linux/security/selinux/avc.c
Sasha Levin b67bfe0d42 hlist: drop the node parameter from iterators
I'm not sure why, but the hlist for each entry iterators were conceived

        list_for_each_entry(pos, head, member)

The hlist ones were greedy and wanted an extra parameter:

        hlist_for_each_entry(tpos, pos, head, member)

Why did they need an extra pos parameter? I'm not quite sure. Not only
they don't really need it, it also prevents the iterator from looking
exactly like the list iterator, which is unfortunate.

Besides the semantic patch, there was some manual work required:

 - Fix up the actual hlist iterators in linux/list.h
 - Fix up the declaration of other iterators based on the hlist ones.
 - A very small amount of places were using the 'node' parameter, this
 was modified to use 'obj->member' instead.
 - Coccinelle didn't handle the hlist_for_each_entry_safe iterator
 properly, so those had to be fixed up manually.

The semantic patch which is mostly the work of Peter Senna Tschudin is here:

@@
iterator name hlist_for_each_entry, hlist_for_each_entry_continue, hlist_for_each_entry_from, hlist_for_each_entry_rcu, hlist_for_each_entry_rcu_bh, hlist_for_each_entry_continue_rcu_bh, for_each_busy_worker, ax25_uid_for_each, ax25_for_each, inet_bind_bucket_for_each, sctp_for_each_hentry, sk_for_each, sk_for_each_rcu, sk_for_each_from, sk_for_each_safe, sk_for_each_bound, hlist_for_each_entry_safe, hlist_for_each_entry_continue_rcu, nr_neigh_for_each, nr_neigh_for_each_safe, nr_node_for_each, nr_node_for_each_safe, for_each_gfn_indirect_valid_sp, for_each_gfn_sp, for_each_host;

type T;
expression a,c,d,e;
identifier b;
statement S;
@@

-T b;
    <+... when != b
(
hlist_for_each_entry(a,
- b,
c, d) S
|
hlist_for_each_entry_continue(a,
- b,
c) S
|
hlist_for_each_entry_from(a,
- b,
c) S
|
hlist_for_each_entry_rcu(a,
- b,
c, d) S
|
hlist_for_each_entry_rcu_bh(a,
- b,
c, d) S
|
hlist_for_each_entry_continue_rcu_bh(a,
- b,
c) S
|
for_each_busy_worker(a, c,
- b,
d) S
|
ax25_uid_for_each(a,
- b,
c) S
|
ax25_for_each(a,
- b,
c) S
|
inet_bind_bucket_for_each(a,
- b,
c) S
|
sctp_for_each_hentry(a,
- b,
c) S
|
sk_for_each(a,
- b,
c) S
|
sk_for_each_rcu(a,
- b,
c) S
|
sk_for_each_from
-(a, b)
+(a)
S
+ sk_for_each_from(a) S
|
sk_for_each_safe(a,
- b,
c, d) S
|
sk_for_each_bound(a,
- b,
c) S
|
hlist_for_each_entry_safe(a,
- b,
c, d, e) S
|
hlist_for_each_entry_continue_rcu(a,
- b,
c) S
|
nr_neigh_for_each(a,
- b,
c) S
|
nr_neigh_for_each_safe(a,
- b,
c, d) S
|
nr_node_for_each(a,
- b,
c) S
|
nr_node_for_each_safe(a,
- b,
c, d) S
|
- for_each_gfn_sp(a, c, d, b) S
+ for_each_gfn_sp(a, c, d) S
|
- for_each_gfn_indirect_valid_sp(a, c, d, b) S
+ for_each_gfn_indirect_valid_sp(a, c, d) S
|
for_each_host(a,
- b,
c) S
|
for_each_host_safe(a,
- b,
c, d) S
|
for_each_mesh_entry(a,
- b,
c, d) S
)
    ...+>

[akpm@linux-foundation.org: drop bogus change from net/ipv4/raw.c]
[akpm@linux-foundation.org: drop bogus hunk from net/ipv6/raw.c]
[akpm@linux-foundation.org: checkpatch fixes]
[akpm@linux-foundation.org: fix warnings]
[akpm@linux-foudnation.org: redo intrusive kvm changes]
Tested-by: Peter Senna Tschudin <peter.senna@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-27 19:10:24 -08:00

