2 * Pseudo-tty backend for pterm.
4 * Unlike the other backends, data for this one is not neatly
5 * encapsulated into a data structure, because it wouldn't make
6 * sense to do so - the utmp stuff has to be done before a backend
7 * is initialised, and starting a second pterm from the same
8 * process would therefore be infeasible because privileges would
9 * already have been dropped. Hence, I haven't bothered to keep the
10 * data dynamically allocated: instead, the backend handle is just
11 * a null pointer and ignored everywhere.
15 #define _XOPEN_SOURCE_EXTENDED
29 #include <sys/types.h>
31 #include <sys/ioctl.h>
44 #define UTMP_FILE "/var/run/utmp"
47 #define WTMP_FILE "/var/log/wtmp"
51 #define LASTLOG_FILE _PATH_LASTLOG
53 #define LASTLOG_FILE "/var/log/lastlog"
58 * Set up a default for vaguely sane systems. The idea is that if
59 * OMIT_UTMP is not defined, then at least one of the symbols which
60 * enable particular forms of utmp processing should be, if only so
61 * that a link error can warn you that you should have defined
62 * OMIT_UTMP if you didn't want any. Currently HAVE_PUTUTLINE is
63 * the only such symbol.
66 #if !defined HAVE_PUTUTLINE
67 #define HAVE_PUTUTLINE
72 static void *pty_frontend
;
73 static char pty_name
[FILENAME_MAX
];
74 static int pty_stamped_utmp
= 0;
75 static int pty_child_pid
;
76 static int pty_utmp_helper_pid
, pty_utmp_helper_pipe
;
77 static int pty_term_width
, pty_term_height
;
78 static volatile sig_atomic_t pty_child_dead
;
79 static volatile int pty_exit_code
;
81 static struct utmp utmp_entry
;
85 static void setup_utmp(char *ttyname
, char *location
)
89 struct lastlog lastlog_entry
;
95 pw
= getpwuid(getuid());
96 memset(&utmp_entry
, 0, sizeof(utmp_entry
));
97 utmp_entry
.ut_type
= USER_PROCESS
;
98 utmp_entry
.ut_pid
= getpid();
99 strncpy(utmp_entry
.ut_line
, ttyname
+5, lenof(utmp_entry
.ut_line
));
100 strncpy(utmp_entry
.ut_id
, ttyname
+8, lenof(utmp_entry
.ut_id
));
101 strncpy(utmp_entry
.ut_user
, pw
->pw_name
, lenof(utmp_entry
.ut_user
));
102 strncpy(utmp_entry
.ut_host
, location
, lenof(utmp_entry
.ut_host
));
103 time(&utmp_entry
.ut_time
);
105 #if defined HAVE_PUTUTLINE
108 pututline(&utmp_entry
);
112 if ((wtmp
= fopen(WTMP_FILE
, "a")) != NULL
) {
113 fwrite(&utmp_entry
, 1, sizeof(utmp_entry
), wtmp
);
118 memset(&lastlog_entry
, 0, sizeof(lastlog_entry
));
119 strncpy(lastlog_entry
.ll_line
, ttyname
+5, lenof(lastlog_entry
.ll_line
));
120 strncpy(lastlog_entry
.ll_host
, location
, lenof(lastlog_entry
.ll_host
));
121 time(&lastlog_entry
.ll_time
);
122 if ((lastlog
= fopen(LASTLOG_FILE
, "r+")) != NULL
) {
123 fseek(lastlog
, sizeof(lastlog_entry
) * getuid(), SEEK_SET
);
124 fwrite(&lastlog_entry
, 1, sizeof(lastlog_entry
), lastlog
);
129 pty_stamped_utmp
= 1;
134 static void cleanup_utmp(void)
139 if (!pty_stamped_utmp
)
142 utmp_entry
.ut_type
= DEAD_PROCESS
;
143 memset(utmp_entry
.ut_user
, 0, lenof(utmp_entry
.ut_user
));
144 time(&utmp_entry
.ut_time
);
146 if ((wtmp
= fopen(WTMP_FILE
, "a")) != NULL
) {
147 fwrite(&utmp_entry
, 1, sizeof(utmp_entry
), wtmp
);
151 memset(utmp_entry
.ut_line
, 0, lenof(utmp_entry
.ut_line
));
152 utmp_entry
.ut_time
= 0;
154 #if defined HAVE_PUTUTLINE
157 pututline(&utmp_entry
);
161 pty_stamped_utmp
= 0; /* ensure we never double-cleanup */
165 static void sigchld_handler(int signum
)
167 int save_errno
= errno
;
171 pid
= waitpid(-1, &status
, WNOHANG
);
172 if (pid
== pty_child_pid
&& (WIFEXITED(status
) || WIFSIGNALED(status
))) {
173 pty_exit_code
= status
;
174 pty_child_dead
= TRUE
;
179 static void fatal_sig_handler(int signum
)
181 putty_signal(signum
, SIG_DFL
);
187 static void pty_open_master(void)
190 const char chars1
[] = "pqrstuvwxyz";
191 const char chars2
[] = "0123456789abcdef";
193 char master_name
[20];
