Add support for TEE based trusted keys where TEE provides the functionality
to seal and unseal trusted keys using hardware unique key. Also, this is
an alternative in case platform doesn't possess a TPM device.
This patch-set has been tested with OP-TEE based early TA which can be
found here [1].
[1] https://github.com/OP-TEE/optee_os/pull/3838
Changes in v4:
1. Pushed independent TEE features separately:
- Part of recent TEE PR: https://lkml.org/lkml/2020/5/4/1062
2. Updated trusted-encrypted doc with TEE as a new trust source.
3. Rebased onto latest tpmdd/master.
Changes in v3:
1. Update patch #2 to support registration of multiple kernel pages.
2. Incoporate dependency patch #4 in this patch-set:
https://patchwork.kernel.org/patch/11091435/
Changes in v2:
1. Add reviewed-by tags for patch #1 and #2.
2. Incorporate comments from Jens for patch #3.
3. Switch to use generic trusted keys framework.
Sumit Garg (4):
KEYS: trusted: Add generic trusted keys framework
KEYS: trusted: Introduce TEE based Trusted Keys
doc: trusted-encrypted: updates with TEE as a new trust source
MAINTAINERS: Add entry for TEE based Trusted Keys
Documentation/security/keys/trusted-encrypted.rst | 203 ++++++++++---
MAINTAINERS | 8 +
include/keys/trusted-type.h | 48 ++++
include/keys/trusted_tee.h | 66 +++++
include/keys/trusted_tpm.h | 15 -
security/keys/Kconfig | 3 +
security/keys/trusted-keys/Makefile | 2 +
security/keys/trusted-keys/trusted_common.c | 336 ++++++++++++++++++++++
security/keys/trusted-keys/trusted_tee.c | 282 ++++++++++++++++++
security/keys/trusted-keys/trusted_tpm1.c | 335 ++++-----------------
10 files changed, 974 insertions(+), 324 deletions(-)
create mode 100644 include/keys/trusted_tee.h
create mode 100644 security/keys/trusted-keys/trusted_common.c
create mode 100644 security/keys/trusted-keys/trusted_tee.c
--
2.7.4
Add support for TEE based trusted keys where TEE provides the functionality
to seal and unseal trusted keys using hardware unique key.
Refer to Documentation/tee.txt for detailed information about TEE.
Signed-off-by: Sumit Garg <[email protected]>
---
include/keys/trusted-type.h | 3 +
include/keys/trusted_tee.h | 66 +++++++
security/keys/Kconfig | 3 +
security/keys/trusted-keys/Makefile | 1 +
security/keys/trusted-keys/trusted_common.c | 3 +
security/keys/trusted-keys/trusted_tee.c | 282 ++++++++++++++++++++++++++++
6 files changed, 358 insertions(+)
create mode 100644 include/keys/trusted_tee.h
create mode 100644 security/keys/trusted-keys/trusted_tee.c
diff --git a/include/keys/trusted-type.h b/include/keys/trusted-type.h
index 5559010..e0df5df 100644
--- a/include/keys/trusted-type.h
+++ b/include/keys/trusted-type.h
@@ -67,6 +67,9 @@ extern struct key_type key_type_trusted;
#if defined(CONFIG_TCG_TPM)
extern struct trusted_key_ops tpm_trusted_key_ops;
#endif
+#if defined(CONFIG_TEE)
+extern struct trusted_key_ops tee_trusted_key_ops;
+#endif
#define TRUSTED_DEBUG 0
diff --git a/include/keys/trusted_tee.h b/include/keys/trusted_tee.h
new file mode 100644
index 0000000..ab58ffd
--- /dev/null
+++ b/include/keys/trusted_tee.h
@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2019 Linaro Ltd.
+ *
+ * Author:
+ * Sumit Garg <[email protected]>
+ */
+
+#ifndef __TEE_TRUSTED_KEY_H
+#define __TEE_TRUSTED_KEY_H
+
+#include <linux/tee_drv.h>
+
+#define DRIVER_NAME "tee-trusted-key"
+
+/*
+ * Get random data for symmetric key
+ *
+ * [out] memref[0] Random data
+ *
+ * Result:
+ * TEE_SUCCESS - Invoke command success
+ * TEE_ERROR_BAD_PARAMETERS - Incorrect input param
+ */
+#define TA_CMD_GET_RANDOM 0x0
+
+/*
+ * Seal trusted key using hardware unique key
+ *
+ * [in] memref[0] Plain key
+ * [out] memref[1] Sealed key datablob
+ *
+ * Result:
+ * TEE_SUCCESS - Invoke command success
+ * TEE_ERROR_BAD_PARAMETERS - Incorrect input param
+ */
+#define TA_CMD_SEAL 0x1
+
+/*
+ * Unseal trusted key using hardware unique key
+ *
+ * [in] memref[0] Sealed key datablob
+ * [out] memref[1] Plain key
+ *
+ * Result:
+ * TEE_SUCCESS - Invoke command success
+ * TEE_ERROR_BAD_PARAMETERS - Incorrect input param
+ */
+#define TA_CMD_UNSEAL 0x2
+
+/**
+ * struct trusted_key_private - TEE Trusted key private data
+ * @dev: TEE based Trusted key device.
