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