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From:   Lin Ma <linma@zju.edu.cn>
To:     lduncan@suse.com, cleech@redhat.com, michael.christie@oracle.com,
        jejb@linux.ibm.com, martin.petersen@oracle.com,
        open-iscsi@googlegroups.com, linux-scsi@vger.kernel.org,
        linux-kernel@vger.kernel.org
Cc:     Lin Ma <linma@zju.edu.cn>
Subject: [PATCH v1 1/2] scsi: iscsi: Add length check for nlattr payload
Date:   Sun, 23 Jul 2023 15:57:57 +0800
Message-Id: <20230723075757.3712913-1-linma@zju.edu.cn>
Precedence: bulk

The current NETLINK_ISCSI netlink parsing loop checks every nlmsg to
make sure the length is bigger than the sizeof(struct iscsi_uevent) and
then calls iscsi_if_recv_msg(...).

  nlh = nlmsg_hdr(skb);
  if (nlh->nlmsg_len < sizeof(*nlh) + sizeof(*ev) ||
    skb->len < nlh->nlmsg_len) {
    break;
  }
  ...
  err = iscsi_if_recv_msg(skb, nlh, &group);

Hence, in iscsi_if_recv_msg, the nlmsg_data can be safely converted to
iscsi_uevent as the length is already checked.

However, in the following parsing, the length of nlattr payload is never
checked before the payload is converted to other data structures in some
consumers. A bad one for example is function iscsi_set_path(...) who
converts the payload to type iscsi_path without any checks.

  params = (struct iscsi_path *)((char *)ev + sizeof(*ev));

A good one for example is function iscsi_if_transport_conn(...) who
checks the pdu_len.

  pdu_len = nlh->nlmsg_len - sizeof(*nlh) - sizeof(*ev);
  if ((ev->u.send_pdu.hdr_size > pdu_len) ..
    err = -EINVAL;

To sum up, some consumers code called in iscsi_if_recv_msg do not check
the length of the data (see below picture)  and directly converts the
data to other structure. This could result in an out-of-bound read and
heap dirty data leakage.

             _________  nlmsg_len(nlh) _______________
            /                                         \
+----------+--------------+---------------------------+
| nlmsghdr | iscsi_uevent |          data              |
+----------+--------------+---------------------------+
                          \                          /
                         iscsi_uevent->u.set_param.len

This commit fixs the disscussed issue by adding the length check before
accessing it. To cleanup the code, an additional parameter named rlen is
added into many consumer functions prototype. The rlen is calculated in
the beginning of the iscsi_if_recv_msg which could also reduces
unnecessary duplicated calculation.

Fixes: ac20c7bf070d ("[SCSI] iscsi_transport: Added Ping support")
Fixes: 43514774ff40 ("[SCSI] iscsi class: Add new NETLINK_ISCSI messages for cnic/bnx2i driver.")
Fixes: 1d9bf13a9cf9 ("[SCSI] iscsi class: add iscsi host set param event")
Fixes: 01cb225dad8d ("[SCSI] iscsi: add target discvery event to transport class")
Fixes: 264faaaa1254 ("[SCSI] iscsi: add transport end point callbacks")
Fixes: fd7255f51a13 ("[SCSI] iscsi: add sysfs attrs for uspace sync up")
Signed-off-by: Lin Ma <linma@zju.edu.cn>
---
 drivers/scsi/scsi_transport_iscsi.c | 72 +++++++++++++++++------------
 1 file changed, 43 insertions(+), 29 deletions(-)

diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index e527ece12453..62b24f1c0232 100644
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -3014,14 +3014,15 @@ iscsi_if_destroy_conn(struct iscsi_transport *transport, struct iscsi_uevent *ev
 }
 
 static int
-iscsi_if_set_param(struct iscsi_transport *transport, struct iscsi_uevent *ev)
+iscsi_if_set_param(struct iscsi_transport *transport, struct iscsi_uevent *ev, u32 rlen)
 {
 	char *data = (char*)ev + sizeof(*ev);
 	struct iscsi_cls_conn *conn;
 	struct iscsi_cls_session *session;
 	int err = 0, value = 0, state;
 
-	if (ev->u.set_param.len > PAGE_SIZE)
+	if (ev->u.set_param.len > rlen ||
+	    ev->u.set_param.len > PAGE_SIZE)
 		return -EINVAL;
 
 	session = iscsi_session_lookup(ev->u.set_param.sid);
@@ -3118,7 +3119,7 @@ static int iscsi_if_ep_disconnect(struct iscsi_transport *transport,
 
