linux-next.git/include/linux/sunrpc/clnt.h, branch master

SUNRPC: pin upper rpc_clnt across the TLS connect_worker

2026-07-08T18:07:19+00:00

The TLS connect path has a use-after-free: nothing pins the upper rpc_clnt across the delayed connect_worker. xs_connect() stores task->tk_client in sock_xprt::clnt as a raw pointer and queues the worker; for TLS-secured transports that worker is xs_tcp_tls_setup_socket(), which reads several fields out of the saved pointer (cl_timeout, cl_program, cl_prog, cl_vers, cl_cred, cl_stats) to construct the args for the inner handshake rpc_clnt. The xprt does not reference the rpc_clnt; the rpc_clnt references the xprt. xs_destroy() does cancel the connect_worker, but it runs only when the xprt's refcount drops to zero, which cannot happen until the rpc_clnt releases its cl_xprt reference in rpc_free_client_work(). When a TLS handshake fails fatally (for example, an mTLS mount whose client cert does not match the server), the connecting task is woken with -EACCES and exits, the mount caller invokes rpc_shutdown_client(), and the upper rpc_clnt is freed before the queued connect_worker fires. xs_tcp_tls_setup_socket() then dereferences the freed clnt, producing the refcount_t underflow Michael Nemanov reported. Take a reference on the upper rpc_clnt in xs_connect() for TLS transports via a new rpc_hold_client() helper, and drop it in the connect_worker's exit path with rpc_release_client(). The xprt_lock_connect() / xprt_unlock_connect() pairing already serialises xs_connect() with xs_tcp_tls_setup_socket(), so the take and release are balanced one-for-one. The non-TLS connect worker (xs_tcp_setup_socket) never reads sock_xprt::clnt, so leave that path alone and avoid the clnt-holds-xprt-holds-clnt cycle that would otherwise prevent xprt destruction. Reported-by: Michael Nemanov Closes: https://lore.kernel.org/linux-nfs/40e3d522-dfcf-4fc1-9c55-b5e81f1536d5@vastdata.com/ Fixes: 75eb6af7acdf ("SUNRPC: Add a TCP-with-TLS RPC transport class") Signed-off-by: Chuck Lever Tested-by: Michael Nemanov Reviewed-by: Michael Nemanov Signed-off-by: Anna Schumaker

NFS: Treat ENETUNREACH errors as fatal in containers

2025-03-21T16:44:19+00:00

Propagate the NFS_MOUNT_NETUNREACH_FATAL flag to work with the generic NFS client. If the flag is set, the client will receive ENETDOWN and ENETUNREACH errors from the RPC layer, and is expected to treat them as being fatal. Signed-off-by: Trond Myklebust Reviewed-by: Jeff Layton Tested-by: Jeff Layton Acked-by: Chuck Lever

SUNRPC: only put task on cl_tasks list after the RPC call slot is reserved.

2025-01-13T18:27:25+00:00

Under heavy write load, we've seen the cl_tasks list grows to millions of entries. Even though the list is extremely long, the system still runs fine until the user wants to get the information of all active RPC tasks by doing: When this happens, tasks_start acquires the cl_lock to walk the cl_tasks list, returning one entry at a time to the caller. The cl_lock is held until all tasks on this list have been processed. While the cl_lock is held, completed RPC tasks have to spin wait in rpc_task_release_client for the cl_lock. If there are millions of entries in the cl_tasks list it will take a long time before tasks_stop is called and the cl_lock is released. The spin wait tasks can use up all the available CPUs in the system, preventing other jobs to run, this causes the system to temporarily lock up. This patch fixes this problem by delaying inserting the RPC task on the cl_tasks list until the RPC call slot is reserved. This limits the length of the cl_tasks to the number of call slots available in the system. Signed-off-by: Dai Ngo Signed-off-by: Anna Schumaker

sunrpc: add a struct rpc_stats arg to rpc_create_args

2024-03-09T14:14:50+00:00

We want to be able to have our rpc stats handled in a per network namespace manner, so add an option to rpc_create_args to specify a different rpc_stats struct instead of using the one on the rpc_program. Signed-off-by: Josef Bacik Signed-off-by: Trond Myklebust

SUNRPC: Remove unused function rpc_clnt_xprt_switch_put()

