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304 lines
7.5 KiB
304 lines
7.5 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Network node table |
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* |
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* SELinux must keep a mapping of network nodes 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 since most of these queries happen on |
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* a per-packet basis. |
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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., 2007 |
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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 "netnode.h" |
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#include "objsec.h" |
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#define SEL_NETNODE_HASH_SIZE 256 |
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#define SEL_NETNODE_HASH_BKT_LIMIT 16 |
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struct sel_netnode_bkt { |
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unsigned int size; |
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struct list_head list; |
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}; |
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struct sel_netnode { |
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struct netnode_security_struct nsec; |
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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_netnode_lock); |
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static struct sel_netnode_bkt sel_netnode_hash[SEL_NETNODE_HASH_SIZE]; |
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/** |
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* sel_netnode_hashfn_ipv4 - IPv4 hashing function for the node table |
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* @addr: IPv4 address |
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* |
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* Description: |
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* This is the IPv4 hashing function for the node interface table, it returns |
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* the bucket number for the given IP address. |
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* |
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*/ |
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static unsigned int sel_netnode_hashfn_ipv4(__be32 addr) |
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{ |
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/* at some point we should determine if the mismatch in byte order |
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* affects the hash function dramatically */ |
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return (addr & (SEL_NETNODE_HASH_SIZE - 1)); |
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} |
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/** |
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* sel_netnode_hashfn_ipv6 - IPv6 hashing function for the node table |
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* @addr: IPv6 address |
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* |
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* Description: |
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* This is the IPv6 hashing function for the node interface table, it returns |
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* the bucket number for the given IP address. |
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* |
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*/ |
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static unsigned int sel_netnode_hashfn_ipv6(const struct in6_addr *addr) |
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{ |
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/* just hash the least significant 32 bits to keep things fast (they |
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* are the most likely to be different anyway), we can revisit this |
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* later if needed */ |
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return (addr->s6_addr32[3] & (SEL_NETNODE_HASH_SIZE - 1)); |
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} |
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/** |
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* sel_netnode_find - Search for a node record |
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* @addr: IP address |
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* @family: address family |
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* |
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* Description: |
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* Search the network node table and return the record matching @addr. If an |
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* entry can not be found in the table return NULL. |
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* |
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*/ |
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static struct sel_netnode *sel_netnode_find(const void *addr, u16 family) |
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{ |
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unsigned int idx; |
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struct sel_netnode *node; |
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switch (family) { |
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case PF_INET: |
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idx = sel_netnode_hashfn_ipv4(*(__be32 *)addr); |
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break; |
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case PF_INET6: |
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idx = sel_netnode_hashfn_ipv6(addr); |
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break; |
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default: |
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BUG(); |
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return NULL; |
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} |
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list_for_each_entry_rcu(node, &sel_netnode_hash[idx].list, list) |
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if (node->nsec.family == family) |
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switch (family) { |
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case PF_INET: |
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if (node->nsec.addr.ipv4 == *(__be32 *)addr) |
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return node; |
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break; |
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case PF_INET6: |
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if (ipv6_addr_equal(&node->nsec.addr.ipv6, |
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addr)) |
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return node; |
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break; |
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} |
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return NULL; |
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} |
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/** |
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* sel_netnode_insert - Insert a new node into the table |
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* @node: the new node record |
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* |
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* Description: |
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* Add a new node record to the network address hash table. |
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* |
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*/ |
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static void sel_netnode_insert(struct sel_netnode *node) |
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{ |
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unsigned int idx; |
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switch (node->nsec.family) { |
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case PF_INET: |
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idx = sel_netnode_hashfn_ipv4(node->nsec.addr.ipv4); |
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break; |
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case PF_INET6: |
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idx = sel_netnode_hashfn_ipv6(&node->nsec.addr.ipv6); |
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break; |
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default: |
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BUG(); |
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return; |