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)
204 close(pty_master_fd
);
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");
213 strcpy(pty_name
, master_name
);
214 pty_name
[5] = 't'; /* /dev/ptyXX -> /dev/ttyXX */
216 /* We need to chown/chmod the /dev/ttyXX device. */
217 gp
= getgrnam("tty");
218 chown(pty_name
, getuid(), gp ? gp
->gr_gid
: -1);
219 chmod(pty_name
, 0600);
221 pty_master_fd
= open("/dev/ptmx", O_RDWR
);
223 if (pty_master_fd
< 0) {
224 perror("/dev/ptmx: open");
228 if (grantpt(pty_master_fd
) < 0) {
233 if (unlockpt(pty_master_fd
) < 0) {
238 pty_name
[FILENAME_MAX
-1] = '\0';
239 strncpy(pty_name
, ptsname(pty_master_fd
), FILENAME_MAX
-1);
244 * Pre-initialisation. This is here to get around the fact that GTK
245 * doesn't like being run in setuid/setgid programs (probably
246 * sensibly). So before we initialise GTK - and therefore before we
247 * even process the command line - we check to see if we're running
248 * set[ug]id. If so, we open our pty master _now_, chown it as
249 * necessary, and drop privileges. We can always close it again
250 * later. If we're potentially going to be doing utmp as well, we
251 * also fork off a utmp helper process and communicate with it by
252 * means of a pipe; the utmp helper will keep privileges in order
253 * to clean up utmp when we exit (i.e. when its end of our pipe
256 void pty_pre_init(void)
261 /* set the child signal handler straight away; it needs to be set
262 * before we ever fork. */
263 putty_signal(SIGCHLD
, sigchld_handler
);
266 if (geteuid() != getuid() || getegid() != getgid()) {
272 * Fork off the utmp helper.
274 if (pipe(pipefd
) < 0) {
275 perror("pterm: pipe");
280 perror("pterm: fork");
282 } else if (pid
== 0) {
283 char display
[128], buffer
[128];
288 * Now sit here until we receive a display name from the
289 * other end of the pipe, and then stamp utmp. Unstamp utmp
290 * again, and exit, when the pipe closes.
296 ret
= read(pipefd
[0], buffer
, lenof(buffer
));
300 } else if (!pty_stamped_utmp
) {
301 if (dlen
< lenof(display
))
302 memcpy(display
+dlen
, buffer
,
303 min(ret
, lenof(display
)-dlen
));
304 if (buffer
[ret
-1] == '\0') {
306 * Now we have a display name. NUL-terminate
307 * it, and stamp utmp.
309 display
[lenof(display
)-1] = '\0';
311 * Trap as many fatal signals as we can in the
312 * hope of having the best possible chance to
313 * clean up utmp before termination. We are
314 * unfortunately unprotected against SIGKILL,
317 putty_signal(SIGHUP
, fatal_sig_handler
);
318 putty_signal(SIGINT
, fatal_sig_handler
);
319 putty_signal(SIGQUIT
, fatal_sig_handler
);
320 putty_signal(SIGILL
, fatal_sig_handler
);
321 putty_signal(SIGABRT
, fatal_sig_handler
);
322 putty_signal(SIGFPE
, fatal_sig_handler
);
323 putty_signal(SIGPIPE
, fatal_sig_handler
);
324 putty_signal(SIGALRM
, fatal_sig_handler
);
325 putty_signal(SIGTERM
, fatal_sig_handler
);
326 putty_signal(SIGSEGV
, fatal_sig_handler
);
327 putty_signal(SIGUSR1
, fatal_sig_handler
);
328 putty_signal(SIGUSR2
, fatal_sig_handler
);
330 putty_signal(SIGBUS
, fatal_sig_handler
);
333 putty_signal(SIGPOLL
, fatal_sig_handler
);
336 putty_signal(SIGPROF
, fatal_sig_handler
);
339 putty_signal(SIGSYS
, fatal_sig_handler
);
342 putty_signal(SIGTRAP
, fatal_sig_handler
);
345 putty_signal(SIGVTALRM
, fatal_sig_handler
);
348 putty_signal(SIGXCPU
, fatal_sig_handler
);
351 putty_signal(SIGXFSZ
, fatal_sig_handler
);
354 putty_signal(SIGIO
, fatal_sig_handler
);
356 setup_utmp(pty_name
, display
);
362 pty_utmp_helper_pid
= pid
;
363 pty_utmp_helper_pipe
= pipefd
[1];
369 int gid
= getgid(), uid
= getuid();
370 #ifndef HAVE_NO_SETRESUID
371 int setresgid(gid_t
, gid_t
, gid_t
);
372 int setresuid(uid_t
, uid_t
, uid_t
);
373 setresgid(gid
, gid
, gid
);
374 setresuid(uid
, uid
, uid
);
383 * Called to set up the pty.
