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DPP: PKEX and STATUS_BAD_GROUP

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Report mismatching finite cyclic group with PKEX Exchange Response using
STATUS_BAD_GROUP and provide more detailed error report over the control
interface on the peer device when this happens.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
This commit is contained in:
Jouni Malinen 2017-11-03 16:43:58 +02:00 committed by Jouni Malinen
parent 2265353a4f
commit e0247e7983
4 changed files with 73 additions and 16 deletions
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6
src/ap/dpp_hostapd.c
View file

@ -1066,6 +1066,12 @@ hostapd_dpp_rx_pkex_exchange_req(struct hostapd_data *hapd, const u8 *src,
DPP_PA_PKEX_EXCHANGE_RESP);
hostapd_drv_send_action(hapd, freq, 0, src,
wpabuf_head(msg), wpabuf_len(msg));
if (hapd->dpp_pkex->failed) {
wpa_printf(MSG_DEBUG,
"DPP: Terminate PKEX exchange due to an earlier error");
dpp_pkex_free(hapd->dpp_pkex);
hapd->dpp_pkex = NULL;
}
}

69
src/common/dpp.c
View file

@ -5711,10 +5711,10 @@ fail:
}
static struct wpabuf * dpp_pkex_build_exchange_resp(struct dpp_pkex *pkex,
const char *identifier,
const BIGNUM *Nx,
const BIGNUM *Ny)
static struct wpabuf *
dpp_pkex_build_exchange_resp(struct dpp_pkex *pkex,
enum dpp_status_error status,
const BIGNUM *Nx, const BIGNUM *Ny)
{
struct wpabuf *msg = NULL;
size_t attr_len;
@ -5723,8 +5723,8 @@ static struct wpabuf * dpp_pkex_build_exchange_resp(struct dpp_pkex *pkex,
/* Initiator -> Responder: DPP Status, [identifier,] N */
attr_len = 4 + 1;
if (identifier)
attr_len += 4 + os_strlen(identifier);
if (pkex->identifier)
attr_len += 4 + os_strlen(pkex->identifier);
attr_len += 4 + 2 * curve->prime_len;
msg = dpp_alloc_msg(DPP_PA_PKEX_EXCHANGE_RESP, attr_len);
if (!msg)
@ -5740,7 +5740,7 @@ static struct wpabuf * dpp_pkex_build_exchange_resp(struct dpp_pkex *pkex,
/* DPP Status */
wpabuf_put_le16(msg, DPP_ATTR_STATUS);
wpabuf_put_le16(msg, 1);
wpabuf_put_u8(msg, DPP_STATUS_OK);
wpabuf_put_u8(msg, status);
#ifdef CONFIG_TESTING_OPTIONS
skip_status:
@ -5753,6 +5753,9 @@ skip_status:
wpabuf_put_str(msg, pkex->identifier);
}
if (status != DPP_STATUS_OK)
goto skip_encrypted_key;
#ifdef CONFIG_TESTING_OPTIONS
if (dpp_test == DPP_TEST_NO_ENCRYPTED_KEY_PKEX_EXCHANGE_RESP) {
wpa_printf(MSG_INFO, "DPP: TESTING - no Encrypted Key");
@ -5795,9 +5798,14 @@ skip_status:
os_memset(wpabuf_put(msg, offset), 0, offset);
BN_bn2bin(Ny, wpabuf_put(msg, num_bytes));
#ifdef CONFIG_TESTING_OPTIONS
skip_encrypted_key:
#endif /* CONFIG_TESTING_OPTIONS */
if (status == DPP_STATUS_BAD_GROUP) {
/* Finite Cyclic Group attribute */
wpabuf_put_le16(msg, DPP_ATTR_FINITE_CYCLIC_GROUP);
wpabuf_put_le16(msg, 2);
wpabuf_put_le16(msg, curve->ike_group);
}
return msg;
fail:
wpabuf_free(msg);
@ -5852,9 +5860,16 @@ struct dpp_pkex * dpp_pkex_rx_exchange_req(void *msg_ctx,
wpa_msg(msg_ctx, MSG_INFO, DPP_EVENT_FAIL
"Mismatching PKEX curve: peer=%u own=%u",
ike_group, curve->ike_group);
/* TODO: error response with suggested curve:
* DPP Status, group */
return NULL;
pkex = os_zalloc(sizeof(*pkex));
if (!pkex)
goto fail;
pkex->own_bi = bi;
pkex->failed = 1;
pkex->exchange_resp = dpp_pkex_build_exchange_resp(
pkex, DPP_STATUS_BAD_GROUP, NULL, NULL);
if (!pkex->exchange_resp)
