Re: [PATCH v6 3/6] KEYS: trusted: Introduce NXP DCP-backed trusted keys
On Fri Mar 8, 2024 at 9:17 AM EET, David Gstir wrote:
> Hi Jarkko,
>
> > On 07.03.2024, at 20:30, Jarkko Sakkinen wrote:
>
> [...]
>
> >> +
> >> +static int trusted_dcp_init(void)
> >> +{
> >> + int ret;
> >> +
> >> + if (use_otp_key)
> >> + pr_info("Using DCP OTP key\n");
> >> +
> >> + ret = test_for_zero_key();
> >> + if (ret) {
> >> + pr_err("Test for zero'ed keys failed: %i\n", ret);
> >
> > I'm not sure whether this should err or warn.
> >
> > What sort of situations can cause the test the fail (e.g.
> > adversary/interposer, bad configuration etc.).
>
> This occurs when the hardware is not in "secure mode". I.e. it’s a bad
> configuration issue.
> Once the board is properly configured, this will never trigger again.
> Do you think a warning is better for this then?
Bad configuration is not unexpected configuration so it cannot possibly
be an error situation as far as Linux is considered. So warning is
appropriate here I'd figure.
BR, Jarkko
Re: [PATCH v6 3/6] KEYS: trusted: Introduce NXP DCP-backed trusted keys
Hi Jarkko,
> On 07.03.2024, at 20:30, Jarkko Sakkinen wrote:
[...]
>> +
>> +static int trusted_dcp_init(void)
>> +{
>> + int ret;
>> +
>> + if (use_otp_key)
>> + pr_info("Using DCP OTP key\n");
>> +
>> + ret = test_for_zero_key();
>> + if (ret) {
>> + pr_err("Test for zero'ed keys failed: %i\n", ret);
>
> I'm not sure whether this should err or warn.
>
> What sort of situations can cause the test the fail (e.g.
> adversary/interposer, bad configuration etc.).
This occurs when the hardware is not in "secure mode". I.e. it’s a bad
configuration issue.
Once the board is properly configured, this will never trigger again.
Do you think a warning is better for this then?
Thanks,
- David
Re: [PATCH v6 3/6] KEYS: trusted: Introduce NXP DCP-backed trusted keys
On Thu Mar 7, 2024 at 5:38 PM EET, David Gstir wrote:
> DCP (Data Co-Processor) is the little brother of NXP's CAAM IP.
> Beside of accelerated crypto operations, it also offers support for
> hardware-bound keys. Using this feature it is possible to implement a blob
> mechanism similar to what CAAM offers. Unlike on CAAM, constructing and
> parsing the blob has to happen in software (i.e. the kernel).
>
> The software-based blob format used by DCP trusted keys encrypts
> the payload using AES-128-GCM with a freshly generated random key and nonce.
> The random key itself is AES-128-ECB encrypted using the DCP unique
> or OTP key.
>
> The DCP trusted key blob format is:
> /*
> * struct dcp_blob_fmt - DCP BLOB format.
> *
> * @fmt_version: Format version, currently being %1
> * @blob_key: Random AES 128 key which is used to encrypt @payload,
> *@blob_key itself is encrypted with OTP or UNIQUE device key in
> *AES-128-ECB mode by DCP.
> * @nonce: Random nonce used for @payload encryption.
> * @payload_len: Length of the plain text @payload.
> * @payload: The payload itself, encrypted using AES-128-GCM and @blob_key,
> * GCM auth tag of size AES_BLOCK_SIZE is attached at the end of it.
> *
> * The total size of a DCP BLOB is sizeof(struct dcp_blob_fmt) + @payload_len
> +
> * AES_BLOCK_SIZE.
> */
> struct dcp_blob_fmt {
> __u8 fmt_version;
> __u8 blob_key[AES_KEYSIZE_128];
> __u8 nonce[AES_KEYSIZE_128];
> __le32 payload_len;
> __u8 payload[];
> } __packed;
>
> By default the unique key is used. It is also possible to use the
> OTP key. While the unique key should be unique it is not documented how
> this key is derived. Therefore selection the OTP key is supported as
> well via the use_otp_key module parameter.
