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TCP: reset addresses and ports after each segment 

TCP can contain multiple PDUs of the next layer protocol, and the
subdissector (or further subdissectors called from it) can change
the addresses and ports. However, the addresses and ports are used
for the desegmentation tables at the TCP level, as well as for
various purposes in encapsulated protocols.

Restore the addresses and ports values of packet_info before each PDU,
and in desegment_tcp after returning from a subdissector. When leaving
desegment_tcp ensure that the addresses and ports are set to whatever
they were after the last subdissector call that successfully
desegmented a PDU.

Fix #2345. Fix #9782.
This commit is contained in:
John Thacker 2022-05-25 08:46:36 -04:00
parent 95ba1151df
commit 717e4c47ee
1 changed files with 79 additions and 5 deletions
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84
epan/dissectors/packet-tcp.c
View File

@ -3308,6 +3308,36 @@ print_tcp_fragment_tree(fragment_head *ipfd_head, proto_tree *tree, proto_tree *
* However, frames can have multiple PDUs with certain encapsulations like
* GSE or MPE over DVB BaseBand Frames.
*/
typedef struct _tcp_endpoint {
address src_addr;
address dst_addr;
port_type ptype;
guint32 src_port;
guint32 dst_port;
} tcp_endpoint_t;
static void
save_endpoint(packet_info *pinfo, tcp_endpoint_t *a)
{
copy_address_shallow(&a->src_addr, &pinfo->src);
copy_address_shallow(&a->dst_addr, &pinfo->dst);
a->ptype = pinfo->ptype;
a->src_port = pinfo->srcport;
a->dst_port = pinfo->destport;
}
static void
restore_endpoint(packet_info *pinfo, tcp_endpoint_t *a)
{
copy_address_shallow(&pinfo->src, &a->src_addr);
copy_address_shallow(&pinfo->dst, &a->dst_addr);
pinfo->ptype = a->ptype;
pinfo->srcport = a->src_port;
pinfo->destport = a->dst_port;
}
typedef struct _tcp_segment_key {
address src_addr;
address dst_addr;
@ -3676,6 +3706,7 @@ desegment_tcp(tvbuff_t *tvb, packet_info *pinfo, int offset,
int last_fragment_len;
gboolean must_desegment;
gboolean called_dissector;
gboolean has_gap;
int another_pdu_follows;
int deseg_offset;
guint32 deseg_seq;
@ -3685,11 +3716,17 @@ desegment_tcp(tvbuff_t *tvb, packet_info *pinfo, int offset,
gboolean cleared_writable = col_get_writable(pinfo->cinfo, COL_PROTOCOL);
const gboolean reassemble_ooo = tcp_analyze_seq && tcp_desegment && tcp_reassemble_out_of_order;
tcp_endpoint_t orig_endpoint, new_endpoint;
save_endpoint(pinfo, &orig_endpoint);
save_endpoint(pinfo, &new_endpoint);
again:
ipfd_head = NULL;
last_fragment_len = 0;
must_desegment = FALSE;
called_dissector = FALSE;
has_gap = FALSE;
another_pdu_follows = 0;
msp = NULL;
@ -3832,7 +3869,7 @@ again:
proto_tree_add_bytes_format(tcp_tree, hf_tcp_segment_data, tvb, offset,
nbytes, NULL, "%sTCP segment data (%u byte%s)", str, nbytes,
plurality(nbytes, "", "s"));
return;
goto clean_exit;
}
/* The above code only finds retransmission if the PDU boundaries and the seq coincide I think
@ -3854,7 +3891,7 @@ again:
* See issue 10289
*/
if((tcpd->ta->flags&TCP_A_SPURIOUS_RETRANSMISSION) == TCP_A_SPURIOUS_RETRANSMISSION) {
return;
goto clean_exit;
}
if((tcpd->ta->flags&TCP_A_RETRANSMISSION) == TCP_A_RETRANSMISSION) {
const char* str = "Retransmitted ";
@ -3862,7 +3899,7 @@ again:
proto_tree_add_bytes_format(tcp_tree, hf_tcp_segment_data, tvb, offset,
nbytes, NULL, "%sTCP segment data (%u byte%s)", str, nbytes,
plurality(nbytes, "", "s"));
return;
goto clean_exit;
}
}
/* Else, find the most previous PDU starting before this sequence number */
@ -3871,8 +3908,6 @@ again:
}
}
gboolean has_gap = FALSE;
if (reassemble_ooo && tcpd && !(tcpd->fwd->flags & TCP_FLOW_REASSEMBLE_UNTIL_FIN)) {
if (!PINFO_FD_VISITED(pinfo)) {
/* If there is a gap between this segment and any previous ones
@ -4050,6 +4085,20 @@ again:
process_tcp_payload(tvb, offset, pinfo, tree, tcp_tree,
sport, dport, 0, 0, FALSE, tcpd, tcpinfo);
/* Unless it failed to dissect any data at all, the subdissector
* might have changed the addresses and/or ports. Save them, and
* set them back to the original values temporarily so that the
* fragment functions work correctly (including in any later PDU.)
*
* (If we didn't dissect any data, the subdissector *shouldn't*
* have changed the addresses or ports, so don't save them, but
* restore them just in case.)
*/
if (!(pinfo->desegment_len && pinfo->desegment_offset == 0)) {
save_endpoint(pinfo, &new_endpoint);
}
restore_endpoint(pinfo, &orig_endpoint);
called_dissector = TRUE;
/* Did the subdissector ask us to desegment some more data
@ -4113,6 +4162,20 @@ again:
/* call subdissector */
process_tcp_payload(next_tvb, 0, pinfo, tree, tcp_tree, sport,
dport, 0, 0, FALSE, tcpd, tcpinfo);
/* Unless it failed to dissect any data at all, the subdissector
* might have changed the addresses and/or ports. Save them, and
* set them back to the original values temporarily so that the
* fragment functions work correctly (including in any later PDU.)
*
* (If we didn't dissect any data, the subdissector *shouldn't*
* have changed the addresses or ports, so don't save them, but
* restore them just in case.)
*/
if (!(pinfo->desegment_len && pinfo->desegment_offset == 0)) {
save_endpoint(pinfo, &new_endpoint);
}
restore_endpoint(pinfo, &orig_endpoint);
called_dissector = TRUE;
/*
@ -4402,6 +4465,12 @@ again:
col_set_writable(pinfo->cinfo, COL_PROTOCOL, TRUE);
}
}
clean_exit:
/* Restore the addresses and ports to whatever they were after
* the last segment that successfully dissected some data, if any.
*/
restore_endpoint(pinfo, &new_endpoint);
}
void
@ -4421,6 +4490,10 @@ tcp_dissect_pdus(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
guint8 curr_layer_num;
wmem_list_frame_t *frame;
tcp_endpoint_t orig_endpoint;
save_endpoint(pinfo, &orig_endpoint);
while (tvb_reported_length_remaining(tvb, offset) > 0) {
/*
* We use "tvb_ensure_captured_length_remaining()" to make
@ -4591,6 +4664,7 @@ tcp_dissect_pdus(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
* data.
*/
saved_proto = pinfo->current_proto;
restore_endpoint(pinfo, &orig_endpoint);
TRY {
(*dissect_pdu)(next_tvb, pinfo, tree, dissector_data);
}