+ * @ctx: TEE context handler.
+ * @session_id: Trusted key TA session identifier.
+ * @shm_pool: Memory pool shared with TEE device.
+ */
+struct trusted_key_private {
+ struct device *dev;
+ struct tee_context *ctx;
+ u32 session_id;
+ u32 data_rate;
+ struct tee_shm *shm_pool;
+};
+
+#endif
diff --git a/security/keys/Kconfig b/security/keys/Kconfig
index 47c0415..6ca6bc7 100644
--- a/security/keys/Kconfig
+++ b/security/keys/Kconfig
@@ -84,6 +84,9 @@ config TRUSTED_KEYS
if the boot PCRs and other criteria match. Userspace will only ever
see encrypted blobs.
+ It also provides support for alternative TEE based Trusted keys
+ generation and sealing in case TPM isn't present.
+
If you are unsure as to whether this is required, answer N.
config ENCRYPTED_KEYS
diff --git a/security/keys/trusted-keys/Makefile b/security/keys/trusted-keys/Makefile
index 2b1085b..ea937d3 100644
--- a/security/keys/trusted-keys/Makefile
+++ b/security/keys/trusted-keys/Makefile
@@ -7,3 +7,4 @@ obj-$(CONFIG_TRUSTED_KEYS) += trusted.o
trusted-y += trusted_common.o
trusted-y += trusted_tpm1.o
trusted-y += trusted_tpm2.o
+trusted-y += trusted_tee.o
diff --git a/security/keys/trusted-keys/trusted_common.c b/security/keys/trusted-keys/trusted_common.c
index 9bfd081..03555ed 100644
--- a/security/keys/trusted-keys/trusted_common.c
+++ b/security/keys/trusted-keys/trusted_common.c
@@ -27,6 +27,9 @@ static struct trusted_key_ops *available_tk_ops[] = {
#if defined(CONFIG_TCG_TPM)
&tpm_trusted_key_ops,
#endif
+#if defined(CONFIG_TEE)
+ &tee_trusted_key_ops,
+#endif
};
static struct trusted_key_ops *tk_ops;
diff --git a/security/keys/trusted-keys/trusted_tee.c b/security/keys/trusted-keys/trusted_tee.c
new file mode 100644
index 0000000..724a73c
--- /dev/null
+++ b/security/keys/trusted-keys/trusted_tee.c
@@ -0,0 +1,282 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 Linaro Ltd.
+ *
+ * Author:
+ * Sumit Garg <[email protected]>
+ */
+
+#include <linux/err.h>
+#include <linux/key-type.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/uuid.h>
+
+#include <keys/trusted-type.h>
+#include <keys/trusted_tee.h>
+
+static struct trusted_key_private pvt_data;
+
+/*
+ * Have the TEE seal(encrypt) the symmetric key
+ */
+static int tee_key_seal(struct trusted_key_payload *p, char *datablob)
+{
+ int ret = 0;
+ struct tee_ioctl_invoke_arg inv_arg;
+ struct tee_param param[4];
+ struct tee_shm *reg_shm_in = NULL, *reg_shm_out = NULL;
+
+ memset(&inv_arg, 0, sizeof(inv_arg));
+ memset(¶m, 0, sizeof(param));
+
+ reg_shm_in = tee_shm_register(pvt_data.ctx, (unsigned long)p->key,
+ p->key_len, TEE_SHM_DMA_BUF |
+ TEE_SHM_KERNEL_MAPPED);
+ if (IS_ERR(reg_shm_in)) {
+ dev_err(pvt_data.dev, "key shm register failed\n");
+ return PTR_ERR(reg_shm_in);
+ }
+
+ reg_shm_out = tee_shm_register(pvt_data.ctx, (unsigned long)p->blob,
+ sizeof(p->blob), TEE_SHM_DMA_BUF |
+ TEE_SHM_KERNEL_MAPPED);
+ if (IS_ERR(reg_shm_out)) {
+ dev_err(pvt_data.dev, "blob shm register failed\n");
+ ret = PTR_ERR(reg_shm_out);
+ goto out;
+ }
+
+ inv_arg.func = TA_CMD_SEAL;
+ inv_arg.session = pvt_data.session_id;
+ inv_arg.num_params = 4;
+
+ param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT;
+ param[0].u.memref.shm = reg_shm_in;
+ param[0].u.memref.size = p->key_len;
+ param[0].u.memref.shm_offs = 0;
+ param[1].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT;
+ param[1].u.memref.shm = reg_shm_out;
+ param[1].u.memref.size = sizeof(p->blob);
+ param[1].u.memref.shm_offs = 0;
