#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
+
#ifdef TEST
// 64 bit version of xdp_md for testing
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 DO_RETURN(reason, ret) { \
+ if (ret == XDP_DROP) drop_cnt_map[reason] += 1; \
+ return ret; \
+ }
+
#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 DO_RETURN(reason, ret) {\
+ if (ret == XDP_DROP) { \
+ long *value = bpf_map_lookup_elem(&drop_cnt_map, &reason); \
+ if (value) \
+ *value += 1; \
+ } \
+ return XDP_DROP; \
+ }
+
SEC("xdp_drop")
#endif
+
+// 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);
+
int xdp_drop_prog(struct xdp_md *ctx)
{
const void *const data_end = (void *)(size_t)ctx->data_end;
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;
-#ifdef PARSE_8021Q
+#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))) {
+ 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 (unlikely(pktdata + sizeof(struct iphdr) > data_end))
- return XDP_DROP;
- ip = (struct iphdr*) pktdata;
+ CHECK_LEN(pktdata, iphdr);
+ const struct iphdr *ip = (struct iphdr*) pktdata;
-#ifdef PARSE_IHL
- if (unlikely(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 (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;
+ }
}
- } else if (eth_proto == BE16(ETH_P_IPV6)) {
- if (unlikely(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);
+ const 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 (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 {
- 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 (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;
+#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;
}
projects / flowspec-xdp / blobdiff