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Message-ID: <07629a06-935c-debf-d490-e02e5ee9f9ec@huawei.com>
Date: Fri, 21 Apr 2023 12:39:01 +0300
From: "Konstantin Meskhidze (A)" <konstantin.meskhidze@...wei.com>
To: Mickaël Salaün <mic@...ikod.net>
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 v10 09/13] landlock: Add network rules and TCP hooks
support
4/16/2023 7:11 PM, Mickaël Salaün пишет:
>
> On 23/03/2023 09:52, 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 enable to restrict TCP socket binding and connection
>
> "which enables to"
>
Got it.
>
>> to specific ports.
>>
>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@...wei.com>
>> ---
>>
>> 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 | 49 +++++
>> security/landlock/Kconfig | 1 +
>> security/landlock/Makefile | 2 +
>> security/landlock/limits.h | 6 +-
>> security/landlock/net.c | 198 +++++++++++++++++++
>> 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, 450 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..09b70fb6a9a6 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;
>> +
>> + /**
>> + * @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 +91,24 @@ struct landlock_path_beneath_attr {
>> */
>> } __attribute__((packed));
>>
>> +/**
>> + * struct landlock_net_service_attr - TCP subnet definition
>> + *
>> + * 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;
>> +
>> +} __attribute__((packed));
>
> You can remove the empty line and the packed attribute.
>
Ok. Thanks.
>
>> +
>> /**
>> * DOC: fs_access
>> *
>> @@ -189,4 +219,23 @@ 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 */
>> #endif /* _SECURITY_LANDLOCK_LIMITS_H */
>> diff --git a/security/landlock/net.c b/security/landlock/net.c
>> new file mode 100644
>> index 000000000000..e19c339906e7
>> --- /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 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 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_addrlen(const struct sockaddr *const address, int addrlen)
>> +{
>> + if (addrlen < offsetofend(struct sockaddr, sa_family))
>> + return -EINVAL;
>> + switch (address->sa_family) {
>> + case AF_UNSPEC:
>> + case AF_INET:
>> + if (addrlen < sizeof(struct sockaddr_in))
>> + return -EINVAL;
>> + return 0;
>> +#if IS_ENABLED(CONFIG_IPV6)
>> + case AF_INET6:
>> + if (addrlen < SIN6_LEN_RFC2133)
>> + return -EINVAL;
>> + return 0;
>> +#endif
>> + }
>> + WARN_ON_ONCE(1);
>> + return 0;
>
> With this code, using any non-TCP socket would print a warning.
>
Yep. Already got this warning printed in tests with unix sockets.
I will refactor this part as you suggest below.
> All these switch/case make difficult to check consistency across
> check_addrlen() and get_port() helpers, they should be inlined into
> check_socket_access(), with only one switch statement, but we need to be
> careful about the return error orders: first EINVAL and after
> EAFNOSUPPORT. Inlining all this also enables to get rid of impossible
> cases (that lead to these WARN_ON_ONCE calls).
>
Got it. Thanks.
>
>
>> +}
>> +
>> +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 check_socket_access(struct socket *sock, struct sockaddr *address, int addrlen, u16 port,
>> + access_mask_t access_request)
>> +{
>> + int ret;
>> + 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,
>> + };
>> + const struct landlock_ruleset *const domain = get_current_net_domain();
>> +
>> + if (WARN_ON_ONCE(!domain))
>> + return 0;
>> + if (WARN_ON_ONCE(domain->num_layers < 1))
>> + return -EACCES;
>> + /* Check if it's a TCP socket. */
>> + if (sock->type != SOCK_STREAM)
>> + return 0;
>> +
>> + ret = check_addrlen(address, addrlen);
>> + if (ret)
>> + return ret;
>
> As explained above, this should be replaced with:
>
> if (addrlen < offsetofend(struct sockaddr, sa_family))
> return -EINVAL;
>
Ok.
>
>> +
>> + switch (address->sa_family) {
>
>
> This below block should be moved after the generic switch statement
> (i.e. once port is checked).
>
Do you mean checking address family after a port has been checked??
>
>
>> + case 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.
>> + */
>> + 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.
>> + */
>> + if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) {
>> + const struct sockaddr_in *const sockaddr =
>> + (struct sockaddr_in *)address;
>> +
>> + if (sockaddr->sin_addr.s_addr != htonl(INADDR_ANY))
>> + return -EAFNOSUPPORT;
>> + }
>> +
>> + fallthrough;
>
>
>
> 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
>
> /* Allows unhandled protocols. */
> default:
> return 0;
> }
>
> if (address->sa_family == AF_UNSPEC) {
>
> // Add here the above AF_UNSPEC checks to be consistent with the
> EINVAL/EAFNOSUPPORT return ordering.
