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 while (argc > 0) {
95 if (matches(*argv, "nat") == 0) {
96 NEXT_ARG();
97 if (parse_nat_args(&argc, &argv, &sel)) {
98 fprintf(stderr, "Illegal nat construct (%s)\n",
99 *argv);
100 explain();
101 return -1;
102 }
103 ok++;
104 continue;
105 } else if (matches(*argv, "help") == 0) {
106 usage();
107 } else {
108 break;
109 }
110
111 }
112
113 if (!ok) {
114 explain();
115 return -1;
116 }
117
118 parse_action_control_dflt(&argc, &argv, &sel.action, false, TC_ACT_OK);
119
120 if (argc) {
121 if (matches(*argv, "index") == 0) {
122 NEXT_ARG();
123 if (get_u32(&sel.index, *argv, 10)) {
124 fprintf(stderr, "Nat: Illegal \"index\"\n");
125 return -1;
126 }
127 argc--;
128 argv++;
129 }
130 }
131
132 tail = NLMSG_TAIL(n);
133 addattr_l(n, MAX_MSG, tca_id, NULL, 0);
134 addattr_l(n, MAX_MSG, TCA_NAT_PARMS, &sel, sizeof(sel));
135 tail->rta_len = (char *)NLMSG_TAIL(n) - (char *)tail;
136
137 *argc_p = argc;
138 *argv_p = argv;
139 return 0;
140 }
141
142 static int
print_nat(struct action_util * au,FILE * f,struct rtattr * arg)143 print_nat(struct action_util *au, FILE * f, struct rtattr *arg)
144 {
145 struct tc_nat *sel;
146 struct rtattr *tb[TCA_NAT_MAX + 1];
147 char buf1[256];
148 char buf2[256];
149
150 int len;
151
152 if (arg == NULL)
153 return -1;
154
155 parse_rtattr_nested(tb, TCA_NAT_MAX, arg);
156
157 if (tb[TCA_NAT_PARMS] == NULL) {
158 fprintf(f, "[NULL nat parameters]");
159 return -1;
160 }
161 sel = RTA_DATA(tb[TCA_NAT_PARMS]);
162
163 len = ffs(sel->mask);
164 len = len ? 33 - len : 0;
165
166 fprintf(f, " nat %s %s/%d %s", sel->flags & TCA_NAT_FLAG_EGRESS ?
167 "egress" : "ingress",
168 format_host_r(AF_INET, 4, &sel->old_addr, buf1, sizeof(buf1)),
169 len,
170 format_host_r(AF_INET, 4, &sel->new_addr, buf2, sizeof(buf2)));
171 print_action_control(f, " ", sel->action, "");
172
173 if (show_stats) {
174 if (tb[TCA_NAT_TM]) {
175 struct tcf_t *tm = RTA_DATA(tb[TCA_NAT_TM]);
176
177 print_tm(f, tm);
178 }
179 }
180
181 return 0;
182 }
183
184 struct action_util nat_action_util = {
185 .id = "nat",
186 .parse_aopt = parse_nat,
187 .print_aopt = print_nat,
188 };
189