[PATCH v13 08/12] landlock: Add network rules and TCP hooks support
Konstantin Meskhidze (A)
konstantin.meskhidze at huawei.com
Fri Oct 20 04:08:33 UTC 2023
10/18/2023 3:29 PM, Mickaël Salaün пишет:
> On Mon, Oct 16, 2023 at 09:50:26AM +0800, Konstantin Meskhidze wrote:
>> This commit adds network rules support in the ruleset management
>
> Here are some advices to better write commit messages:
> https://docs.kernel.org/process/submitting-patches.html#describe-your-changes
> The "Describe your changes in imperative mood" part is important for
> this commit and others. Most of this patch series' commit messages need
> small updates.
Ok. I will refactor commit messages with "imperative mood". Thanks.
>
>> 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
>
> Please explain the "why" (when it makes sense) instead of just listing
> the "what".
Ok.
>
>> rights can be stored. Implement socket_bind() and socket_connect()
>> LSM hooks, which enables to restrict TCP socket binding and connection
>> to specific ports.
>
> I reworded and moved this part in last:
>> For the file system, a file descriptor is a direct access to a file/data.
>> But for the network, it's impossible to identify for which data/peer a
>> newly created socket will give access to, it's needed to wait for a
>> connect or bind request to identify the use case for this socket.
>> That's why the access rights (related to ports) are tied to an opened
>> socket, but this would not align with the way Landlock access control
>> works for the filesystem [2].
Thanks.
>
> Please add empty line to split paragraphs.
Got it.
>
>> The new landlock_net_port_attr structure has two fields. The allowed_access
>> field contains the LANDLOCK_ACCESS_NET_* rights. The port field contains
>> the port value according to the allowed protocol. This field can
>> take up to a 64-bit value [1] but the maximum value depends on the related
>> protocol (e.g. 16-bit for TCP).
>
> For the file system, a file descriptor is a direct access to a file/data.
> However, for network sockets, we cannot identify for which data or peer a newly
> created socket will give access to. Indeed, we need to wait for a connect or
> bind request to identify the use case for this socket.
>
> Access rights are not tied to socket file descriptors. Instead, bind and
> connect actions are controlled by the task's domain. As for the filesystem, a
> directory file descriptor may enable to open another file (i.e. a new data
> item), but this opening is restricted by the task's domain, not the file
> descriptor's access rights [2].
>
>>
>> [1]
>> https://lore.kernel.org/r/278ab07f-7583-a4e0-3d37-1bacd091531d@digikod.net
>> [2]
>> https://lore.kernel.org/all/263c1eb3-602f-57fe-8450-3f138581bee7@digikod.net
>
> [1] https://lore.kernel.org/r/278ab07f-7583-a4e0-3d37-1bacd091531d@digikod.net
> [2] https://lore.kernel.org/r/263c1eb3-602f-57fe-8450-3f138581bee7@digikod.net
>
Thanks.
>
>>
>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze at huawei.com>
>> Link: https://lore.kernel.org/r/20230920092641.832134-9-konstantin.meskhidze@huawei.com
>> [mic: Remove !ARCH_EPHEMERAL_INODES in Kconfig, and add landlock_ prefix
>> to add_rule_net_service()]
>> Signed-off-by: Mickaël Salaün <mic at digikod.net>
>> ---
>>
>> Changes since v12:
>> * Moves add_rule_net_port() back in syscalls.c and makes it static.
>> * Deletes bind_access_mask allowing bind action rule on port 0.
>> * Adds comment about port 0 in landlock_net_port_attr structure.
>> * Removes !ARCH_EPHEMERAL_INODES from Kconfig.
>> * Minor fixes.
>> * Refactors commit message.
>>
>> Changes since v11:
>> * Replaces dates with "2022-2023" in net.c/h files headers.
>> * Removes WARN_ON_ONCE(!domain) in check_socket_access().
>> * Using "typeof(*address)" instead of offsetofend(struct sockaddr, sa_family).
>> * Renames LANDLOCK_RULE_NET_SERVICE to LANDLOCK_RULE_NET_PORT.
>> * Renames landlock_net_service_attr to landlock_net_port_attr.
>> * Defines two add_rule_net_service() functions according to
>> IS_ENABLED(CONFIG_INET) instead of changing the body of the only
>> function.
>> * Adds af_family consistency check while handling AF_UNSPEC specifically.
