libnftnl  1.2.0
exthdr.c
1 /*
2  * (C) 2012-2013 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 "internal.h"
13 
14 #include <stdio.h>
15 #include <string.h>
16 #include <stdint.h>
17 #include <limits.h>
18 #include <arpa/inet.h>
19 #include <errno.h>
20 #include <libmnl/libmnl.h>
21 
22 #include <linux/netfilter/nf_tables.h>
23 
24 #include <libnftnl/expr.h>
25 #include <libnftnl/rule.h>
26 
27 #ifndef IPPROTO_MH
28 #define IPPROTO_MH 135
29 #endif
30 
32  enum nft_registers dreg;
33  enum nft_registers sreg;
34  uint32_t offset;
35  uint32_t len;
36  uint8_t type;
37  uint32_t op;
38  uint32_t flags;
39 };
40 
41 static int
42 nftnl_expr_exthdr_set(struct nftnl_expr *e, uint16_t type,
43  const void *data, uint32_t data_len)
44 {
45  struct nftnl_expr_exthdr *exthdr = nftnl_expr_data(e);
46 
47  switch(type) {
48  case NFTNL_EXPR_EXTHDR_DREG:
49  memcpy(&exthdr->dreg, data, sizeof(exthdr->dreg));
50  break;
51  case NFTNL_EXPR_EXTHDR_TYPE:
52  memcpy(&exthdr->type, data, sizeof(exthdr->type));
53  break;
54  case NFTNL_EXPR_EXTHDR_OFFSET:
55  memcpy(&exthdr->offset, data, sizeof(exthdr->offset));
56  break;
57  case NFTNL_EXPR_EXTHDR_LEN:
58  memcpy(&exthdr->len, data, sizeof(exthdr->len));
59  break;
60  case NFTNL_EXPR_EXTHDR_OP:
61  memcpy(&exthdr->op, data, sizeof(exthdr->op));
62  break;
63  case NFTNL_EXPR_EXTHDR_FLAGS:
64  memcpy(&exthdr->flags, data, sizeof(exthdr->flags));
65  break;
66  case NFTNL_EXPR_EXTHDR_SREG:
67  memcpy(&exthdr->sreg, data, sizeof(exthdr->sreg));
68  break;
69  default:
70  return -1;
71  }
72  return 0;
73 }
74 
75 static const void *
76 nftnl_expr_exthdr_get(const struct nftnl_expr *e, uint16_t type,
77  uint32_t *data_len)
78 {
79  struct nftnl_expr_exthdr *exthdr = nftnl_expr_data(e);
80 
81  switch(type) {
82  case NFTNL_EXPR_EXTHDR_DREG:
83  *data_len = sizeof(exthdr->dreg);
84  return &exthdr->dreg;
85  case NFTNL_EXPR_EXTHDR_TYPE:
86  *data_len = sizeof(exthdr->type);
87  return &exthdr->type;
88  case NFTNL_EXPR_EXTHDR_OFFSET:
89  *data_len = sizeof(exthdr->offset);
90  return &exthdr->offset;
91  case NFTNL_EXPR_EXTHDR_LEN:
92  *data_len = sizeof(exthdr->len);
93  return &exthdr->len;
94  case NFTNL_EXPR_EXTHDR_OP:
95  *data_len = sizeof(exthdr->op);
96  return &exthdr->op;
97  case NFTNL_EXPR_EXTHDR_FLAGS:
98  *data_len = sizeof(exthdr->flags);
99  return &exthdr->flags;
100  case NFTNL_EXPR_EXTHDR_SREG:
101  *data_len = sizeof(exthdr->sreg);
102  return &exthdr->sreg;
103  }
104  return NULL;
105 }
106 
