diff options
Diffstat (limited to 'security/selinux/netnode.c')
| -rw-r--r-- | security/selinux/netnode.c | 350 |
1 files changed, 350 insertions, 0 deletions
diff --git a/security/selinux/netnode.c b/security/selinux/netnode.c new file mode 100644 index 000000000000..49c527799240 --- /dev/null +++ b/security/selinux/netnode.c @@ -0,0 +1,350 @@ +/* + * 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 "objsec.h" + +#define SEL_NETNODE_HASH_SIZE 256 +#define SEL_NETNODE_HASH_BKT_LIMIT 16 + +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 list_head 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 u32 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 u32 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) +{ + u32 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) + 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. Returns zero on + * success, negative values on failure. + * + */ +static int sel_netnode_insert(struct sel_netnode *node) +{ + u32 idx; + u32 count = 0; + struct sel_netnode *iter; + + 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(); + } + list_add_rcu(&node->list, &sel_netnode_hash[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 */ + list_for_each_entry(iter, &sel_netnode_hash[idx], list) + if (++count > SEL_NETNODE_HASH_BKT_LIMIT) { + list_del_rcu(&iter->list); + call_rcu(&iter->rcu, sel_netnode_free); + break; + } + + return 0; +} + +/** + * sel_netnode_destroy - Remove a node record from the table + * @node: the existing node record + * + * Description: + * Remove an existing node record from the network address table. + * + */ +static void sel_netnode_destroy(struct sel_netnode *node) +{ + list_del_rcu(&node->list); + call_rcu(&node->rcu, sel_netnode_free); +} + +/** + * 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; + 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; + ret = 0; + goto out; + } + new = kzalloc(sizeof(*new), GFP_ATOMIC); + if (new == NULL) { + ret = -ENOMEM; + goto out; + } + switch (family) { + case PF_INET: + ret = security_node_sid(PF_INET, + addr, sizeof(struct in_addr), + &new->nsec.sid); + new->nsec.addr.ipv4 = *(__be32 *)addr; + break; + case PF_INET6: + ret = security_node_sid(PF_INET6, + addr, sizeof(struct in6_addr), + &new->nsec.sid); + ipv6_addr_copy(&new->nsec.addr.ipv6, addr); + break; + default: + BUG(); + } + if (ret != 0) + goto out; + new->nsec.family = family; + ret = sel_netnode_insert(new); + if (ret != 0) + goto out; + *sid = new->nsec.sid; + +out: + spin_unlock_bh(&sel_netnode_lock); + if (ret != 0) + 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) +{ + u32 idx; + struct sel_netnode *node; + + spin_lock_bh(&sel_netnode_lock); + for (idx = 0; idx < SEL_NETNODE_HASH_SIZE; idx++) + list_for_each_entry(node, &sel_netnode_hash[idx], list) + sel_netnode_destroy(node); + 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]); + + 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); |