DPP: DPPEnvelopedData generation for Configurator backup

This adds support for generating an encrypted backup of the local
Configurator information for the purpose of enrolling a new
Configurator. This includes all ASN.1 construction and data encryption,
but the configuration and connector template values in
dpp_build_conf_params() are not yet complete.

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
This commit is contained in:
Jouni Malinen 2019-12-12 02:28:39 +02:00 committed by Jouni Malinen
parent 7d9e320054
commit c025c2eb59

View file

@ -5170,11 +5170,488 @@ dpp_build_conf_obj(struct dpp_authentication *auth, enum dpp_netrole netrole,
}
#ifdef CONFIG_DPP2
static struct wpabuf * dpp_build_conf_params(void)
{
struct wpabuf *buf;
size_t len;
/* TODO: proper template values */
const char *conf_template = "{\"wi-fi_tech\":\"infra\",\"discovery\":{\"ssid\":\"test\"},\"cred\":{\"akm\":\"dpp\"}}";
const char *connector_template = NULL;
len = 100 + os_strlen(conf_template);
if (connector_template)
len += os_strlen(connector_template);
buf = wpabuf_alloc(len);
if (!buf)
return NULL;
/*
* DPPConfigurationParameters ::= SEQUENCE {
* configurationTemplate UTF8String,
* connectorTemplate UTF8String OPTIONAL}
*/
asn1_put_utf8string(buf, conf_template);
if (connector_template)
asn1_put_utf8string(buf, conf_template);
return asn1_encaps(buf, ASN1_CLASS_UNIVERSAL, ASN1_TAG_SEQUENCE);
}
static struct wpabuf * dpp_build_attribute(void)
{
struct wpabuf *conf_params, *attr;
/*
* aa-DPPConfigurationParameters ATTRIBUTE ::=
* { TYPE DPPConfigurationParameters IDENTIFIED BY id-DPPConfigParams }
*
* Attribute ::= SEQUENCE {
* type OBJECT IDENTIFIER,
* values SET SIZE(1..MAX) OF Type
*/
conf_params = dpp_build_conf_params();
conf_params = asn1_encaps(conf_params, ASN1_CLASS_UNIVERSAL,
ASN1_TAG_SET);
if (!conf_params)
return NULL;
attr = wpabuf_alloc(100 + wpabuf_len(conf_params));
if (!attr) {
wpabuf_clear_free(conf_params);
return NULL;
}
asn1_put_oid(attr, &asn1_dpp_config_params_oid);
wpabuf_put_buf(attr, conf_params);
wpabuf_clear_free(conf_params);
return asn1_encaps(attr, ASN1_CLASS_UNIVERSAL, ASN1_TAG_SEQUENCE);
}
static struct wpabuf * dpp_build_key_alg(const struct dpp_curve_params *curve)
{
const struct asn1_oid *oid;
struct wpabuf *params, *res;
switch (curve->ike_group) {
case 19:
oid = &asn1_prime256v1_oid;
break;
case 20:
oid = &asn1_secp384r1_oid;
break;
case 21:
oid = &asn1_secp521r1_oid;
break;
case 28:
oid = &asn1_brainpoolP256r1_oid;
break;
case 29:
oid = &asn1_brainpoolP384r1_oid;
break;
case 30:
oid = &asn1_brainpoolP512r1_oid;
break;
default:
return NULL;
}
params = wpabuf_alloc(20);
if (!params)
return NULL;
asn1_put_oid(params, oid); /* namedCurve */
res = asn1_build_alg_id(&asn1_ec_public_key_oid, params);
wpabuf_free(params);
return res;
}
static struct wpabuf * dpp_build_key_pkg(struct dpp_authentication *auth)
{
struct wpabuf *key = NULL, *attr, *alg, *priv_key = NULL;
EC_KEY *eckey;
unsigned char *der = NULL;
int der_len;
eckey = EVP_PKEY_get0_EC_KEY(auth->conf->csign);
if (!eckey)
return NULL;
EC_KEY_set_enc_flags(eckey, EC_PKEY_NO_PUBKEY);
der_len = i2d_ECPrivateKey(eckey, &der);
if (der_len > 0)
priv_key = wpabuf_alloc_copy(der, der_len);
OPENSSL_free(der);
alg = dpp_build_key_alg(auth->conf->curve);
/* Attributes ::= SET OF Attribute { { OneAsymmetricKeyAttributes } } */
attr = dpp_build_attribute();
attr = asn1_encaps(attr, ASN1_CLASS_UNIVERSAL, ASN1_TAG_SET);
if (!priv_key || !attr || !alg)
goto fail;
/*
* OneAsymmetricKey ::= SEQUENCE {
* version Version,
* privateKeyAlgorithm PrivateKeyAlgorithmIdentifier,
* privateKey PrivateKey,
* attributes [0] Attributes OPTIONAL,
* ...,
* [[2: publicKey [1] BIT STRING OPTIONAL ]],
* ...
