[DECnet]: Use RCU locking in dn_rules.c
[linux-2.6.git] / net / decnet / dn_rules.c
1
2 /*
3  * DECnet       An implementation of the DECnet protocol suite for the LINUX
4  *              operating system.  DECnet is implemented using the  BSD Socket
5  *              interface as the means of communication with the user level.
6  *
7  *              DECnet Routing Forwarding Information Base (Rules)
8  *
9  * Author:      Steve Whitehouse <SteveW@ACM.org>
10  *              Mostly copied from Alexey Kuznetsov's ipv4/fib_rules.c
11  *
12  *
13  * Changes:
14  *
15  */
16 #include <linux/config.h>
17 #include <linux/string.h>
18 #include <linux/net.h>
19 #include <linux/socket.h>
20 #include <linux/sockios.h>
21 #include <linux/init.h>
22 #include <linux/skbuff.h>
23 #include <linux/netlink.h>
24 #include <linux/rtnetlink.h>
25 #include <linux/proc_fs.h>
26 #include <linux/netdevice.h>
27 #include <linux/timer.h>
28 #include <linux/spinlock.h>
29 #include <linux/in_route.h>
30 #include <linux/list.h>
31 #include <linux/rcupdate.h>
32 #include <asm/atomic.h>
33 #include <asm/uaccess.h>
34 #include <net/neighbour.h>
35 #include <net/dst.h>
36 #include <net/flow.h>
37 #include <net/dn.h>
38 #include <net/dn_fib.h>
39 #include <net/dn_neigh.h>
40 #include <net/dn_dev.h>
41
42 struct dn_fib_rule
43 {
44         struct hlist_node       r_hlist;
45         atomic_t                r_clntref;
46         u32                     r_preference;
47         unsigned char           r_table;
48         unsigned char           r_action;
49         unsigned char           r_dst_len;
50         unsigned char           r_src_len;
51         __le16                  r_src;
52         __le16                  r_srcmask;
53         __le16                  r_dst;
54         __le16                  r_dstmask;
55         __le16                  r_srcmap;
56         u8                      r_flags;
57 #ifdef CONFIG_DECNET_ROUTE_FWMARK
58         u32                     r_fwmark;
59 #endif
60         int                     r_ifindex;
61         char                    r_ifname[IFNAMSIZ];
62         int                     r_dead;
63         struct rcu_head         rcu;
64 };
65
66 static struct dn_fib_rule default_rule = {
67         .r_clntref =            ATOMIC_INIT(2),
68         .r_preference =         0x7fff,
69         .r_table =              RT_TABLE_MAIN,
70         .r_action =             RTN_UNICAST
71 };
72
73 static struct hlist_head dn_fib_rules;
74
75 int dn_fib_rtm_delrule(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
76 {
77         struct rtattr **rta = arg;
78         struct rtmsg *rtm = NLMSG_DATA(nlh);
79         struct dn_fib_rule *r;
80         struct hlist_node *node;
81         int err = -ESRCH;
82
83         hlist_for_each_entry(r, node, &dn_fib_rules, r_hlist) {
84                 if ((!rta[RTA_SRC-1] || memcmp(RTA_DATA(rta[RTA_SRC-1]), &r->r_src, 2) == 0) &&
85                         rtm->rtm_src_len == r->r_src_len &&
86                         rtm->rtm_dst_len == r->r_dst_len &&
87                         (!rta[RTA_DST-1] || memcmp(RTA_DATA(rta[RTA_DST-1]), &r->r_dst, 2) == 0) &&
88 #ifdef CONFIG_DECNET_ROUTE_FWMARK
89                         (!rta[RTA_PROTOINFO-1] || memcmp(RTA_DATA(rta[RTA_PROTOINFO-1]), &r->r_fwmark, 4) == 0) &&
90 #endif
91                         (!rtm->rtm_type || rtm->rtm_type == r->r_action) &&
92                         (!rta[RTA_PRIORITY-1] || memcmp(RTA_DATA(rta[RTA_PRIORITY-1]), &r->r_preference, 4) == 0) &&
93                         (!rta[RTA_IIF-1] || rtattr_strcmp(rta[RTA_IIF-1], r->r_ifname) == 0) &&
94                         (!rtm->rtm_table || (r && rtm->rtm_table == r->r_table))) {
95
96                         err = -EPERM;
97                         if (r == &default_rule)
98                                 break;
99
100                         hlist_del_rcu(&r->r_hlist);
