--- embedaddon/sudo/src/exec_pty.c 2012/05/29 12:26:49 1.1.1.2 +++ embedaddon/sudo/src/exec_pty.c 2013/07/22 10:46:13 1.1.1.4 @@ -1,5 +1,5 @@ /* - * Copyright (c) 2009-2011 Todd C. Miller + * Copyright (c) 2009-2013 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 @@ -17,7 +17,6 @@ #include #include -#include #ifdef HAVE_SYS_SYSMACROS_H # include #endif @@ -86,20 +85,21 @@ struct io_buffer { int rfd; /* reader (producer) */ int wfd; /* writer (consumer) */ bool (*action)(const char *buf, unsigned int len); - char buf[16 * 1024]; + char buf[32 * 1024]; }; 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, child, child_pgrp; +static pid_t ppgrp, cmnd_pgrp, mon_pgrp; static sigset_t ttyblock; static struct io_buffer *iobufs; static void flush_output(void); static int exec_monitor(struct command_details *details, int backchannel); -static void exec_pty(struct command_details *detail, int *errfd); +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); @@ -107,10 +107,10 @@ static int safe_close(int fd); static void check_foreground(void); /* - * Cleanup hook for error()/errorx() + * Cleanup hook for fatal()/fatalx() */ -void -cleanup(int gotsignal) +static void +pty_cleanup(void) { debug_decl(cleanup, SUDO_DEBUG_EXEC); @@ -128,6 +128,45 @@ cleanup(int gotsignal) } /* + * 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 +void +mon_handler(int s, siginfo_t *info, void *context) +{ + unsigned char signo = (unsigned char)s; + + /* + * If the signal came from the command we ran, just ignore + * it since we don't want the command 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 (info != NULL && info->si_code == SI_USER && 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. + */ + ignore_result(write(signal_pipe[1], &signo, sizeof(signo))); +} +#else +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. + */ + ignore_result(write(signal_pipe[1], &signo, sizeof(signo))); +} +#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. @@ -141,7 +180,7 @@ pty_setup(uid_t uid, const char *tty, const char *utmp if (io_fds[SFD_USERTTY] != -1) { if (!get_pty(&io_fds[SFD_MASTER], &io_fds[SFD_SLAVE], slavename, sizeof(slavename), uid)) - error(1, _("unable to allocate pty")); + fatal(_("unable to allocate pty")); /* Add entry to utmp/utmpx? */ if (utmp_user != NULL) utmp_login(tty, slavename, io_fds[SFD_SLAVE], utmp_user); @@ -290,22 +329,23 @@ check_foreground(void) /* * Suspend sudo if the underlying command is suspended. - * Returns SIGCONT_FG if the child should be resume in the + * 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 n, oldmode = ttymode, rval = 0; + int n, rval = 0; debug_decl(suspend_parent, SUDO_DEBUG_EXEC); switch (signo) { case SIGTTOU: case SIGTTIN: /* - * If we are the foreground process, just resume the child. - * Otherwise, re-send the signal with the handler disabled. + * 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(); @@ -316,10 +356,9 @@ suspend_parent(int signo) } while (!n && errno == EINTR); ttymode = TERM_RAW; } - rval = SIGCONT_FG; /* resume child in foreground */ + rval = SIGCONT_FG; /* resume command in foreground */ break; } - ttymode = TERM_RAW; /* FALLTHROUGH */ case SIGSTOP: case SIGTSTP: @@ -327,45 +366,55 @@ suspend_parent(int signo) flush_output(); /* Restore original tty mode before suspending. */ - if (oldmode != TERM_COOKED) { + if (ttymode != TERM_COOKED) { do { n = term_restore(io_fds[SFD_USERTTY], 0); } while (!n && errno == EINTR); } - /* Suspend self and continue child when we resume. */ - zero_bytes(&sa, sizeof(sa)); - sigemptyset(&sa.sa_mask); - sa.sa_flags = SA_INTERRUPT; /* do not restart syscalls */ - sa.sa_handler = SIG_DFL; - sigaction(signo, &sa, &osa); - sudo_debug_printf(SUDO_DEBUG_INFO, "kill parent %d", signo); + 