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 8E78BC761AF for ; Tue, 4 Apr 2023 09:31:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234275AbjDDJbT (ORCPT ); Tue, 4 Apr 2023 05:31:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34132 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234233AbjDDJbP (ORCPT ); Tue, 4 Apr 2023 05:31:15 -0400 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 96E5E1FD8; Tue, 4 Apr 2023 02:31:12 -0700 (PDT) Received: from lhrpeml500004.china.huawei.com (unknown [172.18.147.226]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4PrMsP4wKXz6J7Kk; Tue, 4 Apr 2023 17:29:13 +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 15.1.2507.23; Tue, 4 Apr 2023 10:31:09 +0100 Message-ID: <1f84d88f-9977-13a9-245a-c75cd3444b29@huawei.com> Date: Tue, 4 Apr 2023 12:31:08 +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 v10 09/13] landlock: Add network rules and TCP hooks support Content-Language: ru To: =?UTF-8?Q?Micka=c3=abl_Sala=c3=bcn?= CC: , , , , , , References: <20230323085226.1432550-1-konstantin.meskhidze@huawei.com> <20230323085226.1432550-10-konstantin.meskhidze@huawei.com> <468fbb05-6d72-3570-3453-b1f8bfdd5bc2@digikod.net> From: "Konstantin Meskhidze (A)" In-Reply-To: <468fbb05-6d72-3570-3453-b1f8bfdd5bc2@digikod.net> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.123.123.126] X-ClientProxiedBy: lhrpeml100003.china.huawei.com (7.191.160.210) To lhrpeml500004.china.huawei.com (7.191.163.9) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org 3/31/2023 8:24 PM, Mickaël Salaün пишет: > > On 23/03/2023 09:52, 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 v9: >> * Changes UAPI port field to __u64. >> * Moves shared code into check_socket_access(). >> * Adds get_raw_handled_net_accesses() and >> get_current_net_domain() helpers. >> * Minor fixes. >> >> 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. >> >> --- >> include/uapi/linux/landlock.h | 49 +++++ >> security/landlock/Kconfig | 1 + >> security/landlock/Makefile | 2 + >> security/landlock/limits.h | 6 +- >> security/landlock/net.c | 198 +++++++++++++++++++ >> security/landlock/net.h | 26 +++ >> security/landlock/ruleset.c | 52 ++++- >> security/landlock/ruleset.h | 63 +++++- >> security/landlock/setup.c | 2 + >> security/landlock/syscalls.c | 72 ++++++- >> tools/testing/selftests/landlock/base_test.c | 2 +- >> 11 files changed, 450 insertions(+), 23 deletions(-) >> create mode 100644 security/landlock/net.c >> create mode 100644 security/landlock/net.h > > [...] > >> diff --git a/security/landlock/net.c b/security/landlock/net.c > > [...] > >> +static int check_addrlen(const struct sockaddr *const address, int addrlen) > > const int addrlen Got it. > >> +{ >> + if (addrlen < offsetofend(struct sockaddr, sa_family)) >> + return -EINVAL; >> + switch (address->sa_family) { >> + case AF_UNSPEC: >> + case AF_INET: >> + if (addrlen < sizeof(struct sockaddr_in)) >> + return -EINVAL; >> + return 0; >> +#if IS_ENABLED(CONFIG_IPV6) >> + case AF_INET6: >> + if (addrlen < SIN6_LEN_RFC2133) >> + return -EINVAL; >> + return 0; >> +#endif >> + } >> + WARN_ON_ONCE(1); >> + return 0; >> +} >> + >> +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 ntohs(sockaddr->sin_port); > > Storing ports in big endian (in rulesets) would avoid converting them > every time the kernel checks a socket port. The above comment should > then be updated too. I thought we came to a conclusion to stick to host endianess and let kernel do the checks under the hood: https://lore.kernel.org/linux-security-module/278ab07f-7583-a4e0-3d37-1bacd091531d@digikod.net/ Did I misunderstand something? > > >> + } >> +#if IS_ENABLED(CONFIG_IPV6) >> + case AF_INET6: { >> + const struct sockaddr_in6 *const sockaddr_ip6 = >> + (struct sockaddr_in6 *)address; >> + return ntohs(sockaddr_ip6->sin6_port); >> + } >> +#endif >> + } >> + WARN_ON_ONCE(1); >> + return 0; >> +} >> + >> +static int check_socket_access(struct socket *sock, struct sockaddr *address, int addrlen, u16 port, >> + access_mask_t access_request) >> +{ >> + int ret; >> + 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, >> + }; >> + const struct landlock_ruleset *const domain = get_current_net_domain(); >> + >> + if (WARN_ON_ONCE(!domain)) >> + return 0; >> + if (WARN_ON_ONCE(domain->num_layers < 1)) >> + return -EACCES; >> + /* Check if it's a TCP socket. */ >> + if (sock->type != SOCK_STREAM) >> + return 0; >> + >> + ret = check_addrlen(address, addrlen); >> + if (ret) >> + return ret; >> + >> + 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)); >> + } >> + return allowed ? 0 : -EACCES; >> +} >> + >> +static int hook_socket_bind(struct socket *sock, struct sockaddr *address, >> + int addrlen) >> +{ >> + return check_socket_access(sock, address, addrlen, get_port(address), >> + LANDLOCK_ACCESS_NET_BIND_TCP); >> +} >> + >> +static int hook_socket_connect(struct socket *sock, struct sockaddr *address, >> + int addrlen) >> +{ >> + return check_socket_access(sock, address, addrlen, get_port(address), >> + LANDLOCK_ACCESS_NET_CONNECT_TCP); >> +} > > [...] > .