Merge remote-tracking branch 'restricted/pr/538' into mbedtls-2.14-restricted
diff --git a/ChangeLog b/ChangeLog
index 683240a..1e3ffbf 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -16,6 +16,15 @@
plaintexts and forge RSA signatures. Other asymmetric algorithms may
have been similarly vulnerable. Reported by Eyal Ronen, Robert Gillham,
Daniel Genkin, Adi Shamir, David Wong and Yuval Yarom.
+ * Wipe sensitive buffers on the stack in the CTR_DRBG and HMAC_DRBG
+ modules.
+
+API Changes
+ * The new functions mbedtls_ctr_drbg_update_ret() and
+ mbedtls_hmac_drbg_update_ret() are similar to mbedtls_ctr_drbg_update()
+ and mbedtls_hmac_drbg_update() respectively, but the new functions
+ report errors whereas the old functions return void. We recommend that
+ applications use the new functions.
= mbed TLS 2.14.0 branch released 2018-11-19
diff --git a/include/mbedtls/ctr_drbg.h b/include/mbedtls/ctr_drbg.h
index c91ca58..304bc91 100644
--- a/include/mbedtls/ctr_drbg.h
+++ b/include/mbedtls/ctr_drbg.h
@@ -237,20 +237,41 @@
const unsigned char *additional, size_t len );
/**
- * \brief This function updates the state of the CTR_DRBG context.
+ * \brief This function updates the state of the CTR_DRBG context.
*
- * \note If \p add_len is greater than
- * #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT, only the first
- * #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT Bytes are used.
- * The remaining Bytes are silently discarded.
+ * \param ctx The CTR_DRBG context.
+ * \param additional The data to update the state with.
+ * \param add_len Length of \p additional in bytes. This must be at
+ * most #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT.
*
- * \param ctx The CTR_DRBG context.
- * \param additional The data to update the state with.
- * \param add_len Length of \p additional data.
+ * \return \c 0 on success.
+ * \return #MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG if
+ * \p add_len is more than
+ * #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT.
+ * \return An error from the underlying AES cipher on failure.
+ */
+int mbedtls_ctr_drbg_update_ret( mbedtls_ctr_drbg_context *ctx,
+ const unsigned char *additional,
+ size_t add_len );
+
+/**
+ * \brief This function updates the state of the CTR_DRBG context.
*
+ * \warning This function cannot report errors. You should use
+ * mbedtls_ctr_drbg_update_ret() instead.
+ *
+ * \note If \p add_len is greater than
+ * #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT, only the first
+ * #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT Bytes are used.
+ * The remaining Bytes are silently discarded.
+ *
+ * \param ctx The CTR_DRBG context.
+ * \param additional The data to update the state with.
+ * \param add_len Length of \p additional data.
*/
void mbedtls_ctr_drbg_update( mbedtls_ctr_drbg_context *ctx,
- const unsigned char *additional, size_t add_len );
+ const unsigned char *additional,
+ size_t add_len );
/**
* \brief This function updates a CTR_DRBG instance with additional
diff --git a/include/mbedtls/hmac_drbg.h b/include/mbedtls/hmac_drbg.h
index 3bc675e..2e1108b 100644
--- a/include/mbedtls/hmac_drbg.h
+++ b/include/mbedtls/hmac_drbg.h
@@ -195,11 +195,31 @@
* \param additional Additional data to update state with, or NULL
* \param add_len Length of additional data, or 0
*
+ * \return \c 0 on success, or an error from the underlying
+ * hash calculation.
+ *
+ * \note Additional data is optional, pass NULL and 0 as second
+ * third argument if no additional data is being used.
+ */
+int mbedtls_hmac_drbg_update_ret( mbedtls_hmac_drbg_context *ctx,
+ const unsigned char *additional, size_t add_len );
+
+/**
+ * \brief HMAC_DRBG update state
+ *
+ * \warning This function cannot report errors. You should use
+ * mbedtls_hmac_drbg_update_ret() instead.
+ *
+ * \param ctx HMAC_DRBG context
+ * \param additional Additional data to update state with, or NULL
+ * \param add_len Length of additional data, or 0
+ *
* \note Additional data is optional, pass NULL and 0 as second
* third argument if no additional data is being used.
