Re: [RFC PATCH v1 06/10] net: qrtr: Allow sendmsg to target an endpoint

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On 10/18/2024 11:18 AM, Denis Kenzior wrote:
Allow QIPCRTR family sockets to include QRTR_ENDPOINT auxiliary data
as part of the sendmsg system call.  By including this parameter, the
client can ask the kernel to route the message to a given endpoint, in
situations where multiple endpoints with conflicting node identifier
sets exist in the system.

For legacy clients, or clients that do not include QRTR_ENDPOINT data,
the endpoint is looked up, as before, by only using the node identifier
of the destination qrtr socket address.

Signed-off-by: Denis Kenzior <denkenz@xxxxxxxxx>
Reviewed-by: Marcel Holtmann <marcel@xxxxxxxxxxxx>
Reviewed-by: Andy Gross <agross@xxxxxxxxxx>
---
  net/qrtr/af_qrtr.c | 80 +++++++++++++++++++++++++++++++++-------------
  net/qrtr/qrtr.h    |  2 ++
  2 files changed, 60 insertions(+), 22 deletions(-)

diff --git a/net/qrtr/af_qrtr.c b/net/qrtr/af_qrtr.c
index 568ccb1d8574..23749a0b0c15 100644
--- a/net/qrtr/af_qrtr.c
+++ b/net/qrtr/af_qrtr.c
@@ -106,6 +106,36 @@ static inline struct qrtr_sock *qrtr_sk(struct sock *sk)
  	return container_of(sk, struct qrtr_sock, sk);
  }
+int qrtr_msg_get_endpoint(struct msghdr *msg, u32 *out_endpoint_id)
+{
+	struct cmsghdr *cmsg;
+	u32 endpoint_id = 0;
+
+	for_each_cmsghdr(cmsg, msg) {
+		if (!CMSG_OK(msg, cmsg))
+			return -EINVAL;
+
+		if (cmsg->cmsg_level != SOL_QRTR)
+			continue;
+
+		if (cmsg->cmsg_type != QRTR_ENDPOINT)
+			return -EINVAL;
+
+		if (cmsg->cmsg_len < CMSG_LEN(sizeof(u32)))
+			return -EINVAL;
+
+		/* Endpoint ids start at 1 */
+		endpoint_id = *(u32 *)CMSG_DATA(cmsg);
+		if (!endpoint_id)
+			return -EINVAL;
+	}
+
+	if (out_endpoint_id)
+		*out_endpoint_id = endpoint_id;

In the case when there is no cmsg attached to the msg. Would it be safer to assign out_endpoint_id to 0 before returning?

I see that in qrtr_sendmsg() there is a risk of using msg_endpoint_id without it being initialized or assigned a value in this function.

+
+	return 0;
+}
+
  static unsigned int qrtr_local_nid = 1;
/* for node ids */
@@ -404,14 +434,16 @@ static int qrtr_node_enqueue(struct qrtr_node *node, struct sk_buff *skb,
   *
   * callers must release with qrtr_node_release()
   */
-static struct qrtr_node *qrtr_node_lookup(unsigned int nid)
+static struct qrtr_node *qrtr_node_lookup(unsigned int endpoint_id,
+					  unsigned int nid)
  {
  	struct qrtr_node *node;
  	unsigned long flags;
+	unsigned long key = (unsigned long)endpoint_id << 32 | nid;
mutex_lock(&qrtr_node_lock);
  	spin_lock_irqsave(&qrtr_nodes_lock, flags);
-	node = radix_tree_lookup(&qrtr_nodes, nid);
+	node = radix_tree_lookup(&qrtr_nodes, key);
  	node = qrtr_node_acquire(node);
  	spin_unlock_irqrestore(&qrtr_nodes_lock, flags);
  	mutex_unlock(&qrtr_node_lock);
@@ -953,6 +985,7 @@ static int qrtr_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
  	struct qrtr_sock *ipc = qrtr_sk(sock->sk);
  	struct sock *sk = sock->sk;
  	struct qrtr_node *node;
+	u32 msg_endpoint_id;
  	u32 endpoint_id = qrtr_local_nid;
  	struct sk_buff *skb;
  	size_t plen;
@@ -965,46 +998,48 @@ static int qrtr_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
  	if (len > 65535)
  		return -EMSGSIZE;
+ rc = qrtr_msg_get_endpoint(msg, &msg_endpoint_id);
+	if (rc < 0)
+		return rc;
+
  	lock_sock(sk);
if (addr) {
-		if (msg->msg_namelen < sizeof(*addr)) {
-			release_sock(sk);
-			return -EINVAL;
-		}
+		rc = -EINVAL;
- if (addr->sq_family != AF_QIPCRTR) {
-			release_sock(sk);
-			return -EINVAL;
-		}
+		if (msg->msg_namelen < sizeof(*addr))
+			goto release_sock;
+
+		if (addr->sq_family != AF_QIPCRTR)
+			goto release_sock;
rc = qrtr_autobind(sock);
-		if (rc) {
-			release_sock(sk);
-			return rc;
-		}
+		if (rc)
+			goto release_sock;
  	} else if (sk->sk_state == TCP_ESTABLISHED) {
  		addr = &ipc->peer;
  	} else {
-		release_sock(sk);
-		return -ENOTCONN;
+		rc = -ENOTCONN;
+		goto release_sock;
  	}
node = NULL;
  	if (addr->sq_node == QRTR_NODE_BCAST) {
  		if (addr->sq_port != QRTR_PORT_CTRL &&
  		    qrtr_local_nid != QRTR_NODE_BCAST) {
-			release_sock(sk);
-			return -ENOTCONN;
+			rc = -ENOTCONN;
+			goto release_sock;
  		}
  		enqueue_fn = qrtr_bcast_enqueue;
  	} else if (addr->sq_node == ipc->us.sq_node) {
  		enqueue_fn = qrtr_local_enqueue;
  	} else {
-		node = qrtr_node_lookup(addr->sq_node);
+		endpoint_id = msg_endpoint_id;
+
+		node = qrtr_node_lookup(endpoint_id, addr->sq_node);
  		if (!node) {
-			release_sock(sk);
-			return -ECONNRESET;
+			rc = endpoint_id ? -ENXIO : -ECONNRESET;
+			goto release_sock;
  		}
  		enqueue_fn = qrtr_node_enqueue;
  	}
@@ -1043,6 +1078,7 @@ static int qrtr_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
out_node:
  	qrtr_node_release(node);
+release_sock:
  	release_sock(sk);
return rc;
@@ -1057,7 +1093,7 @@ static int qrtr_send_resume_tx(struct qrtr_cb *cb)
  	struct sk_buff *skb;
  	int ret;
- node = qrtr_node_lookup(remote.sq_node);
+	node = qrtr_node_lookup(cb->endpoint_id, remote.sq_node);
  	if (!node)
  		return -EINVAL;
diff --git a/net/qrtr/qrtr.h b/net/qrtr/qrtr.h
index 11b897af05e6..22fcecbf8de2 100644
--- a/net/qrtr/qrtr.h
+++ b/net/qrtr/qrtr.h
@@ -34,4 +34,6 @@ int qrtr_ns_init(void);
void qrtr_ns_remove(void); +int qrtr_msg_get_endpoint(struct msghdr *msg, u32 *out_endpoint_id);
+
  #endif




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