diff mbox series

[v5,08/15] landlock: TCP network hooks implementation

Message ID 20220516152038.39594-9-konstantin.meskhidze@huawei.com (mailing list archive)
State Handled Elsewhere
Headers show
Series Network support for Landlock | expand

Commit Message

Konstantin Meskhidze (A) May 16, 2022, 3:20 p.m. UTC 
Support of socket_bind() and socket_connect() hooks.
Its possible to restrict binding and connecting of TCP
types of sockets to particular ports. Its just basic idea
how Landlock could support network confinement.

Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
---

Changes since v3:
* Split commit.
* Add SECURITY_NETWORK in config.
* Add IS_ENABLED(CONFIG_INET) if a kernel has no INET configuration.
* Add hook_socket_bind and hook_socket_connect hooks.

Changes since v4:
* Factors out CONFIG_INET into make file.
* Refactoring 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.
* Refactoring add_rule_net_service() and landlock_add_rule
syscall to support network rule inserting.
* Refactoring init_layer_masks() to support network rules.

---
 security/landlock/Kconfig    |   1 +
 security/landlock/Makefile   |   2 +
 security/landlock/net.c      | 159 +++++++++++++++++++++++++++++++++++
 security/landlock/net.h      |  25 ++++++
 security/landlock/ruleset.c  |  15 +++-
 security/landlock/setup.c    |   2 +
 security/landlock/syscalls.c |  63 ++++++++++++--
 7 files changed, 261 insertions(+), 6 deletions(-)
 create mode 100644 security/landlock/net.c
 create mode 100644 security/landlock/net.h

--
2.25.1

Comments

Mickaël Salaün May 17, 2022, 8:51 a.m. UTC | #1 
On 16/05/2022 17:20, Konstantin Meskhidze wrote:
> Support of socket_bind() and socket_connect() hooks.
> Its possible to restrict binding and connecting of TCP
> types of sockets to particular ports. Its just basic idea
> how Landlock could support network confinement.
> 
> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
> ---
> 
> Changes since v3:
> * Split commit.
> * Add SECURITY_NETWORK in config.
> * Add IS_ENABLED(CONFIG_INET) if a kernel has no INET configuration.
> * Add hook_socket_bind and hook_socket_connect hooks.
> 
> Changes since v4:
> * Factors out CONFIG_INET into make file.
> * Refactoring 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.
> * Refactoring add_rule_net_service() and landlock_add_rule
> syscall to support network rule inserting.
> * Refactoring init_layer_masks() to support network rules.
> 
> ---
>   security/landlock/Kconfig    |   1 +
>   security/landlock/Makefile   |   2 +
>   security/landlock/net.c      | 159 +++++++++++++++++++++++++++++++++++
>   security/landlock/net.h      |  25 ++++++
>   security/landlock/ruleset.c  |  15 +++-
>   security/landlock/setup.c    |   2 +
>   security/landlock/syscalls.c |  63 ++++++++++++--
>   7 files changed, 261 insertions(+), 6 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..9302e5891991
> --- /dev/null
> +++ b/security/landlock/net.c
> @@ -0,0 +1,159 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Landlock LSM - Network management and hooks
> + *
> + * Copyright (C) 2022 Huawei Tech. Co., Ltd.
> + */
> +
> +#include <linux/in.h>
> +#include <linux/net.h>
> +#include <linux/socket.h>
> +#include <net/ipv6.h>
> +
> +#include "cred.h"
> +#include "limits.h"
> +#include "net.h"
> +
> +int landlock_append_net_rule(struct landlock_ruleset *const ruleset,
> +			     u16 port, u32 access_rights)
> +{
> +	int err;
> +
> +	/* Transforms relative access rights to absolute ones. */
> +	access_rights |= LANDLOCK_MASK_ACCESS_NET &
> +			 ~landlock_get_net_access_mask(ruleset, 0);
> +
> +	BUILD_BUG_ON(sizeof(port) > sizeof(uintptr_t));
> +	mutex_lock(&ruleset->lock);
> +	err = landlock_insert_rule(ruleset, NULL, port,
> +				access_rights, LANDLOCK_RULE_NET_SERVICE);
> +	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;
> +
> +	if (WARN_ON_ONCE(!domain))
> +		return 0;
> +	if (WARN_ON_ONCE(domain->num_layers < 1))
> +		return -EACCES;
> +
> +	rule = landlock_find_rule(domain, port,
> +					LANDLOCK_RULE_NET_SERVICE);
> +
> +	handled_access = init_layer_masks(domain, access_request,
> +			&layer_masks, sizeof(layer_masks),
> +			LANDLOCK_RULE_NET_SERVICE);
> +	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:

Are you sure about that?

