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/sock.h>
40 #include <rdma/rdma_netlink.h>
41 #include <linux/module.h>
42 #include "core_priv.h"
43 
44 static DEFINE_MUTEX(rdma_nl_mutex);
45 static struct sock *nls;
46 static struct {
47 	const struct rdma_nl_cbs   *cb_table;
48 } rdma_nl_types[RDMA_NL_NUM_CLIENTS];
49 
50 bool rdma_nl_chk_listeners(unsigned int group)
51 {
52 	return netlink_has_listeners(nls, group);
53 }
54 EXPORT_SYMBOL(rdma_nl_chk_listeners);
55 
56 static bool is_nl_msg_valid(unsigned int type, unsigned int op)
57 {
58 	static const unsigned int max_num_ops[RDMA_NL_NUM_CLIENTS] = {
59 		[RDMA_NL_RDMA_CM] = RDMA_NL_RDMA_CM_NUM_OPS,
60 		[RDMA_NL_IWCM] = RDMA_NL_IWPM_NUM_OPS,
61 		[RDMA_NL_LS] = RDMA_NL_LS_NUM_OPS,
62 		[RDMA_NL_NLDEV] = RDMA_NLDEV_NUM_OPS,
63 	};
64 
65 	/*
66 	 * This BUILD_BUG_ON is intended to catch addition of new
67 	 * RDMA netlink protocol without updating the array above.
68 	 */
69 	BUILD_BUG_ON(RDMA_NL_NUM_CLIENTS != 6);
70 
71 	if (type >= RDMA_NL_NUM_CLIENTS)
72 		return false;
73 
74 	return (op < max_num_ops[type]) ? true : false;
75 }
76 
77 static bool is_nl_valid(unsigned int type, unsigned int op)
78 {
79 	const struct rdma_nl_cbs *cb_table;
80 
81 	if (!is_nl_msg_valid(type, op))
82 		return false;
83 
84 	if (!rdma_nl_types[type].cb_table) {
85 		mutex_unlock(&rdma_nl_mutex);
86 		request_module("rdma-netlink-subsys-%d", type);
87 		mutex_lock(&rdma_nl_mutex);
88 	}
89 
90 	cb_table = rdma_nl_types[type].cb_table;
91 
92 	if (!cb_table || (!cb_table[op].dump && !cb_table[op].doit))
93 		return false;
94 	return true;
95 }
96 
97 void rdma_nl_register(unsigned int index,
98 		      const struct rdma_nl_cbs cb_table[])
99 {
100 	mutex_lock(&rdma_nl_mutex);
101 	if (!is_nl_msg_valid(index, 0)) {
102 		/*
103 		 * All clients are not interesting in success/failure of
104 		 * this call. They want to see the print to error log and
105 		 * continue their initialization. Print warning for them,
106 		 * because it is programmer's error to be here.
107 		 */
108 		mutex_unlock(&rdma_nl_mutex);
109 		WARN(true,
110 		     "The not-valid %u index was supplied to RDMA netlink\n",
111 		     index);
112 		return;
113 	}
114 
115 	if (rdma_nl_types[index].cb_table) {
116 		mutex_unlock(&rdma_nl_mutex);
117 		WARN(true,
118 		     "The %u index is already registered in RDMA netlink\n",
119 		     index);
120 		return;
121 	}
122 
123 	rdma_nl_types[index].cb_table = cb_table;
124 	mutex_unlock(&rdma_nl_mutex);
125 }
126 EXPORT_SYMBOL(rdma_nl_register);
127 
128 void rdma_nl_unregister(unsigned int index)
129 {
130 	mutex_lock(&rdma_nl_mutex);
131 	rdma_nl_types[index].cb_table = NULL;
132 	mutex_unlock(&rdma_nl_mutex);
133 }
134 EXPORT_SYMBOL(rdma_nl_unregister);
135 
136 void *ibnl_put_msg(struct sk_buff *skb, struct nlmsghdr **nlh, int seq,
137 		   int len, int client, int op, int flags)
138 {
139 	*nlh = nlmsg_put(skb, 0, seq, RDMA_NL_GET_TYPE(client, op), len, flags);
140 	if (!*nlh)
141 		return NULL;
142 	return nlmsg_data(*nlh);
143 }
144 EXPORT_SYMBOL(ibnl_put_msg);
145 
146 int ibnl_put_attr(struct sk_buff *skb, struct nlmsghdr *nlh,
147 		  int len, void *data, int type)
148 {
149 	if (nla_put(skb, type, len, data)) {
150 		nlmsg_cancel(skb, nlh);
151 		return -EMSGSIZE;
152 	}
153 	return 0;
154 }
155 EXPORT_SYMBOL(ibnl_put_attr);
156 
157 static int rdma_nl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
158 			   struct netlink_ext_ack *extack)
159 {
160 	int type = nlh->nlmsg_type;
161 	unsigned int index = RDMA_NL_GET_CLIENT(type);
162 	unsigned int op = RDMA_NL_GET_OP(type);
163 	const struct rdma_nl_cbs *cb_table;
164 
165 	if (!is_nl_valid(index, op))
166 		return -EINVAL;
167 
168 	cb_table = rdma_nl_types[index].cb_table;
169 
170 	if ((cb_table[op].flags & RDMA_NL_ADMIN_PERM) &&
171 	    !netlink_capable(skb, CAP_NET_ADMIN))
172 		return -EPERM;
173 
174 	/*
175 	 * LS responses overload the 0x100 (NLM_F_ROOT) flag.  Don't
176 	 * mistakenly call the .dump() function.
