From cf0a9f96c520f84a4299f68213dc0dbe06a273d0 Mon Sep 17 00:00:00 2001 From: Paul Bakker Date: Wed, 1 Jun 2016 11:25:44 +0100 Subject: [PATCH] Introduce platform-layer functions for reading/writing seed from NV Introduces mbedtls_nv_seed_read() and mbedtls_nv_seed_write(). The platform-layer functions are only available when MBEDTLS_ENTROPY_NV_SEED is enabled. --- include/mbedtls/check_config.h | 34 ++++++++++++- include/mbedtls/config.h | 25 ++++++++++ include/mbedtls/platform.h | 53 +++++++++++++++++++- library/platform.c | 89 +++++++++++++++++++++++++++++++++- 4 files changed, 198 insertions(+), 3 deletions(-) diff --git a/include/mbedtls/check_config.h b/include/mbedtls/check_config.h index 407cd571a..63f93ec16 100644 --- a/include/mbedtls/check_config.h +++ b/include/mbedtls/check_config.h @@ -3,7 +3,7 @@ * * \brief Consistency checks for configuration options * - * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved + * Copyright (C) 2006-2016, ARM Limited, All Rights Reserved * SPDX-License-Identifier: Apache-2.0 * * Licensed under the Apache License, Version 2.0 (the "License"); you may @@ -368,6 +368,38 @@ #error "MBEDTLS_PLATFORM_STD_SNPRINTF defined, but not all prerequisites" #endif +#if defined(MBEDTLS_ENTROPY_NV_SEED) &&\ + ( !defined(MBEDTLS_PLATFORM_C) || !defined(MBEDTLS_ENTROPY_C) ) +#error "MBEDTLS_ENTROPY_NV_SEED defined, but not all prerequisites" +#endif + +#if defined(MBEDTLS_PLATFORM_NV_SEED_ALT) &&\ + !defined(MBEDTLS_ENTROPY_NV_SEED) +#error "MBEDTLS_PLATFORM_NV_SEED_ALT defined, but not all prerequisites" +#endif + +#if defined(MBEDTLS_PLATFORM_STD_NV_SEED_READ) &&\ + !defined(MBEDTLS_PLATFORM_NV_SEED_ALT) +#error "MBEDTLS_PLATFORM_STD_NV_SEED_READ defined, but not all prerequisites" +#endif + +#if defined(MBEDTLS_PLATFORM_STD_NV_SEED_WRITE) &&\ + !defined(MBEDTLS_PLATFORM_NV_SEED_ALT) +#error "MBEDTLS_PLATFORM_STD_NV_SEED_WRITE defined, but not all prerequisites" +#endif + +#if defined(MBEDTLS_PLATFORM_NV_SEED_READ_MACRO) &&\ + ( defined(MBEDTLS_PLATFORM_STD_NV_SEED_READ) ||\ + defined(MBEDTLS_PLATFORM_NV_SEED_ALT) ) +#error "MBEDTLS_PLATFORM_NV_SEED_READ_MACRO and MBEDTLS_PLATFORM_STD_NV_SEED_READ cannot be defined simultaneously" +#endif + +#if defined(MBEDTLS_PLATFORM_NV_SEED_WRITE_MACRO) &&\ + ( defined(MBEDTLS_PLATFORM_STD_NV_SEED_WRITE) ||\ + defined(MBEDTLS_PLATFORM_NV_SEED_ALT) ) +#error "MBEDTLS_PLATFORM_NV_SEED_WRITE_MACRO and MBEDTLS_PLATFORM_STD_NV_SEED_WRITE cannot be defined simultaneously" +#endif + #if defined(MBEDTLS_RSA_C) && ( !defined(MBEDTLS_BIGNUM_C) || \ !defined(MBEDTLS_OID_C) ) #error "MBEDTLS_RSA_C defined, but not all prerequisites" diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h index f800f1346..3e12f43dd 100644 --- a/include/mbedtls/config.h +++ b/include/mbedtls/config.h @@ -156,6 +156,7 @@ //#define MBEDTLS_PLATFORM_FPRINTF_ALT //#define