From mboxrd@z Thu Jan 1 00:00:00 1970 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 A63EBC05027 for ; Tue, 14 Feb 2023 10:20:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231610AbjBNKT7 (ORCPT ); Tue, 14 Feb 2023 05:19:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57194 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229681AbjBNKT6 (ORCPT ); Tue, 14 Feb 2023 05:19:58 -0500 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3D2876A7C; Tue, 14 Feb 2023 02:19:57 -0800 (PST) Received: from lhrpeml500004.china.huawei.com (unknown [172.18.147.201]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4PGHCT6XHGz67K2K; Tue, 14 Feb 2023 18:15:33 +0800 (CST) Received: from [10.123.123.126] (10.123.123.126) 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 15.1.2507.17; Tue, 14 Feb 2023 10:19:54 +0000 Message-ID: <2d25dbd5-f7b1-ba32-d971-36c86870661e@huawei.com> Date: Tue, 14 Feb 2023 13:19:53 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.4.1 Subject: Re: [PATCH v9 08/12] landlock: Add network rules and TCP hooks support Content-Language: ru To: =?UTF-8?Q?Micka=c3=abl_Sala=c3=bcn?= CC: , , , , , , References: <20230116085818.165539-1-konstantin.meskhidze@huawei.com> <20230116085818.165539-9-konstantin.meskhidze@huawei.com> <5198f456-91f5-5c65-76c2-45b82ccb05eb@digikod.net> From: "Konstantin Meskhidze (A)" In-Reply-To: <5198f456-91f5-5c65-76c2-45b82ccb05eb@digikod.net> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.123.123.126] X-ClientProxiedBy: lhrpeml500001.china.huawei.com (7.191.163.213) To lhrpeml500004.china.huawei.com (7.191.163.9) X-CFilter-Loop: Reflected Precedence: bulk List-ID: 2/10/2023 8:39 PM, Mickaël Salaün пишет: > > On 16/01/2023 09:58, Konstantin Meskhidze wrote: >> This commit adds network rules support in the ruleset management >> helpers and the landlock_create_ruleset syscall. >> Refactor user space API to support network actions. Add new network >> access flags, network rule and network attributes. Increment Landlock >> ABI version. Expand access_masks_t to u32 to be sure network access >> rights can be stored. Implement socket_bind() and socket_connect() >> LSM hooks, which enable to restrict TCP socket binding and connection >> to specific ports. >> >> Signed-off-by: Konstantin Meskhidze >> --- >> >> Changes since v8: >> * Squashes commits. >> * Refactors commit message. >> * Changes UAPI port field to __be16. >> * Changes logic of bind/connect hooks with AF_UNSPEC families. >> * Adds address length checking. >> * Minor fixes. >> >> Changes since v7: >> * Squashes commits. >> * Increments ABI version to 4. >> * Refactors commit message. >> * Minor fixes. >> >> Changes since v6: >> * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask() >> because it OR values. >> * Makes landlock_add_net_access_mask() more resilient incorrect values. >> * Refactors landlock_get_net_access_mask(). >> * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use >> LANDLOCK_NUM_ACCESS_FS as value. >> * Updates access_masks_t to u32 to support network access actions. >> * Refactors landlock internal functions to support network actions with >> landlock_key/key_type/id types. >> >> Changes since v5: >> * Gets rid of partial revert from landlock_add_rule >> syscall. >> * Formats code with clang-format-14. >> >> Changes since v4: >> * Refactors landlock_create_ruleset() - splits ruleset and >> masks checks. >> * Refactors landlock_create_ruleset() and landlock mask >> setters/getters to support two rule types. >> * Refactors landlock_add_rule syscall add_rule_path_beneath >> function by factoring out