conf: switch mount_autodev() to new safe_mount_beneath() helper

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

diff --git a/src/lxc/conf.c b/src/lxc/conf.c
index 2e513d1cc7bd0c538f01387ccabcf3109978e81c..5fcfb0afa3229bf93fc29739981f8339c0675f0b 100644 (file)
--- a/src/lxc/conf.c
+++ b/src/lxc/conf.c
@@ -1051,50 +1051,55 @@ on_error:
 static int mount_autodev(const char *name, const struct lxc_rootfs *rootfs,
                         int autodevtmpfssize, const char *lxcpath)
 {
-       __do_free char *path = NULL;
+       __do_close int root_mntpt_fd = -EBADF;
+       const char *path = rootfs->path ? rootfs->mount : NULL;
        int ret;
-       size_t clen;
        mode_t cur_mask;
         char mount_options[128];
 
        INFO("Preparing \"/dev\"");
 
-       /* $(rootfs->mount) + "/dev/pts" + '\0' */
-       clen = (rootfs->path ? strlen(rootfs->mount) : 0) + 9;
-       path = must_realloc(NULL, clen);
        sprintf(mount_options, "size=%d,mode=755", (autodevtmpfssize != 0) ? autodevtmpfssize : 500000);
        DEBUG("Using mount options: %s", mount_options);
 
-       ret = snprintf(path, clen, "%s/dev", rootfs->path ? rootfs->mount : "");
-       if (ret < 0 || (size_t)ret >= clen)
-               return -1;
+       root_mntpt_fd = openat(-1, path, O_RDONLY | O_CLOEXEC | O_PATH | O_DIRECTORY);
+       if (root_mntpt_fd < 0)
+               return log_error_errno(-errno, errno, "Failed to open \"%s\"", path);
 
        cur_mask = umask(S_IXUSR | S_IXGRP | S_IXOTH);
-       ret = mkdir(path, S_IRWXU | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH);
+       ret = mkdirat(root_mntpt_fd, "dev" , S_IRWXU | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH);
        if (ret < 0 && errno != EEXIST) {
                SYSERROR("Failed to create \"/dev\" directory");
                ret = -errno;
                goto reset_umask;
        }
 
-       ret = safe_mount("none", "dev", "tmpfs", 0, mount_options,
-                        rootfs->path ? rootfs->mount : NULL );
+       ret = safe_mount_beneath(path, "none", "dev", "tmpfs", 0, mount_options);
        if (ret < 0) {
-               SYSERROR("Failed to mount tmpfs on \"%s\"", path);
-               goto reset_umask;
-       }
-       TRACE("Mounted tmpfs on \"%s\"", path);
+               __do_free char *fallback_path = NULL;
 
-       ret = snprintf(path, clen, "%s/dev/pts", rootfs->path ? rootfs->mount : "");
-       if (ret < 0 || (size_t)ret >= clen) {
-               ret = -1;
-               goto reset_umask;
+               if (errno != ENOSYS) {
+                       SYSERROR("Failed to mount tmpfs on \"%s\"", path);
+                       goto reset_umask;
+               }
+
+               if (path) {
+                       fallback_path = must_make_path(path, "/dev", NULL);
+                       ret = safe_mount("none", fallback_path, "tmpfs", 0, mount_options, path);
+               } else {
+                       ret = safe_mount("none", "dev", "tmpfs", 0, mount_options, NULL);
+               }
+               if (ret < 0) {
+                       SYSERROR("Failed to mount tmpfs on \"%s\"", path);
+                       goto reset_umask;
+               }
        }
+       TRACE("Mounted tmpfs on \"%s\"", path);
 
        /* If we are running on a devtmpfs mapping, dev/pts may already exist.
         * If not, then create it and exit if that fails...
         */
-       ret = mkdir(path, S_IRWXU | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH);
+       ret = mkdirat(root_mntpt_fd, "dev/pts", S_IRWXU | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH);
        if (ret < 0 && errno != EEXIST) {
                SYSERROR("Failed to create directory \"%s\"", path);
                ret = -errno;