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* [PATCH v8 0/8] TPM 2.0 trusted keys with attached policy
@ 2020-03-10  5:15 James Bottomley
  2020-03-10  5:16 ` [PATCH v8 1/8] lib: add ASN.1 encoder James Bottomley
                   ` (10 more replies)
  0 siblings, 11 replies; 19+ messages in thread
From: James Bottomley @ 2020-03-10  5:15 UTC (permalink / raw)
  To: linux-integrity; +Cc: Mimi Zohar, Jarkko Sakkinen, David Woodhouse, keyrings

This is a respin to separate patch 4 into the original three patches
it was.  I've done testing with each of the three splinters, so I
think I've got the split correct.

General cover letter:

This patch updates the trusted key code to export keys in the ASN.1
format used by current TPM key tools (openssl_tpm2_engine and
openconnect).  It also simplifies the use of policy with keys because
the ASN.1 format is designed to carry a description of how to
construct the policy, with the result that simple policies (like
authorization and PCR locking) can now be constructed and used in the
kernel, bringing the TPM 2.0 policy use into line with how TPM 1.2
works.

The key format is designed to be compatible with our two openssl
engine implementations as well as with the format used by openconnect.
I've added seal/unseal to my engine so I can use it for
interoperability testing and I'll later use this for sealed symmetric
keys via engine:

https://git.kernel.org/pub/scm/linux/kernel/git/jejb/openssl_tpm2_engine.git/

James

---

James Bottomley (8):
  lib: add ASN.1 encoder
  oid_registry: Add TCG defined OIDS for TPM keys
  security: keys: trusted: fix TPM2 authorizations
  security: keys: trusted: use ASN.1 TPM2 key format for the blobs
  security: keys: trusted: Make sealed key properly interoperable
  security: keys: trusted: add PCR policy to TPM2 keys
  security: keys: trusted: add ability to specify arbitrary policy
  security: keys: trusted: implement counter/timer policy

 Documentation/security/keys/trusted-encrypted.rst |  64 ++-
 include/keys/trusted-type.h                       |   7 +-
 include/linux/asn1_encoder.h                      |  32 ++
 include/linux/oid_registry.h                      |   5 +
 include/linux/tpm.h                               |   8 +
 lib/Makefile                                      |   2 +-
 lib/asn1_encoder.c                                | 431 ++++++++++++++++++++
 security/keys/Kconfig                             |   2 +
 security/keys/trusted-keys/Makefile               |   2 +-
 security/keys/trusted-keys/tpm2-policy.c          | 463 ++++++++++++++++++++++
 security/keys/trusted-keys/tpm2-policy.h          |  31 ++
 security/keys/trusted-keys/tpm2key.asn1           |  23 ++
 security/keys/trusted-keys/trusted_tpm1.c         |  56 ++-
 security/keys/trusted-keys/trusted_tpm2.c         | 370 +++++++++++++++--
 14 files changed, 1459 insertions(+), 37 deletions(-)
 create mode 100644 include/linux/asn1_encoder.h
 create mode 100644 lib/asn1_encoder.c
 create mode 100644 security/keys/trusted-keys/tpm2-policy.c
 create mode 100644 security/keys/trusted-keys/tpm2-policy.h
 create mode 100644 security/keys/trusted-keys/tpm2key.asn1

-- 
2.16.4


^ permalink raw reply	[flat|nested] 19+ messages in thread

* [PATCH v8 1/8] lib: add ASN.1 encoder
  2020-03-10  5:15 [PATCH v8 0/8] TPM 2.0 trusted keys with attached policy James Bottomley
@ 2020-03-10  5:16 ` James Bottomley
  2020-03-19 19:16   ` Eric Biggers
  2020-03-10  5:16 ` [PATCH v8 2/8] oid_registry: Add TCG defined OIDS for TPM keys James Bottomley
                   ` (9 subsequent siblings)
  10 siblings, 1 reply; 19+ messages in thread
From: James Bottomley @ 2020-03-10  5:16 UTC (permalink / raw)
  To: linux-integrity; +Cc: Mimi Zohar, Jarkko Sakkinen, David Woodhouse, keyrings

We have a need in the TPM2 trusted keys to return the ASN.1 form of
the TPM key blob so it can be operated on by tools outside of the
kernel.  The specific tools are the openssl_tpm2_engine, openconnect
and the Intel tpm2-tss-engine.  To do that, we have to be able to read
and write the same binary key format the tools use.  The current ASN.1
decoder does fine for reading, but we need pieces of an ASN.1 encoder
to write the key blob in binary compatible form.

For backwards compatibility, the trusted key reader code will still
accept the two TPM2B quantities that it uses today, but the writer
will only output the ASN.1 form.

The current implementation only encodes the ASN.1 bits we actually need.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

---

v2: updated API to use indefinite length, and made symbol exports gpl
v3: add data length error handling
v4: use end_data instead of data_len pointer
v5: mention tools and space out code
v7: reverse christmas tree variable definitions and better spacing
---
 include/linux/asn1_encoder.h |  32 ++++
 lib/Makefile                 |   2 +-
 lib/asn1_encoder.c           | 431 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 464 insertions(+), 1 deletion(-)
 create mode 100644 include/linux/asn1_encoder.h
 create mode 100644 lib/asn1_encoder.c

