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867fd16343a9650ceee83ad710b28dc642e4466c
sudo/src/exec_pty.c
Todd C. Miller 867fd16343 Move SIGCHLD handling into handle_sigchld() functions and move the 
remaining bits of dispatch_signal() into signal_pipe_cb()
2017-03-09 08:36:40 -07:00

1521 lines
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/*
* Copyright (c) 2009-2017 Todd C. Miller <Todd.Miller@courtesan.com>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <config.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <sys/ioctl.h>
#include <stdio.h>
#include <stdlib.h>
#ifdef HAVE_STRING_H
# include <string.h>
#endif /* HAVE_STRING_H */
#ifdef HAVE_STRINGS_H
# include <strings.h>
#endif /* HAVE_STRINGS_H */
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include "sudo.h"
#include "sudo_event.h"
#include "sudo_exec.h"
#include "sudo_plugin.h"
#include "sudo_plugin_int.h"
/* Evaluates to true if the event has /dev/tty as its fd. */
#define USERTTY_EVENT(_ev) (sudo_ev_get_fd((_ev)) == io_fds[SFD_USERTTY])
#define TERM_COOKED 0
#define TERM_RAW 1
/* We keep a tailq of signals to forward to child. */
struct sigforward {
TAILQ_ENTRY(sigforward) entries;
int signo;
};
TAILQ_HEAD(sigfwd_list, sigforward);
struct exec_closure_pty {
pid_t child;
sigset_t *omask;
struct command_status *cstat;
struct command_details *details;
struct sudo_event_base *evbase;
struct sudo_event *signal_event;
struct sudo_event *sigfwd_event;
struct sudo_event *backchannel_event;
struct sigfwd_list sigfwd_list;
};
/*
* I/O buffer with associated read/write events and a logging action.
* Used to, e.g. pass data from the pty to the user's terminal
* and any I/O logging plugins.
*/
struct io_buffer;
typedef bool (*sudo_io_action_t)(const char *, unsigned int, struct io_buffer *);
struct io_buffer {
SLIST_ENTRY(io_buffer) entries;
struct sudo_event *revent;
struct sudo_event *wevent;
sudo_io_action_t action;
int len; /* buffer length (how much produced) */
int off; /* write position (how much already consumed) */
char buf[64 * 1024];
};
SLIST_HEAD(io_buffer_list, io_buffer);
static char slavename[PATH_MAX];
int io_fds[6] = { -1, -1, -1, -1, -1, -1}; /* XXX - sudo_exec.h? */
static bool foreground, pipeline;
static bool tty_initialized;
static int ttymode = TERM_COOKED;
static sigset_t ttyblock;
static struct io_buffer_list iobufs;
static const char *utmp_user;
static int fork_pty(struct command_details *details, int sv[], sigset_t *omask);
static void del_io_events(bool nonblocking);
static void sigwinch(int s);
static void sync_ttysize(int src, int dst);
static int safe_close(int fd);
static void ev_free_by_fd(struct sudo_event_base *evbase, int fd);
static void check_foreground(void);
static void add_io_events(struct sudo_event_base *evbase);
/*
* Cleanup hook for sudo_fatal()/sudo_fatalx()
*/
void
pty_cleanup(void)
{
debug_decl(cleanup, SUDO_DEBUG_EXEC);
if (!TAILQ_EMPTY(&io_plugins) && io_fds[SFD_USERTTY] != -1)
sudo_term_restore(io_fds[SFD_USERTTY], false);
if (utmp_user != NULL)
utmp_logout(slavename, 0);
debug_return;
}
/*
* Allocate a pty if /dev/tty is a tty.
* Fills in io_fds[SFD_USERTTY], io_fds[SFD_MASTER], io_fds[SFD_SLAVE]
* and slavename globals.
*/
static void
pty_setup(uid_t uid, const char *tty)
{
debug_decl(pty_setup, SUDO_DEBUG_EXEC);
io_fds[SFD_USERTTY] = open(_PATH_TTY, O_RDWR);
if (io_fds[SFD_USERTTY] != -1) {
if (!get_pty(&io_fds[SFD_MASTER], &io_fds[SFD_SLAVE],
slavename, sizeof(slavename), uid))
sudo_fatal(U_("unable to allocate pty"));
/* Add entry to utmp/utmpx? */
if (utmp_user != NULL)
utmp_login(tty, slavename, io_fds[SFD_SLAVE], utmp_user);
sudo_debug_printf(SUDO_DEBUG_INFO,
"%s: /dev/tty fd %d, pty master fd %d, pty slave fd %d", __func__,
io_fds[SFD_USERTTY], io_fds[SFD_MASTER], io_fds[SFD_SLAVE]);
}
debug_return;
}
int
pty_make_controlling(void)
{
if (io_fds[SFD_USERTTY] != -1) {
#ifdef TIOCSCTTY
if (ioctl(io_fds[SFD_SLAVE], TIOCSCTTY, NULL) != 0)
return -1;
#else
/* Set controlling tty by reopening slave. */
int fd = open(slavename, O_RDWR);
if (fd == -1)
return -1;
close(fd);
#endif
}
return 0;
}
/* Call I/O plugin tty input log method. */
static bool
log_ttyin(const char *buf, unsigned int n, struct io_buffer *iob)
{
struct plugin_container *plugin;
sigset_t omask;
bool ret = true;
debug_decl(log_ttyin, SUDO_DEBUG_EXEC);
sigprocmask(SIG_BLOCK, &ttyblock, &omask);
TAILQ_FOREACH(plugin, &io_plugins, entries) {
if (plugin->u.io->log_ttyin) {
int rc;
sudo_debug_set_active_instance(plugin->debug_instance);
rc = plugin->u.io->log_ttyin(buf, n);
if (rc <= 0) {
if (rc < 0) {
/* Error: disable plugin's I/O function. */
plugin->u.io->log_ttyin = NULL;
}
break;
}
}
}
sudo_debug_set_active_instance(sudo_debug_instance);
sigprocmask(SIG_SETMASK, &omask, NULL);
debug_return_bool(ret);
}
/* Call I/O plugin stdin log method. */
static bool
log_stdin(const char *buf, unsigned int n, struct io_buffer *iob)
{
struct plugin_container *plugin;
sigset_t omask;
bool ret = true;
debug_decl(log_stdin, SUDO_DEBUG_EXEC);
sigprocmask(SIG_BLOCK, &ttyblock, &omask);
TAILQ_FOREACH(plugin, &io_plugins, entries) {
if (plugin->u.io->log_stdin) {
int rc;
sudo_debug_set_active_instance(plugin->debug_instance);
rc = plugin->u.io->log_stdin(buf, n);
if (rc <= 0) {
if (rc < 0) {
/* Error: disable plugin's I/O function. */
plugin->u.io->log_stdin = NULL;
}
break;
}
}
}
sudo_debug_set_active_instance(sudo_debug_instance);
sigprocmask(SIG_SETMASK, &omask, NULL);
debug_return_bool(ret);
}
/* Call I/O plugin tty output log method. */
static bool
log_ttyout(const char *buf, unsigned int n, struct io_buffer *iob)
{
struct plugin_container *plugin;
sigset_t omask;
bool ret = true;
debug_decl(log_ttyout, SUDO_DEBUG_EXEC);
sigprocmask(SIG_BLOCK, &ttyblock, &omask);
TAILQ_FOREACH(plugin, &io_plugins, entries) {
if (plugin->u.io->log_ttyout) {
int rc;
sudo_debug_set_active_instance(plugin->debug_instance);
rc = plugin->u.io->log_ttyout(buf, n);
if (rc <= 0) {
if (rc < 0) {
/* Error: disable plugin's I/O function. */
plugin->u.io->log_ttyout = NULL;
}
break;
}
}
}
sudo_debug_set_active_instance(sudo_debug_instance);
if (!ret) {
/*
* I/O plugin rejected the output, delete the write event
* (user's tty) so we do not display the rejected output.
