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Take control of the tty and save its settings before doing a policy check.

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Otherwise the policy plugin won't be able to read the password.
This commit is contained in:
Todd C. Miller
2021-08-09 15:50:25 -06:00
parent 42598735d0
commit 60e76e3e35
1 changed files with 28 additions and 1 deletions
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29
src/exec.c
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@@ -39,6 +39,7 @@
#include <fcntl.h>
#include <pwd.h>
#include <signal.h>
#include <termios.h>
#ifdef HAVE_LOGIN_CAP_H
# include <login_cap.h>
# ifndef LOGIN_SETENV
@@ -56,6 +57,11 @@
#include "sudo_plugin_int.h"
#include "intercept.pb-c.h"
/* TCSASOFT is a BSD extension that ignores control flags and speed. */
#ifndef TCSASOFT
# define TCSASOFT 0
#endif
static void intercept_cb(int fd, int what, void *v);
static void
@@ -674,9 +680,12 @@ intercept_read(int fd, struct intercept_closure *closure)
struct sudo_event_base *base = sudo_ev_get_base(&closure->ev);
InterceptMessage *msg = NULL;
uint8_t *cp, *buf = NULL;
pid_t saved_pgrp = -1;
struct termios oterm;
uint32_t msg_len;
ssize_t nread;
bool ret = false;
int ttyfd = -1;
ssize_t nread;
debug_decl(intercept_read, SUDO_DEBUG_EXEC);
/* Read message size (uint32_t in host byte order). */
@@ -729,9 +738,25 @@ intercept_read(int fd, struct intercept_closure *closure)
goto done;
}
/* Take back control of the tty, if necessary, for the policy check. */
ttyfd = open(_PATH_TTY, O_RDWR);
if (ttyfd != -1) {
saved_pgrp = tcgetpgrp(ttyfd);
if (saved_pgrp == -1 || tcsetpgrp(ttyfd, getpgid(0)) == -1 ||
tcgetattr(ttyfd, &oterm) == -1) {
close(ttyfd);
ttyfd = -1;
}
}
closure->policy_result = intercept_check_policy(msg->u.policy_check_req,
closure, &closure->errstr);
if (ttyfd != -1) {
(void)tcsetattr(ttyfd, TCSASOFT|TCSAFLUSH, &oterm);
(void)tcsetpgrp(ttyfd, saved_pgrp);
}
/* Switch event to write mode for the reply. */
if (sudo_ev_set(&closure->ev, fd, SUDO_EV_WRITE, intercept_cb, closure) == -1) {
/* This cannot (currently) fail. */
@@ -746,6 +771,8 @@ intercept_read(int fd, struct intercept_closure *closure)
ret = true;
done:
if (ttyfd != -1)
close(ttyfd);
intercept_message__free_unpacked(msg, NULL);
free(buf);
debug_return_bool(ret);