+
+ ret = tee_client_invoke_func(pvt_data.ctx, &inv_arg, param);
+ if ((ret < 0) || (inv_arg.ret != 0)) {
+ dev_err(pvt_data.dev, "TA_CMD_SEAL invoke err: %x\n",
+ inv_arg.ret);
+ ret = -EFAULT;
+ } else {
+ p->blob_len = param[1].u.memref.size;
+ }
+
+out:
+ if (reg_shm_out)
+ tee_shm_free(reg_shm_out);
+ if (reg_shm_in)
+ tee_shm_free(reg_shm_in);
+
+ return ret;
+}
+
+/*
+ * Have the TEE unseal(decrypt) the symmetric key
+ */
+static int tee_key_unseal(struct trusted_key_payload *p, char *datablob)
+{
+ int ret = 0;
+ struct tee_ioctl_invoke_arg inv_arg;
+ struct tee_param param[4];
+ struct tee_shm *reg_shm_in = NULL, *reg_shm_out = NULL;
+
+ memset(&inv_arg, 0, sizeof(inv_arg));
+ memset(¶m, 0, sizeof(param));
+
+ reg_shm_in = tee_shm_register(pvt_data.ctx, (unsigned long)p->blob,
+ p->blob_len, TEE_SHM_DMA_BUF |
+ TEE_SHM_KERNEL_MAPPED);
+ if (IS_ERR(reg_shm_in)) {
+ dev_err(pvt_data.dev, "blob shm register failed\n");
+ return PTR_ERR(reg_shm_in);
+ }
+
+ reg_shm_out = tee_shm_register(pvt_data.ctx, (unsigned long)p->key,
+ sizeof(p->key), TEE_SHM_DMA_BUF |
+ TEE_SHM_KERNEL_MAPPED);
+ if (IS_ERR(reg_shm_out)) {
+ dev_err(pvt_data.dev, "key shm register failed\n");
+ ret = PTR_ERR(reg_shm_out);
+ goto out;
+ }
+
+ inv_arg.func = TA_CMD_UNSEAL;
+ inv_arg.session = pvt_data.session_id;
+ inv_arg.num_params = 4;
+
+ param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT;
+ param[0].u.memref.shm = reg_shm_in;
+ param[0].u.memref.size = p->blob_len;
+ param[0].u.memref.shm_offs = 0;
+ param[1].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT;
+ param[1].u.memref.shm = reg_shm_out;
+ param[1].u.memref.size = sizeof(p->key);
+ param[1].u.memref.shm_offs = 0;
+
+ ret = tee_client_invoke_func(pvt_data.ctx, &inv_arg, param);
+ if ((ret < 0) || (inv_arg.ret != 0)) {
+ dev_err(pvt_data.dev, "TA_CMD_UNSEAL invoke err: %x\n",
+ inv_arg.ret);
+ ret = -EFAULT;
+ } else {
+ p->key_len = param[1].u.memref.size;
+ }
+
+out:
+ if (reg_shm_out)
+ tee_shm_free(reg_shm_out);
+ if (reg_shm_in)
+ tee_shm_free(reg_shm_in);
+
+ return ret;
+}
+
+/*
+ * Have the TEE generate random symmetric key
+ */
+static int tee_get_random(unsigned char *key, size_t key_len)
+{
+ int ret = 0;
+ struct tee_ioctl_invoke_arg inv_arg;
+ struct tee_param param[4];
+ struct tee_shm *reg_shm = NULL;
+
+ memset(&inv_arg, 0, sizeof(inv_arg));
+ memset(¶m, 0, sizeof(param));
+
+ reg_shm = tee_shm_register(pvt_data.ctx, (unsigned long)key, key_len,
+ TEE_SHM_DMA_BUF | TEE_SHM_KERNEL_MAPPED);
+ if (IS_ERR(reg_shm)) {
+ dev_err(pvt_data.dev, "random key shm register failed\n");
+ return PTR_ERR(reg_shm);
+ }
+
+ inv_arg.func = TA_CMD_GET_RANDOM;
+ inv_arg.session = pvt_data.session_id;
+ inv_arg.num_params = 4;
+
+ param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT;
+ param[0].u.memref.shm = reg_shm;
+ param[0].u.memref.size = key_len;
+ param[0].u.memref.shm_offs = 0;
+
+ ret = tee_client_invoke_func(pvt_data.ctx, &inv_arg, param);
+ if ((ret < 0) || (inv_arg.ret != 0)) {
+ dev_err(pvt_data.dev, "TA_CMD_GET_RANDOM invoke err: %x\n",
+ inv_arg.ret);
+ ret = -EFAULT;
+ } else {
+ ret = param[0].u.memref.size;
+ }
+
+ tee_shm_free(reg_shm);
+
+ return ret;
+}
+
+static int optee_ctx_match(struct tee_ioctl_version_data *ver, const void *data)
+{
+ if (ver->impl_id == TEE_IMPL_ID_OPTEE)
+ return 1;
+ else
+ return 0;
+}
+
+static int trusted_key_probe(struct device *dev)
+{
+ struct tee_client_device *rng_device = to_tee_client_device(dev);