>> * Adds bind_access_mask in add_rule_net_service() to deny all rules with bind
>> action on port zero.
>> * Minor fixes.
>> * Refactors commit message.
>>
>> 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 | 56 ++++++
>> security/landlock/Kconfig | 1 +
>> security/landlock/Makefile | 2 +
>> security/landlock/limits.h | 5 +
>> security/landlock/net.c | 198 +++++++++++++++++++
>> security/landlock/net.h | 33 ++++
>> security/landlock/ruleset.c | 62 +++++-
>> security/landlock/ruleset.h | 59 +++++-
>> security/landlock/setup.c | 2 +
>> security/landlock/syscalls.c | 69 ++++++-
>> tools/testing/selftests/landlock/base_test.c | 2 +-
>> 11 files changed, 466 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..25349666b19e 100644
>> --- a/include/uapi/linux/landlock.h
>> +++ b/include/uapi/linux/landlock.h
>> @@ -31,6 +31,12 @@ struct landlock_ruleset_attr {
>> * this access right.
>> */
>> __u64 handled_access_fs;
>> + /**
>> + * @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 +60,11 @@ enum landlock_rule_type {
>> * landlock_path_beneath_attr .
>> */
>> LANDLOCK_RULE_PATH_BENEATH = 1,
>> + /**
>> + * @LANDLOCK_RULE_NET_PORT: Type of a &struct
>> + * landlock_net_port_attr .
>> + */
>> + LANDLOCK_RULE_NET_PORT = 2,
>
> We don't need the explicit " = 2".
Fixed. Thanks.
>
>> };
>>
>> /**
>> @@ -79,6 +90,32 @@ struct landlock_path_beneath_attr {
>> */
>> } __attribute__((packed));
>>
>> +/**
>> + * struct landlock_net_port_attr - Network port definition
>> + *
>> + * Argument of sys_landlock_add_rule().
>> + */
>> +struct landlock_net_port_attr {
>> + /**
>> + * @allowed_access: Bitmask of allowed access network for a port
>> + * (cf. `Network flags`_).
>> + */
>> + __u64 allowed_access;
>> + /**
>> + * @port: Network port. Landlock does not forbid rules with port 0,
>> + * since some network services use it. Port 0 is a reserved one in
>> + * TCP/IP networking, meaning that it should not be used in TCP or
>> + * UDP messages. To allocate its source port number, services call
>> + * TCP/IP network functions like bind() to request one. With port 0
>> + * it triggers the operating system to automatically search for
>> + * and return a suitable available port in the TCP/IP dynamic
>> + * port number range. This port range can be controlled by a
>> + * sysadmin with /proc/sys/net/ipv4/ip_local_port_range sysctl,
>> + * which is also used by IPv6.
>
> This looks too inspired from
> https://www.lifewire.com/port-0-in-tcp-and-udp-818145
Yep. You are right.
>
> Let's make it simpler:
>
> * @port: Network port.
> *
> * It should be noted that port 0 passed to :manpage:`bind(2)` will
> * bind to an available port from a specific port range. This can be
> * configured thanks to the ``/proc/sys/net/ipv4/ip_local_port_range``
> * sysctl (also used for IPv6). A Landlock rule with port 0 and the
> * ``LANDLOCK_ACCESS_NET_BIND_TCP`` right means that requesting to bind
> * on port 0 is allowed and it will automatically translate to binding
> * on the related port range.
>
Thanks.
>
>> + */
>> + __u64 port;
>> +};
>> +
>> /**
>> * DOC: fs_access
>> *
>> @@ -189,4 +226,23 @@ 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.
>
> You can add:
> "This is supported since ABI 4."
Updated.
>
>> + *
>> + * 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 c1e862a38410..c4bf0d5eff39 100644
>> --- a/security/landlock/Kconfig
>> +++ b/security/landlock/Kconfig
>> @@ -3,6 +3,7 @@
>> config SECURITY_LANDLOCK
>> bool "Landlock support"
>> depends on SECURITY
>> + 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..93c9c6f91556 100644
>> --- a/security/landlock/limits.h
>> +++ b/security/landlock/limits.h
>> @@ -23,6 +23,11 @@
>> #define LANDLOCK_NUM_ACCESS_FS __const_hweight64(LANDLOCK_MASK_ACCESS_FS)
>> #define LANDLOCK_SHIFT_ACCESS_FS 0
>>
>> +#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 */
>>
>> #endif /* _SECURITY_LANDLOCK_LIMITS_H */
>> diff --git a/security/landlock/net.c b/security/landlock/net.c
>> new file mode 100644
>> index 000000000000..1bf26cf3c41b
>> --- /dev/null
>> +++ b/security/landlock/net.c
>> @@ -0,0 +1,198 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Landlock LSM - Network management and hooks
>> + *
>> + * Copyright © 2022-2023 Huawei Tech. Co., Ltd.
