libnftnl 1.2.6
bitwise.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 "internal.h"
13
14#include <stdio.h>
15#include <stdint.h>
16#include <string.h> /* for memcpy */
17#include <arpa/inet.h>
18#include <errno.h>
19#include <libmnl/libmnl.h>
20#include <linux/netfilter/nf_tables.h>
21#include <libnftnl/expr.h>
22#include <libnftnl/rule.h>
23
25 enum nft_registers sreg;
26 enum nft_registers dreg;
27 enum nft_bitwise_ops op;
28 unsigned int len;
29 union nftnl_data_reg mask;
30 union nftnl_data_reg xor;
31 union nftnl_data_reg data;
32};
33
34static int
35nftnl_expr_bitwise_set(struct nftnl_expr *e, uint16_t type,
36 const void *data, uint32_t data_len)
37{
38 struct nftnl_expr_bitwise *bitwise = nftnl_expr_data(e);
39
40 switch(type) {
41 case NFTNL_EXPR_BITWISE_SREG:
42 memcpy(&bitwise->sreg, data, sizeof(bitwise->sreg));
43 break;
44 case NFTNL_EXPR_BITWISE_DREG:
45 memcpy(&bitwise->dreg, data, sizeof(bitwise->dreg));
46 break;
47 case NFTNL_EXPR_BITWISE_OP:
48 memcpy(&bitwise->op, data, sizeof(bitwise->op));
49 break;
50 case NFTNL_EXPR_BITWISE_LEN:
51 memcpy(&bitwise->len, data, sizeof(bitwise->len));
52 break;
53 case NFTNL_EXPR_BITWISE_MASK:
54 memcpy(&bitwise->mask.val, data, data_len);
55 bitwise->mask.len = data_len;
56 break;
57 case NFTNL_EXPR_BITWISE_XOR:
58 memcpy(&bitwise->xor.val, data, data_len);
59 bitwise->xor.len = data_len;
60 break;
61 case NFTNL_EXPR_BITWISE_DATA:
62 memcpy(&bitwise->data.val, data, data_len);
63 bitwise->data.len = data_len;
64 break;
65 default:
66 return -1;
67 }
68 return 0;
69}
70
71static const void *
72nftnl_expr_bitwise_get(const struct nftnl_expr *e, uint16_t type,
73 uint32_t *data_len)
74{
75 struct nftnl_expr_bitwise *bitwise = nftnl_expr_data(e);
76
77 switch(type) {
78 case NFTNL_EXPR_BITWISE_SREG:
79 *data_len = sizeof(bitwise->sreg);
80 return &bitwise->sreg;
81 case NFTNL_EXPR_BITWISE_DREG:
82 *data_len = sizeof(bitwise->dreg);
83 return &bitwise->dreg;
84 case NFTNL_EXPR_BITWISE_OP:
85 *data_len = sizeof(bitwise->op);
86 return &bitwise->op;
87 case NFTNL_EXPR_BITWISE_LEN:
88 *data_len = sizeof(bitwise->len);
89 return &bitwise->len;
90 case NFTNL_EXPR_BITWISE_MASK:
91 *data_len = bitwise->mask.len;
92 return &bitwise->mask.val;
93 case NFTNL_EXPR_BITWISE_XOR:
94 *data_len = bitwise->xor.len;
95 return &bitwise->xor.val;
96 case NFTNL_EXPR_BITWISE_DATA:
97 *data_len = bitwise->data.len;
98 return &bitwise->data.val;
99 }
100 return NULL;
101}
102
103static int nftnl_expr_bitwise_cb(const struct nlattr *attr, void *data)
104{
105 const struct nlattr **tb = data;
106 int type = mnl_attr_get_type(attr);
107
108 if (mnl_attr_type_valid(attr, NFTA_BITWISE_MAX) < 0)
109 return MNL_CB_OK;
110
111 switch(type) {
112 case NFTA_BITWISE_SREG:
