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![Eric Paris](/assets/img/avatar_default.png)
The security_ops reset done when SELinux is disabled at run time is done after the avc cache is freed and after the kmem_cache for the avc is also freed. This means that between the time the selinux disable code destroys the avc_node_cachep another process could make a security request and could try to allocate from the cache. We are just going to leave the cachep around, like we always have. SELinux: Disabled at runtime. BUG: unable to handle kernel NULL pointer dereference at (null) IP: [<ffffffff81122537>] kmem_cache_alloc+0x9a/0x185 PGD 0 Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC last sysfs file: CPU 1 Modules linked in: Pid: 12, comm: khelper Not tainted 2.6.31-tip-05525-g0eeacc6-dirty #14819 System Product Name RIP: 0010:[<ffffffff81122537>] [<ffffffff81122537>] kmem_cache_alloc+0x9a/0x185 RSP: 0018:ffff88003f9258b0 EFLAGS: 00010086 RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000078c0129e RDX: 0000000000000000 RSI: ffffffff8130b626 RDI: ffffffff81122528 RBP: ffff88003f925900 R08: 0000000078c0129e R09: 0000000000000001 R10: 0000000000000000 R11: 0000000078c0129e R12: 0000000000000246 R13: 0000000000008020 R14: ffff88003f8586d8 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff880002b00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0018 ES: 0018 CR0: 000000008005003b CR2: 0000000000000000 CR3: 0000000001001000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: ffffffff827bd420 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process khelper (pid: 12, threadinfo ffff88003f924000, task ffff88003f928000) Stack: 0000000000000246 0000802000000246 ffffffff8130b626 0000000000000001 <0> 0000000078c0129e 0000000000000000 ffff88003f925a70 0000000000000002 <0> 0000000000000001 0000000000000001 ffff88003f925960 ffffffff8130b626 Call Trace: [<ffffffff8130b626>] ? avc_alloc_node+0x36/0x273 [<ffffffff8130b626>] avc_alloc_node+0x36/0x273 [<ffffffff8130b545>] ? avc_latest_notif_update+0x7d/0x9e [<ffffffff8130b8b4>] avc_insert+0x51/0x18d [<ffffffff8130bcce>] avc_has_perm_noaudit+0x9d/0x128 [<ffffffff8130bf20>] avc_has_perm+0x45/0x88 [<ffffffff8130f99d>] current_has_perm+0x52/0x6d [<ffffffff8130fbb2>] selinux_task_create+0x2f/0x45 [<ffffffff81303bf7>] security_task_create+0x29/0x3f [<ffffffff8105c6ba>] copy_process+0x82/0xdf0 [<ffffffff81091578>] ? register_lock_class+0x2f/0x36c [<ffffffff81091a13>] ? mark_lock+0x2e/0x1e1 [<ffffffff8105d596>] do_fork+0x16e/0x382 [<ffffffff81091578>] ? register_lock_class+0x2f/0x36c [<ffffffff810d9166>] ? probe_workqueue_execution+0x57/0xf9 [<ffffffff81091a13>] ? mark_lock+0x2e/0x1e1 [<ffffffff810d9166>] ? probe_workqueue_execution+0x57/0xf9 [<ffffffff8100cdb2>] kernel_thread+0x82/0xe0 [<ffffffff81078b1f>] ? ____call_usermodehelper+0x0/0x139 [<ffffffff8100ce10>] ? child_rip+0x0/0x20 [<ffffffff81078aea>] ? __call_usermodehelper+0x65/0x9a [<ffffffff8107a5c7>] run_workqueue+0x171/0x27e [<ffffffff8107a573>] ? run_workqueue+0x11d/0x27e [<ffffffff81078a85>] ? __call_usermodehelper+0x0/0x9a [<ffffffff8107a7bc>] worker_thread+0xe8/0x10f [<ffffffff810808e2>] ? autoremove_wake_function+0x0/0x63 [<ffffffff8107a6d4>] ? worker_thread+0x0/0x10f [<ffffffff8108042e>] kthread+0x91/0x99 [<ffffffff8100ce1a>] child_rip+0xa/0x20 [<ffffffff8100c754>] ? restore_args+0x0/0x30 [<ffffffff8108039d>] ? kthread+0x0/0x99 [<ffffffff8100ce10>] ? child_rip+0x0/0x20 Code: 0f 85 99 00 00 00 9c 58 66 66 90 66 90 49 89 c4 fa 66 66 90 66 66 90 e8 83 34 fb ff e8 d7 e9 26 00 48 98 49 8b 94 c6 10 01 00 00 <48> 8b 1a 44 8b 7a 18 48 85 db 74 0f 8b 42 14 48 8b 04 c3 ff 42 RIP [<ffffffff81122537>] kmem_cache_alloc+0x9a/0x185 RSP <ffff88003f9258b0> CR2: 0000000000000000 ---[ end trace 42f41a982344e606 ]--- Reported-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Eric Paris <eparis@redhat.com> Signed-off-by: James Morris <jmorris@namei.org>
886 lines
22 KiB
C
886 lines
22 KiB
C
/*
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* Implementation of the kernel access vector cache (AVC).
