libnftnl  1.2.9
immediate.c
1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3  * (C) 2012 by Pablo Neira Ayuso <pablo@netfilter.org>
4  *
5  * This code has been sponsored by Sophos Astaro <http://www.sophos.com>
6  */
7 
8 #include <stdio.h>
9 #include <stdint.h>
10 #include <string.h>
11 #include <arpa/inet.h>
12 #include <errno.h>
13 #include "internal.h"
14 #include <libmnl/libmnl.h>
15 #include <linux/netfilter/nf_tables.h>
16 #include <libnftnl/expr.h>
17 #include <libnftnl/rule.h>
18 
20  union nftnl_data_reg data;
21  enum nft_registers dreg;
22 };
23 
24 static int
25 nftnl_expr_immediate_set(struct nftnl_expr *e, uint16_t type,
26  const void *data, uint32_t data_len)
27 {
28  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
29 
30  switch(type) {
31  case NFTNL_EXPR_IMM_DREG:
32  memcpy(&imm->dreg, data, data_len);
33  break;
34  case NFTNL_EXPR_IMM_DATA:
35  return nftnl_data_cpy(&imm->data, data, data_len);
36  case NFTNL_EXPR_IMM_VERDICT:
37  memcpy(&imm->data.verdict, data, data_len);
38  break;
39  case NFTNL_EXPR_IMM_CHAIN:
40  if (e->flags & (1 << NFTNL_EXPR_IMM_CHAIN))
41  xfree(imm->data.chain);
42 
43  imm->data.chain = strdup(data);
44  if (!imm->data.chain)
45  return -1;
46  break;
47  case NFTNL_EXPR_IMM_CHAIN_ID:
48  memcpy(&imm->data.chain_id, data, data_len);
49  break;
50  }
51  return 0;
52 }
53 
54 static const void *
55 nftnl_expr_immediate_get(const struct nftnl_expr *e, uint16_t type,
56  uint32_t *data_len)
57 {
58  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
59 
60  switch(type) {
61  case NFTNL_EXPR_IMM_DREG:
62  *data_len = sizeof(imm->dreg);
63  return &imm->dreg;
64  case NFTNL_EXPR_IMM_DATA:
65  *data_len = imm->data.len;
66  return &imm->data.val;
67  case NFTNL_EXPR_IMM_VERDICT:
68  *data_len = sizeof(imm->data.verdict);
69  return &imm->data.verdict;
70  case NFTNL_EXPR_IMM_CHAIN:
71  *data_len = strlen(imm->data.chain)+1;
72  return imm->data.chain;
73  case NFTNL_EXPR_IMM_CHAIN_ID:
74  *data_len = sizeof(imm->data.chain_id);
75  return &imm->data.chain_id;
76  }
77  return NULL;
78 }
79 
80 static int nftnl_expr_immediate_cb(const struct nlattr *attr, void *data)
81 {
82  const struct nlattr **tb = data;
83  int type = mnl_attr_get_type(attr);
84 
85  if (mnl_attr_type_valid(attr, NFTA_IMMEDIATE_MAX) < 0)
86  return MNL_CB_OK;
87 
88  switch(type) {
89  case NFTA_IMMEDIATE_DREG:
90  if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
91  abi_breakage();
92  break;
93  case NFTA_IMMEDIATE_DATA:
94  if (mnl_attr_validate(attr, MNL_TYPE_BINARY) < 0)
95  abi_breakage();
96  break;
97  }
98 
99  tb[type] = attr;
100  return MNL_CB_OK;
101 }
102 
103 static void
104 nftnl_expr_immediate_build(struct nlmsghdr *nlh, const struct nftnl_expr *e)
105 {
106  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
107 
108  if (e->flags & (1 << NFTNL_EXPR_IMM_DREG))
109  mnl_attr_put_u32(nlh, NFTA_IMMEDIATE_DREG, htonl(imm->dreg));
110 
111  /* Sane configurations allows you to set ONLY one of these two below */
112  if (e->flags & (1 << NFTNL_EXPR_IMM_DATA)) {
113  struct nlattr *nest;
114 
115  nest = mnl_attr_nest_start(nlh, NFTA_IMMEDIATE_DATA);
116  mnl_attr_put(nlh, NFTA_DATA_VALUE, imm->data.len, imm->data.val);
117  mnl_attr_nest_end(nlh, nest);
118 
119  } else if (e->flags & (1 << NFTNL_EXPR_IMM_VERDICT)) {
120  struct nlattr *nest1, *nest2;
121 
122  nest1 = mnl_attr_nest_start(nlh, NFTA_IMMEDIATE_DATA);
123  nest2 = mnl_attr_nest_start(nlh, NFTA_DATA_VERDICT);
124  mnl_attr_put_u32(nlh, NFTA_VERDICT_CODE, htonl(imm->data.verdict));
125  if (e->flags & (1 << NFTNL_EXPR_IMM_CHAIN))
