kernel/linux.git/fs/lockd/host.c, branch v6.1.168

lockd: move from strlcpy with unused retval to strscpy

2022-09-26T18:02:20+00:00

Follow the advice of the below link and prefer 'strscpy' in this subsystem. Conversion is 1:1 because the return value is not used. Generated by a coccinelle script. Link: https://lore.kernel.org/r/CAHk-=wgfRnXz0W3D37d01q3JFkr_i_uTL=V6A6G1oUZcprmknw@mail.gmail.com/ Signed-off-by: Wolfram Sang Signed-off-by: Chuck Lever

fs/lockd: convert comma to semicolon

2020-12-16T12:57:37+00:00

Replace a comma between expression statements by a semicolon. Signed-off-by: Zheng Yongjun Signed-off-by: Trond Myklebust

lockd: don't use interval-based rebinding over TCP

2020-12-02T19:05:54+00:00

NLM uses an interval-based rebinding, i.e. it clears the transport's binding under certain conditions if more than 60 seconds have elapsed since the connection was last bound. This rebinding is not necessary for an autobind RPC client over a connection-oriented protocol like TCP. It can also cause problems: it is possible for nlm_bind_host() to clear XPRT_BOUND whilst a connection worker is in the middle of trying to reconnect, after it had already been checked in xprt_connect(). When the connection worker notices that XPRT_BOUND has been cleared under it, in xs_tcp_finish_connecting(), that results in: xs_tcp_setup_socket: connect returned unhandled error -107 Worse, it's possible that the two can get into lockstep, resulting in the same behaviour repeated indefinitely, with the above error every 300 seconds, without ever recovering, and the connection never being established. This has been seen in practice, with a large number of NLM client tasks, following a server restart. The existing callers of nlm_bind_host & nlm_rebind_host should not need to force the rebind, for TCP, so restrict the interval-based rebinding to UDP only. For TCP, we will still rebind when needed, e.g. on timeout, and connection error (including closure), since connection-related errors on an existing connection, ECONNREFUSED when trying to connect, and rpc_check_timeout(), already unconditionally clear XPRT_BOUND. To avoid having to add the fix, and explanation, to both nlm_bind_host() and nlm_rebind_host(), remove the duplicate code from the former, and have it call the latter. Drop the dprintk, which adds no value over a trace. Signed-off-by: Calum Mackay Fixes: 35f5a422ce1a ("SUNRPC: new interface to force an RPC rebind") Signed-off-by: Trond Myklebust

NFSv4.1: Don't rebind to the same source port when reconnecting to the server

2019-11-04T02:28:45+00:00

NFSv2, v3 and NFSv4 servers often have duplicate replay caches that look at the source port when deciding whether or not an RPC call is a replay of a previous call. This requires clients to perform strange TCP gymnastics in order to ensure that when they reconnect to the server, they bind to the same source port. NFSv4.1 and NFSv4.2 have sessions that provide proper replay semantics, that do not look at the source port of the connection. This patch therefore ensures they can ignore the rebind requirement. Signed-off-by: Trond Myklebust

lockd: Store the lockd client credential in struct nlm_host

2019-04-26T21:51:23+00:00

When we create a new lockd client, we want to be able to pass the correct credential of the process that created the struct nlm_host. Signed-off-by: Trond Myklebust Signed-off-by: Anna Schumaker

SUNRPC: Cache cred of process creating the rpc_client

2019-04-26T20:00:48+00:00

When converting kuids to AUTH_UNIX creds, etc we will want to use the same user namespace as the process that created the rpc client. Signed-off-by: Trond Myklebust Signed-off-by: Anna Schumaker

NFS: fix mount/umount race in nlmclnt.

2019-03-19T02:39:34+00:00

If the last NFSv3 unmount from a given host races with a mount from the same host, we can destroy an nlm_host that is still in use. Specifically nlmclnt_lookup_host() can increment h_count on an nlm_host that nlmclnt_release_host() has just successfully called refcount_dec_and_test() on. Once nlmclnt_lookup_host() drops the mutex, nlm_destroy_host_lock() will be called to destroy the nlmclnt which is now in use again. The cause of the problem is that the dec_and_test happens outside the locked region. This is easily fixed by using refcount_dec_and_mutex_lock(). Fixes: 8ea6ecc8b075 ("lockd: Create client-side nlm_host cache") Cc: stable@vger.kernel.org (v2.6.38+) Signed-off-by: NeilBrown Signed-off-by: Trond Myklebust

lockd: fix access beyond unterminated strings in prints

2018-10-29T20:58:04+00:00

printk format used %*s instead of %.*s, so hostname_len does not limit the number of bytes accessed from hostname. Signed-off-by: Amir Goldstein Cc: stable@vger.kernel.org Signed-off-by: J. Bruce Fields

lockd: Fix server refcounting

2018-01-24T22:33:57+00:00

The server shouldn't actually delete the struct nlm_host until it hits the garbage collector. In order to make that work correctly with the refcount API, we can bump the refcount by one, and then use refcount_dec_if_one() in the garbage collector. Signed-off-by: Trond Myklebust Acked-by: J. Bruce Fields

lockd: convert nsm_handle.sm_count from atomic_t to refcount_t

2018-01-15T04:06:29+00:00

atomic_t variables are currently used to implement reference counters with the following properties: - counter is initialized to 1 using atomic_set() - a resource is freed upon counter reaching zero - once counter reaches zero, its further increments aren't allowed - counter schema uses basic atomic operations (set, inc, inc_not_zero, dec_and_test, etc.) Such atomic variables should be converted to a newly provided refcount_t type and API that prevents accidental counter overflows and underflows. This is important since overflows and underflows can lead to use-after-free situation and be exploitable. The variable nsm_handle.sm_count is used as pure reference counter. Convert it to refcount_t and fix up the operations. **Important note for maintainers: Some functions from refcount_t API defined in lib/refcount.c have different memory ordering guarantees than their atomic counterparts. The full comparison can be seen in https://lkml.org/lkml/2017/11/15/57 and it is hopefully soon in state to be merged to the documentation tree. Normally the differences should not matter since refcount_t provides enough guarantees to satisfy the refcounting use cases, but in some rare cases it might matter. Please double check that you don't have some undocumented memory guarantees for this variable usage. For the nsm_handle.sm_count it might make a difference in following places: - nsm_release(): decrement in refcount_dec_and_lock() only provides RELEASE ordering, control dependency on success and holds a spin lock on success vs. fully ordered atomic counterpart. No change for the spin lock guarantees. Suggested-by: Kees Cook Reviewed-by: David Windsor Reviewed-by: Hans Liljestrand Signed-off-by: Elena Reshetova Signed-off-by: Trond Myklebust