From a258bf2648fa5e3005b96203c60b9751807bacf0 Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Wed, 16 Mar 2011 02:57:52 +0100 Subject: [PATCH] nspawn: allocate a new pty instead of passing ours through to avoid terminal settings chaos --- src/nspawn.c | 450 +++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 399 insertions(+), 51 deletions(-) diff --git a/src/nspawn.c b/src/nspawn.c index 94e03b58..f8a19009 100644 --- a/src/nspawn.c +++ b/src/nspawn.c @@ -33,12 +33,16 @@ #include #include #include +#include +#include +#include #include "log.h" #include "util.h" #include "missing.h" #include "cgroup-util.h" #include "sd-daemon.h" +#include "strv.h" static char *arg_directory = NULL; @@ -166,7 +170,7 @@ static int mount_all(const char *dest) { return r; } -static int copy_devnodes(const char *dest) { +static int copy_devnodes(const char *dest, const char *console) { static const char devnodes[] = "null\0" @@ -181,15 +185,17 @@ static int copy_devnodes(const char *dest) { const char *d; int r = 0, k; - char *tty = NULL; - dev_t tty_devnum; mode_t u; + struct stat st; + char *from = NULL, *to = NULL; + + assert(dest); + assert(console); u = umask(0000); NULSTR_FOREACH(d, devnodes) { - char *from = NULL, *to = NULL; - struct stat st; + from = to = NULL; asprintf(&from, "/dev/%s", d); asprintf(&to, "%s/dev/%s", dest, d); @@ -200,6 +206,8 @@ static int copy_devnodes(const char *dest) { free(from); free(to); + from = to = NULL; + if (r == 0) r = -ENOMEM; @@ -210,70 +218,80 @@ static int copy_devnodes(const char *dest) { if (errno != ENOENT) { log_error("Failed to stat %s: %m", from); - if (r == 0) r = -errno; } - } else { - if (mknod(to, st.st_mode, st.st_rdev) < 0) { - log_error("mknod(%s) failed: %m", dest); + } else if (!S_ISCHR(st.st_mode) && !S_ISBLK(st.st_mode)) { - if (r == 0) - r = -errno; - } + log_error("%s is not a char or block device, cannot copy.", from); + if (r == 0) + r = -EIO; + + } else if (mknod(to, st.st_mode, st.st_rdev) < 0) { + + log_error("mknod(%s) failed: %m", dest); + if (r == 0) + r = -errno; } free(from); free(to); } - if ((k = get_ctty(&tty, &tty_devnum)) < 0) { - log_error("Failed to determine controlling tty: %s", strerror(-k)); + if (stat(console, &st) < 0) { + log_error("Failed to stat %s: %m", console); if (r == 0) - r = k; - } else { - char *from = NULL, *to = NULL; + r = -errno; - asprintf(&from, "/dev/%s", tty); - asprintf(&to, "%s/dev/console", dest); + goto finish; - if (!from || !to) { - log_error("Out of memory"); + } else if (!S_ISCHR(st.st_mode)) { - if (r == 0) - r = k; - } else { - /* We need to bind mount our own tty on - * /dev/console, since ptys cannot be used - * unless on a devpts file system. But to bind - * mount it we first have to create a device - * node where we can bind mount it on. This is - * kinda ugly since the TTY will very likely - * be owned by a user/group that does not - * exist in the container. */ - - if (mknod(to, S_IFCHR|0600, tty_devnum) < 0) { - log_error("mknod for /dev/console failed: %m"); + log_error("/dev/console is not a char device."); + if (r == 0) + r = -EIO; - if (r == 0) - r = -errno; - } + goto finish; + } - if (mount(from, to, "bind", MS_BIND|MS_RDONLY, NULL) < 0) { - log_error("bind mount for /dev/console failed: %m"); + if (asprintf(&to, "%s/dev/console", dest) < 0) { - if (r == 0) - r = -errno; - } - } + log_error("Out of memory"); + if (r == 0) + r = -ENOMEM; - free(from); - free(to); + goto