2021-06-22 12:39:50

by Ahmad Fatoum

[permalink] [raw]
Subject: [PATCH v2 0/6] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys

The first three patches are new and are applicable regardless of this
series, but the rest won't apply cleanly without them. I chose to
include them this time, but I can split them up for v3 if that's
preferred.

v1 -> v2:
- Added new commit to make trusted key Kconfig option independent
of TPM and added new Kconfig file and symbols for trusted keys
- Add new commit for importing existing key material (Jan)
- Allow users to force use of kernel RNG (Jarkko)
- Enforce maximum keymod size (Horia)
- Use append_seq_(in|out)_ptr_intlen instead of append_seq_(in|out)_ptr
(Horia)
- Make blobifier handle private to CAAM glue code file (Horia)
- Extend trusted keys documentation for CAAM
- Rebased on v5.12-rc7 and updated cover letter:

The Cryptographic Acceleration and Assurance Module (CAAM) is an IP core
built into many newer i.MX and QorIQ SoCs by NXP.

Its blob mechanism can AES encrypt/decrypt user data using a unique
never-disclosed device-specific key.

There has been multiple discussions on how to represent this within the kernel:

The Cryptographic Acceleration and Assurance Module (CAAM) is an IP core
built into many newer i.MX and QorIQ SoCs by NXP.

Its blob mechanism can AES encrypt/decrypt user data using a unique
never-disclosed device-specific key. There has been multiple
discussions on how to represent this within the kernel:

- [RFC] crypto: caam - add red blobifier
Steffen implemented[1] a PoC sysfs driver to start a discussion on how to
best integrate the blob mechanism.
Mimi suggested that it could be used to implement trusted keys.
Trusted keys back then were a TPM-only feature.

- security/keys/secure_key: Adds the secure key support based on CAAM.
Udit added[2] a new "secure" key type with the CAAM as backend. The key
material stays within the kernel only.
Mimi and James agreed that this needs a generic interface, not specific
to CAAM. Mimi suggested trusted keys. Jan noted that this could serve as
basis for TEE-backed keys.

- [RFC] drivers: crypto: caam: key: Add caam_tk key type
Franck added[3] a new "caam_tk" key type based on Udit's work. This time
it uses CAAM "black blobs" instead of "red blobs", so key material stays
within the CAAM and isn't exposed to kernel in plaintext.
James voiced the opinion that there should be just one user-facing generic
wrap/unwrap key type with multiple possible handlers.
David suggested trusted keys.

- Introduce TEE based Trusted Keys support
Sumit reworked[4] trusted keys to support multiple possible backends with
one chosen at boot time and added a new TEE backend along with TPM.
This now sits in Jarkko's master branch to be sent out for v5.13

This patch series builds on top of Sumit's rework to have the CAAM as yet another
trusted key backend.

The CAAM bits are based on Steffen's initial patch from 2015. His work had been
used in the field for some years now, so I preferred not to deviate too much from it.

This series has been tested with dmcrypt[5] on an i.MX6DL.

Looking forward to your feedback.

Cheers,
Ahmad

[1]: https://lore.kernel.org/linux-crypto/[email protected]/
[2]: https://lore.kernel.org/linux-integrity/[email protected]/
[3]: https://lore.kernel.org/lkml/[email protected]/
[4]: https://lore.kernel.org/lkml/[email protected]/
[5]: https://lore.kernel.org/linux-integrity/[email protected]/

---
To: Jarkko Sakkinen <[email protected]>
To: "Horia Geantă" <[email protected]>
To: Mimi Zohar <[email protected]>
To: Aymen Sghaier <[email protected]>
To: Herbert Xu <[email protected]>
To: "David S. Miller" <[email protected]>
To: James Bottomley <[email protected]>
Cc: David Howells <[email protected]>
Cc: James Morris <[email protected]>
Cc: "Serge E. Hallyn" <[email protected]>
Cc: Steffen Trumtrar <[email protected]>
Cc: Udit Agarwal <[email protected]>
Cc: Jan Luebbe <[email protected]>
Cc: David Gstir <[email protected]>
Cc: Eric Biggers <[email protected]>
Cc: Richard Weinberger <[email protected]>
Cc: Franck LENORMAND <[email protected]>
Cc: Sumit Garg <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]

