// SPDX-License-Identifier: GPL-2.0-only/* * 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@paul-moore.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 */ #include <linux/types.h>#include <linux/rcupdate.h>#include <linux/list.h>#include <linux/slab.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 "initcalls.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 DEFINE_SPINLOCK(sel_netnode_lock);static struct sel_netnode_bkt sel_netnode_hash[SEL_NETNODE_HASH_SIZE]; /** * 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(*(const __be32 *)addr);		break;	case PF_INET6:		idx = sel_netnode_hashfn_ipv6(addr);		break;	default:		BUG();		return NULL;	} 	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 == *(const __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();		return;	} 	/* 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_protected(				list_tail_rcu(&sel_netnode_hash[idx].list),				lockdep_is_held(&sel_netnode_lock)),			struct sel_netnode, list);		list_del_rcu(&tail->list);		kfree_rcu(tail, rcu);	} 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 querying 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(const void *addr, u16 family, u32 *sid){	int ret;	struct sel_netnode *node;	struct sel_netnode *new; 	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;	} 	/* If this memory allocation fails still return 0. The SID	 * is valid, it just won't be added to the cache.	 */	new = kmalloc_obj(*new, GFP_ATOMIC);	switch (family) {	case PF_INET:		ret = security_node_sid(PF_INET,					addr, sizeof(struct in_addr), sid);		if (new)			new->nsec.addr.ipv4 = *(const __be32 *)addr;		break;	case PF_INET6:		ret = security_node_sid(PF_INET6,					addr, sizeof(struct in6_addr), sid);		if (new)			new->nsec.addr.ipv6 = *(const struct in6_addr *)addr;		break;	default:		BUG();		ret = -EINVAL;	}	if (ret == 0 && new) {		new->nsec.family = family;		new->nsec.sid = *sid;		sel_netnode_insert(new);	} else		kfree(new); 	spin_unlock_bh(&sel_netnode_lock);	if (unlikely(ret))		pr_warn("SELinux: failure in %s(), unable to determine network node label\n",			__func__);	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(const void *addr, u16 family, u32 *sid){	struct sel_netnode *node; 	rcu_read_lock();	node = sel_netnode_find(addr, family);	if (likely(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. * */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);				kfree_rcu(node, rcu);		}		sel_netnode_hash[idx].size = 0;	}	spin_unlock_bh(&sel_netnode_lock);} int __init sel_netnode_init(void){	int iter; 	if (!selinux_enabled_boot)		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;	} 	return 0;}