[PATCH 6.1 0104/1146] ovl: remove privs in ovl_copyfile()

Greg Kroah-Hartman
2022-12-28T15:11:56Z

From: Amir Goldstein <amir73il@gmail.com>

[ Upstream commit b306e90ffabdaa7e3b3350dbcd19b7663e71ab17 ]

Underlying fs doesn't remove privs because copy_range/remap_range are
called with privileged mounter credentials.

This fixes some failures in fstest generic/673.

Fixes: 8ede205541ff ("ovl: add reflink/copyfile/dedup support")
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/overlayfs/file.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index a1a22f58ba18..755a11c63596 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -567,14 +567,23 @@ static loff_t ovl_copyfile(struct file *file_in, loff_t pos_in,
const struct cred *old_cred;
loff_t ret;

+ inode_lock(inode_out);
+ if (op != OVL_DEDUPE) {
+ /* Update mode */
+ ovl_copyattr(inode_out);
+ ret = file_remove_privs(file_out);
+ if (ret)
+ goto out_unlock;
+ }
+
ret = ovl_real_fdget(file_out, &real_out);
if (ret)
- return ret;
+ goto out_unlock;

ret = ovl_real_fdget(file_in, &real_in);
if (ret) {
fdput(real_out);
- return ret;
+ goto out_unlock;
}

old_cred = ovl_override_creds(file_inode(file_out)->i_sb);
@@ -603,6 +612,9 @@ static loff_t ovl_copyfile(struct file *file_in, loff_t pos_in,
fdput(real_in);
fdput(real_out);

+out_unlock:
+ inode_unlock(inode_out);
+
return ret;
}

--
2.35.1