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; + sudo_sigaction(signo, &sa, &osa); + } + sudo_debug_printf(SUDO_DEBUG_INFO, "kill parent SIG%s", signame); if (killpg(ppgrp, signo) != 0) - warning("killpg(%d, %d)", (int)ppgrp, signo); + warning("killpg(%d, SIG%s)", (int)ppgrp, signame); /* Check foreground/background status on resume. */ check_foreground(); /* - * Only modify term if we are foreground process and either - * the old tty mode was not cooked or child got SIGTT{IN,OU} + * 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", oldmode, ttymode); + foreground ? "foreground" : "background", ttymode, + foreground ? TERM_RAW : TERM_COOKED); - if (ttymode != TERM_COOKED) { - if (foreground) { - /* Set raw mode. */ - do { - n = term_raw(io_fds[SFD_USERTTY], 0); - } while (!n && errno == EINTR); - } else { - /* Background process, no access to tty. */ - ttymode = TERM_COOKED; - } + if (foreground) { + /* Foreground process, set tty to raw mode. */ + do { + n = term_raw(io_fds[SFD_USERTTY], 0); + } while (!n && errno == EINTR); + ttymode = TERM_RAW; + } else { + /* Background process, no access to tty. */ + ttymode = TERM_COOKED; } - sigaction(signo, &osa, NULL); + if (signo != SIGSTOP) + sudo_sigaction(signo, &osa, NULL); rval = ttymode == TERM_RAW ? SIGCONT_FG : SIGCONT_BG; break; } @@ -374,12 +423,12 @@ suspend_parent(int signo) } /* - * Kill child with increasing urgency. + * Kill command with increasing urgency. */ void -terminate_child(pid_t pid, bool use_pgrp) +terminate_command(pid_t pid, bool use_pgrp) { - debug_decl(terminate_child, SUDO_DEBUG_EXEC); + debug_decl(terminate_command, SUDO_DEBUG_EXEC); /* * Note that SIGCHLD will interrupt the sleep() @@ -460,7 +509,7 @@ perform_io(fd_set *fdsr, fd_set *fdsw, struct command_ sudo_debug_printf(SUDO_DEBUG_INFO, "read %d bytes from fd %d", n, iob->rfd); if (!iob->action(iob->buf + iob->len, n)) - terminate_child(child, true); + terminate_command(cmnd_pid, true); iob->len += n; break; } @@ -509,23 +558,25 @@ perform_io(fd_set *fdsr, fd_set *fdsw, struct command_ * Returns the child pid. */ int -fork_pty(struct command_details *details, int sv[], int *maxfd) +fork_pty(struct command_details *details, int sv[], int *maxfd, sigset_t *omask) { struct command_status cstat; struct io_buffer *iob; int io_pipe[3][2], n; 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 */ - - zero_bytes(&sa, sizeof(sa)); + + memset(&sa, 0, sizeof(sa)); sigemptyset(&sa.sa_mask); - + if (io_fds[SFD_USERTTY] != -1) { sa.sa_flags = SA_RESTART; sa.sa_handler = sigwinch; - sigaction(SIGWINCH, &sa, NULL); + sudo_sigaction(SIGWINCH, &sa, NULL); } /* So we can block tty-generated signals */ @@ -569,7 +620,7 @@ fork_pty(struct command_details *details, int sv[], in sudo_debug_printf(SUDO_DEBUG_INFO, "stdin not a tty, creating a pipe"); pipeline = true; if (pipe(io_pipe[STDIN_FILENO]) != 0) - error(1, _("unable to create pipe")); + fatal(_("unable to create pipe")); iobufs = io_buf_new(STDIN_FILENO, io_pipe[STDIN_FILENO][1], log_stdin, iobufs); io_fds[SFD_STDIN] = io_pipe[STDIN_FILENO][0]; @@ -578,7 +629,7 @@ fork_pty(struct command_details *details, int sv[], in sudo_debug_printf(SUDO_DEBUG_INFO, "stdout not a tty, creating a pipe"); pipeline = true; if (pipe(io_pipe[STDOUT_FILENO]) != 0) - error(1, _("unable to create pipe")); + fatal(_("unable to create pipe")); iobufs = io_buf_new(io_pipe[STDOUT_FILENO][0], STDOUT_FILENO, log_stdout, iobufs); io_fds[SFD_STDOUT] = io_pipe[STDOUT_FILENO][1]; @@ -586,22 +637,28 @@ fork_pty(struct command_details *details, int sv[], in 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) - error(1, _("unable to create pipe")); + fatal(_("unable to create pipe")); iobufs = 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; + sudo_sigaction(SIGTTIN, &sa, NULL); + sudo_sigaction(SIGTTOU, &sa, NULL); + /* 