aa8e712cee
Define a selinux state structure (struct selinux_state) for global SELinux state and pass it explicitly to all security server functions. The public portion of the structure contains state that is used throughout the SELinux code, such as the enforcing mode. The structure also contains a pointer to a selinux_ss structure whose definition is private to the security server and contains security server specific state such as the policy database and SID table. This change should have no effect on SELinux behavior or APIs (userspace or LSM). It merely wraps SELinux state and passes it explicitly as needed. Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov> [PM: minor fixups needed due to collisions with the SCTP patches] Signed-off-by: Paul Moore <paul@paul-moore.com>
128 lines
3.5 KiB
C
128 lines
3.5 KiB
C
/*
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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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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2,
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* as published by the Free Software Foundation.
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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 = is_enforcing(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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