/* * Network node table * * SELinux must keep a mapping of network nodes to labels/SIDs. This * mapping is maintained as part of the normal policy but a fast cache is * needed to reduce the lookup overhead since most of these queries happen on * a per-packet basis. * * Author: Paul Moore <paul.moore@hp.com> * * This code is heavily based on the "netif" concept originally developed by * James Morris <jmorris@redhat.com> * (see security/selinux/netif.c for more information) * */ /* * (c) Copyright Hewlett-Packard Development Company, L.P., 2007 * * This program is free software: you can redistribute it and/or modify * it under the terms of version 2 of the GNU General Public License as * published by the Free Software Foundation. * * 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. * */ #include <linux/types.h> #include <linux/rcupdate.h> #include <linux/list.h> #include <linux/spinlock.h> #include <linux/in.h> #include <linux/in6.h> #include <linux/ip.h> #include <linux/ipv6.h> #include <net/ip.h> #include <net/ipv6.h> #include <asm/bug.h> #include "netnode.h" #include "objsec.h" #define SEL_NETNODE_HASH_SIZE 256 #define SEL_NETNODE_HASH_BKT_LIMIT 16 struct sel_netnode_bkt { unsigned int size; struct list_head list; }; struct sel_netnode { struct netnode_security_struct nsec; struct list_head list; struct rcu_head rcu; }; /* NOTE: we are using a combined hash table for both IPv4 and IPv6, the reason * for this is that I suspect most users will not make heavy use of both * address families at the same time so one table will usually end up wasted, * if this becomes a problem we can always add a hash table for each address * family later */ static LIST_HEAD(sel_netnode_list); static DEFINE_SPINLOCK(sel_netnode_lock); static struct sel_netnode_bkt sel_netnode_hash[SEL_NETNODE_HASH_SIZE]; /** * sel_netnode_free - Frees a node entry * @p: the entry's RCU field * * Description: * This function is designed to be used as a callback to the call_rcu() * function so that memory allocated to a hash table node entry can be * released safely. * */ static void sel_netnode_free(struct rcu_head *p) { struct sel_netnode *node = container_of(p, struct sel_netnode, rcu); kfree(node); } /** * sel_netnode_hashfn_ipv4 - IPv4 hashing function for the node table * @addr: IPv4 address * * Description: * This is the IPv4 hashing function for the node interface table, it returns * the bucket number for the given IP address. * */ static unsigned int sel_netnode_hashfn_ipv4(__be32 addr) { /* at some point we should determine if the mismatch in byte order * affects the hash function dramatically */ return (addr & (SEL_NETNODE_HASH_SIZE - 1)); } /** * sel_netnode_hashfn_ipv6 - IPv6 hashing function for the node table * @addr: IPv6 address * * Description: * This is the IPv6 hashing function for the node interface table, it returns * the bucket number for the given IP address. * */ static unsigned int sel_netnode_hashfn_ipv6(const struct in6_addr *addr) { /* just hash the least significant 32 bits to keep things fast (they * are the most likely to be different anyway), we can revisit this * later if needed */ return (addr->s6_addr32[3] & (SEL_NETNODE_HASH_SIZE - 1)); } /** * sel_netnode_find - Search for a node record * @addr: IP address * @family: address family * * Description: * Search the network node table and return the record matching @addr. If an * entry can not be found in the table return NULL. * */ static struct sel_netnode *sel_netnode_find(const void *addr, u16 family) { unsigned int idx; struct sel_netnode *node; switch (family) { case PF_INET: idx = sel_netnode_hashfn_ipv4(*(__be32 *)addr); break; case PF_INET6: idx = sel_netnode_hashfn_ipv6(addr); break; default: BUG(); } list_for_each_entry_rcu(node, &sel_netnode_hash[idx].list, list) if (node->nsec.family == family) switch (family) { case PF_INET: if (node->nsec.addr.ipv4 == *(__be32 *)addr) return node; break; case PF_INET6: if (ipv6_addr_equal(&node->nsec.addr.ipv6, addr)) return node; break; } return