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micropython/extmod/modussl_mbedtls.c

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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2016 Linaro Ltd.
* Copyright (c) 2019 Paul Sokolovsky
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "py/mpconfig.h"
#if MICROPY_PY_USSL && MICROPY_SSL_MBEDTLS
#include <stdio.h>
#include <string.h>
#include <errno.h> // needed because mp_is_nonblocking_error uses system error codes
#include "py/runtime.h"
#include "py/stream.h"
#include "py/objstr.h"
// mbedtls_time_t
#include "mbedtls/platform.h"
#include "mbedtls/ssl.h"
#include "mbedtls/x509_crt.h"
#include "mbedtls/pk.h"
#include "mbedtls/entropy.h"
#include "mbedtls/ctr_drbg.h"
#include "mbedtls/debug.h"
#include "mbedtls/error.h"
typedef struct _mp_obj_ssl_socket_t {
mp_obj_base_t base;
mp_obj_t sock;
mbedtls_entropy_context entropy;
mbedtls_ctr_drbg_context ctr_drbg;
mbedtls_ssl_context ssl;
mbedtls_ssl_config conf;
mbedtls_x509_crt cacert;
mbedtls_x509_crt cert;
mbedtls_pk_context pkey;
} mp_obj_ssl_socket_t;
struct ssl_args {
mp_arg_val_t key;
mp_arg_val_t cert;
mp_arg_val_t server_side;
mp_arg_val_t server_hostname;
mp_arg_val_t cert_reqs;
mp_arg_val_t cadata;
mp_arg_val_t do_handshake;
};
STATIC const mp_obj_type_t ussl_socket_type;
#ifdef MBEDTLS_DEBUG_C
STATIC void mbedtls_debug(void *ctx, int level, const char *file, int line, const char *str) {
(void)ctx;
(void)level;
mp_printf(&mp_plat_print, "DBG:%s:%04d: %s\n", file, line, str);
}
#endif
STATIC NORETURN void mbedtls_raise_error(int err) {
// _mbedtls_ssl_send and _mbedtls_ssl_recv (below) turn positive error codes from the
// underlying socket into negative codes to pass them through mbedtls. Here we turn them
// positive again so they get interpreted as the OSError they really are. The
// cut-off of -256 is a bit hacky, sigh.
if (err < 0 && err > -256) {
mp_raise_OSError(-err);
}
#if defined(MBEDTLS_ERROR_C)
// Including mbedtls_strerror takes about 1.5KB due to the error strings.
// MBEDTLS_ERROR_C is the define used by mbedtls to conditionally include mbedtls_strerror.
// It is set/unset in the MBEDTLS_CONFIG_FILE which is defined in the Makefile.
// Try to allocate memory for the message
#define ERR_STR_MAX 80 // mbedtls_strerror truncates if it doesn't fit
mp_obj_str_t *o_str = m_new_obj_maybe(mp_obj_str_t);
byte *o_str_buf = m_new_maybe(byte, ERR_STR_MAX);
if (o_str == NULL || o_str_buf == NULL) {
mp_raise_OSError(err);
}
// print the error message into the allocated buffer
mbedtls_strerror(err, (char *)o_str_buf, ERR_STR_MAX);
size_t len = strlen((char *)o_str_buf);
// Put the exception object together
o_str->base.type = &mp_type_str;
o_str->data = o_str_buf;
o_str->len = len;
o_str->hash = qstr_compute_hash(o_str->data, o_str->len);
// raise
mp_obj_t args[2] = { MP_OBJ_NEW_SMALL_INT(err), MP_OBJ_FROM_PTR(o_str)};
nlr_raise(mp_obj_exception_make_new(&mp_type_OSError, 2, 0, args));
#else
// mbedtls is compiled without error strings so we simply return the err number
mp_raise_OSError(err); // err is typically a large negative number
#endif
}
STATIC int _mbedtls_ssl_send(void *ctx, const byte *buf, size_t len) {
