diff options
Diffstat (limited to 'lwip/src/apps/altcp_tls/altcp_tls_mbedtls.c')
| -rw-r--r-- | lwip/src/apps/altcp_tls/altcp_tls_mbedtls.c | 1008 |
1 files changed, 1008 insertions, 0 deletions
diff --git a/lwip/src/apps/altcp_tls/altcp_tls_mbedtls.c b/lwip/src/apps/altcp_tls/altcp_tls_mbedtls.c new file mode 100644 index 0000000..de60801 --- /dev/null +++ b/lwip/src/apps/altcp_tls/altcp_tls_mbedtls.c @@ -0,0 +1,1008 @@ +/** + * @file + * Application layered TCP/TLS connection API (to be used from TCPIP thread) + * + * This file provides a TLS layer using mbedTLS + */ + +/* + * Copyright (c) 2017 Simon Goldschmidt + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without modification, + * are permitted provided that the following conditions are met: + * + * 1. Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright notice, + * this list of conditions and the following disclaimer in the documentation + * and/or other materials provided with the distribution. + * 3. The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED + * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT + * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, + * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT + * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING + * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY + * OF SUCH DAMAGE. + * + * This file is part of the lwIP TCP/IP stack. + * + * Author: Simon Goldschmidt <goldsimon@gmx.de> + * + * Watch out: + * - 'sent' is always called with len==0 to the upper layer. This is because keeping + * track of the ratio of application data and TLS overhead would be too much. + * + * Mandatory security-related configuration: + * - define ALTCP_MBEDTLS_RNG_FN to a custom GOOD rng function returning 0 on success: + * int my_rng_fn(void *ctx, unsigned char *buffer , size_t len) + * - define ALTCP_MBEDTLS_ENTROPY_PTR and ALTCP_MBEDTLS_ENTROPY_LEN to something providing + * GOOD custom entropy + * + * Missing things / @todo: + * - RX data is acknowledged after receiving (tcp_recved is called when enqueueing + * the pbuf for mbedTLS receive, not when processed by mbedTLS or the inner + * connection; altcp_recved() from inner connection does nothing) + * - Client connections starting with 'connect()' are not handled yet... + * - some unhandled things are caught by LWIP_ASSERTs... + */ + +#include "lwip/opt.h" + +#if LWIP_ALTCP /* don't build if not configured for use in lwipopts.h */ + +#include "lwip/apps/altcp_tls_mbedtls_opts.h" + +#if LWIP_ALTCP_TLS && LWIP_ALTCP_TLS_MBEDTLS + +#include "lwip/altcp.h" +#include "lwip/altcp_tls.h" +#include "lwip/priv/altcp_priv.h" + +#include "altcp_tls_mbedtls_structs.h" +#include "altcp_tls_mbedtls_mem.h" + +/* @todo: which includes are really needed? */ +#include "mbedtls/entropy.h" +#include "mbedtls/ctr_drbg.h" +#include "mbedtls/certs.h" +#include "mbedtls/x509.h" +#include "mbedtls/ssl.h" +#include "mbedtls/net.h" +#include "mbedtls/error.h" +#include "mbedtls/debug.h" +#include "mbedtls/platform.h" +#include "mbedtls/memory_buffer_alloc.h" +#include "mbedtls/ssl_cache.h" + +#include "mbedtls/ssl_internal.h" /* to call mbedtls_flush_output after ERR_MEM */ + +#include <string.h> + +#ifndef ALTCP_MBEDTLS_ENTROPY_PTR +#define ALTCP_MBEDTLS_ENTROPY_PTR NULL +#endif +#ifndef ALTCP_MBEDTLS_ENTROPY_LEN +#define ALTCP_MBEDTLS_ENTROPY_LEN 0 +#endif + +/* Variable prototype, the actual declaration is at the end of this file + since it contains pointers to static functions declared here */ +extern const struct altcp_functions altcp_mbedtls_functions; + +/** Our global mbedTLS configuration (server-specific, not connection-specific) */ +struct altcp_tls_config { + mbedtls_ssl_config conf; + mbedtls_entropy_context entropy; + mbedtls_ctr_drbg_context ctr_drbg; +#if defined(MBEDTLS_SSL_CACHE_C) && ALTCP_MBEDTLS_SESSION_CACHE_TIMEOUT_SECONDS + /** Inter-connection cache for fast connection