From patchwork Sat Jun 3 19:15:18 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roberto Sassu X-Patchwork-Id: 13266263 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 37AD1C7EE24 for ; Sat, 3 Jun 2023 19:17:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229871AbjFCTRH (ORCPT ); Sat, 3 Jun 2023 15:17:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41168 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230081AbjFCTQy (ORCPT ); Sat, 3 Jun 2023 15:16:54 -0400 Received: from frasgout11.his.huawei.com (unknown [14.137.139.23]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3A1F2E72; Sat, 3 Jun 2023 12:16:44 -0700 (PDT) Received: from mail02.huawei.com (unknown [172.18.147.228]) by frasgout11.his.huawei.com (SkyGuard) with ESMTP id 4QYTqc0sXZz9xGhC; Sun, 4 Jun 2023 03:06:20 +0800 (CST) Received: from huaweicloud.com (unknown [10.204.63.22]) by APP1 (Coremail) with SMTP id LxC2BwCnCuZXkXtkAEoJAw--.3607S6; Sat, 03 Jun 2023 20:16:21 +0100 (CET) From: Roberto Sassu To: zohar@linux.ibm.com, dmitry.kasatkin@gmail.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, stephen.smalley.work@gmail.com, eparis@parisplace.org, casey@schaufler-ca.com Cc: linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, bpf@vger.kernel.org, kpsingh@kernel.org, keescook@chromium.org, nicolas.bouchinet@clip-os.org, Roberto Sassu Subject: [PATCH v11 4/4] evm: Support multiple LSMs providing an xattr Date: Sat, 3 Jun 2023 21:15:18 +0200 Message-Id: <20230603191518.1397490-5-roberto.sassu@huaweicloud.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230603191518.1397490-1-roberto.sassu@huaweicloud.com> References: <20230603191518.1397490-1-roberto.sassu@huaweicloud.com> MIME-Version: 1.0 X-CM-TRANSID: LxC2BwCnCuZXkXtkAEoJAw--.3607S6 X-Coremail-Antispam: 1UD129KBjvJXoWxGryktFy8JF1rur1rGr1kGrg_yoWrKF4Upa 98tas8Arn5JFy7Wr9aya18ua4SgrW8Cw1UK393JryjyFnIqr1IvryIyr15ur98WrW8JrnI yw4Yvw15C3W5t3DanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBSb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUAV Cq3wA2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0 rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVWUJVWUCwA2z4x0Y4vE2Ix0cI8IcVCY1x0267 AKxVWxJVW8Jr1l84ACjcxK6I8E87Iv67AKxVW8JVWxJwA2z4x0Y4vEx4A2jsIEc7CjxVAF wI0_Gr1j6F4UJwAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I 80ewAv7VC0I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCj c4AY6r1j6r4UM4x0Y48IcxkI7VAKI48JM4IIrI8v6xkF7I0E8cxan2IY04v7MxAIw28Icx kI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2Iq xVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVW8ZVWrXwCIc40Y0x0EwIxGrwCI42 IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVWxJVW8Jr1lIxAI cVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2js IEc7CjxVAFwI0_Gr1j6F4UJbIYCTnIWIevJa73UjIFyTuYvjxUFgAwUUUUU X-CM-SenderInfo: purev21wro2thvvxqx5xdzvxpfor3voofrz/1tbiAgARBF1jj4oUiwAAsz X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org From: Roberto Sassu Currently, evm_inode_init_security() processes a single LSM xattr from the array passed by security_inode_init_security(), and calculates the HMAC on it and other inode metadata. As the LSM infrastructure now can pass to EVM an array with multiple xattrs, scan them until the terminator (xattr name NULL), and calculate the HMAC on all of them. Also, double check that the xattrs array terminator is the first non-filled slot (obtained with lsm_get_xattr_slot()). Consumers of the xattrs array, such as the initxattrs() callbacks, rely on the terminator. Finally, change the name of the lsm_xattr parameter of evm_init_hmac() to xattrs, to reflect the new type of information