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Free mbedtls structures after use

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This commit is contained in:
jaseg 2021-07-19 14:14:38 +02:00
parent 0f1ee28337
commit 4a97412516
3 changed files with 91 additions and 47 deletions
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66
demo/fw/src/cage.c
View file

@ -9,7 +9,6 @@
#include "cage.h"
#include "cage_base64.h"
#include "logging.h"
#include "bech32.h"
#include "rng.h"
@ -19,6 +18,9 @@
#include "mbedtls/ecp.h"
#include "mbedtls/ctr_drbg.h"
#include "con_usart.h"
#define LOG_PRINTF con_printf
static enum ca_error parse_stanza(struct ca_keystore *ks, const char *stanza_head, size_t len, unsigned char file_key[16]);
static enum ca_error parse_stanza_x25519(struct ca_keystore *ks, size_t nargs, const char **args, size_t body_len, const unsigned char *body, unsigned char file_key[16]);
@ -28,6 +30,10 @@ void ca_keystore_init(struct ca_keystore *ks) {
mbedtls_ecp_keypair_init(&(ks->x25519_kp));
}
void ca_keystore_free(struct ca_keystore *ks) {
mbedtls_ecp_keypair_free(&(ks->x25519_kp));
}
enum ca_error ca_keystore_load_x25519_private_key(struct ca_keystore *ks, const unsigned char buf[32]) {
/*
@ -233,6 +239,7 @@ errout:
enum ca_error parse_stanza_x25519(struct ca_keystore *ks, size_t nargs, const char **args, size_t body_len, const unsigned char *body, unsigned char file_key[16]) {
int mbedtls_rc = -1;
enum ca_error err = CA_ERR_CORRUPTED_STATE;
/* body length: 16 bytes ciphertext of 128 bit file key + 16 bytes Poly1305 tag */
if (nargs != 1 || body_len != 32) {
@ -266,13 +273,15 @@ enum ca_error parse_stanza_x25519(struct ca_keystore *ks, size_t nargs, const ch
mbedtls_rc = mbedtls_ecp_group_load(&x25519_grp, MBEDTLS_ECP_DP_CURVE25519);
if (mbedtls_rc) {
LOG_PRINTF("Error: mbedtls_ecp_group_load: rc=-0x%x\n", -mbedtls_rc);
return CA_ERR_KEY_WRAPPING_DECRYPTION_FAILURE;
err = CA_ERR_KEY_WRAPPING_DECRYPTION_FAILURE;
goto err_free_grp;
}
mbedtls_rc = mbedtls_ecp_point_read_binary(&x25519_grp, &ecp_ciphertext_pt, ecp_ciphertext, sizeof(ecp_ciphertext));
if (mbedtls_rc) {
LOG_PRINTF("Error: mbedtls_ecp_point_read_binary: rc=-0x%x\n", -mbedtls_rc);
return CA_ERR_KEY_WRAPPING_DECRYPTION_FAILURE;
err = CA_ERR_KEY_WRAPPING_DECRYPTION_FAILURE;
goto err_free_grp;
}
/*
@ -290,7 +299,8 @@ enum ca_error parse_stanza_x25519(struct ca_keystore *ks, size_t nargs, const ch
mbedtls_ctr_drbg_random, g_drbg_ctx);
if (mbedtls_rc) {
LOG_PRINTF("Error: mbedtls_ecp_mul: rc=-0x%x\n", -mbedtls_rc);
return CA_ERR_MBEDTLS_ERROR;
err = CA_ERR_MBEDTLS_ERROR;
goto err_free_dec;
}
@ -310,18 +320,21 @@ enum ca_error parse_stanza_x25519(struct ca_keystore *ks, size_t nargs, const ch
if (mbedtls_rc) {
LOG_PRINTF("Error: mbedtls_ecp_point_write_binary: rc=-0x%x\n", -mbedtls_rc);
return CA_ERR_MBEDTLS_ERROR;
err = CA_ERR_MBEDTLS_ERROR;
goto err_free_dec;
}
if (ecp_plaintext_len != 32) {
LOG_PRINTF("Error: parse_stanza_x25519: (ecp_plaintext_len == %d) != 32 (bug, should not happen!)\n", ecp_plaintext_len);
return CA_ERR_CORRUPTED_STATE;
err = CA_ERR_CORRUPTED_STATE;
