/* * Copyright (c) 2009-2016 Todd C. Miller * * 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 #include #include #include #include #include #include #include #ifdef HAVE_STRING_H # include #endif /* HAVE_STRING_H */ #ifdef HAVE_STRINGS_H # include #endif /* HAVE_STRINGS_H */ #include #ifdef TIME_WITH_SYS_TIME # include #endif #include #include #include #include #include "sudo.h" #include "sudo_event.h" #include "sudo_exec.h" #include "sudo_plugin.h" #include "sudo_plugin_int.h" #define SFD_STDIN 0 #define SFD_STDOUT 1 #define SFD_STDERR 2 #define SFD_MASTER 3 #define SFD_SLAVE 4 #define SFD_USERTTY 5 /* 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 /* Compatibility with older tty systems. */ #if !defined(TIOCGWINSZ) && defined(TIOCGSIZE) # define TIOCGWINSZ TIOCGSIZE # define TIOCSWINSZ TIOCSSIZE # define winsize ttysize #endif /* * 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]; static bool foreground, pipeline, tty_initialized; static int io_fds[6] = { -1, -1, -1, -1, -1, -1}; static int ttymode = TERM_COOKED; static pid_t ppgrp, cmnd_pgrp, mon_pgrp; static sigset_t ttyblock; static struct io_buffer_list iobufs; static void del_io_events(bool nonblocking); static int exec_monitor(struct command_details *details, int backchannel); static void exec_pty(struct command_details *details, struct command_status *cstat, int errfd); static void sigwinch(int s); static void sync_ttysize(int src, int dst); static void deliver_signal(pid_t pid, int signo, bool from_parent); static int safe_close(int fd); static void ev_free_by_fd(struct sudo_event_base *evbase, int fd); static void check_foreground(void); /* * Cleanup hook for sudo_fatal()/sudo_fatalx() */ static 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], 0); #ifdef HAVE_SELINUX selinux_restore_tty(); #endif utmp_logout(slavename, 0); /* XXX - only if CD_SET_UTMP */ debug_return; } /* * Generic handler for signals recieved by the monitor process. * The other end of signal_pipe is checked in the monitor event loop. */ #ifdef SA_SIGINFO static void mon_handler(int s, siginfo_t *info, void *context) { unsigned char signo = (unsigned char)s; /* * If the signal came from the process group of the command we ran, * do not forward it as we don't want the child to indirectly kill * itself. This can happen with, e.g., BSD-derived versions of * reboot that call kill(-1, SIGTERM) to kill all other processes. */ if (s != SIGCHLD && USER_SIGNALED(info) && info->si_pid != 0) { pid_t si_pgrp = getpgid(info->si_pid); if (si_pgrp != -1) { if (si_pgrp == cmnd_pgrp) return; } else if (info->si_pid == cmnd_pid) { return; } } /* * The pipe is non-blocking, if we overflow the kernel's pipe * buffer we drop the signal. This is not a problem in practice. */ while (write(signal_pipe[1], &signo, sizeof(signo)) == -1) { if (errno != EINTR) break; } } #else static void mon_handler(int s) { unsigned char signo = (unsigned char)s; /* * The pipe is non-blocking, if we overflow the kernel's pipe * buffer we drop the signal. This is not a problem in practice. */ while (write(signal_pipe[1], &signo, sizeof(signo)) == -1) { if (errno != EINTR) break; } } #endif /* * 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. */ void pty_setup(uid_t uid, const char *tty, const char *utmp_user) { 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; } /* 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 rval = 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; } rval = false; break; } } } sudo_debug_set_active_instance(sudo_debug_instance); sigprocmask(SIG_SETMASK, &omask, NULL); debug_return_bool(rval); } /* 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 rval = 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; } rval = false; break; } } } sudo_debug_set_active_instance(sudo_debug_instance); sigprocmask(SIG_SETMASK, &omask, NULL); debug_return_bool(rval); } /* 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 rval = 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; } rval = false; break; } } } sudo_debug_set_active_instance(sudo_debug_instance); if (!rval) { /* * 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(rval); } /* 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 rval = 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; } rval = false; break; } } } sudo_debug_set_active_instance(sudo_debug_instance); if (!rval) { /* * 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(rval); } /* 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 rval = 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; } rval = false; break; } } } sudo_debug_set_active_instance(sudo_debug_instance); if (!rval) { /* * 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(rval); } /* * 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. */ int suspend_parent(int signo) { char signame[SIG2STR_MAX]; sigaction_t sa, osa; int rval = 0; debug_decl(suspend_parent, 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; } rval = 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], 0); 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); } rval = ttymode == TERM_RAW ? SIGCONT_FG : SIGCONT_BG; break; } debug_return_int(rval); } /* * Kill command with increasing urgency. */ void terminate_command(pid_t pid, bool use_pgrp) { debug_decl(terminate_command, SUDO_DEBUG_EXEC); /* * Note that SIGCHLD will interrupt the sleep() */ if (use_pgrp) { sudo_debug_printf(SUDO_DEBUG_INFO, "killpg %d SIGHUP", (int)pid); killpg(pid, SIGHUP); sudo_debug_printf(SUDO_DEBUG_INFO, "killpg %d SIGTERM", (int)pid); killpg(pid, SIGTERM); sleep(2); sudo_debug_printf(SUDO_DEBUG_INFO, "killpg %d SIGKILL", (int)pid); killpg(pid, SIGKILL); } else { sudo_debug_printf(SUDO_DEBUG_INFO, "kill %d SIGHUP", (int)pid); kill(pid, SIGHUP); sudo_debug_printf(SUDO_DEBUG_INFO, "kill %d SIGTERM", (int)pid); kill(pid, SIGTERM); sleep(2); sudo_debug_printf(SUDO_DEBUG_INFO, "kill %d SIGKILL", (int)pid); kill(pid, SIGKILL); } debug_return; } /* * 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. */ 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]; } /* We don't want to receive SIGTTIN/SIGTTOU, getting EIO is preferable. */ 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); /* Job control signals to relay from parent to child. */ sigfillset(&sa.sa_mask); sa.sa_flags = SA_INTERRUPT; /* do not restart syscalls */ #ifdef SA_SIGINFO sa.sa_flags |= SA_SIGINFO; sa.sa_sigaction = handler; #else sa.sa_handler = handler; #endif if (sudo_sigaction(SIGCHLD, &sa, NULL) != 0) sudo_warn(U_("unable to set handler for signal %d"), SIGCHLD); if (sudo_sigaction(SIGTSTP, &sa, NULL) != 0) sudo_warn(U_("unable to set handler for signal %d"), SIGTSTP); 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]); exec_monitor(details, sv[1]); cstat.type = CMD_ERRNO; cstat.val = errno; ignore_result(send(sv[1], &cstat, sizeof(cstat), 0)); _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); } 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], 0); /* 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)); } } } utmp_logout(slavename, cstat->type == CMD_WSTATUS ? cstat->val : 0); /* XXX - only if CD_SET_UTMP */ debug_return; } /* * Schedule I/O events before starting the main event loop or * resuming from suspend. */ 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; } static void deliver_signal(pid_t pid, int signo, bool from_parent) { char signame[SIG2STR_MAX]; int status; debug_decl(deliver_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); /* Handle signal from parent. */ sudo_debug_printf(SUDO_DEBUG_INFO, "received SIG%s%s", signame, from_parent ? " from parent" : ""); switch (signo) { case SIGALRM: terminate_command(pid, true); break; case SIGCONT_FG: /* Continue in foreground, grant it controlling tty. */ do { status = tcsetpgrp(io_fds[SFD_SLAVE], cmnd_pgrp); } while (status == -1 && errno == EINTR); killpg(pid, SIGCONT); break; case SIGCONT_BG: /* Continue in background, I take controlling tty. */ do { status = tcsetpgrp(io_fds[SFD_SLAVE], mon_pgrp); } while (status == -1 && errno == EINTR); killpg(pid, SIGCONT); break; case SIGKILL: _exit(1); /* XXX */ /* NOTREACHED */ default: /* Relay signal to command. */ killpg(pid, signo); break; } debug_return; } /* * Send status to parent over socketpair. * Return value is the same as send(2). */ static int send_status(int fd, struct command_status *cstat) { int n = -1; debug_decl(send_status, SUDO_DEBUG_EXEC); if (cstat->type != CMD_INVALID) { sudo_debug_printf(SUDO_DEBUG_INFO, "sending status message to parent: [%d, %d]", cstat->type, cstat->val); do { n = send(fd, cstat, sizeof(*cstat), 0); } while (n == -1 && errno == EINTR); if (n != sizeof(*cstat)) { sudo_debug_printf(SUDO_DEBUG_ERROR, "unable to send status to parent: %s", strerror(errno)); } cstat->type = CMD_INVALID; /* prevent re-sending */ } debug_return_int(n); } /* * Wait for command status after receiving SIGCHLD. * If the command was stopped, the status is send back to the parent. * Otherwise, cstat is filled in but not sent. * Returns true if command is still alive, else false. */ static bool handle_sigchld(int backchannel, struct command_status *cstat) { bool alive = true; int status; pid_t pid; debug_decl(handle_sigchld, SUDO_DEBUG_EXEC); /* read command status */ do { pid = waitpid(cmnd_pid, &status, WUNTRACED|WNOHANG); } while (pid == -1 && errno == EINTR); if (pid != cmnd_pid) { sudo_debug_printf(SUDO_DEBUG_INFO, "waitpid returned %d, expected pid %d", pid, cmnd_pid); } else { if (cstat->type != CMD_ERRNO) { char signame[SIG2STR_MAX]; cstat->type = CMD_WSTATUS; cstat->val = status; if (WIFSTOPPED(status)) { if (sig2str(WSTOPSIG(status), signame) == -1) snprintf(signame, sizeof(signame), "%d", WSTOPSIG(status)); sudo_debug_printf(SUDO_DEBUG_INFO, "command stopped, SIG%s", signame); /* Saved the foreground pgid so we can restore it later. */ do { pid = tcgetpgrp(io_fds[SFD_SLAVE]); } while (pid == -1 && errno == EINTR); if (pid != mon_pgrp) cmnd_pgrp = pid; if (send_status(backchannel, cstat) == -1) debug_return_bool(alive); /* XXX */ } else if (WIFSIGNALED(status)) { if (sig2str(WTERMSIG(status), signame) == -1) snprintf(signame, sizeof(signame), "%d", WTERMSIG(status)); sudo_debug_printf(SUDO_DEBUG_INFO, "command killed, SIG%s", signame); } else { sudo_debug_printf(SUDO_DEBUG_INFO, "command exited: %d", WEXITSTATUS(status)); } } if (!WIFSTOPPED(status)) alive = false; } debug_return_bool(alive); } struct monitor_closure { struct sudo_event_base *evbase; struct sudo_event *errpipe_event; struct sudo_event *backchannel_event; struct sudo_event *signal_pipe_event; struct command_status *cstat; int backchannel; bool alive; }; static void mon_signal_pipe_cb(int fd, int what, void *v) { struct monitor_closure *mc = v; unsigned char signo; ssize_t nread; debug_decl(mon_signal_pipe_cb, SUDO_DEBUG_EXEC); 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; if (errno != EINTR && errno != EAGAIN) { sudo_warn(U_("error reading from signal pipe")); sudo_ev_loopbreak(mc->evbase); } } else { /* * Handle SIGCHLD specially and deliver other signals * directly to the command. */ if (signo == SIGCHLD) { mc->alive = handle_sigchld(mc->backchannel, mc->cstat); if (!mc->alive) { /* Remove all but the errpipe event. */ sudo_ev_del(mc->evbase, mc->backchannel_event); sudo_ev_del(mc->evbase, mc->signal_pipe_event); } } else { deliver_signal(cmnd_pid, signo, false); } } debug_return; } static void mon_errpipe_cb(int fd, int what, void *v) { struct monitor_closure *mc = v; ssize_t n; debug_decl(mon_errpipe_cb, SUDO_DEBUG_EXEC); /* read errno or EOF from command pipe */ n = read(fd, mc->cstat, sizeof(struct command_status)); if (n == -1) { if (errno != EINTR && errno != EAGAIN) { sudo_warn(U_("error reading from pipe")); sudo_ev_loopbreak(mc->evbase); } } else { /* Got errno or EOF, either way we are done with errpipe. */ sudo_debug_printf(SUDO_DEBUG_DIAG, "%s: type: %d, val: %d", __func__, mc->cstat->type, mc->cstat->val); sudo_ev_del(mc->evbase, mc->errpipe_event); close(fd); } debug_return; } static