Import mbedtls-2.27.0

Imports Mbed TLS 2.27.0 from https://github.com/ARMmbed/mbedtls.git
commit f71e28780841 ("Merge pull request #843 from
paul-elliott-arm/mbedtls-2.27.0rc0-pr") (tag mbedtls-2.27.0, v2.27.0).

Files that are not needed are removed.

 cd lib/libmbedtls
 rm -rf mbedtls
 cp -R path/to/mbedtls-2.27.0/mbedtls .
 cd mbedtls
 rm CMakeLists.txt DartConfiguration.tcl Makefile
 rm .gitignore .travis.yml .pylintrc .globalrc .mypy.ini BRANCHES.md
 rm include/.gitignore include/CMakeLists.txt library/.gitignore
 rm library/CMakeLists.txt library/Makefile
 rm -rf .git .github doxygen configs programs scripts tests visualc yotta
 rm -rf 3rdparty ChangeLog.d docs
 rm -rf include/mbedtls/config_psa.h include/psa
 rm library/psa_* library/mps_*
 cd ..
 git add mbedtls

This is a complete overwrite of previous code so earlier changes in the
previous branch import/mbedtls-2.22.0 will be added on top of this commit.

Signed-off-by: Jerome Forissier <jerome@forissier.org>
diff --git a/lib/libmbedtls/mbedtls/library/dhm.c b/lib/libmbedtls/mbedtls/library/dhm.c
index 9a76fc5..accd5a8 100644
--- a/lib/libmbedtls/mbedtls/library/dhm.c
+++ b/lib/libmbedtls/mbedtls/library/dhm.c
@@ -1,8 +1,8 @@
-// SPDX-License-Identifier: Apache-2.0
 /*
  *  Diffie-Hellman-Merkle key exchange
  *
- *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
+ *  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.
@@ -15,8 +15,6 @@
  *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  *  See the License for the specific language governing permissions and
  *  limitations under the License.
- *
- *  This file is part of mbed TLS (https://tls.mbed.org)
  */
 /*
  *  The following sources were referenced in the design of this implementation
@@ -27,11 +25,7 @@
  *
  */
 
-#if !defined(MBEDTLS_CONFIG_FILE)
-#include "mbedtls/config.h"
-#else
-#include MBEDTLS_CONFIG_FILE
-#endif
+#include "common.h"
 
 #if defined(MBEDTLS_DHM_C)
 
@@ -85,7 +79,7 @@
         return( MBEDTLS_ERR_DHM_BAD_INPUT_DATA );
 
     if( ( ret = mbedtls_mpi_read_binary( X, *p, n ) ) != 0 )
-        return( MBEDTLS_ERR_DHM_READ_PARAMS_FAILED + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_DHM_READ_PARAMS_FAILED, ret ) );
 
     (*p) += n;
 
@@ -106,22 +100,21 @@
  */
 static int dhm_check_range( const mbedtls_mpi *param, const mbedtls_mpi *P )
 {
-    mbedtls_mpi L, U;
+    mbedtls_mpi U;
     int ret = 0;
 
-    mbedtls_mpi_init( &L ); mbedtls_mpi_init( &U );
+    mbedtls_mpi_init( &U );
 
-    MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &L, 2 ) );
     MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &U, P, 2 ) );
 
-    if( mbedtls_mpi_cmp_mpi( param, &L ) < 0 ||
+    if( mbedtls_mpi_cmp_int( param, 2 ) < 0 ||
         mbedtls_mpi_cmp_mpi( param, &U ) > 0 )
     {
         ret = MBEDTLS_ERR_DHM_BAD_INPUT_DATA;
     }
 
 cleanup:
-    mbedtls_mpi_free( &L ); mbedtls_mpi_free( &U );
+    mbedtls_mpi_free( &U );
     return( ret );
 }
 
