conf: merge devpts setup and move before pivot root

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

diff --git a/src/lxc/conf.c b/src/lxc/conf.c
index f8402b56124f10b42be3867067a1bd08a18e3b61..39bcdb1ee6394c8ba1936036af97c13289b600be 100644 (file)
--- a/src/lxc/conf.c
+++ b/src/lxc/conf.c
@@ -1663,9 +1663,9 @@ static int lxc_recv_devpts_from_child(struct lxc_handler *handler)
        return 0;
 }
 
-static int lxc_prepare_devpts_child(struct lxc_handler *handler)
+static int lxc_setup_devpts_child(struct lxc_handler *handler)
 {
-       __do_close int fd_fs = -EBADF, fd_fsmnt = -EBADF;
+       __do_close int devpts_fd = -EBADF, fd_fs = -EBADF;
        struct lxc_conf *conf = handler->conf;
        struct lxc_rootfs *rootfs = &conf->rootfs;
        int ret;
@@ -1685,70 +1685,54 @@ static int lxc_prepare_devpts_child(struct lxc_handler *handler)
        if (ret < 0 && errno != EEXIST)
                return log_error_errno(-1, errno, "Failed to create \"/dev/pts\" directory");
 
-       if (!can_use_mount_api())
-               return 0;
-
-       fd_fs = fs_prepare("devpts", -EBADF, "", 0, 0);
-       if (fd_fs < 0)
-               return syserror("Failed to prepare filesystem context for devpts");
-
-       ret = fs_set_property(fd_fs, "source", "devpts");
-       if (ret < 0)
-               SYSTRACE("Failed to set \"source=devpts\" on devpts filesystem context %d", fd_fs);
-
-       ret = fs_set_property(fd_fs, "gid", "5");
-       if (ret < 0)
-               SYSTRACE("Failed to set \"gid=5\" on devpts filesystem context %d", fd_fs);
-
-       ret = fs_set_flag(fd_fs, "newinstance");
-       if (ret < 0)
-               return syserror("Failed to set \"newinstance\" property on devpts filesystem context %d", fd_fs);
+       if (can_use_mount_api()) {
+               fd_fs = fs_prepare("devpts", -EBADF, "", 0, 0);
+               if (fd_fs < 0)
+                       return syserror("Failed to prepare filesystem context for devpts");
 
-       ret = fs_set_property(fd_fs, "ptmxmode", "0666");
-       if (ret < 0)
-               return syserror("Failed to set \"ptmxmode=0666\" property on devpts filesystem context %d", fd_fs);
+               ret = fs_set_property(fd_fs, "source", "devpts");
+               if (ret < 0)
+                       SYSTRACE("Failed to set \"source=devpts\" on devpts filesystem context %d", fd_fs);
 
-       ret = fs_set_property(fd_fs, "mode", "0620");
-       if (ret < 0)
-               return syserror("Failed to set \"mode=0620\" property on devpts filesystem context %d", fd_fs);
+               ret = fs_set_property(fd_fs, "gid", "5");
+               if (ret < 0)
+                       SYSTRACE("Failed to set \"gid=5\" on devpts filesystem context %d", fd_fs);
 
-       ret = fs_set_property(fd_fs, "max", fdstr(conf->pty_max));
-       if (ret < 0)
-               return syserror("Failed to set \"max=%zu\" property on devpts filesystem context %d", conf->pty_max, fd_fs);
+               ret = fs_set_flag(fd_fs, "newinstance");
+               if (ret < 0)
+                       return syserror("Failed to set \"newinstance\" property on devpts filesystem context %d", fd_fs);
 
-       ret = fsconfig(fd_fs, FSCONFIG_CMD_CREATE, NULL, NULL, 0);
-       if (ret < 0)
-               return syserror("Failed to finalize filesystem context %d", fd_fs);
+               ret = fs_set_property(fd_fs, "ptmxmode", "0666");
+               if (ret < 0)
+                       return syserror("Failed to set \"ptmxmode=0666\" property on devpts filesystem context %d", fd_fs);
 
-       fd_fsmnt = fsmount(fd_fs, FSMOUNT_CLOEXEC, MOUNT_ATTR_NOSUID | MOUNT_ATTR_NOEXEC);
-       if (fd_fsmnt < 0)
-               return syserror("Failed to create new mount for filesystem context %d", fd_fs);
-       TRACE("Created detached devpts mount %d", fd_fsmnt);
+               ret = fs_set_property(fd_fs, "mode", "0620");
+               if (ret < 0)
+                       return syserror("Failed to set \"mode=0620\" property on devpts filesystem context %d", fd_fs);
 
