From patchwork Mon Aug 29 17:03:49 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Konstantin Meskhidze (A)" X-Patchwork-Id: 12958224 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 48C89ECAAD2 for ; Mon, 29 Aug 2022 17:04:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231303AbiH2REv (ORCPT ); Mon, 29 Aug 2022 13:04:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37808 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231276AbiH2REY (ORCPT ); Mon, 29 Aug 2022 13:04:24 -0400 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E036A9C2D1; Mon, 29 Aug 2022 10:04:20 -0700 (PDT) Received: from fraeml715-chm.china.huawei.com (unknown [172.18.147.206]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4MGcBv1Phdz687Wr; Tue, 30 Aug 2022 01:00:39 +0800 (CST) Received: from lhrpeml500004.china.huawei.com (7.191.163.9) by fraeml715-chm.china.huawei.com (10.206.15.34) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 29 Aug 2022 19:04:18 +0200 Received: from mscphis00759.huawei.com (10.123.66.134) by lhrpeml500004.china.huawei.com (7.191.163.9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Mon, 29 Aug 2022 18:04:17 +0100 From: Konstantin Meskhidze To: CC: , , , , , , , Subject: [PATCH v7 06/18] landlock: refactor landlock_add_rule syscall Date: Tue, 30 Aug 2022 01:03:49 +0800 Message-ID: <20220829170401.834298-7-konstantin.meskhidze@huawei.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220829170401.834298-1-konstantin.meskhidze@huawei.com> References: <20220829170401.834298-1-konstantin.meskhidze@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.123.66.134] X-ClientProxiedBy: mscpeml100002.china.huawei.com (7.188.26.75) To lhrpeml500004.china.huawei.com (7.191.163.9) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Modifies landlock_add_rule syscall to support new rule types in future Landlock versions. Adds add_rule_path_beneath() helper to support current filesystem rules. Signed-off-by: Konstantin Meskhidze --- Changes since v6: * None Changes since v5: * Refactors syscall landlock_add_rule() and add_rule_path_beneath() helper to make argument check ordering consistent and get rid of partial revertings in following patches. * Rolls back refactoring base_test.c seltest. * Formats code with clang-format-14. Changes since v4: * Refactors add_rule_path_beneath() and landlock_add_rule() functions to optimize code usage. * Refactors base_test.c seltest: adds LANDLOCK_RULE_PATH_BENEATH rule type in landlock_add_rule() call. Changes since v3: * Split commit. * Refactors landlock_add_rule syscall. --- security/landlock/syscalls.c | 99 +++++++++++++++++++----------------- 1 file changed, 52 insertions(+), 47 deletions(-) -- 2.25.1 diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c index 6593381466e0..28acc4cef3e8 100644 --- a/security/landlock/syscalls.c +++ b/security/landlock/syscalls.c @@ -274,6 +274,47 @@ static int get_path_from_fd(const s32 fd, struct path *const path) return err; } +static int add_rule_path_beneath(struct landlock_ruleset *const ruleset, + const void __user *const rule_attr) +{ + struct landlock_path_beneath_attr path_beneath_attr; + struct path path; + int res, err; + u32 mask; + + /* Copies raw user space buffer, only one type for now. */ + res = copy_from_user(&path_beneath_attr, rule_attr, + sizeof(path_beneath_attr)); + if (res) + return -EFAULT; + + /* + * Informs about useless rule: empty allowed_access (i.e. deny rules) + * are ignored in path walks. + */ + if (!path_beneath_attr.allowed_access) + return -ENOMSG; + /* + * Checks that allowed_access matches the @ruleset constraints + * (ruleset->access_masks[0] is automatically upgraded to 64-bits). + */ + mask = landlock_get_fs_access_mask(ruleset, 0); + if ((path_beneath_attr.allowed_access | mask) != mask) + return -EINVAL; + + /* Gets and checks the new rule. */ + err = get_path_from_fd(path_beneath_attr.parent_fd, &path); + if (err) + return err; + + /* Imports the new rule. */ + err = landlock_append_fs_rule(ruleset, &path, + path_beneath_attr.allowed_access); + path_put(&path); + + return err; +} + /** * sys_landlock_add_rule - Add a new rule to a ruleset * @@ -292,13 +333,14 @@ static int get_path_from_fd(const s32 fd, struct path *const path) * * - EOPNOTSUPP: Landlock is supported by the kernel but disabled at boot time; * - EINVAL: @flags is not 0, or inconsistent access in the rule (i.e. - * &landlock_path_beneath_attr.allowed_access is not a subset of the - * ruleset handled accesses); + * &landlock_path_beneath_attr.allowed_access is not a subset of the rule's + * accesses); * - ENOMSG: Empty accesses (e.g. &landlock_path_beneath_attr.allowed_access); * - EBADF: @ruleset_fd is not a file descriptor for the current thread, or a * member of @rule_attr is not a file descriptor as expected; * - EBADFD: @ruleset_fd is not a ruleset file descriptor, or a member of - * @rule_attr is not the expected file descriptor type; + * @rule_attr is not the expected file descriptor type (e.g. file open + * without O_PATH); * - EPERM: @ruleset_fd has no write access to the underlying ruleset; * - EFAULT: @rule_attr inconsistency. */ @@ -306,10 +348,8 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd, const enum landlock_rule_type, rule_type, const void __user *const, rule_attr, const __u32, flags) { - struct landlock_path_beneath_attr path_beneath_attr; - struct path path; struct landlock_ruleset *ruleset; - int res, err; + int err; if (!landlock_initialized) return -EOPNOTSUPP; @@ -323,49 +363,14 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd, if (IS_ERR(ruleset)) return PTR_ERR(ruleset); - if (rule_type != LANDLOCK_RULE_PATH_BENEATH) { + switch (rule_type) { + case LANDLOCK_RULE_PATH_BENEATH: + err = add_rule_path_beneath(ruleset, rule_attr); + break; + default: err = -EINVAL; - goto out_put_ruleset; - } - - /* Copies raw user space buffer, only one type for now. */ - res = copy_from_user(&path_beneath_attr, rule_attr, - sizeof(path_beneath_attr)); - if (res) { - err = -EFAULT; - goto out_put_ruleset; + break; } - - /* - * Informs about useless rule: empty allowed_access (i.e. deny rules) - * are ignored in path walks. - */ - if (!path_beneath_attr.allowed_access) { - err = -ENOMSG; - goto out_put_ruleset; - } - /* - * Checks that allowed_access matches the @ruleset constraints - * (ruleset->access_masks[0] is automatically upgraded to 64-bits). - */ - if ((path_beneath_attr.allowed_access | - landlock_get_fs_access_mask(ruleset, 0)) != - landlock_get_fs_access_mask(ruleset, 0)) { - err = -EINVAL; - goto out_put_ruleset; - } - - /* Gets and checks the new rule. */ - err = get_path_from_fd(path_beneath_attr.parent_fd, &path); - if (err) - goto out_put_ruleset; - - /* Imports the new rule. */ - err = landlock_append_fs_rule(ruleset, &path, - path_beneath_attr.allowed_access); - path_put(&path); - -out_put_ruleset: landlock_put_ruleset(ruleset); return err; }