diff --git a/include/linux/asn1_encoder.h b/include/linux/asn1_encoder.h
new file mode 100644
index 000000000000..08cd0c2ad34f
--- /dev/null
+++ b/include/linux/asn1_encoder.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef _LINUX_ASN1_ENCODER_H
+#define _LINUX_ASN1_ENCODER_H
+
+#include <linux/types.h>
+#include <linux/asn1.h>
+#include <linux/asn1_ber_bytecode.h>
+#include <linux/bug.h>
+
+#define asn1_oid_len(oid) (sizeof(oid)/sizeof(u32))
+unsigned char *
+asn1_encode_integer(unsigned char *data, const unsigned char *end_data,
+		    s64 integer);
+unsigned char *
+asn1_encode_oid(unsigned char *data, const unsigned char *end_data,
+		u32 oid[], int oid_len);
+unsigned char *
+asn1_encode_tag(unsigned char *data, const unsigned char *end_data,
+		u32 tag, const unsigned char *string, int len);
+unsigned char *
+asn1_encode_octet_string(unsigned char *data,
+			 const unsigned char *end_data,
+			 const unsigned char *string, u32 len);
+unsigned char *
+asn1_encode_sequence(unsigned char *data, const unsigned char *end_data,
+		     const unsigned char *seq, int len);
+unsigned char *
+asn1_encode_boolean(unsigned char *data, const unsigned char *end_data,
+		    bool val);
+
+#endif
diff --git a/lib/Makefile b/lib/Makefile
index 611872c06926..1a9169ef2bed 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -237,7 +237,7 @@ obj-$(CONFIG_INTERVAL_TREE_TEST) += interval_tree_test.o
 
 obj-$(CONFIG_PERCPU_TEST) += percpu_test.o
 
-obj-$(CONFIG_ASN1) += asn1_decoder.o
+obj-$(CONFIG_ASN1) += asn1_decoder.o asn1_encoder.o
 
