/* * Copyright (c) 2009-2010 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 #ifdef HAVE_TERMIOS_H # include #else # include #endif /* HAVE_TERMIOS_H */ #include #ifdef HAVE_SYS_SELECT_H # include #endif /* HAVE_SYS_SELECT_H */ #include #ifdef STDC_HEADERS # include # include #else # ifdef HAVE_STDLIB_H # include # endif #endif /* STDC_HEADERS */ #ifdef HAVE_STRING_H # if defined(HAVE_MEMORY_H) && !defined(STDC_HEADERS) # include # endif # include #else # ifdef HAVE_STRINGS_H # include # endif #endif /* HAVE_STRING_H */ #ifdef HAVE_UNISTD_H # include #endif /* HAVE_UNISTD_H */ #if TIME_WITH_SYS_TIME # include #endif #include #include #include #include #include #ifdef HAVE_SELINUX # include #endif #if !defined(NSIG) # if defined(_NSIG) # define NSIG _NSIG # elif defined(__NSIG) # define NSIG __NSIG # else # define NSIG 64 # endif #endif #include "sudo.h" /* XXX? */ #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 #define TERM_COOKED 0 #define TERM_RAW 1 #if !defined(TIOCGSIZE) && defined(TIOCGWINSZ) # define TIOCGSIZE TIOCGWINSZ # define TIOCSSIZE TIOCSWINSZ # define ttysize winsize # define ts_cols ws_col #endif struct io_buffer { struct io_buffer *next; int len; /* buffer length (how much produced) */ int off; /* write position (how much already consumed) */ int rfd; /* reader (producer) */ int wfd; /* writer (consumer) */ int (*action)(char *buf, unsigned int len); char buf[16 * 1024]; }; static int script_fds[6] = { -1, -1, -1, -1, -1, -1}; static int pipeline = FALSE; static sig_atomic_t recvsig[NSIG]; static sig_atomic_t ttymode = TERM_COOKED; static sig_atomic_t tty_initialized = 0; static sigset_t ttyblock; static pid_t ppgrp, child; static int child_status; static int foreground; static char slavename[PATH_MAX]; static int suspend_parent(int signo, int fd, struct io_buffer *output); static void flush_output(struct io_buffer *iobufs); static int perform_io(struct io_buffer *iobufs, fd_set *fdsr, fd_set *fdsw); static void handler(int s); static int script_child(const char *path, char *argv[], char *envp[], int, int); static void script_run(const char *path, char *argv[], char *envp[], int); static void sigwinch(int s); static void sync_ttysize(int src, int dst); static void deliver_signal(pid_t pid, int signo); /* sudo.c */ extern struct plugin_container_list io_plugins; void script_setup(uid_t uid) { script_fds[SFD_USERTTY] = open(_PATH_TTY, O_RDWR|O_NOCTTY, 0); if (script_fds[SFD_USERTTY] == -1) errorx(1, "tty required for transcript support"); if (!get_pty(&script_fds[SFD_MASTER], &script_fds[SFD_SLAVE], slavename, sizeof(slavename), uid)) error(1, "Can't get pty"); } /* Call I/O plugin tty input log method. */ static int log_ttyin(char *buf, unsigned int n) { struct plugin_container *plugin; sigset_t omask; int rval = TRUE; sigprocmask(SIG_BLOCK, &ttyblock, &omask); tq_foreach_fwd(&io_plugins, plugin) { if (plugin->u.io->log_ttyin) { if (!plugin->u.io->log_ttyin(buf, n)) { rval = FALSE; break; } } } sigprocmask(SIG_SETMASK, &omask, NULL); return rval; } /* Call I/O plugin stdin log method. */ static int log_stdin(char *buf, unsigned int n) { struct plugin_container *plugin; sigset_t omask; int rval = TRUE; sigprocmask(SIG_BLOCK, &ttyblock, &omask); tq_foreach_fwd(&io_plugins, plugin) { if (plugin->u.io->log_stdin) { if (!plugin->u.io->log_stdin(buf, n)) { rval = FALSE; break; } } } sigprocmask(SIG_SETMASK, &omask, NULL); return rval; } /* Call I/O