From patchwork Mon Apr 8 09:39:27 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mikhail Ivanov X-Patchwork-Id: 13620893 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 51DEB5027B; Mon, 8 Apr 2024 09:40:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.187 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712569229; cv=none; b=FqE/an16NqeYH8fItQKulxnc6xyWb1oU+pxW/cEz7LNaCvKKApyq6GXBSQODU3aYlPwryA6vLf5VErZSTqM3kmXDkykdXEvSWSyoWRRJnRZgLoCLn15RzTWbuj36dgFI8dPGxJWDAIlFqF6OYj5Cf0f+Q5NjF9q0Mdg1LsVsVpM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712569229; c=relaxed/simple; bh=NY+y50EeFT3zDJgNa//Ls2FXBG/qKme14tasGwEfcRo=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=dma+0R1IpX+yKawIoNgF0n8fNK3KMVuKwM2lPxzINcOMWe53PKGQ3r9ayI0A6RBsCCtEomyoZZcrAziDZtBDXV/rF8FJo9WP8lpSkdkxUjvVYz1Dk4ogDE1Lw++zDBfshT7nnUkYZLvXrSrM4CQrlH9NkJKw0UwLpSu6ekzusbA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei-partners.com; spf=pass smtp.mailfrom=huawei-partners.com; arc=none smtp.client-ip=45.249.212.187 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei-partners.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei-partners.com Received: from mail.maildlp.com (unknown [172.19.163.252]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4VCkXC4RNWzwRZc; Mon, 8 Apr 2024 17:37:31 +0800 (CST) Received: from dggpemm500020.china.huawei.com (unknown [7.185.36.49]) by mail.maildlp.com (Postfix) with ESMTPS id DA2B818007D; Mon, 8 Apr 2024 17:40:24 +0800 (CST) Received: from mscphis02103.huawei.com (10.123.65.215) by dggpemm500020.china.huawei.com (7.185.36.49) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.35; Mon, 8 Apr 2024 17:40:22 +0800 From: Ivanov Mikhail To: CC: , , , , , , , Subject: [RFC PATCH v1 10/10] samples/landlock: Support socket protocol restrictions Date: Mon, 8 Apr 2024 17:39:27 +0800 Message-ID: <20240408093927.1759381-11-ivanov.mikhail1@huawei-partners.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240408093927.1759381-1-ivanov.mikhail1@huawei-partners.com> References: <20240408093927.1759381-1-ivanov.mikhail1@huawei-partners.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: mscpeml100003.china.huawei.com (10.199.174.67) To dggpemm500020.china.huawei.com (7.185.36.49) X-Patchwork-State: RFC Add socket protocol control support in sandboxer demo. It's possible to allow a sandboxer to create sockets with specified family(domain) and type values. This is controlled with the new LL_SOCKET_CREATE environment variable. Single token in this variable looks like this: 'FAMILY.TYPE', where FAMILY corresponds to one of the possible socket family name and TYPE to the possible socket type name (see socket(2)). Add ENV_TOKEN_INTERNAL_DELIMITER. Add get_socket_protocol() method to parse socket family and type strings to the appropriate constants. Add CHECK_DOMAIN() and CHECK_TYPE() macroses to prevent copypaste. Signed-off-by: Ivanov Mikhail Reviewed-by: Konstantin Meskhidze --- samples/landlock/sandboxer.c | 149 ++++++++++++++++++++++++++++++++--- 1 file changed, 136 insertions(+), 13 deletions(-) diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c index 32e930c85..4642a7437 100644 --- a/samples/landlock/sandboxer.c +++ b/samples/landlock/sandboxer.c @@ -14,6 +14,7 @@ #include #include #include +#include #include #include #include @@ -55,8 +56,11 @@ static inline int landlock_restrict_self(const int ruleset_fd, #define ENV_FS_RW_NAME "LL_FS_RW" #define ENV_TCP_BIND_NAME "LL_TCP_BIND" #define ENV_TCP_CONNECT_NAME "LL_TCP_CONNECT" +#define ENV_SOCKET_CREATE_NAME "LL_SOCKET_CREATE" #define ENV_DELIMITER ":" +#define ENV_TOKEN_INTERNAL_DELIMITER "." + static int parse_path(char *env_path, const char ***const path_list) { int i, num_paths = 0; @@ -85,6 +89,49 @@ static int parse_path(char *env_path, const char ***const path_list) /* clang-format on */ +#define CHECK_DOMAIN(domain_variant) \ + do { \ + if (strcmp(strdomain, #domain_variant) == 0) { \ + protocol->domain = domain_variant; \ + domain_parsed = 1; \ + goto domain_check; \ + } \ + } while (0) + +#define CHECK_TYPE(type_variant) \ + do { \ + if (strcmp(strtype, #type_variant) == 0) { \ + protocol->type = type_variant; \ + type_parsed = 1; \ + goto type_check; \ + } \ + } while (0) + +static int get_socket_protocol(char *strdomain, char *strtype, + struct landlock_socket_attr *protocol) +{ + int domain_parsed = 0, type_parsed = 0; + + CHECK_DOMAIN(AF_UNIX); + CHECK_DOMAIN(AF_INET); + CHECK_DOMAIN(AF_INET6); + +domain_check: + if (!domain_parsed) + return 1; + + CHECK_TYPE(SOCK_STREAM); + CHECK_TYPE(SOCK_DGRAM); + +type_check: + if (!type_parsed) + return 1; + return 0; +} + +#undef CHECK_DOMAIN +#undef CHECK_TYPE + static int populate_ruleset_fs(const char *const env_var, const int ruleset_fd, const __u64 allowed_access) { @@ -182,6 +229,58 @@ static int populate_ruleset_net(const char *const env_var, const int ruleset_fd, return ret; } +static int populate_ruleset_socket(const char *const env_var, + const int ruleset_fd, const __u64 allowed_access) +{ + int ret = 1; + char *env_protocol_name, *env_protocol_name_next; + char *strprotocol, *strdomain, *strtype; + struct landlock_socket_attr protocol = { + .allowed_access = allowed_access, + .domain = 0, + .type = 0, + }; + + env_protocol_name = getenv(env_var); + if (!env_protocol_name) + return 0; + env_protocol_name = strdup(env_protocol_name); + unsetenv(env_var); + + env_protocol_name_next = env_protocol_name; + while ((strprotocol = strsep(&env_protocol_name_next, ENV_DELIMITER))) { + strdomain = strsep(&strprotocol, ENV_TOKEN_INTERNAL_DELIMITER); + strtype = strsep(&strprotocol, ENV_TOKEN_INTERNAL_DELIMITER); + + if (!strtype) { + fprintf(stderr, "Failed to extract socket protocol with " + "unspecified type value\n"); + goto out_free_name; + } + + if (get_socket_protocol(strdomain, strtype, &protocol)) { + fprintf(stderr, "Failed to extract socket protocol with " + "domain: \"%s\", type: \"%s\"\n", + strdomain, strtype); + goto out_free_name; + } + + if (landlock_add_rule(ruleset_fd, LANDLOCK_RULE_SOCKET, + &protocol, 0)) { + fprintf(stderr, + "Failed to update the ruleset with " + "domain \"%s\" and type \"%s\": %s\n", + strdomain, strtype, strerror(errno)); + goto out_free_name; + } + } + ret = 0; + +out_free_name: + free(env_protocol_name); + return ret; +} + /* clang-format off */ #define ACCESS_FS_ROUGHLY_READ ( \ @@ -205,14 +304,14 @@ static int populate_ruleset_net(const char *const env_var, const int ruleset_fd, /* clang-format on */ -#define LANDLOCK_ABI_LAST 4 +#define LANDLOCK_ABI_LAST 5 int main(const int argc, char *const argv[], char *const *const envp) { const char *cmd_path; char *const *cmd_argv; int ruleset_fd, abi; - char *env_port_name; + char *env_optional_name; __u64 access_fs_ro = ACCESS_FS_ROUGHLY_READ, access_fs_rw = ACCESS_FS_ROUGHLY_READ | ACCESS_FS_ROUGHLY_WRITE; @@ -220,18 +319,19 @@ int main(const int argc, char *const argv[], char *const *const envp) .handled_access_fs = access_fs_rw, .handled_access_net = LANDLOCK_ACCESS_NET_BIND_TCP | LANDLOCK_ACCESS_NET_CONNECT_TCP, + .handled_access_socket = LANDLOCK_ACCESS_SOCKET_CREATE, }; if (argc < 2) { fprintf(stderr, - "usage: %s=\"...\" %s=\"...\" %s=\"...\" %s=\"...\"%s " + "usage: %s=\"...\" %s=\"...\" %s=\"...\" %s=\"...\" %s=\"...\"%s " " [args]...