>> + * Copyright © 2022-2023 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,
>
> To be consistent with current_check_access_path(), please rename to
> current_check_access_socket().
Done. Thanks.
>
>> + 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();
>
> For consistency with other functions, s/domain/dom/g
Ok. Fixed.
>
>> +
>> + if (!domain)
>> + return 0;
>> + if (WARN_ON_ONCE(domain->num_layers < 1))
>> + return -EACCES;
>> +
>> + /* Checks if it's a (potential) TCP socket. */
>> + if (sock->type != SOCK_STREAM)
>> + return 0;
>> +
>> + /* Checks for minimal header length to safely read sa_family. */
>> + if (addrlen < offsetofend(typeof(*address), sa_family))
>> + return -EINVAL;
>> +
>> + switch (address->sa_family) {
>> + case AF_UNSPEC:
>> + case AF_INET:
>> + if (addrlen < sizeof(struct sockaddr_in))
>> + return -EINVAL;
>> + port = ((struct sockaddr_in *)address)->sin_port;
>> + break;
>> +#if IS_ENABLED(CONFIG_IPV6)
>> + case AF_INET6:
>> + if (addrlen < SIN6_LEN_RFC2133)
>> + return -EINVAL;
>> + port = ((struct sockaddr_in6 *)address)->sin6_port;
>> + break;
>> +#endif
>
> #endif /* IS_ENABLED(CONFIG_INET) */
#endif /* IS_ENABLED(CONFIG_IPV6) */ I suppose.
>
>> + default:
>> + return 0;
>> + }
>> +
>> + /* Specific AF_UNSPEC handling. */
>> + if (address->sa_family == 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.
>> + *
>> + * For a TCP access control system, this request is legitimate.
>> + * Let the network stack handle potential inconsistencies and
>> + * return -EINVAL if needed.
>> + */
>> + 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.
>> + *
>> + * We could return 0 and let the network stack handle these
>> + * checks, but it is safer to return a proper error and test
>> + * consistency thanks to kselftest.
>> + */
>> + if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) {
>> + /* addrlen has already been checked for AF_UNSPEC. */
>> + const struct sockaddr_in *const sockaddr =
>> + (struct sockaddr_in *)address;
>> +
>> + if (sock->sk->__sk_common.skc_family != AF_INET)
>> + return -EINVAL;
>> +
>> + if (sockaddr->sin_addr.s_addr != htonl(INADDR_ANY))
>> + return -EAFNOSUPPORT;
>> + }
>> + } else {
>> + /*
>> + * Checks sa_family consistency to not wrongfully return
>> + * -EACCES instead of -EINVAL. Valid sa_family changes are
>> + * only (from AF_INET or AF_INET6) to AF_UNSPEC.
>> + *
>> + * We could return 0 and let the network stack handle this
>> + * check, but it is safer to return a proper error and test
>> + * consistency thanks to kselftest.
