static const int XDP_PASS = 0;
static const int XDP_DROP = 1;
-static long drop_cnt_map[RULECNT + STATIC_RULE_CNT];
+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 /* TEST */
};
struct {
__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
- __uint(max_entries, RULECNT + STATIC_RULE_CNT);
+ __uint(max_entries, STATS_RULECNT + STATIC_RULE_CNT);
__u32 *key;
struct match_counter *value;
} drop_cnt_map SEC(".maps");
} \
}
+// 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;
- int64_t sent_rate;
- int64_t sent_time;
+ uint64_t sent_time;
};
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
// 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.
-#define SRC_HASH_MAX_PARALLELISM_POW 9
+//
+// 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 3
+#define SRC_HASH_BUCKET_COUNT_POW 4
#define SRC_HASH_BUCKET_COUNT (1 << SRC_HASH_BUCKET_COUNT_POW)
-#include "rand.h"
+#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 { \
- int64_t sent_rate; \
- int64_t sent_time; \
+ uint64_t sent_time; \
IP_TYPE srcip; \
}; \
\
struct persrc_rate##IPV##_entry entries[]; \
}; \
\
-struct persrc_rate##IPV##_ptr { \
- struct persrc_rate##IPV##_entry *rate; \
- struct bpf_spin_lock *lock; \
-}; \
- \
-__attribute__((always_inline)) \
-static inline struct persrc_rate##IPV##_ptr get_v##IPV##_persrc_ratelimit(IP_TYPE key, void *map, size_t map_limit) { \
- struct persrc_rate##IPV##_ptr res = { .rate = NULL, .lock = NULL }; \
- uint64_t hash = siphash(&key, sizeof(key), COMPILE_TIME_RAND); \
+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 res; \
+ 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); \
\
- int min_sent_idx = 0; \
- int64_t min_sent_time = INT64_MAX; \
- for (int i = 0; i < SRC_HASH_BUCKET_COUNT; i++) { \
+ 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) { \
- res.rate = &first_bucket[i]; \
- res.lock = &buckets->lock; \
- return res; \
- } else if (min_sent_time > first_bucket[i].sent_time) { \
- min_sent_time = first_bucket[i].sent_time; \
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; \
} \
- res.rate = &first_bucket[min_sent_idx]; \
- res.rate->srcip = key; \
- res.rate->sent_rate = 0; \
- res.rate->sent_time = 0; \
- res.lock = &buckets->lock; \
- return res; \
+ 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)
projects / flowspec-xdp / blobdiff