* }
*/
key = wpabuf_alloc(100 + wpabuf_len(alg) + wpabuf_len(priv_key) +
wpabuf_len(attr));
if (!key)
goto fail;
asn1_put_integer(key, 1); /* version = v2(1) */
/* PrivateKeyAlgorithmIdentifier */
wpabuf_put_buf(key, alg);
/* PrivateKey ::= OCTET STRING */
asn1_put_octet_string(key, priv_key);
/* [0] Attributes OPTIONAL */
asn1_put_hdr(key, ASN1_CLASS_CONTEXT_SPECIFIC, 1, 0, wpabuf_len(attr));
wpabuf_put_buf(key, attr);
fail:
wpabuf_clear_free(attr);
wpabuf_clear_free(priv_key);
wpabuf_free(alg);
/*
* DPPAsymmetricKeyPackage ::= AsymmetricKeyPackage
*
* AsymmetricKeyPackage ::= SEQUENCE SIZE (1..MAX) OF OneAsymmetricKey
*
* OneAsymmetricKey ::= SEQUENCE
*/
return asn1_encaps(asn1_encaps(key,
ASN1_CLASS_UNIVERSAL, ASN1_TAG_SEQUENCE),
ASN1_CLASS_UNIVERSAL, ASN1_TAG_SEQUENCE);
return key;
}
static struct wpabuf * dpp_build_pbkdf2_alg_id(const struct wpabuf *salt,
size_t hash_len)
{
struct wpabuf *params = NULL, *buf = NULL, *prf = NULL;
const struct asn1_oid *oid;
/*
* PBKDF2-params ::= SEQUENCE {
* salt CHOICE {
* specified OCTET STRING,
* otherSource AlgorithmIdentifier}
* iterationCount INTEGER (1..MAX),
* keyLength INTEGER (1..MAX),
* prf AlgorithmIdentifier}
*
* salt is an 64 octet value, iterationCount is 1000, keyLength is based
* on Configurator signing key length, prf is
* id-hmacWithSHA{256,384,512} based on Configurator signing key.
*/
if (hash_len == 32)
oid = &asn1_pbkdf2_hmac_sha256_oid;
else if (hash_len == 48)
oid = &asn1_pbkdf2_hmac_sha384_oid;
else if (hash_len == 64)
oid = &asn1_pbkdf2_hmac_sha512_oid;
else
goto fail;
prf = asn1_build_alg_id(oid, NULL);
if (!prf)
goto fail;
params = wpabuf_alloc(100 + wpabuf_len(salt) + wpabuf_len(prf));
if (!params)
goto fail;
asn1_put_octet_string(params, salt); /* salt.specified */
asn1_put_integer(params, 1000); /* iterationCount */
asn1_put_integer(params, hash_len); /* keyLength */
wpabuf_put_buf(params, prf);
params = asn1_encaps(params, ASN1_CLASS_UNIVERSAL, ASN1_TAG_SEQUENCE);
if (!params)
goto fail;
buf = asn1_build_alg_id(&asn1_pbkdf2_oid, params);
fail:
wpabuf_free(params);
wpabuf_free(prf);
return buf;
}
static struct wpabuf *
dpp_build_pw_recipient_info(struct dpp_authentication *auth, size_t hash_len,
const struct wpabuf *cont_enc_key)
{
struct wpabuf *pwri = NULL, *enc_key = NULL, *key_der_alg = NULL,
*key_enc_alg = NULL, *salt;
u8 kek[DPP_MAX_HASH_LEN];
const u8 *key;
size_t key_len;
salt = wpabuf_alloc(64);
