head skb_pool; | ^~~~~~~~ This change results in no executable instruction differences. Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20211207062758.2324338-1-keescook@chromium.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2021-12-07skbuff: introduce skb_pull_dataLuiz Augusto von Dentz
Like skb_pull but returns the original data pointer before pulling the data after performing a check against sbk->len. This allows to change code that does "struct foo *p = (void *)skb->data;" which is hard to audit and error prone, to: p = skb_pull_data(skb, sizeof(*p)); if (!p) return; Which is both safer and cleaner. Acked-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2021-12-06net: fix recent csum changesEric Dumazet
Vladimir reported csum issues after my recent change in skb_postpull_rcsum() Issue here is the following: initial skb->csum is the csum of [part to be pulled][rest of packet] Old code: skb->csum = csum_sub(skb->csum, csum_partial(pull, pull_length, 0)); New code: skb->csum = ~csum_partial(pull, pull_length, ~skb->csum); This is broken if the csum of [pulled part] happens to be equal to skb->csum, because end result of skb->csum is 0 in new code, instead of being 0xffffffff David Laight suggested to use skb->csum = -csum_partial(pull, pull_length, -skb->csum); I based my patches on existing code present in include/net/seg6.h, update_csum_diff4() and update_csum_diff16() which might need a similar fix. I guess that my tests, mostly pulling 40 bytes of IPv6 header were not providing enough entropy to hit this bug. v2: added wsum_negate() to make sparse happy. Fixes: 29c3002644bd ("net: optimize skb_postpull_rcsum()") Fixes: 0bd28476f636 ("gro: optimize skb_gro_postpull_rcsum()") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Vladimir Oltean <vladimir.oltean@nxp.com> Suggested-by: David Laight <David.Laight@ACULAB.COM> Cc: David Lebrun <dlebrun@google.com> Tested-by: Vladimir Oltean <vladimir.oltean@nxp.com> Link: https://lore.kernel.org/r/20211204045356.3659278-1-eric.dumazet@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2021-11-25net: optimize skb_postpull_rcsum()Eric Dumazet
Remove one pair of add/adc instructions and their dependency against carry flag. We can leverage third argument to csum_partial(): X = csum_block_sub(X, csum_partial(start, len, 0), 0); --> X = csum_block_add(X, ~csum_partial(start, len, 0), 0); --> X = ~csum_partial(start, len, ~X); Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2021-11-22skbuff: Switch structure bounds to struct_group()Kees Cook
In preparation for FORTIFY_SOURCE performing compile-time and run-time field bounds checking for memcpy(), memmove(), and memset(), avoid intentionally writing across neighboring fields. Replace the existing empty member position markers "headers_start" and "headers_end" with a struct_group(). This will allow memcpy() and sizeof() to more easily reason about sizes, and improve readability. "pahole" shows no size nor member offset changes to struct sk_buff. "objdump -d" shows no object code changes (outside of WARNs affected by source line number changes). Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org> Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com> # drivers/net/wireguard/* Link: https://lore.kernel.org/lkml/20210728035006.GD35706@embeddedor Signed-off-by: David S. Miller <davem@davemloft.net>
2021-11-22skbuff: Move conditional preprocessor directives out of struct sk_buffKees Cook
In preparation for using the struct_group() macro in struct sk_buff, move the conditional preprocessor directives out of the region of struct sk_buff that will be enclosed by struct_group(). While GCC and Clang are happy with conditional preprocessor directives here, sparse is not, even under -Wno-directive-within-macro[1], as would be seen under a C=1 build: net/core/filter.c: note: in included file (through include/linux/netlink.h, include/linux/sock_diag.h): ./include/linux/skbuff.h:820:1: warning: directive in macro's argument list ./include/linux/skbuff.h:822:1: warning: directive in macro's argument list ./include/linux/skbuff.h:846:1: warning: directive in macro's argument list ./include/linux/skbuff.h:848:1: warning: directive in macro's argument list Additionally remove empty macro argument definitions and usage. "objdump -d" shows no object code differences. [1] https://www.spinics.net/lists/linux-sparse/msg10857.html Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2021-11-18Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netJakub Kicinski