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*
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* Authors: Stephen Smalley, <sds@epoch.ncsc.mil>
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* James Morris <jmorris@redhat.com>
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*
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* Update: KaiGai, Kohei <kaigai@ak.jp.nec.com>
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* Replaced the avc_lock spinlock by RCU.
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*
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* Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com>
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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/types.h>
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#include <linux/stddef.h>
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/fs.h>
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#include <linux/dcache.h>
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#include <linux/init.h>
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#include <linux/skbuff.h>
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#include <linux/percpu.h>
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#include <net/sock.h>
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#include <linux/un.h>
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#include <net/af_unix.h>
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#include <linux/ip.h>
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#include <linux/audit.h>
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#include <linux/ipv6.h>
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#include <net/ipv6.h>
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#include "avc.h"
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#include "avc_ss.h"
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static const struct av_perm_to_string av_perm_to_string[] = {
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#define S_(c, v, s) { c, v, s },
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#include "av_perm_to_string.h"
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#undef S_
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};
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static const char *class_to_string[] = {
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#define S_(s) s,
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#include "class_to_string.h"
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#undef S_
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};
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#define TB_(s) static const char *s[] = {
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#define TE_(s) };
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#define S_(s) s,
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#include "common_perm_to_string.h"
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#undef TB_
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#undef TE_
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#undef S_
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static const struct av_inherit av_inherit[] = {
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#define S_(c, i, b) { .tclass = c,\
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.common_pts = common_##i##_perm_to_string,\
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.common_base = b },
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#include "av_inherit.h"
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#undef S_
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};
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const struct selinux_class_perm selinux_class_perm = {
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.av_perm_to_string = av_perm_to_string,
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.av_pts_len = ARRAY_SIZE(av_perm_to_string),
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.class_to_string = class_to_string,
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.cts_len = ARRAY_SIZE(class_to_string),
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.av_inherit = av_inherit,
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.av_inherit_len = ARRAY_SIZE(av_inherit)
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};
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#define AVC_CACHE_SLOTS 512
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#define AVC_DEF_CACHE_THRESHOLD 512
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#define AVC_CACHE_RECLAIM 16
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#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
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#define avc_cache_stats_incr(field) \
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do { \
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per_cpu(avc_cache_stats, get_cpu()).field++; \
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put_cpu(); \
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} while (0)
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#else
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#define avc_cache_stats_incr(field) do {} while (0)
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#endif
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struct avc_entry {
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u32 ssid;
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u32 tsid;
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u16 tclass;
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struct av_decision avd;
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};
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struct avc_node {
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struct avc_entry ae;
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struct hlist_node list; /* anchored in avc_cache->slots[i] */
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struct rcu_head rhead;
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};
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struct avc_cache {
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struct hlist_head slots[AVC_CACHE_SLOTS]; /* head for avc_node->list */
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spinlock_t slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */
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atomic_t lru_hint; /* LRU hint for reclaim scan */
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atomic_t active_nodes;
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u32 latest_notif; /* latest revocation notification */
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};
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struct avc_callback_node {
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int (*callback) (u32 event, u32 ssid, u32 tsid,
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u16 tclass, u32 perms,
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u32 *out_retained);
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u32 events;
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u32 ssid;
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u32 tsid;
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u16 tclass;
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u32 perms;
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struct avc_callback_node *next;
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};
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/* Exported via selinufs */
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unsigned int avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
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#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
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DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
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#endif
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static struct avc_cache avc_cache;
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static struct avc_callback_node *avc_callbacks;
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static struct kmem_cache *avc_node_cachep;
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static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass)
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{
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return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1);
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}
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/**
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* avc_dump_av - Display an access vector in human-readable form.
