libnftnl  1.2.3
data_reg.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 
12 #include <stdio.h>
13 #include <stdint.h>
14 #include <string.h>
15 #include <limits.h>
16 #include <arpa/inet.h>
17 #include <errno.h>
18 #include <netinet/in.h>
19 
20 #include <libmnl/libmnl.h>
21 #include <linux/netfilter.h>
22 #include <linux/netfilter/nf_tables.h>
23 #include <libnftnl/expr.h>
24 #include <libnftnl/rule.h>
25 #include "internal.h"
26 
27 static int
28 nftnl_data_reg_value_snprintf_default(char *buf, size_t remain,
29  const union nftnl_data_reg *reg,
30  uint32_t flags)
31 {
32  const char *pfx = flags & DATA_F_NOPFX ? "" : "0x";
33  int offset = 0, ret, i;
34 
35 
36 
37  for (i = 0; i < div_round_up(reg->len, sizeof(uint32_t)); i++) {
38  ret = snprintf(buf + offset, remain,
39  "%s%.8x ", pfx, reg->val[i]);
40  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
41  }
42 
43  return offset;
44 }
45 
46 static int
47 nftnl_data_reg_verdict_snprintf_def(char *buf, size_t size,
48  const union nftnl_data_reg *reg,
49  uint32_t flags)
50 {
51  int remain = size, offset = 0, ret = 0;
52 
53  ret = snprintf(buf, size, "%s ", nftnl_verdict2str(reg->verdict));
54  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
55 
56  if (reg->chain != NULL) {
57  ret = snprintf(buf + offset, remain, "-> %s ", reg->chain);
58  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
59  }
60 
61  return offset;
62 }
63 
64 int nftnl_data_reg_snprintf(char *buf, size_t size,
65  const union nftnl_data_reg *reg,
66  uint32_t flags, int reg_type)
67 {
68  switch(reg_type) {
69  case DATA_VALUE:
70  return nftnl_data_reg_value_snprintf_default(buf, size,
71  reg, flags);
72  case DATA_VERDICT:
73  case DATA_CHAIN:
74  return nftnl_data_reg_verdict_snprintf_def(buf, size,
75  reg, flags);
76  default:
77  return -1;
78  }
79 }
80 
81 static int nftnl_data_parse_cb(const struct nlattr *attr, void *data)
82 {
83  const struct nlattr **tb = data;
84  int type = mnl_attr_get_type(attr);
85 
86  if (mnl_attr_type_valid(attr, NFTA_DATA_MAX) < 0)
87  return MNL_CB_OK;
88 
89  switch(type) {
90  case NFTA_DATA_VALUE:
91  if (mnl_attr_validate(attr, MNL_TYPE_BINARY) < 0)
92  abi_breakage();
93  break;
94  case NFTA_DATA_VERDICT:
95  if (mnl_attr_validate(attr, MNL_TYPE_NESTED) < 0)
96  abi_breakage();
97  break;
98  }
99  tb[type] = attr;
100  return MNL_CB_OK;
101 }
102 
103 static int nftnl_verdict_parse_cb(const struct nlattr *attr, void *data)
104 {
105  const struct nlattr **tb = data;
106  int type = mnl_attr_get_type(attr);
107 
108  if (mnl_attr_type_valid(attr, NFTA_VERDICT_MAX) < 0)
109  return MNL_CB_OK;
110 
111  switch(type) {
112  case NFTA_VERDICT_CODE:
113  case NFTA_VERDICT_CHAIN_ID:
114  if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
115  abi_breakage();
116  break;
117  case NFTA_VERDICT_CHAIN:
118  if (mnl_attr_validate(attr, MNL_TYPE_STRING) < 0)
119  abi_breakage();
120  break;
121  }
122  tb[type] = attr;
123  return MNL_CB_OK;
124 }
125 
126 static int
127 nftnl_parse_verdict(union nftnl_data_reg *data, const struct nlattr *attr, int *type)
128 {
129  struct nlattr *tb[NFTA_VERDICT_MAX+1];
130 
131  if (mnl_attr_parse_nested(attr, nftnl_verdict_parse_cb, tb) < 0)
132  return -1;
133 
134  if (!tb[NFTA_VERDICT_CODE])
135  return -1;
136 
137  data->verdict = ntohl(mnl_attr_get_u32(tb[NFTA_VERDICT_CODE]));
138 
139  switch(data->verdict) {
140  case NF_ACCEPT:
141  case NF_DROP:
142  case NF_QUEUE:
143  case NFT_CONTINUE:
144  case NFT_BREAK:
145  case NFT_RETURN:
146  if (type)
147  *type = DATA_VERDICT;
148  data->len = sizeof(data->verdict);
149  break;
150  case NFT_JUMP:
151  case NFT_GOTO:
152  if (!tb[NFTA_VERDICT_CHAIN])
153  return -1;
154 
155  data->chain = strdup(mnl_attr_get_str(tb[NFTA_VERDICT_CHAIN]));
156  if (!data->chain)
157  return -1;
158 
159  if (type)
160  *type = DATA_CHAIN;
161  break;
162  default:
163  return -1;
164  }
165 
166  return 0;
167 }
168 
169 static int
170 __nftnl_parse_data(union nftnl_data_reg *data, const struct nlattr *attr)
171 {
172  void *orig = mnl_attr_get_payload(attr);
173  uint32_t data_len = mnl_attr_get_payload_len(attr);
174 
175  if (data_len == 0)
176  return -1;
177 
178  if (data_len > sizeof(data->val))
179  return -1;
180 
181  memcpy(data->val, orig, data_len);
182  data->len = data_len;
183 
184  return 0;
185 }
186 
187 int nftnl_parse_data(union nftnl_data_reg *data, struct nlattr *attr, int *type)
188 {
189  struct nlattr *tb[NFTA_DATA_MAX+1] = {};
190  int ret = 0;
191 
192  if (mnl_attr_parse_nested(attr, nftnl_data_parse_cb, tb) < 0)
193  return -1;
194 
195  if (tb[NFTA_DATA_VALUE]) {
196  if (type)
197  *type = DATA_VALUE;
198 
199  ret = __nftnl_parse_data(data, tb[NFTA_DATA_VALUE]);
200  if (ret < 0)
201  return ret;
202  }
203  if (tb[NFTA_DATA_VERDICT])
204  ret = nftnl_parse_verdict(data, tb[NFTA_DATA_VERDICT], type);
205 
206  return ret;
207 }
208 
209 void nftnl_free_verdict(const union nftnl_data_reg *data)
210 {
211  switch(data->verdict) {
212  case NFT_JUMP:
213  case NFT_GOTO:
214  xfree(data->chain);
215  break;
216  default:
217  break;
218  }
219 }