Merge pull request #715 from ARMmbed/merge-2.7.16-release-to-mbedtls-2.7

Merge 2.7.16 release to mbedtls 2.7

ChangeLog

@@ -1,5 +1,57 @@
 mbed TLS ChangeLog (Sorted per branch, date)
 
+= mbed TLS 2.7.16 branch released 2020-07-01
+
+Security
+   * Fix a side channel vulnerability in modular exponentiation that could
+     reveal an RSA private key used in a secure enclave. Noticed by Sangho Lee,
+     Ming-Wei Shih, Prasun Gera, Taesoo Kim and Hyesoon Kim (Georgia Institute
+     of Technology); and Marcus Peinado (Microsoft Research). Reported by Raoul
+     Strackx (Fortanix) in #3394.
+   * Fix side channel in mbedtls_ecp_check_pub_priv() and
+     mbedtls_pk_parse_key() / mbedtls_pk_parse_keyfile() (when loading a
+     private key that didn't include the uncompressed public key), as well as
+     mbedtls_ecp_mul() / mbedtls_ecp_mul_restartable() when called with a NULL
+     f_rng argument. An attacker with access to precise enough timing and
+     memory access information (typically an untrusted operating system
+     attacking a secure enclave) could fully recover the ECC private key.
+     Found and reported by Alejandro Cabrera Aldaya and Billy Brumley.
+   * Fix issue in Lucky 13 counter-measure that could make it ineffective when
+     hardware accelerators were used (using one of the MBEDTLS_SHAxxx_ALT
+     macros). This would cause the original Lucky 13 attack to be possible in
+     those configurations, allowing an active network attacker to recover
+     plaintext after repeated timing measurements under some conditions.
+     Reported and fix suggested by Luc Perneel in #3246.
+
+Bugfix
+   * Fix the Visual Studio Release x64 build configuration for mbedtls itself.
+     Completes a previous fix in Mbed TLS 2.7.12 that only fixed the build for
+     the example programs. Reported in #1430 and fix contributed by irwir.
+   * Fix undefined behavior in X.509 certificate parsing if the
+     pathLenConstraint basic constraint value is equal to INT_MAX.
+     The actual effect with almost every compiler is the intended
+     behavior, so this is unlikely to be exploitable anywhere. #3196
+   * Include asn1.h in error.c. Fixes #3328 reported by David Hu.
+   * Fix potential memory leaks in ecp_randomize_jac() and ecp_randomize_mxz()
+     when PRNG function fails. Contributed by Jonas Lejeune in #3318.
+   * Add additional bounds checks in ssl_write_client_hello() preventing
+     output buffer overflow if the configuration declared a buffer that was
+     too small.
+
+Changes
+   * Unify the example programs termination to call mbedtls_exit() instead of
+     using a return command. This has been done to enable customization of the
+     behavior in bare metal environments.
+   * Abort the ClientHello writing function as soon as some extension doesn't
+     fit into the record buffer. Previously, such extensions were silently
+     dropped. As a consequence, the TLS handshake now fails when the output
+     buffer is not large enough to hold the ClientHello.
+   * The ECP module, enabled by `MBEDTLS_ECP_C`, now depends on
+     `MBEDTLS_CTR_DRBG_C`, `MBEDTLS_HMAC_DRBG_C`, `MBEDTLS_SHA512_C` or
+     `MBEDTLS_SHA256_C` for some side-channel coutermeasures. If side channels
+     are not a concern, this dependency can be avoided by enabling the new
+     option `MBEDTLS_ECP_NO_INTERNAL_RNG`.
+
 = mbed TLS 2.7.15 branch released 2020-04-14
 
 Security

ChangeLog.d/bugfix.txt

@@ -1,4 +0,0 @@
-Bugfix
-   * Fix the Visual Studio Release x64 build configuration for mbedtls itself.
-     Completes a previous fix in Mbed TLS 2.7.12 that only fixed the build for
-     the example programs. Reported in #1430 and fix contributed by irwir.

ChangeLog.d/error-asn1.txt

@@ -1,2 +0,0 @@
-Bugfix
-   * Include asn1.h in error.c. Fixes #3328 reported by David Hu.

ChangeLog.d/fix-ecp-mul-memory-leak.txt

@@ -1,3 +0,0 @@
-Bugfix
-   * Fix potential memory leaks in ecp_randomize_jac() and ecp_randomize_mxz()
-     when PRNG function fails. Contributed by Jonas Lejeune in #3318.

