From: wenxu <[email protected]> In case almost or all available ports are taken, clash resolution can take a very long time, resulting in pmd hang in conntrack.
This can happen when many to-be-natted hosts connect to same destination:port (e.g. a proxy) and all connections pass the same SNAT. Pick a random offset in the acceptable range, then try ever smaller number of adjacent port numbers, until either the limit is reached or a useable port was found. This results in at most 248 attempts (128 + 64 + 32 + 16 + 8, i.e. 4 restarts with new search offset) instead of 64000+. And if thenumber of ip address will limit the max attempts and which will lead the total attempts under 248. Signed-off-by: wenxu <[email protected]> --- lib/conntrack.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 63 insertions(+), 8 deletions(-) diff --git a/lib/conntrack.c b/lib/conntrack.c index dc29c9b..248cd45 100644 --- a/lib/conntrack.c +++ b/lib/conntrack.c @@ -2400,19 +2400,50 @@ next_addr_in_range_guarded(union ct_addr *curr, union ct_addr *min, static bool nat_get_unique_l4(struct conntrack *ct, struct conn *nat_conn, ovs_be16 *port, uint16_t curr, uint16_t min, - uint16_t max) + uint16_t max, unsigned int attempts) { + unsigned int i = 0; + FOR_EACH_PORT_IN_RANGE(curr, min, max) { - *port = htons(curr); - if (!conn_lookup(ct, &nat_conn->rev_key, - time_msec(), NULL, NULL)) { - return true; + if (i++ < attempts) { + *port = htons(curr); + if (!conn_lookup(ct, &nat_conn->rev_key, + time_msec(), NULL, NULL)) { + return true; + } + } else { + break; } } return false; } +static void +nat_get_attempts_range(union ct_addr *min_addr, union ct_addr *max_addr, + uint16_t dl_type, unsigned int *max_attempts, + unsigned int *min_attempts) +{ + uint32_t range_addr; + + if (dl_type == htons(ETH_TYPE_IP)) { + range_addr = ntohl(max_addr->ipv4) - ntohl(min_addr->ipv4) + 1; + } else { + range_addr = nat_ipv6_addrs_delta(&min_addr->ipv6, + &max_addr->ipv6) + 1; + } + + *max_attempts = 128 / range_addr; + if (*max_attempts < 1) { + *max_attempts = 1; + } + + *min_attempts = 16 / range_addr; + if (*min_attempts < 2) { + *min_attempts = 2; + } +} + /* This function tries to get a unique tuple. * Every iteration checks that the reverse tuple doesn't * collide with any existing one. @@ -2446,6 +2477,9 @@ nat_get_unique_tuple(struct conntrack *ct, const struct conn *conn, uint16_t min_dport, max_dport, curr_dport, orig_dport; bool pat_proto = conn->key.nw_proto == IPPROTO_TCP || conn->key.nw_proto == IPPROTO_UDP; + unsigned int attempts, max_attempts, min_attempts; + uint16_t range_src, range_dst, range_max; + bool found; min_addr = nat_info->min_addr; max_addr = nat_info->max_addr; @@ -2462,6 +2496,13 @@ nat_get_unique_tuple(struct conntrack *ct, const struct conn *conn, set_dport_range(nat_info, &conn->key, hash, &orig_dport, &min_dport, &max_dport); + range_src = max_sport - min_sport + 1; + range_dst = max_dport - min_dport + 1; + range_max = range_src > range_dst ? range_src : range_dst; + + nat_get_attempts_range(&min_addr, &max_addr, conn->key.dl_type, + &max_attempts, &min_attempts); + another_round: store_addr_to_key(&curr_addr, &nat_conn->rev_key, nat_info->nat_action); @@ -2481,10 +2522,16 @@ another_round: nat_conn->rev_key.src.port = htons(curr_dport); nat_conn->rev_key.dst.port = htons(curr_sport); - bool found = false; + attempts = range_max; + if (attempts > max_attempts) { + attempts = max_attempts; + } + +another_port_round: + found = false; if (nat_info->nat_action & NAT_ACTION_DST_PORT) { found = nat_get_unique_l4(ct, nat_conn, &nat_conn->rev_key.src.port, - curr_dport, min_dport, max_dport); + curr_dport, min_dport, max_dport, attempts); if (!found) { nat_conn->rev_key.src.port = htons(orig_dport); } @@ -2492,13 +2539,21 @@ another_round: if (!found) { found = nat_get_unique_l4(ct, nat_conn, &nat_conn->rev_key.dst.port, - curr_sport, min_sport, max_sport); + curr_sport, min_sport, max_sport, attempts); } if (found) { return true; } + if (attempts < range_max && attempts >= min_attempts) { + attempts /= 2; + curr_dport = min_dport + (random_uint32() % range_dst); + curr_sport = min_sport + (random_uint32() % range_src); + + goto another_port_round; + } + /* Check if next IP is in range and respin. Otherwise, notify * exhaustion to the caller. */ next_addr: -- 1.8.3.1 _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