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2021-11-18tcp: add missing htmldocs for skb->ll_node and sk->defer_listEric Dumazet
Add missing entries to fix these "make htmldocs" warnings. ./include/linux/skbuff.h:953: warning: Function parameter or member 'll_node' not described in 'sk_buff' ./include/net/sock.h:540: warning: Function parameter or member 'defer_list' not described in 'sock' Fixes: f35f821935d8 ("tcp: defer skb freeing after socket lock is released") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2021-11-16tcp: defer skb freeing after socket lock is releasedEric Dumazet
tcp recvmsg() (or rx zerocopy) spends a fair amount of time freeing skbs after their payload has been consumed. A typical ~64KB GRO packet has to release ~45 page references, eventually going to page allocator for each of them. Currently, this freeing is performed while socket lock is held, meaning that there is a high chance that BH handler has to queue incoming packets to tcp socket backlog. This can cause additional latencies, because the user thread has to process the backlog at release_sock() time, and while doing so, additional frames can be added by BH handler. This patch adds logic to defer these frees after socket lock is released, or directly from BH handler if possible. Being able to free these skbs from BH handler helps a lot, because this avoids the usual alloc/free assymetry, when BH handler and user thread do not run on same cpu or NUMA node. One cpu can now be fully utilized for the kernel->user copy, and another cpu is handling BH processing and skb/page allocs/frees (assuming RFS is not forcing use of a single CPU) Tested: 100Gbit NIC Max throughput for one TCP_STREAM flow, over 10 runs MTU : 1500 Before: 55 Gbit After: 66 Gbit MTU : 4096+(headers) Before: 82 Gbit After: 95 Gbit Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2021-11-15net: Clean up some inconsistent indentingJiapeng Chong
Eliminate the follow smatch warning: ./include/linux/skbuff.h:4229 skb_remcsum_process() warn: inconsistent indenting. Reported-by: Abaci Robot <abaci@linux.alibaba.com> Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2021-11-03net: avoid double accounting for pure zerocopy skbsTalal Ahmad
Track skbs containing only zerocopy data and avoid charging them to kernel memory to correctly account the memory utilization for msg_zerocopy. All of the data in such skbs is held in user pages which are already accounted to user. Before this change, they are charged again in kernel in __zerocopy_sg_from_iter. The charging in kernel is excessive because data is not being copied into skb frags. This excessive charging can lead to kernel going into memory pressure state which impacts all sockets in the system adversely. Mark pure zerocopy skbs with a SKBFL_PURE_ZEROCOPY flag and remove charge/uncharge for data in such skbs. Initially, an skb is marked pure zerocopy when it is empty and in zerocopy path. skb can then change from a pure zerocopy skb to mixed data skb (zerocopy and copy data) if it is at tail of write queue and there is room available in it and non-zerocopy data is being sent in the next sendmsg call. At this time sk_mem_charge is done for the pure zerocopied data and the pure zerocopy flag is unmarked. We found that this happens very rarely on workloads that pass MSG_ZEROCOPY. A pure zerocopy skb can later be coalesced into normal skb if they are next to each other in queue but this patch prevents coalescing from happening. This avoids complexity of charging when skb downgrades from pure zerocopy to mixed. This is also rare. In sk_wmem_free_skb, if it is a pure zerocopy skb, an sk_mem_uncharge for SKB_TRUESIZE(skb_end_offset(skb)) is done for sk_mem_charge in tcp_skb_entail for an skb without data. Testing with the msg_zerocopy.c benchmark between two hosts(100G nics) with zerocopy showed that before this patch the 'sock' variable in memory.stat for cgroup2 that tracks sum of sk_forward_alloc, sk_rmem_alloc and sk_wmem_queued is around 1822720 and with this change it is 0. This is due to no charge to sk_forward_alloc for zerocopy data and shows memory utilization for kernel is lowered. With this commit we don't see the warning we saw in previous commit which resulted in commit 84882cf72cd774cf16fd338bdbf00f69ac9f9194. Signed-off-by: Talal Ahmad <talalahmad@google.com> Acked-by: Arjun Roy <arjunroy@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2021-11-02net: add and use skb_unclone_keeptruesize() helperEric Dumazet
