[PATCH v13 08/12] landlock: Add network rules and TCP hooks support
Mickaël Salaün
mic at digikod.net
Wed Oct 18 16:34:44 UTC 2023
On Mon, Oct 16, 2023 at 09:50:26AM +0800, Konstantin Meskhidze wrote:
> This commit adds network rules support in the ruleset management
> helpers and the landlock_create_ruleset syscall.
> Refactor user space API to support network actions. Add new network
> access flags, network rule and network attributes. Increment Landlock
> ABI version. Expand access_masks_t to u32 to be sure network access
> rights can be stored. Implement socket_bind() and socket_connect()
> LSM hooks, which enables to restrict TCP socket binding and connection
> to specific ports.
> 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].
> 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).
>
> [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
>
> 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,
> };
>
> /**
> @@ -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.
> + */
> + __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.
> + *
> + * 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,
> + struct sockaddr *const address,
> + const int addrlen,
> + const access_mask_t access_request)
> +{
> + __be16 port;
> + layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_NET] = {};
> + const struct landlock_rule *rule;
> + access_mask_t handled_access;
> + struct landlock_id id = {
> + .type = LANDLOCK_KEY_NET_PORT,
> + };
> + const struct landlock_ruleset *const domain = get_current_net_domain();
> +
> + if (!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
> + 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);
> 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);
> 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
> + * 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;
> + /**
> + * @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;
> /**
> * @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. */
> 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).
> + */
You can replace this comment block with that:
+ /* Checks that allowed_access matches the @ruleset constraints. */
> + 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. */
> + 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);
> +}
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