*/
sudo_debug_printf(SUDO_DEBUG_INFO,
"%s: deleting and freeing devtty wevent %p", __func__, iob->wevent);
sudo_ev_del(NULL, iob->wevent);
sudo_ev_free(iob->wevent);
iob->wevent = NULL;
iob->off = iob->len = 0;
}
sigprocmask(SIG_SETMASK, &omask, NULL);
debug_return_bool(ret);
}
/* Call I/O plugin stdout log method. */
static bool
log_stdout(const char *buf, unsigned int n, struct io_buffer *iob)
{
struct plugin_container *plugin;
sigset_t omask;
bool ret = true;
debug_decl(log_stdout, SUDO_DEBUG_EXEC);
sigprocmask(SIG_BLOCK, &ttyblock, &omask);
TAILQ_FOREACH(plugin, &io_plugins, entries) {
if (plugin->u.io->log_stdout) {
int rc;
sudo_debug_set_active_instance(plugin->debug_instance);
rc = plugin->u.io->log_stdout(buf, n);
if (rc <= 0) {
if (rc < 0) {
/* Error: disable plugin's I/O function. */
plugin->u.io->log_stdout = NULL;
}
break;
}
}
}
sudo_debug_set_active_instance(sudo_debug_instance);
if (!ret) {
/*
* I/O plugin rejected the output, delete the write event
* (user's stdout) so we do not display the rejected output.
*/
sudo_debug_printf(SUDO_DEBUG_INFO,
"%s: deleting and freeing stdout wevent %p", __func__, iob->wevent);
sudo_ev_del(NULL, iob->wevent);
sudo_ev_free(iob->wevent);
iob->wevent = NULL;
iob->off = iob->len = 0;
}
sigprocmask(SIG_SETMASK, &omask, NULL);
debug_return_bool(ret);
}
/* Call I/O plugin stderr log method. */
static bool
log_stderr(const char *buf, unsigned int n, struct io_buffer *iob)
{
struct plugin_container *plugin;
sigset_t omask;
bool ret = true;
debug_decl(log_stderr, SUDO_DEBUG_EXEC);
sigprocmask(SIG_BLOCK, &ttyblock, &omask);
TAILQ_FOREACH(plugin, &io_plugins, entries) {
if (plugin->u.io->log_stderr) {
int rc;
sudo_debug_set_active_instance(plugin->debug_instance);
rc = plugin->u.io->log_stderr(buf, n);
if (rc <= 0) {
if (rc < 0) {
/* Error: disable plugin's I/O function. */
plugin->u.io->log_stderr = NULL;
}
break;
}
}
}
sudo_debug_set_active_instance(sudo_debug_instance);
if (!ret) {
/*
* I/O plugin rejected the output, delete the write event
* (user's stderr) so we do not display the rejected output.
*/
sudo_debug_printf(SUDO_DEBUG_INFO,
"%s: deleting and freeing stderr wevent %p", __func__, iob->wevent);
sudo_ev_del(NULL, iob->wevent);
sudo_ev_free(iob->wevent);
iob->wevent = NULL;
iob->off = iob->len = 0;
}
sigprocmask(SIG_SETMASK, &omask, NULL);
debug_return_bool(ret);
}
/*
* Check whether we are running in the foregroup.
* Updates the foreground global and does lazy init of the
* the pty slave as needed.
*/
static void
check_foreground(void)
{
debug_decl(check_foreground, SUDO_DEBUG_EXEC);
if (io_fds[SFD_USERTTY] != -1) {
foreground = tcgetpgrp(io_fds[SFD_USERTTY]) == ppgrp;
if (foreground && !tty_initialized) {
if (sudo_term_copy(io_fds[SFD_USERTTY], io_fds[SFD_SLAVE])) {
tty_initialized = true;
sync_ttysize(io_fds[SFD_USERTTY], io_fds[SFD_SLAVE]);
}
}
}
debug_return;
}
/*
* Suspend sudo if the underlying command is suspended.
* Returns SIGCONT_FG if the command should be resumed in the
* foreground or SIGCONT_BG if it is a background process.
*/
static int
suspend_sudo(int signo)
{
char signame[SIG2STR_MAX];
sigaction_t sa, osa;
int ret = 0;
debug_decl(suspend_sudo, SUDO_DEBUG_EXEC);
switch (signo) {
case SIGTTOU:
case SIGTTIN:
/*
* If sudo is already the foreground process, just resume the command
* in the foreground. If not, we'll suspend sudo and resume later.
*/
if (!foreground)
check_foreground();
if (foreground) {
if (ttymode != TERM_RAW) {
if (sudo_term_raw(io_fds[SFD_USERTTY], 0))
ttymode = TERM_RAW;
}
ret = SIGCONT_FG; /* resume command in foreground */
break;
}
/* FALLTHROUGH */
case SIGSTOP:
case SIGTSTP:
/* Flush any remaining output and deschedule I/O events. */
del_io_events(true);
/* Restore original tty mode before suspending. */
if (ttymode != TERM_COOKED)
sudo_term_restore(io_fds[SFD_USERTTY], false);
if (sig2str(signo, signame) == -1)
snprintf(signame, sizeof(signame), "%d", signo);
/* Suspend self and continue command when we resume. */
if (signo != SIGSTOP) {
memset(&sa, 0, sizeof(sa));
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART;
sa.sa_handler = SIG_DFL;
if (sudo_sigaction(signo, &sa, &osa) != 0)
sudo_warn(U_("unable to set handler for signal %d"), signo);
}
sudo_debug_printf(SUDO_DEBUG_INFO, "kill parent SIG%s", signame);
if (killpg(ppgrp, signo) != 0)
sudo_warn("killpg(%d, SIG%s)", (int)ppgrp, signame);
/* Check foreground/background status on resume. */
check_foreground();
/*
* We always resume the command in the foreground if sudo itself
* is the foreground process. This helps work around poorly behaved
* programs that catch SIGTTOU/SIGTTIN but suspend themselves with
* SIGSTOP. At worst, sudo will go into the background but upon
* resume the command will be runnable. Otherwise, we can get into
* a situation where the command will immediately suspend itself.