*/
void mbedtls_hmac_drbg_update( mbedtls_hmac_drbg_context *ctx,
- const unsigned char *additional, size_t add_len );
+ const unsigned char *additional,
+ size_t add_len );
/**
* \brief HMAC_DRBG reseeding (extracts data from entropy source)
diff --git a/library/ctr_drbg.c b/library/ctr_drbg.c
index fead18f..0655e76 100644
--- a/library/ctr_drbg.c
+++ b/library/ctr_drbg.c
@@ -299,9 +299,7 @@
* Crypt counter block
*/
if( ( ret = mbedtls_aes_crypt_ecb( &ctx->aes_ctx, MBEDTLS_AES_ENCRYPT, ctx->counter, p ) ) != 0 )
- {
- return( ret );
- }
+ goto exit;
p += MBEDTLS_CTR_DRBG_BLOCKSIZE;
}
@@ -313,12 +311,12 @@
* Update key and counter
*/
if( ( ret = mbedtls_aes_setkey_enc( &ctx->aes_ctx, tmp, MBEDTLS_CTR_DRBG_KEYBITS ) ) != 0 )
- {
- return( ret );
- }
+ goto exit;
memcpy( ctx->counter, tmp + MBEDTLS_CTR_DRBG_KEYSIZE, MBEDTLS_CTR_DRBG_BLOCKSIZE );
- return( 0 );
+exit:
+ mbedtls_platform_zeroize( tmp, sizeof( tmp ) );
+ return( ret );
}
/* CTR_DRBG_Instantiate with derivation function (SP 800-90A §10.2.1.3.2)
@@ -333,21 +331,36 @@
* and with outputs
* ctx = initial_working_state
*/
-void mbedtls_ctr_drbg_update( mbedtls_ctr_drbg_context *ctx,
- const unsigned char *additional, size_t add_len )
+int mbedtls_ctr_drbg_update_ret( mbedtls_ctr_drbg_context *ctx,
+ const unsigned char *additional,
+ size_t add_len )
{
unsigned char add_input[MBEDTLS_CTR_DRBG_SEEDLEN];
+ int ret;
- if( add_len > 0 )
- {
- /* MAX_INPUT would be more logical here, but we have to match
- * block_cipher_df()'s limits since we can't propagate errors */
- if( add_len > MBEDTLS_CTR_DRBG_MAX_SEED_INPUT )
- add_len = MBEDTLS_CTR_DRBG_MAX_SEED_INPUT;
+ if( add_len == 0 )
+ return( 0 );
- block_cipher_df( add_input, additional, add_len );
- ctr_drbg_update_internal( ctx, add_input );
- }
+ if( ( ret = block_cipher_df( add_input, additional, add_len ) ) != 0 )
+ goto exit;
+ if( ( ret = ctr_drbg_update_internal( ctx, add_input ) ) != 0 )
+ goto exit;
+
+exit:
+ mbedtls_platform_zeroize( add_input, sizeof( add_input ) );
+ return( ret );
+}
+
+/* Deprecated function, kept for backward compatibility. */
+void mbedtls_ctr_drbg_update( mbedtls_ctr_drbg_context *ctx,
+ const unsigned char *additional,
+ size_t add_len )
+{
+ /* MAX_INPUT would be more logical here, but we have to match
+ * block_cipher_df()'s limits since we can't propagate errors */
+ if( add_len > MBEDTLS_CTR_DRBG_MAX_SEED_INPUT )
+ add_len = MBEDTLS_CTR_DRBG_MAX_SEED_INPUT;
+ (void) mbedtls_ctr_drbg_update_ret( ctx, additional, add_len );
}
/* CTR_DRBG_Reseed with derivation function (SP 800-90A §10.2.1.4.2)
@@ -399,20 +412,18 @@
* Reduce to 384 bits
*/
if( ( ret = block_cipher_df( seed, seed, seedlen ) ) != 0 )
- {
- return( ret );
- }
+ goto exit;
/*
* Update state
*/
if( ( ret = ctr_drbg_update_internal( ctx, seed ) ) != 0 )
- {
- return( ret );
- }
+ goto exit;
ctx->reseed_counter = 1;
- return( 0 );
+exit:
+ mbedtls_platform_zeroize( seed, sizeof( seed ) );
+ return( ret );
}
/* CTR_DRBG_Generate with derivation function (SP 800-90A §10.2.1.5.2)
@@ -467,13 +478,9 @@
if( add_len > 0 )
{
if( ( ret = block_cipher_df( add_input, additional, add_len ) ) != 0 )
- {
- return( ret );
- }
+ goto exit;