MBEDTLS_PLATFORM_PRINTF_ALT //#define MBEDTLS_PLATFORM_SNPRINTF_ALT +//#define MBEDTLS_PLATFORM_NV_SEED_ALT /** * \def MBEDTLS_DEPRECATED_WARNING @@ -824,6 +825,25 @@ */ //#define MBEDTLS_ENTROPY_FORCE_SHA256 +/** + * \def MBEDTLS_ENTROPY_NV_SEED + * + * Enable the non-volatile (NV) seed file-based entropy source. + * (Also enables the NV seed read/write functions in the platform layer) + * + * This is crucial (if not required) on systems that do not have a + * cryptographic entropy source (in hardware or kernel) available. + * + * Requires: MBEDTLS_ENTROPY_C, MBEDTLS_PLATFORM_C + * + * Note: If you use the default implementation functions that read a seedfile + * with regular fopen(), please make sure you make a seedfile with the + * proper name (defined in MBEDTLS_PLATFORM_STD_NV_SEED_FILE) and at + * least MBEDTLS_ENTROPY_BLOCK_SIZE bytes in size that can be read from + * and written to or you will get an entropy source error! + */ +//#define MBEDTLS_ENTROPY_NV_SEED + /** * \def MBEDTLS_MEMORY_DEBUG * @@ -2498,6 +2518,9 @@ //#define MBEDTLS_PLATFORM_STD_SNPRINTF snprintf /**< Default snprintf to use, can be undefined */ //#define MBEDTLS_PLATFORM_STD_EXIT_SUCCESS 0 /**< Default exit value to use, can be undefined */ //#define MBEDTLS_PLATFORM_STD_EXIT_FAILURE 1 /**< Default exit value to use, can be undefined */ +//#define MBEDTLS_PLATFORM_STD_NV_SEED_READ mbedtls_platform_std_nv_seed_read /**< Default nv_seed_read function to use, can be undefined */ +//#define MBEDTLS_PLATFORM_STD_NV_SEED_WRITE mbedtls_platform_std_nv_seed_write /**< Default nv_seed_write function to use, can be undefined */ +//#define MBEDTLS_PLATFORM_STD_NV_SEED_FILE "seedfile" /**< Seed file to read/write with default implementation */ /* To Use Function Macros MBEDTLS_PLATFORM_C must be enabled */ /* MBEDTLS_PLATFORM_XXX_MACRO and MBEDTLS_PLATFORM_XXX_ALT cannot both be defined */ @@ -2510,6 +2533,8 @@ //#define MBEDTLS_PLATFORM_PRINTF_MACRO printf /**< Default printf macro to use, can be undefined */ /* Note: your snprintf must correclty zero-terminate the buffer! */ //#define MBEDTLS_PLATFORM_SNPRINTF_MACRO snprintf /**< Default snprintf macro to use, can be undefined */ +//#define MBEDTLS_PLATFORM_NV_SEED_READ_MACRO mbedtls_platform_std_nv_seed_read /**< Default nv_seed_read function to use, can be undefined */ +//#define MBEDTLS_PLATFORM_NV_SEED_WRITE_MACRO mbedtls_platform_std_nv_seed_write /**< Default nv_seed_write function to use, can be undefined */ /* SSL Cache options */ //#define MBEDTLS_SSL_CACHE_DEFAULT_TIMEOUT 86400 /**< 1 day */ diff --git a/include/mbedtls/platform.h b/include/mbedtls/platform.h index 039cb587a..10137d781 100644 --- a/include/mbedtls/platform.h +++ b/include/mbedtls/platform.h @@ -3,7 +3,7 @@ * * \brief mbed TLS Platform abstraction layer * - * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved + * Copyright (C) 