plugin tty output log method. */ static int log_ttyout(char *buf, unsigned int n) { struct plugin_container *plugin; sigset_t omask; int rval = TRUE; sigprocmask(SIG_BLOCK, &ttyblock, &omask); tq_foreach_fwd(&io_plugins, plugin) { if (plugin->u.io->log_ttyout) { if (!plugin->u.io->log_ttyout(buf, n)) { rval = FALSE; break; } } } sigprocmask(SIG_SETMASK, &omask, NULL); return rval; } /* Call I/O plugin stdout log method. */ static int log_stdout(char *buf, unsigned int n) { struct plugin_container *plugin; sigset_t omask; int rval = TRUE; sigprocmask(SIG_BLOCK, &ttyblock, &omask); tq_foreach_fwd(&io_plugins, plugin) { if (plugin->u.io->log_stdout) { if (!plugin->u.io->log_stdout(buf, n)) { rval = FALSE; break; } } } sigprocmask(SIG_SETMASK, &omask, NULL); return rval; } /* Call I/O plugin stderr log method. */ static int log_stderr(char *buf, unsigned int n) { struct plugin_container *plugin; sigset_t omask; int rval = TRUE; sigprocmask(SIG_BLOCK, &ttyblock, &omask); tq_foreach_fwd(&io_plugins, plugin) { if (plugin->u.io->log_stderr) { if (!plugin->u.io->log_stderr(buf, n)) { rval = FALSE; break; } } } sigprocmask(SIG_SETMASK, &omask, NULL); return rval; } static void check_foreground(void) { foreground = tcgetpgrp(script_fds[SFD_USERTTY]) == ppgrp; if (foreground && !tty_initialized) { if (term_copy(script_fds[SFD_USERTTY], script_fds[SFD_SLAVE])) { tty_initialized = 1; sync_ttysize(script_fds[SFD_USERTTY], script_fds[SFD_SLAVE]); } } } /* * Suspend sudo if the underlying command is suspended. * Returns SIGUSR1 if the child should be resume in foreground else SIGUSR2. */ static int suspend_parent(int signo, int fd, struct io_buffer *iobufs) { sigaction_t sa, osa; int n, oldmode = ttymode, rval = 0; 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 (!foreground) check_foreground(); if (foreground) { if (ttymode != TERM_RAW) { do { n = term_raw(script_fds[SFD_USERTTY], 0); } while (!n && errno == EINTR); ttymode = TERM_RAW; } rval = SIGUSR1; /* resume child in foreground */ break; } ttymode = TERM_RAW; /* FALLTHROUGH */ case SIGSTOP: case SIGTSTP: /* Flush any remaining output before suspending. */ flush_output(iobufs); /* Restore original tty mode before suspending. */ if (oldmode != TERM_COOKED) { do { n = term_restore(script_fds[SFD_USERTTY], 0); } while (!n && errno == EINTR); } /* Suspend self and continue child when we resume. */ sa.sa_handler = SIG_DFL; sigaction(signo, &sa, &osa); sudo_debug(8, "kill parent %d", signo); killpg(ppgrp, signo); /* 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} */ sudo_debug(8, "parent is in %sground, ttymode %d -> %d", foreground ? "fore" : "back", oldmode, ttymode); if (ttymode != TERM_COOKED) { if (foreground) { /* Set raw mode. */ do { n = term_raw(script_fds[SFD_USERTTY], 0); } while (!n && errno == EINTR); } else { /* Background process, no access to tty. */ ttymode = TERM_COOKED; } } sigaction(signo, &osa, NULL); rval = ttymode == TERM_RAW ? SIGUSR1 : SIGUSR2; break; } return(rval); } /* * Like execve(2) but falls back to running through /bin/sh * like execvp(3) if we get ENOEXEC. */ static int my_execve(const char *path, char *const argv[], char *const envp[]) { execve(path, argv, envp); if (errno == ENOEXEC) { int argc; char **nargv; for (argc = 0; argv[argc] != NULL; argc++) continue; nargv = emalloc2(argc + 2, sizeof(char *)); nargv[0] = "sh"; nargv[1] = (char *)path; memcpy(nargv + 2, argv + 1, argc * sizeof(char *)); execve(_PATH_BSHELL, nargv, envp); efree(nargv); } return -1; } static void terminate_child(pid_t pid, int use_pgrp) { /* * Kill child with increasing urgency. * Note that SIGCHLD will interrupt the sleep() */ if (use_pgrp) { killpg(pid, SIGHUP); killpg(pid, SIGTERM); sleep(2); killpg(pid, SIGKILL); } else { kill(pid, SIGHUP); kill(pid, SIGTERM); sleep(2); kill(pid, SIGKILL); } } static struct io_buffer * io_buf_new(int rfd, int wfd, int (*action)(char *, unsigned int), struct io_buffer *head) { struct io_buffer *iob; iob = emalloc(sizeof(*iob)); zero_bytes(iob, sizeof(*iob)); iob->rfd = rfd; iob->wfd = wfd; iob->action = action; iob->next = head; return iob; } /* * Read/write iobufs depending on fdsr and fdsw. * Returns the number of errors. */ static int perform_io(struct io_buffer *iobufs, fd_set *fdsr, fd_set *fdsw) { struct io_buffer *iob; int n, errors = 0; for (iob = iobufs; iob; iob = iob->next) { if (iob->rfd != -1 && FD_ISSET(iob->rfd, fdsr)) { do { n = read(iob->rfd, iob->buf + iob->len, sizeof(iob->buf) - iob->len); } while (n == -1 && errno == EINTR); if (n == -1) { if (errno != EAGAIN) break; } else if (n == 0) { /* got EOF */ close(iob->rfd); iob->rfd = -1; } else { if (!iob->action(iob->buf + iob->len, n)) terminate_child(child, TRUE); iob->len += n; } } if (iob->wfd != -1 && FD_ISSET(iob->wfd, fdsw)) { do { n = write(iob->wfd, iob->buf + iob->off, iob->len - iob->off); } while (n == -1 && errno == EINTR); if (n == -1) { if (errno == EPIPE) { /* other end of pipe closed */ if (iob->rfd != -1) { close(iob->rfd); iob->rfd = -1; } close(iob->wfd); iob->wfd = -1; continue; } if (errno != EAGAIN) errors++; } else { iob->off += n; } } } return errors; } /* * 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. * There are three processes: * 1) parent, which forks a child and does all the I/O passing. * Handles job control signals send by its child to bridge the * two sessions (and ttys). * 2) child, creates a new session so it can receive notification of * tty stop signals (SIGTSTP, SIGTTIN, SIGTTOU). Waits for the * command to stop or die and passes back tty stop signals to parent * so job control works in the user's shell. * 3) grandchild, executes the actual command with the pty slave as its * controlling tty, belongs to child's session but has its own pgrp. */ int script_execve(struct command_details *details, char *argv[], char *envp[], struct command_status *cstat) { sigaction_t sa; struct io_buffer *iob, *iobufs = NULL; int n, nready; int io_pipe[3][2], sv[2]; fd_set *fdsr, *fdsw; int rbac_enabled = 0; int log_io, maxfd; cstat->type = 0; /* XXX */ log_io = !tq_empty(&io_plugins); #ifdef HAVE_SELINUX rbac_enabled = is_selinux_enabled() > 0 && user_role != NULL; if (rbac_enabled) { selinux_prefork(user_role, user_type, script_fds[SFD_SLAVE]); if (log_io) { /* Re-open slave fd after it has been relabeled */ close(script_fds[SFD_SLAVE]); script_fds[SFD_SLAVE] = open(slavename, O_RDWR|O_NOCTTY, 0); if (script_fds[SFD_SLAVE] == -1) error(1, "cannot open %s", slavename); } } #endif ppgrp = getpgrp(); /* parent's pgrp, so child can signal us */ /* * We communicate with the child over a bi-directional pipe. * Parent sends signal info to child and child sends back wait status. */ if (socketpair(PF_UNIX, SOCK_DGRAM, 0, sv) != 0) error(1, "cannot create sockets"); zero_bytes(&sa, sizeof(sa)); sigemptyset(&sa.sa_mask); /* Note: HP-UX select() will not be interrupted