Please write a test for this case.


> +	case AF_INET:
> +	{

You don't need these braces (except if it is required by checkpatch.pl).


> +		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
> +	}

You missed some part of my patch… We should not get the port for a 
protocol we don't know, hence the WARN_ON_ONCE.


> +	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;
> +
> +	/* Get port value in host byte order */

I moved/removed this in my patch against v4 for a reason. Please, ask if 
you don't understand or if you don't agree with something I said.


> +	switch (address->sa_family) {
> +	case AF_UNSPEC:

Is this correct?

Please write a test for this case.

> +	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;
> +
> +	/* Get port value in host byte order */
> +	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;
> +		/*
> +		 * 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..da5ce8fa04cc
> --- /dev/null
> +++ b/security/landlock/net.h
> @@ -0,0 +1,25 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Landlock LSM - Network management and hooks
> + *
> + * Copyright (C) 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/ruleset.c b/security/landlock/ruleset.c
> index ea9ecb3f471a..317cf98890f6 100644
> --- a/security/landlock/ruleset.c
> +++ b/security/landlock/ruleset.c
> @@ -671,7 +671,7 @@ access_mask_t get_handled_accesses(
>   		}
>   		break;
>   	default:
> -		break;
> +		return 0;

Why?


>   	}
>   	return access_dom;
>   }
> @@ -763,6 +763,19 @@ access_mask_t init_layer_masks(const struct landlock_ruleset *const domain,
>   				}
>   			}
>   			break;
> +		case LANDLOCK_RULE_NET_SERVICE:
> +			for_each_set_bit(access_bit, &access_req,
> +					LANDLOCK_NUM_ACCESS_NET) {
> +				if (landlock_get_net_access_mask(domain,
> +								 layer_level) &
> +						BIT_ULL(access_bit)) {
> +					(*layer_masks)[access_bit] |=
> +						BIT_ULL(layer_level);
> +					handled_accesses |=
> +							   BIT_ULL(access_bit);
> +				}
> +			}
> +			break;
>   		default:
>   			return 0;
>   		}
> 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 812541f4e155..9454c6361011 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 */
> @@ -299,9 +306,9 @@ static int add_rule_path_beneath(struct landlock_ruleset *const ruleset,
>   	 * Informs about useless rule: empty allowed_access (i.e. deny rules)
>   	 * are ignored in path walks.
>   	 */
> -	if (!path_beneath_attr.allowed_access) {
> +	if (!path_beneath_attr.allowed_access)

Why?