 obj-$(CONFIG_FONT_SUPPORT) += fonts/
 
diff --git a/lib/asn1_encoder.c b/lib/asn1_encoder.c
new file mode 100644
index 000000000000..24d45a838887
--- /dev/null
+++ b/lib/asn1_encoder.c
@@ -0,0 +1,431 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Simple encoder primitives for ASN.1 BER/DER/CER
+ *
+ * Copyright (C) 2019 James.Bottomley@HansenPartnership.com
+ */
+
+#include <linux/asn1_encoder.h>
+#include <linux/bug.h>
+#include <linux/string.h>
+#include <linux/module.h>
+
+/**
+ * asn1_encode_integer() - encode positive integer to ASN.1
+ * @data:	pointer to the pointer to the data
+ * @end_data:	end of data pointer, points one beyond last usable byte in @data
+ * @integer:	integer to be encoded
+ *
+ * This is a simplified encoder: it only currently does
+ * positive integers, but it should be simple enough to add the
+ * negative case if a use comes along.
+ */
+unsigned char *
+asn1_encode_integer(unsigned char *data, const unsigned char *end_data,
+		    s64 integer)
+{
+	int data_len = end_data - data;
+	unsigned char *d = &data[2];
+	bool found = false;
+	int i;
+
+	if (WARN(integer < 0,
+		 "BUG: integer encode only supports positive integers"))
+		return ERR_PTR(-EINVAL);
+
+	if (IS_ERR(data))
+		return data;
+
+	/* need at least 3 bytes for tag, length and integer encoding */
+	if (data_len < 3)
+		return ERR_PTR(-EINVAL);
+
+	/* remaining length where at d (the start of the integer encoding) */
+	data_len -= 2;
+
+	data[0] = _tag(UNIV, PRIM, INT);
+	if (integer == 0) {
+		*d++ = 0;
+		goto out;
+	}
+
+	for (i = sizeof(integer); i > 0 ; i--) {
+		int byte = integer >> (8 * (i - 1));
+
+		if (!found && byte == 0)
+			continue;
+
+		/*
+		 * for a positive number the first byte must have bit
+		 * 7 clear in two's complement (otherwise it's a
+		 * negative number) so prepend a leading zero if
+		 * that's not the case
+		 */
+		if (!found && (byte & 0x80)) {
+			/*
+			 * no check needed here, we already know we
+			 * have len >= 1
+			 */
+			*d++ = 0;
+			data_len--;
+		}
+
+		found = true;
+		if (data_len == 0)
+			return ERR_PTR(-EINVAL);
+
+		*d++ = byte;
+		data_len--;
+	}
+
+ out:
+	data[1] = d - data - 2;
+
+	return d;
+}
+EXPORT_SYMBOL_GPL(asn1_encode_integer);
+
+/* calculate the base 128 digit values setting the top bit of the first octet */
+static int asn1_encode_oid_digit(unsigned char **_data, int *data_len, u32 oid)
+{
+	unsigned char *data = *_data;
+	int start = 7 + 7 + 7 + 7;
+	int ret = 0;
+
+	if (*data_len < 1)
+		return -EINVAL;
+
+	/* quick case */
+	if (oid == 0) {
+		*data++ = 0x80;
+		(*data_len)--;
+		goto out;
+	}
+
+	while (oid >> start == 0)
+		start -= 7;
+
+	while (start > 0 && *data_len > 0) {
+		u8 byte;
+
+		byte = oid >> start;
+		oid = oid - (byte << start);
+		start -= 7;
+		byte |= 0x80;
+		*data++ = byte;
+		(*data_len)--;
+	}
+
+	if (*data_len > 0) {
+		*data++ = oid;
+		(*data_len)--;
+	} else {
+		ret = -EINVAL;
+	}
+
+ out:
+	*_data = data;
+	return ret;
+}
+
+/**
+ * asn1_encode_oid() - encode an oid to ASN.1
+ * @data:	position to begin encoding at
+ * @end_data:	end of data pointer, points one beyond last usable byte in @data
+ * @oid:	array of oids
+ * @oid_len:	length of oid array
+ *
+ * this encodes an OID up to ASN.1 when presented as an array of OID values
+ */
+unsigned char *
+asn1_encode_oid(unsigned char *data, const unsigned char *end_data,
+		u32 oid[], int oid_len)
+{
+	int data_len = end_data - data;
+	unsigned char *d = data + 2;
+	int i, ret;
+
+	if (WARN(oid_len < 2, "OID must have at least two elements"))
+		return ERR_PTR(-EINVAL);
+
+	if (WARN(oid_len > 32, "OID is too large"))
+		return ERR_PTR(-EINVAL);
+
+	if (IS_ERR(data))
+		return data;
+
+
+	/* need at least 3 bytes for tag, length and OID encoding */
+	if (data_len < 3)
+		return ERR_PTR(-EINVAL);
+
+	data[0] = _tag(UNIV, PRIM, OID);
+	*d++ = oid[0] * 40 + oid[1];
+
+	data_len -= 3;
+
+	ret = 0;
+
+	for (i = 2; i < oid_len; i++) {
+		ret = asn1_encode_oid_digit(&d, &data_len, oid[i]);
+		if (ret < 0)
+			return ERR_PTR(ret);
+	}
+
+	data[1] = d - data - 2;
+
+	return d;
+}
+EXPORT_SYMBOL_GPL(asn1_encode_oid);
+
+static int asn1_encode_length(unsigned char **data, int *data_len, int len)
+{
+	if (*data_len < 1)
+		return -EINVAL;
+
+	if (len < 0) {
+		*((*data)++) = ASN1_INDEFINITE_LENGTH;
+		(*data_len)--;
+		return 0;
+	}
+
+	if (len <= 0x7f) {
+		*((*data)++) = len;
+		(*data_len)--;
+		return 0;
+	}
+
+	if (*data_len < 2)
+		return -EINVAL;
+
+	if (len <= 0xff) {
+		*((*data)++) = 0x81;
+		*((*data)++) = len & 0xff;
+		*data_len -= 2;
+		return 0;
+	}
+
+	if (*data_len < 3)
+		return -EINVAL;
+
+	if (len <= 0xffff) {
+		*((*data)++) = 0x82;
+		*((*data)++) = (len >> 8) & 0xff;
+		*((*data)++) = len & 0xff;
+		*data_len -= 3;
+		return 0;
+	}
+
+	if (WARN(len > 0xffffff, "ASN.1 length can't be > 0xffffff"))
+		return -EINVAL;
+
+	if (*data_len < 4)
+		return -EINVAL;
+	*((*data)++) = 0x83;
+	*((*data)++) = (len >> 16) & 0xff;
+	*((*data)++) = (len >> 8) & 0xff;
+	*((*data)++) = len & 0xff;
+	*data_len -= 4;
+
+	return 0;
+}
+
+/**
+ * asn1_encode_tag() - add a tag for optional or explicit value
+ * @data:	pointer to place tag at
+ * @end_data:	end of data pointer, points one beyond last usable byte in @data
+ * @tag:	tag to be placed
+ * @string:	the data to be tagged
+ * @len:	the length of the data to be tagged
+ *
+ * Note this currently only handles short form tags < 31.  To encode
+ * in place pass a NULL @string and -1 for @len; all this will do is
+ * add an indefinite length tag and update the data pointer to the
+ * place where the tag contents should be placed.  After the data is
+ * placed, repeat the prior statement but now with the known length.
+ * In order to avoid having to keep both before and after pointers,
+ * the repeat expects to be called with @data pointing to where the
+ * first encode placed it.
+ */
+unsigned char *
+asn1_encode_tag(unsigned char *data, const unsigned char *end_data,
+		u32 tag, const unsigned char *string, int len)
+{
+	int data_len = end_data - data;
+	int ret;
+
+	if (WARN(tag > 30, "ASN.1 tag can't be > 30"))
+		return ERR_PTR(-EINVAL);
+
+	if (!string && WARN(len > 127,
+			    "BUG: recode tag is too big (>127)"))
+		return ERR_PTR(-EINVAL);
+
+	if (IS_ERR(data))
+		return data;
+
+	if (!string && len > 0) {
+		/*
+		 * we're recoding, so move back to the start of the
+		 * tag and install a dummy length because the real
+		 * data_len should be NULL
+		 */
+		data -= 2;
+		data_len = 2;
+	}
+
+	if (data_len < 2)
+		return ERR_PTR(-EINVAL);
+
+	*(data++) = _tagn(CONT, CONS, tag);
+	data_len--;
+	ret = asn1_encode_length(&data, &data_len, len);
+	if (ret < 0)
+		return ERR_PTR(ret);
+
+	if (!string)
+		return data;
+
+	if (data_len < len)
+		return ERR_PTR(-EINVAL);
+
+	memcpy(data, string, len);
+	data += len;
+
+	return data;
+}
+EXPORT_SYMBOL_GPL(asn1_encode_tag);
+
+/**
+ * asn1_encode_octet_string() - encode an ASN.1 OCTET STRING
+ * @data:	pointer to encode at
+ * @end_data:	end of data pointer, points one beyond last usable byte in @data
+ * @string:	string to be encoded
+ * @len:	length of string
+ *
+ * Note ASN.1 octet strings may contain zeros, so the length is obligatory.
+ */
+unsigned char *
+asn1_encode_octet_string(unsigned char *data,
+			 const unsigned char *end_data,
+			 const unsigned char *string, u32 len)
+{
+	int data_len = end_data - data;
+	int ret;
+
+	if (IS_ERR(data))
+		return data;
+
+	/* need minimum of 2 bytes for tag and length of zero length string */
+	if (data_len < 2)
+		return ERR_PTR(-EINVAL);
+
+	*(data++) = _tag(UNIV, PRIM, OTS);
+	data_len--;
+
+	ret = asn1_encode_length(&data, &data_len, len);
+	if (ret)
+		return ERR_PTR(ret);
+
+	if (data_len < len)
+		return ERR_PTR(-EINVAL);
+
+	memcpy(data, string, len);
+	data += len;
+
+	return data;
+}
+EXPORT_SYMBOL_GPL(asn1_encode_octet_string);
+
+/**
+ * asn1_encode_sequence() - wrap a byte stream in an ASN.1 SEQUENCE
+ * @data:	pointer to encode at
+ * @end_data:	end of data pointer, points one beyond last usable byte in @data
+ * @seq:	data to be encoded as a sequence
+ * @len:	length of the data to be encoded as a sequence
+ *
+ * Fill in a sequence.  To encode in place, pass NULL for @seq and -1
+ * for @len; then call again once the length is known (still with NULL
+ * for @seq). In order to avoid having to keep both before and after
+ * pointers, the repeat expects to be called with @data pointing to
+ * where the first encode placed it.
+ */
+unsigned char *
+asn1_encode_sequence(unsigned char *data, const unsigned char *end_data,
+		     const unsigned char *seq, int len)
+{
+	int data_len = end_data - data;
+	int ret;
+
+	if (!seq && WARN(len > 127,
+			 "BUG: recode sequence is too big (>127)"))
+		return ERR_PTR(-EINVAL);
+
+	if (IS_ERR(data))
+		return data;
+
+	if (!seq && len >= 0) {
+		/*
+		 * we're recoding, so move back to the start of the
+		 * sequence and install a dummy length because the
+		 * real length should be NULL
+		 */
+		data -= 2;
+		data_len = 2;
+	}
+
+	if (data_len < 2)
+		return ERR_PTR(-EINVAL);
+
+	*(data++) = _tag(UNIV, CONS, SEQ);
+	data_len--;
+
+	ret = asn1_encode_length(&data, &data_len, len);
+	if (ret)
+		return ERR_PTR(ret);
+
+	if (!seq)
+		return data;
+
+	if (data_len < len)
+		return ERR_PTR(-EINVAL);
+
+	memcpy(data, seq, len);
+	data += len;
+
+	return data;
+}
+EXPORT_SYMBOL_GPL(asn1_encode_sequence);
+
+/**
+ * asn1_encode_boolean() - encode a boolean value to ASN.1
+ * @data:	pointer to encode at
+ * @end_data:	end of data pointer, points one beyond last usable byte in @data
+ * @val:	the boolean true/false value
+ */
+unsigned char *
+asn1_encode_boolean(unsigned char *data, const unsigned char *end_data,
+		    bool val)
+{
+	int data_len = end_data - data;
+
+	if (IS_ERR(data))
+		return data;
+
+	/* booleans are 3 bytes: tag, length == 1 and value == 0 or 1 */
+	if (data_len < 3)
+		return ERR_PTR(-EINVAL);
+
+	*(data++) = _tag(UNIV, PRIM, BOOL);
+	data_len--;
+
+	asn1_encode_length(&data, &data_len, 1);
+
+	if (val)
+		*(data++) = 1;
+	else
+		*(data++) = 0;
+
+	return data;
+}
+EXPORT_SYMBOL_GPL(asn1_encode_boolean);
-- 
2.16.4


