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From: "Maciej Żenczykowski" <zenczykowski@gmail.com>
To: "Maciej Żenczykowski" <maze@google.com>,
	"Alexei Starovoitov" <ast@kernel.org>,
	"Daniel Borkmann" <daniel@iogearbox.net>
Cc: Linux Network Development Mailing List <netdev@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	BPF Mailing List <bpf@vger.kernel.org>,
	"David S . Miller" <davem@davemloft.net>,
	Dongseok Yi <dseok.yi@samsung.com>,
	Willem de Bruijn <willemb@google.com>
Subject: [PATCH bpf-next v2 3/4] bpf: support all gso types in bpf_skb_change_proto()
Date: Wed, 16 Jun 2021 17:09:52 -0700	[thread overview]
Message-ID: <20210617000953.2787453-3-zenczykowski@gmail.com> (raw)
In-Reply-To: <20210617000953.2787453-1-zenczykowski@gmail.com>

From: Maciej Żenczykowski <maze@google.com>

Since we no longer modify gso_size, it is now theoretically
safe to not set SKB_GSO_DODGY and reset gso_segs to zero.

This also means the skb_is_gso_tcp() check should no
longer be necessary.

Unfortunately we cannot remove the skb_{decrease,increase}_gso_size()
helpers, as they are still used elsewhere:
  bpf_skb_net_grow() without BPF_F_ADJ_ROOM_FIXED_GSO
  bpf_skb_net_shrink() without BPF_F_ADJ_ROOM_FIXED_GSO
and
  net/core/lwt_bpf.c's handle_gso_type()

Cc: Dongseok Yi <dseok.yi@samsung.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: Maciej Żenczykowski <maze@google.com>
---
 net/core/filter.c | 22 ++--------------------
 1 file changed, 2 insertions(+), 20 deletions(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index 6541358a770b..8f05498f497e 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3241,9 +3241,6 @@ static int bpf_skb_proto_4_to_6(struct sk_buff *skb)
 	u32 off = skb_mac_header_len(skb);
 	int ret;
 
-	if (skb_is_gso(skb) && !skb_is_gso_tcp(skb))
-		return -ENOTSUPP;
-
 	ret = skb_cow(skb, len_diff);
 	if (unlikely(ret < 0))
 		return ret;
@@ -3255,17 +3252,11 @@ static int bpf_skb_proto_4_to_6(struct sk_buff *skb)
 	if (skb_is_gso(skb)) {
 		struct skb_shared_info *shinfo = skb_shinfo(skb);
 
-		/* SKB_GSO_TCPV4 needs to be changed into
-		 * SKB_GSO_TCPV6.
-		 */
+		/* SKB_GSO_TCPV4 needs to be changed into SKB_GSO_TCPV6. */
 		if (shinfo->gso_type & SKB_GSO_TCPV4) {
 			shinfo->gso_type &= ~SKB_GSO_TCPV4;
 			shinfo->gso_type |=  SKB_GSO_TCPV6;
 		}
-
-		/* Header must be checked, and gso_segs recomputed. */
-		shinfo->gso_type |= SKB_GSO_DODGY;
-		shinfo->gso_segs = 0;
 	}
 
 	skb->protocol = htons(ETH_P_IPV6);
@@ -3280,9 +3271,6 @@ static int bpf_skb_proto_6_to_4(struct sk_buff *skb)
 	u32 off = skb_mac_header_len(skb);
 	int ret;
 
-	if (skb_is_gso(skb) && !skb_is_gso_tcp(skb))
-		return -ENOTSUPP;
-
 	ret = skb_unclone(skb, GFP_ATOMIC);
 	if (unlikely(ret < 0))
 		return ret;
@@ -3294,17 +3282,11 @@ static int bpf_skb_proto_6_to_4(struct sk_buff *skb)
 	if (skb_is_gso(skb)) {
 		struct skb_shared_info *shinfo = skb_shinfo(skb);
 
-		/* SKB_GSO_TCPV6 needs to be changed into
-		 * SKB_GSO_TCPV4.
-		 */
+		/* SKB_GSO_TCPV6 needs to be changed into SKB_GSO_TCPV4. */
 		if (shinfo->gso_type & SKB_GSO_TCPV6) {
 			shinfo->gso_type &= ~SKB_GSO_TCPV6;
 			shinfo->gso_type |=  SKB_GSO_TCPV4;
 		}
-
-		/* Header must be checked, and gso_segs recomputed. */
-		shinfo->gso_type |= SKB_GSO_DODGY;
-		shinfo->gso_segs = 0;
 	}
 
 	skb->protocol = htons(ETH_P_IP);
-- 
2.32.0.272.g935e593368-goog


  parent reply	other threads:[~2021-06-17  0:10 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-04  1:52 [PATCH bpf-next 1/2] Revert "bpf: Check for BPF_F_ADJ_ROOM_FIXED_GSO when bpf_skb_change_proto" Maciej Żenczykowski
2021-06-04  1:52 ` [PATCH bpf-next 2/2] bpf: do not change gso_size during bpf_skb_change_proto() Maciej Żenczykowski
2021-06-15  7:35   ` Maciej Żenczykowski
2021-06-15 22:16     ` Daniel Borkmann
2021-06-16  0:06       ` Maciej Żenczykowski
2021-06-17  0:09         ` [PATCH bpf-next v2 1/4] Revert "bpf: Check for BPF_F_ADJ_ROOM_FIXED_GSO when bpf_skb_change_proto" Maciej Żenczykowski
2021-06-17  0:09           ` [PATCH bpf-next v2 2/4] bpf: do not change gso_size during bpf_skb_change_proto() Maciej Żenczykowski
2021-06-17  0:09           ` Maciej Żenczykowski [this message]
2021-06-17  0:09           ` [PATCH bpf-next v2 4/4] bpf: more lenient bpf_skb_net_shrink() with BPF_F_ADJ_ROOM_FIXED_GSO Maciej Żenczykowski
2021-06-24 14:05             ` Daniel Borkmann
2021-06-24 17:13               ` Maciej Żenczykowski

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