147 lines
3.7 KiB
C
147 lines
3.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Landlock - Credential hooks
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*
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* Copyright © 2019-2020 Mickaël Salaün <mic@digikod.net>
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* Copyright © 2019-2020 ANSSI
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* Copyright © 2021-2025 Microsoft Corporation
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*/
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#ifndef _SECURITY_LANDLOCK_CRED_H
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#define _SECURITY_LANDLOCK_CRED_H
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#include <linux/container_of.h>
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#include <linux/cred.h>
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#include <linux/init.h>
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#include <linux/rcupdate.h>
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#include "access.h"
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#include "limits.h"
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#include "ruleset.h"
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#include "setup.h"
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/**
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* struct landlock_cred_security - Credential security blob
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*
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* This structure is packed to minimize the size of struct
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* landlock_file_security. However, it is always aligned in the LSM cred blob,
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* see lsm_set_blob_size().
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*/
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struct landlock_cred_security {
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/**
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* @domain: Immutable ruleset enforced on a task.
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*/
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struct landlock_ruleset *domain;
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#ifdef CONFIG_AUDIT
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/**
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* @domain_exec: Bitmask identifying the domain layers that were enforced by
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* the current task's executed file (i.e. no new execve(2) since
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* landlock_restrict_self(2)).
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*/
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u16 domain_exec;
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/**
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* @log_subdomains_off: Set if the domain descendants's log_status should be
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* set to %LANDLOCK_LOG_DISABLED. This is not a landlock_hierarchy
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* configuration because it applies to future descendant domains and it does
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* not require a current domain.
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*/
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u8 log_subdomains_off : 1;
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#endif /* CONFIG_AUDIT */
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} __packed;
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#ifdef CONFIG_AUDIT
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/* Makes sure all layer executions can be stored. */
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static_assert(BITS_PER_TYPE(typeof_member(struct landlock_cred_security,
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domain_exec)) >=
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LANDLOCK_MAX_NUM_LAYERS);
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#endif /* CONFIG_AUDIT */
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static inline struct landlock_cred_security *
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landlock_cred(const struct cred *cred)
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{
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return cred->security + landlock_blob_sizes.lbs_cred;
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}
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static inline struct landlock_ruleset *landlock_get_current_domain(void)
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{
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return landlock_cred(current_cred())->domain;
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}
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/*
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* The call needs to come from an RCU read-side critical section.
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*/
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static inline const struct landlock_ruleset *
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landlock_get_task_domain(const struct task_struct *const task)
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{
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return landlock_cred(__task_cred(task))->domain;
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}
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static inline bool landlocked(const struct task_struct *const task)
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{
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bool has_dom;
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if (task == current)
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return !!landlock_get_current_domain();
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rcu_read_lock();
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has_dom = !!landlock_get_task_domain(task);
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rcu_read_unlock();
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return has_dom;
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}
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/**
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* landlock_get_applicable_subject - Return the subject's Landlock credential
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* if its enforced domain applies to (i.e.
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* handles) at least one of the access rights
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* specified in @masks
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*
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* @cred: credential
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* @masks: access masks
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* @handle_layer: returned youngest layer handling a subset of @masks. Not set
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* if the function returns NULL.
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*
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* Returns: landlock_cred(@cred) if any access rights specified in @masks is
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* handled, or NULL otherwise.
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*/
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static inline const struct landlock_cred_security *
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landlock_get_applicable_subject(const struct cred *const cred,
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const struct access_masks masks,
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size_t *const handle_layer)
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{
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const union access_masks_all masks_all = {
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.masks = masks,
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};
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const struct landlock_ruleset *domain;
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ssize_t layer_level;
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if (!cred)
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return NULL;
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domain = landlock_cred(cred)->domain;
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if (!domain)
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return NULL;
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for (layer_level = domain->num_layers - 1; layer_level >= 0;
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layer_level--) {
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union access_masks_all layer = {
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.masks = domain->access_masks[layer_level],
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};
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if (layer.all & masks_all.all) {
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if (handle_layer)
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*handle_layer = layer_level;
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return landlock_cred(cred);
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}
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}
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return NULL;
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}
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__init void landlock_add_cred_hooks(void);
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#endif /* _SECURITY_LANDLOCK_CRED_H */
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