1 #ifndef lint 2 static char sccsid[] = "@(#)rshd.c 4.2 82/10/07"; 3 #endif 4 5 #include <stdio.h> 6 #include <sys/ioctl.h> 7 #include <sys/param.h> 8 #include <sys/socket.h> 9 #include <net/in.h> 10 #include <errno.h> 11 #include <pwd.h> 12 #include <wait.h> 13 #include <signal.h> 14 #include <netdb.h> 15 16 int errno; 17 struct sockaddr_in sin = { AF_INET }; 18 struct passwd *getpwnam(); 19 char *index(), *rindex(), *sprintf(); 20 int options = SO_ACCEPTCONN|SO_KEEPALIVE; 21 /* VARARGS 1 */ 22 int error(); 23 /* 24 * remote execute server: 25 * remuser\0 26 * locuser\0 27 * command\0 28 * data 29 */ 30 main(argc, argv) 31 int argc; 32 char **argv; 33 { 34 union wait status; 35 int f; 36 struct sockaddr_in from; 37 struct servent *sp; 38 39 sp = getservbyname("shell", "tcp"); 40 if (sp == 0) { 41 fprintf(stderr, "rshd: tcp/shell: unknown service\n"); 42 exit(1); 43 } 44 #ifndef DEBUG 45 if (fork()) 46 exit(0); 47 for (f = 0; f < 10; f++) 48 (void) close(f); 49 (void) open("/", 0); 50 (void) dup2(0, 1); 51 (void) dup2(0, 2); 52 { int t = open("/dev/tty", 2); 53 if (t >= 0) { 54 ioctl(t, TIOCNOTTY, (char *)0); 55 (void) close(t); 56 } 57 } 58 #endif 59 sin.sin_port = htons(sp->s_port); 60 argc--, argv++; 61 if (argc > 0 && !strcmp(argv[0], "-d")) 62 options |= SO_DEBUG, argc--, argv++; 63 if (argc > 0) { 64 int port = atoi(argv[0]); 65 66 if (port < 0) { 67 fprintf(stderr, "%s: bad port #\n", argv[0]); 68 exit(1); 69 } 70 sin.sin_port = htons(port); 71 argc--, argv++; 72 } 73 for (;;) { 74 errno = 0; 75 f = socket(SOCK_STREAM, 0, &sin, options); 76 if (f < 0) { 77 perror("socket"); 78 sleep(5); 79 continue; 80 } 81 if (accept(f, &from) < 0) { 82 perror("accept"); 83 (void) close(f); 84 sleep(1); 85 continue; 86 } 87 if (fork() == 0) 88 doit(f, &from); 89 (void) close(f); 90 while(wait3(status, WNOHANG, 0) > 0) 91 continue; 92 } 93 } 94 95 char username[20] = "USER="; 96 char homedir[64] = "HOME="; 97 char shell[64] = "SHELL="; 98 char *envinit[] = 99 {homedir, shell, "PATH=:/usr/ucb:/bin:/usr/bin", username, 0}; 100 char **environ; 101 102 doit(f, fromp) 103 int f; 104 struct sockaddr_in *fromp; 105 { 106 char cmdbuf[NCARGS+1], *cp; 107 char locuser[16], remuser[16]; 108 struct passwd *pwd; 109 int s; 110 struct hostent *hp; 111 short port; 112 int pv[2], pid, ready, readfrom, cc; 113 char buf[BUFSIZ], sig; 114 int one = 1; 115 116 (void) signal(SIGINT, SIG_DFL); 117 (void) signal(SIGQUIT, SIG_DFL); 118 (void) signal(SIGTERM, SIG_DFL); 119 #ifdef DEBUG 120 { int t = open("/dev/tty", 2); 121 if (t >= 0) { 122 ioctl(t, TIOCNOTTY, (char *)0); 123 (void) close(t); 124 } 125 } 126 #endif 127 dup2(f, 0); 128 dup2(f, 1); 129 dup2(f, 2); 130 fromp->sin_port = ntohs((u_short)fromp->sin_port); 131 if (fromp->sin_family != AF_INET || 132 fromp->sin_port >= IPPORT_RESERVED) 133 exit(1); 134 (void) alarm(60); 135 port = 0; 136 for (;;) { 137 char c; 138 if (read(f, &c, 1) != 1) 139 exit(1); 140 if (c == 0) 141 break; 142 port = port * 10 + c - '0'; 143 } 