+ int ret = 0, err = -ENODEV;
+ struct tee_ioctl_open_session_arg sess_arg;
+
+ memset(&sess_arg, 0, sizeof(sess_arg));
+
+ /* Open context with TEE driver */
+ pvt_data.ctx = tee_client_open_context(NULL, optee_ctx_match, NULL,
+ NULL);
+ if (IS_ERR(pvt_data.ctx))
+ return -ENODEV;
+
+ /* Open session with hwrng Trusted App */
+ memcpy(sess_arg.uuid, rng_device->id.uuid.b, TEE_IOCTL_UUID_LEN);
+ sess_arg.clnt_login = TEE_IOCTL_LOGIN_REE_KERNEL;
+ sess_arg.num_params = 0;
+
+ ret = tee_client_open_session(pvt_data.ctx, &sess_arg, NULL);
+ if ((ret < 0) || (sess_arg.ret != 0)) {
+ dev_err(dev, "tee_client_open_session failed, err: %x\n",
+ sess_arg.ret);
+ err = -EINVAL;
+ goto out_ctx;
+ }
+ pvt_data.session_id = sess_arg.session;
+
+ ret = register_key_type(&key_type_trusted);
+ if (ret < 0)
+ goto out_sess;
+
+ pvt_data.dev = dev;
+
+ return 0;
+
+out_sess:
+ tee_client_close_session(pvt_data.ctx, pvt_data.session_id);
+out_ctx:
+ tee_client_close_context(pvt_data.ctx);
+
+ return err;
+}
+
+static int trusted_key_remove(struct device *dev)
+{
+ unregister_key_type(&key_type_trusted);
+ tee_client_close_session(pvt_data.ctx, pvt_data.session_id);
+ tee_client_close_context(pvt_data.ctx);
+
+ return 0;
+}
+
+static const struct tee_client_device_id trusted_key_id_table[] = {
+ {UUID_INIT(0xf04a0fe7, 0x1f5d, 0x4b9b,
+ 0xab, 0xf7, 0x61, 0x9b, 0x85, 0xb4, 0xce, 0x8c)},
+ {}
+};
+
+MODULE_DEVICE_TABLE(tee, trusted_key_id_table);
+
+static struct tee_client_driver trusted_key_driver = {
+ .id_table = trusted_key_id_table,
+ .driver = {
+ .name = DRIVER_NAME,
+ .bus = &tee_bus_type,
+ .probe = trusted_key_probe,
+ .remove = trusted_key_remove,
+ },
+};
+
+static int __init init_tee_trusted(void)
+{
+ return driver_register(&trusted_key_driver.driver);
+}
+
+static void __exit cleanup_tee_trusted(void)
+{
+ driver_unregister(&trusted_key_driver.driver);
+}
+
+struct trusted_key_ops tee_trusted_key_ops = {
+ .migratable = 0, /* non-migratable */
+ .init = init_tee_trusted,
+ .seal = tee_key_seal,
+ .unseal = tee_key_unseal,
+ .get_random = tee_get_random,
+ .cleanup = cleanup_tee_trusted,
+};
+EXPORT_SYMBOL_GPL(tee_trusted_key_ops);
--
2.7.4
Update documentation for Trusted and Encrypted Keys with TEE as a new
trust source. Following is brief description of updates:
- Add a section to demostrate a list of supported devices along with
their security properties/guarantees.
- Add a key generation section.
- Updates for usage section including differences specific to a trust
source.
Signed-off-by: Sumit Garg <[email protected]>
---
Documentation/security/keys/trusted-encrypted.rst | 203 ++++++++++++++++++----
1 file changed, 171 insertions(+), 32 deletions(-)
diff --git a/Documentation/security/keys/trusted-encrypted.rst b/Documentation/security/keys/trusted-encrypted.rst
index 50ac8bc..4764a6d 100644
--- a/Documentation/security/keys/trusted-encrypted.rst
+++ b/Documentation/security/keys/trusted-encrypted.rst
@@ -6,30 +6,161 @@ Trusted and Encrypted Keys are two new key types added to the existing kernel
key ring service. Both of these new types are variable length symmetric keys,
and in both cases all keys are created in the kernel, and user space sees,
stores, and loads only encrypted blobs. Trusted Keys require the availability
-of a Trusted Platform Module (TPM) chip for greater security, while Encrypted
-Keys can be used on any system. All user level blobs, are displayed and loaded
-in hex ascii for convenience, and are integrity verified.