*/
sudo_debug_printf(SUDO_DEBUG_INFO, "parent is in %s, ttymode %d -> %d",
foreground ? "foreground" : "background", ttymode,
foreground ? TERM_RAW : TERM_COOKED);
if (foreground) {
/* Foreground process, set tty to raw mode. */
if (sudo_term_raw(io_fds[SFD_USERTTY], 0))
ttymode = TERM_RAW;
} else {
/* Background process, no access to tty. */
ttymode = TERM_COOKED;
}
if (signo != SIGSTOP) {
if (sudo_sigaction(signo, &osa, NULL) != 0)
sudo_warn(U_("unable to restore handler for signal %d"), signo);
}
ret = ttymode == TERM_RAW ? SIGCONT_FG : SIGCONT_BG;
break;
}
debug_return_int(ret);
}
/*
* Read an iobuf that is ready.
*/
static void
read_callback(int fd, int what, void *v)
{
struct io_buffer *iob = v;
struct sudo_event_base *evbase;
int n;
debug_decl(read_callback, SUDO_DEBUG_EXEC);
evbase = sudo_ev_get_base(iob->revent);
do {
n = read(fd, iob->buf + iob->len, sizeof(iob->buf) - iob->len);
} while (n == -1 && errno == EINTR);
switch (n) {
case -1:
if (errno == EAGAIN)
break;
/* treat read error as fatal and close the fd */
sudo_debug_printf(SUDO_DEBUG_ERROR,
"error reading fd %d: %s", fd, strerror(errno));
/* FALLTHROUGH */
case 0:
/* got EOF or pty has gone away */
if (n == 0) {
sudo_debug_printf(SUDO_DEBUG_INFO,
"read EOF from fd %d", fd);
}
safe_close(fd);
ev_free_by_fd(evbase, fd);
/* If writer already consumed the buffer, close it too. */
if (iob->wevent != NULL && iob->off == iob->len) {
safe_close(sudo_ev_get_fd(iob->wevent));
ev_free_by_fd(evbase, sudo_ev_get_fd(iob->wevent));
iob->off = iob->len = 0;
}
break;
default:
sudo_debug_printf(SUDO_DEBUG_INFO,
"read %d bytes from fd %d", n, fd);
if (!iob->action(iob->buf + iob->len, n, iob))
terminate_command(cmnd_pid, true);
iob->len += n;
/* Enable writer if not /dev/tty or we are foreground pgrp. */
if (iob->wevent != NULL &&
(foreground || !USERTTY_EVENT(iob->wevent))) {
if (sudo_ev_add(evbase, iob->wevent, NULL, false) == -1)
sudo_fatal(U_("unable to add event to queue"));
}
/* Re-enable reader if buffer is not full. */
if (iob->len != sizeof(iob->buf)) {
if (sudo_ev_add(evbase, iob->revent, NULL, false) == -1)
sudo_fatal(U_("unable to add event to queue"));
}
break;
}
}
/*
* Write an iobuf that is ready.
*/
static void
write_callback(int fd, int what, void *v)
{
struct io_buffer *iob = v;
struct sudo_event_base *evbase;
int n;
debug_decl(write_callback, SUDO_DEBUG_EXEC);
evbase = sudo_ev_get_base(iob->wevent);
do {
n = write(fd, iob->buf + iob->off, iob->len - iob->off);
} while (n == -1 && errno == EINTR);
if (n == -1) {
switch (errno) {
case EPIPE:
case ENXIO:
case EIO:
case EBADF:
/* other end of pipe closed or pty revoked */
sudo_debug_printf(SUDO_DEBUG_INFO,
"unable to write %d bytes to fd %d",
iob->len - iob->off, fd);
/* Close reader if there is one. */
if (iob->revent != NULL) {
safe_close(sudo_ev_get_fd(iob->revent));
ev_free_by_fd(evbase, sudo_ev_get_fd(iob->revent));
}
safe_close(fd);
ev_free_by_fd(evbase, fd);
break;
case EAGAIN:
/* not an error */
break;
default:
#if 0 /* XXX -- how to set cstat? stash in iobufs instead? */
if (cstat != NULL) {
cstat->type = CMD_ERRNO;
cstat->val = errno;
}
#endif /* XXX */
sudo_debug_printf(SUDO_DEBUG_ERROR,
"error writing fd %d: %s", fd, strerror(errno));
sudo_ev_loopbreak(evbase);
break;
}
} else {
sudo_debug_printf(SUDO_DEBUG_INFO,
"wrote %d bytes to fd %d", n, fd);
iob->off += n;
/* Reset buffer if fully consumed. */
if (iob->off == iob->len) {
iob->off = iob->len = 0;
/* Forward the EOF from reader to writer. */
if (iob->revent == NULL) {
safe_close(fd);
ev_free_by_fd(evbase, fd);
}
}
/* Re-enable writer if buffer is not empty. */
if (iob->len > iob->off) {
if (sudo_ev_add(evbase, iob->wevent, NULL, false) == -1)
sudo_fatal(U_("unable to add event to queue"));
}
/* Enable reader if buffer is not full. */
if (iob->revent != NULL &&
(ttymode == TERM_RAW || !USERTTY_EVENT(iob->revent))) {
if (iob->len != sizeof(iob->buf)) {
if (sudo_ev_add(evbase, iob->revent, NULL, false) == -1)
sudo_fatal(U_("unable to add event to queue"));
}
}
}
}
static void
io_buf_new(int rfd, int wfd,
bool (*action)(const char *, unsigned int, struct io_buffer *),
struct io_buffer_list *head)
{
int n;
struct io_buffer *iob;
debug_decl(io_buf_new, SUDO_DEBUG_EXEC);
/* Set non-blocking mode. */
n = fcntl(rfd, F_GETFL, 0);
if (n != -1 && !ISSET(n, O_NONBLOCK))
(void) fcntl(rfd, F_SETFL, n | O_NONBLOCK);
n = fcntl(wfd, F_GETFL, 0);
if (n != -1 && !ISSET(n, O_NONBLOCK))
(void) fcntl(wfd, F_SETFL, n | O_NONBLOCK);
/* Allocate and add to head of list. */
if ((iob = malloc(sizeof(*iob))) == NULL)
sudo_fatalx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
iob->revent = sudo_ev_alloc(rfd, SUDO_EV_READ, read_callback, iob);
iob->wevent = sudo_ev_alloc(wfd, SUDO_EV_WRITE, write_callback, iob);
iob->len = 0;
iob->off = 0;
iob->action = action;
iob->buf[0] = '\0';
if (iob->revent == NULL || iob->wevent == NULL)
sudo_fatalx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
SLIST_INSERT_HEAD(head, iob, entries);
debug_return;
}
/*
* Fork a monitor process which runs the actual command as its own child
* process with std{in,out,err} hooked up to the pty or pipes as appropriate.
