From patchwork Fri Oct 21 15:26:36 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: 13014940 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 E95C7C4332F for ; Fri, 21 Oct 2022 15:27:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230347AbiJUP1V (ORCPT ); Fri, 21 Oct 2022 11:27:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45692 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230341AbiJUP1F (ORCPT ); Fri, 21 Oct 2022 11:27:05 -0400 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 191AB24BAAB; Fri, 21 Oct 2022 08:27:04 -0700 (PDT) Received: from frapeml100006.china.huawei.com (unknown [172.18.147.206]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4Mv7b32kkMz67yhs; Fri, 21 Oct 2022 23:25:51 +0800 (CST) Received: from lhrpeml500004.china.huawei.com (7.191.163.9) by frapeml100006.china.huawei.com (7.182.85.201) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 21 Oct 2022 17:27:01 +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 15.1.2375.31; Fri, 21 Oct 2022 16:27:00 +0100 From: Konstantin Meskhidze To: CC: , , , , , Subject: [PATCH v8 04/12] landlock: Move unmask_layers() and init_layer_masks() Date: Fri, 21 Oct 2022 23:26:36 +0800 Message-ID: <20221021152644.155136-5-konstantin.meskhidze@huawei.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20221021152644.155136-1-konstantin.meskhidze@huawei.com> References: <20221021152644.155136-1-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: This patch moves unmask_layers() and init_layer_masks() helpers to ruleset.c to share with landlock network implementation in following commits. Signed-off-by: Konstantin Meskhidze --- Changes since v7: * Refactors commit message. Changes since v6: * Moves get_handled_accesses() helper from ruleset.c back to fs.c, cause it's not used in coming network commits. Changes since v5: * Splits commit. * Moves init_layer_masks() and get_handled_accesses() helpers to ruleset.c and makes then non-static. * Formats code with clang-format-14. --- security/landlock/fs.c | 103 ------------------------------------ security/landlock/ruleset.c | 102 +++++++++++++++++++++++++++++++++++ security/landlock/ruleset.h | 20 +++++++ 3 files changed, 122 insertions(+), 103 deletions(-) -- 2.25.1 diff --git a/security/landlock/fs.c b/security/landlock/fs.c index 710cfa1306de..240e42a8f788 100644 --- a/security/landlock/fs.c +++ b/security/landlock/fs.c @@ -226,60 +226,6 @@ find_rule(const struct landlock_ruleset *const domain, return rule; } -/* - * @layer_masks is read and may be updated according to the access request and - * the matching rule. - * - * Returns true if the request is allowed (i.e. relevant layer masks for the - * request are empty). - */ -static inline bool -unmask_layers(const struct landlock_rule *const rule, - const access_mask_t access_request, - layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS]) -{ - size_t layer_level; - - if (!access_request || !layer_masks) - return true; - if (!rule) - return false; - - /* - * An access is granted if, for each policy layer, at least one rule - * encountered on the pathwalk grants the requested access, - * regardless of its position in the layer stack. We must then check - * the remaining layers for each inode, from the first added layer to - * the last one. When there is multiple requested accesses, for each - * policy layer, the full set of requested accesses may not be granted - * by only one rule, but by the union (binary OR) of multiple rules. - * E.g. /a/b + /a => /a/b - */ - for (layer_level = 0; layer_level < rule->num_layers; layer_level++) { - const struct landlock_layer *const layer = - &rule->layers[layer_level]; - const layer_mask_t layer_bit = BIT_ULL(layer->level - 1); - const unsigned long access_req = access_request; - unsigned long access_bit; - bool is_empty; - - /* - * Records in @layer_masks which layer grants access to each - * requested access. - */ - is_empty = true; - for_each_set_bit(access_bit, &access_req, - ARRAY_SIZE(*layer_masks)) { - if (layer->access & BIT_ULL(access_bit)) - (*layer_masks)[access_bit] &= ~layer_bit; - is_empty = is_empty && !(*layer_masks)[access_bit]; - } - if (is_empty) - return true; - } - return false; -} - /* * Allows access to pseudo filesystems that will never be mountable (e.g. * sockfs, pipefs), but can still be reachable through @@ -303,55 +249,6 @@ get_handled_accesses(const struct landlock_ruleset *const domain) return access_dom & LANDLOCK_MASK_ACCESS_FS; } -/** - * init_layer_masks - Initialize layer masks from an access request - * - * Populates @layer_masks such that for each access right in @access_request, - * the bits for all the layers are set where this access right is handled. - * - * @domain: The domain that defines the current restrictions. - * @access_request: The requested access rights to check. - * @layer_masks: The layer masks to populate. - * - * Returns: An access mask where each access right bit is set which is handled - * in any of the active layers in @domain. - */ -static inline access_mask_t -init_layer_masks(const struct landlock_ruleset *const domain, - const access_mask_t access_request, - layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS]) -{ - access_mask_t handled_accesses = 0; - size_t layer_level; - - memset(layer_masks, 0, sizeof(*layer_masks)); - /* An empty access request can happen because of O_WRONLY | O_RDWR. */ - if (!access_request) - return 0; - - /* Saves all handled accesses per layer. */ - for (layer_level = 