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 8EC3BC77B60 for ; Fri, 31 Mar 2023 17:30:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231232AbjCaRa6 (ORCPT ); Fri, 31 Mar 2023 13:30:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57286 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229967AbjCaRa5 (ORCPT ); Fri, 31 Mar 2023 13:30:57 -0400 Received: from smtp-bc0f.mail.infomaniak.ch (smtp-bc0f.mail.infomaniak.ch [IPv6:2001:1600:3:17::bc0f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 30A591D2F2 for ; Fri, 31 Mar 2023 10:30:54 -0700 (PDT) Received: from smtp-2-0001.mail.infomaniak.ch (unknown [10.5.36.108]) by smtp-2-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 4Pp6l121lpzMqR6x; Fri, 31 Mar 2023 19:30:53 +0200 (CEST) Received: from unknown by smtp-2-0001.mail.infomaniak.ch (Postfix) with ESMTPA id 4Pp6l0421rzMpqPr; Fri, 31 Mar 2023 19:30:52 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=digikod.net; s=20191114; t=1680283853; bh=48PJInuIliMAXlUYsxYTA8stA5dTlSv7rxJqGVVbJm4=; h=Date:Subject:From:To:Cc:References:In-Reply-To:From; b=UlROYnn69+qWcWv1EsSLuJYTfmenKH9SXEv6pejekdjFZwa3VhjL7xSPMFN/KWTEI AQ4s9M+g3LdW/DFxTQwmGp8lrOs8OH23mf2HvENS7DMa/AwfoY4fsAmh1MOT0QRlc2 19GpfgYox5d9q9KI/36zcA//b0FobwaiSwZ0V8z4= Message-ID: <01bdfa52-3bac-4703-6caa-d83ea5990c87@digikod.net> Date: Fri, 31 Mar 2023 19:30:51 +0200 MIME-Version: 1.0 User-Agent: Subject: Re: [PATCH v10 09/13] landlock: Add network rules and TCP hooks support Content-Language: en-US From: =?UTF-8?Q?Micka=c3=abl_Sala=c3=bcn?= To: Konstantin Meskhidze Cc: willemdebruijn.kernel@gmail.com, gnoack3000@gmail.com, linux-security-module@vger.kernel.org, netdev@vger.kernel.org, netfilter-devel@vger.kernel.org, yusongping@huawei.com, artem.kuzin@huawei.com References: <20230323085226.1432550-1-konstantin.meskhidze@huawei.com> <20230323085226.1432550-10-konstantin.meskhidze@huawei.com> <468fbb05-6d72-3570-3453-b1f8bfdd5bc2@digikod.net> In-Reply-To: <468fbb05-6d72-3570-3453-b1f8bfdd5bc2@digikod.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Infomaniak-Routing: alpha Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org On 31/03/2023 19:24, Mickaël Salaün wrote: > > 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 > >> +{ >> + 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. You can then return a __be16 type here and at least also use __be16 in check_socket_access(). > > >> + } >> +#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); >> +} > > [...]