[PATCH 02/13] pem: Factor out the PKCS#8 decoding code

--- ell/pem-private.h | 7 ++ ell/pem.c | 167 ++++++++++++++++++++++++---------------------- 2 files changed, 96 insertions(+), 78 deletions(-) diff --git a/ell/pem-private.h b/ell/pem-private.h index 1cf7ee5..6e9458d 100644 --- a/ell/pem-private.h +++ b/ell/pem-private.h @@ -30,3 +30,10 @@ const char *pem_next(const void *buf, size_t buf_len, char **type_label, size_t *base64_len, const char **endp, bool strict); + +struct l_key *pem_key_from_pkcs8_private_key_info(const uint8_t *der, + size_t der_len); + +struct l_key *pem_key_from_pkcs8_encrypted_private_key_info(const uint8_t *der, + size_t der_len, + const char *passphrase); diff --git a/ell/pem.c b/ell/pem.c index 70d1f62..42c7975 100644 --- a/ell/pem.c +++ b/ell/pem.c @@ -601,6 +601,79 @@ cleanup: return cipher; } +struct l_key *pem_key_from_pkcs8_private_key_info(const uint8_t *der, + size_t der_len) +{ + return l_key_new(L_KEY_RSA, der, der_len); +} + +struct l_key *pem_key_from_pkcs8_encrypted_private_key_info(const uint8_t *der, + size_t der_len, + const char *passphrase) +{ + const uint8_t *key_info, *alg_id, *data; + uint8_t tag; + size_t key_info_len, alg_id_len, data_len, tmp_len; + struct l_cipher *alg; + uint8_t *decrypted; + int i; + struct l_key *pkey; + bool r; + + /* Technically this is BER, not limited to DER */ + key_info = asn1_der_find_elem(der, der_len, 0, &tag, &key_info_len); + if (!key_info || tag != ASN1_ID_SEQUENCE) + return NULL; + + alg_id = asn1_der_find_elem(key_info, key_info_len, 0, &tag, + &alg_id_len); + if (!alg_id || tag != ASN1_ID_SEQUENCE) + return NULL; + + data = asn1_der_find_elem(key_info, key_info_len, 1, &tag, &data_len); + if (!data || tag != ASN1_ID_OCTET_STRING || data_len < 8 || + (data_len & 7) != 0) + return NULL; + + if (asn1_der_find_elem(der, der_len, 2, &tag, &tmp_len)) + return NULL; + + alg = pkcs5_cipher_from_alg_id(alg_id, alg_id_len, passphrase); + if (!alg) + return NULL; + + decrypted = l_malloc(data_len); + + r = l_cipher_decrypt(alg, data, decrypted, data_len); + l_cipher_free(alg); + + if (!r) { + l_free(decrypted); + return NULL; + } + + /* + * Strip padding as defined in RFC8018 (for PKCS#5 v1) or + * RFC1423 / RFC5652 (for v2). + */ + pkey = NULL; + if (decrypted[data_len - 1] >= data_len || + decrypted[data_len - 1] > 16) + goto cleanup; + + for (i = 1; i < decrypted[data_len - 1]; i++) + if (decrypted[data_len - 1 - i] != decrypted[data_len - 1]) + goto cleanup; + + pkey = pem_key_from_pkcs8_private_key_info(decrypted, + data_len - decrypted[data_len - 1]); + +cleanup: + explicit_bzero(decrypted, data_len); + l_free(decrypted); + return pkey; +} + static struct l_key *pem_load_private_key(uint8_t *content, size_t len, char *label, @@ -608,7 +681,7 @@ static struct l_key *pem_load_private_key(uint8_t *content, char *headers, bool *encrypted) { - struct l_key *pkey = NULL; + struct l_key *pkey; /* * RFC7468 Section 10-compatible unencrypted private key label @@ -621,6 +694,7 @@ static struct l_key *pem_load_private_key(uint8_t *content, if (headers) goto err; + pkey = pem_key_from_pkcs8_private_key_info(content, len); goto done; } @@ -632,13 +706,6 @@ static struct