goto err_free_dec;
}
const mbedtls_md_info_t *sha256_md = mbedtls_md_info_from_type(MBEDTLS_MD_SHA256);
if (!sha256_md) {
LOG_PRINTF("Error: mbedtls_md_info_from_type: cannot load SHA256\n");
return CA_ERR_MBEDTLS_ERROR;
err = CA_ERR_MBEDTLS_ERROR;
goto err_free_dec;
}
unsigned char salt[64];
@ -331,11 +344,13 @@ enum ca_error parse_stanza_x25519(struct ca_keystore *ks, size_t nargs, const ch
MBEDTLS_ECP_PF_UNCOMPRESSED, &pbin_olen, salt+32, 32);
if (mbedtls_rc) {
LOG_PRINTF("Error: mbedtls_ecp_point_write_binary: rc=-0x%x\n", -mbedtls_rc);
return CA_ERR_MBEDTLS_ERROR;
err = CA_ERR_MBEDTLS_ERROR;
goto err_free_dec;
}
if (pbin_olen != 32) {
LOG_PRINTF("Error: mbedtls_ecp_point_write_binary returned invalid output len: %d != 32\n", pbin_olen);
return CA_ERR_CORRUPTED_STATE;
err = CA_ERR_CORRUPTED_STATE;
goto err_free_dec;
}
/*
@ -370,18 +385,31 @@ enum ca_error parse_stanza_x25519(struct ca_keystore *ks, size_t nargs, const ch
mbedtls_rc = mbedtls_chachapoly_setkey(&cp_ctx, wrap_key);
if (mbedtls_rc) {
LOG_PRINTF("Error: mbedtls_chachapoly_setkey: rc=-0x%x\n", -mbedtls_rc);
return CA_ERR_MBEDTLS_ERROR;
err = CA_ERR_MBEDTLS_ERROR;
goto err_free_cp;
}
const unsigned char nonce[12] = { 0 };
mbedtls_rc = mbedtls_chachapoly_auth_decrypt(&cp_ctx, 16, nonce, NULL, 0, (const unsigned char*)(body + body_len - 16), body, file_key);
if (mbedtls_rc) {
LOG_PRINTF("Error: mbedtls_chachapoly_auth_decrypt: rc=-0x%x\n", -mbedtls_rc);
return CA_ERR_MBEDTLS_ERROR;
err = CA_ERR_MBEDTLS_ERROR;
goto err_free_cp;
}
err = CA_ERR_SUCCESS;
return CA_ERR_SUCCESS;
err_free_cp:
mbedtls_chachapoly_free(&cp_ctx);
err_free_dec:
mbedtls_ecp_point_free(&ecp_dec_res_pt);
err_free_grp:
mbedtls_ecp_group_free(&x25519_grp);
mbedtls_ecp_point_free(&ecp_ciphertext_pt);
return err;
}
enum ca_error check_file_key(const unsigned char *buf, size_t buflen, const unsigned char file_key[16]) {
@ -441,6 +469,7 @@ enum ca_error check_file_key(const unsigned char *buf, size_t buflen, const unsi
}
enum ca_error stream_decrypt(unsigned char *out, size_t outlen, size_t *out_written, const unsigned char *in, size_t inlen, const unsigned char file_key[16]) {
enum ca_error err = CA_ERR_CORRUPTED_STATE;
const char *found = strstr((const char *)in, "\n--- ");
if (!found) {
@ -517,7 +546,8 @@ enum ca_error stream_decrypt(unsigned char *out, size_t outlen, size_t *out_writ
mbedtls_rc = mbedtls_chachapoly_setkey(&cp_ctx, stream_key);
if (mbedtls_rc) {
LOG_PRINTF("Error: mbedtls_chachapoly_setkey: rc=-0x%x\n", -mbedtls_rc);
return CA_ERR_MBEDTLS_ERROR;
err = CA_ERR_MBEDTLS_ERROR;
goto err_free_cp;
}
in += 16;
@ -552,14 +582,20 @@ enum ca_error stream_decrypt(unsigned char *out, size_t outlen, size_t *out_writ
data_len, (unsigned char *)&nonce, NULL, 0, tag, inp, outp);
if (mbedtls_rc) {
LOG_PRINTF("Error: mbedtls_chachapoly_auth_decrypt: i=%zx rc=-0x%x\n", i, -mbedtls_rc);
return CA_ERR_MBEDTLS_ERROR;
err = CA_ERR_MBEDTLS_ERROR;
goto err_free_cp;
}
*out_written += data_len;
block_num += 1;
}
return CA_ERR_SUCCESS;
err = CA_ERR_SUCCESS;
err_free_cp:
mbedtls_chachapoly_free(&cp_ctx);
return err;
}
#ifdef CAGE_DEBUG