\n\n", ENV_FS_RO_NAME, ENV_FS_RW_NAME, ENV_TCP_BIND_NAME, - ENV_TCP_CONNECT_NAME, argv[0]); + ENV_TCP_CONNECT_NAME, ENV_SOCKET_CREATE_NAME, argv[0]); fprintf(stderr, "Execute a command in a restricted environment.\n\n"); fprintf(stderr, - "Environment variables containing paths and ports " + "Environment variables containing paths, ports and protocols " "each separated by a colon:\n"); fprintf(stderr, "* %s: list of paths allowed to be used in a read-only way.\n", @@ -240,7 +340,7 @@ int main(const int argc, char *const argv[], char *const *const envp) "* %s: list of paths allowed to be used in a read-write way.\n\n", ENV_FS_RW_NAME); fprintf(stderr, - "Environment variables containing ports are optional " + "Environment variables containing ports or protocols are optional " "and could be skipped.\n"); fprintf(stderr, "* %s: list of ports allowed to bind (server).\n", @@ -248,22 +348,25 @@ int main(const int argc, char *const argv[], char *const *const envp) fprintf(stderr, "* %s: list of ports allowed to connect (client).\n", ENV_TCP_CONNECT_NAME); + fprintf(stderr, + "* %s: list of socket protocols allowed to be created.\n", + ENV_SOCKET_CREATE_NAME); fprintf(stderr, "\nexample:\n" "%s=\"${PATH}:/lib:/usr:/proc:/etc:/dev/urandom\" " "%s=\"/dev/null:/dev/full:/dev/zero:/dev/pts:/tmp\" " "%s=\"9418\" " "%s=\"80:443\" " + "%s=\"AF_INET6.SOCK_STREAM:AF_UNIX.SOCK_STREAM\" " "%s bash -i\n\n", ENV_FS_RO_NAME, ENV_FS_RW_NAME, ENV_TCP_BIND_NAME, - ENV_TCP_CONNECT_NAME, argv[0]); + ENV_TCP_CONNECT_NAME, ENV_SOCKET_CREATE_NAME, argv[0]); fprintf(stderr, "This sandboxer can use Landlock features " "up to ABI version %d.\n", LANDLOCK_ABI_LAST); return 1; } - abi = landlock_create_ruleset(NULL, 0, LANDLOCK_CREATE_RULESET_VERSION); if (abi < 0) { const int err = errno; @@ -325,6 +428,16 @@ int main(const int argc, char *const argv[], char *const *const envp) "provided by ABI version %d (instead of %d).\n", LANDLOCK_ABI_LAST, abi); __attribute__((fallthrough)); + case 4: + /* Removes socket support for ABI < 5 */ + ruleset_attr.handled_access_socket &= + ~LANDLOCK_ACCESS_SOCKET_CREATE; + fprintf(stderr, + "Hint: You should update the running kernel " + "to leverage Landlock features " + "provided by ABI version %d (instead of %d).\n", + LANDLOCK_ABI_LAST, abi); + __attribute__((fallthrough)); case LANDLOCK_ABI_LAST: break; default: @@ -338,18 +451,23 @@ int main(const int argc, char *const argv[], char *const *const envp) access_fs_rw &= ruleset_attr.handled_access_fs; /* Removes bind access attribute if not supported by a user. */ - env_port_name = getenv(ENV_TCP_BIND_NAME); - if (!env_port_name) { + env_optional_name = getenv(ENV_TCP_BIND_NAME); + if (!env_optional_name) { ruleset_attr.handled_access_net &= ~LANDLOCK_ACCESS_NET_BIND_TCP; } /* Removes connect access attribute if not supported by a user. */ - env_port_name = getenv(ENV_TCP_CONNECT_NAME); - if (!env_port_name) { + env_optional_name = getenv(ENV_TCP_CONNECT_NAME); + if (!env_optional_name) { ruleset_attr.handled_access_net &= ~LANDLOCK_ACCESS_NET_CONNECT_TCP; } - + /* Removes socket create access attribute if not supported by a user. */ + env_optional_name = getenv(ENV_SOCKET_CREATE_NAME); + if (!env_optional_name) { + ruleset_attr.handled_access_socket &= + ~LANDLOCK_ACCESS_SOCKET_CREATE; + } ruleset_fd = landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0); if (ruleset_fd < 0) { @@ -373,6 +491,11 @@ int main(const int argc, char *const argv[], char *const *const envp) goto err_close_ruleset; } + if (populate_ruleset_socket(ENV_SOCKET_CREATE_NAME, ruleset_fd, + LANDLOCK_ACCESS_SOCKET_CREATE)) { + goto err_close_ruleset; + } + if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) { perror("Failed to restrict privileges"); goto err_close_ruleset;