>   		return -ENOMSG;
> -	}
> +
>   	/*
>   	 * Checks that allowed_access matches the @ruleset constraints
>   	 * (ruleset->access_masks[0] is automatically upgraded to 64-bits).
> @@ -323,13 +330,54 @@ 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 *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;
> +#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.
> @@ -340,6 +388,8 @@ 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 rule's
>    *   accesses);
> @@ -375,6 +425,9 @@ SYSCALL_DEFINE4(landlock_add_rule,
>   	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
>
Konstantin Meskhidze (A) May 19, 2022, 11:40 a.m. UTC | #2 
5/17/2022 11:51 AM, Mickaël Salaün пишет:
> 
> On 16/05/2022 17:20, Konstantin Meskhidze wrote:
>> Support of socket_bind() and socket_connect() hooks.
>> Its possible to restrict binding and connecting of TCP
>> types of sockets to particular ports. Its just basic idea
>> how Landlock could support network confinement.
>>
>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
>> ---
>>
>> Changes since v3:
>> * Split commit.
>> * Add SECURITY_NETWORK in config.
>> * Add IS_ENABLED(CONFIG_INET) if a kernel has no INET configuration.
>> * Add hook_socket_bind and hook_socket_connect hooks.
>>
>> Changes since v4:
>> * Factors out CONFIG_INET into make file.
>> * Refactoring 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.
>> * Refactoring add_rule_net_service() and landlock_add_rule
>> syscall to support network rule inserting.
>> * Refactoring init_layer_masks() to support network rules.
>>
>> ---
>>   security/landlock/Kconfig    |   1 +
>>   security/landlock/Makefile   |   2 +
>>   security/landlock/net.c      | 159 +++++++++++++++++++++++++++++++++++
>>   security/landlock/net.h      |  25 ++++++
>>   security/landlock/ruleset.c  |  15 +++-
>>   security/landlock/setup.c    |   2 +
>>   security/landlock/syscalls.c |  63 ++++++++++++--
>>   7 files changed, 261 insertions(+), 6 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..9302e5891991
>> --- /dev/null
>> +++ b/security/landlock/net.c
>> @@ -0,0 +1,159 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Landlock LSM - Network management and hooks
>> + *
>> + * Copyright (C) 2022 Huawei Tech. Co., Ltd.
>> + */
>> +
>> +#include <linux/in.h>
>> +#include <linux/net.h>
>> +#include <linux/socket.h>
>> +#include <net/ipv6.h>
>> +
>> +#include "cred.h"
>> +#include "limits.h"
>> +#include "net.h"
>> +
>> +int landlock_append_net_rule(struct landlock_ruleset *const ruleset,
>> +                 u16 port, u32 access_rights)
>> +{
>> +    int err;
>> +
>> +    /* Transforms relative access rights to absolute ones. */
>> +    access_rights |= LANDLOCK_MASK_ACCESS_NET &
>> +             ~landlock_get_net_access_mask(ruleset, 0);
>> +
>> +    BUILD_BUG_ON(sizeof(port) > sizeof(uintptr_t));
>> +    mutex_lock(&ruleset->lock);
>> +    err = landlock_insert_rule(ruleset, NULL, port,
>> +                access_rights, LANDLOCK_RULE_NET_SERVICE);
>> +    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;
>> +
>> +    if (WARN_ON_ONCE(!domain))
>> +        return 0;
>> +    if (WARN_ON_ONCE(domain->num_layers < 1))
>> +        return -EACCES;
>> +
>> +    rule = landlock_find_rule(domain, port,
>> +                    LANDLOCK_RULE_NET_SERVICE);
>> +
>> +    handled_access = init_layer_masks(domain, access_request,
>> +            &layer_masks, sizeof(layer_masks),
>> +            LANDLOCK_RULE_NET_SERVICE);
>> +    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:
> 
> Are you sure about that?
> 
> Please write a test for this case.
> 
   I checked the logic in Selinux LSM in a bind() hook and AF_UNSPEC
family is treated as AF_INET (only for INADDR_ANY address)  but we can 
discuss it.
> 
>> +    case AF_INET:
>> +    {
> 
> You don't need these braces (except if it is required by checkpatch.pl).
> 
   I got compilation error without braces:
...
error: a label can only be part of a statement and a declaration is not 
a statement
    67 |   const struct sockaddr_in *const sockaddr =
...
  so I added braces.
> 
>> +        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
>> +    }
> 
> You missed some part of my patch… We should not get the port for a 
> protocol we don't know, hence the WARN_ON_ONCE.
> 
  Sorry. I manually updated the code and missed that. I will fix it.
> 
>> +    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;
>> +
>> +    /* Get port value in host byte order */
> 
> I moved/removed this in my patch against v4 for a reason. Please, ask if 
> you don't understand or if you don't agree with something I said.
> 
   Sorry. I updated your changed manually and missed that.
   Will be fixed.
> 
>> +    switch (address->sa_family) {
>> +    case AF_UNSPEC:
> 
> Is this correct?

