cosmopolitan/third_party/mbedtls/ssl_tls13_keys.c
Justine Tunney cc1920749e Add SSL to redbean
Your redbean can now interoperate with clients that require TLS crypto.
This is accomplished using a protocol polyglot that lets us distinguish
between HTTP and HTTPS regardless of the port number. Certificates will
be generated automatically, if none are supplied by the user. Footprint
increases by only a few hundred kb so redbean in MODY=tiny is now 1.0mb

- Add lseek() polyfills for ZIP executable
- Automatically polyfill /tmp/FOO paths on NT
- Fix readdir() / ftw() / nftw() bugs on Windows
- Introduce -B flag for slower SSL that's stronger
- Remove mbedtls features Cosmopolitan doesn't need
- Have base64 decoder support the uri-safe alternative
- Remove Truncated HMAC because it's forbidden by the IETF
- Add all the mbedtls test suites and make them go 3x faster
- Support opendir() / readdir() / closedir() on ZIP executable
- Use Everest for ECDHE-ECDSA because it's so good it's so good
- Add tinier implementation of sha1 since it's not worth the rom
- Add chi-square monte-carlo mean correlation tests for getrandom()
- Source entropy on Windows from the proper interface everyone uses

We're continuing to outperform NGINX and other servers on raw message
throughput. Using SSL means that instead of 1,000,000 qps you can get
around 300,000 qps. However redbean isn't as fast as NGINX yet at SSL
handshakes, since redbean can do 2,627 per second and NGINX does 4.3k

Right now, the SSL UX story works best if you give your redbean a key
signing key since that can be easily generated by openssl using a one
liner then redbean will do all the things that are impossibly hard to
do like signing ecdsa and rsa certificates that'll work in chrome. We
should integrate the let's encrypt acme protocol in the future.

Live Demo: https://redbean.justine.lol/
Root Cert: https://redbean.justine.lol/redbean1.crt
2021-06-24 13:20:50 -07:00

508 lines
19 KiB
C

#include "third_party/mbedtls/common.h"
#include "third_party/mbedtls/hkdf.h"
#include "third_party/mbedtls/ssl_internal.h"
#include "third_party/mbedtls/ssl_tls13_keys.h"
asm(".ident\t\"\\n\\n\
Mbed TLS (Apache 2.0)\\n\
Copyright ARM Limited\\n\
Copyright Mbed TLS Contributors\"");
asm(".include \"libc/disclaimer.inc\"");
/* clang-format off */
/*
* TLS 1.3 key schedule
*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 ( the "License" ); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
#define MBEDTLS_SSL_TLS1_3_LABEL( name, string ) \
.name = string,
struct mbedtls_ssl_tls1_3_labels_struct const mbedtls_ssl_tls1_3_labels =
{
/* This seems to work in C, despite the string literal being one
* character too long due to the 0-termination. */
MBEDTLS_SSL_TLS1_3_LABEL_LIST
};
#undef MBEDTLS_SSL_TLS1_3_LABEL
/*
* This function creates a HkdfLabel structure used in the TLS 1.3 key schedule.
*
* The HkdfLabel is specified in RFC 8446 as follows:
*
* struct HkdfLabel {
* uint16 length; // Length of expanded key material
* opaque label<7..255>; // Always prefixed by "tls13 "
* opaque context<0..255>; // Usually a communication transcript hash
* };
*
* Parameters:
* - desired_length: Length of expanded key material
* Even though the standard allows expansion to up to
* 2**16 Bytes, TLS 1.3 never uses expansion to more than
* 255 Bytes, so we require `desired_length` to be at most
* 255. This allows us to save a few Bytes of code by
* hardcoding the writing of the high bytes.
* - (label, llen): label + label length, without "tls13 " prefix
* The label length MUST be less than or equal to
* MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_LABEL_LEN
* It is the caller's responsibility to ensure this.
* All (label, label length) pairs used in TLS 1.3
* can be obtained via MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN().
* - (ctx, clen): context + context length
* The context length MUST be less than or equal to
* MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_CONTEXT_LEN
* It is the caller's responsibility to ensure this.
* - dst: Target buffer for HkdfLabel structure,
* This MUST be a writable buffer of size
* at least SSL_TLS1_3_KEY_SCHEDULE_MAX_HKDF_LABEL_LEN Bytes.
* - dlen: Pointer at which to store the actual length of
* the HkdfLabel structure on success.