Ahmad Fatoum (6):
KEYS: trusted: allow use of TEE as backend without TCG_TPM support
KEYS: trusted: Allow import from existing key material for development
KEYS: trusted: allow users to use kernel RNG for key material
KEYS: trusted: allow trust sources to use kernel RNG for key material
crypto: caam - add in-kernel interface for blob generator
KEYS: trusted: Introduce support for NXP CAAM-based trusted keys

Documentation/admin-guide/kernel-parameters.txt | 8 +-
Documentation/security/keys/trusted-encrypted.rst | 74 ++++-
drivers/crypto/caam/Kconfig | 3 +-
drivers/crypto/caam/Makefile | 1 +-
drivers/crypto/caam/blob_gen.c | 230 +++++++++++++++-
include/keys/trusted-type.h | 2 +-
include/keys/trusted_caam.h | 11 +-
include/soc/fsl/caam-blob.h | 56 ++++-
security/keys/Kconfig | 14 +-
security/keys/trusted-keys/Kconfig | 49 +++-
security/keys/trusted-keys/Makefile | 10 +-
security/keys/trusted-keys/trusted_caam.c | 74 +++++-
security/keys/trusted-keys/trusted_core.c | 48 ++-
13 files changed, 554 insertions(+), 26 deletions(-)
create mode 100644 drivers/crypto/caam/blob_gen.c
create mode 100644 include/keys/trusted_caam.h
create mode 100644 include/soc/fsl/caam-blob.h
create mode 100644 security/keys/trusted-keys/Kconfig
create mode 100644 security/keys/trusted-keys/trusted_caam.c

base-commit: 13311e74253fe64329390df80bed3f07314ddd61
--
git-series 0.9.1


2021-06-22 12:40:03

by Ahmad Fatoum

[permalink] [raw]
Subject: [PATCH v2 6/6] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys

The Cryptographic Acceleration and Assurance Module (CAAM) is an IP core
built into many newer i.MX and QorIQ SoCs by NXP.

The CAAM does crypto acceleration, hardware number generation and
has a blob mechanism for encapsulation/decapsulation of sensitive material.

This blob mechanism depends on a device specific random 256-bit One Time
Programmable Master Key that is fused in each SoC at manufacturing
time. This key is unreadable and can only be used by the CAAM for AES
encryption/decryption of user data.

This makes it a suitable backend (source) for kernel trusted keys.

Previous commits generalized trusted keys to support multiple backends
and added an API to access the CAAM blob mechanism. Based on these,
provide the necessary glue to use the CAAM for trusted keys.

Signed-off-by: Ahmad Fatoum <[email protected]>
---
To: Jonathan Corbet <[email protected]>
To: David Howells <[email protected]>
To: Jarkko Sakkinen <[email protected]>
To: James Bottomley <[email protected]>
To: Mimi Zohar <[email protected]>
Cc: James Morris <[email protected]>
Cc: "Serge E. Hallyn" <[email protected]>
Cc: "Horia Geantă" <[email protected]>
Cc: Aymen Sghaier <[email protected]>
Cc: Herbert Xu <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Udit Agarwal <[email protected]>
Cc: Eric Biggers <[email protected]>
Cc: Jan Luebbe <[email protected]>
Cc: David Gstir <[email protected]>
Cc: Richard Weinberger <[email protected]>
Cc: Franck LENORMAND <[email protected]>
Cc: Sumit Garg <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
---
Documentation/admin-guide/kernel-parameters.txt | 1 +-
Documentation/security/keys/trusted-encrypted.rst | 42 ++++++++-
include/keys/trusted_caam.h | 11 ++-
security/keys/trusted-keys/Kconfig | 11 +-
security/keys/trusted-keys/Makefile | 2 +-
security/keys/trusted-keys/trusted_caam.c | 74 ++++++++++++++++-
security/keys/trusted-keys/trusted_core.c | 6 +-
7 files changed, 143 insertions(+), 4 deletions(-)
create mode 100644 include/keys/trusted_caam.h
create mode 100644 security/keys/trusted-keys/trusted_caam.c