ChangeLog.d/max_pathlen.txt

@@ -1,5 +0,0 @@
-Bugfix
-   * Fix undefined behavior in X.509 certificate parsing if the
-     pathLenConstraint basic constraint value is equal to INT_MAX.
-     The actual effect with almost every compiler is the intended
-     behavior, so this is unlikely to be exploitable anywhere. #3196

ChangeLog.d/montmul-cmp-branch.txt

@@ -1,6 +0,0 @@
-Security
-   * Fix a side channel vulnerability in modular exponentiation that could
-     reveal an RSA private key used in a secure enclave. Noticed by Sangho Lee,
-     Ming-Wei Shih, Prasun Gera, Taesoo Kim and Hyesoon Kim (Georgia Institute
-     of Technology); and Marcus Peinado (Microsoft Research). Reported by Raoul
-     Strackx (Fortanix) in #3394.

ChangeLog.d/unified-exit-in-examples.txt

@@ -1,4 +0,0 @@
-Changes
-   * Unify the example programs termination to call mbedtls_exit() instead of
-     using a return command. This has been done to enable customization of the
-     behavior in bare metal environments.

ChangeLog.d/uniformize_bounds_checks.txt

@@ -1,9 +0,0 @@
-Bugfix
-   * Add additional bounds checks in ssl_write_client_hello() preventing
-     output buffer overflow if the configuration declared a buffer that was
-     too small.
-Changes
-   * Abort the ClientHello writing function as soon as some extension doesn't
-     fit into the record buffer. Previously, such extensions were silently
-     dropped. As a consequence, the TLS handshake now fails when the output
-     buffer is not large enough to hold the ClientHello.

doxygen/input/doc_mainpage.h

@@ -51,7 +51,7 @@
  */
 
 /**
- * @mainpage mbed TLS v2.7.15 source code documentation
+ * @mainpage mbed TLS v2.7.16 source code documentation
  *
  * This documentation describes the internal structure of mbed TLS.  It was
  * automatically generated from specially formatted comment blocks in

doxygen/mbedtls.doxyfile

@@ -28,7 +28,7 @@ DOXYFILE_ENCODING      = UTF-8
 # identify the project. Note that if you do not use Doxywizard you need
 # to put quotes around the project name if it contains spaces.
 
-PROJECT_NAME           = "mbed TLS v2.7.15"
+PROJECT_NAME           = "mbed TLS v2.7.16"
 
 # The PROJECT_NUMBER tag can be used to enter a project or revision number.
 # This could be handy for archiving the generated documentation or

include/mbedtls/check_config.h

@@ -150,6 +150,16 @@
 #error "MBEDTLS_ECP_C defined, but not all prerequisites"
 #endif
 
+#if defined(MBEDTLS_ECP_C) && !(            \
+    defined(MBEDTLS_ECP_ALT) ||             \
+    defined(MBEDTLS_CTR_DRBG_C) ||          \
+    defined(MBEDTLS_HMAC_DRBG_C) ||         \
+    defined(MBEDTLS_SHA512_C) ||            \
+    defined(MBEDTLS_SHA256_C) ||            \
+    defined(MBEDTLS_ECP_NO_INTERNAL_RNG))
+#error "MBEDTLS_ECP_C requires a DRBG or SHA-2 module unless MBEDTLS_ECP_NO_INTERNAL_RNG is defined or an alternative implementation is used"
+#endif
+
 #if defined(MBEDTLS_PK_PARSE_C) && !defined(MBEDTLS_ASN1_PARSE_C)
 #error "MBEDTLS_PK_PARSE_C defined, but not all prerequesites"
 #endif

include/mbedtls/config.h

@@ -645,6 +645,28 @@
  */
 #define MBEDTLS_ECP_NIST_OPTIM
 
+/**
+ * \def MBEDTLS_ECP_NO_INTERNAL_RNG
+ *
+ * When this option is disabled, mbedtls_ecp_mul() will make use of an
+ * internal RNG when called with a NULL \c f_rng argument, in order to protect
+ * against some side-channel attacks.
+ *
+ * This protection introduces a dependency of the ECP module on one of the
+ * DRBG or SHA modules (HMAC-DRBG, CTR-DRBG, SHA-512 or SHA-256.) For very
+ * constrained applications that don't require this protection (for example,
+ * because you're only doing signature verification, so not manipulating any
+ * secret, or because local/physical side-channel attacks are outside your
+ * threat model), it might be desirable to get rid of that dependency.
+ *
+ * \warning Enabling this option makes some uses of ECP vulnerable to some
+ * side-channel attacks. Only enable it if you know that's not a problem for
+ * your use case.
+ *
+ * Uncomment this macro to disable some counter-measures in ECP.
+ */
+//#define MBEDTLS_ECP_NO_INTERNAL_RNG
+
 /**
  * \def MBEDTLS_ECDSA_DETERMINISTIC
  *