if( ( ret = ctr_drbg_update_internal( ctx, add_input ) ) != 0 )
- {
- return( ret );
- }
+ goto exit;
}
while( output_len > 0 )
@@ -489,9 +496,7 @@
* Crypt counter block
*/
if( ( ret = mbedtls_aes_crypt_ecb( &ctx->aes_ctx, MBEDTLS_AES_ENCRYPT, ctx->counter, tmp ) ) != 0 )
- {
- return( ret );
- }
+ goto exit;
use_len = ( output_len > MBEDTLS_CTR_DRBG_BLOCKSIZE ) ? MBEDTLS_CTR_DRBG_BLOCKSIZE :
output_len;
@@ -504,12 +509,13 @@
}
if( ( ret = ctr_drbg_update_internal( ctx, add_input ) ) != 0 )
- {
- return( ret );
- }
+ goto exit;
ctx->reseed_counter++;
+exit:
+ mbedtls_platform_zeroize( add_input, sizeof( add_input ) );
+ mbedtls_platform_zeroize( tmp, sizeof( tmp ) );
return( 0 );
}
@@ -581,7 +587,7 @@
if( fread( buf, 1, n, f ) != n )
ret = MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR;
else
- mbedtls_ctr_drbg_update( ctx, buf, n );
+ ret = mbedtls_ctr_drbg_update_ret( ctx, buf, n );
fclose( f );
diff --git a/library/hmac_drbg.c b/library/hmac_drbg.c
index dad55ff..73c606b 100644
--- a/library/hmac_drbg.c
+++ b/library/hmac_drbg.c
@@ -66,29 +66,56 @@
/*
* HMAC_DRBG update, using optional additional data (10.1.2.2)
*/
-void mbedtls_hmac_drbg_update( mbedtls_hmac_drbg_context *ctx,
- const unsigned char *additional, size_t add_len )
+int mbedtls_hmac_drbg_update_ret( mbedtls_hmac_drbg_context *ctx,
+ const unsigned char *additional,
+ size_t add_len )
{
size_t md_len = mbedtls_md_get_size( ctx->md_ctx.md_info );
unsigned char rounds = ( additional != NULL && add_len != 0 ) ? 2 : 1;
unsigned char sep[1];
unsigned char K[MBEDTLS_MD_MAX_SIZE];
+ int ret;
for( sep[0] = 0; sep[0] < rounds; sep[0]++ )
{
/* Step 1 or 4 */
- mbedtls_md_hmac_reset( &ctx->md_ctx );
- mbedtls_md_hmac_update( &ctx->md_ctx, ctx->V, md_len );
- mbedtls_md_hmac_update( &ctx->md_ctx, sep, 1 );
+ if( ( ret = mbedtls_md_hmac_reset( &ctx->md_ctx ) ) != 0 )
+ goto exit;
+ if( ( ret = mbedtls_md_hmac_update( &ctx->md_ctx,
+ ctx->V, md_len ) ) != 0 )
+ goto exit;
+ if( ( ret = mbedtls_md_hmac_update( &ctx->md_ctx,
+ sep, 1 ) ) != 0 )
+ goto exit;
if( rounds == 2 )
- mbedtls_md_hmac_update( &ctx->md_ctx, additional, add_len );
- mbedtls_md_hmac_finish( &ctx->md_ctx, K );
+ {
+ if( ( ret = mbedtls_md_hmac_update( &ctx->md_ctx,
+ additional, add_len ) ) != 0 )
+ goto exit;
+ }
+ if( ( ret = mbedtls_md_hmac_finish( &ctx->md_ctx, K ) ) != 0 )
+ goto exit;
/* Step 2 or 5 */
- mbedtls_md_hmac_starts( &ctx->md_ctx, K, md_len );
- mbedtls_md_hmac_update( &ctx->md_ctx, ctx->V, md_len );
- mbedtls_md_hmac_finish( &ctx->md_ctx, ctx->V );
+ if( ( ret = mbedtls_md_hmac_starts( &ctx->md_ctx, K, md_len ) ) != 0 )
+ goto exit;
+ if( ( ret = mbedtls_md_hmac_update( &ctx->md_ctx,
+ ctx->V, md_len ) ) != 0 )
+ goto exit;
+ if( ( ret = mbedtls_md_hmac_finish( &ctx->md_ctx, ctx->V ) ) != 0 )
+ goto exit;
}
+
+exit:
+ mbedtls_platform_zeroize( K, sizeof( K ) );
+ return( ret );
+}
+
+void mbedtls_hmac_drbg_update( mbedtls_hmac_drbg_context *ctx,
+ const unsigned char *additional,
+ size_t add_len )
+{
+ (void) mbedtls_hmac_drbg_update_ret( ctx, additional, add_len );
}
/*
@@ -108,10 +135,13 @@
* Use the V memory location, which is currently all 0, to initialize the
* MD context with an all-zero key. Then set V to its initial value.