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; - sigaction(SIGTSTP, &sa, NULL); +#endif + sudo_sigaction(SIGTSTP, &sa, NULL); - /* We don't want to receive SIGTTIN/SIGTTOU, getting EIO is preferable. */ - sa.sa_handler = SIG_IGN; - sigaction(SIGTTIN, &sa, NULL); - sigaction(SIGTTOU, &sa, NULL); - if (foreground) { /* Copy terminal attrs from user tty -> pty slave. */ if (term_copy(io_fds[SFD_USERTTY], io_fds[SFD_SLAVE])) { @@ -609,14 +666,14 @@ fork_pty(struct command_details *details, int sv[], in sync_ttysize(io_fds[SFD_USERTTY], io_fds[SFD_SLAVE]); } - /* Start out in raw mode if we are not part of a pipeline. */ - if (!pipeline) { + /* Start out in raw mode unless part of a pipeline or backgrounded. */ + if (!pipeline && !ISSET(details->flags, CD_EXEC_BG)) { ttymode = TERM_RAW; do { n = term_raw(io_fds[SFD_USERTTY], 0); } while (!n && errno == EINTR); if (!n) - error(1, _("unable to set terminal to raw mode")); + fatal(_("unable to set terminal to raw mode")); } } @@ -625,12 +682,23 @@ fork_pty(struct command_details *details, int sv[], in * or certain pam modules won't be able to track their state. */ if (policy_init_session(details) != true) - errorx(1, _("policy plugin failed session initialization")); + fatalx(_("policy plugin failed session initialization")); + /* + * 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: - error(1, _("unable to fork")); + fatal(_("unable to fork")); break; case 0: /* child */ @@ -638,19 +706,18 @@ fork_pty(struct command_details *details, int sv[], in close(signal_pipe[0]); close(signal_pipe[1]); fcntl(sv[1], F_SETFD, FD_CLOEXEC); - if (exec_setup(details, slavename, io_fds[SFD_SLAVE]) == true) { - /* 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]); - } + 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; - send(sv[1], &cstat, sizeof(cstat), 0); + ignore_result(send(sv[1], &cstat, sizeof(cstat), 0)); _exit(1); } @@ -659,7 +726,7 @@ fork_pty(struct command_details *details, int sv[], in close(io_pipe[STDIN_FILENO][0]); if (io_pipe[STDOUT_FILENO][1]) close(io_pipe[STDOUT_FILENO][1]); - if (io_pipe[STDERR_FILENO][1]) + if (io_pipe[STDERR_FILENO][1]) close(io_pipe[STDERR_FILENO][1]); for (iob = iobufs; iob; iob = iob->next) { @@ -764,27 +831,35 @@ fd_set_iobs(fd_set *fdsr, fd_set *fdsw) 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 signal %d%s", signo, - from_parent ? " from parent" : ""); + sudo_debug_printf(SUDO_DEBUG_INFO, "received SIG%s%s", + signame, from_parent ? " from parent" : ""); switch (signo) { case SIGALRM: - terminate_child(pid, true); + terminate_command(pid, true); break; case SIGCONT_FG: /* Continue in foreground, grant it controlling tty. */ do { - status = tcsetpgrp(io_fds[SFD_SLAVE], child_pgrp); + 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], getpid()); + status = tcsetpgrp(io_fds[SFD_SLAVE], mon_pgrp); } while (status == -1 && errno == EINTR); killpg(pid, SIGCONT); break; @@ -792,7 +867,7 @@ deliver_signal(pid_t pid, int signo, bool from_parent) _exit(1); /* XXX */ /* NOTREACHED */ default: - /* Relay signal to child. */ + /* Relay signal to command. */ killpg(pid, signo); break; } @@ -826,10 +901,10 @@ send_status(int fd, struct command_status *cstat) } /* - * Wait for child status after receiving SIGCHLD. - * If the child was stopped, the status is send back to the parent. + * 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 child is still alive, else false. + * Returns true if command is still alive, else false. */ static bool handle_sigchld(int backchannel, struct command_status *cstat) @@ -839,25 +914,34 @@ handle_sigchld(int backchannel, struct command_status pid_t pid; debug_decl(handle_sigchld, SUDO_DEBUG_EXEC); - /* read child status */ + /* read command status */ do { - pid = waitpid(child, &status, WUNTRACED|WNOHANG); + pid = waitpid(cmnd_pid, &status, WUNTRACED|WNOHANG); } while (pid == -1 && errno == EINTR); - if (pid == child) { + if (pid == cmnd_pid) { if (cstat->type != CMD_ERRNO) { + char signame[SIG2STR_MAX]; + cstat->type = CMD_WSTATUS; cstat->val = status; if (WIFSTOPPED(status)) { - sudo_debug_printf(SUDO_DEBUG_INFO, "command stopped, signal %d", - WSTOPSIG(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 { - child_pgrp = tcgetpgrp(io_fds[SFD_SLAVE]); - } while (child_pgrp == -1 && errno == EINTR); + pid = tcgetpgrp(io_fds[SFD_SLAVE]); + } while (pid == -1 && errno == EINTR); + if (pid != mon_pgrp) + cmnd_pgrp = pid; if (send_status(backchannel, cstat) == -1) return alive; /* XXX */ } else if (WIFSIGNALED(status)) { - sudo_debug_printf(SUDO_DEBUG_INFO, "command killed, signal %d", - WTERMSIG(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)); @@ -883,7 +967,7 @@ exec_monitor(struct command_details *details, int back struct timeval tv; fd_set *fdsr; sigaction_t sa; - int errpipe[2], maxfd, n, status; + int errpipe[2], maxfd, n; bool alive = true; unsigned char signo; debug_decl(exec_monitor, SUDO_DEBUG_EXEC); @@ -899,41 +983,54 @@ exec_monitor(struct command_details *details, int back * the select() loop. */ if (pipe_nonblock(signal_pipe) != 0) - error(1, _("unable to create pipe")); + fatal(_("unable to create pipe")); /* Reset SIGWINCH and SIGALRM. */ - zero_bytes(&sa, sizeof(sa)); + memset(&sa, 0, sizeof(sa)); sigemptyset(&sa.sa_mask); sa.sa_flags = SA_RESTART; sa.sa_handler = SIG_DFL; - sigaction(SIGWINCH, &sa, NULL); - sigaction(SIGALRM, &sa, NULL); + sudo_sigaction(SIGWINCH, &sa, NULL); + sudo_sigaction(SIGALRM, &sa, NULL); /* Ignore any SIGTTIN or SIGTTOU we get. */ sa.sa_handler = SIG_IGN; - sigaction(SIGTTIN, &sa, NULL); - sigaction(SIGTTOU, &sa, NULL); + sudo_sigaction(SIGTTIN, &sa, NULL); + sudo_sigaction(SIGTTOU, &sa, NULL); + /* Block all signals in mon_handler(). */ + sigfillset(&sa.sa_mask); + /* Note: HP-UX select() will not be interrupted if SA_RESTART set */ sa.sa_flags = SA_INTERRUPT; - sa.sa_handler = handler; - sigaction(SIGCHLD, &sa, NULL); +#ifdef SA_SIGINFO + sa.sa_flags |= SA_SIGINFO; + sa.sa_sigaction = mon_handler; +#else + sa.sa_handler = mon_handler; +#endif + sudo_sigaction(SIGCHLD, &sa, NULL); /* Catch common signals so we can cleanup properly. */ sa.sa_flags = SA_RESTART; - sa.sa_handler = handler; - sigaction(SIGHUP, &sa, NULL); - sigaction(SIGINT, &sa, NULL); - sigaction(SIGQUIT, &sa, NULL); - sigaction(SIGTERM, &sa, NULL); - sigaction(SIGTSTP, &sa, NULL); - sigaction(SIGUSR1, &sa, NULL); - sigaction(SIGUSR2, &sa, NULL); +#ifdef SA_SIGINFO + sa.sa_flags |= SA_SIGINFO; + sa.sa_sigaction = mon_handler; +#else + sa.sa_handler = mon_handler; +#endif + sudo_sigaction(SIGHUP, &sa, NULL); + sudo_sigaction(SIGINT, &sa, NULL); + sudo_sigaction(SIGQUIT, &sa, NULL); + sudo_sigaction(SIGTERM, &sa, NULL); + sudo_sigaction(SIGTSTP, &sa, NULL); + sudo_sigaction(SIGUSR1, &sa, NULL); + sudo_sigaction(SIGUSR2, &sa, NULL); /* * 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 child has been suspended. + * This allows us to be notified when the command has been suspended. */ if (setsid() == -1) { warning("setsid"); @@ -942,7 +1039,7 @@ exec_monitor(struct command_details *details, int back if (io_fds[SFD_SLAVE] != -1) { #ifdef TIOCSCTTY if (ioctl(io_fds[SFD_SLAVE], TIOCSCTTY, NULL) != 0) - error(1, _("unable to set controlling tty")); + fatal(_("unable to set controlling tty")); #else /* Set controlling tty by reopening slave. */ if ((n = open(slavename, O_RDWR)) >= 0) @@ -950,6 +1047,8 @@ exec_monitor(struct command_details *details, int back #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. @@ -961,13 +1060,13 @@ exec_monitor(struct command_details *details, int back /* Start command and wait for it to stop or exit */ if (pipe(errpipe) == -1) - error(1, _("unable