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TOMOYO Linux Cross Reference
Linux/security/selinux/netport.c

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  1 /*
  2  * Network port table
  3  *
  4  * SELinux must keep a mapping of network ports to labels/SIDs.  This
  5  * mapping is maintained as part of the normal policy but a fast cache is
  6  * needed to reduce the lookup overhead.
  7  *
  8  * Author: Paul Moore <paul@paul-moore.com>
  9  *
 10  * This code is heavily based on the "netif" concept originally developed by
 11  * James Morris <jmorris@redhat.com>
 12  *   (see security/selinux/netif.c for more information)
 13  *
 14  */
 15 
 16 /*
 17  * (c) Copyright Hewlett-Packard Development Company, L.P., 2008
 18  *
 19  * This program is free software: you can redistribute it and/or modify
 20  * it under the terms of version 2 of the GNU General Public License as
 21  * published by the Free Software Foundation.
 22  *
 23  * This program is distributed in the hope that it will be useful,
 24  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 25  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 26  * GNU General Public License for more details.
 27  *
 28  */
 29 
 30 #include <linux/types.h>
 31 #include <linux/rcupdate.h>
 32 #include <linux/list.h>
 33 #include <linux/slab.h>
 34 #include <linux/spinlock.h>
 35 #include <linux/in.h>
 36 #include <linux/in6.h>
 37 #include <linux/ip.h>
 38 #include <linux/ipv6.h>
 39 #include <net/ip.h>
 40 #include <net/ipv6.h>
 41 
 42 #include "netport.h"
 43 #include "objsec.h"
 44 
 45 #define SEL_NETPORT_HASH_SIZE       256
 46 #define SEL_NETPORT_HASH_BKT_LIMIT   16
 47 
 48 struct sel_netport_bkt {
 49         int size;
 50         struct list_head list;
 51 };
 52 
 53 struct sel_netport {
 54         struct netport_security_struct psec;
 55 
 56         struct list_head list;
 57         struct rcu_head rcu;
 58 };
 59 
 60 /* NOTE: we are using a combined hash table for both IPv4 and IPv6, the reason
 61  * for this is that I suspect most users will not make heavy use of both
 62  * address families at the same time so one table will usually end up wasted,
 63  * if this becomes a problem we can always add a hash table for each address
 64  * family later */
 65 
 66 static LIST_HEAD(sel_netport_list);
 67 static DEFINE_SPINLOCK(sel_netport_lock);
 68 static struct sel_netport_bkt sel_netport_hash[SEL_NETPORT_HASH_SIZE];
 69 
 70 /**
 71  * sel_netport_hashfn - Hashing function for the port table
 72  * @pnum: port number
 73  *
 74  * Description:
 75  * This is the hashing function for the port table, it returns the bucket
 76  * number for the given port.
 77  *
 78  */
 79 static unsigned int sel_netport_hashfn(u16 pnum)
 80 {
 81         return (pnum & (SEL_NETPORT_HASH_SIZE - 1));
 82 }
 83 
 84 /**
 85  * sel_netport_find - Search for a port record
 86  * @protocol: protocol
 87  * @port: pnum
 88  *
 89  * Description:
 90  * Search the network port table and return the matching record.  If an entry
 91  * can not be found in the table return NULL.
 92  *
 93  */
 94 static struct sel_netport *sel_netport_find(u8 protocol, u16 pnum)
 95 {
 96         unsigned int idx;
 97         struct sel_netport *port;
 98 
 99         idx = sel_netport_hashfn(pnum);
100         list_for_each_entry_rcu(port, &sel_netport_hash[idx].list, list)
101                 if (port->psec.port == pnum && port->psec.protocol == protocol)
102                         return port;
103 
104         return NULL;
105 }
106 
107 /**
108  * sel_netport_insert - Insert a new port into the table
109  * @port: the new port record
110  *
111  * Description:
112  * Add a new port record to the network address hash table.
