diff --git a/src/openvpn/reliable.c b/src/openvpn/reliable.c index 372444350..9b2b2fc6f 100644 --- a/src/openvpn/reliable.c +++ b/src/openvpn/reliable.c @@ -41,6 +41,14 @@ #include "memdbg.h" +/* calculates test - base while allowing for base or test wraparound. test is + * assumed to be higher than base */ +static inline packet_id_type +subtract_pid(const packet_id_type test, const packet_id_type base) +{ + return test - base; +} + /* * verify that test - base < extent while allowing for base or test wraparound */ @@ -49,22 +57,7 @@ reliable_pid_in_range1(const packet_id_type test, const packet_id_type base, const unsigned int extent) { - if (test >= base) - { - if (test - base < extent) - { - return true; - } - } - else - { - if ((test+0x80000000u) - (base+0x80000000u) < extent) - { - return true; - } - } - - return false; + return subtract_pid(test, base) < extent; } /* @@ -496,6 +489,38 @@ reliable_get_buf(struct reliable *rel) return NULL; } +/* Counts the number of free buffers in output that can be potientially used + * for sending */ +int +reliable_get_num_output_sequenced_available(struct reliable *rel) +{ + struct gc_arena gc = gc_new(); + packet_id_type min_id = 0; + bool min_id_defined = false; + + /* find minimum active packet_id */ + for (int i = 0; i < rel->size; ++i) + { + const struct reliable_entry *e = &rel->array[i]; + if (e->active) + { + if (!min_id_defined || reliable_pid_min(e->packet_id, min_id)) + { + min_id_defined = true; + min_id = e->packet_id; + } + } + } + + int ret = rel->size; + if (min_id_defined) + { + ret -= subtract_pid(rel->packet_id, min_id); + } + gc_free(&gc); + return ret; +} + /* grab a free buffer, fail if buffer clogged by unacknowledged low packet IDs */ struct buffer * reliable_get_buf_output_sequenced(struct reliable *rel) diff --git a/src/openvpn/reliable.h b/src/openvpn/reliable.h index b9863efe3..5b4f75c28 100644 --- a/src/openvpn/reliable.h +++ b/src/openvpn/reliable.h @@ -46,7 +46,7 @@ * be stored in one \c reliable_ack * structure. */ -#define RELIABLE_CAPACITY 8 /**< The maximum number of packets that +#define RELIABLE_CAPACITY 12 /**< The maximum number of packets that * the reliability layer for one VPN * tunnel in one direction can store. */ @@ -93,7 +93,7 @@ struct reliable int size; interval_t initial_timeout; packet_id_type packet_id; - int offset; + int offset; /**< Offset of the bufs in the reliable_entry array */ bool hold; /* don't xmit until reliable_schedule_now is called */ struct reliable_entry array[RELIABLE_CAPACITY]; }; @@ -178,6 +178,20 @@ reliable_ack_empty(struct reliable_ack *ack) return !ack->len; } +/** + * Returns the number of packets that need to be acked. + * + * @param ack The acknowledgment structure to check. + * + * @returns the number of outstanding acks + */ +static inline int +reliable_ack_outstanding(struct reliable_ack *ack) +{ + return ack->len; +} + + /** * Write a packet ID acknowledgment record to a buffer. * @@ -385,6 +399,20 @@ void reliable_mark_deleted(struct reliable *rel, struct buffer *buf); */ struct buffer *reliable_get_buf_output_sequenced(struct reliable *rel); + +/** + * Counts the number of free buffers in output that can be potientially used + * for sending + * + * @param rel The reliable structure in which to search for a free + * entry. + * + * @return the number of buffer that are available for sending without + * breaking ack sequence + * */ +int +reliable_get_num_output_sequenced_available(struct reliable *rel); + /** * Mark the reliable entry associated with the given buffer as * active outgoing. diff --git a/src/openvpn/ssl.c b/src/openvpn/ssl.c index 61dea996d..1e3c500d8 100644 --- a/src/openvpn/ssl.c +++ b/src/openvpn/ssl.c @@ -323,8 +323,10 @@ tls_init_control_channel_frame_parameters(const struct frame *data_channel_frame /* Previous OpenVPN version calculated the maximum size and buffer of a * control frame depending on the overhead of the data channel frame * overhead and limited its maximum size to 1250. We always allocate the - * 1250 buffer size since a lot of code blindly assumes a large buffer - * (e.g. PUSH_BUNDLE_SIZE) and set frame->mtu_mtu as suggestion for the + * TLS_CHANNEL_BUF_SIZE buffer size since a lot of code blindly assumes + * a large buffer (e.g. PUSH_BUNDLE_SIZE) and also our peer might have + * a higher size configured and we still want to be able to receive the + * packets. frame->mtu_mtu is set as suggestion for the maximum packet * size */ frame->buf.payload_size = 1250 + overhead; @@ -334,6 +336,47 @@ tls_init_control_channel_frame_parameters(const struct frame *data_channel_frame frame->tun_mtu = min_int(data_channel_frame->tun_mtu, 1250); } +/** + * calculate the maximum overhead that control channel frames have + * This includes header, op code and everything apart from the + * payload itself. This method is a bit pessimistic and might give higher + * overhead than we actually have */ +static int +calc_control_channel_frame_overhead(const struct tls_session *session) +{ + const struct key_state *ks = &session->key[KS_PRIMARY]; + int overhead = 0; + + /* TCP length field and opcode */ + overhead += 3; + + /* our own session id */ + overhead += SID_SIZE; + + /* ACK array and remote SESSION ID (part of the ACK array) */ + overhead += ACK_SIZE(min_int(reliable_ack_outstanding(ks->rec_ack), CONTROL_SEND_ACK_MAX)); + + /* Message packet id */ + overhead += sizeof(packet_id_type); + + if (session->tls_wrap.mode == TLS_WRAP_CRYPT) + { + overhead += tls_crypt_buf_overhead(); + } + else if (session->tls_wrap.mode == TLS_WRAP_AUTH) + { + overhead += hmac_ctx_size(session->tls_wrap.opt.key_ctx_bi.encrypt.hmac); + overhead += packet_id_size(true); + } + + /* Add the typical UDP overhead for an IPv6 UDP packet. TCP+IPv6 has a + * larger overhead but the risk of a TCP connection getting dropped because + * we try to send a too large packet is basically zero */ + overhead += datagram_overhead(AF_INET6, PROTO_UDP); + + return overhead; +} + void init_ssl_lib(void) { @@ -2619,7 +2662,7 @@ read_incoming_tls_plaintext(struct key_state *ks, struct buffer *buf, { ASSERT(buf_init(buf, 0)); - int status = key_state_read_plaintext(&ks->ks_ssl, buf, TLS_CHANNEL_BUF_SIZE); + int status = key_state_read_plaintext(&ks->ks_ssl, buf); update_time(); if (status == -1) @@ -2638,6 +2681,91 @@ read_incoming_tls_plaintext(struct key_state *ks, struct buffer *buf, return true; } +static bool +write_outgoing_tls_ciphertext(struct tls_session *session, bool *state_change) +{ + struct key_state *ks = &session->key[KS_PRIMARY]; + + int rel_avail = reliable_get_num_output_sequenced_available(ks->send_reliable); + if (rel_avail == 0) + { + return true; + } + + /* We need to determine how much space is actually available in the control + * channel frame */ + + int max_pkt_len = min_int(TLS_CHANNEL_BUF_SIZE, session->opt->frame.tun_mtu); + + + /* Subtract overhead */ + max_pkt_len -= calc_control_channel_frame_overhead(session); + + /* calculate total available length for outgoing tls ciphertext */ + int maxlen = max_pkt_len * rel_avail; + + /* Is first packet one that will have a WKC appended? */ + if (control_packet_needs_wkc(ks)) + { + maxlen -= buf_len(session->tls_wrap.tls_crypt_v2_wkc); + } + + /* Not enough space available to send a full control channel packet */ + if (maxlen < TLS_CHANNEL_BUF_SIZE) + { + if (rel_avail == TLS_RELIABLE_N_SEND_BUFFERS) + { + msg(D_TLS_ERRORS, "--tls-mtu setting to low. Unable to send TLS packets"); + } + msg(D_REL_LOW, "Reliable: Send queue full, postponing TLS send"); + return true; + } + + /* This seems a bit wasteful to allocate every time */ + struct gc_arena gc = gc_new(); + struct buffer tmp = alloc_buf_gc(TLS_CHANNEL_BUF_SIZE, &gc); + + int status = key_state_read_ciphertext(&ks->ks_ssl, &tmp); + + if (status == -1) + { + msg(D_TLS_ERRORS, + "TLS Error: Ciphertext -> reliable TCP/UDP transport read error"); + gc_free(&gc); + return false; + } + if (status == 1) + { + /* Split the TLS ciphertext (TLS record) into multiple small packets + * that respect tls_mtu */ + while (tmp.len) + { + int len = max_pkt_len; + int opcode = P_CONTROL_V1; + if (control_packet_needs_wkc(ks)) + { + opcode = P_CONTROL_WKC_V1; + len = max_int(0, len - buf_len(session->tls_wrap.tls_crypt_v2_wkc)); + } + /* do not send more than available */ + len = min_int(len, tmp.len); + + struct buffer *buf = reliable_get_buf_output_sequenced(ks->send_reliable); + /* we assert here since we checked for its availibility before */ + ASSERT(buf); + buf_copy_n(buf, &tmp, len); + + reliable_mark_active_outgoing(ks->send_reliable, buf, opcode); + INCR_GENERATED; + *state_change = true; + } + dmsg(D_TLS_DEBUG, "Outgoing Ciphertext -> Reliable"); + } + + gc_free(&gc); + return true; +} + static bool tls_process_state(struct tls_multi *multi, @@ -2792,26 +2920,10 @@ tls_process_state(struct tls_multi *multi, buf = reliable_get_buf_output_sequenced(ks->send_reliable); if (buf) { - int status = key_state_read_ciphertext(&ks->ks_ssl, buf, multi->opt.frame.tun_mtu); - - if (status == -1) + if (!write_outgoing_tls_ciphertext(session, &state_change)) { - msg(D_TLS_ERRORS, - "TLS Error: Ciphertext -> reliable TCP/UDP transport read error"); goto error; } - if (status == 1) - { - int opcode = P_CONTROL_V1; - if (control_packet_needs_wkc(ks)) - { - opcode = P_CONTROL_WKC_V1; - } - reliable_mark_active_outgoing(ks->send_reliable, buf, opcode); - INCR_GENERATED; - state_change = true; - dmsg(D_TLS_DEBUG, "Outgoing Ciphertext -> Reliable"); - } } } diff --git a/src/openvpn/ssl_backend.h b/src/openvpn/ssl_backend.h index 1bd336999..215425d41 100644 --- a/src/openvpn/ssl_backend.h +++ b/src/openvpn/ssl_backend.h @@ -461,7 +461,6 @@ int key_state_write_plaintext_const(struct key_state_ssl *ks_ssl, * @param ks_ssl - The security parameter state for this %key * session. * @param buf - A buffer in which to store the ciphertext. - * @param maxlen - The maximum number of bytes to extract. * * @return The return value indicates whether the data was successfully * processed: @@ -470,8 +469,8 @@ int key_state_write_plaintext_const(struct key_state_ssl *ks_ssl, * later to retry. * - \c -1: An error occurred. */ -int key_state_read_ciphertext(struct key_state_ssl *ks_ssl, struct buffer *buf, - int maxlen); +int key_state_read_ciphertext(struct key_state_ssl *ks_ssl, struct buffer *buf); + /** @} name Functions for packets to be sent to a remote OpenVPN peer */ @@ -517,8 +516,7 @@ int key_state_write_ciphertext(struct key_state_ssl *ks_ssl, * later to retry. * - \c -1: An error occurred. */ -int key_state_read_plaintext(struct key_state_ssl *ks_ssl, struct buffer *buf, - int maxlen); +int key_state_read_plaintext(struct key_state_ssl *ks_ssl, struct buffer *buf); /** @} name Functions for packets received from a remote OpenVPN peer */ diff --git a/src/openvpn/ssl_mbedtls.c b/src/openvpn/ssl_mbedtls.c index b0785bae9..ea06cf703 100644 --- a/src/openvpn/ssl_mbedtls.c +++ b/src/openvpn/ssl_mbedtls.c @@ -1285,8 +1285,7 @@ key_state_write_plaintext_const(struct key_state_ssl *ks, const uint8_t *data, i } int -key_state_read_ciphertext(struct key_state_ssl *ks, struct buffer *buf, - int maxlen) +key_state_read_ciphertext(struct key_state_ssl *ks, struct buffer *buf) { int retval = 0; int len = 0; @@ -1304,10 +1303,6 @@ key_state_read_ciphertext(struct key_state_ssl *ks, struct buffer *buf, } len = buf_forward_capacity(buf); - if (maxlen < len) - { - len = maxlen; - } retval = endless_buf_read(&ks->bio_ctx->out, BPTR(buf), len); @@ -1388,8 +1383,7 @@ key_state_write_ciphertext(struct key_state_ssl *ks, struct buffer *buf) } int -key_state_read_plaintext(struct key_state_ssl *ks, struct buffer *buf, - int maxlen) +key_state_read_plaintext(struct key_state_ssl *ks, struct buffer *buf) { int retval = 0; int len = 0; @@ -1407,10 +1401,6 @@ key_state_read_plaintext(struct key_state_ssl *ks, struct buffer *buf, } len = buf_forward_capacity(buf); - if (maxlen < len) - { - len = maxlen; - } retval = mbedtls_ssl_read(ks->ctx, BPTR(buf), len); diff --git a/src/openvpn/ssl_openssl.c b/src/openvpn/ssl_openssl.c index c9ea10d49..92bf60862 100644 --- a/src/openvpn/ssl_openssl.c +++ b/src/openvpn/ssl_openssl.c @@ -1871,7 +1871,7 @@ bio_write_post(const int status, struct buffer *buf) * Read from an OpenSSL BIO in non-blocking mode. */ static int -bio_read(BIO *bio, struct buffer *buf, int maxlen, const char *desc) +bio_read(BIO *bio, struct buffer *buf, const char *desc) { int i; int ret = 0; @@ -1882,10 +1882,6 @@ bio_read(BIO *bio, struct buffer *buf, int maxlen, const char *desc) else { int len = buf_forward_capacity(buf); - if (maxlen < len) - { - len = maxlen; - } /* * BIO_read brackets most of the serious RSA @@ -2012,15 +2008,14 @@ key_state_write_plaintext_const(struct key_state_ssl *ks_ssl, const uint8_t *dat } int -key_state_read_ciphertext(struct key_state_ssl *ks_ssl, struct buffer *buf, - int maxlen) +key_state_read_ciphertext(struct key_state_ssl *ks_ssl, struct buffer *buf) { int ret = 0; perf_push(PERF_BIO_READ_CIPHERTEXT); ASSERT(NULL != ks_ssl); - ret = bio_read(ks_ssl->ct_out, buf, maxlen, "tls_read_ciphertext"); + ret = bio_read(ks_ssl->ct_out, buf, "tls_read_ciphertext"); perf_pop(); return ret; @@ -2042,15 +2037,14 @@ key_state_write_ciphertext(struct key_state_ssl *ks_ssl, struct buffer *buf) } int -key_state_read_plaintext(struct key_state_ssl *ks_ssl, struct buffer *buf, - int maxlen) +key_state_read_plaintext(struct key_state_ssl *ks_ssl, struct buffer *buf) { int ret = 0; perf_push(PERF_BIO_READ_PLAINTEXT); ASSERT(NULL != ks_ssl); - ret = bio_read(ks_ssl->ssl_bio, buf, maxlen, "tls_read_plaintext"); + ret = bio_read(ks_ssl->ssl_bio, buf, "tls_read_plaintext"); perf_pop(); return ret; diff --git a/src/openvpn/ssl_pkt.h b/src/openvpn/ssl_pkt.h index 45e0a81f5..9bb3ca958 100644 --- a/src/openvpn/ssl_pkt.h +++ b/src/openvpn/ssl_pkt.h @@ -67,8 +67,8 @@ /* * Define number of buffers for send and receive in the reliability layer. */ -#define TLS_RELIABLE_N_SEND_BUFFERS 4 /* also window size for reliability layer */ -#define TLS_RELIABLE_N_REC_BUFFERS 8 +#define TLS_RELIABLE_N_SEND_BUFFERS 6 /* also window size for reliability layer */ +#define TLS_RELIABLE_N_REC_BUFFERS 12 /* * Used in --mode server mode to check tls-auth signature on initial