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DPP: PKEX counter t

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Add limit on number of failed attempts that could have used PKEX code.
If the limit (5) is reached, drop the PKEX state (including the code)
and report this on the control interface to indicate that a new code
needs to be entered due to possible attack.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
This commit is contained in:
Jouni Malinen 2017-11-03 17:49:45 +02:00 • committed by Jouni Malinen
parent 84d53c775c
commit 29ab69e4b0
5 changed files with 59 additions and 3 deletions
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21
src/common/dpp.c
View file

@ -5769,6 +5769,12 @@ struct dpp_pkex * dpp_pkex_rx_exchange_req(void *msg_ctx,
const EC_POINT *Y_point;
BIGNUM *Nx = NULL, *Ny = NULL;
if (bi->pkex_t >= PKEX_COUNTER_T_LIMIT) {
wpa_msg(msg_ctx, MSG_INFO, DPP_EVENT_FAIL
"PKEX counter t limit reached - ignore message");
return NULL;
}
attr_id = dpp_get_attr(buf, len, DPP_ATTR_CODE_IDENTIFIER,
&attr_id_len);
if (!attr_id && identifier) {
@ -5841,12 +5847,14 @@ struct dpp_pkex * dpp_pkex_rx_exchange_req(void *msg_ctx,
!EC_POINT_is_on_curve(group, X, bnctx)) {
wpa_msg(msg_ctx, MSG_INFO, DPP_EVENT_FAIL
"Invalid Encrypted Key value");
bi->pkex_t++;
goto fail;
}
pkex = os_zalloc(sizeof(*pkex));
if (!pkex)
goto fail;
pkex->t = bi->pkex_t;
pkex->msg_ctx = msg_ctx;
pkex->own_bi = bi;
os_memcpy(pkex->own_mac, own_mac, ETH_ALEN);
@ -6103,7 +6111,7 @@ struct wpabuf * dpp_pkex_rx_exchange_resp(struct dpp_pkex *pkex,
u8 u[DPP_MAX_HASH_LEN];
int res;
if (pkex->failed)
if (pkex->failed || pkex->t >= PKEX_COUNTER_T_LIMIT)
return NULL;
attr_status = dpp_get_attr(buf, buflen, DPP_ATTR_STATUS,
@ -6176,6 +6184,7 @@ struct wpabuf * dpp_pkex_rx_exchange_resp(struct dpp_pkex *pkex,
EC_POINT_is_at_infinity(group, Y) ||
!EC_POINT_is_on_curve(group, Y, bnctx)) {
dpp_pkex_fail(pkex, "Invalid Encrypted Key value");
pkex->t++;
goto fail;
}
@ -6396,7 +6405,8 @@ struct wpabuf * dpp_pkex_rx_commit_reveal_req(struct dpp_pkex *pkex,
u8 u[DPP_MAX_HASH_LEN], v[DPP_MAX_HASH_LEN];
int res;
if (!pkex->exchange_done || pkex->failed)
if (!pkex->exchange_done || pkex->failed ||
pkex->t >= PKEX_COUNTER_T_LIMIT)
goto fail;
/* K = y * X' */
@ -6455,6 +6465,7 @@ struct wpabuf * dpp_pkex_rx_commit_reveal_req(struct dpp_pkex *pkex,
dpp_pkex_fail(pkex,
"AES-SIV decryption failed - possible PKEX code mismatch");
pkex->failed = 1;
pkex->t++;
goto fail;
}
wpa_hexdump(MSG_DEBUG, "DPP: AES-SIV cleartext",
@ -6523,6 +6534,7 @@ struct wpabuf * dpp_pkex_rx_commit_reveal_req(struct dpp_pkex *pkex,
wpa_hexdump(MSG_DEBUG, "DPP: Calculated u'",
u, curve->hash_len);
wpa_hexdump(MSG_DEBUG, "DPP: Received u", peer_u, peer_u_len);
pkex->t++;
goto fail;
}
wpa_printf(MSG_DEBUG, "DPP: Valid u (I-Auth tag) received");
@ -6598,7 +6610,8 @@ int dpp_pkex_rx_commit_reveal_resp(struct dpp_pkex *pkex, const u8 *hdr,
EVP_PKEY_CTX *ctx = NULL;
struct wpabuf *B_pub = NULL, *X_pub = NULL, *Y_pub = NULL;
if (!pkex->exchange_done || pkex->failed)
if (!pkex->exchange_done || pkex->failed ||
pkex->t >= PKEX_COUNTER_T_LIMIT)
goto fail;
wrapped_data = dpp_get_attr(buf, buflen, DPP_ATTR_WRAPPED_DATA,
@ -6629,6 +6642,7 @@ int dpp_pkex_rx_commit_reveal_resp(struct dpp_pkex *pkex, const u8 *hdr,
2, addr, len, unwrapped) < 0) {
dpp_pkex_fail(pkex,
"AES-SIV decryption failed - possible PKEX code mismatch");
pkex->t++;
goto fail;
}
wpa_hexdump(MSG_DEBUG, "DPP: AES-SIV cleartext",
@ -6696,6 +6710,7 @@ int dpp_pkex_rx_commit_reveal_resp(struct dpp_pkex *pkex, const u8 *hdr,
wpa_hexdump(MSG_DEBUG, "DPP: Calculated v'",
v, curve->hash_len);
wpa_hexdump(MSG_DEBUG, "DPP: Received v", peer_v, peer_v_len);
pkex->t++;
goto fail;
}
wpa_printf(MSG_DEBUG, "DPP: Valid v (R-Auth tag) received");