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isisd: fix router capability TLV parsing issues

Browse Source 
isis_tlvs.c would fail at multiple places if incorrect TLVs were
received causing stream assertion violations.
This patch fixes the issues by adding missing length checks, missing
consumed length updates and handling malformed Segment Routing subTLVs.

Signed-off-by: Juraj Vijtiuk <juraj.vijtiuk@sartura.hr>

Small adjustments by Igor Ryzhov:
- fix incorrect replacement of srgb by srlb on lines 3052 and 3054
- add length check for ISIS_SUBTLV_ALGORITHM
- fix conflict in fuzzing data during rebase

Signed-off-by: Igor Ryzhov <iryzhov@nfware.com>
This commit is contained in:
Juraj Vijtiuk 2021-10-13 18:32:53 +02:00 committed by Igor Ryzhov
parent 249932f969
commit 9ba865f54d
3 changed files with 60 additions and 11 deletions
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70
isisd/isis_tlvs.c
View File

@ -3007,28 +3007,55 @@ static int unpack_tlv_router_cap(enum isis_tlv_context context,
type = stream_getc(s);
length = stream_getc(s);
if (length > STREAM_READABLE(s) || length > subtlv_len - 2) {
sbuf_push(
log, indent,
"WARNING: Router Capability subTLV length too large compared to expected size\n");
stream_forward_getp(s, STREAM_READABLE(s));
return 0;
}
switch (type) {
case ISIS_SUBTLV_SID_LABEL_RANGE:
/* Check that SRGB is correctly formated */
if (length < SUBTLV_RANGE_LABEL_SIZE
|| length > SUBTLV_RANGE_INDEX_SIZE) {
stream_forward_getp(s, length);
continue;
break;
}
/* Only one SRGB is supported. Skip subsequent one */
if (rcap->srgb.range_size != 0) {
stream_forward_getp(s, length);
continue;
break;
}
rcap->srgb.flags = stream_getc(s);
rcap->srgb.range_size = stream_get3(s);
/* Skip Type and get Length of SID Label */
stream_getc(s);
size = stream_getc(s);
if (size == ISIS_SUBTLV_SID_LABEL_SIZE)
if (size == ISIS_SUBTLV_SID_LABEL_SIZE
&& length != SUBTLV_RANGE_LABEL_SIZE) {
stream_forward_getp(s, length - 6);
break;
}
if (size == ISIS_SUBTLV_SID_INDEX_SIZE
&& length != SUBTLV_RANGE_INDEX_SIZE) {
stream_forward_getp(s, length - 6);
break;
}
if (size == ISIS_SUBTLV_SID_LABEL_SIZE) {
rcap->srgb.lower_bound = stream_get3(s);
else
} else if (size == ISIS_SUBTLV_SID_INDEX_SIZE) {
rcap->srgb.lower_bound = stream_getl(s);
} else {
stream_forward_getp(s, length - 6);
break;
}
/* SRGB sanity checks. */
if (rcap->srgb.range_size == 0
@ -3042,9 +3069,12 @@ static int unpack_tlv_router_cap(enum isis_tlv_context context,
/* Only one range is supported. Skip subsequent one */
size = length - (size + SUBTLV_SR_BLOCK_SIZE);
if (size > 0)
stream_forward_getp(s, length);
stream_forward_getp(s, size);
break;
case ISIS_SUBTLV_ALGORITHM:
if (length == 0)
break;
/* Only 2 algorithms are supported: SPF & Strict SPF */
stream_get(&rcap->algo, s,
length > SR_ALGORITHM_COUNT
@ -3059,12 +3089,12 @@ static int unpack_tlv_router_cap(enum isis_tlv_context context,
if (length < SUBTLV_RANGE_LABEL_SIZE
|| length > SUBTLV_RANGE_INDEX_SIZE) {
stream_forward_getp(s, length);
continue;
break;
}
/* RFC 8667 section #3.3: Only one SRLB is authorized */
if (rcap->srlb.range_size != 0) {
stream_forward_getp(s, length);
continue;
break;
}
/* Ignore Flags which are not defined */
stream_getc(s);
@ -3072,10 +3102,27 @@ static int unpack_tlv_router_cap(enum isis_tlv_context context,
/* Skip Type and get Length of SID Label */
stream_getc(s);
size = stream_getc(s);
if (size == ISIS_SUBTLV_SID_LABEL_SIZE)
if (size == ISIS_SUBTLV_SID_LABEL_SIZE
&& length != SUBTLV_RANGE_LABEL_SIZE) {
stream_forward_getp(s, length - 6);
break;
}
if (size == ISIS_SUBTLV_SID_INDEX_SIZE
&& length != SUBTLV_RANGE_INDEX_SIZE) {
stream_forward_getp(s, length - 6);
break;
}
if (size == ISIS_SUBTLV_SID_LABEL_SIZE) {
rcap->srlb.lower_bound = stream_get3(s);
else
} else if (size == ISIS_SUBTLV_SID_INDEX_SIZE) {
rcap->srlb.lower_bound = stream_getl(s);
} else {
stream_forward_getp(s, length - 6);
break;
}
/* SRLB sanity checks. */
if (rcap->srlb.range_size == 0
@ -3089,13 +3136,14 @@ static int unpack_tlv_router_cap(enum isis_tlv_context context,
/* Only one range is supported. Skip subsequent one */
size = length - (size + SUBTLV_SR_BLOCK_SIZE);
if (size > 0)
stream_forward_getp(s, length);
stream_forward_getp(s, size);
break;
case ISIS_SUBTLV_NODE_MSD:
/* Check that MSD is correctly formated */
if (length < MSD_TLV_SIZE) {
stream_forward_getp(s, length);
continue;
break;
}
msd_type = stream_getc(s);
rcap->msd = stream_getc(s);

1
isisd/isis_tlvs.h
View File

@ -447,6 +447,7 @@ enum ext_subtlv_size {
/* RFC 8667 sections #2 & #3 */
ISIS_SUBTLV_SID_LABEL_SIZE = 3,
ISIS_SUBTLV_SID_INDEX_SIZE = 4,
ISIS_SUBTLV_SID_LABEL_RANGE_SIZE = 9,
ISIS_SUBTLV_ALGORITHM_SIZE = 4,
ISIS_SUBTLV_ADJ_SID_SIZE = 5,

BIN
tests/isisd/test_fuzz_isis_tlv_tests.h.gz
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