+of a Trust Source for greater security, while Encrypted Keys can be used on any
+system. All user level blobs, are displayed and loaded in hex ascii for
+convenience, and are integrity verified.
-Trusted Keys use a TPM both to generate and to seal the keys. Keys are sealed
-under a 2048 bit RSA key in the TPM, and optionally sealed to specified PCR
-(integrity measurement) values, and only unsealed by the TPM, if PCRs and blob
-integrity verifications match. A loaded Trusted Key can be updated with new
-(future) PCR values, so keys are easily migrated to new pcr values, such as
-when the kernel and initramfs are updated. The same key can have many saved
-blobs under different PCR values, so multiple boots are easily supported.
-TPM 1.2
--------
+Trust Source
+============
-By default, trusted keys are sealed under the SRK, which has the default
-authorization value (20 zeros). This can be set at takeownership time with the
-trouser's utility: "tpm_takeownership -u -z".
+Trust Source provides the source of security for the Trusted Keys, on which
+basis Trusted Keys establishes a Trust model with its user. A Trust Source could
+differ from one system to another depending on its security requirements. It
+could be either an off-chip device or an on-chip device. Following section
+demostrates a list of supported devices along with their security properties/
+guarantees:
-TPM 2.0
--------
+ * Root of trust for storage
-The user must first create a storage key and make it persistent, so the key is
-available after reboot. This can be done using the following commands.
+ (1) TPM (Trusted Platform Module: hardware device)
+
+ Rooted to Storage Root Key (SRK) which never leaves the TPM that
+ provides crypto operation to establish root of trust for storage.
+
+ (2) TEE (Trusted Execution Environment: OP-TEE based on Arm TrustZone)
+
+ Rooted to Hardware Unique Key (HUK) which is generally burnt in on-chip
+ fuses and is accessible to TEE only.
+
+ * Execution isolation
+
+ (1) TPM
+
+ Fixed set of operations running in isolated execution environment.
+
+ (2) TEE
+
+ Customizable set of operations running in isolated execution
+ environment verified via Secure/Trusted boot process.
+
+ * Optional binding to platform integrity state
+
+ (1) TPM
+
+ Keys can be optionally sealed to specified PCR (integrity measurement)
+ values, and only unsealed by the TPM, if PCRs and blob integrity
+ verifications match. A loaded Trusted Key can be updated with new
+ (future) PCR values, so keys are easily migrated to new PCR values,
+ such as when the kernel and initramfs are updated. The same key can
+ have many saved blobs under different PCR values, so multiple boots are
+ easily supported.
+
+ (2) TEE
+
+ Relies on Secure/Trusted boot process for platform integrity. It can
+ be extended with TEE based measured boot process.
+
+ * On-chip versus off-chip
+
+ (1) TPM
+
+ Off-chip device connected via serial bus (like I2C, SPI etc.) exposing
+ physical access which represents an attack surface that can be
+ mitigated via tamper detection.
+
+ (2) TEE
+
+ On-chip functionality, immune to this attack surface.
+
+ * Memory attacks (DRAM based like attaching a bus monitor etc.)
+
+ (1) TPM
+
+ Immune to these attacks as it doesn’t make use of system DRAM.
+
+ (2) TEE
+
+ An implementation based on TrustZone protected DRAM is susceptible to
+ such attacks. In order to mitigate these attacks one needs to rely on
+ on-chip secure RAM to store secrets or have the entire TEE
+ implementation based on on-chip secure RAM. An alternative mitigation
+ would be to use encrypted DRAM.
+
+ * Side-channel attacks (cache, memory, CPU or time based)
+
+ (1) TPM
+
+ Immune to side-channel attacks as its resources are isolated from the
+ main OS.
+
+ (2) TEE
+
+ A careful implementation is required to mitigate against these attacks
+ for resources which are shared (eg. shared memory) with the main OS.
+ Cache and CPU based side-channel attacks can be mitigated via
+ invalidating caches and CPU registers during context switch to and from
+ the secure world.
+ To mitigate against time based attacks, one needs to have time
+ invariant implementations (like crypto algorithms etc.).
+
+ * Resistance to physical attacks (power analysis, electromagnetic emanation,
+ probes etc.)
+
+ (1) TPM
+
+ Provides limited protection utilizing tamper resistance.
+
+ (2) TEE
+
+ Provides no protection by itself, relies on the underlying platform for
+ features such as tamper resistance.
+
+
+Key Generation
+==============
+
+Trusted Keys
+------------
+
+New keys are created from trust source generated random numbers, and are
+encrypted/decrypted using trust source storage root key.
+
+ * TPM (hardware device) based RNG
+
+ Strength of random numbers may vary from one device manufacturer to
+ another.
