Author | Tokens | Token Proportion | Commits | Commit Proportion |
---|---|---|---|---|
Daniel Xu | 405 | 100.00% | 2 | 100.00% |
Total | 405 | 2 |
// SPDX-License-Identifier: GPL-2.0-only #include "vmlinux.h" #include <bpf/bpf_helpers.h> #include <bpf/bpf_endian.h> #include "bpf_tracing_net.h" #define NF_DROP 0 #define NF_ACCEPT 1 #define ETH_P_IP 0x0800 #define ETH_P_IPV6 0x86DD #define IP_MF 0x2000 #define IP_OFFSET 0x1FFF #define NEXTHDR_FRAGMENT 44 extern int bpf_dynptr_from_skb(struct __sk_buff *skb, __u64 flags, struct bpf_dynptr *ptr__uninit) __ksym; extern void *bpf_dynptr_slice(const struct bpf_dynptr *ptr, uint32_t offset, void *buffer, uint32_t buffer__sz) __ksym; volatile int shootdowns = 0; static bool is_frag_v4(struct iphdr *iph) { int offset; int flags; offset = bpf_ntohs(iph->frag_off); flags = offset & ~IP_OFFSET; offset &= IP_OFFSET; offset <<= 3; return (flags & IP_MF) || offset; } static bool is_frag_v6(struct ipv6hdr *ip6h) { /* Simplifying assumption that there are no extension headers * between fixed header and fragmentation header. This assumption * is only valid in this test case. It saves us the hassle of * searching all potential extension headers. */ return ip6h->nexthdr == NEXTHDR_FRAGMENT; } static int handle_v4(struct __sk_buff *skb) { struct bpf_dynptr ptr; u8 iph_buf[20] = {}; struct iphdr *iph; if (bpf_dynptr_from_skb(skb, 0, &ptr)) return NF_DROP; iph = bpf_dynptr_slice(&ptr, 0, iph_buf, sizeof(iph_buf)); if (!iph) return NF_DROP; /* Shootdown any frags */ if (is_frag_v4(iph)) { shootdowns++; return NF_DROP; } return NF_ACCEPT; } static int handle_v6(struct __sk_buff *skb) { struct bpf_dynptr ptr; struct ipv6hdr *ip6h; u8 ip6h_buf[40] = {}; if (bpf_dynptr_from_skb(skb, 0, &ptr)) return NF_DROP; ip6h = bpf_dynptr_slice(&ptr, 0, ip6h_buf, sizeof(ip6h_buf)); if (!ip6h) return NF_DROP; /* Shootdown any frags */ if (is_frag_v6(ip6h)) { shootdowns++; return NF_DROP; } return NF_ACCEPT; } SEC("netfilter") int defrag(struct bpf_nf_ctx *ctx) { struct __sk_buff *skb = (struct __sk_buff *)ctx->skb; switch (bpf_ntohs(ctx->skb->protocol)) { case ETH_P_IP: return handle_v4(skb); case ETH_P_IPV6: return handle_v6(skb); default: return NF_ACCEPT; } } char _license[] SEC("license") = "GPL";
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