netdev - [PATCH bpf-next v5 1/2] bpf: setup socket family and addresses in bpf_prog_test_run

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Message-Id: <20200802213631.78937-2-zeil@yandex-team.ru>
Date:   Mon,  3 Aug 2020 00:36:30 +0300
From:   Dmitry Yakunin <zeil@...dex-team.ru>
To:     alexei.starovoitov@...il.com, daniel@...earbox.net,
        netdev@...r.kernel.org, bpf@...r.kernel.org
Cc:     sdf@...gle.com
Subject: [PATCH bpf-next v5 1/2] bpf: setup socket family and addresses in bpf_prog_test_run_skb

Now it's impossible to test all branches of cgroup_skb bpf program which
accesses skb->family and skb->{local,remote}_ip{4,6} fields because they
are zeroed during socket allocation. This commit fills socket family and
addresses from related fields in constructed skb.

v2:
  - fix build without CONFIG_IPV6 (kernel test robot <lkp@...el.com>)

v3:
  - check skb length before access to inet headers (Eric Dumazet)

Signed-off-by: Dmitry Yakunin <zeil@...dex-team.ru>
---
 net/bpf/test_run.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index b03c469..8d69295 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -449,6 +449,27 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
 	skb->protocol = eth_type_trans(skb, current->nsproxy->net_ns->loopback_dev);
 	skb_reset_network_header(skb);
 
+	switch (skb->protocol) {
+	case htons(ETH_P_IP):
+		sk->sk_family = AF_INET;
+		if (pskb_may_pull(skb, sizeof(struct iphdr))) {
+			sk->sk_rcv_saddr = ip_hdr(skb)->saddr;
+			sk->sk_daddr = ip_hdr(skb)->daddr;
+		}
+		break;
+#if IS_ENABLED(CONFIG_IPV6)
+	case htons(ETH_P_IPV6):
+		sk->sk_family = AF_INET6;
+		if (pskb_may_pull(skb, sizeof(struct ipv6hdr))) {
+			sk->sk_v6_rcv_saddr = ipv6_hdr(skb)->saddr;
+			sk->sk_v6_daddr = ipv6_hdr(skb)->daddr;
+		}
+		break;
+#endif
+	default:
+		break;
+	}
+
 	if (is_l2)
 		__skb_push(skb, hh_len);
 	if (is_direct_pkt_access)
-- 
2.7.4