1 /*
2 * m_nat.c NAT module
3 *
4 * This program is free software; you can distribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version
7 * 2 of the License, or (at your option) any later version.
8 *
9 * Authors: Herbert Xu <herbert@gondor.apana.org.au>
10 *
11 */
12
13 #include <stdio.h>
14 #include <stdlib.h>
15 #include <unistd.h>
16 #include <syslog.h>
17 #include <fcntl.h>
18 #include <sys/socket.h>
19 #include <netinet/in.h>
20 #include <arpa/inet.h>
21 #include <string.h>
22 #include "utils.h"
23 #include "tc_util.h"
24 #include <linux/tc_act/tc_nat.h>
25
26 static void
explain(void)27 explain(void)
28 {
29 fprintf(stderr, "Usage: ... nat NAT\n"
30 "NAT := DIRECTION OLD NEW\n"
31 "DIRECTION := { ingress | egress }\n"
32 "OLD := PREFIX\n"
33 "NEW := ADDRESS\n");
34 }
35
36 static void
usage(void)37 usage(void)
38 {
39 explain();
40 exit(-1);
41 }
42
43 static int
parse_nat_args(int * argc_p,char *** argv_p,struct tc_nat * sel)44 parse_nat_args(int *argc_p, char ***argv_p,struct tc_nat *sel)
45 {
46 int argc = *argc_p;
47 char **argv = *argv_p;
48 inet_prefix addr;
49
50 if (argc <= 0)
51 return -1;
52
53 if (matches(*argv, "egress") == 0)
54 sel->flags |= TCA_NAT_FLAG_EGRESS;
55 else if (matches(*argv, "ingress") != 0)
56 goto bad_val;
57
58 NEXT_ARG();
59
60 if (get_prefix_1(&addr, *argv, AF_INET))
61 goto bad_val;
62
63 sel->old_addr = addr.data[0];
64 sel->mask = htonl(~0u << (32 - addr.bitlen));
65
66 NEXT_ARG();
67
68 if (get_prefix_1(&addr, *argv, AF_INET))
69 goto bad_val;
70
71 sel->new_addr = addr.data[0];
72
73 argc--;
74 argv++;
75
76 *argc_p = argc;
77 *argv_p = argv;
78 return 0;
79
80 bad_val:
81 return -1;
82 }
83
84 static int
parse_nat(struct action_util * a,int * argc_p,char *** argv_p,int tca_id,struct nlmsghdr * n)85 parse_nat(struct action_util *a, int *argc_p, char ***argv_p, int tca_id, struct nlmsghdr *n)
86 {
87 struct tc_nat sel;
88
89 int argc = *argc_p;
90 char **argv = *argv_p;
91 int ok = 0;
92 struct rtattr *tail;
93
94 memset(&sel, 0, sizeof(sel));
95
96 while (argc > 0) {
97 if (matches(*argv, "nat") == 0) {
98 NEXT_ARG();
99 if (parse_nat_args(&argc, &argv, &sel)) {
100 fprintf(stderr, "Illegal nat construct (%s) \n",
101 *argv);
102 explain();
103 return -1;
104 }
105 ok++;
106 continue;
107 } else if (matches(*argv, "help") == 0) {
108 usage();
109 } else {
110 break;
111 }
112
113 }
114
115 if (!ok) {
116 explain();
117 return -1;
118 }
119
120 if (argc) {
121 if (matches(*argv, "reclassify") == 0) {
122 sel.action = TC_ACT_RECLASSIFY;
123 argc--;
124 argv++;
125 } else if (matches(*argv, "pipe") == 0) {
126 sel.action = TC_ACT_PIPE;
127 argc--;
128 argv++;
129 } else if (matches(*argv, "drop") == 0 ||
130 matches(*argv, "shot") == 0) {
131 sel.action = TC_ACT_SHOT;
132 argc--;
133 argv++;
134 } else if (matches(*argv, "continue") == 0) {
135 sel.action = TC_ACT_UNSPEC;
136 argc--;
137 argv++;
138 } else if (matches(*argv, "pass") == 0) {
139 sel.action = TC_ACT_OK;
140 argc--;
141 argv++;
142 }
143 }
144
145 if (argc) {
146 if (matches(*argv, "index") == 0) {
147 NEXT_ARG();
148 if (get_u32(&sel.index, *argv, 10)) {
149 fprintf(stderr, "Nat: Illegal \"index\"\n");
150 return -1;
151 }
152 argc--;
153 argv++;
154 }
155 }
156
157 tail = NLMSG_TAIL(n);
158 addattr_l(n, MAX_MSG, tca_id, NULL, 0);
159 addattr_l(n, MAX_MSG, TCA_NAT_PARMS, &sel, sizeof(sel));
160 tail->rta_len = (char *)NLMSG_TAIL(n) - (char *)tail;
161
162 *argc_p = argc;
163 *argv_p = argv;
164 return 0;
165 }
166
167 static int
print_nat(struct action_util * au,FILE * f,struct rtattr * arg)168 print_nat(struct action_util *au,FILE * f, struct rtattr *arg)
169 {
170 struct tc_nat *sel;
171 struct rtattr *tb[TCA_NAT_MAX + 1];
172 char buf1[256];
173 char buf2[256];
174 SPRINT_BUF(buf3);
175 int len;
176
177 if (arg == NULL)
178 return -1;
179
180 parse_rtattr_nested(tb, TCA_NAT_MAX, arg);
181
182 if (tb[TCA_NAT_PARMS] == NULL) {
183 fprintf(f, "[NULL nat parameters]");
184 return -1;
185 }
186 sel = RTA_DATA(tb[TCA_NAT_PARMS]);
187
188 len = ffs(sel->mask);
189 len = len ? 33 - len : 0;
190
191 fprintf(f, " nat %s %s/%d %s %s", sel->flags & TCA_NAT_FLAG_EGRESS ?
192 "egress" : "ingress",
193 format_host(AF_INET, 4, &sel->old_addr, buf1, sizeof(buf1)),
194 len,
195 format_host(AF_INET, 4, &sel->new_addr, buf2, sizeof(buf2)),
196 action_n2a(sel->action, buf3, sizeof (buf3)));
197
198 if (show_stats) {
199 if (tb[TCA_NAT_TM]) {
200 struct tcf_t *tm = RTA_DATA(tb[TCA_NAT_TM]);
201 print_tm(f,tm);
202 }
203 }
204
205 return 0;
206 }
207
208 struct action_util nat_action_util = {
209 .id = "nat",
210 .parse_aopt = parse_nat,
211 .print_aopt = print_nat,
212 };
213