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