1 /*
2  * Copyright (c) 2017 Mellanox Technologies Inc.  All rights reserved.
3  * Copyright (c) 2010 Voltaire Inc.  All rights reserved.
4  *
5  * This software is available to you under a choice of one of two
6  * licenses.  You may choose to be licensed under the terms of the GNU
7  * General Public License (GPL) Version 2, available from the file
8  * COPYING in the main directory of this source tree, or the
9  * OpenIB.org BSD license below:
10  *
11  *     Redistribution and use in source and binary forms, with or
12  *     without modification, are permitted provided that the following
13  *     conditions are met:
14  *
15  *      - Redistributions of source code must retain the above
16  *        copyright notice, this list of conditions and the following
17  *        disclaimer.
18  *
19  *      - Redistributions in binary form must reproduce the above
20  *        copyright notice, this list of conditions and the following
21  *        disclaimer in the documentation and/or other materials
22  *        provided with the distribution.
23  *
24  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
25  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
26  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
27  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
28  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
29  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
30  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
31  * SOFTWARE.
32  */
33 
34 #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__
35 
36 #include <linux/export.h>
37 #include <net/netlink.h>
38 #include <net/net_namespace.h>
39 #include <net/netns/generic.h>
40 #include <net/sock.h>
41 #include <rdma/rdma_netlink.h>
42 #include <linux/module.h>
43 #include "core_priv.h"
44 
45 static struct {
46 	const struct rdma_nl_cbs *cb_table;
47 	/* Synchronizes between ongoing netlink commands and netlink client
48 	 * unregistration.
49 	 */
50 	struct rw_semaphore sem;
51 } rdma_nl_types[RDMA_NL_NUM_CLIENTS];
52 
53 bool rdma_nl_chk_listeners(unsigned int group)
54 {
55 	struct rdma_dev_net *rnet = rdma_net_to_dev_net(&init_net);
56 
57 	return netlink_has_listeners(rnet->nl_sock, group);
58 }
59 EXPORT_SYMBOL(rdma_nl_chk_listeners);
60 
61 static bool is_nl_msg_valid(unsigned int type, unsigned int op)
62 {
63 	static const unsigned int max_num_ops[RDMA_NL_NUM_CLIENTS] = {
64 		[RDMA_NL_IWCM] = RDMA_NL_IWPM_NUM_OPS,
65 		[RDMA_NL_LS] = RDMA_NL_LS_NUM_OPS,
66 		[RDMA_NL_NLDEV] = RDMA_NLDEV_NUM_OPS,
67 	};
68 
69 	/*
70 	 * This BUILD_BUG_ON is intended to catch addition of new
71 	 * RDMA netlink protocol without updating the array above.
72 	 */
73 	BUILD_BUG_ON(RDMA_NL_NUM_CLIENTS != 6);
74 
75 	if (type >= RDMA_NL_NUM_CLIENTS)
76 		return false;
77 
78 	return op < max_num_ops[type];
79 }
80 
81 static const struct rdma_nl_cbs *
82 get_cb_table(const struct sk_buff *skb, unsigned int type, unsigned int op)
83 {
84 	const struct rdma_nl_cbs *cb_table;
85 
86 	/*
87 	 * Currently only NLDEV client is supporting netlink commands in
88 	 * non init_net net namespace.
89 	 */
90 	if (sock_net(skb->sk) != &init_net && type != RDMA_NL_NLDEV)
91 		return NULL;
92 
93 	cb_table = READ_ONCE(rdma_nl_types[type].cb_table);
94 	if (!cb_table) {
95 		/*
96 		 * Didn't get valid reference of the table, attempt module
97 		 * load once.
