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authorThomas Graf <tgraf@suug.ch>2005-11-09 20:25:51 -0500
committerThomas Graf <tgr@axs.localdomain>2005-11-09 20:26:40 -0500
commitbfa83a9e03cf8d501c6272999843470afecb32ed (patch)
tree1584441824b67bee52906a1345d8277e6965fe1b /net/netlink
parent9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 (diff)
[NETLINK]: Type-safe netlink messages/attributes interface
Introduces a new type-safe interface for netlink message and attributes handling. The interface is fully binary compatible with the old interface towards userspace. Besides type safety, this interface features attribute validation capabilities, simplified message contstruction, and documentation. The resulting netlink code should be smaller, less error prone and easier to understand. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/netlink')
-rw-r--r--net/netlink/Makefile2
-rw-r--r--net/netlink/attr.c328
2 files changed, 329 insertions, 1 deletions
diff --git a/net/netlink/Makefile b/net/netlink/Makefile
index 39d9c2dcd03..68179015bd3 100644
--- a/net/netlink/Makefile
+++ b/net/netlink/Makefile
@@ -2,4 +2,4 @@
2# Makefile for the netlink driver. 2# Makefile for the netlink driver.
3# 3#
4 4
5obj-y := af_netlink.o 5obj-y := af_netlink.o attr.o
diff --git a/net/netlink/attr.c b/net/netlink/attr.c
new file mode 100644
index 00000000000..fffef4ab276
--- /dev/null
+++ b/net/netlink/attr.c
@@ -0,0 +1,328 @@
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
19static 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
28static 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 */
68int 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;
81errout:
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 */
99int 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;
126errout:
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 */
138struct 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 */
162size_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 */
191int 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 */
206int 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 */
222int 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 */
245struct 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 */
270struct 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 */
288void __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 */
308int 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
318EXPORT_SYMBOL(nla_validate);
319EXPORT_SYMBOL(nla_parse);
320EXPORT_SYMBOL(nla_find);
321EXPORT_SYMBOL(nla_strlcpy);
322EXPORT_SYMBOL(__nla_reserve);
323EXPORT_SYMBOL(nla_reserve);
324EXPORT_SYMBOL(__nla_put);
325EXPORT_SYMBOL(nla_put);
326EXPORT_SYMBOL(nla_memcpy);
327EXPORT_SYMBOL(nla_memcmp);
328EXPORT_SYMBOL(nla_strcmp);