Merge tag 'nfsd-6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux

Pull nfsd updates from Chuck Lever:
 "The bulk of the patches for this release are clean-ups and minor bug
  fixes.

  There is one significant revert to mention: support for RDMA Read
  operations in the server's RPC-over-RDMA transport implementation has
  been fixed so it waits for Read completion in a way that avoids tying
  up an nfsd thread. This prevents a possible DoS vector if an
  RPC-over-RDMA client should become unresponsive during RDMA Read
  operations.

  As always I am grateful to NFSD contributors, reviewers, and testers"

* tag 'nfsd-6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux: (56 commits)
  nfsd: rename nfsd_last_thread() to nfsd_destroy_serv()
  SUNRPC: discard sv_refcnt, and svc_get/svc_put
  svc: don't hold reference for poolstats, only mutex.
  SUNRPC: remove printk when back channel request not found
  svcrdma: Implement multi-stage Read completion again
  svcrdma: Copy construction of svc_rqst::rq_arg to rdma_read_complete()
  svcrdma: Add back svcxprt_rdma::sc_read_complete_q
  svcrdma: Add back svc_rdma_recv_ctxt::rc_pages
  svcrdma: Clean up comment in svc_rdma_accept()
  svcrdma: Remove queue-shortening warnings
  svcrdma: Remove pointer addresses shown in dprintk()
  svcrdma: Optimize svc_rdma_cc_init()
  svcrdma: De-duplicate completion ID initialization helpers
  svcrdma: Move the svc_rdma_cc_init() call
  svcrdma: Remove struct svc_rdma_read_info
  svcrdma: Update the synopsis of svc_rdma_read_special()
  svcrdma: Update the synopsis of svc_rdma_read_call_chunk()
  svcrdma: Update synopsis of svc_rdma_read_multiple_chunks()
  svcrdma: Update synopsis of svc_rdma_copy_inline_range()
  svcrdma: Update the synopsis of svc_rdma_read_data_item()
  ...

1 files changed, 42 insertions, 4 deletions

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 707ef21f275b..6e7e37192461 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1211,6 +1211,30 @@ out_nfserr:
 }
 
 /**
+ * nfsd_read_splice_ok - check if spliced reading is supported
+ * @rqstp: RPC transaction context
+ *
+ * Return values:
+ *   %true: nfsd_splice_read() may be used
+ *   %false: nfsd_splice_read() must not be used
+ *
+ * NFS READ normally uses splice to send data in-place. However the
+ * data in cache can change after the reply's MIC is computed but
+ * before the RPC reply is sent. To prevent the client from
+ * rejecting the server-computed MIC in this somewhat rare case, do
+ * not use splice with the GSS integrity and privacy services.
+ */
+bool nfsd_read_splice_ok(struct svc_rqst *rqstp)
+{
+	switch (svc_auth_flavor(rqstp)) {
+	case RPC_AUTH_GSS_KRB5I:
+	case RPC_AUTH_GSS_KRB5P:
+		return false;
+	}
+	return true;
+}
+
+/**
  * nfsd_read - Read data from a file
  * @rqstp: RPC transaction context
  * @fhp: file handle of file to be read
@@ -1239,7 +1263,7 @@ __be32 nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
 		return err;
 
 	file = nf->nf_file;
-	if (file->f_op->splice_read && test_bit(RQ_SPLICE_OK, &rqstp->rq_flags))
+	if (file->f_op->splice_read && nfsd_read_splice_ok(rqstp))
 		err = nfsd_splice_read(rqstp, fhp, file, offset, count, eof);
 	else
 		err = nfsd_iter_read(rqstp, fhp, file, offset, count, 0, eof);
@@ -2103,9 +2127,23 @@ static __be32 nfsd_buffered_readdir(struct file *file, struct svc_fh *fhp,
 	return cdp->err;
 }
 
-/*
- * Read entries from a directory.
- * The  NFSv3/4 verifier we ignore for now.
+/**
+ * nfsd_readdir - Read entries from a directory
+ * @rqstp: RPC transaction context
+ * @fhp: NFS file handle of directory to be read
+ * @offsetp: OUT: seek offset of final entry that was read
+ * @cdp: OUT: an eof error value
+ * @func: entry filler actor
+ *
+ * This implementation ignores the NFSv3/4 verifier cookie.
+ *
+ * NB: normal system calls hold file->f_pos_lock when calling
+ * ->iterate_shared and ->llseek, but nfsd_readdir() does not.
+ * Because the struct file acquired here is not visible to other
+ * threads, it's internal state does not need mutex protection.
+ *
+ * Returns nfs_ok on success, otherwise an nfsstat code is
+ * returned.
  */
 __be32
 nfsd_readdir(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t *offsetp,