conf: rework console setup

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

diff --git a/src/lxc/conf.c b/src/lxc/conf.c
index 7ca155e73193d77d8d80f3f2f77d5b86da8b4497..1161365419ae94a7bcabf4c02592a4f0bf3c5654 100644 (file)
--- a/src/lxc/conf.c
+++ b/src/lxc/conf.c
@@ -1834,8 +1834,8 @@ static inline bool wants_console(const struct lxc_terminal *terminal)
        return !terminal->path || !strequal(terminal->path, "none");
 }
 
-static int lxc_bind_mount_console(const struct lxc_terminal *console,
-                                 int dfd_to, const char *path_to)
+static int bind_mount_console(struct lxc_rootfs *rootfs,
+                             struct lxc_terminal *console, int fd_to)
 {
        __do_close int fd_pty = -EBADF;
 
@@ -1856,25 +1856,23 @@ static int lxc_bind_mount_console(const struct lxc_terminal *console,
         * created a detached mount based on the newly opened O_PATH file
         * descriptor and then safely mount.
         */
-       fd_pty = open_at(-EBADF, console->name, PROTECT_OPATH_FILE,
-                        PROTECT_LOOKUP_ABSOLUTE_XDEV, 0);
+       fd_pty = open_at_same(console->pty, rootfs->dfd_host, deabs(console->name),
+                             PROTECT_OPATH_FILE, PROTECT_LOOKUP_ABSOLUTE_XDEV, 0);
        if (fd_pty < 0)
-               return log_error_errno(-errno, errno, "Failed to open \"%s\"", console->name);
-
-       if (!same_file_lax(console->pty, fd_pty))
-               return log_error_errno(-EINVAL, EINVAL, "Console file descriptor changed");
+               return syserror("Failed to open \"%s\"", console->name);
 
        /*
         * Note, there are intentionally no open or lookup restrictions since
         * we're operating directly on the fd.
         */
-       return fd_bind_mount(fd_pty, "", 0, 0,
-                            dfd_to, path_to, PROTECT_OPATH_FILE, PROTECT_LOOKUP_BENEATH,
-                            0, false);
+       if (can_use_mount_api())
+               return fd_bind_mount(fd_pty, "", 0, 0, fd_to, "", 0, 0, 0, false);
+
+       return mount_fd(fd_pty, fd_to, "none", MS_BIND, 0);
 }
 
 static int lxc_setup_dev_console(struct lxc_rootfs *rootfs,
-                                const struct lxc_terminal *console)
+                                struct lxc_terminal *console)
 {
        __do_close int fd_console = -EBADF;
        int ret;
@@ -1901,56 +1899,68 @@ static int lxc_setup_dev_console(struct lxc_rootfs *rootfs,
         * For unprivileged containers autodev or automounts will already have
         * taken care of creating /dev/console.
         */
-       fd_console = open_at(rootfs->dfd_dev, "console", PROTECT_OPEN | O_CREAT,
-                            PROTECT_LOOKUP_BENEATH, 0000);
+       fd_console = open_at(rootfs->dfd_dev,
+                            "console",
+                            PROTECT_OPEN | O_CREAT,
+                            PROTECT_LOOKUP_BENEATH,
+                            0000);
        if (fd_console < 0)
-               return syserror("Failed to create console");
+               return syserror("Failed to create \"%d/console\"", rootfs->dfd_dev);
 
        ret = fchmod(console->pty, 0620);
        if (ret < 0)
-               return log_error_errno(-errno, errno, "Failed to set mode \"0%o\" to \"%s\"", 0620, console->name);
+               return syserror("Failed to change console mode");
 