 static int
 iscsi_if_transport_ep(struct iscsi_transport *transport,
-		      struct iscsi_uevent *ev, int msg_type)
+		      struct iscsi_uevent *ev, int msg_type, u32 rlen)
 {
 	struct iscsi_endpoint *ep;
 	int rc = 0;
@@ -3126,7 +3127,10 @@ iscsi_if_transport_ep(struct iscsi_transport *transport,
 	switch (msg_type) {
 	case ISCSI_UEVENT_TRANSPORT_EP_CONNECT_THROUGH_HOST:
 	case ISCSI_UEVENT_TRANSPORT_EP_CONNECT:
-		rc = iscsi_if_ep_connect(transport, ev, msg_type);
+		if (rlen < sizeof(struct sockaddr))
+			rc = -EINVAL;
+		else
+			rc = iscsi_if_ep_connect(transport, ev, msg_type);
 		break;
 	case ISCSI_UEVENT_TRANSPORT_EP_POLL:
 		if (!transport->ep_poll)
@@ -3150,12 +3154,15 @@ iscsi_if_transport_ep(struct iscsi_transport *transport,
 
 static int
 iscsi_tgt_dscvr(struct iscsi_transport *transport,
-		struct iscsi_uevent *ev)
+		struct iscsi_uevent *ev, u32 rlen)
 {
 	struct Scsi_Host *shost;
 	struct sockaddr *dst_addr;
 	int err;
 
+	if (rlen < sizeof(*dst_addr))
+		return -EINVAL;
+
 	if (!transport->tgt_dscvr)
 		return -EINVAL;
 
@@ -3176,7 +3183,7 @@ iscsi_tgt_dscvr(struct iscsi_transport *transport,
 
 static int
 iscsi_set_host_param(struct iscsi_transport *transport,
-		     struct iscsi_uevent *ev)
+		     struct iscsi_uevent *ev, u32 rlen)
 {
 	char *data = (char*)ev + sizeof(*ev);
 	struct Scsi_Host *shost;
@@ -3185,7 +3192,8 @@ iscsi_set_host_param(struct iscsi_transport *transport,
 	if (!transport->set_host_param)
 		return -ENOSYS;
 
-	if (ev->u.set_host_param.len > PAGE_SIZE)
+	if (ev->u.set_host_param.len > rlen ||
+	    ev->u.set_host_param.len > PAGE_SIZE)
 		return -EINVAL;
 
 	shost = scsi_host_lookup(ev->u.set_host_param.host_no);
@@ -3202,12 +3210,15 @@ iscsi_set_host_param(struct iscsi_transport *transport,
 }
 
 static int
-iscsi_set_path(struct iscsi_transport *transport, struct iscsi_uevent *ev)
+iscsi_set_path(struct iscsi_transport *transport, struct iscsi_uevent *ev, u32 rlen)
 {
 	struct Scsi_Host *shost;
 	struct iscsi_path *params;
 	int err;
 
+	if (rlen < sizeof(*params))
+		return -EINVAL;
+
 	if (!transport->set_path)
 		return -ENOSYS;
 
@@ -3267,12 +3278,15 @@ iscsi_set_iface_params(struct iscsi_transport *transport,
 }
 
 static int
-iscsi_send_ping(struct iscsi_transport *transport, struct iscsi_uevent *ev)
+iscsi_send_ping(struct iscsi_transport *transport, struct iscsi_uevent *ev, u32 rlen)
 {
 	struct Scsi_Host *shost;
 	struct sockaddr *dst_addr;
 	int err;
 
+	if (rlen < sizeof(*dst_addr))
+		return -EINVAL;
+
 	if (!transport->send_ping)
 		return -ENOSYS;
 
@@ -3770,13 +3784,12 @@ iscsi_get_host_stats(struct iscsi_transport *transport, struct nlmsghdr *nlh)
 }
 
 static int iscsi_if_transport_conn(struct iscsi_transport *transport,
-				   struct nlmsghdr *nlh)
+				   struct nlmsghdr *nlh, u32 pdu_len)
 {
 	struct iscsi_uevent *ev = nlmsg_data(nlh);
 	struct iscsi_cls_session *session;
 	struct iscsi_cls_conn *conn = NULL;
 	struct iscsi_endpoint *ep;
-	uint32_t pdu_len;
 	int err = 0;
 
 	switch (nlh->nlmsg_type) {
@@ -3861,8 +3874,6 @@ static int iscsi_if_transport_conn(struct iscsi_transport *transport,
 
 		break;
 	case ISCSI_UEVENT_SEND_PDU:
-		pdu_len = nlh->nlmsg_len - sizeof(*nlh) - sizeof(*ev);
-
 		if ((ev->u.send_pdu.hdr_size > pdu_len) ||
 		    (ev->u.send_pdu.data_size > (pdu_len - ev->u.send_pdu.hdr_size))) {
 			err = -EINVAL;
@@ -3892,6 +3903,7 @@ iscsi_if_recv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, uint32_t *group)
 	struct iscsi_internal *priv;
 	struct iscsi_cls_session *session;
 	struct iscsi_endpoint *ep = NULL;
+	u32 rlen;
 
 	if (!netlink_capable(skb, CAP_SYS_ADMIN))
 		return -EPERM;
@@ -3911,6 +3923,13 @@ iscsi_if_recv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, uint32_t *group)
 
 	portid = NETLINK_CB(skb).portid;
 
