[RFC PATCH v2 01/12] landlock: Support socket access-control
Günther Noack
gnoack at google.com
Mon May 27 09:57:13 UTC 2024
On Fri, May 24, 2024 at 05:30:04PM +0800, Mikhail Ivanov wrote:
> * Add new landlock rule type that corresponds to the restriction of
> socket protocols. This is represented as an landlock_socket_attr
> structure. Protocol allowed by landlock must be described by
> a family-type pair (see socket(2)).
>
> * Support socket rule storage in landlock ruleset.
>
> * Add flag LANDLOCK_ACCESS_SOCKET_CREATE that will provide the
> ability to control socket creation.
>
> * Add socket.c file that will contain socket rules management and hooks.
> Implement helper pack_socket_key() to convert 32-bit family and type
> values into uintptr_t. This is possible due to the fact that these
> values are limited to AF_MAX (=46), SOCK_MAX (=11) constants. Assumption
> is checked in build-time by the helper.
>
> * Support socket rules in landlock syscalls. Change ABI version to 6.
>
> Closes: https://github.com/landlock-lsm/linux/issues/6
> Signed-off-by: Mikhail Ivanov <ivanov.mikhail1 at huawei-partners.com>
> ---
>
> Changes since v1:
> * Reverts landlock_key.data type from u64 to uinptr_t.
> * Adds helper to pack domain and type values into uintptr_t.
> * Denies inserting socket rule with invalid family and type.
> * Renames 'domain' to 'family' in landlock_socket_attr.
> * Updates ABI version to 6 since ioctl patches changed it to 5.
> * Formats code with clang-format.
> * Minor fixes.
> ---
> include/uapi/linux/landlock.h | 53 +++++++++++++++-
> security/landlock/Makefile | 2 +-
> security/landlock/limits.h | 5 ++
> security/landlock/ruleset.c | 37 ++++++++++-
> security/landlock/ruleset.h | 41 +++++++++++-
> security/landlock/socket.c | 60 ++++++++++++++++++
> security/landlock/socket.h | 17 +++++
> security/landlock/syscalls.c | 66 ++++++++++++++++++--
> tools/testing/selftests/landlock/base_test.c | 2 +-
> 9 files changed, 272 insertions(+), 11 deletions(-)
> create mode 100644 security/landlock/socket.c
> create mode 100644 security/landlock/socket.h
>
> diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h
> index 68625e728f43..a25ba5983dfb 100644
> --- a/include/uapi/linux/landlock.h
> +++ b/include/uapi/linux/landlock.h
> @@ -37,6 +37,13 @@ struct landlock_ruleset_attr {
> * rule explicitly allow them.
> */
> __u64 handled_access_net;
> +
> + /**
> + * @handled_access_socket: Bitmask of actions (cf. `Socket flags`_)
> + * that is handled by this ruleset and should then be forbidden if no
> + * rule explicitly allow them.
> + */
> + __u64 handled_access_socket;
> };
>
> /*
> @@ -65,6 +72,11 @@ enum landlock_rule_type {
> * landlock_net_port_attr .
> */
> LANDLOCK_RULE_NET_PORT,
> + /**
> + * @LANDLOCK_RULE_SOCKET: Type of a &struct
> + * landlock_socket_attr .
> + */
> + LANDLOCK_RULE_SOCKET,
> };
>
> /**
> @@ -115,6 +127,28 @@ struct landlock_net_port_attr {
> __u64 port;
> };
>
> +/**
> + * struct landlock_socket_attr - Socket definition
> + *
> + * Argument of sys_landlock_add_rule().
> + */
> +struct landlock_socket_attr {
> + /**
> + * @allowed_access: Bitmask of allowed access for a socket
> + * (cf. `Socket flags`_).
> + */
> + __u64 allowed_access;
> + /**
> + * @family: Protocol family used for communication
> + * (same as domain in socket(2)).
> + */
> + int family;
> + /**
> + * @type: Socket type (see socket(2)).
> + */
> + int type;
> +};
Regarding the naming of struct landlock_socket_attr and the associated
LANDLOCK_RULE_SOCKET enum:
For the two existing rule types LANDLOCK_RULE_PATH_BENEATH (struct
landlock_path_beneath_attr) and LANDLOCK_RULE_NET_PORT (struct
landlock_net_port_attr), the names of the rule types are describing the
*properties* by which we are filtering (path *beneath*, *network port*), rather
than just the kind of object that we are filtering on.
