diff options
| -rw-r--r-- | crypto/apr_crypto_prng.c | 108 |
1 files changed, 49 insertions, 59 deletions
diff --git a/crypto/apr_crypto_prng.c b/crypto/apr_crypto_prng.c index b21909040..178f58164 100644 --- a/crypto/apr_crypto_prng.c +++ b/crypto/apr_crypto_prng.c @@ -119,53 +119,52 @@ void cprng_stream_ctx_free(cprng_stream_ctx_t *ctx) } static APR_INLINE +void cprng_stream_setkey(cprng_stream_ctx_t *ctx, + const unsigned char *key, + const unsigned char *iv) +{ +#if defined(NID_chacha20) + /* With CHACHA20, iv=NULL is the same as zeros but it's faster + * to (re-)init; use that for efficiency. + */ + EVP_EncryptInit_ex(ctx, NULL, NULL, key, NULL); +#else + /* With AES256-CTR, iv=NULL seems to peek up and random one (for + * the initial CTR), while we can live with zeros (fixed CTR); + * efficiency still. + */ + EVP_EncryptInit_ex(ctx, NULL, NULL, key, iv); +#endif +} + +static APR_INLINE apr_status_t cprng_stream_ctx_bytes(cprng_stream_ctx_t **pctx, - unsigned char *key, unsigned char *to, - apr_size_t n, const unsigned char *z) + unsigned char *key, int rekey, + unsigned char *to, apr_size_t n, + const unsigned char *z) { cprng_stream_ctx_t *ctx = *pctx; int len; - /* Can be called for rekeying (key != NULL), streaming more bytes - * with the current key (n != 0), or both successively in a one go. + /* We never encrypt twice with the same key, so no IV is needed (can + * be zeros). When EVP_EncryptInit() is called multiple times it clears + * its previous resources approprietly, and since we don't want the key + * and its keystream to reside in memory at the same time, we have to + * EVP_EncryptInit() twice: firstly to set the key and then finally to + * overwrite the key (with zeros) after the keystream is produced. + * As for EVP_EncryptFinish(), we don't need it either because padding + * is disabled (irrelevant for a stream cipher). */ - if (key) { - /* We never encrypt twice with the same key, so no IV is needed (can - * be zeros). When EVP_EncryptInit() is called multiple times it clears - * its previous resources approprietly, and since we don't want the key - * and its keystream to reside in memory at the same time, we have to - * EVP_EncryptInit() twice: firstly to set the key and then finally to - * overwrite the key (with zeros) after the keystream is produced. - * As for EVP_EncryptFinish(), we don't need it either because padding - * is disabled (irrelevant for a stream cipher). - */ -#if defined(NID_chacha20) - /* With CHACHA20, iv=NULL is the same as zeros but it's faster - * to (re-)init; use that for efficiency. - */ - EVP_EncryptInit_ex(ctx, NULL, NULL, key, NULL); -#else - /* With AES256-CTR, iv=NULL seems to peek up and random one (for - * the initial CTR), while we can live with zeros (fixed CTR); - * efficiency still. - */ - EVP_EncryptInit_ex(ctx, NULL, NULL, key, z); -#endif - EVP_CIPHER_CTX_set_padding(ctx, 0); - + cprng_stream_setkey(ctx, key, z); + EVP_CIPHER_CTX_set_padding(ctx, 0); + if (rekey) { memset(key, 0, CPRNG_KEY_SIZE); EVP_EncryptUpdate(ctx, key, &len, key, CPRNG_KEY_SIZE); } if (n) { EVP_EncryptUpdate(ctx, to, &len, z, n); - - /* Burn the key in openssl internals */ -#if defined(NID_chacha20) - EVP_EncryptInit_ex(ctx, NULL, NULL, z, NULL); -#else - EVP_EncryptInit_ex(ctx, NULL, NULL, z, z); -#endif } + cprng_stream_setkey(ctx, z, z); return