// SPDX-License-Identifier: GPL-2.0-only

  /*
   * Pkey table
   *
   * SELinux must keep a mapping of Infinband PKEYs to labels/SIDs.  This
   * mapping is maintained as part of the normal policy but a fast cache is
   * needed to reduce the lookup overhead.
   *
   * This code is heavily based on the "netif" and "netport" concept originally
   * developed by
   * James Morris <jmorris@redhat.com> and
   * Paul Moore <paul@paul-moore.com>
   *   (see security/selinux/netif.c and security/selinux/netport.c for more
   *   information)

   */
  
  /*
   * (c) Mellanox Technologies, 2016

   */
  
  #include <linux/types.h>
  #include <linux/rcupdate.h>
  #include <linux/list.h>
  #include <linux/spinlock.h>
  
  #include "ibpkey.h"
  #include "objsec.h"
  
  #define SEL_PKEY_HASH_SIZE       256
  #define SEL_PKEY_HASH_BKT_LIMIT   16
  
  struct sel_ib_pkey_bkt {
  	int size;
  	struct list_head list;
  };
  
  struct sel_ib_pkey {
  	struct pkey_security_struct psec;
  	struct list_head list;
  	struct rcu_head rcu;
  };
  
  static LIST_HEAD(sel_ib_pkey_list);
  static DEFINE_SPINLOCK(sel_ib_pkey_lock);
  static struct sel_ib_pkey_bkt sel_ib_pkey_hash[SEL_PKEY_HASH_SIZE];
  
  /**
   * sel_ib_pkey_hashfn - Hashing function for the pkey table
   * @pkey: pkey number
   *
   * Description:
   * This is the hashing function for the pkey table, it returns the bucket
   * number for the given pkey.
   *
   */
  static unsigned int sel_ib_pkey_hashfn(u16 pkey)
  {
  	return (pkey & (SEL_PKEY_HASH_SIZE - 1));
  }
  
  /**
   * sel_ib_pkey_find - Search for a pkey record
   * @subnet_prefix: subnet_prefix
   * @pkey_num: pkey_num
   *
   * Description:
   * Search the pkey table and return the matching record.  If an entry
   * can not be found in the table return NULL.
   *
   */
  static struct sel_ib_pkey *sel_ib_pkey_find(u64 subnet_prefix, u16 pkey_num)
  {
  	unsigned int idx;
  	struct sel_ib_pkey *pkey;
  
  	idx = sel_ib_pkey_hashfn(pkey_num);
  	list_for_each_entry_rcu(pkey, &sel_ib_pkey_hash[idx].list, list) {
  		if (pkey->psec.pkey == pkey_num &&
  		    pkey->psec.subnet_prefix == subnet_prefix)
  			return pkey;
  	}
  
  	return NULL;
  }
  
  /**
   * sel_ib_pkey_insert - Insert a new pkey into the table
   * @pkey: the new pkey record
   *
   * Description:
   * Add a new pkey record to the hash table.
   *
   */
  static void sel_ib_pkey_insert(struct sel_ib_pkey *pkey)
  {
  	unsigned int idx;
  
  	/* we need to impose a limit on the growth of the hash table so check
  	 * this bucket to make sure it is within the specified bounds
  	 */
  	idx = sel_ib_pkey_hashfn(pkey->psec.pkey);
  	list_add_rcu(&pkey->list, &sel_ib_pkey_hash[idx].list);
  	if (sel_ib_pkey_hash[idx].size == SEL_PKEY_HASH_BKT_LIMIT) {
  		struct sel_ib_pkey *tail;
  
  		tail = list_entry(
  			rcu_dereference_protected(
  				sel_ib_pkey_hash[idx].list.prev,
  				lockdep_is_held(&sel_ib_pkey_lock)),
  			struct sel_ib_pkey, list);
  		list_del_rcu(&tail->list);
  		kfree_rcu(tail, rcu);
  	} else {
  		sel_ib_pkey_hash[idx].size++;
  	}
  }
  