Should the new enum and struct maybe be called differently as well to match that
convention? Maybe LANDLOCK_RULE_SOCKET_FAMILY_TYPE and struct
landlock_socket_family_type_attr?
Are there *other* properties apart from family and type, by which you are
thinking of restricting the use of sockets in the future?
> @@ -266,4 +300,21 @@ struct landlock_net_port_attr {
> #define LANDLOCK_ACCESS_NET_BIND_TCP (1ULL << 0)
> #define LANDLOCK_ACCESS_NET_CONNECT_TCP (1ULL << 1)
> /* clang-format on */
> +
> +/**
> + * DOC: socket_access
> + *
> + * Socket flags
> + * ~~~~~~~~~~~~
> + *
> + * These flags enable to restrict a sanboxed process to a set of socket
> + * protocols. This is supported since the Landlock ABI version 6.
(Some phrasing remarks)
* typo in "sanboxed"
* Optional grammar nit: you can drop the "the" in front of "Landlock ABI
version 6" (or alternatively use the phrasing as it was used in the FS
restriction docs)
* Grammar nit: The use of "enable to" sounds weird in my ears (but I am not a
native speaker either). I think it could just be dropped here ("These flags
restrict a sandboxed process..." or "These flags control the use of...").
I realize that the wording was used in other places already, so it's just an
optional remark.
(More about the content)
The Landlock documentation states the general approach up front:
A Landlock rule describes an *action* on an *object* which the process intends
to perform.
(In your case, the object is a socket, and the action is the socket's creation.
The Landlock rules describe predicates on objects to restrict the set of actions
through the access_mask_t.)
The implementation is perfectly in line with that, but it would help to phrase
the documentation also in terms of that framework. That means, what we are
restricting are *actions*, not protocols.
To make a more constructive suggestion:
"These flags restrict actions on sockets for a sandboxed process (e.g. socket
creation)."
Does it also need the following addition?
"Sockets opened before sandboxing are not subject to these restrictions."
> + *
> + * The following access rights apply only to sockets:
^^^^^^^^^^^^^^^^^^^
Probably better to use singular for now: "access right applies".
> + *
> + * - %LANDLOCK_ACCESS_SOCKET_CREATE: Create a socket.
Can we be more specific here what operations are affected by this? It is rather
obvious that this affects socket(2), but does this also affect accept(2) and
connect(2)?
A scenario that I could imagine being useful is to sandbox a TCP server like
this:
* create a socket, bind(2) and listen(2)
* sandbox yourself so that no new sockets can be created with socket(2)
* go into the main loop and start accept(2)ing new connections
Is this an approach that would work with this patch set?
(It might make a neat sample tool as well, if something like this works :))
Regarding the list of socket access rights with only one item in it:
I am still unsure what other socket actions are in scope in the future; it would
probably help to phrase the documentation in those terms. (listen(2), bind(2),
connect(2), shutdown(2)? On the other hand, bind(2) and connect(2) for TCP are
already restrictable differently.))
> + */
> +/* clang-format off */
> +#define LANDLOCK_ACCESS_SOCKET_CREATE (1ULL << 0)
> +/* clang-format on */
> #endif /* _UAPI_LINUX_LANDLOCK_H */
> diff --git a/security/landlock/Makefile b/security/landlock/Makefile
> index b4538b7cf7d2..ff1dd98f6a1b 100644
> --- a/security/landlock/Makefile
> +++ b/security/landlock/Makefile
> @@ -1,6 +1,6 @@
> obj-$(CONFIG_SECURITY_LANDLOCK) := landlock.o
>
> landlock-y := setup.o syscalls.o object.o ruleset.o \
> - cred.o task.o fs.o
> + cred.o task.o fs.o socket.o
>
> landlock-$(CONFIG_INET) += net.o
> diff --git a/security/landlock/limits.h b/security/landlock/limits.h
> index 20fdb5ff3514..448b4d596783 100644
> --- a/security/landlock/limits.h
> +++ b/security/landlock/limits.h
> @@ -28,6 +28,11 @@
> #define LANDLOCK_NUM_ACCESS_NET __const_hweight64(LANDLOCK_MASK_ACCESS_NET)
> #define LANDLOCK_SHIFT_ACCESS_NET LANDLOCK_NUM_ACCESS_FS
>
> +#define LANDLOCK_LAST_ACCESS_SOCKET LANDLOCK_ACCESS_SOCKET_CREATE