*/
static const char tls1_3_label_prefix[6] = "tls13 ";
#define SSL_TLS1_3_KEY_SCHEDULE_HKDF_LABEL_LEN( label_len, context_len ) \
( 2 /* expansion length */ \
+ 1 /* label length */ \
+ label_len \
+ 1 /* context length */ \
+ context_len )
#define SSL_TLS1_3_KEY_SCHEDULE_MAX_HKDF_LABEL_LEN \
SSL_TLS1_3_KEY_SCHEDULE_HKDF_LABEL_LEN( \
sizeof(tls1_3_label_prefix) + \
MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_LABEL_LEN, \
MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_CONTEXT_LEN )
static void ssl_tls1_3_hkdf_encode_label(
size_t desired_length,
const unsigned char *label, size_t llen,
const unsigned char *ctx, size_t clen,
unsigned char *dst, size_t *dlen )
{
size_t total_label_len =
sizeof(tls1_3_label_prefix) + llen;
size_t total_hkdf_lbl_len =
SSL_TLS1_3_KEY_SCHEDULE_HKDF_LABEL_LEN( total_label_len, clen );
unsigned char *p = dst;
/* Add the size of the expanded key material.
* We're hardcoding the high byte to 0 here assuming that we never use
* TLS 1.3 HKDF key expansion to more than 255 Bytes. */
#if MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_EXPANSION_LEN > 255
#error "The implementation of ssl_tls1_3_hkdf_encode_label() is not fit for the \
value of MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_EXPANSION_LEN"
#endif
*p++ = 0;
*p++ = (unsigned char)( ( desired_length >> 0 ) & 0xFF );
/* Add label incl. prefix */
*p++ = (unsigned char)( total_label_len & 0xFF );
memcpy( p, tls1_3_label_prefix, sizeof(tls1_3_label_prefix) );
p += sizeof(tls1_3_label_prefix);
memcpy( p, label, llen );
p += llen;
/* Add context value */
*p++ = (unsigned char)( clen & 0xFF );
if( clen != 0 )
memcpy( p, ctx, clen );
/* Return total length to the caller. */
*dlen = total_hkdf_lbl_len;
}
/**
* \brief The \c HKDF-Expand-Label function from
* the TLS 1.3 standard RFC 8446.
*
* <tt>
* HKDF-Expand-Label( Secret, Label, Context, Length ) =
* HKDF-Expand( Secret, HkdfLabel, Length )
* </tt>
*
* \param hash_alg The identifier for the hash algorithm to use.
* \param secret The \c Secret argument to \c HKDF-Expand-Label.
* This must be a readable buffer of length \p slen Bytes.
* \param slen The length of \p secret in Bytes.
* \param label The \c Label argument to \c HKDF-Expand-Label.
* This must be a readable buffer of length \p llen Bytes.
* \param llen The length of \p label in Bytes.
* \param ctx The \c Context argument to \c HKDF-Expand-Label.
* This must be a readable buffer of length \p clen Bytes.
* \param clen The length of \p context in Bytes.
* \param buf The destination buffer to hold the expanded secret.
* This must be a writable buffer of length \p blen Bytes.
* \param blen The desired size of the expanded secret in Bytes.
*
* \returns \c 0 on success.
* \return A negative error code on failure.
*/
int mbedtls_ssl_tls1_3_hkdf_expand_label(
mbedtls_md_type_t hash_alg,
const unsigned char *secret, size_t slen,
const unsigned char *label, size_t llen,
const unsigned char *ctx, size_t clen,
unsigned char *buf, size_t blen )
{
const mbedtls_md_info_t *md;
unsigned char hkdf_label[ SSL_TLS1_3_KEY_SCHEDULE_MAX_HKDF_LABEL_LEN ];
size_t hkdf_label_len;
if( llen > MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_LABEL_LEN )
{
/* Should never happen since this is an internal
* function, and we know statically which labels
* are allowed. */
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
if( clen > MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_CONTEXT_LEN )
{
/* Should not happen, as above. */
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
if( blen > MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_EXPANSION_LEN )
{
/* Should not happen, as above. */
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
md = mbedtls_md_info_from_type( hash_alg );
if( md == NULL )
return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
ssl_tls1_3_hkdf_encode_label( blen,
label, llen,
ctx, clen,
hkdf_label,
&hkdf_label_len );
return( mbedtls_hkdf_expand( md,
secret, slen,
hkdf_label, hkdf_label_len,
buf, blen ) );
}
/**
* \brief This function is part of the TLS 1.3 key schedule.
* It extracts key and IV for the actual client/server traffic
* from the client/server traffic secrets.
*
* From RFC 8446:
*
* <tt>
* [sender]_write_key = HKDF-Expand-Label(Secret, "key", "", key_length)
* [sender]_write_iv = HKDF-Expand-Label(Secret, "iv", "", iv_length)*
* </tt>
*
* The traffic keying material is generated from the following inputs:
*
* - One secret value per sender.
