4c3a0a254e
Currently, if the call to netlbl_domhsh_search succeeds the return result will still be NULL. Fix that, by returning the found entry (if any). Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Acked-by: Paul Moore <paul.moore@hp.com> Signed-off-by: David S. Miller <davem@davemloft.net>
441 lines
12 KiB
C
441 lines
12 KiB
C
/*
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* NetLabel Domain Hash Table
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*
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* This file manages the domain hash table that NetLabel uses to determine
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* which network labeling protocol to use for a given domain. The NetLabel
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* system manages static and dynamic label mappings for network protocols such
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* as CIPSO and RIPSO.
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*
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* Author: Paul Moore <paul.moore@hp.com>
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*
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*/
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/*
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* (c) Copyright Hewlett-Packard Development Company, L.P., 2006
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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 as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
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* the GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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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/skbuff.h>
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#include <linux/spinlock.h>
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#include <linux/string.h>
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#include <linux/audit.h>
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#include <net/netlabel.h>
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#include <net/cipso_ipv4.h>
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#include <asm/bug.h>
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#include "netlabel_mgmt.h"
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#include "netlabel_domainhash.h"
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#include "netlabel_user.h"
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struct netlbl_domhsh_tbl {
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struct list_head *tbl;
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u32 size;
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};
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/* Domain hash table */
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/* XXX - updates should be so rare that having one spinlock for the entire
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* hash table should be okay */
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static DEFINE_SPINLOCK(netlbl_domhsh_lock);
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static struct netlbl_domhsh_tbl *netlbl_domhsh = NULL;
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static struct netlbl_dom_map *netlbl_domhsh_def = NULL;
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/*
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* Domain Hash Table Helper Functions
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*/
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/**
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* netlbl_domhsh_free_entry - Frees a domain hash table entry
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* @entry: the entry's RCU field
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*
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* Description:
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* This function is designed to be used as a callback to the call_rcu()
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* function so that the memory allocated to a hash table entry can be released
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* safely.
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*
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*/
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static void netlbl_domhsh_free_entry(struct rcu_head *entry)
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{
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struct netlbl_dom_map *ptr;
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ptr = container_of(entry, struct netlbl_dom_map, rcu);
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kfree(ptr->domain);
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kfree(ptr);
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}
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/**
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* netlbl_domhsh_hash - Hashing function for the domain hash table
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* @domain: the domain name to hash
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*
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* Description:
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* This is the hashing function for the domain hash table, it returns the
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* correct bucket number for the domain. The caller is responsibile for
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* calling the rcu_read_[un]lock() functions.
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*
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*/
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static u32 netlbl_domhsh_hash(const char *key)
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{
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u32 iter;
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u32 val;
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u32 len;
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/* This is taken (with slight modification) from
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* security/selinux/ss/symtab.c:symhash() */
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for (iter = 0, val = 0, len = strlen(key); iter < len; iter++)
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val = (val << 4 | (val >> (8 * sizeof(u32) - 4))) ^ key[iter];
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return val & (rcu_dereference(netlbl_domhsh)->size - 1);
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}
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/**
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* netlbl_domhsh_search - Search for a domain entry
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* @domain: the domain
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*
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* Description:
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* Searches the domain hash table and returns a pointer to the hash table
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* entry if found, otherwise NULL is returned. The caller is responsibile for
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* the rcu hash table locks (i.e. the caller much call rcu_read_[un]lock()).
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*
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*/
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static struct netlbl_dom_map *netlbl_domhsh_search(const char *domain)
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{
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u32 bkt;
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struct netlbl_dom_map *iter;
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if (domain != NULL) {
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bkt = netlbl_domhsh_hash(domain);
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list_for_each_entry_rcu(iter,
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&rcu_dereference(netlbl_domhsh)->tbl[bkt],
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list)
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if (iter->valid && strcmp(iter->domain, domain) == 0)
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return iter;
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}
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return NULL;
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}
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/**
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* netlbl_domhsh_search_def - Search for a domain entry
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* @domain: the domain
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* @def: return default if no match is found
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*
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* Description:
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* Searches the domain hash table and returns a pointer to the hash table
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* entry if an exact match is found, if an exact match is not present in the
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* hash table then the default entry is returned if valid otherwise NULL is
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* returned. The caller is responsibile for the rcu hash table locks
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* (i.e. the caller much call rcu_read_[un]lock()).
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*
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*/
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static struct netlbl_dom_map *netlbl_domhsh_search_def(const char *domain)
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{
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struct netlbl_dom_map *entry;
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entry = netlbl_domhsh_search(domain);
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if (entry == NULL) {
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entry = rcu_dereference(netlbl_domhsh_def);
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if (entry != NULL && !entry->valid)
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entry = NULL;
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}
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return entry;
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}
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/*
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* Domain Hash Table Functions
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*/
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/**
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* netlbl_domhsh_init - Init for the domain hash
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* @size: the number of bits to use for the hash buckets
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*
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* Description:
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* Initializes the domain hash table, should be called only by
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* netlbl_user_init() during initialization. Returns zero on success, non-zero
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* values on error.
