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
;
172 pid
= waitpid(-1, &status
, WNOHANG
);
173 if (pid
== pty_child_pid
&& (WIFEXITED(status
) || WIFSIGNALED(status
))) {
174 pty_exit_code
= status
;
175 pty_child_dead
= TRUE
;
181 static void fatal_sig_handler(int signum
)
183 putty_signal(signum
, SIG_DFL
);
189 static void pty_open_master(void)
192 const char chars1
[] = "pqrstuvwxyz";
193 const char chars2
[] = "0123456789abcdef";
195 char master_name
[20];
198 for (p1
= chars1
; *p1
; p1
++)
199 for (p2
= chars2
; *p2
; p2
++) {
200 sprintf(master_name
, "/dev/pty%c%c", *p1
, *p2
);
201 pty_master_fd
= open(master_name
, O_RDWR
);
202 if (pty_master_fd
>= 0) {
203 if (geteuid() == 0 ||
204 access(master_name
, R_OK
| W_OK
) == 0)
206 close(pty_master_fd
);
210 /* If we get here, we couldn't get a tty at all. */
211 fprintf(stderr
, "pterm: unable to open a pseudo-terminal device\n");
215 strcpy(pty_name
, master_name
);
216 pty_name
[5] = 't'; /* /dev/ptyXX -> /dev/ttyXX */
218 /* We need to chown/chmod the /dev/ttyXX device. */
219 gp
= getgrnam("tty");
220 chown(pty_name
, getuid(), gp ? gp
->gr_gid
: -1);
221 chmod(pty_name
, 0600);
223 pty_master_fd
= open("/dev/ptmx", O_RDWR
);
225 if (pty_master_fd
< 0) {
226 perror("/dev/ptmx: open");
230 if (grantpt(pty_master_fd
) < 0) {
235 if (unlockpt(pty_master_fd
) < 0) {
240 pty_name
[FILENAME_MAX
-1] = '\0';
241 strncpy(pty_name
, ptsname(pty_master_fd
), FILENAME_MAX
-1);
246 * Pre-initialisation. This is here to get around the fact that GTK
247 * doesn't like being run in setuid/setgid programs (probably
248 * sensibly). So before we initialise GTK - and therefore before we
249 * even process the command line - we check to see if we're running
250 * set[ug]id. If so, we open our pty master _now_, chown it as
251 * necessary, and drop privileges. We can always close it again
252 * later. If we're potentially going to be doing utmp as well, we
253 * also fork off a utmp helper process and communicate with it by
254 * means of a pipe; the utmp helper will keep privileges in order
255 * to clean up utmp when we exit (i.e. when its end of our pipe
258 void pty_pre_init(void)
263 /* set the child signal handler straight away; it needs to be set
264 * before we ever fork. */
265 putty_signal(SIGCHLD
, sigchld_handler
);
268 if (geteuid() != getuid() || getegid() != getgid()) {
274 * Fork off the utmp helper.
276 if (pipe(pipefd
) < 0) {
277 perror("pterm: pipe");
282 perror("pterm: fork");
284 } else if (pid
== 0) {
285 char display
[128], buffer
[128];
290 * Now sit here until we receive a display name from the
291 * other end of the pipe, and then stamp utmp. Unstamp utmp
292 * again, and exit, when the pipe closes.
298 ret
= read(pipefd
[0], buffer
, lenof(buffer
));
302 } else if (!pty_stamped_utmp
) {
303 if (dlen
< lenof(display
))
304 memcpy(display
+dlen
, buffer
,
305 min(ret
, lenof(display
)-dlen
));
306 if (buffer
[ret
-1] == '\0') {
308 * Now we have a display name. NUL-terminate
309 * it, and stamp utmp.
311 display
[lenof(display
)-1] = '\0';
313 * Trap as many fatal signals as we can in the
314 * hope of having the best possible chance to
315 * clean up utmp before termination. We are
316 * unfortunately unprotected against SIGKILL,
319 putty_signal(SIGHUP
, fatal_sig_handler
);
320 putty_signal(SIGINT
, fatal_sig_handler
);
321 putty_signal(SIGQUIT
, fatal_sig_handler
);
322 putty_signal(SIGILL
, fatal_sig_handler
);
323 putty_signal(SIGABRT
, fatal_sig_handler
);
324 putty_signal(SIGFPE
, fatal_sig_handler
);
325 putty_signal(SIGPIPE
, fatal_sig_handler
);
326 putty_signal(SIGALRM
, fatal_sig_handler
);
327 putty_signal(SIGTERM
, fatal_sig_handler
);
328 putty_signal(SIGSEGV
, fatal_sig_handler
);
329 putty_signal(SIGUSR1
, fatal_sig_handler
);
330 putty_signal(SIGUSR2
, fatal_sig_handler
);
332 putty_signal(SIGBUS
, fatal_sig_handler
);
335 putty_signal(SIGPOLL
, fatal_sig_handler
);
338 putty_signal(SIGPROF
, fatal_sig_handler
);
341 putty_signal(SIGSYS
, fatal_sig_handler
);
344 putty_signal(SIGTRAP
, fatal_sig_handler
);
347 putty_signal(SIGVTALRM
, fatal_sig_handler
);
350 putty_signal(SIGXCPU
, fatal_sig_handler
);
353 putty_signal(SIGXFSZ
, fatal_sig_handler
);
356 putty_signal(SIGIO
, fatal_sig_handler
);
358 setup_utmp(pty_name
, display
);
364 pty_utmp_helper_pid
= pid
;
365 pty_utmp_helper_pipe
= pipefd
[1];
371 int gid
= getgid(), uid
= getuid();
372 #ifndef HAVE_NO_SETRESUID
373 int setresgid(gid_t
, gid_t
, gid_t
);
374 int setresuid(uid_t
, uid_t
, uid_t
);
375 setresgid(gid
, gid
, gid
);
376 setresuid(uid
, uid
, uid
);
385 * Called to set up the pty.
