libnftnl  1.0.5
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 struct nftnl_expr *nftnl_expr_alloc(const char *name)
28 {
29  struct nftnl_expr *expr;
30  struct expr_ops *ops;
31 
32  ops = nftnl_expr_ops_lookup(name);
33  if (ops == NULL)
34  return NULL;
35 
36  expr = calloc(1, sizeof(struct nftnl_expr) + ops->alloc_len);
37  if (expr == NULL)
38  return NULL;
39 
40  /* Manually set expression name attribute */
41  expr->flags |= (1 << NFTNL_EXPR_NAME);
42  expr->ops = ops;
43 
44  return expr;
45 }
46 EXPORT_SYMBOL(nftnl_expr_alloc, nft_rule_expr_alloc);
47 
48 void nftnl_expr_free(struct nftnl_expr *expr)
49 {
50  if (expr->ops->free)
51  expr->ops->free(expr);
52 
53  xfree(expr);
54 }
55 EXPORT_SYMBOL(nftnl_expr_free, nft_rule_expr_free);
56 
57 bool nftnl_expr_is_set(const struct nftnl_expr *expr, uint16_t type)
58 {
59  return expr->flags & (1 << type);
60 }
61 EXPORT_SYMBOL(nftnl_expr_is_set, nft_rule_expr_is_set);
62 
63 void
64 nftnl_expr_set(struct nftnl_expr *expr, uint16_t type,
65  const void *data, uint32_t data_len)
66 {
67  switch(type) {
68  case NFTNL_EXPR_NAME: /* cannot be modified */
69  return;
70  default:
71  if (expr->ops->set(expr, type, data, data_len) < 0)
72  return;
73  }
74  expr->flags |= (1 << type);
75 }
76 EXPORT_SYMBOL(nftnl_expr_set, nft_rule_expr_set);
77 
78 void
79 nftnl_expr_set_u8(struct nftnl_expr *expr, uint16_t type, uint8_t data)
80 {
81  nftnl_expr_set(expr, type, &data, sizeof(uint8_t));
82 }
83 EXPORT_SYMBOL(nftnl_expr_set_u8, nft_rule_expr_set_u8);
84 
85 void
86 nftnl_expr_set_u16(struct nftnl_expr *expr, uint16_t type, uint16_t data)
87 {
88  nftnl_expr_set(expr, type, &data, sizeof(uint16_t));
89 }
90 EXPORT_SYMBOL(nftnl_expr_set_u16, nft_rule_expr_set_u16);
91 
92 void
93 nftnl_expr_set_u32(struct nftnl_expr *expr, uint16_t type, uint32_t data)
94 {
95  nftnl_expr_set(expr, type, &data, sizeof(uint32_t));
96 }
97 EXPORT_SYMBOL(nftnl_expr_set_u32, nft_rule_expr_set_u32);
98 
99 void
100 nftnl_expr_set_u64(struct nftnl_expr *expr, uint16_t type, uint64_t data)
101 {
102  nftnl_expr_set(expr, type, &data, sizeof(uint64_t));
103 }
104 EXPORT_SYMBOL(nftnl_expr_set_u64, nft_rule_expr_set_u64);
105 
106 void
107 nftnl_expr_set_str(struct nftnl_expr *expr, uint16_t type, const char *str)
108 {
109  nftnl_expr_set(expr, type, str, strlen(str)+1);
110 }
111 EXPORT_SYMBOL(nftnl_expr_set_str, nft_rule_expr_set_str);
112 
113 const void *nftnl_expr_get(const struct nftnl_expr *expr,
114  uint16_t type, uint32_t *data_len)
115 {
116  const void *ret;
117 
118  if (!(expr->flags & (1 << type)))
119  return NULL;
120 
121  switch(type) {
122  case NFTNL_EXPR_NAME:
123  ret = expr->ops->name;
124  break;
125  default:
126  ret = expr->ops->get(expr, type, data_len);
127  break;
128  }
129 
130  return ret;
131 }
132 EXPORT_SYMBOL(nftnl_expr_get, nft_rule_expr_get);
133 
134 uint8_t nftnl_expr_get_u8(const struct nftnl_expr *expr, uint16_t type)
135 {
136  const void *data;
137  uint32_t data_len;
138 
139  data = nftnl_expr_get(expr, type, &data_len);
140  if (data == NULL)
141  return 0;
142 
143  if (data_len != sizeof(uint8_t))
144  return 0;
145 
146  return *((uint8_t *)data);
147 }
148 EXPORT_SYMBOL(nftnl_expr_get_u8, nft_rule_expr_get_u8);
149 