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*
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*/
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int netlbl_domhsh_init(u32 size)
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{
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u32 iter;
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struct netlbl_domhsh_tbl *hsh_tbl;
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if (size == 0)
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return -EINVAL;
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hsh_tbl = kmalloc(sizeof(*hsh_tbl), GFP_KERNEL);
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if (hsh_tbl == NULL)
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return -ENOMEM;
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hsh_tbl->size = 1 << size;
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hsh_tbl->tbl = kcalloc(hsh_tbl->size,
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sizeof(struct list_head),
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GFP_KERNEL);
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if (hsh_tbl->tbl == NULL) {
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kfree(hsh_tbl);
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return -ENOMEM;
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}
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for (iter = 0; iter < hsh_tbl->size; iter++)
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INIT_LIST_HEAD(&hsh_tbl->tbl[iter]);
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spin_lock(&netlbl_domhsh_lock);
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rcu_assign_pointer(netlbl_domhsh, hsh_tbl);
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spin_unlock(&netlbl_domhsh_lock);
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return 0;
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}
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/**
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* netlbl_domhsh_add - Adds a entry to the domain hash table
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* @entry: the entry to add
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* @audit_info: NetLabel audit information
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*
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* Description:
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* Adds a new entry to the domain hash table and handles any updates to the
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* lower level protocol handler (i.e. CIPSO). Returns zero on success,
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* negative on failure.
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*
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*/
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int netlbl_domhsh_add(struct netlbl_dom_map *entry,
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struct netlbl_audit *audit_info)
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{
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int ret_val;
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u32 bkt;
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struct audit_buffer *audit_buf;
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switch (entry->type) {
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case NETLBL_NLTYPE_UNLABELED:
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ret_val = 0;
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break;
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case NETLBL_NLTYPE_CIPSOV4:
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ret_val = cipso_v4_doi_domhsh_add(entry->type_def.cipsov4,
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entry->domain);
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break;
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default:
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return -EINVAL;
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}
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if (ret_val != 0)
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return ret_val;
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entry->valid = 1;
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INIT_RCU_HEAD(&entry->rcu);
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rcu_read_lock();
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spin_lock(&netlbl_domhsh_lock);
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if (entry->domain != NULL) {
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bkt = netlbl_domhsh_hash(entry->domain);
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if (netlbl_domhsh_search(entry->domain) == NULL)
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list_add_tail_rcu(&entry->list,
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&rcu_dereference(netlbl_domhsh)->tbl[bkt]);
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else
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ret_val = -EEXIST;
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} else {
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INIT_LIST_HEAD(&entry->list);
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if (rcu_dereference(netlbl_domhsh_def) == NULL)
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rcu_assign_pointer(netlbl_domhsh_def, entry);
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else
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ret_val = -EEXIST;
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}
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spin_unlock(&netlbl_domhsh_lock);
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audit_buf = netlbl_audit_start_common(AUDIT_MAC_MAP_ADD, audit_info);
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if (audit_buf != NULL) {
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audit_log_format(audit_buf,
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" nlbl_domain=%s",
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entry->domain ? entry->domain : "(default)");
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switch (entry->type) {
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case NETLBL_NLTYPE_UNLABELED:
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audit_log_format(audit_buf, " nlbl_protocol=unlbl");
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break;
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case NETLBL_NLTYPE_CIPSOV4:
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audit_log_format(audit_buf,
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" nlbl_protocol=cipsov4 cipso_doi=%u",
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entry->type_def.cipsov4->doi);
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break;
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}
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audit_log_format(audit_buf, " res=%u", ret_val == 0 ? 1 : 0);
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audit_log_end(audit_buf);
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}
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rcu_read_unlock();
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if (ret_val != 0) {
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switch (entry->type) {
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case NETLBL_NLTYPE_CIPSOV4:
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if (cipso_v4_doi_domhsh_remove(entry->type_def.cipsov4,
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entry->domain) != 0)
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BUG();
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break;
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}
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}
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return ret_val;
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}
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/**
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* netlbl_domhsh_add_default - Adds the default entry to the domain hash table
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* @entry: the entry to add
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* @audit_info: NetLabel audit information
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*
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* Description:
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* Adds a new default entry to the domain hash table and handles any updates
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* to the lower level protocol handler (i.e. CIPSO). Returns zero on success,
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* negative on failure.
