1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Management Component Transport Protocol (MCTP) - device implementation.
4 *
5 * Copyright (c) 2021 Code Construct
6 * Copyright (c) 2021 Google
7 */
8
9 #include <linux/if_arp.h>
10 #include <linux/if_link.h>
11 #include <linux/mctp.h>
12 #include <linux/netdevice.h>
13 #include <linux/rcupdate.h>
14 #include <linux/rtnetlink.h>
15
16 #include <net/addrconf.h>
17 #include <net/netlink.h>
18 #include <net/mctp.h>
19 #include <net/mctpdevice.h>
20 #include <net/sock.h>
21
22 struct mctp_dump_cb {
23 int h;
24 int idx;
25 size_t a_idx;
26 };
27
28 /* unlocked: caller must hold rcu_read_lock.
29 * Returned mctp_dev has its refcount incremented, or NULL if unset.
30 */
31 struct mctp_dev *__mctp_dev_get(const struct net_device *dev)
32 {
33 struct mctp_dev *mdev = rcu_dereference(dev->mctp_ptr);
34
35 /* RCU guarantees that any mdev is still live.
36 * Zero refcount implies a pending free, return NULL.
37 */
38 if (mdev)
39 if (!refcount_inc_not_zero(&mdev->refs))
40 return NULL;
41 return mdev;
42 }
43
44 /* Returned mctp_dev does not have refcount incremented. The returned pointer
45 * remains live while rtnl_lock is held, as that prevents mctp_unregister()
46 */
47 struct mctp_dev *mctp_dev_get_rtnl(const struct net_device *dev)
48 {
49 return rtnl_dereference(dev->mctp_ptr);
50 }
51
52 static int mctp_addrinfo_size(void)
53 {
54 return NLMSG_ALIGN(sizeof(struct ifaddrmsg))
55 + nla_total_size(1) // IFA_LOCAL
56 + nla_total_size(1) // IFA_ADDRESS
57 ;
58 }
59
60 /* flag should be NLM_F_MULTI for dump calls */
61 static int mctp_fill_addrinfo(struct sk_buff *skb,
62 struct mctp_dev *mdev, mctp_eid_t eid,
63 int msg_type, u32 portid, u32 seq, int flag)
64 {
65 struct ifaddrmsg *hdr;
66 struct nlmsghdr *nlh;
67
68 nlh = nlmsg_put(skb, portid, seq,
69 msg_type, sizeof(*hdr), flag);
70 if (!nlh)
71 return -EMSGSIZE;
72
73 hdr = nlmsg_data(nlh);
74 hdr->ifa_family = AF_MCTP;
75 hdr->ifa_prefixlen = 0;
76 hdr->ifa_flags = 0;
77 hdr->ifa_scope = 0;
78 hdr->ifa_index = mdev->dev->ifindex;
79
80 if (nla_put_u8(skb, IFA_LOCAL, eid))
81 goto cancel;
82
83 if (nla_put_u8(skb, IFA_ADDRESS, eid))
84 goto cancel;
85
86 nlmsg_end(skb, nlh);
87
88 return 0;
89
90 cancel:
91 nlmsg_cancel(skb, nlh);
92 return -EMSGSIZE;
93 }
94
95 static int mctp_dump_dev_addrinfo(struct mctp_dev *mdev, struct sk_buff *skb,
96 struct netlink_callback *cb)
97 {
98 struct mctp_dump_cb *mcb = (void *)cb->ctx;
99 u32 portid, seq;
100 int rc = 0;
101
102 portid = NETLINK_CB(cb->skb).portid;
103 seq = cb->nlh->nlmsg_seq;
104 for (; mcb->a_idx < mdev->num_addrs; mcb->a_idx++) {
105 rc = mctp_fill_addrinfo(skb, mdev, mdev->addrs[mcb->a_idx],
106 RTM_NEWADDR, portid, seq, NLM_F_MULTI);
