diff --git a/libknet/threads_pmtud.c b/libknet/threads_pmtud.c index 75d51962..f4d15ae1 100644 --- a/libknet/threads_pmtud.c +++ b/libknet/threads_pmtud.c @@ -1,616 +1,623 @@ /* * Copyright (C) 2015-2019 Red Hat, Inc. All rights reserved. * * Authors: Fabio M. Di Nitto * Federico Simoncelli * * This software licensed under LGPL-2.0+ */ #include "config.h" #include #include #include #include #include "crypto.h" #include "links.h" #include "host.h" #include "logging.h" #include "transports.h" #include "threads_common.h" #include "threads_pmtud.h" static int _calculate_manual_mtu(knet_handle_t knet_h, struct knet_link *dst_link) { size_t ipproto_overhead_len; /* onwire packet overhead (protocol based) */ switch (dst_link->dst_addr.ss_family) { case AF_INET6: ipproto_overhead_len = KNET_PMTUD_OVERHEAD_V6 + dst_link->proto_overhead; break; case AF_INET: ipproto_overhead_len = KNET_PMTUD_OVERHEAD_V4 + dst_link->proto_overhead; break; default: log_debug(knet_h, KNET_SUB_PMTUD, "unknown protocol"); return 0; break; } dst_link->status.mtu = calc_max_data_outlen(knet_h, knet_h->manual_mtu - ipproto_overhead_len); return 1; } static int _handle_check_link_pmtud(knet_handle_t knet_h, struct knet_host *dst_host, struct knet_link *dst_link) { int err, ret, savederrno, mutex_retry_limit, failsafe, use_kernel_mtu, warn_once; uint32_t kernel_mtu; /* record kernel_mtu from EMSGSIZE */ size_t onwire_len; /* current packet onwire size */ size_t ipproto_overhead_len; /* onwire packet overhead (protocol based) */ size_t max_mtu_len; /* max mtu for protocol */ size_t data_len; /* how much data we can send in the packet * generally would be onwire_len - ipproto_overhead_len * needs to be adjusted for crypto */ size_t app_mtu_len; /* real data that we can send onwire */ ssize_t len; /* len of what we were able to sendto onwire */ struct timespec ts, pmtud_crypto_start_ts, pmtud_crypto_stop_ts; unsigned long long pong_timeout_adj_tmp, timediff; int pmtud_crypto_reduce = 1; unsigned char *outbuf = (unsigned char *)knet_h->pmtudbuf; warn_once = 0; mutex_retry_limit = 0; failsafe = 0; knet_h->pmtudbuf->khp_pmtud_link = dst_link->link_id; switch (dst_link->dst_addr.ss_family) { case AF_INET6: max_mtu_len = KNET_PMTUD_SIZE_V6; ipproto_overhead_len = KNET_PMTUD_OVERHEAD_V6 + dst_link->proto_overhead; break; case AF_INET: max_mtu_len = KNET_PMTUD_SIZE_V4; ipproto_overhead_len = KNET_PMTUD_OVERHEAD_V4 + dst_link->proto_overhead; break; default: log_debug(knet_h, KNET_SUB_PMTUD, "PMTUD aborted, unknown protocol"); return -1; break; } dst_link->last_bad_mtu = 0; dst_link->last_good_mtu = dst_link->last_ping_size + ipproto_overhead_len; /* * discovery starts from the top because kernel will * refuse to send packets > current iface mtu. * this saves us some time and network bw. */ onwire_len = max_mtu_len; restart: /* * prevent a race when interface mtu is changed _exactly_ during * the discovery process and it's complex to detect. Easier * to wait the next loop. * 30 is not an arbitrary value. To bisect