150 uint16_t nftnl_expr_get_u16(const struct nftnl_expr *expr, uint16_t type)
151 {
152  const void *data;
153  uint32_t data_len;
154 
155  data = nftnl_expr_get(expr, type, &data_len);
156  if (data == NULL)
157  return 0;
158 
159  if (data_len != sizeof(uint16_t))
160  return 0;
161 
162  return *((uint16_t *)data);
163 }
164 EXPORT_SYMBOL(nftnl_expr_get_u16, nft_rule_expr_get_u16);
165 
166 uint32_t nftnl_expr_get_u32(const struct nftnl_expr *expr, uint16_t type)
167 {
168  const void *data;
169  uint32_t data_len;
170 
171  data = nftnl_expr_get(expr, type, &data_len);
172  if (data == NULL)
173  return 0;
174 
175  if (data_len != sizeof(uint32_t))
176  return 0;
177 
178  return *((uint32_t *)data);
179 }
180 EXPORT_SYMBOL(nftnl_expr_get_u32, nft_rule_expr_get_u32);
181 
182 uint64_t nftnl_expr_get_u64(const struct nftnl_expr *expr, uint16_t type)
183 {
184  const void *data;
185  uint32_t data_len;
186 
187  data = nftnl_expr_get(expr, type, &data_len);
188  if (data == NULL)
189  return 0;
190 
191  if (data_len != sizeof(uint64_t))
192  return 0;
193 
194  return *((uint64_t *)data);
195 }
196 EXPORT_SYMBOL(nftnl_expr_get_u64, nft_rule_expr_get_u64);
197 
198 const char *nftnl_expr_get_str(const struct nftnl_expr *expr, uint16_t type)
199 {
200  uint32_t data_len;
201 
202  return (const char *)nftnl_expr_get(expr, type, &data_len);
203 }
204 EXPORT_SYMBOL(nftnl_expr_get_str, nft_rule_expr_get_str);
205 
206 void
207 nftnl_expr_build_payload(struct nlmsghdr *nlh, struct nftnl_expr *expr)
208 {
209  struct nlattr *nest;
210 
211  mnl_attr_put_strz(nlh, NFTA_EXPR_NAME, expr->ops->name);
212 
213  nest = mnl_attr_nest_start(nlh, NFTA_EXPR_DATA);
214  expr->ops->build(nlh, expr);
215  mnl_attr_nest_end(nlh, nest);
216 }
217 
218 static int nftnl_rule_parse_expr_cb(const struct nlattr *attr, void *data)
219 {
220  const struct nlattr **tb = data;
221  int type = mnl_attr_get_type(attr);
222 
223  if (mnl_attr_type_valid(attr, NFTA_EXPR_MAX) < 0)
224  return MNL_CB_OK;
225 
226  switch (type) {
227  case NFTA_EXPR_NAME:
228  if (mnl_attr_validate(attr, MNL_TYPE_STRING) < 0)
229  abi_breakage();
230  break;
231  case NFTA_EXPR_DATA:
232  if (mnl_attr_validate(attr, MNL_TYPE_NESTED) < 0)
233  abi_breakage();
234  break;
235  }
236 
237  tb[type] = attr;
238  return MNL_CB_OK;
239 }
240 
241 struct nftnl_expr *nftnl_expr_parse(struct nlattr *attr)
242 {
243  struct nlattr *tb[NFTA_EXPR_MAX+1] = {};
244  struct nftnl_expr *expr;
245 
246  if (mnl_attr_parse_nested(attr, nftnl_rule_parse_expr_cb, tb) < 0)
247  goto err1;
248 
249  expr = nftnl_expr_alloc(mnl_attr_get_str(tb[NFTA_EXPR_NAME]));
250  if (expr == NULL)
251  goto err1;
252 
253  if (tb[NFTA_EXPR_DATA] &&
254  expr->ops->parse(expr, tb[NFTA_EXPR_DATA]) < 0)
255  goto err2;
256 
257  return expr;
258 
259 err2:
260  xfree(expr);
261 err1:
262  return NULL;
263 }
264 
265 int nftnl_expr_snprintf(char *buf, size_t size, struct nftnl_expr *expr,
266  uint32_t type, uint32_t flags)
267 {
268  int ret;
269  unsigned int offset = 0, len = size;
270 
271  ret = expr->ops->snprintf(buf+offset, len, type, flags, expr);
272  SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
273 
274  return offset;
275 }
276 EXPORT_SYMBOL(nftnl_expr_snprintf, nft_rule_expr_snprintf);