107 if (rc < 0)
108 break;
109 }
110
111 return rc;
112 }
113
114 static int mctp_dump_addrinfo(struct sk_buff *skb, struct netlink_callback *cb)
115 {
116 struct mctp_dump_cb *mcb = (void *)cb->ctx;
117 struct net *net = sock_net(skb->sk);
118 struct hlist_head *head;
119 struct net_device *dev;
120 struct ifaddrmsg *hdr;
121 struct mctp_dev *mdev;
122 int ifindex;
123 int idx = 0, rc;
124
125 hdr = nlmsg_data(cb->nlh);
126 // filter by ifindex if requested
127 ifindex = hdr->ifa_index;
128
129 rcu_read_lock();
130 for (; mcb->h < NETDEV_HASHENTRIES; mcb->h++, mcb->idx = 0) {
131 idx = 0;
132 head = &net->dev_index_head[mcb->h];
133 hlist_for_each_entry_rcu(dev, head, index_hlist) {
134 if (idx >= mcb->idx &&
135 (ifindex == 0 || ifindex == dev->ifindex)) {
136 mdev = __mctp_dev_get(dev);
137 if (mdev) {
138 rc = mctp_dump_dev_addrinfo(mdev,
139 skb, cb);
140 mctp_dev_put(mdev);
141 // Error indicates full buffer, this
142 // callback will get retried.
143 if (rc < 0)
144 goto out;
145 }
146 }
147 idx++;
148 // reset for next iteration
149 mcb->a_idx = 0;
150 }
151 }
152 out:
153 rcu_read_unlock();
154 mcb->idx = idx;
155
156 return skb->len;
157 }
158
159 static void mctp_addr_notify(struct mctp_dev *mdev, mctp_eid_t eid, int msg_type,
160 struct sk_buff *req_skb, struct nlmsghdr *req_nlh)
161 {
162 u32 portid = NETLINK_CB(req_skb).portid;
163 struct net *net = dev_net(mdev->dev);
164 struct sk_buff *skb;
165 int rc = -ENOBUFS;
166
167 skb = nlmsg_new(mctp_addrinfo_size(), GFP_KERNEL);
168 if (!skb)
169 goto out;
170
171 rc = mctp_fill_addrinfo(skb, mdev, eid, msg_type,
172 portid, req_nlh->nlmsg_seq, 0);
173 if (rc < 0) {
174 WARN_ON_ONCE(rc == -EMSGSIZE);
175 goto out;
176 }
177
178 rtnl_notify(skb, net, portid, RTNLGRP_MCTP_IFADDR, req_nlh, GFP_KERNEL);
179 return;
180 out:
181 kfree_skb(skb);
182 rtnl_set_sk_err(net, RTNLGRP_MCTP_IFADDR, rc);
183 }
184
185 static const struct nla_policy ifa_mctp_policy[IFA_MAX + 1] = {
186 [IFA_ADDRESS] = { .type = NLA_U8 },
187 [IFA_LOCAL] = { .type = NLA_U8 },
188 };
189
190 static int mctp_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh,
191 struct netlink_ext_ack *extack)
192 {
193 struct net *net = sock_net(skb->sk);
194 struct nlattr *tb[IFA_MAX + 1];
195 struct net_device *dev;
196 struct mctp_addr *addr;
197 struct mctp_dev *mdev;
198 struct ifaddrmsg *ifm;
199 unsigned long flags;
200 u8 *tmp_addrs;
201 int rc;
202
203 rc = nlmsg_parse(nlh, sizeof(*ifm), tb, IFA_MAX, ifa_mctp_policy,
204 extack);
205 if (rc < 0)
206 return rc;
207
208 ifm = nlmsg_data(nlh);
209
210 if (tb[IFA_LOCAL])
211 addr = nla_data(tb[IFA_LOCAL]);
212 else if (tb[IFA_ADDRESS])
213 addr = nla_data(tb[IFA_ADDRESS]);
214 else
215 return -EINVAL;
216
217 /* find device */