@@ -157,38 +150,44 @@
 }
 
 /*
- * Setup and write the ServerKeyExchange parameters
+ * Pick a random R in the range [2, M-2] for blinding or key generation.
  */
-int mbedtls_dhm_make_params( mbedtls_dhm_context *ctx, int x_size,
-                     unsigned char *output, size_t *olen,
-                     int (*f_rng)(void *, unsigned char *, size_t),
-                     void *p_rng )
+static int dhm_random_below( mbedtls_mpi *R, const mbedtls_mpi *M,
+                int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
 {
-    int ret, count = 0;
-    size_t n1, n2, n3;
-    unsigned char *p;
-    DHM_VALIDATE_RET( ctx != NULL );
-    DHM_VALIDATE_RET( output != NULL );
-    DHM_VALIDATE_RET( olen != NULL );
-    DHM_VALIDATE_RET( f_rng != NULL );
+    int ret;
+
+    MBEDTLS_MPI_CHK( mbedtls_mpi_random( R, 3, M, f_rng, p_rng ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( R, R, 1 ) );
+
+cleanup:
+    return( ret );
+}
+
+static int dhm_make_common( mbedtls_dhm_context *ctx, int x_size,
+                            int (*f_rng)(void *, unsigned char *, size_t),
+                            void *p_rng )
+{
+    int ret = 0;
 
     if( mbedtls_mpi_cmp_int( &ctx->P, 0 ) == 0 )
         return( MBEDTLS_ERR_DHM_BAD_INPUT_DATA );
+    if( x_size < 0 )
+        return( MBEDTLS_ERR_DHM_BAD_INPUT_DATA );
 
-    /*
-     * Generate X as large as possible ( < P )
-     */
-    do
+    if( (unsigned) x_size < mbedtls_mpi_size( &ctx->P ) )
     {
         MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &ctx->X, x_size, f_rng, p_rng ) );
-
-        while( mbedtls_mpi_cmp_mpi( &ctx->X, &ctx->P ) >= 0 )
-            MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( &ctx->X, 1 ) );
-
-        if( count++ > 10 )
-            return( MBEDTLS_ERR_DHM_MAKE_PARAMS_FAILED );
     }
-    while( dhm_check_range( &ctx->X, &ctx->P ) != 0 );
+    else
+    {
+        /* Generate X as large as possible ( <= P - 2 ) */
+        ret = dhm_random_below( &ctx->X, &ctx->P, f_rng, p_rng );
+        if( ret == MBEDTLS_ERR_MPI_NOT_ACCEPTABLE )
+            return( MBEDTLS_ERR_DHM_MAKE_PARAMS_FAILED );
+        if( ret != 0 )
+            return( ret );
+    }
 
     /*
      * Calculate GX = G^X mod P
@@ -199,8 +198,33 @@
     if( ( ret = dhm_check_range( &ctx->GX, &ctx->P ) ) != 0 )
         return( ret );
 
+cleanup:
+    return( ret );
+}
+
+/*
+ * Setup and write the ServerKeyExchange parameters
+ */
+int mbedtls_dhm_make_params( mbedtls_dhm_context *ctx, int x_size,
+                     unsigned char *output, size_t *olen,
+                     int (*f_rng)(void *, unsigned char *, size_t),
+                     void *p_rng )
+{
+    int ret;
+    size_t n1, n2, n3;
+    unsigned char *p;
+    DHM_VALIDATE_RET( ctx != NULL );
+    DHM_VALIDATE_RET( output != NULL );
+    DHM_VALIDATE_RET( olen != NULL );
+    DHM_VALIDATE_RET( f_rng != NULL );
+
+    ret = dhm_make_common( ctx, x_size, f_rng, p_rng );
+    if( ret != 0 )
+        goto cleanup;
+
     /*
-     * export P, G, GX
+     * Export P, G, GX. RFC 5246 §4.4 states that "leading zero octets are
+     * not required". We omit leading zeros for compactness.
      */
 #define DHM_MPI_EXPORT( X, n )                                          \
     do {                                                                \
@@ -226,11 +250,9 @@
     ctx->len = n1;
 
 cleanup:
-
-    if( ret != 0 )
-        return( MBEDTLS_ERR_DHM_MAKE_PARAMS_FAILED + ret );
-
-    return( 0 );
+    if( ret != 0 && ret > -128 )
+        ret = MBEDTLS_ERROR_ADD( MBEDTLS_ERR_DHM_MAKE_PARAMS_FAILED, ret );
+    return( ret );
 }
 