-       ret = move_mount(fd_fsmnt, "", rootfs->dfd_dev, "pts", MOVE_MOUNT_F_EMPTY_PATH);
-       if (ret)
-               return syserror("Failed to attach devpts mount %d to %d/pts", conf->devpts_fd, rootfs->dfd_dev);
+               ret = fs_set_property(fd_fs, "max", fdstr(conf->pty_max));
+               if (ret < 0)
+                       return syserror("Failed to set \"max=%zu\" property on devpts filesystem context %d", conf->pty_max, fd_fs);
 
-       DEBUG("Attached detached devpts mount %d to %d/pts", fd_fsmnt, rootfs->dfd_dev);
-       handler->conf->devpts_fd = move_fd(fd_fsmnt);
-       return 0;
-}
+               ret = fsconfig(fd_fs, FSCONFIG_CMD_CREATE, NULL, NULL, 0);
+               if (ret < 0)
+                       return syserror("Failed to finalize filesystem context %d", fd_fs);
 
-static int lxc_finalize_devpts_child(struct lxc_handler *handler)
-{
-       int ret;
-       char **opts;
-       char devpts_mntopts[256];
-       char *mntopt_sets[5];
-       char default_devpts_mntopts[256] = "gid=5,newinstance,ptmxmode=0666,mode=0620";
-       struct lxc_conf *conf = handler->conf;
-       struct lxc_rootfs *rootfs = &conf->rootfs;
+               devpts_fd = fsmount(fd_fs, FSMOUNT_CLOEXEC, MOUNT_ATTR_NOSUID | MOUNT_ATTR_NOEXEC);
+               if (devpts_fd < 0)
+                       return syserror("Failed to create new mount for filesystem context %d", fd_fs);
+               TRACE("Created detached devpts mount %d", devpts_fd);
 
-       if (conf->pty_max <= 0)
-               return log_debug(0, "No new devpts instance will be mounted since no pts devices are requested");
+               ret = move_mount(devpts_fd, "", rootfs->dfd_dev, "pts", MOVE_MOUNT_F_EMPTY_PATH);
+               if (ret)
+                       return syserror("Failed to attach devpts mount %d to %d/pts", conf->devpts_fd, rootfs->dfd_dev);
 
-       if (!can_use_mount_api()) {
-               __do_close int devpts_fd = -EBADF;
+               DEBUG("Attached detached devpts mount %d to %d/pts", devpts_fd, rootfs->dfd_dev);
+       } else {
+               char **opts;
+               char devpts_mntopts[256];
+               char *mntopt_sets[5];
+               char default_devpts_mntopts[256] = "gid=5,newinstance,ptmxmode=0666,mode=0620";
 
                /*
                 * Fallback codepath in case the new mount API can't be used to
@@ -1760,8 +1744,6 @@ static int lxc_finalize_devpts_child(struct lxc_handler *handler)
                if (ret < 0)
                        return -1;
 
-               (void)umount2("/dev/pts", MNT_DETACH);
-
                /* Create mountpoint for devpts instance. */
                ret = mkdirat(rootfs->dfd_dev, "pts", 0755);
                if (ret < 0 && errno != EEXIST)
@@ -1797,9 +1779,9 @@ static int lxc_finalize_devpts_child(struct lxc_handler *handler)
                        TRACE("Failed to create detached devpts mount");
                }
 
-               handler->conf->devpts_fd = move_fd(devpts_fd);
                DEBUG("Mounted new devpts instance with options \"%s\"", *opts);
        }
+       handler->conf->devpts_fd = move_fd(devpts_fd);
 
        /* Remove any pre-existing /dev/ptmx file. */
        ret = unlinkat(rootfs->dfd_dev, "ptmx", 0);
@@ -4237,7 +4219,7 @@ int lxc_setup(struct lxc_handler *handler)
        if (ret < 0)
                return log_error(-1, "Failed to mount transient procfs instance for LSMs");
 
-       ret = lxc_prepare_devpts_child(handler);
+       ret = lxc_setup_devpts_child(handler);
        if (ret < 0)
                return log_error(-1, "Failed to prepare new devpts instance");
 
@@ -4258,10 +4240,6 @@ int lxc_setup(struct lxc_handler *handler)
        if (lxc_conf->autodev > 0)
                (void)lxc_setup_boot_id();
 
-       ret = lxc_finalize_devpts_child(handler);
-       if (ret < 0)
-               return log_error(-1, "Failed to setup new devpts instance");
-
        ret = lxc_create_ttys(handler);
        if (ret < 0)
                return -1;