startup */ + struct mbedtls_ssl_cache_context cache; +#endif +}; + +static err_t altcp_mbedtls_lower_recv(void *arg, struct altcp_pcb *inner_conn, struct pbuf *p, err_t err); +static err_t altcp_mbedtls_setup(void *conf, struct altcp_pcb *conn, struct altcp_pcb *inner_conn); +static void altcp_mbedtls_dealloc(struct altcp_pcb *conn); +static err_t altcp_mbedtls_lower_recv_process(struct altcp_pcb *conn, altcp_mbedtls_state_t *state); +static err_t altcp_mbedtls_handle_rx_appldata(struct altcp_pcb *conn, altcp_mbedtls_state_t *state); +static int altcp_mbedtls_bio_send(void *ctx, const unsigned char *dataptr, size_t size); + + +/* callback functions from inner/lower connection: */ + +/** Accept callback from lower connection (i.e. TCP) + * Allocate one of our structures, assign it to the new connection's 'state' and + * call the new connection's 'accepted' callback. If that succeeds, we wait + * to receive connection setup handshake bytes from the client. + */ +static err_t +altcp_mbedtls_lower_accept(void *arg, struct altcp_pcb *accepted_conn, err_t err) +{ + struct altcp_pcb *listen_conn = (struct altcp_pcb *)arg; + if (listen_conn && listen_conn->state && listen_conn->accept) { + err_t setup_err; + altcp_mbedtls_state_t *listen_state = (altcp_mbedtls_state_t *)listen_conn->state; + /* create a new altcp_conn to pass to the next 'accept' callback */ + struct altcp_pcb *new_conn = altcp_alloc(); + if (new_conn == NULL) { + return ERR_MEM; + } + setup_err = altcp_mbedtls_setup(listen_state->conf, new_conn, accepted_conn); + if (setup_err != ERR_OK) { + altcp_free(new_conn); + return setup_err; + } + return listen_conn->accept(listen_conn->arg, new_conn, err); + } + return ERR_ARG; +} + +/** Connected callback from lower connection (i.e. TCP). + * Not really implemented/tested yet... + */ +static err_t +altcp_mbedtls_lower_connected(void *arg, struct altcp_pcb *inner_conn, err_t err) +{ + struct altcp_pcb *conn = (struct altcp_pcb *)arg; + if (conn && conn->state) { + LWIP_ASSERT("pcb mismatch", conn->inner_conn == inner_conn); + /* upper connected is called when handshake is done */ + if (err != ERR_OK) { + if (conn->connected) { + if (conn->connected(conn->arg, conn, err) == ERR_ABRT) { + return ERR_ABRT; + } + return ERR_OK; + } + } + return altcp_mbedtls_lower_recv_process(conn, (altcp_mbedtls_state_t *)conn->state); + } + return ERR_VAL; +} + +/* Call recved for possibly more than an u16_t */ +static void +altcp_mbedtls_lower_recved(struct altcp_pcb *inner_conn, int recvd_cnt) +{ + while (recvd_cnt > 0) { + u16_t recvd_part = (u16_t)LWIP_MIN(recvd_cnt, 0xFFFF); + altcp_recved(inner_conn, recvd_part); + recvd_cnt -= recvd_part; + } +} + +/** Recv callback from lower connection (i.e. TCP) + * This one mainly differs between connection setup/handshake (data is fed into mbedTLS only) + * and application phase (data is decoded by mbedTLS and passed on to the application). + */ +static err_t +altcp_mbedtls_lower_recv(void *arg, struct altcp_pcb *inner_conn, struct pbuf *p, err_t err) +{ + altcp_mbedtls_state_t *state; + struct altcp_pcb *conn = (struct altcp_pcb *)arg; + + LWIP_ASSERT("no err expected", err == ERR_OK); + LWIP_UNUSED_ARG(err); + + if (!conn) { + /* no connection given as arg? should not happen, but prevent pbuf/conn leaks */ + if (p != NULL) { + pbuf_free(p); + } + altcp_close(inner_conn); + return ERR_CLSD; + } + state = (altcp_mbedtls_state_t *)conn->state; + LWIP_ASSERT("pcb mismatch", conn->inner_conn == inner_conn); + if (!state) { + /* already closed */ + if (p != NULL) { + pbuf_free(p); + } + altcp_close(inner_conn); + return ERR_CLSD; + } + + /* handle NULL pbuf (connection closed) */ + if (p == NULL) { + /* remote host sent FIN, remember this (SSL state is destroyed + when both sides are closed only!) */ + state->flags |= ALTCP_MBEDTLS_FLAGS_RX_CLOSE_QUEUED; + if ((state->flags & (ALTCP_MBEDTLS_FLAGS_HANDSHAKE_DONE | ALTCP_MBEDTLS_FLAGS_UPPER_CALLED)) == + (ALTCP_MBEDTLS_FLAGS_HANDSHAKE_DONE | ALTCP_MBEDTLS_FLAGS_UPPER_CALLED)) { + /* need to notify upper layer (e.g. 