from 576 to 128000 doesn't * take more than 18/19 steps. */ if (failsafe == 30) { log_err(knet_h, KNET_SUB_PMTUD, "Aborting PMTUD process: Too many attempts. MTU might have changed during discovery."); return -1; } else { failsafe++; } /* * common to all packets */ /* * calculate the application MTU based on current onwire_len minus ipproto_overhead_len */ app_mtu_len = calc_max_data_outlen(knet_h, onwire_len - ipproto_overhead_len); /* * recalculate onwire len back that might be different based * on data padding from crypto layer. */ onwire_len = calc_data_outlen(knet_h, app_mtu_len + KNET_HEADER_ALL_SIZE) + ipproto_overhead_len; /* * calculate the size of what we need to send to sendto(2). * see also onwire.c for packet format explanation. */ data_len = app_mtu_len + knet_h->sec_hash_size + knet_h->sec_salt_size + KNET_HEADER_ALL_SIZE; if (knet_h->crypto_instance) { if (data_len < (knet_h->sec_hash_size + knet_h->sec_salt_size) + 1) { log_debug(knet_h, KNET_SUB_PMTUD, "Aborting PMTUD process: link mtu smaller than crypto header detected (link might have been disconnected)"); return -1; } knet_h->pmtudbuf->khp_pmtud_size = onwire_len; if (crypto_encrypt_and_sign(knet_h, (const unsigned char *)knet_h->pmtudbuf, data_len - (knet_h->sec_hash_size + knet_h->sec_salt_size), knet_h->pmtudbuf_crypt, (ssize_t *)&data_len) < 0) { log_debug(knet_h, KNET_SUB_PMTUD, "Unable to crypto pmtud packet"); return -1; } outbuf = knet_h->pmtudbuf_crypt; knet_h->stats_extra.tx_crypt_pmtu_packets++; } else { knet_h->pmtudbuf->khp_pmtud_size = onwire_len; } /* link has gone down, aborting pmtud */ if (dst_link->status.connected != 1) { log_debug(knet_h, KNET_SUB_PMTUD, "PMTUD detected host (%u) link (%u) has been disconnected", dst_host->host_id, dst_link->link_id); return -1; } if (dst_link->transport_connected != 1) { log_debug(knet_h, KNET_SUB_PMTUD, "PMTUD detected host (%u) link (%u) has been disconnected", dst_host->host_id, dst_link->link_id); return -1; } if (pthread_mutex_lock(&knet_h->pmtud_mutex) != 0) { log_debug(knet_h, KNET_SUB_PMTUD, "Unable to get mutex lock"); return -1; } if (knet_h->pmtud_abort) { pthread_mutex_unlock(&knet_h->pmtud_mutex); errno = EDEADLK; return -1; } savederrno = pthread_mutex_lock(&knet_h->tx_mutex); if (savederrno) { log_err(knet_h, KNET_SUB_PMTUD, "Unable to get TX mutex lock: %s", strerror(savederrno)); return -1; } retry: if (transport_get_connection_oriented(knet_h, dst_link->transport) == TRANSPORT_PROTO_NOT_CONNECTION_ORIENTED) { len = sendto(dst_link->outsock, outbuf, data_len, MSG_DONTWAIT | MSG_NOSIGNAL, (struct sockaddr *) &dst_link->dst_addr, sizeof(struct sockaddr_storage)); } else { len = sendto(dst_link->outsock, outbuf, data_len, MSG_DONTWAIT | MSG_NOSIGNAL, NULL, 0); } savederrno = errno; /* * we cannot hold a lock on kmtu_mutex between resetting * knet_h->kernel_mtu here and below where it's used. * use_kernel_mtu tells us if the knet_h->kernel_mtu was * set to 0 and we can trust its value later. */ use_kernel_mtu = 0; if (pthread_mutex_lock(&knet_h->kmtu_mutex) == 0) { use_kernel_mtu = 1; knet_h->kernel_mtu = 0; pthread_mutex_unlock(&knet_h->kmtu_mutex); } kernel_mtu = 0; err = transport_tx_sock_error(knet_h, dst_link->transport, dst_link->outsock, len, savederrno); switch(err) { case -1: /* unrecoverable error */ log_debug(knet_h, KNET_SUB_PMTUD, "Unable to send pmtu packet (sendto): %d %s", savederrno, strerror(savederrno)); pthread_mutex_unlock(&knet_h->tx_mutex); pthread_mutex_unlock(&knet_h->pmtud_mutex); dst_link->status.stats.tx_pmtu_errors++; return -1; case 0: /* ignore error and continue */ break; case 1: /* retry to send those same data */ dst_link->status.stats.tx_pmtu_retries++; goto retry; break; } pthread_mutex_unlock(&knet_h->tx_mutex); if (len != (ssize_t )data_len) { if (savederrno == EMSGSIZE) { /* * we cannot hold a lock on kmtu_mutex between resetting * knet_h->kernel_mtu and here. * use_kernel_mtu tells us if the knet_h->kernel_mtu was * set to 0 previously and we can trust its value now. */ if (use_kernel_mtu) { use_kernel_mtu = 0; if (pthread_mutex_lock(&knet_h->kmtu_mutex) == 0) { kernel_mtu = knet_h->kernel_mtu; pthread_mutex_unlock(&knet_h->kmtu_mutex); } } if (kernel_mtu > 0) { dst_link->last_bad_mtu = kernel_mtu + 1; } else { dst_link->last_bad_mtu = onwire_len; } } else { log_debug(knet_h, KNET_SUB_PMTUD, "Unable to send pmtu packet len: %zu err: %s", onwire_len, strerror(savederrno)); } } else { dst_link->last_sent_mtu = onwire_len; dst_link->last_recv_mtu = 0; dst_link->status.stats.tx_pmtu_packets++; dst_link->status.stats.tx_pmtu_bytes += data_len; if (clock_gettime(CLOCK_REALTIME, &ts) < 0) { log_debug(knet_h, KNET_SUB_PMTUD, "Unable to get current time: %s", strerror(errno)); pthread_mutex_unlock(&knet_h->pmtud_mutex); return -1; } /* * non fatal, we can wait the next round to reduce the * multiplier */ if (clock_gettime(CLOCK_MONOTONIC, &pmtud_crypto_start_ts) < 0) { log_debug(knet_h, KNET_SUB_PMTUD, "Unable to get current time: %s", strerror(errno)); pmtud_crypto_reduce = 0; } /* * set PMTUd reply timeout to match pong_timeout on a given link * * math: internally pong_timeout is expressed in microseconds, while * the public API exports milliseconds. So careful with the 0's here. * the loop is necessary because we are grabbing the current time just above * and add values to it that could overflow into seconds. */ if (pthread_mutex_lock(&knet_h->backoff_mutex)) { log_debug(knet_h, KNET_SUB_PMTUD, "Unable to get backoff_mutex"); pthread_mutex_unlock(&knet_h->pmtud_mutex); return -1; } if (knet_h->crypto_instance) { /* * crypto, under pressure, is a royal PITA */ pong_timeout_adj_tmp = dst_link->pong_timeout_adj * dst_link->pmtud_crypto_timeout_multiplier; } else { pong_timeout_adj_tmp = dst_link->pong_timeout_adj; } ts.tv_sec += pong_timeout_adj_tmp / 1000000; ts.tv_nsec += (((pong_timeout_adj_tmp) % 1000000) * 1000); while (ts.tv_nsec > 1000000000) { ts.tv_sec += 1; ts.tv_nsec -= 1000000000; } pthread_mutex_unlock(&knet_h->backoff_mutex); knet_h->pmtud_waiting = 1; ret = pthread_cond_timedwait(&knet_h->pmtud_cond, &knet_h->pmtud_mutex, &ts); knet_h->pmtud_waiting = 0; if (knet_h->pmtud_abort) { pthread_mutex_unlock(&knet_h->pmtud_mutex); errno = EDEADLK; return -1; } /* * we cannot use shutdown_in_progress in here because * we already hold the read lock */ if (knet_h->fini_in_progress) { pthread_mutex_unlock(&knet_h->pmtud_mutex); log_debug(knet_h, KNET_SUB_PMTUD, "PMTUD aborted. shutdown in progress"); return -1; } if (ret) { if (ret == ETIMEDOUT) { if ((knet_h->crypto_instance) && (dst_link->pmtud_crypto_timeout_multiplier < KNET_LINK_PMTUD_CRYPTO_TIMEOUT_MULTIPLIER_MAX)) { dst_link->pmtud_crypto_timeout_multiplier = dst_link->pmtud_crypto_timeout_multiplier * 2; pmtud_crypto_reduce = 0; log_debug(knet_h, KNET_SUB_PMTUD, "Increasing PMTUd response timeout multiplier to (%u) for host %u link: %u", dst_link->pmtud_crypto_timeout_multiplier, dst_host->host_id, dst_link->link_id); pthread_mutex_unlock(&knet_h->pmtud_mutex); goto restart; } if (!warn_once) { log_warn(knet_h, KNET_SUB_PMTUD, "possible MTU misconfiguration detected. " "kernel is reporting MTU: %u bytes for " "host %u link %u but the other node is " "not acknowledging packets of this size. ", dst_link->last_sent_mtu, dst_host->host_id, dst_link->link_id); log_warn(knet_h, KNET_SUB_PMTUD, "This can be caused by this node interface MTU " "too big or a network device that does not " "support or has been misconfigured to manage MTU " "of this size, or packet loss. knet will continue " "to run but performances might be affected."); warn_once = 1; } } else { pthread_mutex_unlock(&knet_h->pmtud_mutex); if (mutex_retry_limit == 3) { log_debug(knet_h, KNET_SUB_PMTUD, "PMTUD aborted, unable to get mutex lock"); return -1; } mutex_retry_limit++; goto restart; } } if ((knet_h->crypto_instance) && (pmtud_crypto_reduce == 1) && (dst_link->pmtud_crypto_timeout_multiplier > KNET_LINK_PMTUD_CRYPTO_TIMEOUT_MULTIPLIER_MIN)) { if (!clock_gettime(CLOCK_MONOTONIC, &pmtud_crypto_stop_ts)) { timespec_diff(pmtud_crypto_start_ts, pmtud_crypto_stop_ts, &timediff); if (((pong_timeout_adj_tmp * 1000) / 2) > timediff) { dst_link->pmtud_crypto_timeout_multiplier = dst_link->pmtud_crypto_timeout_multiplier / 2; log_debug(knet_h, KNET_SUB_PMTUD, "Decreasing PMTUd response timeout multiplier to (%u) for host %u link: %u", dst_link->pmtud_crypto_timeout_multiplier, dst_host->host_id, dst_link->link_id); } } else { log_debug(knet_h, KNET_SUB_PMTUD, "Unable to get current time: %s", strerror(errno)); } } if ((dst_link->last_recv_mtu != onwire_len) || (ret)) { dst_link->last_bad_mtu = onwire_len; } else { int found_mtu = 0; if (knet_h->sec_block_size) { if ((onwire_len + knet_h->sec_block_size >= max_mtu_len) || ((dst_link->last_bad_mtu) && (dst_link->last_bad_mtu <= (onwire_len + knet_h->sec_block_size)))) { found_mtu = 1; } } else { if ((onwire_len == max_mtu_len) || ((dst_link->last_bad_mtu) && (dst_link->last_bad_mtu == (onwire_len + 1))) || (dst_link->last_bad_mtu == dst_link->last_good_mtu)) { found_mtu = 1; } } if (found_mtu) { /* * account for IP overhead, knet headers and crypto in PMTU calculation */ dst_link->status.mtu = calc_max_data_outlen(knet_h, onwire_len - ipproto_overhead_len); pthread_mutex_unlock(&knet_h->pmtud_mutex); return 0; } dst_link->last_good_mtu = onwire_len; } } if (kernel_mtu) { onwire_len = kernel_mtu; } else { onwire_len = (dst_link->last_good_mtu + dst_link->last_bad_mtu) / 2; } pthread_mutex_unlock(&knet_h->pmtud_mutex); goto restart; } static int _handle_check_pmtud(knet_handle_t knet_h, struct knet_host *dst_host, struct knet_link *dst_link, int force_run) { uint8_t saved_valid_pmtud; unsigned int saved_pmtud; struct timespec clock_now; unsigned long long diff_pmtud, interval; if (clock_gettime(CLOCK_MONOTONIC, &clock_now) != 0) { log_debug(knet_h, KNET_SUB_PMTUD, "Unable to get monotonic clock"); return 0; } if (!force_run) { interval = knet_h->pmtud_interval * 1000000000llu; /* nanoseconds */ timespec_diff(dst_link->pmtud_last, clock_now, &diff_pmtud); if (diff_pmtud < interval) { return dst_link->has_valid_mtu; } } /* * status.proto_overhead should include all IP/(UDP|SCTP)/knet headers * * please note that it is not the same as link->proto_overhead that * includes only either UDP or SCTP (at the moment) overhead. */ switch (dst_link->dst_addr.ss_family) { case AF_INET6: dst_link->status.proto_overhead = KNET_PMTUD_OVERHEAD_V6 + dst_link->proto_overhead + KNET_HEADER_ALL_SIZE + knet_h->sec_hash_size + knet_h->sec_salt_size; break; case AF_INET: dst_link->status.proto_overhead = KNET_PMTUD_OVERHEAD_V4 + dst_link->proto_overhead + KNET_HEADER_ALL_SIZE + knet_h->sec_hash_size + knet_h->sec_salt_size; break; } saved_pmtud = dst_link->status.mtu; saved_valid_pmtud = dst_link->has_valid_mtu; log_debug(knet_h, KNET_SUB_PMTUD, "Starting PMTUD for host: %u link: %u", dst_host->host_id, dst_link->link_id); errno = 0; if (_handle_check_link_pmtud(knet_h, dst_host, dst_link) < 0) { if (errno == EDEADLK) { log_debug(knet_h, KNET_SUB_PMTUD, "PMTUD for host: %u link: %u has been rescheduled", dst_host->host_id, dst_link->link_id); dst_link->status.mtu = saved_pmtud; dst_link->has_valid_mtu = saved_valid_pmtud; errno = EDEADLK; return dst_link->has_valid_mtu; } dst_link->has_valid_mtu = 0; } else { - dst_link->has_valid_mtu = 1; + if (dst_link->status.mtu < calc_min_mtu(knet_h)) { + log_info(knet_h, KNET_SUB_PMTUD, + "Invalid MTU detected for host: %u link: %u mtu: %u", + dst_host->host_id, dst_link->link_id, dst_link->status.mtu); + dst_link->has_valid_mtu = 0; + } else { + dst_link->has_valid_mtu = 1; + } if (dst_link->has_valid_mtu) { if ((saved_pmtud) && (saved_pmtud != dst_link->status.mtu)) { log_info(knet_h, KNET_SUB_PMTUD, "PMTUD link change for host: %u link: %u from %u to %u", dst_host->host_id, dst_link->link_id, saved_pmtud, dst_link->status.mtu); } log_debug(knet_h, KNET_SUB_PMTUD, "PMTUD completed for host: %u link: %u current link mtu: %u", dst_host->host_id, dst_link->link_id, dst_link->status.mtu); /* * set pmtud_last, if we can, after