+	/*
+	 * Even though the remaining payload may not be regarded as nlattr,
+	 * (like address or something else), calculate the remaining length
+	 * here to ease following length checks.
+	 */
+	rlen = nlmsg_attrlen(nlh, sizeof(*ev));
+
 	switch (nlh->nlmsg_type) {
 	case ISCSI_UEVENT_CREATE_SESSION:
 		err = iscsi_if_create_session(priv, ep, ev,
@@ -3967,7 +3986,7 @@ iscsi_if_recv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, uint32_t *group)
 			err = -EINVAL;
 		break;
 	case ISCSI_UEVENT_SET_PARAM:
-		err = iscsi_if_set_param(transport, ev);
+		err = iscsi_if_set_param(transport, ev, rlen);
 		break;
 	case ISCSI_UEVENT_CREATE_CONN:
 	case ISCSI_UEVENT_DESTROY_CONN:
@@ -3975,7 +3994,7 @@ iscsi_if_recv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, uint32_t *group)
 	case ISCSI_UEVENT_START_CONN:
 	case ISCSI_UEVENT_BIND_CONN:
 	case ISCSI_UEVENT_SEND_PDU:
-		err = iscsi_if_transport_conn(transport, nlh);
+		err = iscsi_if_transport_conn(transport, nlh, rlen);
 		break;
 	case ISCSI_UEVENT_GET_STATS:
 		err = iscsi_if_get_stats(transport, nlh);
@@ -3984,23 +4003,22 @@ iscsi_if_recv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, uint32_t *group)
 	case ISCSI_UEVENT_TRANSPORT_EP_POLL:
 	case ISCSI_UEVENT_TRANSPORT_EP_DISCONNECT:
 	case ISCSI_UEVENT_TRANSPORT_EP_CONNECT_THROUGH_HOST:
-		err = iscsi_if_transport_ep(transport, ev, nlh->nlmsg_type);
+		err = iscsi_if_transport_ep(transport, ev, nlh->nlmsg_type, rlen);
 		break;
 	case ISCSI_UEVENT_TGT_DSCVR:
-		err = iscsi_tgt_dscvr(transport, ev);
+		err = iscsi_tgt_dscvr(transport, ev, rlen);
 		break;
 	case ISCSI_UEVENT_SET_HOST_PARAM:
-		err = iscsi_set_host_param(transport, ev);
+		err = iscsi_set_host_param(transport, ev, rlen);
 		break;
 	case ISCSI_UEVENT_PATH_UPDATE:
-		err = iscsi_set_path(transport, ev);
+		err = iscsi_set_path(transport, ev, rlen);
 		break;
 	case ISCSI_UEVENT_SET_IFACE_PARAMS:
-		err = iscsi_set_iface_params(transport, ev,
-					     nlmsg_attrlen(nlh, sizeof(*ev)));
+		err = iscsi_set_iface_params(transport, ev, rlen);
 		break;
 	case ISCSI_UEVENT_PING:
-		err = iscsi_send_ping(transport, ev);
+		err = iscsi_send_ping(transport, ev, rlen);
 		break;
 	case ISCSI_UEVENT_GET_CHAP:
 		err = iscsi_get_chap(transport, nlh);
@@ -4009,13 +4027,10 @@ iscsi_if_recv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, uint32_t *group)
 		err = iscsi_delete_chap(transport, ev);
 		break;
 	case ISCSI_UEVENT_SET_FLASHNODE_PARAMS:
-		err = iscsi_set_flashnode_param(transport, ev,
-						nlmsg_attrlen(nlh,
-							      sizeof(*ev)));
+		err = iscsi_set_flashnode_param(transport, ev, rlen);
 		break;
 	case ISCSI_UEVENT_NEW_FLASHNODE:
-		err = iscsi_new_flashnode(transport, ev,
-					  nlmsg_attrlen(nlh, sizeof(*ev)));
+		err = iscsi_new_flashnode(transport, ev, rlen);
 		break;
 	case ISCSI_UEVENT_DEL_FLASHNODE:
 		err = iscsi_del_flashnode(transport, ev);
@@ -4030,8 +4045,7 @@ iscsi_if_recv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, uint32_t *group)
 		err = iscsi_logout_flashnode_sid(transport, ev);
 		break;
 	case ISCSI_UEVENT_SET_CHAP:
-		err = iscsi_set_chap(transport, ev,
-				     nlmsg_attrlen(nlh, sizeof(*ev)));
+		err = iscsi_set_chap(transport, ev, rlen);
 		break;
 	case ISCSI_UEVENT_GET_HOST_STATS:
 		err = iscsi_get_host_stats(transport, nlh);
-- 
2.17.1