libnftnl  1.1.4
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, sizeof(imm->dreg));
37  break;
38  case NFTNL_EXPR_IMM_DATA:
39  memcpy(&imm->data.val, data, data_len);
40  imm->data.len = data_len;
41  break;
42  case NFTNL_EXPR_IMM_VERDICT:
43  memcpy(&imm->data.verdict, data, sizeof(imm->data.verdict));
44  break;
45  case NFTNL_EXPR_IMM_CHAIN:
46  if (e->flags & (1 << NFTNL_EXPR_IMM_CHAIN))
47  xfree(imm->data.chain);
48 
49  imm->data.chain = strdup(data);
50  if (!imm->data.chain)
51  return -1;
52  break;
53  default:
54  return -1;
55  }
56  return 0;
57 }
58 
59 static const void *
60 nftnl_expr_immediate_get(const struct nftnl_expr *e, uint16_t type,
61  uint32_t *data_len)
62 {
63  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
64 
65  switch(type) {
66  case NFTNL_EXPR_IMM_DREG:
67  *data_len = sizeof(imm->dreg);
68  return &imm->dreg;
69  case NFTNL_EXPR_IMM_DATA:
70  *data_len = imm->data.len;
71  return &imm->data.val;
72  case NFTNL_EXPR_IMM_VERDICT:
73  *data_len = sizeof(imm->data.verdict);
74  return &imm->data.verdict;
75  case NFTNL_EXPR_IMM_CHAIN:
76  *data_len = strlen(imm->data.chain)+1;
77  return imm->data.chain;
78  }
79  return NULL;
80 }
81 
82 static int nftnl_expr_immediate_cb(const struct nlattr *attr, void *data)
83 {
84  const struct nlattr **tb = data;
85  int type = mnl_attr_get_type(attr);
86 
87  if (mnl_attr_type_valid(attr, NFTA_IMMEDIATE_MAX) < 0)
88  return MNL_CB_OK;
89 
90  switch(type) {
91  case NFTA_IMMEDIATE_DREG:
92  if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
93  abi_breakage();
94  break;
95  case NFTA_IMMEDIATE_DATA:
96  if (mnl_attr_validate(attr, MNL_TYPE_BINARY) < 0)
97  abi_breakage();
98  break;
99  }
100 
101  tb[type] = attr;
102  return MNL_CB_OK;
103 }
104 
105 static void
106 nftnl_expr_immediate_build(struct nlmsghdr *nlh, const struct nftnl_expr *e)
107 {
108  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
109 
110  if (e->flags & (1 << NFTNL_EXPR_IMM_DREG))
111  mnl_attr_put_u32(nlh, NFTA_IMMEDIATE_DREG, htonl(imm->dreg));
112 
113  /* Sane configurations allows you to set ONLY one of these two below */
114  if (e->flags & (1 << NFTNL_EXPR_IMM_DATA)) {
115  struct nlattr *nest;
116 
117  nest = mnl_attr_nest_start(nlh, NFTA_IMMEDIATE_DATA);
118  mnl_attr_put(nlh, NFTA_DATA_VALUE, imm->data.len, imm->data.val);
119  mnl_attr_nest_end(nlh, nest);
120 
121  } else if (e->flags & (1 << NFTNL_EXPR_IMM_VERDICT)) {
122  struct nlattr *nest1, *nest2;
123 
124  nest1 = mnl_attr_nest_start(nlh, NFTA_IMMEDIATE_DATA);
125  nest2 = mnl_attr_nest_start(nlh, NFTA_DATA_VERDICT);
126  mnl_attr_put_u32(nlh, NFTA_VERDICT_CODE, htonl(imm->data.verdict));
127  if (e->flags & (1 << NFTNL_EXPR_IMM_CHAIN))
128  mnl_attr_put_strz(nlh, NFTA_VERDICT_CHAIN, imm->data.chain);
129 
130  mnl_attr_nest_end(nlh, nest1);
131  mnl_attr_nest_end(nlh, nest2);
132  }
133 }
134 
135 static int
136 nftnl_expr_immediate_parse(struct nftnl_expr *e, struct nlattr *attr)
137 {
138  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
139  struct nlattr *tb[NFTA_IMMEDIATE_MAX+1] = {};
