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Merge branch 'bugfix/hwcrypt_fault_inj_v3.3' into 'release/v3.3'

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AES & SHA fault injection checks (backport v3.3)

See merge request espressif/esp-idf!5710
This commit is contained in:
Angus Gratton 2019-08-11 14:04:36 +08:00
parent a6fb161309 3991084777
commit beb34b5390
3 changed files with 144 additions and 28 deletions
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133
components/esp32/hwcrypto/aes.c
View file

@ -28,6 +28,7 @@
#include <string.h>
#include "mbedtls/aes.h"
#include "hwcrypto/aes.h"
#include "mbedtls/platform_util.h"
#include "soc/dport_reg.h"
#include "soc/hwcrypto_reg.h"
#include <sys/lock.h>
@ -49,6 +50,11 @@
*/
static portMUX_TYPE aes_spinlock = portMUX_INITIALIZER_UNLOCKED;
static inline bool valid_key_length(const esp_aes_context *ctx)
{
return ctx->key_bytes == 128/8 || ctx->key_bytes == 192/8 || ctx->key_bytes == 256/8;
}
void esp_aes_acquire_hardware( void )
{
portENTER_CRITICAL(&aes_spinlock);
@ -93,6 +99,7 @@ int esp_aes_setkey( esp_aes_context *ctx, const unsigned char *key,
}
ctx->key_bytes = keybits / 8;
memcpy(ctx->key, key, ctx->key_bytes);
ctx->key_in_hardware = 0;
return 0;
}
@ -102,35 +109,83 @@ int esp_aes_setkey( esp_aes_context *ctx, const unsigned char *key,
*
* Call only while holding esp_aes_acquire_hardware().
*/
static inline void esp_aes_setkey_hardware( esp_aes_context *ctx, int mode)
static void esp_aes_setkey_hardware(esp_aes_context *ctx, int mode)
{
const uint32_t MODE_DECRYPT_BIT = 4;
unsigned mode_reg_base = (mode == ESP_AES_ENCRYPT) ? 0 : MODE_DECRYPT_BIT;
ctx->key_in_hardware = 0;
for (int i = 0; i < ctx->key_bytes/4; ++i) {
DPORT_REG_WRITE(AES_KEY_BASE + i * 4, *(((uint32_t *)ctx->key) + i));
ctx->key_in_hardware += 4;
}
DPORT_REG_WRITE(AES_MODE_REG, mode_reg_base + ((ctx->key_bytes / 8) - 2));
/* Fault injection check: all words of key data should have been written to hardware */
if (ctx->key_in_hardware < 16
|| ctx->key_in_hardware != ctx->key_bytes) {
abort();
}
}
/* Run a single 16 byte block of AES, using the hardware engine.
*
* Call only while holding esp_aes_acquire_hardware().
*/
static inline void esp_aes_block(const void *input, void *output)
static int esp_aes_block(esp_aes_context *ctx, const void *input, void *output)
{
const uint32_t *input_words = (const uint32_t *)input;
uint32_t i0, i1, i2, i3;
uint32_t *output_words = (uint32_t *)output;
uint32_t *mem_block = (uint32_t *)AES_TEXT_BASE;
for(int i = 0; i < 4; i++) {
mem_block[i] = input_words[i];
/* If no key is written to hardware yet, either the user hasn't called
mbedtls_aes_setkey_enc/mbedtls_aes_setkey_dec - meaning we also don't
know which mode to use - or a fault skipped the
key write to hardware. Treat this as a fatal error and zero the output block.
*/
if (ctx->key_in_hardware != ctx->key_bytes) {
bzero(output, 16);
return MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH;
}
/* Storing i0,i1,i2,i3 in registers not an array
helps a lot with optimisations at -Os level */
i0 = input_words[0];
DPORT_REG_WRITE(AES_TEXT_BASE, i0);
i1 = input_words[1];
DPORT_REG_WRITE(AES_TEXT_BASE + 4, i1);
i2 = input_words[2];
DPORT_REG_WRITE(AES_TEXT_BASE + 8, i2);
i3 = input_words[3];
DPORT_REG_WRITE(AES_TEXT_BASE + 12, i3);
DPORT_REG_WRITE(AES_START_REG, 1);
while (DPORT_REG_READ(AES_IDLE_REG) != 1) { }
esp_dport_access_read_buffer(output_words, (uint32_t)&mem_block[0], 4);
esp_dport_access_read_buffer(output_words, AES_TEXT_BASE, 4);
/* Physical security check: Verify the AES accelerator actually ran, and wasn't
skipped due to external fault injection while starting the peripheral.
Note that i0,i1,i2,i3 are copied from input buffer in case input==output.
Bypassing this check requires at least one additional fault.
*/
if(i0 == output_words[0] && i1 == output_words[1] && i2 == output_words[2] && i3 == output_words[3]) {
// calling zeroing functions to narrow the
// window for a double-fault of the abort step, here
memset(output, 0, 16);
