X-Git-Url: http://git.bitcoin.ninja/index.cgi?p=flowspec-xdp;a=blobdiff_plain;f=genrules.py;h=a9f3d16db50c54ee04830757a4d5482fd8d7f39c;hp=10f138f277cb2657931488743f0f3f3aa81f2390;hb=HEAD;hpb=9257387510c6760e67d28d24fe520e6ef9cd59d4 diff --git a/genrules.py b/genrules.py index 10f138f..a9f3d16 100755 --- a/genrules.py +++ b/genrules.py @@ -12,6 +12,10 @@ IP_PROTO_ICMPV6 = 58 IP_PROTO_TCP = 6 IP_PROTO_UDP = 17 +ORD_LESS = 0 +ORD_GREATER = 1 +ORD_EQUAL = 2 + class ASTAction(Enum): OR = 1 AND = 2 @@ -175,28 +179,67 @@ def parse_bit_expr(expr): return ASTNode(ASTAction.EXPR, BitExpr(expr)) +class IpRule: + def __init__(self, ty, offset, net, proto): + self.ty = ty + self.offset = offset + if offset is None: + self.offset = 0 + self.net = net + self.proto = proto + + def ord(self, other): + assert self.ty == other.ty + assert self.proto == other.proto + if self.offset < other.offset: + return ORD_LESS + if self.offset > other.offset: + return ORD_GREATER + + if self.net.overlaps(other.net): + if self.net.prefixlen > other.net.prefixlen: + return ORD_LESS + elif self.net.prefixlen < other.net.prefixlen: + return ORD_GREATER + else: + if self.net < other.net: + return ORD_LESS + else: + assert self.net > other.net + return ORD_GREATER + + return ORD_EQUAL + + def __lt__(self, other): + return self.ord(other) == ORD_LESS + + def __eq__(self, other): + return type(other) == IpRule and self.ty == other.ty and self.offset == other.offset and self.net == other.net and self.proto == other.proto + + def __str__(self): + if self.proto == 4: + assert self.offset == 0 + return f"""if ((ip->{self.ty} & MASK4({self.net.prefixlen})) != BIGEND32({int(self.net.network_address)}ULL)) + break;""" + else: + u32s = [(int(self.net.network_address) >> (3*32)) & 0xffffffff, + (int(self.net.network_address) >> (2*32)) & 0xffffffff, + (int(self.net.network_address) >> (1*32)) & 0xffffffff, + (int(self.net.network_address) >> (0*32)) & 0xffffffff] + if self.offset == 0: + mask = f"MASK6({self.net.prefixlen})" + else: + mask = f"MASK6_OFFS({self.offset}, {self.net.prefixlen})" + return f"""if ((ip6->{self.ty} & {mask}) != (BIGEND128({u32s[0]}ULL, {u32s[1]}ULL, {u32s[2]}ULL, {u32s[3]}ULL) & {mask})) + break;""" def ip_to_rule(proto, inip, ty, offset): if proto == 4: assert offset is None net = ipaddress.IPv4Network(inip.strip()) - if net.prefixlen == 0: - return "" - return f"""if ((ip->{ty} & MASK4({net.prefixlen})) != BIGEND32({int(net.network_address)}ULL)) - break;""" + return IpRule(ty, offset, net, 4) else: net = ipaddress.IPv6Network(inip.strip()) - if net.prefixlen == 0: - return "" - u32s = [(int(net.network_address) >> (3*32)) & 0xffffffff, - (int(net.network_address) >> (2*32)) & 0xffffffff, - (int(net.network_address) >> (1*32)) & 0xffffffff, - (int(net.network_address) >> (0*32)) & 0xffffffff] - if offset is None: - mask = f"MASK6({net.prefixlen})" - else: - mask = f"MASK6_OFFS({offset}, {net.prefixlen})" - return f"""if ((ip6->{ty} & {mask}) != (BIGEND128({u32s[0]}ULL, {u32s[1]}ULL, {u32s[2]}ULL, {u32s[3]}ULL) & {mask})) - break;""" + return IpRule(ty, offset, net, 6) def fragment_to_rule(ipproto, rules): ast = parse_ast(rules, parse_frag_expr, False) @@ -256,6 +299,100 @@ 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;""" +class RuleAction(Enum): + CONDITIONS = 1 + ACTION = 2 + LIST = 3 +class RuleNode: + def __init__(self, ty, action, inner): + self.ty = ty + self.action = action + self.inner = inner + if ty == RuleAction.ACTION: + assert inner is None + assert type(action) == str + elif ty == RuleAction.LIST: + assert type(inner) == list + assert action is None + for item in inner: + assert type(item) == RuleNode + else: + assert ty == RuleAction.CONDITIONS + assert type(action) == list + assert type(inner) == RuleNode + + def __lt__(self, other): + assert self.ty == RuleAction.CONDITIONS + assert other.ty == RuleAction.CONDITIONS + + o = ORD_EQUAL + + # RFC first has us sort by dest, then source, then other conditions. We don't implement the + # other conditions because doing so requires re-implementing the Flowspec wire format, + # which isn't trivial. However, we do implement the source/dest sorting in the hopes it + # allows us to group rules according to source/dest IP and hopefully LLVM optimizes out + # later rules. + + selfdest = next(filter(lambda a : type(a) == IpRule and a.ty == "daddr", self.action), None) + otherdest = next(filter(lambda a : type(a) == IpRule and a.ty == "daddr", self.action), None) + if o == ORD_EQUAL and selfdest is not None and otherdest is not None: + o = selfdest.ord(otherdest) + + if o == ORD_EQUAL: + selfsrc = next(filter(lambda a : type(a) == IpRule and a.ty == "saddr", self.action), None) + othersrc = next(filter(lambda a : type(a) == IpRule and a.ty == "saddr", self.action), None) + if selfsrc is not None and othersrc is None: + return True + elif selfsrc is None and othersrc is not None: + return False + elif selfsrc is not None and othersrc is not None: + o = selfsrc.ord(othersrc) + + if o == ORD_LESS: + return True + return self.action < other.action + + def maybe_join(self, neighbor): + if self.ty == RuleAction.CONDITIONS and neighbor.ty == RuleAction.CONDITIONS: + overlapping_conditions = [x for x in self.action if x in neighbor.action] + if len(overlapping_conditions) != 0: + us = RuleNode(RuleAction.CONDITIONS, [x for x in self.action if x not in overlapping_conditions], self.inner) + them = RuleNode(RuleAction.CONDITIONS, [x for x in neighbor.action if x not in overlapping_conditions], neighbor.inner) + self.action = overlapping_conditions + if self.inner.ty == RuleAction.LIST and us.action == []: + self.inner.inner.append(them) + else: + self.inner = RuleNode(RuleAction.LIST, None, [us, them]) + self.inner.flatten() + return True + return False + + def flatten(self): + # LLVM can be pretty bad at optimizing out common subexpressions. Thus, we have to do a + # pass here to toptimize out common subexpressions in back-to-back rules. + # See https://bugs.llvm.org/show_bug.cgi?id=52455 + assert self.ty == RuleAction.LIST + did_update = True + while did_update: + did_update = False + for i in range(0, len(self.inner) - 1): + if self.inner[i].maybe_join(self.inner[i + 1]): + del self.inner[i + 1] + did_update = True + break + + def write(self, out, pfx="\t"): + if self.ty == RuleAction.CONDITIONS: + out.write(pfx + "do {\\\n") + for cond in self.action: + out.write("\t" + pfx + str(cond).replace("\n", " \\\n\t" + pfx) + " \\\n") + self.inner.write(out, pfx) + out.write(pfx + "} while(0);\\\n") + elif self.ty == RuleAction.LIST: + for item in self.inner: + item.write(out, pfx + "\t") + else: + out.write("\t" + pfx + self.action.strip().replace("\n", " \\\n\t" + pfx) + " \\\n") with open("rules.h", "w") as out: parse = argparse.ArgumentParser() @@ -291,8 +428,8 @@ with open("rules.h", "w") as out: assert False out.write("#define REQ_8021Q " + args.vlan_tag + "\n") - rules6 = "" - rules4 = "" + rules6 = [] + rules4 = [] use_v6_frags = False stats_rulecnt = 0 ratelimitcnt = 0 @@ -313,29 +450,15 @@ with open("rules.h", "w") as out: 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 - # LLVM can be pretty bad at optimizing out common subexpressions. Ideally we'd optimize - # by pulling common subexpressions in back-to-back rules out into a single check, but - # that's a bunch of work that LLVM really should do for us. Instead, we blindly guess - # that source-address is the least likely to be a common subexpression and rely on LLVM - # managing to pull out common subexpressions as long as they're the first check(s). By - # placing source-address checks last, LLVM should do at least some work for us. - # See https://bugs.llvm.org/show_bug.cgi?id=52455 - last_checks = "" - def write_rule(r, place_at_end=False): - global rules4, rules6, last_checks - if place_at_end: - last_checks += "\t\t" + r.replace("\n", " \\\n\t\t") + " \\\n" - elif proto == 6: - rules6 += "\t\t" + r.replace("\n", " \\\n\t\t") + " \\\n" - else: - rules4 += "\t\t" + r.replace("\n", " \\\n\t\t") + " \\\n" + conditions = [] + def write_rule(r): + global conditions + conditions.append(r) rule = t[1].split("}")[0].strip() for step in rule.split(";"): @@ -347,7 +470,7 @@ with open("rules.h", "w") as out: else: offset = None if step.strip().startswith("src"): - write_rule(ip_to_rule(proto, nets[0], "saddr", offset), True) + 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: @@ -377,10 +500,10 @@ with open("rules.h", "w") as out: else: assert False - if proto == 6: - rules6 += last_checks - else: - rules4 += last_checks + actions = "" + def write_rule(r): + global actions + actions += r + "\n" # Now write the match handling! first_action = None @@ -485,9 +608,9 @@ with open("rules.h", "w") as out: if last_action is not None: write_rule(last_action) if proto == 6: - rules6 += "\t} while(0);\\\n" + rules6.append(RuleNode(RuleAction.CONDITIONS, conditions, RuleNode(RuleAction.ACTION, actions, None))) else: - rules4 += "\t} while(0);\\\n" + rules4.append(RuleNode(RuleAction.CONDITIONS, conditions, RuleNode(RuleAction.ACTION, actions, None))) if stats_action != "": print(rule) stats_rulecnt += 1 @@ -497,12 +620,29 @@ with open("rules.h", "w") as out: out.write(f"#define STATS_RULECNT {stats_rulecnt}\n") if ratelimitcnt != 0: out.write(f"#define RATE_CNT {ratelimitcnt}\n") - if rules4 != "": + + if len(rules4) != 0: out.write("#define NEED_V4_PARSE\n") - out.write("#define RULES4 {\\\n" + rules4 + "}\n") - if rules6: + out.write("#define RULES4 {\\\n") + # First sort the rules according to the RFC, then make it a single + # LIST rule and call flatten() to unify redundant conditions + rules4.sort() + rules4 = RuleNode(RuleAction.LIST, None, rules4) + rules4.flatten() + rules4.write(out) + out.write("}\n") + + if len(rules6) != 0: out.write("#define NEED_V6_PARSE\n") - out.write("#define RULES6 {\\\n" + rules6 + "}\n") + out.write("#define RULES6 {\\\n") + # First sort the rules according to the RFC, then make it a single + # LIST rule and call flatten() to unify redundant conditions + rules6.sort() + rules6 = RuleNode(RuleAction.LIST, None, rules6) + rules6.flatten() + rules6.write(out) + out.write("}\n") + if args.v6frag == "ignore-parse-if-rule": if use_v6_frags: out.write("#define PARSE_V6_FRAG PARSE\n")