commit d5253bba324b2a31ad752f152ac424ccbf5dc00f
author gabor-mezei-arm <gabor.mezei@arm.com> Thu Jul 30 16:41:25 2020 +0200
committer gabor-mezei-arm <gabor.mezei@arm.com> Wed Sep 09 15:16:01 2020 +0200
tree 809bfe198b8804fe7e7724359b6bd055c2e552c8
parent fa3b3e0d88c3dcbf2650d0bcadaf365896c2abf7

Zeroize internal buffers and variables in PKCS and SHA

Zeroising of local buffers and variables which are used for calculations in
mbedtls_pkcs5_pbkdf2_hmac() and mbedtls_internal_sha*_process() functions
to erase sensitive data from memory.
Checked all function for possible missing zeroisation in PKCS and SHA.

Signed-off-by: gabor-mezei-arm <gabor.mezei@arm.com>

ChangeLog.d/zeroizations_of_sensitive_data_in_PKCS5_and_SHA.txt

diff --git a/ChangeLog.d/zeroizations_of_sensitive_data_in_PKCS5_and_SHA.txt b/ChangeLog.d/zeroizations_of_sensitive_data_in_PKCS5_and_SHA.txt
new file mode 100644
index 0000000..f844561
--- /dev/null
+++ b/ChangeLog.d/zeroizations_of_sensitive_data_in_PKCS5_and_SHA.txt
@@ -0,0 +1,5 @@
+Security
+   * Zeroising of local buffers and variables which are used for calculations
+     in mbedtls_pkcs5_pbkdf2_hmac() and mbedtls_internal_sha*_process()
+     functions to erase sensitive data from memory. Reported by
+     Johan Malmgren and Johan Uppman Bruce from Sectra.

library/pkcs5.c

diff --git a/library/pkcs5.c b/library/pkcs5.c
index 8a80aa5..69b85de 100644
--- a/library/pkcs5.c
+++ b/library/pkcs5.c
@@ -312,6 +312,10 @@
                 break;
     }
 
+    /* Zeroise buffers to clear sensitive data from memory. */
+    mbedtls_platform_zeroize( work, MBEDTLS_MD_MAX_SIZE );
+    mbedtls_platform_zeroize( md1, MBEDTLS_MD_MAX_SIZE );
+
     return( 0 );
 }
 

library/sha1.c

diff --git a/library/sha1.c b/library/sha1.c
index 8682abd..4bb5198 100644
--- a/library/sha1.c
+++ b/library/sha1.c
@@ -313,6 +313,15 @@
     ctx->state[3] += D;
     ctx->state[4] += E;
 
+    /* Zeroise buffers and variables to clear sensitive data from memory. */
+    mbedtls_platform_zeroize( &A, sizeof( A ) );
+    mbedtls_platform_zeroize( &B, sizeof( B ) );
+    mbedtls_platform_zeroize( &C, sizeof( C ) );
+    mbedtls_platform_zeroize( &D, sizeof( D ) );
+    mbedtls_platform_zeroize( &E, sizeof( E ) );
+    mbedtls_platform_zeroize( &W, sizeof( W ) );
+    mbedtls_platform_zeroize( &temp, sizeof( temp ) );
+
     return( 0 );
 }
 

library/sha256.c

diff --git a/library/sha256.c b/library/sha256.c
index 5169584..2decd08 100644
--- a/library/sha256.c
+++ b/library/sha256.c
@@ -281,6 +281,12 @@
     for( i = 0; i < 8; i++ )
         ctx->state[i] += A[i];
 
+    /* Zeroise buffers and variables to clear sensitive data from memory. */
+    mbedtls_platform_zeroize( &A, sizeof( A ) );
+    mbedtls_platform_zeroize( &W, sizeof( W ) );
+    mbedtls_platform_zeroize( &temp1, sizeof( temp1 ) );
+    mbedtls_platform_zeroize( &temp2, sizeof( temp2 ) );
+
     return( 0 );
 }
 

library/sha512.c

diff --git a/library/sha512.c b/library/sha512.c
index 36d5d96..37a01dd 100644
--- a/library/sha512.c
+++ b/library/sha512.c
@@ -312,6 +312,19 @@
     ctx->state[6] += G;
     ctx->state[7] += H;
 
+    /* Zeroise buffers and variables to clear sensitive data from memory. */
+    mbedtls_platform_zeroize( &A, sizeof( A ) );
+    mbedtls_platform_zeroize( &B, sizeof( B ) );
+    mbedtls_platform_zeroize( &C, sizeof( C ) );
+    mbedtls_platform_zeroize( &D, sizeof( D ) );
+    mbedtls_platform_zeroize( &E, sizeof( E ) );
+    mbedtls_platform_zeroize( &F, sizeof( F ) );
+    mbedtls_platform_zeroize( &G, sizeof( G ) );
+    mbedtls_platform_zeroize( &H, sizeof( H ) );
+    mbedtls_platform_zeroize( &W, sizeof( W ) );
+    mbedtls_platform_zeroize( &temp1, sizeof( temp1 ) );
+    mbedtls_platform_zeroize( &temp2, sizeof( temp2 ) );
+
     return( 0 );
 }