if (!salt || os_get_random(wpabuf_put(salt, 64), 64) < 0)
goto fail;
wpa_hexdump_buf(MSG_DEBUG, "DPP: PBKDF2 salt", salt);
/* TODO: For initial testing, use ke as the key. Replace this with a
* new key once that has been defined. */
key = auth->ke;
key_len = auth->curve->hash_len;
wpa_hexdump_key(MSG_DEBUG, "DPP: PBKDF2 key", key, key_len);
if (dpp_pbkdf2(hash_len, key, key_len, wpabuf_head(salt), 64, 1000,
kek, hash_len)) {
wpa_printf(MSG_DEBUG, "DPP: PBKDF2 failed");
goto fail;
}
wpa_hexdump_key(MSG_DEBUG, "DPP: key-encryption key from PBKDF2",
kek, hash_len);
enc_key = wpabuf_alloc(hash_len + AES_BLOCK_SIZE);
if (!enc_key ||
aes_siv_encrypt(kek, hash_len, wpabuf_head(cont_enc_key),
wpabuf_len(cont_enc_key), 0, NULL, NULL,
wpabuf_put(enc_key, hash_len + AES_BLOCK_SIZE)) < 0)
goto fail;
wpa_hexdump_buf(MSG_DEBUG, "DPP: encryptedKey", enc_key);
/*
* PasswordRecipientInfo ::= SEQUENCE {
* version CMSVersion,
* keyDerivationAlgorithm [0] KeyDerivationAlgorithmIdentifier OPTIONAL,
* keyEncryptionAlgorithm KeyEncryptionAlgorithmIdentifier,
* encryptedKey EncryptedKey}
*
* version is 0, keyDerivationAlgorithm is id-PKBDF2, and the
* parameters contains PBKDF2-params SEQUENCE.
*/
key_der_alg = dpp_build_pbkdf2_alg_id(salt, hash_len);
key_enc_alg = asn1_build_alg_id(&asn1_aes_siv_cmac_aead_256_oid, NULL);
if (!key_der_alg || !key_enc_alg)
goto fail;
pwri = wpabuf_alloc(100 + wpabuf_len(key_der_alg) +
wpabuf_len(key_enc_alg) + wpabuf_len(enc_key));
if (!pwri)
goto fail;
/* version = 0 */
asn1_put_integer(pwri, 0);
/* [0] KeyDerivationAlgorithmIdentifier */
asn1_put_hdr(pwri, ASN1_CLASS_CONTEXT_SPECIFIC, 1, 0,
wpabuf_len(key_der_alg));
wpabuf_put_buf(pwri, key_der_alg);
/* KeyEncryptionAlgorithmIdentifier */
wpabuf_put_buf(pwri, key_enc_alg);
/* EncryptedKey ::= OCTET STRING */
asn1_put_octet_string(pwri, enc_key);
fail:
wpabuf_clear_free(key_der_alg);
wpabuf_free(key_enc_alg);
wpabuf_free(enc_key);
wpabuf_free(salt);
forced_memzero(kek, sizeof(kek));
return asn1_encaps(pwri, ASN1_CLASS_UNIVERSAL, ASN1_TAG_SEQUENCE);
}
static struct wpabuf *
dpp_build_recipient_info(struct dpp_authentication *auth, size_t hash_len,
const struct wpabuf *cont_enc_key)
{
struct wpabuf *pwri;
/*
* RecipientInfo ::= CHOICE {
* ktri KeyTransRecipientInfo,
* kari [1] KeyAgreeRecipientInfo,
* kekri [2] KEKRecipientInfo,
* pwri [3] PasswordRecipientInfo,
* ori [4] OtherRecipientInfo}
*
* Shall always use the pwri CHOICE.
