diff options
Diffstat (limited to 'src/event/quic/ngx_event_quic_migration.c')
| -rw-r--r-- | src/event/quic/ngx_event_quic_migration.c | 671 |
1 files changed, 671 insertions, 0 deletions
diff --git a/src/event/quic/ngx_event_quic_migration.c b/src/event/quic/ngx_event_quic_migration.c new file mode 100644 index 000000000..37c7b8675 --- /dev/null +++ b/src/event/quic/ngx_event_quic_migration.c @@ -0,0 +1,671 @@ + +/* + * Copyright (C) Nginx, Inc. + */ + + +#include <ngx_config.h> +#include <ngx_core.h> +#include <ngx_event.h> +#include <ngx_event_quic_connection.h> + + +static void ngx_quic_set_connection_path(ngx_connection_t *c, + ngx_quic_path_t *path); +static ngx_int_t ngx_quic_validate_path(ngx_connection_t *c, + ngx_quic_path_t *path); +static ngx_int_t ngx_quic_send_path_challenge(ngx_connection_t *c, + ngx_quic_path_t *path); +static ngx_quic_path_t *ngx_quic_get_path(ngx_connection_t *c, ngx_uint_t tag); + + +ngx_int_t +ngx_quic_handle_path_challenge_frame(ngx_connection_t *c, + ngx_quic_header_t *pkt, ngx_quic_path_challenge_frame_t *f) +{ + ngx_quic_frame_t frame, *fp; + ngx_quic_connection_t *qc; + + qc = ngx_quic_get_connection(c); + + ngx_memzero(&frame, sizeof(ngx_quic_frame_t)); + + frame.level = ssl_encryption_application; + frame.type = NGX_QUIC_FT_PATH_RESPONSE; + frame.u.path_response = *f; + + /* + * RFC 9000, 8.2.2. Path Validation Responses + * + * A PATH_RESPONSE frame MUST be sent on the network path where the + * PATH_CHALLENGE frame was received. + */ + + /* + * An endpoint MUST expand datagrams that contain a PATH_RESPONSE frame + * to at least the smallest allowed maximum datagram size of 1200 bytes. + */ + if (ngx_quic_frame_sendto(c, &frame, 1200, pkt->path) != NGX_OK) { + return NGX_ERROR; + } + + if (pkt->path == qc->path) { + /* + * RFC 9000, 9.3.3. Off-Path Packet Forwarding + * + * An endpoint that receives a PATH_CHALLENGE on an active path SHOULD + * send a non-probing packet in response. + */ + + fp = ngx_quic_alloc_frame(c); + if (fp == NULL) { + return NGX_ERROR; + } + + fp->level = ssl_encryption_application; + fp->type = NGX_QUIC_FT_PING; + + ngx_quic_queue_frame(qc, fp); + } + + return NGX_OK; +} + + +ngx_int_t +ngx_quic_handle_path_response_frame(ngx_connection_t *c, + ngx_quic_path_challenge_frame_t *f) +{ + ngx_uint_t rst; + ngx_queue_t *q; + ngx_quic_path_t *path, *prev; + ngx_quic_connection_t *qc; + + qc = ngx_quic_get_connection(c); + + /* + * RFC 9000, 8.2.3. Successful Path Validation + * + * A PATH_RESPONSE frame received on any network path validates the path + * on which the PATH_CHALLENGE was sent. + */ + + for (q = ngx_queue_head(&qc->paths); + q != ngx_queue_sentinel(&qc->paths); + q = ngx_queue_next(q)) + { + path = ngx_queue_data(q, ngx_quic_path_t, queue); + + if (!path->validating) { + continue; + } + + if (ngx_memcmp(path->challenge1, f->data, sizeof(f->data)) == 0 + || ngx_memcmp(path->challenge2, f->data, sizeof(f->data)) == 0) + { + goto valid; + } + } + + ngx_log_debug0(NGX_LOG_DEBUG_EVENT, c->log, 0, + "quic stale PATH_RESPONSE ignored"); + + return NGX_OK; + +valid: + + /* + * RFC 9000, 9.4. Loss Detection