From: Jesper Dangaard Brouer Date: Tue, 9 Feb 2021 13:38:34 +0000 (+0100) Subject: selftests/bpf: Use bpf_check_mtu in selftest test_cls_redirect X-Git-Tag: v5.15.73~12633^2~28^2~3 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=6b8838be7e21edb620099e01eb040c21c5190494;p=platform%2Fkernel%2Flinux-rpi.git selftests/bpf: Use bpf_check_mtu in selftest test_cls_redirect 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 Signed-off-by: Daniel Borkmann Acked-by: John Fastabend Link: https://lore.kernel.org/bpf/161287791481.790810.4444271170546646080.stgit@firesoul --- 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) ||