107 static int nftnl_expr_exthdr_cb(const struct nlattr *attr, void *data)
108 {
109  const struct nlattr **tb = data;
110  int type = mnl_attr_get_type(attr);
111 
112  if (mnl_attr_type_valid(attr, NFTA_EXTHDR_MAX) < 0)
113  return MNL_CB_OK;
114 
115  switch(type) {
116  case NFTA_EXTHDR_TYPE:
117  if (mnl_attr_validate(attr, MNL_TYPE_U8) < 0)
118  abi_breakage();
119  break;
120  case NFTA_EXTHDR_DREG:
121  case NFTA_EXTHDR_SREG:
122  case NFTA_EXTHDR_OFFSET:
123  case NFTA_EXTHDR_LEN:
124  case NFTA_EXTHDR_OP:
125  case NFTA_EXTHDR_FLAGS:
126  if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
127  abi_breakage();
128  break;
129  }
130 
131  tb[type] = attr;
132  return MNL_CB_OK;
133 }
134 
135 static void
136 nftnl_expr_exthdr_build(struct nlmsghdr *nlh, const struct nftnl_expr *e)
137 {
138  struct nftnl_expr_exthdr *exthdr = nftnl_expr_data(e);
139 
140  if (e->flags & (1 << NFTNL_EXPR_EXTHDR_DREG))
141  mnl_attr_put_u32(nlh, NFTA_EXTHDR_DREG, htonl(exthdr->dreg));
142  if (e->flags & (1 << NFTNL_EXPR_EXTHDR_SREG))
143  mnl_attr_put_u32(nlh, NFTA_EXTHDR_SREG, htonl(exthdr->sreg));
144  if (e->flags & (1 << NFTNL_EXPR_EXTHDR_TYPE))
145  mnl_attr_put_u8(nlh, NFTA_EXTHDR_TYPE, exthdr->type);
146  if (e->flags & (1 << NFTNL_EXPR_EXTHDR_OFFSET))
147  mnl_attr_put_u32(nlh, NFTA_EXTHDR_OFFSET, htonl(exthdr->offset));
148  if (e->flags & (1 << NFTNL_EXPR_EXTHDR_LEN))
149  mnl_attr_put_u32(nlh, NFTA_EXTHDR_LEN, htonl(exthdr->len));
150  if (e->flags & (1 << NFTNL_EXPR_EXTHDR_OP))
151  mnl_attr_put_u32(nlh, NFTA_EXTHDR_OP, htonl(exthdr->op));
152  if (e->flags & (1 << NFTNL_EXPR_EXTHDR_FLAGS))
153  mnl_attr_put_u32(nlh, NFTA_EXTHDR_FLAGS, htonl(exthdr->flags));
154 }
155 
156 static int
157 nftnl_expr_exthdr_parse(struct nftnl_expr *e, struct nlattr *attr)
158 {
159  struct nftnl_expr_exthdr *exthdr = nftnl_expr_data(e);
160  struct nlattr *tb[NFTA_EXTHDR_MAX+1] = {};
161 
162  if (mnl_attr_parse_nested(attr, nftnl_expr_exthdr_cb, tb) < 0)
163  return -1;
164 
165  if (tb[NFTA_EXTHDR_DREG]) {
166  exthdr->dreg = ntohl(mnl_attr_get_u32(tb[NFTA_EXTHDR_DREG]));
167  e->flags |= (1 << NFTNL_EXPR_EXTHDR_DREG);
168  }
169  if (tb[NFTA_EXTHDR_SREG]) {
170  exthdr->sreg = ntohl(mnl_attr_get_u32(tb[NFTA_EXTHDR_SREG]));
171  e->flags |= (1 << NFTNL_EXPR_EXTHDR_SREG);
172  }
173  if (tb[NFTA_EXTHDR_TYPE]) {
174  exthdr->type = mnl_attr_get_u8(tb[NFTA_EXTHDR_TYPE]);
175  e->flags |= (1 << NFTNL_EXPR_EXTHDR_TYPE);
176  }
177  if (tb[NFTA_EXTHDR_OFFSET]) {
178  exthdr->offset = ntohl(mnl_attr_get_u32(tb[NFTA_EXTHDR_OFFSET]));