98 		 */
99 		up_read(&rdma_nl_types[type].sem);
100 
101 		request_module("rdma-netlink-subsys-%u", type);
102 
103 		down_read(&rdma_nl_types[type].sem);
104 		cb_table = READ_ONCE(rdma_nl_types[type].cb_table);
105 	}
106 	if (!cb_table || (!cb_table[op].dump && !cb_table[op].doit))
107 		return NULL;
108 	return cb_table;
109 }
110 
111 void rdma_nl_register(unsigned int index,
112 		      const struct rdma_nl_cbs cb_table[])
113 {
114 	if (WARN_ON(!is_nl_msg_valid(index, 0)) ||
115 	    WARN_ON(READ_ONCE(rdma_nl_types[index].cb_table)))
116 		return;
117 
118 	/* Pairs with the READ_ONCE in is_nl_valid() */
119 	smp_store_release(&rdma_nl_types[index].cb_table, cb_table);
120 }
121 EXPORT_SYMBOL(rdma_nl_register);
122 
123 void rdma_nl_unregister(unsigned int index)
124 {
125 	down_write(&rdma_nl_types[index].sem);
126 	rdma_nl_types[index].cb_table = NULL;
127 	up_write(&rdma_nl_types[index].sem);
128 }
129 EXPORT_SYMBOL(rdma_nl_unregister);
130 
131 void *ibnl_put_msg(struct sk_buff *skb, struct nlmsghdr **nlh, int seq,
132 		   int len, int client, int op, int flags)
133 {
134 	*nlh = nlmsg_put(skb, 0, seq, RDMA_NL_GET_TYPE(client, op), len, flags);
135 	if (!*nlh)
136 		return NULL;
137 	return nlmsg_data(*nlh);
138 }
139 EXPORT_SYMBOL(ibnl_put_msg);
140 
141 int ibnl_put_attr(struct sk_buff *skb, struct nlmsghdr *nlh,
142 		  int len, void *data, int type)
143 {
144 	if (nla_put(skb, type, len, data)) {
145 		nlmsg_cancel(skb, nlh);
146 		return -EMSGSIZE;
147 	}
148 	return 0;
149 }
150 EXPORT_SYMBOL(ibnl_put_attr);
151 
152 static int rdma_nl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
153 			   struct netlink_ext_ack *extack)
154 {
155 	int type = nlh->nlmsg_type;
156 	unsigned int index = RDMA_NL_GET_CLIENT(type);
157 	unsigned int op = RDMA_NL_GET_OP(type);
158 	const struct rdma_nl_cbs *cb_table;
159 	int err = -EINVAL;
160 
161 	if (!is_nl_msg_valid(index, op))
162 		return -EINVAL;
163 
164 	down_read(&rdma_nl_types[index].sem);
165 	cb_table = get_cb_table(skb, index, op);
166 	if (!cb_table)
167 		goto done;
168 
169 	if ((cb_table[op].flags & RDMA_NL_ADMIN_PERM) &&
170 	    !netlink_capable(skb, CAP_NET_ADMIN)) {
171 		err = -EPERM;
172 		goto done;
173 	}
174 
175 	/*
176 	 * LS responses overload the 0x100 (NLM_F_ROOT) flag.  Don't
177 	 * mistakenly call the .dump() function.
178 	 */
179 	if (index == RDMA_NL_LS) {
180 		if (cb_table[op].doit)
181 			err = cb_table[op].doit(skb, nlh, extack);
182 		goto done;
183 	}
184 	/* FIXME: Convert IWCM to properly handle doit callbacks */
185 	if ((nlh->nlmsg_flags & NLM_F_DUMP) || index == RDMA_NL_IWCM) {
186 		struct netlink_dump_control c = {
187 			.dump = cb_table[op].dump,
188 		};
189 		if (c.dump)
190 			err = netlink_dump_start(skb->sk, skb, nlh, &c);
191 		goto done;
192 	}
193 
194 	if (cb_table[op].doit)
195 		err = cb_table[op].doit(skb, nlh, extack);
196 done:
197 	up_read(&rdma_nl_types[index].sem);
198 	return err;
199 }
200 
201 /*
202  * This function is similar to netlink_rcv_skb with one exception:
203  * It calls to the callback for the netlink messages without NLM_F_REQUEST
204  * flag. These messages are intended for RDMA_NL_LS consumer, so it is allowed
205  * for that consumer only.
206  */
207 static int rdma_nl_rcv_skb(struct sk_buff *skb, int (*cb)(struct sk_buff *,
208 						   struct nlmsghdr *,
209 						   struct netlink_ext_ack *))
210 {
211 	struct netlink_ext_ack extack = {};
212 	struct nlmsghdr *nlh;
213 	int err;
214 
215 	while (skb->len >= nlmsg_total_size(0)) {
216 		int msglen;
217 
218 		nlh = nlmsg_hdr(skb);
219 		err = 0;
220 
221 		if (nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len)
222 			return 0;
223 
224 		/*
225 		 * Generally speaking, the only requests are handled
226 		 * by the kernel, but RDMA_NL_LS is different, because it
227 		 * runs backward netlink scheme. Kernel initiates messages
228 		 * and waits for reply with data to keep pathrecord cache
229 		 * in sync.