>> + */
>> + if (address->sa_family != sock->sk->__sk_common.skc_family)
>> + return -EINVAL;
>> + }
>> +
>> + id.key.data = (__force uintptr_t)port;
>> + BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data));
>> +
>> + rule = landlock_find_rule(domain, id);
>> + handled_access = landlock_init_layer_masks(
>> + domain, access_request, &layer_masks, LANDLOCK_KEY_NET_PORT);
>> + if (landlock_unmask_layers(rule, handled_access, &layer_masks,
>> + ARRAY_SIZE(layer_masks)))
>> + return 0;
>> +
>> + return -EACCES;
>> +}
>> +
>> +static int hook_socket_bind(struct socket *const sock,
>> + struct sockaddr *const address, const int addrlen)
>> +{
>> + return check_socket_access(sock, address, addrlen,
>> + LANDLOCK_ACCESS_NET_BIND_TCP);
>> +}
>> +
>> +static int hook_socket_connect(struct socket *const sock,
>> + struct sockaddr *const address,
>> + const int addrlen)
>> +{
>> + return check_socket_access(sock, address, addrlen,
>> + LANDLOCK_ACCESS_NET_CONNECT_TCP);
>> +}
>> +
>> +static struct security_hook_list landlock_hooks[] __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..588a49fd6907
>> --- /dev/null
>> +++ b/security/landlock/net.h
>> @@ -0,0 +1,33 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +/*
>> + * Landlock LSM - Network management and hooks
>> + *
>> + * Copyright © 2022-2023 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,
>> + const u16 port, access_mask_t access_rights);
>> +#else /* IS_ENABLED(CONFIG_INET) */
>> +static inline void landlock_add_net_hooks(void)
>> +{
>> +}
>> +
>> +static inline int
>> +landlock_append_net_rule(struct landlock_ruleset *const ruleset, const u16 port,
>> + access_mask_t access_rights);
>> +{
>> + return -EAFNOSUPPORT;
>> +}
>> +#endif /* IS_ENABLED(CONFIG_INET) */
>> +
>> +#endif /* _SECURITY_LANDLOCK_NET_H */
>> diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
>> index 4c209acee01e..1fe4298ff4a7 100644
>> --- a/security/landlock/ruleset.c
>> +++ b/security/landlock/ruleset.c
>> @@ -36,6 +36,11 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers)
>> refcount_set(&new_ruleset->usage, 1);
>> mutex_init(&new_ruleset->lock);
>> new_ruleset->root_inode = RB_ROOT;
>> +
>> +#if IS_ENABLED(CONFIG_INET)
>> + new_ruleset->root_net_port = RB_ROOT;
>> +#endif /* IS_ENABLED(CONFIG_INET) */
>> +
>> new_ruleset->num_layers = num_layers;
>> /*
>> * hierarchy = NULL
>> @@ -46,16 +51,21 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers)
>> }
>>
>> struct landlock_ruleset *
>> -landlock_create_ruleset(const access_mask_t fs_access_mask)
>> +landlock_create_ruleset(const access_mask_t fs_access_mask,
>> + const access_mask_t net_access_mask)
>> {
>> struct landlock_ruleset *new_ruleset;
>>
>> /* Informs about useless ruleset. */
>> - if (!fs_access_mask)
>> + if (!fs_access_mask && !net_access_mask)
>> return ERR_PTR(-ENOMSG);
>> new_ruleset = create_ruleset(1);
>> - if (!IS_ERR(new_ruleset))
>> + if (IS_ERR(new_ruleset))
>> + return new_ruleset;
>> + if (fs_access_mask)
>> landlock_add_fs_access_mask(new_ruleset, fs_access_mask, 0);
>> + if (net_access_mask)
>> + landlock_add_net_access_mask(new_ruleset, net_access_mask, 0);
>
> This is good, but it is not tested: we need to add a test that both
> handle FS and net restrictions. You can add one in net.c, just handling
> LANDLOCK_ACCESS_FS_READ_DIR and LANDLOCK_ACCESS_NET_BIND_TCP, add one
> rule with path_beneath (e.g. /dev) and another with net_port, and check
> that open("/") is denied, open("/dev") is allowed, and and only the
> allowed port is allowed with bind(). This test should be simple and can
> only check against an IPv4 socket, i.e. using ipv4_tcp fixture, just
> after port_endianness. fcntl.h should then be included by net.c
Ok.
>
> I guess that was the purpose of layout1.with_net (in fs_test.c) but it
Yep. I added this kind of nest in fs_test.c to test both fs and
network rules together.
> is not complete. You can revamp this test and move it to net.c
> following the above suggestions, keeping it consistent with other tests
> in net.c . You don't need the test_open() nor create_ruleset() helpers.
>
> This test must failed if we change "ruleset->access_masks[layer_level] |="
> to "ruleset->access_masks[layer_level] =" in
> landlock_add_fs_access_mask() or landlock_add_net_access_mask().
Do you want to change it? Why?
Fs and network masks are ORed to not intersect with each other.