passed. Signed-off-by: Roberto Sassu Reviewed-by: Mimi Zohar --- security/integrity/evm/evm.h | 4 +++- security/integrity/evm/evm_crypto.c | 11 +++++++++-- security/integrity/evm/evm_main.c | 29 +++++++++++++++++++++++++---- 3 files changed, 37 insertions(+), 7 deletions(-) diff --git a/security/integrity/evm/evm.h b/security/integrity/evm/evm.h index f8b8c5004fc..53bd7fec93f 100644 --- a/security/integrity/evm/evm.h +++ b/security/integrity/evm/evm.h @@ -46,6 +46,8 @@ struct evm_digest { char digest[IMA_MAX_DIGEST_SIZE]; } __packed; +int evm_protected_xattr(const char *req_xattr_name); + int evm_init_key(void); int evm_update_evmxattr(struct dentry *dentry, const char *req_xattr_name, @@ -58,7 +60,7 @@ int evm_calc_hash(struct dentry *dentry, const char *req_xattr_name, const char *req_xattr_value, size_t req_xattr_value_len, char type, struct evm_digest *data); -int evm_init_hmac(struct inode *inode, const struct xattr *xattr, +int evm_init_hmac(struct inode *inode, const struct xattr *xattrs, char *hmac_val); int evm_init_secfs(void); diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c index 033804f5a5f..0fdd382b58e 100644 --- a/security/integrity/evm/evm_crypto.c +++ b/security/integrity/evm/evm_crypto.c @@ -385,10 +385,11 @@ int evm_update_evmxattr(struct dentry *dentry, const char *xattr_name, return rc; } -int evm_init_hmac(struct inode *inode, const struct xattr *lsm_xattr, +int evm_init_hmac(struct inode *inode, const struct xattr *xattrs, char *hmac_val) { struct shash_desc *desc; + const struct xattr *xattr; desc = init_desc(EVM_XATTR_HMAC, HASH_ALGO_SHA1); if (IS_ERR(desc)) { @@ -396,7 +397,13 @@ int evm_init_hmac(struct inode *inode, const struct xattr *lsm_xattr, return PTR_ERR(desc); } - crypto_shash_update(desc, lsm_xattr->value, lsm_xattr->value_len); + for (xattr = xattrs; xattr->name != NULL; xattr++) { + if (!evm_protected_xattr(xattr->name)) + continue; + + crypto_shash_update(desc, xattr->value, xattr->value_len); + } + hmac_add_misc(desc, inode, EVM_XATTR_HMAC, hmac_val); kfree(desc); return 0; diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c index 475196ce712..e9441419a81 100644 --- a/security/integrity/evm/evm_main.c +++ b/security/integrity/evm/evm_main.c @@ -306,7 +306,7 @@ static int evm_protected_xattr_common(const char *req_xattr_name, return found; } -static int evm_protected_xattr(const char *req_xattr_name) +int evm_protected_xattr(const char *req_xattr_name) { return evm_protected_xattr_common(req_xattr_name, false); } @@ -870,14 +870,35 @@ int evm_inode_init_security(struct inode *inode, struct inode *dir, int *xattr_count) { struct evm_xattr *xattr_data; - struct xattr *evm_xattr; + struct xattr *xattr, *evm_xattr; + bool evm_protected_xattrs = false; int rc; - if (!(evm_initialized & EVM_INIT_HMAC) || !xattrs || - !evm_protected_xattr(xattrs->name)) + if (!(evm_initialized & EVM_INIT_HMAC) || !xattrs) + return 0; + + /* + * security_inode_init_security() makes sure that the xattrs array is + * contiguous, there is enough space for security.evm, and that there is + * a terminator at the end of the array. + */ + for (xattr = xattrs; xattr->name != NULL; xattr++) { + if (evm_protected_xattr(xattr->name)) + evm_protected_xattrs = true; + } + + /* EVM xattr not needed. */ + if (!evm_protected_xattrs) return 0; evm_xattr = lsm_get_xattr_slot(xattrs, xattr_count); + /* + * Array terminator (xattr name = NULL) must be the first non-filled + * xattr slot. + */ + WARN_ONCE(evm_xattr != xattr, + "%s: xattrs terminator is not the first non-filled slot\n", + __func__); xattr_data = kzalloc(sizeof(*xattr_data), GFP_NOFS); if (!xattr_data)