^ permalink raw reply	[flat|nested] 19+ messages in thread

* [PATCH v8 2/8] oid_registry: Add TCG defined OIDS for TPM keys
  2020-03-10  5:15 [PATCH v8 0/8] TPM 2.0 trusted keys with attached policy James Bottomley
  2020-03-10  5:16 ` [PATCH v8 1/8] lib: add ASN.1 encoder James Bottomley
@ 2020-03-10  5:16 ` James Bottomley
  2020-03-10  5:16 ` [PATCH v8 3/8] security: keys: trusted: fix TPM2 authorizations James Bottomley
                   ` (8 subsequent siblings)
  10 siblings, 0 replies; 19+ messages in thread
From: James Bottomley @ 2020-03-10  5:16 UTC (permalink / raw)
  To: linux-integrity; +Cc: Mimi Zohar, Jarkko Sakkinen, David Woodhouse, keyrings

The TCG has defined an OID prefix "2.23.133.10.1" for the various TPM
key uses.  We've defined three of the available numbers:

2.23.133.10.1.3 TPM Loadable key.  This is an asymmetric key (Usually
		RSA2048 or Elliptic Curve) which can be imported by a
		TPM2_Load() operation.

2.23.133.10.1.4 TPM Importable Key.  This is an asymmetric key (Usually
		RSA2048 or Elliptic Curve) which can be imported by a
		TPM2_Import() operation.

Both loadable and importable keys are specific to a given TPM, the
difference is that a loadable key is wrapped with the symmetric
secret, so must have been created by the TPM itself.  An importable
key is wrapped with a DH shared secret, and may be created without
access to the TPM provided you know the public part of the parent key.

2.23.133.10.1.5 TPM Sealed Data.  This is a set of data (up to 128
		bytes) which is sealed by the TPM.  It usually
		represents a symmetric key and must be unsealed before
		use.

The ASN.1 binary key form starts of with this OID as the first element
of a sequence, giving the binary form a unique recognizable identity
marker regardless of encoding.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Acked-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

---

v3: correct OID_TPMImportableKey name
v7: add ack
---
 include/linux/oid_registry.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/linux/oid_registry.h b/include/linux/oid_registry.h
index 657d6bf2c064..f6e2276e5f30 100644
--- a/include/linux/oid_registry.h
+++ b/include/linux/oid_registry.h
@@ -107,6 +107,11 @@ enum OID {
 	OID_gostTC26Sign512B,		/* 1.2.643.7.1.2.1.2.2 */
 	OID_gostTC26Sign512C,		/* 1.2.643.7.1.2.1.2.3 */
 
+	/* TCG defined OIDS for TPM based keys */
+	OID_TPMLoadableKey,		/* 2.23.133.10.1.3 */
+	OID_TPMImportableKey,		/* 2.23.133.10.1.4 */
+	OID_TPMSealedData,		/* 2.23.133.10.1.5 */
+
 	OID__NR
 };
 
