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SAE: Validate peer commit values as part of parsing the message

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There is no need to postpone this validation step to a separate
processing operation for the commit message, so move the minimal
validation tasks into the parsing functions.

Signed-hostap: Jouni Malinen <j@w1.fi>
This commit is contained in:
Jouni Malinen 2013-01-06 17:34:05 +02:00
parent 24dc1e2a2c
commit 61bd6a307c
1 changed files with 61 additions and 53 deletions
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94
src/common/sae.c
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@ -567,44 +567,6 @@ int sae_prepare_commit(const u8 *addr1, const u8 *addr2,
}
static int sae_check_peer_commit(struct sae_data *sae)
{
u8 prime[SAE_MAX_PRIME_LEN];
if (crypto_bignum_to_bin(sae->prime, prime, sizeof(prime),
sae->prime_len) < 0)
return -1;
/* 0 < scalar < r */
if (crypto_bignum_is_zero(sae->peer_commit_scalar) ||
crypto_bignum_cmp(sae->peer_commit_scalar, sae->order) >= 0) {
wpa_printf(MSG_DEBUG, "SAE: Invalid peer scalar");
return -1;
}
if (sae->dh) {
if (os_memcmp(sae->peer_commit_element, prime, sae->prime_len)
>= 0 ||
val_zero_or_one(sae->peer_commit_element, sae->prime_len)) {
wpa_printf(MSG_DEBUG, "SAE: Invalid peer element");
return -1;
}
return 0;
}
/* element x and y coordinates < p */
if (os_memcmp(sae->peer_commit_element, prime, sae->prime_len) >= 0 ||
os_memcmp(sae->peer_commit_element + sae->prime_len, prime,
sae->prime_len) >= 0) {
wpa_printf(MSG_DEBUG, "SAE: Invalid coordinates in peer "
"element");
return -1;
}
return 0;
}
static int sae_derive_k_ec(struct sae_data *sae, u8 *k)
{
struct crypto_ec_point *peer_elem, *K;
@ -736,9 +698,7 @@ fail:
int sae_process_commit(struct sae_data *sae)
{
u8 k[SAE_MAX_PRIME_LEN];
if (sae_check_peer_commit(sae) < 0 ||
sae_derive_k(sae, k) < 0 ||
sae_derive_keys(sae, k) < 0)
if (sae_derive_k(sae, k) < 0 || sae_derive_keys(sae, k) < 0)
return -1;
return 0;
}
@ -845,6 +805,15 @@ static u16 sae_parse_commit_scalar(struct sae_data *sae, const u8 **pos,
return WLAN_STATUS_UNSPECIFIED_FAILURE;
}
/* 0 < scalar < r */
if (crypto_bignum_is_zero(peer_scalar) ||
crypto_bignum_cmp(peer_scalar, sae->order) >= 0) {
wpa_printf(MSG_DEBUG, "SAE: Invalid peer scalar");
crypto_bignum_deinit(peer_scalar, 0);
return WLAN_STATUS_UNSPECIFIED_FAILURE;
}
crypto_bignum_deinit(sae->peer_commit_scalar, 0);
sae->peer_commit_scalar = peer_scalar;
wpa_hexdump(MSG_DEBUG, "SAE: Peer commit-scalar", *pos, sae->prime_len);
@ -854,10 +823,11 @@ static u16 sae_parse_commit_scalar(struct sae_data *sae, const u8 **pos,
}
static u16 sae_parse_commit_element(struct sae_data *sae, const u8 *pos,
static u16 sae_parse_commit_element_ffc(struct sae_data *sae, const u8 *pos,
const u8 *end)
{
if (sae->dh) {
u8 prime[SAE_MAX_PRIME_LEN];
if (pos + sae->prime_len > end) {
wpa_printf(MSG_DEBUG, "SAE: Not enough data for "
"commit-element");
@ -867,9 +837,25 @@ static u16 sae_parse_commit_element(struct sae_data *sae, const u8 *pos,
wpa_hexdump(MSG_DEBUG, "SAE: Peer commit-element",
sae->peer_commit_element, sae->prime_len);
if (crypto_bignum_to_bin(sae->prime, prime, sizeof(prime),
sae->prime_len) < 0)
return WLAN_STATUS_UNSPECIFIED_FAILURE;
if (os_memcmp(sae->peer_commit_element, prime, sae->prime_len) >= 0 ||
val_zero_or_one(sae->peer_commit_element, sae->prime_len)) {
wpa_printf(MSG_DEBUG, "SAE: Invalid peer element");
return WLAN_STATUS_UNSPECIFIED_FAILURE;
}
return WLAN_STATUS_SUCCESS;
}
static u16 sae_parse_commit_element_ecc(struct sae_data *sae, const u8 *pos,
const u8 *end)
{
u8 prime[SAE_MAX_PRIME_LEN];
if (pos + 2 * sae->prime_len > end) {
wpa_printf(MSG_DEBUG, "SAE: Not enough data for "
"commit-element");
@ -881,10 +867,32 @@ static u16 sae_parse_commit_element(struct sae_data *sae, const u8 *pos,
wpa_hexdump(MSG_DEBUG, "SAE: Peer commit-element(y)",
sae->peer_commit_element + sae->prime_len, sae->prime_len);
if (crypto_bignum_to_bin(sae->prime, prime, sizeof(prime),
sae->prime_len) < 0)
return -1;
/* element x and y coordinates < p */
if (os_memcmp(sae->peer_commit_element, prime, sae->prime_len) >= 0 ||
os_memcmp(sae->peer_commit_element + sae->prime_len, prime,
sae->prime_len) >= 0) {
wpa_printf(MSG_DEBUG, "SAE: Invalid coordinates in peer "
"element");
return WLAN_STATUS_UNSPECIFIED_FAILURE;
}
return WLAN_STATUS_SUCCESS;
}
static u16 sae_parse_commit_element(struct sae_data *sae, const u8 *pos,
const u8 *end)
{
if (sae->dh)
return sae_parse_commit_element_ffc(sae, pos, end);
return sae_parse_commit_element_ecc(sae, pos, end);
}
u16 sae_parse_commit(struct sae_data *sae, const u8 *data, size_t len,
const u8 **token, size_t *token_len, int *allowed_groups)
{