finish; } - free(tty); + /* We need to bind mount the right tty to /dev/console since + * ptys can only exist on pts file systems. To have something + * to bind mount things on we create a device node first, that + * has the right major/minor (note that the major minor + * doesn't actually matter here, since we mount it over + * anyway). */ + + if (mknod(to, (st.st_mode & ~07777) | 0600, st.st_rdev) < 0) + log_error("mknod for /dev/console failed: %m"); + + if (mount(console, to, "bind", MS_BIND, NULL) < 0) { + log_error("bind mount for /dev/console failed: %m"); + + if (r == 0) + r = -errno; + } + + free(to); + + if ((k = chmod_and_chown(console, 0600, 0, 0)) < 0) { + log_error("Failed to correct access mode for TTY: %s", strerror(-k)); + + if (r == 0) + r = k; + } + +finish: umask(u); @@ -346,11 +364,259 @@ static int is_os_tree(const char *path) { return r < 0 ? 0 : 1; } +#define BUFFER_SIZE 1024 + +static int process_pty(int master, sigset_t *mask) { + char in_buffer[BUFFER_SIZE], out_buffer[BUFFER_SIZE]; + size_t in_buffer_full = 0, out_buffer_full = 0; + struct epoll_event stdin_ev, stdout_ev, master_ev, signal_ev; + bool stdin_readable = false, stdout_writable = false, master_readable = false, master_writable = false; + bool stdin_rhup = false, stdout_whup = false, master_rhup = false, master_whup = false; + int ep = -1, signal_fd = -1, r; + + fd_nonblock(STDIN_FILENO, 1); + fd_nonblock(STDOUT_FILENO, 1); + fd_nonblock(master, 1); + + if ((signal_fd = signalfd(-1, mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) { + log_error("signalfd(): %m"); + r = -errno; + goto finish; + } + + if ((ep = epoll_create1(EPOLL_CLOEXEC)) < 0) { + log_error("Failed to create epoll: %m"); + r = -errno; + goto finish; + } + + zero(stdin_ev); + stdin_ev.events = EPOLLIN|EPOLLET; + stdin_ev.data.fd = STDIN_FILENO; + + zero(stdout_ev); + stdout_ev.events = EPOLLOUT|EPOLLET; + stdout_ev.data.fd = STDOUT_FILENO; + + zero(master_ev); + master_ev.events = EPOLLIN|EPOLLOUT|EPOLLET; + master_ev.data.fd = master; + + zero(signal_ev); + signal_ev.events = EPOLLIN; + signal_ev.data.fd = signal_fd; + + if (epoll_ctl(ep, EPOLL_CTL_ADD, STDIN_FILENO, &stdin_ev) < 0 || + epoll_ctl(ep, EPOLL_CTL_ADD, STDOUT_FILENO, &stdout_ev) < 0 || + epoll_ctl(ep, EPOLL_CTL_ADD, master, &master_ev) < 0 || + epoll_ctl(ep, EPOLL_CTL_ADD, signal_fd, &signal_ev) < 0) { + log_error("Failed to regiser fds in epoll: %m"); + r = -errno; + goto finish; + } + + do { + struct epoll_event ev[16]; + ssize_t k; + int i, nfds; + + if ((nfds = epoll_wait(ep, ev, ELEMENTSOF(ev), -1)) < 0) { + + if (errno == EINTR || errno == EAGAIN) + continue; + + log_error("epoll_wait(): %m"); + r = -errno; + goto finish; + } + + assert(nfds >= 1); + + for (i = 0; i < nfds; i++) { + if (ev[i].data.fd == STDIN_FILENO) { + + if (!stdin_rhup && (ev[i].events & (EPOLLHUP|EPOLLIN))) + stdin_readable = true; + + } else if (ev[i].data.fd == STDOUT_FILENO) { + + if (ev[i].events & EPOLLHUP) { + stdout_writable = false; + stdout_whup = true; + } + + if (!stdout_whup && (ev[i].events & EPOLLOUT)) + stdout_writable = true; + + } else if (ev[i].data.fd == master) { + + /* We don't connect EPOLLHUP to + * master_whup here, since EPOLLHUP + * can happen when noone has opened + * the other side */ + + if (!master_rhup && (ev[i].events & (EPOLLHUP|EPOLLIN))) + master_readable = true; + + if (!master_whup && (ev[i].events & EPOLLOUT)) + master_writable = true; + + } else if (ev[i].data.fd == signal_fd) { + struct signalfd_siginfo sfsi; + ssize_t n; + + if ((n = read(signal_fd, &sfsi, sizeof(sfsi))) != sizeof(sfsi)) { + + if (n >= 0) { + r = -EIO; + goto finish; + } + + if (errno != EINTR && errno != EAGAIN) { + r = -errno; + goto finish; + } + } else { + + if (sfsi.ssi_signo == SIGWINCH) { + struct winsize ws; + + /* The window size changed, let's forward that. */ + + if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) >= 0) + ioctl(master, TIOCSWINSZ, &ws); + } else { + r = -EINTR; + goto finish; + } + } + } + } + + while ((stdin_readable && in_buffer_full <= 0) || + (master_writable && in_buffer_full > 0) || + (master_readable && out_buffer_full <= 0) || + (stdout_writable && out_buffer_full > 0)) { + + if (stdin_readable && in_buffer_full < BUFFER_SIZE) { + + if ((k = read(STDIN_FILENO, in_buffer + in_buffer_full, BUFFER_SIZE - in_buffer_full)) < 0) { + + if (errno == EAGAIN) + stdin_readable = false; + else if (errno == EPIPE || errno == ECONNRESET || errno == EIO) + k = 0; + else { + log_error("read(): %m"); + goto finish; + } + } else + in_buffer_full += (size_t) k; + + if (k == 0) { + stdin_rhup = true; + stdin_readable = false; + shutdown(STDIN_FILENO, SHUT_RD); + } + } + + if (master_writable && in_buffer_full > 0) { + + if ((k = write(master, in_buffer, in_buffer_full)) < 0) { + + if (errno == EAGAIN) + master_writable = false; + else if (errno == EPIPE || errno == ECONNRESET || errno == EIO) { + master_whup = true; + master_writable = false; + } else { + log_error("write(): %m"); + goto finish; + } + + } else { + assert(in_buffer_full >= (size_t) k); + memmove(in_buffer, in_buffer + k, in_buffer_full - k); + in_buffer_full -= k; + } + } + + if (master_readable && out_buffer_full < BUFFER_SIZE) { + + if ((k = read(master, out_buffer + out_buffer_full, BUFFER_SIZE - out_buffer_full)) < 0) { + + if (errno == EAGAIN) + master_readable = false; + else if (errno == EPIPE || errno == ECONNRESET || errno == EIO) + k = 0; + else { + log_error("read(): %m"); + goto finish; + } + } else + out_buffer_full += (size_t) k; + + if (k == 0) { + master_rhup = true; + master_readable = false; + } + } + + if (stdout_writable && out_buffer_full > 0) { + + if ((k = write(STDOUT_FILENO, out_buffer, out_buffer_full)) < 0) { + + if (errno == EAGAIN) + stdout_writable = false; + else if (errno == EPIPE || errno == ECONNRESET || errno == EIO) { + stdout_whup = true; + stdout_writable = false; + } else { + log_error("write(): %m"); + goto finish; + } + + } else { + assert(out_buffer_full >= (size_t) k); + memmove(out_buffer, out_buffer + k, out_buffer_full - k); + out_buffer_full -= k; + } + } + } + + if (stdin_rhup && in_buffer_full <= 0 && !master_whup) { + master_whup = true; + master_writable = false; + } + + if (master_rhup && out_buffer_full <= 0 && !stdout_whup) { + stdout_whup = true; + stdout_writable = false; + shutdown(STDOUT_FILENO, SHUT_WR); + } + + } while (!stdout_whup || !master_whup); + +finish: + if (ep >= 0) + close_nointr_nofail(ep); + + if (signal_fd >= 0) + close_nointr_nofail(signal_fd); + + return r; +} int main(int argc, char *argv[]) { pid_t pid = 0; int r = EXIT_FAILURE, k; char *oldcg = NULL, *newcg = NULL; + int master = -1; + const char *console = NULL; + struct termios saved_attr, raw_attr; + sigset_t mask; + bool saved_attr_valid = false; + struct winsize ws; log_parse_environment(); log_open(); @@ -394,8 +660,6 @@ int main(int argc, char *argv[]) { goto finish; } - log_info("Spawning namespace container on %s.", arg_directory); - if ((k = cg_get_by_pid(SYSTEMD_CGROUP_CONTROLLER, 0, &oldcg)) < 0) { log_error("Failed to determine current cgroup: %s", strerror(-k)); goto finish; @@ -411,31 +675,99 @@ int main(int argc, char *argv[]) { goto finish; } + if ((master = posix_openpt(O_RDWR|O_NOCTTY|O_CLOEXEC|O_NDELAY)) < 0) { + log_error("Failed to acquire pseudo tty: %m"); + goto finish; + } + + if (!