mbedtls_platform_zeroize(output, 16);
abort();
}
return 0;
}
/*
@ -140,11 +195,18 @@ int esp_internal_aes_encrypt( esp_aes_context *ctx,
const unsigned char input[16],
unsigned char output[16] )
{
int r;
if (!valid_key_length(ctx)) {
return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
}
esp_aes_acquire_hardware();
ctx->key_in_hardware = 0;
esp_aes_setkey_hardware(ctx, ESP_AES_ENCRYPT);
esp_aes_block(input, output);
r = esp_aes_block(ctx, input, output);
esp_aes_release_hardware();
return 0;
return r;
}
void esp_aes_encrypt( esp_aes_context *ctx,
@ -162,11 +224,18 @@ int esp_internal_aes_decrypt( esp_aes_context *ctx,
const unsigned char input[16],
unsigned char output[16] )
{
int r;
if (!valid_key_length(ctx)) {
return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
}
esp_aes_acquire_hardware();
ctx->key_in_hardware = 0;
esp_aes_setkey_hardware(ctx, ESP_AES_DECRYPT);
esp_aes_block(input, output);
r = esp_aes_block(ctx, input, output);
esp_aes_release_hardware();
return 0;
return r;
}
void esp_aes_decrypt( esp_aes_context *ctx,
@ -176,7 +245,6 @@ void esp_aes_decrypt( esp_aes_context *ctx,
esp_internal_aes_decrypt(ctx, input, output);
}
/*
* AES-ECB block encryption/decryption
*/
@ -185,12 +253,19 @@ int esp_aes_crypt_ecb( esp_aes_context *ctx,
const unsigned char input[16],
unsigned char output[16] )
{
int r;
if (!valid_key_length(ctx)) {
return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
}
esp_aes_acquire_hardware();
ctx->key_in_hardware = 0;
esp_aes_setkey_hardware(ctx, mode);
esp_aes_block(input, output);
r = esp_aes_block(ctx, input, output);
esp_aes_release_hardware();
return 0;
return r;
}
@ -214,14 +289,19 @@ int esp_aes_crypt_cbc( esp_aes_context *ctx,
return ( ERR_ESP_AES_INVALID_INPUT_LENGTH );
}
if (!valid_key_length(ctx)) {
return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
}
esp_aes_acquire_hardware();
ctx->key_in_hardware = 0;
esp_aes_setkey_hardware(ctx, mode);
if ( mode == ESP_AES_DECRYPT ) {
while ( length > 0 ) {
memcpy(temp, input_words, 16);
esp_aes_block(input_words, output_words);
esp_aes_block(ctx, input_words, output_words);
for ( i = 0; i < 4; i++ ) {
output_words[i] = output_words[i] ^ iv_words[i];
@ -240,7 +320,7 @@ int esp_aes_crypt_cbc( esp_aes_context *ctx,
output_words[i] = input_words[i] ^ iv_words[i];
}
esp_aes_block(output_words, output_words);
esp_aes_block(ctx, output_words, output_words);
memcpy( iv_words, output_words, 16 );
input_words += 4;
@ -268,14 +348,19 @@ int esp_aes_crypt_cfb128( esp_aes_context *ctx,
int c;
size_t n = *iv_off;
if (!valid_key_length(ctx)) {
return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
}
esp_aes_acquire_hardware();
ctx->key_in_hardware = 0;
esp_aes_setkey_hardware(ctx, ESP_AES_ENCRYPT);
if ( mode == ESP_AES_DECRYPT ) {
while ( length-- ) {
if ( n == 0 ) {
esp_aes_block(iv, iv );
esp_aes_block(ctx, iv, iv );
}
c = *input++;
@ -287,7 +372,7 @@ int esp_aes_crypt_cfb128( esp_aes_context *ctx,
} else {
while ( length-- ) {
if ( n == 0 ) {
esp_aes_block(iv, iv );
esp_aes_block(ctx, iv, iv );
}
iv[n] = *output++ = (unsigned char)( iv[n] ^ *input++ );
@ -316,13 +401,18 @@ int esp_aes_crypt_cfb8( esp_aes_context *ctx,
unsigned char c;
unsigned char ov[17];
if (!valid_key_length(ctx)) {
return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
}
esp_aes_acquire_hardware();
ctx->key_in_hardware = 0;
esp_aes_setkey_hardware(ctx, ESP_AES_ENCRYPT);
while ( length-- ) {
memcpy( ov, iv, 16 );
esp_aes_block(iv, iv);
esp_aes_block(ctx, iv, iv);
if ( mode == ESP_AES_DECRYPT ) {
ov[16] = *input;
@ -356,13 +446,18 @@ int esp_aes_crypt_ctr( esp_aes_context *ctx,
int c, i;
size_t n = *nc_off;
if (!valid_key_length(ctx)) {
return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
}
esp_aes_acquire_hardware();
ctx->key_in_hardware = 0;
esp_aes_setkey_hardware(ctx, ESP_AES_ENCRYPT);
while ( length-- ) {
if ( n == 0 ) {
esp_aes_block(nonce_counter, stream_block);
esp_aes_block(ctx, nonce_counter, stream_block);
for ( i = 16; i > 0; i-- )
if ( ++nonce_counter[i - 1] != 0 ) {