 /*
@@ -248,7 +270,7 @@
     if( ( ret = mbedtls_mpi_copy( &ctx->P, P ) ) != 0 ||
         ( ret = mbedtls_mpi_copy( &ctx->G, G ) ) != 0 )
     {
-        return( MBEDTLS_ERR_DHM_SET_GROUP_FAILED + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_DHM_SET_GROUP_FAILED, ret ) );
     }
 
     ctx->len = mbedtls_mpi_size( &ctx->P );
@@ -269,7 +291,7 @@
         return( MBEDTLS_ERR_DHM_BAD_INPUT_DATA );
 
     if( ( ret = mbedtls_mpi_read_binary( &ctx->GY, input, ilen ) ) != 0 )
-        return( MBEDTLS_ERR_DHM_READ_PUBLIC_FAILED + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_DHM_READ_PUBLIC_FAILED, ret ) );
 
     return( 0 );
 }
@@ -282,7 +304,7 @@
                      int (*f_rng)(void *, unsigned char *, size_t),
                      void *p_rng )
 {
-    int ret, count = 0;
+    int ret;
     DHM_VALIDATE_RET( ctx != NULL );
     DHM_VALIDATE_RET( output != NULL );
     DHM_VALIDATE_RET( f_rng != NULL );
@@ -290,40 +312,21 @@
     if( olen < 1 || olen > ctx->len )
         return( MBEDTLS_ERR_DHM_BAD_INPUT_DATA );
 
-    if( mbedtls_mpi_cmp_int( &ctx->P, 0 ) == 0 )
-        return( MBEDTLS_ERR_DHM_BAD_INPUT_DATA );
-
-    /*
-     * generate X and calculate GX = G^X mod P
-     */
-    do
-    {
-        MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &ctx->X, x_size, f_rng, p_rng ) );
-
-        while( mbedtls_mpi_cmp_mpi( &ctx->X, &ctx->P ) >= 0 )
-            MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( &ctx->X, 1 ) );
-
-        if( count++ > 10 )
-            return( MBEDTLS_ERR_DHM_MAKE_PUBLIC_FAILED );
-    }
-    while( dhm_check_range( &ctx->X, &ctx->P ) != 0 );
-
-    MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &ctx->GX, &ctx->G, &ctx->X,
-                          &ctx->P , &ctx->RP ) );
-
-    if( ( ret = dhm_check_range( &ctx->GX, &ctx->P ) ) != 0 )
-        return( ret );
+    ret = dhm_make_common( ctx, x_size, f_rng, p_rng );
+    if( ret == MBEDTLS_ERR_DHM_MAKE_PARAMS_FAILED )
+        return( MBEDTLS_ERR_DHM_MAKE_PUBLIC_FAILED );
+    if( ret != 0 )
+        goto cleanup;
 
     MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->GX, output, olen ) );
 
 cleanup:
-
-    if( ret != 0 )
-        return( MBEDTLS_ERR_DHM_MAKE_PUBLIC_FAILED + ret );
-
-    return( 0 );
+    if( ret != 0 && ret > -128 )
+        ret = MBEDTLS_ERROR_ADD( MBEDTLS_ERR_DHM_MAKE_PUBLIC_FAILED, ret );
+    return( ret );
 }
 
+
 /*
  * Use the blinding method and optimisation suggested in section 10 of:
  *  KOCHER, Paul C. Timing attacks on implementations of Diffie-Hellman, RSA,
@@ -333,7 +336,10 @@
 static int dhm_update_blinding( mbedtls_dhm_context *ctx,
                     int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
 {
-    int ret, count;
+    int ret;
+    mbedtls_mpi R;
+
+    mbedtls_mpi_init( &R );
 