>
>> return new_ruleset;
>> }
>>
>> @@ -74,6 +84,11 @@ static bool is_object_pointer(const enum landlock_key_type key_type)
>> case LANDLOCK_KEY_INODE:
>> return true;
>>
>> +#if IS_ENABLED(CONFIG_INET)
>> + case LANDLOCK_KEY_NET_PORT:
>> + return false;
>> +#endif /* IS_ENABLED(CONFIG_INET) */
>> +
>> default:
>> WARN_ON_ONCE(1);
>> return false;
>> @@ -126,7 +141,13 @@ static struct rb_root *get_root(struct landlock_ruleset *const ruleset,
>> case LANDLOCK_KEY_INODE:
>> return &ruleset->root_inode;
>>
>> +#if IS_ENABLED(CONFIG_INET)
>> + case LANDLOCK_KEY_NET_PORT:
>> + return &ruleset->root_net_port;
>> +#endif /* IS_ENABLED(CONFIG_INET) */
>> +
>> default:
>> + WARN_ON_ONCE(1);
>
> Please move this WARN to the patch that added the previous and next
> lines.
OK. Will be moved.
>
>> return ERR_PTR(-EINVAL);
>> }
>> }
>> @@ -153,7 +174,8 @@ static void build_check_ruleset(void)
>> BUILD_BUG_ON(ruleset.num_rules < LANDLOCK_MAX_NUM_RULES);
>> BUILD_BUG_ON(ruleset.num_layers < LANDLOCK_MAX_NUM_LAYERS);
>> BUILD_BUG_ON(access_masks <
>> - (LANDLOCK_MASK_ACCESS_FS << LANDLOCK_SHIFT_ACCESS_FS));
>> + ((LANDLOCK_MASK_ACCESS_FS << LANDLOCK_SHIFT_ACCESS_FS) |
>> + (LANDLOCK_MASK_ACCESS_NET << LANDLOCK_SHIFT_ACCESS_NET)));
>> }
>>
>> /**
>> @@ -370,6 +392,13 @@ static int merge_ruleset(struct landlock_ruleset *const dst,
>> if (err)
>> goto out_unlock;
>>
>> +#if IS_ENABLED(CONFIG_INET)
>> + /* Merges the @src network port tree. */
>> + err = merge_tree(dst, src, LANDLOCK_KEY_NET_PORT);
>> + if (err)
>> + goto out_unlock;
>> +#endif /* IS_ENABLED(CONFIG_INET) */
>> +
>> out_unlock:
>> mutex_unlock(&src->lock);
>> mutex_unlock(&dst->lock);
>> @@ -426,6 +455,13 @@ static int inherit_ruleset(struct landlock_ruleset *const parent,
>> if (err)
>> goto out_unlock;
>>
>> +#if IS_ENABLED(CONFIG_INET)
>> + /* Copies the @parent network port tree. */
>> + err = inherit_tree(parent, child, LANDLOCK_KEY_NET_PORT);
>> + if (err)
>> + goto out_unlock;
>> +#endif /* IS_ENABLED(CONFIG_INET) */
>> +
>> if (WARN_ON_ONCE(child->num_layers <= parent->num_layers)) {
>> err = -EINVAL;
>> goto out_unlock;
>> @@ -455,6 +491,13 @@ static void free_ruleset(struct landlock_ruleset *const ruleset)
>> rbtree_postorder_for_each_entry_safe(freeme, next, &ruleset->root_inode,
>> node)
>> free_rule(freeme, LANDLOCK_KEY_INODE);
>> +
>> +#if IS_ENABLED(CONFIG_INET)
>> + rbtree_postorder_for_each_entry_safe(freeme, next,
>> + &ruleset->root_net_port, node)
>> + free_rule(freeme, LANDLOCK_KEY_NET_PORT);
>> +#endif /* IS_ENABLED(CONFIG_INET) */
>> +
>> put_hierarchy(ruleset->hierarchy);
>> kfree(ruleset);
>> }
>> @@ -635,7 +678,8 @@ get_access_mask_t(const struct landlock_ruleset *const ruleset,
>> *
>> * @domain: The domain that defines the current restrictions.
>> * @access_request: The requested access rights to check.
>> - * @layer_masks: The layer masks to populate.
>> + * @layer_masks: It must contain LANDLOCK_NUM_ACCESS_FS or LANDLOCK_NUM_ACCESS_NET
>
> "%LANDLOCK_NUM_ACCESS_FS or %LANDLOCK_NUM_ACCESS_NET"
Done.
>
>> + * elements according to @key_type.