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* @tclass: target security class
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* @av: access vector
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*/
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static void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av)
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{
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const char **common_pts = NULL;
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u32 common_base = 0;
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int i, i2, perm;
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if (av == 0) {
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audit_log_format(ab, " null");
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return;
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}
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for (i = 0; i < ARRAY_SIZE(av_inherit); i++) {
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if (av_inherit[i].tclass == tclass) {
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common_pts = av_inherit[i].common_pts;
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common_base = av_inherit[i].common_base;
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break;
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}
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}
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audit_log_format(ab, " {");
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i = 0;
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perm = 1;
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while (perm < common_base) {
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if (perm & av) {
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audit_log_format(ab, " %s", common_pts[i]);
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av &= ~perm;
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}
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i++;
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perm <<= 1;
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}
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while (i < sizeof(av) * 8) {
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if (perm & av) {
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for (i2 = 0; i2 < ARRAY_SIZE(av_perm_to_string); i2++) {
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if ((av_perm_to_string[i2].tclass == tclass) &&
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(av_perm_to_string[i2].value == perm))
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break;
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}
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if (i2 < ARRAY_SIZE(av_perm_to_string)) {
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audit_log_format(ab, " %s",
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av_perm_to_string[i2].name);
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av &= ~perm;
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}
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}
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i++;
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perm <<= 1;
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}
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if (av)
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audit_log_format(ab, " 0x%x", av);
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audit_log_format(ab, " }");
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}
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/**
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* avc_dump_query - Display a SID pair and a class in human-readable form.
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* @ssid: source security identifier
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* @tsid: target security identifier
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* @tclass: target security class
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*/
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static void avc_dump_query(struct audit_buffer *ab, u32 ssid, u32 tsid, u16 tclass)
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{
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int rc;
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char *scontext;
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u32 scontext_len;
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rc = security_sid_to_context(ssid, &scontext, &scontext_len);
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if (rc)
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audit_log_format(ab, "ssid=%d", ssid);
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else {
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audit_log_format(ab, "scontext=%s", scontext);
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kfree(scontext);
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}
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rc = security_sid_to_context(tsid, &scontext, &scontext_len);
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if (rc)
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audit_log_format(ab, " tsid=%d", tsid);
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else {
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audit_log_format(ab, " tcontext=%s", scontext);
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kfree(scontext);
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}
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BUG_ON(tclass >= ARRAY_SIZE(class_to_string) || !class_to_string[tclass]);
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audit_log_format(ab, " tclass=%s", class_to_string[tclass]);
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}
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/**
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* avc_init - Initialize the AVC.
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*
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* Initialize the access vector cache.
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*/
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void __init avc_init(void)
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{
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int i;
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for (i = 0; i < AVC_CACHE_SLOTS; i++) {
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INIT_HLIST_HEAD(&avc_cache.slots[i]);
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spin_lock_init(&avc_cache.slots_lock[i]);
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}
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atomic_set(&avc_cache.active_nodes, 0);
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atomic_set(&avc_cache.lru_hint, 0);
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avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node),
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0, SLAB_PANIC, NULL);
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audit_log(current->audit_context, GFP_KERNEL, AUDIT_KERNEL, "AVC INITIALIZED\n");
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}
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int avc_get_hash_stats(char *page)
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{
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int i, chain_len, max_chain_len, slots_used;
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struct avc_node *node;
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struct hlist_head *head;
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rcu_read_lock();
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slots_used = 0;
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max_chain_len = 0;
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for (i = 0; i < AVC_CACHE_SLOTS; i++) {
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head = &avc_cache.slots[i];
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if (!hlist_empty(head)) {
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struct hlist_node *next;
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slots_used++;
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chain_len = 0;
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hlist_for_each_entry_rcu(node, next, head, list)
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chain_len++;
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if (chain_len > max_chain_len)
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max_chain_len = chain_len;
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}
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}
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rcu_read_unlock();
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return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
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"longest chain: %d\n",
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atomic_read(&avc_cache.active_nodes),
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slots_used, AVC_CACHE_SLOTS, max_chain_len);
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}
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static void avc_node_free(struct rcu_head *rhead)
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{