* Returns the child pid.
*/
static int
fork_pty(struct command_details *details, int sv[], sigset_t *omask)
{
struct command_status cstat;
int io_pipe[3][2];
sigaction_t sa;
sigset_t mask;
pid_t child;
debug_decl(fork_pty, SUDO_DEBUG_EXEC);
ppgrp = getpgrp(); /* parent's pgrp, so child can signal us */
memset(&sa, 0, sizeof(sa));
sigemptyset(&sa.sa_mask);
if (io_fds[SFD_USERTTY] != -1) {
sa.sa_flags = SA_RESTART;
sa.sa_handler = sigwinch;
if (sudo_sigaction(SIGWINCH, &sa, NULL) != 0)
sudo_warn(U_("unable to set handler for signal %d"), SIGWINCH);
}
/* So we can block tty-generated signals */
sigemptyset(&ttyblock);
sigaddset(&ttyblock, SIGINT);
sigaddset(&ttyblock, SIGQUIT);
sigaddset(&ttyblock, SIGTSTP);
sigaddset(&ttyblock, SIGTTIN);
sigaddset(&ttyblock, SIGTTOU);
/*
* Setup stdin/stdout/stderr for child, to be duped after forking.
* In background mode there is no stdin.
*/
if (!ISSET(details->flags, CD_BACKGROUND))
io_fds[SFD_STDIN] = io_fds[SFD_SLAVE];
io_fds[SFD_STDOUT] = io_fds[SFD_SLAVE];
io_fds[SFD_STDERR] = io_fds[SFD_SLAVE];
if (io_fds[SFD_USERTTY] != -1) {
/* Read from /dev/tty, write to pty master */
if (!ISSET(details->flags, CD_BACKGROUND)) {
io_buf_new(io_fds[SFD_USERTTY], io_fds[SFD_MASTER],
log_ttyin, &iobufs);
}
/* Read from pty master, write to /dev/tty */
io_buf_new(io_fds[SFD_MASTER], io_fds[SFD_USERTTY],
log_ttyout, &iobufs);
/* Are we the foreground process? */
foreground = tcgetpgrp(io_fds[SFD_USERTTY]) == ppgrp;
}
/*
* If either stdin, stdout or stderr is not a tty we use a pipe
* to interpose ourselves instead of duping the pty fd.
*/
memset(io_pipe, 0, sizeof(io_pipe));
if (io_fds[SFD_STDIN] == -1 || !isatty(STDIN_FILENO)) {
sudo_debug_printf(SUDO_DEBUG_INFO, "stdin not a tty, creating a pipe");
pipeline = true;
if (pipe(io_pipe[STDIN_FILENO]) != 0)
sudo_fatal(U_("unable to create pipe"));
io_buf_new(STDIN_FILENO, io_pipe[STDIN_FILENO][1],
log_stdin, &iobufs);
io_fds[SFD_STDIN] = io_pipe[STDIN_FILENO][0];
}
if (io_fds[SFD_STDOUT] == -1 || !isatty(STDOUT_FILENO)) {
sudo_debug_printf(SUDO_DEBUG_INFO, "stdout not a tty, creating a pipe");
pipeline = true;
if (pipe(io_pipe[STDOUT_FILENO]) != 0)
sudo_fatal(U_("unable to create pipe"));
io_buf_new(io_pipe[STDOUT_FILENO][0], STDOUT_FILENO,
log_stdout, &iobufs);
io_fds[SFD_STDOUT] = io_pipe[STDOUT_FILENO][1];
}
if (io_fds[SFD_STDERR] == -1 || !isatty(STDERR_FILENO)) {
sudo_debug_printf(SUDO_DEBUG_INFO, "stderr not a tty, creating a pipe");
if (pipe(io_pipe[STDERR_FILENO]) != 0)
sudo_fatal(U_("unable to create pipe"));
io_buf_new(io_pipe[STDERR_FILENO][0], STDERR_FILENO,
log_stderr, &iobufs);
io_fds[SFD_STDERR] = io_pipe[STDERR_FILENO][1];
}
if (foreground) {
/* Copy terminal attrs from user tty -> pty slave. */
if (sudo_term_copy(io_fds[SFD_USERTTY], io_fds[SFD_SLAVE])) {
tty_initialized = true;
sync_ttysize(io_fds[SFD_USERTTY], io_fds[SFD_SLAVE]);
}
/* Start out in raw mode unless part of a pipeline or backgrounded. */
if (!pipeline && !ISSET(details->flags, CD_EXEC_BG)) {
if (sudo_term_raw(io_fds[SFD_USERTTY], 0))
ttymode = TERM_RAW;
}
}
/*
* Block some signals until cmnd_pid is set in the parent to avoid a
* race between exec of the command and receipt of a fatal signal from it.
*/
sigemptyset(&mask);
sigaddset(&mask, SIGTERM);
sigaddset(&mask, SIGHUP);
sigaddset(&mask, SIGINT);
sigaddset(&mask, SIGQUIT);
sigprocmask(SIG_BLOCK, &mask, omask);
child = sudo_debug_fork();
switch (child) {
case -1:
sudo_fatal(U_("unable to fork"));
break;
case 0:
/* child */
close(sv[0]);
close(signal_pipe[0]);
close(signal_pipe[1]);
(void)fcntl(sv[1], F_SETFD, FD_CLOEXEC);
sigprocmask(SIG_SETMASK, omask, NULL);
/* Close the other end of the stdin/stdout/stderr pipes and exec. */
if (io_pipe[STDIN_FILENO][1])
close(io_pipe[STDIN_FILENO][1]);
if (io_pipe[STDOUT_FILENO][0])
close(io_pipe[STDOUT_FILENO][0]);
if (io_pipe[STDERR_FILENO][0])
close(io_pipe[STDERR_FILENO][0]);
/*
* If stdin/stdout is not a tty, start command in the background
* since it might be part of a pipeline that reads from /dev/tty.
* In this case, we rely on the command receiving SIGTTOU or SIGTTIN
* when it needs access to the controlling tty.
