libnftnl  1.2.8
immediate.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 <arpa/inet.h>
16 #include <errno.h>
17 #include "internal.h"
18 #include <libmnl/libmnl.h>
19 #include <linux/netfilter/nf_tables.h>
20 #include <libnftnl/expr.h>
21 #include <libnftnl/rule.h>
22 
24  union nftnl_data_reg data;
25  enum nft_registers dreg;
26 };
27 
28 static int
29 nftnl_expr_immediate_set(struct nftnl_expr *e, uint16_t type,
30  const void *data, uint32_t data_len)
31 {
32  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
33 
34  switch(type) {
35  case NFTNL_EXPR_IMM_DREG:
36  memcpy(&imm->dreg, data, data_len);
37  break;
38  case NFTNL_EXPR_IMM_DATA:
39  return nftnl_data_cpy(&imm->data, data, data_len);
40  case NFTNL_EXPR_IMM_VERDICT:
41  memcpy(&imm->data.verdict, data, data_len);
42  break;
43  case NFTNL_EXPR_IMM_CHAIN:
44  if (e->flags & (1 << NFTNL_EXPR_IMM_CHAIN))
45  xfree(imm->data.chain);
46 
47  imm->data.chain = strdup(data);
48  if (!imm->data.chain)
49  return -1;
50  break;
51  case NFTNL_EXPR_IMM_CHAIN_ID:
52  memcpy(&imm->data.chain_id, data, data_len);
53  break;
54  }
55  return 0;
56 }
57 
58 static const void *
59 nftnl_expr_immediate_get(const struct nftnl_expr *e, uint16_t type,
60  uint32_t *data_len)
61 {
62  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
63 
64  switch(type) {
65  case NFTNL_EXPR_IMM_DREG:
66  *data_len = sizeof(imm->dreg);
67  return &imm->dreg;
68  case NFTNL_EXPR_IMM_DATA:
69  *data_len = imm->data.len;
70  return &imm->data.val;
71  case NFTNL_EXPR_IMM_VERDICT:
72  *data_len = sizeof(imm->data.verdict);
73  return &imm->data.verdict;
74  case NFTNL_EXPR_IMM_CHAIN:
75  *data_len = strlen(imm->data.chain)+1;
76  return imm->data.chain;
77  case NFTNL_EXPR_IMM_CHAIN_ID:
78  *data_len = sizeof(imm->data.chain_id);
79  return &imm->data.chain_id;
80  }
81  return NULL;
82 }
83 
84 static int nftnl_expr_immediate_cb(const struct nlattr *attr, void *data)
85 {
86  const struct nlattr **tb = data;
87  int type = mnl_attr_get_type(attr);
88 
89  if (mnl_attr_type_valid(attr, NFTA_IMMEDIATE_MAX) < 0)
90  return MNL_CB_OK;
91 
92  switch(type) {
93  case NFTA_IMMEDIATE_DREG:
94  if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
95  abi_breakage();
96  break;
97  case NFTA_IMMEDIATE_DATA:
98  if (mnl_attr_validate(attr, MNL_TYPE_BINARY) < 0)
99  abi_breakage();
100  break;
101  }
102 
103  tb[type] = attr;
104  return MNL_CB_OK;
105 }
106 
107 static void
108 nftnl_expr_immediate_build(struct nlmsghdr *nlh, const struct nftnl_expr *e)
109 {
110  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
111 
112  if (e->flags & (1 << NFTNL_EXPR_IMM_DREG))
113  mnl_attr_put_u32(nlh, NFTA_IMMEDIATE_DREG, htonl(imm->dreg));
114 
115  /* Sane configurations allows you to set ONLY one of these two below */
116  if (e->flags & (1 << NFTNL_EXPR_IMM_DATA)) {
117  struct nlattr *nest;
118 
119  nest = mnl_attr_nest_start(nlh, NFTA_IMMEDIATE_DATA);
120  mnl_attr_put(nlh, NFTA_DATA_VALUE, imm->data.len, imm->data.val);
121  mnl_attr_nest_end(nlh, nest);
122 
123  } else if (e->flags & (1 << NFTNL_EXPR_IMM_VERDICT)) {
124  struct nlattr *nest1, *nest2;
125 
126  nest1 = mnl_attr_nest_start(nlh, NFTA_IMMEDIATE_DATA);
127  nest2 = mnl_attr_nest_start(nlh, NFTA_DATA_VERDICT);
128  mnl_attr_put_u32(nlh, NFTA_VERDICT_CODE, htonl(imm->data.verdict));
129  if (e->flags & (1 << NFTNL_EXPR_IMM_CHAIN))
130  mnl_attr_put_strz(nlh, NFTA_VERDICT_CHAIN, imm->data.chain);
131  if (e->flags & (1 << NFTNL_EXPR_IMM_CHAIN_ID)) {
