X-Git-Url: http://git.bitcoin.ninja/index.cgi?p=flowspec-xdp;a=blobdiff_plain;f=genrules.py;h=7e71d755fbd43e1187e76651b3e4c3ede8716eeb;hp=6de93829c18529a10e2feb5c0dad285d4efa5c0b;hb=109e2f9ca7608102bbb276296a2cf8389e22c5cb;hpb=d1468659faf993c7ccb398e3e35b8132bb208d83 diff --git a/genrules.py b/genrules.py index 6de9382..7e71d75 100755 --- a/genrules.py +++ b/genrules.py @@ -4,6 +4,7 @@ import sys import ipaddress from enum import Enum import argparse +import math IP_PROTO_ICMP = 1 @@ -44,20 +45,26 @@ class ASTNode: if self.action == ASTAction.EXPR: return self.left.write(expr_param, expr_param2) -def parse_ast(expr, parse_expr): +def parse_ast(expr, parse_expr, comma_is_or): expr = expr.strip() comma_split = expr.split(",", 1) or_split = expr.split("||", 1) if len(comma_split) > 1 and not "||" in comma_split[0]: - return ASTNode(ASTAction.OR, parse_ast(comma_split[0], parse_expr), parse_ast(comma_split[1], parse_expr)) + # Confusingly, BIRD uses `,` as either || or &&, depending on the type + # of expression being parsed. Specifically, a `numbers-match` uses `,` + # as OR, whereas a `bitmask-match` uses `,` as AND. + if comma_is_or: + return ASTNode(ASTAction.OR, parse_ast(comma_split[0], parse_expr, comma_is_or), parse_ast(comma_split[1], parse_expr, comma_is_or)) + else: + return ASTNode(ASTAction.AND, parse_ast(comma_split[0], parse_expr, comma_is_or), parse_ast(comma_split[1], parse_expr, comma_is_or)) if len(or_split) > 1: assert not "," in or_split[0] - return ASTNode(ASTAction.OR, parse_ast(or_split[0], parse_expr), parse_ast(or_split[1], parse_expr)) + return ASTNode(ASTAction.OR, parse_ast(or_split[0], parse_expr, comma_is_or), parse_ast(or_split[1], parse_expr, comma_is_or)) and_split = expr.split("&&", 1) if len(and_split) > 1: - return ASTNode(ASTAction.AND, parse_ast(and_split[0], parse_expr), parse_ast(and_split[1], parse_expr)) + return ASTNode(ASTAction.AND, parse_ast(and_split[0], parse_expr, comma_is_or), parse_ast(and_split[1], parse_expr, comma_is_or)) if expr.strip() == "true": return ASTNode(ASTAction.TRUE, None) @@ -65,7 +72,7 @@ def parse_ast(expr, parse_expr): return ASTNode(ASTAction.FALSE, None) if expr.startswith("!"): - return ASTNode(ASTAction.NOT, parse_ast(expr[1:], parse_expr)) + return ASTNode(ASTAction.NOT, parse_ast(expr[1:], parse_expr, comma_is_or)) return parse_expr(expr) @@ -192,15 +199,15 @@ def ip_to_rule(proto, inip, ty, offset): break;""" def fragment_to_rule(ipproto, rules): - ast = parse_ast(rules, parse_frag_expr) + ast = parse_ast(rules, parse_frag_expr, False) return "if (!( " + ast.write(ipproto) + " )) break;" def len_to_rule(rules): - ast = parse_ast(rules, parse_numbers_expr) + ast = parse_ast(rules, parse_numbers_expr, True) return "if (!( " + ast.write("(data_end - pktdata)") + " )) break;" def proto_to_rule(ipproto, proto): - ast = parse_ast(proto, parse_numbers_expr) + ast = parse_ast(proto, parse_numbers_expr, True) if ipproto == 4: return "if (!( " + ast.write("ip->protocol") + " )) break;" @@ -208,47 +215,48 @@ def proto_to_rule(ipproto, proto): return "if (!( " + ast.write("ip6->nexthdr") + " )) break;" def icmp_type_to_rule(proto, ty): - ast = parse_ast(ty, parse_numbers_expr) + ast = parse_ast(ty, parse_numbers_expr, True) if proto == 4: return "if (icmp == NULL) break;\nif (!( " + ast.write("icmp->type") + " )) break;" else: return "if (icmpv6 == NULL) break;\nif (!( " + ast.write("icmpv6->icmp6_type") + " )) break;" def icmp_code_to_rule(proto, code): - ast = parse_ast(code, parse_numbers_expr) + ast = parse_ast(code, parse_numbers_expr, True) if proto == 4: return "if (icmp == NULL) break;\nif (!( " + ast.write("icmp->code") + " )) break;" else: return "if (icmpv6 == NULL) break;\nif (!( " + ast.write("icmpv6->icmp6_code") + " )) break;" def dscp_to_rule(proto, rules): - ast = parse_ast(rules, parse_numbers_expr) + ast = parse_ast(rules, parse_numbers_expr, True) if proto == 4: return "if (!( " + ast.write("((ip->tos & 0xfc) >> 2)") + " )) break;" else: - return "if (!( " + ast.write("((ip6->priority << 4) | ((ip6->flow_lbl[0] & 0xc0) >> 4) >> 2)") + " )) break;" + return "if (!( " + ast.write("((ip6->priority << 2) | ((ip6->flow_lbl[0] & 0xc0) >> 6))") + " )) break;" def port_to_rule(ty, rules): if ty == "port" : - ast = parse_ast(rules, parse_numbers_expr) - return "if (tcp == NULL && udp == NULL) break;\nif (!( " + ast.write("sport", "dport") + " )) break;" + ast = parse_ast(rules, parse_numbers_expr, True) + return "if (sport == -1 || dport == -1) break;\nif (!( " + ast.write("sport", "dport") + " )) break;" - ast = parse_ast(rules, parse_numbers_expr) - return "if (tcp == NULL && udp == NULL) break;\nif (!( " + ast.write(ty) + " )) break;" + ast = parse_ast(rules, parse_numbers_expr, True) + return "if (" + ty + " == -1) break;\nif (!( " + ast.write(ty) + " )) break;" def tcp_flags_to_rule(rules): - ast = parse_ast(rules, parse_bit_expr) + ast = parse_ast(rules, parse_bit_expr, False) return f"""if (tcp == NULL) break; if (!( {ast.write("(ntohs(tcp->flags) & 0xfff)")} )) break;""" def flow_label_to_rule(rules): - ast = parse_ast(rules, parse_bit_expr) + ast = parse_ast(rules, parse_bit_expr, False) return f"""if (ip6 == NULL) break; if (!( {ast.write("((((uint32_t)(ip6->flow_lbl[0] & 0xf)) << 2*8) | (((uint32_t)ip6->flow_lbl[1]) << 1*8) | (uint32_t)ip6->flow_lbl[0])")} )) break;""" + with open("rules.h", "w") as out: parse = argparse.ArgumentParser() parse.add_argument("--ihl", dest="ihl", required=True, choices=["drop-options","accept-options","parse-options"]) @@ -283,83 +291,232 @@ with open("rules.h", "w") as out: assert False out.write("#define REQ_8021Q " + args.vlan_tag + "\n") - use_v4 = False - use_v6 = False + rules6 = "" + rules4 = "" use_v6_frags = False - rulecnt = 0 - - out.write("#define RULES \\\n") - - def write_rule(r): - out.write("\t\t" + r.replace("\n", " \\\n\t\t") + " \\\n") + stats_rulecnt = 0 + ratelimitcnt = 0 + v4persrcratelimits = [] + v5persrcratelimits = [] + v6persrcratelimits = [] + lastrule = None for line in sys.stdin.readlines(): - t = line.split("{") - if len(t) != 2: - continue - if t[0].strip() == "flow4": - proto = 4 - use_v4 = True - out.write("if (eth_proto == htons(ETH_P_IP)) { \\\n") - out.write("\tdo {\\\n") - elif t[0].strip() == "flow6": - proto = 6 - use_v6 = True - out.write("if (eth_proto == htons(ETH_P_IPV6)) { \\\n") - out.write("\tdo {\\\n") - else: + if "{" in line: + if lastrule is not None: + print("Skipped rule due to lack of understood community tag: " + lastrule) + lastrule = line continue + if "BGP.ext_community: " in line: + assert lastrule is not None + + t = lastrule.split("{") + if t[0].strip() == "flow4": + proto = 4 + rules4 += "\tdo {\\\n" + elif t[0].strip() == "flow6": + proto = 6 + rules6 += "\tdo {\\\n" + else: + continue - rule = t[1].split("}")[0].strip() - for step in rule.split(";"): - if step.strip().startswith("src") or step.strip().startswith("dst"): - nets = step.strip()[3:].strip().split(" ") - if len(nets) > 1: - assert nets[1] == "offset" - offset = nets[2] + def write_rule(r): + global rules4, rules6 + if proto == 6: + rules6 += "\t\t" + r.replace("\n", " \\\n\t\t") + " \\\n" else: - offset = None - if step.strip().startswith("src"): - write_rule(ip_to_rule(proto, nets[0], "saddr", offset)) + rules4 += "\t\t" + r.replace("\n", " \\\n\t\t") + " \\\n" + + rule = t[1].split("}")[0].strip() + for step in rule.split(";"): + if step.strip().startswith("src") or step.strip().startswith("dst"): + nets = step.strip()[3:].strip().split(" ") + if len(nets) > 1: + assert nets[1] == "offset" + offset = nets[2] + else: + offset = None + if step.strip().startswith("src"): + write_rule(ip_to_rule(proto, nets[0], "saddr", offset)) + else: + write_rule(ip_to_rule(proto, nets[0], "daddr", offset)) + elif step.strip().startswith("proto") and proto == 4: + write_rule(proto_to_rule(4, step.strip()[6:])) + elif step.strip().startswith("next header") and proto == 6: + write_rule(proto_to_rule(6, step.strip()[12:])) + elif step.strip().startswith("icmp type"): + write_rule(icmp_type_to_rule(proto, step.strip()[10:])) + elif step.strip().startswith("icmp code"): + write_rule(icmp_code_to_rule(proto, step.strip()[10:])) + elif step.strip().startswith("sport") or step.strip().startswith("dport") or step.strip().startswith("port"): + write_rule(port_to_rule(step.strip().split(" ")[0], step.strip().split(" ", 1)[1])) + elif step.strip().startswith("length"): + write_rule(len_to_rule(step.strip()[7:])) + elif step.strip().startswith("dscp"): + write_rule(dscp_to_rule(proto, step.strip()[5:])) + elif step.strip().startswith("tcp flags"): + write_rule(tcp_flags_to_rule(step.strip()[10:])) + elif step.strip().startswith("label"): + write_rule(flow_label_to_rule(step.strip()[6:])) + elif step.strip().startswith("fragment"): + if proto == 6: + use_v6_frags = True + write_rule(fragment_to_rule(proto, step.strip()[9:])) + elif step.strip() == "": + pass else: - write_rule(ip_to_rule(proto, nets[0], "daddr", offset)) - elif step.strip().startswith("proto") and proto == 4: - write_rule(proto_to_rule(4, step.strip()[6:])) - elif step.strip().startswith("next header") and proto == 6: - write_rule(proto_to_rule(6, step.strip()[12:])) - elif step.strip().startswith("icmp type"): - write_rule(icmp_type_to_rule(proto, step.strip()[10:])) - elif step.strip().startswith("icmp code"): - write_rule(icmp_code_to_rule(proto, step.strip()[10:])) - elif step.strip().startswith("sport") or step.strip().startswith("dport") or step.strip().startswith("port"): - write_rule(port_to_rule(step.strip().split(" ")[0], step.strip().split(" ", 1)[1])) - elif step.strip().startswith("length"): - write_rule(len_to_rule(step.strip()[7:])) - elif step.strip().startswith("dscp"): - write_rule(dscp_to_rule(proto, step.strip()[5:])) - elif step.strip().startswith("tcp flags"): - write_rule(tcp_flags_to_rule(step.strip()[10:])) - elif step.strip().startswith("label"): - write_rule(flow_label_to_rule(step.strip()[6:])) - elif step.strip().startswith("fragment"): - if proto == 6: - use_v6_frags = True - write_rule(fragment_to_rule(proto, step.strip()[9:])) - elif step.strip() == "": - pass + assert False + + # Now write the match handling! + first_action = None + stats_action = "" + last_action = None + for community in line.split("("): + if not community.startswith("generic, "): + continue + blocks = community.split(",") + assert len(blocks) == 3 + if len(blocks[1].strip()) != 10: # Should be 0x12345678 + continue + ty = blocks[1].strip()[:6] + high_byte = int(blocks[1].strip()[6:8], 16) + mid_byte = int(blocks[1].strip()[8:], 16) + low_bytes = int(blocks[2].strip(") \n"), 16) + if ty == "0x8006" or ty == "0x800c" or ty == "0x8306" or ty == "0x830c": + if first_action is not None: + # Two ratelimit actions, just drop the old one. RFC 8955 says we can. + first_action = None + exp = (low_bytes & (0xff << 23)) >> 23 + if low_bytes == 0: + first_action = "{stats_replace}\nreturn XDP_DROP;" + elif low_bytes & (1 << 31) != 0: + # Negative limit, just drop + first_action = "{stats_replace}\nreturn XDP_DROP;" + elif exp == 0xff: + # NaN/INF. Just treat as INF and accept + first_action = None + elif exp < 127: # < 1 + first_action = "{stats_replace}\nreturn XDP_DROP;" + elif exp >= 127 + 29: # We can't handle the precision required with ns this high + first_action = None + else: + mantissa = low_bytes & ((1 << 23) - 1) + value = 1.0 + mantissa / (2**23) + value *= 2**(exp-127) + + first_action = "int64_t time_masked = bpf_ktime_get_ns() & RATE_TIME_MASK;\n" + first_action += f"int64_t per_pkt_ns = (1000000000LL << RATE_BUCKET_INTEGER_BITS) / {math.floor(value)};\n" + if ty == "0x8006" or ty == "0x800c": + spin_lock = "bpf_spin_lock(&rate->lock);" + spin_unlock = "bpf_spin_unlock(&rate->lock);" + first_action += f"const uint32_t ratelimitidx = {ratelimitcnt};\n" + first_action += "struct ratelimit *rate = bpf_map_lookup_elem(&rate_map, &ratelimitidx);\n" + ratelimitcnt += 1 + else: + spin_lock = "/* No locking as we're locked in get_v*_persrc_ratelimit */" + spin_unlock = "bpf_spin_unlock(rate_ptr.lock);" + if proto == 4: + if mid_byte > 32: + continue + first_action += f"const uint32_t srcip = ip->saddr & MASK4({mid_byte});\n" + first_action += f"void *rate_map = &v4_src_rate_{len(v4persrcratelimits)};\n" + first_action += f"struct persrc_rate4_ptr rate_ptr = get_v4_persrc_ratelimit(srcip, rate_map, {(high_byte + 1) * 4096}, time_masked);\n" + first_action += f"struct persrc_rate4_entry *rate = rate_ptr.rate;\n" + v4persrcratelimits.append((high_byte + 1) * 4096) + elif mid_byte <= 64: + first_action += f"const uint64_t srcip = BE128BEHIGH64(ip6->saddr & MASK6({mid_byte}));\n" + first_action += f"void *rate_map = &v5_src_rate_{len(v5persrcratelimits)};\n" + first_action += f"struct persrc_rate5_ptr rate_ptr = get_v5_persrc_ratelimit(srcip, rate_map, {(high_byte + 1) * 4096}, time_masked);\n" + first_action += f"struct persrc_rate5_entry *rate = rate_ptr.rate;\n" + v5persrcratelimits.append((high_byte + 1) * 4096) + else: + if mid_byte > 128: + continue + first_action += f"const uint128_t srcip = ip6->saddr & MASK6({mid_byte});\n" + first_action += f"void *rate_map = &v6_src_rate_{len(v6persrcratelimits)};\n" + first_action += f"struct persrc_rate6_ptr rate_ptr = get_v6_persrc_ratelimit(srcip, rate_map, {(high_byte + 1) * 4096}, time_masked);\n" + first_action += f"struct persrc_rate6_entry *rate = rate_ptr.rate;\n" + v6persrcratelimits.append((high_byte + 1) * 4096) + if ty == "0x8006" or ty == "0x8306": + first_action += "uint64_t amt = data_end - pktdata;\n" + else: + first_action += "uint64_t amt = 1;\n" + first_action += "if (rate) {\n" + first_action += f"\t{spin_lock}\n" + first_action += "\tint64_t bucket_pkts = (rate->sent_time & (~RATE_TIME_MASK)) >> (64 - RATE_BUCKET_BITS);\n" + # We mask the top 12 bits, so date overflows every 52 days, handled below + first_action += "\tint64_t time_diff = time_masked - ((int64_t)(rate->sent_time & RATE_TIME_MASK));\n" + first_action += "\tif (unlikely(time_diff < -1000000000 || time_diff > 16000000000)) {\n" + first_action += "\t\tbucket_pkts = 0;\n" + first_action += "\t} else {\n" + first_action += "\t\tif (unlikely(time_diff < 0)) { time_diff = 0; }\n" + first_action += f"\t\tint64_t pkts_since_last = (time_diff << RATE_BUCKET_BITS) * amt / per_pkt_ns;\n" + first_action += "\t\tbucket_pkts -= pkts_since_last;\n" + first_action += "\t}\n" + first_action += "\tif (bucket_pkts >= (((1 << RATE_BUCKET_INTEGER_BITS) - 1) << RATE_BUCKET_DECIMAL_BITS)) {\n" + first_action += f"\t\t{spin_unlock}\n" + first_action += "\t\t{stats_replace}\n" + first_action += "\t\treturn XDP_DROP;\n" + first_action += "\t} else {\n" + first_action += "\t\tif (unlikely(bucket_pkts < 0)) bucket_pkts = 0;\n" + first_action += f"\t\trate->sent_time = time_masked | ((bucket_pkts + (1 << RATE_BUCKET_DECIMAL_BITS)) << (64 - RATE_BUCKET_BITS));\n" + first_action += f"\t\t{spin_unlock}\n" + first_action += "\t}\n" + first_action += "}\n" + elif ty == "0x8007": + if low_bytes & 1 == 0: + last_action = "return XDP_PASS;" + if low_bytes & 2 == 2: + stats_action = f"const uint32_t ruleidx = STATIC_RULE_CNT + {stats_rulecnt};\n" + stats_action += "INCREMENT_MATCH(ruleidx);" + elif ty == "0x8008": + assert False # We do not implement the redirect action + elif ty == "0x8009": + if low_bytes & ~0b111111 != 0: + assert False # Invalid DSCP value + if proto == 4: + write_rule("int32_t chk = ~BE16(ip->check) & 0xffff;") + write_rule("uint8_t orig_tos = ip->tos;") + write_rule("ip->tos = (ip->tos & 3) | " + str(low_bytes << 2) + ";") + write_rule("chk = (chk - orig_tos + ip->tos);") + write_rule("if (unlikely(chk > 0xffff)) { chk -= 65535; }") + write_rule("else if (unlikely(chk < 0)) { chk += 65535; }") + write_rule("ip->check = ~BE16(chk);") + else: + write_rule("ip6->priority = " + str(low_bytes >> 2) + ";") + write_rule("ip6->flow_lbl[0] = (ip6->flow_lbl[0] & 0x3f) | " + str((low_bytes & 3) << 6) + ";") + if first_action is not None: + write_rule(first_action.replace("{stats_replace}", stats_action)) + if stats_action != "" and (first_action is None or "{stats_replace}" not in first_action): + write_rule(stats_action) + if last_action is not None: + write_rule(last_action) + if proto == 6: + rules6 += "\t} while(0);\\\n" else: - assert False - 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 + rules4 += "\t} while(0);\\\n" + if stats_action != "": + print(rule) + stats_rulecnt += 1 + lastrule = None out.write("\n") - out.write(f"#define RULECNT {rulecnt}\n") - if use_v4: + out.write(f"#define STATS_RULECNT {stats_rulecnt}\n") + if ratelimitcnt != 0: + out.write(f"#define RATE_CNT {ratelimitcnt}\n") + if rules4 != "": out.write("#define NEED_V4_PARSE\n") - if use_v6: + out.write("#define RULES4 {\\\n" + rules4 + "}\n") + if rules6: out.write("#define NEED_V6_PARSE\n") + out.write("#define RULES6 {\\\n" + rules6 + "}\n") if args.v6frag == "ignore-parse-if-rule": if use_v6_frags: out.write("#define PARSE_V6_FRAG PARSE\n") + with open("maps.h", "w") as out: + for idx, limit in enumerate(v4persrcratelimits): + out.write(f"SRC_RATE_DEFINE(4, {idx}, {limit})\n") + for idx, limit in enumerate(v5persrcratelimits): + out.write(f"SRC_RATE_DEFINE(5, {idx}, {limit})\n") + for idx, limit in enumerate(v6persrcratelimits): + out.write(f"SRC_RATE_DEFINE(6, {idx}, {limit})\n")