1
demo/fw/src/cage.h
View file

@ -33,6 +33,7 @@ struct ca_keystore {
enum ca_error parse_age_buf(struct ca_keystore *ks, const char *buf, size_t buflen, unsigned char file_key[16]);
void ca_keystore_init(struct ca_keystore *ks);
void ca_keystore_free(struct ca_keystore *ks);
enum ca_error ca_keystore_load_x25519_private_key(struct ca_keystore *ks, const unsigned char buf[32]);
enum ca_error stream_decrypt(unsigned char *out, size_t outlen, size_t *out_written, const unsigned char *in, size_t inlen, const unsigned char file_key[16]);

71
demo/fw/src/main.c
View file

@ -338,11 +338,12 @@ int main(void)
spif_printf(&spif, "loop #%u \033[4%dmloop #%u \033[10%dmloop #%u\033[0m\n", i, k%8, (k+1)%8);
*/
i++;
k = (k + 1) % 40;
if (k == 0) {
spif_capture_read(&spif, sizeof(payload_buf), payload_buf);
k = (k + 1) % 5;
con_printf_blocking("\r\n");
spif_capture_read(&spif, sizeof(payload_buf), payload_buf);
con_printf_blocking("\r\n");
if (k == 0) {
con_printf_blocking("\r\n");
con_printf_blocking("buffer capture:\r\n");
for (size_t e=0; e<256; e += 27) {
@ -367,40 +368,46 @@ int main(void)
}
}
con_printf_blocking("\033[0m\r\n");
}
unpack_px_data(payload_buf, sizeof(payload_buf));
size_t payload_len = be32toh(((uint32_t *)payload_buf)[0]);
if (payload_len < 0 || payload_len > sizeof(payload_buf) - sizeof(uint32_t)) {
con_printf_blocking("Invalid payload size %zx\r\n", payload_len);
continue;
}
unsigned char file_key[16];
err = parse_age_buf(&ks, payload_buf + sizeof(uint32_t), payload_len+1, file_key);
if (err) {
con_printf_blocking("Error parsing payload age header: %d\r\n", err);
continue;
}
size_t decrypted_size = 0;
err = stream_decrypt(dec_buf, sizeof(dec_buf), &decrypted_size, payload_buf + sizeof(uint32_t), payload_len, file_key);
if (err) {
con_printf_blocking("Error decrypting payload: %d\r\n", err);
continue;
}
assert (decrypted_size > 0 && decrypted_size < sizeof(dec_buf));
dec_buf[decrypted_size-1] = '\0'; /* overwrite trailing \n */
con_printf_blocking("decrypted payload: %s\r\n", dec_buf);
unpack_px_data(payload_buf, sizeof(payload_buf));
size_t payload_len = be32toh(((uint32_t *)payload_buf)[0]);
if (payload_len < 0 || payload_len > sizeof(payload_buf) - sizeof(uint32_t)) {
con_printf_blocking("Invalid payload size %zx\r\n", payload_len);
spif_printf(&spif, "\033[H\033[0m\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\033[H");
spif_printf(&spif, "\033[1;91mDecrypted data:\033[0m\n\n%s\n", dec_buf);
spif_printf(&spif, "\033[1;91mDecryption error!\033[0m\n");
continue;
}
for (int j=0; j<1000000; j++) {
/* pass */
unsigned char file_key[16];
err = parse_age_buf(&ks, payload_buf + sizeof(uint32_t), payload_len+1, file_key);
if (err) {
con_printf_blocking("Error parsing payload age header: %d\r\n", err);
spif_printf(&spif, "\033[H\033[0m\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\033[H");
spif_printf(&spif, "\033[1;91mDecryption error!\033[0m\n");
continue;
}
size_t decrypted_size = 0;
err = stream_decrypt(dec_buf, sizeof(dec_buf), &decrypted_size, payload_buf + sizeof(uint32_t), payload_len, file_key);
if (err) {
con_printf_blocking("Error decrypting payload: %d\r\n", err);
spif_printf(&spif, "\033[H\033[0m\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\033[H");
spif_printf(&spif, "\033[1;91mDecryption error!\033[0m\n");
continue;
}
assert (decrypted_size > 0 && decrypted_size < sizeof(dec_buf));
dec_buf[decrypted_size-1] = '\0'; /* overwrite trailing \n */
con_printf_blocking("decrypted payload: %s\r\n", dec_buf);
spif_printf(&spif, "\033[H\033[0m\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\033[H");
spif_printf(&spif, "\033[1;92mDecrypted data:\033[0m\n\n%s\n", dec_buf);
//for (int j=0; j<1000000; j++) {
/* pass */
//}
}
return 0;