if SA_RESTART set */ sa.sa_flags = 0; /* do not restart syscalls */ sa.sa_handler = handler; sigaction(SIGALRM, &sa, NULL); sigaction(SIGCHLD, &sa, NULL); sigaction(SIGHUP, &sa, NULL); sigaction(SIGINT, &sa, NULL); sigaction(SIGPIPE, &sa, NULL); sigaction(SIGQUIT, &sa, NULL); sigaction(SIGTERM, &sa, NULL); if (log_io) { sa.sa_flags = SA_RESTART; sa.sa_handler = sigwinch; sigaction(SIGWINCH, &sa, NULL); /* So we can block tty-generated signals */ sigemptyset(&ttyblock); sigaddset(&ttyblock, SIGINT); sigaddset(&ttyblock, SIGQUIT); sigaddset(&ttyblock, SIGTSTP); sigaddset(&ttyblock, SIGTTIN); sigaddset(&ttyblock, SIGTTOU); /* Are we the foreground process? */ foreground = tcgetpgrp(script_fds[SFD_USERTTY]) == ppgrp; /* * Setup stdin/stdout/stderr for child, to be duped after forking. */ script_fds[SFD_STDIN] = script_fds[SFD_SLAVE]; script_fds[SFD_STDOUT] = script_fds[SFD_SLAVE]; script_fds[SFD_STDERR] = script_fds[SFD_SLAVE]; /* Copy /dev/tty -> pty master */ iobufs = io_buf_new(script_fds[SFD_USERTTY], script_fds[SFD_MASTER], log_ttyin, iobufs); /* Copy pty master -> /dev/tty */ iobufs = io_buf_new(script_fds[SFD_MASTER], script_fds[SFD_USERTTY], log_ttyout, iobufs); /* * 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 (!isatty(STDIN_FILENO)) { pipeline = TRUE; if (pipe(io_pipe[STDIN_FILENO]) != 0) error(1, "unable to create pipe"); iobufs = io_buf_new(STDIN_FILENO, io_pipe[STDIN_FILENO][1], log_stdin, iobufs); script_fds[SFD_STDIN] = io_pipe[STDIN_FILENO][0]; } if (!isatty(STDOUT_FILENO)) { pipeline = TRUE; if (pipe(io_pipe[STDOUT_FILENO]) != 0) error(1, "unable to create pipe"); iobufs = io_buf_new(io_pipe[STDOUT_FILENO][0], STDOUT_FILENO, log_stdout, iobufs); script_fds[SFD_STDOUT] = io_pipe[STDOUT_FILENO][1]; } if (!isatty(STDERR_FILENO)) { if (pipe(io_pipe[STDERR_FILENO]) != 0) error(1, "unable to create pipe"); iobufs = io_buf_new(io_pipe[STDERR_FILENO][0], STDERR_FILENO, log_stderr, iobufs); script_fds[SFD_STDERR] = io_pipe[STDERR_FILENO][1]; } /* Job control signals to relay from parent to child. */ sa.sa_flags = 0; /* do not restart syscalls */ sa.sa_handler = handler; sigaction(SIGTSTP, &sa, NULL); #if 0 /* XXX - add these? */ sigaction(SIGTTIN, &sa, NULL); sigaction(SIGTTOU, &sa, NULL); #endif if (foreground) { /* Copy terminal attrs from user tty -> pty slave. */ if (term_copy(script_fds[SFD_USERTTY], script_fds[SFD_SLAVE])) { tty_initialized = 1; sync_ttysize(script_fds[SFD_USERTTY], script_fds[SFD_SLAVE]); } /* Start out in raw mode if we are not part of a pipeline. */ if (!pipeline) { ttymode = TERM_RAW; do { n = term_raw(script_fds[SFD_USERTTY], 0); } while (!n && errno == EINTR); if (!n) error(1, "Can't set terminal to raw mode"); } } } /* * Child will run the command in the pty, parent will pass data * to and from pty. */ child = fork(); switch (child) { case -1: error(1, "fork"); break; case 0: /* child */ close(sv[0]); fcntl(sv[1], F_SETFD, FD_CLOEXEC); if (exec_setup(details) == 0) { /* headed for execve() */ if (log_io) { /* Close the other end of the stdin/stdout/stderr pipes. */ 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]); script_child(details->command, argv, envp, sv[1], rbac_enabled); } else { #ifdef HAVE_SELINUX if (rbac_enabled) selinux_execve(details->command, argv, envp); else #endif my_execve(details->command, argv, envp); } } cstat->type = CMD_ERRNO; cstat->val = errno; send(sv[1], cstat, sizeof(*cstat), 