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| author | Miklos Szeredi <mszeredi@redhat.com> | 2016-06-15 15:18:59 +0300 |
|---|---|---|
| committer | Miklos Szeredi <mszeredi@redhat.com> | 2016-06-15 15:18:59 +0300 |
| commit | d0e13f5bbe4be7c8f27736fc40503dcec04b7de0 (patch) | |
| tree | c63531a963fbe14bb83641c22185e8c5f72812c9 /fs/overlayfs | |
| parent | 30402c8949934fbaca07d9c20074d0d7a5a8385f (diff) | |
| download | linux-d0e13f5bbe4be7c8f27736fc40503dcec04b7de0.tar.xz | |
ovl: fix uid/gid when creating over whiteout
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: 3fe6e52f0626 ("ovl: override creds with the ones from the superblock mounter")
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'fs/overlayfs')
| -rw-r--r-- | fs/overlayfs/dir.c | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c index 22f0253a3567..c2a6b0894022 100644 --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -405,12 +405,21 @@ 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); } |