goto fail;
return pkex;
}
/* M in Encrypted Key attribute */
@ -5947,7 +5962,7 @@ struct dpp_pkex * dpp_pkex_rx_exchange_req(void *msg_ctx,
EC_POINT_get_affine_coordinates_GFp(group, N, Nx, Ny, bnctx) != 1)
goto fail;
pkex->exchange_resp = dpp_pkex_build_exchange_resp(pkex, identifier,
pkex->exchange_resp = dpp_pkex_build_exchange_resp(pkex, DPP_STATUS_OK,
Nx, Ny);
if (!pkex->exchange_resp)
goto fail;
@ -6136,8 +6151,8 @@ fail:
struct wpabuf * dpp_pkex_rx_exchange_resp(struct dpp_pkex *pkex,
const u8 *buf, size_t buflen)
{
const u8 *attr_status, *attr_id, *attr_key;
u16 attr_status_len, attr_id_len, attr_key_len;
const u8 *attr_status, *attr_id, *attr_key, *attr_group;
u16 attr_status_len, attr_id_len, attr_key_len, attr_group_len;
const EC_GROUP *group;
BN_CTX *bnctx = NULL;
struct wpabuf *msg = NULL, *A_pub = NULL, *X_pub = NULL, *Y_pub = NULL;
@ -6153,6 +6168,9 @@ struct wpabuf * dpp_pkex_rx_exchange_resp(struct dpp_pkex *pkex,
u8 u[DPP_MAX_HASH_LEN];
int res;
if (pkex->failed)
return NULL;
attr_status = dpp_get_attr(buf, buflen, DPP_ATTR_STATUS,
&attr_status_len);
if (!attr_status || attr_status_len != 1) {
@ -6160,6 +6178,19 @@ struct wpabuf * dpp_pkex_rx_exchange_resp(struct dpp_pkex *pkex,
return NULL;
}
wpa_printf(MSG_DEBUG, "DPP: Status %u", attr_status[0]);
if (attr_status[0] == DPP_STATUS_BAD_GROUP) {
attr_group = dpp_get_attr(buf, buflen,
DPP_ATTR_FINITE_CYCLIC_GROUP,
&attr_group_len);
if (attr_group && attr_group_len == 2) {
wpa_msg(pkex->msg_ctx, MSG_INFO, DPP_EVENT_FAIL
"Peer indicated mismatching PKEX group - proposed %u",
WPA_GET_LE16(attr_group));
return NULL;
}
}
if (attr_status[0] != DPP_STATUS_OK) {
dpp_pkex_fail(pkex, "PKEX failed (peer indicated failure)");
return NULL;
@ -6414,7 +6445,7 @@ struct wpabuf * dpp_pkex_rx_commit_reveal_req(struct dpp_pkex *pkex,
const u8 *buf, size_t buflen)
{
const struct dpp_curve_params *curve = pkex->own_bi->curve;
EVP_PKEY_CTX *ctx;
EVP_PKEY_CTX *ctx = NULL;
size_t Jx_len, Kx_len, Lx_len;
u8 Jx[DPP_MAX_SHARED_SECRET_LEN], Kx[DPP_MAX_SHARED_SECRET_LEN];
u8 Lx[DPP_MAX_SHARED_SECRET_LEN];
@ -6430,6 +6461,9 @@ 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)
goto fail;
/* K = y * X' */
ctx = EVP_PKEY_CTX_new(pkex->y, NULL);
if (!ctx ||
@ -6628,6 +6662,9 @@ 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)
goto fail;
wrapped_data = dpp_get_attr(buf, buflen, DPP_ATTR_WRAPPED_DATA,
&wrapped_data_len);
if (!wrapped_data || wrapped_data_len < AES_BLOCK_SIZE) {

1
src/common/dpp.h
View file

@ -113,6 +113,7 @@ struct dpp_pkex {
void *msg_ctx;
unsigned int initiator:1;
unsigned int exchange_done:1;
unsigned int failed:1;
struct dpp_bootstrap_info *own_bi;
u8 own_mac[ETH_ALEN];
u8 peer_mac[ETH_ALEN];

13
wpa_supplicant/dpp_supplicant.c
View file

@ -1427,6 +1427,19 @@ wpas_dpp_tx_pkex_status(struct wpa_supplicant *wpa_s,
wpa_msg(wpa_s, MSG_INFO, DPP_EVENT_TX_STATUS "dst=" MACSTR
" freq=%u result=%s", MAC2STR(dst), freq, res_txt);
/* TODO: Time out wait for response more quickly in error cases? */
if (!wpa_s->dpp_pkex) {
wpa_printf(MSG_DEBUG,
"DPP: Ignore TX status since there is no ongoing PKEX exchange");
return;
}
if (wpa_s->dpp_pkex->failed) {
wpa_printf(MSG_DEBUG,
"DPP: Terminate PKEX exchange due to an earlier error");
dpp_pkex_free(wpa_s->dpp_pkex);
wpa_s->dpp_pkex = NULL;
}
}