113  *
114  */
115 static void sel_netport_insert(struct sel_netport *port)
116 {
117         unsigned int idx;
118 
119         /* we need to impose a limit on the growth of the hash table so check
120          * this bucket to make sure it is within the specified bounds */
121         idx = sel_netport_hashfn(port->psec.port);
122         list_add_rcu(&port->list, &sel_netport_hash[idx].list);
123         if (sel_netport_hash[idx].size == SEL_NETPORT_HASH_BKT_LIMIT) {
124                 struct sel_netport *tail;
125                 tail = list_entry(
126                         rcu_dereference_protected(
127                                 sel_netport_hash[idx].list.prev,
128                                 lockdep_is_held(&sel_netport_lock)),
129                         struct sel_netport, list);
130                 list_del_rcu(&tail->list);
131                 kfree_rcu(tail, rcu);
132         } else
133                 sel_netport_hash[idx].size++;
134 }
135 
136 /**
137  * sel_netport_sid_slow - Lookup the SID of a network address using the policy
138  * @protocol: protocol
139  * @pnum: port
140  * @sid: port SID
141  *
142  * Description:
143  * This function determines the SID of a network port by quering the security
144  * policy.  The result is added to the network port table to speedup future
145  * queries.  Returns zero on success, negative values on failure.
146  *
147  */
148 static int sel_netport_sid_slow(u8 protocol, u16 pnum, u32 *sid)
149 {
150         int ret = -ENOMEM;
151         struct sel_netport *port;
152         struct sel_netport *new = NULL;
153 
154         spin_lock_bh(&sel_netport_lock);
155         port = sel_netport_find(protocol, pnum);
156         if (port != NULL) {
157                 *sid = port->psec.sid;
158                 spin_unlock_bh(&sel_netport_lock);
159                 return 0;
160         }
161         new = kzalloc(sizeof(*new), GFP_ATOMIC);
162         if (new == NULL)
163                 goto out;
164         ret = security_port_sid(protocol, pnum, sid);
165         if (ret != 0)
166                 goto out;
167 
168         new->psec.port = pnum;
169         new->psec.protocol = protocol;
170         new->psec.sid = *sid;
171         sel_netport_insert(new);
172 
173 out:
174         spin_unlock_bh(&sel_netport_lock);
175         if (unlikely(ret)) {
176                 printk(KERN_WARNING
177                        "SELinux: failure in sel_netport_sid_slow(),"
178                        " unable to determine network port label\n");
179                 kfree(new);
180         }
181         return ret;
182 }
183 
184 /**
185  * sel_netport_sid - Lookup the SID of a network port
186  * @protocol: protocol
187  * @pnum: port
188  * @sid: port SID
189  *
190  * Description:
191  * This function determines the SID of a network port using the fastest method
192  * possible.  First the port table is queried, but if an entry can't be found
193  * then the policy is queried and the result is added to the table to speedup
194  * future queries.  Returns zero on success, negative values on failure.
195  *
196  */
197 int sel_netport_sid(u8 protocol, u16 pnum, u32 *sid)
198 {
199         struct sel_netport *port;
200 
201         rcu_read_lock();
202         port = sel_netport_find(protocol, pnum);
203         if (port != NULL) {
204                 *sid = port->psec.sid;
205                 rcu_read_unlock();
206                 return 0;
207         }
208         rcu_read_unlock();
209 
210         return sel_netport_sid_slow(protocol, pnum, sid);
211 }
212 
213 /**
214  * sel_netport_flush - Flush the entire network port table
215  *
216  * Description:
217  * Remove all entries from the network address table.
218  *
219  */
220 void sel_netport_flush(void)
221 {
222         unsigned int idx;
223         struct sel_netport *port, *port_tmp;
224 
225         spin_lock_bh(&sel_netport_lock);
226         for (idx = 0; idx < SEL_NETPORT_HASH_SIZE; idx++) {
227                 list_for_each_entry_safe(port, port_tmp,
228                                          &sel_netport_hash[idx].list, list) {
229                         list_del_rcu(&port->list);
230                         kfree_rcu(port, rcu);
231                 }
232                 sel_netport_hash[idx].size = 0;
233         }
234         spin_unlock_bh(&sel_netport_lock);
235 }
236 
237 static __init int sel_netport_init(void)
238 {
239         int iter;
240 
241         if (!selinux_enabled)
242                 return 0;
243 
244         for (iter = 0; iter < SEL_NETPORT_HASH_SIZE; iter++) {
245                 INIT_LIST_HEAD(&sel_netport_hash[iter].list);
246                 sel_netport_hash[iter].size = 0;
247         }
248 
249         return 0;
250 }
251 
252 __initcall(sel_netport_init);
253 

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