Messages in this thread | | | Date | Fri, 4 Nov 2022 10:05:50 +0100 | Subject | Re: [PATCH] crypto: caam: blob_gen.c: warn if key is insecure | From | Ahmad Fatoum <> |
| |
Hello Nikolaus,
On 19.10.22 14:44, Nikolaus Voss wrote: > If CAAM is not in "trusted" or "secure" state, a fixed non-volatile key > is used instead of the unique device key. This is the default mode of > operation without secure boot (HAB). In this scenario, CAAM encrypted > blobs should be used only for testing but not in a production > environment, so issue a warning.
Thanks for your patch.
> Signed-off-by: Nikolaus Voss <nikolaus.voss@haag-streit.com> > --- > drivers/crypto/caam/blob_gen.c | 8 ++++++++ > drivers/crypto/caam/regs.h | 3 +++ > 2 files changed, 11 insertions(+) > > diff --git a/drivers/crypto/caam/blob_gen.c b/drivers/crypto/caam/blob_gen.c > index 6345c7269eb0..f3e741393f65 100644 > --- a/drivers/crypto/caam/blob_gen.c > +++ b/drivers/crypto/caam/blob_gen.c > @@ -6,6 +6,7 @@ > > #define pr_fmt(fmt) "caam blob_gen: " fmt > > +#include <linux/bitfield.h> > #include <linux/device.h> > #include <soc/fsl/caam-blob.h> > > @@ -62,11 +63,13 @@ int caam_process_blob(struct caam_blob_priv *priv, > struct caam_blob_info *info, bool encap)
I agree with Herbert that this may not be the best place. I think a single warning during caam_blob_gen_init() would suffice.
> { > struct caam_blob_job_result testres; > + const struct caam_drv_private *ctrlpriv; > struct device *jrdev = &priv->jrdev; > dma_addr_t dma_in, dma_out; > int op = OP_PCLID_BLOB; > size_t output_len; > u32 *desc; > + u32 moo; > int ret; > > if (info->key_mod_len > CAAM_BLOB_KEYMOD_LENGTH) > @@ -100,6 +103,11 @@ int caam_process_blob(struct caam_blob_priv *priv, > goto out_unmap_in; > } > > + ctrlpriv = dev_get_drvdata(jrdev->parent); > + moo = FIELD_GET(CSTA_MOO, ctrlpriv->ctrl->perfmon.status); > + if (moo != CSTA_MOO_SECURE && moo != CSTA_MOO_TRUSTED) > + dev_warn(jrdev, "using insecure test key!\n");
I'd make the warning a bit more verbose, e.g.
"device not configured for trusted/secure mode: using insecure test key!"
> + > /* > * A data blob is encrypted using a blob key (BK); a random number. > * The BK is used as an AES-CCM key. The initial block (B0) and the > diff --git a/drivers/crypto/caam/regs.h b/drivers/crypto/caam/regs.h > index 66d6dad841bb..b7de5fb5e056 100644 > --- a/drivers/crypto/caam/regs.h > +++ b/drivers/crypto/caam/regs.h > @@ -426,6 +426,9 @@ struct caam_perfmon { > u32 rsvd2; > #define CSTA_PLEND BIT(10) > #define CSTA_ALT_PLEND BIT(18) > +#define CSTA_MOO GENMASK(9, 8) > +#define CSTA_MOO_SECURE 1 > +#define CSTA_MOO_TRUSTED 3
I just checked the i.MX6 and LS1046 security reference manuals and both have Trusted as 2 (10b). 3 is fail. Does you SoC differ? Either way, please note what SoC you were testing on in the commit message.
> u32 status; /* CSTA - CAAM Status */ > u64 rsvd3; >
Cheers, Ahmad
-- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
| |