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index f8bdc898c354..4a95369c2bc7 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5639,6 +5639,7 @@
sources:
- "tpm"
- "tee"
+ - "caam"
If not specified then it defaults to iterating through
the trust source list starting with TPM and assigns the
first trust source as a backend which is initialized
diff --git a/Documentation/security/keys/trusted-encrypted.rst b/Documentation/security/keys/trusted-encrypted.rst
index 3fb5562ee937..3461746b1fbd 100644
--- a/Documentation/security/keys/trusted-encrypted.rst
+++ b/Documentation/security/keys/trusted-encrypted.rst
@@ -35,6 +35,13 @@ safe.
Rooted to Hardware Unique Key (HUK) which is generally burnt in on-chip
fuses and is accessible to TEE only.

+ (3) CAAM (Cryptographic Acceleration and Assurance Module: IP on NXP SoCs)
+
+ When High Assurance Boot (HAB) is enabled and the CAAM is in secure
+ mode, trust is rooted to the OTPMK, a never-disclosed 256-bit key
+ randomly generated and fused into each SoC at manufacturing time.
+ Otherwise, a common fixed test key is used instead.
+
* Execution isolation

(1) TPM
@@ -46,6 +53,10 @@ safe.
Customizable set of operations running in isolated execution
environment verified via Secure/Trusted boot process.

+ (3) CAAM
+
+ Fixed set of operations running in isolated execution environment.
+
* Optional binding to platform integrity state

(1) TPM
@@ -63,6 +74,11 @@ safe.
Relies on Secure/Trusted boot process for platform integrity. It can
be extended with TEE based measured boot process.

+ (3) CAAM
+
+ Relies on the High Assurance Boot (HAB) mechanism of NXP SoCs
+ for platform integrity.
+
* Interfaces and APIs

(1) TPM
@@ -74,10 +90,13 @@ safe.
TEEs have well-documented, standardized client interface and APIs. For
more details refer to ``Documentation/staging/tee.rst``.

+ (3) CAAM
+
+ Interface is specific to silicon vendor.

* Threat model

- The strength and appropriateness of a particular TPM or TEE for a given
+ The strength and appropriateness of a particular trust source for a given
purpose must be assessed when using them to protect security-relevant data.


@@ -104,8 +123,14 @@ selected trust source:
from platform specific hardware RNG or a software based Fortuna CSPRNG
which can be seeded via multiple entropy sources.

+ * CAAM: Kernel RNG
+
+ The normal kernel random number generator is used. To seed it from the
+ CAAM HWRNG, enable CRYPTO_DEV_FSL_CAAM_RNG_API and ensure the device
+ can be probed.
+
Optionally, users may specify ``trusted.kernel_rng=1`` on the kernel
-command-line to override the used RNG with the kernel's random number pool.
+command-line to force use of the kernel's random number pool.

Encrypted Keys
--------------
@@ -192,6 +217,19 @@ Usage::
specific to TEE device implementation. The key length for new keys is always
in bytes. Trusted Keys can be 32 - 128 bytes (256 - 1024 bits).

+Trusted Keys usage: CAAM
+------------------------
+
+Usage::
+
+ keyctl add trusted name "new keylen" ring
+ keyctl add trusted name "load hex_blob" ring
+ keyctl print keyid
+
+"keyctl print" returns an ASCII hex copy of the sealed key, which is in format
+specific to CAAM device implementation. The key length for new keys is always
+in bytes. Trusted Keys can be 32 - 128 bytes (256 - 1024 bits).
+
Trusted Keys: import plain-text key for development
---------------------------------------------------