mp_obj_t sock = *(mp_obj_t *)ctx;
const mp_stream_p_t *sock_stream = mp_get_stream(sock);
int err;
mp_uint_t out_sz = sock_stream->write(sock, buf, len, &err);
if (out_sz == MP_STREAM_ERROR) {
if (mp_is_nonblocking_error(err)) {
return MBEDTLS_ERR_SSL_WANT_WRITE;
}
return -err; // convert an MP_ERRNO to something mbedtls passes through as error
} else {
return out_sz;
}
}
// _mbedtls_ssl_recv is called by mbedtls to receive bytes from the underlying socket
STATIC int _mbedtls_ssl_recv(void *ctx, byte *buf, size_t len) {
mp_obj_t sock = *(mp_obj_t *)ctx;
const mp_stream_p_t *sock_stream = mp_get_stream(sock);
int err;
mp_uint_t out_sz = sock_stream->read(sock, buf, len, &err);
if (out_sz == MP_STREAM_ERROR) {
if (mp_is_nonblocking_error(err)) {
return MBEDTLS_ERR_SSL_WANT_READ;
}
return -err;
} else {
return out_sz;
}
}
STATIC mp_obj_ssl_socket_t *socket_new(mp_obj_t sock, struct ssl_args *args) {
// Verify the socket object has the full stream protocol
mp_get_stream_raise(sock, MP_STREAM_OP_READ | MP_STREAM_OP_WRITE | MP_STREAM_OP_IOCTL);
#if MICROPY_PY_USSL_FINALISER
mp_obj_ssl_socket_t *o = m_new_obj_with_finaliser(mp_obj_ssl_socket_t);
#else
mp_obj_ssl_socket_t *o = m_new_obj(mp_obj_ssl_socket_t);
#endif
o->base.type = &ussl_socket_type;
o->sock = sock;
int ret;
mbedtls_ssl_init(&o->ssl);
mbedtls_ssl_config_init(&o->conf);
mbedtls_x509_crt_init(&o->cacert);
mbedtls_x509_crt_init(&o->cert);
mbedtls_pk_init(&o->pkey);
mbedtls_ctr_drbg_init(&o->ctr_drbg);
#ifdef MBEDTLS_DEBUG_C
// Debug level (0-4) 1=warning, 2=info, 3=debug, 4=verbose
mbedtls_debug_set_threshold(3);
#endif
mbedtls_entropy_init(&o->entropy);
const byte seed[] = "upy";
ret = mbedtls_ctr_drbg_seed(&o->ctr_drbg, mbedtls_entropy_func, &o->entropy, seed, sizeof(seed));
if (ret != 0) {
goto cleanup;
}
ret = mbedtls_ssl_config_defaults(&o->conf,
args->server_side.u_bool ? MBEDTLS_SSL_IS_SERVER : MBEDTLS_SSL_IS_CLIENT,
MBEDTLS_SSL_TRANSPORT_STREAM,
MBEDTLS_SSL_PRESET_DEFAULT);
if (ret != 0) {
goto cleanup;
}
mbedtls_ssl_conf_authmode(&o->conf, args->cert_reqs.u_int);
mbedtls_ssl_conf_rng(&o->conf, mbedtls_ctr_drbg_random, &o->ctr_drbg);
#ifdef MBEDTLS_DEBUG_C
mbedtls_ssl_conf_dbg(&o->conf, mbedtls_debug, NULL);
#endif
ret = mbedtls_ssl_setup(&o->ssl, &o->conf);
if (ret != 0) {
goto cleanup;
}
if (args->server_hostname.u_obj != mp_const_none) {
const char *sni = mp_obj_str_get_str(args->server_hostname.u_obj);
ret = mbedtls_ssl_set_hostname(&o->ssl, sni);
if (ret != 0) {
goto cleanup;
}
}
mbedtls_ssl_set_bio(&o->ssl, &o->sock, _mbedtls_ssl_send, _mbedtls_ssl_recv, NULL);
if (args->key.u_obj != mp_const_none) {
size_t key_len;
const byte *key = (const byte *)mp_obj_str_get_data(args->key.u_obj, &key_len);
// len should include terminating null
ret = mbedtls_pk_parse_key(&o->pkey, key, key_len + 1, NULL, 0);
if (ret != 0) {
ret = MBEDTLS_ERR_PK_BAD_INPUT_DATA; // use general error for all key errors
goto cleanup;
}
size_t cert_len;
const byte *cert = (const byte *)mp_obj_str_get_data(args->cert.u_obj, &cert_len);
// len should include terminating null
ret = mbedtls_x509_crt_parse(&o->cert, cert, cert_len + 1);
if (ret != 0) {
