From patchwork Thu Sep 5 15:05:33 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roberto Sassu X-Patchwork-Id: 13792533 Received: from frasgout12.his.huawei.com (frasgout12.his.huawei.com [14.137.139.154]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 144C084A2F; Thu, 5 Sep 2024 15:07:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=14.137.139.154 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725548869; cv=none; b=NG4sXDtlDL5r/oJnHx7yI2U2dgIdeuqfPFbN0vJ6v4NSzJhX/k8glUC1xJPI1oA3Xl6um2g8GNb7uP1kxXYVMvEfql0m4PPw/M1dCxpJsT7EJFihuKDvNsRlu28YVkIqmxrzD0Lu6XMT3isn6T5JF20pY6FblqXozdJN1qPj0YI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725548869; c=relaxed/simple; bh=6lpMHiZwFsdXCLmbmUpkhqTZ3pO3tetjpkHbtTN1dsU=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=uexJh3KOGCUWX11W/XKB3Q0E33o+0GhZSpvvH4sH+Urn6P+PVBybGw3ebMoYGmi2JUx7qp3lBWmRYe4j4PdzOERPB92c+xZeM/Lc2RXltPmq797I/u6eBqIOnq/OccNmXpq7x6yO3yHlGpxonuIE4ZnigulHWSp3GXh5UUJAiDY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=14.137.139.154 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.18.186.29]) by frasgout12.his.huawei.com (SkyGuard) with ESMTP id 4X02C05qsMz9v7JT; Thu, 5 Sep 2024 22:42:36 +0800 (CST) Received: from mail02.huawei.com (unknown [7.182.16.47]) by mail.maildlp.com (Postfix) with ESMTP id 3916C140516; Thu, 5 Sep 2024 23:07:28 +0800 (CST) Received: from huaweicloud.com (unknown [10.204.63.22]) by APP1 (Coremail) with SMTP id LxC2BwDXZy_myNlmE0tUAA--.16274S6; Thu, 05 Sep 2024 16:07:27 +0100 (CET) From: Roberto Sassu To: zohar@linux.ibm.com, dmitry.kasatkin@gmail.com, eric.snowberg@oracle.com, corbet@lwn.net, akpm@linux-foundation.org, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, shuah@kernel.org, mcoquelin.stm32@gmail.com, alexandre.torgue@foss.st.com Cc: linux-integrity@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kselftest@vger.kernel.org, wufan@linux.microsoft.com, pbrobinson@gmail.com, zbyszek@in.waw.pl, hch@lst.de, mjg59@srcf.ucam.org, pmatilai@redhat.com, jannh@google.com, dhowells@redhat.com, jikos@kernel.org, mkoutny@suse.com, ppavlu@suse.com, petr.vorel@gmail.com, mzerqung@0pointer.de, kgold@linux.ibm.com, Roberto Sassu Subject: [PATCH v5 04/14] digest_cache: Add securityfs interface Date: Thu, 5 Sep 2024 17:05:33 +0200 Message-Id: <20240905150543.3766895-5-roberto.sassu@huaweicloud.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240905150543.3766895-1-roberto.sassu@huaweicloud.com> References: <20240905150543.3766895-1-roberto.sassu@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-CM-TRANSID: LxC2BwDXZy_myNlmE0tUAA--.16274S6 X-Coremail-Antispam: 1UD129KBjvJXoW3AryUXw4xXFyfuF4fWFWUtwb_yoW3tF1kpa 9Ik3WUKr4xZFy3Cwn7A3W3CF1Fg390gF17Cws8Wry3Aay5uw1qva40yr1UZry5Xr4UZa4I yr4j9r1UZr4qqaDanT9S1TB71UUUUUDqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUPlb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUAV Cq3wA2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0 rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVW8JVW5JwA2z4x0Y4vE2Ix0cI8IcVCY1x0267 AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_Gr0_Cr1l84ACjcxK6I8E87Iv6xkF7I0E 14v26r4UJVWxJr1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrV C2j2WlYx0E2Ix0cI8IcVAFwI0_Jrv_JF1lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE 7xkEbVWUJVW8JwACjcxG0xvY0x0EwIxGrwACI402YVCY1x02628vn2kIc2xKxwCY1x0262 kKe7AKxVWrXVW3AwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s02 6c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_GF v_WrylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVW8JVW5JwCI42IY6xIIjxv20xvE c7CjxVAFwI0_Gr1j6F4UJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aV AFwI0_Gr0_Cr1lIxAIcVC2z280aVCY1x0267AKxVW8Jr0_Cr1UYxBIdaVFxhVjvjDU0xZF pf9x07jhXo7UUUUU= X-CM-SenderInfo: purev21wro2thvvxqx5xdzvxpfor3voofrz/1tbiAQARBGbZE3MK2gAAsb