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 01D74C6FA83 for ; Tue, 6 Sep 2022 08:09:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233609AbiIFIJe (ORCPT ); Tue, 6 Sep 2022 04:09:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49004 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239077AbiIFIJE (ORCPT ); Tue, 6 Sep 2022 04:09:04 -0400 Received: from smtp-8faa.mail.infomaniak.ch (smtp-8faa.mail.infomaniak.ch [IPv6:2001:1600:4:17::8faa]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 24F82719AA for ; Tue, 6 Sep 2022 01:09:00 -0700 (PDT) Received: from smtp-2-0001.mail.infomaniak.ch (unknown [10.5.36.108]) by smtp-3-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 4MMJ1k2NC9zMqNKM; Tue, 6 Sep 2022 10:08:58 +0200 (CEST) Received: from ns3096276.ip-94-23-54.eu (unknown [23.97.221.149]) by smtp-2-0001.mail.infomaniak.ch (Postfix) with ESMTPA id 4MMJ1j4cyMzMppMq; Tue, 6 Sep 2022 10:08:57 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=digikod.net; s=20191114; t=1662451738; bh=srHFntzEYBYWZtTU8tEvBUs2xqbes+tqbiJpiWJMDzw=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Kb0280ouPLcxeProqEOw+jSl2vm0HVC52qhNpYcIWh/OT+BJ5BVXwNgZQU5wBThh2 HaYvq9FAORR0gO2qpY0AUQJYaSfbzwtVPRNdxY6CXEnoYzEJumKgGbHm559Soq9TkL tJMK5jzcQqmhe7aGIDYo15JKifHKuBOQEvFG2H7A= Message-ID: <71dd7517-4d3c-b644-18bd-cb792d68bcd8@digikod.net> Date: Tue, 6 Sep 2022 10:08:57 +0200 MIME-Version: 1.0 User-Agent: Subject: Re: [PATCH v7 09/18] landlock: implement TCP network hooks Content-Language: en-US To: Konstantin Meskhidze , gnoack3000@gmail.com Cc: willemdebruijn.kernel@gmail.com, linux-security-module@vger.kernel.org, netdev@vger.kernel.org, netfilter-devel@vger.kernel.org, yusongping@huawei.com, hukeping@huawei.com, anton.sirazetdinov@huawei.com References: <20220829170401.834298-1-konstantin.meskhidze@huawei.com> <20220829170401.834298-10-konstantin.meskhidze@huawei.com> From: =?UTF-8?Q?Micka=c3=abl_Sala=c3=bcn?= In-Reply-To: <20220829170401.834298-10-konstantin.meskhidze@huawei.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org On 29/08/2022 19:03, Konstantin Meskhidze wrote: > This patch adds support of socket_bind() and socket_connect() hooks. > It's possible to restrict binding and connecting of TCP types of > sockets to particular ports. It's just basic idea of how Landlock I guess it's not a basic idea anymore. > could support network confinement. > > Signed-off-by: Konstantin Meskhidze > --- > > Changes since v6: > * Updates copyright. > * Refactors landlock_append_net_rule() and check_socket_access() > functions with landlock_id type. > > Changes since v5: > * Fixes some logic errors. > * Formats code with clang-format-14. > > Changes since v4: > * Factors out CONFIG_INET into make file. > * Refactors check_socket_access(). > * Adds helper get_port(). > * Adds CONFIG_IPV6 in get_port(), hook_socket_bind/connect > functions to support AF_INET6 family. > * Adds AF_UNSPEC family support in hook_socket_bind/connect > functions. > * Refactors add_rule_net_service() and landlock_add_rule > syscall to support network rule inserting. > * Refactors init_layer_masks() to support network rules. > > Changes since v3: > * Splits commit. > * Adds SECURITY_NETWORK in config. > * Adds IS_ENABLED(CONFIG_INET) if a kernel has no INET configuration. > * Adds hook_socket_bind and hook_socket_connect hooks. > > --- > security/landlock/Kconfig | 1 + > security/landlock/Makefile | 2 + > security/landlock/net.c | 161 +++++++++++++++++++++++++++++++++++ > security/landlock/net.h | 26 ++++++ > security/landlock/setup.c | 2 + > security/landlock/syscalls.c | 59 ++++++++++++- > 6 files changed, 248 insertions(+), 3 deletions(-) > create mode 100644 security/landlock/net.c > create mode 100644 security/landlock/net.h > > diff --git a/security/landlock/Kconfig b/security/landlock/Kconfig > index 8e33c4e8ffb8..10c099097533 100644 > --- a/security/landlock/Kconfig > +++ b/security/landlock/Kconfig > @@ -3,6 +3,7 @@ > config SECURITY_LANDLOCK > bool "Landlock support" > depends on SECURITY && !ARCH_EPHEMERAL_INODES > + select SECURITY_NETWORK > select SECURITY_PATH > help > Landlock is a sandboxing mechanism that enables processes to restrict > diff --git a/security/landlock/Makefile b/security/landlock/Makefile > index 7bbd2f413b3e..53d3c92ae22e 100644 > --- a/security/landlock/Makefile > +++ b/security/landlock/Makefile > @@ -2,3 +2,5 @@ obj-$(CONFIG_SECURITY_LANDLOCK) := landlock.o > > landlock-y := setup.o syscalls.o object.o ruleset.o \ > cred.o ptrace.o fs.o > + > +landlock-$(CONFIG_INET) += net.o > \ No newline at end of file > diff --git a/security/landlock/net.c b/security/landlock/net.c > new file mode 100644 > index 000000000000..0d249ad619bf > --- /dev/null > +++ b/security/landlock/net.c > @@ -0,0 +1,161 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * Landlock LSM - Network management and hooks > + * > + * Copyright © 2022 Huawei Tech. Co., Ltd. > + * Copyright © 2022 Microsoft Corporation > + */ > + > +#include > +#include > +#include > +#include > + #include "common.h" > +#include "cred.h" > +#include "limits.h" > +#include "net.h" #include "ruleset.h" > + > +int landlock_append_net_rule(struct landlock_ruleset *const ruleset, u16 port, > + u32 access_rights) Please constify all arguments, in this function and others. > +{ > + int err; > + const struct landlock_id id = { > + .key.data = port, > + .type = LANDLOCK_KEY_NET_PORT, > + }; > + BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data)); > + > + /* Transforms relative access rights to absolute ones. */ > + access_rights |= LANDLOCK_MASK_ACCESS_NET & > + ~landlock_get_net_access_mask(ruleset, 0); > + > + mutex_lock(&ruleset->lock); > + err = landlock_insert_rule(ruleset, id, access_rights); > + mutex_unlock(&ruleset->lock); > + > + return err; > +} > + > +static int check_socket_access(const struct landlock_ruleset *const domain, > + u16 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; > + > + rule = landlock_find_rule(domain, id); > + handled_access = init_layer_masks(domain, access_request, &layer_masks, > + LANDLOCK_KEY_NET_PORT); > + allowed = unmask_layers(rule, handled_access, &layer_masks, > + ARRAY_SIZE(layer_masks)); > + > + 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 ntohs(sockaddr->sin_port); > + } > +#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 hook_socket_bind(struct socket *sock, struct sockaddr *address, > + int addrlen) > +{ > + const struct landlock_ruleset *const dom = > + landlock_get_current_domain(); > + > + if (!dom) > + return 0; > + > + /* Check if it's a TCP socket. */ > + if (sock->type != SOCK_STREAM) > + return 0; > + > + switch (address->sa_family) { > + case AF_UNSPEC: > + case AF_INET: > +#if IS_ENABLED(CONFIG_IPV6) > + case AF_INET6: > +#endif > + return check_socket_access(dom, get_port(address), > + LANDLOCK_ACCESS_NET_BIND_TCP); > + default: > + return 0; > + } > +} > + > +static int hook_socket_connect(struct socket *sock, struct sockaddr *address, > + int addrlen) > +{ > + const struct landlock_ruleset *const dom = > + landlock_get_current_domain(); > + > + if (!dom) > + return 0; > + > + /* Check if it's a TCP socket. */ > + if (sock->type != SOCK_STREAM) > + return 