diff options
| author | Vinicius Costa Gomes <vinicius.gomes@intel.com> | 2024-11-14 11:52:23 +0300 |
|---|---|---|
| committer | Amir Goldstein <amir73il@gmail.com> | 2024-11-15 10:55:39 +0300 |
| commit | c5b28fc161c5402da2e10cc11637c2dff727ac23 (patch) | |
| tree | 06fc8b4a355cc63db9705792e814dc5892e2d626 | |
| parent | 711747e204ead127235aa41b350e518e92a87fcc (diff) | |
| download | linux-c5b28fc161c5402da2e10cc11637c2dff727ac23.tar.xz | |
ovl: Optimize override/revert creds
Use override_creds_light() in ovl_override_creds() and
revert_creds_light() in ovl_revert_creds().
The _light() functions do not change the 'usage' of the credentials in
question, as they refer to the credentials associated with the
mounter, which have a longer lifetime.
In ovl_setup_cred_for_create(), do not need to modify the mounter
credentials (returned by override_creds_light()) 'usage' counter.
Add a warning to verify that we are indeed working with the mounter
credentials (stored in the superblock). Failure in this assumption
means that creds may leak.
Suggested-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
| -rw-r--r-- | fs/overlayfs/dir.c | 10 | ||||
| -rw-r--r-- | fs/overlayfs/util.c | 4 |
2 files changed, 11 insertions, 3 deletions
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c index 4b0bb7a91d37..5cf529482a8a 100644 --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -573,7 +573,15 @@ static const struct cred *ovl_setup_cred_for_create(struct dentry *dentry, put_cred(override_cred); return ERR_PTR(err); } - put_cred(override_creds(override_cred)); + + /* + * Caller is going to match this with revert_creds_light() and drop + * referenec on the returned creds. + * We must be called with creator creds already, otherwise we risk + * leaking creds. + */ + old_cred = override_creds_light(override_cred); + WARN_ON_ONCE(old_cred != ovl_creds(dentry->d_sb)); return override_cred; } diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c index 9408046f4f41..3bb107471fb4 100644 --- a/fs/overlayfs/util.c +++ b/fs/overlayfs/util.c @@ -65,12 +65,12 @@ const struct cred *ovl_override_creds(struct super_block *sb) { struct ovl_fs *ofs = OVL_FS(sb); - return override_creds(ofs->creator_cred); + return override_creds_light(ofs->creator_cred); } void ovl_revert_creds(const struct cred *old_cred) { - revert_creds(old_cred); + revert_creds_light(old_cred); } /* |