385 * Returns an error message, or NULL on success.
387 * Also places the canonical host name into `realhost'. It must be
388 * freed by the caller.
390 static char *pty_init(void *frontend
, void **backend_handle
,
391 char *host
, int port
, char **realhost
, int nodelay
)
396 pty_frontend
= frontend
;
397 *backend_handle
= NULL
; /* we can't sensibly use this, sadly */
399 pty_term_width
= cfg
.width
;
400 pty_term_height
= cfg
.height
;
402 if (pty_master_fd
< 0)
406 * Set the backspace character to be whichever of ^H and ^? is
407 * specified by bksp_is_delete.
410 struct termios attrs
;
411 tcgetattr(pty_master_fd
, &attrs
);
412 attrs
.c_cc
[VERASE
] = cfg
.bksp_is_delete ?
'\177' : '\010';
413 tcsetattr(pty_master_fd
, TCSANOW
, &attrs
);
417 * Stamp utmp (that is, tell the utmp helper process to do so),
421 close(pty_utmp_helper_pipe
); /* just let the child process die */
423 char *location
= get_x_display(pty_frontend
);
424 int len
= strlen(location
)+1, pos
= 0; /* +1 to include NUL */
426 int ret
= write(pty_utmp_helper_pipe
, location
+pos
, len
- pos
);
428 perror("pterm: writing to utmp helper process");
429 close(pty_utmp_helper_pipe
); /* arrgh, just give up */
437 * Fork and execute the command.
451 slavefd
= open(pty_name
, O_RDWR
);
453 perror("slave pty: open");
457 close(pty_master_fd
);
458 fcntl(slavefd
, F_SETFD
, 0); /* don't close on exec */
463 ioctl(slavefd
, TIOCSCTTY
, 1);
465 tcsetpgrp(slavefd
, pgrp
);
467 close(open(pty_name
, O_WRONLY
, 0));
469 /* Close everything _else_, for tidiness. */
470 for (i
= 3; i
< 1024; i
++)
473 char term_env_var
[10 + sizeof(cfg
.termtype
)];
474 sprintf(term_env_var
, "TERM=%s", cfg
.termtype
);
475 putenv(term_env_var
);
478 * SIGINT and SIGQUIT may have been set to ignored by our
479 * parent, particularly by things like sh -c 'pterm &' and
480 * some window managers. Reverse this for our child process.
482 putty_signal(SIGINT
, SIG_DFL
);
483 putty_signal(SIGQUIT
, SIG_DFL
);
485 execvp(pty_argv
[0], pty_argv
);
487 char *shell
= getenv("SHELL");
489 if (cfg
.login_shell
) {
490 char *p
= strrchr(shell
, '/');
491 shellname
= smalloc(2+strlen(shell
));
493 sprintf(shellname
, "-%s", p
);
496 execl(getenv("SHELL"), shellname
, NULL
);
500 * If we're here, exec has gone badly foom.
506 pty_child_dead
= FALSE
;
513 * Called to send data down the pty.
515 static int pty_send(void *handle
, char *buf
, int len
)
517 if (pty_master_fd
< 0)
518 return 0; /* ignore all writes if fd closed */
521 int ret
= write(pty_master_fd
, buf
, len
);
523 perror("write pty master");
534 if (pty_master_fd
>= 0) {
535 close(pty_master_fd
);
538 close(pty_utmp_helper_pipe
); /* this causes utmp to be cleaned up */
542 * Called to query the current socket sendability status.
544 static int pty_sendbuffer(void *handle
)
550 * Called to set the size of the window
552 static void pty_size(void *handle
, int width
, int height
)
556 pty_term_width
= width
;
557 pty_term_height
= height
;
559 size
.ws_row
= (unsigned short)pty_term_height
;
560 size
.ws_col
= (unsigned short)pty_term_width
;
561 size
.ws_xpixel
= (unsigned short) pty_term_width
*
562 font_dimension(pty_frontend
, 0);
563 size
.ws_ypixel
= (unsigned short) pty_term_height
*
564 font_dimension(pty_frontend
, 1);
565 ioctl(pty_master_fd
, TIOCSWINSZ
, (void *)&size
);
570 * Send special codes.
572 static void pty_special(void *handle
, Telnet_Special code
)
578 static Socket
pty_socket(void *handle
)
580 return NULL
; /* shouldn't ever be needed */
583 static int pty_sendok(void *handle
)
588 static void pty_unthrottle(void *handle
, int backlog
)
593 static int pty_ldisc(void *handle
, int option
)
595 return 0; /* neither editing nor echoing */
598 static void pty_provide_ldisc(void *handle
, void *ldisc
)
600 /* This is a stub. */
603 static void pty_provide_logctx(void *handle
, void *logctx
)
605 /* This is a stub. */
608 static int pty_exitcode(void *handle
)
611 return -1; /* not dead yet */
613 return pty_exit_code
;
616 Backend pty_backend
= {