nspawn: allocate a new pty instead of passing ours through to avoid terminal settings chaos
This commit is contained in:
Lennart Poettering
parent
6ef1b05339
commit
a258bf2648
462
src/nspawn.c
462
src/nspawn.c
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@ -33,12 +33,16 @@
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#include <sys/prctl.h>
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#include <sys/capability.h>
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#include <getopt.h>
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#include <sys/epoll.h>
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#include <termios.h>
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#include <sys/signalfd.h>
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#include "log.h"
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#include "util.h"
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#include "missing.h"
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#include "cgroup-util.h"
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#include "sd-daemon.h"
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#include "strv.h"
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static char *arg_directory = NULL;
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@ -166,7 +170,7 @@ static int mount_all(const char *dest) {
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return r;
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}
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static int copy_devnodes(const char *dest) {
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static int copy_devnodes(const char *dest, const char *console) {
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static const char devnodes[] =
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"null\0"
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@ -181,15 +185,17 @@ static int copy_devnodes(const char *dest) {
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const char *d;
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int r = 0, k;
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char *tty = NULL;
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dev_t tty_devnum;
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mode_t u;
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struct stat st;
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char *from = NULL, *to = NULL;
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assert(dest);
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assert(console);
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u = umask(0000);
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NULSTR_FOREACH(d, devnodes) {
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char *from = NULL, *to = NULL;
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struct stat st;
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from = to = NULL;
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asprintf(&from, "/dev/%s", d);
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asprintf(&to, "%s/dev/%s", dest, d);
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@ -200,6 +206,8 @@ static int copy_devnodes(const char *dest) {
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free(from);
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free(to);
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from = to = NULL;
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if (r == 0)
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r = -ENOMEM;
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@ -210,70 +218,80 @@ static int copy_devnodes(const char *dest) {
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if (errno != ENOENT) {
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log_error("Failed to stat %s: %m", from);
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if (r == 0)
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r = -errno;
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}
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} else {
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if (mknod(to, st.st_mode, st.st_rdev) < 0) {
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log_error("mknod(%s) failed: %m", dest);
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} else if (!S_ISCHR(st.st_mode) && !S_ISBLK(st.st_mode)) {
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if (r == 0)
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r = -errno;
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}
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log_error("%s is not a char or block device, cannot copy.", from);
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if (r == 0)
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r = -EIO;
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} else if (mknod(to, st.st_mode, st.st_rdev) < 0) {
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log_error("mknod(%s) failed: %m", dest);
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if (r == 0)
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r = -errno;
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}
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free(from);
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free(to);
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}
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if ((k = get_ctty(&tty, &tty_devnum)) < 0) {
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log_error("Failed to determine controlling tty: %s", strerror(-k));
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if (stat(console, &st) < 0) {
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log_error("Failed to stat %s: %m", console);
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if (r == 0)
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r = -errno;
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goto finish;
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} else if (!S_ISCHR(st.st_mode)) {
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log_error("/dev/console is not a char device.");
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if (r == 0)
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r = -EIO;
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goto finish;
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}
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if (asprintf(&to, "%s/dev/console", dest) < 0) {
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log_error("Out of memory");
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if (r == 0)
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r = -ENOMEM;
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goto finish;
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}
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/* We need to bind mount the right tty to /dev/console since
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* ptys can only exist on pts file systems. To have something
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* to bind mount things on we create a device node first, that
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* has the right major/minor (note that the major minor
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* doesn't actually matter here, since we mount it over
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* anyway). */
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if (mknod(to, (st.st_mode & ~07777) | 0600, st.st_rdev) < 0)
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log_error("mknod for /dev/console failed: %m");
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if (mount(console, to, "bind", MS_BIND, NULL) < 0) {
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log_error("bind mount for /dev/console failed: %m");
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if (r == 0)
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r = -errno;
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}
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free(to);
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if ((k = chmod_and_chown(console, 0600, 0, 0)) < 0) {
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log_error("Failed to correct access mode for TTY: %s", strerror(-k));
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if (r == 0)
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r = k;
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} else {
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char *from = NULL, *to = NULL;
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asprintf(&from, "/dev/%s", tty);
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asprintf(&to, "%s/dev/console", dest);
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if (!from || !to) {
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log_error("Out of memory");
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if (r == 0)
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r = k;
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} else {
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/* We need to bind mount our own tty on
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* /dev/console, since ptys cannot be used
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* unless on a devpts file system. But to bind
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* mount it we first have to create a device
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* node where we can bind mount it on. This is
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* kinda ugly since the TTY will very likely
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* be owned by a user/group that does not
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* exist in the container. */
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if (mknod(to, S_IFCHR|0600, tty_devnum) < 0) {
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log_error("mknod for /dev/console failed: %m");
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if (r == 0)
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r = -errno;
