From ad9294dbc227cbc8e173b3b963e7dd9af5314f77 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Wed, 17 Jan 2018 22:36:49 +0100 Subject: [PATCH] bpf: fix cls_bpf on filter replace Running the following sequence is currently broken: # tc qdisc add dev foo clsact # tc filter replace dev foo ingress prio 1 handle 1 bpf da obj bar.o # tc filter replace dev foo ingress prio 1 handle 1 bpf da obj bar.o RTNETLINK answers: Invalid argument The normal expectation on kernel side is that the second command succeeds replacing the existing program. However, what happens is in cls_bpf_change(), we bail out with err in the second run in cls_bpf_offload(). The EINVAL comes directly in cls_bpf_offload() when comparing prog vs oldprog's gen_flags. In case of above replace the new prog's gen_flags are 0, but the old ones are 8, which means TCA_CLS_FLAGS_NOT_IN_HW is set (e.g. drivers not having cls_bpf offload). Fix 102740bd9436 ("cls_bpf: fix offload assumptions after callback conversion") in the following way: gen_flags from user space passed down via netlink cannot include status flags like TCA_CLS_FLAGS_IN_HW or TCA_CLS_FLAGS_NOT_IN_HW as opposed to oldprog that we previously loaded. Therefore, it doesn't make any sense to include them in the gen_flags comparison with the new prog before we even attempt to offload. Thus, lets fix this before 4.15 goes out. Fixes: 102740bd9436 ("cls_bpf: fix offload assumptions after callback conversion") Signed-off-by: Daniel Borkmann Acked-by: Jakub Kicinski Signed-off-by: David S. Miller --- net/sched/cls_bpf.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c index 8d78e7f4ecc3..a62586e2dbdb 100644 --- a/net/sched/cls_bpf.c +++ b/net/sched/cls_bpf.c @@ -183,10 +183,17 @@ static int cls_bpf_offload_cmd(struct tcf_proto *tp, struct cls_bpf_prog *prog, return 0; } +static u32 cls_bpf_flags(u32 flags) +{ + return flags & CLS_BPF_SUPPORTED_GEN_FLAGS; +} + static int cls_bpf_offload(struct tcf_proto *tp, struct cls_bpf_prog *prog, struct cls_bpf_prog *oldprog) { - if (prog && oldprog && prog->gen_flags != oldprog->gen_flags) + if (prog && oldprog && + cls_bpf_flags(prog->gen_flags) != + cls_bpf_flags(oldprog->gen_flags)) return -EINVAL; if (prog && tc_skip_hw(prog->gen_flags)) -- GitLab