-- 
2.16.4


^ permalink raw reply	[flat|nested] 19+ messages in thread

* [PATCH v8 3/8] security: keys: trusted: fix TPM2 authorizations
  2020-03-10  5:15 [PATCH v8 0/8] TPM 2.0 trusted keys with attached policy James Bottomley
  2020-03-10  5:16 ` [PATCH v8 1/8] lib: add ASN.1 encoder James Bottomley
  2020-03-10  5:16 ` [PATCH v8 2/8] oid_registry: Add TCG defined OIDS for TPM keys James Bottomley
@ 2020-03-10  5:16 ` James Bottomley
  2020-03-10  5:16 ` [PATCH v8 4/8] security: keys: trusted: use ASN.1 TPM2 key format for the blobs James Bottomley
                   ` (7 subsequent siblings)
  10 siblings, 0 replies; 19+ messages in thread
From: James Bottomley @ 2020-03-10  5:16 UTC (permalink / raw)
  To: linux-integrity; +Cc: Mimi Zohar, Jarkko Sakkinen, David Woodhouse, keyrings

In TPM 1.2 an authorization was a 20 byte number.  The spec actually
recommended you to hash variable length passwords and use the sha1
hash as the authorization.  Because the spec doesn't require this
hashing, the current authorization for trusted keys is a 40 digit hex
number.  For TPM 2.0 the spec allows the passing in of variable length
passwords and passphrases directly, so we should allow that in trusted
keys for ease of use.  Update the 'blobauth' parameter to take this
into account, so we can now use plain text passwords for the keys.

so before

keyctl add trusted kmk "new 32 blobauth=f572d396fae9206628714fb2ce00f72e94f2258f"

after we will accept both the old hex sha1 form as well as a new
directly supplied password:

keyctl add trusted kmk "new 32 blobauth=hello keyhandle=81000001"

Since a sha1 hex code must be exactly 40 bytes long and a direct
password must be 20 or less, we use the length as the discriminator
for which form is input.

Note this is both and enhancement and a potential bug fix.  The TPM
2.0 spec requires us to strip leading zeros, meaning empyty
authorization is a zero length HMAC whereas we're currently passing in
20 bytes of zeros.  A lot of TPMs simply accept this as OK, but the
Microsoft TPM emulator rejects it with TPM_RC_BAD_AUTH, so this patch
makes the Microsoft TPM emulator work with trusted keys.

Fixes: 0fe5480303a1 ("keys, trusted: seal/unseal with TPM 2.0 chips")
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

---

v6: change comment, eliminate else clauses and add fixes tag
v7: fixes before signoff
---
 include/keys/trusted-type.h               |  1 +
 security/keys/trusted-keys/trusted_tpm1.c | 32 +++++++++++++++++++++++++------
 security/keys/trusted-keys/trusted_tpm2.c | 10 ++++++----
 3 files changed, 33 insertions(+), 10 deletions(-)

diff --git a/include/keys/trusted-type.h b/include/keys/trusted-type.h
index a94c03a61d8f..b2ed3481c6a0 100644
--- a/include/keys/trusted-type.h
+++ b/include/keys/trusted-type.h
@@ -30,6 +30,7 @@ struct trusted_key_options {
 	uint16_t keytype;
 	uint32_t keyhandle;
 	unsigned char keyauth[TPM_DIGEST_SIZE];
+	uint32_t blobauth_len;
 	unsigned char blobauth[TPM_DIGEST_SIZE];
 	uint32_t pcrinfo_len;
 	unsigned char pcrinfo[MAX_PCRINFO_SIZE];
diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c
index d2c5ec1e040b..add9f071d818 100644
--- a/security/keys/trusted-keys/trusted_tpm1.c
+++ b/security/keys/trusted-keys/trusted_tpm1.c
@@ -781,13 +781,33 @@ static int getoptions(char *c, struct trusted_key_payload *pay,
 				return -EINVAL;
 			break;
 		case Opt_blobauth:
-			if (strlen(args[0].from) != 2 * SHA1_DIGEST_SIZE)
-				return -EINVAL;
-			res = hex2bin(opt->blobauth, args[0].from,
-				      SHA1_DIGEST_SIZE);
-			if (res < 0)
-				return -EINVAL;
+			/*
+			 * TPM 1.2 authorizations are sha1 hashes passed in as
+			 * hex strings.  TPM 2.0 authorizations are simple
+			 * passwords (although it can take a hash as well)
+			 */
+			opt->blobauth_len = strlen(args[0].from);
+
+			if (opt->blobauth_len == 2 * TPM_DIGEST_SIZE) {
+				res = hex2bin(opt->blobauth, args[0].from,
+					      TPM_DIGEST_SIZE);
+				if (res < 0)
+					return -EINVAL;
+
+				opt->blobauth_len = TPM_DIGEST_SIZE;
+				return 0;
+			}
+
+			if (tpm2 && opt->blobauth_len <= sizeof(opt->blobauth)) {
+				memcpy(opt->blobauth, args[0].from,
+				       opt->blobauth_len);
+				return 0;
+			}
+
+			return -EINVAL;
+
 			break;
+
 		case Opt_migratable:
 			if (*args[0].from == '0')
 				pay->migratable = 0;
diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index 08ec7f48f01d..b4a5058107c2 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -91,10 +91,12 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 			     TPM_DIGEST_SIZE);
 
 	/* sensitive */
-	tpm_buf_append_u16(&buf, 4 + TPM_DIGEST_SIZE + payload->key_len + 1);
+	tpm_buf_append_u16(&buf, 4 + options->blobauth_len + payload->key_len + 1);
+
+	tpm_buf_append_u16(&buf, options->blobauth_len);
+	if (options->blobauth_len)
+		tpm_buf_append(&buf, options->blobauth, options->blobauth_len);
 
