libnftnl  1.3.2
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 
19 struct nftnl_expr_immediate {
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, uint32_t byteorder)
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,
36  data_len, byteorder, NULL);
37  case NFTNL_EXPR_IMM_VERDICT:
38  memcpy(&imm->data.verdict, data, data_len);
39  break;
40  case NFTNL_EXPR_IMM_CHAIN:
41  if (e->flags & (1 << NFTNL_EXPR_IMM_CHAIN))
42  xfree(imm->data.chain);
43 
44  imm->data.chain = strdup(data);
45  if (!imm->data.chain)
46  return -1;
47  break;
48  case NFTNL_EXPR_IMM_CHAIN_ID:
49  memcpy(&imm->data.chain_id, data, data_len);
50  break;
51  }
52  return 0;
53 }
54 
55 static const void *
56 nftnl_expr_immediate_get(const struct nftnl_expr *e, uint16_t type,
57  uint32_t *data_len)
58 {
59  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
60 
61  switch(type) {
62  case NFTNL_EXPR_IMM_DREG:
63  *data_len = sizeof(imm->dreg);
64  return &imm->dreg;
65  case NFTNL_EXPR_IMM_DATA:
66  *data_len = imm->data.len;
67  return &imm->data.val;
68  case NFTNL_EXPR_IMM_VERDICT:
69  *data_len = sizeof(imm->data.verdict);
70  return &imm->data.verdict;
71  case NFTNL_EXPR_IMM_CHAIN:
72  *data_len = strlen(imm->data.chain)+1;
73  return imm->data.chain;
74  case NFTNL_EXPR_IMM_CHAIN_ID:
75  *data_len = sizeof(imm->data.chain_id);
76  return &imm->data.chain_id;
77  }
78  return NULL;
79 }
80 
81 static int nftnl_expr_immediate_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_IMMEDIATE_MAX) < 0)
87  return MNL_CB_OK;
88 
89  switch(type) {
90  case NFTA_IMMEDIATE_DREG:
91  if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
92  abi_breakage();
93  break;
94  case NFTA_IMMEDIATE_DATA:
95  if (mnl_attr_validate(attr, MNL_TYPE_BINARY) < 0)
96  abi_breakage();
97  break;
98  }
99 
100  tb[type] = attr;
101  return MNL_CB_OK;
102 }
103 
104 static void
105 nftnl_expr_immediate_build(struct nlmsghdr *nlh, const struct nftnl_expr *e)
106 {
107  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
108 
109  if (e->flags & (1 << NFTNL_EXPR_IMM_DREG))
110  mnl_attr_put_u32(nlh, NFTA_IMMEDIATE_DREG, htonl(imm->dreg));
111 
112  /* Sane configurations allows you to set ONLY one of these two below */
113  if (e->flags & (1 << NFTNL_EXPR_IMM_DATA)) {
114  struct nlattr *nest;
115 
116  nest = mnl_attr_nest_start(nlh, NFTA_IMMEDIATE_DATA);
117  mnl_attr_put(nlh, NFTA_DATA_VALUE, imm->data.len, imm->data.val);
118  mnl_attr_nest_end(nlh, nest);
119 
120  } else if (e->flags & (1 << NFTNL_EXPR_IMM_VERDICT)) {
121  struct nlattr *nest1, *nest2;
122 
123  nest1 = mnl_attr_nest_start(nlh, NFTA_IMMEDIATE_DATA);
124  nest2 = mnl_attr_nest_start(nlh, NFTA_DATA_VERDICT);
125  mnl_attr_put_u32(nlh, NFTA_VERDICT_CODE, htonl(imm->data.verdict));
126  if (e->flags & (1 << NFTNL_EXPR_IMM_CHAIN))
127  mnl_attr_put_strz(nlh, NFTA_VERDICT_CHAIN, imm->data.chain);
128  if (e->flags & (1 << NFTNL_EXPR_IMM_CHAIN_ID)) {
129  mnl_attr_put_u32(nlh, NFTA_VERDICT_CHAIN_ID,
130  htonl(imm->data.chain_id));
131  }
132 
133  mnl_attr_nest_end(nlh, nest1);
134  mnl_attr_nest_end(nlh, nest2);
135  }
136 }
137 
138 static int
139 nftnl_expr_immediate_parse(struct nftnl_expr *e, struct nlattr *attr)
140 {
141  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
142  struct nlattr *tb[NFTA_IMMEDIATE_MAX+1] = {};
143  int ret = 0;
144 
145  if (mnl_attr_parse_nested(attr, nftnl_expr_immediate_cb, tb) < 0)
146  return -1;
147 
148  if (tb[NFTA_IMMEDIATE_DREG]) {
149  imm->dreg = ntohl(mnl_attr_get_u32(tb[NFTA_IMMEDIATE_DREG]));
150  e->flags |= (1 << NFTNL_EXPR_IMM_DREG);
151  }
152  if (tb[NFTA_IMMEDIATE_DATA]) {
153  int type;
154 
155  ret = nftnl_parse_data(&imm->data, tb[NFTA_IMMEDIATE_DATA], &type);
156  if (ret < 0)
157  return ret;
158 
159  switch(type) {
160  case DATA_VALUE:
161  /* real immediate data to be loaded to destination */
162  e->flags |= (1 << NFTNL_EXPR_IMM_DATA);
163  break;
164  case DATA_VERDICT:
165  /* NF_ACCEPT, NF_DROP, NF_QUEUE and NFTNL_RETURN case */
166  e->flags |= (1 << NFTNL_EXPR_IMM_VERDICT);
167  break;
168  case DATA_CHAIN:
169  /* NFTNL_GOTO and NFTNL_JUMP case */
170  e->flags |= (1 << NFTNL_EXPR_IMM_VERDICT) |
171  (1 << NFTNL_EXPR_IMM_CHAIN);
172  break;
173  }
174  }
175 
176  return ret;
177 }
178 
179 static int
180 nftnl_expr_immediate_snprintf(char *buf, size_t remain,
181  uint32_t flags, const struct nftnl_expr *e)
182 {
183  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
184  int offset = 0, ret;
185 
186  ret = snprintf(buf, remain, "reg %u ", imm->dreg);
187  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
188 
189  if (e->flags & (1 << NFTNL_EXPR_IMM_DATA)) {
190  ret = nftnl_data_reg_snprintf(buf + offset, remain, &imm->data,
191  flags, DATA_VALUE);
192  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
193 
194  } else if (e->flags & (1 << NFTNL_EXPR_IMM_VERDICT)) {
195  ret = nftnl_data_reg_snprintf(buf + offset, remain, &imm->data,
196  flags, DATA_VERDICT);
197  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
198 
199  } else if (e->flags & (1 << NFTNL_EXPR_IMM_CHAIN)) {
200  ret = nftnl_data_reg_snprintf(buf + offset, remain, &imm->data,
201  flags, DATA_CHAIN);
202  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
203  }
204 
205  ret = snprintf(buf + offset, remain, " ");
206  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
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 };
nftnl_expr_immediate
Definition: immediate.c:19
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