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Merge remote-tracking branch 'public/pr/2922' into baremetal

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This commit is contained in:
Simon Butcher 2019-12-05 14:31:03 +00:00
parent 098846287f 65be6b48de
commit 7c5de360da
3 changed files with 76 additions and 26 deletions
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12
include/mbedtls/platform.h
View file

@ -39,14 +39,16 @@
#include MBEDTLS_CONFIG_FILE
#endif
#if defined(MBEDTLS_HAVE_TIME)
#include "platform_time.h"
#endif
#define MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED -0x0070 /**< Hardware accelerator failed */
#define MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED -0x0072 /**< The requested feature is not supported by the platform */
#define MBEDTLS_ERR_PLATFORM_FAULT_DETECTED -0x0071 /**< A hardware fault was detected in a critical path. As a security precaution this should be treated as a potential physical attack */
#if defined(MBEDTLS_PLATFORM_C)
#if defined(MBEDTLS_HAVE_TIME)
#include "platform_time.h"
#endif
#ifdef __cplusplus
extern "C" {
#endif
@ -365,4 +367,6 @@ void mbedtls_platform_teardown( mbedtls_platform_context *ctx );
}
#endif
#endif /* MBEDTLS_PLATFORM_C */
#endif /* platform.h */

2
include/mbedtls/x509.h
View file

@ -85,6 +85,8 @@
* \{
*/
/* Reminder: update x509_crt_verify_strings[] in library/x509_crt.c */
/* Reminder: update X509_BADCERT_FI_EXTRA in library/x509_crt.c if using more
* that 24 bits */
#define MBEDTLS_X509_BADCERT_EXPIRED 0x01 /**< The certificate validity has expired. */
#define MBEDTLS_X509_BADCERT_REVOKED 0x02 /**< The certificate has been revoked (is on a CRL). */
#define MBEDTLS_X509_BADCERT_CN_MISMATCH 0x04 /**< The certificate Common Name (CN) does not match with the expected CN. */