  /**
   * sel_ib_pkey_sid_slow - Lookup the SID of a pkey using the policy
   * @subnet_prefix: subnet prefix
   * @pkey_num: pkey number
   * @sid: pkey SID
   *
   * Description:
   * This function determines the SID of a pkey by querying the security
   * policy.  The result is added to the pkey table to speedup future
   * queries.  Returns zero on success, negative values on failure.
   *
   */
  static int sel_ib_pkey_sid_slow(u64 subnet_prefix, u16 pkey_num, u32 *sid)
  {
  	int ret;
  	struct sel_ib_pkey *pkey;
  	struct sel_ib_pkey *new = NULL;
  	unsigned long flags;
  
  	spin_lock_irqsave(&sel_ib_pkey_lock, flags);
  	pkey = sel_ib_pkey_find(subnet_prefix, pkey_num);
  	if (pkey) {
  		*sid = pkey->psec.sid;
  		spin_unlock_irqrestore(&sel_ib_pkey_lock, flags);
  		return 0;
  	}

  	ret = security_ib_pkey_sid(&selinux_state, subnet_prefix, pkey_num,
  				   sid);

  	if (ret)
  		goto out;
  
  	/* If this memory allocation fails still return 0. The SID
  	 * is valid, it just won't be added to the cache.
  	 */
  	new = kzalloc(sizeof(*new), GFP_ATOMIC);
  	if (!new)
  		goto out;
  
  	new->psec.subnet_prefix = subnet_prefix;
  	new->psec.pkey = pkey_num;
  	new->psec.sid = *sid;
  	sel_ib_pkey_insert(new);
  
  out:
  	spin_unlock_irqrestore(&sel_ib_pkey_lock, flags);
  	return ret;
  }
  
  /**
   * sel_ib_pkey_sid - Lookup the SID of a PKEY
   * @subnet_prefix: subnet_prefix
   * @pkey_num: pkey number
   * @sid: pkey SID
   *
   * Description:
   * This function determines the SID of a PKEY using the fastest method
   * possible.  First the pkey table is queried, but if an entry can't be found
   * then the policy is queried and the result is added to the table to speedup
   * future queries.  Returns zero on success, negative values on failure.
   *
   */
  int sel_ib_pkey_sid(u64 subnet_prefix, u16 pkey_num, u32 *sid)
  {
  	struct sel_ib_pkey *pkey;
  
  	rcu_read_lock();
  	pkey = sel_ib_pkey_find(subnet_prefix, pkey_num);
  	if (pkey) {
  		*sid = pkey->psec.sid;
  		rcu_read_unlock();
  		return 0;
  	}
  	rcu_read_unlock();
  
  	return sel_ib_pkey_sid_slow(subnet_prefix, pkey_num, sid);
  }
  
  /**
   * sel_ib_pkey_flush - Flush the entire pkey table
   *
   * Description:
   * Remove all entries from the pkey table
   *
   */
  void sel_ib_pkey_flush(void)
  {
  	unsigned int idx;
  	struct sel_ib_pkey *pkey, *pkey_tmp;
  	unsigned long flags;
  
  	spin_lock_irqsave(&sel_ib_pkey_lock, flags);
  	for (idx = 0; idx < SEL_PKEY_HASH_SIZE; idx++) {
  		list_for_each_entry_safe(pkey, pkey_tmp,
  					 &sel_ib_pkey_hash[idx].list, list) {
  			list_del_rcu(&pkey->list);
  			kfree_rcu(pkey, rcu);
  		}
  		sel_ib_pkey_hash[idx].size = 0;
  	}
  	spin_unlock_irqrestore(&sel_ib_pkey_lock, flags);
  }
  
  static __init int sel_ib_pkey_init(void)
  {
  	int iter;

  	if (!selinux_enabled_boot)

  		return 0;
  
  	for (iter = 0; iter < SEL_PKEY_HASH_SIZE; iter++) {
  		INIT_LIST_HEAD(&sel_ib_pkey_hash[iter].list);
  		sel_ib_pkey_hash[iter].size = 0;
  	}
  
  	return 0;
  }
  
  subsys_initcall(sel_ib_pkey_init);