commit e97dc60b42481b77dbb2f1ae2fdae4a22fc385c1
author Gilles Peskine <Gilles.Peskine@arm.com> Wed Dec 19 00:51:38 2018 +0100
committer Gilles Peskine <Gilles.Peskine@arm.com> Wed Dec 19 00:55:36 2018 +0100
tree 4524cfcb48728b1cf248d25f885738c05f89ecf7
parent a310b41ebecf9724934666941df6d29ae2cbe8c2

Implement parameter validation in pk, pkparse and pkwrite

Add checks for null pointers under MBEDTLS_CHECK_PARAMS.

In functions that perform operations with a context, only check if the
context pointer is non-null under MBEDTLS_CHECK_PARAMS. In the default
configuration, unconditionally dereference the context pointer.

In functions that query a context, support NULL as a
pointer-to-context argument, and return the same value as for a
context which has been initialized but not set up.

library/pkwrite.c

diff --git a/library/pkwrite.c b/library/pkwrite.c
index 8eabd88..51d0c56 100644
--- a/library/pkwrite.c
+++ b/library/pkwrite.c
@@ -30,6 +30,7 @@
 #include "mbedtls/pk.h"
 #include "mbedtls/asn1write.h"
 #include "mbedtls/oid.h"
+#include "mbedtls/platform_util.h"
 
 #include <string.h>
 
@@ -54,6 +55,12 @@
 #define mbedtls_free       free
 #endif
 
+/* Parameter validation macros based on platform_util.h */
+#define PK_VALIDATE_RET( cond )    \
+    MBEDTLS_INTERNAL_VALIDATE_RET( cond, MBEDTLS_ERR_PK_BAD_INPUT_DATA )
+#define PK_VALIDATE( cond )        \
+    MBEDTLS_INTERNAL_VALIDATE( cond )
+
 #if defined(MBEDTLS_RSA_C)
 /*
  *  RSAPublicKey ::= SEQUENCE {
@@ -151,6 +158,11 @@
     int ret;
     size_t len = 0;
 
+    PK_VALIDATE_RET( p != NULL );
+    PK_VALIDATE_RET( *p != NULL );
+    PK_VALIDATE_RET( start != NULL );
+    PK_VALIDATE_RET( key != NULL );
+
 #if defined(MBEDTLS_RSA_C)
     if( mbedtls_pk_get_type( key ) == MBEDTLS_PK_RSA )
         MBEDTLS_ASN1_CHK_ADD( len, pk_write_rsa_pubkey( p, start, mbedtls_pk_rsa( *key ) ) );
@@ -173,6 +185,9 @@
     size_t len = 0, par_len = 0, oid_len;
     const char *oid;
 
+    PK_VALIDATE_RET( key != NULL );
+    PK_VALIDATE_RET( buf != NULL || size == 0 );
+
     c = buf + size;
 
     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_pk_write_pubkey( &c, buf, key ) );
@@ -217,9 +232,14 @@
 int mbedtls_pk_write_key_der( mbedtls_pk_context *key, unsigned char *buf, size_t size )
 {
     int ret;
-    unsigned char *c = buf + size;
+    unsigned char *c;
     size_t len = 0;
 
+    PK_VALIDATE_RET( key != NULL );
+    PK_VALIDATE_RET( buf != NULL || size == 0 );
+
+    c = buf + size;
+
 #if defined(MBEDTLS_RSA_C)
     if( mbedtls_pk_get_type( key ) == MBEDTLS_PK_RSA )
     {
@@ -457,6 +477,9 @@
     unsigned char output_buf[PUB_DER_MAX_BYTES];
     size_t olen = 0;
 
+    PK_VALIDATE_RET( key != NULL );
+    PK_VALIDATE_RET( buf != NULL || size == 0 );
+
     if( ( ret = mbedtls_pk_write_pubkey_der( key, output_buf,
                                      sizeof(output_buf) ) ) < 0 )
     {
@@ -480,6 +503,9 @@
     const char *begin, *end;
     size_t olen = 0;
 
+    PK_VALIDATE_RET( key != NULL );
+    PK_VALIDATE_RET( buf != NULL || size == 0 );
+
     if( ( ret = mbedtls_pk_write_key_der( key, output_buf, sizeof(output_buf) ) ) < 0 )
         return( ret );