[PATCH bpf-next v2 4/4] bpf: more lenient bpf_skb_net_shrink() with BPF_F_ADJ_ROOM_FIXED_GSO
From: Maciej Żenczykowski <hidden>
Date: 2021-06-17 00:10:22
Also in:
bpf, lkml
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [networking] (tcx & tc bpf, sock_addr), networking [general], the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
From: Maciej Żenczykowski <redacted> This is to more closely match behaviour of bpf_skb_change_proto() which now does not adjust gso_size, and thus thoretically supports all gso types, and does not need to set SKB_GSO_DODGY nor reset gso_segs to zero. Something similar should probably be done with bpf_skb_net_grow(), but that code scares me. Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Willem de Bruijn <willemb@google.com> Signed-off-by: Maciej Żenczykowski <redacted> --- net/core/filter.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-)
diff --git a/net/core/filter.c b/net/core/filter.c
index 8f05498f497e..faf2bae0309b 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c@@ -3506,11 +3506,10 @@ static int bpf_skb_net_shrink(struct sk_buff *skb, u32 off, u32 len_diff, BPF_F_ADJ_ROOM_NO_CSUM_RESET))) return -EINVAL; - if (skb_is_gso(skb) && !skb_is_gso_tcp(skb)) { - /* udp gso_size delineates datagrams, only allow if fixed */ - if (!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4) || - !(flags & BPF_F_ADJ_ROOM_FIXED_GSO)) - return -ENOTSUPP; + if (skb_is_gso(skb) && + !skb_is_gso_tcp(skb) && + !(flags & BPF_F_ADJ_ROOM_FIXED_GSO)) { + return -ENOTSUPP; } ret = skb_unclone(skb, GFP_ATOMIC);
@@ -3521,12 +3520,11 @@ static int bpf_skb_net_shrink(struct sk_buff *skb, u32 off, u32 len_diff, if (unlikely(ret < 0)) return ret; - if (skb_is_gso(skb)) { + if (skb_is_gso(skb) && !(flags & BPF_F_ADJ_ROOM_FIXED_GSO)) { struct skb_shared_info *shinfo = skb_shinfo(skb); /* Due to header shrink, MSS can be upgraded. */ - if (!(flags & BPF_F_ADJ_ROOM_FIXED_GSO)) - skb_increase_gso_size(shinfo, len_diff); + skb_increase_gso_size(shinfo, len_diff); /* Header must be checked, and gso_segs recomputed. */ shinfo->gso_type |= SKB_GSO_DODGY;
--
2.32.0.272.g935e593368-goog