798 lines
20 KiB
C

/*
* Implementation of the kernel access vector cache (AVC).
*
* Authors: Stephen Smalley, <sds@epoch.ncsc.mil>
* James Morris <jmorris@redhat.com>
*
* Update: KaiGai, Kohei <kaigai@ak.jp.nec.com>
* Replaced the avc_lock spinlock by RCU.
*
* Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com>
*
* 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.
*/
#include <linux/types.h>
#include <linux/stddef.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/dcache.h>
#include <linux/init.h>
#include <linux/skbuff.h>
#include <linux/percpu.h>
#include <net/sock.h>
#include <linux/un.h>
#include <net/af_unix.h>
#include <linux/ip.h>
#include <linux/audit.h>
#include <linux/ipv6.h>
#include <net/ipv6.h>
#include "avc.h"
#include "avc_ss.h"
#include "classmap.h"
#define AVC_CACHE_SLOTS 512
#define AVC_DEF_CACHE_THRESHOLD 512
#define AVC_CACHE_RECLAIM 16
#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
#define avc_cache_stats_incr(field) this_cpu_inc(avc_cache_stats.field)
#else
#define avc_cache_stats_incr(field) do {} while (0)
#endif
struct avc_entry {
u32 ssid;
u32 tsid;
u16 tclass;
struct av_decision avd;
};
struct avc_node {
struct avc_entry ae;
struct hlist_node list; /* anchored in avc_cache->slots[i] */
struct rcu_head rhead;
};
struct avc_cache {
struct hlist_head slots[AVC_CACHE_SLOTS]; /* head for avc_node->list */
spinlock_t slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */
atomic_t lru_hint; /* LRU hint for reclaim scan */
atomic_t active_nodes;
u32 latest_notif; /* latest revocation notification */
};
struct avc_callback_node {
int (*callback) (u32 event);
u32 events;
struct avc_callback_node *next;
};
/* Exported via selinufs */
unsigned int avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
#endif
static struct avc_cache avc_cache;
static struct avc_callback_node *avc_callbacks;
static struct kmem_cache *avc_node_cachep;
static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass)
{
return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1);
}
/**
* avc_dump_av - Display an access vector in human-readable form.
* @tclass: target security class
* @av: access vector
*/
static void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av)
{
const char **perms;
int i, perm;
if (av == 0) {
audit_log_format(ab, " null");
return;
}
perms = secclass_map[tclass-1].perms;
audit_log_format(ab, " {");
i = 0;
perm = 1;
while (i < (sizeof(av) * 8)) {
if ((perm & av) && perms[i]) {
audit_log_format(ab, " %s", perms[i]);
av &= ~perm;
}
i++;
perm <<= 1;
}
if (av)
audit_log_format(ab, " 0x%x", av);
audit_log_format(ab, " }");
}
/**
* avc_dump_query - Display a SID pair and a class in human-readable form.
* @ssid: source security identifier
* @tsid: target security identifier
* @tclass: target security class
*/
static void avc_dump_query(struct audit_buffer *ab, u32 ssid, u32 tsid, u16 tclass)
{
int rc;
char *scontext;
u32 scontext_len;
rc = security_sid_to_context(ssid, &scontext, &scontext_len);
if (rc)
audit_log_format(ab, "ssid=%d", ssid);
else {
audit_log_format(ab, "scontext=%s", scontext);
kfree(scontext);
}
rc = security_sid_to_context(tsid, &scontext, &scontext_len);
if (rc)
audit_log_format(ab, " tsid=%d", tsid);
else {
audit_log_format(ab, " tcontext=%s", scontext);
kfree(scontext);
}
BUG_ON(tclass >= ARRAY_SIZE(secclass_map));
audit_log_format(ab, " tclass=%s", secclass_map[tclass-1].name);
}
/**
* avc_init - Initialize the AVC.
*
* Initialize the access vector cache.
*/
void __init avc_init(void)
{
int i;
for (i = 0; i < AVC_CACHE_SLOTS; i++) {
INIT_HLIST_HEAD(&avc_cache.slots[i]);
spin_lock_init(&avc_cache.slots_lock[i]);
}
atomic_set(&avc_cache.active_nodes, 0);
atomic_set(&avc_cache.lru_hint, 0);
avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node),
0, SLAB_PANIC, NULL);
audit_log(current->audit_context, GFP_KERNEL, AUDIT_KERNEL, "AVC INITIALIZED\n");