get_ruleset_from_fd() and >> landlock_put_ruleset(). >> >> Changes since v3: >> * Splits commit. >> * Adds network rule support for internal landlock functions. >> * Adds set_mask and get_mask for network. >> * Adds rb_root root_net_port. > > [...] > >> +static int check_socket_access(const struct landlock_ruleset *const domain, >> + struct sockaddr *address, __be16 port, >> + access_mask_t access_request) >> +{ >> + bool allowed = false; >> + layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_NET] = {}; >> + const struct landlock_rule *rule; >> + access_mask_t handled_access; >> + const struct landlock_id id = { >> + .key.data = port, >> + .type = LANDLOCK_KEY_NET_PORT, >> + }; >> + >> + if (WARN_ON_ONCE(!domain)) >> + return 0; >> + if (WARN_ON_ONCE(domain->num_layers < 1)) >> + return -EACCES; >> + >> + switch (address->sa_family) { >> + case AF_UNSPEC: >> + /* >> + * Connecting to an address with AF_UNSPEC dissolves the TCP >> + * association, which have the same effect as closing the >> + * connection while retaining the socket object (i.e., the file >> + * descriptor). As for dropping privileges, closing >> + * connections is always allowed. >> + */ >> + if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP) >> + return 0; >> + >> + /* >> + * For compatibility reason, accept AF_UNSPEC for bind >> + * accesses (mapped to AF_INET) only if the address is >> + * INADDR_ANY (cf. __inet_bind). Checking the address is >> + * required to not wrongfully return -EACCES instead of >> + * -EAFNOSUPPORT. >> + */ >> + if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) { >> + const struct sockaddr_in *const sockaddr = >> + (struct sockaddr_in *)address; >> + >> + if (sockaddr->sin_addr.s_addr != htonl(INADDR_ANY)) >> + return -EAFNOSUPPORT; >> + } >> + >> + fallthrough; >> + case AF_INET: >> +#if IS_ENABLED(CONFIG_IPV6) >> + case AF_INET6: >> +#endif >> + rule = landlock_find_rule(domain, id); >> + handled_access = landlock_init_layer_masks( >> + domain, access_request, &layer_masks, >> + LANDLOCK_KEY_NET_PORT); >> + allowed = landlock_unmask_layers(rule, handled_access, >> + &layer_masks, >> + ARRAY_SIZE(layer_masks)); >> + >> + fallthrough; > > You can remove this fallthrough. Got it. > > >> + } >> + return allowed ? 0 : -EACCES; >> +} >> + >> +static u16 get_port(const struct sockaddr *const address) >> +{ >> + /* Gets port value in host byte order. */ >> + switch (address->sa_family) { >> + case AF_UNSPEC: >> + case AF_INET: { >> + const struct sockaddr_in *const sockaddr = >> + (struct sockaddr_in *)address; >> + return sockaddr->sin_port; >> + } >> +#if IS_ENABLED(CONFIG_IPV6) >> + case AF_INET6: { >> + const struct sockaddr_in6 *const sockaddr_ip6 = >> + (struct sockaddr_in6 *)address; >> + return sockaddr_ip6->sin6_port; >> + } >> +#endif >> + } >> + WARN_ON_ONCE(1); >> + return 0; >> +} >> + >> +static int hook_socket_bind(struct socket *sock, struct sockaddr *address, >> + int addrlen) >> +{ >> + int ret; >> + const struct landlock_ruleset *const dom = >> + landlock_get_current_domain(); > > landlock_get_current_domain() should only be called by a > get_current_net_domain() wrapper that checks if the current domain > handles network accesses. See get_current_fs_domain() in patch 2/12. > Ok. Thanks for a tip. > >> + >> + if (!dom) >> + return 0; >> + >> + /* Check if it's a TCP socket. */ >> + if (sock->type != SOCK_STREAM) >> + return 0; >> + >> + ret = check_addrlen(address, addrlen); >> + if (ret) >> + return ret; >> + >> + return check_socket_access(dom, address, get_port(address), >> + LANDLOCK_ACCESS_NET_BIND_TCP); >> +} > .