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bfa83a9e TG |
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/config.h> | |
9 | #include <linux/module.h> | |
10 | #include <linux/kernel.h> | |
11 | #include <linux/errno.h> | |
12 | #include <linux/jiffies.h> | |
13 | #include <linux/netdevice.h> | |
14 | #include <linux/skbuff.h> | |
15 | #include <linux/string.h> | |
16 | #include <linux/types.h> | |
17 | #include <net/netlink.h> | |
18 | ||
19 | static u16 nla_attr_minlen[NLA_TYPE_MAX+1] __read_mostly = { | |
20 | [NLA_U8] = sizeof(u8), | |
21 | [NLA_U16] = sizeof(u16), | |
22 | [NLA_U32] = sizeof(u32), | |
23 | [NLA_U64] = sizeof(u64), | |
24 | [NLA_STRING] = 1, | |
25 | [NLA_NESTED] = NLA_HDRLEN, | |
26 | }; | |
27 | ||
28 | static int validate_nla(struct nlattr *nla, int maxtype, | |
29 | struct nla_policy *policy) | |
30 | { | |
31 | struct nla_policy *pt; | |
32 | int minlen = 0; | |
33 | ||
34 | if (nla->nla_type <= 0 || nla->nla_type > maxtype) | |
35 | return 0; | |
36 | ||
37 | pt = &policy[nla->nla_type]; | |
38 | ||
39 | BUG_ON(pt->type > NLA_TYPE_MAX); | |
40 | ||
41 | if (pt->minlen) | |
42 | minlen = pt->minlen; | |
43 | else if (pt->type != NLA_UNSPEC) | |
44 | minlen = nla_attr_minlen[pt->type]; | |
45 | ||
46 | if (pt->type == NLA_FLAG && nla_len(nla) > 0) | |
47 | return -ERANGE; | |
48 | ||
49 | if (nla_len(nla) < minlen) | |
50 | return -ERANGE; | |
51 | ||
52 | return 0; | |
53 | } | |
54 | ||
55 | /** | |
56 | * nla_validate - Validate a stream of attributes | |
57 | * @head: head of attribute stream | |
58 | * @len: length of attribute stream | |
59 | * @maxtype: maximum attribute type to be expected | |
60 | * @policy: validation policy | |
61 | * | |
62 | * Validates all attributes in the specified attribute stream against the | |
63 | * specified policy. Attributes with a type exceeding maxtype will be | |
64 | * ignored. See documenation of struct nla_policy for more details. | |
65 | * | |
66 | * Returns 0 on success or a negative error code. | |
67 | */ | |
68 | int nla_validate(struct nlattr *head, int len, int maxtype, | |
69 | struct nla_policy *policy) | |
70 | { | |
71 | struct nlattr *nla; | |
72 | int rem, err; | |
73 | ||
74 | nla_for_each_attr(nla, head, len, rem) { | |
75 | err = validate_nla(nla, maxtype, policy); | |
76 | if (err < 0) | |
77 | goto errout; | |
78 | } | |
79 | ||
80 | err = 0; | |
81 | errout: | |
82 | return err; | |
83 | } | |
84 | ||
85 | /** | |
86 | * nla_parse - Parse a stream of attributes into a tb buffer | |
87 | * @tb: destination array with maxtype+1 elements | |
88 | * @maxtype: maximum attribute type to be expected | |
89 | * @head: head of attribute stream | |
90 | * @len: length of attribute stream | |
91 | * | |
92 | * Parses a stream of attributes and stores a pointer to each attribute in | |
93 | * the tb array accessable via the attribute type. Attributes with a type | |
94 | * exceeding maxtype will be silently ignored for backwards compatibility | |
95 | * reasons. policy may be set to NULL if no validation is required. | |
96 | * | |
97 | * Returns 0 on success or a negative error code. | |
98 | */ | |
99 | int nla_parse(struct nlattr *tb[], int maxtype, struct nlattr *head, int len, | |
100 | struct nla_policy *policy) | |
101 | { | |
102 | struct nlattr *nla; | |
103 | int rem, err; | |
104 | ||
105 | memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1)); | |
106 | ||
107 | nla_for_each_attr(nla, head, len, rem) { | |
108 | u16 type = nla->nla_type; | |
109 | ||
110 | if (type > 0 && type <= maxtype) { | |
111 | if (policy) { | |
112 | err = validate_nla(nla, maxtype, policy); | |
113 | if (err < 0) | |
114 | goto errout; | |
115 | } | |
116 | ||
117 | tb[type] = nla; | |
118 | } | |
119 | } | |
120 | ||
121 | if (unlikely(rem > 0)) | |
122 | printk(KERN_WARNING "netlink: %d bytes leftover after parsing " | |
123 | "attributes.\n", rem); | |
124 | ||
125 | err = 0; | |
126 | errout: | |
127 | return err; | |
128 | } | |
129 | ||
130 | /** | |
131 | * nla_find - Find a specific attribute in a stream of attributes | |
132 | * @head: head of attribute stream | |
133 | * @len: length of attribute stream | |
134 | * @attrtype: type of attribute to look for | |
135 | * | |
136 | * Returns the first attribute in the stream matching the specified type. | |
137 | */ | |
138 | struct nlattr *nla_find(struct nlattr *head, int len, int attrtype) | |
139 | { | |
140 | struct nlattr *nla; | |
141 | int rem; | |
142 | ||
143 | nla_for_each_attr(nla, head, len, rem) | |
144 | if (nla->nla_type == attrtype) | |
145 | return nla; | |
146 | ||
147 | return NULL; | |
148 | } | |
149 | ||
150 | /** | |
151 | * nla_strlcpy - Copy string attribute payload into a sized buffer | |
152 | * @dst: where to copy the string to | |
153 | * @src: attribute to copy the string from | |
154 | * @dstsize: size of destination buffer | |
155 | * | |
156 | * Copies at most dstsize - 1 bytes into the destination buffer. | |
157 | * The result is always a valid NUL-terminated string. Unlike | |
158 | * strlcpy the destination buffer is always padded out. | |
159 | * | |
160 | * Returns the length of the source buffer. | |
161 | */ | |
162 | size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize) | |
163 | { | |
164 | size_t srclen = nla_len(nla); | |
165 | char *src = nla_data(nla); | |
166 | ||
167 | if (srclen > 0 && src[srclen - 1] == '\0') | |
168 | srclen--; | |
169 | ||
170 | if (dstsize > 0) { | |
171 | size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen; | |
172 | ||
173 | memset(dst, 0, dstsize); | |
174 | memcpy(dst, src, len); | |
175 | } | |
176 | ||
177 | return srclen; | |
178 | } | |
179 | ||
180 | /** | |
181 | * nla_memcpy - Copy a netlink attribute into another memory area | |
182 | * @dest: where to copy to memcpy | |
183 | * @src: netlink attribute to copy from | |
184 | * @count: size of the destination area | |
185 | * | |
186 | * Note: The number of bytes copied is limited by the length of | |
187 | * attribute's payload. memcpy | |
188 | * | |
189 | * Returns the number of bytes copied. | |
190 | */ | |
191 | int nla_memcpy(void *dest, struct nlattr *src, int count) | |
192 | { | |
193 | int minlen = min_t(int, count, nla_len(src)); | |
194 | ||
195 | memcpy(dest, nla_data(src), minlen); | |
196 | ||
197 | return minlen; | |
198 | } | |
199 | ||
200 | /** | |
201 | * nla_memcmp - Compare an attribute with sized memory area | |
202 | * @nla: netlink attribute | |
203 | * @data: memory area | |
204 | * @size: size of memory area | |
205 | */ | |
206 | int nla_memcmp(const struct nlattr *nla, const void *data, | |
207 | size_t size) | |
208 | { | |
209 | int d = nla_len(nla) - size; | |
210 | ||
211 | if (d == 0) | |
212 | d = memcmp(nla_data(nla), data, size); | |
213 | ||
214 | return d; | |
215 | } | |
216 | ||
217 | /** | |
218 | * nla_strcmp - Compare a string attribute against a string | |
219 | * @nla: netlink string attribute | |
220 | * @str: another string | |
221 | */ | |
222 | int nla_strcmp(const struct nlattr *nla, const char *str) | |
223 | { | |
224 | int len = strlen(str) + 1; | |
225 | int d = nla_len(nla) - len; | |
226 | ||
227 | if (d == 0) | |
228 | d = memcmp(nla_data(nla), str, len); | |
229 | ||
230 | return d; | |
231 | } | |
232 | ||
233 | /** | |
234 | * __nla_reserve - reserve room for attribute on the skb | |
235 | * @skb: socket buffer to reserve room on | |
236 | * @attrtype: attribute type | |
237 | * @attrlen: length of attribute payload | |
238 | * | |
239 | * Adds a netlink attribute header to a socket buffer and reserves | |
240 | * room for the payload but does not copy it. | |
241 | * | |
242 | * The caller is responsible to ensure that the skb provides enough | |
243 | * tailroom for the attribute header and payload. | |
244 | */ | |
245 | struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen) | |
246 | { | |
247 | struct nlattr *nla; | |
248 | ||
249 | nla = (struct nlattr *) skb_put(skb, nla_total_size(attrlen)); | |
250 | nla->nla_type = attrtype; | |
251 | nla->nla_len = nla_attr_size(attrlen); | |
252 | ||
253 | memset((unsigned char *) nla + nla->nla_len, 0, nla_padlen(attrlen)); | |
254 | ||
255 | return nla; | |
256 | } | |
257 | ||
258 | /** | |
259 | * nla_reserve - reserve room for attribute on the skb | |
260 | * @skb: socket buffer to reserve room on | |
261 | * @attrtype: attribute type | |
262 | * @attrlen: length of attribute payload | |
263 | * | |
264 | * Adds a netlink attribute header to a socket buffer and reserves | |
265 | * room for the payload but does not copy it. | |
266 | * | |
267 | * Returns NULL if the tailroom of the skb is insufficient to store | |
268 | * the attribute header and payload. | |
269 | */ | |
270 | struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen) | |
271 | { | |
272 | if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen))) | |
273 | return NULL; | |
274 | ||
275 | return __nla_reserve(skb, attrtype, attrlen); | |
276 | } | |
277 | ||
278 | /** | |
279 | * __nla_put - Add a netlink attribute to a socket buffer | |
280 | * @skb: socket buffer to add attribute to | |
281 | * @attrtype: attribute type | |
282 | * @attrlen: length of attribute payload | |
283 | * @data: head of attribute payload | |
284 | * | |
285 | * The caller is responsible to ensure that the skb provides enough | |
286 | * tailroom for the attribute header and payload. | |
287 | */ | |
288 | void __nla_put(struct sk_buff *skb, int attrtype, int attrlen, | |
289 | const void *data) | |
290 | { | |
291 | struct nlattr *nla; | |
292 | ||
293 | nla = __nla_reserve(skb, attrtype, attrlen); | |
294 | memcpy(nla_data(nla), data, attrlen); | |
295 | } | |
296 | ||
297 | ||
298 | /** | |
299 | * nla_put - Add a netlink attribute to a socket buffer | |
300 | * @skb: socket buffer to add attribute to | |
301 | * @attrtype: attribute type | |
302 | * @attrlen: length of attribute payload | |
303 | * @data: head of attribute payload | |
304 | * | |
305 | * Returns -1 if the tailroom of the skb is insufficient to store | |
306 | * the attribute header and payload. | |
307 | */ | |
308 | int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data) | |
309 | { | |
310 | if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen))) | |
311 | return -1; | |
312 | ||
313 | __nla_put(skb, attrtype, attrlen, data); | |
314 | return 0; | |
315 | } | |
316 | ||
317 | ||
318 | EXPORT_SYMBOL(nla_validate); | |
319 | EXPORT_SYMBOL(nla_parse); | |
320 | EXPORT_SYMBOL(nla_find); | |
321 | EXPORT_SYMBOL(nla_strlcpy); | |
322 | EXPORT_SYMBOL(__nla_reserve); | |
323 | EXPORT_SYMBOL(nla_reserve); | |
324 | EXPORT_SYMBOL(__nla_put); | |
325 | EXPORT_SYMBOL(nla_put); | |
326 | EXPORT_SYMBOL(nla_memcpy); | |
327 | EXPORT_SYMBOL(nla_memcmp); | |
328 | EXPORT_SYMBOL(nla_strcmp); |