to create pipe")); - child = sudo_debug_fork(); - if (child == -1) { + fatal(_("unable to create pipe")); + cmnd_pid = sudo_debug_fork(); + if (cmnd_pid == -1) { warning(_("unable to fork")); goto bad; } - if (child == 0) { + if (cmnd_pid == 0) { /* We pass errno back to our parent via pipe on exec failure. */ close(backchannel); close(signal_pipe[0]); @@ -977,14 +1076,17 @@ exec_monitor(struct command_details *details, int back restore_signals(); /* setup tty and exec command */ - exec_pty(details, &errpipe[1]); - cstat.type = CMD_ERRNO; - cstat.val = errno; + exec_pty(details, &cstat, &errpipe[1]); ignore_result(write(errpipe[1], &cstat, sizeof(cstat))); _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]); @@ -993,16 +1095,15 @@ exec_monitor(struct command_details *details, int back if (io_fds[SFD_STDERR] != io_fds[SFD_SLAVE]) close(io_fds[SFD_STDERR]); - /* - * Put child in its own process group. If we are starting the command - * in the foreground, assign its pgrp to the tty. - */ - child_pgrp = child; - setpgid(child, child_pgrp); - if (foreground) { + /* 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 { - status = tcsetpgrp(io_fds[SFD_SLAVE], child_pgrp); - } while (status == -1 && errno == EINTR); + n = tcsetpgrp(io_fds[SFD_SLAVE], cmnd_pgrp); + } while (n == -1 && errno == EINTR); } /* Wait for errno on pipe, signal on backchannel or for SIGCHLD */ @@ -1040,13 +1141,13 @@ exec_monitor(struct command_details *details, int back } /* * Handle SIGCHLD specially and deliver other signals - * directly to the child. + * directly to the command. */ if (signo == SIGCHLD) { if (!handle_sigchld(backchannel, &cstat)) alive = false; } else { - deliver_signal(child, signo, false); + deliver_signal(cmnd_pid, signo, false); } continue; } @@ -1080,14 +1181,14 @@ exec_monitor(struct command_details *details, int back cstmp.type); continue; } - deliver_signal(child, cstmp.val, true); + deliver_signal(cmnd_pid, cstmp.val, true); } } done: if (alive) { /* XXX An error occurred, should send an error back. */ - kill(child, SIGKILL); + kill(cmnd_pid, SIGKILL); } else { /* Send parent status. */ send_status(backchannel, &cstat); @@ -1179,22 +1280,26 @@ flush_output(void) * Returns only if execve() fails. */ static void -exec_pty(struct command_details *details, int *errfd) +exec_pty(struct command_details *details, + struct command_status *cstat, int *errfd) { pid_t self = getpid(); debug_decl(exec_pty, SUDO_DEBUG_EXEC); - /* Set child process group here too to avoid a race. */ + /* Register cleanup function */ + 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) - error(1, "dup2"); + fatal("dup2"); /* Wait for parent to grant us the tty if we are foreground. */ - if (foreground) { + if (foreground && !ISSET(details->flags, CD_EXEC_BG)) { while (tcgetpgrp(io_fds[SFD_SLAVE]) != self) ; /* spin */ } @@ -1209,30 +1314,9 @@ exec_pty(struct command_details *details, int *errfd) if (io_fds[SFD_STDERR] != io_fds[SFD_SLAVE]) close(io_fds[SFD_STDERR]); - sudo_debug_execve(SUDO_DEBUG_INFO, details->command, - details->argv, details->envp); + /* Execute command; only returns on error. */ + exec_cmnd(details, cstat, errfd); - if (details->closefrom >= 0) { - int maxfd = details->closefrom; - dup2(*errfd, maxfd); - (void)fcntl(maxfd, F_SETFD, FD_CLOEXEC); - *errfd = maxfd++; - if (sudo_debug_fd_set(maxfd) != -1) - maxfd++; - closefrom(maxfd); - } -#ifdef HAVE_SELINUX - if (ISSET(details->flags, CD_RBAC_ENABLED)) { - selinux_execve(details->command, details->argv, details->envp, - ISSET(details->flags, CD_NOEXEC)); - } else -#endif - { - sudo_execve(details->command, details->argv, details->envp, - ISSET(details->flags, CD_NOEXEC)); - } - sudo_debug_printf(SUDO_DEBUG_ERROR, "unable to exec %s: %s", - details->command, strerror(errno)); debug_return; }