X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=xdp.c;h=8003b89e0066b4311fd8eb482a922718914166e4;hb=ce7cb6545f4fd8872f08263733cb2188530e9420;hp=10ed78b2a22411988661a367de4a87fc73817bef;hpb=bcf836638563135278efe7d0476ece5772ff465a;p=flowspec-xdp diff --git a/xdp.c b/xdp.c index 10ed78b..8003b89 100644 --- a/xdp.c +++ b/xdp.c @@ -96,6 +96,7 @@ struct tcphdr { #elif defined(__BIG_ENDIAN) #define BIGEND128(a, b, c, d) ((((uint128_t)a) << 3*32) | (((uint128_t)b) << 2*32) | (((uint128_t)c) << 1*32) | (((uint128_t)d) << 0*32)) #define HTON128(a) (a) +#define BE16(a) ((uint16_t)a) #else #error "Need endian info" #endif @@ -111,6 +112,22 @@ struct tcphdr { #define unlikely(a) __builtin_expect(a, 0) #define likely(a) __builtin_expect(a, 1) +static const uint32_t PKT_LEN_DROP = 0; +static const uint32_t VLAN_DROP = 1; +static const uint32_t IHL_DROP = 2; +static const uint32_t V6FRAG_DROP = 3; +#define STATIC_RULE_CNT 4 + +#define DO_RETURN(reason, ret) {\ + if (ret == XDP_DROP) { INCREMENT_MATCH(reason); } \ + return ret; \ + } + +// It seems (based on drop counts) that data_end points to the last byte, not one-past-the-end. +// This feels strange, but some documentation suggests > here as well, so we stick with that. +#define CHECK_LEN(start, struc) \ + if (unlikely((void*)(start) + sizeof(struct struc) > data_end)) DO_RETURN(PKT_LEN_DROP, XDP_DROP); + #ifdef TEST // 64 bit version of xdp_md for testing struct xdp_md { @@ -125,10 +142,40 @@ struct xdp_md { }; static const int XDP_PASS = 0; static const int XDP_DROP = 1; + +static long drop_cnt_map[RULECNT + STATIC_RULE_CNT]; +#define INCREMENT_MATCH(reason) drop_cnt_map[reason] += 1; + #else #include #include +struct bpf_map_def SEC("maps") drop_cnt_map = { + .type = BPF_MAP_TYPE_PERCPU_ARRAY, + .key_size = sizeof(uint32_t), + .value_size = sizeof(long), + .max_entries = RULECNT + STATIC_RULE_CNT, +}; +#define INCREMENT_MATCH(reason) { \ + long *value = bpf_map_lookup_elem(&drop_cnt_map, &reason); \ + if (value) \ + *value += 1; \ +} + +#ifdef RATE_CNT +struct ratelimit { + struct bpf_spin_lock lock; + int64_t sent_bytes; + int64_t sent_time; +}; +struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __uint(max_entries, RATE_CNT); + __u32 *key; + struct ratelimit *value; +} rate_map SEC(".maps"); +#endif + SEC("xdp_drop") #endif int xdp_drop_prog(struct xdp_md *ctx) @@ -139,30 +186,28 @@ int xdp_drop_prog(struct xdp_md *ctx) unsigned short eth_proto; { - if (unlikely((void*)(size_t)ctx->data + sizeof(struct ethhdr) > data_end)) - return XDP_DROP; + CHECK_LEN((size_t)ctx->data, ethhdr); const struct ethhdr *const eth = (void*)(size_t)ctx->data; #if PARSE_8021Q == PARSE if (likely(eth->h_proto == BE16(ETH_P_8021Q))) { - if (unlikely((void*)(size_t)ctx->data + sizeof(struct ethhdr_vlan) > data_end)) - return XDP_DROP; + CHECK_LEN((size_t)ctx->data, ethhdr_vlan); const struct ethhdr_vlan *const eth_vlan = (void*)(size_t)ctx->data; #ifdef REQ_8021Q if (unlikely((eth_vlan->tci & BE16(0xfff)) != BE16(REQ_8021Q))) - return XDP_DROP; + DO_RETURN(VLAN_DROP, XDP_DROP); #endif eth_proto = eth_vlan->h_proto; pktdata = (const void *)(long)ctx->data + sizeof(struct ethhdr_vlan); #else if (unlikely(eth->h_proto == BE16(ETH_P_8021Q))) { - return PARSE_8021Q; + DO_RETURN(VLAN_DROP, PARSE_8021Q); #endif } else { #ifdef REQ_8021Q - return XDP_DROP; + DO_RETURN(VLAN_DROP, XDP_DROP); #else pktdata = (const void *)(long)ctx->data + sizeof(struct ethhdr); eth_proto = eth->h_proto; @@ -170,100 +215,94 @@ int xdp_drop_prog(struct xdp_md *ctx) } } -#ifdef NEED_V4_PARSE - const struct iphdr *ip = NULL; - const struct icmphdr *icmp = NULL; -#endif -#ifdef NEED_V6_PARSE - const struct ip6hdr *ip6 = NULL; - const struct icmp6hdr *icmpv6 = NULL; - const struct ip6_fraghdr *frag6 = NULL; -#endif - const void *l4hdr = NULL; const struct tcphdr *tcp = NULL; - const struct udphdr *udp = NULL; + uint8_t ports_valid = 0; + uint16_t sport, dport; // Host Endian! Only valid with