Root/lib/nlattr.c

Source at commit b386be689295730688885552666ea40b2e639b14 created 8 years 11 months ago.
By Maarten ter Huurne, Revert "MIPS: JZ4740: reset: Initialize hibernate wakeup counters."
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/module.h>
9#include <linux/kernel.h>
10#include <linux/errno.h>
11#include <linux/jiffies.h>
12#include <linux/netdevice.h>
13#include <linux/skbuff.h>
14#include <linux/string.h>
15#include <linux/types.h>
16#include <net/netlink.h>
17
18static const u16 nla_attr_minlen[NLA_TYPE_MAX+1] = {
19    [NLA_U8] = sizeof(u8),
20    [NLA_U16] = sizeof(u16),
21    [NLA_U32] = sizeof(u32),
22    [NLA_U64] = sizeof(u64),
23    [NLA_MSECS] = sizeof(u64),
24    [NLA_NESTED] = NLA_HDRLEN,
25};
26
27static int validate_nla(const struct nlattr *nla, int maxtype,
28            const struct nla_policy *policy)
29{
30    const struct nla_policy *pt;
31    int minlen = 0, attrlen = nla_len(nla), type = nla_type(nla);
32
33    if (type <= 0 || type > maxtype)
34        return 0;
35
36    pt = &policy[type];
37
38    BUG_ON(pt->type > NLA_TYPE_MAX);
39
40    switch (pt->type) {
41    case NLA_FLAG:
42        if (attrlen > 0)
43            return -ERANGE;
44        break;
45
46    case NLA_NUL_STRING:
47        if (pt->len)
48            minlen = min_t(int, attrlen, pt->len + 1);
49        else
50            minlen = attrlen;
51
52        if (!minlen || memchr(nla_data(nla), '\0', minlen) == NULL)
53            return -EINVAL;
54        /* fall through */
55
56    case NLA_STRING:
57        if (attrlen < 1)
58            return -ERANGE;
59
60        if (pt->len) {
61            char *buf = nla_data(nla);
62
63            if (buf[attrlen - 1] == '\0')
64                attrlen--;
65
66            if (attrlen > pt->len)
67                return -ERANGE;
68        }
69        break;
70
71    case NLA_BINARY:
72        if (pt->len && attrlen > pt->len)
73            return -ERANGE;
74        break;
75
76    case NLA_NESTED_COMPAT:
77        if (attrlen < pt->len)
78            return -ERANGE;
79        if (attrlen < NLA_ALIGN(pt->len))
80            break;
81        if (attrlen < NLA_ALIGN(pt->len) + NLA_HDRLEN)
82            return -ERANGE;
83        nla = nla_data(nla) + NLA_ALIGN(pt->len);
84        if (attrlen < NLA_ALIGN(pt->len) + NLA_HDRLEN + nla_len(nla))
85            return -ERANGE;
86        break;
87    case NLA_NESTED:
88        /* a nested attributes is allowed to be empty; if its not,
89         * it must have a size of at least NLA_HDRLEN.
90         */
91        if (attrlen == 0)
92            break;
93    default:
94        if (pt->len)
95            minlen = pt->len;
96        else if (pt->type != NLA_UNSPEC)
97            minlen = nla_attr_minlen[pt->type];
98
99        if (attrlen < minlen)
100            return -ERANGE;
101    }
102
103    return 0;
104}
105
106/**
107 * nla_validate - Validate a stream of attributes
108 * @head: head of attribute stream
109 * @len: length of attribute stream
110 * @maxtype: maximum attribute type to be expected
111 * @policy: validation policy
112 *
113 * Validates all attributes in the specified attribute stream against the
114 * specified policy. Attributes with a type exceeding maxtype will be
115 * ignored. See documenation of struct nla_policy for more details.
116 *
117 * Returns 0 on success or a negative error code.
118 */
119int nla_validate(const struct nlattr *head, int len, int maxtype,
120         const struct nla_policy *policy)
121{
122    const struct nlattr *nla;
123    int rem, err;
124
125    nla_for_each_attr(nla, head, len, rem) {
126        err = validate_nla(nla, maxtype, policy);
127        if (err < 0)
128            goto errout;
129    }
130
131    err = 0;
132errout:
133    return err;
134}
135
136/**
137 * nla_policy_len - Determin the max. length of a policy
138 * @policy: policy to use
139 * @n: number of policies
140 *
141 * Determines the max. length of the policy. It is currently used
142 * to allocated Netlink buffers roughly the size of the actual
143 * message.
144 *
145 * Returns 0 on success or a negative error code.