include/mbedtls/ecp.h

@@ -545,10 +545,13 @@ int mbedtls_ecp_tls_write_group( const mbedtls_ecp_group *grp, size_t *olen,
  *                  operations for any valid m. It avoids any if-branch or
  *                  array index depending on the value of m.
  *
- * \note            If f_rng is not NULL, it is used to randomize intermediate
- *                  results in order to prevent potential timing attacks
- *                  targeting these results. It is recommended to always
- *                  provide a non-NULL f_rng (the overhead is negligible).
+ * \note            If \p f_rng is not NULL, it is used to randomize
+ *                  intermediate results to prevent potential timing attacks
+ *                  targeting these results. We recommend always providing
+ *                  a non-NULL \p f_rng. The overhead is negligible.
+ *                  Note: unless #MBEDTLS_ECP_NO_INTERNAL_RNG is defined, when
+ *                  \p f_rng is NULL, an internal RNG (seeded from the value
+ *                  of \p m) will be used instead.
  *
  * \param grp       ECP group
  * \param R         Destination point

include/mbedtls/md.h

@@ -122,6 +122,8 @@ typedef struct {
  * \brief           This function returns the list of digests supported by the
  *                  generic digest module.
  *
+ * \note            The list starts with the strongest available hashes.
+ *
  * \return          A statically allocated array of digests. Each element
  *                  in the returned list is an integer belonging to the
  *                  message-digest enumeration #mbedtls_md_type_t.

include/mbedtls/version.h

@@ -67,16 +67,16 @@
  */
 #define MBEDTLS_VERSION_MAJOR  2
 #define MBEDTLS_VERSION_MINOR  7
-#define MBEDTLS_VERSION_PATCH  15
+#define MBEDTLS_VERSION_PATCH  16
 
 /**
  * The single version number has the following structure:
  *    MMNNPP00
  *    Major version | Minor version | Patch version
  */
-#define MBEDTLS_VERSION_NUMBER         0x02070F00
-#define MBEDTLS_VERSION_STRING         "2.7.15"
-#define MBEDTLS_VERSION_STRING_FULL    "mbed TLS 2.7.15"
+#define MBEDTLS_VERSION_NUMBER         0x02071000
+#define MBEDTLS_VERSION_STRING         "2.7.16"
+#define MBEDTLS_VERSION_STRING_FULL    "mbed TLS 2.7.16"
 
 #if defined(MBEDTLS_VERSION_C)
 

library/CMakeLists.txt

@@ -147,15 +147,15 @@ endif(USE_STATIC_MBEDTLS_LIBRARY)
 
 if(USE_SHARED_MBEDTLS_LIBRARY)
     add_library(mbedcrypto SHARED ${src_crypto})
-    set_target_properties(mbedcrypto PROPERTIES VERSION 2.7.15 SOVERSION 2)
+    set_target_properties(mbedcrypto PROPERTIES VERSION 2.7.16 SOVERSION 2)
     target_link_libraries(mbedcrypto ${libs})
 
     add_library(mbedx509 SHARED ${src_x509})
-    set_target_properties(mbedx509 PROPERTIES VERSION 2.7.15 SOVERSION 0)
+    set_target_properties(mbedx509 PROPERTIES VERSION 2.7.16 SOVERSION 0)
     target_link_libraries(mbedx509 ${libs} mbedcrypto)
 
     add_library(mbedtls SHARED ${src_tls})
-    set_target_properties(mbedtls PROPERTIES VERSION 2.7.15 SOVERSION 10)
+    set_target_properties(mbedtls PROPERTIES VERSION 2.7.16 SOVERSION 10)
     target_link_libraries(mbedtls ${libs} mbedx509)
 
     install(TARGETS mbedtls mbedx509 mbedcrypto

library/ecp.c

@@ -94,6 +94,20 @@
 
 #include "mbedtls/ecp_internal.h"
 
+#if !defined(MBEDTLS_ECP_NO_INTERNAL_RNG)
+#if defined(MBEDTLS_HMAC_DRBG_C)
+#include "mbedtls/hmac_drbg.h"
+#elif defined(MBEDTLS_CTR_DRBG_C)
+#include "mbedtls/ctr_drbg.h"
+#elif defined(MBEDTLS_SHA512_C)
+#include "mbedtls/sha512.h"
+#elif defined(MBEDTLS_SHA256_C)
+#include "mbedtls/sha256.h"
+#else
+#error "Invalid configuration detected. Include check_config.h to ensure that the configuration is valid."
+#endif
+#endif /* MBEDTLS_ECP_NO_INTERNAL_RNG */
+
 #if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && \
     !defined(inline) && !defined(__cplusplus)
 #define inline __inline
@@ -112,6 +126,233 @@ static void mbedtls_zeroize( void *v, size_t n ) {
 static unsigned long add_count, dbl_count, mul_count;
 #endif
 
