linux-kernel - [PATCH v1 8/9] fs/fuse: support idmapped ->set

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Date: Mon,  8 Jan 2024 13:08:23 +0100
From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@...onical.com>
To: mszeredi@...hat.com
Cc: brauner@...nel.org,
	stgraber@...raber.org,
	linux-fsdevel@...r.kernel.org,
	Seth Forshee <sforshee@...nel.org>,
	Miklos Szeredi <miklos@...redi.hu>,
	Amir Goldstein <amir73il@...il.com>,
	Bernd Schubert <bschubert@....com>,
	Alexander Mikhalitsyn <aleksandr.mikhalitsyn@...onical.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH v1 8/9] fs/fuse: support idmapped ->set_acl

It's just a matter of adjusting a permission check condition
for S_ISGID flag. All the rest is already handled in the generic
VFS code.

Notice that this permission check is the analog of what
we have in posix_acl_update_mode() generic helper, but
fuse doesn't use this helper as on the kernel side we don't
care about ensuring that POSIX ACL and CHMOD permissions are in sync
as it is a responsibility of a userspace daemon to handle that.
For the same reason we don't have a calls to posix_acl_chmod(),
while most of other filesystem do.

Cc: Christian Brauner <brauner@...nel.org>
Cc: Seth Forshee <sforshee@...nel.org>
Cc: Miklos Szeredi <miklos@...redi.hu>
Cc: Amir Goldstein <amir73il@...il.com>
Cc: Bernd Schubert <bschubert@....com>
Cc: <linux-fsdevel@...r.kernel.org>
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@...onical.com>
---
 fs/fuse/acl.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/fuse/acl.c b/fs/fuse/acl.c
index 3a3cd88bd3d7..727fe50e255e 100644
--- a/fs/fuse/acl.c
+++ b/fs/fuse/acl.c
@@ -144,8 +144,8 @@ int fuse_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 		 * be stripped.
 		 */
 		if (fc->posix_acl &&
-		    !vfsgid_in_group_p(i_gid_into_vfsgid(&nop_mnt_idmap, inode)) &&
-		    !capable_wrt_inode_uidgid(&nop_mnt_idmap, inode, CAP_FSETID))
+		    !vfsgid_in_group_p(i_gid_into_vfsgid(idmap, inode)) &&
+		    !capable_wrt_inode_uidgid(idmap, inode, CAP_FSETID))
 			extra_flags |= FUSE_SETXATTR_ACL_KILL_SGID;
 
 		ret = fuse_setxattr(inode, name, value, size, 0, extra_flags);
-- 
2.34.1