0; layer_level < domain->num_layers; layer_level++) { - const unsigned long access_req = access_request; - unsigned long access_bit; - - for_each_set_bit(access_bit, &access_req, - ARRAY_SIZE(*layer_masks)) { - /* - * Artificially handles all initially denied by default - * access rights. - */ - if (BIT_ULL(access_bit) & - (landlock_get_fs_access_mask(domain, layer_level) | - ACCESS_INITIALLY_DENIED)) { - (*layer_masks)[access_bit] |= - BIT_ULL(layer_level); - handled_accesses |= BIT_ULL(access_bit); - } - } - } - return handled_accesses; -} - /* * Check that a destination file hierarchy has more restrictions than a source * file hierarchy. This is only used for link and rename actions. diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c index 961ffe0c709e..02ab14439c43 100644 --- a/security/landlock/ruleset.c +++ b/security/landlock/ruleset.c @@ -572,3 +572,105 @@ landlock_find_rule(const struct landlock_ruleset *const ruleset, } return NULL; } + +/* + * @layer_masks is read and may be updated according to the access request and + * the matching rule. + * + * Returns true if the request is allowed (i.e. relevant layer masks for the + * request are empty). + */ +bool unmask_layers(const struct landlock_rule *const rule, + const access_mask_t access_request, + layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS]) +{ + size_t layer_level; + + if (!access_request || !layer_masks) + return true; + if (!rule) + return false; + + /* + * An access is granted if, for each policy layer, at least one rule + * encountered on the pathwalk grants the requested access, + * regardless of its position in the layer stack. We must then check + * the remaining layers for each inode, from the first added layer to + * the last one. When there is multiple requested accesses, for each + * policy layer, the full set of requested accesses may not be granted + * by only one rule, but by the union (binary OR) of multiple rules. + * E.g. /a/b + /a => /a/b + */ + for (layer_level = 0; layer_level < rule->num_layers; layer_level++) { + const struct landlock_layer *const layer = + &rule->layers[layer_level]; + const layer_mask_t layer_bit = BIT_ULL(layer->level - 1); + const unsigned long access_req = access_request; + unsigned long access_bit; + bool is_empty; + + /* + * Records in @layer_masks which layer grants access to each + * requested access. + */ + is_empty = true; + for_each_set_bit(access_bit, &access_req, + ARRAY_SIZE(*layer_masks)) { + if (layer->access & BIT_ULL(access_bit)) + (*layer_masks)[access_bit] &= ~layer_bit; + is_empty = is_empty && !(*layer_masks)[access_bit]; + } + if (is_empty) + return true; + } + return false; +} + +/** + * init_layer_masks - Initialize layer masks from an access request + * + * Populates @layer_masks such that for each access right in @access_request, + * the bits for all the layers are set where this access right is handled. + * + * @domain: The domain that defines the current restrictions. + * @access_request: The requested access rights to check. + * @layer_masks: The layer masks to populate. + * + * Returns: An access mask where each access right bit is set which is handled + * in any of the active layers in @domain. + */ +access_mask_t +init_layer_masks(const struct landlock_ruleset *const domain, + const access_mask_t access_request, + layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS]) +{ + access_mask_t handled_accesses = 0; + size_t layer_level; + + memset(layer_masks, 0, sizeof(*layer_masks)); + /* An empty access request can happen because of O_WRONLY | O_RDWR. */ + if (!access_request) + return 0; + + /* Saves all handled accesses per layer. */ + for (layer_level = 0; layer_level < domain->num_layers; layer_level++) { + const unsigned long access_req = access_request; + unsigned long access_bit; + + for_each_set_bit(access_bit, &access_req, + ARRAY_SIZE(*layer_masks)) { + /* + * Artificially handles all initially denied by default + * access rights. + */ + if (BIT_ULL(access_bit) & + (landlock_get_fs_access_mask(domain, layer_level) | + ACCESS_INITIALLY_DENIED)) { + (*layer_masks)[access_bit] |= + BIT_ULL(layer_level); + handled_accesses |= BIT_ULL(access_bit); + } + } + } + return handled_accesses; +} diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h index 608ab356bc3e..50baff4fcbb4 100644 --- a/security/landlock/ruleset.h +++ b/security/landlock/ruleset.h @@ -34,6 +34,16 @@ typedef u16 layer_mask_t; /* Makes sure all layers can be checked. */ static_assert(BITS_PER_TYPE(layer_mask_t) >= LANDLOCK_MAX_NUM_LAYERS); +/* + * All access rights that are denied by default whether they are handled or not + * by a ruleset/layer. This must be ORed with all ruleset->fs_access_masks[] + * entries when we need to get the absolute handled access masks. + */ +/* clang-format off */ +#define ACCESS_INITIALLY_DENIED ( \ + LANDLOCK_ACCESS_FS_REFER) +/* clang-format on */ + /** * struct landlock_layer - Access rights for a given layer */ @@ -246,4 +256,14 @@ landlock_get_fs_access_mask(const struct landlock_ruleset *const ruleset, LANDLOCK_SHIFT_ACCESS_FS) & LANDLOCK_MASK_ACCESS_FS; } + +bool unmask_layers(const struct landlock_rule *const rule, + const access_mask_t access_request, + layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS]); + +access_mask_t +init_layer_masks(const struct landlock_ruleset *const domain, + const access_mask_t access_request, + layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS]); + #endif /* _SECURITY_LANDLOCK_RULESET_H */