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mirror of https://github.com/systemd/systemd-stable.git synced 2024-12-22 13:33:56 +03:00

machined: move logic for bind mounting into containers from machinectl to machined

This extends the bus interface, adding BindMountMachine() for bind
mounting directories from the host into the container.
This commit is contained in:
Lennart Poettering 2015-02-17 17:19:57 +01:00
parent 0974a682d1
commit 90adaa25e8
5 changed files with 263 additions and 190 deletions

View File

@ -22,6 +22,7 @@
#include <errno.h>
#include <string.h>
#include <arpa/inet.h>
#include <sys/mount.h>
#include "bus-util.h"
#include "bus-label.h"
@ -32,6 +33,7 @@
#include "in-addr-util.h"
#include "local-addresses.h"
#include "path-util.h"
#include "mkdir.h"
#include "bus-internal.h"
#include "machine.h"
#include "machine-dbus.h"
@ -518,6 +520,211 @@ int bus_machine_method_open_login(sd_bus *bus, sd_bus_message *message, void *us
return sd_bus_send(bus, reply, NULL);
}
int bus_machine_method_bind_mount(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error) {
_cleanup_close_pair_ int errno_pipe_fd[2] = { -1, -1 };
char mount_slave[] = "/tmp/propagate.XXXXXX", *mount_tmp, *mount_outside, *p;
bool mount_slave_created = false, mount_slave_mounted = false,
mount_tmp_created = false, mount_tmp_mounted = false,
mount_outside_created = false, mount_outside_mounted = false;
const char *dest, *src;
Machine *m = userdata;
int read_only, make_directory;
pid_t child;
siginfo_t si;
int r;
if (m->class != MACHINE_CONTAINER)
return sd_bus_error_setf(error, SD_BUS_ERROR_NOT_SUPPORTED, "Bind mounting is only supported on container machines.");
r = sd_bus_message_read(message, "ssbb", &src, &dest, &read_only, &make_directory);
if (r < 0)
return r;
if (!path_is_absolute(src) || !path_is_safe(src))
return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Source path must be absolute and not contain ../.");
if (isempty(dest))
dest = src;
else if (!path_is_absolute(dest) || !path_is_safe(dest))
return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Source path must be absolute and not contain ../.");
/* One day, when bind mounting /proc/self/fd/n works across
* namespace boundaries we should rework this logic to make
* use of it... */
p = strjoina("/run/systemd/nspawn/propagate/", m->name, "/");
if (laccess(p, F_OK) < 0)
return sd_bus_error_setf(error, SD_BUS_ERROR_NOT_SUPPORTED, "Container does not allow propagation of mount points.");
/* Our goal is to install a new bind mount into the container,
possibly read-only. This is irritatingly complex
unfortunately, currently.
First, we start by creating a private playground in /tmp,
that we can mount MS_SLAVE. (Which is necessary, since
MS_MOUNT cannot be applied to mounts with MS_SHARED parent
mounts.) */
if (!mkdtemp(mount_slave))
return sd_bus_error_set_errnof(error, errno, "Failed to create playground %s: %m", mount_slave);
mount_slave_created = true;
if (mount(mount_slave, mount_slave, NULL, MS_BIND, NULL) < 0) {
r = sd_bus_error_set_errnof(error, errno, "Failed to make bind mount %s: %m", mount_slave);
goto finish;
}
mount_slave_mounted = true;
if (mount(NULL, mount_slave, NULL, MS_SLAVE, NULL) < 0) {
r = sd_bus_error_set_errnof(error, errno, "Failed to remount slave %s: %m", mount_slave);
goto finish;
}
/* Second, we mount the source directory to a directory inside
of our MS_SLAVE playground. */
mount_tmp = strjoina(mount_slave, "/mount");
if (mkdir(mount_tmp, 0700) < 0) {
r = sd_bus_error_set_errnof(error, errno, "Failed to create temporary mount point %s: %m", mount_tmp);
goto finish;
}
mount_tmp_created = true;
if (mount(src, mount_tmp, NULL, MS_BIND, NULL) < 0) {
r = sd_bus_error_set_errnof(error, errno, "Failed to overmount %s: %m", mount_tmp);