88
library/x509_crt.c
View file

@ -43,6 +43,7 @@
#include "mbedtls/x509_internal.h"
#include "mbedtls/oid.h"
#include "mbedtls/platform_util.h"
#include "mbedtls/platform.h"
#include <string.h>
@ -2884,6 +2885,10 @@ static int x509_crt_check_parent( const mbedtls_x509_crt_sig_info *sig_info,
return( 0 );
}
/* This value is different enough from 0 that it's hard for an active physical
* attacker to reach it just by flipping a few bits. */
#define X509_SIGNATURE_IS_GOOD 0x7f5a5a5a
/*
* Find a suitable parent for child in candidates, or return NULL.
*
@ -2915,7 +2920,8 @@ static int x509_crt_check_parent( const mbedtls_x509_crt_sig_info *sig_info,
* - [in] child: certificate for which we're looking for a parent
* - [in] candidates: chained list of potential parents
* - [out] r_parent: parent found (or NULL)
* - [out] r_signature_is_good: 1 if child signature by parent is valid, or 0
* - [out] r_signature_is_good: set to X509_SIGNATURE_IS_GOOD if
* child signature by parent is valid, or to 0
* - [in] top: 1 if candidates consists of trusted roots, ie we're at the top
* of the chain, 0 otherwise
* - [in] path_cnt: number of intermediates seen so far
@ -2938,8 +2944,9 @@ static int x509_crt_find_parent_in(
mbedtls_x509_crt_restart_ctx *rs_ctx )
{
int ret;
volatile int ret_fi = MBEDTLS_ERR_PLATFORM_FAULT_DETECTED;
mbedtls_x509_crt *parent_crt;
int signature_is_good;
int signature_is_good = 0;
#if defined(MBEDTLS_HAVE_TIME_DATE)
mbedtls_x509_crt *fallback_parent;
@ -3018,10 +3025,10 @@ check_signature:
continue;
/* Signature */
ret = x509_crt_check_signature( child_sig, parent_crt, rs_ctx );
ret_fi = x509_crt_check_signature( child_sig, parent_crt, rs_ctx );
#if defined(MBEDTLS_ECDSA_C) && defined(MBEDTLS_ECP_RESTARTABLE)
if( rs_ctx != NULL && ret == MBEDTLS_ERR_ECP_IN_PROGRESS )
if( rs_ctx != NULL && ret_fi == MBEDTLS_ERR_ECP_IN_PROGRESS )
{
/* save state */
rs_ctx->parent = parent_crt;
@ -3030,13 +3037,17 @@ check_signature:
rs_ctx->fallback_signature_is_good = fallback_signature_is_good;
#endif /* MBEDTLS_HAVE_TIME_DATE */
return( ret );
return( ret_fi );
}
#else
(void) ret;
#endif
signature_is_good = ret == 0;
if( ret_fi == 0 )
{
mbedtls_platform_enforce_volatile_reads();
if( ret_fi == 0 )
signature_is_good = X509_SIGNATURE_IS_GOOD;
}
if( top && ! signature_is_good )
continue;
@ -3317,6 +3328,23 @@ static unsigned x509_crt_verify_chain_len(
#endif /* MBEDTLS_X509_REMOVE_VERIFY_CALLBACK */
/*
* This is used in addition to the flag for a specific issue, to ensure that
* it is not possible for an active physical attacker to entirely clear the
* flags just by flipping a single bit. Take advantage of the fact that all
* values defined in include/mbedtls/x509.h so far are 24-bit or less, so the
* top byte is free.
*
* Currently this protection is not compatible with the vrfy callback (as it
* can observ and modify flags freely), so it's only enabled when the callback
* is disabled.
*/
#if defined(MBEDTLS_X509_REMOVE_VERIFY_CALLBACK)
#define X509_BADCERT_FI_EXTRA 0xff000000u
#else
#define X509_BADCERT_FI_EXTRA 0u
#endif
/*
* Build and verify a certificate chain
*
@ -3374,6 +3402,7 @@ static int x509_crt_verify_chain(
int parent_is_trusted;
int child_is_trusted;
int signature_is_good;
volatile int signature_is_good_fi;
unsigned self_cnt;
#if defined(MBEDTLS_ECDSA_C) && defined(MBEDTLS_ECP_RESTARTABLE)
@ -3422,9 +3451,9 @@ find_parent:
#if !defined(MBEDTLS_X509_CRT_REMOVE_TIME)
/* Check time-validity (all certificates) */