*/
exec_monitor(details, foreground && !pipeline, sv[1]);
cstat.type = CMD_ERRNO;
cstat.val = errno;
while (send(sv[1], &cstat, sizeof(cstat), 0) == -1) {
if (errno != EINTR)
break;
}
_exit(1);
}
/* Close the other end of the stdin/stdout/stderr pipes. */
if (io_pipe[STDIN_FILENO][0])
close(io_pipe[STDIN_FILENO][0]);
if (io_pipe[STDOUT_FILENO][1])
close(io_pipe[STDOUT_FILENO][1]);
if (io_pipe[STDERR_FILENO][1])
close(io_pipe[STDERR_FILENO][1]);
debug_return_int(child);
}
static void
pty_close(struct command_status *cstat)
{
struct io_buffer *iob;
int n;
debug_decl(pty_close, SUDO_DEBUG_EXEC);
/* Flush any remaining output (the plugin already got it). */
if (io_fds[SFD_USERTTY] != -1) {
n = fcntl(io_fds[SFD_USERTTY], F_GETFL, 0);
if (n != -1 && ISSET(n, O_NONBLOCK)) {
CLR(n, O_NONBLOCK);
(void) fcntl(io_fds[SFD_USERTTY], F_SETFL, n);
}
}
del_io_events(false);
/* Free I/O buffers. */
while ((iob = SLIST_FIRST(&iobufs)) != NULL) {
SLIST_REMOVE_HEAD(&iobufs, entries);
if (iob->revent != NULL)
sudo_ev_free(iob->revent);
if (iob->wevent != NULL)
sudo_ev_free(iob->wevent);
free(iob);
}
/* Restore terminal settings. */
if (io_fds[SFD_USERTTY] != -1)
sudo_term_restore(io_fds[SFD_USERTTY], false);
/* If child was signalled, write the reason to stdout like the shell. */
if (cstat->type == CMD_WSTATUS && WIFSIGNALED(cstat->val)) {
int signo = WTERMSIG(cstat->val);
if (signo && signo != SIGINT && signo != SIGPIPE) {
const char *reason = strsignal(signo);
n = io_fds[SFD_USERTTY] != -1 ?
io_fds[SFD_USERTTY] : STDOUT_FILENO;
if (write(n, reason, strlen(reason)) != -1) {
if (WCOREDUMP(cstat->val))
ignore_result(write(n, " (core dumped)", 14));
ignore_result(write(n, "\n", 1));
}
}
}
if (utmp_user != NULL)
utmp_logout(slavename, cstat->type == CMD_WSTATUS ? cstat->val : 0);
debug_return;
}
/*
* Schedule a signal to be forwarded.
*/
static void
schedule_signal(struct exec_closure_pty *ec, int signo)
{
struct sigforward *sigfwd;
char signame[SIG2STR_MAX];
debug_decl(schedule_signal, SUDO_DEBUG_EXEC)
if (signo == SIGCONT_FG)
strlcpy(signame, "CONT_FG", sizeof(signame));
else if (signo == SIGCONT_BG)
strlcpy(signame, "CONT_BG", sizeof(signame));
else if (sig2str(signo, signame) == -1)
snprintf(signame, sizeof(signame), "%d", signo);
sudo_debug_printf(SUDO_DEBUG_DIAG, "scheduled SIG%s for child", signame);
if ((sigfwd = calloc(1, sizeof(*sigfwd))) == NULL)
sudo_fatalx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
sigfwd->signo = signo;
TAILQ_INSERT_TAIL(&ec->sigfwd_list, sigfwd, entries);
if (sudo_ev_add(ec->evbase, ec->sigfwd_event, NULL, true) == -1)
sudo_fatal(U_("unable to add event to queue"));
debug_return;
}
static void
backchannel_cb(int fd, int what, void *v)
{
struct exec_closure_pty *ec = v;
ssize_t n;
debug_decl(backchannel_cb, SUDO_DEBUG_EXEC)
/* read child status */
n = recv(fd, ec->cstat, sizeof(struct command_status), MSG_WAITALL);
if (n != sizeof(struct command_status)) {
if (n == -1) {
switch (errno) {
case EINTR:
/* got a signal, restart loop to service it. */
sudo_ev_loopcontinue(ec->evbase);
break;
case EAGAIN:
/* not ready after all... */
break;
default:
ec->cstat->type = CMD_ERRNO;
ec->cstat->val = errno;
sudo_debug_printf(SUDO_DEBUG_ERROR,
"failed to read child status: %s", strerror(errno));
sudo_ev_loopbreak(ec->evbase);
break;
}
} else {
/* Short read or EOF. */
sudo_debug_printf(SUDO_DEBUG_ERROR,
"failed to read child status: %s", n ? "short read" : "EOF");
/* XXX - need new CMD_ type for monitor errors. */
errno = n ? EIO : ECONNRESET;
ec->cstat->type = CMD_ERRNO;
ec->cstat->val = errno;
sudo_ev_loopbreak(ec->evbase);
}
debug_return;
}
switch (ec->cstat->type) {
case CMD_PID:
/*
* Once we know the command's pid we can unblock
* signals which ere blocked in fork_pty(). This
* avoids a race between exec of the command and
* receipt of a fatal signal from it.
*/
cmnd_pid = ec->cstat->val;
sudo_debug_printf(SUDO_DEBUG_INFO, "executed %s, pid %d",
ec->details->command, (int)cmnd_pid);
sigprocmask(SIG_SETMASK, ec->omask, NULL);
break;
case CMD_WSTATUS:
if (WIFSTOPPED(ec->cstat->val)) {
/* Suspend parent and tell child how to resume on return. */
sudo_debug_printf(SUDO_DEBUG_INFO,
"child stopped, suspending parent");
n = suspend_sudo(WSTOPSIG(ec->cstat->val));
schedule_signal(ec, n);
/* Re-enable I/O events and restart event loop to service signal. */
add_io_events(ec->evbase);
sudo_ev_loopcontinue(ec->evbase);
} else {
/* Child exited or was killed, either way we are done. */
sudo_debug_printf(SUDO_DEBUG_INFO, "child exited or was killed");
sudo_ev_loopexit(ec->evbase);
}
break;
case CMD_ERRNO:
/* Child was unable to execute command or broken pipe. */
sudo_debug_printf(SUDO_DEBUG_INFO, "errno from child: %s",
strerror(ec->cstat->val));
sudo_ev_loopbreak(ec->evbase);
break;
}
debug_return;
}
/*
* Handle changes to the monitors's status (SIGCHLD).
*/
static void
handle_sigchld_pty(struct exec_closure_pty *ec)
{
int n, status;
pid_t pid;
debug_decl(handle_sigchld_pty, SUDO_DEBUG_EXEC)
/*
* Monitor process was signaled; wait for it as needed.
*/
do {
pid = waitpid(ec->child, &status, WUNTRACED|WNOHANG);
} while (pid == -1 && errno == EINTR);
if (pid == ec->child) {
/*
* If the monitor dies we get notified via backchannel_cb().
