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-rw-r--r--net/sctp/sm_statefuns.c243
1 files changed, 204 insertions, 39 deletions
diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
index 177528ed3e1b..a583d67cab63 100644
--- a/net/sctp/sm_statefuns.c
+++ b/net/sctp/sm_statefuns.c
@@ -90,6 +90,11 @@ static sctp_disposition_t sctp_sf_shut_8_4_5(const struct sctp_endpoint *ep,
const sctp_subtype_t type,
void *arg,
sctp_cmd_seq_t *commands);
+static sctp_disposition_t sctp_sf_tabort_8_4_8(const struct sctp_endpoint *ep,
+ const struct sctp_association *asoc,
+ const sctp_subtype_t type,
+ void *arg,
+ sctp_cmd_seq_t *commands);
static struct sctp_sackhdr *sctp_sm_pull_sack(struct sctp_chunk *chunk);
static sctp_disposition_t sctp_stop_t1_and_abort(sctp_cmd_seq_t *commands,
@@ -98,6 +103,7 @@ static sctp_disposition_t sctp_stop_t1_and_abort(sctp_cmd_seq_t *commands,
struct sctp_transport *transport);
static sctp_disposition_t sctp_sf_abort_violation(
+ const struct sctp_endpoint *ep,
const struct sctp_association *asoc,
void *arg,
sctp_cmd_seq_t *commands,
@@ -111,6 +117,13 @@ static sctp_disposition_t sctp_sf_violation_chunklen(
void *arg,
sctp_cmd_seq_t *commands);
+static sctp_disposition_t sctp_sf_violation_paramlen(
+ const struct sctp_endpoint *ep,
+ const struct sctp_association *asoc,
+ const sctp_subtype_t type,
+ void *arg,
+ sctp_cmd_seq_t *commands);
+
static sctp_disposition_t sctp_sf_violation_ctsn(
const struct sctp_endpoint *ep,
const struct sctp_association *asoc,
@@ -118,6 +131,13 @@ static sctp_disposition_t sctp_sf_violation_ctsn(
void *arg,
sctp_cmd_seq_t *commands);
+static sctp_disposition_t sctp_sf_violation_chunk(
+ const struct sctp_endpoint *ep,
+ const struct sctp_association *asoc,
+ const sctp_subtype_t type,
+ void *arg,
+ sctp_cmd_seq_t *commands);
+
/* Small helper function that checks if the chunk length
* is of the appropriate length. The 'required_length' argument
* is set to be the size of a specific chunk we are testing.
@@ -181,16 +201,21 @@ sctp_disposition_t sctp_sf_do_4_C(const struct sctp_endpoint *ep,
struct sctp_chunk *chunk = arg;
struct sctp_ulpevent *ev;
+ if (!sctp_vtag_verify_either(chunk, asoc))
+ return sctp_sf_pdiscard(ep, asoc, type, arg, commands);
+
/* RFC 2960 6.10 Bundling
*
* An endpoint MUST NOT bundle INIT, INIT ACK or
* SHUTDOWN COMPLETE with any other chunks.
*/
if (!chunk->singleton)
- return SCTP_DISPOSITION_VIOLATION;
+ return sctp_sf_violation_chunk(ep, asoc, type, arg, commands);
- if (!sctp_vtag_verify_either(chunk, asoc))
- return sctp_sf_pdiscard(ep, asoc, type, arg, commands);
+ /* Make sure that the SHUTDOWN_COMPLETE chunk has a valid length. */
+ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t)))
+ return sctp_sf_violation_chunklen(ep, asoc, type, arg,
+ commands);
/* RFC 2960 10.2 SCTP-to-ULP
*
@@ -450,17 +475,17 @@ sctp_disposition_t sctp_sf_do_5_1C_ack(const struct sctp_endpoint *ep,
if (!sctp_vtag_verify(chunk, asoc))
return sctp_sf_pdiscard(ep, asoc, type, arg, commands);
- /* Make sure that the INIT-ACK chunk has a valid length */
- if (!sctp_chunk_length_valid(chunk, sizeof(sctp_initack_chunk_t)))
- return sctp_sf_violation_chunklen(ep, asoc, type, arg,
- commands);
/* 6.10 Bundling
* An endpoint MUST NOT bundle INIT, INIT ACK or
* SHUTDOWN COMPLETE with any other chunks.
