1/*
2 * NETLINK      Netlink attributes
3 *
4 * 		Authors:	Thomas Graf <tgraf@suug.ch>
5 * 				Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
6 */
7
8#include <linux/export.h>
9#include <linux/kernel.h>
10#include <linux/errno.h>
11#include <linux/jiffies.h>
12#include <linux/skbuff.h>
13#include <linux/string.h>
14#include <linux/types.h>
15#include <net/netlink.h>
16
17static const u16 nla_attr_minlen[NLA_TYPE_MAX+1] = {
18	[NLA_U8]	= sizeof(u8),
19	[NLA_U16]	= sizeof(u16),
20	[NLA_U32]	= sizeof(u32),
21	[NLA_U64]	= sizeof(u64),
22	[NLA_MSECS]	= sizeof(u64),
23	[NLA_NESTED]	= NLA_HDRLEN,
24	[NLA_S8]	= sizeof(s8),
25	[NLA_S16]	= sizeof(s16),
26	[NLA_S32]	= sizeof(s32),
27	[NLA_S64]	= sizeof(s64),
28};
29
30static int validate_nla(const struct nlattr *nla, int maxtype,
31			const struct nla_policy *policy)
32{
33	const struct nla_policy *pt;
34	int minlen = 0, attrlen = nla_len(nla), type = nla_type(nla);
35
36	if (type <= 0 || type > maxtype)
37		return 0;
38
39	pt = &policy[type];
40
41	BUG_ON(pt->type > NLA_TYPE_MAX);
42
43	switch (pt->type) {
44	case NLA_FLAG:
45		if (attrlen > 0)
46			return -ERANGE;
47		break;
48
49	case NLA_NUL_STRING:
50		if (pt->len)
51			minlen = min_t(int, attrlen, pt->len + 1);
52		else
53			minlen = attrlen;
54
55		if (!minlen || memchr(nla_data(nla), '\0', minlen) == NULL)
56			return -EINVAL;
57		/* fall through */
58
59	case NLA_STRING:
60		if (attrlen < 1)
61			return -ERANGE;
62
63		if (pt->len) {
64			char *buf = nla_data(nla);
65
66			if (buf[attrlen - 1] == '\0')
67				attrlen--;
68
69			if (attrlen > pt->len)
70				return -ERANGE;
71		}
72		break;
73
74	case NLA_BINARY:
75		if (pt->len && attrlen > pt->len)
76			return -ERANGE;
77		break;
78
79	case NLA_NESTED_COMPAT:
80		if (attrlen < pt->len)
81			return -ERANGE;
82		if (attrlen < NLA_ALIGN(pt->len))
83			break;
84		if (attrlen < NLA_ALIGN(pt->len) + NLA_HDRLEN)
85			return -ERANGE;
86		nla = nla_data(nla) + NLA_ALIGN(pt->len);
87		if (attrlen < NLA_ALIGN(pt->len) + NLA_HDRLEN + nla_len(nla))
88			return -ERANGE;
89		break;
90	case NLA_NESTED:
91		/* a nested attributes is allowed to be empty; if its not,
92		 * it must have a size of at least NLA_HDRLEN.
93		 */
94		if (attrlen == 0)
95			break;
96	default:
97		if (pt->len)
98			minlen = pt->len;
99		else if (pt->type != NLA_UNSPEC)
100			minlen = nla_attr_minlen[pt->type];
101
102		if (attrlen < minlen)
103			return -ERANGE;
104	}
105
106	return 0;
107}
108
109/**
110 * nla_validate - Validate a stream of attributes
111 * @head: head of attribute stream
112 * @len: length of attribute stream
113 * @maxtype: maximum attribute type to be expected
114 * @policy: validation policy
115 *
116 * Validates all attributes in the specified attribute stream against the
117 * specified policy. Attributes with a type exceeding maxtype will be
118 * ignored. See documenation of struct nla_policy for more details.
