1 #ifndef lint 2 static char sccsid[] = "@(#)rshd.c 4.20 (Berkeley) 09/04/84"; 3 #endif 4 5 /* 6 * remote shell server: 7 * remuser\0 8 * locuser\0 9 * command\0 10 * data 11 */ 12 #include <sys/ioctl.h> 13 #include <sys/param.h> 14 #include <sys/socket.h> 15 #include <sys/wait.h> 16 17 #include <netinet/in.h> 18 19 #include <stdio.h> 20 #include <errno.h> 21 #include <pwd.h> 22 #include <signal.h> 23 #include <netdb.h> 24 25 int errno; 26 struct passwd *getpwnam(); 27 char *index(), *rindex(), *sprintf(); 28 /* VARARGS 1 */ 29 int error(); 30 31 main(argc, argv) 32 int argc; 33 char **argv; 34 { 35 struct linger linger; 36 int on = 1, fromlen; 37 struct sockaddr_in from; 38 39 fromlen = sizeof (from); 40 if (getpeername(0, &from, &fromlen) < 0) { 41 fprintf(stderr, "%s: ", argv[0]); 42 perror("getpeername"); 43 _exit(1); 44 } 45 if (setsockopt(0, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof (on)) < 0) { 46 fprintf(stderr, "%s: ", argv[0]); 47 perror("setsockopt (SO_KEEPALIVE)"); 48 } 49 linger.l_onoff = 1; 50 linger.l_linger = 60; /* XXX */ 51 if (setsockopt(0, SOL_SOCKET, SO_LINGER, &linger, sizeof (linger)) < 0) { 52 fprintf(stderr, "%s: ", argv[0]); 53 perror("setsockopt (SO_LINGER)"); 54 } 55 doit(dup(0), &from); 56 } 57 58 char username[20] = "USER="; 59 char homedir[64] = "HOME="; 60 char shell[64] = "SHELL="; 61 char *envinit[] = 62 {homedir, shell, "PATH=:/usr/ucb:/bin:/usr/bin", username, 0}; 63 char **environ; 64 65 doit(f, fromp) 66 int f; 67 struct sockaddr_in *fromp; 68 { 69 char cmdbuf[NCARGS+1], *cp; 70 char locuser[16], remuser[16]; 71 struct passwd *pwd; 72 int s, backoff; 73 struct hostent *hp; 74 short port; 75 int pv[2], pid, ready, readfrom, cc; 76 char buf[BUFSIZ], sig; 77 int one = 1; 78 79 (void) signal(SIGINT, SIG_DFL); 80 (void) signal(SIGQUIT, SIG_DFL); 81 (void) signal(SIGTERM, SIG_DFL); 82 #ifdef DEBUG 83 { int t = open("/dev/tty", 2); 84 if (t >= 0) { 85 ioctl(t, TIOCNOTTY, (char *)0); 86 (void) close(t); 87 } 88 } 89 #endif 90 fromp->sin_port = ntohs((u_short)fromp->sin_port); 91 if (fromp->sin_family != AF_INET || 92 fromp->sin_port >= IPPORT_RESERVED) { 93 fprintf(stderr, "rshd: malformed from address\n"); 94 exit(1); 95 } 96 (void) alarm(60); 97 port = 0; 98 for (;;) { 99 char c; 100 if (read(f, &c, 1) != 1) { 101 perror("rshd: read"); 102 shutdown(f, 1+1); 103 exit(1); 104 } 105 if (c == 0) 106 break; 107 port = port * 10 + c - '0'; 108 } 109 (void) alarm(0); 110 if (port != 0) { 111 int lport = IPPORT_RESERVED - 1, retryshift; 112 s = rresvport(&lport); 113 if (s < 0) { 114 perror("rshd: can't get stderr port"); 115 exit(1); 116 } 117 if (port >= IPPORT_RESERVED) { 118 fprintf(stderr, "rshd: 2nd port not reserved\n"); 119 exit(1); 120 } 121 fromp->sin_port = htons((u_short)port); 122 if (connect(s, fromp, sizeof (*fromp), 0) < 0) { 123 perror("rshd: connect"); 