libnftnl  1.2.6
expr.c
1 /*
2  * (C) 2012 by Pablo Neira Ayuso <pablo@netfilter.org>
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License as published
6  * by the Free Software Foundation; either version 2 of the License, or
7  * (at your option) any later version.
8  *
9  * This code has been sponsored by Sophos Astaro <http://www.sophos.com>
10  */
11 #include "internal.h"
12 
13 #include <time.h>
14 #include <endian.h>
15 #include <stdint.h>
16 #include <stdlib.h>
17 #include <string.h>
18 #include <errno.h>
19 #include <netinet/in.h>
20 
21 #include <libmnl/libmnl.h>
22 #include <linux/netfilter/nfnetlink.h>
23 #include <linux/netfilter/nf_tables.h>
24 
25 #include <libnftnl/expr.h>
26 
27 EXPORT_SYMBOL(nftnl_expr_alloc);
28 struct nftnl_expr *nftnl_expr_alloc(const char *name)
29 {
30  struct nftnl_expr *expr;
31  struct expr_ops *ops;
32 
33  ops = nftnl_expr_ops_lookup(name);
34  if (ops == NULL)
35  return NULL;
36 
37  expr = calloc(1, sizeof(struct nftnl_expr) + ops->alloc_len);
38  if (expr == NULL)
39  return NULL;
40 
41  /* Manually set expression name attribute */
42  expr->flags |= (1 << NFTNL_EXPR_NAME);
43  expr->ops = ops;
44 
45  if (ops->init)
46  ops->init(expr);
47 
48  return expr;
49 }
50 
51 EXPORT_SYMBOL(nftnl_expr_free);
52 void nftnl_expr_free(const struct nftnl_expr *expr)
53 {
54  if (expr->ops->free)
55  expr->ops->free(expr);
56 
57  xfree(expr);
58 }
59 
60 EXPORT_SYMBOL(nftnl_expr_is_set);
61 bool nftnl_expr_is_set(const struct nftnl_expr *expr, uint16_t type)
62 {
63  return expr->flags & (1 << type);
64 }
65 
66 EXPORT_SYMBOL(nftnl_expr_set);
67 int nftnl_expr_set(struct nftnl_expr *expr, uint16_t type,
68  const void *data, uint32_t data_len)
69 {
70  switch(type) {
71  case NFTNL_EXPR_NAME: /* cannot be modified */
72  return 0;
73  default:
74  if (expr->ops->set(expr, type, data, data_len) < 0)
75  return -1;
76  }
77  expr->flags |= (1 << type);
78  return 0;
79 }
80 
81 EXPORT_SYMBOL(nftnl_expr_set_u8);
82 void
83 nftnl_expr_set_u8(struct nftnl_expr *expr, uint16_t type, uint8_t data)
84 {
85  nftnl_expr_set(expr, type, &data, sizeof(uint8_t));
86 }
87 
88 EXPORT_SYMBOL(nftnl_expr_set_u16);
89 void
90 nftnl_expr_set_u16(struct nftnl_expr *expr, uint16_t type, uint16_t data)
91 {
92  nftnl_expr_set(expr, type, &data, sizeof(uint16_t));
93 }
94 
95 EXPORT_SYMBOL(nftnl_expr_set_u32);
96 void
97 nftnl_expr_set_u32(struct nftnl_expr *expr, uint16_t type, uint32_t data)
98 {
99  nftnl_expr_set(expr, type, &data, sizeof(uint32_t));
100 }
101 
102 EXPORT_SYMBOL(nftnl_expr_set_u64);
103 void
104 nftnl_expr_set_u64(struct nftnl_expr *expr, uint16_t type, uint64_t data)
105 {
106  nftnl_expr_set(expr, type, &data, sizeof(uint64_t));
107 }
108 
109 EXPORT_SYMBOL(nftnl_expr_set_str);
110 int nftnl_expr_set_str(struct nftnl_expr *expr, uint16_t type, const char *str)
111 {
112  return nftnl_expr_set(expr, type, str, strlen(str) + 1);
113 }
114 
115 EXPORT_SYMBOL(nftnl_expr_get);
116 const void *nftnl_expr_get(const struct nftnl_expr *expr,
117  uint16_t type, uint32_t *data_len)
118 {
119  const void *ret;
120 
121  if (!(expr->flags & (1 << type)))
122  return NULL;
123 
124  switch(type) {
125  case NFTNL_EXPR_NAME:
126  *data_len = strlen(expr->ops->name) + 1;
127  ret = expr->ops->name;
128  break;
129  default:
130  ret = expr->ops->get(expr, type, data_len);
131  break;
132  }
133 
134  return ret;
135 }
136 
137 EXPORT_SYMBOL(nftnl_expr_get_u8);
138 uint8_t nftnl_expr_get_u8(const struct nftnl_expr *expr, uint16_t type)
139 {
140  const void *data;
141  uint32_t data_len;
142 
143  data = nftnl_expr_get(expr, type, &data_len);
144  if (data == NULL)
145  return 0;
146 
147  if (data_len != sizeof(uint8_t))
148  return 0;
149 
150  return *((uint8_t *)data);
151 }
152 
153 EXPORT_SYMBOL(nftnl_expr_get_u16);