goto finish;
}
mount_tmp_mounted = true;
/* Third, we remount the new bind mount read-only if requested. */
if (read_only)
if (mount(NULL, mount_tmp, NULL, MS_BIND|MS_REMOUNT|MS_RDONLY, NULL) < 0) {
r = sd_bus_error_set_errnof(error, errno, "Failed to remount read-only %s: %m", mount_tmp);
goto finish;
}
/* Fourth, we move the new bind mount into the propagation
* directory. This way it will appear there read-only
* right-away. */
mount_outside = strjoina("/run/systemd/nspawn/propagate/", m->name, "/XXXXXX");
if (!mkdtemp(mount_outside)) {
r = sd_bus_error_set_errnof(error, errno, "Cannot create propagation directory %s: %m", mount_outside);
goto finish;
}
mount_outside_created = true;
if (mount(mount_tmp, mount_outside, NULL, MS_MOVE, NULL) < 0) {
r = sd_bus_error_set_errnof(error, errno, "Failed to move %s to %s: %m", mount_tmp, mount_outside);
goto finish;
}
mount_outside_mounted = true;
mount_tmp_mounted = false;
(void) rmdir(mount_tmp);
mount_tmp_created = false;
(void) umount(mount_slave);
mount_slave_mounted = false;
(void) rmdir(mount_slave);
mount_slave_created = false;
if (pipe2(errno_pipe_fd, O_CLOEXEC|O_NONBLOCK) < 0) {
r = sd_bus_error_set_errnof(error, errno, "Failed to create pipe: %m");
goto finish;
}
child = fork();
if (child < 0) {
r = sd_bus_error_set_errnof(error, errno, "Failed to fork(): %m");
goto finish;
}
if (child == 0) {
const char *mount_inside;
int mntfd;
const char *q;
errno_pipe_fd[0] = safe_close(errno_pipe_fd[0]);
q = procfs_file_alloca(m->leader, "ns/mnt");
mntfd = open(q, O_RDONLY|O_NOCTTY|O_CLOEXEC);
if (mntfd < 0) {
r = log_error_errno(errno, "Failed to open mount namespace of leader: %m");
goto child_fail;
}
if (setns(mntfd, CLONE_NEWNS) < 0) {
r = log_error_errno(errno, "Failed to join namespace of leader: %m");
goto child_fail;
}
if (make_directory)
(void) mkdir_p(dest, 0755);
/* Fifth, move the mount to the right place inside */
mount_inside = strjoina("/run/systemd/nspawn/incoming/", basename(mount_outside));
if (mount(mount_inside, dest, NULL, MS_MOVE, NULL) < 0) {
r = log_error_errno(errno, "Failed to mount: %m");
goto child_fail;
}
_exit(EXIT_SUCCESS);
child_fail:
(void) write(errno_pipe_fd[1], &r, sizeof(r));
errno_pipe_fd[1] = safe_close(errno_pipe_fd[1]);
_exit(EXIT_FAILURE);
}
errno_pipe_fd[1] = safe_close(errno_pipe_fd[1]);
r = wait_for_terminate(child, &si);
if (r < 0) {
r = sd_bus_error_set_errnof(error, errno, "Failed to wait for client: %m");
goto finish;
}
if (si.si_code != CLD_EXITED) {
r = sd_bus_error_setf(error, SD_BUS_ERROR_FAILED, "Client died abnormally.");
goto finish;
}
if (si.si_status != EXIT_SUCCESS) {
if (read(errno_pipe_fd[0], &r, sizeof(r)) == sizeof(r))
r = sd_bus_error_set_errnof(error, r, "Failed to mount in container: %m");
else
r = sd_bus_error_setf(error, SD_BUS_ERROR_FAILED, "Client failed.");
goto finish;
}
r = sd_bus_reply_method_return(message, NULL);
finish:
if (mount_outside_mounted)
umount(mount_outside);
if (mount_outside_created)
rmdir(mount_outside);
if (mount_tmp_mounted)
umount(mount_tmp);
if (mount_tmp_created)
rmdir(mount_tmp);
if (mount_slave_mounted)
umount(mount_slave);
if (mount_slave_created)
rmdir(mount_slave);
return r;
}
const sd_bus_vtable machine_vtable[] = {
SD_BUS_VTABLE_START(0),
SD_BUS_PROPERTY("Name", "s", NULL, offsetof(Machine, name), SD_BUS_VTABLE_PROPERTY_CONST),
@ -537,6 +744,7 @@ const sd_bus_vtable machine_vtable[] = {
SD_BUS_METHOD("GetOSRelease", NULL, "a{ss}", bus_machine_method_get_os_release, SD_BUS_VTABLE_UNPRIVILEGED),
SD_BUS_METHOD("OpenPTY", NULL, "hs", bus_machine_method_open_pty, 0),
SD_BUS_METHOD("OpenLogin", NULL, "hs", bus_machine_method_open_login, SD_BUS_VTABLE_UNPRIVILEGED),
SD_BUS_METHOD("BindMount", "ssbb", NULL, bus_machine_method_bind_mount, 0),
SD_BUS_VTABLE_END
};

