Re: [RFC PATCH v3 12/16] ceph: add encrypted fname handling to ceph_mdsc_build_path

[Eric Biggers <ebiggers@kernel.org>]

On Mon, Sep 14, 2020 at 03:17:03PM -0400, Jeff Layton wrote:
> +		} else {
> +			int err;
> +			struct fscrypt_name fname = { };
> +			int len;
> +			char buf[FSCRYPT_BASE64_CHARS(NAME_MAX)];
> +
> +			dget(parent);
> +			spin_unlock(&cur->d_lock);
> +
> +			err = fscrypt_setup_filename(d_inode(parent), &cur->d_name, 1, &fname);
> +			if (err) {
> +				dput(parent);
> +				dput(cur);
> +				return ERR_PTR(err);
> +			}

It's still not clear how no-key names are handled here (or if they are even
possible here).

> +
> +			/* base64 encode the encrypted name */
> +			len = fscrypt_base64_encode(fname.disk_name.name, fname.disk_name.len, buf);
> +			pos -= len;
> +			if (pos < 0) {
> +				dput(parent);
> +				fscrypt_free_filename(&fname);
> +				break;
> +			}
> +			memcpy(path + pos, buf, len);
> +			dout("non-ciphertext name = %.*s\n", len, buf);
> +			fscrypt_free_filename(&fname);

This says "non-ciphertext name", which suggest that it's a plaintext name.  But
actually it's a base64-encoded ciphertext name.

- Eric