(console = ptsname(master))) { + log_error("Failed to determine tty name: %m"); + goto finish; + } + + log_info("Spawning namespace container on %s (console is %s).", arg_directory, console); + + if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) >= 0) + ioctl(master, TIOCSWINSZ, &ws); + + if (unlockpt(master) < 0) { + log_error("Failed to unlock tty: %m"); + goto finish; + } + + if (tcgetattr(STDIN_FILENO, &saved_attr) < 0) { + log_error("Failed to get terminal attributes: %m"); + goto finish; + } + + saved_attr_valid = true; + + raw_attr = saved_attr; + cfmakeraw(&raw_attr); + raw_attr.c_lflag &= ~ECHO; + + if (tcsetattr(STDIN_FILENO, TCSANOW, &raw_attr) < 0) { + log_error("Failed to set terminal attributes: %m"); + goto finish; + } + + assert_se(sigemptyset(&mask) == 0); + sigset_add_many(&mask, SIGCHLD, SIGWINCH, SIGTERM, SIGINT, -1); + assert_se(sigprocmask(SIG_BLOCK, &mask, NULL) == 0); + if ((pid = syscall(__NR_clone, SIGCHLD|CLONE_NEWIPC|CLONE_NEWNS|CLONE_NEWPID|CLONE_NEWUTS, NULL)) < 0) { log_error("clone() failed: %m"); goto finish; } if (pid == 0) { + /* child */ + const char *hn; const char *envp[] = { "HOME=/root", "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin", + NULL, NULL }; - /* child */ + envp[2] = strv_find_prefix(environ, "TERM="); + + close_nointr_nofail(master); + + close_nointr(STDIN_FILENO); + close_nointr(STDOUT_FILENO); + close_nointr(STDERR_FILENO); + + close_all_fds(NULL, 0); + + reset_all_signal_handlers(); + + assert_se(sigemptyset(&mask) == 0); + assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0); + + if (setsid() < 0) + goto child_fail; + + if (prctl(PR_SET_PDEATHSIG, SIGKILL) < 0) + goto child_fail; if (mount_all(arg_directory) < 0) goto child_fail; - if (copy_devnodes(arg_directory) < 0) + if (copy_devnodes(arg_directory, console) < 0) goto child_fail; if (chdir(arg_directory) < 0) { log_error("chdir(%s) failed: %m", arg_directory); goto child_fail; } + + if (open_terminal("dev/console", O_RDWR) != STDIN_FILENO || + dup2(STDIN_FILENO, STDOUT_FILENO) != STDOUT_FILENO || + dup2(STDIN_FILENO, STDERR_FILENO) != STDERR_FILENO) + goto child_fail; + if (mount(arg_directory, "/", "bind", MS_BIND|MS_MOVE, NULL) < 0) { log_error("mount(MS_MOVE) failed: %m"); goto child_fail; @@ -451,6 +783,8 @@ int main(int argc, char *argv[]) { goto child_fail; } + umask(0002); + if (drop_capabilities() < 0) goto child_fail; @@ -470,12 +804,26 @@ int main(int argc, char *argv[]) { _exit(EXIT_FAILURE); } + if (process_pty(master, &mask) < 0) + goto finish; + + if (saved_attr_valid) { + tcsetattr(STDIN_FILENO, TCSANOW, &saved_attr); + saved_attr_valid = false; + } + r = wait_for_terminate_and_warn(argc > optind ? argv[optind] : "bash", pid); if (r < 0) r = EXIT_FAILURE; finish: + if (saved_attr_valid) + tcsetattr(STDIN_FILENO, TCSANOW, &saved_attr); + + if (master >= 0) + close_nointr_nofail(master); + if (oldcg) cg_attach(SYSTEMD_CGROUP_CONTROLLER, oldcg, 0); -- 2.39.5