tcp || udp #ifdef NEED_V4_PARSE if (eth_proto == BE16(ETH_P_IP)) { - if (unlikely(pktdata + sizeof(struct iphdr) > data_end)) - return XDP_DROP; - ip = (struct iphdr*) pktdata; + CHECK_LEN(pktdata, iphdr); + struct iphdr *ip = (struct iphdr*) pktdata; #if PARSE_IHL == PARSE - if (unlikely(ip->ihl < 5)) return XDP_DROP; + if (unlikely(ip->ihl < 5)) DO_RETURN(IHL_DROP, XDP_DROP); l4hdr = pktdata + ip->ihl * 4; #else - if (ip->ihl != 5) return PARSE_IHL; + if (ip->ihl != 5) DO_RETURN(IHL_DROP, PARSE_IHL); l4hdr = pktdata + 5*4; #endif - if (ip->protocol == IP_PROTO_TCP) { - if (unlikely(l4hdr + sizeof(struct tcphdr) > data_end)) - return XDP_DROP; - tcp = (struct tcphdr*) l4hdr; - } else if (ip->protocol == IP_PROTO_UDP) { - if (unlikely(l4hdr + sizeof(struct udphdr) > data_end)) - return XDP_DROP; - udp = (struct udphdr*) l4hdr; - } else if (ip->protocol == IP_PROTO_ICMP) { - if (unlikely(l4hdr + sizeof(struct icmphdr) > data_end)) - return XDP_DROP; - icmp = (struct icmphdr*) l4hdr; + const struct icmphdr *icmp = NULL; + if ((ip->frag_off & BE16(IP_OFFSET)) == 0) { + if (ip->protocol == IP_PROTO_TCP) { + CHECK_LEN(l4hdr, tcphdr); + tcp = (struct tcphdr*) l4hdr; + sport = BE16(tcp->source); + dport = BE16(tcp->dest); + ports_valid = 1; + } else if (ip->protocol == IP_PROTO_UDP) { + CHECK_LEN(l4hdr, udphdr); + const struct udphdr *udp = (struct udphdr*) l4hdr; + sport = BE16(udp->source); + dport = BE16(udp->dest); + ports_valid = 1; + } else if (ip->protocol == IP_PROTO_ICMP) { + CHECK_LEN(l4hdr, icmphdr); + icmp = (struct icmphdr*) l4hdr; + } } + + RULES4 } #endif #ifdef NEED_V6_PARSE if (eth_proto == BE16(ETH_P_IPV6)) { - if (unlikely(pktdata + sizeof(struct ip6hdr) > data_end)) - return XDP_DROP; - ip6 = (struct ip6hdr*) pktdata; + CHECK_LEN(pktdata, ip6hdr); + struct ip6hdr *ip6 = (struct ip6hdr*) pktdata; l4hdr = pktdata + 40; uint8_t v6nexthdr = ip6->nexthdr; + const struct ip6_fraghdr *frag6 = NULL; #ifdef PARSE_V6_FRAG #if PARSE_V6_FRAG == PARSE if (ip6->nexthdr == IP6_PROTO_FRAG) { - if (unlikely(l4hdr + sizeof(struct ip6_fraghdr) > data_end)) - return XDP_DROP; + CHECK_LEN(l4hdr, ip6_fraghdr); frag6 = (struct ip6_fraghdr*) l4hdr; l4hdr = l4hdr + sizeof(struct ip6_fraghdr); v6nexthdr = frag6->nexthdr; #else if (unlikely(ip6->nexthdr == IP6_PROTO_FRAG)) { - return PARSE_V6_FRAG; + DO_RETURN(V6FRAG_DROP, PARSE_V6_FRAG); #endif } #endif - - if (v6nexthdr == IP_PROTO_TCP) { - if (unlikely(l4hdr + sizeof(struct tcphdr) > data_end)) - return XDP_DROP; - tcp = (struct tcphdr*) l4hdr; - } else if (v6nexthdr == IP_PROTO_UDP) { - if (unlikely(l4hdr + sizeof(struct udphdr) > data_end)) - return XDP_DROP; - udp = (struct udphdr*) l4hdr; - } else if (v6nexthdr == IP6_PROTO_ICMPV6) { - if (unlikely(l4hdr + sizeof(struct icmp6hdr) > data_end)) - return XDP_DROP; - icmpv6 = (struct icmp6hdr*) l4hdr; + // TODO: Handle more options? + + const struct icmp6hdr *icmpv6 = NULL; + if (frag6 == NULL || (frag6->frag_off & BE16(IP6_FRAGOFF)) == 0) { + if (v6nexthdr == IP_PROTO_TCP) { + CHECK_LEN(l4hdr, tcphdr); + tcp = (struct tcphdr*) l4hdr; + sport = BE16(tcp->source); + dport = BE16(tcp->dest); + ports_valid = 1; + } else if (v6nexthdr == IP_PROTO_UDP) { + CHECK_LEN(l4hdr, udphdr); + const struct udphdr *udp = (struct udphdr*) l4hdr; + sport = BE16(udp->source); + dport = BE16(udp->dest); + ports_valid = 1; + } else if (v6nexthdr == IP6_PROTO_ICMPV6) { + CHECK_LEN(l4hdr, icmp6hdr); + icmpv6 = (struct icmp6hdr*) l4hdr; + } } - // TODO: Handle some options? - } -#endif - uint16_t sport, dport; // Host Endian! Only valid with tcp || udp - if (tcp != NULL) { - sport = BE16(tcp->source); - dport = BE16(tcp->dest); - } else if (udp != NULL) { - sport = BE16(udp->source); - dport = BE16(udp->dest); + RULES6 } - - RULES +#endif return XDP_PASS; } @@ -272,7 +311,7 @@ int xdp_drop_prog(struct xdp_md *ctx) #include #include -const char d[] = TEST; +char d[] = TEST; int main() { struct xdp_md test = { .data = (uint64_t)d,