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struct avc_node *node = container_of(rhead, struct avc_node, rhead);
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kmem_cache_free(avc_node_cachep, node);
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avc_cache_stats_incr(frees);
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}
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static void avc_node_delete(struct avc_node *node)
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{
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hlist_del_rcu(&node->list);
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call_rcu(&node->rhead, avc_node_free);
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atomic_dec(&avc_cache.active_nodes);
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}
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static void avc_node_kill(struct avc_node *node)
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{
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kmem_cache_free(avc_node_cachep, node);
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avc_cache_stats_incr(frees);
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atomic_dec(&avc_cache.active_nodes);
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}
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static void avc_node_replace(struct avc_node *new, struct avc_node *old)
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{
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hlist_replace_rcu(&old->list, &new->list);
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call_rcu(&old->rhead, avc_node_free);
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atomic_dec(&avc_cache.active_nodes);
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}
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static inline int avc_reclaim_node(void)
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{
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struct avc_node *node;
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int hvalue, try, ecx;
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unsigned long flags;
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struct hlist_head *head;
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struct hlist_node *next;
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spinlock_t *lock;
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for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) {
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hvalue = atomic_inc_return(&avc_cache.lru_hint) & (AVC_CACHE_SLOTS - 1);
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head = &avc_cache.slots[hvalue];
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lock = &avc_cache.slots_lock[hvalue];
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if (!spin_trylock_irqsave(lock, flags))
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continue;
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rcu_read_lock();
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hlist_for_each_entry(node, next, head, list) {
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avc_node_delete(node);
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avc_cache_stats_incr(reclaims);
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ecx++;
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if (ecx >= AVC_CACHE_RECLAIM) {
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rcu_read_unlock();
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spin_unlock_irqrestore(lock, flags);
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goto out;
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}
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}
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rcu_read_unlock();
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spin_unlock_irqrestore(lock, flags);
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}
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out:
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return ecx;
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}
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static struct avc_node *avc_alloc_node(void)
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{
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struct avc_node *node;
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node = kmem_cache_zalloc(avc_node_cachep, GFP_ATOMIC);
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if (!node)
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goto out;
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INIT_RCU_HEAD(&node->rhead);
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INIT_HLIST_NODE(&node->list);
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avc_cache_stats_incr(allocations);
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if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold)
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avc_reclaim_node();
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out:
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return node;
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}
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static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
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{
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node->ae.ssid = ssid;
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node->ae.tsid = tsid;
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node->ae.tclass = tclass;
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memcpy(&node->ae.avd, avd, sizeof(node->ae.avd));
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}
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static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass)
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{
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struct avc_node *node, *ret = NULL;
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int hvalue;
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struct hlist_head *head;
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struct hlist_node *next;
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hvalue = avc_hash(ssid, tsid, tclass);
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head = &avc_cache.slots[hvalue];
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hlist_for_each_entry_rcu(node, next, head, list) {
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if (ssid == node->ae.ssid &&
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tclass == node->ae.tclass &&
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tsid == node->ae.tsid) {
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ret = node;
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break;
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}
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}
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return ret;
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}
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/**
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* avc_lookup - Look up an AVC entry.
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* @ssid: source security identifier
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* @tsid: target security identifier
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* @tclass: target security class
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*
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* Look up an AVC entry that is valid for the
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* (@ssid, @tsid), interpreting the permissions
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* based on @tclass. If a valid AVC entry exists,
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* then this function return the avc_node.
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* Otherwise, this function returns NULL.
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*/
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static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass)
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{
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struct avc_node *node;
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avc_cache_stats_incr(lookups);
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node = avc_search_node(ssid, tsid, tclass);
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if (node)
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avc_cache_stats_incr(hits);
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|
else
|
|
avc_cache_stats_incr(misses);
|
|
|
|
return node;
|
|
}
|
|
|
|
static int avc_latest_notif_update(int seqno, int is_insert)
|
|
{
|
|
int ret = 0;
|
|
static DEFINE_SPINLOCK(notif_lock);
|
|
unsigned long flag;
|
|
|
|
spin_lock_irqsave(¬if_lock, flag);
|
|
if (is_insert) {
|
|
if (seqno < avc_cache.latest_notif) {
|
|
printk(KERN_WARNING "SELinux: avc: seqno %d < latest_notif %d\n",
|
|
seqno, avc_cache.latest_notif);
|
|
ret = -EAGAIN;
|
|
}
|
|
} else {
|
|
if (seqno > avc_cache.latest_notif)
|
|
avc_cache.latest_notif = seqno;
|
|
}
|
|
spin_unlock_irqrestore(¬if_lock, flag);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* avc_insert - Insert an AVC entry.
