X-Git-Url: http://git.bitcoin.ninja/index.cgi?p=flowspec-xdp;a=blobdiff_plain;f=genrules.py;h=a9f3d16db50c54ee04830757a4d5482fd8d7f39c;hp=a8ad71a2a578396ba26d7e9761b16f97d3e4ae28;hb=HEAD;hpb=df0131458705400d181f9b4d3ce4a0be8be0471a diff --git a/genrules.py b/genrules.py index a8ad71a..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() @@ -291,12 +428,13 @@ 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 - rulecnt = 0 + stats_rulecnt = 0 ratelimitcnt = 0 v4persrcratelimits = [] + v5persrcratelimits = [] v6persrcratelimits = [] lastrule = None @@ -312,19 +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 + conditions = [] def write_rule(r): - global rules4, rules6 - if proto == 6: - rules6 += "\t\t" + r.replace("\n", " \\\n\t\t") + " \\\n" - else: - rules4 += "\t\t" + r.replace("\n", " \\\n\t\t") + " \\\n" + global conditions + conditions.append(r) rule = t[1].split("}")[0].strip() for step in rule.split(";"): @@ -366,9 +500,14 @@ with open("rules.h", "w") as out: else: assert False + actions = "" + def write_rule(r): + global actions + actions += r + "\n" + # Now write the match handling! first_action = None - stats_action = None + stats_action = "" last_action = None for community in line.split("("): if not community.startswith("generic, "): @@ -394,76 +533,57 @@ with open("rules.h", "w") as out: elif exp == 0xff: # NaN/INF. Just treat as INF and accept first_action = None - elif exp <= 127: # < 1 + elif exp < 127: # < 1 first_action = "{stats_replace}\nreturn XDP_DROP;" - elif exp >= 127 + 63: # The count won't even fit in 64-bits, just accept + 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) - # Note that int64_t will overflow after 292 years of uptime - first_action = "int64_t time = bpf_ktime_get_ns();\n" - first_action += "uint64_t allowed_since_last = 0;\n" + + 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 == "0x8306": + first_action += "uint64_t amt = data_end - pktdata;\n" + else: + first_action += "uint64_t amt = 1;\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 + first_action += "int matched = 0;\n" + first_action += "DO_RATE_LIMIT(bpf_spin_lock(&rate->lock), rate, time_masked, amt, per_pkt_ns, matched);\n" + first_action += "if (rate) { bpf_spin_unlock(&rate->lock); }\n" else: - spin_lock = "/* No locking as we're per-CPU */" - spin_unlock = "/* No locking as we're per-CPU */" 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" - v4persrcratelimits.append((high_byte + 1) * 1024) + first_action += f"int matched = check_v4_persrc_ratelimit(srcip, rate_map, {(high_byte + 1) * 4096}, time_masked, amt, per_pkt_ns);\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"int matched = check_v5_persrc_ratelimit(srcip, rate_map, {(high_byte + 1) * 4096}, time_masked, amt, per_pkt_ns);\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" - v6persrcratelimits.append((high_byte + 1) * 1024) - first_action += f"struct percpu_ratelimit *rate = bpf_map_lookup_elem(rate_map, &srcip);\n" - first_action += "if (rate) {\n" - first_action += f"\t{spin_lock}\n" - first_action += "\tif (likely(rate->sent_rate > 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 += "\t\t\trate->sent_rate = 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 += "\tif (rate->sent_rate - ((int64_t)allowed_since_last) <= 0)" + " {\n" - if ty == "0x8006" or ty == "0x8306": - first_action += "\t\trate->sent_rate = data_end - pktdata;\n" - else: - first_action += "\t\trate->sent_rate = 1;\n" - first_action += "\t\trate->sent_time = time;\n" - first_action += f"\t\t{spin_unlock}\n" - first_action += "\t} else {\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}\n" - if ty == "0x8306" or ty == "0x830c": - first_action += "} else {\n" - first_action += "\tstruct percpu_ratelimit new_rate = { .sent_time = time, };\n" - first_action += "\trate = &new_rate;\n" - if ty == "0x8006" or ty == "0x8306": - first_action += f"\t\trate->sent_rate = data_end - pktdata;\n" - else: - first_action += f"\t\trate->sent_rate = 1;\n" - first_action += "\tbpf_map_update_elem(rate_map, &srcip, rate, BPF_ANY);\n" + first_action += f"int matched = check_v6_persrc_ratelimit(srcip, rate_map, {(high_byte + 1) * 4096}, time_masked, amt, per_pkt_ns);\n" + v6persrcratelimits.append((high_byte + 1) * 4096) + first_action += "if (matched) {\n" + first_action += "\t{stats_replace}\n" + first_action += "\treturn XDP_DROP;\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 + {rulecnt};\n" + 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 @@ -483,32 +603,53 @@ with open("rules.h", "w") as out: 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 is not None and (first_action is None or "{stats_replace}" not in first_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" + rules6.append(RuleNode(RuleAction.CONDITIONS, conditions, RuleNode(RuleAction.ACTION, actions, None))) else: - rules4 += "\t} while(0);\\\n" - rulecnt += 1 + rules4.append(RuleNode(RuleAction.CONDITIONS, conditions, RuleNode(RuleAction.ACTION, actions, None))) + if stats_action != "": + print(rule) + stats_rulecnt += 1 lastrule = None out.write("\n") - out.write(f"#define RULECNT {rulecnt}\n") + 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") with open("maps.h", "w") as out: for idx, limit in enumerate(v4persrcratelimits): - out.write(f"V4_SRC_RATE_DEFINE({idx}, {limit})\n") + 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"V6_SRC_RATE_DEFINE({idx}, {limit})\n") + out.write(f"SRC_RATE_DEFINE(6, {idx}, {limit})\n")