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Implement suspend/resume callbacks for the conversation function.

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If suspended, close the timestamp file (dropping all locks).  On
resume, lock the record before reading the password.

For this to work properly we need to be able to run th callback
when tsetattr() suspends us, not just when the user does.  To
accomplish this the term_* functions now return EINTR if SIGTTOU
would be generated.  The caller now has to restart the term_*
function (and send itself SIGTTOU) instead of it being done
automatically.
This commit is contained in:
Todd C. Miller
2015-09-07 06:06:08 -06:00
parent 00142c91fa
commit 0c70df5de9
4 changed files with 106 additions and 52 deletions
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68
src/tgetpass.c
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@@ -51,6 +51,24 @@ static void tgetpass_handler(int);
static char *getln(int, char *, size_t, int);
static char *sudo_askpass(const char *, const char *);
static int
suspend(int signo, struct sudo_conv_callback *callback)
{
int rval = 0;
debug_decl(suspend, SUDO_DEBUG_CONV)
if (callback != NULL && callback->on_suspend != NULL) {
if (callback->on_suspend(signo, callback->closure) == -1)
rval = -1;
}
kill(getpid(), signo);
if (callback != NULL && callback->on_resume != NULL) {
if (callback->on_resume(signo, callback->closure) == -1)
rval = -1;
}
debug_return_int(rval);
}
/*
* Like getpass(3) but with timeout and echo flags.
*/
@@ -106,13 +124,23 @@ restart:
/*
* If we are using a tty but are not the foreground pgrp this will
* generate SIGTTOU, so do it *before* installing the signal handlers.
* return EINTR. We send ourself SIGTTOU bracketed by callbacks.
*/
if (!ISSET(flags, TGP_ECHO)) {
if (ISSET(flags, TGP_MASK))
neednl = sudo_term_cbreak(input);
else
neednl = sudo_term_noecho(input);
for (;;) {
if (ISSET(flags, TGP_MASK))
neednl = sudo_term_cbreak(input);
else
neednl = sudo_term_noecho(input);
if (neednl || errno != EINTR)
break;
/* Received SIGTTOU, suspend the process. */
if (suspend(SIGTTOU, callback) == -1) {
if (input != STDIN_FILENO)
(void) close(input);
debug_return_ptr(NULL);
}
}
}
/*
@@ -154,8 +182,19 @@ restart:
restore:
/* Restore old tty settings and signals. */
if (!ISSET(flags, TGP_ECHO))
sudo_term_restore(input, 1);
if (!ISSET(flags, TGP_ECHO)) {
for (;;) {
/* Restore old tty settings if possible. */
if (sudo_term_restore(input, 1) || errno != EINTR)
break;
/* Received SIGTTOU, suspend the process. */
if (suspend(SIGTTOU, callback) == -1) {
if (input != STDIN_FILENO)
(void) close(input);
debug_return_ptr(NULL);
}
}
}
(void) sigaction(SIGALRM, &savealrm, NULL);
(void) sigaction(SIGINT, &saveint, NULL);
(void) sigaction(SIGHUP, &savehup, NULL);
@@ -178,18 +217,11 @@ restore:
case SIGTSTP:
case SIGTTIN:
case SIGTTOU:
if (callback != NULL && callback->on_suspend != NULL)
callback->on_suspend(i, callback->closure);
if (suspend(i, callback) == 0)
need_restart = 1;
break;
}
kill(getpid(), i);
switch (i) {
case SIGTSTP:
case SIGTTIN:
case SIGTTOU:
if (callback != NULL && callback->on_resume != NULL)
callback->on_resume(i, callback->closure);
need_restart = 1;
default:
kill(getpid(), i);
break;
}
}