*/
if (!chunk->singleton)
- return SCTP_DISPOSITION_VIOLATION;
+ return sctp_sf_violation_chunk(ep, asoc, type, arg, commands);
+ /* Make sure that the INIT-ACK chunk has a valid length */
+ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_initack_chunk_t)))
+ return sctp_sf_violation_chunklen(ep, asoc, type, arg,
+ commands);
/* Grab the INIT header. */
chunk->subh.init_hdr = (sctp_inithdr_t *) chunk->skb->data;
@@ -585,7 +610,7 @@ sctp_disposition_t sctp_sf_do_5_1D_ce(const struct sctp_endpoint *ep,
* control endpoint, respond with an ABORT.
*/
if (ep == sctp_sk((sctp_get_ctl_sock()))->ep)
- return sctp_sf_ootb(ep, asoc, type, arg, commands);
+ return sctp_sf_tabort_8_4_8(ep, asoc, type, arg, commands);
/* Make sure that the COOKIE_ECHO chunk has a valid length.
* In this case, we check that we have enough for at least a
@@ -2496,6 +2521,11 @@ sctp_disposition_t sctp_sf_do_9_2_reshutack(const struct sctp_endpoint *ep,
struct sctp_chunk *chunk = (struct sctp_chunk *) arg;
struct sctp_chunk *reply;
+ /* Make sure that the chunk has a valid length */
+ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t)))
+ return sctp_sf_violation_chunklen(ep, asoc, type, arg,
+ commands);
+
/* Since we are not going to really process this INIT, there
* is no point in verifying chunk boundries. Just generate
* the SHUTDOWN ACK.
@@ -2929,7 +2959,7 @@ sctp_disposition_t sctp_sf_eat_sack_6_2(const struct sctp_endpoint *ep,
*
* The return value is the disposition of the chunk.
*/
-sctp_disposition_t sctp_sf_tabort_8_4_8(const struct sctp_endpoint *ep,
+static sctp_disposition_t sctp_sf_tabort_8_4_8(const struct sctp_endpoint *ep,
const struct sctp_association *asoc,
const sctp_subtype_t type,
void *arg,
@@ -2965,6 +2995,7 @@ sctp_disposition_t sctp_sf_tabort_8_4_8(const struct sctp_endpoint *ep,
SCTP_INC_STATS(SCTP_MIB_OUTCTRLCHUNKS);
+ sctp_sf_pdiscard(ep, asoc, type, arg, commands);
return SCTP_DISPOSITION_CONSUME;
}
@@ -3125,14 +3156,14 @@ sctp_disposition_t sctp_sf_ootb(const struct sctp_endpoint *ep,
ch = (sctp_chunkhdr_t *) chunk->chunk_hdr;
do {
- /* Break out if chunk length is less then minimal. */
+ /* Report violation if the chunk is less then minimal */
if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
- break;
-
- ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
- if (ch_end > skb_tail_pointer(skb))
- break;
+ return sctp_sf_violation_chunklen(ep, asoc, type, arg,
+ commands);
+ /* Now that we know we at least have a chunk header,
+ * do things that are type appropriate.
