[PATCH v1 1/6] lib: add crypt subsystem

[Simon Glass]

Hi Steffen,

On Sat, 1 May 2021 at 03:51, Steffen Jaeckel
<jaeckel-floss at eyet-services.de> wrote:
>
> Hi Simon,
>
> On 4/29/21 6:10 PM, Simon Glass wrote:
> >> diff --git a/include/crypt.h b/include/crypt.h
> >> new file mode 100644
> >> index 0000000000..e0be2832ff
> >> --- /dev/null
> >> +++ b/include/crypt.h
> >> @@ -0,0 +1,13 @@
> >> +/* SPDX-License-Identifier: GPL-2.0+ */
> >> +/* Copyright (C) 2020 Steffen Jaeckel <jaeckel-floss at eyet-services.de> */
> >> +
> >> +/**
> >> + * Compare should with the processed passphrase.
> >> + *
> >> + * @should      The crypt-style string to compare against
> >> + * @passphrase  The plaintext passphrase
> >> + * @equal       Pointer to an int where the result is stored
> >> + *                 '0' = unequal
> >> + *                 '1' = equal
> >
> > Can this be a return value from the function? true/false
>
> ... the next patch in the series changes the return type to int ... I'll
> rework those to make this better visible.
>
> The concept stayed the same as IMO this would complicate the handling in
> the caller and with this pattern the usage is a lot easier:
> * return value indicates success of the operation
> * `equal` argument returns whether the given crypt-style string equals
> the hashed passphrase

Well that's up to you, but it is pretty common in U-Boot to return an
error code or a true/false value.

>
>
> >> + */
> >> +void crypt_compare(const char *should, const char *passphrase, int *equal);
> >> diff --git a/lib/Kconfig b/lib/Kconfig
> >> index 6d2d41de30..c7c0b87ec7 100644
> >> --- a/lib/Kconfig
> >> +++ b/lib/Kconfig
> >> @@ -297,6 +297,7 @@ config AES
> >>
> >>  source lib/rsa/Kconfig
> >>  source lib/crypto/Kconfig
> >> +source lib/crypt/Kconfig
> >>
> >>  config TPM
> >>         bool "Trusted Platform Module (TPM) Support"
> >> diff --git a/lib/Makefile b/lib/Makefile
> >> index 6825671955..f0d91986b1 100644
> >> --- a/lib/Makefile
> >> +++ b/lib/Makefile
> >> @@ -65,6 +65,7 @@ obj-$(CONFIG_FIT_SIGNATURE) += hash-checksum.o
> >>  obj-$(CONFIG_SHA1) += sha1.o
> >>  obj-$(CONFIG_SHA256) += sha256.o
> >>  obj-$(CONFIG_SHA512_ALGO) += sha512.o
> >> +obj-$(CONFIG_CRYPT_PW) += crypt/
> >>
> >>  obj-$(CONFIG_$(SPL_)ZLIB) += zlib/
> >>  obj-$(CONFIG_$(SPL_)ZSTD) += zstd/
> >> diff --git a/lib/crypt/Kconfig b/lib/crypt/Kconfig
> >> new file mode 100644
> >> index 0000000000..6f828cefd6
> >> --- /dev/null
> >> +++ b/lib/crypt/Kconfig
> >> @@ -0,0 +1,29 @@
> >> +config CRYPT_PW
> >> +       bool "Add crypt support for password-based unlock"
> >> +       help
> >> +         Enable support for crypt-style hashed passphrases.
> >> +         This will then be used as the mechanism of choice to
> >> +         verify whether the entered password to unlock the
> >> +         console is correct or not.
> >> +         To make it fully functional, one has also to enable
> >> +         CONFIG_AUTOBOOT_KEYED and CONFIG_AUTOBOOT_ENCRYPTION
> >
> > So should CRYPT_PW depend on one or both of those?
>
> Should it depend or can it also select?

Depend is better, as I understand it, but not sure if this applies to you:

https://docs.zephyrproject.org/1.14.0/guides/kconfig/index.html#select-pitfalls

>
> > ...
> >> diff --git a/lib/crypt/crypt-sha256.c b/lib/crypt/crypt-sha256.c
> >> new file mode 100644
> >> index 0000000000..37127d41e1
> >> --- /dev/null
> >> +++ b/lib/crypt/crypt-sha256.c
> >> @@ -0,0 +1,313 @@
> >> +/* One way encryption based on the SHA256-based Unix crypt implementation.
> >> + *
> >> + * Written by Ulrich Drepper <drepper at redhat.com> in 2007 [1].
> >> + * Modified by Zack Weinberg <zackw at panix.com> in 2017, 2018.
> >> + * Composed by Björn Esser <besser82 at fedoraproject.org> in 2018.
> >> + * Modified by Björn Esser <besser82 at fedoraproject.org> in 2020.
> >> + * Modified by Steffen Jaeckel <jaeckel-floss at eyet-services.de> in 2020.
> >> + * To the extent possible under law, the named authors have waived all
> >> + * copyright and related or neighboring rights to this work.
> >> + *
> >> + * See https://creativecommons.org/publicdomain/zero/1.0/ for further
> >> + * details.
> >> + *
> >> + * This file is a modified except from [2], lines 648 up to 909.
> >> + *
> >> + * [1]  https://www.akkadia.org/drepper/sha-crypt.html
> >> + * [2]  https://www.akkadia.org/drepper/SHA-crypt.txt
> >
> > Can you add SPDX to the new files?
>
> Sure, after we're done with those files I'll see which parts I can
> upstream to libxcrypt.

OK.

Regards,
Simon