113 case NFTA_BITWISE_DREG:
114 case NFTA_BITWISE_OP:
115 case NFTA_BITWISE_LEN:
116 if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
117 abi_breakage();
118 break;
119 case NFTA_BITWISE_MASK:
120 case NFTA_BITWISE_XOR:
121 case NFTA_BITWISE_DATA:
122 if (mnl_attr_validate(attr, MNL_TYPE_BINARY) < 0)
123 abi_breakage();
124 break;
125 }
126
127 tb[type] = attr;
128 return MNL_CB_OK;
129}
130
131static void
132nftnl_expr_bitwise_build(struct nlmsghdr *nlh, const struct nftnl_expr *e)
133{
134 struct nftnl_expr_bitwise *bitwise = nftnl_expr_data(e);
135
136 if (e->flags & (1 << NFTNL_EXPR_BITWISE_SREG))
137 mnl_attr_put_u32(nlh, NFTA_BITWISE_SREG, htonl(bitwise->sreg));
138 if (e->flags & (1 << NFTNL_EXPR_BITWISE_DREG))
139 mnl_attr_put_u32(nlh, NFTA_BITWISE_DREG, htonl(bitwise->dreg));
140 if (e->flags & (1 << NFTNL_EXPR_BITWISE_OP))
141 mnl_attr_put_u32(nlh, NFTA_BITWISE_OP, htonl(bitwise->op));
142 if (e->flags & (1 << NFTNL_EXPR_BITWISE_LEN))
143 mnl_attr_put_u32(nlh, NFTA_BITWISE_LEN, htonl(bitwise->len));
144 if (e->flags & (1 << NFTNL_EXPR_BITWISE_MASK)) {
145 struct nlattr *nest;
146
147 nest = mnl_attr_nest_start(nlh, NFTA_BITWISE_MASK);
148 mnl_attr_put(nlh, NFTA_DATA_VALUE, bitwise->mask.len,
149 bitwise->mask.val);
150 mnl_attr_nest_end(nlh, nest);
151 }
152 if (e->flags & (1 << NFTNL_EXPR_BITWISE_XOR)) {
153 struct nlattr *nest;
154
155 nest = mnl_attr_nest_start(nlh, NFTA_BITWISE_XOR);
156 mnl_attr_put(nlh, NFTA_DATA_VALUE, bitwise->xor.len,
157 bitwise->xor.val);
158 mnl_attr_nest_end(nlh, nest);
159 }
160 if (e->flags & (1 << NFTNL_EXPR_BITWISE_DATA)) {
161 struct nlattr *nest;
162
163 nest = mnl_attr_nest_start(nlh, NFTA_BITWISE_DATA);
164 mnl_attr_put(nlh, NFTA_DATA_VALUE, bitwise->data.len,
165 bitwise->data.val);
166 mnl_attr_nest_end(nlh, nest);
167 }
168}
169
170static int
171nftnl_expr_bitwise_parse(struct nftnl_expr *e, struct nlattr *attr)
172{
173 struct nftnl_expr_bitwise *bitwise = nftnl_expr_data(e);
174 struct nlattr *tb[NFTA_BITWISE_MAX+1] = {};
175 int ret = 0;
176
177 if (mnl_attr_parse_nested(attr, nftnl_expr_bitwise_cb, tb) < 0)
178 return -1;
179
180 if (tb[NFTA_BITWISE_SREG]) {
181 bitwise->sreg = ntohl(mnl_attr_get_u32(tb[NFTA_BITWISE_SREG]));
182 e->flags |= (1 << NFTNL_EXPR_BITWISE_SREG);
183 }
184 if (tb[NFTA_BITWISE_DREG]) {
185 bitwise->dreg = ntohl(mnl_attr_get_u32(tb[NFTA_BITWISE_DREG]));
186 e->flags |= (1 << NFTNL_EXPR_BITWISE_DREG);
187 }
188 if (tb[NFTA_BITWISE_OP]) {
189 bitwise->op = ntohl(mnl_attr_get_u32(tb[NFTA_BITWISE_OP]));
190 e->flags |= (1 << NFTNL_EXPR_BITWISE_OP);
191 }
192 if (tb[NFTA_BITWISE_LEN]) {
193 bitwise->len = ntohl(mnl_attr_get_u32(tb[NFTA_BITWISE_LEN]));
194 e->flags |= (1 << NFTNL_EXPR_BITWISE_LEN);
