Track drops

diff --git a/genrules.py b/genrules.py
index 6c8411b03ec3962a8100e3aa585e34fb3197ba04..40fc5c1f2d84969b959e5d30fdaad8c3c29cdf20 100755 (executable)
--- a/genrules.py
+++ b/genrules.py
@@ -272,6 +272,7 @@ with open("rules.h", "w") as out:
     use_v4 = False
     use_v6 = False
     use_v6_frags = False
+    rulecnt = 0
 
     out.write("#define RULES \\\n")
 
@@ -334,10 +335,13 @@ with open("rules.h", "w") as out:
                 pass
             else:
                 assert False
-        out.write("\t\treturn XDP_DROP;\\\n")
+        out.write(f"\t\tconst uint32_t ruleidx = STATIC_RULE_CNT + {rulecnt};\\\n")
+        out.write("\t\tDO_RETURN(ruleidx, XDP_DROP);\\\n")
         out.write("\t} while(0);\\\n}\\\n")
+        rulecnt += 1
 
     out.write("\n")
+    out.write(f"#define RULECNT {rulecnt}\n")
     if use_v4:
         out.write("#define NEED_V4_PARSE\n")
     if use_v6:

diff --git a/xdp.c b/xdp.c
index 10ed78b2a22411988661a367de4a87fc73817bef..1709e00cfb727e308c541d60441c8ce50c828707 100644 (file)
--- a/xdp.c
+++ b/xdp.c
@@ -111,6 +111,12 @@ 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
+
 #ifdef TEST
 // 64 bit version of xdp_md for testing
 struct xdp_md {
@@ -125,10 +131,32 @@ 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
 int xdp_drop_prog(struct xdp_md *ctx)
@@ -140,29 +168,29 @@ int xdp_drop_prog(struct xdp_md *ctx)
 
        {
                if (unlikely((void*)(size_t)ctx->data + sizeof(struct ethhdr) > data_end))
-                       return XDP_DROP;
+                       DO_RETURN(PKT_LEN_DROP, XDP_DROP);
                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;
+                               DO_RETURN(PKT_LEN_DROP, XDP_DROP);
                        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;
@@ -187,28 +215,28 @@ int xdp_drop_prog(struct xdp_md *ctx)
 #ifdef NEED_V4_PARSE
        if (eth_proto == BE16(ETH_P_IP)) {
                if (unlikely(pktdata + sizeof(struct iphdr) > data_end))
-                       return XDP_DROP;
+                       DO_RETURN(PKT_LEN_DROP, XDP_DROP);
                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;
+                               DO_RETURN(PKT_LEN_DROP, XDP_DROP);
                        tcp = (struct tcphdr*) l4hdr;
                } else if (ip->protocol == IP_PROTO_UDP) {
                        if (unlikely(l4hdr + sizeof(struct udphdr) > data_end))
-                               return XDP_DROP;
+                               DO_RETURN(PKT_LEN_DROP, XDP_DROP);
                        udp = (struct udphdr*) l4hdr;
                } else if (ip->protocol == IP_PROTO_ICMP) {
                        if (unlikely(l4hdr + sizeof(struct icmphdr) > data_end))
-                               return XDP_DROP;
+                               DO_RETURN(PKT_LEN_DROP, XDP_DROP);
                        icmp = (struct icmphdr*) l4hdr;
                }
        }
@@ -216,7 +244,7 @@ int xdp_drop_prog(struct xdp_md *ctx)
 #ifdef NEED_V6_PARSE
        if (eth_proto == BE16(ETH_P_IPV6)) {
                if (unlikely(pktdata + sizeof(struct ip6hdr) > data_end))
-                       return XDP_DROP;
+                       DO_RETURN(PKT_LEN_DROP, XDP_DROP);
                ip6 = (struct ip6hdr*) pktdata;
 
                l4hdr = pktdata + 40;
@@ -226,28 +254,28 @@ int xdp_drop_prog(struct xdp_md *ctx)
 #if PARSE_V6_FRAG == PARSE
                if (ip6->nexthdr == IP6_PROTO_FRAG) {
                        if (unlikely(l4hdr + sizeof(struct ip6_fraghdr) > data_end))
-                               return XDP_DROP;
+                               DO_RETURN(PKT_LEN_DROP, XDP_DROP);
                        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;
+                               DO_RETURN(PKT_LEN_DROP, XDP_DROP);
                        tcp = (struct tcphdr*) l4hdr;
                } else if (v6nexthdr == IP_PROTO_UDP) {
                        if (unlikely(l4hdr + sizeof(struct udphdr) > data_end))
-                               return XDP_DROP;
+                               DO_RETURN(PKT_LEN_DROP, XDP_DROP);
                        udp = (struct udphdr*) l4hdr;
                } else if (v6nexthdr == IP6_PROTO_ICMPV6) {
                        if (unlikely(l4hdr + sizeof(struct icmp6hdr) > data_end))
-                               return XDP_DROP;
+                               DO_RETURN(PKT_LEN_DROP, XDP_DROP);
                        icmpv6 = (struct icmp6hdr*) l4hdr;
                }
                // TODO: Handle some options?