From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: multipart/mixed; boundary="===============7502524282315242156==" MIME-Version: 1.0 From: Tim Kourt Subject: [PATCH v2 2/2] peap: Add support for Crypto-Binding in PEAPv0 Date: Thu, 12 Dec 2019 12:10:16 -0800 Message-ID: <20191212201016.18072-2-tim.a.kourt@linux.intel.com> In-Reply-To: <20191212201016.18072-1-tim.a.kourt@linux.intel.com> List-Id: To: iwd@lists.01.org --===============7502524282315242156== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable The Crypto Binding TLV is used to ensure that the EAP peer and the EAP server participated in both the inner and the outer EAP authentications of a PEAP authentication by cryptographically associating the phase 1 and phase 2 authentications. The usage of Crypto-Binding in PEAPv0 is optional and is triggered by the reception of the Crypto-Binding TLV from the server. --- src/eap-peap.c | 170 +++++++++++++++++++++++++++++++++++++++++++++++++++++= +++- 1 file changed, 169 insertions(+), 1 deletion(-) diff --git a/src/eap-peap.c b/src/eap-peap.c index 8059e60b..dd2438b8 100644 --- a/src/eap-peap.c +++ b/src/eap-peap.c @@ -29,6 +29,7 @@ #include #include = +#include "src/crypto.h" #include "src/missing.h" #include "src/eap.h" #include "src/eap-private.h" @@ -117,9 +118,170 @@ enum eap_extensions_tlv_type { /* Reserved =3D 0x0000, */ /* Reserved =3D 0x0001, */ /* Reserved =3D 0x0002, */ - EAP_EXTENSIONS_TLV_TYPE_RESULT =3D 0x8003, + EAP_EXTENSIONS_TLV_TYPE_RESULT =3D 0x8003, + EAP_EXTENSIONS_TLV_TYPE_CRYPTOBINDING =3D 0x000C, }; = +enum TLV_CRYPTOBINDING_TYPE { + TLV_CRYPTOBINDING_TYPE_REQUEST =3D 0, + TLV_CRYPTOBINDING_TYPE_RESPONSE =3D 1, +}; + +static bool cryptobinding_tlv_generate_csk(struct eap_state *eap, uint8_t = *imck) +{ + struct peap_state *peap_state =3D eap_tls_common_get_variant_data(eap); + static const char *label =3D "Session Key Generating Function"; + + if (!prf_plus_sha1(imck, 40, label, strlen(label), "\00", 1, + peap_state->key, sizeof(peap_state->key))) + return false; + + return true; +} + +static bool cryptobinding_tlv_generate_imck(struct eap_state *eap, + uint8_t *imck_out) +{ + struct peap_state *peap_state =3D eap_tls_common_get_variant_data(eap); + static const char *label =3D "Inner Methods Compound Keys"; + uint8_t isk[32]; + + memset(isk, 0, sizeof(isk)); + + if (!prf_plus_sha1(peap_state->key, 40, label, strlen(label), + isk, sizeof(isk), imck_out, 60)) + return false; + + return true; +} + +static int eap_extensions_handle_cryptobinding_tlv(struct eap_state *eap, + const uint8_t *data, + uint16_t tlv_value_len, + uint8_t *response) +{ + static const uint8_t cryptobinding_val_len =3D 56; + static const uint8_t cryptobinding_compound_mac_len =3D 20; + static const uint8_t cryptobinding_nonce_len =3D 32; + const uint8_t *nonce; + const uint8_t *server_compound_mac; + uint8_t client_compound_mac[cryptobinding_compound_mac_len]; + const uint8_t *cryptobinding_tlv_value; + uint8_t buf[61]; + uint8_t imck[60]; + + if (tlv_value_len !=3D cryptobinding_val_len) + return -ENOENT; + + cryptobinding_tlv_value =3D data; + + /* Reserved byte: must be ignored on receipt. */ + data +=3D 1; + + /* Version byte: must be set to 0. */ + if (*data) + return -ENOENT; + + data +=3D 1; + + /* RecvVersion byte: must be set to 0. */ + if (*data) + return -ENOENT; + + data +=3D 1; + + /* SubType byte: cryptobinding TLV request. */ + if (*data !=3D TLV_CRYPTOBINDING_TYPE_REQUEST) + return -ENOENT; + + data +=3D 1; + + nonce =3D data; + data +=3D cryptobinding_nonce_len; + + server_compound_mac =3D data; + + l_put_be16(EAP_EXTENSIONS_TLV_TYPE_CRYPTOBINDING, &buf[0]); + l_put_be16(tlv_value_len, &buf[2]); + memcpy(&buf[4], cryptobinding_tlv_value, + 4 + cryptobinding_nonce_len); + memset(&buf[EAP_EXTENSIONS_TLV_HEADER_LEN + 4 + + cryptobinding_nonce_len], + 0, cryptobinding_compound_mac_len); + buf[60] =3D EAP_TYPE_PEAP; + + if (!cryptobinding_tlv_generate_imck(eap, imck)) { + l_error("PEAP: Failed to generate IMCK to validate " + "server compound MAC."); + + return -ENOENT; + } + + if (!hmac_sha1(imck + 40, 20, buf, sizeof(buf), client_compound_mac, + cryptobinding_compound_mac_len)) { + l_error("PEAP: Failed to generate compound MAC to validate " + "server compound MAC."); + + return -ENOENT; + } + + if (memcmp(server_compound_mac, client_compound_mac, + cryptobinding_compound_mac_len)) { + l_error("PEAP: Generated compound MAC and server compound MAC " + "don't match."); + + return -ENOENT; + } + + /* Build response Crypto-Binding TLV */ + data =3D response; + + l_put_be16(EAP_EXTENSIONS_TLV_TYPE_CRYPTOBINDING, response); + response +=3D 2; + + l_put_be16(cryptobinding_val_len, response); + response +=3D 2; + + /* Reserved - must be set to 0. */ + l_put_u8(0, response); + response +=3D 1; + + /* Version */ + l_put_u8(EAP_TLS_VERSION_0, response); + response +=3D 1; + + /* Received Version */ + l_put_u8(EAP_TLS_VERSION_0, response); + response +=3D 1; + + /* Sub-Type */ + l_put_u8(TLV_CRYPTOBINDING_TYPE_RESPONSE, response); + response +=3D 1; + + memcpy(response, nonce, cryptobinding_nonce_len); + response +=3D cryptobinding_nonce_len; + + memcpy(buf, data, EAP_EXTENSIONS_TLV_HEADER_LEN + 4 + + cryptobinding_nonce_len); + + if (!hmac_sha1(imck + 40, 20, buf, sizeof(buf), client_compound_mac, + cryptobinding_compound_mac_len)) { + l_error("PEAP: Failed to generate client compound MAC."); + + return -ENOENT; + } + + memcpy(response, client_compound_mac, cryptobinding_compound_mac_len); + + if (!cryptobinding_tlv_generate_csk(eap, imck)) { + l_error("PEAP: Failed to generate Compound Session Key."); + + return -ENOENT; + } + + return EAP_EXTENSIONS_TLV_HEADER_LEN + cryptobinding_val_len; +} + enum eap_extensions_result { EAP_EXTENSIONS_RESULT_SUCCCESS =3D 1, EAP_EXTENSIONS_RESULT_FAILURE =3D 2, @@ -199,6 +361,12 @@ static int eap_extensions_process_tlvs(struct eap_stat= e *eap, result); = break; + case EAP_EXTENSIONS_TLV_TYPE_CRYPTOBINDING: + response_tlv_len =3D + eap_extensions_handle_cryptobinding_tlv(eap, + data, tlv_value_len, response); + + break; default: if (tlv_type & EAP_EXTENSIONS_TLV_M_BIT_MASK) return -ENOENT; -- = 2.13.6 --===============7502524282315242156==--