kernel/net/sched/act_skbedit.c, branch linux-6.6.y

net/sched: act_skbedit: fix divide-by-zero in tcf_skbedit_hash()

2026-03-04T12:21:19Z

[ Upstream commit be054cc66f739a9ba615dba9012a07fab8e7dd6f ] Commit 38a6f0865796 ("net: sched: support hash selecting tx queue") added SKBEDIT_F_TXQ_SKBHASH support. The inclusive range size is computed as: mapping_mod = queue_mapping_max - queue_mapping + 1; The range size can be 65536 when the requested range covers all possible u16 queue IDs (e.g. queue_mapping=0 and queue_mapping_max=U16_MAX). That value cannot be represented in a u16 and previously wrapped to 0, so tcf_skbedit_hash() could trigger a divide-by-zero: queue_mapping += skb_get_hash(skb) % params->mapping_mod; Compute mapping_mod in a wider type and reject ranges larger than U16_MAX to prevent params->mapping_mod from becoming 0 and avoid the crash. Fixes: 38a6f0865796 ("net: sched: support hash selecting tx queue") Cc: stable@vger.kernel.org # 6.12+ Signed-off-by: Ruitong Liu Link: https://patch.msgid.link/20260213175948.1505257-1-cnitlrt@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net/sched: avoid indirect act functions on retpoline kernels

2022-12-09T09:18:07Z

Expose the necessary tc act functions and wire up act_api to use direct calls in retpoline kernels. Signed-off-by: Pedro Tammela Reviewed-by: Jamal Hadi Salim Reviewed-by: Victor Nogueira Signed-off-by: David S. Miller

act_skbedit: skbedit queue mapping for receive queue

2022-10-25T08:32:40Z

Add support for skbedit queue mapping action on receive side. This is supported only in hardware, so the skip_sw flag is enforced. This enables offloading filters for receive queue selection in the hardware using the skbedit action. Traffic arrives on the Rx queue requested in the skbedit action parameter. A new tc action flag TCA_ACT_FLAGS_AT_INGRESS is introduced to identify the traffic direction the action queue_mapping is requested on during filter addition. This is used to disallow offloading the skbedit queue mapping action on transmit side. Example: $tc filter add dev $IFACE ingress protocol ip flower dst_ip $DST_IP\ action skbedit queue_mapping $rxq_id skip_sw Reviewed-by: Sridhar Samudrala Signed-off-by: Amritha Nambiar Signed-off-by: Paolo Abeni

net: sched: act_skbedit: get rid of tcf_skbedit_walker and tcf_skbedit_search

2022-09-09T07:24:42Z

tcf_skbedit_walker() and tcf_skbedit_search() do the same thing as generic walk/search function, so remove them. Signed-off-by: Zhengchao Shao Acked-by: Jamal Hadi Salim Signed-off-by: David S. Miller

net: sched: act: move global static variable net_id to tc_action_ops

2022-09-09T07:24:41Z

Each tc action module has a corresponding net_id, so put net_id directly into the structure tc_action_ops. Signed-off-by: Zhengchao Shao Acked-by: Jamal Hadi Salim Signed-off-by: David S. Miller