>> * @key_type: The key type to switch between access masks of different types.
>> *
>> * Returns: An access mask where each access right bit is set which is handled
>> @@ -656,6 +700,14 @@ landlock_init_layer_masks(const struct landlock_ruleset *const domain,
>> get_access_mask = landlock_get_fs_access_mask;
>> num_access = LANDLOCK_NUM_ACCESS_FS;
>> break;
>> +
>> +#if IS_ENABLED(CONFIG_INET)
>> + case LANDLOCK_KEY_NET_PORT:
>> + get_access_mask = landlock_get_net_access_mask;
>> + num_access = LANDLOCK_NUM_ACCESS_NET;
>> + break;
>> +#endif /* IS_ENABLED(CONFIG_INET) */
>> +
>> default:
>> WARN_ON_ONCE(1);
>> return 0;
>> diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
>> index 1ede2b9a79b7..ba4a06035599 100644
>> --- a/security/landlock/ruleset.h
>> +++ b/security/landlock/ruleset.h
>> @@ -33,13 +33,16 @@
>> typedef u16 access_mask_t;
>> /* Makes sure all filesystem access rights can be stored. */
>> static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_FS);
>> +/* Makes sure all network access rights can be stored. */
>> +static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_NET);
>> /* Makes sure for_each_set_bit() and for_each_clear_bit() calls are OK. */
>> static_assert(sizeof(unsigned long) >= sizeof(access_mask_t));
>>
>> /* Ruleset access masks. */
>> -typedef u16 access_masks_t;
>> +typedef u32 access_masks_t;
>> /* Makes sure all ruleset access rights can be stored. */
>> -static_assert(BITS_PER_TYPE(access_masks_t) >= LANDLOCK_NUM_ACCESS_FS);
>> +static_assert(BITS_PER_TYPE(access_masks_t) >=
>> + LANDLOCK_NUM_ACCESS_FS + LANDLOCK_NUM_ACCESS_NET);
>>
>> typedef u16 layer_mask_t;
>> /* Makes sure all layers can be checked. */
>> @@ -84,6 +87,11 @@ enum landlock_key_type {
>> * keys.
>> */
>> LANDLOCK_KEY_INODE = 1,
>> + /**
>> + * @LANDLOCK_KEY_NET_PORT: Type of &landlock_ruleset.root_net_port's
>> + * node keys.
>> + */
>> + LANDLOCK_KEY_NET_PORT,
>> };
>>
>> /**
>> @@ -158,6 +166,13 @@ struct landlock_ruleset {
>> * reaches zero.
>> */
>> struct rb_root root_inode;
>
> #if IS_ENABLED(CONFIG_INET)
>
OK. Done.
>> + /**
>> + * @root_net_port: Root of a red-black tree containing &struct
>> + * landlock_rule nodes with network port. Once a ruleset is tied to a
>> + * process (i.e. as a domain), this tree is immutable until @usage
>> + * reaches zero.
>> + */
>> + struct rb_root root_net_port;
>
> #endif /* IS_ENABLED(CONFIG_INET) */
Done.
>
>> /**
>> * @hierarchy: Enables hierarchy identification even when a parent
>> * domain vanishes. This is needed for the ptrace protection.
>> @@ -196,13 +211,13 @@ struct landlock_ruleset {
>> */
>> u32 num_layers;
>> /**
>> - * @access_masks: Contains the subset of filesystem
>> - * actions that are restricted by a ruleset. A domain
>> - * saves all layers of merged rulesets in a stack
>> - * (FAM), starting from the first layer to the last
>> - * one. These layers are used when merging rulesets,
>> - * for user space backward compatibility (i.e.
>> - * future-proof), and to properly handle merged
>> + * @access_masks: Contains the subset of filesystem and
>> + * network actions that are restricted by a ruleset.
>> + * A domain saves all layers of merged rulesets in a
>> + * stack (FAM), starting from the first layer to the
>> + * last one. These layers are used when merging
>> + * rulesets, for user space backward compatibility
>> + * (i.e. future-proof), and to properly handle merged
>> * rulesets without overlapping access rights. These
>> * layers are set once and never changed for the
>> * lifetime of the ruleset.