218 dev = __dev_get_by_index(net, ifm->ifa_index);
219 if (!dev)
220 return -ENODEV;
221
222 mdev = mctp_dev_get_rtnl(dev);
223 if (!mdev)
224 return -ENODEV;
225
226 if (!mctp_address_unicast(addr->s_addr))
227 return -EINVAL;
228
229 /* Prevent duplicates. Under RTNL so don't need to lock for reading */
230 if (memchr(mdev->addrs, addr->s_addr, mdev->num_addrs))
231 return -EEXIST;
232
233 tmp_addrs = kmalloc(mdev->num_addrs + 1, GFP_KERNEL);
234 if (!tmp_addrs)
235 return -ENOMEM;
236 memcpy(tmp_addrs, mdev->addrs, mdev->num_addrs);
237 tmp_addrs[mdev->num_addrs] = addr->s_addr;
238
239 /* Lock to write */
240 spin_lock_irqsave(&mdev->addrs_lock, flags);
241 mdev->num_addrs++;
242 swap(mdev->addrs, tmp_addrs);
243 spin_unlock_irqrestore(&mdev->addrs_lock, flags);
244
245 kfree(tmp_addrs);
246
247 mctp_addr_notify(mdev, addr->s_addr, RTM_NEWADDR, skb, nlh);
248 mctp_route_add_local(mdev, addr->s_addr);
249
250 return 0;
251 }
252
253 static int mctp_rtm_deladdr(struct sk_buff *skb, struct nlmsghdr *nlh,
254 struct netlink_ext_ack *extack)
255 {
256 struct net *net = sock_net(skb->sk);
257 struct nlattr *tb[IFA_MAX + 1];
258 struct net_device *dev;
259 struct mctp_addr *addr;
260 struct mctp_dev *mdev;
261 struct ifaddrmsg *ifm;
262 unsigned long flags;
263 u8 *pos;
264 int rc;
265
266 rc = nlmsg_parse(nlh, sizeof(*ifm), tb, IFA_MAX, ifa_mctp_policy,
267 extack);
268 if (rc < 0)
269 return rc;
270
271 ifm = nlmsg_data(nlh);
272
273 if (tb[IFA_LOCAL])
274 addr = nla_data(tb[IFA_LOCAL]);
275 else if (tb[IFA_ADDRESS])
276 addr = nla_data(tb[IFA_ADDRESS]);
277 else
278 return -EINVAL;
279
280 /* find device */
281 dev = __dev_get_by_index(net, ifm->ifa_index);
282 if (!dev)
283 return -ENODEV;
284
285 mdev = mctp_dev_get_rtnl(dev);
286 if (!mdev)
287 return -ENODEV;
288
289 pos = memchr(mdev->addrs, addr->s_addr, mdev->num_addrs);
290 if (!pos)
291 return -ENOENT;
292
293 rc = mctp_route_remove_local(mdev, addr->s_addr);
294 // we can ignore -ENOENT in the case a route was already removed
295 if (rc < 0 && rc != -ENOENT)
296 return rc;
297
298 spin_lock_irqsave(&mdev->addrs_lock, flags);
299 memmove(pos, pos + 1, mdev->num_addrs - 1 - (pos - mdev->addrs));
300 mdev->num_addrs--;
301 spin_unlock_irqrestore(&mdev->addrs_lock, flags);
302
303 mctp_addr_notify(mdev, addr->s_addr, RTM_DELADDR, skb, nlh);
304
305 return 0;
306 }
307
308 void mctp_dev_hold(struct mctp_dev *mdev)
309 {
310 refcount_inc(&mdev->refs);
311 }
312
313 void mctp_dev_put(struct mctp_dev *mdev)
314 {
315 if (mdev && refcount_dec_and_test(&mdev->refs)) {
316 kfree(mdev->addrs);
317 dev_put(mdev->dev);
318 kfree_rcu(mdev, rcu);
319 }
320 }
321
322 void mctp_dev_release_key(struct mctp_dev *dev, struct mctp_sk_key *key)
323 __must_hold(&key->lock)