2006-2016, ARM Limited, All Rights Reserved * SPDX-License-Identifier: Apache-2.0 * * Licensed under the Apache License, Version 2.0 (the "License"); you may @@ -76,12 +76,22 @@ extern "C" { #if !defined(MBEDTLS_PLATFORM_STD_EXIT_FAILURE) #define MBEDTLS_PLATFORM_STD_EXIT_FAILURE EXIT_FAILURE /**< Default exit value to use */ #endif +#if !defined(MBEDTLS_PLATFORM_STD_NV_SEED_READ) +#define MBEDTLS_PLATFORM_STD_NV_SEED_READ mbedtls_platform_std_nv_seed_read +#endif +#if !defined(MBEDTLS_PLATFORM_STD_NV_SEED_WRITE) +#define MBEDTLS_PLATFORM_STD_NV_SEED_WRITE mbedtls_platform_std_nv_seed_write +#endif +#if !defined(MBEDTLS_PLATFORM_STD_NV_SEED_FILE) +#define MBEDTLS_PLATFORM_STD_NV_SEED_FILE "seedfile" +#endif #else /* MBEDTLS_PLATFORM_NO_STD_FUNCTIONS */ #if defined(MBEDTLS_PLATFORM_STD_MEM_HDR) #include MBEDTLS_PLATFORM_STD_MEM_HDR #endif #endif /* MBEDTLS_PLATFORM_NO_STD_FUNCTIONS */ + /* \} name SECTION: Module settings */ /* @@ -262,6 +272,47 @@ int mbedtls_platform_set_time( mbedtls_time_t (*time_func)( mbedtls_time_t* time #endif /* MBEDTLS_PLATFORM_TIME_MACRO */ #endif /* MBEDTLS_PLATFORM_TIME_ALT */ +/* + * The function pointers for reading from and writing a seed file to + * Non-Volatile storage (NV) in a platform-independent way + * + * Only enabled when the NV seed entropy source is enabled + */ +#if defined(MBEDTLS_ENTROPY_NV_SEED) +#if !defined(MBEDTLS_PLATFORM_NO_STD_FUNCTIONS) && defined(MBEDTLS_FS_IO) +/* Internal standard platform definitions */ +int mbedtls_platform_std_nv_seed_read( unsigned char *buf, size_t buf_len ); +int mbedtls_platform_std_nv_seed_write( unsigned char *buf, size_t buf_len ); +#endif + +#if defined(MBEDTLS_PLATFORM_NV_SEED_ALT) +extern int (*mbedtls_nv_seed_read)( unsigned char *buf, size_t buf_len ); +extern int (*mbedtls_nv_seed_write)( unsigned char *buf, size_t buf_len ); + +/** + * \brief Set your own seed file writing/reading functions + * + * \param nv_seed_read_func the seed reading function implementation + * \param nv_seed_write_func the seed writing function implementation + * + * \return 0 + */ +int mbedtls_platform_set_nv_seed( + int (*nv_seed_read_func)( unsigned char *buf, size_t buf_len ), + int (*nv_seed_write_func)( unsigned char *buf, size_t buf_len ) + ); +#else +#if defined(MBEDTLS_PLATFORM_NV_SEED_READ_MACRO) && \ + defined(MBEDTLS_PLATFORM_NV_SEED_WRITE_MACRO) +#define mbedtls_nv_seed_read MBEDTLS_PLATFORM_NV_SEED_READ_MACRO +#define mbedtls_nv_seed_write MBEDTLS_PLATFORM_NV_SEED_WRITE_MACRO +#else +#define mbedtls_nv_seed_read mbedtls_platform_std_nv_seed_read +#define mbedtls_nv_seed_write mbedtls_platform_std_nv_seed_write +#endif +#endif /* MBEDTLS_PLATFORM_NV_SEED_ALT */ +#endif /* MBEDTLS_ENTROPY_NV_SEED */ + #ifdef __cplusplus } #endif diff --git a/library/platform.c b/library/platform.c index 89a2bd65d..68ca45d10 100644 --- a/library/platform.c +++ b/library/platform.c @@ -1,7 +1,7 @@ /* * Platform abstraction layer * - * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved + * Copyright (C) 2006-2016, ARM Limited, All Rights Reserved * SPDX-License-Identifier: Apache-2.0 * * Licensed under the Apache License, Version 2.0 (the "License"); you may @@ -213,4 +213,91 @@ int mbedtls_platform_set_time( mbedtls_time_t (*time_func)( mbedtls_time_t* time } #endif /* MBEDTLS_PLATFORM_TIME_ALT */ +#if defined(MBEDTLS_ENTROPY_NV_SEED) +#if !defined(MBEDTLS_PLATFORM_NO_STD_FUNCTIONS) && defined(MBEDTLS_FS_IO) +/* Default implementations for the platform independent seed functions use + * standard libc file functions to read from and write to a pre-defined filename + */ +int mbedtls_platform_std_nv_seed_read( unsigned char *buf, size_t buf_len ) +{ + FILE *file; + size_t n; + + if( ( file = fopen( MBEDTLS_PLATFORM_STD_NV_SEED_FILE, "rb" ) ) == NULL ) + return -1; + + if( ( n = fread( buf, 1, buf_len, file ) ) != buf_len ) + { + fclose( file ); + return -1; + } + + fclose( file ); + return( n ); +} + +int mbedtls_platform_std_nv_seed_write( unsigned char *buf, size_t buf_len ) +{ + FILE *file; + size_t n; + + if( ( file = fopen( MBEDTLS_PLATFORM_STD_NV_SEED_FILE, "w" ) ) == NULL ) + return -1; + + if( ( n = fwrite( buf, 1, buf_len, file ) ) != buf_len ) + { + fclose( file ); + return -1; + } + + fclose( file ); + return( n ); +} +#endif /* MBEDTLS_PLATFORM_NO_STD_FUNCTIONS */ + +#if defined(MBEDTLS_PLATFORM_NV_SEED_ALT) +#if !defined(MBEDTLS_PLATFORM_STD_NV_SEED_READ) +/* + * Make dummy function to prevent NULL pointer dereferences + */ +static int platform_nv_seed_read_uninit( unsigned char *buf, size_t buf_len ) +{ + ((void) buf); + ((void) buf_len); + return( -1 ); +} + +#define MBEDTLS_PLATFORM_STD_NV_SEED_READ platform_nv_seed_read_uninit +#endif /* !MBEDTLS_PLATFORM_STD_NV_SEED_READ */ + +#if !defined(MBEDTLS_PLATFORM_STD_NV_SEED_WRITE) +/* + * Make dummy function to prevent NULL pointer dereferences + */ +static int platform_nv_seed_write_uninit( unsigned char *buf, size_t buf_len ) +{ + ((void) buf); + ((void) buf_len); + return( -1 ); +} + +#define MBEDTLS_PLATFORM_STD_NV_SEED_WRITE platform_nv_seed_write_uninit +#endif /* !MBEDTLS_PLATFORM_STD_NV_SEED_WRITE */ + +int (*mbedtls_nv_seed_read)( unsigned char *buf, size_t buf_len ) = + MBEDTLS_PLATFORM_STD_NV_SEED_READ; +int (*mbedtls_nv_seed_write)( unsigned char *buf, size_t buf_len ) = + MBEDTLS_PLATFORM_STD_NV_SEED_WRITE; + +int mbedtls_platform_set_nv_seed( + int (*nv_seed_read_func)( unsigned char *buf, size_t buf_len ), + int (*nv_seed_write_func)( unsigned char *buf, size_t buf_len ) ) +{ + mbedtls_nv_seed_read = nv_seed_read_func; + mbedtls_nv_seed_write = nv_seed_write_func; + return( 0 ); +} +#endif /* MBEDTLS_PLATFORM_NV_SEED_ALT */ +#endif /* MBEDTLS_ENTROPY_NV_SEED */ + #endif /* MBEDTLS_PLATFORM_C */