1 files changed, 35 insertions, 11 deletions

diff --git a/thirdparty/mbedtls/library/rsa.c b/thirdparty/mbedtls/library/rsa.c
index af1cef6515..42becbf17b 100644
--- a/thirdparty/mbedtls/library/rsa.c
+++ b/thirdparty/mbedtls/library/rsa.c
@@ -1,7 +1,7 @@
 /*
  *  The RSA public-key cryptosystem
  *
- *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
+ *  Copyright The Mbed TLS Contributors
  *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
  *
  *  This file is provided under the Apache License 2.0, or the
@@ -42,8 +42,6 @@
  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  *  **********
- *
- *  This file is part of mbed TLS (https://tls.mbed.org)
  */
 
 /*
@@ -83,7 +81,7 @@
 #include "mbedtls/md.h"
 #endif
 
-#if defined(MBEDTLS_PKCS1_V15) && !defined(__OpenBSD__)
+#if defined(MBEDTLS_PKCS1_V15) && !defined(__OpenBSD__) && !defined(__NetBSD__)
 #include <stdlib.h>
 #endif
 
@@ -808,6 +806,9 @@ static int rsa_prepare_blinding( mbedtls_rsa_context *ctx,
                  int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
 {
     int ret, count = 0;
+    mbedtls_mpi R;
+
+    mbedtls_mpi_init( &R );
 
     if( ctx->Vf.p != NULL )
     {
@@ -823,18 +824,41 @@ static int rsa_prepare_blinding( mbedtls_rsa_context *ctx,
     /* Unblinding value: Vf = random number, invertible mod N */
     do {
         if( count++ > 10 )
-            return( MBEDTLS_ERR_RSA_RNG_FAILED );
+        {
+            ret = MBEDTLS_ERR_RSA_RNG_FAILED;
+            goto cleanup;
+        }
 
         MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &ctx->Vf, ctx->len - 1, f_rng, p_rng ) );
-        MBEDTLS_MPI_CHK( mbedtls_mpi_gcd( &ctx->Vi, &ctx->Vf, &ctx->N ) );
-    } while( mbedtls_mpi_cmp_int( &ctx->Vi, 1 ) != 0 );
 
-    /* Blinding value: Vi =  Vf^(-e) mod N */
-    MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &ctx->Vi, &ctx->Vf, &ctx->N ) );
+        /* Compute Vf^-1 as R * (R Vf)^-1 to avoid leaks from inv_mod. */
+        MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &R, ctx->len - 1, f_rng, p_rng ) );
+        MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vi, &ctx->Vf, &R ) );
+        MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vi, &ctx->Vi, &ctx->N ) );
+
+        /* At this point, Vi is invertible mod N if and only if both Vf and R
+         * are invertible mod N. If one of them isn't, we don't need to know
+         * which one, we just loop and choose new values for both of them.
+         * (Each iteration succeeds with overwhelming probability.) */
+        ret = mbedtls_mpi_inv_mod( &ctx->Vi, &ctx->Vi, &ctx->N );
+        if( ret == MBEDTLS_ERR_MPI_NOT_ACCEPTABLE )
+            continue;
+        if( ret != 0 )
+            goto cleanup;
+
+        /* Finish the computation of Vf^-1 = R * (R Vf)^-1 */
+        MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vi, &ctx->Vi, &R ) );
+        MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vi, &ctx->Vi, &ctx->N ) );
+    } while( 0 );
+
+    /* Blinding value: Vi = Vf^(-e) mod N
+     * (Vi already contains Vf^-1 at this point) */
     MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &ctx->Vi, &ctx->Vi, &ctx->E, &ctx->N, &ctx->RN ) );
 
 
 cleanup:
+    mbedtls_mpi_free( &R );
+
     return( ret );
 }
 
@@ -2590,7 +2614,7 @@ void mbedtls_rsa_free( mbedtls_rsa_context *ctx )
 #if defined(MBEDTLS_PKCS1_V15)
 static int myrand( void *rng_state, unsigned char *output, size_t len )
 {
-#if !defined(__OpenBSD__)
+#if !defined(__OpenBSD__) && !defined(__NetBSD__)
     size_t i;
 
     if( rng_state != NULL )
@@ -2603,7 +2627,7 @@ static int myrand( void *rng_state, unsigned char *output, size_t len )
         rng_state = NULL;
 
     arc4random_buf( output, len );
-#endif /* !OpenBSD */
+#endif /* !OpenBSD && !NetBSD */
 
     return( 0 );
 }