Actually I did'not find any issue with bind() using AF_UNSPEC family.
(instead of connect() one and we came to an agreement that it must be 
banned). So I checked athoner LSMs like Selinux and found out that
it treats bind() hook with AF_UNSPEC family as with AF_INET one.
But Selinux allows AF_UNSPEC family only for INADDR_ANY address and
I cant understand the reason now. So I let AF_UNSPEC family bind()
hook for any address, but we can discuss it. What do you think?
> 
> Please write a test for this case.
> 
  I have one. Please check it in connect_afunspec_with_restictions
  test:

...
  /* Enforces the ruleset. */
	enforce_ruleset(_metadata, ruleset_fd_1);

	/* Creates a server socket 1 */
	sockfd = create_socket(_metadata, false, false);
	ASSERT_LE(0, sockfd);

	/* Binds the socket 1 to address with port[0] with AF_UNSPEC
            family */
	self->addr4[0].sin_family = AF_UNSPEC;
	ASSERT_EQ(0, bind(sockfd, (struct sockaddr *)&self->addr4[0],
                           sizeof(self->addr4[0])));

	/* Makes connection to socket with port[0] */
	ASSERT_EQ(0, connect(sockfd, (struct sockaddr *)&self->addr4[0],
			     sizeof(self->addr4[0])));

	const int ruleset_fd_2 =
                              landlock_create_ruleset(&ruleset_attr_2,
					sizeof(ruleset_attr_2), 0);
	ASSERT_LE(0, ruleset_fd_2);

	/* Allows connect and bind operations to the port[0] socket */
	ASSERT_EQ(0, landlock_add_rule(ruleset_fd_2, 	
                                        LANDLOCK_RULE_NET_SERVICE,
				       &net_service_2, 0));
...
>> +    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;
>> +
>> +    /* Get port value in host byte order */
>> +    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;
>> +        /*
>> +         * 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..da5ce8fa04cc
>> --- /dev/null
>> +++ b/security/landlock/net.h
>> @@ -0,0 +1,25 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Landlock LSM - Network management and hooks
>> + *
>> + * Copyright (C) 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/ruleset.c b/security/landlock/ruleset.c
>> index ea9ecb3f471a..317cf98890f6 100644
>> --- a/security/landlock/ruleset.c
>> +++ b/security/landlock/ruleset.c
>> @@ -671,7 +671,7 @@ access_mask_t get_handled_accesses(
>>           }
>>           break;
>>       default:
>> -        break;
>> +        return 0;
> 
> Why?

   You are right - this is useless code, cause anyway 0 is retured in 
default rule_type. Will be fixed.
> 
> 
>>       }
>>       return access_dom;
>>   }
>> @@ -763,6 +763,19 @@ access_mask_t init_layer_masks(const struct 
>> landlock_ruleset *const domain,
>>                   }
>>               }
>>               break;
>> +        case LANDLOCK_RULE_NET_SERVICE:
>> +            for_each_set_bit(access_bit, &access_req,
>> +                    LANDLOCK_NUM_ACCESS_NET) {
>> +                if (landlock_get_net_access_mask(domain,
>> +                                 layer_level) &
>> +                        BIT_ULL(access_bit)) {
>> +                    (*layer_masks)[access_bit] |=
>> +                        BIT_ULL(layer_level);
>> +                    handled_accesses |=
>> +                               BIT_ULL(access_bit);
>> +                }
>> +            }
>> +            break;
>>           default:
>>               return 0;
>>           }
>> 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 812541f4e155..9454c6361011 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 */
>> @@ -299,9 +306,9 @@ static int add_rule_path_beneath(struct 
>> landlock_ruleset *const ruleset,
>>        * Informs about useless rule: empty allowed_access (i.e. deny 
>> rules)
>>        * are ignored in path walks.
>>        */
>> -    if (!path_beneath_attr.allowed_access) {
>> +    if (!path_beneath_attr.allowed_access)
> 
> Why?