0); _exit(1); } close(sv[1]); /* Set command timeout if specified. */ if (ISSET(details->flags, CD_SET_TIMEOUT)) alarm(details->timeout); /* Max fd we will be selecting on. */ maxfd = sv[0]; if (log_io) { /* 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]); for (iob = iobufs; iob; iob = iob->next) { /* Determine maxfd */ if (iob->rfd > maxfd) maxfd = iob->rfd; if (iob->wfd > maxfd) maxfd = iob->wfd; /* Set non-blocking mode. */ n = fcntl(iob->rfd, F_GETFL, 0); if (n != -1 && !ISSET(n, O_NONBLOCK)) (void) fcntl(iob->rfd, F_SETFL, n | O_NONBLOCK); n = fcntl(iob->wfd, F_GETFL, 0); if (n != -1 && !ISSET(n, O_NONBLOCK)) (void) fcntl(iob->wfd, F_SETFL, n | O_NONBLOCK); } } /* * In the event loop we pass input from user tty to master * and pass output from master to stdout and IO plugin. */ fdsr = (fd_set *)emalloc2(howmany(maxfd + 1, NFDBITS), sizeof(fd_mask)); fdsw = (fd_set *)emalloc2(howmany(maxfd + 1, NFDBITS), sizeof(fd_mask)); for (;;) { if (recvsig[SIGCHLD]) { pid_t pid; /* * If logging I/O, child is the intermediate process, * otherwise it is the command itself. */ recvsig[SIGCHLD] = FALSE; do { pid = waitpid(child, &child_status, WNOHANG); } while (pid == -1 && errno == EINTR); if (pid == child) { /* If not logging I/O and child has exited we are done. */ if (!log_io) { cstat->type = CMD_WSTATUS; cstat->val = child_status; return 0; } } } zero_bytes(fdsw, howmany(maxfd + 1, NFDBITS) * sizeof(fd_mask)); zero_bytes(fdsr, howmany(maxfd + 1, NFDBITS) * sizeof(fd_mask)); FD_SET(sv[0], fdsr); for (iob = iobufs; iob; iob = iob->next) { if (iob->rfd == -1 && iob->wfd == -1) continue; if (iob->off == iob->len) { iob->off = iob->len = 0; /* Forward the EOF from reader to writer. */ if (iob->rfd == -1) { if (iob->wfd != script_fds[SFD_USERTTY]) close(iob->wfd); iob->wfd = -1; } } /* Don't read/write /dev/tty if we are not in the foreground. */ if (iob->rfd != -1 && (ttymode == TERM_RAW || iob->rfd != script_fds[SFD_USERTTY])) { if (iob->len != sizeof(iob->buf)) FD_SET(iob->rfd, fdsr); } if (iob->wfd != -1 && (foreground || iob->wfd != script_fds[SFD_USERTTY])) { if (iob->len > iob->off) FD_SET(iob->wfd, fdsw); } } for (n = 0; n < NSIG; n++) { if (recvsig[n] && n != SIGCHLD) { if (log_io) { FD_SET(sv[0], fdsw); break; } else { /* nothing listening on sv[0], send directly */ if (n == SIGALRM) { terminate_child(child, FALSE); } else { kill(child, n); } } } } if (recvsig[SIGCHLD]) continue; nready = select(maxfd + 1, fdsr, fdsw, NULL, NULL); if (nready == -1) { if (errno == EINTR) continue; error(1, "select failed"); } if (FD_ISSET(sv[0], fdsr)) { /* read child status */ n = recv(sv[0], cstat, sizeof(*cstat), 0); if (n == -1) { if (errno == EINTR) continue; if (log_io && errno != EAGAIN) { /* Did the other end of the pipe go away? */ cstat->type = CMD_ERRNO; cstat->val = errno; } } if (cstat->type == CMD_WSTATUS) { if (WIFSTOPPED(cstat->val)) { /* Suspend parent and tell child how to resume on return. */ sudo_debug(8, "child stopped, suspending parent"); n = suspend_parent(WSTOPSIG(cstat->val), script_fds[SFD_USERTTY], iobufs); recvsig[n] = TRUE; continue; } else { /* Child exited or was killed, either way we are done. */ break; } } else if (cstat->type == CMD_ERRNO) { /* Child was unable to execute command or broken pipe. */ break; } } if (FD_ISSET(sv[0], fdsw)) { for (n = 0; n < NSIG; n++) { if (!recvsig[n]) continue; recvsig[n] = FALSE; sudo_debug(9, "sending signal %d to child over