387 * Returns an error message, or NULL on success.
389 * Also places the canonical host name into `realhost'. It must be
390 * freed by the caller.
392 static char *pty_init(void *frontend
, void **backend_handle
, Config
*cfg
,
393 char *host
, int port
, char **realhost
, int nodelay
)
398 pty_frontend
= frontend
;
399 *backend_handle
= NULL
; /* we can't sensibly use this, sadly */
401 pty_term_width
= cfg
->width
;
402 pty_term_height
= cfg
->height
;
404 if (pty_master_fd
< 0)
408 * Set the backspace character to be whichever of ^H and ^? is
409 * specified by bksp_is_delete.
412 struct termios attrs
;
413 tcgetattr(pty_master_fd
, &attrs
);
414 attrs
.c_cc
[VERASE
] = cfg
->bksp_is_delete ?
'\177' : '\010';
415 tcsetattr(pty_master_fd
, TCSANOW
, &attrs
);
419 * Stamp utmp (that is, tell the utmp helper process to do so),
422 if (!cfg
->stamp_utmp
)
423 close(pty_utmp_helper_pipe
); /* just let the child process die */
425 char *location
= get_x_display(pty_frontend
);
426 int len
= strlen(location
)+1, pos
= 0; /* +1 to include NUL */
428 int ret
= write(pty_utmp_helper_pipe
, location
+pos
, len
- pos
);
430 perror("pterm: writing to utmp helper process");
431 close(pty_utmp_helper_pipe
); /* arrgh, just give up */
439 * Fork and execute the command.
453 slavefd
= open(pty_name
, O_RDWR
);
455 perror("slave pty: open");
459 close(pty_master_fd
);
460 fcntl(slavefd
, F_SETFD
, 0); /* don't close on exec */
465 ioctl(slavefd
, TIOCSCTTY
, 1);
467 tcsetpgrp(slavefd
, pgrp
);
469 close(open(pty_name
, O_WRONLY
, 0));
471 /* Close everything _else_, for tidiness. */
472 for (i
= 3; i
< 1024; i
++)
475 char term_env_var
[10 + sizeof(cfg
->termtype
)];
476 sprintf(term_env_var
, "TERM=%s", cfg
->termtype
);
477 putenv(term_env_var
);
480 * SIGINT and SIGQUIT may have been set to ignored by our
481 * parent, particularly by things like sh -c 'pterm &' and
482 * some window managers. Reverse this for our child process.
484 putty_signal(SIGINT
, SIG_DFL
);
485 putty_signal(SIGQUIT
, SIG_DFL
);
487 execvp(pty_argv
[0], pty_argv
);
489 char *shell
= getenv("SHELL");
491 if (cfg
->login_shell
) {
492 char *p
= strrchr(shell
, '/');
493 shellname
= smalloc(2+strlen(shell
));
495 sprintf(shellname
, "-%s", p
);
498 execl(getenv("SHELL"), shellname
, NULL
);
502 * If we're here, exec has gone badly foom.
508 pty_child_dead
= FALSE
;
515 * Stub routine (we don't have any need to reconfigure this backend).
517 static void pty_reconfig(void *handle
, Config
*cfg
)
522 * Stub routine (never called in pterm
524 static void pty_free(void *handle
)
530 * Called to send data down the pty.
532 static int pty_send(void *handle
, char *buf
, int len
)
534 if (pty_master_fd
< 0)
535 return 0; /* ignore all writes if fd closed */
538 int ret
= write(pty_master_fd
, buf
, len
);
540 perror("write pty master");
551 if (pty_master_fd
>= 0) {
552 close(pty_master_fd
);
555 close(pty_utmp_helper_pipe
); /* this causes utmp to be cleaned up */
559 * Called to query the current socket sendability status.
561 static int pty_sendbuffer(void *handle
)
567 * Called to set the size of the window
569 static void pty_size(void *handle
, int width
, int height
)
573 pty_term_width
= width
;
574 pty_term_height
= height
;
576 size
.ws_row
= (unsigned short)pty_term_height
;
577 size
.ws_col
= (unsigned short)pty_term_width
;
578 size
.ws_xpixel
= (unsigned short) pty_term_width
*
579 font_dimension(pty_frontend
, 0);
580 size
.ws_ypixel
= (unsigned short) pty_term_height
*
581 font_dimension(pty_frontend
, 1);
582 ioctl(pty_master_fd
, TIOCSWINSZ
, (void *)&size
);
587 * Send special codes.
589 static void pty_special(void *handle
, Telnet_Special code
)
595 static Socket
pty_socket(void *handle
)
597 return NULL
; /* shouldn't ever be needed */
600 static int pty_sendok(void *handle
)
605 static void pty_unthrottle(void *handle
, int backlog
)
610 static int pty_ldisc(void *handle
, int option
)
612 return 0; /* neither editing nor echoing */
615 static void pty_provide_ldisc(void *handle
, void *ldisc
)
617 /* This is a stub. */
620 static void pty_provide_logctx(void *handle
, void *logctx
)
622 /* This is a stub. */
625 static int pty_exitcode(void *handle
)
628 return -1; /* not dead yet */
630 return pty_exit_code
;
633 Backend pty_backend
= {