net: sched: support hash selecting tx queue

2022-04-19T10:20:45Z

This patch allows users to pick queue_mapping, range from A to B. Then we can load balance packets from A to B tx queue. The range is an unsigned 16bit value in decimal format. $ tc filter ... action skbedit queue_mapping skbhash A B "skbedit queue_mapping QUEUE_MAPPING" (from "man 8 tc-skbedit") is enhanced with flags: SKBEDIT_F_TXQ_SKBHASH +----+ +----+ +----+ | P1 | | P2 | | Pn | +----+ +----+ +----+ | | | +-----------+-----------+ | | clsact/skbedit | MQ v +-----------+-----------+ | q0 | qn | qm v v v HTB/FQ FIFO ... FIFO For example: If P1 sends out packets to different Pods on other host, and we want distribute flows from qn - qm. Then we can use skb->hash as hash. setup commands: $ NETDEV=eth0 $ ip netns add n1 $ ip link add ipv1 link $NETDEV type ipvlan mode l2 $ ip link set ipv1 netns n1 $ ip netns exec n1 ifconfig ipv1 2.2.2.100/24 up $ tc qdisc add dev $NETDEV clsact $ tc filter add dev $NETDEV egress protocol ip prio 1 \ flower skip_hw src_ip 2.2.2.100 action skbedit queue_mapping skbhash 2 6 $ tc qdisc add dev $NETDEV handle 1: root mq $ tc qdisc add dev $NETDEV parent 1:1 handle 2: htb $ tc class add dev $NETDEV parent 2: classid 2:1 htb rate 100kbit $ tc class add dev $NETDEV parent 2: classid 2:2 htb rate 200kbit $ tc qdisc add dev $NETDEV parent 1:2 tbf rate 100mbit burst 100mb latency 1 $ tc qdisc add dev $NETDEV parent 1:3 pfifo $ tc qdisc add dev $NETDEV parent 1:4 pfifo $ tc qdisc add dev $NETDEV parent 1:5 pfifo $ tc qdisc add dev $NETDEV parent 1:6 pfifo $ tc qdisc add dev $NETDEV parent 1:7 pfifo $ ip netns exec n1 iperf3 -c 2.2.2.1 -i 1 -t 10 -P 10 pick txqueue from 2 - 6: $ ethtool -S $NETDEV | grep -i tx_queue_[0-9]_bytes tx_queue_0_bytes: 42 tx_queue_1_bytes: 0 tx_queue_2_bytes: 11442586444 tx_queue_3_bytes: 7383615334 tx_queue_4_bytes: 3981365579 tx_queue_5_bytes: 3983235051 tx_queue_6_bytes: 6706236461 tx_queue_7_bytes: 42 tx_queue_8_bytes: 0 tx_queue_9_bytes: 0 txqueues 2 - 6 are mapped to classid 1:3 - 1:7 $ tc -s class show dev $NETDEV ... class mq 1:3 root leaf 8002: Sent 11949133672 bytes 7929798 pkt (dropped 0, overlimits 0 requeues 0) backlog 0b 0p requeues 0 class mq 1:4 root leaf 8003: Sent 7710449050 bytes 5117279 pkt (dropped 0, overlimits 0 requeues 0) backlog 0b 0p requeues 0 class mq 1:5 root leaf 8004: Sent 4157648675 bytes 2758990 pkt (dropped 0, overlimits 0 requeues 0) backlog 0b 0p requeues 0 class mq 1:6 root leaf 8005: Sent 4159632195 bytes 2759990 pkt (dropped 0, overlimits 0 requeues 0) backlog 0b 0p requeues 0 class mq 1:7 root leaf 8006: Sent 7003169603 bytes 4646912 pkt (dropped 0, overlimits 0 requeues 0) backlog 0b 0p requeues 0 ... Cc: Jamal Hadi Salim Cc: Cong Wang Cc: Jiri Pirko Cc: "David S. Miller" Cc: Jakub Kicinski Cc: Jonathan Lemon Cc: Eric Dumazet Cc: Alexander Lobakin Cc: Paolo Abeni Cc: Talal Ahmad Cc: Kevin Hao Cc: Ilias Apalodimas Cc: Kees Cook Cc: Kumar Kartikeya Dwivedi Cc: Antoine Tenart Cc: Wei Wang Cc: Arnd Bergmann Signed-off-by: Tonghao Zhang Reviewed-by: Jamal Hadi Salim Signed-off-by: Paolo Abeni

