/*
* Copyright (C) 2015-2020 Red Hat, Inc. All rights reserved.
*
* Authors: Fabio M. Di Nitto <fabbione@kronosnet.org>
* Federico Simoncelli <fsimon@kronosnet.org>
*
* This software licensed under LGPL-2.0+
*/
#include "config.h"
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <pthread.h>
#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;
if (pthread_mutex_lock(&knet_h->handle_stats_mutex) < 0) {
log_err(knet_h, KNET_SUB_PMTUD, "Unable to get mutex lock");
return -1;
}
knet_h->stats_extra.tx_crypt_pmtu_packets++;
pthread_mutex_unlock(&knet_h->handle_stats_mutex);
} 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) {
pthread_mutex_unlock(&knet_h->pmtud_mutex);
log_err(knet_h, KNET_SUB_PMTUD, "Unable to get TX mutex lock: %s", strerror(savederrno));
return -1;
}
savederrno = pthread_mutex_lock(&dst_link->link_stats_mutex);
if (savederrno) {
pthread_mutex_unlock(&knet_h->pmtud_mutex);
pthread_mutex_unlock(&knet_h->tx_mutex);
log_err(knet_h, KNET_SUB_PMTUD, "Unable to get stats mutex lock for host %u link %u: %s",
dst_host->host_id, dst_link->link_id, 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++;
pthread_mutex_unlock(&dst_link->link_stats_mutex);
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) {
pthread_mutex_unlock(&dst_link->link_stats_mutex);
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;
pthread_mutex_unlock(&dst_link->link_stats_mutex);
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 {
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;
}