View File

@ -36,6 +36,7 @@ int bus_machine_method_get_addresses(sd_bus *bus, sd_bus_message *message, void
int bus_machine_method_get_os_release(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error);
int bus_machine_method_open_pty(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error);
int bus_machine_method_open_login(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error);
int bus_machine_method_bind_mount(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error);
int machine_send_signal(Machine *m, bool new_machine);
int machine_send_create_reply(Machine *m, sd_bus_error *error);

View File

@ -901,14 +901,14 @@ static int show_image(int argc, char *argv[], void *userdata) {
const char *path = NULL;
r = sd_bus_call_method(
bus,
"org.freedesktop.machine1",
"/org/freedesktop/machine1",
"org.freedesktop.machine1.Manager",
"GetImage",
&error,
&reply,
"s", argv[i]);
bus,
"org.freedesktop.machine1",
"/org/freedesktop/machine1",
"org.freedesktop.machine1.Manager",
"GetImage",
&error,
&reply,
"s", argv[i]);
if (r < 0) {
log_error("Could not get path to image: %s", bus_error_message(&error, -r));
return r;
@ -930,7 +930,7 @@ static int show_image(int argc, char *argv[], void *userdata) {
static int kill_machine(int argc, char *argv[], void *userdata) {
_cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
sd_bus *bus = userdata;
int i;
int r, i;
assert(bus);
@ -940,8 +940,6 @@ static int kill_machine(int argc, char *argv[], void *userdata) {
arg_kill_who = "all";
for (i = 1; i < argc; i++) {
int r;
r = sd_bus_call_method(
bus,
"org.freedesktop.machine1",
@ -1143,187 +1141,32 @@ static int copy_files(int argc, char *argv[], void *userdata) {
}
static int bind_mount(int argc, char *argv[], void *userdata) {
char mount_slave[] = "/tmp/propagate.XXXXXX", *mount_tmp, *mount_outside, *p;
_cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
sd_bus *bus = userdata;
pid_t child, leader;
const char *dest;
siginfo_t si;
bool mount_slave_created = false, mount_slave_mounted = false,
mount_tmp_created = false, mount_tmp_mounted = false,
mount_outside_created = false, mount_outside_mounted = false;
int r;
assert(bus);
/* One day, when bind mounting /proc/self/fd/n works across
* namespace boundaries we should rework this logic to make
* use of it... */
dest = argv[3] ?: argv[2];
if (!path_is_absolute(dest)) {
log_error("Destination path not absolute.");
return -EINVAL;
}
p = strjoina("/run/systemd/nspawn/propagate/", argv[1], "/");
if (access(p, F_OK) < 0) {
log_error("Container does not allow propagation of mount points.");
return -ENOTSUP;
}
r = machine_get_leader(bus, argv[1], &leader);
if (r < 0)
return r;
/* Our goal is to install a new bind mount into the container,
possibly read-only. This is irritatingly complex
unfortunately, currently.
First, we start by creating a private playground in /tmp,
that we can mount MS_SLAVE. (Which is necessary, since
MS_MOUNT cannot be applied to mounts with MS_SHARED parent
mounts.) */
if (!mkdtemp(mount_slave))
return log_error_errno(errno, "Failed to create playground: %m");
mount_slave_created = true;
if (mount(mount_slave, mount_slave, NULL, MS_BIND, NULL) < 0) {
r = log_error_errno(errno, "Failed to make bind mount: %m");
goto finish;
}
mount_slave_mounted = true;
