Commit a258bf26 authored by Lennart Poettering's avatar Lennart Poettering
Browse files

nspawn: allocate a new pty instead of passing ours through to avoid terminal settings chaos

parent 6ef1b053
......@@ -33,12 +33,16 @@
#include <sys/prctl.h>
#include <sys/capability.h>
#include <getopt.h>
#include <sys/epoll.h>
#include <termios.h>
#include <sys/signalfd.h>
#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);
......
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