[PATCH 5.15 095/230] NFSD: COMMIT operations must not return NFS?ERR_INVAL

Greg Kroah-Hartman
2022-07-11T09:53:28Z

From: Chuck Lever <chuck.lever@oracle.com>

[ Upstream commit 3f965021c8bc38965ecb1924f570c4842b33d408 ]

Since, well, forever, the Linux NFS server's nfsd_commit() function
has returned nfserr_inval when the passed-in byte range arguments
were non-sensical.

However, according to RFC 1813 section 3.3.21, NFSv3 COMMIT requests
are permitted to return only the following non-zero status codes:

NFS3ERR_IO
NFS3ERR_STALE
NFS3ERR_BADHANDLE
NFS3ERR_SERVERFAULT

NFS3ERR_INVAL is not included in that list. Likewise, NFS4ERR_INVAL
is not listed in the COMMIT row of Table 6 in RFC 8881.

RFC 7530 does permit COMMIT to return NFS4ERR_INVAL, but does not
specify when it can or should be used.

Instead of dropping or failing a COMMIT request in a byte range that
is not supported, turn it into a valid request by treating one or
both arguments as zero. Offset zero means start-of-file, count zero
means until-end-of-file, so we only ever extend the commit range.
NFS servers are always allowed to commit more and sooner than
requested.

The range check is no longer bounded by NFS_OFFSET_MAX, but rather
by the value that is returned in the maxfilesize field of the NFSv3
FSINFO procedure or the NFSv4 maxfilesize file attribute.

Note that this change results in a new pynfs failure:

CMT4 st_commit.testCommitOverflow : RUNNING
CMT4 st_commit.testCommitOverflow : FAILURE
COMMIT with offset + count overflow should return
NFS4ERR_INVAL, instead got NFS4_OK

IMO the test is not correct as written: RFC 8881 does not allow the
COMMIT operation to return NFS4ERR_INVAL.

Reported-by: Dan Aloni <dan.aloni@vastdata.com>
Cc: stable@vger.kernel.org
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Bruce Fields <bfields@fieldses.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/nfsd/nfs3proc.c | 6 ------
fs/nfsd/vfs.c | 53 +++++++++++++++++++++++++++++++---------------
fs/nfsd/vfs.h | 4 ++--
3 files changed, 38 insertions(+), 25 deletions(-)

diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
index b540489ea240..936eebd4c56d 100644
--- a/fs/nfsd/nfs3proc.c
+++ b/fs/nfsd/nfs3proc.c
@@ -660,15 +660,9 @@ nfsd3_proc_commit(struct svc_rqst *rqstp)
argp->count,
(unsigned long long) argp->offset);

- if (argp->offset > NFS_OFFSET_MAX) {
- resp->status = nfserr_inval;
- goto out;
- }
-
fh_copy(&resp->fh, &argp->fh);
resp->status = nfsd_commit(rqstp, &resp->fh, argp->offset,
argp->count, resp->verf);
-out:
return rpc_success;
}

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index c8e3f81d110e..abfbb6953e89 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1108,42 +1108,61 @@ nfsd_write(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t offset,
}

#ifdef CONFIG_NFSD_V3
-/*
- * Commit all pending writes to stable storage.
+/**
+ * nfsd_commit - Commit pending writes to stable storage
+ * @rqstp: RPC request being processed
+ * @fhp: NFS filehandle
+ * @offset: raw offset from beginning of file
+ * @count: raw count of bytes to sync
+ * @verf: filled in with the server's current write verifier
*
- * Note: we only guarantee that data that lies within the range specified
- * by the 'offset' and 'count' parameters will be synced.
+ * Note: we guarantee that data that lies within the range specified
+ * by the 'offset' and 'count' parameters will be synced. The server
+ * is permitted to sync data that lies outside this range at the
+ * same time.
*
* Unfortunately we cannot lock the file to make sure we return full WCC
* data to the client, as locking happens lower down in the filesystem.
+ *
+ * Return values:
+ * An nfsstat value in network byte order.
*/
__be32
-nfsd_commit(struct svc_rqst *rqstp, struct svc_fh *fhp,
- loff_t offset, unsigned long count, __be32 *verf)
+nfsd_commit(struct svc_rqst *rqstp, struct svc_fh *fhp, u64 offset,
+ u32 count, __be32 *verf)
{
+ u64 maxbytes;
+ loff_t start, end;
struct nfsd_net *nn;
struct nfsd_file *nf;
- loff_t end = LLONG_MAX;
- __be32 err = nfserr_inval;
-
- if (offset < 0)
- goto out;
- if (count != 0) {
- end = offset + (loff_t)count - 1;
- if (end < offset)
- goto out;
- }
+ __be32 err;

err = nfsd_file_acquire(rqstp, fhp,
NFSD_MAY_WRITE|NFSD_MAY_NOT_BREAK_LEASE, &nf);
if (err)
goto out;
+
+ /*
+ * Convert the client-provided (offset, count) range to a
+ * (start, end) range. If the client-provided range falls
+ * outside the maximum file size of the underlying FS,
+ * clamp the sync range appropriately.
+ */
+ start = 0;
+ end = LLONG_MAX;
+ maxbytes = (u64)fhp->fh_dentry->d_sb->s_maxbytes;
+ if (offset < maxbytes) {
+ start = offset;
+ if (count && (offset + count - 1 < maxbytes))
+ end = offset + count - 1;
+ }
+
nn = net_generic(nf->nf_net, nfsd_net_id);
if (EX_ISSYNC(fhp->fh_export)) {
errseq_t since = READ_ONCE(nf->nf_file->f_wb_err);
int err2;

- err2 = vfs_fsync_range(nf->nf_file, offset, end, 0);
+ err2 = vfs_fsync_range(nf->nf_file, start, end, 0);
switch (err2) {
case 0:
nfsd_copy_boot_verifier(verf, nn);
diff --git a/fs/nfsd/vfs.h b/fs/nfsd/vfs.h
index b21b76e6b9a8..3cf5a8a13da5 100644
--- a/fs/nfsd/vfs.h
+++ b/fs/nfsd/vfs.h
@@ -73,8 +73,8 @@ __be32 do_nfsd_create(struct svc_rqst *, struct svc_fh *,
char *name, int len, struct iattr *attrs,
struct svc_fh *res, int createmode,
u32 *verifier, bool *truncp, bool *created);
-__be32 nfsd_commit(struct svc_rqst *, struct svc_fh *,
- loff_t, unsigned long, __be32 *verf);
+__be32 nfsd_commit(struct svc_rqst *rqst, struct svc_fh *fhp,
+ u64 offset, u32 count, __be32 *verf);
#endif /* CONFIG_NFSD_V3 */
#ifdef CONFIG_NFSD_V4
__be32 nfsd_getxattr(struct svc_rqst *rqstp, struct svc_fh *fhp,
--
2.35.1