>
> Co-developed-by: Richard Weinberger
> Signed-off-by: Richard Weinberger
> Co-developed-by: David Oberhollenzer
> Signed-off-by: David Oberhollenzer
> Signed-off-by: David Gstir
> ---
> include/keys/trusted_dcp.h| 11 +
> security/keys/trusted-keys/Kconfig| 8 +
> security/keys/trusted-keys/Makefile | 2 +
> security/keys/trusted-keys/trusted_core.c | 6 +-
> security/keys/trusted-keys/trusted_dcp.c | 309 ++
> 5 files changed, 335 insertions(+), 1 deletion(-)
> create mode 100644 include/keys/trusted_dcp.h
> create mode 100644 security/keys/trusted-keys/trusted_dcp.c
>
> diff --git a/include/keys/trusted_dcp.h b/include/keys/trusted_dcp.h
> new file mode 100644
> index ..9aaa42075b40
> --- /dev/null
> +++ b/include/keys/trusted_dcp.h
> @@ -0,0 +1,11 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (C) 2021 sigma star gmbh
> + */
> +
> +#ifndef TRUSTED_DCP_H
> +#define TRUSTED_DCP_H
> +
> +extern struct trusted_key_ops dcp_trusted_key_ops;
> +
> +#endif
> diff --git a/security/keys/trusted-keys/Kconfig
> b/security/keys/trusted-keys/Kconfig
> index 553dc117f385..1fb8aa001995 100644
> --- a/security/keys/trusted-keys/Kconfig
> +++ b/security/keys/trusted-keys/Kconfig
> @@ -39,6 +39,14 @@ config TRUSTED_KEYS_CAAM
> Enable use of NXP's Cryptographic Accelerator and Assurance Module
> (CAAM) as trusted key backend.
>
> +config TRUSTED_KEYS_DCP
> + bool "DCP-based trusted keys"
> + depends on CRYPTO_DEV_MXS_DCP >= TRUSTED_KEYS
> + default y
> + select HAVE_TRUSTED_KEYS
> + help
> + Enable use of NXP's DCP (Data Co-Processor) as trusted key backend.
> +
> if !HAVE_TRUSTED_KEYS
> comment "No trust source selected!"
> endif
> diff --git a/security/keys/trusted-keys/Makefile
> b/security/keys/trusted-keys/Makefile
> index 735aa0bc08ef..f0f3b27f688b 100644
> --- a/security/keys/trusted-keys/Makefile
> +++ b/security/keys/trusted-keys/Makefile
> @@ -14,3 +14,5 @@ trusted-$(CONFIG_TRUSTED_KEYS_TPM) += tpm2key.asn1.o
> trusted-$(CONFIG_TRUSTED_KEYS_TEE) += trusted_tee.o
>
> trusted-$(CONFIG_TRUSTED_KEYS_CAAM) += trusted_caam.o
> +
> +trusted-$(CONFIG_TRUSTED_KEYS_DCP) += trusted_dcp.o
> diff --git a/security/keys/trusted-keys/trusted_core.c
> b/security/keys/trusted-keys/trusted_core.c
> index fee1ab2c734d..5113aeae5628 100644
> --- a/security/keys/trusted-keys/trusted_core.c
> +++ b/security/keys/trusted-keys/trusted_core.c
> @@ -10,6 +10,7 @@
> #include
> #include
> #include
> +#include
> #include
> #include
> #include
> @@ -30,7 +31,7 @@ MODULE_PARM_DESC(rng, "Select trusted key RNG");
>
> static char *trusted_key_source;
> module_param_named(source, trusted_key_source, charp, 0);
> -MODULE_PARM_DESC(source, "Select trusted keys source (tpm, tee or caam)");
> +MODULE_PARM_DESC(source, "Select trusted keys source (tpm, tee, caam or
> dcp)");
>
> static const struct trusted_key_source trusted_key_sources[] = {
> #if defined(CONFIG_TRUSTED_KEYS_TPM)
> @@ -42,6 +43,9 @@ static const struct trusted_key_source
> trusted_key_sources[] = {
> #if
Re: [PATCH v6 3/6] KEYS: trusted: Introduce NXP DCP-backed trusted keys
On Thu Mar 7, 2024 at 5:38 PM EET, David Gstir wrote:> DCP (Data Co-Processor)
is the little brother of NXP's CAAM IP.
> Beside of accelerated crypto operations, it also offers support for
> hardware-bound keys. Using this feature it is possible to implement a blob
> mechanism similar to what CAAM offers. Unlike on CAAM, constructing and
> parsing the blob has to happen in software (i.e. the kernel).
>
> The software-based blob format used by DCP trusted keys encrypts
> the payload using AES-128-GCM with a freshly generated random key and nonce.
> The random key itself is AES-128-ECB encrypted using the DCP unique
> or OTP key.
>
> The DCP trusted key blob format is:
> /*
> * struct dcp_blob_fmt - DCP BLOB format.
> *
> * @fmt_version: Format version, currently being %1
> * @blob_key: Random AES 128 key which is used to encrypt @payload,
> *@blob_key itself is encrypted with OTP or UNIQUE device key in
> *AES-128-ECB mode by DCP.
> * @nonce: Random nonce used for @payload encryption.
> * @payload_len: Length of the plain text @payload.
> * @payload: The payload itself, encrypted using AES-128-GCM and @blob_key,
> * GCM auth tag of size AES_BLOCK_SIZE is attached at the end of it.