void mon_backchannel_cb(int fd, int what, void *v) { struct monitor_closure *mc = v; struct command_status cstmp; ssize_t n; debug_decl(mon_backchannel_cb, SUDO_DEBUG_EXEC); /* read command from backchannel, should be a signal */ n = recv(fd, &cstmp, sizeof(cstmp), MSG_WAITALL); if (n != sizeof(cstmp)) { if (n == -1) { if (errno == EINTR || errno == EAGAIN) debug_return; sudo_warn(U_("error reading from socketpair")); } else { /* short read or EOF, parent process died? */ } sudo_ev_loopbreak(mc->evbase); } else { if (cstmp.type == CMD_SIGNO) { deliver_signal(cmnd_pid, cstmp.val, true); } else { sudo_warnx(U_("unexpected reply type on backchannel: %d"), cstmp.type); } } debug_return; } /* * Monitor process that creates a new session with the controlling tty, * resets signal handlers and forks a child to call exec_pty(). * Waits for status changes from the command and relays them to the * parent and relays signals from the parent to the command. * Returns an error if fork(2) fails, else calls _exit(2). */ static int exec_monitor(struct command_details *details, int backchannel) { struct command_status cstat; struct sudo_event_base *evbase; struct monitor_closure mc; sigaction_t sa; int errpipe[2], n; debug_decl(exec_monitor, SUDO_DEBUG_EXEC); /* Close unused fds. */ if (io_fds[SFD_MASTER] != -1) close(io_fds[SFD_MASTER]); if (io_fds[SFD_USERTTY] != -1) close(io_fds[SFD_USERTTY]); /* * We use a pipe to atomically handle signal notification within * the event loop. */ if (pipe_nonblock(signal_pipe) != 0) sudo_fatal(U_("unable to create pipe")); /* Reset SIGWINCH and SIGALRM. */ memset(&sa, 0, sizeof(sa)); sigemptyset(&sa.sa_mask); sa.sa_flags = SA_RESTART; sa.sa_handler = SIG_DFL; if (sudo_sigaction(SIGWINCH, &sa, NULL) != 0) sudo_warn(U_("unable to set handler for signal %d"), SIGWINCH); if (sudo_sigaction(SIGALRM, &sa, NULL) != 0) sudo_warn(U_("unable to set handler for signal %d"), SIGALRM); /* Ignore any SIGTTIN or SIGTTOU we get. */ 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); /* Block all signals in mon_handler(). */ sigfillset(&sa.sa_mask); /* Note: HP-UX poll() will not be interrupted if SA_RESTART is set. */ sa.sa_flags = SA_INTERRUPT; #ifdef SA_SIGINFO sa.sa_flags |= SA_SIGINFO; sa.sa_sigaction = mon_handler; #else sa.sa_handler = mon_handler; #endif if (sudo_sigaction(SIGCHLD, &sa, NULL) != 0) sudo_warn(U_("unable to set handler for signal %d"), SIGCHLD); /* Catch common signals so we can cleanup properly. */ sa.sa_flags = SA_RESTART; #ifdef SA_SIGINFO sa.sa_flags |= SA_SIGINFO; sa.sa_sigaction = mon_handler; #else sa.sa_handler = mon_handler; #endif if (sudo_sigaction(SIGHUP, &sa, NULL) != 0) sudo_warn(U_("unable to set handler for signal %d"), SIGHUP); 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(SIGTERM, &sa, NULL) != 0) sudo_warn(U_("unable to set handler for signal %d"), SIGTERM); if (sudo_sigaction(SIGTSTP, &sa, NULL) != 0) sudo_warn(U_("unable to set handler for signal %d"), SIGTSTP); 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); /* * Start a new session with the parent as the session leader * and the slave pty as the controlling terminal. * This allows us to be notified when the command has been suspended. */ if (setsid() == -1) { sudo_warn("setsid"); goto bad; } if (io_fds[SFD_SLAVE] != -1) { #ifdef TIOCSCTTY if (ioctl(io_fds[SFD_SLAVE], TIOCSCTTY, NULL) != 0) sudo_fatal(U_("unable to set controlling tty")); #else /* Set controlling tty by reopening slave. */ if ((n = open(slavename, O_RDWR)) >= 0) close(n); #endif } mon_pgrp = getpgrp(); /* save a copy of our process group */ /* * 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. */ if (pipeline) foreground = false; /* Start command and wait for it to stop or exit */ if (pipe(errpipe) == -1) sudo_fatal(U_("unable to create pipe")); cmnd_pid = sudo_debug_fork(); if (cmnd_pid == -1) { sudo_warn(U_("unable to fork")); goto bad; } if (cmnd_pid == 0) { /* We pass errno back to our parent via pipe on exec failure. */ close(backchannel); close(signal_pipe[0]); close(signal_pipe[1]); close(errpipe[0]); (void)fcntl(errpipe[1], F_SETFD, FD_CLOEXEC); restore_signals(); /* setup tty and exec command */ exec_pty(details, &cstat, errpipe[1]); while (write(errpipe[1], &cstat, sizeof(cstat)) == -1) { if (errno != EINTR) break; } _exit(1); } close(errpipe[1]); /* Send the command's pid to main sudo process. */ cstat.type = CMD_PID; cstat.val = cmnd_pid; ignore_result(send(backchannel, &cstat, sizeof(cstat), 0)); /* If any of stdin/stdout/stderr are pipes, close them in parent. */ if (io_fds[SFD_STDIN] != io_fds[SFD_SLAVE]) close(io_fds[SFD_STDIN]); if (io_fds[SFD_STDOUT] != io_fds[SFD_SLAVE]) close(io_fds[SFD_STDOUT]); if (io_fds[SFD_STDERR] != io_fds[SFD_SLAVE]) close(io_fds[SFD_STDERR]); /* Put command in its own process group. */ cmnd_pgrp = cmnd_pid; setpgid(cmnd_pid, cmnd_pgrp); /* Make the command the foreground process for the pty slave. */ if (foreground && !ISSET(details->flags, CD_EXEC_BG)) { do { n = tcsetpgrp(io_fds[SFD_SLAVE], cmnd_pgrp); } while (n == -1 && errno == EINTR); } /* * Create new event base and register read events for the * signal pipe, error pipe, and backchannel. */ evbase = sudo_ev_base_alloc(); if (evbase == NULL) sudo_fatal(NULL); memset(&cstat, 0, sizeof(cstat)); mc.cstat = &cstat; mc.evbase = evbase; mc.backchannel = backchannel; mc.alive = true; mc.signal_pipe_event = sudo_ev_alloc(signal_pipe[0], SUDO_EV_READ|SUDO_EV_PERSIST, mon_signal_pipe_cb, &mc); if (mc.signal_pipe_event == NULL) sudo_fatal(NULL); if (sudo_ev_add(evbase, mc.signal_pipe_event, NULL, false) == -1) sudo_fatal(U_("unable to add event to queue")); mc.errpipe_event = sudo_ev_alloc(errpipe[0], SUDO_EV_READ|SUDO_EV_PERSIST, mon_errpipe_cb, &mc); if (mc.errpipe_event == NULL) sudo_fatal(NULL); if (sudo_ev_add(evbase, mc.errpipe_event, NULL, false) == -1) sudo_fatal(U_("unable to add event to queue")); mc.backchannel_event = sudo_ev_alloc(backchannel, SUDO_EV_READ|SUDO_EV_PERSIST, mon_backchannel_cb, &mc); if (mc.backchannel_event == NULL) sudo_fatal(NULL); if (sudo_ev_add(evbase, mc.backchannel_event, NULL, false) == -1) sudo_fatal(U_("unable to add event to queue")); /* * Wait for errno on pipe, signal on backchannel or for SIGCHLD. * The event loop ends when the child is no longer running and * the error pipe is closed. */ (void) sudo_ev_loop(evbase, 0); if (mc.alive) { /* XXX An error occurred, should send a message back. */ sudo_debug_printf(SUDO_DEBUG_ERROR, "Command still running after event loop exit, sending SIGKILL"); kill(cmnd_pid, SIGKILL); } else { /* Send parent status. */ send_status(backchannel, &cstat); } sudo_debug_exit_int(__func__, __FILE__, __LINE__, sudo_debug_subsys, 1); _exit(1); bad: debug_return_int(errno); } /* * Sets up std{in,out,err} and executes the actual command. * Returns only if execve() fails. */ static void exec_pty(struct command_details *details, struct command_status *cstat, int errfd) { pid_t self = getpid(); debug_decl(exec_pty, SUDO_DEBUG_EXEC); /* Register cleanup function */ sudo_fatal_callback_register(pty_cleanup); /* Set command process group here too to avoid a race. */ setpgid(0, self); /* Wire up standard fds, note that stdout/stderr may be pipes. */ if (dup2(io_fds[SFD_STDIN], STDIN_FILENO) == -1 || dup2(io_fds[SFD_STDOUT], STDOUT_FILENO) == -1 || dup2(io_fds[SFD_STDERR], STDERR_FILENO) == -1) sudo_fatal("dup2"); /* Wait for parent to grant us the tty if we are foreground. */ if (foreground && !ISSET(details->flags, CD_EXEC_BG)) { while (tcgetpgrp(io_fds[SFD_SLAVE]) != self) ; /* spin */ } /* We have guaranteed that the slave fd is > 2 */ if (io_fds[SFD_SLAVE] != -1) close(io_fds[SFD_SLAVE]); if (io_fds[SFD_STDIN] != io_fds[SFD_SLAVE]) close(io_fds[SFD_STDIN]); if (io_fds[SFD_STDOUT] != io_fds[SFD_SLAVE]) close(io_fds[SFD_STDOUT]); if (io_fds[SFD_STDERR] != io_fds[SFD_SLAVE]) close(io_fds[SFD_STDERR]); /* Execute command; only returns on error. */ exec_cmnd(details, cstat, errfd); 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)); }