commands/rshd/rshd.c

   1 /*
   2 in.rshd.c
   3 */
   4
   5 /*
   6         main channel:
   7
   8         back channel\0
   9         remuser\0
  10         locuser\0
  11         command\0
  12         data
  13
  14         back channel:
  15         signal\0
  16
  17 */
  18
  19 #include <sys/types.h>
  20 #include <errno.h>
  21 #include <fcntl.h>
  22 #include <limits.h>
  23 #include <pwd.h>
  24 #include <grp.h>
  25 #include <signal.h>
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <unistd.h>
  30 #include <sys/ioctl.h>
  31 #include <net/gen/in.h>
  32 #include <net/gen/inet.h>
  33 #include <net/gen/netdb.h>
  34 #include <net/gen/socket.h>
  35 #include <net/gen/tcp.h>
  36 #include <net/gen/tcp_io.h>
  37 #include <net/hton.h>
  38 #include <net/netlib.h>
  39
  40 #define DEBUG 0
  41
  42 #if DEBUG
  43 #define where() fprintf(stderr, "%s, %d: ", __FILE__, __LINE__)
  44 #endif
  45
  46 char cmdbuf[_POSIX_ARG_MAX+1], locuser[16], remuser[16];
  47 extern char **environ;
  48 char username[20]="USER=";
  49 char homedir[64]="HOME=";
  50 char shell[64]="SHELL=";
  51 char tz[1024]="TZ=";
  52 char *envinit[]= {homedir, shell, username, tz, "PATH=:/bin:/usr/bin", 0};
  53 char *prog_name;
  54 char buffer[PIPE_BUF];
  55
  56 #if __STDC__
  57 #define PROTO(func, args) func args
  58 #else
  59 #define PROTO(func, args) func ()
  60 #endif
  61
  62 PROTO (int main, (int argc, char *argv[]));
  63 PROTO (void getstr, (char*buf, int cnt, char *err));
  64 PROTO (void close_on_exec, (int fd));
  65
  66 int main(argc, argv)
  67 int argc;
  68 char *argv[];
  69 {
  70         int result, result1;
  71         nwio_tcpconf_t tcpconf, err_tcpconf;
  72         nwio_tcpcl_t tcpconnopt;
  73         nwio_tcpatt_t tcpattachopt;
  74         tcpport_t tcpport;
  75         tcpport_t err_port;
  76         int err_fd, pds[2];
  77         pid_t pid, pid1, new_pg;
  78 #if USEATTACH
  79         int err2_fd;
  80 #endif
  81         struct passwd *pwent;
  82         char *cp, *buff_ptr, *TZ;
  83         char sig;
  84
  85         prog_name= argv[0];
  86         if (argc != 1)
  87         {
  88                 fprintf(stderr, "%s: wrong number of arguments (%d)\n",
  89                         prog_name, argc);
  90                 exit(1);
  91         }
  92
  93         signal(SIGINT, SIG_DFL);
  94         signal(SIGQUIT, SIG_DFL);
  95         signal(SIGTERM, SIG_DFL);
  96
  97 #if DEBUG
  98  { where(); fprintf(stderr, "\n"); }
  99 #endif
 100         result= ioctl (0, NWIOGTCPCONF, &tcpconf);
 101         if (result<0)
 102         {
 103                 fprintf(stderr, "%s: ioctl(NWIOGTCPCONF)= %d : %s\n",
 104                         prog_name, errno, strerror(errno));
 105                 exit(1);
 106         }
 107 #if DEBUG
 108  { where(); fprintf(stderr, "\n"); }
 109 #endif
 110
 111         tcpport= ntohs(tcpconf.nwtc_remport);
 112         if (tcpport >= TCPPORT_RESERVED || tcpport < TCPPORT_RESERVED/2)
 113         {
 114                 printf("\1%s: unprotected port (%d)\n", prog_name, tcpport);
 115                 exit(1);
 116         }
 117         alarm(60);
 118         err_port= 0;
 119         for (;;)
 120         {
 121                 char c;
 122                 result= read(0, &c, 1);
 123                 if (result <0)
 124                 {
 125                         fprintf(stderr, "%s: read= %d : %s\n", prog_name,
 126                                 errno, strerror(errno));
 127                 }
 128                 if (result<1)
 129                         exit(1);
 130                 if (c == 0)
 131                         break;
 132                 err_port= err_port*10 + c - '0';
 133         }
 134         alarm(0);
 135         if (err_port != 0)
 136         {
 137                 int n, pid, lport;
 138
 139                 pid= getpid();
 140                 lport= 1;
 141                 do {
 142                         lport= (lport << 1) | (pid & 1);