and Congestion Control + * + * On confirming a peer's ownership of its new address, + * an endpoint MUST immediately reset the congestion controller + * and round-trip time estimator for the new path to initial values + * unless the only change in the peer's address is its port number. + */ + + rst = 1; + + prev = ngx_quic_get_path(c, NGX_QUIC_PATH_BACKUP); + + if (prev != NULL) { + + if (ngx_cmp_sockaddr(prev->sockaddr, prev->socklen, + path->sockaddr, path->socklen, 0) + == NGX_OK) + { + /* address did not change */ + rst = 0; + } + } + + if (rst) { + ngx_memzero(&qc->congestion, sizeof(ngx_quic_congestion_t)); + + qc->congestion.window = ngx_min(10 * qc->tp.max_udp_payload_size, + ngx_max(2 * qc->tp.max_udp_payload_size, + 14720)); + qc->congestion.ssthresh = (size_t) -1; + qc->congestion.recovery_start = ngx_current_msec; + } + + /* + * RFC 9000, 9.3. Responding to Connection Migration + * + * After verifying a new client address, the server SHOULD + * send new address validation tokens (Section 8) to the client. + */ + + if (ngx_quic_send_new_token(c, path) != NGX_OK) { + return NGX_ERROR; + } + + ngx_log_error(NGX_LOG_INFO, c->log, 0, + "quic path seq:%uL addr:%V successfully validated", + path->seqnum, &path->addr_text); + + ngx_quic_path_dbg(c, "is validated", path); + + path->validated = 1; + path->validating = 0; + path->limited = 0; + + return NGX_OK; +} + + +ngx_quic_path_t * +ngx_quic_new_path(ngx_connection_t *c, + struct sockaddr *sockaddr, socklen_t socklen, ngx_quic_client_id_t *cid) +{ + ngx_queue_t *q; + ngx_quic_path_t *path; + ngx_quic_connection_t *qc; + + qc = ngx_quic_get_connection(c); + + if (!ngx_queue_empty(&qc->free_paths)) { + + q = ngx_queue_head(&qc->free_paths); + path = ngx_queue_data(q, ngx_quic_path_t, queue); + + ngx_queue_remove(&path->queue); + + ngx_memzero(path, sizeof(ngx_quic_path_t)); + + } else { + + path = ngx_pcalloc(c->pool, sizeof(ngx_quic_path_t)); + if (path == NULL) { + return NULL; + } + } + + ngx_queue_insert_tail(&qc->paths, &path->queue); + + path->cid = cid; + cid->used = 1; + + path->limited = 1; + + path->seqnum = qc->path_seqnum++; + + path->sockaddr = &path->sa.sockaddr; + path->socklen = socklen; + ngx_memcpy(path->sockaddr, sockaddr, socklen); + + path->addr_text.data = path->text; + path->addr_text.len = ngx_sock_ntop(sockaddr, socklen, path->text, + NGX_SOCKADDR_STRLEN, 1); + + ngx_log_debug2(NGX_LOG_DEBUG_EVENT, c->log, 0, + "quic path seq:%uL created addr:%V", + path->seqnum, &path->addr_text); + return path; +} + + +static ngx_quic_path_t * +ngx_quic_get_path(ngx_connection_t *c, ngx_uint_t tag) +{ + ngx_queue_t *q; + ngx_quic_path_t *path; + ngx_quic_connection_t *qc; + + qc = ngx_quic_get_connection(c); + + for (q = ngx_queue_head(&qc->paths); + q != ngx_queue_sentinel(&qc->paths); + q = ngx_queue_next(q)) + { + path = ngx_queue_data(q, ngx_quic_path_t, queue); + + if (path->tag == tag) { + return path; + } + } + + return NULL; +} + + +ngx_int_t +ngx_quic_set_path(ngx_connection_t *c, ngx_quic_header_t *pkt) +{ + off_t len; + ngx_queue_t *q; + ngx_quic_path_t *path, *probe; + ngx_quic_socket_t *qsock; + ngx_quic_send_ctx_t *ctx; + ngx_quic_client_id_t *cid; + ngx_quic_connection_t *qc; + + qc = ngx_quic_get_connection(c); + qsock = ngx_quic_get_socket(c); + + len = pkt->raw->last - pkt->raw->start; + + if (c->udp->buffer == NULL) { + /* first ever packet in connection, path already exists */ + path = qc->path; + goto update; + } + + probe = NULL; + + for (q = ngx_queue_head(&qc->paths); + q != ngx_queue_sentinel(&qc->paths); + q = ngx_queue_next(q)) + { + path = ngx_queue_data(q, ngx_quic_path_t, queue); + + if (ngx_cmp_sockaddr(&qsock->sockaddr.sockaddr, qsock->socklen, + path->sockaddr, path->socklen, 1) + == NGX_OK) + { + goto update; + } + + if (path->tag == NGX_QUIC_PATH_PROBE) { + probe = path; + } + } + + /* packet from new path, drop current probe, if any */ + + ctx = ngx_quic_get_send_ctx(qc, pkt->level); + + /* + * only accept highest-numbered packets to prevent connection id + * exhaustion by excessive probing packets from unknown paths + */ + if (pkt->pn != ctx->largest_pn) { + return NGX_DONE; + } + + if (probe && ngx_quic_free_path(c, probe) != NGX_OK) { + return NGX_ERROR; + } + + /* new path requires new client id */ + cid = ngx_quic_next_client_id(c); + if (cid == NULL) { + ngx_log_error(NGX_LOG_INFO, c->log, 0, + "quic no available client ids for new path"); + /* stop processing of this datagram */ + return NGX_DONE; + } + + path = ngx_quic_new_path(c, &qsock->sockaddr.sockaddr, qsock->socklen, cid); + if (path == NULL) { + return NGX_ERROR; + } + + path->tag = NGX_QUIC_PATH_PROBE; + + /* + * client arrived using new path and previously seen DCID, + * this indicates NAT rebinding (or bad client) + */ + if (qsock->used) { + pkt->rebound = 1; + } + +update: + + qsock->used = 1; + pkt->path = path; + + /* TODO: this may be too late in some cases; + * for example, if error happens during decrypt(), we cannot + * send CC, if error happens in 1st packet, due to amplification + * limit, because path->received = 0 + * + * should we account garbage as received or only decrypting packets? + */ + path->received += len; + + ngx_log_debug3(NGX_LOG_DEBUG_EVENT, c->log, 0, + "quic packet len:%O via sock seq:%L path seq:%uL", + len, (int64_t) qsock->sid.seqnum, path->seqnum); + ngx_quic_path_dbg(c, "status", path); + + return NGX_OK; +} + + +ngx_int_t +ngx_quic_free_path(ngx_connection_t *c, ngx_quic_path_t *path) +{ + ngx_quic_connection_t *qc; + + qc = ngx_quic_get_connection(c); + + ngx_queue_remove(&path->queue); + ngx_queue_insert_head(&qc->free_paths, &path->queue); + + /* + * invalidate CID that is no longer usable for any other path; + * this also requests new CIDs from client + */ + if (path->cid) { + if (ngx_quic_free_client_id(c, path->cid) != NGX_OK) { + return NGX_ERROR; + } + } + + ngx_log_debug2(NGX_LOG_DEBUG_EVENT, c->log, 0, + "quic path seq:%uL addr:%V retired", + path->seqnum, &path->addr_text); + + return NGX_OK; +} + + +static void +ngx_quic_set_connection_path(ngx_connection_t *c, ngx_quic_path_t *path) +{ + size_t len; + + ngx_memcpy(c->sockaddr, path->sockaddr, path->socklen); + c->socklen = path->socklen; + + if (c->addr_text.data) { + len = ngx_min(c->addr_text.len, path->addr_text.len); + + ngx_memcpy(c->addr_text.data, path->addr_text.data, len); + c->addr_text.len = len; + } + + ngx_log_debug2(NGX_LOG_DEBUG_EVENT, c->log, 0, + "quic send path set to seq:%uL addr:%V", + path->seqnum, &path->addr_text); +} + + +ngx_int_t +ngx_quic_handle_migration(ngx_connection_t *c, ngx_quic_header_t *pkt) +{ + ngx_quic_path_t *next, *bkp; + ngx_quic_send_ctx_t *ctx; + ngx_quic_connection_t *qc; + + /* got non-probing packet via non-active path */ + + qc = ngx_quic_get_connection(c); + + ctx = ngx_quic_get_send_ctx(qc, pkt->level); + + /* + * RFC 9000, 9.3. Responding to Connection Migration + * + * An endpoint only changes the address to which it sends packets in + * response to the highest-numbered non-probing packet. + */ + if (pkt->pn != ctx->largest_pn) { + return NGX_OK; + } + + next = pkt->path; + + /* + * RFC 9000, 9.3.3: + * + * In response to an apparent migration, endpoints MUST validate the + * previously active path using a PATH_CHALLENGE frame. + */ + if (pkt->rebound) { + + /* NAT rebinding: client uses new path with old SID */ + if (ngx_quic_validate_path(c, qc->path) != NGX_OK) { + return NGX_ERROR; + } + } + + if (qc->path->validated) { + + if (next->tag != NGX_QUIC_PATH_BACKUP) { + /* can delete backup path, if any */ + bkp = ngx_quic_get_path(c, NGX_QUIC_PATH_BACKUP); + + if (bkp && ngx_quic_free_path(c, bkp) != NGX_OK) { + return NGX_ERROR; + } + } + + qc->path->tag = NGX_QUIC_PATH_BACKUP; + ngx_quic_path_dbg(c, "is now backup", qc->path); + + } else { + if (ngx_quic_free_path(c, qc->path) != NGX_OK) { + return NGX_ERROR; + } + } + + /* switch active path to migrated */ + qc->path = next; + qc->path->tag = NGX_QUIC_PATH_ACTIVE; + + ngx_quic_set_connection_path(c, next); + + if (!next->validated && !next->validating) { + if (ngx_quic_validate_path(c, next) != NGX_OK) { + return NGX_ERROR; + } + } + + ngx_log_error(NGX_LOG_INFO, c->log, 0, + "quic migrated to path seq:%uL addr:%V", + qc->path->seqnum, &qc->path->addr_text); + + ngx_quic_path_dbg(c, "is now active", qc->path); + + return NGX_OK; +} + + +static ngx_int_t +ngx_quic_validate_path(ngx_connection_t *c, ngx_quic_path_t *path) +{ + ngx_msec_t pto; + ngx_quic_send_ctx_t *ctx; + ngx_quic_connection_t *qc; + + qc = ngx_quic_get_connection(c); + + ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0, + "quic initiated validation of path seq:%uL", path->seqnum); + + path->validating = 1; + + if (RAND_bytes(path->challenge1, 8) != 1) { + return NGX_ERROR; + } + + if (RAND_bytes(path->challenge2, 8) != 1) { + return NGX_ERROR; + } + + if (ngx_quic_send_path_challenge(c, path) != NGX_OK) { + return NGX_ERROR; + } + + ctx = ngx_quic_get_send_ctx(qc, ssl_encryption_application); + pto = ngx_quic_pto(c, ctx); + + path->expires = ngx_current_msec + pto; + path->tries = NGX_QUIC_PATH_RETRIES; + + if (!qc->path_validation.timer_set) { + ngx_add_timer(&qc->path_validation, pto); + } + + return NGX_OK; +} + + +static ngx_int_t +ngx_quic_send_path_challenge(ngx_connection_t *c, ngx_quic_path_t *path) +{ + ngx_quic_frame_t frame; + + ngx_log_debug2(NGX_LOG_DEBUG_EVENT, c->log, 