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}
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if (mount(from, to, "bind", MS_BIND|MS_RDONLY, NULL) < 0) {
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log_error("bind mount for /dev/console failed: %m");
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if (r == 0)
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r = -errno;
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}
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}
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free(from);
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free(to);
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}
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free(tty);
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finish:
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umask(u);
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@ -346,11 +364,259 @@ static int is_os_tree(const char *path) {
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return r < 0 ? 0 : 1;
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}
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#define BUFFER_SIZE 1024
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static int process_pty(int master, sigset_t *mask) {
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char in_buffer[BUFFER_SIZE], out_buffer[BUFFER_SIZE];
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size_t in_buffer_full = 0, out_buffer_full = 0;
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struct epoll_event stdin_ev, stdout_ev, master_ev, signal_ev;
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bool stdin_readable = false, stdout_writable = false, master_readable = false, master_writable = false;
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bool stdin_rhup = false, stdout_whup = false, master_rhup = false, master_whup = false;
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int ep = -1, signal_fd = -1, r;
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fd_nonblock(STDIN_FILENO, 1);
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fd_nonblock(STDOUT_FILENO, 1);
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fd_nonblock(master, 1);
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if ((signal_fd = signalfd(-1, mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) {
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log_error("signalfd(): %m");
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r = -errno;
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goto finish;
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}
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if ((ep = epoll_create1(EPOLL_CLOEXEC)) < 0) {
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log_error("Failed to create epoll: %m");
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r = -errno;
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goto finish;
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}
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zero(stdin_ev);
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stdin_ev.events = EPOLLIN|EPOLLET;
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stdin_ev.data.fd = STDIN_FILENO;
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zero(stdout_ev);
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stdout_ev.events = EPOLLOUT|EPOLLET;
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stdout_ev.data.fd = STDOUT_FILENO;
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zero(master_ev);
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master_ev.events = EPOLLIN|EPOLLOUT|EPOLLET;
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master_ev.data.fd = master;
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zero(signal_ev);
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signal_ev.events = EPOLLIN;
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signal_ev.data.fd = signal_fd;
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if (epoll_ctl(ep, EPOLL_CTL_ADD, STDIN_FILENO, &stdin_ev) < 0 ||
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epoll_ctl(ep, EPOLL_CTL_ADD, STDOUT_FILENO, &stdout_ev) < 0 ||
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epoll_ctl(ep, EPOLL_CTL_ADD, master, &master_ev) < 0 ||
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epoll_ctl(ep, EPOLL_CTL_ADD, signal_fd, &signal_ev) < 0) {
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log_error("Failed to regiser fds in epoll: %m");
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r = -errno;
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goto finish;
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}
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do {
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struct epoll_event ev[16];
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ssize_t k;
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int i, nfds;
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if ((nfds = epoll_wait(ep, ev, ELEMENTSOF(ev), -1)) < 0) {
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if (errno == EINTR || errno == EAGAIN)
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continue;
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log_error("epoll_wait(): %m");
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r = -errno;
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goto finish;
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}
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assert(nfds >= 1);
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for (i = 0; i < nfds; i++) {
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if (ev[i].data.fd == STDIN_FILENO) {
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if (!stdin_rhup && (ev[i].events & (EPOLLHUP|EPOLLIN)))
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stdin_readable = true;
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} else if (ev[i].data.fd == STDOUT_FILENO) {
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if (ev[i].events & EPOLLHUP) {
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stdout_writable = false;
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stdout_whup = true;
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}
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if (!stdout_whup && (ev[i].events & EPOLLOUT))
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stdout_writable = true;
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} else if (ev[i].data.fd == master) {
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/* We don't connect EPOLLHUP to
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* master_whup here, since EPOLLHUP
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* can happen when noone has opened
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* the other side */
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if (!master_rhup && (ev[i].events & (EPOLLHUP|EPOLLIN)))
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master_readable = true;
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if (!master_whup && (ev[i].events & EPOLLOUT))
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master_writable = true;
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} else if (ev[i].data.fd == signal_fd) {
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struct signalfd_siginfo sfsi;
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ssize_t n;
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if ((n = read(signal_fd, &sfsi, sizeof(sfsi))) != sizeof(sfsi)) {
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if (n >= 0) {
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r = -EIO;
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goto finish;
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}
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if (errno != EINTR && errno != EAGAIN) {
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r = -errno;
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goto finish;
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}
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} else {
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if (sfsi.ssi_signo == SIGWINCH) {
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struct winsize ws;
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/* The window size changed, let's forward that. */
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if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) >= 0)
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ioctl(master, TIOCSWINSZ, &ws);
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} else {
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r = -EINTR;
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goto finish;
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}
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}
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}
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}
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while ((stdin_readable && in_buffer_full <= 0) ||
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(master_writable && in_buffer_full > 0) ||
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(master_readable && out_buffer_full <= 0) ||
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(stdout_writable && out_buffer_full > 0)) {
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if (stdin_readable && in_buffer_full < BUFFER_SIZE) {
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if ((k = read(STDIN_FILENO, in_buffer + in_buffer_full, BUFFER_SIZE - in_buffer_full)) < 0) {
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if (errno == EAGAIN)
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stdin_readable = false;
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else if (errno == EPIPE || errno == ECONNRESET || errno == EIO)
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k = 0;
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else {
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log_error("read(): %m");