-       if (can_use_mount_api())
-               ret = lxc_bind_mount_console(console, rootfs->dfd_dev, "console");
-       else
-               ret = mount_fd(console->pty, fd_console, "none", MS_BIND, NULL);
+       ret = bind_mount_console(rootfs, console, fd_console);
        if (ret < 0)
-               return log_error_errno(ret, errno, "Failed to mount %d(%s) on \"%s\"", console->pty, console->name, rootfs->buf);
+               return syserror("Failed to mount \"%d(%s)\" on \"%d\"",
+                               console->pty, console->name, fd_console);
 
-       DEBUG("Mounted pty device %d(%s) onto \"/dev/console\"", console->pty, console->name);
+       TRACE("Setup console \"%s\"", console->name);
        return 0;
 }
 
 static int lxc_setup_ttydir_console(struct lxc_rootfs *rootfs,
-                                   const struct lxc_terminal *console,
+                                   struct lxc_terminal *console,
                                    char *ttydir)
 {
-       __do_close int fd_console = -EBADF, fd_ttydir_console = -EBADF;
+       __do_close int fd_ttydir = -EBADF, fd_dev_console = -EBADF,
+                      fd_reg_console = -EBADF, fd_reg_ttydir_console = -EBADF;
        int ret;
-       char path[PATH_MAX], lxcpath[PATH_MAX];
-       char *rootfs_path = rootfs->path ? rootfs->mount : "";
 
        /* create dev/<ttydir> */
        ret = mkdirat(rootfs->dfd_dev, ttydir, 0755);
        if (ret < 0 && errno != EEXIST)
                return syserror("Failed to create \"%d/%s\"", rootfs->dfd_dev, ttydir);
-       TRACE("Created directory \"%d/%s\" for console and tty devices", rootfs->dfd_dev, ttydir);
+
+       fd_ttydir = open_at(rootfs->dfd_dev,
+                           ttydir,
+                           PROTECT_OPATH_DIRECTORY,
+                           PROTECT_LOOKUP_BENEATH,
+                           0);
+       if (fd_ttydir < 0)
+               return syserror("Failed to open \"%d/%s\"", rootfs->dfd_dev, ttydir);
 
        ret = strnprintf(rootfs->buf, sizeof(rootfs->buf), "%s/console", ttydir);
        if (ret < 0)
                return -1;
 
        /* create dev/<ttydir>/console */
-       fd_ttydir_console = open_at(rootfs->dfd_dev, rootfs->buf, PROTECT_OPEN | O_CREAT,
-                            PROTECT_LOOKUP_BENEATH, 0000);
-       if (fd_ttydir_console < 0)
-               return syserror("Failed to create console");
-
-       ret = strnprintf(rootfs->buf, sizeof(rootfs->buf), "%s/dev/console", rootfs_path);
-       if (ret < 0)
-               return -1;
+       fd_reg_ttydir_console = open_at(fd_ttydir,
+                                       "console",
+                                       PROTECT_OPEN | O_CREAT,
+                                       PROTECT_LOOKUP_BENEATH,
+                                       0000);
+       if (fd_reg_ttydir_console < 0)
+               return syserror("Failed to create \"%d/console\"", fd_ttydir);
 
        if (file_exists(rootfs->buf)) {
+               char *rootfs_path = rootfs->path ? rootfs->mount : "";
+
+               ret = strnprintf(rootfs->buf, sizeof(rootfs->buf), "%s/dev/console", rootfs_path);
+               if (ret < 0)
+                       return -1;
+
                ret = lxc_unstack_mountpoint(rootfs->buf, false);
                if (ret < 0)
                        return log_error_errno(-ret, errno, "Failed to unmount \"%s\"", rootfs->buf);
@@ -1958,45 +1968,53 @@ static int lxc_setup_ttydir_console(struct lxc_rootfs *rootfs,
                        DEBUG("Cleared all (%d) mounts from \"%s\"", ret, rootfs->buf);
        }
 
