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From: Jesper Dangaard Brouer <brouer@redhat.com>
To: bpf@vger.kernel.org
Cc: Jesper Dangaard Brouer <brouer@redhat.com>,
	netdev@vger.kernel.org, Daniel Borkmann <borkmann@iogearbox.net>,
	Alexei Starovoitov <alexei.starovoitov@gmail.com>,
	maze@google.com, lmb@cloudflare.com, shaun@tigera.io,
	Lorenzo Bianconi <lorenzo@kernel.org>,
	marek@cloudflare.com, John Fastabend <john.fastabend@gmail.com>,
	Jakub Kicinski <kuba@kernel.org>,
	eyal.birger@gmail.com, colrack@gmail.com
Subject: [PATCH bpf-next V11 6/7] selftests/bpf: use bpf_check_mtu in selftest test_cls_redirect
Date: Tue, 12 Jan 2021 18:45:31 +0100
Message-ID: <161047353102.4003084.16408050677931166544.stgit@firesoul> (raw)
In-Reply-To: <161047346644.4003084.2653117664787086168.stgit@firesoul>

This demonstrate how bpf_check_mtu() helper can easily be used together
with bpf_skb_adjust_room() helper, prior to doing size adjustment, as
delta argument is already setup.

Hint: This specific test can be selected like this:
 ./test_progs -t cls_redirect

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
---
 .../selftests/bpf/progs/test_cls_redirect.c        |    7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tools/testing/selftests/bpf/progs/test_cls_redirect.c b/tools/testing/selftests/bpf/progs/test_cls_redirect.c
index c9f8464996ea..3c1e042962e6 100644
--- a/tools/testing/selftests/bpf/progs/test_cls_redirect.c
+++ b/tools/testing/selftests/bpf/progs/test_cls_redirect.c
@@ -70,6 +70,7 @@ typedef struct {
 	uint64_t errors_total_encap_adjust_failed;
 	uint64_t errors_total_encap_buffer_too_small;
 	uint64_t errors_total_redirect_loop;
+	uint64_t errors_total_encap_mtu_violate;
 } metrics_t;
 
 typedef enum {
@@ -407,6 +408,7 @@ static INLINING ret_t forward_with_gre(struct __sk_buff *skb, encap_headers_t *e
 		payload_off - sizeof(struct ethhdr) - sizeof(struct iphdr);
 	int32_t delta = sizeof(struct gre_base_hdr) - encap_overhead;
 	uint16_t proto = ETH_P_IP;
+	uint32_t mtu_len = 0;
 
 	/* Loop protection: the inner packet's TTL is decremented as a safeguard
 	 * against any forwarding loop. As the only interesting field is the TTL
@@ -479,6 +481,11 @@ static INLINING ret_t forward_with_gre(struct __sk_buff *skb, encap_headers_t *e
 		}
 	}
 
+	if (bpf_check_mtu(skb, skb->ifindex, &mtu_len, delta, 0)) {
+		metrics->errors_total_encap_mtu_violate++;
+		return TC_ACT_SHOT;
+	}
+
 	if (bpf_skb_adjust_room(skb, delta, BPF_ADJ_ROOM_NET,
 				BPF_F_ADJ_ROOM_FIXED_GSO |
 				BPF_F_ADJ_ROOM_NO_CSUM_RESET) ||



  parent reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-12 17:45 [PATCH bpf-next V11 0/7] bpf: New approach for BPF MTU handling Jesper Dangaard Brouer
2021-01-12 17:45 ` [PATCH bpf-next V11 1/7] bpf: Remove MTU check in __bpf_skb_max_len Jesper Dangaard Brouer
2021-01-14  8:18   ` John Fastabend
2021-01-12 17:45 ` [PATCH bpf-next V11 2/7] bpf: fix bpf_fib_lookup helper MTU check for SKB ctx Jesper Dangaard Brouer
2021-01-12 17:45 ` [PATCH bpf-next V11 3/7] bpf: bpf_fib_lookup return MTU value as output when looked up Jesper Dangaard Brouer
2021-01-12 17:45 ` [PATCH bpf-next V11 4/7] bpf: add BPF-helper for MTU checking Jesper Dangaard Brouer
2021-01-12 19:23   ` Andrii Nakryiko
2021-01-14 14:52     ` Jesper Dangaard Brouer
2021-01-14 15:33       ` Yonghong Song
2021-01-13 23:07   ` Daniel Borkmann
2021-01-14 14:36     ` Jesper Dangaard Brouer
2021-01-14 22:28       ` Daniel Borkmann
2021-01-18 11:04         ` Jesper Dangaard Brouer
2021-01-12 17:45 ` [PATCH bpf-next V11 5/7] bpf: drop MTU check when doing TC-BPF redirect to ingress Jesper Dangaard Brouer
2021-01-14  9:03   ` John Fastabend
2021-01-14 16:14     ` Jesper Dangaard Brouer
2021-01-12 17:45 ` Jesper Dangaard Brouer [this message]
2021-01-12 17:45 ` [PATCH bpf-next V11 7/7] bpf/selftests: tests using bpf_check_mtu BPF-helper Jesper Dangaard Brouer
2021-01-12 19:29   ` Andrii Nakryiko

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