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*
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*/
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int netlbl_domhsh_add_default(struct netlbl_dom_map *entry,
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struct netlbl_audit *audit_info)
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{
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return netlbl_domhsh_add(entry, audit_info);
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}
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/**
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* netlbl_domhsh_remove - Removes an entry from the domain hash table
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* @domain: the domain to remove
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* @audit_info: NetLabel audit information
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*
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* Description:
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* Removes an entry from the domain hash table and handles any updates to the
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* lower level protocol handler (i.e. CIPSO). Returns zero on success,
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* negative on failure.
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*
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*/
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int netlbl_domhsh_remove(const char *domain, struct netlbl_audit *audit_info)
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{
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int ret_val = -ENOENT;
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struct netlbl_dom_map *entry;
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struct audit_buffer *audit_buf;
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rcu_read_lock();
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if (domain)
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entry = netlbl_domhsh_search(domain);
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else
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entry = netlbl_domhsh_search_def(domain);
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if (entry == NULL)
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goto remove_return;
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switch (entry->type) {
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case NETLBL_NLTYPE_CIPSOV4:
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cipso_v4_doi_domhsh_remove(entry->type_def.cipsov4,
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entry->domain);
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break;
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}
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spin_lock(&netlbl_domhsh_lock);
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if (entry->valid) {
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entry->valid = 0;
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if (entry != rcu_dereference(netlbl_domhsh_def))
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list_del_rcu(&entry->list);
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else
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rcu_assign_pointer(netlbl_domhsh_def, NULL);
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ret_val = 0;
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}
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spin_unlock(&netlbl_domhsh_lock);
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audit_buf = netlbl_audit_start_common(AUDIT_MAC_MAP_DEL, audit_info);
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if (audit_buf != NULL) {
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audit_log_format(audit_buf,
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" nlbl_domain=%s res=%u",
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entry->domain ? entry->domain : "(default)",
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ret_val == 0 ? 1 : 0);
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audit_log_end(audit_buf);
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}
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remove_return:
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rcu_read_unlock();
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if (ret_val == 0)
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call_rcu(&entry->rcu, netlbl_domhsh_free_entry);
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return ret_val;
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}
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/**
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* netlbl_domhsh_remove_default - Removes the default entry from the table
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* @audit_info: NetLabel audit information
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*
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* Description:
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* Removes/resets the default entry for the domain hash table and handles any
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* updates to the lower level protocol handler (i.e. CIPSO). Returns zero on
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* success, non-zero on failure.
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*
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*/
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int netlbl_domhsh_remove_default(struct netlbl_audit *audit_info)
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{
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return netlbl_domhsh_remove(NULL, audit_info);
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}
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/**
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* netlbl_domhsh_getentry - Get an entry from the domain hash table
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* @domain: the domain name to search for
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*
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* Description:
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* Look through the domain hash table searching for an entry to match @domain,
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* return a pointer to a copy of the entry or NULL. The caller is responsibile
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* for ensuring that rcu_read_[un]lock() is called.
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*
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*/
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struct netlbl_dom_map *netlbl_domhsh_getentry(const char *domain)
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{
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return netlbl_domhsh_search_def(domain);
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}
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/**
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* netlbl_domhsh_walk - Iterate through the domain mapping hash table
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* @skip_bkt: the number of buckets to skip at the start
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* @skip_chain: the number of entries to skip in the first iterated bucket
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* @callback: callback for each entry
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* @cb_arg: argument for the callback function
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*
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* Description:
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* Interate over the domain mapping hash table, skipping the first @skip_bkt
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* buckets and @skip_chain entries. For each entry in the table call
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* @callback, if @callback returns a negative value stop 'walking' through the
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* table and return. Updates the values in @skip_bkt and @skip_chain on
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* return. Returns zero on succcess, negative values on failure.
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*
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*/
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int netlbl_domhsh_walk(u32 *skip_bkt,
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u32 *skip_chain,
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int (*callback) (struct netlbl_dom_map *entry, void *arg),
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void *cb_arg)
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{
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int ret_val = -ENOENT;
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u32 iter_bkt;
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struct netlbl_dom_map *iter_entry;
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u32 chain_cnt = 0;
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rcu_read_lock();
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for (iter_bkt = *skip_bkt;
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iter_bkt < rcu_dereference(netlbl_domhsh)->size;
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iter_bkt++, chain_cnt = 0) {
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list_for_each_entry_rcu(iter_entry,
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&rcu_dereference(netlbl_domhsh)->tbl[iter_bkt],
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list)
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if (iter_entry->valid) {
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if (chain_cnt++ < *skip_chain)
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continue;
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ret_val = callback(iter_entry, cb_arg);
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if (ret_val < 0) {
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chain_cnt--;
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goto walk_return;
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}
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}
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}
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walk_return:
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rcu_read_unlock();
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*skip_bkt = iter_bkt;
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*skip_chain = chain_cnt;
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return ret_val;
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}
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