From patchwork Thu Sep 30 18:59:10 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vivek Goyal X-Patchwork-Id: 12529241 X-Patchwork-Delegate: paul@paul-moore.com Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 978FFC433EF for ; Thu, 30 Sep 2021 19:00:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7E1CA61527 for ; Thu, 30 Sep 2021 19:00:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345651AbhI3TB4 (ORCPT ); Thu, 30 Sep 2021 15:01:56 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:58557 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344221AbhI3TBx (ORCPT ); Thu, 30 Sep 2021 15:01:53 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1633028406; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type; bh=2pk1sHN9IiEVNwyrRIA+irxwkyugDUv380w1Nyihj+s=; b=VxL/50e56jWL1T7A7TJkB64TMECsMvZWKjU1Hox7SMtpZfQ66TnMTuWe/bB710IwJ0wNWp gZ8ldYCfUpwHyxORyOdrS766oCODEAD3cwsmDSsw40nk3L+ULD24NW8+67I7w5rUbTrF8R yWdWpE57uXqgLJyNb0NMZPF+w+xSIaw= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-565-_9nMR1BVNSy7EKgIZIIGLA-1; Thu, 30 Sep 2021 15:00:01 -0400 X-MC-Unique: _9nMR1BVNSy7EKgIZIIGLA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 89E2F1007928; Thu, 30 Sep 2021 18:59:33 +0000 (UTC) Received: from horse.redhat.com (unknown [10.22.17.236]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0BDC260CD1; Thu, 30 Sep 2021 18:59:11 +0000 (UTC) Received: by horse.redhat.com (Postfix, from userid 10451) id D77042201CC; Thu, 30 Sep 2021 14:59:10 -0400 (EDT) Date: Thu, 30 Sep 2021 14:59:10 -0400 From: Vivek Goyal To: linux-security-module@vger.kernel.org, selinux@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, virtio-fs@redhat.com, casey@schaufler-ca.com, Miklos Szeredi , Daniel J Walsh , jlayton@kernel.org, idryomov@gmail.com, ceph-devel@vger.kernel.org, linux-nfs@vger.kernel.org, bfields@fieldses.org, chuck.lever@oracle.com, stephen.smalley.work@gmail.com Subject: [PATCH] security: Return xattr name from security_dentry_init_security() Message-ID: MIME-Version: 1.0 Content-Disposition: inline X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: selinux@vger.kernel.org Right now security_dentry_init_security() only supports single security label and is used by SELinux only. There are two users of of this hook, namely ceph and nfs. NFS does not care about xattr name. Ceph hardcodes the xattr name to security.selinux (XATTR_NAME_SELINUX). I am making changes to fuse/virtiofs to send security label to virtiofsd and I need to send xattr name as well. I also hardcoded the name of xattr to security.selinux. Stephen Smalley suggested that it probably is a good idea to modify security_dentry_init_security() to also return name of xattr so that we can avoid this hardcoding in the callers. This patch adds a new parameter "const char **xattr_name" to security_dentry_init_security() and LSM puts the name of xattr too if caller asked for it (xattr_name != NULL). Signed-off-by: Vivek Goyal Reviewed-by: Jeff Layton --- I have compile tested this patch. Don't know how to setup ceph and test it. Its a very simple change. Hopefully ceph developers can have a quick look at it. A similar attempt was made three years back. https://lore.kernel.org/linux-security-module/20180626080429.27304-1-zyan@redhat.com/T/ --- fs/ceph/xattr.c | 3 +-- fs/nfs/nfs4proc.c | 3 ++- include/linux/lsm_hook_defs.h | 3 ++- include/linux/lsm_hooks.h | 1 + include/linux/security.h | 6 ++++-- security/security.c | 7 ++++--- security/selinux/hooks.c | 6 +++++- 7 files changed, 19 insertions(+), 10 deletions(-) Index: redhat-linux/security/selinux/hooks.c =================================================================== --- redhat-linux.orig/security/selinux/hooks.c 2021-09-28 11:36:03.559785943 -0400 +++ redhat-linux/security/selinux/hooks.c 2021-09-30 14:01:05.869195347 -0400 @@ -2948,7 +2948,8 @@ static void selinux_inode_free_security( } static int selinux_dentry_init_security(struct dentry *dentry, int mode, - const struct qstr *name, void **ctx, + const struct qstr *name, + const char **xattr_name, void **ctx, u32 *ctxlen) { u32 newsid; @@ -2961,6 +2962,9 @@ static int selinux_dentry_init_security( if (rc) return rc; + if (xattr_name) + *xattr_name = XATTR_NAME_SELINUX; + return security_sid_to_context(&selinux_state, newsid, (char **)ctx, ctxlen); } Index: redhat-linux/security/security.c =================================================================== --- redhat-linux.orig/security/security.c 2021-08-16 10:39:28.518988836 -0400 +++ redhat-linux/security/security.c 2021-09-30 13:54:36.367195347 -0400 @@ -1052,11 +1052,12 @@ void security_inode_free(struct inode *i } int security_dentry_init_security(struct dentry *dentry, int mode, - const struct qstr *name, void **ctx, - u32 *ctxlen) + const struct qstr *name, + const char **xattr_name, void **ctx, + u32 *ctxlen) { return call_int_hook(dentry_init_security, -EOPNOTSUPP, dentry, mode, - name, ctx, ctxlen); + name, xattr_name, ctx, ctxlen); } EXPORT_SYMBOL(security_dentry_init_security); Index: redhat-linux/include/linux/lsm_hooks.h =================================================================== --- redhat-linux.orig/include/linux/lsm_hooks.h 2021-06-02 10:20:27.717485143 -0400 +++ redhat-linux/include/linux/lsm_hooks.h 2021-09-30 13:56:48.440195347 -0400 @@ -196,6 +196,7 @@ * @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 + * @xattr_name pointer to place the pointer to security xattr name * @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: Index: redhat-linux/include/linux/security.h =================================================================== --- redhat-linux.orig/include/linux/security.h 2021-08-16 10:39:28.484988836 -0400 +++ redhat-linux/include/linux/security.h 2021-09-30 13:59:00.288195347 -0400 @@ -317,8 +317,9 @@ int security_add_mnt_opt(const char *opt int len, void **mnt_opts); int security_move_mount(const struct path *from_path, const struct path *to_path); int security_dentry_init_security(struct dentry *dentry, int mode, - const struct qstr *name, void **ctx, - u32 *ctxlen); + const struct qstr *name, + const char **xattr_name, void **ctx, + u32 *ctxlen); int security_dentry_create_files_as(struct dentry *dentry, int mode, struct qstr *name, const struct cred *old, @@ -739,6 +740,7 @@ static inline void security_inode_free(s static inline int security_dentry_init_security(struct dentry *dentry, int mode, const struct qstr *name, + const char **xattr_name, void **ctx, u32 *ctxlen) { Index: redhat-linux/include/linux/lsm_hook_defs.h =================================================================== --- redhat-linux.orig/include/linux/lsm_hook_defs.h 2021-07-07 11:54:59.673549151 -0400 +++ redhat-linux/include/linux/lsm_hook_defs.h 2021-09-30 14:02:13.114195347 -0400 @@ -83,7 +83,8 @@ LSM_HOOK(int, 0, sb_add_mnt_opt, const c LSM_HOOK(int, 0, move_mount, const struct path *from_path, const struct path *to_path) LSM_HOOK(int, 0, dentry_init_security, struct dentry *dentry, - int mode, const struct qstr *name, void **ctx, u32 *ctxlen) + int mode, const struct qstr *name, const char **xattr_name, + void **ctx, u32 *ctxlen) LSM_HOOK(int, 0, dentry_create_files_as, struct dentry *dentry, int mode, struct qstr *name, const struct cred *old, struct cred *new) Index: redhat-linux/fs/nfs/nfs4proc.c =================================================================== --- redhat-linux.orig/fs/nfs/nfs4proc.c 2021-07-14 14:47:42.732842926 -0400 +++ redhat-linux/fs/nfs/nfs4proc.c 2021-09-30 14:06:02.249195347 -0400 @@ -127,7 +127,8 @@ nfs4_label_init_security(struct inode *d return NULL; err = security_dentry_init_security(dentry, sattr->ia_mode, - &dentry->d_name, (void **)&label->label, &label->len); + &dentry->d_name, NULL, + (void **)&label->label, &label->len); if (err == 0) return label; Index: redhat-linux/fs/ceph/xattr.c =================================================================== --- redhat-linux.orig/fs/ceph/xattr.c 2021-09-09 13:05:21.800611264 -0400 +++ redhat-linux/fs/ceph/xattr.c 2021-09-30 14:14:59.892195347 -0400 @@ -1311,7 +1311,7 @@ int ceph_security_init_secctx(struct den int err; err = security_dentry_init_security(dentry, mode, &dentry->d_name, - &as_ctx->sec_ctx, + &name, &as_ctx->sec_ctx, &as_ctx->sec_ctxlen); if (err < 0) { WARN_ON_ONCE(err != -EOPNOTSUPP); @@ -1335,7 +1335,6 @@ int ceph_security_init_secctx(struct den * It only supports single security module and only selinux has * dentry_init_security hook. */ - name = XATTR_NAME_SELINUX; name_len = strlen(name); err = ceph_pagelist_reserve(pagelist, 4 * 2 + name_len + as_ctx->sec_ctxlen);