While commit 097b9146c0e2 ("net: fix up truesize of cloned skb in skb_prepare_for_shift()") fixed immediate issues found when KFENCE was enabled/tested, there are still similar issues, when tcp_trim_head() hits KFENCE while the master skb is cloned. This happens under heavy networking TX workloads, when the TX completion might be delayed after incoming ACK. This patch fixes the WARNING in sk_stream_kill_queues when sk->sk_mem_queued/sk->sk_forward_alloc are not zero. Fixes: d3fb45f370d9 ("mm, kfence: insert KFENCE hooks for SLAB") Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Marco Elver <elver@google.com> Link: https://lore.kernel.org/r/20211102004555.1359210-1-eric.dumazet@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2021-11-01Revert "net: avoid double accounting for pure zerocopy skbs"Jakub Kicinski
This reverts commit f1a456f8f3fc5828d8abcad941860380ae147b1d. WARNING: CPU: 1 PID: 6819 at net/core/skbuff.c:5429 skb_try_coalesce+0x78b/0x7e0 CPU: 1 PID: 6819 Comm: xxxxxxx Kdump: loaded Tainted: G S 5.15.0-04194-gd852503f7711 #16 RIP: 0010:skb_try_coalesce+0x78b/0x7e0 Code: e8 2a bf 41 ff 44 8b b3 bc 00 00 00 48 8b 7c 24 30 e8 19 c0 41 ff 44 89 f0 48 03 83 c0 00 00 00 48 89 44 24 40 e9 47 fb ff ff <0f> 0b e9 ca fc ff ff 4c 8d 70 ff 48 83 c0 07 48 89 44 24 38 e9 61 RSP: 0018:ffff88881f449688 EFLAGS: 00010282 RAX: 00000000fffffe96 RBX: ffff8881566e4460 RCX: ffffffff82079f7e RDX: 0000000000000003 RSI: dffffc0000000000 RDI: ffff8881566e47b0 RBP: ffff8881566e46e0 R08: ffffed102619235d R09: ffffed102619235d R10: ffff888130c91ae3 R11: ffffed102619235c R12: ffff88881f4498a0 R13: 0000000000000056 R14: 0000000000000009 R15: ffff888130c91ac0 FS: 00007fec2cbb9700(0000) GS:ffff88881f440000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fec1b060d80 CR3: 00000003acf94005 CR4: 00000000003706e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <IRQ> tcp_try_coalesce+0xeb/0x290 ? tcp_parse_options+0x610/0x610 ? mark_held_locks+0x79/0xa0 tcp_queue_rcv+0x69/0x2f0 tcp_rcv_established+0xa49/0xd40 ? tcp_data_queue+0x18a0/0x18a0 tcp_v6_do_rcv+0x1c9/0x880 ? rt6_mtu_change_route+0x100/0x100 tcp_v6_rcv+0x1624/0x1830 Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2021-11-01net: avoid double accounting for pure zerocopy skbsTalal Ahmad
Track skbs with only zerocopy data and avoid charging them to kernel memory to correctly account the memory utilization for msg_zerocopy. All of the data in such skbs is held in user pages which are already accounted to user. Before this change, they are charged again in kernel in __zerocopy_sg_from_iter. The charging in kernel is excessive because data is not being copied into skb frags. This excessive charging can lead to kernel going into memory pressure state which impacts all sockets in the system adversely. Mark pure zerocopy skbs with a SKBFL_PURE_ZEROCOPY flag and remove charge/uncharge for data in such skbs. Initially, an skb is marked pure zerocopy when it is empty and in zerocopy path. skb can then change from a pure zerocopy skb to mixed data skb (zerocopy and copy data) if it is at tail of write queue and there is room available in it and non-zerocopy data is being sent in the next sendmsg call. At this time sk_mem_charge is done for the pure zerocopied data and the pure zerocopy flag is unmarked. We found that this happens very rarely on workloads that pass MSG_ZEROCOPY. A pure zerocopy skb can later be coalesced into normal skb if they are next to each other in queue but this patch prevents coalescing from happening. This avoids complexity of charging when skb downgrades from pure zerocopy to mixed. This is also rare. In sk_wmem_free_skb, if it is a pure zerocopy skb, an sk_mem_uncharge for SKB_TRUESIZE(MAX_TCP_HEADER) is done for sk_mem_charge in tcp_skb_entail for an skb without data. Testing with the msg_zerocopy.c benchmark between two hosts(100G nics) with zerocopy showed that before this patch the 'sock' variable in memory.stat for cgroup2 that tracks sum of sk_forward_alloc, sk_rmem_alloc and sk_wmem_queued is around 1822720 and with this change it is 0. This is due to no charge to sk_forward_alloc for zerocopy data and shows memory utilization for kernel is lowered. Signed-off-by: Talal Ahmad <talalahmad@google.com> Acked-by: Arjun Roy <arjunroy@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2021-10-29mctp: Add flow extension to skbJeremy Kerr
