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Let's follow a consistent and documented coding style. Everything may not be to our liking but it is better than tacit knowledge. Moreover, this will help maintain style consistency between different developers. This contains only whitespace changes. Automatically formatted with: clang-format-14 -i security/landlock/*.[ch] include/uapi/linux/landlock.h Link: https://lore.kernel.org/r/20220506160513.523257-3-mic@digikod.net Cc: stable@vger.kernel.org Signed-off-by: Mickaël Salaün <mic@digikod.net>
120 lines
3.2 KiB
C
120 lines
3.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Landlock LSM - Ptrace hooks
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*
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* Copyright © 2017-2020 Mickaël Salaün <mic@digikod.net>
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* Copyright © 2019-2020 ANSSI
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*/
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#include <asm/current.h>
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#include <linux/cred.h>
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#include <linux/errno.h>
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#include <linux/kernel.h>
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#include <linux/lsm_hooks.h>
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#include <linux/rcupdate.h>
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#include <linux/sched.h>
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#include "common.h"
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#include "cred.h"
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#include "ptrace.h"
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#include "ruleset.h"
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#include "setup.h"
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/**
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* domain_scope_le - Checks domain ordering for scoped ptrace
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*
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* @parent: Parent domain.
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* @child: Potential child of @parent.
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*
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* Checks if the @parent domain is less or equal to (i.e. an ancestor, which
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* means a subset of) the @child domain.
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*/
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static bool domain_scope_le(const struct landlock_ruleset *const parent,
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const struct landlock_ruleset *const child)
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{
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const struct landlock_hierarchy *walker;
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if (!parent)
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return true;
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if (!child)
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return false;
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for (walker = child->hierarchy; walker; walker = walker->parent) {
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if (walker == parent->hierarchy)
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/* @parent is in the scoped hierarchy of @child. */
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return true;
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}
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/* There is no relationship between @parent and @child. */
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return false;
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}
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static bool task_is_scoped(const struct task_struct *const parent,
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const struct task_struct *const child)
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{
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bool is_scoped;
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const struct landlock_ruleset *dom_parent, *dom_child;
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rcu_read_lock();
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dom_parent = landlock_get_task_domain(parent);
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dom_child = landlock_get_task_domain(child);
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is_scoped = domain_scope_le(dom_parent, dom_child);
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rcu_read_unlock();
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return is_scoped;
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}
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static int task_ptrace(const struct task_struct *const parent,
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const struct task_struct *const child)
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{
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/* Quick return for non-landlocked tasks. */
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if (!landlocked(parent))
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return 0;
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if (task_is_scoped(parent, child))
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return 0;
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return -EPERM;
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}
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/**
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* hook_ptrace_access_check - Determines whether the current process may access
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* another
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*
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* @child: Process to be accessed.
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* @mode: Mode of attachment.
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*
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* If the current task has Landlock rules, then the child must have at least
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* the same rules. Else denied.
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*
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* Determines whether a process may access another, returning 0 if permission
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* granted, -errno if denied.
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*/
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static int hook_ptrace_access_check(struct task_struct *const child,
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const unsigned int mode)
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{
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return task_ptrace(current, child);
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}
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/**
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* hook_ptrace_traceme - Determines whether another process may trace the
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* current one
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*
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* @parent: Task proposed to be the tracer.
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*
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* If the parent has Landlock rules, then the current task must have the same
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* or more rules. Else denied.
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*
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* Determines whether the nominated task is permitted to trace the current
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* process, returning 0 if permission is granted, -errno if denied.
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*/
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static int hook_ptrace_traceme(struct task_struct *const parent)
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{
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return task_ptrace(parent, current);
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}
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static struct security_hook_list landlock_hooks[] __lsm_ro_after_init = {
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LSM_HOOK_INIT(ptrace_access_check, hook_ptrace_access_check),
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LSM_HOOK_INIT(ptrace_traceme, hook_ptrace_traceme),
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};
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__init void landlock_add_ptrace_hooks(void)
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{
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security_add_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks),
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LANDLOCK_NAME);
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}
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