* - A purpose value indicating the specific value being generated
* - The desired lengths of key and IV.
*
* The expansion itself is based on HKDF:
*
* [sender]_write_key = HKDF-Expand-Label( Secret, "key", "", key_length )
* [sender]_write_iv = HKDF-Expand-Label( Secret, "iv" , "", iv_length )
*
* [sender] denotes the sending side and the Secret value is provided
* by the function caller. Note that we generate server and client side
* keys in a single function call.
*
* \param hash_alg The identifier for the hash algorithm to be used
* for the HKDF-based expansion of the secret.
* \param client_secret The client traffic secret.
* This must be a readable buffer of size \p slen Bytes
* \param server_secret The server traffic secret.
* This must be a readable buffer of size \p slen Bytes
* \param slen Length of the secrets \p client_secret and
* \p server_secret in Bytes.
* \param key_len The desired length of the key to be extracted in Bytes.
* \param iv_len The desired length of the IV to be extracted in Bytes.
* \param keys The address of the structure holding the generated
* keys and IVs.
*
* \returns \c 0 on success.
* \returns A negative error code on failure.
*/
int mbedtls_ssl_tls1_3_make_traffic_keys(
mbedtls_md_type_t hash_alg,
const unsigned char *client_secret,
const unsigned char *server_secret,
size_t slen, size_t key_len, size_t iv_len,
mbedtls_ssl_key_set *keys )
{
int ret = 0;
ret = mbedtls_ssl_tls1_3_hkdf_expand_label( hash_alg,
client_secret, slen,
MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( key ),
NULL, 0,
keys->client_write_key, key_len );
if( ret != 0 )
return( ret );
ret = mbedtls_ssl_tls1_3_hkdf_expand_label( hash_alg,
server_secret, slen,
MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( key ),
NULL, 0,
keys->server_write_key, key_len );
if( ret != 0 )
return( ret );
ret = mbedtls_ssl_tls1_3_hkdf_expand_label( hash_alg,
client_secret, slen,
MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( iv ),
NULL, 0,
keys->client_write_iv, iv_len );
if( ret != 0 )
return( ret );
ret = mbedtls_ssl_tls1_3_hkdf_expand_label( hash_alg,
server_secret, slen,
MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( iv ),
NULL, 0,
keys->server_write_iv, iv_len );
if( ret != 0 )
return( ret );
keys->key_len = key_len;
keys->iv_len = iv_len;
return( 0 );
}
/**
* \brief The \c Derive-Secret function from the TLS 1.3 standard RFC 8446.
*
* <tt>
* Derive-Secret( Secret, Label, Messages ) =
* HKDF-Expand-Label( Secret, Label,
* Hash( Messages ),
* Hash.Length ) )
* </tt>
*
* \param hash_alg The identifier for the hash function used for the
* applications of HKDF.
* \param secret The \c Secret argument to the \c Derive-Secret function.
* This must be a readable buffer of length \p slen Bytes.
* \param slen The length of \p secret in Bytes.
* \param label The \c Label argument to the \c Derive-Secret function.
* This must be a readable buffer of length \p llen Bytes.
* \param llen The length of \p label in Bytes.
* \param ctx The hash of the \c Messages argument to the
* \c Derive-Secret function, or the \c Messages argument
* itself, depending on \p context_already_hashed.
* \param clen The length of \p hash.
* \param ctx_hashed This indicates whether the \p ctx contains the hash of
* the \c Messages argument in the application of the
* \c Derive-Secret function
* (value MBEDTLS_SSL_TLS1_3_CONTEXT_HASHED), or whether
* it is the content of \c Messages itself, in which case
* the function takes care of the hashing
* (value MBEDTLS_SSL_TLS1_3_CONTEXT_UNHASHED).
* \param dstbuf The target buffer to write the output of
* \c Derive-Secret to. This must be a writable buffer of
* size \p buflen Bytes.
* \param buflen The length of \p dstbuf in Bytes.
*
* \returns \c 0 on success.
* \returns A negative error code on failure.
