[PATCH bpf-next v4 10/15] bpf: Allow all struct_ops to use bpf_dynptr_from_skb()
From: Amery Hung <hidden>
Date: 2026-09-17 20:06:11
Also in:
bpf
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [networking] (tcx & tc bpf, sock_addr), networking [general], tc subsystem, the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Jamal Hadi Salim, Jiri Pirko, Linus Torvalds
bpf_dynptr_from_skb() was only made available to bpf_qdisc, so far the only struct_ops type that needs to read an skb. The upcoming bpf_tcp_ops header-option hooks (parse_hdr/write_hdr_opt) also want to access the TCP options of an skb through a dynptr. All struct_ops programs share BPF_PROG_TYPE_STRUCT_OPS, so register bpf_kfunc_set_skb (which holds bpf_dynptr_from_skb) for that program type once, instead of per struct_ops. This makes bpf_dynptr_from_skb() available to bpf_tcp_ops and any future struct_ops. With the kfunc now provided to all of struct_ops, the bpf_qdisc-specific registration becomes redundant and is dropped: bpf_qdisc_kfunc_filter() only constrains kfuncs listed in qdisc_kfunc_ids, so removing bpf_dynptr_from_skb from that set (and from qdisc_common_kfunc_set) lets it fall through the filter unchanged, and bpf_qdisc keeps access via the generic struct_ops registration. Widening the registration is safe: a struct_ops that does not receive an skb in its context has nothing to pass to the helper. Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com> Signed-off-by: Amery Hung <redacted> --- net/core/filter.c | 1 + net/sched/bpf_qdisc.c | 2 -- 2 files changed, 1 insertion(+), 2 deletions(-)
diff --git a/net/core/filter.c b/net/core/filter.c
index 61940e753552..47b7a8f73069 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c@@ -12887,6 +12887,7 @@ static int __init bpf_kfunc_init(void) ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_LWT_SEG6LOCAL, &bpf_kfunc_set_skb); ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_NETFILTER, &bpf_kfunc_set_skb); ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &bpf_kfunc_set_skb); + ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &bpf_kfunc_set_skb); ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &bpf_kfunc_set_skb_meta); ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_ACT, &bpf_kfunc_set_skb_meta); ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &bpf_kfunc_set_xdp);
diff --git a/net/sched/bpf_qdisc.c b/net/sched/bpf_qdisc.c
index 098ca02aed89..5691c13781a8 100644
--- a/net/sched/bpf_qdisc.c
+++ b/net/sched/bpf_qdisc.c@@ -280,7 +280,6 @@ BTF_KFUNCS_START(qdisc_kfunc_ids) BTF_ID_FLAGS(func, bpf_skb_get_hash) BTF_ID_FLAGS(func, bpf_kfree_skb, KF_RELEASE) BTF_ID_FLAGS(func, bpf_qdisc_skb_drop, KF_RELEASE) -BTF_ID_FLAGS(func, bpf_dynptr_from_skb) BTF_ID_FLAGS(func, bpf_qdisc_watchdog_schedule) BTF_ID_FLAGS(func, bpf_qdisc_init_prologue) BTF_ID_FLAGS(func, bpf_qdisc_reset_destroy_epilogue)
@@ -290,7 +289,6 @@ BTF_KFUNCS_END(qdisc_kfunc_ids) BTF_SET_START(qdisc_common_kfunc_set) BTF_ID(func, bpf_skb_get_hash) BTF_ID(func, bpf_kfree_skb) -BTF_ID(func, bpf_dynptr_from_skb) BTF_SET_END(qdisc_common_kfunc_set) BTF_SET_START(qdisc_enqueue_kfunc_set)
--
2.52.0