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TLS: Validate RSA ClientKeyExchange length field

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Instead of using implicit length based on the received buffer, validate
RSA ClientKeyExchange based on the explicit length field.
This commit is contained in:
Jouni Malinen 2011-10-23 13:04:32 +03:00
parent 46eeedac61
commit 3803bd331d
1 changed files with 13 additions and 5 deletions
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18
src/tls/tlsv1_server_read.c
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@ -494,6 +494,14 @@ static int tls_process_client_key_exchange_rsa(
encr_len = WPA_GET_BE16(pos); encr_len = WPA_GET_BE16(pos);
pos += 2; pos += 2;
if (pos + encr_len > end) {
wpa_printf(MSG_DEBUG, "TLSv1: Invalid ClientKeyExchange "
"format: encr_len=%u left=%u",
encr_len, (unsigned int) (end - pos));
tlsv1_server_alert(conn, TLS_ALERT_LEVEL_FATAL,
TLS_ALERT_DECODE_ERROR);
return -1;
}
outbuflen = outlen = end - pos; outbuflen = outlen = end - pos;
out = os_malloc(outlen >= TLS_PRE_MASTER_SECRET_LEN ? out = os_malloc(outlen >= TLS_PRE_MASTER_SECRET_LEN ?
@ -523,21 +531,21 @@ static int tls_process_client_key_exchange_rsa(
*/ */
if (crypto_private_key_decrypt_pkcs1_v15(conn->cred->key, if (crypto_private_key_decrypt_pkcs1_v15(conn->cred->key,
pos, end - pos, pos, encr_len,
out, &outlen) < 0) { out, &outlen) < 0) {
wpa_printf(MSG_DEBUG, "TLSv1: Failed to decrypt " wpa_printf(MSG_DEBUG, "TLSv1: Failed to decrypt "
"PreMasterSecret (encr_len=%d outlen=%lu)", "PreMasterSecret (encr_len=%u outlen=%lu)",
(int) (end - pos), (unsigned long) outlen); encr_len, (unsigned long) outlen);
use_random = 1; use_random = 1;
} }
if (outlen != TLS_PRE_MASTER_SECRET_LEN) { if (!use_random && outlen != TLS_PRE_MASTER_SECRET_LEN) {
wpa_printf(MSG_DEBUG, "TLSv1: Unexpected PreMasterSecret " wpa_printf(MSG_DEBUG, "TLSv1: Unexpected PreMasterSecret "
"length %lu", (unsigned long) outlen); "length %lu", (unsigned long) outlen);
use_random = 1; use_random = 1;
} }
if (WPA_GET_BE16(out) != conn->client_version) { if (!use_random && WPA_GET_BE16(out) != conn->client_version) {
wpa_printf(MSG_DEBUG, "TLSv1: Client version in " wpa_printf(MSG_DEBUG, "TLSv1: Client version in "
"ClientKeyExchange does not match with version in " "ClientKeyExchange does not match with version in "
"ClientHello"); "ClientHello");