+#if !defined(MBEDTLS_ECP_NO_INTERNAL_RNG)
+/*
+ * Currently ecp_mul() takes a RNG function as an argument, used for
+ * side-channel protection, but it can be NULL. The initial reasoning was
+ * that people will pass non-NULL RNG when they care about side-channels, but
+ * unfortunately we have some APIs that call ecp_mul() with a NULL RNG, with
+ * no opportunity for the user to do anything about it.
+ *
+ * The obvious strategies for addressing that include:
+ * - change those APIs so that they take RNG arguments;
+ * - require a global RNG to be available to all crypto modules.
+ *
+ * Unfortunately those would break compatibility. So what we do instead is
+ * have our own internal DRBG instance, seeded from the secret scalar.
+ *
+ * The following is a light-weight abstraction layer for doing that with
+ * HMAC_DRBG (first choice) or CTR_DRBG.
+ */
+
+#if defined(MBEDTLS_HMAC_DRBG_C)
+
+/* DRBG context type */
+typedef mbedtls_hmac_drbg_context ecp_drbg_context;
+
+/* DRBG context init */
+static inline void ecp_drbg_init( ecp_drbg_context *ctx )
+{
+    mbedtls_hmac_drbg_init( ctx );
+}
+
+/* DRBG context free */
+static inline void ecp_drbg_free( ecp_drbg_context *ctx )
+{
+    mbedtls_hmac_drbg_free( ctx );
+}
+
+/* DRBG function */
+static inline int ecp_drbg_random( void *p_rng,
+                                   unsigned char *output, size_t output_len )
+{
+    return( mbedtls_hmac_drbg_random( p_rng, output, output_len ) );
+}
+
+/* DRBG context seeding */
+static int ecp_drbg_seed( ecp_drbg_context *ctx,
+                   const mbedtls_mpi *secret, size_t secret_len )
+{
+    int ret;
+    unsigned char secret_bytes[MBEDTLS_ECP_MAX_BYTES];
+    /* The list starts with strong hashes */
+    const mbedtls_md_type_t md_type = mbedtls_md_list()[0];
+    const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type( md_type );
+
+    MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( secret,
+                                               secret_bytes, secret_len ) );
+
+    ret = mbedtls_hmac_drbg_seed_buf( ctx, md_info, secret_bytes, secret_len );
+
+cleanup:
+    mbedtls_zeroize( secret_bytes, secret_len );
+
+    return( ret );
+}
+
+#elif defined(MBEDTLS_CTR_DRBG_C)
+
+/* DRBG context type */
+typedef mbedtls_ctr_drbg_context ecp_drbg_context;
+
+/* DRBG context init */
+static inline void ecp_drbg_init( ecp_drbg_context *ctx )
+{
+    mbedtls_ctr_drbg_init( ctx );
+}
+
+/* DRBG context free */
+static inline void ecp_drbg_free( ecp_drbg_context *ctx )
+{
+    mbedtls_ctr_drbg_free( ctx );
+}
+
+/* DRBG function */
+static inline int ecp_drbg_random( void *p_rng,
+                                   unsigned char *output, size_t output_len )
+{
+    return( mbedtls_ctr_drbg_random( p_rng, output, output_len ) );
+}
+
+/*
+ * Since CTR_DRBG doesn't have a seed_buf() function the way HMAC_DRBG does,
+ * we need to pass an entropy function when seeding. So we use a dummy
+ * function for that, and pass the actual entropy as customisation string.
+ * (During seeding of CTR_DRBG the entropy input and customisation string are
+ * concatenated before being used to update the secret state.)
+ */
+static int ecp_ctr_drbg_null_entropy(void *ctx, unsigned char *out, size_t len)
+{
+    (void) ctx;
+    memset( out, 0, len );
+    return( 0 );
+}
+
+/* DRBG context seeding */
+static int ecp_drbg_seed( ecp_drbg_context *ctx,
+                   const mbedtls_mpi *secret, size_t secret_len )
+{
+    int ret;
+    unsigned char secret_bytes[MBEDTLS_ECP_MAX_BYTES];
+
+    MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( secret,
+                                               secret_bytes, secret_len ) );
+
+    ret = mbedtls_ctr_drbg_seed( ctx, ecp_ctr_drbg_null_entropy, NULL,
+                                 secret_bytes, secret_len );
+
+cleanup:
+    mbedtls_zeroize( secret_bytes, secret_len );
+
+    return( ret );
+}
+
+#elif defined(MBEDTLS_SHA512_C) || defined(MBEDTLS_SHA256_C)
+
