linux/net/sched
Willem de Bruijn c4f796c4f1 net_sched: sch_fq: convert skb->tstamp if not monotonic
FQ currently assumes skb->tstamp holds monotonic time, as used by TCP.

Users with ns_capable CAP_NET_ADMIN can transmit skbs using SO_TXTIME
with CLOCK_MONOTONIC, CLOCK_REALTIME or CLOCK_TAI clockids as of
commit 80b14dee2b ("net: Add a new socket option for a future
transmit time.")

More recently, skbs also gained tstamp_type to explicitly communicate
the clockid of skb->tstamp, with commit 4d25ca2d68 ("net: Rename
mono_delivery_time to tstamp_type for scalabilty"), commit
1693c5db6a ("net: Add additional bit to support clockid_t timestamp
type") and a few others.

Detect other clocks and convert to monotonic for use in FQ. That is,
convert fq_skb_cb(skb)->time_to_send. Do not convert skb->tstamp
itself. Network device clocks are more commonly synchronized to TAI.

Conversion may be imprecise due to clock adjustment (e.g., adjfreq)
between when SCM_TSTAMP is set and when it is converted in fq_enqueue.
The common codepath is short, so skew will be well below common pacing
operation. Even in edge cases, bursts (too soon) or beyond horizon
(too late) are indistinguishable from network conditions. To which
senders must be robust, as long as infrequent.

Avoid overflow due to negative offsets becoming huge when converting
from signed ktime_t to u64 time_to_send. Bound lower to mono 1 and
upper to now + q->horizon. This protects against bad input, e.g.,
from BPF programs.

Detect legacy BPF programs that program skb->tstamp without setting
skb->tstamp_type. Here tstamp_type is zero (SKB_CLOCK_REALTIME), but
the value will be unrealistic for realtime in the 21st century. Follow
existing TIME_UPTIME_SEC_MAX as bound between mono and realtime.

Signed-off-by: Willem de Bruijn <willemb@google.com>

----

Changes
  v1 -> v2
    - replace Fixes tag with references inside the commit message