+
+ * TEE (OP-TEE based on Arm TrustZone) based RNG
+
+ RNG is customizable as per platform needs. It can either be direct output
+ from platform specific hardware RNG or a software based Fortuna CSPRNG
+ which can be seeded via multiple entropy sources.
+
+Encrypted Keys
+--------------
+
+Encrypted keys do not depend on a trust source, and are faster, as they use AES
+for encryption/decryption. New keys are created from kernel generated random
+numbers, and are encrypted/decrypted using a specified ‘master’ key. The
+‘master’ key can either be a trusted-key or user-key type. The main disadvantage
+of encrypted keys is that if they are not rooted in a trusted key, they are only
+as secure as the user key encrypting them. The master user key should therefore
+be loaded in as secure a way as possible, preferably early in boot.
+
+
+Usage
+=====
+
+Trusted Keys usage: TPM
+-----------------------
+
+TPM 1.2: By default, trusted keys are sealed under the SRK, which has the
+default authorization value (20 zeros). This can be set at takeownership time
+with the TrouSerS utility: "tpm_takeownership -u -z".
+
+TPM 2.0: The user must first create a storage key and make it persistent, so the
+key is available after reboot. This can be done using the following commands.
With the IBM TSS 2 stack::
@@ -79,14 +210,21 @@ TPM_STORED_DATA format. The key length for new keys are always in bytes.
Trusted Keys can be 32 - 128 bytes (256 - 1024 bits), the upper limit is to fit
within the 2048 bit SRK (RSA) keylength, with all necessary structure/padding.
-Encrypted keys do not depend on a TPM, and are faster, as they use AES for
-encryption/decryption. New keys are created from kernel generated random
-numbers, and are encrypted/decrypted using a specified 'master' key. The
-'master' key can either be a trusted-key or user-key type. The main
-disadvantage of encrypted keys is that if they are not rooted in a trusted key,
-they are only as secure as the user key encrypting them. The master user key
-should therefore be loaded in as secure a way as possible, preferably early in
-boot.
+Trusted Keys usage: TEE
+-----------------------
+
+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 TEE device implementation. The key length for new keys are always
+in bytes. Trusted Keys can be 32 - 128 bytes (256 - 1024 bits).
+
+Encrypted Keys usage
+--------------------
The decrypted portion of encrypted keys can contain either a simple symmetric
key or a more complex structure. The format of the more complex structure is
@@ -104,8 +242,8 @@ Where::
format:= 'default | ecryptfs | enc32'
key-type:= 'trusted' | 'user'
-
Examples of trusted and encrypted key usage:
+--------------------------------------------
Create and save a trusted key named "kmk" of length 32 bytes.
@@ -151,7 +289,7 @@ Load a trusted key from the saved blob::
f1f8fff03ad0acb083725535636addb08d73dedb9832da198081e5deae84bfaf0409c22b
e4a8aea2b607ec96931e6f4d4fe563ba
-Reseal a trusted key under new pcr values::
+Reseal (TPM specific) a trusted key under new PCR values::
$ keyctl update 268728824 "update pcrinfo=`cat pcr.blob`"
$ keyctl print 268728824
@@ -165,11 +303,12 @@ Reseal a trusted key under new pcr values::
7ef6a24defe4846104209bf0c3eced7fa1a672ed5b125fc9d8cd88b476a658a4434644ef
df8ae9a178e9f83ba9f08d10fa47e4226b98b0702f06b3b8
+
The initial consumer of trusted keys is EVM, which at boot time needs a high
-quality symmetric key for HMAC protection of file metadata. The use of a
+quality symmetric key for HMAC protection of file metadata. The use of a
trusted key provides strong guarantees that the EVM key has not been
-compromised by a user level problem, and when sealed to specific boot PCR
-values, protects against boot and offline attacks. Create and save an
+compromised by a user level problem, and when sealed to a platform integrity
+state, protects against boot and offline attacks. Create and save an
encrypted key "evm" using the above trusted key "kmk":
option 1: omitting 'format'::
--
2.7.4
Add MAINTAINERS entry for TEE based Trusted Keys framework.
Signed-off-by: Sumit Garg <[email protected]>
---
MAINTAINERS | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/MAINTAINERS b/MAINTAINERS
index b816a45..fc8bf16 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9403,6 +9403,14 @@ F: include/keys/trusted-type.h
F: include/keys/trusted_tpm.h
F: security/keys/trusted-keys/
+KEYS-TRUSTED-TEE
+M: Sumit Garg <[email protected]>
+L: [email protected]
+L: [email protected]
+S: Supported
+F: include/keys/trusted_tee.h
+F: security/keys/trusted-keys/trusted_tee.c
+
KEYS/KEYRINGS
M: David Howells <[email protected]>
M: Jarkko Sakkinen <[email protected]>
--
2.7.4
On Wed, 6 May 2020 at 15:10, Sumit Garg <[email protected]> wrote:
>
> Add support for TEE based trusted keys where TEE provides the functionality
> to seal and unseal trusted keys using hardware unique key. Also, this is
> an alternative in case platform doesn't possess a TPM device.
