| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <fa4c8e04-3999-94a9-7691-6df3130eb591@digikod.net>
Date: Mon, 3 Jul 2023 19:06:55 +0200
From: Mickaël Salaün <mic@...ikod.net>
To: "Konstantin Meskhidze (A)" <konstantin.meskhidze@...wei.com>
Cc: willemdebruijn.kernel@...il.com, gnoack3000@...il.com,
linux-security-module@...r.kernel.org, netdev@...r.kernel.org,
netfilter-devel@...r.kernel.org, yusongping@...wei.com,
artem.kuzin@...wei.com
Subject: Re: [PATCH v11 08/12] landlock: Add network rules and TCP hooks
support
On 03/07/2023 12:36, Konstantin Meskhidze (A) wrote:
>
>
> 6/26/2023 9:57 PM, Mickaël Salaün пишет:
>> Complementary review:
>>
>> On 15/05/2023 18:13, 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 enables to restrict TCP socket binding and connection
>>> to specific ports.
>>>
>>> Co-developed-by: Mickaël Salaün <mic@...ikod.net>
>>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@...wei.com>
>>> ---
>>>
>>> Changes since v10:
>>> * Removes "packed" attribute.
>>> * Applies Mickaёl's patch with some refactoring.
>>> * Deletes get_port() and check_addrlen() helpers.
>>> * Refactors check_socket_access() by squashing get_port() and
>>> check_addrlen() helpers into it.
>>> * Fixes commit message.
>>>
>>> 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 | 48 +++++
>>> security/landlock/Kconfig | 1 +
>>> security/landlock/Makefile | 2 +
>>> security/landlock/limits.h | 6 +-
>>> security/landlock/net.c | 174 +++++++++++++++++++
>>> 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, 425 insertions(+), 23 deletions(-)
>>> create mode 100644 security/landlock/net.c
>>> create mode 100644 security/landlock/net.h
>>>
>>> diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h
>>> index 81d09ef9aa50..93794759dad4 100644
>>> --- a/include/uapi/linux/landlock.h
>>> +++ b/include/uapi/linux/landlock.h
>>> @@ -31,6 +31,13 @@ struct landlock_ruleset_attr {
>>> * this access right.
>>> */
>>> __u64 handled_access_fs;
>>> +
>>
>> Please remove this empty line.
>
> Ok. Thanks.
>>
>>
>>> + /**
>>> + * @handled_access_net: Bitmask of actions (cf. `Network flags`_)
>>> + * that is handled by this ruleset and should then be forbidden if no
>>> + * rule explicitly allow them.
>>> + */
>>> + __u64 handled_access_net;
>>> };
>>>
>>> /*
>>> @@ -54,6 +61,11 @@ enum landlock_rule_type {
>>> * landlock_path_beneath_attr .
>>> */
>>> LANDLOCK_RULE_PATH_BENEATH = 1,
>>> + /**
>>> + * @LANDLOCK_RULE_NET_SERVICE: Type of a &struct
>>> + * landlock_net_service_attr .
>>> + */
>>> + LANDLOCK_RULE_NET_SERVICE = 2,
>>> };
>>>
>>> /**
>>> @@ -79,6 +91,23 @@ struct landlock_path_beneath_attr {
>>> */
>>> } __attribute__((packed));
>>>
>>> +/**
>>> + * struct landlock_net_service_attr - TCP subnet definition
>>
>> s/TCP subnet definition/Network service definition/
>>
> Ok. Thanks.
>>
>>> + *
>>> + * Argument of sys_landlock_add_rule().
>>> + */
>>> +struct landlock_net_service_attr {
>>> + /**
>>> + * @allowed_access: Bitmask of allowed access network for services
>>> + * (cf. `Network flags`_).
>>> + */
>>> + __u64 allowed_access;
>>> + /**
>>> + * @port: Network port.
>>> + */
>>> + __u64 port;
>>> +};
>>> +
>>> /**
>>> * DOC: fs_access
>>> *
>>> @@ -189,4 +218,23 @@ struct landlock_path_beneath_attr {
>>> #define LANDLOCK_ACCESS_FS_TRUNCATE (1ULL << 14)
>>> /* clang-format on */
>>>
>>> +/**
>>> + * DOC: net_access
>>> + *
>>> + * Network flags
>>> + * ~~~~~~~~~~~~~~~~
>>> + *
>>> + * These flags enable to restrict a sandboxed process to a set of network
>>> + * actions.
>>> + *
>>> + * TCP sockets with allowed actions:
>>> + *
>>> + * - %LANDLOCK_ACCESS_NET_BIND_TCP: Bind a TCP socket to a local port.
>>> + * - %LANDLOCK_ACCESS_NET_CONNECT_TCP: Connect an active TCP socket to
>>> + * a remote port.
