From ba47396e1c042619f1c038ad19493aef737677f5 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Maciej=20=C5=BBenczykowski?= Date: Wed, 16 Jun 2021 17:09:50 -0700 Subject: [PATCH] Revert "bpf: Check for BPF_F_ADJ_ROOM_FIXED_GSO when bpf_skb_change_proto" MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit This reverts commit fa7b83bf3b156c767f3e4a25bbf3817b08f3ff8e. See the followup commit for the reasoning why I believe the appropriate approach is to simply make this change without a flag, but it can basically be summarized as using this helper without the flag is bug-prone or outright buggy, and thus the default should be this new behaviour. As this commit has only made it into net-next/master, but not into any real release, such a backwards incompatible change is still ok. Signed-off-by: Maciej Żenczykowski Signed-off-by: Daniel Borkmann Cc: Dongseok Yi Cc: Willem de Bruijn Link: https://lore.kernel.org/bpf/20210617000953.2787453-1-zenczykowski@gmail.com --- net/core/filter.c | 22 +++++++++------------- 1 file changed, 9 insertions(+), 13 deletions(-) diff --git a/net/core/filter.c b/net/core/filter.c index 0b13d81..243abf5 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -3235,7 +3235,7 @@ static int bpf_skb_net_hdr_pop(struct sk_buff *skb, u32 off, u32 len) return ret; } -static int bpf_skb_proto_4_to_6(struct sk_buff *skb, u64 flags) +static int bpf_skb_proto_4_to_6(struct sk_buff *skb) { const u32 len_diff = sizeof(struct ipv6hdr) - sizeof(struct iphdr); u32 off = skb_mac_header_len(skb); @@ -3264,9 +3264,7 @@ static int bpf_skb_proto_4_to_6(struct sk_buff *skb, u64 flags) } /* Due to IPv6 header, MSS needs to be downgraded. */ - if (!(flags & BPF_F_ADJ_ROOM_FIXED_GSO)) - skb_decrease_gso_size(shinfo, len_diff); - + skb_decrease_gso_size(shinfo, len_diff); /* Header must be checked, and gso_segs recomputed. */ shinfo->gso_type |= SKB_GSO_DODGY; shinfo->gso_segs = 0; @@ -3278,7 +3276,7 @@ static int bpf_skb_proto_4_to_6(struct sk_buff *skb, u64 flags) return 0; } -static int bpf_skb_proto_6_to_4(struct sk_buff *skb, u64 flags) +static int bpf_skb_proto_6_to_4(struct sk_buff *skb) { const u32 len_diff = sizeof(struct ipv6hdr) - sizeof(struct iphdr); u32 off = skb_mac_header_len(skb); @@ -3307,9 +3305,7 @@ static int bpf_skb_proto_6_to_4(struct sk_buff *skb, u64 flags) } /* Due to IPv4 header, 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; shinfo->gso_segs = 0; @@ -3321,17 +3317,17 @@ static int bpf_skb_proto_6_to_4(struct sk_buff *skb, u64 flags) return 0; } -static int bpf_skb_proto_xlat(struct sk_buff *skb, __be16 to_proto, u64 flags) +static int bpf_skb_proto_xlat(struct sk_buff *skb, __be16 to_proto) { __be16 from_proto = skb->protocol; if (from_proto == htons(ETH_P_IP) && to_proto == htons(ETH_P_IPV6)) - return bpf_skb_proto_4_to_6(skb, flags); + return bpf_skb_proto_4_to_6(skb); if (from_proto == htons(ETH_P_IPV6) && to_proto == htons(ETH_P_IP)) - return bpf_skb_proto_6_to_4(skb, flags); + return bpf_skb_proto_6_to_4(skb); return -ENOTSUPP; } @@ -3341,7 +3337,7 @@ BPF_CALL_3(bpf_skb_change_proto, struct sk_buff *, skb, __be16, proto, { int ret; - if (unlikely(flags & ~(BPF_F_ADJ_ROOM_FIXED_GSO))) + if (unlikely(flags)) return -EINVAL; /* General idea is that this helper does the basic groundwork @@ -3361,7 +3357,7 @@ BPF_CALL_3(bpf_skb_change_proto, struct sk_buff *, skb, __be16, proto, * that. For offloads, we mark packet as dodgy, so that headers * need to be verified first. */ - ret = bpf_skb_proto_xlat(skb, proto, flags); + ret = bpf_skb_proto_xlat(skb, proto); bpf_compute_data_pointers(skb); return ret; } -- 2.7.4