     /*
      * Don't use any blinding the first time a particular X is used,
@@ -367,25 +373,24 @@
      * We need to generate blinding values from scratch
      */
 
-    /* Vi = random( 2, P-1 ) */
-    count = 0;
-    do
-    {
-        MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &ctx->Vi, mbedtls_mpi_size( &ctx->P ), f_rng, p_rng ) );
+    /* Vi = random( 2, P-2 ) */
+    MBEDTLS_MPI_CHK( dhm_random_below( &ctx->Vi, &ctx->P, f_rng, p_rng ) );
 
-        while( mbedtls_mpi_cmp_mpi( &ctx->Vi, &ctx->P ) >= 0 )
-            MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( &ctx->Vi, 1 ) );
+    /* Vf = Vi^-X mod P
+     * First compute Vi^-1 = R * (R Vi)^-1, (avoiding leaks from inv_mod),
+     * then elevate to the Xth power. */
+    MBEDTLS_MPI_CHK( dhm_random_below( &R, &ctx->P, f_rng, p_rng ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vf, &ctx->Vi, &R ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vf, &ctx->Vf, &ctx->P ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &ctx->Vf, &ctx->Vf, &ctx->P ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vf, &ctx->Vf, &R ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vf, &ctx->Vf, &ctx->P ) );
 
-        if( count++ > 10 )
-            return( MBEDTLS_ERR_MPI_NOT_ACCEPTABLE );
-    }
-    while( mbedtls_mpi_cmp_int( &ctx->Vi, 1 ) <= 0 );
-
-    /* Vf = Vi^-X mod P */
-    MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &ctx->Vf, &ctx->Vi, &ctx->P ) );
     MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &ctx->Vf, &ctx->Vf, &ctx->X, &ctx->P, &ctx->RP ) );
 
 cleanup:
+    mbedtls_mpi_free( &R );
+
     return( ret );
 }
 
@@ -432,15 +437,16 @@
         MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->K, &ctx->K, &ctx->P ) );
     }
 
+    /* Output the secret without any leading zero byte. This is mandatory
+     * for TLS per RFC 5246 §8.1.2. */
     *olen = mbedtls_mpi_size( &ctx->K );
-
     MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->K, output, *olen ) );
 
 cleanup:
     mbedtls_mpi_free( &GYb );
 
     if( ret != 0 )
-        return( MBEDTLS_ERR_DHM_CALC_SECRET_FAILED + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_DHM_CALC_SECRET_FAILED, ret ) );
 
     return( 0 );
 }
@@ -522,7 +528,7 @@
     if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
     {
-        ret = MBEDTLS_ERR_DHM_INVALID_FORMAT + ret;
+        ret = MBEDTLS_ERROR_ADD( MBEDTLS_ERR_DHM_INVALID_FORMAT, ret );
         goto exit;
     }
 
@@ -531,7 +537,7 @@
     if( ( ret = mbedtls_asn1_get_mpi( &p, end, &dhm->P  ) ) != 0 ||
         ( ret = mbedtls_asn1_get_mpi( &p, end, &dhm->G ) ) != 0 )
     {
-        ret = MBEDTLS_ERR_DHM_INVALID_FORMAT + ret;
+        ret = MBEDTLS_ERROR_ADD( MBEDTLS_ERR_DHM_INVALID_FORMAT, ret );
         goto exit;
     }
 
@@ -545,13 +551,13 @@
         mbedtls_mpi_free( &rec );
         if ( ret != 0 )
         {
-            ret = MBEDTLS_ERR_DHM_INVALID_FORMAT + ret;
+            ret = MBEDTLS_ERROR_ADD( MBEDTLS_ERR_DHM_INVALID_FORMAT, ret );
             goto exit;
         }
         if ( p != end )
         {
-            ret = MBEDTLS_ERR_DHM_INVALID_FORMAT +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH;
+            ret = MBEDTLS_ERROR_ADD( MBEDTLS_ERR_DHM_INVALID_FORMAT,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
             goto exit;
         }
     }