33
components/esp32/hwcrypto/sha.c
View file

@ -226,6 +226,9 @@ void esp_sha_wait_idle(void)
void esp_sha_read_digest_state(esp_sha_type sha_type, void *digest_state)
{
uint32_t *digest_state_words = NULL;
uint32_t *reg_addr_buf = NULL;
uint32_t word_len = sha_length(sha_type)/4;
#ifndef NDEBUG
{
SemaphoreHandle_t *engine_state = sha_get_engine_state(sha_type);
@ -243,20 +246,30 @@ void esp_sha_read_digest_state(esp_sha_type sha_type, void *digest_state)
DPORT_REG_WRITE(SHA_LOAD_REG(sha_type), 1);
while(DPORT_REG_READ(SHA_BUSY_REG(sha_type)) == 1) { }
uint32_t *digest_state_words = (uint32_t *)digest_state;
uint32_t *reg_addr_buf = (uint32_t *)(SHA_TEXT_BASE);
digest_state_words = (uint32_t *)digest_state;
reg_addr_buf = (uint32_t *)(SHA_TEXT_BASE);
if(sha_type == SHA2_384 || sha_type == SHA2_512) {
/* for these ciphers using 64-bit states, swap each pair of words */
DPORT_INTERRUPT_DISABLE(); // Disable interrupt only on current CPU.
for(int i = 0; i < sha_length(sha_type)/4; i += 2) {
for(int i = 0; i < word_len; i += 2) {
digest_state_words[i+1] = DPORT_SEQUENCE_REG_READ((uint32_t)&reg_addr_buf[i]);
digest_state_words[i] = DPORT_SEQUENCE_REG_READ((uint32_t)&reg_addr_buf[i+1]);
}
DPORT_INTERRUPT_RESTORE(); // restore the previous interrupt level
} else {
esp_dport_access_read_buffer(digest_state_words, (uint32_t)&reg_addr_buf[0], sha_length(sha_type)/4);
esp_dport_access_read_buffer(digest_state_words, (uint32_t)&reg_addr_buf[0], word_len);
}
esp_sha_unlock_memory_block();
/* Fault injection check: verify SHA engine actually ran,
state is not all zeroes.
*/
for (int i = 0; i < word_len; i++) {
if (digest_state_words[i] != 0) {
return;
}
}
abort(); // SHA peripheral returned all zero state, probably due to fault injection
}
void esp_sha_block(esp_sha_type sha_type, const void *data_block, bool is_first_block)
@ -310,6 +323,8 @@ void esp_sha(esp_sha_type sha_type, const unsigned char *input, size_t ilen, uns
esp_sha_lock_engine(sha_type);
bzero(output, sha_length(sha_type));
SHA_CTX ctx;
ets_sha_init(&ctx);
@ -353,4 +368,14 @@ void esp_sha(esp_sha_type sha_type, const unsigned char *input, size_t ilen, uns
}
esp_sha_unlock_engine(sha_type);
/* Fault injection check: verify SHA engine actually ran,
state is not all zeroes.
*/
for (int i = 0; i < sha_length(sha_type); i++) {
if (output[i] != 0) {
return;
}
}
abort(); // SHA peripheral returned all zero state, probably due to fault injection
}

6
components/esp32/include/hwcrypto/aes.h
View file

@ -41,17 +41,13 @@ extern "C" {
/**
* \brief AES context structure
*
* \note buf is able to hold 32 extra bytes, which can be used:
* - for alignment purposes if VIA padlock is used, and/or
* - to simplify key expansion in the 256-bit case by
* generating an extra round key
*/
typedef struct {
uint8_t key_bytes;
volatile uint8_t key_in_hardware; /* This variable is used for fault injection checks, so marked volatile to avoid optimisation */
uint8_t key[32];
} esp_aes_context;
/**
* \brief The AES XTS context-type definition.
*/