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238 lines
5.8 KiB
238 lines
5.8 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Network port table |
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* |
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* SELinux must keep a mapping of network ports to labels/SIDs. This |
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* mapping is maintained as part of the normal policy but a fast cache is |
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* needed to reduce the lookup overhead. |
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* |
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* Author: Paul Moore <[email protected]> |
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* |
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* This code is heavily based on the "netif" concept originally developed by |
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* James Morris <[email protected]> |
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* (see security/selinux/netif.c for more information) |
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*/ |
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/* |
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* (c) Copyright Hewlett-Packard Development Company, L.P., 2008 |
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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/slab.h> |
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#include <linux/spinlock.h> |
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#include <linux/in.h> |
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#include <linux/in6.h> |
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#include <linux/ip.h> |
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#include <linux/ipv6.h> |
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#include <net/ip.h> |
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#include <net/ipv6.h> |
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#include "netport.h" |
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#include "objsec.h" |
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#define SEL_NETPORT_HASH_SIZE 256 |
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#define SEL_NETPORT_HASH_BKT_LIMIT 16 |
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struct sel_netport_bkt { |
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int size; |
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struct list_head list; |
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}; |
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struct sel_netport { |
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struct netport_security_struct psec; |
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struct list_head list; |
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struct rcu_head rcu; |
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}; |
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/* NOTE: we are using a combined hash table for both IPv4 and IPv6, the reason |
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* for this is that I suspect most users will not make heavy use of both |
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* address families at the same time so one table will usually end up wasted, |
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* if this becomes a problem we can always add a hash table for each address |
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* family later */ |
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static DEFINE_SPINLOCK(sel_netport_lock); |
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static struct sel_netport_bkt sel_netport_hash[SEL_NETPORT_HASH_SIZE]; |
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/** |
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* sel_netport_hashfn - Hashing function for the port table |
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* @pnum: port number |
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* |
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* Description: |
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* This is the hashing function for the port table, it returns the bucket |
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* number for the given port. |
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* |
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*/ |
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static unsigned int sel_netport_hashfn(u16 pnum) |
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{ |
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return (pnum & (SEL_NETPORT_HASH_SIZE - 1)); |
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} |
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/** |
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* sel_netport_find - Search for a port record |
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* @protocol: protocol |
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* @port: pnum |
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* |
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* Description: |
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* Search the network port table and return the matching record. If an entry |
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* can not be found in the table return NULL. |
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* |
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*/ |
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static struct sel_netport *sel_netport_find(u8 protocol, u16 pnum) |
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{ |
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unsigned int idx; |
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struct sel_netport *port; |
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idx = sel_netport_hashfn(pnum); |
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list_for_each_entry_rcu(port, &sel_netport_hash[idx].list, list) |
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if (port->psec.port == pnum && port->psec.protocol == protocol) |
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return port; |
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return NULL; |
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} |
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/** |
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* sel_netport_insert - Insert a new port into the table |
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* @port: the new port record |
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* |
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* Description: |
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* Add a new port record to the network address hash table. |
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* |
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*/ |
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static void sel_netport_insert(struct sel_netport *port) |
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{ |
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unsigned int idx; |
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/* we need to impose a limit on the growth of the hash table so check |
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* this bucket to make sure it is within the specified bounds */ |
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idx = sel_netport_hashfn(port->psec.port); |
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list_add_rcu(&port->list, &sel_netport_hash[idx].list); |
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if (sel_netport_hash[idx].size == SEL_NETPORT_HASH_BKT_LIMIT) { |
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struct sel_netport *tail; |
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tail = list_entry( |
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rcu_dereference_protected( |
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sel_netport_hash[idx].list.prev, |
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lockdep_is_held(&sel_netport_lock)), |
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struct sel_netport, list); |
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list_del_rcu(&tail->list); |
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kfree_rcu(tail, rcu); |
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} else |
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sel_netport_hash[idx].size++; |
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} |
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/** |
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* sel_netport_sid_slow - Lookup the SID of a network address using the policy |
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* @protocol: protocol |
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* @pnum: port |
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* @sid: port SID |
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* |
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* Description: |
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* This function determines the SID of a network port by querying the security |
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* policy. The result is added to the network port table to speedup future |
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* queries. Returns zero on success, negative values on failure. |
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* |
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*/ |
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static int sel_netport_sid_slow(u8 protocol, u16 pnum, u32 *sid) |
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{ |
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int ret; |
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struct sel_netport *port; |
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struct sel_netport *new; |
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spin_lock_bh(&sel_netport_lock); |
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port = sel_netport_find(protocol, pnum); |
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if (port != NULL) { |
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*sid = port->psec.sid; |
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spin_unlock_bh(&sel_netport_lock); |
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return 0; |
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} |
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ret = security_port_sid(&selinux_state, protocol, pnum, sid); |
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if (ret != 0) |
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goto out; |
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new = kzalloc(sizeof(*new), GFP_ATOMIC); |
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if (new) { |
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new->psec.port = pnum; |
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new->psec.protocol = protocol; |
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new->psec.sid = *sid; |
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sel_netport_insert(new); |
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} |
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out: |
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spin_unlock_bh(&sel_netport_lock); |
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if (unlikely(ret)) |
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pr_warn("SELinux: failure in %s(), unable to determine network port label\n", |
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__func__); |
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return ret; |
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} |
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/** |
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* sel_netport_sid - Lookup the SID of a network port |
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* @protocol: protocol |
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* @pnum: port |
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* @sid: port SID |
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* |
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* Description: |
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* This function determines the SID of a network port using the fastest method |
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* possible. First the port table is queried, but if an entry can't be found |
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* then the policy is queried and the result is added to the table to speedup |
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* future queries. Returns zero on success, negative values on failure. |
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* |
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*/ |
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int sel_netport_sid(u8 protocol, u16 pnum, u32 *sid) |
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{ |
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struct sel_netport *port; |
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rcu_read_lock(); |
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port = sel_netport_find(protocol, pnum); |
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if (port != NULL) { |
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*sid = port->psec.sid; |
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rcu_read_unlock(); |
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return 0; |
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} |
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rcu_read_unlock(); |
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return sel_netport_sid_slow(protocol, pnum, sid); |
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} |
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/** |
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* sel_netport_flush - Flush the entire network port table |
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* |
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* Description: |
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* Remove all entries from the network address table. |
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* |
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*/ |
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void sel_netport_flush(void) |
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{ |
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unsigned int idx; |
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struct sel_netport *port, *port_tmp; |
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spin_lock_bh(&sel_netport_lock); |
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for (idx = 0; idx < SEL_NETPORT_HASH_SIZE; idx++) { |
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list_for_each_entry_safe(port, port_tmp, |
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&sel_netport_hash[idx].list, list) { |
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list_del_rcu(&port->list); |
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kfree_rcu(port, rcu); |
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} |
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sel_netport_hash[idx].size = 0; |
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} |
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spin_unlock_bh(&sel_netport_lock); |
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} |
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static __init int sel_netport_init(void) |
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{ |
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int iter; |
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if (!selinux_enabled_boot) |
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return 0; |
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for (iter = 0; iter < SEL_NETPORT_HASH_SIZE; iter++) { |
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INIT_LIST_HEAD(&sel_netport_hash[iter].list); |
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sel_netport_hash[iter].size = 0; |
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} |
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return 0; |
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} |
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__initcall(sel_netport_init);
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