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![Paul Moore](/assets/img/avatar_default.png)
When running the SELinux code through sparse, there are a handful of warnings. This patch resolves some of these warnings caused by "__rcu" mismatches. % make W=1 C=1 security/selinux/ Signed-off-by: Paul Moore <paul@paul-moore.com>
237 lines
5.6 KiB
C
237 lines
5.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Pkey table
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*
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* SELinux must keep a mapping of Infinband PKEYs to labels/SIDs. This
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* mapping is maintained as part of the normal policy but a fast cache is
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* needed to reduce the lookup overhead.
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*
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* This code is heavily based on the "netif" and "netport" concept originally
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* developed by
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* James Morris <jmorris@redhat.com> and
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* Paul Moore <paul@paul-moore.com>
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* (see security/selinux/netif.c and security/selinux/netport.c for more
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* information)
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*/
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/*
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* (c) Mellanox Technologies, 2016
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*/
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#include <linux/types.h>
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#include <linux/rcupdate.h>
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#include <linux/list.h>
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#include <linux/spinlock.h>
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#include "ibpkey.h"
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#include "objsec.h"
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#define SEL_PKEY_HASH_SIZE 256
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#define SEL_PKEY_HASH_BKT_LIMIT 16
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struct sel_ib_pkey_bkt {
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int size;
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struct list_head list;
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};
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struct sel_ib_pkey {
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struct pkey_security_struct psec;
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struct list_head list;
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struct rcu_head rcu;
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};
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static DEFINE_SPINLOCK(sel_ib_pkey_lock);
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static struct sel_ib_pkey_bkt sel_ib_pkey_hash[SEL_PKEY_HASH_SIZE];
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/**
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* sel_ib_pkey_hashfn - Hashing function for the pkey table
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* @pkey: pkey number
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*
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* Description:
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* This is the hashing function for the pkey table, it returns the bucket
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* number for the given pkey.
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*
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*/
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static unsigned int sel_ib_pkey_hashfn(u16 pkey)
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{
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return (pkey & (SEL_PKEY_HASH_SIZE - 1));
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}
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/**
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* sel_ib_pkey_find - Search for a pkey record
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* @subnet_prefix: subnet_prefix
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* @pkey_num: pkey_num
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*
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* Description:
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* Search the pkey table and return the matching record. If an entry
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* can not be found in the table return NULL.
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*
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*/
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static struct sel_ib_pkey *sel_ib_pkey_find(u64 subnet_prefix, u16 pkey_num)
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{
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unsigned int idx;
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struct sel_ib_pkey *pkey;
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idx = sel_ib_pkey_hashfn(pkey_num);
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list_for_each_entry_rcu(pkey, &sel_ib_pkey_hash[idx].list, list) {
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if (pkey->psec.pkey == pkey_num &&
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pkey->psec.subnet_prefix == subnet_prefix)
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return pkey;
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}
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return NULL;
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}
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/**
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* sel_ib_pkey_insert - Insert a new pkey into the table
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* @pkey: the new pkey record
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*
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* Description:
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* Add a new pkey record to the hash table.
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*
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*/
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static void sel_ib_pkey_insert(struct sel_ib_pkey *pkey)
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{
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unsigned int idx;
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/* we need to impose a limit on the growth of the hash table so check
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* this bucket to make sure it is within the specified bounds
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*/
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idx = sel_ib_pkey_hashfn(pkey->psec.pkey);
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list_add_rcu(&pkey->list, &sel_ib_pkey_hash[idx].list);
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if (sel_ib_pkey_hash[idx].size == SEL_PKEY_HASH_BKT_LIMIT) {
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struct sel_ib_pkey *tail;
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tail = list_entry(
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rcu_dereference_protected(
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list_tail_rcu(&sel_ib_pkey_hash[idx].list),
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lockdep_is_held(&sel_ib_pkey_lock)),
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struct sel_ib_pkey, list);
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list_del_rcu(&tail->list);
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kfree_rcu(tail, rcu);
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} else {
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sel_ib_pkey_hash[idx].size++;
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}
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}
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/**
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* sel_ib_pkey_sid_slow - Lookup the SID of a pkey using the policy
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* @subnet_prefix: subnet prefix
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* @pkey_num: pkey number
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* @sid: pkey SID
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*
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* Description:
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* This function determines the SID of a pkey by querying the security
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* policy. The result is added to the pkey table to speedup future
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* queries. Returns zero on success, negative values on failure.