>
> This patch-set has been tested with OP-TEE based early TA which can be
> found here [1].
>
> [1] https://github.com/OP-TEE/optee_os/pull/3838
Fyi, this PR has been merged in OP-TEE OS as commit [1]. Looking
forward to any further comments/feedback on this patch-set.
[1] https://github.com/OP-TEE/optee_os/commit/f86ab8e7e0de869dfa25ca05a37ee070d7e5b86b
-Sumit
>
> Changes in v4:
> 1. Pushed independent TEE features separately:
> - Part of recent TEE PR: https://lkml.org/lkml/2020/5/4/1062
> 2. Updated trusted-encrypted doc with TEE as a new trust source.
> 3. Rebased onto latest tpmdd/master.
>
> Changes in v3:
> 1. Update patch #2 to support registration of multiple kernel pages.
> 2. Incoporate dependency patch #4 in this patch-set:
> https://patchwork.kernel.org/patch/11091435/
>
> Changes in v2:
> 1. Add reviewed-by tags for patch #1 and #2.
> 2. Incorporate comments from Jens for patch #3.
> 3. Switch to use generic trusted keys framework.
>
> Sumit Garg (4):
> KEYS: trusted: Add generic trusted keys framework
> KEYS: trusted: Introduce TEE based Trusted Keys
> doc: trusted-encrypted: updates with TEE as a new trust source
> MAINTAINERS: Add entry for TEE based Trusted Keys
>
> Documentation/security/keys/trusted-encrypted.rst | 203 ++++++++++---
> MAINTAINERS | 8 +
> include/keys/trusted-type.h | 48 ++++
> include/keys/trusted_tee.h | 66 +++++
> include/keys/trusted_tpm.h | 15 -
> security/keys/Kconfig | 3 +
> security/keys/trusted-keys/Makefile | 2 +
> security/keys/trusted-keys/trusted_common.c | 336 ++++++++++++++++++++++
> security/keys/trusted-keys/trusted_tee.c | 282 ++++++++++++++++++
> security/keys/trusted-keys/trusted_tpm1.c | 335 ++++-----------------
> 10 files changed, 974 insertions(+), 324 deletions(-)
> create mode 100644 include/keys/trusted_tee.h
> create mode 100644 security/keys/trusted-keys/trusted_common.c
> create mode 100644 security/keys/trusted-keys/trusted_tee.c
>
> --
> 2.7.4
>
On Wed, 2020-05-06 at 15:10 +0530, Sumit Garg wrote:
> Add support for TEE based trusted keys where TEE provides the functionality
> to seal and unseal trusted keys using hardware unique key.
>
> Refer to Documentation/tee.txt for detailed information about TEE.
>
> Signed-off-by: Sumit Garg <[email protected]>
The implementation looks solid but how or who could possibly test this?
I do posses (personally, not from employer) bunch of ARM boards but my
TZ knowledge is somewhat limited (e.g. how can I get something running
in TZ).
/Jarkko
On Wed, 2020-05-06 at 15:10 +0530, Sumit Garg wrote:
> Update documentation for Trusted and Encrypted Keys with TEE as a new
> trust source. Following is brief description of updates:
>
> - Add a section to demostrate a list of supported devices along with
> their security properties/guarantees.
> - Add a key generation section.
> - Updates for usage section including differences specific to a trust
> source.
>
> Signed-off-by: Sumit Garg <[email protected]>
Reviewed-by: Jarkko Sakkinen <[email protected]>
/Jarkko
On Wed, 2020-05-06 at 15:10 +0530, Sumit Garg wrote:
> Add MAINTAINERS entry for TEE based Trusted Keys framework.
>
> Signed-off-by: Sumit Garg <[email protected]>
Acked-by: Jarkko Sakkinen <[email protected]>
/Jarkko
On Thu, 14 May 2020 at 05:58, Jarkko Sakkinen
<[email protected]> wrote:
>
> On Wed, 2020-05-06 at 15:10 +0530, Sumit Garg wrote:
> > Add support for TEE based trusted keys where TEE provides the functionality
> > to seal and unseal trusted keys using hardware unique key.
> >
> > Refer to Documentation/tee.txt for detailed information about TEE.
> >
> > Signed-off-by: Sumit Garg <[email protected]>
>
> The implementation looks solid but how or who could possibly test this?
>
> I do posses (personally, not from employer) bunch of ARM boards but my
> TZ knowledge is somewhat limited (e.g. how can I get something running
> in TZ).
