projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 11904167 KK |
1 | /* |
| 2 | * mmap based event notifications for SELinux | |
| 3 | * | |
| 4 | * Author: KaiGai Kohei <kaigai@ak.jp.nec.com> | |
| 5 | * | |
| 6 | * Copyright (C) 2010 NEC corporation | |
| 7 | * | |
| 8 | * This program is free software; you can redistribute it and/or modify | |
| 9 | * it under the terms of the GNU General Public License version 2, | |
| 10 | * as published by the Free Software Foundation. | |
| 11 | */ | |
| 12 | #include <linux/kernel.h> | |
| 13 | #include <linux/gfp.h> | |
| 14 | #include <linux/mm.h> | |
| 15 | #include <linux/mutex.h> | |
| 16 | #include "avc.h" | |
| 17 | #include "services.h" | |
| 18 | ||
| 19 | /* | |
| 20 | * The selinux_status_page shall be exposed to userspace applications | |
| 21 | * using mmap interface on /selinux/status. | |
| 22 | * It enables to notify applications a few events that will cause reset | |
| 23 | * of userspace access vector without context switching. | |
| 24 | * | |
| 25 | * The selinux_kernel_status structure on the head of status page is | |
| 26 | * protected from concurrent accesses using seqlock logic, so userspace | |
| 27 | * application should reference the status page according to the seqlock | |
| 28 | * logic. | |
| 29 | * | |
| 30 | * Typically, application checks status->sequence at the head of access | |
| 31 | * control routine. If it is odd-number, kernel is updating the status, | |
| 32 | * so please wait for a moment. If it is changed from the last sequence | |
| 33 | * number, it means something happen, so application will reset userspace | |
| 34 | * avc, if needed. | |
| 35 | * In most cases, application shall confirm the kernel status is not | |
| 36 | * changed without any system call invocations. | |
| 37 | */ | |
| 36f7f284 | 38 | static struct page *selinux_status_page; |
| 11904167 KK |
39 | static DEFINE_MUTEX(selinux_status_lock); |
| 40 | ||
| 41 | /* | |
| 42 | * selinux_kernel_status_page | |
| 43 | * | |
| 44 | * It returns a reference to selinux_status_page. If the status page is | |
| 45 | * not allocated yet, it also tries to allocate it at the first time. | |
| 46 | */ | |
| 47 | struct page *selinux_kernel_status_page(void) | |
| 48 | { | |
| 49 | struct selinux_kernel_status *status; | |
| 50 | struct page *result = NULL; | |
| 51 | ||
| 52 | mutex_lock(&selinux_status_lock); | |
| 36f7f284 | 53 | if (!selinux_status_page) { |
| 11904167 | 54 | selinux_status_page = alloc_page(GFP_KERNEL|__GFP_ZERO); |
| 36f7f284 KK |
55 | |
| 56 | if (selinux_status_page) { | |
| 11904167 KK |
57 | status = page_address(selinux_status_page); |
| 58 | ||
| 59 | status->version = SELINUX_KERNEL_STATUS_VERSION; | |
| 60 | status->sequence = 0; | |
| 61 | status->enforcing = selinux_enforcing; | |
| 62 | /* | |
| 63 | * NOTE: the next policyload event shall set | |
| 64 | * a positive value on the status->policyload, | |
| 65 | * although it may not be 1, but never zero. | |
| 66 | * So, application can know it was updated. | |
| 67 | */ | |
| 68 | status->policyload = 0; | |
| 69 | status->deny_unknown = !security_get_allow_unknown(); | |
| 70 | } | |
| 71 | } | |
| 72 | result = selinux_status_page; | |
| 73 | mutex_unlock(&selinux_status_lock); | |
| 74 | ||
| 75 | return result; | |
| 76 | } | |
| 77 | ||
| 78 | /* | |
| 79 | * selinux_status_update_setenforce | |
| 80 | * | |
| 81 | * It updates status of the current enforcing/permissive mode. | |
| 82 | */ | |
| 83 | void selinux_status_update_setenforce(int enforcing) | |
| 84 | { | |
| 85 | struct selinux_kernel_status *status; | |
| 86 | ||
| 87 | mutex_lock(&selinux_status_lock); | |
| 36f7f284 | 88 | if (selinux_status_page) { |
| 11904167 KK |
89 | status = page_address(selinux_status_page); |
| 90 | ||
| 91 | status->sequence++; | |
| 92 | smp_wmb(); | |
| 93 | ||
| 94 | status->enforcing = enforcing; | |
| 95 | ||
| 96 | smp_wmb(); | |
| 97 | status->sequence++; | |
| 98 | } | |
| 99 | mutex_unlock(&selinux_status_lock); | |
| 100 | } | |
| 101 | ||
| 102 | /* | |
| 103 | * selinux_status_update_policyload | |
| 104 | * | |
| 105 | * It updates status of the times of policy reloaded, and current | |
| 106 | * setting of deny_unknown. | |
| 107 | */ | |
| 108 | void selinux_status_update_policyload(int seqno) | |
| 109 | { | |
| 110 | struct selinux_kernel_status *status; | |
| 111 | ||
| 112 | mutex_lock(&selinux_status_lock); | |
| 36f7f284 | 113 | if (selinux_status_page) { |
| 11904167 KK |
114 | status = page_address(selinux_status_page); |
| 115 | ||
| 116 | status->sequence++; | |
| 117 | smp_wmb(); | |
| 118 | ||
| 119 | status->policyload = seqno; | |
| 120 | status->deny_unknown = !security_get_allow_unknown(); | |
| 121 | ||
| 122 | smp_wmb(); | |
| 123 | status->sequence++; | |
| 124 | } | |
| 125 | mutex_unlock(&selinux_status_lock); | |
| 126 | } |