*/
int mbedtls_ssl_tls1_3_derive_secret(
mbedtls_md_type_t hash_alg,
const unsigned char *secret, size_t slen,
const unsigned char *label, size_t llen,
const unsigned char *ctx, size_t clen,
int ctx_hashed,
unsigned char *dstbuf, size_t buflen )
{
int ret;
unsigned char hashed_context[ MBEDTLS_MD_MAX_SIZE ];
const mbedtls_md_info_t *md;
md = mbedtls_md_info_from_type( hash_alg );
if( md == NULL )
return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
if( ctx_hashed == MBEDTLS_SSL_TLS1_3_CONTEXT_UNHASHED )
{
ret = mbedtls_md( md, ctx, clen, hashed_context );
if( ret != 0 )
return( ret );
clen = mbedtls_md_get_size( md );
}
else
{
if( clen > sizeof(hashed_context) )
{
/* This should never happen since this function is internal
* and the code sets `ctx_hashed` correctly.
* Let's double-check nonetheless to not run at the risk
* of getting a stack overflow. */
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
memcpy( hashed_context, ctx, clen );
}
return( mbedtls_ssl_tls1_3_hkdf_expand_label( hash_alg,
secret, slen,
label, llen,
hashed_context, clen,
dstbuf, buflen ) );
}
/**
* \brief Compute the next secret in the TLS 1.3 key schedule
*
* The TLS 1.3 key schedule proceeds as follows to compute
* the three main secrets during the handshake: The early
* secret for early data, the handshake secret for all
* other encrypted handshake messages, and the master
* secret for all application traffic.
*
* <tt>
* 0
* |
* v
* PSK -> HKDF-Extract = Early Secret
* |
* v
* Derive-Secret( ., "derived", "" )
* |
* v
* (EC)DHE -> HKDF-Extract = Handshake Secret
* |
* v
* Derive-Secret( ., "derived", "" )
* |
* v
* 0 -> HKDF-Extract = Master Secret
* </tt>
*
* Each of the three secrets in turn is the basis for further
* key derivations, such as the derivation of traffic keys and IVs;
* see e.g. mbedtls_ssl_tls1_3_make_traffic_keys().
*
* This function implements one step in this evolution of secrets:
*
* <tt>
* old_secret
* |
* v
* Derive-Secret( ., "derived", "" )
* |
* v
* input -> HKDF-Extract = new_secret
* </tt>
*
* \param hash_alg The identifier for the hash function used for the
* applications of HKDF.
* \param secret_old The address of the buffer holding the old secret
* on function entry. If not \c NULL, this must be a
* readable buffer whose size matches the output size
* of the hash function represented by \p hash_alg.
* If \c NULL, an all \c 0 array will be used instead.
* \param input The address of the buffer holding the additional
* input for the key derivation (e.g., the PSK or the
* ephemeral (EC)DH secret). If not \c NULL, this must be
* a readable buffer whose size \p input_len Bytes.
* If \c NULL, an all \c 0 array will be used instead.
* \param input_len The length of \p input in Bytes.
* \param secret_new The address of the buffer holding the new secret
* on function exit. This must be a writable buffer
* whose size matches the output size of the hash
* function represented by \p hash_alg.
* This may be the same as \p secret_old.
*
* \returns \c 0 on success.
* \returns A negative error code on failure.
*/
int mbedtls_ssl_tls1_3_evolve_secret(
mbedtls_md_type_t hash_alg,
const unsigned char *secret_old,
const unsigned char *input, size_t input_len,
unsigned char *secret_new )
{
int ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR;
size_t hlen, ilen;
unsigned char tmp_secret[ MBEDTLS_MD_MAX_SIZE ] = { 0 };
unsigned char tmp_input [ MBEDTLS_MD_MAX_SIZE ] = { 0 };
const mbedtls_md_info_t *md;
md = mbedtls_md_info_from_type( hash_alg );
if( md == NULL )
return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
hlen = mbedtls_md_get_size( md );
/* For non-initial runs, call Derive-Secret( ., "derived", "")
* on the old secret. */
if( secret_old != NULL )
{
ret = mbedtls_ssl_tls1_3_derive_secret(
hash_alg,
secret_old, hlen,
MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( derived ),
NULL, 0, /* context */
MBEDTLS_SSL_TLS1_3_CONTEXT_UNHASHED,
tmp_secret, hlen );
if( ret != 0 )
goto cleanup;
}
if( input != NULL )
{
memcpy( tmp_input, input, input_len );
ilen = input_len;
}
else
{
ilen = hlen;
}
/* HKDF-Extract takes a salt and input key material.
* The salt is the old secret, and the input key material
* is the input secret (PSK / ECDHE). */
ret = mbedtls_hkdf_extract( md,
tmp_secret, hlen,
tmp_input, ilen,
secret_new );
if( ret != 0 )
goto cleanup;
ret = 0;
cleanup:
mbedtls_platform_zeroize( tmp_secret, sizeof(tmp_secret) );
mbedtls_platform_zeroize( tmp_input, sizeof(tmp_input) );
return( ret );
}
#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */