netdev - [PATCH bpf-next] bpf: fix issue that packet only contains l2 is dropped

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Message-ID: <20221015092448.117563-1-shaozhengchao@huawei.com>
Date:   Sat, 15 Oct 2022 17:24:48 +0800
From:   Zhengchao Shao <shaozhengchao@...wei.com>
To:     <bpf@...r.kernel.org>, <netdev@...r.kernel.org>,
        <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
        <pabeni@...hat.com>
CC:     <ast@...nel.org>, <daniel@...earbox.net>, <andrii@...nel.org>,
        <martin.lau@...ux.dev>, <song@...nel.org>, <yhs@...com>,
        <john.fastabend@...il.com>, <kpsingh@...nel.org>, <sdf@...gle.com>,
        <haoluo@...gle.com>, <jolsa@...nel.org>, <oss@....io>,
        <weiyongjun1@...wei.com>, <yuehaibing@...wei.com>,
        <shaozhengchao@...wei.com>
Subject: [PATCH bpf-next] bpf: fix issue that packet only contains l2 is dropped

As [0] see, bpf_prog_test_run_skb() should allow user space to forward
14-bytes packet via BPF_PROG_RUN instead of dropping packet directly.
So fix it.

0: https://github.com/cilium/ebpf/commit/a38fb6b5a46ab3b5639ea4d421232a10013596c0

Fixes: fd1894224407 ("bpf: Don't redirect packets with invalid pkt_len")
Signed-off-by: Zhengchao Shao <shaozhengchao@...wei.com>
---
 net/bpf/test_run.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index 13d578ce2a09..aa1b49f19ca3 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -979,9 +979,6 @@ static int convert___skb_to_skb(struct sk_buff *skb, struct __sk_buff *__skb)
 {
 	struct qdisc_skb_cb *cb = (struct qdisc_skb_cb *)skb->cb;
 
-	if (!skb->len)
-		return -EINVAL;
-
 	if (!__skb)
 		return 0;
 
@@ -1102,6 +1099,9 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
 	if (IS_ERR(data))
 		return PTR_ERR(data);
 
+	if (size == ETH_HLEN)
+		is_l2 = true;
+
 	ctx = bpf_ctx_init(kattr, sizeof(struct __sk_buff));
 	if (IS_ERR(ctx)) {
 		kfree(data);
-- 
2.17.1