6fd5fb6382
Add a test case for using bpf_skb_change_head() in combination with bpf_redirect_peer() to redirect a packet from a L3 device to veth and back. The test uses a BPF program that adds L2 headers to the packet coming from a L3 device and then calls bpf_redirect_peer() to redirect the packet to a veth device. The test fails as skb->mac_len is not set properly and thus the ethernet headers are not properly skb_pull'd in cls_bpf_classify(), causing tcp_v4_rcv() to point the TCP header into middle of the IP header. Signed-off-by: Jussi Maki <joamaki@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20210525102955.2811090-1-joamaki@gmail.com
63 lines
1.4 KiB
C
63 lines
1.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <stdint.h>
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#include <stdbool.h>
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#include <linux/bpf.h>
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#include <linux/stddef.h>
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#include <linux/pkt_cls.h>
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#include <linux/if_ether.h>
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#include <linux/ip.h>
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#include <bpf/bpf_helpers.h>
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volatile const __u32 IFINDEX_SRC;
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volatile const __u32 IFINDEX_DST;
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static const __u8 src_mac[] = {0x00, 0x11, 0x22, 0x33, 0x44, 0x55};
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static const __u8 dst_mac[] = {0x00, 0x22, 0x33, 0x44, 0x55, 0x66};
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SEC("classifier/chk_egress")
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int tc_chk(struct __sk_buff *skb)
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{
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return TC_ACT_SHOT;
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}
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SEC("classifier/dst_ingress")
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int tc_dst(struct __sk_buff *skb)
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{
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return bpf_redirect_peer(IFINDEX_SRC, 0);
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}
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SEC("classifier/src_ingress")
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int tc_src(struct __sk_buff *skb)
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{
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return bpf_redirect_peer(IFINDEX_DST, 0);
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}
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SEC("classifier/dst_ingress_l3")
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int tc_dst_l3(struct __sk_buff *skb)
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{
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return bpf_redirect(IFINDEX_SRC, 0);
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}
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SEC("classifier/src_ingress_l3")
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int tc_src_l3(struct __sk_buff *skb)
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{
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__u16 proto = skb->protocol;
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if (bpf_skb_change_head(skb, ETH_HLEN, 0) != 0)
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return TC_ACT_SHOT;
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if (bpf_skb_store_bytes(skb, 0, &src_mac, ETH_ALEN, 0) != 0)
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return TC_ACT_SHOT;
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if (bpf_skb_store_bytes(skb, ETH_ALEN, &dst_mac, ETH_ALEN, 0) != 0)
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return TC_ACT_SHOT;
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if (bpf_skb_store_bytes(skb, ETH_ALEN + ETH_ALEN, &proto, sizeof(__u16), 0) != 0)
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return TC_ACT_SHOT;
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return bpf_redirect_peer(IFINDEX_DST, 0);
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}
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char __license[] SEC("license") = "GPL";
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