This change adds a new skb extension for MCTP, to represent a request/response flow. The intention is to use this in a later change to allow i2c controllers to correctly configure a multiplexer over a flow. Since we have a cleanup function in the core path (if an extension is present), we'll need to make CONFIG_MCTP a bool, rather than a tristate. Includes a fix for a build warning with clang: Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2021-10-14netfilter: Introduce egress hookLukas Wunner
Support classifying packets with netfilter on egress to satisfy user requirements such as: * outbound security policies for containers (Laura) * filtering and mangling intra-node Direct Server Return (DSR) traffic on a load balancer (Laura) * filtering locally generated traffic coming in through AF_PACKET, such as local ARP traffic generated for clustering purposes or DHCP (Laura; the AF_PACKET plumbing is contained in a follow-up commit) * L2 filtering from ingress and egress for AVB (Audio Video Bridging) and gPTP with nftables (Pablo) * in the future: in-kernel NAT64/NAT46 (Pablo) The egress hook introduced herein complements the ingress hook added by commit e687ad60af09 ("netfilter: add netfilter ingress hook after handle_ing() under unique static key"). A patch for nftables to hook up egress rules from user space has been submitted separately, so users may immediately take advantage of the feature. Alternatively or in addition to netfilter, packets can be classified with traffic control (tc). On ingress, packets are classified first by tc, then by netfilter. On egress, the order is reversed for symmetry. Conceptually, tc and netfilter can be thought of as layers, with netfilter layered above tc. Traffic control is capable of redirecting packets to another interface (man 8 tc-mirred). E.g., an ingress packet may be redirected from the host namespace to a container via a veth connection: tc ingress (host) -> tc egress (veth host) -> tc ingress (veth container) In this case, netfilter egress classifying is not performed when leaving the host namespace! That's because the packet is still on the tc layer. If tc redirects the packet to a physical interface in the host namespace such that it leaves the system, the packet is never subjected to netfilter egress classifying. That is only logical since it hasn't passed through netfilter ingress classifying either. Packets can alternatively be redirected at the netfilter layer using nft fwd. Such a packet *is* subjected to netfilter egress classifying since it has reached the netfilter layer. Internally, the skb->nf_skip_egress flag controls whether netfilter is invoked on egress by __dev_queue_xmit(). Because __dev_queue_xmit() may be called recursively by tunnel drivers such as vxlan, the flag is reverted to false after sch_handle_egress(). This ensures that netfilter is applied both on the overlay and underlying network. Interaction between tc and netfilter is possible by setting and querying skb->mark. If netfilter egress classifying is not enabled on any interface, it is patched out of the data path by way of a static_key and doesn't make a performance difference that is discernible from noise: Before: 1537 1538 1538 1537 1538 1537 Mb/sec After: 1536 1534 1539 1539 1539 1540 Mb/sec Before + tc accept: 1418 1418 1418 1419 1419 1418 Mb/sec After + tc accept: 1419 1424 1418 1419 1422 1420 Mb/sec Before + tc drop: 1620 1619 1619 1619 1620 1620 Mb/sec After + tc drop: 1616 1624 1625 1624 1622 1619 Mb/sec When netfilter egress classifying is enabled on at least one interface, a minimal performance penalty is incurred for every egress packet, even if the interface it's transmitted over doesn't have any netfilter egress rules configured. That is caused by checking dev->nf_hooks_egress against NULL. Measurements were performed on a Core i7-3615QM. Commands to reproduce: ip link add dev foo type dummy ip link set dev foo up modprobe pktgen echo "add_device foo" > /proc/net/pktgen/kpktgend_3 samples/pktgen/pktgen_bench_xmit_mode_queue_xmit.sh -i foo -n 400000000 -m "11:11:11:11:11:11" -d 1.1.1.1 Accept all traffic with tc: tc qdisc add dev foo clsact tc filter add dev foo egress bpf da bytecode '1,6 0 0 0,' Drop all traffic with tc: tc qdisc add dev foo clsact tc filter add dev foo egress bpf da bytecode '1,6 0 0 2,' Apply this patch when measuring packet drops to avoid errors in dmesg: https://lore.kernel.org/netdev/a73dda33-57f4-95d8-ea51-ed483abd6a7a@iogearbox.net/ Signed-off-by: Lukas Wunner <lukas@wunner.de> Cc: Laura García Liébana <nevola@gmail.com> Cc: John Fastabend <john.fastabend@gmail.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Eric Dumazet <edumazet@google.com> Cc: Thomas Graf <tgraf@suug.ch> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>