diff --git a/include/keys/trusted_caam.h b/include/keys/trusted_caam.h
new file mode 100644
index 000000000000..2fba0996b0b0
--- /dev/null
+++ b/include/keys/trusted_caam.h
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2021 Pengutronix, Ahmad Fatoum <[email protected]>
+ */
+
+#ifndef __CAAM_TRUSTED_KEY_H
+#define __CAAM_TRUSTED_KEY_H
+
+extern struct trusted_key_ops caam_trusted_key_ops;
+
+#endif
diff --git a/security/keys/trusted-keys/Kconfig b/security/keys/trusted-keys/Kconfig
index 8bd69b252bf9..641bed8923ec 100644
--- a/security/keys/trusted-keys/Kconfig
+++ b/security/keys/trusted-keys/Kconfig
@@ -20,7 +20,16 @@ config TRUSTED_KEYS_TEE
Enable use of the Trusted Execution Environment (TEE) as trusted
key backend.

-if !TRUSTED_KEYS_TPM && !TRUSTED_KEYS_TEE
+config TRUSTED_KEYS_CAAM
+ bool "CAAM-based trusted keys"
+ depends on CRYPTO_DEV_FSL_CAAM_JR >= TRUSTED_KEYS
+ select CRYPTO_DEV_FSL_CAAM_BLOB_GEN
+ default y
+ help
+ Enable use of NXP's Cryptographic Accelerator and Assurance Module
+ (CAAM) as trusted key backend.
+
+if !TRUSTED_KEYS_TPM && !TRUSTED_KEYS_TEE && !TRUSTED_KEYS_CAAM
comment "No trust source selected!"
endif

diff --git a/security/keys/trusted-keys/Makefile b/security/keys/trusted-keys/Makefile
index 96fc6c377398..5788bc07a2ab 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-$(CONFIG_TEE) += trusted_tee.o
+
+trusted-$(CONFIG_TRUSTED_KEYS_CAAM) += trusted_caam.o
diff --git a/security/keys/trusted-keys/trusted_caam.c b/security/keys/trusted-keys/trusted_caam.c
new file mode 100644
index 000000000000..01adfd18adda
--- /dev/null
+++ b/security/keys/trusted-keys/trusted_caam.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2021 Pengutronix, Ahmad Fatoum <[email protected]>
+ */
+
+#include <keys/trusted_caam.h>
+#include <keys/trusted-type.h>
+#include <linux/build_bug.h>
+#include <linux/key-type.h>
+#include <soc/fsl/caam-blob.h>
+
+static struct caam_blob_priv *blobifier;
+
+#define KEYMOD "kernel:trusted"
+
+static_assert(MAX_KEY_SIZE + CAAM_BLOB_OVERHEAD <= CAAM_BLOB_MAX_LEN);
+static_assert(MAX_BLOB_SIZE <= CAAM_BLOB_MAX_LEN);
+
+static int trusted_caam_seal(struct trusted_key_payload *p, char *datablob)
+{
+ int length = p->key_len + CAAM_BLOB_OVERHEAD;
+ int ret;
+
+ ret = caam_encap_blob(blobifier, KEYMOD, p->key, p->blob, length);
+ if (ret)
+ return ret;
+
+ p->blob_len = length;
+ return 0;
+}
+
+static int trusted_caam_unseal(struct trusted_key_payload *p, char *datablob)
+{
+ int length = p->blob_len;
+ int ret;
+
+ ret = caam_decap_blob(blobifier, KEYMOD, p->blob, p->key, length);
+ if (ret)
+ return ret;
+
+ p->key_len = length - CAAM_BLOB_OVERHEAD;
+ return 0;
+}
+
+static int trusted_caam_init(void)
+{
+ int ret;
+
+ blobifier = caam_blob_gen_init();
+ if (IS_ERR(blobifier)) {
+ pr_err("Job Ring Device allocation for transform failed\n");
+ return PTR_ERR(blobifier);
+ }
+
+ ret = register_key_type(&key_type_trusted);
+ if (ret)
+ caam_blob_gen_exit(blobifier);
+
+ return ret;
+}
+
+static void trusted_caam_exit(void)
+{
+ unregister_key_type(&key_type_trusted);
+ caam_blob_gen_exit(blobifier);
+}
+
+struct trusted_key_ops caam_trusted_key_ops = {
+ .migratable = 0, /* non-migratable */
+ .init = trusted_caam_init,
+ .seal = trusted_caam_seal,
+ .unseal = trusted_caam_unseal,
+ .exit = trusted_caam_exit,
+};
diff --git a/security/keys/trusted-keys/trusted_core.c b/security/keys/trusted-keys/trusted_core.c
index 8d829e6866ca..21997a5debde 100644
--- a/security/keys/trusted-keys/trusted_core.c
+++ b/security/keys/trusted-keys/trusted_core.c
@@ -9,6 +9,7 @@
#include <keys/user-type.h>
#include <keys/trusted-type.h>
#include <keys/trusted_tee.h>
+#include <keys/trusted_caam.h>
#include <keys/trusted_tpm.h>
#include <linux/capability.h>
#include <linux/err.h>
@@ -29,7 +30,7 @@ MODULE_PARM_DESC(kernel_rng, "Generate key material from kernel RNG");