net: sched: use queue_mapping to pick tx queue

2022-04-19T10:20:45Z

This patch fixes issue: * If we install tc filters with act_skbedit in clsact hook. It doesn't work, because netdev_core_pick_tx() overwrites queue_mapping. $ tc filter ... action skbedit queue_mapping 1 And this patch is useful: * We can use FQ + EDT to implement efficient policies. Tx queues are picked by xps, ndo_select_queue of netdev driver, or skb hash in netdev_core_pick_tx(). In fact, the netdev driver, and skb hash are _not_ under control. xps uses the CPUs map to select Tx queues, but we can't figure out which task_struct of pod/containter running on this cpu in most case. We can use clsact filters to classify one pod/container traffic to one Tx queue. Why ? In containter networking environment, there are two kinds of pod/ containter/net-namespace. One kind (e.g. P1, P2), the high throughput is key in these applications. But avoid running out of network resource, the outbound traffic of these pods is limited, using or sharing one dedicated Tx queues assigned HTB/TBF/FQ Qdisc. Other kind of pods (e.g. Pn), the low latency of data access is key. And the traffic is not limited. Pods use or share other dedicated Tx queues assigned FIFO Qdisc. This choice provides two benefits. First, contention on the HTB/FQ Qdisc lock is significantly reduced since fewer CPUs contend for the same queue. More importantly, Qdisc contention can be eliminated completely if each CPU has its own FIFO Qdisc for the second kind of pods. There must be a mechanism in place to support classifying traffic based on pods/container to different Tx queues. Note that clsact is outside of Qdisc while Qdisc can run a classifier to select a sub-queue under the lock. In general recording the decision in the skb seems a little heavy handed. This patch introduces a per-CPU variable, suggested by Eric. The xmit.skip_txqueue flag is firstly cleared in __dev_queue_xmit(). - Tx Qdisc may install that skbedit actions, then xmit.skip_txqueue flag is set in qdisc->enqueue() though tx queue has been selected in netdev_tx_queue_mapping() or netdev_core_pick_tx(). That flag is cleared firstly in __dev_queue_xmit(), is useful: - Avoid picking Tx queue with netdev_tx_queue_mapping() in next netdev in such case: eth0 macvlan - eth0.3 vlan - eth0 ixgbe-phy: For example, eth0, macvlan in pod, which root Qdisc install skbedit queue_mapping, send packets to eth0.3, vlan in host. In __dev_queue_xmit() of eth0.3, clear the flag, does not select tx queue according to skb->queue_mapping because there is no filters in clsact or tx Qdisc of this netdev. Same action taked in eth0, ixgbe in Host. - Avoid picking Tx queue for next packet. If we set xmit.skip_txqueue in tx Qdisc (qdisc->enqueue()), the proper way to clear it is clearing it in __dev_queue_xmit when processing next packets. For performance reasons, use the static key. If user does not config the NET_EGRESS, the patch will not be compiled. +----+ +----+ +----+ | P1 | | P2 | | Pn | +----+ +----+ +----+ | | | +-----------+-----------+ | | clsact/skbedit | MQ v +-----------+-----------+ | q0 | q1 | qn v v v HTB/FQ HTB/FQ ... FIFO Cc: Jamal Hadi Salim Cc: Cong Wang Cc: Jiri Pirko Cc: "David S. Miller" Cc: Jakub Kicinski Cc: Jonathan Lemon Cc: Eric Dumazet Cc: Alexander Lobakin Cc: Paolo Abeni Cc: Talal Ahmad Cc: Kevin Hao Cc: Ilias Apalodimas Cc: Kees Cook Cc: Kumar Kartikeya Dwivedi Cc: Antoine Tenart Cc: Wei Wang Cc: Arnd Bergmann Suggested-by: Eric Dumazet Signed-off-by: Tonghao Zhang Acked-by: Jamal Hadi Salim Signed-off-by: Paolo Abeni

net/sched: act_skbedit: Add extack messages for offload failure

2022-04-08T12:45:43Z

For better error reporting to user space, add extack messages when skbedit action offload fails. Example: # echo 1 > /sys/kernel/tracing/events/netlink/netlink_extack/enable # tc filter add dev dummy0 ingress pref 1 proto all matchall skip_sw action skbedit queue_mapping 1234 Error: cls_matchall: Failed to setup flow action. We have an error talking to the kernel # cat /sys/kernel/tracing/trace_pipe tc-185 [002] b..1. 31.802414: netlink_extack: msg=act_skbedit: Offload not supported when "queue_mapping" option is used tc-185 [002] ..... 31.802418: netlink_extack: msg=cls_matchall: Failed to setup flow action # tc filter add dev dummy0 ingress pref 1 proto all matchall skip_sw action skbedit inheritdsfield Error: cls_matchall: Failed to setup flow action. We have an error talking to the kernel # cat /sys/kernel/tracing/trace_pipe tc-187 [002] b..1. 45.985145: netlink_extack: msg=act_skbedit: Offload not supported when "inheritdsfield" option is used tc-187 [002] ..... 45.985160: netlink_extack: msg=cls_matchall: Failed to setup flow action Signed-off-by: Ido Schimmel Reviewed-by: Petr Machata Signed-off-by: David S. Miller

net/sched: act_api: Add extack to offload_act_setup() callback

2022-04-08T12:45:43Z

The callback is used by various actions to populate the flow action structure prior to offload. Pass extack to this callback so that the various actions will be able to report accurate error messages to user space. Signed-off-by: Ido Schimmel Reviewed-by: Petr Machata Signed-off-by: David S. Miller

flow_offload: allow user to offload tc action to net device

2021-12-19T14:08:48Z

Use flow_indr_dev_register/flow_indr_dev_setup_offload to offload tc action. We need to call tc_cleanup_flow_action to clean up tc action entry since in tc_setup_action, some actions may hold dev refcnt, especially the mirror action. Signed-off-by: Baowen Zheng Signed-off-by: Louis Peens Signed-off-by: Simon Horman Signed-off-by: David S. Miller