154 uint16_t nftnl_expr_get_u16(const struct nftnl_expr *expr, uint16_t type)
155 {
156  const void *data;
157  uint32_t data_len;
158 
159  data = nftnl_expr_get(expr, type, &data_len);
160  if (data == NULL)
161  return 0;
162 
163  if (data_len != sizeof(uint16_t))
164  return 0;
165 
166  return *((uint16_t *)data);
167 }
168 
169 EXPORT_SYMBOL(nftnl_expr_get_u32);
170 uint32_t nftnl_expr_get_u32(const struct nftnl_expr *expr, uint16_t type)
171 {
172  const void *data;
173  uint32_t data_len;
174 
175  data = nftnl_expr_get(expr, type, &data_len);
176  if (data == NULL)
177  return 0;
178 
179  if (data_len != sizeof(uint32_t))
180  return 0;
181 
182  return *((uint32_t *)data);
183 }
184 
185 EXPORT_SYMBOL(nftnl_expr_get_u64);
186 uint64_t nftnl_expr_get_u64(const struct nftnl_expr *expr, uint16_t type)
187 {
188  const void *data;
189  uint32_t data_len;
190 
191  data = nftnl_expr_get(expr, type, &data_len);
192  if (data == NULL)
193  return 0;
194 
195  if (data_len != sizeof(uint64_t))
196  return 0;
197 
198  return *((uint64_t *)data);
199 }
200 
201 EXPORT_SYMBOL(nftnl_expr_get_str);
202 const char *nftnl_expr_get_str(const struct nftnl_expr *expr, uint16_t type)
203 {
204  uint32_t data_len;
205 
206  return (const char *)nftnl_expr_get(expr, type, &data_len);
207 }
208 
209 EXPORT_SYMBOL(nftnl_expr_build_payload);
210 void nftnl_expr_build_payload(struct nlmsghdr *nlh, struct nftnl_expr *expr)
211 {
212  struct nlattr *nest;
213 
214  mnl_attr_put_strz(nlh, NFTA_EXPR_NAME, expr->ops->name);
215 
216  if (!expr->ops->build)
217  return;
218 
219  nest = mnl_attr_nest_start(nlh, NFTA_EXPR_DATA);
220  expr->ops->build(nlh, expr);
221  mnl_attr_nest_end(nlh, nest);
222 }
223 
224 static int nftnl_rule_parse_expr_cb(const struct nlattr *attr, void *data)
225 {
226  const struct nlattr **tb = data;
227  int type = mnl_attr_get_type(attr);
228 
229  if (mnl_attr_type_valid(attr, NFTA_EXPR_MAX) < 0)
230  return MNL_CB_OK;
231 
232  switch (type) {
233  case NFTA_EXPR_NAME:
234  if (mnl_attr_validate(attr, MNL_TYPE_STRING) < 0)
235  abi_breakage();
236  break;
237  case NFTA_EXPR_DATA:
238  if (mnl_attr_validate(attr, MNL_TYPE_NESTED) < 0)
239  abi_breakage();
240  break;
241  }
242 
243  tb[type] = attr;
244  return MNL_CB_OK;
245 }
246 
247 struct nftnl_expr *nftnl_expr_parse(struct nlattr *attr)
248 {
249  struct nlattr *tb[NFTA_EXPR_MAX+1] = {};
250  struct nftnl_expr *expr;
251 
252  if (mnl_attr_parse_nested(attr, nftnl_rule_parse_expr_cb, tb) < 0)
253  goto err1;
254 
255  expr = nftnl_expr_alloc(mnl_attr_get_str(tb[NFTA_EXPR_NAME]));
256  if (expr == NULL)
257  goto err1;
258 
259  if (tb[NFTA_EXPR_DATA] &&
260  expr->ops->parse &&
261  expr->ops->parse(expr, tb[NFTA_EXPR_DATA]) < 0)
262  goto err2;
263 
264  return expr;
265 
266 err2:
267  xfree(expr);
268 err1:
269  return NULL;
270 }
271 
272 EXPORT_SYMBOL(nftnl_expr_snprintf);
273 int nftnl_expr_snprintf(char *buf, size_t remain, const struct nftnl_expr *expr,
274  uint32_t type, uint32_t flags)
275 {
276  int ret;
277  unsigned int offset = 0;
278 
279  if (remain)
280  buf[0] = '\0';
281 
282  if (!expr->ops->output || type != NFTNL_OUTPUT_DEFAULT)
283  return 0;
284 
285  ret = expr->ops->output(buf + offset, remain, flags, expr);
286  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
287 
288  return offset;
289 }
290 
291 static int nftnl_expr_do_snprintf(char *buf, size_t size, const void *e,
292  uint32_t cmd, uint32_t type, uint32_t flags)
293 {
294  return nftnl_expr_snprintf(buf, size, e, type, flags);
295 }
296 
297 EXPORT_SYMBOL(nftnl_expr_fprintf);
298 int nftnl_expr_fprintf(FILE *fp, const struct nftnl_expr *expr, uint32_t type,
299  uint32_t flags)
300 {
301  return nftnl_fprintf(fp, expr, NFTNL_CMD_UNSPEC, type, flags,
302  nftnl_expr_do_snprintf);
303 }