ret = MBEDTLS_ERR_X509_BAD_INPUT_DATA; // use general error for all cert errors
goto cleanup;
}
ret = mbedtls_ssl_conf_own_cert(&o->conf, &o->cert, &o->pkey);
if (ret != 0) {
goto cleanup;
}
}
if (args->cadata.u_obj != mp_const_none) {
size_t cacert_len;
const byte *cacert = (const byte *)mp_obj_str_get_data(args->cadata.u_obj, &cacert_len);
// len should include terminating null
ret = mbedtls_x509_crt_parse(&o->cacert, cacert, cacert_len + 1);
if (ret != 0) {
ret = MBEDTLS_ERR_X509_BAD_INPUT_DATA; // use general error for all cert errors
goto cleanup;
}
mbedtls_ssl_conf_ca_chain(&o->conf, &o->cacert, NULL);
}
if (args->do_handshake.u_bool) {
while ((ret = mbedtls_ssl_handshake(&o->ssl)) != 0) {
if (ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE) {
goto cleanup;
}
#ifdef MICROPY_EVENT_POLL_HOOK
MICROPY_EVENT_POLL_HOOK
#endif
}
}
return o;
cleanup:
mbedtls_pk_free(&o->pkey);
mbedtls_x509_crt_free(&o->cert);
mbedtls_x509_crt_free(&o->cacert);
mbedtls_ssl_free(&o->ssl);
mbedtls_ssl_config_free(&o->conf);
mbedtls_ctr_drbg_free(&o->ctr_drbg);
mbedtls_entropy_free(&o->entropy);
if (ret == MBEDTLS_ERR_SSL_ALLOC_FAILED) {
mp_raise_OSError(MP_ENOMEM);
} else if (ret == MBEDTLS_ERR_PK_BAD_INPUT_DATA) {
mp_raise_ValueError(MP_ERROR_TEXT("invalid key"));
} else if (ret == MBEDTLS_ERR_X509_BAD_INPUT_DATA) {
mp_raise_ValueError(MP_ERROR_TEXT("invalid cert"));
} else {
mbedtls_raise_error(ret);
}
}
STATIC mp_obj_t mod_ssl_getpeercert(mp_obj_t o_in, mp_obj_t binary_form) {
mp_obj_ssl_socket_t *o = MP_OBJ_TO_PTR(o_in);
if (!mp_obj_is_true(binary_form)) {
mp_raise_NotImplementedError(NULL);
}
const mbedtls_x509_crt *peer_cert = mbedtls_ssl_get_peer_cert(&o->ssl);
if (peer_cert == NULL) {
return mp_const_none;
}
return mp_obj_new_bytes(peer_cert->raw.p, peer_cert->raw.len);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_ssl_getpeercert_obj, mod_ssl_getpeercert);
STATIC void socket_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
(void)kind;
mp_obj_ssl_socket_t *self = MP_OBJ_TO_PTR(self_in);
mp_printf(print, "<_SSLSocket %p>", self);
}
STATIC mp_uint_t socket_read(mp_obj_t o_in, void *buf, mp_uint_t size, int *errcode) {
mp_obj_ssl_socket_t *o = MP_OBJ_TO_PTR(o_in);
int ret = mbedtls_ssl_read(&o->ssl, buf, size);
if (ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY) {
// end of stream
return 0;
}
if (ret >= 0) {
return ret;
}
if (ret == MBEDTLS_ERR_SSL_WANT_READ) {
ret = MP_EWOULDBLOCK;
} else if (ret == MBEDTLS_ERR_SSL_WANT_WRITE) {
// If handshake is not finished, read attempt may end up in protocol
// wanting to write next handshake message. The same may happen with
// renegotation.
ret = MP_EWOULDBLOCK;
}
*errcode = ret;
return MP_STREAM_ERROR;
}
STATIC mp_uint_t socket_write(mp_obj_t o_in, const void *buf, mp_uint_t size, int *errcode) {
mp_obj_ssl_socket_t *o = MP_OBJ_TO_PTR(o_in);
int ret = mbedtls_ssl_write(&o->ssl, buf, size);
if (ret >= 0) {
return ret;
}
if (ret == MBEDTLS_ERR_SSL_WANT_WRITE) {
ret = MP_EWOULDBLOCK;
} else if (ret == MBEDTLS_ERR_SSL_WANT_READ) {
// If handshake is not finished, write attempt may end up in protocol
// wanting to read next handshake message. The same may happen with
// renegotation.