static char *trusted_key_source;
module_param_named(source, trusted_key_source, charp, 0);
-MODULE_PARM_DESC(source, "Select trusted keys source (tpm or tee)");
+MODULE_PARM_DESC(source, "Select trusted keys source (tpm, tee or caam)");

static const struct trusted_key_source trusted_key_sources[] = {
#if defined(CONFIG_TRUSTED_KEYS_TPM)
@@ -38,6 +39,9 @@ static const struct trusted_key_source trusted_key_sources[] = {
#if defined(CONFIG_TRUSTED_KEYS_TEE)
{ "tee", &trusted_key_tee_ops },
#endif
+#if defined(CONFIG_TRUSTED_KEYS_CAAM)
+ { "caam", &caam_trusted_key_ops },
+#endif
};

DEFINE_STATIC_CALL_NULL(trusted_key_init, *trusted_key_sources[0].ops->init);
--
git-series 0.9.1

2021-07-01 20:59:02

by Richard Weinberger

[permalink] [raw]
Subject: Re: [PATCH v2 6/6] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys

Ahmad,

----- Ursprüngliche Mail -----
> Von: "Ahmad Fatoum" <[email protected]>
> +static struct caam_blob_priv *blobifier;
> +
> +#define KEYMOD "kernel:trusted"

I'm still think that hard coding the key modifier is not wise.
As I said[0], there are folks out there that want to provide their own modifier,
so it is not only about being binary compatible with other CAAM blob patches in the wild.

I'll happily implement that feature after your patches got merged but IMHO we should first agree on an interface.
How about allowing another optional parameter to Opt_new and Opt_load and having a key modifier
per struct trusted_key_payload instance?

Thanks,
//richard

[0]
https://patchwork.kernel.org/project/linux-crypto/patch/319e558e[email protected]pengutronix.de/#24085397

2021-07-02 08:01:44

by Ahmad Fatoum

[permalink] [raw]
Subject: Re: [PATCH v2 6/6] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys

Hello Richard,

On 01.07.21 22:42, Richard Weinberger wrote:
> Ahmad,
>
> ----- Ursprüngliche Mail -----
>> Von: "Ahmad Fatoum" <[email protected]>
>> +static struct caam_blob_priv *blobifier;
>> +
>> +#define KEYMOD "kernel:trusted"
>
> I'm still think that hard coding the key modifier is not wise.
> As I said[0], there are folks out there that want to provide their own modifier,
> so it is not only about being binary compatible with other CAAM blob patches in the wild.

I don't think the characterization as a salt is accurate. AFAIU it's more
of a namespace, so blobs being loaded are "type-checked" against the modifier.

> I'll happily implement that feature after your patches got merged but IMHO we should first agree on an interface.
> How about allowing another optional parameter to Opt_new and Opt_load

Sound good to me. pcrlock for TPM trusted keys has the same interface.

I'd prefer the new option to accept strings, not hex though.