195 }
196 if (tb[NFTA_BITWISE_MASK]) {
197 ret = nftnl_parse_data(&bitwise->mask, tb[NFTA_BITWISE_MASK], NULL);
198 e->flags |= (1 << NFTA_BITWISE_MASK);
199 }
200 if (tb[NFTA_BITWISE_XOR]) {
201 ret = nftnl_parse_data(&bitwise->xor, tb[NFTA_BITWISE_XOR], NULL);
202 e->flags |= (1 << NFTA_BITWISE_XOR);
203 }
204 if (tb[NFTA_BITWISE_DATA]) {
205 ret = nftnl_parse_data(&bitwise->data, tb[NFTA_BITWISE_DATA], NULL);
206 e->flags |= (1 << NFTNL_EXPR_BITWISE_DATA);
207 }
208
209 return ret;
210}
211
212static int
213nftnl_expr_bitwise_snprintf_bool(char *buf, size_t remain,
214 const struct nftnl_expr_bitwise *bitwise)
215{
216 int offset = 0, ret;
217
218 ret = snprintf(buf, remain, "reg %u = ( reg %u & ",
219 bitwise->dreg, bitwise->sreg);
220 SNPRINTF_BUFFER_SIZE(ret, remain, offset);
221
222 ret = nftnl_data_reg_snprintf(buf + offset, remain, &bitwise->mask,
223 0, DATA_VALUE);
224 SNPRINTF_BUFFER_SIZE(ret, remain, offset);
225
226 ret = snprintf(buf + offset, remain, ") ^ ");
227 SNPRINTF_BUFFER_SIZE(ret, remain, offset);
228
229 ret = nftnl_data_reg_snprintf(buf + offset, remain, &bitwise->xor,
230 0, DATA_VALUE);
231 SNPRINTF_BUFFER_SIZE(ret, remain, offset);
232
233 return offset;
234}
235
236static int
237nftnl_expr_bitwise_snprintf_shift(char *buf, size_t remain, const char *op,
238 const struct nftnl_expr_bitwise *bitwise)
239{ int offset = 0, ret;
240
241 ret = snprintf(buf, remain, "reg %u = ( reg %u %s ",
242 bitwise->dreg, bitwise->sreg, op);
243 SNPRINTF_BUFFER_SIZE(ret, remain, offset);
244
245 ret = nftnl_data_reg_snprintf(buf + offset, remain, &bitwise->data,
246 0, DATA_VALUE);
247 SNPRINTF_BUFFER_SIZE(ret, remain, offset);
248
249 ret = snprintf(buf + offset, remain, ") ");
250 SNPRINTF_BUFFER_SIZE(ret, remain, offset);
251
252 return offset;
253}
254
255static int
256nftnl_expr_bitwise_snprintf(char *buf, size_t size,
257 uint32_t flags, const struct nftnl_expr *e)
258{
259 struct nftnl_expr_bitwise *bitwise = nftnl_expr_data(e);
260 int err = -1;
261
262 switch (bitwise->op) {
263 case NFT_BITWISE_BOOL:
264 err = nftnl_expr_bitwise_snprintf_bool(buf, size, bitwise);
265 break;
266 case NFT_BITWISE_LSHIFT:
267 err = nftnl_expr_bitwise_snprintf_shift(buf, size, "<<", bitwise);
268 break;
269 case NFT_BITWISE_RSHIFT:
270 err = nftnl_expr_bitwise_snprintf_shift(buf, size, ">>", bitwise);
271 break;
272 }
273
274 return err;
275}
276
277struct expr_ops expr_ops_bitwise = {
278 .name = "bitwise",
279 .alloc_len = sizeof(struct nftnl_expr_bitwise),
280 .max_attr = NFTA_BITWISE_MAX,
281 .set = nftnl_expr_bitwise_set,
282 .get = nftnl_expr_bitwise_get,
283 .parse = nftnl_expr_bitwise_parse,
284 .build = nftnl_expr_bitwise_build,
285 .output = nftnl_expr_bitwise_snprintf,
286};