324 {
325 if (!dev)
326 return;
327 if (dev->ops && dev->ops->release_flow)
328 dev->ops->release_flow(dev, key);
329 key->dev = NULL;
330 mctp_dev_put(dev);
331 }
332
333 void mctp_dev_set_key(struct mctp_dev *dev, struct mctp_sk_key *key)
334 __must_hold(&key->lock)
335 {
336 mctp_dev_hold(dev);
337 key->dev = dev;
338 }
339
340 static struct mctp_dev *mctp_add_dev(struct net_device *dev)
341 {
342 struct mctp_dev *mdev;
343
344 ASSERT_RTNL();
345
346 mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
347 if (!mdev)
348 return ERR_PTR(-ENOMEM);
349
350 spin_lock_init(&mdev->addrs_lock);
351
352 mdev->net = mctp_default_net(dev_net(dev));
353
354 /* associate to net_device */
355 refcount_set(&mdev->refs, 1);
356 rcu_assign_pointer(dev->mctp_ptr, mdev);
357
358 dev_hold(dev);
359 mdev->dev = dev;
360
361 return mdev;
362 }
363
364 static int mctp_fill_link_af(struct sk_buff *skb,
365 const struct net_device *dev, u32 ext_filter_mask)
366 {
367 struct mctp_dev *mdev;
368
369 mdev = mctp_dev_get_rtnl(dev);
370 if (!mdev)
371 return -ENODATA;
372 if (nla_put_u32(skb, IFLA_MCTP_NET, mdev->net))
373 return -EMSGSIZE;
374 return 0;
375 }
376
377 static size_t mctp_get_link_af_size(const struct net_device *dev,
378 u32 ext_filter_mask)
379 {
380 struct mctp_dev *mdev;
381 unsigned int ret;
382
383 /* caller holds RCU */
384 mdev = __mctp_dev_get(dev);
385 if (!mdev)
386 return 0;
387 ret = nla_total_size(4); /* IFLA_MCTP_NET */
388 mctp_dev_put(mdev);
389 return ret;
390 }
391
392 static const struct nla_policy ifla_af_mctp_policy[IFLA_MCTP_MAX + 1] = {
393 [IFLA_MCTP_NET] = { .type = NLA_U32 },
394 };
395
396 static int mctp_set_link_af(struct net_device *dev, const struct nlattr *attr,
397 struct netlink_ext_ack *extack)
398 {
399 struct nlattr *tb[IFLA_MCTP_MAX + 1];
400 struct mctp_dev *mdev;
401 int rc;
402
403 rc = nla_parse_nested(tb, IFLA_MCTP_MAX, attr, ifla_af_mctp_policy,
404 NULL);
405 if (rc)
406 return rc;
407
408 mdev = mctp_dev_get_rtnl(dev);
409 if (!mdev)
410 return 0;
411
412 if (tb[IFLA_MCTP_NET])
413 WRITE_ONCE(mdev->net, nla_get_u32(tb[IFLA_MCTP_NET]));
414
415 return 0;
416 }
417
418 /* Matches netdev types that should have MCTP handling */
419 static bool mctp_known(struct net_device *dev)
420 {
421 /* only register specific types (inc. NONE for TUN devices) */
422 return dev->type == ARPHRD_MCTP ||
423 dev->type == ARPHRD_LOOPBACK ||
424 dev->type == ARPHRD_NONE;
425 }
426
427 static void mctp_unregister(struct net_device *dev)
428 {
429 struct mctp_dev *mdev;
430
431 mdev = mctp_dev_get_rtnl(dev);
432 if (!mdev)
433 return;
434
435 RCU_INIT_POINTER(mdev->dev->mctp_ptr, NULL);
436
437 mctp_route_remove_dev(mdev);
438 mctp_neigh_remove_dev(mdev);
439
440 mctp_dev_put(mdev);
