1 /* Copyright 2002 Jeff Dike
2 * Licensed under the GPL
3 */
4
5 #include <stdio.h>
6 #include <stdlib.h>
7 #include <string.h>
8 #include <errno.h>
9 #include <fcntl.h>
10 #include <unistd.h>
11 #include <pwd.h>
12 #include <grp.h>
13 #include <net/if.h>
14 #include <sys/ioctl.h>
15 #include <linux/if_tun.h>
16
17 /* TUNSETGROUP appeared in 2.6.23 */
18 #ifndef TUNSETGROUP
19 #define TUNSETGROUP _IOW('T', 206, int)
20 #endif
21
Usage(char * name,int status)22 static void Usage(char *name, int status)
23 {
24 fprintf(stderr, "Create: %s [-b] [-u owner] [-g group] [-t device-name] "
25 "[-f tun-clone-device]\n", name);
26 fprintf(stderr, "Delete: %s -d device-name [-f tun-clone-device]\n\n",
27 name);
28 fprintf(stderr, "The default tun clone device is /dev/net/tun - some systems"
29 " use\n/dev/misc/net/tun instead\n\n");
30 fprintf(stderr, "-b will result in brief output (just the device name)\n");
31 exit(status);
32 }
33
main(int argc,char ** argv)34 int main(int argc, char **argv)
35 {
36 struct ifreq ifr;
37 struct passwd *pw;
38 struct group *gr;
39 uid_t owner = -1;
40 gid_t group = -1;
41 int tap_fd, opt, delete = 0, brief = 0;
42 char *tun = "", *file = "/dev/net/tun", *name = argv[0], *end;
43
44 while((opt = getopt(argc, argv, "bd:f:t:u:g:h")) > 0){
45 switch(opt) {
46 case 'b':
47 brief = 1;
48 break;
49 case 'd':
50 delete = 1;
51 tun = optarg;
52 break;
53 case 'f':
54 file = optarg;
55 break;
56 case 'u':
57 pw = getpwnam(optarg);
58 if(pw != NULL){
59 owner = pw->pw_uid;
60 break;
61 }
62 owner = strtol(optarg, &end, 0);
63 if(*end != '\0'){
64 fprintf(stderr, "'%s' is neither a username nor a numeric uid.\n",
65 optarg);
66 Usage(name, 1);
67 }
68 break;
69 case 'g':
70 gr = getgrnam(optarg);
71 if(gr != NULL){
72 group = gr->gr_gid;
73 break;
74 }
75 group = strtol(optarg, &end, 0);
76 if(*end != '\0'){
77 fprintf(stderr, "'%s' is neither a groupname nor a numeric group.\n",
78 optarg);
79 Usage(name, 1);
80 }
81 break;
82
83 case 't':
84 tun = optarg;
85 break;
86 case 'h':
87 Usage(name, 0);
88 break;
89 default:
90 Usage(name, 1);
91 }
92 }
93
94 argv += optind;
95 argc -= optind;
96
97 if(argc > 0)
98 Usage(name, 1);
99
100 if((tap_fd = open(file, O_RDWR)) < 0){
101 fprintf(stderr, "Failed to open '%s' : ", file);
102 perror("");
103 exit(1);
104 }
105
106 memset(&ifr, 0, sizeof(ifr));
107
108 ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
109 strncpy(ifr.ifr_name, tun, sizeof(ifr.ifr_name) - 1);
110 if(ioctl(tap_fd, TUNSETIFF, (void *) &ifr) < 0){
111 perror("TUNSETIFF");
112 exit(1);
113 }
114
115 if(delete){
116 if(ioctl(tap_fd, TUNSETPERSIST, 0) < 0){
117 perror("disabling TUNSETPERSIST");
118 exit(1);
119 }
120 printf("Set '%s' nonpersistent\n", ifr.ifr_name);
121 }
122 else {
123 /* emulate behaviour prior to TUNSETGROUP */
124 if(owner == -1 && group == -1) {
125 owner = geteuid();
126 }
127
128 if(owner != -1) {
129 if(ioctl(tap_fd, TUNSETOWNER, owner) < 0){
130 perror("TUNSETOWNER");
131 exit(1);
132 }
133 }
134 if(group != -1) {
135 if(ioctl(tap_fd, TUNSETGROUP, group) < 0){
136 perror("TUNSETGROUP");
137 exit(1);
138 }
139 }
140
141 if(ioctl(tap_fd, TUNSETPERSIST, 1) < 0){
142 perror("enabling TUNSETPERSIST");
143 exit(1);
144 }
145
146 if(brief)
147 printf("%s\n", ifr.ifr_name);
148 else {
149 printf("Set '%s' persistent and owned by", ifr.ifr_name);
150 if(owner != -1)
151 printf(" uid %d", owner);
152 if(group != -1)
153 printf(" gid %d", group);
154 printf("\n");
155 }
156 }
157 return(0);
158 }
159