-	tpm_buf_append_u16(&buf, TPM_DIGEST_SIZE);
-	tpm_buf_append(&buf, options->blobauth, TPM_DIGEST_SIZE);
 	tpm_buf_append_u16(&buf, payload->key_len + 1);
 	tpm_buf_append(&buf, payload->key, payload->key_len);
 	tpm_buf_append_u8(&buf, payload->migratable);
@@ -258,7 +260,7 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 			     NULL /* nonce */, 0,
 			     TPM2_SA_CONTINUE_SESSION,
 			     options->blobauth /* hmac */,
-			     TPM_DIGEST_SIZE);
+			     options->blobauth_len);
 
 	rc = tpm_send(chip, buf.data, tpm_buf_length(&buf));
 	if (rc > 0)
-- 
2.16.4


^ permalink raw reply	[flat|nested] 19+ messages in thread

* [PATCH v8 4/8] security: keys: trusted: use ASN.1 TPM2 key format for the blobs
  2020-03-10  5:15 [PATCH v8 0/8] TPM 2.0 trusted keys with attached policy James Bottomley
                   ` (2 preceding siblings ...)
  2020-03-10  5:16 ` [PATCH v8 3/8] security: keys: trusted: fix TPM2 authorizations James Bottomley
@ 2020-03-10  5:16 ` James Bottomley
  2020-03-10  5:16 ` [PATCH v8 5/8] security: keys: trusted: Make sealed key properly interoperable James Bottomley
                   ` (6 subsequent siblings)
  10 siblings, 0 replies; 19+ messages in thread
From: James Bottomley @ 2020-03-10  5:16 UTC (permalink / raw)
  To: linux-integrity; +Cc: Mimi Zohar, Jarkko Sakkinen, David Woodhouse, keyrings

Modify the TPM2 key format blob output to export and import in the
ASN.1 form for TPM2 sealed object keys.  For compatibility with prior
trusted keys, the importer will also accept two TPM2B quantities
representing the public and private parts of the key.  However, the
export via keyctl pipe will only output the ASN.1 format.

The benefit of the ASN.1 format is that it's a standard and thus the
exported key can be used by userspace tools (openssl_tpm2_engine,
openconnect and tpm2-tss-engine).  The format includes policy
specifications, thus it gets us out of having to construct policy
handles in userspace and the format includes the parent meaning you
don't have to keep passing it in each time.

This patch only implements basic handling for the ASN.1 format, so
keys with passwords but no policy.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

---
v2: Updated encode API, added length checks
v5: correct export format after doing interoperability checks
v7: use prefix tpm2_key_ instead of tpmkey_ for functions
v8: resplit commit
---
 include/keys/trusted-type.h               |   1 +
 security/keys/trusted-keys/Makefile       |   2 +-
 security/keys/trusted-keys/tpm2key.asn1   |  23 ++++
 security/keys/trusted-keys/trusted_tpm1.c |   2 +-
 security/keys/trusted-keys/trusted_tpm2.c | 207 +++++++++++++++++++++++++++++-
 5 files changed, 227 insertions(+), 8 deletions(-)
 create mode 100644 security/keys/trusted-keys/tpm2key.asn1

diff --git a/include/keys/trusted-type.h b/include/keys/trusted-type.h
index b2ed3481c6a0..b2d87ad21714 100644
--- a/include/keys/trusted-type.h
+++ b/include/keys/trusted-type.h
@@ -22,6 +22,7 @@ struct trusted_key_payload {
 	unsigned int key_len;
 	unsigned int blob_len;
 	unsigned char migratable;
+	unsigned char old_format;
 	unsigned char key[MAX_KEY_SIZE + 1];
 	unsigned char blob[MAX_BLOB_SIZE];
 };
diff --git a/security/keys/trusted-keys/Makefile b/security/keys/trusted-keys/Makefile
index 7b73cebbb378..e0198641eff2 100644
--- a/security/keys/trusted-keys/Makefile
+++ b/security/keys/trusted-keys/Makefile
@@ -5,4 +5,4 @@
 
 obj-$(CONFIG_TRUSTED_KEYS) += trusted.o
 trusted-y += trusted_tpm1.o
-trusted-y += trusted_tpm2.o
+trusted-y += trusted_tpm2.o tpm2key.asn1.o
diff --git a/security/keys/trusted-keys/tpm2key.asn1 b/security/keys/trusted-keys/tpm2key.asn1
new file mode 100644
index 000000000000..660b3fa917ae
--- /dev/null
+++ b/security/keys/trusted-keys/tpm2key.asn1
@@ -0,0 +1,23 @@
+---
+--- Note: This isn't quite the definition in the standard
+---       However, the Linux asn.1 parser doesn't understand
+---       [2] EXPLICIT SEQUENCE OF OPTIONAL
+---       So there's an extra intermediate TPMPolicySequence
+---       definition to work around this
+
+TPMKey ::= SEQUENCE {
+	type		OBJECT IDENTIFIER ({tpm2_key_type}),
+	emptyAuth	[0] EXPLICIT BOOLEAN OPTIONAL,
+	policy		[1] EXPLICIT TPMPolicySequence OPTIONAL,
+	secret		[2] EXPLICIT OCTET STRING OPTIONAL,
+	parent		INTEGER ({tpm2_key_parent}),
+	pubkey		OCTET STRING ({tpm2_key_pub}),
+	privkey		OCTET STRING ({tpm2_key_priv})
+	}
+
+TPMPolicySequence ::= SEQUENCE OF TPMPolicy
+
+TPMPolicy ::= SEQUENCE {
+	commandCode		[0] EXPLICIT INTEGER,
+	commandPolicy		[1] EXPLICIT OCTET STRING
+	}
diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c
index add9f071d818..77e16caa6a65 100644
--- a/security/keys/trusted-keys/trusted_tpm1.c
+++ b/security/keys/trusted-keys/trusted_tpm1.c
@@ -1011,7 +1011,7 @@ static int trusted_instantiate(struct key *key,
 		goto out;
 	}
 
