forked from Minki/linux
d2912cb15b
Based on 2 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation # extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 4122 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Enrico Weigelt <info@metux.net> Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
125 lines
3.3 KiB
C
125 lines
3.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* mmap based event notifications for SELinux
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*
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* Author: KaiGai Kohei <kaigai@ak.jp.nec.com>
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*
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* Copyright (C) 2010 NEC corporation
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*/
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#include <linux/kernel.h>
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#include <linux/gfp.h>
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#include <linux/mm.h>
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#include <linux/mutex.h>
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#include "avc.h"
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#include "services.h"
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/*
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* The selinux_status_page shall be exposed to userspace applications
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* using mmap interface on /selinux/status.
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* It enables to notify applications a few events that will cause reset
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* of userspace access vector without context switching.
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*
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* The selinux_kernel_status structure on the head of status page is
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* protected from concurrent accesses using seqlock logic, so userspace
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* application should reference the status page according to the seqlock
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* logic.
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*
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* Typically, application checks status->sequence at the head of access
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* control routine. If it is odd-number, kernel is updating the status,
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* so please wait for a moment. If it is changed from the last sequence
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* number, it means something happen, so application will reset userspace
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* avc, if needed.
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* In most cases, application shall confirm the kernel status is not
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* changed without any system call invocations.
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*/
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/*
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* selinux_kernel_status_page
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*
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* It returns a reference to selinux_status_page. If the status page is
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* not allocated yet, it also tries to allocate it at the first time.
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*/
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struct page *selinux_kernel_status_page(struct selinux_state *state)
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{
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struct selinux_kernel_status *status;
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struct page *result = NULL;
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mutex_lock(&state->ss->status_lock);
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if (!state->ss->status_page) {
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state->ss->status_page = alloc_page(GFP_KERNEL|__GFP_ZERO);
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if (state->ss->status_page) {
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status = page_address(state->ss->status_page);
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status->version = SELINUX_KERNEL_STATUS_VERSION;
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status->sequence = 0;
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status->enforcing = enforcing_enabled(state);
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/*
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* NOTE: the next policyload event shall set
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* a positive value on the status->policyload,
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* although it may not be 1, but never zero.
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* So, application can know it was updated.
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*/
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status->policyload = 0;
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status->deny_unknown =
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!security_get_allow_unknown(state);
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}
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}
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result = state->ss->status_page;
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mutex_unlock(&state->ss->status_lock);
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return result;
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}
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/*
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* selinux_status_update_setenforce
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*
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* It updates status of the current enforcing/permissive mode.
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*/
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void selinux_status_update_setenforce(struct selinux_state *state,
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int enforcing)
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{
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struct selinux_kernel_status *status;
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mutex_lock(&state->ss->status_lock);
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if (state->ss->status_page) {
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status = page_address(state->ss->status_page);
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status->sequence++;
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smp_wmb();
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status->enforcing = enforcing;
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smp_wmb();
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status->sequence++;
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}
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mutex_unlock(&state->ss->status_lock);
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}
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/*
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* selinux_status_update_policyload
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*
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* It updates status of the times of policy reloaded, and current
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* setting of deny_unknown.
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*/
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void selinux_status_update_policyload(struct selinux_state *state,
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int seqno)
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{
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struct selinux_kernel_status *status;
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mutex_lock(&state->ss->status_lock);
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if (state->ss->status_page) {
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status = page_address(state->ss->status_page);
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status->sequence++;
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smp_wmb();
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status->policyload = seqno;
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status->deny_unknown = !security_get_allow_unknown(state);
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smp_wmb();
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status->sequence++;
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}
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mutex_unlock(&state->ss->status_lock);
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}
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