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*
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*/
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static int sel_ib_pkey_sid_slow(u64 subnet_prefix, u16 pkey_num, u32 *sid)
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{
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int ret;
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struct sel_ib_pkey *pkey;
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struct sel_ib_pkey *new = NULL;
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unsigned long flags;
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spin_lock_irqsave(&sel_ib_pkey_lock, flags);
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pkey = sel_ib_pkey_find(subnet_prefix, pkey_num);
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if (pkey) {
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*sid = pkey->psec.sid;
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spin_unlock_irqrestore(&sel_ib_pkey_lock, flags);
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return 0;
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}
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ret = security_ib_pkey_sid(&selinux_state, subnet_prefix, pkey_num,
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sid);
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if (ret)
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goto out;
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/* If this memory allocation fails still return 0. The SID
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* is valid, it just won't be added to the cache.
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*/
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new = kzalloc(sizeof(*new), GFP_ATOMIC);
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if (!new) {
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ret = -ENOMEM;
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goto out;
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}
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new->psec.subnet_prefix = subnet_prefix;
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new->psec.pkey = pkey_num;
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new->psec.sid = *sid;
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sel_ib_pkey_insert(new);
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out:
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spin_unlock_irqrestore(&sel_ib_pkey_lock, flags);
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return ret;
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}
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/**
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* sel_ib_pkey_sid - Lookup the SID of a PKEY
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* @subnet_prefix: subnet_prefix
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* @pkey_num: pkey number
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* @sid: pkey SID
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*
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* Description:
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* This function determines the SID of a PKEY using the fastest method
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* possible. First the pkey table is queried, but if an entry can't be found
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* then the policy is queried and the result is added to the table to speedup
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* future queries. Returns zero on success, negative values on failure.
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*
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*/
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int sel_ib_pkey_sid(u64 subnet_prefix, u16 pkey_num, u32 *sid)
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{
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struct sel_ib_pkey *pkey;
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rcu_read_lock();
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pkey = sel_ib_pkey_find(subnet_prefix, pkey_num);
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if (pkey) {
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*sid = pkey->psec.sid;
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rcu_read_unlock();
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return 0;
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}
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rcu_read_unlock();
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return sel_ib_pkey_sid_slow(subnet_prefix, pkey_num, sid);
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}
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/**
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* sel_ib_pkey_flush - Flush the entire pkey table
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*
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* Description:
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* Remove all entries from the pkey table
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*
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*/
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void sel_ib_pkey_flush(void)
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{
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unsigned int idx;
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struct sel_ib_pkey *pkey, *pkey_tmp;
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unsigned long flags;
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spin_lock_irqsave(&sel_ib_pkey_lock, flags);
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for (idx = 0; idx < SEL_PKEY_HASH_SIZE; idx++) {
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list_for_each_entry_safe(pkey, pkey_tmp,
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&sel_ib_pkey_hash[idx].list, list) {
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list_del_rcu(&pkey->list);
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kfree_rcu(pkey, rcu);
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}
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sel_ib_pkey_hash[idx].size = 0;
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}
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spin_unlock_irqrestore(&sel_ib_pkey_lock, flags);
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}
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static __init int sel_ib_pkey_init(void)
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{
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int iter;
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if (!selinux_enabled_boot)
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return 0;
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for (iter = 0; iter < SEL_PKEY_HASH_SIZE; iter++) {
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INIT_LIST_HEAD(&sel_ib_pkey_hash[iter].list);
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sel_ib_pkey_hash[iter].size = 0;
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}
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return 0;
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}
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subsys_initcall(sel_ib_pkey_init);
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