+ */
if (SCTP_CID_SHUTDOWN_ACK == ch->type)
ootb_shut_ack = 1;
@@ -3144,15 +3175,19 @@ sctp_disposition_t sctp_sf_ootb(const struct sctp_endpoint *ep,
if (SCTP_CID_ABORT == ch->type)
return sctp_sf_pdiscard(ep, asoc, type, arg, commands);
+ /* Report violation if chunk len overflows */
+ ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
+ if (ch_end > skb_tail_pointer(skb))
+ return sctp_sf_violation_chunklen(ep, asoc, type, arg,
+ commands);
+
ch = (sctp_chunkhdr_t *) ch_end;
} while (ch_end < skb_tail_pointer(skb));
if (ootb_shut_ack)
- sctp_sf_shut_8_4_5(ep, asoc, type, arg, commands);
+ return sctp_sf_shut_8_4_5(ep, asoc, type, arg, commands);
else
- sctp_sf_tabort_8_4_8(ep, asoc, type, arg, commands);
-
- return sctp_sf_pdiscard(ep, asoc, type, arg, commands);
+ return sctp_sf_tabort_8_4_8(ep, asoc, type, arg, commands);
}
/*
@@ -3218,7 +3253,11 @@ static sctp_disposition_t sctp_sf_shut_8_4_5(const struct sctp_endpoint *ep,
if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t)))
return sctp_sf_pdiscard(ep, asoc, type, arg, commands);
- return SCTP_DISPOSITION_CONSUME;
+ /* We need to discard the rest of the packet to prevent
+ * potential bomming attacks from additional bundled chunks.
+ * This is documented in SCTP Threats ID.
+ */
+ return sctp_sf_pdiscard(ep, asoc, type, arg, commands);
}
return SCTP_DISPOSITION_NOMEM;
@@ -3241,6 +3280,13 @@ sctp_disposition_t sctp_sf_do_8_5_1_E_sa(const struct sctp_endpoint *ep,
void *arg,
sctp_cmd_seq_t *commands)
{
+ struct sctp_chunk *chunk = arg;
+
+ /* Make sure that the SHUTDOWN_ACK chunk has a valid length. */
+ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t)))
+ return sctp_sf_violation_chunklen(ep, asoc, type, arg,
+ commands);
+
/* Although we do have an association in this case, it corresponds
* to a restarted association. So the packet is treated as an OOTB
* packet and the state function that handles OOTB SHUTDOWN_ACK is
@@ -3257,8 +3303,11 @@ sctp_disposition_t sctp_sf_do_asconf(const struct sctp_endpoint *ep,
{
struct sctp_chunk *chunk = arg;
struct sctp_chunk *asconf_ack = NULL;
+ struct sctp_paramhdr *err_param = NULL;
sctp_addiphdr_t *hdr;
+ union sctp_addr_param *addr_param;
__u32 serial;
+ int length;
if (!sctp_vtag_verify(chunk, asoc)) {
sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG,
@@ -3274,6 +3323,20 @@ sctp_disposition_t sctp_sf_do_asconf(const struct sctp_endpoint *ep,
hdr = (sctp_addiphdr_t *)chunk->skb->data;
serial = ntohl(hdr->serial);
+ addr_param = (union sctp_addr_param *)hdr->params;
+ length = ntohs(addr_param->p.length);
+ if (length < sizeof(sctp_paramhdr_t))
+ return sctp_sf_violation_paramlen(ep, asoc, type,
+ (void *)addr_param, commands);
+
+ /* Verify the ASCONF chunk before processing it. */
+ if (!sctp_verify_asconf(asoc,
+ (sctp_paramhdr_t *)((void *)addr_param + length),
+ (void *)chunk->chunk_end,
+ &err_param))
+ return sctp_sf_violation_paramlen(ep, asoc, type,
+ (void *)&err_param, commands);
+
/* ADDIP 4.2 C1) Compare the value of the serial number to the value
* the endpoint stored in a new association variable
* 'Peer-Serial-Number'.
