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