* If it was stopped, we should stop too (the command keeps
* running in its pty) and continue it when we come back.
*/
if (WIFSTOPPED(status)) {
sudo_debug_printf(SUDO_DEBUG_INFO,
"monitor stopped, suspending sudo");
n = suspend_sudo(WSTOPSIG(status));
kill(pid, SIGCONT);
schedule_signal(ec, n);
/* Re-enable I/O events and restart event loop. */
add_io_events(ec->evbase);
sudo_ev_loopcontinue(ec->evbase);
} else if (WIFSIGNALED(status)) {
char signame[SIG2STR_MAX];
if (sig2str(WTERMSIG(status), signame) == -1)
snprintf(signame, sizeof(signame), "%d", WTERMSIG(status));
sudo_debug_printf(SUDO_DEBUG_INFO, "%s: monitor (%d) killed, SIG%s",
__func__, (int)ec->child, signame);
ec->child = -1;
} else {
sudo_debug_printf(SUDO_DEBUG_INFO,
"%s: monitor exited, status %d", __func__, WEXITSTATUS(status));
ec->child = -1;
}
}
debug_return;
}
/* Signal pipe callback */
static void
signal_pipe_cb(int fd, int what, void *v)
{
struct exec_closure_pty *ec = v;
char signame[SIG2STR_MAX];
unsigned char signo;
ssize_t nread;
debug_decl(signal_pipe_cb, SUDO_DEBUG_EXEC)
/* Process received signals until the child dies or the pipe is empty. */
do {
/* read signal pipe */
nread = read(fd, &signo, sizeof(signo));
if (nread <= 0) {
/* It should not be possible to get EOF but just in case... */
if (nread == 0)
errno = ECONNRESET;
/* Restart if interrupted by signal so the pipe doesn't fill. */
if (errno == EINTR)
continue;
/* On error, store errno and break out of the event loop. */
if (errno != EAGAIN) {
ec->cstat->type = CMD_ERRNO;
ec->cstat->val = errno;
sudo_warn(U_("error reading from signal pipe"));
sudo_ev_loopbreak(ec->evbase);
}
break;
}
if (sig2str(signo, signame) == -1)
snprintf(signame, sizeof(signame), "%d", signo);
sudo_debug_printf(SUDO_DEBUG_DIAG,
"%s: evbase %p, child: %d, signo %s(%d), cstat %p",
__func__, ec->evbase, (int)ec->child, signame, signo, ec->cstat);
if (signo == SIGCHLD) {
handle_sigchld_pty(ec);
} else if (ec->child != -1) {
/* Schedule signo to be forwared to the child. */
schedule_signal(ec, signo);
/* Restart event loop to service signal immediately. */
sudo_ev_loopcontinue(ec->evbase);
}
} while (ec->child != -1);
debug_return;
}
/*
* Forward signals in sigfwd_list to the monitor so it can
* deliver them to the command.
*/
static void
sigfwd_cb(int sock, int what, void *v)
{
struct exec_closure_pty *ec = v;
char signame[SIG2STR_MAX];
struct sigforward *sigfwd;
struct command_status cstat;
ssize_t nsent;
debug_decl(sigfwd_cb, SUDO_DEBUG_EXEC)
while (!TAILQ_EMPTY(&ec->sigfwd_list)) {
sigfwd = TAILQ_FIRST(&ec->sigfwd_list);
if (sigfwd->signo == SIGCONT_FG)
strlcpy(signame, "CONT_FG", sizeof(signame));
else if (sigfwd->signo == SIGCONT_BG)
strlcpy(signame, "CONT_BG", sizeof(signame));
else if (sig2str(sigfwd->signo, signame) == -1)
snprintf(signame, sizeof(signame), "%d", sigfwd->signo);
sudo_debug_printf(SUDO_DEBUG_INFO,
"sending SIG%s to child over backchannel", signame);
cstat.type = CMD_SIGNO;
cstat.val = sigfwd->signo;
do {
nsent = send(sock, &cstat, sizeof(cstat), 0);
} while (nsent == -1 && errno == EINTR);
TAILQ_REMOVE(&ec->sigfwd_list, sigfwd, entries);
free(sigfwd);
if (nsent != sizeof(cstat)) {
if (errno == EPIPE) {
struct sigforward *sigfwd_next;
sudo_debug_printf(SUDO_DEBUG_ERROR,
"broken pipe writing to child over backchannel");
/* Other end of socket gone, empty out sigfwd_list. */
TAILQ_FOREACH_SAFE(sigfwd, &ec->sigfwd_list, entries, sigfwd_next) {
free(sigfwd);
}
TAILQ_INIT(&ec->sigfwd_list);
/* XXX - child (monitor) is dead, we should exit too? */
}
break;
}
}
}
/*
* Fill in the exec closure and setup initial exec events.
* Allocates events for the signal pipe and backchannel.
* Forwarded signals on the backchannel are enabled on demand.
*/
static void
fill_exec_closure_pty(struct exec_closure_pty *ec, struct command_status *cstat,
struct command_details *details, pid_t child, sigset_t *omask,
int backchannel)
{
debug_decl(fill_exec_closure_pty, SUDO_DEBUG_EXEC)
/* Fill in the non-event part of the closure. */
ec->child = child;
ec->omask = omask;
ec->cstat = cstat;
ec->details = details;
TAILQ_INIT(&ec->sigfwd_list);
/* Setup event base and events. */
ec->evbase = sudo_ev_base_alloc();
if (ec->evbase == NULL)
sudo_fatal(NULL);
/* Event for local signals via signal_pipe. */
ec->signal_event = sudo_ev_alloc(signal_pipe[0],
SUDO_EV_READ|SUDO_EV_PERSIST, signal_pipe_cb, ec);
if (ec->signal_event == NULL)
sudo_fatal(NULL);
if (sudo_ev_add(ec->evbase, ec->signal_event, NULL, false) == -1)
sudo_fatal(U_("unable to add event to queue"));
/* Event for command status via backchannel. */
ec->backchannel_event = sudo_ev_alloc(backchannel,
SUDO_EV_READ|SUDO_EV_PERSIST, backchannel_cb, ec);
if (ec->backchannel_event == NULL)
sudo_fatal(NULL);
if (sudo_ev_add(ec->evbase, ec->backchannel_event, NULL, false) == -1)
sudo_fatal(U_("unable to add event to queue"));
/* The signal forwarding event gets added on demand. */
ec->sigfwd_event = sudo_ev_alloc(backchannel,
SUDO_EV_WRITE, sigfwd_cb, ec);
if (ec->sigfwd_event == NULL)
sudo_fatal(NULL);
sudo_debug_printf(SUDO_DEBUG_INFO, "signal pipe fd %d\n", signal_pipe[0]);
sudo_debug_printf(SUDO_DEBUG_INFO, "backchannel fd %d\n", backchannel);
}
/*
* Execute a command in a pty, potentially with I/O loggging, and
* wait for it to finish.