NULL; } /** * sel_netnode_insert - Insert a new node into the table * @node: the new node record * * Description: * Add a new node record to the network address hash table. * */ static void sel_netnode_insert(struct sel_netnode *node) { unsigned int idx; switch (node->nsec.family) { case PF_INET: idx = sel_netnode_hashfn_ipv4(node->nsec.addr.ipv4); break; case PF_INET6: idx = sel_netnode_hashfn_ipv6(&node->nsec.addr.ipv6); break; default: BUG(); } INIT_RCU_HEAD(&node->rcu); /* 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 */ list_add_rcu(&node->list, &sel_netnode_hash[idx].list); if (sel_netnode_hash[idx].size == SEL_NETNODE_HASH_BKT_LIMIT) { struct sel_netnode *tail; tail = list_entry( rcu_dereference(sel_netnode_hash[idx].list.prev), struct sel_netnode, list); list_del_rcu(&tail->list); call_rcu(&tail->rcu, sel_netnode_free); } else sel_netnode_hash[idx].size++; } /** * sel_netnode_sid_slow - Lookup the SID of a network address using the policy * @addr: the IP address * @family: the address family * @sid: node SID * * Description: * This function determines the SID of a network address by quering the * security policy. The result is added to the network address table to * speedup future queries. Returns zero on success, negative values on * failure. * */ static int sel_netnode_sid_slow(void *addr, u16 family, u32 *sid) { int ret = -ENOMEM; struct sel_netnode *node; struct sel_netnode *new = NULL; spin_lock_bh(&sel_netnode_lock); node = sel_netnode_find(addr, family); if (node != NULL) { *sid = node->nsec.sid; spin_unlock_bh(&sel_netnode_lock); return 0; } new = kzalloc(sizeof(*new), GFP_ATOMIC); if (new == NULL) goto out; switch (family) { case PF_INET: ret = security_node_sid(PF_INET, addr, sizeof(struct in_addr), sid); new->nsec.addr.ipv4 = *(__be32 *)addr; break; case PF_INET6: ret = security_node_sid(PF_INET6, addr, sizeof(struct in6_addr), sid); ipv6_addr_copy(&new->nsec.addr.ipv6, addr); break; default: BUG(); } if (ret != 0) goto out; new->nsec.family = family; new->nsec.sid = *sid; sel_netnode_insert(new); out: spin_unlock_bh(&sel_netnode_lock); if (unlikely(ret)) { printk(KERN_WARNING "SELinux: failure in sel_netnode_sid_slow()," " unable to determine network node label\n"); kfree(new); } return ret; } /** * sel_netnode_sid - Lookup the SID of a network address * @addr: the IP address * @family: the address family * @sid: node SID * * Description: * This function determines the SID of a network address using the fastest * method possible. First the address 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_netnode_sid(void *addr, u16 family, u32 *sid) { struct sel_netnode *node; rcu_read_lock(); node = sel_netnode_find(addr, family); if (node != NULL) { *sid = node->nsec.sid; rcu_read_unlock(); return 0; } rcu_read_unlock(); return sel_netnode_sid_slow(addr, family, sid); } /** * sel_netnode_flush - Flush the entire network address table * * Description: * Remove all entries from the network address table. * */ static void sel_netnode_flush(void) { unsigned int idx; struct sel_netnode *node, *node_tmp; spin_lock_bh(&sel_netnode_lock); for (idx = 0; idx < SEL_NETNODE_HASH_SIZE; idx++) { list_for_each_entry_safe(node, node_tmp, &sel_netnode_hash[idx].list, list) { list_del_rcu(&node->list); call_rcu(&node->rcu, sel_netnode_free); } sel_netnode_hash[idx].size = 0; } spin_unlock_bh(&sel_netnode_lock); } static int sel_netnode_avc_callback(u32 event, u32 ssid, u32 tsid, u16 class, u32 perms, u32 *retained) { if (event == AVC_CALLBACK_RESET) { sel_netnode_flush(); synchronize_net(); } return 0; } static __init int sel_netnode_init(void) { int iter; int ret; if (!selinux_enabled) return 0; for (iter = 0; iter < SEL_NETNODE_HASH_SIZE; iter++) { INIT_LIST_HEAD(&sel_netnode_hash[iter].list); sel_netnode_hash[iter].size = 0; } ret = avc_add_callback(sel_netnode_avc_callback, AVC_CALLBACK_RESET, SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0); if (ret != 0) panic("avc_add_callback() failed, error %d\n", ret); return ret; } __initcall(sel_netnode_init);