 143                         pid >>= 1;
 144                 } while (lport < TCPPORT_RESERVED/2);
 145
 146                 n= TCPPORT_RESERVED/2;
 147                 do
 148                 {
 149                         if (--lport < TCPPORT_RESERVED/2)
 150                                 lport= TCPPORT_RESERVED-1;
 151                         err_fd= open ("/dev/tcp", O_RDWR);
 152                         if (err_fd<0)
 153                         {
 154                                 fprintf(stderr, "%s: open= %d : %s\n",
 155                                         prog_name, errno, strerror(errno));
 156                                 exit(1);
 157                         }
 158                         close_on_exec(err_fd);
 159                         err_tcpconf.nwtc_flags= NWTC_LP_SET | NWTC_SET_RA |
 160                                 NWTC_SET_RP | NWTC_EXCL;
 161                         err_tcpconf.nwtc_locport= htons(lport);
 162                         err_tcpconf.nwtc_remport= htons(err_port);
 163                         err_tcpconf.nwtc_remaddr= tcpconf.nwtc_remaddr;
 164
 165 #if DEBUG
 166  { where(); fprintf(stderr, "\n"); }
 167 #endif
 168                         result= ioctl (err_fd, NWIOSTCPCONF, &err_tcpconf);
 169                         if (result == 0) break;
 170                         if (errno != EADDRINUSE)
 171                         {
 172                                 fprintf(stderr,
 173                                         "%s: ioctl(NWIOSTCPCONF)= %d : %s\n",
 174                                         prog_name, errno, strerror(errno));
 175                                 exit(1);
 176                         }
 177                         close(err_fd);
 178                 } while (--n > 0);
 179                 if (n == 0)
 180                 {
 181                         printf("\1can't get stderr port\n");
 182                         exit(1);
 183                 }
 184
 185                 err_tcpconf.nwtc_flags= NWTC_SHARED;
 186 #if DEBUG
 187 { where(); fprintf(stderr, "\n"); }
 188 #endif
 189                 result= ioctl (err_fd, NWIOSTCPCONF, &err_tcpconf);
 190                 if (result<0)
 191                 {
 192                         fprintf(stderr,
 193                                 "%s: ioctl(NWIOSTCPCONF)= %d : %s\n",
 194                                 prog_name, errno, strerror(errno));
 195                         exit(1);
 196                 }
 197 #if DEBUG
 198 { where(); fprintf(stderr, "\n"); }
 199 #endif
 200                 tcpconnopt.nwtcl_flags= 0;
 201
 202                 n= 20;
 203                 for (;;)
 204                 {
 205 #if DEBUG
 206 { where(); fprintf(stderr, "\n"); }
 207 #endif
 208                         result= ioctl (err_fd, NWIOTCPCONN, &tcpconnopt);
 209                         if (result == 0) break;
 210                         if (errno != EAGAIN && errno != ECONNREFUSED)
 211                         {
 212                                 fprintf(stderr,
 213                                         "%s: ioctl(NWIOTCPCONN)= %d : %s\n",
 214                                         prog_name, errno, strerror(errno));
 215                                 exit(1);
 216                         }
 217                         if (--n == 0) break;
 218                         sleep(1);
 219 #if DEBUG
 220 { where(); fprintf(stderr, "\n"); }
 221 #endif
 222                 }
 223 #if USEATTACH
 224                 err2_fd= open ("/dev/tcp", O_RDWR);
 225                 close_on_exec(err2_fd);
 226                 if (err2_fd<0)
 227                 {
 228                         fprintf(stderr, "%s: open= %d : %s\n", errno,
 229                                 prog_name, strerror(errno));
 230                         exit(1);
 231                 }
 232 #if DEBUG
 233  { where(); fprintf(stderr, "\n"); }
 234 #endif
 235                 result= ioctl (err2_fd, NWIOSTCPCONF, &err_tcpconf);
 236                 if (result<0)
 237                 {