101                         r->r_dead = 1;
102                         dn_fib_rule_put(r);
103                         err = 0;
104                         break;
105                 }
106         }
107
108         return err;
109 }
110
111 static inline void dn_fib_rule_put_rcu(struct rcu_head *head)
112 {
113         struct dn_fib_rule *r = container_of(head, struct dn_fib_rule, rcu);
114         kfree(r);
115 }
116
117 void dn_fib_rule_put(struct dn_fib_rule *r)
118 {
119         if (atomic_dec_and_test(&r->r_clntref)) {
120                 if (r->r_dead)
121                         call_rcu(&r->rcu, dn_fib_rule_put_rcu);
122                 else
123                         printk(KERN_DEBUG "Attempt to free alive dn_fib_rule\n");
124         }
125 }
126
127
128 int dn_fib_rtm_newrule(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
129 {
130         struct rtattr **rta = arg;
131         struct rtmsg *rtm = NLMSG_DATA(nlh);
132         struct dn_fib_rule *r, *new_r, *last = NULL;
133         struct hlist_node *node = NULL;
134         unsigned char table_id;
135
136         if (rtm->rtm_src_len > 16 || rtm->rtm_dst_len > 16)
137                 return -EINVAL;
138
139         if (rta[RTA_IIF-1] && RTA_PAYLOAD(rta[RTA_IIF-1]) > IFNAMSIZ)
140                 return -EINVAL;
141
142         if (rtm->rtm_type == RTN_NAT)
143                 return -EINVAL;
144
145         table_id = rtm->rtm_table;
146         if (table_id == RT_TABLE_UNSPEC) {
147                 struct dn_fib_table *tb;
148                 if (rtm->rtm_type == RTN_UNICAST) {
149                         if ((tb = dn_fib_empty_table()) == NULL)
150                                 return -ENOBUFS;
151                         table_id = tb->n;
152                 }
153         }
154
155         new_r = kmalloc(sizeof(*new_r), GFP_KERNEL);
156         if (!new_r)
157                 return -ENOMEM;
158         memset(new_r, 0, sizeof(*new_r));
159
160         if (rta[RTA_SRC-1])
161                 memcpy(&new_r->r_src, RTA_DATA(rta[RTA_SRC-1]), 2);
162         if (rta[RTA_DST-1])
163                 memcpy(&new_r->r_dst, RTA_DATA(rta[RTA_DST-1]), 2);
164         if (rta[RTA_GATEWAY-1])
165                 memcpy(&new_r->r_srcmap, RTA_DATA(rta[RTA_GATEWAY-1]), 2);
166         new_r->r_src_len = rtm->rtm_src_len;
167         new_r->r_dst_len = rtm->rtm_dst_len;
168         new_r->r_srcmask = dnet_make_mask(rtm->rtm_src_len);
169         new_r->r_dstmask = dnet_make_mask(rtm->rtm_dst_len);
170 #ifdef CONFIG_DECNET_ROUTE_FWMARK
171         if (rta[RTA_PROTOINFO-1])
172                 memcpy(&new_r->r_fwmark, RTA_DATA(rta[RTA_PROTOINFO-1]), 4);
173 #endif
174         new_r->r_action = rtm->rtm_type;
175         new_r->r_flags = rtm->rtm_flags;
176         if (rta[RTA_PRIORITY-1])
177                 memcpy(&new_r->r_preference, RTA_DATA(rta[RTA_PRIORITY-1]), 4);
178         new_r->r_table = table_id;
179         if (rta[RTA_IIF-1]) {
180                 struct net_device *dev;
181                 rtattr_strlcpy(new_r->r_ifname, rta[RTA_IIF-1], IFNAMSIZ);
182                 new_r->r_ifindex = -1;
183                 dev = dev_get_by_name(new_r->r_ifname);
184                 if (dev) {
185                         new_r->r_ifindex = dev->ifindex;
186                         dev_put(dev);
187                 }
188         }
189
190         r = container_of(dn_fib_rules.first, struct dn_fib_rule, r_hlist);
191         if (!new_r->r_preference) {
192                 if (r && r->r_hlist.next != NULL) {
193                         r = container_of(r->r_hlist.next, struct dn_fib_rule, r_hlist);
194                         if (r->r_preference)
195                                 new_r->r_preference = r->r_preference - 1;
196                 }
197         }
198
199         hlist_for_each_entry(r, node, &dn_fib_rules, r_hlist) {