124 exit(1); 125 } 126 } 127 dup2(f, 0); 128 dup2(f, 1); 129 dup2(f, 2); 130 hp = gethostbyaddr(&fromp->sin_addr, sizeof (struct in_addr), 131 fromp->sin_family); 132 if (hp == 0) { 133 error("Host name for your address unknown\n"); 134 exit(1); 135 } 136 getstr(remuser, sizeof(remuser), "remuser"); 137 getstr(locuser, sizeof(locuser), "locuser"); 138 getstr(cmdbuf, sizeof(cmdbuf), "command"); 139 setpwent(); 140 pwd = getpwnam(locuser); 141 if (pwd == NULL) { 142 error("Login incorrect.\n"); 143 exit(1); 144 } 145 endpwent(); 146 if (chdir(pwd->pw_dir) < 0) { 147 chdir("/"); 148 #ifdef notdef 149 error("No remote directory.\n"); 150 exit(1); 151 #endif 152 } 153 if (ruserok(hp->h_name, pwd->pw_uid == 0, remuser, locuser) < 0) { 154 error("Permission denied.\n"); 155 exit(1); 156 } 157 (void) write(2, "\0", 1); 158 if (port) { 159 if (pipe(pv) < 0) { 160 error("Can't make pipe.\n"); 161 exit(1); 162 } 163 pid = fork(); 164 if (pid == -1) { 165 error("Try again.\n"); 166 exit(1); 167 } 168 if (pid) { 169 (void) close(0); (void) close(1); (void) close(2); 170 (void) close(f); (void) close(pv[1]); 171 readfrom = (1<<s) | (1<<pv[0]); 172 ioctl(pv[1], FIONBIO, (char *)&one); 173 /* should set s nbio! */ 174 do { 175 ready = readfrom; 176 if (select(16, &ready, 0, 0, 0) < 0) 177 break; 178 if (ready & (1<<s)) { 179 if (read(s, &sig, 1) <= 0) 180 readfrom &= ~(1<<s); 181 else 182 killpg(pid, sig); 183 } 184 if (ready & (1<<pv[0])) { 185 errno = 0; 186 cc = read(pv[0], buf, sizeof (buf)); 187 if (cc <= 0) { 188 shutdown(s, 1+1); 189 readfrom &= ~(1<<pv[0]); 190 } else 191 (void) write(s, buf, cc); 192 } 193 } while (readfrom); 194 exit(0); 195 } 196 setpgrp(0, getpid()); 197 (void) close(s); (void) close(pv[0]); 198 dup2(pv[1], 2); 199 } 200 if (*pwd->pw_shell == '\0') 201 pwd->pw_shell = "/bin/sh"; 202 (void) close(f); 203 (void) setgid(pwd->pw_gid); 204 initgroups(pwd->pw_name, pwd->pw_gid); 205 (void) setuid(pwd->pw_uid); 206 environ = envinit; 207 strncat(homedir, pwd->pw_dir, sizeof(homedir)-6); 208 strncat(shell, pwd->pw_shell, sizeof(shell)-7); 209 strncat(username, pwd->pw_name, sizeof(username)-6); 210 cp = rindex(pwd->pw_shell, '/'); 211 if (cp) 212 cp++; 213 else 214 cp = pwd->pw_shell; 215 execl(pwd->pw_shell, cp, "-c", cmdbuf, 0); 216 perror(pwd->pw_shell); 217 exit(1); 218 protofail: 219 error("rsh: protocol failure detected by remote\n"); 220 exit(1); 221 } 222 223 /* VARARGS 1 */ 224 error(fmt) 225 char *fmt; 226 { 227 char buf[BUFSIZ]; 228 229 buf[0] = 1; 230 (void) sprintf(buf+1, fmt); 231 (void) write(2, buf, strlen(buf)); 232 } 233 234 getstr(buf, cnt, err) 235 char *buf; 236 int cnt; 237 char *err; 238 { 239 char c; 240 241 do { 242 if (read(0, &c, 1) != 1) 243 exit(1); 244 *buf++ = c; 245 if (--cnt == 0) { 246 error("%s too long\n", err); 247 exit(1); 248 } 249 } while (c != 0); 250 } 251