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SAE: Parse Rejected Groups element from H2E SAE commit

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Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
This commit is contained in:
Jouni Malinen 2019-09-07 18:38:29 +03:00 committed by Jouni Malinen
parent 86f6084862
commit ecd7114072
2 changed files with 67 additions and 12 deletions
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78
src/common/sae.c
View file

@ -107,6 +107,7 @@ void sae_clear_temp_data(struct sae_data *sae)
crypto_ec_point_deinit(tmp->own_commit_element_ecc, 0);
crypto_ec_point_deinit(tmp->peer_commit_element_ecc, 0);
wpabuf_free(tmp->anti_clogging_token);
wpabuf_free(tmp->peer_rejected_groups);
os_free(tmp->pw_id);
bin_clear_free(tmp, sizeof(*tmp));
sae->tmp = NULL;
@ -849,9 +850,19 @@ static int sae_is_password_id_elem(const u8 *pos, const u8 *end)
}
static int sae_is_rejected_groups_elem(const u8 *pos, const u8 *end)
{
return end - pos >= 3 &&
pos[0] == WLAN_EID_EXTENSION &&
pos[1] >= 2 &&
end - pos - 2 >= pos[1] &&
pos[2] == WLAN_EID_EXT_REJECTED_GROUPS;
}
static void sae_parse_commit_token(struct sae_data *sae, const u8 **pos,
const u8 *end, const u8 **token,
size_t *token_len)
size_t *token_len, int h2e)
{
size_t scalar_elem_len, tlen;
const u8 *elem;
@ -872,6 +883,8 @@ static void sae_parse_commit_token(struct sae_data *sae, const u8 **pos,
* fields, so use that length as a requirement for the received
* token and check for the presence of possible Password
* Identifier element based on the element header information.
* When parsing H2E case, also consider the Rejected Groupd element
* similarly.
*/
tlen = end - (*pos + scalar_elem_len);
@ -889,12 +902,27 @@ static void sae_parse_commit_token(struct sae_data *sae, const u8 **pos,
* this frame. */
return;
}
if (h2e && sae_is_rejected_groups_elem(elem, end)) {
/* Rejected Groups takes out all available extra octets, so
* there can be no Anti-Clogging token in this frame. */
return;
}
elem += SHA256_MAC_LEN;
if (sae_is_password_id_elem(elem, end)) {
/* Password Identifier element is included in the end, so
* remove its length from the Anti-Clogging token field. */
tlen -= 2 + elem[1];
elem += 2 + elem[1];
if (h2e && sae_is_rejected_groups_elem(elem, end)) {
/* Also remove Rejected Groups element from the
* Anti-Clogging token field length */
tlen -= 2 + elem[1];
}
} else if (h2e && sae_is_rejected_groups_elem(elem, end)) {
/* Rejected Groups element is included in the end, so
* remove its length from the Anti-Clogging token field. */
tlen -= 2 + elem[1];
}
wpa_hexdump(MSG_DEBUG, "SAE: Anti-Clogging Token", *pos, tlen);
@ -1061,11 +1089,11 @@ static u16 sae_parse_commit_element(struct sae_data *sae, const u8 **pos,
static int sae_parse_password_identifier(struct sae_data *sae,
const u8 *pos, const u8 *end)
const u8 **pos, const u8 *end)
{
wpa_hexdump(MSG_DEBUG, "SAE: Possible elements at the end of the frame",
pos, end - pos);