+/* This will be used in the self-test function */
+#define ECP_ONE_STEP_KDF
+
+/*
+ * We need to expand secret data (the scalar) into a longer stream of bytes.
+ *
+ * We'll use the One-Step KDF from NIST SP 800-56C, with option 1 (H is a hash
+ * function) and empty FixedInfo. (Though we'll make it fit the DRBG API for
+ * convenience, this is not a full-fledged DRBG, but we don't need one here.)
+ *
+ * We need a basic hash abstraction layer to use whatever SHA-2 is available.
+ */
+#if defined(MBEDTLS_SHA512_C)
+
+#define HASH_FUNC( in, ilen, out )  mbedtls_sha512_ret( in, ilen, out, 0 );
+#define HASH_BLOCK_BYTES            ( 512 / 8 )
+
+#elif defined(MBEDTLS_SHA256_C)
+
+#define HASH_FUNC( in, ilen, out )  mbedtls_sha256_ret( in, ilen, out, 0 );
+#define HASH_BLOCK_BYTES            ( 256 / 8 )
+
+#endif /* SHA512/SHA256 abstraction */
+
+/*
+ * State consists of a 32-bit counter plus the secret value.
+ *
+ * We stored them concatenated in a single buffer as that's what will get
+ * passed to the hash function.
+ */
+typedef struct {
+    size_t total_len;
+    uint8_t buf[4 + MBEDTLS_ECP_MAX_BYTES];
+} ecp_drbg_context;
+
+static void ecp_drbg_init( ecp_drbg_context *ctx )
+{
+    memset( ctx, 0, sizeof( ecp_drbg_context ) );
+}
+
+static void ecp_drbg_free( ecp_drbg_context *ctx )
+{
+    mbedtls_zeroize( ctx, sizeof( ecp_drbg_context ) );
+}
+
+static int ecp_drbg_seed( ecp_drbg_context *ctx,
+                   const mbedtls_mpi *secret, size_t secret_len )
+{
+    ctx->total_len = 4 + secret_len;
+    memset( ctx->buf, 0, 4);
+    return( mbedtls_mpi_write_binary( secret, ctx->buf + 4, secret_len ) );
+}
+
+static int ecp_drbg_random( void *p_rng, unsigned char *output, size_t output_len )
+{
+    ecp_drbg_context *ctx = p_rng;
+    int ret;
+    size_t len_done = 0;
+    uint8_t tmp[HASH_BLOCK_BYTES];
+
+    while( len_done < output_len )
+    {
+        uint8_t use_len;
+
+        /* This function is only called for coordinate randomisation, which
+         * happens only twice in a scalar multiplication. Each time needs a
+         * random value in the range [2, p-1], and gets it by drawing len(p)
+         * bytes from this function, and retrying up to 10 times if unlucky.
+         *
+         * So for the largest curve, each scalar multiplication draws at most
+         * 20 * 66 bytes. The minimum block size is 32 (SHA-256), so with
+         * rounding that means a most 20 * 3 blocks.
+         *
+         * Since we don't need to draw more that 255 blocks, don't bother
+         * with carry propagation and just return an error instead. We can
+         * change that it we even need to draw more blinding values.
+         */
+        ctx->buf[3] += 1;
+        if( ctx->buf[3] == 0 )
+            return( MBEDTLS_ERR_ECP_RANDOM_FAILED );
+
+        ret = HASH_FUNC( ctx->buf, ctx->total_len, tmp );
+        if( ret != 0 )
+            return( ret );
+
+        if( output_len - len_done > HASH_BLOCK_BYTES )
+            use_len = HASH_BLOCK_BYTES;
+        else
+            use_len = output_len - len_done;
+
+        memcpy( output + len_done, tmp, use_len );
+        len_done += use_len;
+    }
+
+    mbedtls_zeroize( tmp, sizeof( tmp ) );
+
+    return( 0 );
+}
+
+#else /* DRBG/SHA modules */
+#error "Invalid configuration detected. Include check_config.h to ensure that the configuration is valid."
+#endif /* DRBG/SHA modules */
+#endif /* MBEDTLS_ECP_NO_INTERNAL_RNG */
+
 #if defined(MBEDTLS_ECP_DP_SECP192R1_ENABLED) ||   \
     defined(MBEDTLS_ECP_DP_SECP224R1_ENABLED) ||   \
     defined(MBEDTLS_ECP_DP_SECP256R1_ENABLED) ||   \
@@ -1357,7 +1598,9 @@ static int ecp_mul_comb_core( const mbedtls_ecp_group *grp, mbedtls_ecp_point *R
     i = d;
     MBEDTLS_MPI_CHK( ecp_select_comb( grp, R, T, t_len, x[i] ) );
     MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &R->Z, 1 ) );
+#if defined(MBEDTLS_ECP_NO_INTERNAL_RNG)
     if( f_rng != 0 )
+#endif
         MBEDTLS_MPI_CHK( ecp_randomize_jac( grp, R, f_rng, p_rng ) );
 