if (mount(NULL, mount_slave, NULL, MS_SLAVE, NULL) < 0) {
r = log_error_errno(errno, "Failed to remount slave: %m");
goto finish;
}
/* Second, we mount the source directory to a directory inside
of our MS_SLAVE playground. */
mount_tmp = strjoina(mount_slave, "/mount");
if (mkdir(mount_tmp, 0700) < 0) {
r = log_error_errno(errno, "Failed to create temporary mount: %m");
goto finish;
}
mount_tmp_created = true;
if (mount(argv[2], mount_tmp, NULL, MS_BIND, NULL) < 0) {
r = log_error_errno(errno, "Failed to overmount: %m");
goto finish;
}
mount_tmp_mounted = true;
/* Third, we remount the new bind mount read-only if requested. */
if (arg_read_only)
if (mount(NULL, mount_tmp, NULL, MS_BIND|MS_REMOUNT|MS_RDONLY, NULL) < 0) {
r = log_error_errno(errno, "Failed to mark read-only: %m");
goto finish;
}
/* Fourth, we move the new bind mount into the propagation
* directory. This way it will appear there read-only
* right-away. */
mount_outside = strjoina("/run/systemd/nspawn/propagate/", argv[1], "/XXXXXX");
if (!mkdtemp(mount_outside)) {
r = log_error_errno(errno, "Cannot create propagation directory: %m");
goto finish;
}
mount_outside_created = true;
if (mount(mount_tmp, mount_outside, NULL, MS_MOVE, NULL) < 0) {
r = log_error_errno(errno, "Failed to move: %m");
goto finish;
}
mount_outside_mounted = true;
mount_tmp_mounted = false;
(void) rmdir(mount_tmp);
mount_tmp_created = false;
(void) umount(mount_slave);
mount_slave_mounted = false;
(void) rmdir(mount_slave);
mount_slave_created = false;
child = fork();
if (child < 0) {
r = log_error_errno(errno, "Failed to fork(): %m");
goto finish;
}
if (child == 0) {
const char *mount_inside;
int mntfd;
const char *q;
q = procfs_file_alloca(leader, "ns/mnt");
mntfd = open(q, O_RDONLY|O_NOCTTY|O_CLOEXEC);
if (mntfd < 0) {
log_error_errno(errno, "Failed to open mount namespace of leader: %m");
_exit(EXIT_FAILURE);
}
if (setns(mntfd, CLONE_NEWNS) < 0) {
log_error_errno(errno, "Failed to join namespace of leader: %m");
_exit(EXIT_FAILURE);
}
if (arg_mkdir)
mkdir_p(dest, 0755);
/* Fifth, move the mount to the right place inside */
mount_inside = strjoina("/run/systemd/nspawn/incoming/", basename(mount_outside));
if (mount(mount_inside, dest, NULL, MS_MOVE, NULL) < 0) {
log_error_errno(errno, "Failed to mount: %m");
_exit(EXIT_FAILURE);
}
_exit(EXIT_SUCCESS);
}
r = wait_for_terminate(child, &si);
r = sd_bus_call_method(
bus,
"org.freedesktop.machine1",
"/org/freedesktop/machine1",
"org.freedesktop.machine1.Manager",
"BindMountMachine",
&error,
NULL,
"sssbb",
argv[1],
argv[2],
argv[3],
arg_read_only,
arg_mkdir);
if (r < 0) {
log_error_errno(r, "Failed to wait for client: %m");
goto finish;
}
if (si.si_code != CLD_EXITED) {
log_error("Client died abnormally.");
r = -EIO;
goto finish;
}
if (si.si_status != EXIT_SUCCESS) {
r = -EIO;
goto finish;
log_error("Failed to bind mount: %s", bus_error_message(&error, -r));
return r;
}
r = 0;
finish:
if (mount_outside_mounted)
umount(mount_outside);
if (mount_outside_created)
rmdir(mount_outside);
if (mount_tmp_mounted)
umount(mount_tmp);
if (mount_tmp_created)
umount(mount_tmp);
if (mount_slave_mounted)
umount(mount_slave);
if (mount_slave_created)
umount(mount_slave);
return r;
return 0;
}
static int on_machine_removed(sd_bus *bus, sd_bus_message *m, void *userdata, sd_bus_error *ret_error) {