> +#define LANDLOCK_MASK_ACCESS_SOCKET ((LANDLOCK_LAST_ACCESS_SOCKET << 1) - 1)
> +#define LANDLOCK_NUM_ACCESS_SOCKET __const_hweight64(LANDLOCK_MASK_ACCESS_SOCKET)
> +#define LANDLOCK_SHIFT_ACCESS_SOCKET LANDLOCK_NUM_ACCESS_SOCKET
> +
> /* clang-format on */
>
> #endif /* _SECURITY_LANDLOCK_LIMITS_H */
> diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
> index e0a5fbf9201a..c782f7cd313d 100644
> --- a/security/landlock/ruleset.c
> +++ b/security/landlock/ruleset.c
> @@ -40,6 +40,7 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers)
> #if IS_ENABLED(CONFIG_INET)
> new_ruleset->root_net_port = RB_ROOT;
> #endif /* IS_ENABLED(CONFIG_INET) */
> + new_ruleset->root_socket = RB_ROOT;
>
> new_ruleset->num_layers = num_layers;
> /*
> @@ -52,12 +53,13 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers)
>
> struct landlock_ruleset *
> landlock_create_ruleset(const access_mask_t fs_access_mask,
> - const access_mask_t net_access_mask)
> + const access_mask_t net_access_mask,
> + const access_mask_t socket_access_mask)
> {
> struct landlock_ruleset *new_ruleset;
>
> /* Informs about useless ruleset. */
> - if (!fs_access_mask && !net_access_mask)
> + if (!fs_access_mask && !net_access_mask && !socket_access_mask)
> return ERR_PTR(-ENOMSG);
> new_ruleset = create_ruleset(1);
> if (IS_ERR(new_ruleset))
> @@ -66,6 +68,9 @@ landlock_create_ruleset(const access_mask_t 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);
> + if (socket_access_mask)
> + landlock_add_socket_access_mask(new_ruleset, socket_access_mask,
> + 0);
> return new_ruleset;
> }
>
> @@ -89,6 +94,9 @@ static bool is_object_pointer(const enum landlock_key_type key_type)
> return false;
> #endif /* IS_ENABLED(CONFIG_INET) */
>
> + case LANDLOCK_KEY_SOCKET:
> + return false;
> +
> default:
> WARN_ON_ONCE(1);
> return false;
> @@ -146,6 +154,9 @@ static struct rb_root *get_root(struct landlock_ruleset *const ruleset,
> return &ruleset->root_net_port;
> #endif /* IS_ENABLED(CONFIG_INET) */
>
> + case LANDLOCK_KEY_SOCKET:
> + return &ruleset->root_socket;
> +
> default:
> WARN_ON_ONCE(1);
> return ERR_PTR(-EINVAL);
> @@ -175,7 +186,9 @@ static void build_check_ruleset(void)
> 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_NET << LANDLOCK_SHIFT_ACCESS_NET)));
> + (LANDLOCK_MASK_ACCESS_NET << LANDLOCK_SHIFT_ACCESS_NET) |
> + (LANDLOCK_MASK_ACCESS_SOCKET
> + << LANDLOCK_SHIFT_ACCESS_SOCKET)));
> }
>
> /**
> @@ -399,6 +412,11 @@ static int merge_ruleset(struct landlock_ruleset *const dst,
> goto out_unlock;
> #endif /* IS_ENABLED(CONFIG_INET) */
>
> + /* Merges the @src socket tree. */
> + err = merge_tree(dst, src, LANDLOCK_KEY_SOCKET);
> + if (err)
> + goto out_unlock;
> +
> out_unlock:
> mutex_unlock(&src->lock);
> mutex_unlock(&dst->lock);
> @@ -462,6 +480,11 @@ static int inherit_ruleset(struct landlock_ruleset *const parent,
> goto out_unlock;
> #endif /* IS_ENABLED(CONFIG_INET) */
>
> + /* Copies the @parent socket tree. */
> + err = inherit_tree(parent, child, LANDLOCK_KEY_SOCKET);
> + if (err)
> + goto out_unlock;
> +
> if (WARN_ON_ONCE(child->num_layers <= parent->num_layers)) {
> err = -EINVAL;
> goto out_unlock;
> @@ -498,6 +521,10 @@ static void free_ruleset(struct landlock_ruleset *const ruleset)
> free_rule(freeme, LANDLOCK_KEY_NET_PORT);
> #endif /* IS_ENABLED(CONFIG_INET) */
>
> + rbtree_postorder_for_each_entry_safe(freeme, next,
> + &ruleset->root_socket, node)
> + free_rule(freeme, LANDLOCK_KEY_SOCKET);
> +
> put_hierarchy(ruleset->hierarchy);
> kfree(ruleset);
> }
> @@ -708,6 +735,10 @@ landlock_init_layer_masks(const struct landlock_ruleset *const domain,
> break;
> #endif /* IS_ENABLED(CONFIG_INET) */
>
> + case LANDLOCK_KEY_SOCKET:
> + get_access_mask = landlock_get_socket_access_mask;
> + num_access = LANDLOCK_NUM_ACCESS_SOCKET;
> + break;
> default:
> WARN_ON_ONCE(1);
> return 0;
> diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
> index c7f1526784fd..a9773efd529b 100644
> --- a/security/landlock/ruleset.h
> +++ b/security/landlock/ruleset.h
> @@ -92,6 +92,12 @@ enum landlock_key_type {
> * node keys.