From: Roberto Sassu Create the digest_cache directory in /integrity, and add the default_path file, to let root change/read the default path (file or directory) from where digest lists are looked up. An RW semaphore prevents the default path from changing while digest_list_new() and read_default_path() are executed, so that those read a stable value. Multiple digest_list_new() and read_default_path() calls, instead, can be done in parallel, since they are the readers. Changing the default path does not affect digest caches created with the old path. Signed-off-by: Roberto Sassu --- security/integrity/digest_cache/Kconfig | 4 + security/integrity/digest_cache/Makefile | 2 +- security/integrity/digest_cache/internal.h | 4 + security/integrity/digest_cache/main.c | 10 +- security/integrity/digest_cache/secfs.c | 104 +++++++++++++++++++++ security/integrity/ima/ima_fs.c | 6 ++ 6 files changed, 128 insertions(+), 2 deletions(-) create mode 100644 security/integrity/digest_cache/secfs.c diff --git a/security/integrity/digest_cache/Kconfig b/security/integrity/digest_cache/Kconfig index 5fbec491237b..6e61089acbe2 100644 --- a/security/integrity/digest_cache/Kconfig +++ b/security/integrity/digest_cache/Kconfig @@ -15,3 +15,7 @@ config DIGEST_LIST_DEFAULT_PATH help Default path where the Integrity Digest Cache expects to find digest lists. + + It can be changed at run-time, by writing the new path to the + securityfs interface. Digest caches created with the old path are + not affected by the change. diff --git a/security/integrity/digest_cache/Makefile b/security/integrity/digest_cache/Makefile index 6a3f7cc6e106..c351186d4e1e 100644 --- a/security/integrity/digest_cache/Makefile +++ b/security/integrity/digest_cache/Makefile @@ -4,4 +4,4 @@ obj-$(CONFIG_INTEGRITY_DIGEST_CACHE) += digest_cache.o -digest_cache-y := main.o +digest_cache-y := main.o secfs.o diff --git a/security/integrity/digest_cache/internal.h b/security/integrity/digest_cache/internal.h index 54e118a2ef79..2fcfa9b4cf13 100644 --- a/security/integrity/digest_cache/internal.h +++ b/security/integrity/digest_cache/internal.h @@ -53,6 +53,7 @@ struct digest_cache_security { extern loff_t inode_sec_offset; extern char *default_path_str; +extern struct rw_semaphore default_path_sem; static inline struct digest_cache_security * digest_cache_get_security(const struct inode *inode) @@ -96,4 +97,7 @@ struct digest_cache *digest_cache_init(struct dentry *dentry, int __init digest_cache_do_init(const struct lsm_id *lsm_id, loff_t inode_offset); +/* secfs.c */ +int __init digest_cache_secfs_init(struct dentry *dir); + #endif /* _DIGEST_CACHE_INTERNAL_H */ diff --git a/security/integrity/digest_cache/main.c b/security/integrity/digest_cache/main.c index 188f1dcc880e..0e25f573166a 100644 --- a/security/integrity/digest_cache/main.c +++ b/security/integrity/digest_cache/main.c @@ -20,6 +20,9 @@ loff_t inode_sec_offset; char *default_path_str = CONFIG_DIGEST_LIST_DEFAULT_PATH; +/* Protects default_path_str. */ +struct rw_semaphore default_path_sem; + /** * digest_cache_alloc_init - Allocate and initialize a new digest cache * @path_str: Path string of the digest list @@ -305,9 +308,12 @@ struct digest_cache *digest_cache_get(struct dentry *dentry) /* Serialize accesses to inode for which the digest cache is used. */ mutex_lock(&dig_sec->dig_user_mutex); - if (!dig_sec->dig_user) + if (!dig_sec->dig_user) { + down_read(&default_path_sem); /* Consume extra reference from digest_cache_create(). */ dig_sec->dig_user = digest_cache_new(dentry); + up_read(&default_path_sem); + } if (dig_sec->dig_user) /* Increment ref. count for reference returned to the caller. */ @@ -404,6 +410,8 @@ static struct security_hook_list digest_cache_hooks[] __ro_after_init = { int __init