     while( i-- != 0 )
@@ -1486,7 +1729,9 @@ static int ecp_mul_comb( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
      *
      * Avoid the leak by randomizing coordinates before we normalize them.
      */
+#if defined(MBEDTLS_ECP_NO_INTERNAL_RNG)
     if( f_rng != 0 )
+#endif
         MBEDTLS_MPI_CHK( ecp_randomize_jac( grp, R, f_rng, p_rng ) );
     MBEDTLS_MPI_CHK( ecp_normalize_jac( grp, R ) );
 
@@ -1689,7 +1934,9 @@ static int ecp_mul_mxz( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
     MOD_ADD( RP.X );
 
     /* Randomize coordinates of the starting point */
+#if defined(MBEDTLS_ECP_NO_INTERNAL_RNG)
     if( f_rng != NULL )
+#endif
         MBEDTLS_MPI_CHK( ecp_randomize_mxz( grp, &RP, f_rng, p_rng ) );
 
     /* Loop invariant: R = result so far, RP = R + P */
@@ -1722,7 +1969,9 @@ static int ecp_mul_mxz( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
      *
      * Avoid the leak by randomizing coordinates before we normalize them.
      */
+#if defined(MBEDTLS_ECP_NO_INTERNAL_RNG)
     if( f_rng != NULL )
+#endif
         MBEDTLS_MPI_CHK( ecp_randomize_mxz( grp, R, f_rng, p_rng ) );
 
     MBEDTLS_MPI_CHK( ecp_normalize_mxz( grp, R ) );
@@ -1746,6 +1995,11 @@ int mbedtls_ecp_mul( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
 #if defined(MBEDTLS_ECP_INTERNAL_ALT)
     char is_grp_capable = 0;
 #endif
+#if !defined(MBEDTLS_ECP_NO_INTERNAL_RNG)
+    ecp_drbg_context drbg_ctx;
+
+    ecp_drbg_init( &drbg_ctx );
+#endif /* !MBEDTLS_ECP_NO_INTERNAL_RNG */
 
     /* Common sanity checks */
     if( mbedtls_mpi_cmp_int( &P->Z, 1 ) != 0 )
@@ -1755,32 +2009,46 @@ int mbedtls_ecp_mul( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
         ( ret = mbedtls_ecp_check_pubkey( grp, P ) ) != 0 )
         return( ret );
 
+#if !defined(MBEDTLS_ECP_NO_INTERNAL_RNG)
+    if( f_rng == NULL )
+    {
+        const size_t m_len = ( grp->nbits + 7 ) / 8;
+        MBEDTLS_MPI_CHK( ecp_drbg_seed( &drbg_ctx, m, m_len ) );
+        f_rng = &ecp_drbg_random;
+        p_rng = &drbg_ctx;
+    }
+#endif /* !MBEDTLS_ECP_NO_INTERNAL_RNG */
+
 #if defined(MBEDTLS_ECP_INTERNAL_ALT)
     if ( is_grp_capable = mbedtls_internal_ecp_grp_capable( grp )  )
     {
         MBEDTLS_MPI_CHK( mbedtls_internal_ecp_init( grp ) );
     }
-
 #endif /* MBEDTLS_ECP_INTERNAL_ALT */
+
 #if defined(ECP_MONTGOMERY)
     if( ecp_get_type( grp ) == ECP_TYPE_MONTGOMERY )
         ret = ecp_mul_mxz( grp, R, m, P, f_rng, p_rng );
-
 #endif
 #if defined(ECP_SHORTWEIERSTRASS)
     if( ecp_get_type( grp ) == ECP_TYPE_SHORT_WEIERSTRASS )
         ret = ecp_mul_comb( grp, R, m, P, f_rng, p_rng );
+#endif
 
+#if defined(MBEDTLS_ECP_INTERNAL_ALT) || !defined(MBEDTLS_ECP_NO_INTERNAL_RNG)
+cleanup:
 #endif
 #if defined(MBEDTLS_ECP_INTERNAL_ALT)
-cleanup:
-
     if ( is_grp_capable )
     {
         mbedtls_internal_ecp_free( grp );
     }
-
 #endif /* MBEDTLS_ECP_INTERNAL_ALT */
+
+#if !defined(MBEDTLS_ECP_NO_INTERNAL_RNG)
+    ecp_drbg_free( &drbg_ctx );
+#endif
+
     return( ret );
 }
 
@@ -2145,6 +2413,76 @@ cleanup:
 
 #if defined(MBEDTLS_SELF_TEST)
 