backchannel", n); cstat->type = CMD_SIGNO; cstat->val = n; do { n = send(sv[0], cstat, sizeof(*cstat), 0); } while (n == -1 && errno == EINTR); if (n != sizeof(*cstat)) { recvsig[n] = TRUE; break; } } } if (perform_io(iobufs, fdsr, fdsw) != 0) break; } if (log_io) { /* Flush any remaining output (the plugin already got it) */ n = fcntl(script_fds[SFD_USERTTY], F_GETFL, 0); if (n != -1 && ISSET(n, O_NONBLOCK)) { CLR(n, O_NONBLOCK); (void) fcntl(script_fds[SFD_USERTTY], F_SETFL, n); } flush_output(iobufs); do { n = term_restore(script_fds[SFD_USERTTY], 0); } while (!n && errno == EINTR); if (cstat->type == CMD_WSTATUS && WIFSIGNALED(cstat->val)) { int signo = WTERMSIG(cstat->val); if (signo && signo != SIGINT && signo != SIGPIPE) { char *reason = strsignal(signo); write(script_fds[SFD_USERTTY], reason, strlen(reason)); if (WCOREDUMP(cstat->val)) write(script_fds[SFD_USERTTY], " (core dumped)", 14); write(script_fds[SFD_USERTTY], "\n", 1); } } } efree(fdsr); efree(fdsw); while ((iob = iobufs) != NULL) { iobufs = iobufs->next; efree(iob); } return cstat->type == CMD_ERRNO ? -1 : 0; } static void deliver_signal(pid_t pid, int signo) { int status; /* Handle signal from parent. */ sudo_debug(8, "signal %d from parent", signo); switch (signo) { case SIGKILL: _exit(1); /* XXX */ /* NOTREACHED */ case SIGPIPE: case SIGHUP: case SIGTERM: case SIGINT: case SIGQUIT: case SIGTSTP: /* relay signal to child */ killpg(pid, signo); break; case SIGALRM: terminate_child(pid, TRUE); break; case SIGUSR1: /* foreground process, grant it controlling tty. */ do { status = tcsetpgrp(script_fds[SFD_SLAVE], pid); } while (status == -1 && errno == EINTR); killpg(pid, SIGCONT); break; case SIGUSR2: /* background process, I take controlling tty. */ do { status = tcsetpgrp(script_fds[SFD_SLAVE], getpid()); } while (status == -1 && errno == EINTR); killpg(pid, SIGCONT); break; default: warningx("unexpected signal from child: %d", signo); break; } } static int send_status(int fd, struct command_status *cstat) { int n; do { n = send(fd, cstat, sizeof(*cstat), 0); } while (n == -1 && errno == EINTR); if (n != sizeof(*cstat)) { sudo_debug(8, "unable to send status to parent: %s", strerror(errno)); } else { sudo_debug(8, "sent status to parent"); } return n; } int script_child(const char *path, char *argv[], char *envp[], int backchannel, int rbac) { struct command_status cstat; fd_set *fdsr; sigaction_t sa; pid_t pid; int errpipe[2], maxfd, n, status; int alive = TRUE; /* Close unused fds. */ close(script_fds[SFD_MASTER]); close(script_fds[SFD_USERTTY]); /* Reset signal handlers. */ zero_bytes(&sa, sizeof(sa)); sigemptyset(&sa.sa_mask); sa.sa_flags = SA_RESTART; sa.sa_handler = SIG_DFL; sigaction(SIGWINCH, &sa, NULL); sigaction(SIGALRM, &sa, NULL); /* Ignore any SIGTTIN or SIGTTOU we get. */ sa.sa_handler = SIG_IGN; sigaction(SIGTTIN, &sa, NULL); sigaction(SIGTTOU, &sa, NULL); /* Note: HP-UX select() will not be interrupted if SA_RESTART set */ sa.sa_flags = 0; sa.sa_handler = handler; sigaction(SIGCHLD, &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. */ #ifdef HAVE_SETSID if (setsid() == -1) { warning("setsid"); goto bad; } #else # ifdef TIOCNOTTY n = open(_PATH_TTY, O_RDWR|O_NOCTTY); if (n >= 0) { /* Disconnect from old controlling tty. */ if (ioctl(n, TIOCNOTTY, NULL) == -1) warning("cannot disconnect controlling tty"); close(n); } # endif setpgrp(0, 0); #endif #ifdef TIOCSCTTY if (ioctl(script_fds[SFD_SLAVE], TIOCSCTTY, NULL) != 0) error(1, "unable to set controlling tty"); #else /* Set controlling tty by reopening slave. */ if ((n = open(slavename, O_RDWR)) >= 0) close(n); #endif /* * 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 = 0; /* Start command and wait for it to stop or exit */ if (pipe(errpipe) == -1) error(1, "unable to create pipe"); child = fork(); if (child == -1) { warning("Can't fork"); goto bad; } if (child == 0) { /* Reset signal handlers. */ sa.sa_flags = SA_RESTART; sa.sa_handler = SIG_DFL; sigaction(SIGHUP, &sa, NULL); sigaction(SIGTERM, &sa, NULL); sigaction(SIGINT, &sa, NULL); sigaction(SIGQUIT, &sa, NULL); sigaction(SIGTSTP, &sa, NULL); sigaction(SIGTTIN, &sa, NULL); sigaction(SIGTTOU, &sa, NULL); sigaction(SIGUSR1, &sa, NULL); sigaction(SIGUSR2, &sa, NULL); sigaction(SIGCHLD, &sa, NULL); /* We pass errno back to our parent via pipe on exec failure. */ close(backchannel); close(errpipe[0]); fcntl(errpipe[1], F_SETFD, FD_CLOEXEC); /* setup tty and exec command */ script_run(path, argv, envp, rbac); cstat.type = CMD_ERRNO; cstat.val = errno; write(errpipe[1], &cstat, sizeof(cstat)); _exit(1); } close(errpipe[1]); /* If any of stdin/stdout/stderr are pipes, close them in parent. */ if (script_fds[SFD_STDIN] != script_fds[SFD_SLAVE]) close(script_fds[SFD_STDIN]); if (script_fds[SFD_STDOUT] != script_fds[SFD_SLAVE]) close(script_fds[SFD_STDOUT]); if (script_fds[SFD_STDERR] != script_fds[SFD_SLAVE]) close(script_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. */ setpgid(child, child); if (foreground) { do { status = tcsetpgrp(script_fds[SFD_SLAVE], child); } while (status == -1 && errno == EINTR); } /* Wait for errno on pipe, signal on backchannel or for SIGCHLD */ maxfd = MAX(errpipe[0], backchannel); fdsr = (fd_set *)emalloc2(howmany(maxfd + 1, NFDBITS), sizeof(fd_mask)); zero_bytes(fdsr, howmany(maxfd + 1, NFDBITS) * sizeof(fd_mask)); zero_bytes(&cstat, sizeof(cstat)); for (;;) { /* Read child status */ if (recvsig[SIGCHLD]) { recvsig[SIGCHLD] = FALSE; /* read child status and relay to parent */ do { pid = waitpid(child, &status, WUNTRACED|WNOHANG); } while (pid == -1 && errno == EINTR); if (pid == child) { if (WIFSTOPPED(status)) { sudo_debug(8, "command stopped, signal %d", WSTOPSIG(status)); } else { if (WIFSIGNALED(status)) sudo_debug(8, "command killed, signal %d", WTERMSIG(status)); else sudo_debug(8, "command exited: %d", WEXITSTATUS(status)); alive = FALSE; } /* Send wait status unless we previously sent errno. */ if (cstat.type != CMD_ERRNO) { cstat.type = CMD_WSTATUS; cstat.val = status; n = send_status(backchannel, &cstat); if (n == -1) goto done; } if (!alive) goto done; } } /* Check for signal on backchannel or errno on errpipe. */ FD_SET(backchannel, fdsr); if (errpipe[0] != -1) FD_SET(errpipe[0], fdsr); maxfd = MAX(errpipe[0], backchannel); if (recvsig[SIGCHLD]) continue; n = select(maxfd + 1, fdsr, NULL, NULL, NULL); if (n == -1) { if (errno == EINTR) continue; error(1, "select failed"); } if (errpipe[0] != -1 && FD_ISSET(errpipe[0], fdsr)) { /* read errno or EOF from command pipe */ n = read(errpipe[0], &cstat, sizeof(cstat)); if (n == -1) { if (errno == EINTR) continue; warning("error reading from pipe"); goto done; } if (n == sizeof(cstat)) { /* execve() failed, relay errno back to parent */ if (cstat.type == CMD_ERRNO) { n = send_status(backchannel, &cstat); if (n == -1) goto done; } else warningx("unexpected reply