// SPDX-License-Identifier: GPL-2.0 /* Copyright (c) 2024 ByteDance */ #include "vmlinux.h" #include <bpf/bpf_helpers.h> #ifndef PAGE_SIZE #define PAGE_SIZE __PAGE_SIZE #endif #define BPF_SKB_MAX_LEN (PAGE_SIZE << 2) struct { __uint(type, BPF_MAP_TYPE_SOCKMAP); __uint(max_entries, 1); __type(key, int); __type(value, int); } sock_map_rx SEC(".maps"); long change_tail_ret = 1; SEC("sk_skb") int prog_skb_verdict(struct __sk_buff *skb) { char *data, *data_end; bpf_skb_pull_data(skb, 1); data = (char *)(unsigned long)skb->data; data_end = (char *)(unsigned long)skb->data_end; if (data + 1 > data_end) return SK_PASS; if (data[0] == 'T') { /* Trim the packet */ change_tail_ret = bpf_skb_change_tail(skb, skb->len - 1, 0); return SK_PASS; } else if (data[0] == 'G') { /* Grow the packet */ change_tail_ret = bpf_skb_change_tail(skb, skb->len + 1, 0); return SK_PASS; } else if (data[0] == 'E') { /* Error */ change_tail_ret = bpf_skb_change_tail(skb, BPF_SKB_MAX_LEN, 0); return SK_PASS; } return SK_PASS; } char _license[] SEC("license") = "GPL";