if( mbedtls_x509_time_is_past( &child->valid_to ) )
*flags |= MBEDTLS_X509_BADCERT_EXPIRED;
*flags |= MBEDTLS_X509_BADCERT_EXPIRED | X509_BADCERT_FI_EXTRA;
if( mbedtls_x509_time_is_future( &child->valid_from ) )
*flags |= MBEDTLS_X509_BADCERT_FUTURE;
*flags |= MBEDTLS_X509_BADCERT_FUTURE | X509_BADCERT_FI_EXTRA;
#endif /* !MBEDTLS_X509_CRT_REMOVE_TIME */
/* Stop here for trusted roots (but not for trusted EE certs) */
@ -3444,10 +3473,10 @@ find_parent:
/* Check signature algorithm: MD & PK algs */
if( x509_profile_check_md_alg( profile, child->sig_md ) != 0 )
*flags |= MBEDTLS_X509_BADCERT_BAD_MD;
*flags |= MBEDTLS_X509_BADCERT_BAD_MD | X509_BADCERT_FI_EXTRA;
if( x509_profile_check_pk_alg( profile, child->sig_pk ) != 0 )
*flags |= MBEDTLS_X509_BADCERT_BAD_PK;
*flags |= MBEDTLS_X509_BADCERT_BAD_PK | X509_BADCERT_FI_EXTRA;
/* Special case: EE certs that are locally trusted */
if( x509_crt_verify_chain_len( ver_chain ) == 1 && self_issued &&
@ -3495,7 +3524,7 @@ find_parent:
/* No parent? We're done here */
if( parent_crt == NULL )
{
*flags |= MBEDTLS_X509_BADCERT_NOT_TRUSTED;
*flags |= MBEDTLS_X509_BADCERT_NOT_TRUSTED | X509_BADCERT_FI_EXTRA;
return( 0 );
}
@ -3516,8 +3545,13 @@ find_parent:
}
/* signature was checked while searching parent */
if( ! signature_is_good )
*flags |= MBEDTLS_X509_BADCERT_NOT_TRUSTED;
signature_is_good_fi = signature_is_good;
if( signature_is_good_fi != X509_SIGNATURE_IS_GOOD )
*flags |= MBEDTLS_X509_BADCERT_NOT_TRUSTED | X509_BADCERT_FI_EXTRA;
mbedtls_platform_enforce_volatile_reads();
if( signature_is_good_fi != X509_SIGNATURE_IS_GOOD )
*flags |= MBEDTLS_X509_BADCERT_NOT_TRUSTED | X509_BADCERT_FI_EXTRA;
{
mbedtls_pk_context *parent_pk;
@ -3527,7 +3561,7 @@ find_parent:
/* check size of signing key */
if( x509_profile_check_key( profile, parent_pk ) != 0 )
*flags |= MBEDTLS_X509_BADCERT_BAD_KEY;
*flags |= MBEDTLS_X509_BADCERT_BAD_KEY | X509_BADCERT_FI_EXTRA;
mbedtls_x509_crt_pk_release( parent_crt );
}
@ -3658,7 +3692,7 @@ static int x509_crt_verify_name( const mbedtls_x509_crt *crt,
if( ret != 0 )
ret = MBEDTLS_ERR_X509_FATAL_ERROR;
*flags |= MBEDTLS_X509_BADCERT_CN_MISMATCH;
*flags |= MBEDTLS_X509_BADCERT_CN_MISMATCH | X509_BADCERT_FI_EXTRA;
return( ret );
}
#endif /* !MBEDTLS_X509_REMOVE_HOSTNAME_VERIFICATION */
@ -3747,6 +3781,7 @@ int mbedtls_x509_crt_verify_restartable( mbedtls_x509_crt *crt,
int ret;
mbedtls_x509_crt_verify_chain ver_chain;
uint32_t ee_flags;
volatile uint32_t flags_fi = (uint32_t) -1;
*flags = 0;
ee_flags = 0;
@ -3780,10 +3815,10 @@ int mbedtls_x509_crt_verify_restartable( mbedtls_x509_crt *crt,
pk_type = mbedtls_pk_get_type( pk );
if( x509_profile_check_pk_alg( profile, pk_type ) != 0 )
ee_flags |= MBEDTLS_X509_BADCERT_BAD_PK;
ee_flags |= MBEDTLS_X509_BADCERT_BAD_PK | X509_BADCERT_FI_EXTRA;
if( x509_profile_check_key( profile, pk ) != 0 )
ee_flags |= MBEDTLS_X509_BADCERT_BAD_KEY;
ee_flags |= MBEDTLS_X509_BADCERT_BAD_KEY | X509_BADCERT_FI_EXTRA;
mbedtls_x509_crt_pk_release( crt );
}
@ -3823,10 +3858,19 @@ exit:
return( ret );
}
if( *flags != 0 )
return( MBEDTLS_ERR_X509_CERT_VERIFY_FAILED );
flags_fi = *flags;
if( flags_fi == 0 )
{
mbedtls_platform_enforce_volatile_reads();
if( flags_fi == 0 )
return( 0 );
}
return( 0 );
/* Preserve the API by removing internal extra bits - from now on the
* fact that flags is non-zero is also redundantly encoded by the
* non-zero return value from this function. */
*flags &= ~ X509_BADCERT_FI_EXTRA;
return( MBEDTLS_ERR_X509_CERT_VERIFY_FAILED );
}
/*