@@ -3328,6 +3391,7 @@ sctp_disposition_t sctp_sf_do_asconf_ack(const struct sctp_endpoint *ep,
struct sctp_chunk *asconf_ack = arg;
struct sctp_chunk *last_asconf = asoc->addip_last_asconf;
struct sctp_chunk *abort;
+ struct sctp_paramhdr *err_param = NULL;
sctp_addiphdr_t *addip_hdr;
__u32 sent_serial, rcvd_serial;
@@ -3345,6 +3409,14 @@ sctp_disposition_t sctp_sf_do_asconf_ack(const struct sctp_endpoint *ep,
addip_hdr = (sctp_addiphdr_t *)asconf_ack->skb->data;
rcvd_serial = ntohl(addip_hdr->serial);
+ /* Verify the ASCONF-ACK chunk before processing it. */
+ if (!sctp_verify_asconf(asoc,
+ (sctp_paramhdr_t *)addip_hdr->params,
+ (void *)asconf_ack->chunk_end,
+ &err_param))
+ return sctp_sf_violation_paramlen(ep, asoc, type,
+ (void *)&err_param, commands);
+
if (last_asconf) {
addip_hdr = (sctp_addiphdr_t *)last_asconf->subh.addip_hdr;
sent_serial = ntohl(addip_hdr->serial);
@@ -3655,6 +3727,16 @@ sctp_disposition_t sctp_sf_discard_chunk(const struct sctp_endpoint *ep,
void *arg,
sctp_cmd_seq_t *commands)
{
+ struct sctp_chunk *chunk = arg;
+
+ /* Make sure that the chunk has a valid length.
+ * Since we don't know the chunk type, we use a general
+ * chunkhdr structure to make a comparison.
+ */
+ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t)))
+ return sctp_sf_violation_chunklen(ep, asoc, type, arg,
+ commands);
+
SCTP_DEBUG_PRINTK("Chunk %d is discarded\n", type.chunk);
return SCTP_DISPOSITION_DISCARD;
}
@@ -3710,6 +3792,13 @@ sctp_disposition_t sctp_sf_violation(const struct sctp_endpoint *ep,
void *arg,
sctp_cmd_seq_t *commands)
{
+ struct sctp_chunk *chunk = arg;
+
+ /* Make sure that the chunk has a valid length. */
+ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t)))
+ return sctp_sf_violation_chunklen(ep, asoc, type, arg,
+ commands);
+
return SCTP_DISPOSITION_VIOLATION;
}
@@ -3717,12 +3806,14 @@ sctp_disposition_t sctp_sf_violation(const struct sctp_endpoint *ep,
* Common function to handle a protocol violation.
*/
static sctp_disposition_t sctp_sf_abort_violation(
+ const struct sctp_endpoint *ep,
const struct sctp_association *asoc,
void *arg,
sctp_cmd_seq_t *commands,
const __u8 *payload,
const size_t paylen)
{
+ struct sctp_packet *packet = NULL;
struct sctp_chunk *chunk = arg;
struct sctp_chunk *abort = NULL;
@@ -3731,30 +3822,51 @@ static sctp_disposition_t sctp_sf_abort_violation(
if (!abort)
goto nomem;
- sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort));
- SCTP_INC_STATS(SCTP_MIB_OUTCTRLCHUNKS);
+ if (asoc) {
+ sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort));
+ SCTP_INC_STATS(SCTP_MIB_OUTCTRLCHUNKS);
- if (asoc->state <= SCTP_STATE_COOKIE_ECHOED) {
- sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
- SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
- sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
- SCTP_ERROR(ECONNREFUSED));
- sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED,
- SCTP_PERR(SCTP_ERROR_PROTO_VIOLATION));
+ if (asoc->state <= SCTP_STATE_COOKIE_ECHOED) {
+ sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
+ SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
+ sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
+ SCTP_ERROR(ECONNREFUSED));
+ sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED,
+ SCTP_PERR(SCTP_ERROR_PROTO_VIOLATION));
+ } else {
+ sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
+ SCTP_ERROR(ECONNABORTED));
+ sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
+ SCTP_PERR(SCTP_ERROR_PROTO_VIOLATION));
+ SCTP_DEC_STATS(SCTP_MIB_CURRESTAB);
+ }
} else {
- sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
