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References: <20230420165454.9517-1-jorge.lopez2@hp.com> <20230420165454.9517-12-jorge.lopez2@hp.com>
 <7364268c-cbff-42a3-a79a-069eef31899e@t-8ch.de>
In-Reply-To: <7364268c-cbff-42a3-a79a-069eef31899e@t-8ch.de>
From:   Jorge Lopez <jorgealtxwork@gmail.com>
Date:   Wed, 3 May 2023 14:34:43 -0500
Message-ID: <CAOOmCE-jP8Romsx+wYrRjOHj_VNh3m+JR4fnd1T0gjJm+n145Q@mail.gmail.com>
Subject: Re: [PATCH v11 11/14] HP BIOSCFG driver - spmobj-attributes
To:     thomas@t-8ch.de
Cc:     hdegoede@redhat.com, platform-driver-x86@vger.kernel.org,
        linux-kernel@vger.kernel.org
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On Sun, Apr 23, 2023 at 4:24=E2=80=AFAM <thomas@t-8ch.de> wrote:
>
> On 2023-04-20 11:54:51-0500, Jorge Lopez wrote:
> >  .../x86/hp/hp-bioscfg/spmobj-attributes.c     | 405 ++++++++++++++++++
> >  1 file changed, 405 insertions(+)
> >  create mode 100644 drivers/platform/x86/hp/hp-bioscfg/spmobj-attribute=
s.c
> >
> > diff --git a/drivers/platform/x86/hp/hp-bioscfg/spmobj-attributes.c b/d=
rivers/platform/x86/hp/hp-bioscfg/spmobj-attributes.c
> > new file mode 100644
> > index 000000000000..78228f44c39b
> > --- /dev/null
> > +++ b/drivers/platform/x86/hp/hp-bioscfg/spmobj-attributes.c
> > @@ -0,0 +1,405 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Functions corresponding to secure platform management object type
> > + * attributes under BIOS PASSWORD for use with hp-bioscfg driver
> > + *
> > + *  Copyright (c) 2022 HP Development Company, L.P.
> > + */
> > +
> > +#include "bioscfg.h"
> > +
> > +
> > +static const char * const spm_state_types[] =3D {
> > +     "not provisioned",
> > +     "provisioned",
> > +     "provisioning in progress"
> > +};
> > +
> > +static const char * const spm_mechanism_types[] =3D {
> > +     "not provision",
>
> "not provisioned" as above?

Good catch.  Done!
>
> > +     "signing-key",
> > +     "endorsement-key"
>
> Trailing commas please.
>
Done!
> > +};
> > +
> > +
> > +int check_spm_is_enabled(void)
> > +{
> > +     /* do we need to check the admin password is also configured */
> > +     return bioscfg_drv.spm_data.is_enabled;
> > +}
> > +
> > +/*
> > + * calculate_security_buffer() - determines size of security buffer
> > + * for authentication scheme
> > + *
> > + * @authentication: the authentication content
> > + *
> > + * Currently only supported type is Admin password
> > + */
> > +size_t calculate_security_buffer(const char *authentication)
> > +{
> > +     int size;
> > +
> > +     if (authentication !=3D NULL && strlen(authentication) > 0) {
> > +
> > +             size =3D (sizeof(u16) + (strlen(authentication) * sizeof(=
u16)));
> > +             if (strncmp(authentication, BEAM_PREFIX, strlen(BEAM_PREF=
IX)) !=3D 0)
>
> strstarts()

Done!
>
> > +                     size +=3D (strlen(UTF_PREFIX) * sizeof(u16));
>
> No need for braces.

Done!
>
> > +
> > +             return size;
> > +     }
> > +
> > +     size  =3D sizeof(u16) * 2;
> > +     return size;
> > +}
> > +
> > +/*
> > + * populate_security_buffer() - builds a security buffer for
> > + * authentication scheme
> > + *
> > + * @buffer: the buffer to populate
> > + * @authentication: the authentication content
> > + *
> > + * Currently only supported type is PLAIN TEXT
> > + */
> > +void populate_security_buffer(u16 *buffer, const char *authentication)
> > +{
> > +     u16 *auth =3D buffer;
> > +     char *strprefix =3D NULL;
> > +
> > +     if (strncmp(authentication, BEAM_PREFIX, strlen(BEAM_PREFIX)) =3D=
=3D 0) {
>
> strstarts()