+#if defined(ECP_ONE_STEP_KDF)
+/*
+ * There are no test vectors from NIST for the One-Step KDF in SP 800-56C,
+ * but unofficial ones can be found at:
+ * https://github.com/patrickfav/singlestep-kdf/wiki/NIST-SP-800-56C-Rev1:-Non-Official-Test-Vectors
+ *
+ * We only use the ones with empty fixedInfo, and for brevity's sake, only
+ * 40-bytes output (with SHA-256 that's more than one block, and with SHA-512
+ * less than one block).
+ */
+#if defined(MBEDTLS_SHA512_C)
+
+static const uint8_t test_kdf_z[16] = {
+    0x3b, 0xa9, 0x79, 0xe9, 0xbc, 0x5e, 0x3e, 0xc7,
+    0x61, 0x30, 0x36, 0xb6, 0xf5, 0x1c, 0xd5, 0xaa,
+};
+static const uint8_t test_kdf_out[40] = {
+    0x3e, 0xf6, 0xda, 0xf9, 0x51, 0x60, 0x70, 0x5f,
+    0xdf, 0x21, 0xcd, 0xab, 0xac, 0x25, 0x7b, 0x05,
+    0xfe, 0xc1, 0xab, 0x7c, 0xc9, 0x68, 0x43, 0x25,
+    0x8a, 0xfc, 0x40, 0x6e, 0x5b, 0xf7, 0x98, 0x27,
+    0x10, 0xfa, 0x7b, 0x93, 0x52, 0xd4, 0x16, 0xaa,
+};
+
+#elif defined(MBEDTLS_SHA256_C)
+
+static const uint8_t test_kdf_z[16] = {
+    0xc8, 0x3e, 0x35, 0x8e, 0x99, 0xa6, 0x89, 0xc6,
+    0x7d, 0xb4, 0xfe, 0x39, 0xcf, 0x8f, 0x26, 0xe1,
+};
+static const uint8_t test_kdf_out[40] = {
+    0x7d, 0xf6, 0x41, 0xf8, 0x3c, 0x47, 0xdc, 0x28,
+    0x5f, 0x7f, 0xaa, 0xde, 0x05, 0x64, 0xd6, 0x25,
+    0x00, 0x6a, 0x47, 0xd9, 0x1e, 0xa4, 0xa0, 0x8c,
+    0xd7, 0xf7, 0x0c, 0x99, 0xaa, 0xa0, 0x72, 0x66,
+    0x69, 0x0e, 0x25, 0xaa, 0xa1, 0x63, 0x14, 0x79,
+};
+
+#endif
+
+static int ecp_kdf_self_test( void )
+{
+    int ret;
+    ecp_drbg_context kdf_ctx;
+    mbedtls_mpi scalar;
+    uint8_t out[sizeof( test_kdf_out )];
+
+    ecp_drbg_init( &kdf_ctx );
+    mbedtls_mpi_init( &scalar );
+    memset( out, 0, sizeof( out ) );
+
+    MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &scalar,
+                        test_kdf_z, sizeof( test_kdf_z ) ) );
+
+    MBEDTLS_MPI_CHK( ecp_drbg_seed( &kdf_ctx,
+                                    &scalar, sizeof( test_kdf_z ) ) );
+
+    MBEDTLS_MPI_CHK( ecp_drbg_random( &kdf_ctx, out, sizeof( out ) ) );
+
+    if( memcmp( out, test_kdf_out, sizeof( out ) ) != 0 )
+        ret = -1;
+
+cleanup:
+    ecp_drbg_free( &kdf_ctx );
+    mbedtls_mpi_free( &scalar );
+
+    return( ret );
+}
+#endif /* ECP_ONE_STEP_KDF */
+
 /*
  * Checkup routine
  */
@@ -2256,6 +2594,24 @@ int mbedtls_ecp_self_test( int verbose )
     if( verbose != 0 )
         mbedtls_printf( "passed\n" );
 
+#if defined(ECP_ONE_STEP_KDF)
+    if( verbose != 0 )
+        mbedtls_printf( "  ECP test #3 (internal KDF): " );
+
+    ret = ecp_kdf_self_test();
+    if( ret != 0 )
+    {
+        if( verbose != 0 )
+            mbedtls_printf( "failed\n" );
+
+        ret = 1;
+        goto cleanup;
+    }
+
+    if( verbose != 0 )
+        mbedtls_printf( "passed\n" );
+#endif /* ECP_ONE_STEP_KDF */
+
 cleanup:
 
     if( ret < 0 && verbose != 0 )

library/ssl_tls.c

@@ -2119,10 +2119,20 @@ static int ssl_decrypt_buf( mbedtls_ssl_context *ssl )
             ssl_read_memory( ssl->in_msg + ssl->in_msglen, padlen );
             mbedtls_md_hmac_finish( &ssl->transform_in->md_ctx_dec, mac_expect );
 
-            /* Call mbedtls_md_process at least once due to cache attacks
-             * that observe whether md_process() was called of not */
+            /* Dummy calls to compression function.
+             * Call mbedtls_md_process at least once due to cache attacks
+             * that observe whether md_process() was called of not.
+             * Respect the usual start-(process|update)-finish sequence for
+             * the sake of hardware accelerators that might require it. */
+            mbedtls_md_starts( &ssl->transform_in->md_ctx_dec );
             for( j = 0; j < extra_run + 1; j++ )
                 mbedtls_md_process( &ssl->transform_in->md_ctx_dec, ssl->in_msg );
+            {
+                /* The switch statement above already checks that we're using
+                 * one of MD-5, SHA-1, SHA-256 or SHA-384. */
+                unsigned char tmp[384 / 8];
+                mbedtls_md_finish( &ssl->transform_in->md_ctx_dec, tmp );
+            }
 
             mbedtls_md_hmac_reset( &ssl->transform_in->md_ctx_dec );
 