|
|
* @ssid: source security identifier
|
|
* @tsid: target security identifier
|
|
* @tclass: target security class
|
|
* @avd: resulting av decision
|
|
*
|
|
* Insert an AVC entry for the SID pair
|
|
* (@ssid, @tsid) and class @tclass.
|
|
* The access vectors and the sequence number are
|
|
* normally provided by the security server in
|
|
* response to a security_compute_av() call. If the
|
|
* sequence number @avd->seqno is not less than the latest
|
|
* revocation notification, then the function copies
|
|
* the access vectors into a cache entry, returns
|
|
* avc_node inserted. Otherwise, this function returns NULL.
|
|
*/
|
|
static struct avc_node *avc_insert(u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
|
|
{
|
|
struct avc_node *pos, *node = NULL;
|
|
int hvalue;
|
|
unsigned long flag;
|
|
|
|
if (avc_latest_notif_update(avd->seqno, 1))
|
|
goto out;
|
|
|
|
node = avc_alloc_node();
|
|
if (node) {
|
|
struct hlist_head *head;
|
|
struct hlist_node *next;
|
|
spinlock_t *lock;
|
|
|
|
hvalue = avc_hash(ssid, tsid, tclass);
|
|
avc_node_populate(node, ssid, tsid, tclass, avd);
|
|
|
|
head = &avc_cache.slots[hvalue];
|
|
lock = &avc_cache.slots_lock[hvalue];
|
|
|
|
spin_lock_irqsave(lock, flag);
|
|
hlist_for_each_entry(pos, next, head, list) {
|
|
if (pos->ae.ssid == ssid &&
|
|
pos->ae.tsid == tsid &&
|
|
pos->ae.tclass == tclass) {
|
|
avc_node_replace(node, pos);
|
|
goto found;
|
|
}
|
|
}
|
|
hlist_add_head_rcu(&node->list, head);
|
|
found:
|
|
spin_unlock_irqrestore(lock, flag);
|
|
}
|
|
out:
|
|
return node;
|
|
}
|
|
|
|
/**
|
|
* avc_audit_pre_callback - SELinux specific information
|
|
* will be called by generic audit code
|
|
* @ab: the audit buffer
|
|
* @a: audit_data
|
|
*/
|
|
static void avc_audit_pre_callback(struct audit_buffer *ab, void *a)
|
|
{
|
|
struct common_audit_data *ad = a;
|
|
audit_log_format(ab, "avc: %s ",
|
|
ad->selinux_audit_data.denied ? "denied" : "granted");
|
|
avc_dump_av(ab, ad->selinux_audit_data.tclass,
|
|
ad->selinux_audit_data.audited);
|
|
audit_log_format(ab, " for ");
|
|
}
|
|
|
|
/**
|
|
* avc_audit_post_callback - SELinux specific information
|
|
* will be called by generic audit code
|
|
* @ab: the audit buffer
|
|
* @a: audit_data
|
|
*/
|
|
static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
|
|
{
|
|
struct common_audit_data *ad = a;
|
|
audit_log_format(ab, " ");
|
|
avc_dump_query(ab, ad->selinux_audit_data.ssid,
|
|
ad->selinux_audit_data.tsid,
|
|
ad->selinux_audit_data.tclass);
|
|
}
|
|
|
|
/**
|
|
* avc_audit - Audit the granting or denial of permissions.
|
|
* @ssid: source security identifier
|
|
* @tsid: target security identifier
|
|
* @tclass: target security class
|
|
* @requested: requested permissions
|
|
* @avd: access vector decisions
|
|
* @result: result from avc_has_perm_noaudit
|
|
* @a: auxiliary audit data
|
|
*
|
|
* Audit the granting or denial of permissions in accordance
|
|
* with the policy. This function is typically called by
|
|
* avc_has_perm() after a permission check, but can also be
|
|
* called directly by callers who use avc_has_perm_noaudit()
|
|
* in order to separate the permission check from the auditing.
|
|
* For example, this separation is useful when the permission check must
|
|
* be performed under a lock, to allow the lock to be released
|
|
* before calling the auditing code.