l_key *pem_load_private_key(uint8_t *content, * pkcs8-key-parser module. */ if (!strcmp(label, "ENCRYPTED PRIVATE KEY")) { - const uint8_t *key_info, *alg_id, *data; - uint8_t tag; - size_t key_info_len, alg_id_len, data_len, tmp_len; - struct l_cipher *alg; - uint8_t *decrypted; - int i; - if (encrypted) *encrypted = true; @@ -649,59 +716,9 @@ static struct l_key *pem_load_private_key(uint8_t *content, if (headers) goto err; - /* Technically this is BER, not limited to DER */ - key_info = asn1_der_find_elem(content, len, 0, &tag, - &key_info_len); - if (!key_info || tag != ASN1_ID_SEQUENCE) - goto err; - - alg_id = asn1_der_find_elem(key_info, key_info_len, 0, &tag, - &alg_id_len); - if (!alg_id || tag != ASN1_ID_SEQUENCE) - goto err; - - data = asn1_der_find_elem(key_info, key_info_len, 1, &tag, - &data_len); - if (!data || tag != ASN1_ID_OCTET_STRING || data_len < 8 || - (data_len & 7) != 0) - goto err; - - if (asn1_der_find_elem(content, len, 2, &tag, &tmp_len)) - goto err; - - alg = pkcs5_cipher_from_alg_id(alg_id, alg_id_len, passphrase); - if (!alg) - goto err; - - decrypted = l_malloc(data_len); - - if (!l_cipher_decrypt(alg, data, decrypted, data_len)) { - l_cipher_free(alg); - l_free(decrypted); - goto err; - } - - l_cipher_free(alg); - explicit_bzero(content, len); - l_free(content); - content = decrypted; - len = data_len; - - /* - * Strip padding as defined in RFC8018 (for PKCS#5 v1) or - * RFC1423 / RFC5652 (for v2). - */ - - if (content[data_len - 1] >= data_len || - content[data_len - 1] > 16) - goto err; - - for (i = 1; i < content[data_len - 1]; i++) - if (content[data_len - 1 - i] != content[data_len - 1]) - goto err; - - len = data_len - content[data_len - 1]; - + pkey = pem_key_from_pkcs8_encrypted_private_key_info(content, + len, + passphrase); goto done; } @@ -791,19 +808,19 @@ static struct l_key *pem_load_private_key(uint8_t *content, key_data = asn1_der_find_elem(content, len, 0, &tag, &key_data_len); if (!key_data || tag != ASN1_ID_SEQUENCE) - goto done; + goto err; data = asn1_der_find_elem(key_data, key_data_len, 0, &tag, &data_len); if (!data || tag != ASN1_ID_INTEGER || data_len != 1 || (data[0] != 0x00 && data[0] != 0x01)) - goto done; + goto err; for (i = 1; i < 9; i++) { data = asn1_der_find_elem(key_data, key_data_len, i, &tag, &data_len); if (!data || tag != ASN1_ID_INTEGER || data_len < 1) - goto done; + goto err; } private_key = l_malloc(10 + len); @@ -830,25 +847,19 @@ static struct l_key *pem_load_private_key(uint8_t *content, explicit_bzero(private_key, private_key_len); l_free(private_key); - explicit_bzero(content, len); - l_free(content); - content = one_asymmetric_key; - len = ptr - one_asymmetric_key; + pkey = pem_key_from_pkcs8_private_key_info(one_asymmetric_key, + ptr - one_asymmetric_key); + explicit_bzero(one_asymmetric_key, ptr - one_asymmetric_key); + l_free(one_asymmetric_key); goto done; } /* Label not known */ - goto err; - -done: - pkey = l_key_new(L_KEY_RSA, content, len); - err: - if (content) { - explicit_bzero(content, len); - l_free(content); - } - + pkey = NULL; +done: + explicit_bzero(content, len); + l_free(content); l_free(label); l_free(headers); return pkey; -- 2.27.0