>> @@ -213,7 +228,8 @@ struct landlock_ruleset {
>> };
>>
>> struct landlock_ruleset *
>> -landlock_create_ruleset(const access_mask_t access_mask);
>> +landlock_create_ruleset(const access_mask_t access_mask_fs,
>> + const access_mask_t access_mask_net);
>>
>> void landlock_put_ruleset(struct landlock_ruleset *const ruleset);
>> void landlock_put_ruleset_deferred(struct landlock_ruleset *const ruleset);
>> @@ -249,6 +265,19 @@ landlock_add_fs_access_mask(struct landlock_ruleset *const ruleset,
>> (fs_mask << LANDLOCK_SHIFT_ACCESS_FS);
>> }
>>
>> +static inline void
>> +landlock_add_net_access_mask(struct landlock_ruleset *const ruleset,
>> + const access_mask_t net_access_mask,
>> + const u16 layer_level)
>> +{
>> + access_mask_t net_mask = net_access_mask & LANDLOCK_MASK_ACCESS_NET;
>> +
>> + /* Should already be checked in sys_landlock_create_ruleset(). */
>> + WARN_ON_ONCE(net_access_mask != net_mask);
>> + ruleset->access_masks[layer_level] |=
>> + (net_mask << LANDLOCK_SHIFT_ACCESS_NET);
>> +}
>> +
>> static inline access_mask_t
>> landlock_get_raw_fs_access_mask(const struct landlock_ruleset *const ruleset,
>> const u16 layer_level)
>> @@ -266,6 +295,16 @@ landlock_get_fs_access_mask(const struct landlock_ruleset *const ruleset,
>> return landlock_get_raw_fs_access_mask(ruleset, layer_level) |
>> LANDLOCK_ACCESS_FS_INITIALLY_DENIED;
>> }
>> +
>> +static inline access_mask_t
>> +landlock_get_net_access_mask(const struct landlock_ruleset *const ruleset,
>> + const u16 layer_level)
>> +{
>> + return (ruleset->access_masks[layer_level] >>
>> + LANDLOCK_SHIFT_ACCESS_NET) &
>> + LANDLOCK_MASK_ACCESS_NET;
>> +}
>> +
>> bool landlock_unmask_layers(const struct landlock_rule *const rule,
>> const access_mask_t access_request,
>> layer_mask_t (*const layer_masks)[],
>> diff --git a/security/landlock/setup.c b/security/landlock/setup.c
>> index 0f6113528fa4..df81612811bf 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 __ro_after_init = false;
>>
>> @@ -29,6 +30,7 @@ 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 8a54e87dbb17..3ad652d9a146 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_port_attr net_port_attr;
>> + size_t ruleset_size, path_beneath_size, net_port_size;
>>
>> /*
>> * For each user space ABI structures, first checks that there is no
>> @@ -82,13 +84,19 @@ static void build_check_abi(void)
>> * struct size.
>> */
>> ruleset_size = sizeof(ruleset_attr.handled_access_fs);
>> + ruleset_size += sizeof(ruleset_attr.handled_access_net);
>> BUILD_BUG_ON(sizeof(ruleset_attr) != ruleset_size);
>> - BUILD_BUG_ON(sizeof(ruleset_attr) != 8);
>> + BUILD_BUG_ON(sizeof(ruleset_attr) != 16);
>>
>> path_beneath_size = sizeof(path_beneath_attr.allowed_access);
>> 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_port_size = sizeof(net_port_attr.allowed_access);
>> + net_port_size += sizeof(net_port_attr.port);
>> + BUILD_BUG_ON(sizeof(net_port_attr) != net_port_size);
>> + BUILD_BUG_ON(sizeof(net_port_attr) != 16);
>> }
>>
>> /* Ruleset handling */
>> @@ -129,7 +137,7 @@ static const struct file_operations ruleset_fops = {
>> .write = fop_dummy_write,
>> };
>>
>> -#define LANDLOCK_ABI_VERSION 3
>> +#define LANDLOCK_ABI_VERSION 4
>>
>> /**
>> * sys_landlock_create_ruleset - Create a new ruleset
>> @@ -188,8 +196,14 @@ SYSCALL_DEFINE3(landlock_create_ruleset,
>> LANDLOCK_MASK_ACCESS_FS)
>> return -EINVAL;
>>
>> + /* Checks network content (and 32-bits cast). */
>> + if ((ruleset_attr.handled_access_net | LANDLOCK_MASK_ACCESS_NET) !=
>> + LANDLOCK_MASK_ACCESS_NET)
>> + return -EINVAL;
>> +
>> /* Checks arguments and transforms to kernel struct. */
>> - ruleset = landlock_create_ruleset(ruleset_attr.handled_access_fs);
>> + ruleset = landlock_create_ruleset(ruleset_attr.handled_access_fs,
>> + ruleset_attr.handled_access_net);
>> if (IS_ERR(ruleset))
>> return PTR_ERR(ruleset);
>>
>> @@ -282,7 +296,7 @@ static int add_rule_path_beneath(struct landlock_ruleset *const ruleset,
>> int res, err;
>> access_mask_t mask;
>>
>> - /* Copies raw user space buffer, only one type for now. */
>> + /* Copies raw user space buffer. */
>
> Shouldn't this be part of a previous patch?