'accept' called or 'connect' succeeded) */ + if ((state->rx != NULL) || (state->rx_app != NULL)) { + /* this is a normal close (FIN) but we have unprocessed data, so delay the FIN */ + altcp_mbedtls_handle_rx_appldata(conn, state); + return ERR_OK; + } + if (conn->recv) { + err_t local_err = conn->recv(conn->arg, conn, NULL, ERR_OK); + if (local_err == ERR_ABRT) { + return ERR_ABRT; + } + } + } else { + /* before connection setup is done: call 'err' */ + if (conn->err) { + conn->err(conn->arg, ERR_CLSD); + } + } + altcp_close(conn); + state->flags |= ALTCP_MBEDTLS_FLAGS_RX_CLOSED; + if (conn->state && ((state->flags & ALTCP_MBEDTLS_FLAGS_CLOSED) == ALTCP_MBEDTLS_FLAGS_CLOSED)) { + altcp_mbedtls_dealloc(conn); + } + return ERR_OK; + } + + /* If we come here, the connection is in good state (handshake phase or application data phase). + Queue up the pbuf for processing as handshake data or application data. */ + if (state->rx == NULL) { + state->rx = p; + } else { + LWIP_ASSERT("rx pbuf overflow", (int)p->tot_len + (int)p->len <= 0xFFFF); + pbuf_cat(state->rx, p); + } + return altcp_mbedtls_lower_recv_process(conn, state); +} + +static err_t +altcp_mbedtls_lower_recv_process(struct altcp_pcb *conn, altcp_mbedtls_state_t *state) +{ + if (!(state->flags & ALTCP_MBEDTLS_FLAGS_HANDSHAKE_DONE)) { + /* handle connection setup (handshake not done) */ + int ret = mbedtls_ssl_handshake(&state->ssl_context); + /* try to send data... */ + altcp_output(conn->inner_conn); + if (state->bio_bytes_read) { + /* acknowledge all bytes read */ + altcp_mbedtls_lower_recved(conn->inner_conn, state->bio_bytes_read); + state->bio_bytes_read = 0; + } + + if (ret == MBEDTLS_ERR_SSL_WANT_READ || ret == MBEDTLS_ERR_SSL_WANT_WRITE) { + /* handshake not done, wait for more recv calls */ + LWIP_ASSERT("in this state, the rx chain should be empty", state->rx == NULL); + return ERR_OK; + } + if (ret != 0) { + LWIP_DEBUGF(ALTCP_MBEDTLS_DEBUG, ("mbedtls_ssl_handshake failed: %d\n", ret)); + /* handshake failed, connection has to be closed */ + conn->recv(conn->arg, conn, NULL, ERR_OK); + if (altcp_close(conn->inner_conn) != ERR_OK) { + altcp_abort(conn->inner_conn); + } + return ERR_OK; + } + /* If we come here, handshake succeeded. */ + LWIP_ASSERT("state", state->bio_bytes_read == 0); + LWIP_ASSERT("state", state->bio_bytes_appl == 0); + state->flags |= ALTCP_MBEDTLS_FLAGS_HANDSHAKE_DONE; + /* issue "connect" callback" to upper connection (this can only happen for active open) */ + if (conn->connected) { + conn->connected(conn->arg, conn, ERR_OK); + } + if (state->rx == NULL) { + return ERR_OK; + } + } + /* handle application data */ + return altcp_mbedtls_handle_rx_appldata(conn, state); +} + +/* Pass queued decoded rx data to application */ +static err_t +altcp_mbedtls_pass_rx_data(struct altcp_pcb *conn, altcp_mbedtls_state_t *state) +{ + err_t err; + struct pbuf *buf; + LWIP_ASSERT("conn != NULL", conn != NULL); + LWIP_ASSERT("state != NULL", state != NULL); + buf = state->rx_app; + if (buf) { + if (conn->recv) { + u16_t tot_len = state->rx_app->tot_len; + /* this needs to be increased first because the 'recved' call may come nested */ + state->rx_passed_unrecved += tot_len; + state->flags |= ALTCP_MBEDTLS_FLAGS_UPPER_CALLED; + err = conn->recv(conn->arg, conn, state->rx_app, ERR_OK); + if (err != ERR_OK) { + /* not received, leave the pbuf(s) queued (and decrease 'unrecved' again) */ + state->rx_passed_unrecved -= tot_len; + LWIP_ASSERT("state->rx_passed_unrecved >= 0", state->rx_passed_unrecved >= 0); + if (state->rx_passed_unrecved < 0) { + state->rx_passed_unrecved = 0; + } + return err; + } + } else { + pbuf_free(buf); + } + state->rx_app = NULL; + } else if ((state->flags & (ALTCP_MBEDTLS_FLAGS_RX_CLOSE_QUEUED | ALTCP_MBEDTLS_FLAGS_RX_CLOSED)) == + ALTCP_MBEDTLS_FLAGS_RX_CLOSE_QUEUED) { + state->flags |= ALTCP_MBEDTLS_FLAGS_RX_CLOSED; + if (conn->recv) { + err = conn->recv(conn->arg, conn, NULL, ERR_OK); + if (err == ERR_ABRT) { + return ERR_ABRT; + } + } + } + + return ERR_OK; +} + +/* Helper function that processes rx application data stored in rx pbuf chain */ +static err_t +altcp_mbedtls_handle_rx_appldata(struct altcp_pcb *conn, altcp_mbedtls_state_t *state) +{ + int ret; + LWIP_ASSERT("state != NULL", state != NULL); + if (!