mdw@git.distorted.org.uk Git - sgt/putty/blob - unix/pty.c

   1 #define _XOPEN_SOURCE
   2 #define _XOPEN_SOURCE_EXTENDED
   3 #include <features.h>
   4
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <string.h>
   8 #include <unistd.h>
   9 #include <signal.h>
  10 #include <fcntl.h>
  11 #include <termios.h>
  12 #include <grp.h>
  13 #include <utmp.h>
  14 #include <pwd.h>
  15 #include <time.h>
  16 #include <sys/types.h>
  17 #include <sys/wait.h>
  18 #include <sys/ioctl.h>
  19
  20 #include "putty.h"
  21
  22 #ifndef FALSE
  23 #define FALSE 0
  24 #endif
  25 #ifndef TRUE
  26 #define TRUE 1
  27 #endif
  28
  29 #ifndef UTMP_FILE
  30 #define UTMP_FILE "/var/run/utmp"
  31 #endif
  32 #ifndef WTMP_FILE
  33 #define WTMP_FILE "/var/log/wtmp"
  34 #endif
  35 #ifndef LASTLOG_FILE
  36 #ifdef _PATH_LASTLOG
  37 #define LASTLOG_FILE _PATH_LASTLOG
  38 #else
  39 #define LASTLOG_FILE "/var/log/lastlog"
  40 #endif
  41 #endif
  42
  43 /*
  44  * Set up a default for vaguely sane systems. The idea is that if
  45  * OMIT_UTMP is not defined, then at least one of the symbols which
  46  * enable particular forms of utmp processing should be, if only so
  47  * that a link error can warn you that you should have defined
  48  * OMIT_UTMP if you didn't want any. Currently HAVE_PUTUTLINE is
  49  * the only such symbol.
  50  */
  51 #ifndef OMIT_UTMP
  52 #if !defined HAVE_PUTUTLINE
  53 #define HAVE_PUTUTLINE
  54 #endif
  55 #endif
  56
  57 int pty_master_fd;
  58 static int pty_stamped_utmp = 0;
  59 static int pty_child_pid;
  60 static sig_atomic_t pty_child_dead;
  61 #ifndef OMIT_UTMP
  62 static struct utmp utmp_entry;
  63 #endif
  64 char **pty_argv;
  65
  66 int pty_child_is_dead(void)
  67 {
  68     return pty_child_dead;
  69 }
  70
  71 static void pty_size(void);
  72
  73 static void setup_utmp(char *ttyname)
  74 {
  75 #ifndef OMIT_UTMP
  76 #ifdef HAVE_LASTLOG
  77     struct lastlog lastlog_entry;
  78     FILE *lastlog;
  79 #endif
  80     struct passwd *pw;
  81     char *location;
  82     FILE *wtmp;
  83
  84     if (!cfg.stamp_utmp)
  85         return;
  86
  87     pw = getpwuid(getuid());
  88     location = get_x_display();
  89     memset(&utmp_entry, 0, sizeof(utmp_entry));
  90     utmp_entry.ut_type = USER_PROCESS;
  91     utmp_entry.ut_pid = getpid();
  92     strncpy(utmp_entry.ut_line, ttyname+5, lenof(utmp_entry.ut_line));
  93     strncpy(utmp_entry.ut_id, ttyname+8, lenof(utmp_entry.ut_id));
  94     strncpy(utmp_entry.ut_user, pw->pw_name, lenof(utmp_entry.ut_user));
  95     strncpy(utmp_entry.ut_host, location, lenof(utmp_entry.ut_host));
  96     time(&utmp_entry.ut_time);
  97
  98 #if defined HAVE_PUTUTLINE
  99     utmpname(UTMP_FILE);
 100     setutent();
 101     pututline(&utmp_entry);
 102     endutent();
 103 #endif
 104
 105     if ((wtmp = fopen(WTMP_FILE, "a")) != NULL) {
 106         fwrite(&utmp_entry, 1, sizeof(utmp_entry), wtmp);
 107         fclose(wtmp);
 108     }
 109
 110 #ifdef HAVE_LASTLOG
 111     memset(&lastlog_entry, 0, sizeof(lastlog_entry));
 112     strncpy(lastlog_entry.ll_line, ttyname+5, lenof(lastlog_entry.ll_line));
 113     strncpy(lastlog_entry.ll_host, location, lenof(lastlog_entry.ll_host));
 114     time(&lastlog_entry.ll_time);
 115     if ((lastlog = fopen(LASTLOG_FILE, "r+")) != NULL) {
 116         fseek(lastlog, sizeof(lastlog_entry) * getuid(), SEEK_SET);
 117         fwrite(&lastlog_entry, 1, sizeof(lastlog_entry), lastlog);
 118         fclose(lastlog);