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} |
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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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list_add_rcu(&node->list, &sel_netnode_hash[idx].list); |
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if (sel_netnode_hash[idx].size == SEL_NETNODE_HASH_BKT_LIMIT) { |
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struct sel_netnode *tail; |
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tail = list_entry( |
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rcu_dereference_protected(sel_netnode_hash[idx].list.prev, |
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lockdep_is_held(&sel_netnode_lock)), |
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struct sel_netnode, 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_netnode_hash[idx].size++; |
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} |
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/** |
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* sel_netnode_sid_slow - Lookup the SID of a network address using the policy |
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* @addr: the IP address |
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* @family: the address family |
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* @sid: node SID |
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* |
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* Description: |
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* This function determines the SID of a network address by querying the |
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* security policy. The result is added to the network address table to |
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* speedup future queries. Returns zero on success, negative values on |
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* failure. |
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* |
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*/ |
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static int sel_netnode_sid_slow(void *addr, u16 family, u32 *sid) |
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{ |
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int ret; |
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struct sel_netnode *node; |
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struct sel_netnode *new; |
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spin_lock_bh(&sel_netnode_lock); |
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node = sel_netnode_find(addr, family); |
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if (node != NULL) { |
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*sid = node->nsec.sid; |
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spin_unlock_bh(&sel_netnode_lock); |
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return 0; |
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} |
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new = kzalloc(sizeof(*new), GFP_ATOMIC); |
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switch (family) { |
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case PF_INET: |
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ret = security_node_sid(&selinux_state, PF_INET, |
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addr, sizeof(struct in_addr), sid); |
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if (new) |
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new->nsec.addr.ipv4 = *(__be32 *)addr; |
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break; |
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case PF_INET6: |
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ret = security_node_sid(&selinux_state, PF_INET6, |
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addr, sizeof(struct in6_addr), sid); |
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if (new) |
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new->nsec.addr.ipv6 = *(struct in6_addr *)addr; |
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break; |
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default: |
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BUG(); |
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ret = -EINVAL; |
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} |
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if (ret == 0 && new) { |
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new->nsec.family = family; |
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new->nsec.sid = *sid; |
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sel_netnode_insert(new); |
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} else |
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kfree(new); |
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spin_unlock_bh(&sel_netnode_lock); |
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if (unlikely(ret)) |
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pr_warn("SELinux: failure in %s(), unable to determine network node 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_netnode_sid - Lookup the SID of a network address |
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* @addr: the IP address |
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* @family: the address family |
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* @sid: node SID |
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* |
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* Description: |
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* This function determines the SID of a network address using the fastest |
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* method possible. First the address table is queried, but if an entry |
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* can't be found then the policy is queried and the result is added to the |
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* table to speedup future queries. Returns zero on success, negative values |
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* on failure. |
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* |
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*/ |
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int sel_netnode_sid(void *addr, u16 family, u32 *sid) |
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{ |
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struct sel_netnode *node; |
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rcu_read_lock(); |
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node = sel_netnode_find(addr, family); |
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if (node != NULL) { |
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*sid = node->nsec.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_netnode_sid_slow(addr, family, sid); |
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} |
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/** |
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* sel_netnode_flush - Flush the entire network address 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_netnode_flush(void) |
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{ |
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unsigned int idx; |
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struct sel_netnode *node, *node_tmp; |
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spin_lock_bh(&sel_netnode_lock); |
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for (idx = 0; idx < SEL_NETNODE_HASH_SIZE; idx++) { |
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list_for_each_entry_safe(node, node_tmp, |
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&sel_netnode_hash[idx].list, list) { |
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list_del_rcu(&node->list); |
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kfree_rcu(node, rcu); |
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} |
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sel_netnode_hash[idx].size = 0; |
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} |
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spin_unlock_bh(&sel_netnode_lock); |
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} |
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static __init int sel_netnode_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_NETNODE_HASH_SIZE; iter++) { |
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INIT_LIST_HEAD(&sel_netnode_hash[iter].list); |
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sel_netnode_hash[iter].size = 0; |
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} |
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return 0; |
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} |
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__initcall(sel_netnode_init);
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