if (!sae_is_password_id_elem(pos, end)) {
*pos, end - *pos);
if (!sae_is_password_id_elem(*pos, end)) {
if (sae->tmp->pw_id) {
wpa_printf(MSG_DEBUG,
"SAE: No Password Identifier included, but expected one (%s)",
@ -1078,8 +1106,8 @@ static int sae_parse_password_identifier(struct sae_data *sae,
}
if (sae->tmp->pw_id &&
(pos[1] - 1 != (int) os_strlen(sae->tmp->pw_id) ||
os_memcmp(sae->tmp->pw_id, pos + 3, pos[1] - 1) != 0)) {
((*pos)[1] - 1 != (int) os_strlen(sae->tmp->pw_id) ||
os_memcmp(sae->tmp->pw_id, (*pos) + 3, (*pos)[1] - 1) != 0)) {
wpa_printf(MSG_DEBUG,
"SAE: The included Password Identifier does not match the expected one (%s)",
sae->tmp->pw_id);
@ -1087,13 +1115,32 @@ static int sae_parse_password_identifier(struct sae_data *sae,
}
os_free(sae->tmp->pw_id);
sae->tmp->pw_id = os_malloc(pos[1]);
sae->tmp->pw_id = os_malloc((*pos)[1]);
if (!sae->tmp->pw_id)
return WLAN_STATUS_UNSPECIFIED_FAILURE;
os_memcpy(sae->tmp->pw_id, pos + 3, pos[1] - 1);
sae->tmp->pw_id[pos[1] - 1] = '\0';
os_memcpy(sae->tmp->pw_id, (*pos) + 3, (*pos)[1] - 1);
sae->tmp->pw_id[(*pos)[1] - 1] = '\0';
wpa_hexdump_ascii(MSG_DEBUG, "SAE: Received Password Identifier",
sae->tmp->pw_id, pos[1] - 1);
sae->tmp->pw_id, (*pos)[1] - 1);
*pos = *pos + 2 + (*pos)[1];
return WLAN_STATUS_SUCCESS;
}
static int sae_parse_rejected_groups(struct sae_data *sae,
const u8 *pos, const u8 *end)
{
wpa_hexdump(MSG_DEBUG, "SAE: Possible elements at the end of the frame",
pos, end - pos);
if (!sae_is_rejected_groups_elem(pos, end))
return WLAN_STATUS_SUCCESS;
wpabuf_free(sae->tmp->peer_rejected_groups);
sae->tmp->peer_rejected_groups = wpabuf_alloc(pos[1] - 1);
if (!sae->tmp->peer_rejected_groups)
return WLAN_STATUS_UNSPECIFIED_FAILURE;
wpabuf_put_data(sae->tmp->peer_rejected_groups, pos + 3, pos[1] - 1);
wpa_hexdump_buf(MSG_DEBUG, "SAE: Received Rejected Groups list",
sae->tmp->peer_rejected_groups);
return WLAN_STATUS_SUCCESS;
}
@ -1114,7 +1161,7 @@ u16 sae_parse_commit(struct sae_data *sae, const u8 *data, size_t len,
pos += 2;
/* Optional Anti-Clogging Token */
sae_parse_commit_token(sae, &pos, end, token, token_len);
sae_parse_commit_token(sae, &pos, end, token, token_len, h2e);
/* commit-scalar */
res = sae_parse_commit_scalar(sae, &pos, end);
@ -1127,10 +1174,17 @@ u16 sae_parse_commit(struct sae_data *sae, const u8 *data, size_t len,
return res;
/* Optional Password Identifier element */
res = sae_parse_password_identifier(sae, pos, end);
res = sae_parse_password_identifier(sae, &pos, end);
if (res != WLAN_STATUS_SUCCESS)
return res;
/* Conditional Rejected Groups element */
if (h2e) {
res = sae_parse_rejected_groups(sae, pos, end);
if (res != WLAN_STATUS_SUCCESS)
return res;
}
/*
* Check whether peer-commit-scalar and PEER-COMMIT-ELEMENT are same as
* the values we sent which would be evidence of a reflection attack.

1
src/common/sae.h
View file

@ -43,6 +43,7 @@ struct sae_temporary_data {
char *pw_id;
int vlan_id;
u8 bssid[ETH_ALEN];
struct wpabuf *peer_rejected_groups;
};
enum sae_state {