>
> }
>
> id.key.data = (__force uintprt_t)port;
> BUID_BUG_ON(...);
>
Will be refactored. Thanks.
>
>
>> + rule = landlock_find_rule(domain, id);
>> + handled_access = landlock_init_layer_masks(
>> + domain, access_request, &layer_masks,
>> + LANDLOCK_KEY_NET_PORT);
>> + allowed = landlock_unmask_layers(rule, handled_access,
>> + &layer_masks,
>> + ARRAY_SIZE(layer_masks));
>> + }
>
> This curly brace can now be removed and the following return line is now OK.
>
Ok. Got it.
>
>> + return allowed ? 0 : -EACCES;
>> +}
>> +
>> +static int hook_socket_bind(struct socket *sock, struct sockaddr *address,
>> + int addrlen)
>> +{
>> + return check_socket_access(sock, address, addrlen, get_port(address),
>> + LANDLOCK_ACCESS_NET_BIND_TCP);
>> +}
>> +
>> +static int hook_socket_connect(struct socket *sock, struct sockaddr *address,
>> + int addrlen)
>> +{
>> + return check_socket_access(sock, address, addrlen, get_port(address),
>> + LANDLOCK_ACCESS_NET_CONNECT_TCP);
>> +}
>> +
>> +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..0da1d9dff5ab
>> --- /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,
>> + const u16 port, access_mask_t access_rights);
>> +#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/ruleset.c b/security/landlock/ruleset.c
>> index 14207b666095..53cb62701280 100644
>> --- a/security/landlock/ruleset.c
>> +++ b/security/landlock/ruleset.c
>> @@ -36,6 +36,9 @@ 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 +49,21 @@ 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);
>> return new_ruleset;
>> }
>>
>> @@ -73,6 +81,10 @@ static bool is_object_pointer(const enum landlock_key_type key_type)
>> switch (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) */
>> }
>> WARN_ON_ONCE(1);
>> return false;
>> @@ -126,6 +138,11 @@ static struct rb_root *get_root(struct landlock_ruleset *const ruleset,
>> case LANDLOCK_KEY_INODE:
>> root = &ruleset->root_inode;
>> break;
>> +#if IS_ENABLED(CONFIG_INET)
>> + case LANDLOCK_KEY_NET_PORT:
>> + root = &ruleset->root_net_port;
>> + break;
>> +#endif /* IS_ENABLED(CONFIG_INET) */
>> }
>> if (WARN_ON_ONCE(!root))
>> return ERR_PTR(-EINVAL);
>> @@ -154,7 +171,8 @@ 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)));
>> }
>>
>> /**
>> @@ -373,6 +391,12 @@ 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);
>> @@ -429,6 +453,12 @@ 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;
>> @@ -461,6 +491,11 @@ 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);
>> }
>> @@ -641,7 +676,8 @@ 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
>> + * 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
>> @@ -662,6 +698,12 @@ 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 2251e6048ccf..dcf7fbac8367 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 +87,13 @@ enum landlock_key_type {
>> * keys.
>> */
>> LANDLOCK_KEY_INODE = 1,
>> +#if IS_ENABLED(CONFIG_INET)
>> + /**
>> + * @LANDLOCK_KEY_NET_PORT: Type of &landlock_ruleset.root_net_port's
>> + * node keys.
>> + */
>> + LANDLOCK_KEY_NET_PORT = 2,
>> +#endif /* IS_ENABLED(CONFIG_INET) */
>> };
>>
>> /**
>> @@ -158,6 +168,15 @@ struct landlock_ruleset {
>> * reaches zero.
>> */
>> struct rb_root root_inode;
>> +#if IS_ENABLED(CONFIG_INET)
>> + /**
>> + * @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) */
>> /**
>> * @hierarchy: Enables hierarchy identification even when a parent
>> * domain vanishes. This is needed for the ptrace protection.
>> @@ -196,13 +215,13 @@ 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 +232,8 @@ 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 +269,19 @@ 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 +299,16 @@ 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 3f196d2ce4f9..7e4a598177b8 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;
>>
>> @@ -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..1f0edd605bc4 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
>> @@ -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_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) != 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);
>>
>> @@ -315,13 +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;
>> + access_mask_t 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 or more than U16_MAX. */
> "Denies inserting a rule with port 0 or higher than 65535."
>
> A test should check that it works with 65535 but not with 65536.
Got it.
>
>
>> + if ((net_service_attr.port == 0) || (net_service_attr.port > U16_MAX))
>> + 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;
>> +#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.
>> * @rule_attr: Pointer to a rule (only of type &struct
>> * landlock_path_beneath_attr for now).
>> * @flags: Must be 0.
>> @@ -332,6 +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
>> + * 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
>> * ruleset handled accesses);
>> @@ -366,6 +423,9 @@ 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;
>> 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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