library/version_features.c

@@ -339,6 +339,9 @@ static const char *features[] = {
 #if defined(MBEDTLS_ECP_NIST_OPTIM)
     "MBEDTLS_ECP_NIST_OPTIM",
 #endif /* MBEDTLS_ECP_NIST_OPTIM */
+#if defined(MBEDTLS_ECP_NO_INTERNAL_RNG)
+    "MBEDTLS_ECP_NO_INTERNAL_RNG",
+#endif /* MBEDTLS_ECP_NO_INTERNAL_RNG */
 #if defined(MBEDTLS_ECDSA_DETERMINISTIC)
     "MBEDTLS_ECDSA_DETERMINISTIC",
 #endif /* MBEDTLS_ECDSA_DETERMINISTIC */

scripts/config.pl

@@ -112,6 +112,7 @@ EOU
 my @excluded = qw(
 MBEDTLS_DEPRECATED_REMOVED
 MBEDTLS_DEPRECATED_WARNING
+MBEDTLS_ECP_NO_INTERNAL_RNG
 MBEDTLS_HAVE_SSE2
 MBEDTLS_MEMORY_BACKTRACE
 MBEDTLS_MEMORY_BUFFER_ALLOC_C

tests/scripts/all.sh

@@ -892,6 +892,61 @@ component_test_no_hmac_drbg () {
     # so there's little value in running those lengthy tests here.
 }
 
+component_test_no_drbg_all_hashes () {
+    # this tests the internal ECP DRBG using a KDF based on SHA-512
+    msg "build: Default minus DRBGs"
+    scripts/config.pl unset MBEDTLS_CTR_DRBG_C
+    scripts/config.pl unset MBEDTLS_HMAC_DRBG_C
+    scripts/config.pl unset MBEDTLS_ECDSA_DETERMINISTIC # requires HMAC_DRBG
+    scripts/config.pl unset MBEDTLS_PSA_CRYPTO_C # requires a DRBG
+    scripts/config.pl unset MBEDTLS_PSA_CRYPTO_STORAGE_C # requires PSA Crypto
+
+    CC=gcc cmake -D CMAKE_BUILD_TYPE:String=Asan .
+    make
+
+    msg "test: Default minus DRBGs"
+    make test
+
+    # no SSL tests as they all depend on having a DRBG
+}
+
+component_test_no_drbg_no_sha512 () {
+    # this tests the internal ECP DRBG using a KDF based on SHA-256
+    msg "build: Default minus DRBGs minus SHA-512"
+    scripts/config.pl unset MBEDTLS_CTR_DRBG_C
+    scripts/config.pl unset MBEDTLS_HMAC_DRBG_C
+    scripts/config.pl unset MBEDTLS_ECDSA_DETERMINISTIC # requires HMAC_DRBG
+    scripts/config.pl unset MBEDTLS_PSA_CRYPTO_C # requires a DRBG
+    scripts/config.pl unset MBEDTLS_PSA_CRYPTO_STORAGE_C # requires PSA Crypto
+    scripts/config.pl unset MBEDTLS_SHA512_C
+
+    CC=gcc cmake -D CMAKE_BUILD_TYPE:String=Asan .
+    make
+
+    msg "test: Default minus DRBGs minus SHA-512"
+    make test
+
+    # no SSL tests as they all depend on having a DRBG
+}
+
+component_test_ecp_no_internal_rng () {
+    msg "build: Default plus ECP_NO_INTERNAL_RNG minus DRBG modules"
+    scripts/config.pl set MBEDTLS_ECP_NO_INTERNAL_RNG
+    scripts/config.pl unset MBEDTLS_CTR_DRBG_C
+    scripts/config.pl unset MBEDTLS_HMAC_DRBG_C
+    scripts/config.pl unset MBEDTLS_ECDSA_DETERMINISTIC # requires HMAC_DRBG
+    scripts/config.pl unset MBEDTLS_PSA_CRYPTO_C # requires a DRBG
+    scripts/config.pl unset MBEDTLS_PSA_CRYPTO_STORAGE_C # requires PSA Crypto
+
+    CC=gcc cmake -D CMAKE_BUILD_TYPE:String=Asan .
+    make
+
+    msg "test: ECP_NO_INTERNAL_RNG, no DRBG module"
+    make test
+
+    # no SSL tests as they all depend on having a DRBG
+}
+
 component_test_full_cmake_clang () {
     msg "build: cmake, full config, clang" # ~ 50s
     scripts/config.pl full

tests/suites/test_suite_version.data

@@ -1,8 +1,8 @@
 Check compiletime library version
-check_compiletime_version:"2.7.15"
+check_compiletime_version:"2.7.16"
 
 Check runtime library version
-check_runtime_version:"2.7.15"
+check_runtime_version:"2.7.16"
 
 Check for MBEDTLS_VERSION_C
 check_feature:"MBEDTLS_VERSION_C":0