230 		 */
231 		if (!(nlh->nlmsg_flags & NLM_F_REQUEST) &&
232 		    (RDMA_NL_GET_CLIENT(nlh->nlmsg_type) != RDMA_NL_LS))
233 			goto ack;
234 
235 		/* Skip control messages */
236 		if (nlh->nlmsg_type < NLMSG_MIN_TYPE)
237 			goto ack;
238 
239 		err = cb(skb, nlh, &extack);
240 		if (err == -EINTR)
241 			goto skip;
242 
243 ack:
244 		if (nlh->nlmsg_flags & NLM_F_ACK || err)
245 			netlink_ack(skb, nlh, err, &extack);
246 
247 skip:
248 		msglen = NLMSG_ALIGN(nlh->nlmsg_len);
249 		if (msglen > skb->len)
250 			msglen = skb->len;
251 		skb_pull(skb, msglen);
252 	}
253 
254 	return 0;
255 }
256 
257 static void rdma_nl_rcv(struct sk_buff *skb)
258 {
259 	rdma_nl_rcv_skb(skb, &rdma_nl_rcv_msg);
260 }
261 
262 int rdma_nl_unicast(struct net *net, struct sk_buff *skb, u32 pid)
263 {
264 	struct rdma_dev_net *rnet = rdma_net_to_dev_net(net);
265 	int err;
266 
267 	err = netlink_unicast(rnet->nl_sock, skb, pid, MSG_DONTWAIT);
268 	return (err < 0) ? err : 0;
269 }
270 EXPORT_SYMBOL(rdma_nl_unicast);
271 
272 int rdma_nl_unicast_wait(struct net *net, struct sk_buff *skb, __u32 pid)
273 {
274 	struct rdma_dev_net *rnet = rdma_net_to_dev_net(net);
275 	int err;
276 
277 	err = netlink_unicast(rnet->nl_sock, skb, pid, 0);
278 	return (err < 0) ? err : 0;
279 }
280 EXPORT_SYMBOL(rdma_nl_unicast_wait);
281 
282 int rdma_nl_multicast(struct net *net, struct sk_buff *skb,
283 		      unsigned int group, gfp_t flags)
284 {
285 	struct rdma_dev_net *rnet = rdma_net_to_dev_net(net);
286 
287 	return nlmsg_multicast(rnet->nl_sock, skb, 0, group, flags);
288 }
289 EXPORT_SYMBOL(rdma_nl_multicast);
290 
291 void rdma_nl_init(void)
292 {
293 	int idx;
294 
295 	for (idx = 0; idx < RDMA_NL_NUM_CLIENTS; idx++)
296 		init_rwsem(&rdma_nl_types[idx].sem);
297 }
298 
299 void rdma_nl_exit(void)
300 {
301 	int idx;
302 
303 	for (idx = 0; idx < RDMA_NL_NUM_CLIENTS; idx++)
304 		WARN(rdma_nl_types[idx].cb_table,
305 		     "Netlink client %d wasn't released prior to unloading %s\n",
306 		     idx, KBUILD_MODNAME);
307 }
308 
309 int rdma_nl_net_init(struct rdma_dev_net *rnet)
310 {
311 	struct net *net = read_pnet(&rnet->net);
312 	struct netlink_kernel_cfg cfg = {
313 		.input	= rdma_nl_rcv,
314 	};
315 	struct sock *nls;
316 
317 	nls = netlink_kernel_create(net, NETLINK_RDMA, &cfg);
318 	if (!nls)
319 		return -ENOMEM;
320 
321 	nls->sk_sndtimeo = 10 * HZ;
322 	rnet->nl_sock = nls;
323 	return 0;
324 }
325 
326 void rdma_nl_net_exit(struct rdma_dev_net *rnet)
327 {
328 	netlink_kernel_release(rnet->nl_sock);
329 }
330 
331 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_RDMA);
332