*/
pwri = dpp_build_pw_recipient_info(auth, hash_len, cont_enc_key);
return asn1_encaps(pwri, ASN1_CLASS_CONTEXT_SPECIFIC, 3);
}
static struct wpabuf *
dpp_build_enc_cont_info(struct dpp_authentication *auth, size_t hash_len,
const struct wpabuf *cont_enc_key)
{
struct wpabuf *key_pkg, *enc_cont_info = NULL, *enc_cont = NULL,
*enc_alg;
const struct asn1_oid *oid;
size_t enc_cont_len;
/*
* EncryptedContentInfo ::= SEQUENCE {
* contentType ContentType,
* contentEncryptionAlgorithm ContentEncryptionAlgorithmIdentifier,
* encryptedContent [0] IMPLICIT EncryptedContent OPTIONAL}
*/
if (hash_len == 32)
oid = &asn1_aes_siv_cmac_aead_256_oid;
else if (hash_len == 48)
oid = &asn1_aes_siv_cmac_aead_384_oid;
else if (hash_len == 64)
oid = &asn1_aes_siv_cmac_aead_512_oid;
else
return NULL;
key_pkg = dpp_build_key_pkg(auth);
enc_alg = asn1_build_alg_id(oid, NULL);
if (!key_pkg || !enc_alg)
goto fail;
wpa_hexdump_buf_key(MSG_MSGDUMP, "DPP: DPPAsymmetricKeyPackage",
key_pkg);
enc_cont_len = wpabuf_len(key_pkg) + AES_BLOCK_SIZE;
enc_cont = wpabuf_alloc(enc_cont_len);
if (!enc_cont ||
aes_siv_encrypt(wpabuf_head(cont_enc_key), wpabuf_len(cont_enc_key),
wpabuf_head(key_pkg), wpabuf_len(key_pkg),
0, NULL, NULL,
wpabuf_put(enc_cont, enc_cont_len)) < 0)
goto fail;
enc_cont_info = wpabuf_alloc(100 + wpabuf_len(enc_alg) +
wpabuf_len(enc_cont));
if (!enc_cont_info)
goto fail;
/* ContentType ::= OBJECT IDENTIFIER */
asn1_put_oid(enc_cont_info, &asn1_dpp_asymmetric_key_package_oid);
/* ContentEncryptionAlgorithmIdentifier ::= AlgorithmIdentifier */
wpabuf_put_buf(enc_cont_info, enc_alg);
/* encryptedContent [0] IMPLICIT EncryptedContent OPTIONAL
* EncryptedContent ::= OCTET STRING */
asn1_put_hdr(enc_cont_info, ASN1_CLASS_CONTEXT_SPECIFIC, 1, 0,
wpabuf_len(enc_cont));
wpabuf_put_buf(enc_cont_info, enc_cont);
fail:
wpabuf_clear_free(key_pkg);
wpabuf_free(enc_cont);
wpabuf_free(enc_alg);
return enc_cont_info;
}
static struct wpabuf * dpp_gen_random(size_t len)
{
struct wpabuf *key;
key = wpabuf_alloc(len);
if (!key || os_get_random(wpabuf_put(key, len), len) < 0) {
wpabuf_free(key);
key = NULL;
}
wpa_hexdump_buf_key(MSG_DEBUG, "DPP: content-encryption key", key);
return key;
}
static struct wpabuf * dpp_build_enveloped_data(struct dpp_authentication *auth)
{
struct wpabuf *env = NULL;
struct wpabuf *recipient_info = NULL, *enc_cont_info = NULL;
struct wpabuf *cont_enc_key = NULL;
size_t hash_len;
if (!auth->conf) {
wpa_printf(MSG_DEBUG,
"DPP: No Configurator instance selected for the session - cannot build DPPEnvelopedData");
return NULL;
}
wpa_printf(MSG_DEBUG, "DPP: Building DPPEnvelopedData");
hash_len = auth->conf->curve->hash_len;
cont_enc_key = dpp_gen_random(hash_len);
if (!cont_enc_key)
goto fail;
recipient_info = dpp_build_recipient_info(auth, hash_len, cont_enc_key);
enc_cont_info = dpp_build_enc_cont_info(auth, hash_len, cont_enc_key);
if (!recipient_info || !enc_cont_info)
goto fail;
env = wpabuf_alloc(wpabuf_len(recipient_info) +
wpabuf_len(enc_cont_info) +
100);
if (!env)
goto fail;
/*
* DPPEnvelopedData ::= EnvelopedData
*
* EnvelopedData ::= SEQUENCE {
* version CMSVersion,
* originatorInfo [0] IMPLICIT OriginatorInfo OPTIONAL,
* recipientInfos RecipientInfos,
* encryptedContentInfo EncryptedContentInfo,
* unprotectedAttrs [1] IMPLICIT UnprotectedAttributes OPTIONAL}
*
* For DPP, version is 3, both originatorInfo and
* unprotectedAttrs are omitted, and recipientInfos contains a single
* RecipientInfo.