146 */
147int
148nla_policy_len(const struct nla_policy *p, int n)
149{
150    int i, len = 0;
151
152    for (i = 0; i < n; i++, p++) {
153        if (p->len)
154            len += nla_total_size(p->len);
155        else if (nla_attr_minlen[p->type])
156            len += nla_total_size(nla_attr_minlen[p->type]);
157    }
158
159    return len;
160}
161
162/**
163 * nla_parse - Parse a stream of attributes into a tb buffer
164 * @tb: destination array with maxtype+1 elements
165 * @maxtype: maximum attribute type to be expected
166 * @head: head of attribute stream
167 * @len: length of attribute stream
168 * @policy: validation policy
169 *
170 * Parses a stream of attributes and stores a pointer to each attribute in
171 * the tb array accessible via the attribute type. Attributes with a type
172 * exceeding maxtype will be silently ignored for backwards compatibility
173 * reasons. policy may be set to NULL if no validation is required.
174 *
175 * Returns 0 on success or a negative error code.
176 */
177int nla_parse(struct nlattr **tb, int maxtype, const struct nlattr *head,
178          int len, const struct nla_policy *policy)
179{
180    const struct nlattr *nla;
181    int rem, err;
182
183    memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
184
185    nla_for_each_attr(nla, head, len, rem) {
186        u16 type = nla_type(nla);
187
188        if (type > 0 && type <= maxtype) {
189            if (policy) {
190                err = validate_nla(nla, maxtype, policy);
191                if (err < 0)
192                    goto errout;
193            }
194
195            tb[type] = (struct nlattr *)nla;
196        }
197    }
198
199    if (unlikely(rem > 0))
200        printk(KERN_WARNING "netlink: %d bytes leftover after parsing "
201               "attributes.\n", rem);
202
203    err = 0;
204errout:
205    return err;
206}
207
208/**
209 * nla_find - Find a specific attribute in a stream of attributes
210 * @head: head of attribute stream
211 * @len: length of attribute stream
212 * @attrtype: type of attribute to look for
213 *
214 * Returns the first attribute in the stream matching the specified type.
215 */
216struct nlattr *nla_find(const struct nlattr *head, int len, int attrtype)
217{
218    const struct nlattr *nla;
219    int rem;
220
221    nla_for_each_attr(nla, head, len, rem)
222        if (nla_type(nla) == attrtype)
223            return (struct nlattr *)nla;
224
225    return NULL;
226}
227
228/**
229 * nla_strlcpy - Copy string attribute payload into a sized buffer
230 * @dst: where to copy the string to
231 * @nla: attribute to copy the string from
232 * @dstsize: size of destination buffer
233 *
234 * Copies at most dstsize - 1 bytes into the destination buffer.
235 * The result is always a valid NUL-terminated string. Unlike
236 * strlcpy the destination buffer is always padded out.
237 *
238 * Returns the length of the source buffer.
239 */
240size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)
241{
242    size_t srclen = nla_len(nla);
243    char *src = nla_data(nla);
244
245    if (srclen > 0 && src[srclen - 1] == '\0')
246        srclen--;
247
248    if (dstsize > 0) {
249        size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen;
250
251        memset(dst, 0, dstsize);
252        memcpy(dst, src, len);
253    }
254
255    return srclen;
256}
257
258/**
259 * nla_memcpy - Copy a netlink attribute into another memory area
260 * @dest: where to copy to memcpy
261 * @src: netlink attribute to copy from
262 * @count: size of the destination area
263 *
264 * Note: The number of bytes copied is limited by the length of
265 * attribute's payload. memcpy
266 *
267 * Returns the number of bytes copied.
268 */
269int nla_memcpy(void *dest, const struct nlattr *src, int count)
270{
271    int minlen = min_t(int, count, nla_len(src));
272
273    memcpy(dest, nla_data(src), minlen);
274
275    return minlen;
276}
277
278/**
279 * nla_memcmp - Compare an attribute with sized memory area
280 * @nla: netlink attribute
281 * @data: memory area
282 * @size: size of memory area
283 */
284int nla_memcmp(const struct nlattr *nla, const void *data,
285                 size_t size)
286{
287    int d = nla_len(nla) - size;
288
289    if (d == 0)
290        d = memcmp(nla_data(nla), data, size);
291
292    return d;
293}
294
295/**
296 * nla_strcmp - Compare a string attribute against a string
297 * @nla: netlink string attribute
298 * @str: another string
299 */
300int nla_strcmp(const struct nlattr *nla, const char *str)
301{
302    int len = strlen(str) + 1;
303    int d = nla_len(nla) - len;
304
305    if (d == 0)
306        d = memcmp(nla_data(nla), str, len);
307
308    return d;
309}
310
311#ifdef CONFIG_NET
312/**
313 * __nla_reserve - reserve room for attribute on the skb
314 * @skb: socket buffer to reserve room on
315 * @attrtype: attribute type
316 * @attrlen: length of attribute payload
317 *
318 * Adds a netlink attribute header to a socket buffer and reserves
319 * room for the payload but does not copy it.
320 *
321 * The caller is responsible to ensure that the skb provides enough
322 * tailroom for the attribute header and payload.