ret = MP_EWOULDBLOCK;
}
*errcode = ret;
return MP_STREAM_ERROR;
}
STATIC mp_obj_t socket_setblocking(mp_obj_t self_in, mp_obj_t flag_in) {
mp_obj_ssl_socket_t *o = MP_OBJ_TO_PTR(self_in);
mp_obj_t sock = o->sock;
mp_obj_t dest[3];
mp_load_method(sock, MP_QSTR_setblocking, dest);
dest[2] = flag_in;
return mp_call_method_n_kw(1, 0, dest);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_2(socket_setblocking_obj, socket_setblocking);
STATIC mp_uint_t socket_ioctl(mp_obj_t o_in, mp_uint_t request, uintptr_t arg, int *errcode) {
mp_obj_ssl_socket_t *self = MP_OBJ_TO_PTR(o_in);
if (request == MP_STREAM_CLOSE) {
mbedtls_pk_free(&self->pkey);
mbedtls_x509_crt_free(&self->cert);
mbedtls_x509_crt_free(&self->cacert);
mbedtls_ssl_free(&self->ssl);
mbedtls_ssl_config_free(&self->conf);
mbedtls_ctr_drbg_free(&self->ctr_drbg);
mbedtls_entropy_free(&self->entropy);
}
// Pass all requests down to the underlying socket
return mp_get_stream(self->sock)->ioctl(self->sock, request, arg, errcode);
}
STATIC const mp_rom_map_elem_t ussl_socket_locals_dict_table[] = {
{ MP_ROM_QSTR(MP_QSTR_read), MP_ROM_PTR(&mp_stream_read_obj) },
{ MP_ROM_QSTR(MP_QSTR_readinto), MP_ROM_PTR(&mp_stream_readinto_obj) },
{ MP_ROM_QSTR(MP_QSTR_readline), MP_ROM_PTR(&mp_stream_unbuffered_readline_obj) },
{ MP_ROM_QSTR(MP_QSTR_write), MP_ROM_PTR(&mp_stream_write_obj) },
{ MP_ROM_QSTR(MP_QSTR_setblocking), MP_ROM_PTR(&socket_setblocking_obj) },
{ MP_ROM_QSTR(MP_QSTR_close), MP_ROM_PTR(&mp_stream_close_obj) },
#if MICROPY_PY_USSL_FINALISER
{ MP_ROM_QSTR(MP_QSTR___del__), MP_ROM_PTR(&mp_stream_close_obj) },
#endif
{ MP_ROM_QSTR(MP_QSTR_getpeercert), MP_ROM_PTR(&mod_ssl_getpeercert_obj) },
};
STATIC MP_DEFINE_CONST_DICT(ussl_socket_locals_dict, ussl_socket_locals_dict_table);
STATIC const mp_stream_p_t ussl_socket_stream_p = {
.read = socket_read,
.write = socket_write,
.ioctl = socket_ioctl,
};
STATIC MP_DEFINE_CONST_OBJ_TYPE(
ussl_socket_type,
MP_QSTR_ussl,
MP_TYPE_FLAG_NONE,
// Save on qstr's, reuse same as for module
print, socket_print,
protocol, &ussl_socket_stream_p,
locals_dict, &ussl_socket_locals_dict
);
STATIC mp_obj_t mod_ssl_wrap_socket(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
// TODO: Implement more args
static const mp_arg_t allowed_args[] = {
{ MP_QSTR_key, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
{ MP_QSTR_cert, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
{ MP_QSTR_server_side, MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
{ MP_QSTR_server_hostname, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
{ MP_QSTR_cert_reqs, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = MBEDTLS_SSL_VERIFY_NONE}},
{ MP_QSTR_cadata, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
{ MP_QSTR_do_handshake, MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = true} },
};
// TODO: Check that sock implements stream protocol
mp_obj_t sock = pos_args[0];
struct ssl_args args;
mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args,
MP_ARRAY_SIZE(allowed_args), allowed_args, (mp_arg_val_t *)&args);
return MP_OBJ_FROM_PTR(socket_new(sock, &args));
}
STATIC MP_DEFINE_CONST_FUN_OBJ_KW(mod_ssl_wrap_socket_obj, 1, mod_ssl_wrap_socket);
STATIC const mp_rom_map_elem_t mp_module_ssl_globals_table[] = {
{ MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_ussl) },
{ MP_ROM_QSTR(MP_QSTR_wrap_socket), MP_ROM_PTR(&mod_ssl_wrap_socket_obj) },
{ MP_ROM_QSTR(MP_QSTR_CERT_NONE), MP_ROM_INT(MBEDTLS_SSL_VERIFY_NONE) },
{ MP_ROM_QSTR(MP_QSTR_CERT_OPTIONAL), MP_ROM_INT(MBEDTLS_SSL_VERIFY_OPTIONAL) },
{ MP_ROM_QSTR(MP_QSTR_CERT_REQUIRED), MP_ROM_INT(MBEDTLS_SSL_VERIFY_REQUIRED) },
};
STATIC MP_DEFINE_CONST_DICT(mp_module_ssl_globals, mp_module_ssl_globals_table);
const mp_obj_module_t mp_module_ussl = {
.base = { &mp_type_module },
.globals = (mp_obj_dict_t *)&mp_module_ssl_globals,
};
MP_REGISTER_MODULE(MP_QSTR_ussl, mp_module_ussl);
#endif // MICROPY_PY_USSL && MICROPY_SSL_MBEDTLS
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