shinys000114/linux
1
0
Fork 0
mirror of https://github.com/hardkernel/linux.git synced 2026-06-09 04:10:18 +09:00
Code Issues Packages Projects Releases Wiki Activity

ovl: fix uid/gid when creating over whiteout

Browse Source 
[ Upstream commit d0e13f5bbe ]

Fix a regression when creating a file over a whiteout.  The new
file/directory needs to use the current fsuid/fsgid, not the ones from the
mounter's credentials.

The refcounting is a bit tricky: prepare_creds() sets an original refcount,
override_creds() gets one more, which revert_cred() drops.  So

  1) we need to expicitly put the mounter's credentials when overriding
     with the updated one

  2) we need to put the original ref to the updated creds (and this can
     safely be done before revert_creds(), since we'll still have the ref
     from override_creds()).

Reported-by: Stephen Smalley <sds@tycho.nsa.gov>
Fixes: 3fe6e52f06 ("ovl: override creds with the ones from the superblock mounter")
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Sasha Levin (Microsoft) <sashal@kernel.org>
This commit is contained in:
Miklos Szeredi
2016-06-15 14:18:59 +02:00
committed by Greg Kroah-Hartman
parent df57807765
commit 54a07fff4b
1 changed files with 11 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

13
fs/overlayfs/dir.c
View File

@@ -408,12 +408,21 @@ static int ovl_create_or_link(struct dentry *dentry, int mode, dev_t rdev,
err = ovl_create_upper(dentry, inode, &stat, link, hardlink);
} else {
const struct cred *old_cred;
struct cred *override_cred;
old_cred = ovl_override_creds(dentry->d_sb);
err = ovl_create_over_whiteout(dentry, inode, &stat, link,
hardlink);
err = -ENOMEM;
override_cred = prepare_creds();
if (override_cred) {
override_cred->fsuid = old_cred->fsuid;
override_cred->fsgid = old_cred->fsgid;
put_cred(override_creds(override_cred));
put_cred(override_cred);
err = ovl_create_over_whiteout(dentry, inode, &stat,
link, hardlink);
}
revert_creds(old_cred);
}