-	if (!options->keyhandle) {
+	if (!options->keyhandle && !tpm2) {
 		ret = -EINVAL;
 		goto out;
 	}
diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index b4a5058107c2..e8dcc47b3388 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -4,6 +4,8 @@
  * Copyright (C) 2014 Intel Corporation
  */
 
+#include <linux/asn1_encoder.h>
+#include <linux/oid_registry.h>
 #include <linux/string.h>
 #include <linux/err.h>
 #include <linux/tpm.h>
@@ -12,6 +14,10 @@
 #include <keys/trusted-type.h>
 #include <keys/trusted_tpm.h>
 
+#include <asm/unaligned.h>
+
+#include "tpm2key.asn1.h"
+
 static struct tpm2_hash tpm2_hash_map[] = {
 	{HASH_ALGO_SHA1, TPM_ALG_SHA1},
 	{HASH_ALGO_SHA256, TPM_ALG_SHA256},
@@ -20,6 +26,165 @@ static struct tpm2_hash tpm2_hash_map[] = {
 	{HASH_ALGO_SM3_256, TPM_ALG_SM3_256},
 };
 
+static u32 tpm2key_oid[] = { 2,23,133,10,1,5 };
+
+static int tpm2_key_encode(struct trusted_key_payload *payload,
+			   struct trusted_key_options *options,
+			   u8 *src, u32 len)
+{
+	const int SCRATCH_SIZE = PAGE_SIZE;
+	u8 *scratch = kmalloc(SCRATCH_SIZE, GFP_KERNEL);
+	u8 *work = scratch, *work1;
+	u8 *end_work = scratch + SCRATCH_SIZE;
+	u8 *priv, *pub;
+	u16 priv_len, pub_len;
+
+	priv_len = get_unaligned_be16(src) + 2;
+	priv = src;
+
+	src += priv_len;
+
+	pub_len = get_unaligned_be16(src) + 2;
+	pub = src;
+
+	if (!scratch)
+		return -ENOMEM;
+
+	work = asn1_encode_oid(work, end_work, tpm2key_oid,
+			       asn1_oid_len(tpm2key_oid));
+
+	if (options->blobauth_len == 0) {
+		unsigned char bool[3], *w = bool;
+		/* tag 0 is emptyAuth */
+		w = asn1_encode_boolean(w, w + sizeof(bool), true);
+		if (WARN(IS_ERR(w), "BUG: Boolean failed to encode"))
+			return PTR_ERR(w);
+		work = asn1_encode_tag(work, end_work, 0, bool, w - bool);
+	}
+
+	/*
+	 * Assume both octet strings will encode to a 2 byte definite length
+	 *
+	 * Note: For a well behaved TPM, this warning should never
+	 * trigger, so if it does there's something nefarious going on
+	 */
+	if (WARN(work - scratch + pub_len + priv_len + 14 > SCRATCH_SIZE,
+		 "BUG: scratch buffer is too small"))
+		return -EINVAL;
+
+	work = asn1_encode_integer(work, end_work, options->keyhandle);
+	work = asn1_encode_octet_string(work, end_work, pub, pub_len);
+	work = asn1_encode_octet_string(work, end_work, priv, priv_len);
+
+	work1 = payload->blob;
+	work1 = asn1_encode_sequence(work1, work1 + sizeof(payload->blob),
+				     scratch, work - scratch);
+	if (WARN(IS_ERR(work1), "BUG: ASN.1 encoder failed"))
+		return PTR_ERR(work1);
+
+	return work1 - payload->blob;
+}
+
+struct tpm2_key_context {
+	u32 parent;
+	const u8 *pub;
+	u32 pub_len;
+	const u8 *priv;
+	u32 priv_len;
+};
+
+static int tpm2_key_decode(struct trusted_key_payload *payload,
+			   struct trusted_key_options *options,
+			   u8 **buf)
+{
+	int ret;
+	struct tpm2_key_context ctx;
+	u8 *blob;
+
+	memset(&ctx, 0, sizeof(ctx));
+
+	ret = asn1_ber_decoder(&tpm2key_decoder, &ctx, payload->blob,
+			       payload->blob_len);
+	if (ret < 0)
+		return ret;
+
+	if (ctx.priv_len + ctx.pub_len > MAX_BLOB_SIZE)
+		return -EINVAL;
+
+	blob = kmalloc(ctx.priv_len + ctx.pub_len + 4, GFP_KERNEL);
+	if (!blob)
+		return -ENOMEM;
+
+	*buf = blob;
+	options->keyhandle = ctx.parent;
+
+	memcpy(blob, ctx.priv, ctx.priv_len);
+	blob += ctx.priv_len;
+
+	memcpy(blob, ctx.pub, ctx.pub_len);
+
+	return 0;
+}
+
+int tpm2_key_parent(void *context, size_t hdrlen,
+		  unsigned char tag,
+		  const void *value, size_t vlen)
+{
+	struct tpm2_key_context *ctx = context;
+	const u8 *v = value;
+	int i;
+
+	ctx->parent = 0;
+	for (i = 0; i < vlen; i++) {
+		ctx->parent <<= 8;
+		ctx->parent |= v[i];
+	}
+
+	return 0;
+}
+
+int tpm2_key_type(void *context, size_t hdrlen,
+		unsigned char tag,
+		const void *value, size_t vlen)
+{
+	enum OID oid = look_up_OID(value, vlen);
+
+	if (oid != OID_TPMSealedData) {
+		char buffer[50];
+
+		sprint_oid(value, vlen, buffer, sizeof(buffer));
+		pr_debug("OID is \"%s\" which is not TPMSealedData\n",
+			 buffer);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+int tpm2_key_pub(void *context, size_t hdrlen,
+	       unsigned char tag,
+	       const void *value, size_t vlen)
+{
+	struct tpm2_key_context *ctx = context;
+
+	ctx->pub = value;
+	ctx->pub_len = vlen;
+
+	return 0;
+}
+
+int tpm2_key_priv(void *context, size_t hdrlen,
+		unsigned char tag,
+		const void *value, size_t vlen)
+{
+	struct tpm2_key_context *ctx = context;
+
+	ctx->priv = value;
+	ctx->priv_len = vlen;
+
+	return 0;
+}
+
 /**
  * tpm_buf_append_auth() - append TPMS_AUTH_COMMAND to the buffer.
  *
@@ -79,6 +244,9 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 	if (i == ARRAY_SIZE(tpm2_hash_map))
 		return -EINVAL;
 