 119     }
 120 #endif
 121
 122     pty_stamped_utmp = 1;
 123
 124 #endif
 125 }
 126
 127 static void cleanup_utmp(void)
 128 {
 129 #ifndef OMIT_UTMP
 130     FILE *wtmp;
 131
 132     if (!cfg.stamp_utmp || !pty_stamped_utmp)
 133         return;
 134
 135     utmp_entry.ut_type = DEAD_PROCESS;
 136     memset(utmp_entry.ut_user, 0, lenof(utmp_entry.ut_user));
 137     time(&utmp_entry.ut_time);
 138
 139     if ((wtmp = fopen(WTMP_FILE, "a")) != NULL) {
 140         fwrite(&utmp_entry, 1, sizeof(utmp_entry), wtmp);
 141         fclose(wtmp);
 142     }
 143
 144     memset(utmp_entry.ut_line, 0, lenof(utmp_entry.ut_line));
 145     utmp_entry.ut_time = 0;
 146
 147 #if defined HAVE_PUTUTLINE
 148     utmpname(UTMP_FILE);
 149     setutent();
 150     pututline(&utmp_entry);
 151     endutent();
 152 #endif
 153
 154     pty_stamped_utmp = 0;              /* ensure we never double-cleanup */
 155 #endif
 156 }
 157
 158 static void sigchld_handler(int signum)
 159 {
 160     pid_t pid;
 161     int status;
 162     pid = waitpid(-1, &status, WNOHANG);
 163     if (pid == pty_child_pid && (WIFEXITED(status) || WIFSIGNALED(status)))
 164         pty_child_dead = TRUE;
 165 }
 166
 167 static void fatal_sig_handler(int signum)
 168 {
 169     signal(signum, SIG_DFL);
 170     cleanup_utmp();
 171     setuid(getuid());
 172     raise(signum);
 173 }
 174
 175 /*
 176  * Called to set up the pty.
 177  *
 178  * Returns an error message, or NULL on success.
 179  *
 180  * Also places the canonical host name into `realhost'. It must be
 181  * freed by the caller.
 182  */
 183 static char *pty_init(char *host, int port, char **realhost, int nodelay)
 184 {
 185     int slavefd;
 186     char name[FILENAME_MAX];
 187     pid_t pid, pgrp;
 188
 189 #ifdef BSD_PTYS
 190     {
 191         const char chars1[] = "pqrstuvwxyz";
 192         const char chars2[] = "0123456789abcdef";
 193         const char *p1, *p2;
 194         char master_name[20];
 195
 196         for (p1 = chars1; *p1; p1++)
 197             for (p2 = chars2; *p2; p2++) {
 198                 sprintf(master_name, "/dev/pty%c%c", *p1, *p2);
 199                 pty_master_fd = open(master_name, O_RDWR);
 200                 if (pty_master_fd >= 0) {
 201                     if (geteuid() == 0 ||
 202                         access(master_name, R_OK | W_OK) == 0)
 203                         goto got_one;
 204                     close(pty_master_fd);
 205                 }
 206             }
 207
 208         /* If we get here, we couldn't get a tty at all. */
 209         fprintf(stderr, "pterm: unable to open a pseudo-terminal device\n");
 210         exit(1);
 211
 212         got_one:
 213         strcpy(name, master_name);
 214         name[5] = 't';                 /* /dev/ptyXX -> /dev/ttyXX */
 215     }
 216 #else
 217     pty_master_fd = open("/dev/ptmx", O_RDWR);
 218
 219     if (pty_master_fd < 0) {
 220         perror("/dev/ptmx: open");
 221         exit(1);
 222     }
 223
 224     if (grantpt(pty_master_fd) < 0) {
 225         perror("grantpt");
 226         exit(1);
 227     }
 228
 229     if (unlockpt(pty_master_fd) < 0) {
 230         perror("unlockpt");
 231         exit(1);
 232     }
 233
 234     name[FILENAME_MAX-1] = '\0';
 235     strncpy(name, ptsname(pty_master_fd), FILENAME_MAX-1);
 236 #endif
 237
 238     /*
 239      * Trap as many fatal signals as we can in the hope of having
 240      * the best chance to clean up utmp before termination.
 241      */
 242     signal(SIGHUP, fatal_sig_handler);
 243     signal(SIGINT, fatal_sig_handler);
 244     signal(SIGQUIT, fatal_sig_handler);
 245     signal(SIGILL, fatal_sig_handler);
 246     signal(SIGABRT, fatal_sig_handler);
 247     signal(SIGFPE, fatal_sig_handler);
 248     signal(SIGPIPE, fatal_sig_handler);
 249     signal(SIGALRM, fatal_sig_handler);
 250     signal(SIGTERM, fatal_sig_handler);
 251     signal(SIGSEGV, fatal_sig_handler);
 252     signal(SIGUSR1, fatal_sig_handler);
 253     signal(SIGUSR2, fatal_sig_handler);
 254 #ifdef SIGBUS
 255     signal(SIGBUS, fatal_sig_handler);
 256 #endif
 257 #ifdef SIGPOLL
 258     signal(SIGPOLL, fatal_sig_handler);
 259 #endif
 260 #ifdef SIGPROF
 261     signal(SIGPROF, fatal_sig_handler);
 262 #endif
 263 #ifdef SIGSYS
 264     signal(SIGSYS, fatal_sig_handler);
 265 #endif
 266 #ifdef SIGTRAP
 267     signal(SIGTRAP, fatal_sig_handler);
 268 #endif
 269 #ifdef SIGVTALRM
 270     signal(SIGVTALRM, fatal_sig_handler);
 271 #endif
 272 #ifdef SIGXCPU
 273     signal(SIGXCPU, fatal_sig_handler);
 274 #endif
 275 #ifdef SIGXFSZ
 276     signal(SIGXFSZ, fatal_sig_handler);
 277 #endif
 278 #ifdef SIGIO
 279     signal(SIGIO, fatal_sig_handler);
 280 #endif
 281     /* Also clean up utmp on normal exit. */
 282     atexit(cleanup_utmp);
 283     setup_utmp(name);
 284
 285     /*
 286      * Fork and execute the command.
 287      */
 288     pid = fork();
 289     if (pid < 0) {
 290         perror("fork");
 291         exit(1);
 292     }
 293
 294     if (pid == 0) {
 295         int i;
 296         /*
 297          * We are the child.