APR_SUCCESS; } @@ -484,12 +483,13 @@ APR_DECLARE(apr_status_t) apr_crypto_prng_destroy(apr_crypto_prng_t *cprng) } static apr_status_t cprng_stream_bytes(apr_crypto_prng_t *cprng, - unsigned char *key, void *to, - size_t len) + void *to, size_t len, + int rekey) { apr_status_t rv; - rv = cprng_stream_ctx_bytes(&cprng->ctx, key, to, len, cprng->buf); + rv = cprng_stream_ctx_bytes(&cprng->ctx, cprng->key, rekey, + to, len, cprng->buf); if (rv != APR_SUCCESS && len) { apr_crypto_memzero(to, len); } @@ -538,7 +538,7 @@ APR_DECLARE(apr_status_t) apr_crypto_prng_reseed(apr_crypto_prng_t *cprng, * i.e. the next key is always extracted from the stream cipher state * and cleared upon use. */ - rv = cprng_stream_bytes(cprng, cprng->key, NULL, 0); + rv = cprng_stream_bytes(cprng, NULL, 0, 1); } cprng_unlock(cprng); @@ -559,7 +559,7 @@ static apr_status_t cprng_bytes(apr_crypto_prng_t *cprng, n = cprng->len; if (len >= n) { do { - rv = cprng_stream_bytes(cprng, cprng->key, ptr, n); + rv = cprng_stream_bytes(cprng, ptr, n, 1); if (rv != APR_SUCCESS) { return rv; } @@ -570,7 +570,7 @@ static apr_status_t cprng_bytes(apr_crypto_prng_t *cprng, break; } } - rv = cprng_stream_bytes(cprng, cprng->key, cprng->buf, n); + rv = cprng_stream_bytes(cprng, cprng->buf, n, 1); if (rv != APR_SUCCESS) { return rv; } @@ -617,11 +617,11 @@ APR_DECLARE(apr_status_t) apr_crypto_prng_bytes(apr_crypto_prng_t *cprng, } /* Reset the buffer and use the next stream bytes as the new key. */ -static apr_status_t cprng_newkey(apr_crypto_prng_t *cprng) +static apr_status_t cprng_newkey(apr_crypto_prng_t *cprng, int rekey) { cprng->pos = cprng->len; apr_crypto_memzero(cprng->buf, cprng->len); - return cprng_stream_bytes(cprng, NULL, cprng->key, CPRNG_KEY_SIZE); + return cprng_stream_bytes(cprng, cprng->key, CPRNG_KEY_SIZE, rekey); } APR_DECLARE(apr_status_t) apr_crypto_prng_rekey(apr_crypto_prng_t *cprng) @@ -639,10 +639,7 @@ APR_DECLARE(apr_status_t) apr_crypto_prng_rekey(apr_crypto_prng_t *cprng) cprng_lock(cprng); /* Renew and apply the new key. */ - rv = cprng_newkey(cprng); - if (rv == APR_SUCCESS) { - rv = cprng_stream_bytes(cprng, cprng->key, NULL, 0); - } + rv = cprng_newkey(cprng, 1); cprng_unlock(cprng); @@ -682,20 +679,13 @@ APR_DECLARE(apr_status_t) apr_crypto_prng_after_fork(apr_crypto_prng_t *cprng, /* Make sure the parent and child processes never share the same state, so * renew the key first (also clears the buffer) for both parent and child, * so that further fork()s (from parent or child) won't use the same state. + * For the parent process only, renew a second time to ensure that key + * material is different from the child. Finally parent and child keys will + * be different and unknown to each other processes. */ - rv = cprng_newkey(cprng); + rv = cprng_newkey(cprng, in_child); if (rv == APR_SUCCESS && !in_child) { - /* For the parent process only, renew a second time to ensure that key - * material is different from the child. - */ - rv = cprng_stream_bytes(cprng, NULL, cprng->key, CPRNG_KEY_SIZE); - } - if (rv == APR_SUCCESS) { - /* Finally apply the new key, parent and child ones will now be - * different and unknown to each other (including at the stream ctx - * level). - */ - rv = cprng_stream_bytes(cprng, cprng->key, NULL, 0); + rv = cprng_stream_bytes(cprng, cprng->key, CPRNG_KEY_SIZE, 1); } cprng_unlock(cprng); |