Done!
>
> > +             /*
> > +              * BEAM_PREFIX is append to buffer when a signature
> > +              * is provided and Sure Admin is enabled in BIOS
> > +              */
> > +             // BEAM_PREFIX found, convert part to unicode
> > +             auth =3D ascii_to_utf16_unicode(auth, authentication);
> > +     } else {
> > +             /*
> > +              * UTF-16 prefix is append to the * buffer when a BIOS
> > +              * admin password is configured in BIOS
> > +              */
> > +
> > +             // append UTF_PREFIX to part and then convert it to unico=
de
> > +             strprefix =3D kasprintf(GFP_KERNEL, "%s%s", UTF_PREFIX,
> > +                                   authentication);
> > +             if (!strprefix)
> > +                     goto out_buffer;
> > +
> > +             auth =3D ascii_to_utf16_unicode(auth, strprefix);
> > +     }
> > +out_buffer:
> > +
> > +     kfree(strprefix);
> > +}
> > +
> > +ssize_t update_spm_state(void)
> > +{
> > +     int ret;
> > +     struct secureplatform_provisioning_data *data =3D NULL;
>
> This can be allocated on the stack.

Done!
>
> > +
> > +     data =3D kmalloc(sizeof(struct secureplatform_provisioning_data),
> > +                    GFP_KERNEL);
> > +     if (!data) {
> > +             ret =3D -ENOMEM;
> > +             goto state_exit;
> > +     }
> > +
> > +     ret =3D hp_wmi_perform_query(HPWMI_SECUREPLATFORM_GET_STATE,
> > +                                HPWMI_SECUREPLATFORM, data, 0,
> > +                                sizeof(*data));
> > +     if (ret < 0)
> > +             goto state_exit;
> > +
> > +     bioscfg_drv.spm_data.mechanism =3D data->state;
> > +     if (bioscfg_drv.spm_data.mechanism)
> > +             bioscfg_drv.spm_data.is_enabled =3D 1;
> > +
> > +state_exit:
> > +     kfree(data);
> > +
> > +     return ret;
> > +}
> > +
> > +ssize_t statusbin(struct kobject *kobj,
> > +               struct kobj_attribute *attr, char *buf)
>
> This can be static.

Done!
>
> If it is known that a struct secureplatform_provisioning_data is to be
> passed, then the type can reflect that.

Done!
>
> > +{
> > +     int ret =3D hp_wmi_perform_query(HPWMI_SECUREPLATFORM_GET_STATE,
> > +                                    HPWMI_SECUREPLATFORM, buf, 0,
> > +                                    sizeof(struct secureplatform_provi=
sioning_data));
> > +
> > +     return ret ? -ENODEV : sizeof(struct secureplatform_provisioning_=
data);
>
> Why not return "ret" on error?

Good point. Done!
>
> > +}
> > +
> > +/*
> > + * status_show - Reads SPM status
> > + */
> > +ssize_t status_show(struct kobject *kobj, struct kobj_attribute
> > +                 *attr, char *buf)
> > +{
> > +     int ret, i;
> > +     struct secureplatform_provisioning_data *data =3D NULL;
>
> Can also be on-stack.

Done!
>
<snip>
> > +static struct kobj_attribute password_spm_key_mechanism =3D __ATTR_RO(=
key_mechanism);
> > +
> > +static ssize_t sk_store(struct kobject *kobj,
> > +                     struct kobj_attribute *attr,
> > +                     const char *buf, size_t count)
> > +{
> > +     int ret;
> > +     int length;
> > +
> > +     length =3D count;
> > +     if (buf[length-1] =3D=3D '\n')
> > +             length--;
> > +
> > +     /* allocate space and copy current signing key */
> > +     bioscfg_drv.spm_data.signing_key =3D kmalloc(length, GFP_KERNEL);
> > +     if (!bioscfg_drv.spm_data.signing_key) {
> > +             ret =3D -ENOMEM;
> > +             goto exit_sk;
> > +     }
> > +
> > +     memcpy(bioscfg_drv.spm_data.signing_key, buf, length);
> > +     bioscfg_drv.spm_data.signing_key[length] =3D '\0';
>
> Is this supposed to handle zero-bytes in the input?
> If yes: Did you test this with zero bytes, I don't think the normal
> attribute APIs handle this.
> If no: Why not use strscpy?
>

Done!

<snip>