Link: https://patch.msgid.link/20260604194221.3319080-3-willemdebruijn.kernel@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
History 2026-06-08 16:00:06 -07:00
..
act_api.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-06-04 15:29:04 -07:00
act_bpf.c net/sched: add qstats_cpu_drop_inc() helper 2026-05-04 18:59:07 -07:00
act_connmark.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
act_csum.c net: sched: act_csum: validate nested VLAN headers 2026-04-03 14:34:56 -07:00
act_ct.c net/sched: act_ct: Only release RCU read lock after ct_ft 2026-04-12 09:26:15 -07:00
act_ctinfo.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
act_gact.c net/sched: Add module aliases for cls_,sch_,act_ modules 2024-02-02 10:57:55 -08:00
act_gate.c net/sched: act_gate: snapshot parameters with RCU on replace 2026-02-27 16:10:36 -08:00
act_ife.c net/sched: add qstats_cpu_drop_inc() helper 2026-05-04 18:59:07 -07:00
act_meta_mark.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
act_meta_skbprio.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
act_meta_skbtcindex.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
act_mirred.c net/sched: act_mirred: Fix return code in early mirred redirect error paths 2026-05-28 12:26:36 +02:00
act_mpls.c net/sched: add qstats_cpu_drop_inc() helper 2026-05-04 18:59:07 -07:00
act_nat.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
act_pedit.c net/sched: fix pedit partial COW leading to page cache corruption 2026-06-04 08:29:02 -07:00
act_police.c net/sched: add qstats_cpu_drop_inc() helper 2026-05-04 18:59:07 -07:00
act_sample.c net: sched: act_sample: add action cookie to sample 2024-07-05 17:45:47 -07:00
act_simple.c net/sched: Remove redundant memset(0) call in reset_policy() 2025-08-12 17:13:29 -07:00
act_skbedit.c net/sched: add qstats_cpu_drop_inc() helper 2026-05-04 18:59:07 -07:00
act_skbmod.c net/sched: rename qstats_overlimit_inc() to qstats_cpu_overlimit_inc() 2026-04-29 16:42:44 -07:00
act_tunnel_key.c net_sched: add back BH safety to tcf_lock 2025-09-02 15:51:45 -07:00
act_vlan.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
bpf_qdisc.c bpf: net_sched: Use the correct destructor kfunc type 2026-01-12 18:53:57 -08:00
cls_api.c net: sched: cls_api: fix tc_chain_fill_node to initialize tcm_info to zero to prevent an info-leak 2026-03-30 17:56:40 -07:00
cls_basic.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
cls_bpf.c net/sched: cls_bpf: prevent unbounded recursion in offload rollback 2026-05-27 17:46:35 -07:00
cls_cgroup.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
cls_flow.c net/sched: cls_flow: fix NULL pointer dereference on shared blocks 2026-04-02 15:08:42 +02:00
cls_flower.c net/sched: cls_flower: revert unintended changes 2026-04-30 13:47:01 +02:00
cls_fw.c net/sched: cls_fw: fix NULL dereference of "old" filters before change() 2026-04-12 08:49:13 -07:00
cls_matchall.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
cls_route.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
cls_u32.c net: sched: cls_u32: Avoid memcpy() false-positive warning in u32_init_knode() 2026-03-10 19:39:35 -07:00
em_canid.c net/sched: em_canid: fix uninit-value in em_canid_match 2025-11-26 16:28:10 +01:00
em_cmp.c net: sched: fix TCF_LAYER_TRANSPORT handling in tcf_get_base_ptr() 2025-11-24 18:53:14 -08:00
em_ipset.c sched: consistently handle layer3 header accesses in the presence of VLANs 2020-07-03 14:34:53 -07:00
em_ipt.c sched: consistently handle layer3 header accesses in the presence of VLANs 2020-07-03 14:34:53 -07:00
em_meta.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
em_nbyte.c net: sched: fix TCF_LAYER_TRANSPORT handling in tcf_get_base_ptr() 2025-11-24 18:53:14 -08:00
em_text.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
em_u32.c net: fill in MODULE_DESCRIPTION()s for net/sched 2024-02-09 14:12:02 -08:00
ematch.c net_sched: reject TCF_EM_SIMPLE case for complex ematch module 2022-12-19 09:43:18 +00:00
Kconfig sched: Add enqueue/dequeue of dualpi2 qdisc 2025-07-23 17:52:07 -07:00
Makefile sched: Add enqueue/dequeue of dualpi2 qdisc 2025-07-23 17:52:07 -07:00
sch_api.c net/sched: prefer existing extack message in qdisc_offload_graft_helper() 2026-05-22 17:23:37 -07:00
sch_blackhole.c Revert "net: sched: Pass root lock to Qdisc_ops.enqueue" 2020-07-16 16:48:34 -07:00
sch_cake.c net/sched: annotate data-races around sch->qstats.backlog 2026-05-11 18:28:07 -07:00
sch_cbs.c net: sched: don't recurse on the netdev ops lock in qdiscs 2026-06-04 14:04:56 -07:00
sch_choke.c net/sched: add qdisc_qlen_inc() and qdisc_qlen_dec() 2026-05-11 18:28:07 -07:00
sch_codel.c net/sched: annotate data-races around sch->qstats.backlog 2026-05-11 18:28:07 -07:00
sch_drr.c net/sched: sch_drr: make cl->quantum lockless 2026-05-20 19:04:58 -07:00
sch_dualpi2.c net/sched: sch_dualpi2: annotate data-races in dualpi2_dump_stats() 2026-05-15 17:43:49 -07:00
sch_etf.c net/sched: add qdisc_qlen_inc() and qdisc_qlen_dec() 2026-05-11 18:28:07 -07:00
sch_ets.c net/sched: sch_ets: make cl->quantum lockless 2026-05-25 11:09:27 -07:00
sch_fifo.c pfifo_tail_enqueue: Drop new packet when sch->limit == 0 2025-02-05 18:13:58 -08:00
sch_fq.c net_sched: sch_fq: convert skb->tstamp if not monotonic 2026-06-08 16:00:06 -07:00
sch_fq_codel.c net/sched: fq_codel: local packets no longer count against memory limit 2026-05-13 19:13:41 -07:00
sch_fq_pie.c net/sched: annotate data-races around sch->qstats.backlog 2026-05-11 18:28:07 -07:00
sch_frag.c net: convert remaining ipv6_stub users to direct function calls 2026-03-29 11:21:23 -07:00
sch_generic.c net/sched: annotate data-races around sch->qstats.backlog 2026-05-11 18:28:07 -07:00
sch_gred.c net/sched: annotate data-races around sch->qstats.backlog 2026-05-11 18:28:07 -07:00
sch_hfsc.c net/sched: sch_hfsc: annotate data-races in hfsc_dump_class_stats() 2026-05-14 17:05:20 -07:00
sch_hhf.c net/sched: add qdisc_qlen_inc() and qdisc_qlen_dec() 2026-05-11 18:28:07 -07:00
sch_htb.c net/sched: sch_htb: fix htb_dump_class_stats() vs offload mode 2026-05-19 18:42:48 -07:00
sch_ingress.c clsact: Fix use-after-free in init/destroy rollback asymmetry 2026-03-17 12:09:16 +01:00
sch_mq.c net/sched: mq: no longer acquire qdisc spinlocks in dump operations 2026-05-11 18:28:08 -07:00
sch_mqprio.c net/sched: mq_prio: no longer acquire qdisc spinlocks in mqprio_dump_class_stats() 2026-05-11 18:28:08 -07:00
sch_mqprio_lib.c net: sched: Fill in missing MODULE_DESCRIPTION for qdiscs 2023-11-01 21:49:09 -07:00
sch_mqprio_lib.h net/sched: mqprio: allow per-TC user input of FP adminStatus 2023-04-13 22:22:10 -07:00
sch_multiq.c net/sched: add qdisc_qlen_inc() and qdisc_qlen_dec() 2026-05-11 18:28:07 -07:00
sch_netem.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-05-28 14:02:21 -07:00
sch_pie.c net/sched: sch_pie: annotate more data-races in pie_dump_stats() 2026-05-01 17:54:57 -07:00
sch_plug.c net/sched: Add module aliases for cls_,sch_,act_ modules 2024-02-02 10:57:55 -08:00
sch_prio.c net/sched: annotate data-races around sch->qstats.backlog 2026-05-11 18:28:07 -07:00
sch_qfq.c net/sched: annotate data-races around sch->qstats.backlog 2026-05-11 18:28:07 -07:00
sch_red.c net/sched: annotate data-races around sch->qstats.backlog 2026-05-11 18:28:07 -07:00
sch_sfb.c net/sched: annotate data-races around sch->qstats.backlog 2026-05-11 18:28:07 -07:00
sch_sfq.c net/sched: annotate data-races around sch->qstats.backlog 2026-05-11 18:28:07 -07:00
sch_skbprio.c net/sched: add qdisc_qlen_inc() and qdisc_qlen_dec() 2026-05-11 18:28:07 -07:00
sch_taprio.c net: sched: don't recurse on the netdev ops lock in qdiscs 2026-06-04 14:04:56 -07:00
sch_tbf.c net/sched: tbf: add extack to offload params 2026-05-22 17:23:37 -07:00
sch_teql.c net/sched: add qdisc_qlen_inc() and qdisc_qlen_dec() 2026-05-11 18:28:07 -07:00