 238                         fprintf(stderr, "%s: ioctl(NWIOSTCPCONF)= %d : %s\n",
 239                                 prog_name, errno, strerror(errno));
 240                         exit(1);
 241                 }
 242 #if DEBUG
 243  { where(); fprintf(stderr, "\n"); }
 244 #endif
 245                 tcpattachopt.nwta_flags= 0;
 246 #if DEBUG
 247  { where(); fprintf(stderr, "\n"); }
 248 #endif
 249                 result= ioctl (err2_fd, NWIOTCPATTACH, &tcpattachopt);
 250                 if (result<0)
 251                 {
 252                         fprintf(stderr, "%s: ioctl(NWIOTCPATTACH)= %d : %s\n",
 253                                 prog_name, errno, strerror(errno));
 254                         exit(1);
 255                 }
 256 #if DEBUG
 257  { where(); fprintf(stderr, "\n"); }
 258 #endif
 259 #endif
 260         }
 261         getstr(remuser, sizeof(remuser), "remuser");
 262         getstr(locuser, sizeof(locuser), "locuser");
 263         getstr(cmdbuf, sizeof(cmdbuf), "cmdbuf");
 264         setpwent();
 265         pwent= getpwnam(locuser);
 266         if (!pwent)
 267         {
 268                 printf("\1Login incorrect.\n");
 269                 exit(1);
 270         }
 271         endpwent();
 272         if (chdir(pwent->pw_dir) < 0)
 273         {
 274                 chdir("/");
 275         }
 276 #if DEBUG
 277  { where(); fprintf(stderr, "calling iruserok(%s, %d, %s, %s)\n",
 278         inet_ntoa(tcpconf.nwtc_remaddr), 0, remuser, locuser); }
 279 #endif
 280         if (iruserok(tcpconf.nwtc_remaddr, 0, remuser, locuser) < 0)
 281         {
 282                 printf("\1Permission denied.\n");
 283                 exit(1);
 284         }
 285         if (err_port)
 286         {
 287                 /* Let's go to a different process group. */
 288                 new_pg= setsid();
 289                 pid= fork();
 290                 if (pid<0)
 291                 {
 292                         if (errno != EAGAIN)
 293                         {
 294                                 fprintf(stderr, "%s: fork()= %d : %s\n",
 295                                         prog_name, errno, strerror(errno));
 296                         }
 297                         printf("\1Try again.\n");
 298                         exit(1);
 299                 }
 300                 if (pid)
 301                 {
 302                         close(0);       /* stdin */
 303                         close(1);       /* stdout */
 304 #if USEATTACH
 305                         close(err_fd);  /* stderr for shell */
 306 #endif
 307                         dup2(2,0);
 308                         dup2(2,1);
 309                         for (;;)
 310                         {
 311 #if !USEATTACH
 312                                 if (read(err_fd, &sig, 1) <= 0)
 313 #else
 314                                 if (read(err2_fd, &sig, 1) <= 0)
 315 #endif
 316                                 {
 317 #if 0
 318                                         printf("read failed: %d\n", errno);
 319 #endif
 320                                         exit(0);
 321                                 }
 322                                 pid= 0;
 323 #if 0
 324                                 printf("killing %d with %d\n", -new_pg, sig);
 325 #endif
 326                                 kill(-new_pg, sig);
 327                         }
 328                 }
 329 #if USEATTACH
 330                 close(err2_fd); /* signal channel for parent */
 331 #endif
 332                 result= pipe(pds);
 333                 if (result<0)
 334                 {
 335                         printf("\1Can't make pipe\n");
 336                         kill(getppid(), SIGTERM);
 337                         exit(1);
 338                 }
 339                 pid1= fork();
 340                 if (pid1<0)
 341                 {
 342                         if (errno != EAGAIN)
 343                         {