126  mnl_attr_put_strz(nlh, NFTA_VERDICT_CHAIN, imm->data.chain);
127  if (e->flags & (1 << NFTNL_EXPR_IMM_CHAIN_ID)) {
128  mnl_attr_put_u32(nlh, NFTA_VERDICT_CHAIN_ID,
129  htonl(imm->data.chain_id));
130  }
131 
132  mnl_attr_nest_end(nlh, nest1);
133  mnl_attr_nest_end(nlh, nest2);
134  }
135 }
136 
137 static int
138 nftnl_expr_immediate_parse(struct nftnl_expr *e, struct nlattr *attr)
139 {
140  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
141  struct nlattr *tb[NFTA_IMMEDIATE_MAX+1] = {};
142  int ret = 0;
143 
144  if (mnl_attr_parse_nested(attr, nftnl_expr_immediate_cb, tb) < 0)
145  return -1;
146 
147  if (tb[NFTA_IMMEDIATE_DREG]) {
148  imm->dreg = ntohl(mnl_attr_get_u32(tb[NFTA_IMMEDIATE_DREG]));
149  e->flags |= (1 << NFTNL_EXPR_IMM_DREG);
150  }
151  if (tb[NFTA_IMMEDIATE_DATA]) {
152  int type;
153 
154  ret = nftnl_parse_data(&imm->data, tb[NFTA_IMMEDIATE_DATA], &type);
155  if (ret < 0)
156  return ret;
157 
158  switch(type) {
159  case DATA_VALUE:
160  /* real immediate data to be loaded to destination */
161  e->flags |= (1 << NFTNL_EXPR_IMM_DATA);
162  break;
163  case DATA_VERDICT:
164  /* NF_ACCEPT, NF_DROP, NF_QUEUE and NFTNL_RETURN case */
165  e->flags |= (1 << NFTNL_EXPR_IMM_VERDICT);
166  break;
167  case DATA_CHAIN:
168  /* NFTNL_GOTO and NFTNL_JUMP case */
169  e->flags |= (1 << NFTNL_EXPR_IMM_VERDICT) |
170  (1 << NFTNL_EXPR_IMM_CHAIN);
171  break;
172  }
173  }
174 
175  return ret;
176 }
177 
178 static int
179 nftnl_expr_immediate_snprintf(char *buf, size_t remain,
180  uint32_t flags, const struct nftnl_expr *e)
181 {
182  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
183  int offset = 0, ret;
184 
185  ret = snprintf(buf, remain, "reg %u ", imm->dreg);
186  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
187 
188  if (e->flags & (1 << NFTNL_EXPR_IMM_DATA)) {
189  ret = nftnl_data_reg_snprintf(buf + offset, remain, &imm->data,
190  flags, DATA_VALUE);
191  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
192 
193  } else if (e->flags & (1 << NFTNL_EXPR_IMM_VERDICT)) {
194  ret = nftnl_data_reg_snprintf(buf + offset, remain, &imm->data,
195  flags, DATA_VERDICT);
196  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
197 
198  } else if (e->flags & (1 << NFTNL_EXPR_IMM_CHAIN)) {
199  ret = nftnl_data_reg_snprintf(buf + offset, remain, &imm->data,
200  flags, DATA_CHAIN);
201  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
202  }
203 
204  return offset;
205 }
206 
207 static void nftnl_expr_immediate_free(const struct nftnl_expr *e)
208 {
209  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
210 
211  if (e->flags & (1 << NFTNL_EXPR_IMM_CHAIN))
212  xfree(imm->data.chain);
213 }
214 
215 static struct attr_policy immediate_attr_policy[__NFTNL_EXPR_IMM_MAX] = {
216  [NFTNL_EXPR_IMM_DREG] = { .maxlen = sizeof(uint32_t) },
217  [NFTNL_EXPR_IMM_DATA] = { .maxlen = NFT_DATA_VALUE_MAXLEN },
218  [NFTNL_EXPR_IMM_VERDICT] = { .maxlen = sizeof(uint32_t) },
219  [NFTNL_EXPR_IMM_CHAIN] = { .maxlen = NFT_CHAIN_MAXNAMELEN },
220  [NFTNL_EXPR_IMM_CHAIN_ID] = { .maxlen = sizeof(uint32_t) },
221 };
222 
223 struct expr_ops expr_ops_immediate = {
224  .name = "immediate",
225  .alloc_len = sizeof(struct nftnl_expr_immediate),
226  .nftnl_max_attr = __NFTNL_EXPR_IMM_MAX - 1,
227  .attr_policy = immediate_attr_policy,
228  .free = nftnl_expr_immediate_free,
229  .set = nftnl_expr_immediate_set,
230  .get = nftnl_expr_immediate_get,
231  .parse = nftnl_expr_immediate_parse,
232  .build = nftnl_expr_immediate_build,
233  .output = nftnl_expr_immediate_snprintf,
234 };