type on pipe: %d", cstat.type); } /* Got errno or EOF, either way we are done with errpipe. */ FD_CLR(errpipe[0], fdsr); close(errpipe[0]); errpipe[0] = -1; } if (FD_ISSET(backchannel, fdsr)) { /* read command from backchannel, should be a signal */ n = recv(backchannel, &cstat, sizeof(cstat), 0); if (n == -1) { if (errno == EINTR) continue; warning("error reading from socketpair"); goto done; } if (cstat.type != CMD_SIGNO) { warningx("unexpected reply type on backchannel: %d", cstat.type); continue; } deliver_signal(child, cstat.val); } } done: if (alive) kill(child, SIGKILL); _exit(1); bad: return errno; } /* * Flush any output buffered in iobufs or readable from the fds. * Does not read from /dev/tty. */ static void flush_output(struct io_buffer *iobufs) { struct io_buffer *iob; struct timeval tv; fd_set *fdsr, *fdsw; int nready, maxfd = -1; /* Determine maxfd */ for (iob = iobufs; iob; iob = iob->next) { if (iob->rfd > maxfd) maxfd = iob->rfd; if (iob->wfd > maxfd) maxfd = iob->wfd; } fdsr = (fd_set *)emalloc2(howmany(maxfd + 1, NFDBITS), sizeof(fd_mask)); fdsw = (fd_set *)emalloc2(howmany(maxfd + 1, NFDBITS), sizeof(fd_mask)); for (;;) { zero_bytes(fdsw, howmany(maxfd + 1, NFDBITS) * sizeof(fd_mask)); zero_bytes(fdsr, howmany(maxfd + 1, NFDBITS) * sizeof(fd_mask)); for (iob = iobufs; iob; iob = iob->next) { /* Don't read from /dev/tty while flushing. */ if (iob->rfd == script_fds[SFD_USERTTY]) continue; if (iob->rfd == -1 && iob->wfd == -1) continue; if (iob->off == iob->len) { iob->off = iob->len = 0; /* Forward the EOF from reader to writer. */ if (iob->rfd == -1) { if (iob->wfd != script_fds[SFD_USERTTY]) close(iob->wfd); iob->wfd = -1; } } if (iob->rfd != -1) { if (iob->len != sizeof(iob->buf)) FD_SET(iob->rfd, fdsr); } if (iob->wfd != -1) { if (iob->len > iob->off) FD_SET(iob->wfd, fdsw); } } /* Effect a poll (no sleeping in select) */ tv.tv_sec = 0; tv.tv_usec = 0; nready = select(maxfd + 1, fdsr, fdsw, NULL, &tv); if (nready <= 0) { if (nready == 0) break; /* all I/O flushed */ if (errno == EINTR) continue; error(1, "select failed"); } if (perform_io(iobufs, fdsr, fdsw) != 0) break; } efree(fdsr); efree(fdsw); } static void script_run(const char *path, char *argv[], char *envp[], int rbac_enabled) { pid_t self = getpid(); /* Set child process group here too to avoid a race. */ setpgid(0, self); /* Wire up standard fds, note that stdout/stderr may be pipes. */ dup2(script_fds[SFD_STDIN], STDIN_FILENO); dup2(script_fds[SFD_STDOUT], STDOUT_FILENO); dup2(script_fds[SFD_STDERR], STDERR_FILENO); /* Wait for parent to grant us the tty if we are foreground. */ if (foreground) { while (tcgetpgrp(script_fds[SFD_SLAVE]) != self) ; /* spin */ } /* We have guaranteed that the slave fd > 3 */ close(script_fds[SFD_SLAVE]); #ifdef HAVE_SELINUX if (rbac_enabled) selinux_execve(path, argv, envp); else #endif my_execve(path, argv, envp); } static void sync_ttysize(int src, int dst) { #ifdef TIOCGSIZE struct ttysize tsize; pid_t pgrp; if (ioctl(src, TIOCGSIZE, &tsize) == 0) { ioctl(dst, TIOCSSIZE, &tsize); #ifdef TIOCGPGRP if (ioctl(dst, TIOCGPGRP, &pgrp) == 0) killpg(pgrp, SIGWINCH); #endif } #endif } /* * Generic handler for signals passed from parent -> child */ static void handler(int s) { recvsig[s] = TRUE; } /* * Handler for SIGWINCH in parent */ static void sigwinch(int s) { int serrno = errno; sync_ttysize(script_fds[SFD_USERTTY], script_fds[SFD_SLAVE]); errno = serrno; }