119 *
120 * Returns 0 on success or a negative error code.
121 */
122int nla_validate(const struct nlattr *head, int len, int maxtype,
123		 const struct nla_policy *policy)
124{
125	const struct nlattr *nla;
126	int rem, err;
127
128	nla_for_each_attr(nla, head, len, rem) {
129		err = validate_nla(nla, maxtype, policy);
130		if (err < 0)
131			goto errout;
132	}
133
134	err = 0;
135errout:
136	return err;
137}
138EXPORT_SYMBOL(nla_validate);
139
140/**
141 * nla_policy_len - Determin the max. length of a policy
142 * @policy: policy to use
143 * @n: number of policies
144 *
145 * Determines the max. length of the policy.  It is currently used
146 * to allocated Netlink buffers roughly the size of the actual
147 * message.
148 *
149 * Returns 0 on success or a negative error code.
150 */
151int
152nla_policy_len(const struct nla_policy *p, int n)
153{
154	int i, len = 0;
155
156	for (i = 0; i < n; i++, p++) {
157		if (p->len)
158			len += nla_total_size(p->len);
159		else if (nla_attr_minlen[p->type])
160			len += nla_total_size(nla_attr_minlen[p->type]);
161	}
162
163	return len;
164}
165EXPORT_SYMBOL(nla_policy_len);
166
167/**
168 * nla_parse - Parse a stream of attributes into a tb buffer
169 * @tb: destination array with maxtype+1 elements
170 * @maxtype: maximum attribute type to be expected
171 * @head: head of attribute stream
172 * @len: length of attribute stream
173 * @policy: validation policy
174 *
175 * Parses a stream of attributes and stores a pointer to each attribute in
176 * the tb array accessible via the attribute type. Attributes with a type
177 * exceeding maxtype will be silently ignored for backwards compatibility
178 * reasons. policy may be set to NULL if no validation is required.
179 *
180 * Returns 0 on success or a negative error code.
181 */
182int nla_parse(struct nlattr **tb, int maxtype, const struct nlattr *head,
183	      int len, const struct nla_policy *policy)
184{
185	const struct nlattr *nla;
186	int rem, err;
187
188	memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
189
190	nla_for_each_attr(nla, head, len, rem) {
191		u16 type = nla_type(nla);
192
193		if (type > 0 && type <= maxtype) {
194			if (policy) {
195				err = validate_nla(nla, maxtype, policy);
196				if (err < 0)
197					goto errout;
198			}
199
200			tb[type] = (struct nlattr *)nla;
201		}
202	}
203
204	if (unlikely(rem > 0))
205		pr_warn_ratelimited("netlink: %d bytes leftover after parsing attributes in process `%s'.\n",
206				    rem, current->comm);
207
208	err = 0;
209errout:
210	return err;
211}
212EXPORT_SYMBOL(nla_parse);
213
214/**
215 * nla_find - Find a specific attribute in a stream of attributes
216 * @head: head of attribute stream
217 * @len: length of attribute stream
218 * @attrtype: type of attribute to look for
219 *
220 * Returns the first attribute in the stream matching the specified type.
221 */
222struct nlattr *nla_find(const struct nlattr *head, int len, int attrtype)
223{
224	const struct nlattr *nla;
225	int rem;
226
227	nla_for_each_attr(nla, head, len, rem)
228		if (nla_type(nla) == attrtype)
229			return (struct nlattr *)nla;
230
231	return NULL;
232}
233EXPORT_SYMBOL(nla_find);
234
235/**
236 * nla_strlcpy - Copy string attribute payload into a sized buffer
237 * @dst: where to copy the string to
238 * @nla: attribute to copy the string from
239 * @dstsize: size of destination buffer
240 *
241 * Copies at most dstsize - 1 bytes into the destination buffer.
242 * The result is always a valid NUL-terminated string. Unlike
243 * strlcpy the destination buffer is always padded out.
244 *
245 * Returns the length of the source buffer.