-       /* create dev/<ttydir>/console */
-       fd_console = open_at(rootfs->dfd_dev, "console", PROTECT_OPEN | O_CREAT,
-                            PROTECT_LOOKUP_BENEATH, 0000);
-       if (fd_console < 0)
-               return syserror("Failed to create console");
+       /* create dev/console */
+       fd_reg_console = open_at(rootfs->dfd_dev,
+                               "console",
+                                PROTECT_OPEN | O_CREAT,
+                                PROTECT_LOOKUP_BENEATH,
+                                0000);
+       if (fd_reg_console < 0)
+               return syserror("Failed to create \"%d/console\"", rootfs->dfd_dev);
 
        ret = fchmod(console->pty, 0620);
        if (ret < 0)
-               return syserror("Failed to set mode \"0%o\" to \"%s\"", 0620, console->name);
+               return syserror("Failed to change console mode");
 
-       /* bind mount console->name to '/dev/<ttydir>/console' */
-       if (can_use_mount_api()) {
-               ret = strnprintf(rootfs->buf, sizeof(rootfs->buf), "%s/console", ttydir);
-               if (ret < 0)
-                       return ret;
-
-               ret = lxc_bind_mount_console(console, rootfs->dfd_dev, rootfs->buf);
-       } else {
-               ret = mount_fd(console->pty, fd_ttydir_console, "none", MS_BIND, 0);
-       }
+       /* bind mount console to '/dev/<ttydir>/console' */
+       ret = bind_mount_console(rootfs, console, fd_reg_ttydir_console);
        if (ret < 0)
-               return log_error_errno(ret, errno, "Failed to mount %d(%s) on \"%s\"", console->pty, console->name, lxcpath);
-       DEBUG("Mounted \"%s\" onto \"%s\"", console->name, lxcpath);
-
-       /* bind mount '/dev/<ttydir>/console'  to '/dev/console'  */
-       if (can_use_mount_api()) {
-               ret = fd_bind_mount(rootfs->dfd_dev, rootfs->buf,
-                                   PROTECT_OPATH_FILE, PROTECT_LOOKUP_BENEATH_XDEV,
-                                   rootfs->dfd_dev, "console",
-                                   PROTECT_OPATH_FILE, PROTECT_LOOKUP_BENEATH,
-                                   0, false);
-       } else {
-               ret = mount_fd(fd_ttydir_console, fd_console, "none", MS_BIND, 0);
-       }
+               return syserror("Failed to mount \"%d(%s)\" on \"%d\"",
+                               console->pty, console->name, fd_reg_ttydir_console);
+
+       fd_dev_console = open_at_same(console->pty,
+                                     fd_ttydir,
+                                     "console",
+                                     PROTECT_OPATH_FILE,
+                                     PROTECT_LOOKUP_BENEATH_XDEV,
+                                     0);
+       if (fd_dev_console < 0)
+               return syserror("Failed to open \"%d/console\"", fd_ttydir);
+
+       /* bind mount '/dev/<ttydir>/console' to '/dev/console' */
+       if (can_use_mount_api())
+               ret = fd_bind_mount(fd_dev_console,
+                                   "",
+                                   PROTECT_OPATH_FILE,
+                                   PROTECT_LOOKUP_BENEATH_XDEV,
+                                   fd_reg_console,
+                                   "",
+                                   PROTECT_OPATH_FILE,
+                                   PROTECT_LOOKUP_BENEATH,
+                                   0,
+                                   false);
+       else
+               ret = mount_fd(fd_dev_console, fd_reg_console, "none", MS_BIND, 0);
        if (ret < 0)
-               return log_error_errno(-1, errno, "Failed to mount \"%s\" on \"%s\"", console->name, lxcpath);
-       DEBUG("Mounted \"%s\" onto \"%s\"", lxcpath, path);
+               return syserror("Failed to mount \"%d\" on \"%d\"",
+                               fd_dev_console, fd_reg_console);
 
-       DEBUG("Console has been setup under \"%s\" and mounted to \"%s\"", lxcpath, path);
+       TRACE("Setup console \"%s\"", console->name);
        return 0;
 }