 298          */
 299
 300         slavefd = open(name, O_RDWR);
 301         if (slavefd < 0) {
 302             perror("slave pty: open");
 303             exit(1);
 304         }
 305
 306 #ifdef BSD_PTYS
 307         /* We need to chown/chmod the /dev/ttyXX device. */
 308         {
 309             struct group *gp = getgrnam("tty");
 310             fchown(slavefd, getuid(), gp ? gp->gr_gid : -1);
 311             fchmod(slavefd, 0600);
 312         }
 313 #endif
 314
 315         close(pty_master_fd);
 316         close(0);
 317         close(1);
 318         close(2);
 319         fcntl(slavefd, F_SETFD, 0);    /* don't close on exec */
 320         dup2(slavefd, 0);
 321         dup2(slavefd, 1);
 322         dup2(slavefd, 2);
 323         setsid();
 324         ioctl(slavefd, TIOCSCTTY, 1);
 325         pgrp = getpid();
 326         tcsetpgrp(slavefd, pgrp);
 327         setpgrp();
 328         close(open(name, O_WRONLY, 0));
 329         setpgrp();
 330         /* In case we were setgid-utmp or setuid-root, drop privs. */
 331         setgid(getgid());
 332         setuid(getuid());
 333         /* Close everything _else_, for tidiness. */
 334         for (i = 3; i < 1024; i++)
 335             close(i);
 336         {
 337             char term_env_var[10 + sizeof(cfg.termtype)];
 338             sprintf(term_env_var, "TERM=%s", cfg.termtype);
 339             putenv(term_env_var);
 340         }
 341         if (pty_argv)
 342             execvp(pty_argv[0], pty_argv);
 343         else {
 344             char *shell = getenv("SHELL");
 345             char *shellname;
 346             if (cfg.login_shell) {
 347                 char *p = strrchr(shell, '/');
 348                 shellname = smalloc(2+strlen(shell));
 349                 p = p ? p+1 : shell;
 350                 sprintf(shellname, "-%s", p);
 351             } else
 352                 shellname = shell;
 353             execl(getenv("SHELL"), shellname, NULL);
 354         }
 355
 356         /*
 357          * If we're here, exec has gone badly foom.
 358          */
 359         perror("exec");
 360         exit(127);
 361     } else {
 362         close(slavefd);
 363         pty_child_pid = pid;
 364         pty_child_dead = FALSE;
 365         signal(SIGCHLD, sigchld_handler);
 366     }
 367
 368     return NULL;
 369 }
 370
 371 /*
 372  * Called to send data down the pty.
 373  */
 374 static int pty_send(char *buf, int len)
 375 {
 376     while (len > 0) {
 377         int ret = write(pty_master_fd, buf, len);
 378         if (ret < 0) {
 379             perror("write pty master");
 380             exit(1);
 381         }
 382         buf += ret;
 383         len -= ret;
 384     }
 385     return 0;
 386 }
 387
 388 /*
 389  * Called to query the current socket sendability status.
 390  */
 391 static int pty_sendbuffer(void)
 392 {
 393     return 0;
 394 }
 395
 396 /*
 397  * Called to set the size of the window
 398  */
 399 static void pty_size(void)
 400 {
 401     struct winsize size;
 402
 403     size.ws_row = (unsigned short)rows;
 404     size.ws_col = (unsigned short)cols;
 405     size.ws_xpixel = (unsigned short) cols * font_dimension(0);
 406     size.ws_ypixel = (unsigned short) rows * font_dimension(1);
 407     ioctl(pty_master_fd, TIOCSWINSZ, (void *)&size);
 408     return;
 409 }
 410
 411 /*
 412  * Send special codes.
 413  */
 414 static void pty_special(Telnet_Special code)
 415 {
 416     /* Do nothing! */
 417     return;
 418 }
 419
 420 static Socket pty_socket(void)
 421 {
 422     return NULL;                       /* shouldn't ever be needed */
 423 }
 424
 425 static int pty_sendok(void)
 426 {
 427     return 1;
 428 }
 429
 430 static void pty_unthrottle(int backlog)
 431 {
 432     /* do nothing */
 433 }
 434
 435 static int pty_ldisc(int option)
 436 {
 437     return 0;                          /* neither editing nor echoing */
 438 }
 439
 440 static int pty_exitcode(void)
 441 {
 442     /* Shouldn't ever be required */
 443     return 0;
 444 }
 445
 446 Backend pty_backend = {
 447     pty_init,
 448     pty_send,
 449     pty_sendbuffer,
 450     pty_size,
 451     pty_special,
 452     pty_socket,
 453     pty_exitcode,
 454     pty_sendok,
 455     pty_ldisc,
 456     pty_unthrottle,
 457     1
 458 };