177 	 */
178 	if (index == RDMA_NL_LS) {
179 		if (cb_table[op].doit)
180 			return cb_table[op].doit(skb, nlh, extack);
181 		return -EINVAL;
182 	}
183 	/* FIXME: Convert IWCM to properly handle doit callbacks */
184 	if ((nlh->nlmsg_flags & NLM_F_DUMP) || index == RDMA_NL_RDMA_CM ||
185 	    index == RDMA_NL_IWCM) {
186 		struct netlink_dump_control c = {
187 			.dump = cb_table[op].dump,
188 		};
189 		if (c.dump)
190 			return netlink_dump_start(nls, skb, nlh, &c);
191 		return -EINVAL;
192 	}
193 
194 	if (cb_table[op].doit)
195 		return cb_table[op].doit(skb, nlh, extack);
196 
197 	return 0;
198 }
199 
200 /*
201  * This function is similar to netlink_rcv_skb with one exception:
202  * It calls to the callback for the netlink messages without NLM_F_REQUEST
203  * flag. These messages are intended for RDMA_NL_LS consumer, so it is allowed
204  * for that consumer only.
205  */
206 static int rdma_nl_rcv_skb(struct sk_buff *skb, int (*cb)(struct sk_buff *,
207 						   struct nlmsghdr *,
208 						   struct netlink_ext_ack *))
209 {
210 	struct netlink_ext_ack extack = {};
211 	struct nlmsghdr *nlh;
212 	int err;
213 
214 	while (skb->len >= nlmsg_total_size(0)) {
215 		int msglen;
216 
217 		nlh = nlmsg_hdr(skb);
218 		err = 0;
219 
220 		if (nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len)
221 			return 0;
222 
223 		/*
224 		 * Generally speaking, the only requests are handled
225 		 * by the kernel, but RDMA_NL_LS is different, because it
226 		 * runs backward netlink scheme. Kernel initiates messages
227 		 * and waits for reply with data to keep pathrecord cache
228 		 * in sync.
229 		 */
230 		if (!(nlh->nlmsg_flags & NLM_F_REQUEST) &&
231 		    (RDMA_NL_GET_CLIENT(nlh->nlmsg_type) != RDMA_NL_LS))
232 			goto ack;
233 
234 		/* Skip control messages */
235 		if (nlh->nlmsg_type < NLMSG_MIN_TYPE)
236 			goto ack;
237 
238 		err = cb(skb, nlh, &extack);
239 		if (err == -EINTR)
240 			goto skip;
241 
242 ack:
243 		if (nlh->nlmsg_flags & NLM_F_ACK || err)
244 			netlink_ack(skb, nlh, err, &extack);
245 
246 skip:
247 		msglen = NLMSG_ALIGN(nlh->nlmsg_len);
248 		if (msglen > skb->len)
249 			msglen = skb->len;
250 		skb_pull(skb, msglen);
251 	}
252 
253 	return 0;
254 }
255 
256 static void rdma_nl_rcv(struct sk_buff *skb)
257 {
258 	mutex_lock(&rdma_nl_mutex);
259 	rdma_nl_rcv_skb(skb, &rdma_nl_rcv_msg);
260 	mutex_unlock(&rdma_nl_mutex);
261 }
262 
263 int rdma_nl_unicast(struct sk_buff *skb, u32 pid)
264 {
265 	int err;
266 
267 	err = netlink_unicast(nls, 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 sk_buff *skb, __u32 pid)
273 {
274 	int err;
275 
276 	err = netlink_unicast(nls, skb, pid, 0);
277 	return (err < 0) ? err : 0;
278 }
279 EXPORT_SYMBOL(rdma_nl_unicast_wait);
280 
281 int rdma_nl_multicast(struct sk_buff *skb, unsigned int group, gfp_t flags)
282 {
283 	return nlmsg_multicast(nls, skb, 0, group, flags);
284 }
285 EXPORT_SYMBOL(rdma_nl_multicast);
286 
287 int __init rdma_nl_init(void)
288 {
289 	struct netlink_kernel_cfg cfg = {
290 		.input	= rdma_nl_rcv,
291 	};
292 
293 	nls = netlink_kernel_create(&init_net, NETLINK_RDMA, &cfg);
294 	if (!nls)
295 		return -ENOMEM;
296 
297 	nls->sk_sndtimeo = 10 * HZ;
298 	return 0;
299 }
300 
301 void rdma_nl_exit(void)
302 {
303 	int idx;
304 
305 	for (idx = 0; idx < RDMA_NL_NUM_CLIENTS; idx++)
306 		rdma_nl_unregister(idx);
307 
308 	netlink_kernel_release(nls);
309 }
310 
311 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_RDMA);
312