200                 if (r->r_preference > new_r->r_preference)
201                         break;
202                 last = r;
203         }
204         atomic_inc(&new_r->r_clntref);
205
206         if (last)
207                 hlist_add_after_rcu(&last->r_hlist, &new_r->r_hlist);
208         else
209                 hlist_add_before_rcu(&new_r->r_hlist, &r->r_hlist);
210         return 0;
211 }
212
213
214 int dn_fib_lookup(const struct flowi *flp, struct dn_fib_res *res)
215 {
216         struct dn_fib_rule *r, *policy;
217         struct dn_fib_table *tb;
218         __le16 saddr = flp->fld_src;
219         __le16 daddr = flp->fld_dst;
220         struct hlist_node *node;
221         int err;
222
223         rcu_read_lock();
224
225         hlist_for_each_entry_rcu(r, node, &dn_fib_rules, r_hlist) {
226                 if (((saddr^r->r_src) & r->r_srcmask) ||
227                     ((daddr^r->r_dst) & r->r_dstmask) ||
228 #ifdef CONFIG_DECNET_ROUTE_FWMARK
229                     (r->r_fwmark && r->r_fwmark != flp->fld_fwmark) ||
230 #endif
231                     (r->r_ifindex && r->r_ifindex != flp->iif))
232                         continue;
233
234                 switch(r->r_action) {
235                         case RTN_UNICAST:
236                         case RTN_NAT:
237                                 policy = r;
238                                 break;
239                         case RTN_UNREACHABLE:
240                                 rcu_read_unlock();
241                                 return -ENETUNREACH;
242                         default:
243                         case RTN_BLACKHOLE:
244                                 rcu_read_unlock();
245                                 return -EINVAL;
246                         case RTN_PROHIBIT:
247                                 rcu_read_unlock();
248                                 return -EACCES;
249                 }
250
251                 if ((tb = dn_fib_get_table(r->r_table, 0)) == NULL)
252                         continue;
253                 err = tb->lookup(tb, flp, res);
254                 if (err == 0) {
255                         res->r = policy;
256                         if (policy)
257                                 atomic_inc(&policy->r_clntref);
258                         rcu_read_unlock();
259                         return 0;
260                 }
261                 if (err < 0 && err != -EAGAIN) {
262                         rcu_read_unlock();
263                         return err;
264                 }
265         }
266
267         rcu_read_unlock();
268         return -ESRCH;
269 }
270
271 unsigned dnet_addr_type(__le16 addr)
272 {
273         struct flowi fl = { .nl_u = { .dn_u = { .daddr = addr } } };
274         struct dn_fib_res res;
275         unsigned ret = RTN_UNICAST;
276         struct dn_fib_table *tb = dn_fib_tables[RT_TABLE_LOCAL];
277
278         res.r = NULL;
279
280         if (tb) {
281                 if (!tb->lookup(tb, &fl, &res)) {
282                         ret = res.type;
283                         dn_fib_res_put(&res);
284                 }
285         }
286         return ret;
287 }
288
289 __le16 dn_fib_rules_policy(__le16 saddr, struct dn_fib_res *res, unsigned *flags)
290 {
291         struct dn_fib_rule *r = res->r;
292
293         if (r->r_action == RTN_NAT) {
294                 int addrtype = dnet_addr_type(r->r_srcmap);
295
296                 if (addrtype == RTN_NAT) {
297                         saddr = (saddr&~r->r_srcmask)|r->r_srcmap;
298                         *flags |= RTCF_SNAT;
299                 } else if (addrtype == RTN_LOCAL || r->r_srcmap == 0) {
300                         saddr = r->r_srcmap;
301                         *flags |= RTCF_MASQ;
302                 }
303         }
304         return saddr;
305 }
306
307 static void dn_fib_rules_detach(struct net_device *dev)