> */
> LANDLOCK_KEY_NET_PORT,
> +
> + /**
> + * @LANDLOCK_KEY_SOCKET: Type of &landlock_ruleset.root_socket's
> + * node keys.
> + */
> + LANDLOCK_KEY_SOCKET,
> };
>
> /**
> @@ -177,6 +183,15 @@ struct landlock_ruleset {
> struct rb_root root_net_port;
> #endif /* IS_ENABLED(CONFIG_INET) */
>
> + /**
> + * @root_socket: Root of a red-black tree containing &struct
> + * landlock_rule nodes with socket type, described by (family, type)
> + * pair (see socket(2)). 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_socket;
> +
> /**
> * @hierarchy: Enables hierarchy identification even when a parent
> * domain vanishes. This is needed for the ptrace protection.
> @@ -233,7 +248,8 @@ struct landlock_ruleset {
>
> struct landlock_ruleset *
> landlock_create_ruleset(const access_mask_t access_mask_fs,
> - const access_mask_t access_mask_net);
> + const access_mask_t access_mask_net,
> + const access_mask_t access_mask_socket);
>
> void landlock_put_ruleset(struct landlock_ruleset *const ruleset);
> void landlock_put_ruleset_deferred(struct landlock_ruleset *const ruleset);
> @@ -282,6 +298,20 @@ landlock_add_net_access_mask(struct landlock_ruleset *const ruleset,
> (net_mask << LANDLOCK_SHIFT_ACCESS_NET);
> }
>
> +static inline void
> +landlock_add_socket_access_mask(struct landlock_ruleset *const ruleset,
> + const access_mask_t socket_access_mask,
> + const u16 layer_level)
> +{
> + access_mask_t socket_mask = socket_access_mask &
> + LANDLOCK_MASK_ACCESS_SOCKET;
> +
> + /* Should already be checked in sys_landlock_create_ruleset(). */
> + WARN_ON_ONCE(socket_access_mask != socket_mask);
> + ruleset->access_masks[layer_level] |=
> + (socket_mask << LANDLOCK_SHIFT_ACCESS_SOCKET);
> +}
> +
> static inline access_mask_t
> landlock_get_raw_fs_access_mask(const struct landlock_ruleset *const ruleset,
> const u16 layer_level)
> @@ -309,6 +339,15 @@ landlock_get_net_access_mask(const struct landlock_ruleset *const ruleset,
> LANDLOCK_MASK_ACCESS_NET;
> }
>
> +static inline access_mask_t
> +landlock_get_socket_access_mask(const struct landlock_ruleset *const ruleset,
> + const u16 layer_level)
> +{
> + return (ruleset->access_masks[layer_level] >>
> + LANDLOCK_SHIFT_ACCESS_SOCKET) &
> + LANDLOCK_MASK_ACCESS_SOCKET;
> +}
> +
> 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/socket.c b/security/landlock/socket.c
> new file mode 100644
> index 000000000000..1249a4a36503
> --- /dev/null
> +++ b/security/landlock/socket.c
> @@ -0,0 +1,60 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Landlock LSM - Socket management and hooks
> + *
> + * Copyright © 2024 Huawei Tech. Co., Ltd.