0; > + > + /* Check if the hook is AF_INET* socket's action. */ > + switch (address->sa_family) { > + case AF_INET: > +#if IS_ENABLED(CONFIG_IPV6) > + case AF_INET6: > +#endif > + return check_socket_access(dom, get_port(address), > + LANDLOCK_ACCESS_NET_CONNECT_TCP); > + case AF_UNSPEC: { > + u16 i; break line > + /* > + * If just in a layer a mask supports connect access, > + * the socket_connect() hook with AF_UNSPEC family flag > + * must be banned. This prevents from disconnecting already > + * connected sockets. > + */ > + for (i = 0; i < dom->num_layers; i++) { > + if (landlock_get_net_access_mask(dom, i) & > + LANDLOCK_ACCESS_NET_CONNECT_TCP) > + return -EACCES; > + } > + } > + } > + return 0; > +} > + > +static struct security_hook_list landlock_hooks[] __lsm_ro_after_init = { > + LSM_HOOK_INIT(socket_bind, hook_socket_bind), > + LSM_HOOK_INIT(socket_connect, hook_socket_connect), > +}; > + > +__init void landlock_add_net_hooks(void) > +{ > + security_add_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks), > + LANDLOCK_NAME); > +} > diff --git a/security/landlock/net.h b/security/landlock/net.h > new file mode 100644 > index 000000000000..2c63a8f1b258 > --- /dev/null > +++ b/security/landlock/net.h > @@ -0,0 +1,26 @@ > +/* SPDX-License-Identifier: GPL-2.0-only */ > +/* > + * Landlock LSM - Network management and hooks > + * > + * Copyright © 2022 Huawei Tech. Co., Ltd. > + */ > + > +#ifndef _SECURITY_LANDLOCK_NET_H > +#define _SECURITY_LANDLOCK_NET_H > + > +#include "common.h" > +#include "ruleset.h" > +#include "setup.h" > + > +#if IS_ENABLED(CONFIG_INET) > +__init void landlock_add_net_hooks(void); > + > +int landlock_append_net_rule(struct landlock_ruleset *const ruleset, u16 port, > + u32 access_hierarchy); > +#else /* IS_ENABLED(CONFIG_INET) */ > +static inline void landlock_add_net_hooks(void) > +{ > +} > +#endif /* IS_ENABLED(CONFIG_INET) */ > + > +#endif /* _SECURITY_LANDLOCK_NET_H */ > diff --git a/security/landlock/setup.c b/security/landlock/setup.c > index f8e8e980454c..8059dc0b47d3 100644 > --- a/security/landlock/setup.c > +++ b/security/landlock/setup.c > @@ -14,6 +14,7 @@ > #include "fs.h" > #include "ptrace.h" > #include "setup.h" > +#include "net.h" > > bool landlock_initialized __lsm_ro_after_init = false; > > @@ -28,6 +29,7 @@ static int __init landlock_init(void) > landlock_add_cred_hooks(); > landlock_add_ptrace_hooks(); > landlock_add_fs_hooks(); > + landlock_add_net_hooks(); > landlock_initialized = true; > pr_info("Up and running.\n"); > return 0; > diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c > index 641155f6f6f8..16880e951346 100644 > --- a/security/landlock/syscalls.c > +++ b/security/landlock/syscalls.c > @@ -29,6 +29,7 @@ > #include "cred.h" > #include "fs.h" > #include "limits.h" > +#include "net.h" > #include "ruleset.h" > #include "setup.h" > > @@ -74,7 +75,8 @@ static void build_check_abi(void) > { > struct landlock_ruleset_attr ruleset_attr; > struct landlock_path_beneath_attr path_beneath_attr; > - size_t ruleset_size, path_beneath_size; > + struct landlock_net_service_attr net_service_attr; > + size_t ruleset_size, path_beneath_size, net_service_size; > > /* > * For each user space ABI structures, first checks that there is no > @@ -90,6 +92,11 @@ static void build_check_abi(void) > path_beneath_size += sizeof(path_beneath_attr.parent_fd); > BUILD_BUG_ON(sizeof(path_beneath_attr) != path_beneath_size); > BUILD_BUG_ON(sizeof(path_beneath_attr) != 12); > + > + net_service_size = sizeof(net_service_attr.allowed_access); > + net_service_size += sizeof(net_service_attr.port); > + BUILD_BUG_ON(sizeof(net_service_attr) != net_service_size); > + BUILD_BUG_ON(sizeof(net_service_attr) != 10); > } > > /* Ruleset handling */ > @@ -322,13 +329,54 @@ static int add_rule_path_beneath(struct landlock_ruleset *const ruleset, > return err; > } > > +static int add_rule_net_service(struct landlock_ruleset *ruleset, > + const void __user *const rule_attr) > +{ > +#if IS_ENABLED(CONFIG_INET) > + struct landlock_net_service_attr net_service_attr; > + int res; > + u32 mask; > + > + /* Copies raw user space buffer, only one type for now. */ > + res = copy_from_user(&net_service_attr, rule_attr, > + sizeof(net_service_attr)); > + if (res) > + return -EFAULT; > + > + /* > + * Informs about useless rule: empty allowed_access (i.e. deny rules) > + * are ignored by network actions. > + */ > + if (!net_service_attr.allowed_access) > + return -ENOMSG; > + > + /* > + * Checks that allowed_access matches the @ruleset constraints > + * (ruleset->access_masks[0] is automatically upgraded to 64-bits). > + */ > + mask = landlock_get_net_access_mask(ruleset, 0); > + if ((net_service_attr.allowed_access | mask) != mask) > + return -EINVAL; > + > + /* Denies inserting a rule with port 0. */ > + if (net_service_attr.port == 0) > + return -EINVAL; > + > + /* Imports the new rule. */ > + return landlock_append_net_rule(ruleset, net_service_attr.port, > + net_service_attr.allowed_access); > +#else /* IS_ENABLED(CONFIG_INET) */ > + return -EAFNOSUPPORT; I think this is the right approach to return -EAFNOSUPPORT here instead of with landlock_create_ruleset() because if some network features are not available this means that they will be denied. Only allowing some exception (i.e. with a rule) would not make sense because it could work at the end. This should be explained in the documentation. Landlock libraries would have to handle this error type as not-an-error most of the time though, except when users want to be sure the running system support such network feature. Any though? > +#endif /* IS_ENABLED(CONFIG_INET) */ > +} > + > /** > * sys_landlock_add_rule - Add a new rule to a ruleset > * > * @ruleset_fd: File descriptor tied to the ruleset that should be extended > * with the new rule. > - * @rule_type: Identify the structure type pointed to by @rule_attr (only > - * LANDLOCK_RULE_PATH_BENEATH for now). > + * @rule_type: Identify the structure type pointed to by @rule_attr: > + * LANDLOCK_RULE_PATH_BENEATH or LANDLOCK_RULE_NET_SERVICE. %LANDLOCK_RULE_PATH_BENEATH or %LANDLOCK_RULE_NET_SERVICE. > * @rule_attr: Pointer to a rule (only of type &struct > * landlock_path_beneath_attr for now). > * @flags: Must be 0. > @@ -339,6 +387,8 @@ static int add_rule_path_beneath(struct landlock_ruleset *const ruleset, > * Possible returned errors are: > * > * - EOPNOTSUPP: Landlock is supported by the kernel but disabled at boot time; > + * - EAFNOSUPPORT: @rule_type is LANDLOCK_RULE_NET_SERVICE but TCP/IP is not %EAFNOSUPPORT %LANDLOCK_RULE_NET_SERVICE BTW, I'll send a patch soon to fix some documentation style inconsistency, including the missing "%" for defined values (e.g. errno). > + * supported by the running kernel; > * - EINVAL: @flags is not 0, or inconsistent access in the rule (i.e. > * &landlock_path_beneath_attr.allowed_access is not a subset of the rule's > * accesses); > @@ -374,6 +424,9 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd, > case LANDLOCK_RULE_PATH_BENEATH: > err = add_rule_path_beneath(ruleset, rule_attr); > break; > + case LANDLOCK_RULE_NET_SERVICE: > + err = add_rule_net_service(ruleset, rule_attr); > + break; > default: > err = -EINVAL; > break; > -- > 2.25.1 >