we are done with the PMTUd process * because it can take a very long time. */ dst_link->pmtud_last = clock_now; if (!clock_gettime(CLOCK_MONOTONIC, &clock_now)) { dst_link->pmtud_last = clock_now; } } } if (saved_valid_pmtud != dst_link->has_valid_mtu) { _host_dstcache_update_async(knet_h, dst_host); } return dst_link->has_valid_mtu; } void *_handle_pmtud_link_thread(void *data) { knet_handle_t knet_h = (knet_handle_t) data; struct knet_host *dst_host; struct knet_link *dst_link; int link_idx; unsigned int have_mtu; unsigned int lower_mtu; int link_has_mtu; int force_run = 0; set_thread_status(knet_h, KNET_THREAD_PMTUD, KNET_THREAD_STARTED); knet_h->data_mtu = calc_min_mtu(knet_h); /* preparing pmtu buffer */ knet_h->pmtudbuf->kh_version = KNET_HEADER_VERSION; knet_h->pmtudbuf->kh_type = KNET_HEADER_TYPE_PMTUD; knet_h->pmtudbuf->kh_node = htons(knet_h->host_id); while (!shutdown_in_progress(knet_h)) { usleep(KNET_THREADS_TIMERES); if (pthread_mutex_lock(&knet_h->pmtud_mutex) != 0) { log_debug(knet_h, KNET_SUB_PMTUD, "Unable to get mutex lock"); continue; } knet_h->pmtud_abort = 0; knet_h->pmtud_running = 1; force_run = knet_h->pmtud_forcerun; knet_h->pmtud_forcerun = 0; pthread_mutex_unlock(&knet_h->pmtud_mutex); if (force_run) { log_debug(knet_h, KNET_SUB_PMTUD, "PMTUd request to rerun has been received"); } if (pthread_rwlock_rdlock(&knet_h->global_rwlock) != 0) { log_debug(knet_h, KNET_SUB_PMTUD, "Unable to get read lock"); continue; } lower_mtu = KNET_PMTUD_SIZE_V4; have_mtu = 0; for (dst_host = knet_h->host_head; dst_host != NULL; dst_host = dst_host->next) { for (link_idx = 0; link_idx < KNET_MAX_LINK; link_idx++) { dst_link = &dst_host->link[link_idx]; if ((dst_link->status.enabled != 1) || (dst_link->status.connected != 1) || (dst_host->link[link_idx].transport == KNET_TRANSPORT_LOOPBACK) || (!dst_link->last_ping_size) || ((dst_link->dynamic == KNET_LINK_DYNIP) && (dst_link->status.dynconnected != 1))) continue; if (!knet_h->manual_mtu) { link_has_mtu = _handle_check_pmtud(knet_h, dst_host, dst_link, force_run); if (errno == EDEADLK) { goto out_unlock; } if (link_has_mtu) { have_mtu = 1; if (dst_link->status.mtu < lower_mtu) { lower_mtu = dst_link->status.mtu; } } } else { link_has_mtu = _calculate_manual_mtu(knet_h, dst_link); if (link_has_mtu) { have_mtu = 1; if (dst_link->status.mtu < lower_mtu) { lower_mtu = dst_link->status.mtu; } } } } } if (have_mtu) { if (knet_h->data_mtu != lower_mtu) { knet_h->data_mtu = lower_mtu; log_info(knet_h, KNET_SUB_PMTUD, "Global data MTU changed to: %u", knet_h->data_mtu); if (knet_h->pmtud_notify_fn) { knet_h->pmtud_notify_fn(knet_h->pmtud_notify_fn_private_data, knet_h->data_mtu); } } } out_unlock: pthread_rwlock_unlock(&knet_h->global_rwlock); if (pthread_mutex_lock(&knet_h->pmtud_mutex) != 0) { log_debug(knet_h, KNET_SUB_PMTUD, "Unable to get mutex lock"); } else { knet_h->pmtud_running = 0; pthread_mutex_unlock(&knet_h->pmtud_mutex); } } set_thread_status(knet_h, KNET_THREAD_PMTUD, KNET_THREAD_STOPPED); return NULL; }