441 }
442
443 static int mctp_register(struct net_device *dev)
444 {
445 struct mctp_dev *mdev;
446
447 /* Already registered? */
448 if (rtnl_dereference(dev->mctp_ptr))
449 return 0;
450
451 /* only register specific types */
452 if (!mctp_known(dev))
453 return 0;
454
455 mdev = mctp_add_dev(dev);
456 if (IS_ERR(mdev))
457 return PTR_ERR(mdev);
458
459 return 0;
460 }
461
462 static int mctp_dev_notify(struct notifier_block *this, unsigned long event,
463 void *ptr)
464 {
465 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
466 int rc;
467
468 switch (event) {
469 case NETDEV_REGISTER:
470 rc = mctp_register(dev);
471 if (rc)
472 return notifier_from_errno(rc);
473 break;
474 case NETDEV_UNREGISTER:
475 mctp_unregister(dev);
476 break;
477 }
478
479 return NOTIFY_OK;
480 }
481
482 static int mctp_register_netdevice(struct net_device *dev,
483 const struct mctp_netdev_ops *ops)
484 {
485 struct mctp_dev *mdev;
486
487 mdev = mctp_add_dev(dev);
488 if (IS_ERR(mdev))
489 return PTR_ERR(mdev);
490
491 mdev->ops = ops;
492
493 return register_netdevice(dev);
494 }
495
496 int mctp_register_netdev(struct net_device *dev,
497 const struct mctp_netdev_ops *ops)
498 {
499 int rc;
500
501 rtnl_lock();
502 rc = mctp_register_netdevice(dev, ops);
503 rtnl_unlock();
504
505 return rc;
506 }
507 EXPORT_SYMBOL_GPL(mctp_register_netdev);
508
509 void mctp_unregister_netdev(struct net_device *dev)
510 {
511 unregister_netdev(dev);
512 }
513 EXPORT_SYMBOL_GPL(mctp_unregister_netdev);
514
515 static struct rtnl_af_ops mctp_af_ops = {
516 .family = AF_MCTP,
517 .fill_link_af = mctp_fill_link_af,
518 .get_link_af_size = mctp_get_link_af_size,
519 .set_link_af = mctp_set_link_af,
520 };
521
522 static struct notifier_block mctp_dev_nb = {
523 .notifier_call = mctp_dev_notify,
524 .priority = ADDRCONF_NOTIFY_PRIORITY,
525 };
526
527 static const struct rtnl_msg_handler mctp_device_rtnl_msg_handlers[] = {
528 {THIS_MODULE, PF_MCTP, RTM_NEWADDR, mctp_rtm_newaddr, NULL, 0},
529 {THIS_MODULE, PF_MCTP, RTM_DELADDR, mctp_rtm_deladdr, NULL, 0},
530 {THIS_MODULE, PF_MCTP, RTM_GETADDR, NULL, mctp_dump_addrinfo, 0},
531 };
532
533 int __init mctp_device_init(void)
534 {
535 int err;
536
537 register_netdevice_notifier(&mctp_dev_nb);
538 rtnl_af_register(&mctp_af_ops);
539
540 err = rtnl_register_many(mctp_device_rtnl_msg_handlers);
541 if (err) {
542 rtnl_af_unregister(&mctp_af_ops);
543 unregister_netdevice_notifier(&mctp_dev_nb);
544 }
545
546 return err;
547 }
548
549 void __exit mctp_device_exit(void)
550 {
551 rtnl_unregister_many(mctp_device_rtnl_msg_handlers);
552 rtnl_af_unregister(&mctp_af_ops);
553 unregister_netdevice_notifier(&mctp_dev_nb);
554 }
555
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