2 * helper.c - setuid helper program for authbind
4 * authbind is Copyright (C) 1998 Ian Jackson
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2, or (at your option)
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software Foundation,
18 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
28 #include <sys/types.h>
29 #include <sys/socket.h>
30 #include <netinet/in.h>
31 #include <arpa/inet.h>
34 # define CONFIGDIR "/etc/authbind"
37 static const char *rcsid="$Id$";
39 static void exiterrno(int e) {
40 exit(e>0 && e<128 ? e : ENOSYS);
43 static void perrorfail(const char *m) {
46 fprintf(stderr,"libauthbind's helper: %s: %s\n",m,strerror(e));
50 static void badusage(void) {
51 fprintf(stderr,"libauthbind's helper: bad usage\n (%s)\n",rcsid);
55 static struct sockaddr_in saddr4;
56 static struct sockaddr_in6 saddr6;
58 static struct sockaddr *saddr_any;
59 static const void *addr_any;
60 static size_t saddrlen_any, addrlen_any;
62 static void authorised(void) {
63 if (bind(0,saddr_any,saddrlen_any)) exiterrno(errno);
67 static void hex2bytes(const char *string, unsigned char *out, int len) {
69 for (i=0; i<len; i++) {
71 hex[0]= *string++; if (!hex[0]) badusage();
72 hex[1]= *string++; if (!hex[1]) badusage();
74 *out++ = strtoul(hex,&ep,16);
75 if (ep != &hex[2]) badusage();
79 int main(int argc, const char *const *argv) {
84 const char *tophalfchar="";
85 unsigned long port, addr4=0, haddr4=0;
86 unsigned int hport, a1,a2,a3,a4, alen,pmin,pmax;
92 saddr_any= (void*)&saddr4;
93 saddrlen_any= sizeof(saddr4);
94 addr_any= &saddr4.sin_addr.s_addr;
95 addrlen_any= sizeof(saddr4.sin_addr.s_addr);
96 addr4= strtoul(argv[1],&ep,16);
97 if (*ep || addr4&~0x0ffffffffUL) badusage();
99 } else if (argc == 4 && !strcmp(argv[3],"6")) {
101 saddr_any= (void*)&saddr6;
102 saddrlen_any= sizeof(saddr6);
103 addr_any= &saddr6.sin6_addr.s6_addr;
104 addrlen_any= sizeof(saddr6.sin6_addr.s6_addr);
105 hex2bytes(argv[1], saddr6.sin6_addr.s6_addr,
106 sizeof(saddr6.sin6_addr.s6_addr));
112 port= strtoul(argv[2],&ep,16); if (*ep || port&~0x0ffffUL) badusage();
114 if (hport >= IPPORT_RESERVED/2) tophalfchar= "!";
116 if (chdir(CONFIGDIR)) perrorfail("chdir " CONFIGDIR);
118 fnbuf[sizeof(fnbuf)-1]= 0;
122 saddr4.sin_family= af;
123 saddr4.sin_port= port;
124 saddr4.sin_addr.s_addr= addr4;
127 saddr6.sin6_family= af;
128 saddr6.sin6_port= port;
134 snprintf(fnbuf,sizeof(fnbuf)-1,"byport/%s%u",tophalfchar,hport);
135 if (!access(fnbuf,X_OK)) authorised();
136 if (errno != ENOENT) exiterrno(errno);
138 char npbuf[INET_ADDRSTRLEN + INET6_ADDRSTRLEN];
139 np= inet_ntop(af,addr_any,npbuf,addrlen_any);
142 snprintf(fnbuf,sizeof(fnbuf)-1,"byaddr/%s:%s%u",np,tophalfchar,hport);
143 if (!access(fnbuf,X_OK)) authorised();
144 if (errno != ENOENT) exiterrno(errno);
146 uid= getuid(); if (uid==(uid_t)-1) perrorfail("getuid");
147 snprintf(fnbuf,sizeof(fnbuf)-1,"byuid/%s%lu",tophalfchar,(unsigned long)uid);
149 file= fopen(fnbuf,"r");
150 if (!file) exiterrno(errno==ENOENT ? EPERM : errno);
152 while (fgets(fnbuf,sizeof(fnbuf)-1,file)) {
155 char *colon = strchr(fnbuf,'/');
156 if (!colon) continue;
159 sscanf(fnbuf," %u.%u.%u.%u/%u%n",
160 &a1,&a2,&a3,&a4,&alen,&nchar);
161 if (nchar == strlen(fnbuf)) {
162 if (alen>32 || pmin&~0x0ffff || pmax&~0x0ffff ||
163 a1&~0x0ff || a2&~0xff || a3&~0x0ff || a4&~0x0ff)
166 unsigned long thaddr, thmask;
167 thaddr= (a1<<24)|(a2<<16)|(a3<<8)|(a4);
168 thmask= 0x0ffffffffUL<<(32-alen);
169 if ((haddr4&thmask) != thaddr) continue;
171 char *hyphen = strchr(fnbuf,'-');
172 const char *min, *max;
181 unsigned char minaddr[addrlen_any];
182 unsigned char maxaddr[addrlen_any];
183 if (inet_pton(af,min,minaddr) != 1 ||
184 inet_pton(af,max,maxaddr) != 1)
186 if (memcmp(addr_any,minaddr,addrlen_any) < 0 ||
187 memcmp(addr_any,maxaddr,addrlen_any) > 0)
191 sscanf(colon," %u,%u %n",
193 if (nchar != strlen(colon))
196 if (hport<pmin || hport>pmax) continue;
200 if (ferror(file)) perrorfail("read per-uid file");