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[crypto] Simplify internal HMAC API

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Simplify the internal HMAC API so that the key is provided only at the
point of calling hmac_init(), and the (potentially reduced) key is
stored as part of the context for later use by hmac_final().

This simplifies the calling code, and avoids the need for callers such
as TLS to allocate a potentially variable length block in order to
retain a copy of the unmodified key.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown
2022-10-09 15:14:41 +01:00
parent 88419b608d
commit 007d3cb800
16 changed files with 142 additions and 163 deletions
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51
src/net/tls.c
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@@ -458,17 +458,17 @@ static int tls_generate_random ( struct tls_connection *tls,
* Update HMAC with a list of ( data, len ) pairs
*
* @v digest Hash function to use
* @v digest_ctx Digest context
* @v ctx HMAC context
* @v args ( data, len ) pairs of data, terminated by NULL
*/
static void tls_hmac_update_va ( struct digest_algorithm *digest,
void *digest_ctx, va_list args ) {
void *ctx, va_list args ) {
void *data;
size_t len;
while ( ( data = va_arg ( args, void * ) ) ) {
len = va_arg ( args, size_t );
hmac_update ( digest, digest_ctx, data, len );
hmac_update ( digest, ctx, data, len );
}
}
@@ -485,43 +485,38 @@ static void tls_hmac_update_va ( struct digest_algorithm *digest,
*/
static void tls_p_hash_va ( struct tls_connection *tls,
struct digest_algorithm *digest,
void *secret, size_t secret_len,
const void *secret, size_t secret_len,
void *out, size_t out_len,
va_list seeds ) {
uint8_t secret_copy[secret_len];
uint8_t digest_ctx[digest->ctxsize];
uint8_t digest_ctx_partial[digest->ctxsize];
uint8_t ctx[ hmac_ctxsize ( digest ) ];
uint8_t ctx_partial[ sizeof ( ctx ) ];
uint8_t a[digest->digestsize];
uint8_t out_tmp[digest->digestsize];
size_t frag_len = digest->digestsize;
va_list tmp;
/* Copy the secret, in case HMAC modifies it */
memcpy ( secret_copy, secret, secret_len );
secret = secret_copy;
DBGC2 ( tls, "TLS %p %s secret:\n", tls, digest->name );
DBGC2_HD ( tls, secret, secret_len );
/* Calculate A(1) */
hmac_init ( digest, digest_ctx, secret, &secret_len );
hmac_init ( digest, ctx, secret, secret_len );
va_copy ( tmp, seeds );
tls_hmac_update_va ( digest, digest_ctx, tmp );
tls_hmac_update_va ( digest, ctx, tmp );
va_end ( tmp );
hmac_final ( digest, digest_ctx, secret, &secret_len, a );
hmac_final ( digest, ctx, a );
DBGC2 ( tls, "TLS %p %s A(1):\n", tls, digest->name );
DBGC2_HD ( tls, &a, sizeof ( a ) );
/* Generate as much data as required */
while ( out_len ) {
/* Calculate output portion */
hmac_init ( digest, digest_ctx, secret, &secret_len );
hmac_update ( digest, digest_ctx, a, sizeof ( a ) );
memcpy ( digest_ctx_partial, digest_ctx, digest->ctxsize );
hmac_init ( digest, ctx, secret, secret_len );
hmac_update ( digest, ctx, a, sizeof ( a ) );
memcpy ( ctx_partial, ctx, sizeof ( ctx_partial ) );
va_copy ( tmp, seeds );
tls_hmac_update_va ( digest, digest_ctx, tmp );
tls_hmac_update_va ( digest, ctx, tmp );
va_end ( tmp );
hmac_final ( digest, digest_ctx,
secret, &secret_len, out_tmp );
hmac_final ( digest, ctx, out_tmp );
/* Copy output */
if ( frag_len > out_len )
@@ -531,8 +526,7 @@ static void tls_p_hash_va ( struct tls_connection *tls,
DBGC2_HD ( tls, out, frag_len );
/* Calculate A(i) */
hmac_final ( digest, digest_ctx_partial,
secret, &secret_len, a );
hmac_final ( digest, ctx_partial, a );
DBGC2 ( tls, "TLS %p %s A(n):\n", tls, digest->name );
DBGC2_HD ( tls, &a, sizeof ( a ) );
@@ -551,13 +545,13 @@ static void tls_p_hash_va ( struct tls_connection *tls,
* @v out_len Length of output buffer
* @v ... ( data, len ) pairs of seed data, terminated by NULL
*/
static void tls_prf ( struct tls_connection *tls, void *secret,
static void tls_prf ( struct tls_connection *tls, const void *secret,
size_t secret_len, void *out, size_t out_len, ... ) {
va_list seeds;
va_list tmp;
size_t subsecret_len;
void *md5_secret;
void *sha1_secret;
const void *md5_secret;
const void *sha1_secret;
uint8_t buf[out_len];
unsigned int i;
@@ -2213,7 +2207,7 @@ static void tls_hmac_init ( struct tls_cipherspec *cipherspec, void *ctx,
uint64_t seq, struct tls_header *tlshdr ) {
struct digest_algorithm *digest = cipherspec->suite->digest;
hmac_init ( digest, ctx, cipherspec->mac_secret, &digest->digestsize );
hmac_init ( digest, ctx, cipherspec->mac_secret, digest->digestsize );
seq = cpu_to_be64 ( seq );
hmac_update ( digest, ctx, &seq, sizeof ( seq ) );
hmac_update ( digest, ctx, tlshdr, sizeof ( *tlshdr ) );
@@ -2245,8 +2239,7 @@ static void tls_hmac_final ( struct tls_cipherspec *cipherspec, void *ctx,
void *hmac ) {
struct digest_algorithm *digest = cipherspec->suite->digest;
hmac_final ( digest, ctx, cipherspec->mac_secret,
&digest->digestsize, hmac );
hmac_final ( digest, ctx, hmac );
}
/**
@@ -2263,7 +2256,7 @@ static void tls_hmac ( struct tls_cipherspec *cipherspec,
uint64_t seq, struct tls_header *tlshdr,
const void *data, size_t len, void *hmac ) {
struct digest_algorithm *digest = cipherspec->suite->digest;
uint8_t ctx[digest->ctxsize];
uint8_t ctx[ hmac_ctxsize ( digest ) ];
tls_hmac_init ( cipherspec, ctx, seq, tlshdr );
tls_hmac_update ( cipherspec, ctx, data, len );
@@ -2545,7 +2538,7 @@ static int tls_new_ciphertext ( struct tls_connection *tls,
struct tls_cipherspec *cipherspec = &tls->rx_cipherspec;
struct cipher_algorithm *cipher = cipherspec->suite->cipher;
struct digest_algorithm *digest = cipherspec->suite->digest;
uint8_t ctx[digest->ctxsize];
uint8_t ctx[ hmac_ctxsize ( digest ) ];
uint8_t verify_mac[digest->digestsize];
struct io_buffer *iobuf;
void *mac;