(state->flags & ALTCP_MBEDTLS_FLAGS_HANDSHAKE_DONE)) { + /* handshake not done yet */ + return ERR_VAL; + } + do { + /* allocate a full-sized unchained PBUF_POOL: this is for RX! */ + struct pbuf *buf = pbuf_alloc(PBUF_RAW, PBUF_POOL_BUFSIZE, PBUF_POOL); + if (buf == NULL) { + /* We're short on pbufs, try again later from 'poll' or 'recv' callbacks. + @todo: close on excessive allocation failures or leave this up to upper conn? */ + return ERR_OK; + } + + /* decrypt application data, this pulls encrypted RX data off state->rx pbuf chain */ + ret = mbedtls_ssl_read(&state->ssl_context, (unsigned char *)buf->payload, PBUF_POOL_BUFSIZE); + if (ret < 0) { + if (ret == MBEDTLS_ERR_SSL_CLIENT_RECONNECT) { + /* client is initiating a new connection using the same source port -> close connection or make handshake */ + LWIP_DEBUGF(ALTCP_MBEDTLS_DEBUG, ("new connection on same source port\n")); + LWIP_ASSERT("TODO: new connection on same source port, close this connection", 0); + } else if ((ret != MBEDTLS_ERR_SSL_WANT_READ) && (ret != MBEDTLS_ERR_SSL_WANT_WRITE)) { + if (ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY) { + LWIP_DEBUGF(ALTCP_MBEDTLS_DEBUG, ("connection was closed gracefully\n")); + } else if (ret == MBEDTLS_ERR_NET_CONN_RESET) { + LWIP_DEBUGF(ALTCP_MBEDTLS_DEBUG, ("connection was reset by peer\n")); + } + pbuf_free(buf); + return ERR_OK; + } else { + pbuf_free(buf); + return ERR_OK; + } + pbuf_free(buf); + altcp_abort(conn); + return ERR_ABRT; + } else { + err_t err; + if (ret) { + LWIP_ASSERT("bogus receive length", ret <= PBUF_POOL_BUFSIZE); + /* trim pool pbuf to actually decoded length */ + pbuf_realloc(buf, (u16_t)ret); + + state->bio_bytes_appl += ret; + if (mbedtls_ssl_get_bytes_avail(&state->ssl_context) == 0) { + /* Record is done, now we know the share between application and protocol bytes + and can adjust the RX window by the protocol bytes. + The rest is 'recved' by the application calling our 'recved' fn. */ + int overhead_bytes; + LWIP_ASSERT("bogus byte counts", state->bio_bytes_read > state->bio_bytes_appl); + overhead_bytes = state->bio_bytes_read - state->bio_bytes_appl; + altcp_mbedtls_lower_recved(conn->inner_conn, overhead_bytes); + state->bio_bytes_read = 0; + state->bio_bytes_appl = 0; + } + + if (state->rx_app == NULL) { + state->rx_app = buf; + } else { + pbuf_cat(state->rx_app, buf); + } + } else { + pbuf_free(buf); + buf = NULL; + } + err = altcp_mbedtls_pass_rx_data(conn, state); + if (err != ERR_OK) { + if (err == ERR_ABRT) { + /* recv callback needs to return this as the pcb is deallocated */ + return ERR_ABRT; + } + /* we hide all other errors as we retry feeding the pbuf to the app later */ + return ERR_OK; + } + } + } while (ret > 0); + return ERR_OK; +} + +/** Receive callback function called from mbedtls (set via mbedtls_ssl_set_bio) + * This function mainly copies data from pbufs and frees the pbufs after copying. + */ +static int +altcp_mbedtls_bio_recv(void *ctx, unsigned char *buf, size_t len) +{ + struct altcp_pcb *conn = (struct altcp_pcb *)ctx; + altcp_mbedtls_state_t *state; + struct pbuf *p; + u16_t ret; + u16_t copy_len; + err_t err; + + if ((conn == NULL) || (conn->state == NULL)) { + return MBEDTLS_ERR_NET_INVALID_CONTEXT; + } + state = (altcp_mbedtls_state_t *)conn->state; + p = state->rx; + + /* @todo: return MBEDTLS_ERR_NET_CONN_RESET/MBEDTLS_ERR_NET_RECV_FAILED? */ + + if ((p == NULL) || ((p->len == 0) && (p->next == NULL))) { + if (p) { + pbuf_free(p); + } + state->rx = NULL; + if ((state->flags & (ALTCP_MBEDTLS_FLAGS_RX_CLOSE_QUEUED | ALTCP_MBEDTLS_FLAGS_RX_CLOSED)) == + ALTCP_MBEDTLS_FLAGS_RX_CLOSE_QUEUED) { + /* close queued but not passed up yet */ + return 0; + } + return MBEDTLS_ERR_SSL_WANT_READ; + } + /* limit number of bytes again to copy from first pbuf in a chain only */ + copy_len = (u16_t)LWIP_MIN(len, p->len); + /* copy the data */ + ret = pbuf_copy_partial(p, buf, copy_len, 0); + LWIP_ASSERT("ret == copy_len", ret == copy_len); + /* hide the copied bytes from the pbuf */ + err = pbuf_remove_header(p, ret); + LWIP_ASSERT("error", err == ERR_OK); + if (p->len == 0) { + /* the first pbuf has been fully read, free it */ + state->rx = p->next; + p->next = NULL; + pbuf_free(p); + } + + state->bio_bytes_read += (int)ret; + return ret; +} + +/** Sent callback from lower connection (i.e. TCP) + * This only informs the upper layer to try to send more, not about + * the number of ACKed bytes. + */ +static err_t +altcp_mbedtls_lower_sent(void *arg, struct altcp_pcb *inner_conn, u16_t len) +{ + struct altcp_pcb *conn = (struct altcp_pcb *)arg; + LWIP_UNUSED_ARG(len); + if (conn) { + altcp_mbedtls_state_t *state = (altcp_mbedtls_state_t *)conn->state; + LWIP_ASSERT("pcb mismatch", conn->inner_conn == inner_conn); + if (!state || !(state->flags & ALTCP_MBEDTLS_FLAGS_HANDSHAKE_DONE)) { + /* @todo: do something here? */ + return ERR_OK; + } + /* try to send more if we failed before */ + mbedtls_ssl_flush_output(&state->ssl_context); + /* call upper sent with len==0 if the application already sent data */ + if ((state->flags & ALTCP_MBEDTLS_FLAGS_APPLDATA_SENT) && conn->sent) { + return conn->sent(conn->arg, conn, 0); + } + } + return ERR_OK; +} + +/** Poll callback from lower connection (i.e. TCP) + * Just pass this on to the application. + * @todo: retry sending? + */ +static err_t +altcp_mbedtls_lower_poll(void *arg, struct altcp_pcb *inner_conn) +{ + struct altcp_pcb *conn = (struct altcp_pcb *)arg; + if (conn) { + LWIP_ASSERT("pcb mismatch", conn->inner_conn == inner_conn); + /* check if there's unreceived rx data */ + if (conn->state) { + altcp_mbedtls_state_t *state = (altcp_mbedtls_state_t *)conn->state; + /* try to send more if we failed before */ + mbedtls_ssl_flush_output(&state->ssl_context); + if (altcp_mbedtls_handle_rx_appldata(conn, state) == ERR_ABRT) { + return ERR_ABRT; + } + } + if (conn->poll) { + return conn->poll(conn->arg, conn); + } + } + return ERR_OK; +} + +static void +altcp_mbedtls_lower_err(void *arg, err_t err) +{ + struct altcp_pcb *conn = (struct altcp_pcb *)arg; + if (conn) { + conn->inner_conn = NULL; /* already freed */ + if (conn->err) { + conn->err(conn->arg, err); + } + altcp_free(conn); + } +} + +/* setup functions */ +static void +altcp_mbedtls_setup_callbacks(struct altcp_pcb *conn, struct altcp_pcb *inner_conn) +{ + altcp_arg(inner_conn, conn); + altcp_recv(inner_conn, altcp_mbedtls_lower_recv); + altcp_sent(inner_conn, altcp_mbedtls_lower_sent); + altcp_err(inner_conn, altcp_mbedtls_lower_err); + /* tcp_poll is set when interval is set by application */ + /* listen is set totally different :-) */ +} + +static err_t +altcp_mbedtls_setup(void *conf, struct altcp_pcb *conn, struct altcp_pcb *inner_conn) +{ + int ret; + struct altcp_tls_config *config = (struct altcp_tls_config *)conf; + altcp_mbedtls_state_t *state; + if (!conf) { + return ERR_ARG; + } + /* allocate mbedtls context */ + state = altcp_mbedtls_alloc(conf); + if (state == NULL) { + return ERR_MEM; + } + /* initialize mbedtls context: */ + mbedtls_ssl_init(&state->ssl_context); + ret = mbedtls_ssl_setup(&state->ssl_context, &config->conf); + if (ret != 0) { + LWIP_DEBUGF(ALTCP_MBEDTLS_DEBUG, ("mbedtls_ssl_setup failed\n")); + /* @todo: convert 'ret' to err_t */ + altcp_mbedtls_free(conf, state); + return ERR_MEM; + } + /* tell mbedtls about our I/O functions */ + mbedtls_ssl_set_bio(&state->ssl_context, conn, altcp_mbedtls_bio_send, altcp_mbedtls_bio_recv, NULL); + + altcp_mbedtls_setup_callbacks(conn, inner_conn); + conn->inner_conn = inner_conn; + conn->fns = &altcp_mbedtls_functions; + conn->state = state; + return ERR_OK; +} + +struct altcp_pcb * +altcp_tls_new(struct altcp_tls_config *config, struct altcp_pcb *inner_pcb) +{ + struct altcp_pcb *ret; + if (inner_pcb == NULL) { + return NULL; + } + ret = altcp_alloc(); + if (ret != NULL) { + if (altcp_mbedtls_setup(config, ret, inner_pcb) != ERR_OK) { + altcp_free(ret); + return NULL; + } + } + return ret; +} + +void * +altcp_tls_context(struct altcp_pcb *conn) +{ + if (conn && conn->state) { + altcp_mbedtls_state_t *state = (altcp_mbedtls_state_t *)conn->state; + return &state->ssl_context; + } + return NULL; +} + +#if ALTCP_MBEDTLS_DEBUG != LWIP_DBG_OFF +static void +altcp_mbedtls_debug(void *ctx, int level, const char *file, int line, const char *str) +{ + LWIP_UNUSED_ARG(str); + LWIP_UNUSED_ARG(level); + LWIP_UNUSED_ARG(file); + LWIP_UNUSED_ARG(line); + LWIP_UNUSED_ARG(ctx); + /* @todo: output debug string :-) */ +} +#endif + +#ifndef ALTCP_MBEDTLS_RNG_FN +/** ATTENTION: It is *really* important to *NOT* use this dummy RNG in production code!!!! */ +static int +dummy_rng(void *ctx, unsigned char *buffer, size_t len) +{ + static size_t ctr; + size_t i; + LWIP_UNUSED_ARG(ctx); + for (i = 0; i < len; i++) { + buffer[i] = (unsigned char)++ctr; + } + return 0; +} +#define ALTCP_MBEDTLS_RNG_FN dummy_rng +#endif /* ALTCP_MBEDTLS_RNG_FN */ + +/** Create new TLS configuration + * ATTENTION: Server certificate and private key have to be added outside this function! + */ +static struct altcp_tls_config * +altcp_tls_create_config(int is_server) +{ + int ret; + struct altcp_tls_config *conf; + + altcp_mbedtls_mem_init(); + + conf = (struct altcp_tls_config *)altcp_mbedtls_alloc_config(sizeof(struct altcp_tls_config)); + if (conf == NULL) { + return NULL; + } + + mbedtls_ssl_config_init(&conf->conf); + mbedtls_entropy_init(&conf->entropy); + mbedtls_ctr_drbg_init(&conf->ctr_drbg); + + /* Seed the RNG */ + ret = mbedtls_ctr_drbg_seed(&conf->ctr_drbg, ALTCP_MBEDTLS_RNG_FN, &conf->entropy, ALTCP_MBEDTLS_ENTROPY_PTR, ALTCP_MBEDTLS_ENTROPY_LEN); + if (ret != 0) { + LWIP_DEBUGF(ALTCP_MBEDTLS_DEBUG, ("mbedtls_ctr_drbg_seed failed: %d\n", ret)); + altcp_mbedtls_free_config(conf); + return NULL; + } + + /* Setup ssl context (@todo: what's different for a client here? -> might better be done on listen/connect) */ + ret = mbedtls_ssl_config_defaults(&conf->conf, is_server ? MBEDTLS_SSL_IS_SERVER : MBEDTLS_SSL_IS_CLIENT, + MBEDTLS_SSL_TRANSPORT_STREAM, MBEDTLS_SSL_PRESET_DEFAULT); + if (ret != 0) { + LWIP_DEBUGF(ALTCP_MBEDTLS_DEBUG, ("mbedtls_ssl_config_defaults failed: %d\n", ret)); + altcp_mbedtls_free_config(conf); + return NULL; + } + mbedtls_ssl_conf_authmode(&conf->conf, MBEDTLS_SSL_VERIFY_OPTIONAL); + + mbedtls_ssl_conf_rng(&conf->conf, mbedtls_ctr_drbg_random, &conf->ctr_drbg); +#if ALTCP_MBEDTLS_DEBUG != LWIP_DBG_OFF + mbedtls_ssl_conf_dbg(&conf->conf, altcp_mbedtls_debug, stdout); +#endif +#if defined(MBEDTLS_SSL_CACHE_C) && ALTCP_MBEDTLS_SESSION_CACHE_TIMEOUT_SECONDS + mbedtls_ssl_conf_session_cache(&conf->conf, &conf->cache, mbedtls_ssl_cache_get, mbedtls_ssl_cache_set); + mbedtls_ssl_cache_set_timeout(&conf->cache, 30); + mbedtls_ssl_cache_set_max_entries(&conf->cache, 30); +#endif + + return conf; +} + +/** Create new TLS configuration + * This is a suboptimal version that gets the encrypted private key and its password, + * as well as the server certificate. + */ +struct altcp_tls_config * +altcp_tls_create_config_server_privkey_cert(const u8_t *privkey, size_t privkey_len, + const u8_t *privkey_pass, size_t privkey_pass_len, + const u8_t *cert, size_t cert_len) +{ + int ret; + static mbedtls_x509_crt srvcert; + static mbedtls_pk_context pkey; + struct altcp_tls_config *conf = altcp_tls_create_config(1); + if (conf == NULL) { + return NULL; + } + + mbedtls_x509_crt_init(&srvcert); + mbedtls_pk_init(&pkey); + + /* Load the certificates and private key */ + ret = mbedtls_x509_crt_parse(&srvcert, cert, cert_len); + if (ret != 0) { + LWIP_DEBUGF(ALTCP_MBEDTLS_DEBUG, ("mbedtls_x509_crt_parse failed: %d\n", ret)); + altcp_mbedtls_free_config(conf); + return NULL; + } + + ret = mbedtls_pk_parse_key(&pkey, (const unsigned char *) privkey, privkey_len, privkey_pass, privkey_pass_len); + if (ret != 0) { + LWIP_DEBUGF(ALTCP_MBEDTLS_DEBUG, ("mbedtls_pk_parse_public_key failed: %d\n", ret)); + altcp_mbedtls_free_config(conf); + return NULL; + } + + mbedtls_ssl_conf_ca_chain(&conf->conf, srvcert.next, NULL); + ret = mbedtls_ssl_conf_own_cert(&conf->conf, &srvcert, &pkey); + if (ret != 0) { + LWIP_DEBUGF(ALTCP_MBEDTLS_DEBUG, ("mbedtls_ssl_conf_own_cert failed: %d\n", ret)); + altcp_mbedtls_free_config(conf); + return NULL; + } + return conf; +} + +struct altcp_tls_config * +altcp_tls_create_config_client(const u8_t *cert, size_t cert_len) +{ + int ret; + static mbedtls_x509_crt acc_cert; + struct altcp_tls_config *conf = altcp_tls_create_config(0); + if (conf == NULL) { + return NULL; + } + + mbedtls_x509_crt_init(&acc_cert); + + /* Load the certificates */ + ret = mbedtls_x509_crt_parse(&acc_cert, cert, cert_len); + if (ret != 0) { + LWIP_DEBUGF(ALTCP_MBEDTLS_DEBUG, ("mbedtls_x509_crt_parse failed: %d", ret)); + altcp_mbedtls_free_config(conf); + return NULL; + } + + mbedtls_ssl_conf_ca_chain(&conf->conf, &acc_cert, NULL); + return conf; +} + +void +altcp_tls_free_config(struct altcp_tls_config *conf) +{ + altcp_mbedtls_free_config(conf); +} + +/* "virtual" functions */ +static void +altcp_mbedtls_set_poll(struct altcp_pcb *conn, u8_t interval) +{ + if (conn != NULL) { + altcp_poll(conn->inner_conn, altcp_mbedtls_lower_poll, interval); + } +} + +static void +altcp_mbedtls_recved(struct altcp_pcb *conn, u16_t len) +{ + u16_t lower_recved; + altcp_mbedtls_state_t *state; + if (conn == NULL) { + return; + } + state = (altcp_mbedtls_state_t *)conn->state; + if (state == NULL) { + return; + } + if (!(state->flags & ALTCP_MBEDTLS_FLAGS_HANDSHAKE_DONE)) { + return; + } + lower_recved = len; + if (lower_recved > state->rx_passed_unrecved) { + LWIP_DEBUGF(ALTCP_MBEDTLS_DEBUG, ("bogus recved count (len > state->rx_passed_unrecved / %d / %d)", + len, state->rx_passed_unrecved)); + lower_recved = (u16_t)state->rx_passed_unrecved; + } + state->rx_passed_unrecved -= lower_recved; + + altcp_recved(conn->inner_conn, lower_recved); +} + +static err_t +altcp_mbedtls_connect(struct altcp_pcb *conn, const ip_addr_t *ipaddr, u16_t port, altcp_connected_fn connected) +{ + if (conn == NULL) { + return ERR_VAL; + } + conn->connected = connected; + return altcp_connect(conn->inner_conn, ipaddr, port, altcp_mbedtls_lower_connected); +} + +static struct altcp_pcb * +altcp_mbedtls_listen(struct altcp_pcb *conn, u8_t backlog, err_t *err) +{ + struct altcp_pcb *lpcb; + if (conn == NULL) { + return NULL; + } + lpcb = altcp_listen_with_backlog_and_err(conn->inner_conn, backlog, err); + if (lpcb != NULL) { + conn->inner_conn = lpcb; + altcp_accept(lpcb, altcp_mbedtls_lower_accept); + return conn; + } + return NULL; +} + +static void +altcp_mbedtls_abort(struct altcp_pcb *conn) +{ + if (conn != NULL) { + altcp_abort(conn->inner_conn); + } +} + +static err_t +altcp_mbedtls_close(struct altcp_pcb *conn) +{ + altcp_mbedtls_state_t *state; + if (conn == NULL) { + return ERR_VAL; + } + state = (altcp_mbedtls_state_t *)conn->state; + if (state != NULL) { + state->flags |= ALTCP_MBEDTLS_FLAGS_TX_CLOSED; + if (state->flags & ALTCP_MBEDTLS_FLAGS_RX_CLOSED) { + altcp_mbedtls_dealloc(conn); + } + } + return altcp_close(conn->inner_conn); +} + +/** Write data to a TLS connection. Calls into mbedTLS, which in turn calls into + * @ref altcp_mbedtls_bio_send() to send the encrypted data + */ +static err_t +altcp_mbedtls_write(struct altcp_pcb *conn, const void *dataptr, u16_t len, u8_t apiflags) +{ + int ret; + altcp_mbedtls_state_t *state; + + LWIP_UNUSED_ARG(apiflags); + + if (conn == NULL) { + return ERR_VAL; + } + + state = (altcp_mbedtls_state_t *)conn->state; + if (state == NULL) { + /* @todo: which error? */ + return ERR_CLSD; + } + if (!(state->flags & ALTCP_MBEDTLS_FLAGS_HANDSHAKE_DONE)) { + /* @todo: which error? */ + return ERR_VAL; + } + + /* HACK: if thre is something left to send, try to flush it and only + allow sending more if this succeeded (this is a hack because neither + returning 0 nor MBEDTLS_ERR_SSL_WANT_WRITE worked for me) */ + if (state->ssl_context.out_left) { + mbedtls_ssl_flush_output(&state->ssl_context); + if (state->ssl_context.out_left) { + return ERR_MEM; + } + } + ret = mbedtls_ssl_write(&state->ssl_context, (const unsigned char *)dataptr, len); + /* try to send data... */ + altcp_output(conn->inner_conn); + if (ret >= 0) { + if (ret == len) { + state->flags |= ALTCP_MBEDTLS_FLAGS_APPLDATA_SENT; + return ERR_OK; + } else { + /* @todo/@fixme: assumption: either everything sent or error */ + LWIP_ASSERT("ret <= 0", 0); + return ERR_MEM; + } + } else { + if (ret == MBEDTLS_ERR_SSL_WANT_WRITE) { + /* @todo: convert error to err_t */ + return ERR_MEM; + } + LWIP_ASSERT("unhandled error", 0); + return ERR_VAL; + } +} + +/** Send callback function called from mbedtls (set via mbedtls_ssl_set_bio) + * This function is either called during handshake or when sending application + * data via @ref altcp_mbedtls_write (or altcp_write) + */ +static int +altcp_mbedtls_bio_send(void *ctx, const unsigned char *dataptr, size_t size) +{ + struct altcp_pcb *conn = (struct altcp_pcb *) ctx; + int written = 0; + size_t size_left = size; + u8_t apiflags = TCP_WRITE_FLAG_COPY; + + LWIP_ASSERT("conn != NULL", conn != NULL); + if ((conn == NULL) || (conn->inner_conn == NULL)) { + return MBEDTLS_ERR_NET_INVALID_CONTEXT; + } + + while (size_left) { + u16_t write_len = (u16_t)LWIP_MIN(size_left, 0xFFFF); + err_t err = altcp_write(conn->inner_conn, (const void *)dataptr, write_len, apiflags); + if (err == ERR_OK) { + written += write_len; + size_left -= write_len; + } else if (err == ERR_MEM) { + if (written) { + return written; + } + return 0; /* MBEDTLS_ERR_SSL_WANT_WRITE; */ + } else { + LWIP_ASSERT("tls_write, tcp_write: err != ERR MEM", 0); + /* @todo: return MBEDTLS_ERR_NET_CONN_RESET or MBEDTLS_ERR_NET_SEND_FAILED */ + return MBEDTLS_ERR_NET_SEND_FAILED; + } + } + return written; +} + +static u16_t +altcp_mbedtls_mss(struct altcp_pcb *conn) +{ + if (conn == NULL) { + return 0; + } + /* @todo: LWIP_MIN(mss, mbedtls_ssl_get_max_frag_len()) ? */ + return altcp_mss(conn->inner_conn); +} + +static void +altcp_mbedtls_dealloc(struct altcp_pcb *conn) +{ + /* clean up and free tls state */ + if (conn) { + altcp_mbedtls_state_t *state = (altcp_mbedtls_state_t *)conn->state; + if (state) { + mbedtls_ssl_free(&state->ssl_context); + state->flags = 0; + altcp_mbedtls_free(state->conf, state); + conn->state = NULL; + } + if (conn->inner_conn) { + altcp_free(conn->inner_conn); + conn->inner_conn = NULL; + } + } +} + +const struct altcp_functions altcp_mbedtls_functions = { + altcp_mbedtls_set_poll, + altcp_mbedtls_recved, + altcp_default_bind, + altcp_mbedtls_connect, + altcp_mbedtls_listen, + altcp_mbedtls_abort, + altcp_mbedtls_close, + altcp_default_shutdown, + altcp_mbedtls_write, + altcp_default_output, + altcp_mbedtls_mss, + altcp_default_sndbuf, + altcp_default_sndqueuelen, + altcp_default_nagle_disable, + altcp_default_nagle_enable, + altcp_default_nagle_disabled, + altcp_default_setprio, + altcp_mbedtls_dealloc, + altcp_default_get_tcp_addrinfo, + altcp_default_get_ip, + altcp_default_get_port +#ifdef LWIP_DEBUG + , altcp_default_dbg_get_tcp_state +#endif +}; + +#endif /* LWIP_ALTCP_TLS && LWIP_ALTCP_TLS_MBEDTLS */ +#endif /* LWIP_ALTCP */ |