}
int avc_get_hash_stats(char *page)
{
int i, chain_len, max_chain_len, slots_used;
struct avc_node *node;
struct hlist_head *head;
rcu_read_lock();
slots_used = 0;
max_chain_len = 0;
for (i = 0; i < AVC_CACHE_SLOTS; i++) {
head = &avc_cache.slots[i];
if (!hlist_empty(head)) {
slots_used++;
chain_len = 0;
hlist_for_each_entry_rcu(node, head, list)
chain_len++;
if (chain_len > max_chain_len)
max_chain_len = chain_len;
}
}
rcu_read_unlock();
return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
"longest chain: %d\n",
atomic_read(&avc_cache.active_nodes),
slots_used, AVC_CACHE_SLOTS, max_chain_len);
}
static void avc_node_free(struct rcu_head *rhead)
{
struct avc_node *node = container_of(rhead, struct avc_node, rhead);
kmem_cache_free(avc_node_cachep, node);
avc_cache_stats_incr(frees);
}
static void avc_node_delete(struct avc_node *node)
{
hlist_del_rcu(&node->list);
call_rcu(&node->rhead, avc_node_free);
atomic_dec(&avc_cache.active_nodes);
}
static void avc_node_kill(struct avc_node *node)
{
kmem_cache_free(avc_node_cachep, node);
avc_cache_stats_incr(frees);
atomic_dec(&avc_cache.active_nodes);
}
static void avc_node_replace(struct avc_node *new, struct avc_node *old)
{
hlist_replace_rcu(&old->list, &new->list);
call_rcu(&old->rhead, avc_node_free);
atomic_dec(&avc_cache.active_nodes);
}
static inline int avc_reclaim_node(void)
{
struct avc_node *node;
int hvalue, try, ecx;
unsigned long flags;
struct hlist_head *head;
spinlock_t *lock;
for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) {
hvalue = atomic_inc_return(&avc_cache.lru_hint) & (AVC_CACHE_SLOTS - 1);
head = &avc_cache.slots[hvalue];
lock = &avc_cache.slots_lock[hvalue];
if (!spin_trylock_irqsave(lock, flags))
continue;
rcu_read_lock();
hlist_for_each_entry(node, head, list) {
avc_node_delete(node);
avc_cache_stats_incr(reclaims);
ecx++;
if (ecx >= AVC_CACHE_RECLAIM) {
rcu_read_unlock();
spin_unlock_irqrestore(lock, flags);
goto out;
}
}
rcu_read_unlock();
spin_unlock_irqrestore(lock, flags);
}
out:
return ecx;
}
static struct avc_node *avc_alloc_node(void)
{
struct avc_node *node;
node = kmem_cache_zalloc(avc_node_cachep, GFP_ATOMIC|__GFP_NOMEMALLOC);
if (!node)
goto out;
INIT_HLIST_NODE(&node->list);
avc_cache_stats_incr(allocations);
if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold)
avc_reclaim_node();
out:
return node;
}
static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
{
node->ae.ssid = ssid;
node->ae.tsid = tsid;
node->ae.tclass = tclass;
memcpy(&node->ae.avd, avd, sizeof(node->ae.avd));
}
static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass)
{
struct avc_node *node, *ret = NULL;
int hvalue;
struct hlist_head *head;
hvalue = avc_hash(ssid, tsid, tclass);
head = &avc_cache.slots[hvalue];
hlist_for_each_entry_rcu(node, head, list) {
if (ssid == node->ae.ssid &&
tclass == node->ae.tclass &&
tsid == node->ae.tsid) {
ret = node;
break;
}
}
return ret;
}
/**
* avc_lookup - Look up an AVC entry.
* @ssid: source security identifier
* @tsid: target security identifier
* @tclass: target security class
*
* Look up an AVC entry that is valid for the
* (@ssid, @tsid), interpreting the permissions
* based on @tclass. If a valid AVC entry exists,
* then this function returns the avc_node.
* Otherwise, this function returns NULL.
*/
static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass)
{
struct avc_node *node;
avc_cache_stats_incr(lookups);
node = avc_search_node(ssid, tsid, tclass);
if (node)
return node;
avc_cache_stats_incr(misses);
return NULL;
}
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(&notif_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(&notif_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;
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, 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);
