/* * Network port table * * SELinux must keep a mapping of network ports to labels/SIDs. This * mapping is maintained as part of the normal policy but a fast cache is * needed to reduce the lookup overhead. * * Author: Paul Moore * * This code is heavily based on the "netif" concept originally developed by * James Morris * (see security/selinux/netif.c for more information) * */ /* * (c) Copyright Hewlett-Packard Development Company, L.P., 2008 * * 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 #include #include #include #include #include #include #include #include #include #include #include "netport.h" #include "objsec.h" #define SEL_NETPORT_HASH_SIZE 256 #define SEL_NETPORT_HASH_BKT_LIMIT 16 struct sel_netport_bkt { int size; struct list_head list; }; struct sel_netport { struct netport_security_struct psec; 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_netport_list); static DEFINE_SPINLOCK(sel_netport_lock); static struct sel_netport_bkt sel_netport_hash[SEL_NETPORT_HASH_SIZE]; /** * sel_netport_hashfn - Hashing function for the port table * @pnum: port number * * Description: * This is the hashing function for the port table, it returns the bucket * number for the given port. * */ static unsigned int sel_netport_hashfn(u16 pnum) { return (pnum & (SEL_NETPORT_HASH_SIZE - 1)); } /** * sel_netport_find - Search for a port record * @protocol: protocol * @port: pnum * * Description: * Search the network port table and return the matching record. If an entry * can not be found in the table return NULL. * */ static struct sel_netport *sel_netport_find(u8 protocol, u16 pnum) { unsigned int idx; struct sel_netport *port; idx = sel_netport_hashfn(pnum); list_for_each_entry_rcu(port, &sel_netport_hash[idx].list, list) if (port->psec.port == pnum && port->psec.protocol == protocol) return port; return NULL; } /** * sel_netport_insert - Insert a new port into the table * @port: the new port record * * Description: * Add a new port record to the network address hash table. * */ static void sel_netport_insert(struct sel_netport *port) { 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_netport_hashfn(port->psec.port); list_add_rcu(&port->list, &sel_netport_hash[idx].list); if (sel_netport_hash[idx].size == SEL_NETPORT_HASH_BKT_LIMIT) { struct sel_netport *tail; tail = list_entry( rcu_dereference_protected( sel_netport_hash[idx].list.prev, lockdep_is_held(&sel_netport_lock)), struct sel_netport, list); list_del_rcu(&tail->list); kfree_rcu(tail, rcu); } else sel_netport_hash[idx].size++; } /** * sel_netport_sid_slow - Lookup the SID of a network address using the policy * @protocol: protocol * @pnum: port * @sid: port SID * * Description: * This function determines the SID of a network port by quering the security * policy. The result is added to the network port table to speedup future * queries. Returns zero on success, negative values on failure. * */ static int sel_netport_sid_slow(u8 protocol, u16 pnum, u32 *sid) { int ret = -ENOMEM; struct sel_netport *port; struct sel_netport *new = NULL; spin_lock_bh(&sel_netport_lock); port = sel_netport_find(protocol, pnum); if (port != NULL) { *sid = port->psec.sid; spin_unlock_bh(&sel_netport_lock); return 0; } new = kzalloc(sizeof(*new), GFP_ATOMIC); if (new == NULL) goto out; ret = security_port_sid(protocol, pnum, sid); if (ret != 0) goto out; new->psec.port = pnum; new->psec.protocol = protocol; new->psec.sid = *sid; sel_netport_insert(new); out: spin_unlock_bh(&sel_netport_lock); if (unlikely(ret)) { printk(KERN_WARNING "SELinux: failure in sel_netport_sid_slow()," " unable to determine network port label\n"); kfree(new); } return ret; } /** * sel_netport_sid - Lookup the SID of a network port * @protocol: protocol * @pnum: port * @sid: port SID * * Description: * This function determines the SID of a network port using the fastest method * possible. First the port 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_netport_sid(u8 protocol, u16 pnum, u32 *sid) { struct sel_netport *port; rcu_read_lock(); port = sel_netport_find(protocol, pnum); if (port != NULL) { *sid = port->psec.sid; rcu_read_unlock(); return 0; } rcu_read_unlock(); return sel_netport_sid_slow(protocol, pnum, sid); } /** * sel_netport_flush - Flush the entire network port table * * Description: * Remove all entries from the network address table. * */ static void sel_netport_flush(void) { unsigned int idx; struct sel_netport *port, *port_tmp; spin_lock_bh(&sel_netport_lock); for (idx = 0; idx < SEL_NETPORT_HASH_SIZE; idx++) { list_for_each_entry_safe(port, port_tmp, &sel_netport_hash[idx].list, list) { list_del_rcu(&port->list); kfree_rcu(port, rcu); } sel_netport_hash[idx].size = 0; } spin_unlock_bh(&sel_netport_lock); } static int sel_netport_avc_callback(u32 event) { if (event == AVC_CALLBACK_RESET) { sel_netport_flush(); synchronize_net(); } return 0; } static __init int sel_netport_init(void) { int iter; int ret; if (!selinux_enabled) return 0; for (iter = 0; iter < SEL_NETPORT_HASH_SIZE; iter++) { INIT_LIST_HEAD(&sel_netport_hash[iter].list); sel_netport_hash[iter].size = 0; } ret = avc_add_callback(sel_netport_avc_callback, AVC_CALLBACK_RESET); if (ret != 0) panic("avc_add_callback() failed, error %d\n", ret); return ret; } __initcall(sel_netport_init);