>>> + */
>>> +/* clang-format off */
>>> +#define LANDLOCK_ACCESS_NET_BIND_TCP (1ULL << 0)
>>> +#define LANDLOCK_ACCESS_NET_CONNECT_TCP (1ULL << 1)
>>> +/* clang-format on */
>>> #endif /* _UAPI_LINUX_LANDLOCK_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/limits.h b/security/landlock/limits.h
>>> index bafb3b8dc677..8a1a6463c64e 100644
>>> --- a/security/landlock/limits.h
>>> +++ b/security/landlock/limits.h
>>> @@ -23,6 +23,10 @@
>>> #define LANDLOCK_NUM_ACCESS_FS __const_hweight64(LANDLOCK_MASK_ACCESS_FS)
>>> #define LANDLOCK_SHIFT_ACCESS_FS 0
>>>
>>> -/* clang-format on */
>>> +#define LANDLOCK_LAST_ACCESS_NET LANDLOCK_ACCESS_NET_CONNECT_TCP
>>> +#define LANDLOCK_MASK_ACCESS_NET ((LANDLOCK_LAST_ACCESS_NET << 1) - 1)
>>> +#define LANDLOCK_NUM_ACCESS_NET __const_hweight64(LANDLOCK_MASK_ACCESS_NET)
>>> +#define LANDLOCK_SHIFT_ACCESS_NET LANDLOCK_NUM_ACCESS_FS
>>>
>>> +/* clang-format on */
>>
>> Please the empty line to make this patch clean.
>
> Ok. I will.
>>
>>
>>> #endif /* _SECURITY_LANDLOCK_LIMITS_H */
>>> diff --git a/security/landlock/net.c b/security/landlock/net.c
>>> new file mode 100644
>>> index 000000000000..f8d2be53ac0d
>>> --- /dev/null
>>> +++ b/security/landlock/net.c
>>> @@ -0,0 +1,174 @@
>>> +// SPDX-License-Identifier: GPL-2.0-only
>>> +/*
>>> + * Landlock LSM - Network management and hooks
>>> + *
>>> + * Copyright © 2022 Huawei Tech. Co., Ltd.
>>> + * Copyright © 2022 Microsoft Corporation
>>> + */
>>> +
>>> +#include <linux/in.h>
>>> +#include <linux/net.h>
>>> +#include <linux/socket.h>
>>> +#include <net/ipv6.h>
>>> +
>>> +#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,
>>> + const u16 port, access_mask_t access_rights)
>>> +{
>>> + int err;
>>> + const struct landlock_id id = {
>>> + .key.data = (__force uintptr_t)htons(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 access_mask_t
>>> +get_raw_handled_net_accesses(const struct landlock_ruleset *const domain)
>>> +{
>>> + access_mask_t access_dom = 0;
>>> + size_t layer_level;
>>> +
>>> + for (layer_level = 0; layer_level < domain->num_layers; layer_level++)
>>> + access_dom |= landlock_get_net_access_mask(domain, layer_level);
>>> + return access_dom;
>>> +}
>>> +
>>> +static const struct landlock_ruleset *get_current_net_domain(void)
>>> +{
>>> + const struct landlock_ruleset *const dom =
>>> + landlock_get_current_domain();
>>> +
>>> + if (!dom || !get_raw_handled_net_accesses(dom))
>>> + return NULL;
>>> +
>>> + return dom;
>>> +}
>>> +
>>> +static int check_socket_access(struct socket *const sock,
>>> + struct sockaddr *const address,
>>> + const int addrlen,
>>> + const access_mask_t access_request)
>>> +{
>>> + __be16 port;
>>> + layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_NET] = {};
>>> + const struct landlock_rule *rule;
>>> + access_mask_t handled_access;
>>> + struct landlock_id id = {
>>> + .type = LANDLOCK_KEY_NET_PORT,
>>> + };
>>> + const struct landlock_ruleset *const domain = get_current_net_domain();
>>> +
>>> + if (WARN_ON_ONCE(!domain))
>>
>> The WARN_ON_ONCE() needs to be removed for processes not sandboxed. This
>> should be printed when running the tests.
>>
> Probably during the boot stage it prints once since no process is
> landlocked at this stage.
> So we need to leave it like this:
> if (!domain)
> return 0;
Yes
> ????
>>
>>
>>> + return 0;
>>> + if (WARN_ON_ONCE(domain->num_layers < 1))
>>> + return -EACCES;
>>> +
>>> + /* Checks if it's a TCP socket. */
>>> + if (sock->type != SOCK_STREAM)
>>> + return 0;
>>> +
>>> + /* Checks for minimal header length. */
>>> + if (addrlen < offsetofend(struct sockaddr, sa_family))
>>
>> You can use "typeof(*address)" instead of struct sockaddr, this makes it
>> easier to review.
>>
> Do mean to change offsetofend() by typeof(*address)??
No: if (addrlen < offsetofend(typeof(*address), sa_family))
>>
>>> + return -EINVAL;
>>> +
>>
>> [...]
>> .
Powered by blists - more mailing lists