|
|
*/
|
|
void avc_audit(u32 ssid, u32 tsid,
|
|
u16 tclass, u32 requested,
|
|
struct av_decision *avd, int result, struct common_audit_data *a)
|
|
{
|
|
struct common_audit_data stack_data;
|
|
u32 denied, audited;
|
|
denied = requested & ~avd->allowed;
|
|
if (denied) {
|
|
audited = denied;
|
|
if (!(audited & avd->auditdeny))
|
|
return;
|
|
} else if (result) {
|
|
audited = denied = requested;
|
|
} else {
|
|
audited = requested;
|
|
if (!(audited & avd->auditallow))
|
|
return;
|
|
}
|
|
if (!a) {
|
|
a = &stack_data;
|
|
memset(a, 0, sizeof(*a));
|
|
a->type = LSM_AUDIT_NO_AUDIT;
|
|
}
|
|
a->selinux_audit_data.tclass = tclass;
|
|
a->selinux_audit_data.requested = requested;
|
|
a->selinux_audit_data.ssid = ssid;
|
|
a->selinux_audit_data.tsid = tsid;
|
|
a->selinux_audit_data.audited = audited;
|
|
a->selinux_audit_data.denied = denied;
|
|
a->lsm_pre_audit = avc_audit_pre_callback;
|
|
a->lsm_post_audit = avc_audit_post_callback;
|
|
common_lsm_audit(a);
|
|
}
|
|
|
|
/**
|
|
* avc_add_callback - Register a callback for security events.
|
|
* @callback: callback function
|
|
* @events: security events
|
|
* @ssid: source security identifier or %SECSID_WILD
|
|
* @tsid: target security identifier or %SECSID_WILD
|
|
* @tclass: target security class
|
|
* @perms: permissions
|
|
*
|
|
* Register a callback function for events in the set @events
|
|
* related to the SID pair (@ssid, @tsid) and
|
|
* and the permissions @perms, interpreting
|
|
* @perms based on @tclass. Returns %0 on success or
|
|
* -%ENOMEM if insufficient memory exists to add the callback.
|
|
*/
|
|
int avc_add_callback(int (*callback)(u32 event, u32 ssid, u32 tsid,
|
|
u16 tclass, u32 perms,
|
|
u32 *out_retained),
|
|
u32 events, u32 ssid, u32 tsid,
|
|
u16 tclass, u32 perms)
|
|
{
|
|
struct avc_callback_node *c;
|
|
int rc = 0;
|
|
|
|
c = kmalloc(sizeof(*c), GFP_ATOMIC);
|
|
if (!c) {
|
|
rc = -ENOMEM;
|
|
goto out;
|
|
}
|
|
|
|
c->callback = callback;
|
|
c->events = events;
|
|
c->ssid = ssid;
|
|
c->tsid = tsid;
|
|
c->perms = perms;
|
|
c->next = avc_callbacks;
|
|
avc_callbacks = c;
|
|
out:
|
|
return rc;
|
|
}
|
|
|
|
static inline int avc_sidcmp(u32 x, u32 y)
|
|
{
|
|
return (x == y || x == SECSID_WILD || y == SECSID_WILD);
|
|
}
|
|
|
|
/**
|
|
* avc_update_node Update an AVC entry
|
|
* @event : Updating event
|
|
* @perms : Permission mask bits
|
|
* @ssid,@tsid,@tclass : identifier of an AVC entry
|
|
* @seqno : sequence number when decision was made
|
|
*
|
|
* if a valid AVC entry doesn't exist,this function returns -ENOENT.
|
|
* if kmalloc() called internal returns NULL, this function returns -ENOMEM.
|
|
* otherwise, this function update the AVC entry. The original AVC-entry object
|
|
* will release later by RCU.