2024-01-04T15:47:56+00:00

Reviewed-by: Jeff Layton Signed-off-by: Anna Schumaker

SUNRPC: Fix RPC client cleaned up the freed pipefs dentries

2023-11-01T19:40:44+00:00

RPC client pipefs dentries cleanup is in separated rpc_remove_pipedir() workqueue,which takes care about pipefs superblock locking. In some special scenarios, when kernel frees the pipefs sb of the current client and immediately alloctes a new pipefs sb, rpc_remove_pipedir function would misjudge the existence of pipefs sb which is not the one it used to hold. As a result, the rpc_remove_pipedir would clean the released freed pipefs dentries. To fix this issue, rpc_remove_pipedir should check whether the current pipefs sb is consistent with the original pipefs sb. This error can be catched by KASAN: ========================================================= [ 250.497700] BUG: KASAN: slab-use-after-free in dget_parent+0x195/0x200 [ 250.498315] Read of size 4 at addr ffff88800a2ab804 by task kworker/0:18/106503 [ 250.500549] Workqueue: events rpc_free_client_work [ 250.501001] Call Trace: [ 250.502880] kasan_report+0xb6/0xf0 [ 250.503209] ? dget_parent+0x195/0x200 [ 250.503561] dget_parent+0x195/0x200 [ 250.503897] ? __pfx_rpc_clntdir_depopulate+0x10/0x10 [ 250.504384] rpc_rmdir_depopulate+0x1b/0x90 [ 250.504781] rpc_remove_client_dir+0xf5/0x150 [ 250.505195] rpc_free_client_work+0xe4/0x230 [ 250.505598] process_one_work+0x8ee/0x13b0 ... [ 22.039056] Allocated by task 244: [ 22.039390] kasan_save_stack+0x22/0x50 [ 22.039758] kasan_set_track+0x25/0x30 [ 22.040109] __kasan_slab_alloc+0x59/0x70 [ 22.040487] kmem_cache_alloc_lru+0xf0/0x240 [ 22.040889] __d_alloc+0x31/0x8e0 [ 22.041207] d_alloc+0x44/0x1f0 [ 22.041514] __rpc_lookup_create_exclusive+0x11c/0x140 [ 22.041987] rpc_mkdir_populate.constprop.0+0x5f/0x110 [ 22.042459] rpc_create_client_dir+0x34/0x150 [ 22.042874] rpc_setup_pipedir_sb+0x102/0x1c0 [ 22.043284] rpc_client_register+0x136/0x4e0 [ 22.043689] rpc_new_client+0x911/0x1020 [ 22.044057] rpc_create_xprt+0xcb/0x370 [ 22.044417] rpc_create+0x36b/0x6c0 ... [ 22.049524] Freed by task 0: [ 22.049803] kasan_save_stack+0x22/0x50 [ 22.050165] kasan_set_track+0x25/0x30 [ 22.050520] kasan_save_free_info+0x2b/0x50 [ 22.050921] __kasan_slab_free+0x10e/0x1a0 [ 22.051306] kmem_cache_free+0xa5/0x390 [ 22.051667] rcu_core+0x62c/0x1930 [ 22.051995] __do_softirq+0x165/0x52a [ 22.052347] [ 22.052503] Last potentially related work creation: [ 22.052952] kasan_save_stack+0x22/0x50 [ 22.053313] __kasan_record_aux_stack+0x8e/0xa0 [ 22.053739] __call_rcu_common.constprop.0+0x6b/0x8b0 [ 22.054209] dentry_free+0xb2/0x140 [ 22.054540] __dentry_kill+0x3be/0x540 [ 22.054900] shrink_dentry_list+0x199/0x510 [ 22.055293] shrink_dcache_parent+0x190/0x240 [ 22.055703] do_one_tree+0x11/0x40 [ 22.056028] shrink_dcache_for_umount+0x61/0x140 [ 22.056461] generic_shutdown_super+0x70/0x590 [ 22.056879] kill_anon_super+0x3a/0x60 [ 22.057234] rpc_kill_sb+0x121/0x200 Fixes: 0157d021d23a ("SUNRPC: handle RPC client pipefs dentries by network namespace aware routines") Signed-off-by: felix Signed-off-by: Trond Myklebust

SUNRPC: Allow specification of TCP client connect timeout at setup

2023-08-24T17:24:15+00:00

When we create a TCP transport, the connect timeout parameters are currently fixed to be 90s. This is problematic in the pNFS flexfiles case, where we may have multiple mirrors, and we would like to fail over quickly to the next mirror if a data server is down. This patch adds the ability to specify the connection parameters at RPC client creation time. Signed-off-by: Trond Myklebust Signed-off-by: Anna Schumaker

NFS: add sysfs shutdown knob

2023-06-19T19:08:12+00:00

Within each nfs_server sysfs tree, add an entry named "shutdown". Writing 1 to this file will set the cl_shutdown bit on the rpc_clnt structs associated with that mount. If cl_shutdown is set, the task scheduler immediately returns -EIO for new tasks. Signed-off-by: Benjamin Coddington Signed-off-by: Trond Myklebust

NFS: Add sysfs links to sunrpc clients for nfs_clients

2023-06-19T19:04:13+00:00

For the general and state management nfs_client under each mount, create symlinks to their respective rpc_client sysfs entries. Signed-off-by: Benjamin Coddington Signed-off-by: Trond Myklebust

SUNRPC: Plumb an API for setting transport layer security

2023-06-19T16:16:59+00:00

Add an initial set of policies along with fields for upper layers to pass the requested policy down to the transport layer. Signed-off-by: Chuck Lever Reviewed-by: Jeff Layton Signed-off-by: Trond Myklebust