[PATCH v2 36/39] overlayfs: do not mount on top of idmapped mounts

Prevent overlayfs from being mounted on top of idmapped mounts until we have ported it to handle this case and added proper testing for it. Cc: Christoph Hellwig <hch(a)lst.de&gt; Cc: David Howells <dhowells(a)redhat.com&gt; Cc: Al Viro <viro(a)zeniv.linux.org.uk&gt; Cc: linux-fsdevel(a)vger.kernel.org Signed-off-by: Christian Brauner <christian.brauner(a)ubuntu.com&gt; --- /* v2 */ patch introduced --- fs/overlayfs/super.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 0d4f2baf6836..3cacc3d3fb65 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -1708,6 +1708,12 @@ static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb, if (err) goto out_err; + if (mnt_idmapped(stack[i].mnt)) { + err = -EINVAL; + pr_err("idmapped lower layers are currently unsupported\n"); + goto out_err; + } + lower = strchr(lower, '\0') + 1; } @@ -1939,6 +1945,12 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) if (err) goto out_err; + if (mnt_idmapped(upperpath.mnt)) { + err = -EINVAL; + pr_err("idmapped lower layers are currently unsupported\n"); + goto out_err; + } + err = ovl_get_workdir(sb, ofs, &upperpath); if (err) goto out_err; -- 2.29.2