X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=genrules.py;h=da42e01732795f85a6c30b3e53913d7ac9a304f9;hb=e63afbe176e13e0b1e3092837807cd5e06886da6;hp=c0a5311916f6f25536848a21c3a5061be547bab5;hpb=b4fab99915a43a095829b2b117947f49b266b4e2;p=flowspec-xdp diff --git a/genrules.py b/genrules.py index c0a5311..da42e01 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 @@ -12,13 +13,18 @@ IP_PROTO_TCP = 6 IP_PROTO_UDP = 17 class ASTAction(Enum): - OR = 1, - AND = 2, - NOT = 3, - EXPR = 4 + OR = 1 + AND = 2 + NOT = 3 + FALSE = 4 + TRUE = 5 + EXPR = 6 class ASTNode: def __init__(self, action, left, right=None): self.action = action + if action == ASTAction.FALSE or action == ASTAction.TRUE: + assert left is None and right is None + return self.left = left if right is None: assert action == ASTAction.EXPR or action == ASTAction.NOT @@ -32,23 +38,32 @@ class ASTNode: return "(" + self.left.write(expr_param, expr_param2) + ") && (" + self.right.write(expr_param, expr_param2) + ")" if self.action == ASTAction.NOT: return "!(" + self.left.write(expr_param, expr_param2) + ")" + if self.action == ASTAction.FALSE: + return "0" + if self.action == ASTAction.TRUE: + return "1" if self.action == ASTAction.EXPR: return self.left.write(expr_param, expr_param2) def parse_ast(expr, parse_expr): expr = expr.strip() - and_split = expr.split("&&", 1) + comma_split = expr.split(",", 1) or_split = expr.split("||", 1) - if len(and_split) > 1 and not "||" in and_split[0]: - return ASTNode(ASTAction.AND, parse_ast(and_split[0], parse_expr), parse_ast(and_split[1], parse_expr)) + 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)) if len(or_split) > 1: - assert not "&&" in or_split[0] + assert not "," in or_split[0] return ASTNode(ASTAction.OR, parse_ast(or_split[0], parse_expr), parse_ast(or_split[1], parse_expr)) - comma_split = expr.split(",", 1) - if len(comma_split) > 1: - return ASTNode(ASTAction.OR, parse_ast(comma_split[0], parse_expr), parse_ast(comma_split[1], parse_expr)) + 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)) + + if expr.strip() == "true": + return ASTNode(ASTAction.TRUE, None) + if expr.strip() == "false": + return ASTNode(ASTAction.FALSE, None) if expr.startswith("!"): return ASTNode(ASTAction.NOT, parse_ast(expr[1:], parse_expr)) @@ -213,15 +228,15 @@ def dscp_to_rule(proto, rules): 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;" + return "if (!ports_valid) 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;" + return "if (!ports_valid) break;\nif (!( " + ast.write(ty) + " )) break;" def tcp_flags_to_rule(rules): ast = parse_ast(rules, parse_bit_expr) @@ -235,9 +250,11 @@ def flow_label_to_rule(rules): 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"]) + parse.add_argument("--v6frag", dest="v6frag", required=True, choices=["drop-frags","ignore","parse-frags","ignore-parse-if-rule"]) parse.add_argument("--8021q", dest="vlan", required=True, choices=["drop-vlan","accept-vlan","parse-vlan"]) parse.add_argument("--require-8021q", dest="vlan_tag") args = parse.parse_args(sys.argv[1:]) @@ -249,6 +266,13 @@ with open("rules.h", "w") as out: elif args.ihl == "parse-options": out.write("#define PARSE_IHL PARSE\n") + if args.v6frag == "drop-frags": + out.write("#define PARSE_V6_FRAG XDP_DROP\n") + elif args.v6frag == "ignore": + pass + elif args.v6frag == "parse-frags": + out.write("#define PARSE_V6_FRAG PARSE\n") + if args.vlan == "drop-vlan": out.write("#define PARSE_8021Q XDP_DROP\n") elif args.vlan == "accept-vlan": @@ -261,64 +285,187 @@ with open("rules.h", "w") as out: assert False out.write("#define REQ_8021Q " + args.vlan_tag + "\n") - out.write("#define RULES \\\n") - - def