- SCTP_ERROR(ECONNABORTED));
- sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
- SCTP_PERR(SCTP_ERROR_PROTO_VIOLATION));
- SCTP_DEC_STATS(SCTP_MIB_CURRESTAB);
+ packet = sctp_ootb_pkt_new(asoc, chunk);
+
+ if (!packet)
+ goto nomem_pkt;
+
+ if (sctp_test_T_bit(abort))
+ packet->vtag = ntohl(chunk->sctp_hdr->vtag);
+
+ abort->skb->sk = ep->base.sk;
+
+ sctp_packet_append_chunk(packet, abort);
+
+ sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT,
+ SCTP_PACKET(packet));
+
+ SCTP_INC_STATS(SCTP_MIB_OUTCTRLCHUNKS);
}
- sctp_add_cmd_sf(commands, SCTP_CMD_DISCARD_PACKET, SCTP_NULL());
+ sctp_sf_pdiscard(ep, asoc, SCTP_ST_CHUNK(0), arg, commands);
SCTP_INC_STATS(SCTP_MIB_ABORTEDS);
return SCTP_DISPOSITION_ABORT;
+nomem_pkt:
+ sctp_chunk_free(abort);
nomem:
return SCTP_DISPOSITION_NOMEM;
}
@@ -3787,7 +3899,24 @@ static sctp_disposition_t sctp_sf_violation_chunklen(
{
char err_str[]="The following chunk had invalid length:";
- return sctp_sf_abort_violation(asoc, arg, commands, err_str,
+ return sctp_sf_abort_violation(ep, asoc, arg, commands, err_str,
+ sizeof(err_str));
+}
+
+/*
+ * Handle a protocol violation when the parameter length is invalid.
+ * "Invalid" length is identified as smaller then the minimal length a
+ * given parameter can be.
+ */
+static sctp_disposition_t sctp_sf_violation_paramlen(
+ const struct sctp_endpoint *ep,
+ const struct sctp_association *asoc,
+ const sctp_subtype_t type,
+ void *arg,
+ sctp_cmd_seq_t *commands) {
+ char err_str[] = "The following parameter had invalid length:";
+
+ return sctp_sf_abort_violation(ep, asoc, arg, commands, err_str,
sizeof(err_str));
}
@@ -3806,10 +3935,31 @@ static sctp_disposition_t sctp_sf_violation_ctsn(
{
char err_str[]="The cumulative tsn ack beyond the max tsn currently sent:";
- return sctp_sf_abort_violation(asoc, arg, commands, err_str,
+ return sctp_sf_abort_violation(ep, asoc, arg, commands, err_str,
sizeof(err_str));
}
+/* Handle protocol violation of an invalid chunk bundling. For example,
+ * when we have an association and we recieve bundled INIT-ACK, or
+ * SHUDOWN-COMPLETE, our peer is clearly violationg the "MUST NOT bundle"
+ * statement from the specs. Additinally, there might be an attacker
+ * on the path and we may not want to continue this communication.
+ */
+static sctp_disposition_t sctp_sf_violation_chunk(
+ const struct sctp_endpoint *ep,
+ const struct sctp_association *asoc,
+ const sctp_subtype_t type,
+ void *arg,
+ sctp_cmd_seq_t *commands)
+{
+ char err_str[]="The following chunk violates protocol:";
+
+ if (!asoc)
+ return sctp_sf_violation(ep, asoc, type, arg, commands);
+
+ return sctp_sf_abort_violation(ep, asoc, arg, commands, err_str,
+ sizeof(err_str));
+}
/***************************************************************************
* These are the state functions for handling primitive (Section 10) events.
***************************************************************************/
@@ -5176,7 +5326,22 @@ static struct sctp_packet *sctp_ootb_pkt_new(const struct sctp_association *asoc
* association exists, otherwise, use the peer's vtag.
*/
if (asoc) {
- vtag = asoc->peer.i.init_tag;
+ /* Special case the INIT-ACK as there is no peer's vtag
+ * yet.
+ */
+ switch(chunk->chunk_hdr->type) {
+ case SCTP_CID_INIT_ACK:
+ {
+ sctp_initack_chunk_t *initack;
+
+ initack = (sctp_initack_chunk_t *)chunk->chunk_hdr;
+ vtag = ntohl(initack->init_hdr.init_tag);
+ break;
+ }
+ default:
+ vtag = asoc->peer.i.init_tag;
+ break;
+ }
} else {
/* Special case the INIT and stale COOKIE_ECHO as there is no
* vtag yet.
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.