|
|
*/
|
|
static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass,
|
|
u32 seqno)
|
|
{
|
|
int hvalue, rc = 0;
|
|
unsigned long flag;
|
|
struct avc_node *pos, *node, *orig = NULL;
|
|
struct hlist_head *head;
|
|
struct hlist_node *next;
|
|
spinlock_t *lock;
|
|
|
|
node = avc_alloc_node();
|
|
if (!node) {
|
|
rc = -ENOMEM;
|
|
goto out;
|
|
}
|
|
|
|
/* Lock the target slot */
|
|
hvalue = avc_hash(ssid, tsid, tclass);
|
|
|
|
head = &avc_cache.slots[hvalue];
|
|
lock = &avc_cache.slots_lock[hvalue];
|
|
|
|
spin_lock_irqsave(lock, flag);
|
|
|
|
hlist_for_each_entry(pos, next, head, list) {
|
|
if (ssid == pos->ae.ssid &&
|
|
tsid == pos->ae.tsid &&
|
|
tclass == pos->ae.tclass &&
|
|
seqno == pos->ae.avd.seqno){
|
|
orig = pos;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (!orig) {
|
|
rc = -ENOENT;
|
|
avc_node_kill(node);
|
|
goto out_unlock;
|
|
}
|
|
|
|
/*
|
|
* Copy and replace original node.
|
|
*/
|
|
|
|
avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd);
|
|
|
|
switch (event) {
|
|
case AVC_CALLBACK_GRANT:
|
|
node->ae.avd.allowed |= perms;
|
|
break;
|
|
case AVC_CALLBACK_TRY_REVOKE:
|
|
case AVC_CALLBACK_REVOKE:
|
|
node->ae.avd.allowed &= ~perms;
|
|
break;
|
|
case AVC_CALLBACK_AUDITALLOW_ENABLE:
|
|
node->ae.avd.auditallow |= perms;
|
|
break;
|
|
case AVC_CALLBACK_AUDITALLOW_DISABLE:
|
|
node->ae.avd.auditallow &= ~perms;
|
|
break;
|
|
case AVC_CALLBACK_AUDITDENY_ENABLE:
|
|
node->ae.avd.auditdeny |= perms;
|
|
break;
|
|
case AVC_CALLBACK_AUDITDENY_DISABLE:
|
|
node->ae.avd.auditdeny &= ~perms;
|
|
break;
|
|
}
|
|
avc_node_replace(node, orig);
|
|
out_unlock:
|
|
spin_unlock_irqrestore(lock, flag);
|
|
out:
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* avc_flush - Flush the cache
|
|
*/
|
|
static void avc_flush(void)
|
|
{
|
|
struct hlist_head *head;
|
|
struct hlist_node *next;
|
|
struct avc_node *node;
|
|
spinlock_t *lock;
|
|
unsigned long flag;
|
|
int i;
|
|
|
|
for (i = 0; i < AVC_CACHE_SLOTS; i++) {
|
|
head = &avc_cache.slots[i];
|
|
lock = &avc_cache.slots_lock[i];
|
|
|
|
spin_lock_irqsave(lock, flag);
|
|
/*
|
|
* With preemptable RCU, the outer spinlock does not
|
|
* prevent RCU grace periods from ending.
|
|
*/
|
|
rcu_read_lock();
|
|
hlist_for_each_entry(node, next, head, list)
|
|
avc_node_delete(node);
|
|
rcu_read_unlock();
|
|
spin_unlock_irqrestore(lock, flag);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* avc_ss_reset - Flush the cache and revalidate migrated permissions.
|
|
* @seqno: policy sequence number
|
|
*/
|
|
int avc_ss_reset(u32 seqno)
|
|
{
|
|
struct avc_callback_node *c;
|
|
int rc = 0, tmprc;
|
|
|
|
avc_flush();
|
|
|
|
for (c = avc_callbacks; c; c = c->next) {
|
|
if (c->events & AVC_CALLBACK_RESET) {
|
|
tmprc = c->callback(AVC_CALLBACK_RESET,
|
|
0, 0, 0, 0, NULL);
|
|
/* save the first error encountered for the return
|
|
value and continue processing the callbacks */
|
|
if (!rc)
|
|
rc = tmprc;
|
|
}
|
|
}
|
|
|
|
avc_latest_notif_update(seqno, 0);
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* avc_has_perm_noaudit - Check permissions but perform no auditing.
|
|
* @ssid: source security identifier
|
|
* @tsid: target security identifier
|
|
* @tclass: target security class
|
|
* @requested: requested permissions, interpreted based on @tclass
|
|
* @flags: AVC_STRICT or 0
|
|
* @avd: access vector decisions
|
|
*
|
|
* Check the AVC to determine whether the @requested permissions are granted
|
|
* for the SID pair (@ssid, @tsid), interpreting the permissions
|
|
* based on @tclass, and call the security server on a cache miss to obtain
|
|
* a new decision and add it to the cache. Return a copy of the decisions
|
|
* in @avd. Return %0 if all @requested permissions are granted,
|
|
* -%EACCES if any permissions are denied, or another -errno upon
|
|
* other errors. This function is typically called by avc_has_perm(),
|
|
* but may also be called directly to separate permission checking from
|
|
* auditing, e.g. in cases where a lock must be held for the check but
|
|
* should be released for the auditing.
