[PATCH] 9p/rdma: create RDMA CM ID in caller's net namespace

[Yizhou Zhao]

The 9p RDMA transport currently passes &init_net to rdma_create_id().
As a result, RDMA address resolution and connection setup are performed
in the initial network namespace, even when the mount is initiated from
a non-initial network namespace.

This differs from the socket-based 9p transports, which create sockets
in current->nsproxy->net_ns.  Use the caller's network namespace for the
RDMA CM ID as well, so that RDMA transport setup follows the same
namespace context as the process performing the mount.

This avoids surprising behaviour where a 9p RDMA mount from a container
or other non-initial network namespace may use the host namespace for
RDMA CM operations.

Fixes: fa20105e09e9 ("IB/cma: Add support for network namespaces")
Reported-by: Yizhou Zhao <zhaoyz24@xxxxxxxxxxxxxxxxxxxxx>
Reported-by: Yuxiang Yang <yangyx22@xxxxxxxxxxxxxxxxxxxxx>
Reported-by: Ao Wang <wangao@xxxxxxxxxx>
Reported-by: Xuewei Feng <fengxw06@xxxxxxx>
Reported-by: Qi Li <qli01@xxxxxxxxxxxxxxx>
Reported-by: Ke Xu <xuke@xxxxxxxxxxxxxxx>
Assisted-by: GLM:GLM-5.1
Signed-off-by: Yizhou Zhao <zhaoyz24@xxxxxxxxxxxxxxxxxxxxx>
---
 net/9p/trans_rdma.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/9p/trans_rdma.c b/net/9p/trans_rdma.c
index aa5bd74..ea49b15 100644
--- a/net/9p/trans_rdma.c
+++ b/net/9p/trans_rdma.c
@@ -541,7 +541,7 @@ rdma_create_trans(struct p9_client *client, struct fs_context *fc)
 		return -ENOMEM;
 
 	/* Create the RDMA CM ID */
-	rdma->cm_id = rdma_create_id(&init_net, p9_cm_event_handler, client,
+	rdma->cm_id = rdma_create_id(current->nsproxy->net_ns, p9_cm_event_handler, client,
 				     RDMA_PS_TCP, IB_QPT_RC);
 	if (IS_ERR(rdma->cm_id))
 		goto error;
-- 
2.43.0