X-Git-Url: http://git.bitcoin.ninja/index.cgi?p=flowspec-xdp;a=blobdiff_plain;f=xdp.c;h=187c220b0261fdaad0acc5ec7d48c6d36a4b86e5;hp=3ebec88555e37bb82ac5ca6868e8ef0e0c5d20d5;hb=HEAD;hpb=348583843f9499b0f1c335edc684a077bb2c2710 diff --git a/xdp.c b/xdp.c index 3ebec88..187c220 100644 --- a/xdp.c +++ b/xdp.c @@ -7,7 +7,7 @@ #include #include -#define NULL (void*)0 +#include "siphash.h" /* IP flags. */ #define IP_CE 0x8000 /* Flag: "Congestion" */ @@ -77,9 +77,12 @@ struct tcphdr { // Note that all operations on uint128s *stay* in Network byte order! #if defined(__LITTLE_ENDIAN) -#define BIGEND32(v) ((v >> 3*8) | ((v >> 8) & 0xff00) | ((v << 8) & 0xff0000) | (v << 3*8) & 0xff000000) +#define BIGEND32(v) (((((uint32_t)(v)) >> 3*8) & 0xff) | \ + ((((uint32_t)(v)) >> 1*8) & 0xff00) | \ + ((((uint32_t)(v)) << 1*8) & 0xff0000) | \ + ((((uint32_t)(v)) << 3*8) & 0xff000000)) #elif defined(__BIG_ENDIAN) -#define BIGEND32(v) (v) +#define BIGEND32(v) ((uint32_t)(v)) #else #error "Need endian info" #endif @@ -92,11 +95,16 @@ struct tcphdr { (((uint128_t)BIGEND32(a)) << 0*32)) #define HTON128(a) BIGEND128(a >> 3*32, a >> 2*32, a >> 1*32, a>> 0*32) // Yes, somehow macro'ing this changes LLVM's view of htons... -#define BE16(a) ((((uint16_t)(a & 0xff00)) >> 8) | (((uint16_t)(a & 0xff)) << 8)) +#define BE16(a) (((((uint16_t)a) & 0xff00) >> 8) | ((((uint16_t)a) & 0xff) << 8)) +#define BE128BEHIGH64(val) ((uint64_t)((uint128_t)(val))) + #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) + +#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) ((uint128_t)(a)) +#define BE16(a) ((uint16_t)(a)) +#define BE128BEHIGH64(val) ((uint64_t)(((uint128_t)(val)) >> 64)) + #else #error "Need endian info" #endif @@ -143,27 +151,178 @@ 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; +static long drop_cnt_map[STATS_RULECNT + STATIC_RULE_CNT]; +#define INCREMENT_MATCH(reason) { drop_cnt_map[reason] += 1; drop_cnt_map[reason] += data_end - pktdata; } -#else +#else /* TEST */ #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, +struct match_counter { + uint64_t bytes; + uint64_t packets; }; +struct { + __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY); + __uint(max_entries, STATS_RULECNT + STATIC_RULE_CNT); + __u32 *key; + struct match_counter *value; +} drop_cnt_map SEC(".maps"); + #define INCREMENT_MATCH(reason) { \ - long *value = bpf_map_lookup_elem(&drop_cnt_map, &reason); \ - if (value) \ - *value += 1; \ + struct match_counter *value = bpf_map_lookup_elem(&drop_cnt_map, &reason); \ + if (value) { \ + value->bytes += data_end - pktdata; \ + value->packets += 1; \ + } \ } +// Rate limits are done in a static-sized leaky bucket with a decimal counter +// Bucket size is always exactly (1 << RATE_BUCKET_INTEGER_BITS) +#define RATE_BUCKET_DECIMAL_BITS 8 +#define RATE_BUCKET_INTEGER_BITS 4 + +#define RATE_BUCKET_BITS (RATE_BUCKET_DECIMAL_BITS + RATE_BUCKET_INTEGER_BITS) +#define RATE_TIME_MASK ((1ULL << (64 - RATE_BUCKET_BITS)) - 1) + +// Time going backwards 10ms+ or forward 32sec+ implies we should consider it +// an overflow, or at least stale enough that we should reset the entry. +#define RATE_MIN_TIME_OFFSET -10000000LL +#define RATE_MAX_TIME_OFFSET 32000000000LL + +#ifdef