digest_cache_do_init(const struct lsm_id *lsm_id, loff_t inode_offset) { + init_rwsem(&default_path_sem); + inode_sec_offset = inode_offset; digest_cache_cache = kmem_cache_create("digest_cache_cache", diff --git a/security/integrity/digest_cache/secfs.c b/security/integrity/digest_cache/secfs.c new file mode 100644 index 000000000000..3267b2a83430 --- /dev/null +++ b/security/integrity/digest_cache/secfs.c @@ -0,0 +1,104 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH + * + * Author: Roberto Sassu + * + * Implement the securityfs interface of the Integrity Digest Cache. + */ + +#define pr_fmt(fmt) "digest_cache: "fmt +#include + +#include "internal.h" + +static struct dentry *digest_cache_dir; +static struct dentry *default_path_dentry; + +/** + * write_default_path - Write default path + * @file: File descriptor of the securityfs file + * @buf: User space buffer + * @datalen: Amount of data to write + * @ppos: Current position in the file + * + * This function sets the new default path where digest lists can be found. + * Can be either a regular file or a directory. + * + * Return: Length of path written on success, a POSIX error code otherwise. + */ +static ssize_t write_default_path(struct file *file, const char __user *buf, + size_t datalen, loff_t *ppos) +{ + char *new_default_path_str; + + new_default_path_str = memdup_user_nul(buf, datalen); + if (IS_ERR(new_default_path_str)) + return PTR_ERR(new_default_path_str); + + down_write(&default_path_sem); + kfree_const(default_path_str); + default_path_str = new_default_path_str; + up_write(&default_path_sem); + return datalen; +} + +/** + * read_default_path - Read default path + * @file: File descriptor of the securityfs file + * @buf: User space buffer + * @datalen: Amount of data to read + * @ppos: Current position in the file + * + * This function returns the current default path where digest lists can be + * found. Can be either a regular file or a directory. + * + * Return: Length of path read on success, a POSIX error code otherwise. + */ +static ssize_t read_default_path(struct file *file, char __user *buf, + size_t datalen, loff_t *ppos) +{ + int ret; + + down_read(&default_path_sem); + ret = simple_read_from_buffer(buf, datalen, ppos, default_path_str, + strlen(default_path_str) + 1); + up_read(&default_path_sem); + return ret; +} + +static const struct file_operations default_path_ops = { + .open = generic_file_open, + .write = write_default_path, + .read = read_default_path, + .llseek = generic_file_llseek, +}; + +/** + * digest_cache_secfs_init - Initialize the securityfs interface + * @dir: Directory entry provided by the calling LSM + * + * This function initialize the securityfs interfaces, for configuration + * by user space. + * + * Initialize 'default_path', allowing user space to change the default + * directory where digest lists are searched. + * + * Return: Zero on success, a POSIX error code otherwise. + */ +int __init digest_cache_secfs_init(struct dentry *dir) +{ + digest_cache_dir = securityfs_create_dir("digest_cache", dir); + if (IS_ERR(digest_cache_dir)) + return PTR_ERR(digest_cache_dir); + + default_path_dentry = securityfs_create_file("default_path", 0660, + digest_cache_dir, NULL, + &default_path_ops); + if (IS_ERR(default_path_dentry)) { + securityfs_remove(digest_cache_dir); + return PTR_ERR(default_path_dentry); + } + + return 0; +} diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c index e4a79a9b2d58..be9e374e2cef 100644 --- a/security/integrity/ima/ima_fs.c +++ b/security/integrity/ima/ima_fs.c @@ -614,6 +614,12 @@ int __init ima_fs_init(void) goto out; } + if (IS_ENABLED(CONFIG_INTEGRITY_DIGEST_CACHE)) { + ret = digest_cache_secfs_init(integrity_dir); + if (ret < 0) + goto out; + } + return 0; out: securityfs_remove(ima_policy);