*/
- mbedtls_md_hmac_starts( &ctx->md_ctx, ctx->V, mbedtls_md_get_size( md_info ) );
+ if( ( ret = mbedtls_md_hmac_starts( &ctx->md_ctx, ctx->V,
+ mbedtls_md_get_size( md_info ) ) ) != 0 )
+ return( ret );
memset( ctx->V, 0x01, mbedtls_md_get_size( md_info ) );
- mbedtls_hmac_drbg_update( ctx, data, data_len );
+ if( ( ret = mbedtls_hmac_drbg_update_ret( ctx, data, data_len ) ) != 0 )
+ return( ret );
return( 0 );
}
@@ -124,6 +154,7 @@
{
unsigned char seed[MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT];
size_t seedlen;
+ int ret;
/* III. Check input length */
if( len > MBEDTLS_HMAC_DRBG_MAX_INPUT ||
@@ -135,7 +166,8 @@
memset( seed, 0, MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT );
/* IV. Gather entropy_len bytes of entropy for the seed */
- if( ctx->f_entropy( ctx->p_entropy, seed, ctx->entropy_len ) != 0 )
+ if( ( ret = ctx->f_entropy( ctx->p_entropy,
+ seed, ctx->entropy_len ) ) != 0 )
return( MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED );
seedlen = ctx->entropy_len;
@@ -148,13 +180,16 @@
}
/* 2. Update state */
- mbedtls_hmac_drbg_update( ctx, seed, seedlen );
+ if( ( ret = mbedtls_hmac_drbg_update_ret( ctx, seed, seedlen ) ) != 0 )
+ goto exit;
/* 3. Reset reseed_counter */
ctx->reseed_counter = 1;
+exit:
/* 4. Done */
- return( 0 );
+ mbedtls_platform_zeroize( seed, seedlen );
+ return( ret );
}
/*
@@ -180,7 +215,8 @@
* Use the V memory location, which is currently all 0, to initialize the
* MD context with an all-zero key. Then set V to its initial value.
*/
- mbedtls_md_hmac_starts( &ctx->md_ctx, ctx->V, md_size );
+ if( ( ret = mbedtls_md_hmac_starts( &ctx->md_ctx, ctx->V, md_size ) ) != 0 )
+ return( ret );
memset( ctx->V, 0x01, md_size );
ctx->f_entropy = f_entropy;
@@ -273,16 +309,24 @@
/* 2. Use additional data if any */
if( additional != NULL && add_len != 0 )
- mbedtls_hmac_drbg_update( ctx, additional, add_len );
+ {
+ if( ( ret = mbedtls_hmac_drbg_update_ret( ctx,
+ additional, add_len ) ) != 0 )
+ goto exit;
+ }
/* 3, 4, 5. Generate bytes */
while( left != 0 )
{
size_t use_len = left > md_len ? md_len : left;
- mbedtls_md_hmac_reset( &ctx->md_ctx );
- mbedtls_md_hmac_update( &ctx->md_ctx, ctx->V, md_len );
- mbedtls_md_hmac_finish( &ctx->md_ctx, ctx->V );
+ if( ( ret = mbedtls_md_hmac_reset( &ctx->md_ctx ) ) != 0 )
+ goto exit;
+ if( ( ret = mbedtls_md_hmac_update( &ctx->md_ctx,
+ ctx->V, md_len ) ) != 0 )
+ goto exit;
+ if( ( ret = mbedtls_md_hmac_finish( &ctx->md_ctx, ctx->V ) ) != 0 )
+ goto exit;
memcpy( out, ctx->V, use_len );
out += use_len;
@@ -290,13 +334,16 @@
}
/* 6. Update */
- mbedtls_hmac_drbg_update( ctx, additional, add_len );
+ if( ( ret = mbedtls_hmac_drbg_update_ret( ctx,
+ additional, add_len ) ) != 0 )
+ goto exit;
/* 7. Update reseed counter */
ctx->reseed_counter++;
+exit:
/* 8. Done */
- return( 0 );
+ return( ret );
}
/*
@@ -388,7 +435,7 @@
if( fread( buf, 1, n, f ) != n )
ret = MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR;
else
- mbedtls_hmac_drbg_update( ctx, buf, n );
+ ret = mbedtls_hmac_drbg_update_ret( ctx, buf, n );
fclose( f );
diff --git a/tests/suites/test_suite_ctr_drbg.function b/tests/suites/test_suite_ctr_drbg.function
index f10e98a..4a97826 100644
--- a/tests/suites/test_suite_ctr_drbg.function
+++ b/tests/suites/test_suite_ctr_drbg.function
@@ -244,9 +244,11 @@
}
TEST_ASSERT( last_idx == test_offset_idx );
- /* Call update with too much data (sizeof entropy > MAX(_SEED)_INPUT)
- * (just make sure it doesn't cause memory corruption) */
- mbedtls_ctr_drbg_update( &ctx, entropy, sizeof( entropy ) );
+ /* Call update with too much data (sizeof entropy > MAX(_SEED)_INPUT).
+ * Make sure it's detected as an error and doesn't cause memory
+ * corruption. */
+ TEST_ASSERT( mbedtls_ctr_drbg_update_ret(
+ &ctx, entropy, sizeof( entropy ) ) != 0 );
/* Now enable PR, so the next few calls should all reseed */
mbedtls_ctr_drbg_set_prediction_resistance( &ctx, MBEDTLS_CTR_DRBG_PR_ON );