write_rule(r): - out.write("\t\t" + r.replace("\n", " \\\n\t\t") + " \\\n") + rules6 = "" + rules4 = "" + use_v6_frags = False + rulecnt = 0 + ratelimitcnt = 0 + lastrule = None for line in sys.stdin.readlines(): - t = line.split("{") - if len(t) != 2: - continue - if t[0].strip() == "flow4": - proto = 4 - out.write("if (eth_proto == htons(ETH_P_IP)) { \\\n") - out.write("\tdo {\\\n") - elif t[0].strip() == "flow6": - proto = 6 - 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"): - write_rule(fragment_to_rule(proto, step.strip()[9:])) - elif step.strip() == "": - pass + assert False + + # Now write the match handling! + first_action = None + 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] + low_bytes = int(blocks[2].strip(") \n"), 16) + if ty == "0x8006" or ty == "0x800c": + 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 = "return XDP_DROP;" + elif low_bytes & (1 << 31) != 0: + # Negative limit, just drop + first_action = "return XDP_DROP;" + elif exp == 0xff: + # NaN/INF. Just treat as INF and accept + first_action = None + elif exp <= 127: # < 1 + first_action = "return XDP_DROP;" + elif exp >= 127 + 63: # The count won't even fit in 64-bits, just accept + first_action = None + else: + mantissa = low_bytes & ((1 << 23) - 1) + value = 1.0 + mantissa / (2**23) + value *= 2**(exp-127) + if ty == "0x8006": + accessor = "rate->rate.sent_bytes" + else: + accessor = "rate->rate.sent_packets" + # Note that int64_t will overflow after 292 years of uptime + first_action = "int64_t time = bpf_ktime_get_ns();\n" + first_action += f"const uint32_t ratelimitidx = {ratelimitcnt};\n" + first_action += "uint64_t allowed_since_last = 0;\n" + first_action += "struct ratelimit *rate = bpf_map_lookup_elem(&rate_map, &ratelimitidx);\n" + first_action += "if (rate) {\n" + first_action += "\tbpf_spin_lock(&rate->lock);\n" + first_action += f"\tif (likely({accessor} > 0))" + " {\n" + first_action += "\t\tint64_t diff = time - rate->sent_time;\n" + # Unlikely or not, if the flow is slow, take a perf hit (though with the else if branch it doesn't matter) + first_action += "\t\tif (unlikely(diff > 1000000000))\n" + first_action += f"\t\t\t{accessor} = 0;\n" + first_action += "\t\telse if (likely(diff > 0))\n" + first_action += f"\t\t\tallowed_since_last = ((uint64_t)diff) * {math.floor(value)} / 1000000000;\n" + first_action += "\t}\n" + first_action += f"\tif ({accessor} - ((int64_t)allowed_since_last) <= 0)" + " {\n" + if ty == "0x8006": + first_action += f"\t\t{accessor} = data_end - pktdata;\n" + else: + first_action += f"\t\t{accessor} = 1;\n" + first_action += "\t\trate->sent_time = time;\n" + first_action += "\t\tbpf_spin_unlock(&rate->lock);\n" + first_action += "\t} else {\n" + first_action += "\t\tbpf_spin_unlock(&rate->lock);\n" + first_action += "\t\treturn XDP_DROP;\n" + first_action += "\t}\n" + first_action += "}\n" + ratelimitcnt += 1 + elif ty == "0x8007": + if low_bytes & 1 == 0: + last_action = "return XDP_PASS;" + if low_bytes & 2 == 2: + write_rule(f"const uint32_t ruleidx = STATIC_RULE_CNT + {rulecnt};") + write_rule("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) + if last_action is not None: + write_rule(last_action) + if proto == 6: + rules6 += "\t} while(0);\\\n" else: - assert False - out.write("\t\treturn XDP_DROP;\\\n") - out.write("\t} while(0);\\\n}\\\n") + rules4 += "\t} while(0);\\\n" + rulecnt += 1 + lastrule = None out.write("\n") + out.write(f"#define RULECNT {rulecnt}\n") + if ratelimitcnt != 0: + out.write(f"#define RATE_CNT {ratelimitcnt}\n") + if rules4 != "": + out.write("#define NEED_V4_PARSE\n") + 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")