libnftnl  1.2.8
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 (type < NFTNL_EXPR_BASE || type > expr->ops->nftnl_max_attr)
75  return -1;
76 
77  if (!expr->ops->attr_policy)
78  return -1;
79 
80  if (expr->ops->attr_policy[type].maxlen &&
81  expr->ops->attr_policy[type].maxlen < data_len)
82  return -1;
83 
84  if (expr->ops->set(expr, type, data, data_len) < 0)
85  return -1;
86  }
87  expr->flags |= (1 << type);
88  return 0;
89 }
90 
91 EXPORT_SYMBOL(nftnl_expr_set_u8);
92 void
93 nftnl_expr_set_u8(struct nftnl_expr *expr, uint16_t type, uint8_t data)
94 {
95  nftnl_expr_set(expr, type, &data, sizeof(uint8_t));
96 }
97 
98 EXPORT_SYMBOL(nftnl_expr_set_u16);
99 void
100 nftnl_expr_set_u16(struct nftnl_expr *expr, uint16_t type, uint16_t data)
101 {
102  nftnl_expr_set(expr, type, &data, sizeof(uint16_t));
103 }
104 
105 EXPORT_SYMBOL(nftnl_expr_set_u32);
106 void
107 nftnl_expr_set_u32(struct nftnl_expr *expr, uint16_t type, uint32_t data)
108 {
109  nftnl_expr_set(expr, type, &data, sizeof(uint32_t));
110 }
111 
112 EXPORT_SYMBOL(nftnl_expr_set_u64);
113 void
114 nftnl_expr_set_u64(struct nftnl_expr *expr, uint16_t type, uint64_t data)
115 {
116  nftnl_expr_set(expr, type, &data, sizeof(uint64_t));
117 }
118 
119 EXPORT_SYMBOL(nftnl_expr_set_str);
120 int nftnl_expr_set_str(struct nftnl_expr *expr, uint16_t type, const char *str)
121 {
122  return nftnl_expr_set(expr, type, str, strlen(str) + 1);
123 }
124 
125 EXPORT_SYMBOL(nftnl_expr_get);
126 const void *nftnl_expr_get(const struct nftnl_expr *expr,
127  uint16_t type, uint32_t *data_len)
128 {
129  const void *ret;
130 
131  if (!(expr->flags & (1 << type)))
132  return NULL;
133 
134  switch(type) {
135  case NFTNL_EXPR_NAME:
136  *data_len = strlen(expr->ops->name) + 1;
137  ret = expr->ops->name;
138  break;
139  default:
140  ret = expr->ops->get(expr, type, data_len);
141  break;
142  }
143 
144  return ret;
145 }
146 
147 EXPORT_SYMBOL(nftnl_expr_get_u8);
148 uint8_t nftnl_expr_get_u8(const struct nftnl_expr *expr, uint16_t type)
149 {
150  const void *data;
151  uint32_t data_len;
152 
153  data = nftnl_expr_get(expr, type, &data_len);
154  if (data == NULL)
155  return 0;
156 
157  if (data_len != sizeof(uint8_t))
158  return 0;
159 
160  return *((uint8_t *)data);
161 }
162 
163 EXPORT_SYMBOL(nftnl_expr_get_u16);
164 uint16_t nftnl_expr_get_u16(const struct nftnl_expr *expr, uint16_t type)
165 {
166  const void *data;
167  uint32_t data_len;
168 
169  data = nftnl_expr_get(expr, type, &data_len);
170  if (data == NULL)
171  return 0;
172 
173  if (data_len != sizeof(uint16_t))
174  return 0;
175 
176  return *((uint16_t *)data);
177 }
178 
179 EXPORT_SYMBOL(nftnl_expr_get_u32);
180 uint32_t nftnl_expr_get_u32(const struct nftnl_expr *expr, uint16_t type)
181 {
182  const void *data;
183  uint32_t data_len;
184 
185  data = nftnl_expr_get(expr, type, &data_len);
186  if (data == NULL)
187  return 0;
188 
189  if (data_len != sizeof(uint32_t))
190  return 0;
191 
192  return *((uint32_t *)data);
193 }
194 
195 EXPORT_SYMBOL(nftnl_expr_get_u64);
