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peap: handle redundant usage of the L flag

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Some of the PEAP server implementations set the L flag along with
redundant TLS Message Length field for the un-fragmented packets.
This patch allows to identify and handle such occasions.
This commit is contained in:
Tim Kourt 2018-09-07 10:24:27 -07:00 committed by Denis Kenzior
parent 958bd12624
commit 2735e32b10
1 changed files with 45 additions and 8 deletions
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53
src/eap-peap.c
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@ -583,13 +583,13 @@ static void eap_peap_handle_payload(struct eap_state *eap,
peap->plain_buf = NULL;
}
static bool eap_peap_init_request_assembly(struct eap_state *eap,
static int eap_peap_init_request_assembly(struct eap_state *eap,
const uint8_t *pkt, size_t len,
uint8_t flags) {
struct eap_peap_state *peap = eap_get_data(eap);
if (peap->rx_pdu_buf || len < 4)
return false;
return -EINVAL;
/*
* Some of the PEAP server implementations brake the protocol and do not
@ -602,25 +602,49 @@ static bool eap_peap_init_request_assembly(struct eap_state *eap,
" of the fragmented transmission.");
peap->rx_pdu_buf_len = l_get_be32(pkt);
len -= 4;
if (!peap->rx_pdu_buf_len || peap->rx_pdu_buf_len > PEAP_PDU_MAX_LEN) {
l_warn("Fragmented pkt size is outside of alowed boundaries "
"[1, %u]", PEAP_PDU_MAX_LEN);
return false;
return -EINVAL;
}
if (peap->rx_pdu_buf_len == len) {
/*
* PEAPv1: draft-josefsson-pppext-eap-tls-eap-05, Section 3.2:
* "The L bit (length included) is set to indicate the presence
* of the four octet TLS Message Length field, and MUST be set
* for the first fragment of a fragmented TLS message or set of
* messages."
*
* TTLSv0: RFC 5281, Section 9.2.2:
* "Unfragmented messages MAY have the L bit set and include
* the length of the message (though this information is
* redundant)."
*
* Some of the PEAP server implementations set the L flag along
* with redundant TLS Message Length field for the un-fragmented
* packets.
*/
l_warn("PEAP: Server has set the redundant TLS Message Length "
"field for the un-fragmented packet.");
return -ENOMSG;
}
if (peap->rx_pdu_buf_len < len) {
l_warn("Fragmented pkt size is smaller than the received "
"packet");
return false;
return -EINVAL;
}
peap->rx_pdu_buf = l_malloc(peap->rx_pdu_buf_len);
peap->rx_pdu_buf_offset = 0;
return true;
return 0;
}
static void eap_peap_send_fragmented_request_ack(struct eap_state *eap)
@ -679,9 +703,10 @@ static int eap_peap_handle_fragmented_request(struct eap_state *eap,
size_t pdu_len;
if (flags_version & PEAP_FLAG_L) {
if (!eap_peap_init_request_assembly(eap, pkt, len,
flags_version))
return -EINVAL;
int r = eap_peap_init_request_assembly(eap, pkt, len,
flags_version);
if (r)
return r;
rx_header_offset = 4;
}
@ -747,6 +772,17 @@ static void eap_peap_handle_request(struct eap_state *eap,
if (r == -EAGAIN)
return;
if (r == -ENOMSG) {
/*
* Redundant usage of the L flag, no packet reassembly
* is required.
*/
pkt += 4;
len -= 4;
goto proceed;
}
if (r < 0)
goto error;
@ -759,6 +795,7 @@ static void eap_peap_handle_request(struct eap_state *eap,
len = peap->rx_pdu_buf_len;
}
proceed:
/*
* tx_pdu_buf is used for the retransmission and needs to be cleared on
* a new request