diff options
Diffstat (limited to 'fs/super.c')
| -rw-r--r-- | fs/super.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/fs/super.c b/fs/super.c index 095ba793e10c..38d72a3cf6fc 100644 --- a/fs/super.c +++ b/fs/super.c @@ -736,6 +736,17 @@ struct super_block *sget_fc(struct fs_context *fc, struct user_namespace *user_ns = fc->global ? &init_user_ns : fc->user_ns; int err; + /* + * Never allow s_user_ns != &init_user_ns when FS_USERNS_MOUNT is + * not set, as the filesystem is likely unprepared to handle it. + * This can happen when fsconfig() is called from init_user_ns with + * an fs_fd opened in another user namespace. + */ + if (user_ns != &init_user_ns && !(fc->fs_type->fs_flags & FS_USERNS_MOUNT)) { + errorfc(fc, "VFS: Mounting from non-initial user namespace is not allowed"); + return ERR_PTR(-EPERM); + } + retry: spin_lock(&sb_lock); if (test) { |