0, + "quic path seq:%uL send path_challenge tries:%ui", + path->seqnum, path->tries); + + ngx_memzero(&frame, sizeof(ngx_quic_frame_t)); + + frame.level = ssl_encryption_application; + frame.type = NGX_QUIC_FT_PATH_CHALLENGE; + + ngx_memcpy(frame.u.path_challenge.data, path->challenge1, 8); + + /* + * RFC 9000, 8.2.1. Initiating Path Validation + * + * An endpoint MUST expand datagrams that contain a PATH_CHALLENGE frame + * to at least the smallest allowed maximum datagram size of 1200 bytes, + * unless the anti-amplification limit for the path does not permit + * sending a datagram of this size. + */ + + /* same applies to PATH_RESPONSE frames */ + if (ngx_quic_frame_sendto(c, &frame, 1200, path) != NGX_OK) { + return NGX_ERROR; + } + + ngx_memcpy(frame.u.path_challenge.data, path->challenge2, 8); + + if (ngx_quic_frame_sendto(c, &frame, 1200, path) != NGX_OK) { + return NGX_ERROR; + } + + return NGX_OK; +} + + +void +ngx_quic_path_validation_handler(ngx_event_t *ev) +{ + ngx_msec_t now; + ngx_queue_t *q; + ngx_msec_int_t left, next, pto; + ngx_quic_path_t *path, *bkp; + ngx_connection_t *c; + ngx_quic_send_ctx_t *ctx; + ngx_quic_connection_t *qc; + + c = ev->data; + qc = ngx_quic_get_connection(c); + + ctx = ngx_quic_get_send_ctx(qc, ssl_encryption_application); + pto = ngx_quic_pto(c, ctx); + + next = -1; + now = ngx_current_msec; + + q = ngx_queue_head(&qc->paths); + + while (q != ngx_queue_sentinel(&qc->paths)) { + + path = ngx_queue_data(q, ngx_quic_path_t, queue); + q = ngx_queue_next(q); + + if (!path->validating) { + continue; + } + + left = path->expires - now; + + if (left > 0) { + + if (next == -1 || left < next) { + next = left; + } + + continue; + } + + if (--path->tries) { + path->expires = ngx_current_msec + pto; + + if (next == -1 || pto < next) { + next = pto; + } + + /* retransmit */ + (void) ngx_quic_send_path_challenge(c, path); + + continue; + } + + ngx_log_debug1(NGX_LOG_DEBUG_EVENT, ev->log, 0, + "quic path seq:%uL validation failed", path->seqnum); + + /* found expired path */ + + path->validated = 0; + path->validating = 0; + path->limited = 1; + + + /* RFC 9000, 9.3.2. On-Path Address Spoofing + * + * To protect the connection from failing due to such a spurious + * migration, an endpoint MUST revert to using the last validated + * peer address when validation of a new peer address fails. + */ + + if (qc->path == path) { + /* active path validation failed */ + + bkp = ngx_quic_get_path(c, NGX_QUIC_PATH_BACKUP); + + if (bkp == NULL) { + qc->error = NGX_QUIC_ERR_NO_VIABLE_PATH; + qc->error_reason = "no viable path"; + ngx_quic_close_connection(c, NGX_ERROR); + return; + } + + qc->path = bkp; + qc->path->tag = NGX_QUIC_PATH_ACTIVE; + + ngx_quic_set_connection_path(c, qc->path); + + ngx_log_error(NGX_LOG_INFO, c->log, 0, + "quic path seq:%uL addr:%V is restored from backup", + qc->path->seqnum, &qc->path->addr_text); + + ngx_quic_path_dbg(c, "is active", qc->path); + } + + if (ngx_quic_free_path(c, path) != NGX_OK) { + ngx_quic_close_connection(c, NGX_ERROR); + return; + } + } + + if (next != -1) { + ngx_add_timer(&qc->path_validation, next); + } +} |