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Message-ID: <f67a9dc0-2f41-8848-3539-6fd981fd150d@huawei.com> Date: Tue, 10 Jan 2023 07:45:09 +0300 From: "Konstantin Meskhidze (A)" <konstantin.meskhidze@...wei.com> To: Mickaël Salaün <mic@...ikod.net>, <netdev@...r.kernel.org>, <linux-api@...r.kernel.org>, "Alejandro Colomar (man-pages)" <alx.manpages@...il.com> CC: <willemdebruijn.kernel@...il.com>, <gnoack3000@...il.com>, <linux-security-module@...r.kernel.org>, <netfilter-devel@...r.kernel.org>, <artem.kuzin@...wei.com> Subject: Re: [PATCH v8 08/12] landlock: Implement TCP network hooks 1/9/2023 3:38 PM, Mickaël Salaün пишет: > > On 09/01/2023 09:07, Konstantin Meskhidze (A) wrote: >> >> >> 1/6/2023 10:30 PM, Mickaël Salaün пишет: >>> >>> On 05/01/2023 09:57, Konstantin Meskhidze (A) wrote: >>>> >>>> >>>> 11/17/2022 9:43 PM, Mickaël Salaün пишет: >>>>> >>>>> On 21/10/2022 17:26, Konstantin Meskhidze wrote: >>>>>> This patch adds support of socket_bind() and socket_connect() hooks. >>>>>> It's possible to restrict binding and connecting of TCP sockets to >>>>>> particular ports. >>>>> >>>>> 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 <konstantin.meskhidze@...wei.com> >>>>>> --- >>>>>> >>>>>> Changes since v7: >>>>>> * Minor fixes. >>>>>> * Refactors commit message. >>>>>> >>>>>> 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 | 164 +++++++++++++++++++++++++++++++++++ >>>>>> security/landlock/net.h | 26 ++++++ >>>>>> security/landlock/setup.c | 2 + >>>>>> security/landlock/syscalls.c | 59 ++++++++++++- >>>>>> 6 files changed, 251 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..39e8a156a1f4 >>>>>> --- /dev/null >>>>>> +++ b/security/landlock/net.c >>>>>> @@ -0,0 +1,164 @@ >>>>>> +// 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 = 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) >>>>> >>>>> get_port() should return a __be16 type. This enables to avoid converting >>>>> port when checking a rule. >>>> >>>> In this case a user must do a coverting port into __be16: >>>> >>>> struct landlock_net_service_attr net_service = { >>>> .allowed_access = LANDLOCK_ACCESS_NET_BIND_TCP, >>>> >>>> .port = htons(sock_port), >>>> }; >>>> I think that a user should not think about this conversion cause it >>>> makes UAPI more complex to use. Lets do this under kernel's hood and let >>>> it as it is now -> u16 port. >>>> >>>> What do you think? >>> >>> BE and LE conversions may be error prone without strong typing, but the >>> current Linux network UAPI uses this convention (see related syscalls), >>> so developers already use htons() in their applications. I think it is >>> less hazardous to use the same convention. It would be nice to have the >>> point of view of network and API folks though. >> >> Ok. Thanks. Let ports be in BE format like in network packets. >> >> What should a selftest with port conversion be like? >> >> 1. Set a port with a Landlock rule with no conversion. get an error >> wit bind/connect actions. >> 2. Convert a port with htons(sock_port). get no error. >> >> What do you think? > > Right, you can do both on a LE architecture (that must be checked in the > test or it should be skipped), test with a port value that has different > representation in LE and BE. Do you mean to check architecture in a test first and then port representaton? What about BE architectures? My current VM is X86-64 architecture a LE one. I can test just it now. > .
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