* This is a little bit tricky due to how POSIX job control works and
* we fact that we have two different controlling terminals to deal with.
*/
int
exec_pty(struct command_details *details, struct command_status *cstat)
{
struct sigforward *sigfwd, *sigfwd_next;
struct exec_closure_pty ec;
sigaction_t sa;
sigset_t omask;
pid_t child;
int sv[2];
debug_decl(exec_pty, SUDO_DEBUG_EXEC)
/*
* Allocate a pty.
*/
if (ISSET(details->flags, CD_SET_UTMP))
utmp_user = details->utmp_user ? details->utmp_user : user_details.username;
sudo_debug_printf(SUDO_DEBUG_INFO, "allocate pty for I/O logging");
pty_setup(details->euid, user_details.tty);
/*
* We communicate with the child over a bi-directional pair of sockets.
* Parent sends signal info to child and child sends back wait status.
*/
if (socketpair(PF_UNIX, SOCK_STREAM, 0, sv) == -1)
sudo_fatal(U_("unable to create sockets"));
/*
* Signals to forward to the child process (excluding SIGALRM).
* We block all other signals while running the signal handler.
* Note: HP-UX select() will not be interrupted if SA_RESTART set.
*/
memset(&sa, 0, sizeof(sa));
sigfillset(&sa.sa_mask);
sa.sa_flags = SA_INTERRUPT; /* do not restart syscalls */
#ifdef SA_SIGINFO
sa.sa_flags |= SA_SIGINFO;
sa.sa_sigaction = exec_handler;
#else
sa.sa_handler = exec_handler;
#endif
if (sudo_sigaction(SIGTERM, &sa, NULL) != 0)
sudo_warn(U_("unable to set handler for signal %d"), SIGTERM);
if (sudo_sigaction(SIGHUP, &sa, NULL) != 0)
sudo_warn(U_("unable to set handler for signal %d"), SIGHUP);
if (sudo_sigaction(SIGALRM, &sa, NULL) != 0)
sudo_warn(U_("unable to set handler for signal %d"), SIGALRM);
if (sudo_sigaction(SIGPIPE, &sa, NULL) != 0)
sudo_warn(U_("unable to set handler for signal %d"), SIGPIPE);
if (sudo_sigaction(SIGUSR1, &sa, NULL) != 0)
sudo_warn(U_("unable to set handler for signal %d"), SIGUSR1);
if (sudo_sigaction(SIGUSR2, &sa, NULL) != 0)
sudo_warn(U_("unable to set handler for signal %d"), SIGUSR2);
if (sudo_sigaction(SIGCHLD, &sa, NULL) != 0)
sudo_warn(U_("unable to set handler for signal %d"), SIGCHLD);
#ifdef SIGINFO
if (sudo_sigaction(SIGINFO, &sa, NULL) != 0)
sudo_warn(U_("unable to set handler for signal %d"), SIGINFO);
#endif
/*
* Unlike the non-pty case, we can use our normal signal handler
* for tty-generated signals triggered by the user.
*/
if (sudo_sigaction(SIGINT, &sa, NULL) != 0)
sudo_warn(U_("unable to set handler for signal %d"), SIGINT);
if (sudo_sigaction(SIGQUIT, &sa, NULL) != 0)
sudo_warn(U_("unable to set handler for signal %d"), SIGQUIT);
if (sudo_sigaction(SIGTSTP, &sa, NULL) != 0)
sudo_warn(U_("unable to set handler for signal %d"), SIGTSTP);
/*
* We don't want to receive SIGTTIN/SIGTTOU, getting EIO is preferable.
*/
sa.sa_flags = SA_RESTART;
sa.sa_handler = SIG_IGN;
if (sudo_sigaction(SIGTTIN, &sa, NULL) != 0)
sudo_warn(U_("unable to set handler for signal %d"), SIGTTIN);
if (sudo_sigaction(SIGTTOU, &sa, NULL) != 0)
sudo_warn(U_("unable to set handler for signal %d"), SIGTTOU);
/*
* The policy plugin's session init must be run before we fork
* or certain pam modules won't be able to track their state.
*/
if (policy_init_session(details) != true)
sudo_fatalx(U_("policy plugin failed session initialization"));
/*
* Child will run the command in the pty, parent will pass data
* to and from pty.
* XXX - inline fork_pty or refactor differently?
*/
child = fork_pty(details, sv, &omask);
close(sv[1]);
/* No longer need execfd. */
if (details->execfd != -1) {
close(details->execfd);
details->execfd = -1;
}
/* Set command timeout if specified. */
if (ISSET(details->flags, CD_SET_TIMEOUT))
alarm(details->timeout);
/*
* I/O logging must be in the C locale for floating point numbers
* to be logged consistently.
*/
setlocale(LC_ALL, "C");
/*
* Allocate event base and two persistent events:
* the signal pipe and the child process's backchannel.
*/
fill_exec_closure_pty(&ec, cstat, details, child, &omask, sv[0]);
/*
* In the event loop we pass input from user tty to master
* and pass output from master to stdout and IO plugin.
*/
add_io_events(ec.evbase);
if (sudo_ev_loop(ec.evbase, 0) == -1)
sudo_warn(U_("error in event loop"));
if (sudo_ev_got_break(ec.evbase)) {
/* error from callback */
sudo_debug_printf(SUDO_DEBUG_ERROR, "event loop exited prematurely");
}
/* Flush any remaining output and free pty-related memory. */
pty_close(cstat);
/* Free things up. */
sudo_ev_base_free(ec.evbase);
sudo_ev_free(ec.sigfwd_event);
sudo_ev_free(ec.signal_event);
sudo_ev_free(ec.backchannel_event);
TAILQ_FOREACH_SAFE(sigfwd, &ec.sigfwd_list, entries, sigfwd_next) {
free(sigfwd);
}
debug_return_int(cstat->type == CMD_ERRNO ? -1 : 0);
}
/*
* Schedule I/O events before starting the main event loop or
* resuming from suspend.
*/
static void
add_io_events(struct sudo_event_base *evbase)
{
struct io_buffer *iob;
debug_decl(add_io_events, SUDO_DEBUG_EXEC);
/*
* Schedule all readers as long as the buffer is not full.
* Schedule writers that contain buffered data.
* Normally, write buffers are added on demand when data is read.
