netdev - [PATCH bpf-next v2 1/2] bpf: expose __sk_buff wire_len/gso_segs to BPF_PROG_TEST

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Date:   Fri, 13 Dec 2019 14:30:27 -0800
From:   Stanislav Fomichev <sdf@...gle.com>
To:     netdev@...r.kernel.org, bpf@...r.kernel.org
Cc:     davem@...emloft.net, ast@...nel.org, daniel@...earbox.net,
        Stanislav Fomichev <sdf@...gle.com>,
        Martin KaFai Lau <kafai@...com>
Subject: [PATCH bpf-next v2 1/2] bpf: expose __sk_buff wire_len/gso_segs to BPF_PROG_TEST_RUN

wire_len should not be less than real len and is capped by GSO_MAX_SIZE.
gso_segs is capped by GSO_MAX_SEGS.

v2:
* set wire_len to skb->len when passed wire_len is 0 (Alexei Starovoitov)

Cc: Martin KaFai Lau <kafai@...com>
Signed-off-by: Stanislav Fomichev <sdf@...gle.com>
---
 net/bpf/test_run.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index 85c8cbbada92..f23707075f26 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -263,8 +263,10 @@ static int convert___skb_to_skb(struct sk_buff *skb, struct __sk_buff *__skb)
 		return -EINVAL;
 
 	/* tstamp is allowed */
+	/* wire_len is allowed */
+	/* gso_segs is allowed */
 
-	if (!range_is_zero(__skb, offsetofend(struct __sk_buff, tstamp),
+	if (!range_is_zero(__skb, offsetofend(struct __sk_buff, gso_segs),
 			   sizeof(struct __sk_buff)))
 		return -EINVAL;
 
@@ -272,6 +274,19 @@ static int convert___skb_to_skb(struct sk_buff *skb, struct __sk_buff *__skb)
 	skb->tstamp = __skb->tstamp;
 	memcpy(&cb->data, __skb->cb, QDISC_CB_PRIV_LEN);
 
+	if (__skb->wire_len == 0) {
+		cb->pkt_len = skb->len;
+	} else {
+		if (__skb->wire_len < skb->len ||
+		    __skb->wire_len > GSO_MAX_SIZE)
+			return -EINVAL;
+		cb->pkt_len = __skb->wire_len;
+	}
+
+	if (__skb->gso_segs > GSO_MAX_SEGS)
+		return -EINVAL;
+	skb_shinfo(skb)->gso_segs = __skb->gso_segs;
+
 	return 0;
 }
 
@@ -285,6 +300,8 @@ static void convert_skb_to___skb(struct sk_buff *skb, struct __sk_buff *__skb)
 	__skb->priority = skb->priority;
 	__skb->tstamp = skb->tstamp;
 	memcpy(__skb->cb, &cb->data, QDISC_CB_PRIV_LEN);
+	__skb->wire_len = cb->pkt_len;
+	__skb->gso_segs = skb_shinfo(skb)->gso_segs;
 }
 
 int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
-- 
2.24.1.735.g03f4e72817-goog