308 {
309         struct hlist_node *node;
310         struct dn_fib_rule *r;
311
312         hlist_for_each_entry(r, node, &dn_fib_rules, r_hlist) {
313                 if (r->r_ifindex == dev->ifindex)
314                         r->r_ifindex = -1;
315         }
316 }
317
318 static void dn_fib_rules_attach(struct net_device *dev)
319 {
320         struct hlist_node *node;
321         struct dn_fib_rule *r;
322
323         hlist_for_each_entry(r, node, &dn_fib_rules, r_hlist) {
324                 if (r->r_ifindex == -1 && strcmp(dev->name, r->r_ifname) == 0)
325                         r->r_ifindex = dev->ifindex;
326         }
327 }
328
329 static int dn_fib_rules_event(struct notifier_block *this, unsigned long event, void *ptr)
330 {
331         struct net_device *dev = ptr;
332
333         switch(event) {
334                 case NETDEV_UNREGISTER:
335                         dn_fib_rules_detach(dev);
336                         dn_fib_sync_down(0, dev, 1);
337                 case NETDEV_REGISTER:
338                         dn_fib_rules_attach(dev);
339                         dn_fib_sync_up(dev);
340         }
341
342         return NOTIFY_DONE;
343 }
344
345
346 static struct notifier_block dn_fib_rules_notifier = {
347         .notifier_call =        dn_fib_rules_event,
348 };
349
350 static int dn_fib_fill_rule(struct sk_buff *skb, struct dn_fib_rule *r,
351                             struct netlink_callback *cb, unsigned int flags)
352 {
353         struct rtmsg *rtm;
354         struct nlmsghdr *nlh;
355         unsigned char *b = skb->tail;
356
357
358         nlh = NLMSG_NEW_ANSWER(skb, cb, RTM_NEWRULE, sizeof(*rtm), flags);
359         rtm = NLMSG_DATA(nlh);
360         rtm->rtm_family = AF_DECnet;
361         rtm->rtm_dst_len = r->r_dst_len;
362         rtm->rtm_src_len = r->r_src_len;
363         rtm->rtm_tos = 0;
364 #ifdef CONFIG_DECNET_ROUTE_FWMARK
365         if (r->r_fwmark)
366                 RTA_PUT(skb, RTA_PROTOINFO, 4, &r->r_fwmark);
367 #endif
368         rtm->rtm_table = r->r_table;
369         rtm->rtm_protocol = 0;
370         rtm->rtm_scope = 0;
371         rtm->rtm_type = r->r_action;
372         rtm->rtm_flags = r->r_flags;
373
374         if (r->r_dst_len)
375                 RTA_PUT(skb, RTA_DST, 2, &r->r_dst);
376         if (r->r_src_len)
377                 RTA_PUT(skb, RTA_SRC, 2, &r->r_src);
378         if (r->r_ifname[0])
379                 RTA_PUT(skb, RTA_IIF, IFNAMSIZ, &r->r_ifname);
380         if (r->r_preference)
381                 RTA_PUT(skb, RTA_PRIORITY, 4, &r->r_preference);
382         if (r->r_srcmap)
383                 RTA_PUT(skb, RTA_GATEWAY, 2, &r->r_srcmap);
384         nlh->nlmsg_len = skb->tail - b;
385         return skb->len;
386
387 nlmsg_failure:
388 rtattr_failure:
389         skb_trim(skb, b - skb->data);
390         return -1;
391 }
392
393 int dn_fib_dump_rules(struct sk_buff *skb, struct netlink_callback *cb)
394 {
395         int idx = 0;
396         int s_idx = cb->args[0];
397         struct dn_fib_rule *r;
398         struct hlist_node *node;
399
400         rcu_read_lock();
401         hlist_for_each_entry(r, node, &dn_fib_rules, r_hlist) {
402                 if (idx < s_idx)
403                         continue;
404                 if (dn_fib_fill_rule(skb, r, cb, NLM_F_MULTI) < 0)
405                         break;
406                 idx++;
407         }
408         rcu_read_unlock();
409         cb->args[0] = idx;
410
411         return skb->len;
412 }
413
414 void __init dn_fib_rules_init(void)
415 {
416         INIT_HLIST_HEAD(&dn_fib_rules);
417         hlist_add_head(&default_rule.r_hlist, &dn_fib_rules);
418         register_netdevice_notifier(&dn_fib_rules_notifier);
419 }
420
421 void __exit dn_fib_rules_cleanup(void)
422 {
423         unregister_netdevice_notifier(&dn_fib_rules_notifier);
424 }
425
426