> and having a key modifier per struct trusted_key_payload instance?

Ye, possibly a void *backend_data, which other trust sources could leverage
as well. But that should be separate discussion.


Cheers,
Ahmad

>
> Thanks,
> //richard
>
> [0]
> https://patchwork.kernel.org/project/linux-crypto/patch/319e558e[email protected]pengutronix.de/#24085397
>
>

--
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 |

2021-07-02 10:54:12

by Richard Weinberger

[permalink] [raw]
Subject: Re: [PATCH v2 6/6] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys

Ahmad,

----- Ursprüngliche Mail -----
> Von: "Ahmad Fatoum" <[email protected]>
>> I'm still think that hard coding the key modifier is not wise.
>> As I said[0], there are folks out there that want to provide their own modifier,
>> so it is not only about being binary compatible with other CAAM blob patches in
>> the wild.
>
> I don't think the characterization as a salt is accurate. AFAIU it's more
> of a namespace, so blobs being loaded are "type-checked" against the modifier.

Well, the CAAM programmer's reference manual states that the blob key is a 128 bit modifier
and has two purposes:
1. It can be used as tag to provide separation between blobs to detect accidental replacement of blobs.
2. But it can also be treated as secret to provide additional protection. Because the blob encryption
key derivation includes the key modifier.

While you have case 1 in mind, I care about case 2. :-)

>> I'll happily implement that feature after your patches got merged but IMHO we
>> should first agree on an interface.
>> How about allowing another optional parameter to Opt_new and Opt_load
>
> Sound good to me. pcrlock for TPM trusted keys has the same interface.
>
> I'd prefer the new option to accept strings, not hex though.

Both is possible. If the string starts with "0x" it needs to be decoded to a
128 bit key. Otherwise it has to be a up to 16 byte string.

Thanks,
//richard

2021-07-02 12:35:51

by Ahmad Fatoum

[permalink] [raw]
Subject: Re: [PATCH v2 6/6] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys

On 02.07.21 12:53, Richard Weinberger wrote:
> Ahmad,
>
> ----- Ursprüngliche Mail -----
>> Von: "Ahmad Fatoum" <[email protected]>
>>> I'm still think that hard coding the key modifier is not wise.
>>> As I said[0], there are folks out there that want to provide their own modifier,
>>> so it is not only about being binary compatible with other CAAM blob patches in
>>> the wild.
>>
>> I don't think the characterization as a salt is accurate. AFAIU it's more
>> of a namespace, so blobs being loaded are "type-checked" against the modifier.
>
> Well, the CAAM programmer's reference manual states that the blob key is a 128 bit modifier
> and has two purposes:
> 1. It can be used as tag to provide separation between blobs to detect accidental replacement of blobs.
> 2. But it can also be treated as secret to provide additional protection. Because the blob encryption
> key derivation includes the key modifier.
>
> While you have case 1 in mind, I care about case 2. :-)

Ah, using the key modifier as a passphrase didn't occur to me.

>>> I'll happily implement that feature after your patches got merged but IMHO we
>>> should first agree on an interface.
>>> How about allowing another optional parameter to Opt_new and Opt_load
>>
>> Sound good to me. pcrlock for TPM trusted keys has the same interface.
>>
>> I'd prefer the new option to accept strings, not hex though.
>
> Both is possible. If the string starts with "0x" it needs to be decoded to a
> 128 bit key. Otherwise it has to be a up to 16 byte string.