> + */
> +
> +#include <linux/net.h>
> +#include <linux/socket.h>
> +#include <linux/stddef.h>
> +
> +#include "limits.h"
> +#include "ruleset.h"
> +#include "socket.h"
> +
> +static uintptr_t pack_socket_key(const int family, const int type)
> +{
> + union {
> + struct {
> + unsigned short family, type;
> + } __packed data;
> + uintptr_t packed;
> + } socket_key;
> +
> + /* Checks that all supported socket families and types can be stored in socket_key. */
> + BUILD_BUG_ON(AF_MAX > (typeof(socket_key.data.family))~0);
> + BUILD_BUG_ON(SOCK_MAX > (typeof(socket_key.data.type))~0);
Off-by-one nit: AF_MAX and SOCK_MAX are one higher than the last permitted value,
so technically it would be ok if they are one higher than (unsigned short)~0.
> +
> + /* Checks that socket_key can be stored in landlock_key. */
> + BUILD_BUG_ON(sizeof(socket_key.data) > sizeof(socket_key.packed));
> + BUILD_BUG_ON(sizeof(socket_key.packed) >
> + sizeof_field(union landlock_key, data));
> +
> + socket_key.data.family = (unsigned short)family;
> + socket_key.data.type = (unsigned short)type;
> +
> + return socket_key.packed;
Can socket_key.packed end up containing uninitialized memory here?
> +}
I see that this function traces back to Mickaël's comment in
https://lore.kernel.org/all/20240412.phoh7laim7Th@digikod.net/
In my understanding, the motivation was to keep the key size in check.
But that does not mean that we need to turn it into a uintptr_t?
Would it not have been possible to extend the union landlock_key in ruleset.h
with a
struct {
unsigned short family, type;
}
and then do the AF_MAX, SOCK_MAX build-time checks on that?
It seems like that might be more in line with what we already have?
> +
> +int landlock_append_socket_rule(struct landlock_ruleset *const ruleset,
> + const int family, const int type,
> + access_mask_t access_rights)
> +{
> + int err;
> +
> + const struct landlock_id id = {
> + .key.data = pack_socket_key(family, type),
> + .type = LANDLOCK_KEY_SOCKET,
> + };
> +
> + /* Transforms relative access rights to absolute ones. */
> + access_rights |= LANDLOCK_MASK_ACCESS_SOCKET &
> + ~landlock_get_socket_access_mask(ruleset, 0);
> +
> + mutex_lock(&ruleset->lock);
> + err = landlock_insert_rule(ruleset, id, access_rights);
> + mutex_unlock(&ruleset->lock);
> +
> + return err;
> +}
> diff --git a/security/landlock/socket.h b/security/landlock/socket.h
> new file mode 100644
> index 000000000000..8519357f1c39
> --- /dev/null
> +++ b/security/landlock/socket.h
> @@ -0,0 +1,17 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Landlock LSM - Socket management and hooks
> + *
> + * Copyright © 2024 Huawei Tech. Co., Ltd.
> + */
> +
> +#ifndef _SECURITY_LANDLOCK_SOCKET_H
> +#define _SECURITY_LANDLOCK_SOCKET_H
> +
> +#include "ruleset.h"
> +
> +int landlock_append_socket_rule(struct landlock_ruleset *const ruleset,
> + const int family, const int type,
> + access_mask_t access_rights);
> +
> +#endif /* _SECURITY_LANDLOCK_SOCKET_H */
> diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
> index 03b470f5a85a..30c771f5e74f 100644
> --- a/security/landlock/syscalls.c
> +++ b/security/landlock/syscalls.c
> @@ -24,12 +24,14 @@
> #include <linux/syscalls.h>
> #include <linux/types.h>
> #include <linux/uaccess.h>
> +#include <linux/net.h>
> #include <uapi/linux/landlock.h>
>
> #include "cred.h"
> #include "fs.h"
> #include "limits.h"
> #include "net.h"
> +#include "socket.h"
> #include "ruleset.h"
> #include "setup.h"
>
> @@ -88,7 +90,8 @@ static void build_check_abi(void)
> struct landlock_ruleset_attr ruleset_attr;
> struct landlock_path_beneath_attr path_beneath_attr;
> struct landlock_net_port_attr net_port_attr;
> - size_t ruleset_size, path_beneath_size, net_port_size;
> + struct landlock_socket_attr socket_attr;
> + size_t ruleset_size, path_beneath_size, net_port_size, socket_size;
>
> /*
> * For each user space ABI structures, first checks that there is no