*/
SLIST_FOREACH(iob, &iobufs, entries) {
/* Don't read/write from /dev/tty if we are not in the foreground. */
if (iob->revent != NULL &&
(ttymode == TERM_RAW || !USERTTY_EVENT(iob->revent))) {
if (iob->len != sizeof(iob->buf)) {
sudo_debug_printf(SUDO_DEBUG_INFO,
"added I/O revent %p, fd %d, events %d",
iob->revent, iob->revent->fd, iob->revent->events);
if (sudo_ev_add(evbase, iob->revent, NULL, false) == -1)
sudo_fatal(U_("unable to add event to queue"));
}
}
if (iob->wevent != NULL &&
(foreground || !USERTTY_EVENT(iob->wevent))) {
if (iob->len > iob->off) {
sudo_debug_printf(SUDO_DEBUG_INFO,
"added I/O wevent %p, fd %d, events %d",
iob->wevent, iob->wevent->fd, iob->wevent->events);
if (sudo_ev_add(evbase, iob->wevent, NULL, false) == -1)
sudo_fatal(U_("unable to add event to queue"));
}
}
}
debug_return;
}
/*
* Flush any output buffered in iobufs or readable from fds other
* than /dev/tty. Removes I/O events from the event base when done.
*/
static void
del_io_events(bool nonblocking)
{
struct io_buffer *iob;
struct sudo_event_base *evbase;
debug_decl(del_io_events, SUDO_DEBUG_EXEC);
/* Remove iobufs from existing event base. */
SLIST_FOREACH(iob, &iobufs, entries) {
if (iob->revent != NULL) {
sudo_debug_printf(SUDO_DEBUG_INFO,
"deleted I/O revent %p, fd %d, events %d",
iob->revent, iob->revent->fd, iob->revent->events);
sudo_ev_del(NULL, iob->revent);
}
if (iob->wevent != NULL) {
sudo_debug_printf(SUDO_DEBUG_INFO,
"deleted I/O wevent %p, fd %d, events %d",
iob->wevent, iob->wevent->fd, iob->wevent->events);
sudo_ev_del(NULL, iob->wevent);
}
}
/* Create temporary event base for flushing. */
evbase = sudo_ev_base_alloc();
if (evbase == NULL)
sudo_fatal(NULL);
/* Avoid reading from /dev/tty, just flush existing data. */
SLIST_FOREACH(iob, &iobufs, entries) {
/* Don't read from /dev/tty while flushing. */
if (iob->revent != NULL && !USERTTY_EVENT(iob->revent)) {
if (iob->len != sizeof(iob->buf)) {
if (sudo_ev_add(evbase, iob->revent, NULL, false) == -1)
sudo_fatal(U_("unable to add event to queue"));
}
}
/* Flush any write buffers with data in them. */
if (iob->wevent != NULL) {
if (iob->len > iob->off) {
if (sudo_ev_add(evbase, iob->wevent, NULL, false) == -1)
sudo_fatal(U_("unable to add event to queue"));
}
}
}
(void) sudo_ev_loop(evbase, SUDO_EVLOOP_NONBLOCK);
/*
* If not in non-blocking mode, make sure we flush write buffers.
* We don't want to read from the pty or stdin since that might block
* and the command is no longer running anyway.
*/
if (!nonblocking) {
/* Clear out iobufs from event base. */
SLIST_FOREACH(iob, &iobufs, entries) {
if (iob->revent != NULL && !USERTTY_EVENT(iob->revent))
sudo_ev_del(evbase, iob->revent);
if (iob->wevent != NULL)
sudo_ev_del(evbase, iob->wevent);
}
SLIST_FOREACH(iob, &iobufs, entries) {
/* Flush any write buffers with data in them. */
if (iob->wevent != NULL) {
if (iob->len > iob->off) {
if (sudo_ev_add(evbase, iob->wevent, NULL, false) == -1)
sudo_fatal(U_("unable to add event to queue"));
}
}
}
(void) sudo_ev_loop(evbase, 0);
/* We should now have flushed all write buffers. */
SLIST_FOREACH(iob, &iobufs, entries) {
if (iob->wevent != NULL) {
if (iob->len > iob->off) {
sudo_debug_printf(SUDO_DEBUG_ERROR,
"unflushed data: wevent %p, fd %d, events %d",
iob->wevent, iob->wevent->fd, iob->wevent->events);
}
}
}
}
/* Free temporary event base, removing its events. */
sudo_ev_base_free(evbase);
debug_return;
}
/*
* Propagates tty size change signals to pty being used by the command.
*/
static void
sync_ttysize(int src, int dst)
{
#ifdef TIOCGWINSZ
struct winsize wsize;
pid_t pgrp;
debug_decl(sync_ttysize, SUDO_DEBUG_EXEC);
if (ioctl(src, TIOCGWINSZ, &wsize) == 0) {
ioctl(dst, TIOCSWINSZ, &wsize);
if ((pgrp = tcgetpgrp(dst)) != -1)
killpg(pgrp, SIGWINCH);
}
debug_return;
#endif
}
/*
* Handler for SIGWINCH in parent.
*/
static void
sigwinch(int s)
{
int serrno = errno;
sync_ttysize(io_fds[SFD_USERTTY], io_fds[SFD_SLAVE]);
errno = serrno;
}
/*
* Remove and free any events associated with the specified
* file descriptor present in the I/O buffers list.
*/
static void
ev_free_by_fd(struct sudo_event_base *evbase, int fd)
{
struct io_buffer *iob;
debug_decl(ev_free_by_fd, SUDO_DEBUG_EXEC);
/* Deschedule any users of the fd and free up the events. */
SLIST_FOREACH(iob, &iobufs, entries) {
if (iob->revent != NULL) {
if (sudo_ev_get_fd(iob->revent) == fd) {
sudo_debug_printf(SUDO_DEBUG_INFO,
"%s: deleting and freeing revent %p with fd %d",
__func__, iob->revent, fd);
sudo_ev_del(evbase, iob->revent);
sudo_ev_free(iob->revent);
iob->revent = NULL;
}
}
if (iob->wevent != NULL) {
if (sudo_ev_get_fd(iob->wevent) == fd) {
sudo_debug_printf(SUDO_DEBUG_INFO,
"%s: deleting and freeing wevent %p with fd %d",
__func__, iob->wevent, fd);
sudo_ev_del(evbase, iob->wevent);
sudo_ev_free(iob->wevent);
iob->wevent = NULL;
}
}
}
debug_return;
}
/*
* Only close the fd if it is not /dev/tty or std{in,out,err}.
* Return value is the same as close(2).
*/
static int
safe_close(int fd)
{
debug_decl(safe_close, SUDO_DEBUG_EXEC);
/* Avoid closing /dev/tty or std{in,out,err}. */
if (fd < 3 || fd == io_fds[SFD_USERTTY]) {
sudo_debug_printf(SUDO_DEBUG_INFO,
"%s: not closing fd %d (/dev/tty)", __func__, fd);
errno = EINVAL;
debug_return_int(-1);
}
sudo_debug_printf(SUDO_DEBUG_INFO, "%s: closing fd %d", __func__, fd);
debug_return_int(close(fd));
}
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