NFS: if ATTR_KILL_S*ID bits are set, then skip mode change

If the ATTR_KILL_S*ID bits are set then any mode change is only for clearing
the setuid/setgid bits.  For NFS, skip the mode change and let the server
handle it.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 6c22453d77ae..6d2f2a3eccf8 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -357,6 +357,10 @@ nfs_setattr(struct dentry *dentry, struct iattr *attr)
 
         nfs_inc_stats(inode, NFSIOS_VFSSETATTR);
 
+        /* skip mode change if it's just for clearing setuid/setgid */
+        if (attr->ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
+                attr->ia_valid &= ~ATTR_MODE;
+
         if (attr->ia_valid & ATTR_SIZE) {
                 if (!S_ISREG(inode->i_mode) || attr->ia_size == i_size_read(inode))
                         attr->ia_valid &= ~ATTR_SIZE;