From: Dongseok Yi <dseok.yi@samsung.com>
To: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Cc: Dongseok Yi <dseok.yi@samsung.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
netdev@vger.kernel.org, bpf@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [PATCH bpf v2] bpf: check BPF_F_ADJ_ROOM_FIXED_GSO when upgrading mss in 6 to 4
Date: Tue, 11 May 2021 15:36:37 +0900 [thread overview]
Message-ID: <1620714998-120657-1-git-send-email-dseok.yi@samsung.com> (raw)
In-Reply-To: <1619690903-1138-1-git-send-email-dseok.yi@samsung.com>
In the forwarding path GRO -> BPF 6 to 4 -> GSO for TCP traffic, the
coalesced packet payload can be > MSS, but < MSS + 20.
bpf_skb_proto_6_to_4 will increase the MSS and it can be > the payload
length. After then tcp_gso_segment checks for the payload length if it
is <= MSS. The condition is causing the packet to be dropped.
tcp_gso_segment():
[...]
mss = skb_shinfo(skb)->gso_size;
if (unlikely(skb->len <= mss))
goto out;
[...]
Allow to increase MSS when BPF_F_ADJ_ROOM_FIXED_GSO is not set.
Fixes: 6578171a7ff0 (bpf: add bpf_skb_change_proto helper)
Signed-off-by: Dongseok Yi <dseok.yi@samsung.com>
---
net/core/filter.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
v2:
per Willem de Bruijn request,
checked the flag instead of a generic approach.
diff --git a/net/core/filter.c b/net/core/filter.c
index cae56d0..a98b28d 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3276,7 +3276,7 @@ static int bpf_skb_proto_4_to_6(struct sk_buff *skb)
return 0;
}
-static int bpf_skb_proto_6_to_4(struct sk_buff *skb)
+static int bpf_skb_proto_6_to_4(struct sk_buff *skb, u64 flags)
{
const u32 len_diff = sizeof(struct ipv6hdr) - sizeof(struct iphdr);
u32 off = skb_mac_header_len(skb);
@@ -3305,7 +3305,8 @@ static int bpf_skb_proto_6_to_4(struct sk_buff *skb)
}
/* Due to IPv4 header, MSS can be upgraded. */
- skb_increase_gso_size(shinfo, len_diff);
+ if (!(flags & BPF_F_ADJ_ROOM_FIXED_GSO))
+ 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;
@@ -3317,7 +3318,7 @@ static int bpf_skb_proto_6_to_4(struct sk_buff *skb)
return 0;
}
-static int bpf_skb_proto_xlat(struct sk_buff *skb, __be16 to_proto)
+static int bpf_skb_proto_xlat(struct sk_buff *skb, __be16 to_proto, u64 flags)
{
__be16 from_proto = skb->protocol;
@@ -3327,7 +3328,7 @@ static int bpf_skb_proto_xlat(struct sk_buff *skb, __be16 to_proto)
if (from_proto == htons(ETH_P_IPV6) &&
to_proto == htons(ETH_P_IP))
- return bpf_skb_proto_6_to_4(skb);
+ return bpf_skb_proto_6_to_4(skb, flags);
return -ENOTSUPP;
}
@@ -3337,7 +3338,7 @@ BPF_CALL_3(bpf_skb_change_proto, struct sk_buff *, skb, __be16, proto,
{
int ret;
- if (unlikely(flags))
+ if (unlikely(flags & ~(BPF_F_ADJ_ROOM_FIXED_GSO)))
return -EINVAL;
/* General idea is that this helper does the basic groundwork
@@ -3357,7 +3358,7 @@ 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);
+ ret = bpf_skb_proto_xlat(skb, proto, flags);
bpf_compute_data_pointers(skb);
return ret;
}
--
2.7.4
next prev parent reply other threads:[~2021-05-11 6:51 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20210429102143epcas2p4c8747c09a9de28f003c20389c050394a@epcas2p4.samsung.com>
2021-04-29 10:08 ` [PATCH bpf] bpf: check for data_len before upgrading mss when 6 to 4 Dongseok Yi
2021-05-05 20:55 ` Daniel Borkmann
2021-05-06 0:45 ` Dongseok Yi
2021-05-06 1:45 ` Willem de Bruijn
2021-05-06 2:27 ` Dongseok Yi
2021-05-06 18:21 ` Willem de Bruijn
2021-05-07 0:53 ` Dongseok Yi
2021-05-07 1:25 ` Willem de Bruijn
2021-05-07 1:45 ` Yunsheng Lin
2021-05-07 1:53 ` Willem de Bruijn
2021-05-07 8:25 ` Dongseok Yi
2021-05-07 9:11 ` Yunsheng Lin
2021-05-07 10:36 ` Dongseok Yi
2021-05-07 13:50 ` Willem de Bruijn
2021-05-10 2:22 ` Dongseok Yi
2021-05-10 13:19 ` Willem de Bruijn
2021-05-10 13:46 ` Willem de Bruijn
2021-05-11 1:11 ` Dongseok Yi
2021-05-11 17:38 ` Willem de Bruijn
2021-05-12 0:45 ` Dongseok Yi
[not found] ` <CGME20210511065056epcas2p1788505019deb274f5c57650a2f5d7ef0@epcas2p1.samsung.com>
2021-05-11 6:36 ` Dongseok Yi [this message]
2021-05-11 17:42 ` [PATCH bpf v2] bpf: check BPF_F_ADJ_ROOM_FIXED_GSO when upgrading mss in " Willem de Bruijn
2021-05-12 6:56 ` Dongseok Yi
[not found] ` <CGME20210512074058epcas2p35536c27bdfafaa6431e164c142007f96@epcas2p3.samsung.com>
2021-05-12 7:27 ` [PATCH bpf-next v3] bpf: check for BPF_F_ADJ_ROOM_FIXED_GSO when bpf_skb_change_proto Dongseok Yi
2021-05-12 14:13 ` Willem de Bruijn
2021-05-18 20:10 ` patchwork-bot+netdevbpf
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