179  e->flags |= (1 << NFTNL_EXPR_EXTHDR_OFFSET);
180  }
181  if (tb[NFTA_EXTHDR_LEN]) {
182  exthdr->len = ntohl(mnl_attr_get_u32(tb[NFTA_EXTHDR_LEN]));
183  e->flags |= (1 << NFTNL_EXPR_EXTHDR_LEN);
184  }
185  if (tb[NFTA_EXTHDR_OP]) {
186  exthdr->op = ntohl(mnl_attr_get_u32(tb[NFTA_EXTHDR_OP]));
187  e->flags |= (1 << NFTNL_EXPR_EXTHDR_OP);
188  }
189  if (tb[NFTA_EXTHDR_FLAGS]) {
190  exthdr->flags = ntohl(mnl_attr_get_u32(tb[NFTA_EXTHDR_FLAGS]));
191  e->flags |= (1 << NFTNL_EXPR_EXTHDR_FLAGS);
192  }
193 
194  return 0;
195 }
196 
197 static const char *op2str(uint8_t op)
198 {
199  switch (op) {
200  case NFT_EXTHDR_OP_TCPOPT:
201  return " tcpopt";
202  case NFT_EXTHDR_OP_IPV6:
203  return " ipv6";
204  case NFT_EXTHDR_OP_IPV4:
205  return " ipv4";
206  default:
207  return "";
208  }
209 }
210 
211 static inline int str2exthdr_op(const char* str)
212 {
213  if (!strcmp(str, "tcpopt"))
214  return NFT_EXTHDR_OP_TCPOPT;
215  if (!strcmp(str, "ipv4"))
216  return NFT_EXTHDR_OP_IPV4;
217 
218  /* if str == "ipv6" or anything else */
219  return NFT_EXTHDR_OP_IPV6;
220 }
221 
222 static inline int str2exthdr_type(const char *str)
223 {
224  if (strcmp(str, "hopopts") == 0)
225  return IPPROTO_HOPOPTS;
226  else if (strcmp(str, "routing") == 0)
227  return IPPROTO_ROUTING;
228  else if (strcmp(str, "fragment") == 0)
229  return IPPROTO_FRAGMENT;
230  else if (strcmp(str, "dstopts") == 0)
231  return IPPROTO_DSTOPTS;
232  else if (strcmp(str, "mh") == 0)
233  return IPPROTO_MH;
234 
235  return -1;
236 }
237 
238 static int
239 nftnl_expr_exthdr_snprintf(char *buf, size_t len,
240  uint32_t flags, const struct nftnl_expr *e)
241 {
242  struct nftnl_expr_exthdr *exthdr = nftnl_expr_data(e);
243 
244  if (e->flags & (1 << NFTNL_EXPR_EXTHDR_DREG))
245  return snprintf(buf, len, "load%s %ub @ %u + %u%s => reg %u ",
246  op2str(exthdr->op), exthdr->len, exthdr->type,
247  exthdr->offset,
248  exthdr->flags & NFT_EXTHDR_F_PRESENT ? " present" : "",
249  exthdr->dreg);
250  else
251  return snprintf(buf, len, "write%s reg %u => %ub @ %u + %u ",
252  op2str(exthdr->op), exthdr->sreg, exthdr->len, exthdr->type,
253  exthdr->offset);
254 
255 }
256 
257 struct expr_ops expr_ops_exthdr = {
258  .name = "exthdr",
259  .alloc_len = sizeof(struct nftnl_expr_exthdr),
260  .max_attr = NFTA_EXTHDR_MAX,
261  .set = nftnl_expr_exthdr_set,
262  .get = nftnl_expr_exthdr_get,
263  .parse = nftnl_expr_exthdr_parse,
264  .build = nftnl_expr_exthdr_build,
265  .snprintf = nftnl_expr_exthdr_snprintf,
266 };