View File

@ -559,6 +559,27 @@ static int method_open_machine_login(sd_bus *bus, sd_bus_message *message, void
return bus_machine_method_open_login(bus, message, machine, error);
}
static int method_bind_mount_machine(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error) {
Manager *m = userdata;
Machine *machine;
const char *name;
int r;
assert(bus);
assert(message);
assert(m);
r = sd_bus_message_read(message, "s", &name);
if (r < 0)
return r;
machine = hashmap_get(m->machines, name);
if (!machine)
return sd_bus_error_setf(error, BUS_ERROR_NO_SUCH_MACHINE, "No machine '%s' known", name);
return bus_machine_method_bind_mount(bus, message, machine, error);
}
static int method_remove_image(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error) {
_cleanup_(image_unrefp) Image* i = NULL;
const char *name;
@ -672,6 +693,7 @@ const sd_bus_vtable manager_vtable[] = {
SD_BUS_METHOD("RenameImage", "ss", NULL, method_rename_image, 0),
SD_BUS_METHOD("CloneImage", "ssb", NULL, method_clone_image, 0),
SD_BUS_METHOD("MarkImageReadOnly", "sb", NULL, method_mark_image_read_only, 0),
SD_BUS_METHOD("BindMountMachine", "sssbb", NULL, method_bind_mount_machine, 0),
SD_BUS_SIGNAL("MachineNew", "so", 0),
SD_BUS_SIGNAL("MachineRemoved", "so", 0),
SD_BUS_VTABLE_END

View File

@ -15,10 +15,9 @@ After=machine.slice
[Service]
ExecStart=@rootlibexecdir@/systemd-machined
BusName=org.freedesktop.machine1
CapabilityBoundingSet=CAP_KILL CAP_SYS_PTRACE CAP_SYS_ADMIN CAP_SETGID CAP_SYS_CHROOT CAP_DAC_READ_SEARCH
CapabilityBoundingSet=CAP_KILL CAP_SYS_PTRACE CAP_SYS_ADMIN CAP_SETGID CAP_SYS_CHROOT CAP_DAC_READ_SEARCH CAP_DAC_OVERRIDE
WatchdogSec=1min
PrivateTmp=yes
PrivateDevices=yes
PrivateNetwork=yes
ProtectSystem=full
ProtectHome=yes
# Note that machined cannot be placed in a mount namespace, since it
# needs access to the host's mount namespace in order to implement the
# "machinectl bind" operation.