[PATCH] nfsd: Return EPERM on utime/utimes/lutimes calls instead of EACCESS in some cases

zhengbin
2018-11-30T08:01:34Z

As the man(3) page for utime/utimes/lutimes, EPERM is returned
when the second parameter of utime/utimes/lutimes is not NULL,
the caller's effective UID does not match the owner of the file,
and the caller is not privileged.

However, in a NFS directory, it will return EACCESS(nfsd_setattr->
fh_verify->nfsd_permission), This patch fix this.

Signed-off-by: zhengbin <zhengbin13@huawei.com>
---
fs/nfsd/vfs.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index eb67098..9824e32 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -396,10 +396,23 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap,
bool get_write_count;
bool size_change = (iap->ia_valid & ATTR_SIZE);

- if (iap->ia_valid & (ATTR_ATIME | ATTR_MTIME | ATTR_SIZE))
+ if (iap->ia_valid & ATTR_SIZE) {
accmode |= NFSD_MAY_WRITE|NFSD_MAY_OWNER_OVERRIDE;
- if (iap->ia_valid & ATTR_SIZE)
ftype = S_IFREG;
+ }
+
+ /*
+ * If utimes(2) and friends are called with times not NULL, we should
+ * not set NFSD_MAY_WRITE bit. Otherwise fh_verify->nfsd_permission
+ * will return EACCESS, when the caller's effective UID does not match
+ * the owner of the file, and the caller is not privileged. In this
+ * situation, we should return EPERM(notify_change will return this).
+ */
+ if (iap->ia_valid & (ATTR_ATIME | ATTR_MTIME)) {
+ accmode |= NFSD_MAY_OWNER_OVERRIDE;
+ if (!(iap->ia_valid & (ATTR_ATIME_SET | ATTR_MTIME_SET)))
+ accmode |= NFSD_MAY_WRITE;
+ }

/* Callers that do fh_verify should do the fh_want_write: */
get_write_count = !fhp->fh_dentry;
--
2.7.4