> @@ -97,8 +100,9 @@ static void build_check_abi(void)
> */
> ruleset_size = sizeof(ruleset_attr.handled_access_fs);
> ruleset_size += sizeof(ruleset_attr.handled_access_net);
> + ruleset_size += sizeof(ruleset_attr.handled_access_socket);
> BUILD_BUG_ON(sizeof(ruleset_attr) != ruleset_size);
> - BUILD_BUG_ON(sizeof(ruleset_attr) != 16);
> + BUILD_BUG_ON(sizeof(ruleset_attr) != 24);
>
> path_beneath_size = sizeof(path_beneath_attr.allowed_access);
> path_beneath_size += sizeof(path_beneath_attr.parent_fd);
> @@ -109,6 +113,12 @@ static void build_check_abi(void)
> 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);
> +
> + socket_size = sizeof(socket_attr.allowed_access);
> + socket_size += sizeof(socket_attr.family);
> + socket_size += sizeof(socket_attr.type);
> + BUILD_BUG_ON(sizeof(socket_attr) != socket_size);
> + BUILD_BUG_ON(sizeof(socket_attr) != 16);
> }
>
> /* Ruleset handling */
> @@ -149,7 +159,7 @@ static const struct file_operations ruleset_fops = {
> .write = fop_dummy_write,
> };
>
> -#define LANDLOCK_ABI_VERSION 5
> +#define LANDLOCK_ABI_VERSION 6
>
> /**
> * sys_landlock_create_ruleset - Create a new ruleset
> @@ -213,9 +223,15 @@ SYSCALL_DEFINE3(landlock_create_ruleset,
> LANDLOCK_MASK_ACCESS_NET)
> return -EINVAL;
>
> + /* Checks socket content (and 32-bits cast). */
> + if ((ruleset_attr.handled_access_socket |
> + LANDLOCK_MASK_ACCESS_SOCKET) != LANDLOCK_MASK_ACCESS_SOCKET)
> + return -EINVAL;
> +
> /* Checks arguments and transforms to kernel struct. */
> ruleset = landlock_create_ruleset(ruleset_attr.handled_access_fs,
> - ruleset_attr.handled_access_net);
> + ruleset_attr.handled_access_net,
> + ruleset_attr.handled_access_socket);
> if (IS_ERR(ruleset))
> return PTR_ERR(ruleset);
>
> @@ -371,6 +387,45 @@ static int add_rule_net_port(struct landlock_ruleset *ruleset,
> net_port_attr.allowed_access);
> }
>
> +static int add_rule_socket(struct landlock_ruleset *ruleset,
> + const void __user *const rule_attr)
> +{
> + struct landlock_socket_attr socket_attr;
> + int family, type;
> + int res;
> + access_mask_t mask;
> +
> + /* Copies raw user space buffer. */
> + res = copy_from_user(&socket_attr, rule_attr, sizeof(socket_attr));
> + if (res)
> + return -EFAULT;
> +
> + /*
> + * Informs about useless rule: empty allowed_access (i.e. deny rules)
> + * are ignored by socket actions.
> + */
> + if (!socket_attr.allowed_access)
> + return -ENOMSG;
> +
> + /* Checks that allowed_access matches the @ruleset constraints. */
> + mask = landlock_get_socket_access_mask(ruleset, 0);
> + if ((socket_attr.allowed_access | mask) != mask)
> + return -EINVAL;
> +
> + family = socket_attr.family;
> + type = socket_attr.type;
> +
> + /* Denies inserting a rule with unsupported socket family and type. */
> + if (family < 0 || family >= AF_MAX)
> + return -EINVAL;
> + if (type < 0 || type >= SOCK_MAX)
> + return -EINVAL;
enum sock_type (include/linux/net.h) has "holes": values 7, 8 and 9 are not
defined in the header. Should we check more specifically for the supported
values here? (Is there already a helper function for that?)
> + /* Imports the new rule. */
> + return landlock_append_socket_rule(ruleset, family, type,
> + socket_attr.allowed_access);
> +}
> +
> /**
> * sys_landlock_add_rule - Add a new rule to a ruleset
> *
> @@ -429,6 +484,9 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd,
> case LANDLOCK_RULE_NET_PORT:
> err = add_rule_net_port(ruleset, rule_attr);
> break;
> + case LANDLOCK_RULE_SOCKET:
> + err = add_rule_socket(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 3c1e9f35b531..52b00472a487 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(5, landlock_create_ruleset(NULL, 0,
> + ASSERT_EQ(6, landlock_create_ruleset(NULL, 0,
> LANDLOCK_CREATE_RULESET_VERSION));
>
> ASSERT_EQ(-1, landlock_create_ruleset(&ruleset_attr, 0,
> --
> 2.34.1
>
—Günther
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