 344                                 fprintf(stderr, "%s: fork()= %d : %s\n",
 345                                         prog_name, errno, strerror(errno));
 346                         }
 347                         printf("\1Try again.\n");
 348                         kill(-new_pg, SIGTERM);
 349                         exit(1);
 350                 }
 351                 if (pid1)
 352                 {
 353                         close(pds[1]);  /* write side of pipe */
 354                         for (;;)
 355                         {
 356                                 result= read(pds[0], buffer, sizeof(buffer));
 357                                 if (result<=0)
 358                                 {
 359                                         kill(pid, SIGTERM);
 360                                         exit(0);
 361                                 }
 362                                 buff_ptr= buffer;
 363                                 while (result>0)
 364                                 {
 365                                         result1= write (err_fd, buff_ptr,
 366                                                 result);
 367                                         if (result1 <= 0)
 368                                         {
 369                                                 fprintf(stderr,
 370                                                 "%s: write()= %d : %s\n",
 371                                                         prog_name, errno,
 372                                                         strerror(errno));
 373                                                 kill(-new_pg, SIGTERM);
 374                                                 exit(1);
 375                                         }
 376                                         result -= result1;
 377                                 }
 378                         }
 379                 }
 380                 close(err_fd);  /* file descriptor for error channel */
 381                 close (pds[0]); /* read side of pipe */
 382                 dup2(pds[1], 2);
 383                 close (pds[1]); /* write side of pipe */
 384         }
 385         if (*pwent->pw_shell == '\0')
 386                 pwent->pw_shell= "/bin/sh";
 387 #if __minix_vmd
 388         initgroups(pwent->pw_name, pwent->pw_gid);
 389 #endif
 390         setgid(pwent->pw_gid);
 391         setuid(pwent->pw_uid);
 392         TZ=getenv("TZ");
 393         environ= envinit;
 394         strncat(homedir, pwent->pw_dir, sizeof(homedir)-6);
 395         strncat(shell, pwent->pw_shell, sizeof(shell)-7);
 396         strncat(username, pwent->pw_name, sizeof(username)-6);
 397         if (TZ)
 398                 strncat(tz, TZ, sizeof(tz)-4);
 399         else
 400                 envinit[3]= NULL;
 401
 402         cp= strrchr(pwent->pw_shell, '/');
 403         if (cp)
 404                 cp++;
 405         else
 406                 cp= pwent->pw_shell;
 407
 408         if (!err_port)
 409                 dup2(1, 2);
 410         write(1, "\0", 1);
 411
 412         execl(pwent->pw_shell, cp, "-c", cmdbuf, 0);
 413         close(2);
 414         open("/dev/tty", O_RDWR);
 415         fprintf(stderr, "%s: execl(%s, %s, .., %s)= %d : %s\n", prog_name,
 416                 pwent->pw_shell, cp, cmdbuf, errno, strerror(errno));
 417         kill(getppid(), SIGTERM);
 418         exit(1);
 419 }
 420
 421 void getstr(buf, cnt, err)
 422 char *buf;
 423 int cnt;
 424 char *err;
 425 {
 426         char c;
 427
 428         do
 429         {
 430                 if (read(0, &c, 1) != 1)
 431                         exit(1);
 432                 *buf++ = c;
 433                 if (--cnt == 0)
 434                 {
 435                         printf("\1%s too long", err);
 436                         exit(1);
 437                 }
 438         } while (c != 0);
 439 }
 440
 441 void close_on_exec(fd)
 442 int fd;
 443 {
 444         (void) fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
 445 }