}
/* This is the slow part of avc audit with big stack footprint */
noinline int slow_avc_audit(u32 ssid, u32 tsid, u16 tclass,
u32 requested, u32 audited, u32 denied,
struct common_audit_data *a,
unsigned flags)
{
struct common_audit_data stack_data;
struct selinux_audit_data sad;
if (!a) {
a = &stack_data;
a->type = LSM_AUDIT_DATA_NONE;
}
/*
* When in a RCU walk do the audit on the RCU retry. This is because
* the collection of the dname in an inode audit message is not RCU
* safe. Note this may drop some audits when the situation changes
* during retry. However this is logically just as if the operation
* happened a little later.
*/
if ((a->type == LSM_AUDIT_DATA_INODE) &&
(flags & MAY_NOT_BLOCK))
return -ECHILD;
sad.tclass = tclass;
sad.requested = requested;
sad.ssid = ssid;
sad.tsid = tsid;
sad.audited = audited;
sad.denied = denied;
a->selinux_audit_data = &sad;
common_lsm_audit(a, avc_audit_pre_callback, avc_audit_post_callback);
return 0;
}
/**
* avc_add_callback - Register a callback for security events.
* @callback: callback function
* @events: security events
*
* Register a callback function for events in the set @events.
* Returns %0 on success or -%ENOMEM if insufficient memory
* exists to add the callback.
*/
int __init avc_add_callback(int (*callback)(u32 event), u32 events)
{
struct avc_callback_node *c;
int rc = 0;
c = kmalloc(sizeof(*c), GFP_KERNEL);
if (!c) {
rc = -ENOMEM;
goto out;
}
c->callback = callback;
c->events = events;
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 updates 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;
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, 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 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, 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);
/* 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;
}
/*
* Slow-path helper function for avc_has_perm_noaudit,
* when the avc_node lookup fails. We get called with
* the RCU read lock held, and need to return with it
* still held, but drop if for the security compute.
*
* Don't inline this, since it's the slow-path and just
* results in a bigger stack frame.
*/
static noinline struct avc_node *avc_compute_av(u32 ssid, u32 tsid,
u16 tclass, struct av_decision *avd)
{
rcu_read_unlock();
security_compute_av(ssid, tsid, tclass, avd);
rcu_read_lock();
return avc_insert(ssid, tsid, tclass, avd);
}
static noinline int avc_denied(u32 ssid, u32 tsid,
u16 tclass, u32 requested,
unsigned flags,
struct av_decision *avd)
{
if (flags & AVC_STRICT)
return -EACCES;
if (selinux_enforcing && !(avd->flags & AVD_FLAGS_PERMISSIVE))
return -EACCES;
avc_update_node(AVC_CALLBACK_GRANT, requested, ssid,
tsid, tclass, avd->seqno);
return 0;
}
/**
* 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.
*/
inline int avc_has_perm_noaudit(u32 ssid, u32 tsid,
u16 tclass, u32 requested,
unsigned flags,
struct av_decision *avd)
{
struct avc_node *node;
int rc = 0;
u32 denied;
BUG_ON(!requested);
rcu_read_lock();
node = avc_lookup(ssid, tsid, tclass);
if (unlikely(!node)) {
node = avc_compute_av(ssid, tsid, tclass, avd);
} else {
memcpy(avd, &node->ae.avd, sizeof(*avd));
avd = &node->ae.avd;
}
denied = requested & ~(avd->allowed);
if (unlikely(denied))
rc = avc_denied(ssid, tsid, tclass, requested, flags, avd);
rcu_read_unlock();
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
* @flags: VFS walk flags
*
* 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_flags(u32 ssid, u32 tsid, u16 tclass,
u32 requested, struct common_audit_data *auditdata,
unsigned flags)
{
struct av_decision avd;
int rc, rc2;
rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, 0, &avd);
rc2 = avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata,
flags);
if (rc2)
return rc2;
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); */
}
}