144 (void) alarm(0); 145 if (port != 0) { 146 s = rresvport(0); 147 if (s < 0) 148 exit(1); 149 if (port >= IPPORT_RESERVED) 150 goto protofail; 151 (void) alarm(60); 152 fromp->sin_port = ntohs(port); 153 if (connect(s, fromp) < 0) 154 exit(1); 155 (void) alarm(0); 156 } 157 hp = gethostbyaddr(&fromp->sin_addr, sizeof (struct in_addr), 158 fromp->sin_family); 159 if (hp == 0) { 160 error("Host name for your address unknown\n"); 161 exit(1); 162 } 163 getstr(remuser, sizeof(remuser), "remuser"); 164 getstr(locuser, sizeof(locuser), "locuser"); 165 getstr(cmdbuf, sizeof(cmdbuf), "command"); 166 setpwent(); 167 pwd = getpwnam(locuser); 168 if (pwd == NULL) { 169 error("Login incorrect.\n"); 170 exit(1); 171 } 172 endpwent(); 173 if (chdir(pwd->pw_dir) < 0) { 174 error("No remote directory.\n"); 175 exit(1); 176 } 177 if (ruserok(hp->h_name, remuser, locuser) < 0) { 178 error("Permission denied.\n"); 179 exit(1); 180 } 181 (void) write(2, "\0", 1); 182 if (port) { 183 if (pipe(pv) < 0) { 184 error("Can't make pipe.\n"); 185 exit(1); 186 } 187 pid = fork(); 188 if (pid == -1) { 189 error("Try again.\n"); 190 exit(1); 191 } 192 if (pid) { 193 (void) close(0); (void) close(1); (void) close(2); 194 (void) close(f); (void) close(pv[1]); 195 readfrom = (1<<s) | (1<<pv[0]); 196 ioctl(pv[1], FIONBIO, (char *)&one); 197 /* should set s nbio! */ 198 do { 199 ready = readfrom; 200 (void) select(32, &ready, 0, 1000000); 201 if (ready & (1<<s)) { 202 if (read(s, &sig, 1) <= 0) 203 readfrom &= ~(1<<s); 204 else 205 killpg(pid, sig); 206 } 207 if (ready & (1<<pv[0])) { 208 cc = read(pv[0], buf, sizeof (buf)); 209 if (cc <= 0) { 210 int done = 1+1; 211 ioctl(s, SIOCDONE, (char *)&done); 212 readfrom &= ~(1<<pv[0]); 213 } else 214 (void) write(s, buf, cc); 215 } 216 } while (readfrom); 217 exit(0); 218 } 219 setpgrp(0, getpid()); 220 (void) close(s); (void) close(pv[0]); 221 dup2(pv[1], 2); 222 } 223 if (*pwd->pw_shell == '\0') 224 pwd->pw_shell = "/bin/sh"; 225 (void) close(f); 226 inigrp(pwd->pw_name, pwd->pw_gid); 227 (void) setuid(pwd->pw_uid); 228 (void) setgid(pwd->pw_gid); 229 environ = envinit; 230 strncat(homedir, pwd->pw_dir, sizeof(homedir)-6); 231 strncat(shell, pwd->pw_shell, sizeof(shell)-7); 232 strncat(username, pwd->pw_name, sizeof(username)-6); 233 cp = rindex(pwd->pw_shell, '/'); 234 if (cp) 235 cp++; 236 else 237 cp = pwd->pw_shell; 238 execl(pwd->pw_shell, cp, "-c", cmdbuf, 0); 239 perror(pwd->pw_shell); 240 exit(1); 241 protofail: 242 error("rsh: protocol failure detected by remote\n"); 243 exit(1); 244 } 245 246 /* VARARGS 1 */ 247 error(fmt) 248 char *fmt; 249 { 250 char buf[BUFSIZ]; 251 252 buf[0] = 1; 253 (void) sprintf(buf+1, fmt); 254 (void) write(2, buf, strlen(buf)); 255 } 256 257 getstr(buf, cnt, err) 258 char *buf; 259 int cnt; 260 char *err; 261 { 262 char c; 263 264 do { 265 if (read(0, &c, 1) != 1) 266 exit(1); 267 *buf++ = c; 268 if (--cnt == 0) { 269 error("%s too long\n", err); 270 exit(1); 271 } 272 } while (c != 0); 273 } 274