> *
> * The total size of a DCP BLOB is sizeof(struct dcp_blob_fmt) + @payload_len
> +
> * AES_BLOCK_SIZE.
> */
> struct dcp_blob_fmt {
> __u8 fmt_version;
> __u8 blob_key[AES_KEYSIZE_128];
> __u8 nonce[AES_KEYSIZE_128];
> __le32 payload_len;
> __u8 payload[];
> } __packed;
>
> By default the unique key is used. It is also possible to use the
> OTP key. While the unique key should be unique it is not documented how
> this key is derived. Therefore selection the OTP key is supported as
> well via the use_otp_key module parameter.
>
> Co-developed-by: Richard Weinberger
> Signed-off-by: Richard Weinberger
> Co-developed-by: David Oberhollenzer
> Signed-off-by: David Oberhollenzer
> Signed-off-by: David Gstir
> ---
> include/keys/trusted_dcp.h| 11 +
> security/keys/trusted-keys/Kconfig| 8 +
> security/keys/trusted-keys/Makefile | 2 +
> security/keys/trusted-keys/trusted_core.c | 6 +-
> security/keys/trusted-keys/trusted_dcp.c | 309 ++
> 5 files changed, 335 insertions(+), 1 deletion(-)
> create mode 100644 include/keys/trusted_dcp.h
> create mode 100644 security/keys/trusted-keys/trusted_dcp.c
>
> diff --git a/include/keys/trusted_dcp.h b/include/keys/trusted_dcp.h
> new file mode 100644
> index ..9aaa42075b40
> --- /dev/null
> +++ b/include/keys/trusted_dcp.h
> @@ -0,0 +1,11 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (C) 2021 sigma star gmbh
> + */
> +
> +#ifndef TRUSTED_DCP_H
> +#define TRUSTED_DCP_H
> +
> +extern struct trusted_key_ops dcp_trusted_key_ops;
> +
> +#endif
> diff --git a/security/keys/trusted-keys/Kconfig
> b/security/keys/trusted-keys/Kconfig
> index 553dc117f385..1fb8aa001995 100644
> --- a/security/keys/trusted-keys/Kconfig
> +++ b/security/keys/trusted-keys/Kconfig
> @@ -39,6 +39,14 @@ config TRUSTED_KEYS_CAAM
> Enable use of NXP's Cryptographic Accelerator and Assurance Module
> (CAAM) as trusted key backend.
>
> +config TRUSTED_KEYS_DCP
> + bool "DCP-based trusted keys"
> + depends on CRYPTO_DEV_MXS_DCP >= TRUSTED_KEYS
> + default y
> + select HAVE_TRUSTED_KEYS
> + help
> + Enable use of NXP's DCP (Data Co-Processor) as trusted key backend.
> +
> if !HAVE_TRUSTED_KEYS
> comment "No trust source selected!"
> endif
> diff --git a/security/keys/trusted-keys/Makefile
> b/security/keys/trusted-keys/Makefile
> index 735aa0bc08ef..f0f3b27f688b 100644
> --- a/security/keys/trusted-keys/Makefile
> +++ b/security/keys/trusted-keys/Makefile
> @@ -14,3 +14,5 @@ trusted-$(CONFIG_TRUSTED_KEYS_TPM) += tpm2key.asn1.o
> trusted-$(CONFIG_TRUSTED_KEYS_TEE) += trusted_tee.o
>
> trusted-$(CONFIG_TRUSTED_KEYS_CAAM) += trusted_caam.o
> +
> +trusted-$(CONFIG_TRUSTED_KEYS_DCP) += trusted_dcp.o
> diff --git a/security/keys/trusted-keys/trusted_core.c
> b/security/keys/trusted-keys/trusted_core.c
> index fee1ab2c734d..5113aeae5628 100644
> --- a/security/keys/trusted-keys/trusted_core.c
> +++ b/security/keys/trusted-keys/trusted_core.c
> @@ -10,6 +10,7 @@
> #include
> #include
> #include
> +#include
> #include
> #include
> #include
> @@ -30,7 +31,7 @@ MODULE_PARM_DESC(rng, "Select trusted key RNG");
>
> static char *trusted_key_source;
> module_param_named(source, trusted_key_source, charp, 0);
> -MODULE_PARM_DESC(source, "Select trusted keys source (tpm, tee or caam)");
> +MODULE_PARM_DESC(source, "Select trusted keys source (tpm, tee, caam or
> dcp)");
>
> static const struct trusted_key_source trusted_key_sources[] = {
> #if defined(CONFIG_TRUSTED_KEYS_TPM)
> @@ -42,6 +43,9 @@ static const struct trusted_key_source
> trusted_key_sources[] = {
> #if
