X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=genrules.py;h=543f7c33f200cc81c7e5050fd577e40936a8ead2;hb=1be9ba6c0ac85e0ea18d944f67ce4e5598d08660;hp=300900a55b15f32e204c6628454e0e9b2227ba8d;hpb=c5f8e7b221515ce043779456945d45a7098d9d9e;p=flowspec-xdp diff --git a/genrules.py b/genrules.py index 300900a..543f7c3 100755 --- a/genrules.py +++ b/genrules.py @@ -290,6 +290,8 @@ with open("rules.h", "w") as out: use_v6_frags = False rulecnt = 0 ratelimitcnt = 0 + v4persrcratelimitcnt = 0 + v6persrcratelimitcnt = 0 lastrule = None for line in sys.stdin.readlines(): @@ -369,40 +371,89 @@ with open("rules.h", "w") as out: if len(blocks[1].strip()) != 10: # Should be 0x12345678 continue ty = blocks[1].strip()[:6] + high_byte = int(blocks[1].strip()[8:], 16) low_bytes = int(blocks[2].strip(") \n"), 16) - if ty == "0x8006": + if ty == "0x8006" or ty == "0x800c" or ty == "0x8306" or ty == "0x830c": if first_action is not None: - assert False # Two ratelimit actions? + # 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: - if low_bytes & (1 << 31) != 0: - assert False # Negative ratelimit? - exp = (low_bytes & (0xff << 23)) >> 23 - if exp == 0xff: - assert False # NaN/INF? - if exp <= 127: # < 1 - first_action = "return XDP_DROP;" - if exp >= 127 + 63: # The count won't even fit in 64-bits, just accept - first_action = "return XDP_PASS;" mantissa = low_bytes & ((1 << 23) - 1) value = 1.0 + mantissa / (2**23) value *= 2**(exp-127) - first_action = "uint64_t secs = bpf_ktime_get_ns() / 1000000000;\n" - first_action += f"const uint32_t ratelimitidx = {ratelimitcnt};\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 += "\tif (secs != rate->bucket_secs) {\n" - first_action += "\t\trate->bucket_secs = secs;\n" - first_action += "\t\trate->bucket_count = 0;\n" - first_action += "\t}\n" - first_action += f"\tif (rate->bucket_count + (data_end - pktdata) > {math.floor(value)})\n" - first_action += "\t\t{ bpf_spin_unlock(&rate->lock); return XDP_DROP; }\n" - first_action += "\trate->bucket_count += data_end - pktdata;\n" - first_action += "\tbpf_spin_unlock(&rate->lock);\n" - first_action += "}\n" - ratelimitcnt += 1 + if ty == "0x8006" or ty == "0x8306": + 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 += "uint64_t allowed_since_last = 0;\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 per-CPU */" + spin_unlock = "/* No locking as we're per-CPU */" + if proto == 4: + if high_byte > 32: + continue + first_action += f"const uint32_t srcip = ip->saddr & MASK4({high_byte});\n" + first_action += f"void *rate_map = &v4_src_rate_{v4persrcratelimitcnt};\n" + v4persrcratelimitcnt += 1 + else: + if high_byte > 128: + continue + first_action += f"const uint128_t srcip = ip6->saddr & MASK6({high_byte});\n" + first_action += f"void *rate_map = &v6_src_rate_{v6persrcratelimitcnt};\n" + v6persrcratelimitcnt += 1 + 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 += 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" or ty == "0x8306": + 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 += f"\t\t{spin_unlock}\n" + first_action += "\t} else {\n" + first_action += f"\t\t{spin_unlock}\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\t{accessor} = data_end - pktdata;\n" + else: + first_action += f"\t\t{accessor} = 1;\n" + first_action += "\tbpf_map_update_elem(rate_map, &srcip, rate, BPF_ANY);\n" + first_action += "}\n" elif ty == "0x8007": if low_bytes & 1 == 0: last_action = "return XDP_PASS;" @@ -419,7 +470,8 @@ with open("rules.h", "w") as out: 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 < 0)) { chk += 65534; }") + 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) + ";") @@ -439,6 +491,10 @@ with open("rules.h", "w") as out: out.write(f"#define RULECNT {rulecnt}\n") if ratelimitcnt != 0: out.write(f"#define RATE_CNT {ratelimitcnt}\n") + if v4persrcratelimitcnt != 0: + out.write(f"#define V4_SRC_RATE_CNT {v4persrcratelimitcnt}\n") + if v6persrcratelimitcnt != 0: + out.write(f"#define V6_SRC_RATE_CNT {v6persrcratelimitcnt}\n") if rules4 != "": out.write("#define NEED_V4_PARSE\n") out.write("#define RULES4 {\\\n" + rules4 + "}\n")