From patchwork Fri Jul 8 16:19:41 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vivek Goyal X-Patchwork-Id: 9221377 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 6095560467 for ; Fri, 8 Jul 2016 16:22:32 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5038924DA2 for ; Fri, 8 Jul 2016 16:22:32 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4273B25221; Fri, 8 Jul 2016 16:22:32 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BD5CE24DA2 for ; Fri, 8 Jul 2016 16:22:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755972AbcGHQVy (ORCPT ); Fri, 8 Jul 2016 12:21:54 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33327 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755926AbcGHQUD (ORCPT ); Fri, 8 Jul 2016 12:20:03 -0400 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id EAE8BC0624DB; Fri, 8 Jul 2016 16:20:02 +0000 (UTC) Received: from horse.redhat.com (dhcp-25-69.bos.redhat.com [10.18.25.69]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u68GK2bY023134; Fri, 8 Jul 2016 12:20:02 -0400 Received: by horse.redhat.com (Postfix, from userid 10451) id 92CDC20600C; Fri, 8 Jul 2016 12:20:01 -0400 (EDT) From: Vivek Goyal To: miklos@szeredi.hu, sds@tycho.nsa.gov, pmoore@redhat.com, casey@schaufler-ca.com, linux-kernel@vger.kernel.org, linux-unionfs@vger.kernel.org, linux-security-module@vger.kernel.org Cc: dwalsh@redhat.com, dhowells@redhat.com, viro@ZenIV.linux.org.uk, vgoyal@redhat.com, linux-fsdevel@vger.kernel.org Subject: [PATCH 6/7] security, overlayfs: Provide hook to correctly label newly created files Date: Fri, 8 Jul 2016 12:19:41 -0400 Message-Id: <1467994782-26474-7-git-send-email-vgoyal@redhat.com> In-Reply-To: <1467994782-26474-1-git-send-email-vgoyal@redhat.com> References: <1467994782-26474-1-git-send-email-vgoyal@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Fri, 08 Jul 2016 16:20:03 +0000 (UTC) Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP During a new file creation we need to make sure new file is created with the right label. New file is created in upper/ so effectively file should get label as if task had created file in upper/. We switched to mounter's creds for actual file creation. Also if there is a whiteout present, then file will be created in work/ dir first and then renamed in upper. In none of the cases file will be labeled as we want it to be. This patch introduces a new hook dentry_create_files_as(), which determines the label/context dentry will get if it had been created by task in upper and modify passed set of creds appropriately. Caller makes use of these new creds for file creation. Signed-off-by: Vivek Goyal --- fs/overlayfs/dir.c | 10 ++++++++++ include/linux/lsm_hooks.h | 15 +++++++++++++++ include/linux/security.h | 12 ++++++++++++ security/security.c | 11 +++++++++++ 4 files changed, 48 insertions(+) diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c index 4cdeb74..f94872f 100644 --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -433,6 +433,15 @@ static int ovl_create_or_link(struct dentry *dentry, int mode, dev_t rdev, if (override_cred) { override_cred->fsuid = inode->i_uid; override_cred->fsgid = inode->i_gid; + if (!hardlink) { + err = security_dentry_create_files_as(dentry, + mode, &dentry->d_name, old_cred, + override_cred); + if (err) { + put_cred(override_cred); + goto out_revert_creds; + } + } put_cred(override_creds(override_cred)); put_cred(override_cred); @@ -443,6 +452,7 @@ static int ovl_create_or_link(struct dentry *dentry, int mode, dev_t rdev, err = ovl_create_over_whiteout(dentry, inode, &stat, link, hardlink); } +out_revert_creds: revert_creds(old_cred); if (!err) { struct inode *realinode = d_inode(ovl_dentry_upper(dentry)); diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index 84caead..95745fe 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -151,6 +151,16 @@ * @name name of the last path component used to create file * @ctx pointer to place the pointer to the resulting context in. * @ctxlen point to place the length of the resulting context. + * @dentry_create_files_as: + * Compute a context for a dentry as the inode is not yet available + * and set that context in passed in creds so that new files are + * created using that context. Context is calculated using the + * passed in creds and not the creds of the caller. + * @dentry dentry to use in calculating the context. + * @mode mode used to determine resource type. + * @name name of the last path component used to create file + * @old creds which should be used for context calculation + * @new creds to modify * * * Security hooks for inode operations. @@ -1375,6 +1385,10 @@ union security_list_options { int (*dentry_init_security)(struct dentry *dentry, int mode, struct qstr *name, void **ctx, u32 *ctxlen); + int (*dentry_create_files_as)(struct dentry *dentry, int mode, + struct qstr *name, + const struct cred *old, + struct cred *new); #ifdef CONFIG_SECURITY_PATH @@ -1675,6 +1689,7 @@ struct security_hook_heads { struct list_head sb_clone_mnt_opts; struct list_head sb_parse_opts_str; struct list_head dentry_init_security; + struct list_head dentry_create_files_as; #ifdef CONFIG_SECURITY_PATH struct list_head path_unlink; struct list_head path_mkdir; diff --git a/include/linux/security.h b/include/linux/security.h index 08d3191..23fb492 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -242,6 +242,10 @@ int security_sb_parse_opts_str(char *options, struct security_mnt_opts *opts); int security_dentry_init_security(struct dentry *dentry, int mode, struct qstr *name, void **ctx, u32 *ctxlen); +int security_dentry_create_files_as(struct dentry *dentry, int mode, + struct qstr *name, + const struct cred *old, + struct cred *new); int security_inode_alloc(struct inode *inode); void security_inode_free(struct inode *inode); @@ -600,6 +604,14 @@ static inline int security_dentry_init_security(struct dentry *dentry, return -EOPNOTSUPP; } +static inline int security_dentry_create_files_as(struct dentry *dentry, + int mode, struct qstr *name, + const struct cred *old, + struct cred *new) +{ + return 0; +} + static inline int security_inode_init_security(struct inode *inode, struct inode *dir, diff --git a/security/security.c b/security/security.c index 3321e31..38747d1 100644 --- a/security/security.c +++ b/security/security.c @@ -364,6 +364,15 @@ int security_dentry_init_security(struct dentry *dentry, int mode, } EXPORT_SYMBOL(security_dentry_init_security); +int security_dentry_create_files_as(struct dentry *dentry, int mode, + struct qstr *name, + const struct cred *old, struct cred *new) +{ + return call_int_hook(dentry_create_files_as, 0, dentry, mode, + name, old, new); +} +EXPORT_SYMBOL(security_dentry_create_files_as); + int security_inode_init_security(struct inode *inode, struct inode *dir, const struct qstr *qstr, const initxattrs initxattrs, void *fs_data) @@ -1614,6 +1623,8 @@ struct security_hook_heads security_hook_heads = { LIST_HEAD_INIT(security_hook_heads.sb_parse_opts_str), .dentry_init_security = LIST_HEAD_INIT(security_hook_heads.dentry_init_security), + .dentry_create_files_as = + LIST_HEAD_INIT(security_hook_heads.dentry_create_files_as), #ifdef CONFIG_SECURITY_PATH .path_unlink = LIST_HEAD_INIT(security_hook_heads.path_unlink), .path_mkdir = LIST_HEAD_INIT(security_hook_heads.path_mkdir),