libnftnl 1.2.6
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
41static int
42nftnl_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
75static const void *
76nftnl_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
107static 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
135static void
136nftnl_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
156static int
157nftnl_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
197static 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
211static 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
222static 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
238static int
239nftnl_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 if (e->flags & (1 << NFTNL_EXPR_EXTHDR_SREG))
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 else if (exthdr->op == NFT_EXTHDR_OP_TCPOPT && exthdr->len == 0)
255 return snprintf(buf, len, "reset tcpopt %u ", exthdr->type);
256 else
257 return snprintf(buf, len, "op %u len %u type %u offset %u ",
258 exthdr->op, exthdr->len, exthdr->type, exthdr->offset);
259
260}
261
262struct expr_ops expr_ops_exthdr = {
263 .name = "exthdr",
264 .alloc_len = sizeof(struct nftnl_expr_exthdr),
265 .max_attr = NFTA_EXTHDR_MAX,
266 .set = nftnl_expr_exthdr_set,
267 .get = nftnl_expr_exthdr_get,
268 .parse = nftnl_expr_exthdr_parse,
269 .build = nftnl_expr_exthdr_build,
270 .output = nftnl_expr_exthdr_snprintf,
271};