246 */
247size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)
248{
249	size_t srclen = nla_len(nla);
250	char *src = nla_data(nla);
251
252	if (srclen > 0 && src[srclen - 1] == '\0')
253		srclen--;
254
255	if (dstsize > 0) {
256		size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen;
257
258		memset(dst, 0, dstsize);
259		memcpy(dst, src, len);
260	}
261
262	return srclen;
263}
264EXPORT_SYMBOL(nla_strlcpy);
265
266/**
267 * nla_memcpy - Copy a netlink attribute into another memory area
268 * @dest: where to copy to memcpy
269 * @src: netlink attribute to copy from
270 * @count: size of the destination area
271 *
272 * Note: The number of bytes copied is limited by the length of
273 *       attribute's payload. memcpy
274 *
275 * Returns the number of bytes copied.
276 */
277int nla_memcpy(void *dest, const struct nlattr *src, int count)
278{
279	int minlen = min_t(int, count, nla_len(src));
280
281	memcpy(dest, nla_data(src), minlen);
282	if (count > minlen)
283		memset(dest + minlen, 0, count - minlen);
284
285	return minlen;
286}
287EXPORT_SYMBOL(nla_memcpy);
288
289/**
290 * nla_memcmp - Compare an attribute with sized memory area
291 * @nla: netlink attribute
292 * @data: memory area
293 * @size: size of memory area
294 */
295int nla_memcmp(const struct nlattr *nla, const void *data,
296			     size_t size)
297{
298	int d = nla_len(nla) - size;
299
300	if (d == 0)
301		d = memcmp(nla_data(nla), data, size);
302
303	return d;
304}
305EXPORT_SYMBOL(nla_memcmp);
306
307/**
308 * nla_strcmp - Compare a string attribute against a string
309 * @nla: netlink string attribute
310 * @str: another string
311 */
312int nla_strcmp(const struct nlattr *nla, const char *str)
313{
314	int len = strlen(str);
315	char *buf = nla_data(nla);
316	int attrlen = nla_len(nla);
317	int d;
318
319	if (attrlen > 0 && buf[attrlen - 1] == '\0')
320		attrlen--;
321
322	d = attrlen - len;
323	if (d == 0)
324		d = memcmp(nla_data(nla), str, len);
325
326	return d;
327}
328EXPORT_SYMBOL(nla_strcmp);
329
330#ifdef CONFIG_NET
331/**
332 * __nla_reserve - reserve room for attribute on the skb
333 * @skb: socket buffer to reserve room on
334 * @attrtype: attribute type
335 * @attrlen: length of attribute payload
336 *
337 * Adds a netlink attribute header to a socket buffer and reserves
338 * room for the payload but does not copy it.
339 *
340 * The caller is responsible to ensure that the skb provides enough
341 * tailroom for the attribute header and payload.
342 */
343struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
344{
345	struct nlattr *nla;
346
347	nla = (struct nlattr *) skb_put(skb, nla_total_size(attrlen));
348	nla->nla_type = attrtype;
349	nla->nla_len = nla_attr_size(attrlen);
350
351	memset((unsigned char *) nla + nla->nla_len, 0, nla_padlen(attrlen));
352
353	return nla;
354}
355EXPORT_SYMBOL(__nla_reserve);
356
357/**
358 * __nla_reserve_nohdr - reserve room for attribute without header
359 * @skb: socket buffer to reserve room on
360 * @attrlen: length of attribute payload
361 *
362 * Reserves room for attribute payload without a header.
363 *
364 * The caller is responsible to ensure that the skb provides enough
365 * tailroom for the payload.
366 */
367void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
368{
369	void *start;
370
371	start = skb_put(skb, NLA_ALIGN(attrlen));
372	memset(start, 0, NLA_ALIGN(attrlen));
373
374	return start;
375}
376EXPORT_SYMBOL(__nla_reserve_nohdr);
377
378/**
379 * nla_reserve - reserve room for attribute on the skb
380 * @skb: socket buffer to reserve room on
381 * @attrtype: attribute type
382 * @attrlen: length of attribute payload
383 *
384 * Adds a netlink attribute header to a socket buffer and reserves
385 * room for the payload but does not copy it.