|
|
*/
|
|
int avc_has_perm_noaudit(u32 ssid, u32 tsid,
|
|
u16 tclass, u32 requested,
|
|
unsigned flags,
|
|
struct av_decision *in_avd)
|
|
{
|
|
struct avc_node *node;
|
|
struct av_decision avd_entry, *avd;
|
|
int rc = 0;
|
|
u32 denied;
|
|
|
|
BUG_ON(!requested);
|
|
|
|
rcu_read_lock();
|
|
|
|
node = avc_lookup(ssid, tsid, tclass);
|
|
if (!node) {
|
|
rcu_read_unlock();
|
|
|
|
if (in_avd)
|
|
avd = in_avd;
|
|
else
|
|
avd = &avd_entry;
|
|
|
|
rc = security_compute_av(ssid, tsid, tclass, requested, avd);
|
|
if (rc)
|
|
goto out;
|
|
rcu_read_lock();
|
|
node = avc_insert(ssid, tsid, tclass, avd);
|
|
} else {
|
|
if (in_avd)
|
|
memcpy(in_avd, &node->ae.avd, sizeof(*in_avd));
|
|
avd = &node->ae.avd;
|
|
}
|
|
|
|
denied = requested & ~(avd->allowed);
|
|
|
|
if (denied) {
|
|
if (flags & AVC_STRICT)
|
|
rc = -EACCES;
|
|
else if (!selinux_enforcing || (avd->flags & AVD_FLAGS_PERMISSIVE))
|
|
avc_update_node(AVC_CALLBACK_GRANT, requested, ssid,
|
|
tsid, tclass, avd->seqno);
|
|
else
|
|
rc = -EACCES;
|
|
}
|
|
|
|
rcu_read_unlock();
|
|
out:
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* avc_has_perm - Check permissions and perform any appropriate auditing.
|
|
* @ssid: source security identifier
|
|
* @tsid: target security identifier
|
|
* @tclass: target security class
|
|
* @requested: requested permissions, interpreted based on @tclass
|
|
* @auditdata: auxiliary audit data
|
|
*
|
|
* Check the AVC to determine whether the @requested permissions are granted
|
|
* for the SID pair (@ssid, @tsid), interpreting the permissions
|
|
* based on @tclass, and call the security server on a cache miss to obtain
|
|
* a new decision and add it to the cache. Audit the granting or denial of
|
|
* permissions in accordance with the policy. Return %0 if all @requested
|
|
* permissions are granted, -%EACCES if any permissions are denied, or
|
|
* another -errno upon other errors.
|
|
*/
|
|
int avc_has_perm(u32 ssid, u32 tsid, u16 tclass,
|
|
u32 requested, struct common_audit_data *auditdata)
|
|
{
|
|
struct av_decision avd;
|
|
int rc;
|
|
|
|
rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, 0, &avd);
|
|
avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata);
|
|
return rc;
|
|
}
|
|
|
|
u32 avc_policy_seqno(void)
|
|
{
|
|
return avc_cache.latest_notif;
|
|
}
|
|
|
|
void avc_disable(void)
|
|
{
|
|
/*
|
|
* If you are looking at this because you have realized that we are
|
|
* not destroying the avc_node_cachep it might be easy to fix, but
|
|
* I don't know the memory barrier semantics well enough to know. It's
|
|
* possible that some other task dereferenced security_ops when
|
|
* it still pointed to selinux operations. If that is the case it's
|
|
* possible that it is about to use the avc and is about to need the
|
|
* avc_node_cachep. I know I could wrap the security.c security_ops call
|
|
* in an rcu_lock, but seriously, it's not worth it. Instead I just flush
|
|
* the cache and get that memory back.
|
|
*/
|
|
if (avc_node_cachep) {
|
|
avc_flush();
|
|
/* kmem_cache_destroy(avc_node_cachep); */
|
|
}
|
|
}
|