132  mnl_attr_put_u32(nlh, NFTA_VERDICT_CHAIN_ID,
133  htonl(imm->data.chain_id));
134  }
135 
136  mnl_attr_nest_end(nlh, nest1);
137  mnl_attr_nest_end(nlh, nest2);
138  }
139 }
140 
141 static int
142 nftnl_expr_immediate_parse(struct nftnl_expr *e, struct nlattr *attr)
143 {
144  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
145  struct nlattr *tb[NFTA_IMMEDIATE_MAX+1] = {};
146  int ret = 0;
147 
148  if (mnl_attr_parse_nested(attr, nftnl_expr_immediate_cb, tb) < 0)
149  return -1;
150 
151  if (tb[NFTA_IMMEDIATE_DREG]) {
152  imm->dreg = ntohl(mnl_attr_get_u32(tb[NFTA_IMMEDIATE_DREG]));
153  e->flags |= (1 << NFTNL_EXPR_IMM_DREG);
154  }
155  if (tb[NFTA_IMMEDIATE_DATA]) {
156  int type;
157 
158  ret = nftnl_parse_data(&imm->data, tb[NFTA_IMMEDIATE_DATA], &type);
159  if (ret < 0)
160  return ret;
161 
162  switch(type) {
163  case DATA_VALUE:
164  /* real immediate data to be loaded to destination */
165  e->flags |= (1 << NFTNL_EXPR_IMM_DATA);
166  break;
167  case DATA_VERDICT:
168  /* NF_ACCEPT, NF_DROP, NF_QUEUE and NFTNL_RETURN case */
169  e->flags |= (1 << NFTNL_EXPR_IMM_VERDICT);
170  break;
171  case DATA_CHAIN:
172  /* NFTNL_GOTO and NFTNL_JUMP case */
173  e->flags |= (1 << NFTNL_EXPR_IMM_VERDICT) |
174  (1 << NFTNL_EXPR_IMM_CHAIN);
175  break;
176  }
177  }
178 
179  return ret;
180 }
181 
182 static int
183 nftnl_expr_immediate_snprintf(char *buf, size_t remain,
184  uint32_t flags, const struct nftnl_expr *e)
185 {
186  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
187  int offset = 0, ret;
188 
189  ret = snprintf(buf, remain, "reg %u ", imm->dreg);
190  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
191 
192  if (e->flags & (1 << NFTNL_EXPR_IMM_DATA)) {
193  ret = nftnl_data_reg_snprintf(buf + offset, remain, &imm->data,
194  flags, DATA_VALUE);
195  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
196 
197  } else if (e->flags & (1 << NFTNL_EXPR_IMM_VERDICT)) {
198  ret = nftnl_data_reg_snprintf(buf + offset, remain, &imm->data,
199  flags, DATA_VERDICT);
200  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
201 
202  } else if (e->flags & (1 << NFTNL_EXPR_IMM_CHAIN)) {
203  ret = nftnl_data_reg_snprintf(buf + offset, remain, &imm->data,
204  flags, DATA_CHAIN);
205  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
206  }
207 
208  return offset;
209 }
210 
211 static void nftnl_expr_immediate_free(const struct nftnl_expr *e)
212 {
213  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
214 
215  if (e->flags & (1 << NFTNL_EXPR_IMM_CHAIN))
216  xfree(imm->data.chain);
217 }
218 
219 static struct attr_policy immediate_attr_policy[__NFTNL_EXPR_IMM_MAX] = {
220  [NFTNL_EXPR_IMM_DREG] = { .maxlen = sizeof(uint32_t) },
221  [NFTNL_EXPR_IMM_DATA] = { .maxlen = NFT_DATA_VALUE_MAXLEN },
222  [NFTNL_EXPR_IMM_VERDICT] = { .maxlen = sizeof(uint32_t) },
223  [NFTNL_EXPR_IMM_CHAIN] = { .maxlen = NFT_CHAIN_MAXNAMELEN },
224  [NFTNL_EXPR_IMM_CHAIN_ID] = { .maxlen = sizeof(uint32_t) },
225 };
226 
227 struct expr_ops expr_ops_immediate = {
228  .name = "immediate",
229  .alloc_len = sizeof(struct nftnl_expr_immediate),
230  .nftnl_max_attr = __NFTNL_EXPR_IMM_MAX - 1,
231  .attr_policy = immediate_attr_policy,
232  .free = nftnl_expr_immediate_free,
233  .set = nftnl_expr_immediate_set,
234  .get = nftnl_expr_immediate_get,
235  .parse = nftnl_expr_immediate_parse,
236  .build = nftnl_expr_immediate_build,
237  .output = nftnl_expr_immediate_snprintf,
238 };