From patchwork Tue Apr 27 11:37:28 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roberto Sassu X-Patchwork-Id: 12226547 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0E962C43603 for ; Tue, 27 Apr 2021 11:37:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D468C61002 for ; Tue, 27 Apr 2021 11:37:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236083AbhD0Lig (ORCPT ); Tue, 27 Apr 2021 07:38:36 -0400 Received: from frasgout.his.huawei.com ([185.176.79.56]:2926 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235426AbhD0Lie (ORCPT ); Tue, 27 Apr 2021 07:38:34 -0400 Received: from fraeml714-chm.china.huawei.com (unknown [172.18.147.226]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4FV0173tFYz71fd1; Tue, 27 Apr 2021 19:30:03 +0800 (CST) Received: from roberto-ThinkStation-P620.huawei.com (10.204.62.217) by fraeml714-chm.china.huawei.com (10.206.15.33) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Tue, 27 Apr 2021 13:37:47 +0200 From: Roberto Sassu To: , , , CC: , , , , , , Roberto Sassu Subject: [PATCH v3 2/6] security: Rewrite security_old_inode_init_security() Date: Tue, 27 Apr 2021 13:37:28 +0200 Message-ID: <20210427113732.471066-3-roberto.sassu@huawei.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210427113732.471066-1-roberto.sassu@huawei.com> References: <20210427113732.471066-1-roberto.sassu@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.204.62.217] X-ClientProxiedBy: lhreml751-chm.china.huawei.com (10.201.108.201) To fraeml714-chm.china.huawei.com (10.206.15.33) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org With upcoming changes, LSMs will be able to write their xattrs in the reserved slots. Boundary checking will be performed to ensure that LSMs don't write outside the passed xattr array. However, the xattr array is created only in security_inode_init_security() and not in security_old_inode_init_security(). Instead of duplicating the code for array allocation, this patch calls security_inode_init_security() from security_old_inode_init_security() and introduces a new callback, called security_initxattrs(), to copy the first element of the xattr array allocated by former function into the destination pointer provided by the latter function. Signed-off-by: Roberto Sassu --- security/security.c | 41 ++++++++++++++++++++++++++++++++++++++--- 1 file changed, 38 insertions(+), 3 deletions(-) diff --git a/security/security.c b/security/security.c index 7f14e59c4f8e..692a148ce764 100644 --- a/security/security.c +++ b/security/security.c @@ -1024,6 +1024,20 @@ int security_dentry_create_files_as(struct dentry *dentry, int mode, } EXPORT_SYMBOL(security_dentry_create_files_as); +static int security_initxattrs(struct inode *inode, const struct xattr *xattrs, + void *fs_info) +{ + struct xattr *dest = (struct xattr *)fs_info; + + if (!dest) + return 0; + + dest->name = xattrs->name; + dest->value = xattrs->value; + dest->value_len = xattrs->value_len; + return 0; +} + int security_inode_init_security(struct inode *inode, struct inode *dir, const struct qstr *qstr, const initxattrs initxattrs, void *fs_data) @@ -1053,8 +1067,14 @@ int security_inode_init_security(struct inode *inode, struct inode *dir, goto out; ret = initxattrs(inode, new_xattrs, fs_data); out: - for (xattr = new_xattrs; xattr->value != NULL; xattr++) + for (xattr = new_xattrs; xattr->value != NULL; xattr++) { + if (xattr == new_xattrs && initxattrs == &security_initxattrs && + !ret && fs_data != NULL) + continue; kfree(xattr->value); + } + if (initxattrs == &security_initxattrs) + return ret; return (ret == -EOPNOTSUPP) ? 0 : ret; } EXPORT_SYMBOL(security_inode_init_security); @@ -1071,10 +1091,25 @@ int security_old_inode_init_security(struct inode *inode, struct inode *dir, const struct qstr *qstr, const char **name, void **value, size_t *len) { + struct xattr xattr = { .name = NULL, .value = NULL, .value_len = 0 }; + struct xattr *lsm_xattr = (name && value && len) ? &xattr : NULL; + int ret; + if (unlikely(IS_PRIVATE(inode))) return -EOPNOTSUPP; - return call_int_hook(inode_init_security, -EOPNOTSUPP, inode, dir, - qstr, name, value, len); + + ret = security_inode_init_security(inode, dir, qstr, + security_initxattrs, lsm_xattr); + if (ret) + return ret; + + if (lsm_xattr) { + *name = lsm_xattr->name; + *value = lsm_xattr->value; + *len = lsm_xattr->value_len; + } + + return 0; } EXPORT_SYMBOL(security_old_inode_init_security);