I did it according Gunter's suggestion
https://lore.kernel.org/netdev/20230627.82cde73b1efe@gnoack.org/
>
>> res = copy_from_user(&path_beneath_attr, rule_attr,
>> sizeof(path_beneath_attr));
>> if (res)
>> @@ -315,13 +329,49 @@ static int add_rule_path_beneath(struct landlock_ruleset *const ruleset,
>> return err;
>> }
>>
>> +static int add_rule_net_port(struct landlock_ruleset *ruleset,
>> + const void __user *const rule_attr)
>> +{
>> + struct landlock_net_port_attr net_port_attr;
>> + int res;
>> + access_mask_t mask;
>> +
>> + /* Copies raw user space buffer. */
>> + res = copy_from_user(&net_port_attr, rule_attr, sizeof(net_port_attr));
>> + if (res)
>> + return -EFAULT;
>> +
>> + /*
>> + * Informs about useless rule: empty allowed_access (i.e. deny rules)
>> + * are ignored by network actions.
>> + */
>> + if (!net_port_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_port_attr.allowed_access | mask) != mask)
>> + return -EINVAL;
>> +
>> + /* Denies inserting a rule with port higher than 65535. */
>
> For consistency with the following comment:
> "Denies inserting a rule with port greater than 65535."
>
Done. Thanks.
>
>> + if (net_port_attr.port > U16_MAX)
>> + return -EINVAL;
>> +
>> + /* Imports the new rule. */
>> + return landlock_append_net_rule(ruleset, net_port_attr.port,
>> + net_port_attr.allowed_access);
>> +}
>> +
>> /**
>> * 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_PORT.
>> * @rule_attr: Pointer to a rule (only of type &struct
>> * landlock_path_beneath_attr for now).
>> * @flags: Must be 0.
>> @@ -332,6 +382,8 @@ 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_PORT but TCP/IP is not
>
> %LANDLOCK_RULE_NET_PORT
Done.
>
>> + * 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
>
> &landlock_path_beneath_attr.allowed_access or
> &landlock_net_port_attr.allowed_access is not a subset of the
Fixed. Thanks.
>
>> * ruleset handled accesses);
>
> EINVAL description needs to be updated, especially for port > U16_MAX:
> - * ruleset handled accesses);
> + * ruleset handled accesses), or &landlock_net_port_attr.port is
> + greater than 65535;
Done. Thanks.
>
>
>> @@ -366,6 +418,9 @@ 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_PORT:
>> + err = add_rule_net_port(ruleset, rule_attr);
>> + break;
>> default:
>> err = -EINVAL;
>> break;
>> diff --git a/tools/testing/selftests/landlock/base_test.c b/tools/testing/selftests/landlock/base_test.c
>> index 792c3f0a59b4..646f778dfb1e 100644
>> --- a/tools/testing/selftests/landlock/base_test.c
>> +++ b/tools/testing/selftests/landlock/base_test.c
>> @@ -75,7 +75,7 @@ TEST(abi_version)
>> const struct landlock_ruleset_attr ruleset_attr = {
>> .handled_access_fs = LANDLOCK_ACCESS_FS_READ_FILE,
>> };
>> - ASSERT_EQ(3, landlock_create_ruleset(NULL, 0,
>> + ASSERT_EQ(4, landlock_create_ruleset(NULL, 0,
>> LANDLOCK_CREATE_RULESET_VERSION));
>>
>> ASSERT_EQ(-1, landlock_create_ruleset(&ruleset_attr, 0,
>> --
>> 2.25.1
>>
> .
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