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goto finish;
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}
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} else
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in_buffer_full += (size_t) k;
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if (k == 0) {
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stdin_rhup = true;
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stdin_readable = false;
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shutdown(STDIN_FILENO, SHUT_RD);
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}
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}
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if (master_writable && in_buffer_full > 0) {
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if ((k = write(master, in_buffer, in_buffer_full)) < 0) {
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if (errno == EAGAIN)
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master_writable = false;
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else if (errno == EPIPE || errno == ECONNRESET || errno == EIO) {
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master_whup = true;
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master_writable = false;
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} else {
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log_error("write(): %m");
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goto finish;
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}
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} else {
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assert(in_buffer_full >= (size_t) k);
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memmove(in_buffer, in_buffer + k, in_buffer_full - k);
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in_buffer_full -= k;
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}
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}
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if (master_readable && out_buffer_full < BUFFER_SIZE) {
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if ((k = read(master, out_buffer + out_buffer_full, BUFFER_SIZE - out_buffer_full)) < 0) {
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if (errno == EAGAIN)
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master_readable = false;
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else if (errno == EPIPE || errno == ECONNRESET || errno == EIO)
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k = 0;
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else {
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log_error("read(): %m");
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goto finish;
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}
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} else
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out_buffer_full += (size_t) k;
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if (k == 0) {
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master_rhup = true;
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master_readable = false;
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}
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}
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if (stdout_writable && out_buffer_full > 0) {
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if ((k = write(STDOUT_FILENO, out_buffer, out_buffer_full)) < 0) {
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if (errno == EAGAIN)
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stdout_writable = false;
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else if (errno == EPIPE || errno == ECONNRESET || errno == EIO) {
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stdout_whup = true;
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stdout_writable = false;
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} else {
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log_error("write(): %m");
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goto finish;
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}
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} else {
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assert(out_buffer_full >= (size_t) k);
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memmove(out_buffer, out_buffer + k, out_buffer_full - k);
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out_buffer_full -= k;
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}
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}
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}
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if (stdin_rhup && in_buffer_full <= 0 && !master_whup) {
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master_whup = true;
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master_writable = false;
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}
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if (master_rhup && out_buffer_full <= 0 && !stdout_whup) {
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stdout_whup = true;
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stdout_writable = false;
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shutdown(STDOUT_FILENO, SHUT_WR);
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}
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} while (!stdout_whup || !master_whup);
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finish:
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if (ep >= 0)
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close_nointr_nofail(ep);
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if (signal_fd >= 0)
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close_nointr_nofail(signal_fd);
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return r;
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}
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int main(int argc, char *argv[]) {
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pid_t pid = 0;
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int r = EXIT_FAILURE, k;
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char *oldcg = NULL, *newcg = NULL;
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int master = -1;
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const char *console = NULL;
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struct termios saved_attr, raw_attr;
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sigset_t mask;
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bool saved_attr_valid = false;
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struct winsize ws;
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log_parse_environment();
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log_open();
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@ -394,8 +660,6 @@ int main(int argc, char *argv[]) {
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goto finish;
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}
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log_info("Spawning namespace container on %s.", arg_directory);
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if ((k = cg_get_by_pid(SYSTEMD_CGROUP_CONTROLLER, 0, &oldcg)) < 0) {
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log_error("Failed to determine current cgroup: %s", strerror(-k));
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goto finish;
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@ -411,31 +675,99 @@ int main(int argc, char *argv[]) {
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goto finish;
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}
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if ((master = posix_openpt(O_RDWR|O_NOCTTY|O_CLOEXEC|O_NDELAY)) < 0) {
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log_error("Failed to acquire pseudo tty: %m");
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goto finish;
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}
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if (!(console = ptsname(master))) {
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log_error("Failed to determine tty name: %m");
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goto finish;
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}
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log_info("Spawning namespace container on %s (console is %s).", arg_directory, console);
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if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) >= 0)
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ioctl(master, TIOCSWINSZ, &ws);
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if (unlockpt(master) < 0) {
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log_error("Failed to unlock tty: %m");
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goto finish;
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}
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if (tcgetattr(STDIN_FILENO, &saved_attr) < 0) {
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log_error("Failed to get terminal attributes: %m");
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goto finish;
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}
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saved_attr_valid = true;
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raw_attr = saved_attr;
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cfmakeraw(&raw_attr);
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raw_attr.c_lflag &= ~ECHO;
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if (tcsetattr(STDIN_FILENO, TCSANOW, &raw_attr) < 0) {
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log_error("Failed to set terminal attributes: %m");
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goto finish;
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}
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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);
|
||||
|
||||
|
|
|
|||
Loading…
Reference in a new issue