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Biederman" , Amir Goldstein , Randy Dunlap , Stephen Smalley , linux-unionfs@vger.kernel.org, linux-doc@vger.kernel.org, kernel-team@android.com Subject: [PATCH v6 1/2] overlayfs: check CAP_DAC_READ_SEARCH before issuing exportfs_decode_fh Date: Mon, 5 Nov 2018 10:21:41 -0800 Message-Id: <20181105182146.233025-2-salyzyn@android.com> X-Mailer: git-send-email 2.19.1.930.g4563a0d9d0-goog In-Reply-To: <20181105182146.233025-1-salyzyn@android.com> References: <20181105182146.233025-1-salyzyn@android.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Assumption never checked, should fail if the mounter creds are not sufficient. Signed-off-by: Mark Salyzyn Cc: Miklos Szeredi Cc: Jonathan Corbet Cc: Vivek Goyal Cc: Eric W. Biederman Cc: Amir Goldstein Cc: Randy Dunlap Cc: Stephen Smalley Cc: linux-unionfs@vger.kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: kernel-team@android.com v5: - dependency of "overlayfs: override_creds=off option bypass creator_cred" v6: - rebase --- fs/overlayfs/namei.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c index efd372312ef1..aa012b6bd46e 100644 --- a/fs/overlayfs/namei.c +++ b/fs/overlayfs/namei.c @@ -163,6 +163,11 @@ struct dentry *ovl_decode_real_fh(struct ovl_fh *fh, struct vfsmount *mnt, if (!uuid_equal(&fh->uuid, &mnt->mnt_sb->s_uuid)) return NULL; + if (!capable(CAP_DAC_READ_SEARCH)) { + origin = ERR_PTR(-EPERM); + goto out; + } + bytes = (fh->len - offsetof(struct ovl_fh, fid)); real = exportfs_decode_fh(mnt, (struct fid *)fh->fid, bytes >> 2, (int)fh->type, -- 2.19.1.930.g4563a0d9d0-goog