X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=xdp.c;h=8003b89e0066b4311fd8eb482a922718914166e4;hb=ce7cb6545f4fd8872f08263733cb2188530e9420;hp=8623af44c1f0cdbb6b0591e7d4c6db148cf05739;hpb=94ae7afe2f87074c7353e247275fe33f7f774bd1;p=flowspec-xdp

diff --git a/xdp.c b/xdp.c
index 8623af4..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
@@ -104,10 +105,29 @@ struct tcphdr {
 #define MASK6(pfxlen) HTON128(~((((uint128_t)1) << (128 - pfxlen)) - 1))
 #define MASK6_OFFS(offs, pfxlen) HTON128((~((((uint128_t)1) << (128 - pfxlen)) - 1)) & ((((uint128_t)1) << (128 - offs)) - 1))
 
-// Note rules.h may also define PARSE_8021Q and REQ_8021Q
-// Note rules.h may also define PARSE_IHL
+// PARSE is used as a preprocessor flag to indicate parsing fields
+#define PARSE 42
 #include "rules.h"
 
+#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 {
@@ -122,10 +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 <linux/bpf.h>
 #include <bpf/bpf_helpers.h>
 
+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)
@@ -136,116 +186,123 @@ int xdp_drop_prog(struct xdp_md *ctx)
 	unsigned short eth_proto;
 
 	{
-		if ((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;
 
-#ifdef PARSE_8021Q
-		if (eth->h_proto == BE16(ETH_P_8021Q)) {
-			if ((void*)(size_t)ctx->data + sizeof(struct ethhdr_vlan) > data_end)
-				return XDP_DROP;
+#if PARSE_8021Q == PARSE
+		if (likely(eth->h_proto == BE16(ETH_P_8021Q))) {
+			CHECK_LEN((size_t)ctx->data, ethhdr_vlan);
 			const struct ethhdr_vlan *const eth_vlan = (void*)(size_t)ctx->data;
 
 #ifdef REQ_8021Q
-			if ((eth_vlan->tci & BE16(0xfff)) != BE16(REQ_8021Q))
-				return XDP_DROP;
+			if (unlikely((eth_vlan->tci & BE16(0xfff)) != BE16(REQ_8021Q)))
+				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))) {
+			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;
 #endif
 		}
-#else
-		pktdata = (const void *)(long)ctx->data + sizeof(struct ethhdr);
-		eth_proto = eth->h_proto;
-#endif
 	}
 
-	const struct tcphdr *tcp = NULL;
-	const struct udphdr *udp = NULL;
-	const struct icmphdr *icmp = NULL;
-	const struct icmp6hdr *icmpv6 = NULL;
-	const struct ip6_fraghdr *frag6 = NULL;
-	const struct iphdr *ip = NULL;
-	const struct ip6hdr *ip6 = NULL;
 	const void *l4hdr = NULL;
+	const struct tcphdr *tcp = 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 (pktdata + sizeof(struct iphdr) > data_end)
-			return XDP_DROP;
-		ip = (struct iphdr*) pktdata;
+		CHECK_LEN(pktdata, iphdr);
+		struct iphdr *ip = (struct iphdr*) pktdata;
 
-#ifdef PARSE_IHL
-		if (ip->ihl < 5) return XDP_DROP;
+#if PARSE_IHL == PARSE
+		if (unlikely(ip->ihl < 5)) DO_RETURN(IHL_DROP, XDP_DROP);
 		l4hdr = pktdata + ip->ihl * 4;
 #else
-		if (ip->ihl != 5) return XDP_DROP;
+		if (ip->ihl != 5) DO_RETURN(IHL_DROP, PARSE_IHL);
 		l4hdr = pktdata + 5*4;
 #endif
-		if (ip->protocol == IP_PROTO_TCP) {
-			if (l4hdr + sizeof(struct tcphdr) > data_end)
-				return XDP_DROP;
-			tcp = (struct tcphdr*) l4hdr;
-		} else if (ip->protocol == IP_PROTO_UDP) {
-			if (l4hdr + sizeof(struct udphdr) > data_end)
-				return XDP_DROP;
-			udp = (struct udphdr*) l4hdr;
-		} else if (ip->protocol == IP_PROTO_ICMP) {
-			if (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;
+			}
 		}
-	} else if (eth_proto == BE16(ETH_P_IPV6)) {
-		if (pktdata + sizeof(struct ip6hdr) > data_end)
-			return XDP_DROP;
-		ip6 = (struct ip6hdr*) pktdata;
+
+		RULES4
+	}
+#endif
+#ifdef NEED_V6_PARSE
+	if (eth_proto == BE16(ETH_P_IPV6)) {
+		CHECK_LEN(pktdata, ip6hdr);
+		struct ip6hdr *ip6 = (struct ip6hdr*) pktdata;
 
 		l4hdr = pktdata + 40;
 
-		uint8_t v6nexthdr;
+		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 (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 {
-			v6nexthdr = ip6->nexthdr;
+#else
+		if (unlikely(ip6->nexthdr == IP6_PROTO_FRAG)) {
+			DO_RETURN(V6FRAG_DROP, PARSE_V6_FRAG);
+#endif
 		}
-
-		if (v6nexthdr == IP_PROTO_TCP) {
-			if (l4hdr + sizeof(struct tcphdr) > data_end)
-				return XDP_DROP;
-			tcp = (struct tcphdr*) l4hdr;
-		} else if (v6nexthdr == IP_PROTO_UDP) {
-			if (l4hdr + sizeof(struct udphdr) > data_end)
-				return XDP_DROP;
-			udp = (struct udphdr*) l4hdr;
-		} else if (v6nexthdr == IP6_PROTO_ICMPV6) {
-			if (l4hdr + sizeof(struct icmp6hdr) > data_end)
-				return XDP_DROP;
-			icmpv6 = (struct icmp6hdr*) l4hdr;
+#endif
+		// 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?
-	} else {
-		return XDP_PASS;
-	}
 
-	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;
 }
@@ -254,7 +311,7 @@ int xdp_drop_prog(struct xdp_md *ctx)
 #include <assert.h>
 #include <string.h>
 
-const char d[] = TEST;
+char d[] = TEST;
 int main() {
 	struct xdp_md test = {
 		.data = (uint64_t)d,