323 */
324struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
325{
326    struct nlattr *nla;
327
328    nla = (struct nlattr *) skb_put(skb, nla_total_size(attrlen));
329    nla->nla_type = attrtype;
330    nla->nla_len = nla_attr_size(attrlen);
331
332    memset((unsigned char *) nla + nla->nla_len, 0, nla_padlen(attrlen));
333
334    return nla;
335}
336EXPORT_SYMBOL(__nla_reserve);
337
338/**
339 * __nla_reserve_nohdr - reserve room for attribute without header
340 * @skb: socket buffer to reserve room on
341 * @attrlen: length of attribute payload
342 *
343 * Reserves room for attribute payload without a header.
344 *
345 * The caller is responsible to ensure that the skb provides enough
346 * tailroom for the payload.
347 */
348void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
349{
350    void *start;
351
352    start = skb_put(skb, NLA_ALIGN(attrlen));
353    memset(start, 0, NLA_ALIGN(attrlen));
354
355    return start;
356}
357EXPORT_SYMBOL(__nla_reserve_nohdr);
358
359/**
360 * nla_reserve - reserve room for attribute on the skb
361 * @skb: socket buffer to reserve room on
362 * @attrtype: attribute type
363 * @attrlen: length of attribute payload
364 *
365 * Adds a netlink attribute header to a socket buffer and reserves
366 * room for the payload but does not copy it.
367 *
368 * Returns NULL if the tailroom of the skb is insufficient to store
369 * the attribute header and payload.
370 */
371struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
372{
373    if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
374        return NULL;
375
376    return __nla_reserve(skb, attrtype, attrlen);
377}
378EXPORT_SYMBOL(nla_reserve);
379
380/**
381 * nla_reserve_nohdr - reserve room for attribute without header
382 * @skb: socket buffer to reserve room on
383 * @attrlen: length of attribute payload
384 *
385 * Reserves room for attribute payload without a header.
386 *
387 * Returns NULL if the tailroom of the skb is insufficient to store
388 * the attribute payload.
389 */
390void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
391{
392    if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
393        return NULL;
394
395    return __nla_reserve_nohdr(skb, attrlen);
396}
397EXPORT_SYMBOL(nla_reserve_nohdr);
398
399/**
400 * __nla_put - Add a netlink attribute to a socket buffer
401 * @skb: socket buffer to add attribute to
402 * @attrtype: attribute type
403 * @attrlen: length of attribute payload
404 * @data: head of attribute payload
405 *
406 * The caller is responsible to ensure that the skb provides enough
407 * tailroom for the attribute header and payload.
408 */
409void __nla_put(struct sk_buff *skb, int attrtype, int attrlen,
410                 const void *data)
411{
412    struct nlattr *nla;
413
414    nla = __nla_reserve(skb, attrtype, attrlen);
415    memcpy(nla_data(nla), data, attrlen);
416}
417EXPORT_SYMBOL(__nla_put);
418
419/**
420 * __nla_put_nohdr - Add a netlink attribute without header
421 * @skb: socket buffer to add attribute to
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 payload.
427 */
428void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
429{
430    void *start;
431
432    start = __nla_reserve_nohdr(skb, attrlen);
433    memcpy(start, data, attrlen);
434}
435EXPORT_SYMBOL(__nla_put_nohdr);
436
437/**
438 * nla_put - Add a netlink attribute to a socket buffer
439 * @skb: socket buffer to add attribute to
440 * @attrtype: attribute type
441 * @attrlen: length of attribute payload
442 * @data: head of attribute payload
443 *
444 * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
445 * the attribute header and payload.
446 */
447int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data)
448{
449    if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
450        return -EMSGSIZE;
451
452    __nla_put(skb, attrtype, attrlen, data);
453    return 0;
454}
455EXPORT_SYMBOL(nla_put);
456
457/**
458 * nla_put_nohdr - Add a netlink attribute without header
459 * @skb: socket buffer to add attribute to
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 payload.
465 */
466int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
467{
468    if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
469        return -EMSGSIZE;
470
471    __nla_put_nohdr(skb, attrlen, data);
472    return 0;
473}
474EXPORT_SYMBOL(nla_put_nohdr);
475
476/**
477 * nla_append - Add a netlink attribute without header or padding
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_append(struct sk_buff *skb, int attrlen, const void *data)
486{
487    if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
488        return -EMSGSIZE;
489
490    memcpy(skb_put(skb, attrlen), data, attrlen);
491    return 0;
492}
493EXPORT_SYMBOL(nla_append);
494#endif
495
496EXPORT_SYMBOL(nla_validate);
497EXPORT_SYMBOL(nla_policy_len);
498EXPORT_SYMBOL(nla_parse);
499EXPORT_SYMBOL(nla_find);
500EXPORT_SYMBOL(nla_strlcpy);
501EXPORT_SYMBOL(nla_memcpy);
502EXPORT_SYMBOL(nla_memcmp);
503EXPORT_SYMBOL(nla_strcmp);
504

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