140  int ret = 0;
141 
142  if (mnl_attr_parse_nested(attr, nftnl_expr_immediate_cb, tb) < 0)
143  return -1;
144 
145  if (tb[NFTA_IMMEDIATE_DREG]) {
146  imm->dreg = ntohl(mnl_attr_get_u32(tb[NFTA_IMMEDIATE_DREG]));
147  e->flags |= (1 << NFTNL_EXPR_IMM_DREG);
148  }
149  if (tb[NFTA_IMMEDIATE_DATA]) {
150  int type;
151 
152  ret = nftnl_parse_data(&imm->data, tb[NFTA_IMMEDIATE_DATA], &type);
153  if (ret < 0)
154  return ret;
155 
156  switch(type) {
157  case DATA_VALUE:
158  /* real immediate data to be loaded to destination */
159  e->flags |= (1 << NFTNL_EXPR_IMM_DATA);
160  break;
161  case DATA_VERDICT:
162  /* NF_ACCEPT, NF_DROP, NF_QUEUE and NFTNL_RETURN case */
163  e->flags |= (1 << NFTNL_EXPR_IMM_VERDICT);
164  break;
165  case DATA_CHAIN:
166  /* NFTNL_GOTO and NFTNL_JUMP case */
167  e->flags |= (1 << NFTNL_EXPR_IMM_VERDICT) |
168  (1 << NFTNL_EXPR_IMM_CHAIN);
169  break;
170  }
171  }
172 
173  return ret;
174 }
175 
176 static int
177 nftnl_expr_immediate_snprintf_default(char *buf, size_t len,
178  const struct nftnl_expr *e,
179  uint32_t flags)
180 {
181  int remain = len, offset = 0, ret;
182  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
183 
184  ret = snprintf(buf, remain, "reg %u ", imm->dreg);
185  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
186 
187  if (e->flags & (1 << NFTNL_EXPR_IMM_DATA)) {
188  ret = nftnl_data_reg_snprintf(buf + offset, remain, &imm->data,
189  NFTNL_OUTPUT_DEFAULT, flags, DATA_VALUE);
190  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
191 
192  } else if (e->flags & (1 << NFTNL_EXPR_IMM_VERDICT)) {
193  ret = nftnl_data_reg_snprintf(buf + offset, remain, &imm->data,
194  NFTNL_OUTPUT_DEFAULT, flags, DATA_VERDICT);
195  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
196 
197  } else if (e->flags & (1 << NFTNL_EXPR_IMM_CHAIN)) {
198  ret = nftnl_data_reg_snprintf(buf + offset, remain, &imm->data,
199  NFTNL_OUTPUT_DEFAULT, flags, DATA_CHAIN);
200  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
201  }
202 
203  return offset;
204 }
205 
206 static int
207 nftnl_expr_immediate_snprintf(char *buf, size_t len, uint32_t type,
208  uint32_t flags, const struct nftnl_expr *e)
209 {
210  switch(type) {
211  case NFTNL_OUTPUT_DEFAULT:
212  return nftnl_expr_immediate_snprintf_default(buf, len, e, flags);
213  case NFTNL_OUTPUT_XML:
214  case NFTNL_OUTPUT_JSON:
215  default:
216  break;
217  }
218  return -1;
219 }
220 
221 static void nftnl_expr_immediate_free(const struct nftnl_expr *e)
222 {
223  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
224 
225  if (e->flags & (1 << NFTNL_EXPR_IMM_VERDICT))
226  nftnl_free_verdict(&imm->data);
227 }
228 
229 struct expr_ops expr_ops_immediate = {
230  .name = "immediate",
231  .alloc_len = sizeof(struct nftnl_expr_immediate),
232  .max_attr = NFTA_IMMEDIATE_MAX,
233  .free = nftnl_expr_immediate_free,
234  .set = nftnl_expr_immediate_set,
235  .get = nftnl_expr_immediate_get,
236  .parse = nftnl_expr_immediate_parse,
237  .build = nftnl_expr_immediate_build,
238  .snprintf = nftnl_expr_immediate_snprintf,
239 };