From 66e2db182f749072cac361b873dcc35d6377468e Mon Sep 17 00:00:00 2001 From: Matt Corallo Date: Sat, 3 Apr 2021 21:43:17 -0400 Subject: [PATCH] Track drops --- genrules.py | 6 +++++- xdp.c | 62 ++++++++++++++++++++++++++++++++++++++--------------- 2 files changed, 50 insertions(+), 18 deletions(-) diff --git a/genrules.py b/genrules.py index 6c8411b..40fc5c1 100755 --- 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 10ed78b..1709e00 100644 --- 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 #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, +}; +#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? -- 2.39.5