386 *
387 * Returns NULL if the tailroom of the skb is insufficient to store
388 * the attribute header and payload.
389 */
390struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
391{
392	if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
393		return NULL;
394
395	return __nla_reserve(skb, attrtype, attrlen);
396}
397EXPORT_SYMBOL(nla_reserve);
398
399/**
400 * nla_reserve_nohdr - reserve room for attribute without header
401 * @skb: socket buffer to reserve room on
402 * @attrlen: length of attribute payload
403 *
404 * Reserves room for attribute payload without a header.
405 *
406 * Returns NULL if the tailroom of the skb is insufficient to store
407 * the attribute payload.
408 */
409void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
410{
411	if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
412		return NULL;
413
414	return __nla_reserve_nohdr(skb, attrlen);
415}
416EXPORT_SYMBOL(nla_reserve_nohdr);
417
418/**
419 * __nla_put - Add a netlink attribute to a socket buffer
420 * @skb: socket buffer to add attribute to
421 * @attrtype: attribute type
422 * @attrlen: length of attribute payload
423 * @data: head of attribute payload
424 *
425 * The caller is responsible to ensure that the skb provides enough
426 * tailroom for the attribute header and payload.
427 */
428void __nla_put(struct sk_buff *skb, int attrtype, int attrlen,
429			     const void *data)
430{
431	struct nlattr *nla;
432
433	nla = __nla_reserve(skb, attrtype, attrlen);
434	memcpy(nla_data(nla), data, attrlen);
435}
436EXPORT_SYMBOL(__nla_put);
437
438/**
439 * __nla_put_nohdr - Add a netlink attribute without header
440 * @skb: socket buffer to add attribute to
441 * @attrlen: length of attribute payload
442 * @data: head of attribute payload
443 *
444 * The caller is responsible to ensure that the skb provides enough
445 * tailroom for the attribute payload.
446 */
447void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
448{
449	void *start;
450
451	start = __nla_reserve_nohdr(skb, attrlen);
452	memcpy(start, data, attrlen);
453}
454EXPORT_SYMBOL(__nla_put_nohdr);
455
456/**
457 * nla_put - Add a netlink attribute to a socket buffer
458 * @skb: socket buffer to add attribute to
459 * @attrtype: attribute type
460 * @attrlen: length of attribute payload
461 * @data: head of attribute payload
462 *
463 * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
464 * the attribute header and payload.
465 */
466int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data)
467{
468	if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
469		return -EMSGSIZE;
470
471	__nla_put(skb, attrtype, attrlen, data);
472	return 0;
473}
474EXPORT_SYMBOL(nla_put);
475
476/**
477 * nla_put_nohdr - Add a netlink attribute without header
478 * @skb: socket buffer to add attribute to
479 * @attrlen: length of attribute payload
480 * @data: head of attribute payload
481 *
482 * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
483 * the attribute payload.
484 */
485int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
486{
487	if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
488		return -EMSGSIZE;
489
490	__nla_put_nohdr(skb, attrlen, data);
491	return 0;
492}
493EXPORT_SYMBOL(nla_put_nohdr);
494
495/**
496 * nla_append - Add a netlink attribute without header or padding
497 * @skb: socket buffer to add attribute to
498 * @attrlen: length of attribute payload
499 * @data: head of attribute payload
500 *
501 * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
502 * the attribute payload.
503 */
504int nla_append(struct sk_buff *skb, int attrlen, const void *data)
505{
506	if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
507		return -EMSGSIZE;
508
509	memcpy(skb_put(skb, attrlen), data, attrlen);
510	return 0;
511}
512EXPORT_SYMBOL(nla_append);
513#endif
514