Fine by me. Looking forward to your patches. :-)


Cheers,
Ahmad

>
> Thanks,
> //richard
>

--
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 |

2021-07-14 06:37:55

by Ahmad Fatoum

[permalink] [raw]
Subject: Re: [PATCH v2 0/6] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys

Dear Trusted Keys and CAAM maintainers/reviewers,

On 22.06.21 14:37, Ahmad Fatoum wrote:
> The first three patches are new and are applicable regardless of this
> series, but the rest won't apply cleanly without them. I chose to
> include them this time, but I can split them up for v3 if that's
> preferred.
>
> v1 -> v2:
> - Added new commit to make trusted key Kconfig option independent
> of TPM and added new Kconfig file and symbols for trusted keys
> - Add new commit for importing existing key material (Jan)
> - Allow users to force use of kernel RNG (Jarkko)
> - Enforce maximum keymod size (Horia)
> - Use append_seq_(in|out)_ptr_intlen instead of append_seq_(in|out)_ptr
> (Horia)
> - Make blobifier handle private to CAAM glue code file (Horia)
> - Extend trusted keys documentation for CAAM
> - Rebased on v5.12-rc7 and updated cover letter:
>
> The Cryptographic Acceleration and Assurance Module (CAAM) is an IP core
> built into many newer i.MX and QorIQ SoCs by NXP.
>
> Its blob mechanism can AES encrypt/decrypt user data using a unique
> never-disclosed device-specific key.
>
> There has been multiple discussions on how to represent this within the kernel:
>
> The Cryptographic Acceleration and Assurance Module (CAAM) is an IP core
> built into many newer i.MX and QorIQ SoCs by NXP.
>
> Its blob mechanism can AES encrypt/decrypt user data using a unique
> never-disclosed device-specific key. There has been multiple
> discussions on how to represent this within the kernel:
>
> - [RFC] crypto: caam - add red blobifier
> Steffen implemented[1] a PoC sysfs driver to start a discussion on how to
> best integrate the blob mechanism.
> Mimi suggested that it could be used to implement trusted keys.
> Trusted keys back then were a TPM-only feature.
>
> - security/keys/secure_key: Adds the secure key support based on CAAM.
> Udit added[2] a new "secure" key type with the CAAM as backend. The key
> material stays within the kernel only.
> Mimi and James agreed that this needs a generic interface, not specific
> to CAAM. Mimi suggested trusted keys. Jan noted that this could serve as
> basis for TEE-backed keys.
>
> - [RFC] drivers: crypto: caam: key: Add caam_tk key type
> Franck added[3] a new "caam_tk" key type based on Udit's work. This time
> it uses CAAM "black blobs" instead of "red blobs", so key material stays
> within the CAAM and isn't exposed to kernel in plaintext.
> James voiced the opinion that there should be just one user-facing generic
> wrap/unwrap key type with multiple possible handlers.
> David suggested trusted keys.
>
> - Introduce TEE based Trusted Keys support
> Sumit reworked[4] trusted keys to support multiple possible backends with
> one chosen at boot time and added a new TEE backend along with TPM.
> This now sits in Jarkko's master branch to be sent out for v5.13
>
> This patch series builds on top of Sumit's rework to have the CAAM as yet another
> trusted key backend.
>
> The CAAM bits are based on Steffen's initial patch from 2015. His work had been
> used in the field for some years now, so I preferred not to deviate too much from it.
>
> This series has been tested with dmcrypt[5] on an i.MX6DL.
>
> Looking forward to your feedback.

Gentle Ping.