*/
/* EnvelopedData.version = 3 */
asn1_put_integer(env, 3);
/* RecipientInfos ::= SET SIZE (1..MAX) OF RecipientInfo */
asn1_put_set(env, recipient_info);
/* EncryptedContentInfo ::= SEQUENCE */
asn1_put_sequence(env, enc_cont_info);
env = asn1_encaps(env, ASN1_CLASS_UNIVERSAL, ASN1_TAG_SEQUENCE);
wpa_hexdump_buf(MSG_MSGDUMP, "DPP: DPPEnvelopedData", env);
out:
wpabuf_clear_free(cont_enc_key);
wpabuf_clear_free(recipient_info);
wpabuf_free(enc_cont_info);
return env;
fail:
wpabuf_free(env);
env = NULL;
goto out;
}
#endif /* CONFIG_DPP2 */
static struct wpabuf *
dpp_build_conf_resp(struct dpp_authentication *auth, const u8 *e_nonce,
u16 e_nonce_len, enum dpp_netrole netrole)
{
struct wpabuf *conf, *conf2 = NULL;
struct wpabuf *conf = NULL, *conf2 = NULL, *env_data = NULL;
size_t clear_len, attr_len;
struct wpabuf *clear = NULL, *msg = NULL;
u8 *wrapped;
@ -5182,13 +5659,21 @@ dpp_build_conf_resp(struct dpp_authentication *auth, const u8 *e_nonce,
size_t len[1];
enum dpp_status_error status;
conf = dpp_build_conf_obj(auth, netrole, 0);
if (conf) {
wpa_hexdump_ascii(MSG_DEBUG, "DPP: configurationObject JSON",
wpabuf_head(conf), wpabuf_len(conf));
conf2 = dpp_build_conf_obj(auth, netrole, 1);
if (netrole == DPP_NETROLE_CONFIGURATOR) {
#ifdef CONFIG_DPP2
env_data = dpp_build_enveloped_data(auth);
#endif /* CONFIG_DPP2 */
} else {
conf = dpp_build_conf_obj(auth, netrole, 0);
if (conf) {
wpa_hexdump_ascii(MSG_DEBUG,
"DPP: configurationObject JSON",
wpabuf_head(conf), wpabuf_len(conf));
conf2 = dpp_build_conf_obj(auth, netrole, 1);
}
}
status = conf ? DPP_STATUS_OK : DPP_STATUS_CONFIGURE_FAILURE;
status = (conf || env_data) ? DPP_STATUS_OK :
DPP_STATUS_CONFIGURE_FAILURE;
auth->conf_resp_status = status;
/* { E-nonce, configurationObject[, sendConnStatus]}ke */
@ -5197,6 +5682,8 @@ dpp_build_conf_resp(struct dpp_authentication *auth, const u8 *e_nonce,
clear_len += 4 + wpabuf_len(conf);
if (conf2)
clear_len += 4 + wpabuf_len(conf2);
if (env_data)
clear_len += 4 + wpabuf_len(env_data);
if (auth->peer_version >= 2 && auth->send_conn_status &&
netrole == DPP_NETROLE_STA)
clear_len += 4;
@ -5255,6 +5742,11 @@ skip_e_nonce:
wpa_printf(MSG_DEBUG,
"DPP: Second Config Object available, but peer does not support more than one");
}
if (env_data) {
wpabuf_put_le16(clear, DPP_ATTR_ENVELOPED_DATA);
wpabuf_put_le16(clear, wpabuf_len(env_data));
wpabuf_put_buf(clear, env_data);
}
if (auth->peer_version >= 2 && auth->send_conn_status &&
netrole == DPP_NETROLE_STA) {
@ -5309,9 +5801,10 @@ skip_wrapped_data:
wpa_hexdump_buf(MSG_DEBUG,
"DPP: Configuration Response attributes", msg);
out:
wpabuf_free(conf);
wpabuf_free(conf2);
wpabuf_free(clear);
wpabuf_clear_free(conf);
wpabuf_clear_free(conf2);
wpabuf_clear_free(env_data);
wpabuf_clear_free(clear);
return msg;
fail: