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fils: update to handle FILS-FT

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FILS unfortunately is a special case when it comes to fast transition.
We have to process the FT IEs internally since we cannot trigger the
same initial mobility association code path (via netdev).
This commit is contained in:
James Prestwood 2019-05-22 15:24:03 -07:00 committed by Denis Kenzior
parent 5ca4fa9b9e
commit e583b1d243
1 changed files with 123 additions and 13 deletions
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136
src/fils.c
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@ -59,6 +59,9 @@ struct fils_sm {
uint8_t pmk[48];
size_t pmk_len;
uint8_t pmkid[16];
uint8_t fils_ft[48];
size_t fils_ft_len;
};
static void fils_derive_pmkid(struct fils_sm *fils, const uint8_t *erp_data,
@ -67,8 +70,11 @@ static void fils_derive_pmkid(struct fils_sm *fils, const uint8_t *erp_data,
struct l_checksum *sha;
enum l_checksum_type type;
type = (fils->hs->akm_suite == IE_RSN_AKM_SUITE_FILS_SHA256) ?
L_CHECKSUM_SHA256 : L_CHECKSUM_SHA384;
if (fils->hs->akm_suite & (IE_RSN_AKM_SUITE_FILS_SHA256 |
IE_RSN_AKM_SUITE_FT_OVER_FILS_SHA256))
type = L_CHECKSUM_SHA256;
else
type = L_CHECKSUM_SHA384;
sha = l_checksum_new(type);
l_checksum_update(sha, erp_data, len);
@ -108,6 +114,12 @@ static void fils_erp_tx_func(const uint8_t *eap_data, size_t len,
ie_tlv_builder_next(&builder, IE_TYPE_FILS_WRAPPED_DATA);
ie_tlv_builder_set_data(&builder, eap_data, len);
if (fils->hs->mde) {
ie_tlv_builder_next(&builder, IE_TYPE_MOBILITY_DOMAIN);
ie_tlv_builder_set_data(&builder, fils->hs->mde + 2,
fils->hs->mde[1]);
}
ie_tlv_builder_finalize(&builder, &tlv_len);
fils->auth(data, ptr - data + tlv_len, fils->user_data);
@ -119,21 +131,29 @@ static int fils_derive_key_data(struct fils_sm *fils)
size_t rmsk_len;
struct ie_tlv_builder builder;
uint8_t key[FILS_NONCE_LEN * 2];
uint8_t key_data[64 + 48 + 16]; /* largest ICK, KEK, TK */
uint8_t key_data[64 + 48 + 16 + 48]; /* largest ICK, KEK, TK, FILS-FT */
uint8_t key_auth[48];
uint8_t data[44];
uint8_t *ptr = data;
size_t hash_len;
struct iovec iov[2];
struct iovec iov[4];
size_t iov_elems = 0;
size_t fils_ft_len = 0;
bool sha384;
unsigned int ie_len;
uint8_t *rsne = NULL;
rmsk = erp_get_rmsk(fils->erp, &rmsk_len);
if (fils->hs->akm_suite == IE_RSN_AKM_SUITE_FT_OVER_FILS_SHA256)
fils_ft_len = 32;
else if (fils->hs->akm_suite == IE_RSN_AKM_SUITE_FT_OVER_FILS_SHA384)
fils_ft_len = 48;
/*
* IEEE 802.11ai - Section 12.12.2.5.3
*/
if (fils->hs->akm_suite == IE_RSN_AKM_SUITE_FILS_SHA256) {
if (fils->hs->akm_suite & (IE_RSN_AKM_SUITE_FILS_SHA256 |
IE_RSN_AKM_SUITE_FT_OVER_FILS_SHA256)) {
sha384 = false;
hash_len = 32;
} else {
@ -176,12 +196,12 @@ static int fils_derive_key_data(struct fils_sm *fils)
kdf_sha384(fils->pmk, hash_len, "FILS PTK Derivation",
strlen("FILS PTK Derivation"), data,
sizeof(data), key_data,
hash_len + fils->kek_len + 16);
hash_len + fils->kek_len + 16 + fils_ft_len);
else
kdf_sha256(fils->pmk, hash_len, "FILS PTK Derivation",
strlen("FILS PTK Derivation"), data,
sizeof(data), key_data,
hash_len + fils->kek_len + 16);
hash_len + fils->kek_len + 16 + fils_ft_len);
ptr = data;
@ -203,6 +223,14 @@ static int fils_derive_key_data(struct fils_sm *fils)
memcpy(fils->ick, key_data, hash_len);
fils->ick_len = hash_len;
if (fils_ft_len) {
memcpy(fils->fils_ft, key_data + hash_len + fils->kek_len + 16,
fils_ft_len);
fils->fils_ft_len = fils_ft_len;
}
handshake_state_set_fils_ft(fils->hs, fils->fils_ft, fils->fils_ft_len);
if (sha384)
hmac_sha384(fils->ick, hash_len, data, ptr - data,
key_auth, hash_len);
@ -218,17 +246,56 @@ static int fils_derive_key_data(struct fils_sm *fils)
ie_tlv_builder_next(&builder, IE_TYPE_FILS_SESSION);
ie_tlv_builder_set_data(&builder, fils->session, sizeof(fils->session));
iov[0].iov_base = ie_tlv_builder_finalize(&builder, &ie_len);
iov[0].iov_len = ie_len;
iov[1].iov_base = fils->hs->supplicant_ie;
iov[1].iov_len = fils->hs->supplicant_ie[1] + 2;
iov[iov_elems].iov_base = ie_tlv_builder_finalize(&builder, &ie_len);
iov[iov_elems].iov_len = ie_len;
iov_elems++;
iov[iov_elems].iov_base = fils->hs->supplicant_ie;
iov[iov_elems].iov_len = fils->hs->supplicant_ie[1] + 2;
iov_elems++;
if (fils->hs->mde) {
struct ie_rsn_info rsn_info;
/*
* IEEE 8021.11ai Section 13.2.4:
*
* If a key hierarchy already exists for this STA belonging to
* the same mobility domain (i.e., having the same MDID), the
* R0KH shall delete the existing PMK-R0 security association
* and PMK-R1 security associations.
*
* All this means is we need to re-derive the new FT keys. This
* will rederive the PTK too, but it will be overwritten with
* the FILS PTK after associate
*/
handshake_state_derive_ptk(fils->hs);
iov[iov_elems].iov_base = fils->hs->mde;
iov[iov_elems].iov_len = fils->hs->mde[1] + 2;
iov_elems++;
if (ie_parse_rsne_from_data(fils->hs->supplicant_ie,
fils->hs->supplicant_ie[1] + 2,
&rsn_info) < 0)
return -EBADMSG;
rsn_info.num_pmkids = 1;
rsn_info.pmkids = fils->hs->pmk_r1_name;
rsne = alloca(256);
ie_build_rsne(&rsn_info, rsne);
iov[iov_elems].iov_base = rsne;
iov[iov_elems].iov_len = rsne[1] + 2;
iov_elems += 1;
}
memcpy(data, fils->nonce, sizeof(fils->nonce));
memcpy(data + sizeof(fils->nonce), fils->anonce, sizeof(fils->anonce));
memcpy(fils->kek_and_tk, key_data + hash_len, fils->kek_len + 16);
fils->assoc(iov, 2, fils->kek_and_tk, fils->kek_len, data,
fils->assoc(iov, iov_elems, fils->kek_and_tk, fils->kek_len, data,
FILS_NONCE_LEN * 2, fils->user_data);
return 0;
@ -266,6 +333,9 @@ static int fils_rx_authenticate(struct auth_proto *driver, const uint8_t *frame,
const uint8_t *session = NULL;
const uint8_t *wrapped = NULL;
size_t wrapped_len = 0;
const uint8_t *rsne = NULL;
const uint8_t *mde = NULL;
const uint8_t *fte = NULL;
if (!hdr) {
l_debug("Auth frame header did not validate");
@ -310,6 +380,27 @@ static int fils_rx_authenticate(struct auth_proto *driver, const uint8_t *frame,
wrapped = iter.data;
wrapped_len = iter.len;
break;
case IE_TYPE_RSN:
if (rsne)
goto invalid_ies;
rsne = ie_tlv_iter_get_data(&iter) - 2;
break;
case IE_TYPE_MOBILITY_DOMAIN:
if (mde)
goto invalid_ies;
mde = ie_tlv_iter_get_data(&iter) - 2;
break;
case IE_TYPE_FAST_BSS_TRANSITION:
if (fte)
goto invalid_ies;
fte = ie_tlv_iter_get_data(&iter) - 2;
break;
default:
continue;
}
@ -320,6 +411,24 @@ static int fils_rx_authenticate(struct auth_proto *driver, const uint8_t *frame,
goto invalid_ies;
}
if (mde)
handshake_state_set_mde(fils->hs, mde);
if (fte) {
struct handshake_state *hs = fils->hs;
uint32_t kck_len = handshake_state_get_kck_len(hs);
struct ie_ft_info ft_info;
if (ie_parse_fast_bss_transition_from_data(fte, fte[1] + 2,
kck_len, &ft_info) < 0)
goto invalid_ies;
handshake_state_set_fte(fils->hs, fte);
handshake_state_set_kh_ids(fils->hs, ft_info.r0khid,
ft_info.r0khid_len,
ft_info.r1khid);
}
memcpy(fils->anonce, anonce, FILS_NONCE_LEN);
if (erp_rx_packet(fils->erp, wrapped, wrapped_len) < 0)
@ -347,7 +456,8 @@ static int fils_rx_associate(struct auth_proto *driver, const uint8_t *frame,
uint8_t igtk_key_index;
const uint8_t *ap_key_auth = NULL;
uint8_t expected_key_auth[48];
bool sha384 = (fils->hs->akm_suite == IE_RSN_AKM_SUITE_FILS_SHA384);
bool sha384 = (fils->hs->akm_suite & (IE_RSN_AKM_SUITE_FILS_SHA384 |
IE_RSN_AKM_SUITE_FT_OVER_FILS_SHA384));
uint8_t data[44];
uint8_t *ptr = data;