196 uint64_t nftnl_expr_get_u64(const struct nftnl_expr *expr, uint16_t type)
197 {
198  const void *data;
199  uint32_t data_len;
200 
201  data = nftnl_expr_get(expr, type, &data_len);
202  if (data == NULL)
203  return 0;
204 
205  if (data_len != sizeof(uint64_t))
206  return 0;
207 
208  return *((uint64_t *)data);
209 }
210 
211 EXPORT_SYMBOL(nftnl_expr_get_str);
212 const char *nftnl_expr_get_str(const struct nftnl_expr *expr, uint16_t type)
213 {
214  uint32_t data_len;
215 
216  return (const char *)nftnl_expr_get(expr, type, &data_len);
217 }
218 
219 EXPORT_SYMBOL(nftnl_expr_build_payload);
220 void nftnl_expr_build_payload(struct nlmsghdr *nlh, struct nftnl_expr *expr)
221 {
222  struct nlattr *nest;
223 
224  mnl_attr_put_strz(nlh, NFTA_EXPR_NAME, expr->ops->name);
225 
226  if (!expr->ops->build)
227  return;
228 
229  nest = mnl_attr_nest_start(nlh, NFTA_EXPR_DATA);
230  expr->ops->build(nlh, expr);
231  mnl_attr_nest_end(nlh, nest);
232 }
233 
234 static int nftnl_rule_parse_expr_cb(const struct nlattr *attr, void *data)
235 {
236  const struct nlattr **tb = data;
237  int type = mnl_attr_get_type(attr);
238 
239  if (mnl_attr_type_valid(attr, NFTA_EXPR_MAX) < 0)
240  return MNL_CB_OK;
241 
242  switch (type) {
243  case NFTA_EXPR_NAME:
244  if (mnl_attr_validate(attr, MNL_TYPE_STRING) < 0)
245  abi_breakage();
246  break;
247  case NFTA_EXPR_DATA:
248  if (mnl_attr_validate(attr, MNL_TYPE_NESTED) < 0)
249  abi_breakage();
250  break;
251  }
252 
253  tb[type] = attr;
254  return MNL_CB_OK;
255 }
256 
257 struct nftnl_expr *nftnl_expr_parse(struct nlattr *attr)
258 {
259  struct nlattr *tb[NFTA_EXPR_MAX+1] = {};
260  struct nftnl_expr *expr;
261 
262  if (mnl_attr_parse_nested(attr, nftnl_rule_parse_expr_cb, tb) < 0)
263  goto err1;
264 
265  expr = nftnl_expr_alloc(mnl_attr_get_str(tb[NFTA_EXPR_NAME]));
266  if (expr == NULL)
267  goto err1;
268 
269  if (tb[NFTA_EXPR_DATA] &&
270  expr->ops->parse &&
271  expr->ops->parse(expr, tb[NFTA_EXPR_DATA]) < 0)
272  goto err2;
273 
274  return expr;
275 
276 err2:
277  xfree(expr);
278 err1:
279  return NULL;
280 }
281 
282 EXPORT_SYMBOL(nftnl_expr_snprintf);
283 int nftnl_expr_snprintf(char *buf, size_t remain, const struct nftnl_expr *expr,
284  uint32_t type, uint32_t flags)
285 {
286  int ret;
287  unsigned int offset = 0;
288 
289  if (remain)
290  buf[0] = '\0';
291 
292  if (!expr->ops->output || type != NFTNL_OUTPUT_DEFAULT)
293  return 0;
294 
295  ret = expr->ops->output(buf + offset, remain, flags, expr);
296  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
297 
298  return offset;
299 }
300 
301 static int nftnl_expr_do_snprintf(char *buf, size_t size, const void *e,
302  uint32_t cmd, uint32_t type, uint32_t flags)
303 {
304  return nftnl_expr_snprintf(buf, size, e, type, flags);
305 }
306 
307 EXPORT_SYMBOL(nftnl_expr_fprintf);
308 int nftnl_expr_fprintf(FILE *fp, const struct nftnl_expr *expr, uint32_t type,
309  uint32_t flags)
310 {
311  return nftnl_fprintf(fp, expr, NFTNL_CMD_UNSPEC, type, flags,
312  nftnl_expr_do_snprintf);
313 }