diff options
Diffstat (limited to 'src/machine/machine-dbus.c')
| -rw-r--r-- | src/machine/machine-dbus.c | 208 |
1 files changed, 208 insertions, 0 deletions
diff --git a/src/machine/machine-dbus.c b/src/machine/machine-dbus.c index b46f0a8dac..246c2cfd05 100644 --- a/src/machine/machine-dbus.c +++ b/src/machine/machine-dbus.c @@ -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 }; |