>
Although, it should be fairly easy to test this implementation on an
ARM board which supports OP-TEE. But since you are new to ARM
TrustZone world, I would suggest you get used to OP-TEE on Qemu based
setup. You could find pretty good documentation for this here [1] but
for simplicity let me document steps here to test this trusted keys
feature from scratch:
# Install prerequisites as mentioned here [2]
# Get the source code
$ mkdir -p <optee-project>
$ cd <optee-project>
$ repo init -u https://github.com/OP-TEE/manifest.git -m qemu_v8.xml
$ repo sync -j4 --no-clone-bundle
# Get the toolchain
$ cd <optee-project>/build
$ make -j2 toolchains
# As trusted keys work is based on latest tpmdd/master, so we can
change Linux base as follows:
$ cd <optee-project>/linux
$ git remote add tpmdd git://git.infradead.org/users/jjs/linux-tpmdd.git
$ git pull tpmdd
$ git checkout -b tpmdd-master remotes/tpmdd/master
# Cherry-pick and apply TEE features patch-set from this PR[3]
# Apply this Linux trusted keys patch-set.
# Now move on to build the source code
$ cd <optee-project>/build
# Apply attached "keyctl_change" patch
$ patch -p1 < keyctl_change
$ make -j`nproc`
CFG_IN_TREE_EARLY_TAS=trusted_keys/f04a0fe7-1f5d-4b9b-abf7-619b85b4ce8c
# Run QEMU setup
$ make run-only
# Type "c" on QEMU console to continue boot
# Now there should be two virtual consoles up, one for OP-TEE and
other for Linux
# On Linux console, you can play with "keyctl" utility to have trusted
and encrypted keys based on TEE.
Do let me know in case you are stuck while following the above steps.
[1] https://optee.readthedocs.io/en/latest/building/devices/qemu.html#qemu-v8
[2] https://optee.readthedocs.io/en/latest/building/prerequisites.html#prerequisites
[3] https://lkml.org/lkml/2020/5/4/1062
-Sumit
> /Jarkko
>
On Thu, 2020-05-14 at 12:57 +0530, Sumit Garg wrote:
> On Thu, 14 May 2020 at 05:58, Jarkko Sakkinen
> <[email protected]> wrote:
> > On Wed, 2020-05-06 at 15:10 +0530, Sumit Garg wrote:
> > > Add support for TEE based trusted keys where TEE provides the functionality
> > > to seal and unseal trusted keys using hardware unique key.
> > >
> > > Refer to Documentation/tee.txt for detailed information about TEE.
> > >
> > > Signed-off-by: Sumit Garg <[email protected]>
> >
> > The implementation looks solid but how or who could possibly test this?
> >
> > I do posses (personally, not from employer) bunch of ARM boards but my
> > TZ knowledge is somewhat limited (e.g. how can I get something running
> > in TZ).
> >
>
> Although, it should be fairly easy to test this implementation on an
> ARM board which supports OP-TEE. But since you are new to ARM
> TrustZone world, I would suggest you get used to OP-TEE on Qemu based
> setup. You could find pretty good documentation for this here [1] but
> for simplicity let me document steps here to test this trusted keys
> feature from scratch:
>
> # Install prerequisites as mentioned here [2]
>
> # Get the source code
> $ mkdir -p <optee-project>
> $ cd <optee-project>
> $ repo init -u https://github.com/OP-TEE/manifest.git -m qemu_v8.xml
> $ repo sync -j4 --no-clone-bundle
>
> # Get the toolchain
> $ cd <optee-project>/build
> $ make -j2 toolchains
>
> # As trusted keys work is based on latest tpmdd/master, so we can
> change Linux base as follows:
> $ cd <optee-project>/linux
> $ git remote add tpmdd git://git.infradead.org/users/jjs/linux-tpmdd.git
> $ git pull tpmdd
> $ git checkout -b tpmdd-master remotes/tpmdd/master
> # Cherry-pick and apply TEE features patch-set from this PR[3]
> # Apply this Linux trusted keys patch-set.
>
> # Now move on to build the source code
> $ cd <optee-project>/build
> # Apply attached "keyctl_change" patch
> $ patch -p1 < keyctl_change
> $ make -j`nproc`
> CFG_IN_TREE_EARLY_TAS=trusted_keys/f04a0fe7-1f5d-4b9b-abf7-619b85b4ce8c
>
> # Run QEMU setup
> $ make run-only
> # Type "c" on QEMU console to continue boot
>
> # Now there should be two virtual consoles up, one for OP-TEE and
> other for Linux
> # On Linux console, you can play with "keyctl" utility to have trusted
> and encrypted keys based on TEE.
>
> Do let me know in case you are stuck while following the above steps.
>
> [1] https://optee.readthedocs.io/en/latest/building/devices/qemu.html#qemu-v8
> [2] https://optee.readthedocs.io/en/latest/building/prerequisites.html#prerequisites
> [3] https://lkml.org/lkml/2020/5/4/1062
>
> -Sumit
Thanks I'll try this out as soon as the v5.8 release hassle is over!
/Jarkko