  Unnecessary braces for single statement blocks.
  I got a warning by scripts/checkpatch.pl:

   WARNING: braces {} are not necessary for single statement blocks
#309: FILE: security/landlock/syscalls.c:309:
+       if (!path_beneath_attr.allowed_access) {
+               return -ENOMSG;
+       }

> 
> 
>>           return -ENOMSG;
>> -    }
>> +
>>       /*
>>        * Checks that allowed_access matches the @ruleset constraints
>>        * (ruleset->access_masks[0] is automatically upgraded to 64-bits).
>> @@ -323,13 +330,54 @@ 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 *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;
>> +#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.
>> @@ -340,6 +388,8 @@ 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 rule's
>>    *   accesses);
>> @@ -375,6 +425,9 @@ SYSCALL_DEFINE4(landlock_add_rule,
>>       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
>>
> .
diff mbox series

Patch

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..9302e5891991
--- /dev/null
+++ b/security/landlock/net.c
@@ -0,0 +1,159 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Landlock LSM - Network management and hooks
+ *
+ * Copyright (C) 2022 Huawei Tech. Co., Ltd.
+ */
+
+#include <linux/in.h>
+#include <linux/net.h>
+#include <linux/socket.h>
+#include <net/ipv6.h>
+
+#include "cred.h"
+#include "limits.h"
+#include "net.h"
+
+int landlock_append_net_rule(struct landlock_ruleset *const ruleset,
+			     u16 port, u32 access_rights)
+{
+	int err;
+
+	/* Transforms relative access rights to absolute ones. */
+	access_rights |= LANDLOCK_MASK_ACCESS_NET &
+			 ~landlock_get_net_access_mask(ruleset, 0);
+
+	BUILD_BUG_ON(sizeof(port) > sizeof(uintptr_t));
+	mutex_lock(&ruleset->lock);
+	err = landlock_insert_rule(ruleset, NULL, port,
+				access_rights, LANDLOCK_RULE_NET_SERVICE);
+	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;
+
+	if (WARN_ON_ONCE(!domain))
+		return 0;
+	if (WARN_ON_ONCE(domain->num_layers < 1))
+		return -EACCES;
+
+	rule = landlock_find_rule(domain, port,
+					LANDLOCK_RULE_NET_SERVICE);
+
+	handled_access = init_layer_masks(domain, access_request,
+			&layer_masks, sizeof(layer_masks),
+			LANDLOCK_RULE_NET_SERVICE);
+	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
+	}
+	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;
+
+	/* Get port value in host byte order */
+	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;
+
+	/* Get port value in host byte order */
+	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;
+		/*
+		 * 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..da5ce8fa04cc
--- /dev/null
+++ b/security/landlock/net.h
@@ -0,0 +1,25 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Landlock LSM - Network management and hooks
+ *
+ * Copyright (C) 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/ruleset.c b/security/landlock/ruleset.c
index ea9ecb3f471a..317cf98890f6 100644
--- a/security/landlock/ruleset.c
+++ b/security/landlock/ruleset.c
@@ -671,7 +671,7 @@  access_mask_t get_handled_accesses(
 		}
 		break;
 	default:
-		break;
+		return 0;
 	}
 	return access_dom;
 }
@@ -763,6 +763,19 @@  access_mask_t init_layer_masks(const struct landlock_ruleset *const domain,
 				}
 			}
 			break;
+		case LANDLOCK_RULE_NET_SERVICE:
+			for_each_set_bit(access_bit, &access_req,
+					LANDLOCK_NUM_ACCESS_NET) {
+				if (landlock_get_net_access_mask(domain,
+								 layer_level) &
+						BIT_ULL(access_bit)) {
+					(*layer_masks)[access_bit] |=
+						BIT_ULL(layer_level);
+					handled_accesses |=
+							   BIT_ULL(access_bit);
+				}
+			}
+			break;
 		default:
 			return 0;
 		}
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 812541f4e155..9454c6361011 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 */
@@ -299,9 +306,9 @@  static int add_rule_path_beneath(struct landlock_ruleset *const ruleset,
 	 * Informs about useless rule: empty allowed_access (i.e. deny rules)
 	 * are ignored in path walks.
 	 */
-	if (!path_beneath_attr.allowed_access) {
+	if (!path_beneath_attr.allowed_access)
 		return -ENOMSG;
-	}
+
 	/*
 	 * Checks that allowed_access matches the @ruleset constraints
 	 * (ruleset->access_masks[0] is automatically upgraded to 64-bits).
@@ -323,13 +330,54 @@  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 *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;
+#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.
@@ -340,6 +388,8 @@  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 rule's
  *   accesses);
@@ -375,6 +425,9 @@  SYSCALL_DEFINE4(landlock_add_rule,
 	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;