RATE_CNT +struct ratelimit { + struct bpf_spin_lock lock; + uint64_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 /* RATE_CNT */ + +// We implement a rather naive hashtable here instead of using a BPF map because +// (a) the BPF map hashtables are similarly naive (no rehashing, etc), +// (b) the BPF map LRU hashtables don't support locking. +// +// We first separate into a few top-level buckets with per-bucket locks, limiting +// us to 2^SRC_HASH_MAX_PARALLELISM parallel accessors. +// +// Then we build an array of MAX_ENTRIES/2**SRC_HASH_MAX_PARALLELISM_POW entries, +// which are split into buckets of size SRC_HASH_BUCKET_COUNT. An entry can appear +// in any of the SRC_HASH_BUCKET_COUNT buckets at it's hash value. +// +// Because we use buckets of size 16, see collision_prob.py, the number of +// elements we can hold with only a 1% probability of overflowing a bucket is: +// +// 128K-entry hash table (2MiB): ~33K sources +// 256K-entry hash table (4MiB): ~63K sources +// 512K-entry hash table (8MiB): ~119K sources +// 1M-entry hash table (16MiB): ~227K sources +#define SRC_HASH_MAX_PARALLELISM_POW 8 +#define SRC_HASH_MAX_PARALLELISM (1 << SRC_HASH_MAX_PARALLELISM_POW) +#define SRC_HASH_BUCKET_COUNT_POW 4 +#define SRC_HASH_BUCKET_COUNT (1 << SRC_HASH_BUCKET_COUNT_POW) + +#define DO_RATE_LIMIT(do_lock, rate, time_masked, amt_in_pkt, limit_ns_per_pkt, matchbool) do { \ +if (rate) { \ + do_lock; \ + int64_t bucket_pkts = (rate->sent_time & (~RATE_TIME_MASK)) >> (64 - RATE_BUCKET_BITS); \ + /* We mask the top 12 bits, so date overflows every 52 days, handled below */ \ + int64_t time_diff = time_masked - ((int64_t)(rate->sent_time & RATE_TIME_MASK)); \ + if (unlikely(time_diff < -1000000000 || time_diff > 16000000000)) { \ + bucket_pkts = 0; \ + } else { \ + if (unlikely(time_diff < 0)) { time_diff = 0; } \ + int64_t pkts_since_last = (time_diff << RATE_BUCKET_BITS) * ((uint64_t)amt_in_pkt) / ((uint64_t)limit_ns_per_pkt); \ + bucket_pkts -= pkts_since_last; \ + } \ + if (bucket_pkts < (((1 << RATE_BUCKET_INTEGER_BITS) - 1) << RATE_BUCKET_DECIMAL_BITS)) { \ + if (unlikely(bucket_pkts < 0)) bucket_pkts = 0; \ + rate->sent_time = time_masked | ((bucket_pkts + (1 << RATE_BUCKET_DECIMAL_BITS)) << (64 - RATE_BUCKET_BITS)); \ + matchbool = 0; \ + } else { \ + matchbool = 1; \ + } \ +} \ +} while(0); + +#define CREATE_PERSRC_LOOKUP(IPV, IP_TYPE) \ +struct persrc_rate##IPV##_entry { \ + uint64_t sent_time; \ + IP_TYPE srcip; \ +}; \ + \ +struct persrc_rate##IPV##_bucket { \ + struct bpf_spin_lock lock; \ + struct persrc_rate##IPV##_entry entries[]; \ +}; \ + \ +static int check_v##IPV##_persrc_ratelimit(IP_TYPE key, void *map, size_t map_limit, int64_t cur_time_masked, uint64_t amt, uint64_t limit_ns_per_pkt) { \ + uint64_t hash = siphash_##IP_TYPE(key); \ + \ + const uint32_t map_key = hash % SRC_HASH_MAX_PARALLELISM; \ + struct persrc_rate##IPV##_bucket *buckets = bpf_map_lookup_elem(map, &map_key); \ + if (!buckets) return 0; \ + \ + hash >>= SRC_HASH_MAX_PARALLELISM_POW; \ + map_limit >>= SRC_HASH_MAX_PARALLELISM_POW; \ + \ + struct persrc_rate##IPV##_entry *first_bucket = &buckets->entries[(hash % map_limit) & (~(SRC_HASH_BUCKET_COUNT - 1))]; \ + bpf_spin_lock(&buckets->lock); \ + \ + uint64_t min_sent_idx = 0; /* Must be uint64_t or BPF verifier gets lost and thinks it can be any value */ \ + uint64_t min_sent_time = UINT64_MAX; \ + for (uint64_t i = 0; i < SRC_HASH_BUCKET_COUNT; i++) { \ + if (first_bucket[i].srcip == key) { \ + min_sent_idx = i; \ + break; \ + } \ + int64_t time_offset = ((int64_t)cur_time_masked) - (first_bucket[i].sent_time & RATE_TIME_MASK); \ + if (time_offset < RATE_MIN_TIME_OFFSET || time_offset > RATE_MAX_TIME_OFFSET) { \ + min_sent_idx = i; \ + break; \ + } \ + if ((first_bucket[i].sent_time & RATE_TIME_MASK) < min_sent_time) { \ + min_sent_time = first_bucket[i].sent_time & RATE_TIME_MASK; \ + min_sent_idx = i; \ + } \ + } \ + struct persrc_rate##IPV##_entry *entry = &first_bucket[min_sent_idx]; \ + if (entry->srcip != key) { \ + entry->srcip = key; \ + entry->sent_time = 0; \ + } \ + int matched = 0; \ + DO_RATE_LIMIT(, entry, cur_time_masked, amt, limit_ns_per_pkt, matched); \ + bpf_spin_unlock(&buckets->lock); \ + return matched; \ +} + +CREATE_PERSRC_LOOKUP(6, uint128_t) +CREATE_PERSRC_LOOKUP(5, uint64_t) // IPv6 matching no more than a /64 +CREATE_PERSRC_LOOKUP(4, uint32_t) + +#define SRC_RATE_DEFINE(IPV, n, limit) \ +struct persrc_rate##IPV##_bucket_##n { \ + struct bpf_spin_lock lock; \ + struct persrc_rate##IPV##_entry entries[limit / SRC_HASH_MAX_PARALLELISM]; \ +}; \ +struct { \ + __uint(type, BPF_MAP_TYPE_ARRAY); \ + __uint(max_entries, SRC_HASH_MAX_PARALLELISM); \ + uint32_t *key; \ + struct persrc_rate##IPV##_bucket_##n *value; \ +} v##IPV##_src_rate_##n SEC(".maps"); + +#include "maps.h" + +#ifndef HAVE_WRAPPER // Set this to call xdp_drop externally SEC("xdp_drop") -#endif +#endif /* HAVE_WRAPPER */ +#endif /* not TEST */ int xdp_drop_prog(struct xdp_md *ctx) { const void *const data_end = (void *)(size_t)ctx->data_end; @@ -172,30 +331,32 @@ int xdp_drop_prog(struct xdp_md *ctx) unsigned short eth_proto; { + // DO_RETURN in CHECK_LEN relies on pktdata being set to calculate packet length. + // That said, we don't want to overflow, so just set packet length to 0 here. + pktdata = data_end; CHECK_LEN((size_t)ctx->data, ethhdr); const struct ethhdr *const eth = (void*)(size_t)ctx->data; + pktdata = (const void *)(long)ctx->data + sizeof(struct ethhdr); #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; - + pktdata = (const void *)(long)ctx->data + sizeof(struct ethhdr_vlan); #ifdef REQ_8021Q 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))) { + pktdata = (const void *)(long)ctx->data + sizeof(struct ethhdr_vlan); DO_RETURN(VLAN_DROP, PARSE_8021Q); #endif } else { #ifdef REQ_8021Q DO_RETURN(VLAN_DROP, XDP_DROP); #else - pktdata = (const void *)(long)ctx->data + sizeof(struct ethhdr); eth_proto = eth->h_proto; #endif } @@ -203,8 +364,7 @@ int xdp_drop_prog(struct xdp_md *ctx) 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 + int32_t sport = -1, dport = -1; // Host Endian! Only valid with tcp || udp #ifdef NEED_V4_PARSE if (eth_proto == BE16(ETH_P_IP)) { @@ -226,13 +386,11 @@ int xdp_drop_prog(struct xdp_md *ctx) 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; @@ -273,13 +431,11 @@ int xdp_drop_prog(struct xdp_md *ctx) 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;