> Cheers,
> Ahmad
>
> [1]: https://lore.kernel.org/linux-crypto/[email protected]/
> [2]: https://lore.kernel.org/linux-integrity/[email protected]/
> [3]: https://lore.kernel.org/lkml/[email protected]/
> [4]: https://lore.kernel.org/lkml/[email protected]/
> [5]: https://lore.kernel.org/linux-integrity/[email protected]/
>
> ---
> To: Jarkko Sakkinen <[email protected]>
> To: "Horia Geantă" <[email protected]>
> To: Mimi Zohar <[email protected]>
> To: Aymen Sghaier <[email protected]>
> To: Herbert Xu <[email protected]>
> To: "David S. Miller" <[email protected]>
> To: James Bottomley <[email protected]>
> Cc: David Howells <[email protected]>
> Cc: James Morris <[email protected]>
> Cc: "Serge E. Hallyn" <[email protected]>
> Cc: Steffen Trumtrar <[email protected]>
> Cc: Udit Agarwal <[email protected]>
> Cc: Jan Luebbe <[email protected]>
> Cc: David Gstir <[email protected]>
> Cc: Eric Biggers <[email protected]>
> Cc: Richard Weinberger <[email protected]>
> Cc: Franck LENORMAND <[email protected]>
> Cc: Sumit Garg <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
>
> Ahmad Fatoum (6):
> KEYS: trusted: allow use of TEE as backend without TCG_TPM support
> KEYS: trusted: Allow import from existing key material for development
> KEYS: trusted: allow users to use kernel RNG for key material
> KEYS: trusted: allow trust sources to use kernel RNG for key material
> crypto: caam - add in-kernel interface for blob generator
> KEYS: trusted: Introduce support for NXP CAAM-based trusted keys
>
> Documentation/admin-guide/kernel-parameters.txt | 8 +-
> Documentation/security/keys/trusted-encrypted.rst | 74 ++++-
> drivers/crypto/caam/Kconfig | 3 +-
> drivers/crypto/caam/Makefile | 1 +-
> drivers/crypto/caam/blob_gen.c | 230 +++++++++++++++-
> include/keys/trusted-type.h | 2 +-
> include/keys/trusted_caam.h | 11 +-
> include/soc/fsl/caam-blob.h | 56 ++++-
> security/keys/Kconfig | 14 +-
> security/keys/trusted-keys/Kconfig | 49 +++-
> security/keys/trusted-keys/Makefile | 10 +-
> security/keys/trusted-keys/trusted_caam.c | 74 +++++-
> security/keys/trusted-keys/trusted_core.c | 48 ++-
> 13 files changed, 554 insertions(+), 26 deletions(-)
> create mode 100644 drivers/crypto/caam/blob_gen.c
> create mode 100644 include/keys/trusted_caam.h
> create mode 100644 include/soc/fsl/caam-blob.h
> create mode 100644 security/keys/trusted-keys/Kconfig
> create mode 100644 security/keys/trusted-keys/trusted_caam.c
>
> base-commit: 13311e74253fe64329390df80bed3f07314ddd61
>


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31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
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2021-07-20 19:22:38

by Richard Weinberger

[permalink] [raw]
Subject: Re: [PATCH v2 6/6] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys

On Fri, Jul 2, 2021 at 2:37 PM Ahmad Fatoum <[email protected]> wrote:
> > Both is possible. If the string starts with "0x" it needs to be decoded to a
> > 128 bit key. Otherwise it has to be a up to 16 byte string.
>
> Fine by me. Looking forward to your patches. :-)

I'm not sure how to proceed. Should I base my changes on this series
or do you plan to send an updated
version soon?
Maybe it makes also sense to base my DCP patch set on yours.

Trusted Keys maintainers, what do you prefer?

--
Thanks,
//richard

2021-07-21 17:04:14

by Ahmad Fatoum

[permalink] [raw]
Subject: Re: [PATCH v2 6/6] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys

Hi,

On 20.07.21 21:19, Richard Weinberger wrote:
> On Fri, Jul 2, 2021 at 2:37 PM Ahmad Fatoum <[email protected]> wrote:
>>> Both is possible. If the string starts with "0x" it needs to be decoded to a
>>> 128 bit key. Otherwise it has to be a up to 16 byte string.
>>
>> Fine by me. Looking forward to your patches. :-)
>
> I'm not sure how to proceed. Should I base my changes on this series
> or do you plan to send an updated
> version soon?
> Maybe it makes also sense to base my DCP patch set on yours.
>
> Trusted Keys maintainers, what do you prefer?

I sent out v3 despite the name (of course forgot that git-send-email -vX is silently
dropped when sending patch files directly..):

https://lore.kernel.org/linux-integrity/cover.9fc9298f[email protected]pengutronix.de/T/#t

I'd advise you base your changes on the first two patches there as well as the Kconfig fix/enhancement
I sent out separately:
https://lore.kernel.org/linux-integrity/[email protected]/T/#u

Those are relevant for you as well and I assume they should be good to be merged even if the
CAAM series turns out to need some more love.

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 |