+	if (!options->keyhandle)
+		return -EINVAL;
+
 	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE);
 	if (rc)
 		return rc;
@@ -146,8 +314,10 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 		goto out;
 	}
 
-	memcpy(payload->blob, &buf.data[TPM_HEADER_SIZE + 4], blob_len);
-	payload->blob_len = blob_len;
+	payload->blob_len =
+		tpm2_key_encode(payload, options,
+				&buf.data[TPM_HEADER_SIZE + 4],
+				blob_len);
 
 out:
 	tpm_buf_destroy(&buf);
@@ -158,6 +328,8 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 		else
 			rc = -EPERM;
 	}
+	if (payload->blob_len < 0)
+		return payload->blob_len;
 
 	return rc;
 }
@@ -184,13 +356,34 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
 	unsigned int private_len;
 	unsigned int public_len;
 	unsigned int blob_len;
+	u8 *blob;
 	int rc;
 
-	private_len = be16_to_cpup((__be16 *) &payload->blob[0]);
-	if (private_len > (payload->blob_len - 2))
+	rc = tpm2_key_decode(payload, options, &blob);
+	if (rc) {
+		/* old form */
+		blob = payload->blob;
+		payload->old_format = 1;
+	}
+
+	/* new format carries keyhandle but old format doesn't */
+	if (!options->keyhandle)
+		return -EINVAL;
+
+	/* must be big enough for at least the two be16 size counts */
+	if (payload->blob_len < 4)
+		return -EINVAL;
+
+	private_len = get_unaligned_be16(blob);
+
+	/* must be big enough for following public_len */
+	if (private_len + 2 + 2 > (payload->blob_len))
+		return -E2BIG;
+
+	public_len = get_unaligned_be16(blob + 2 + private_len);
+	if (private_len + 2 + public_len + 2 > payload->blob_len)
 		return -E2BIG;
 
-	public_len = be16_to_cpup((__be16 *) &payload->blob[2 + private_len]);
 	blob_len = private_len + public_len + 4;
 	if (blob_len > payload->blob_len)
 		return -E2BIG;
@@ -206,7 +399,7 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
 			     options->keyauth /* hmac */,
 			     TPM_DIGEST_SIZE);
 
-	tpm_buf_append(&buf, payload->blob, blob_len);
+	tpm_buf_append(&buf, blob, blob_len);
 
 	if (buf.flags & TPM_BUF_OVERFLOW) {
 		rc = -E2BIG;
@@ -219,6 +412,8 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
 			(__be32 *) &buf.data[TPM_HEADER_SIZE]);
 
 out:
+	if (blob != payload->blob)
+		kfree(blob);
 	tpm_buf_destroy(&buf);
 
 	if (rc > 0)
-- 
2.16.4


^ permalink raw reply	[flat|nested] 19+ messages in thread

* [PATCH v8 5/8] security: keys: trusted: Make sealed key properly interoperable
  2020-03-10  5:15 [PATCH v8 0/8] TPM 2.0 trusted keys with attached policy James Bottomley
                   ` (3 preceding siblings ...)
  2020-03-10  5:16 ` [PATCH v8 4/8] security: keys: trusted: use ASN.1 TPM2 key format for the blobs James Bottomley
@ 2020-03-10  5:16 ` James Bottomley
  2020-03-10  5:16 ` [PATCH v8 6/8] security: keys: trusted: add PCR policy to TPM2 keys James Bottomley
                   ` (5 subsequent siblings)
  10 siblings, 0 replies; 19+ messages in thread
From: James Bottomley @ 2020-03-10  5:16 UTC (permalink / raw)
  To: linux-integrity; +Cc: Mimi Zohar, Jarkko Sakkinen, David Woodhouse, keyrings

The current implementation appends a migratable flag to the end of a
key, meaning the format isn't exactly interoperable because the using
party needs to know to strip this extra byte.  However, all other
consumers of TPM sealed blobs expect the unseal to return exactly the
key.  Since TPM2 keys have a key property flag that corresponds to
migratable, use that flag instead and make the actual key the only
sealed quantity.  This is secure because the key properties are bound
to a hash in the private part, so if they're altered the key won't
load.

Backwards compatibility is implemented by detecting whether we're
loading a new format key or not and correctly setting migratable from
the last byte of old format keys.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

---

v2: added length checks to untrusted payload
v8: recover patch
---
 include/linux/tpm.h                       |  2 ++
 security/keys/trusted-keys/trusted_tpm2.c | 53 ++++++++++++++++++++++---------
 2 files changed, 40 insertions(+), 15 deletions(-)

diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 03e9b184411b..cd46ab27baa5 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -297,6 +297,8 @@ struct tpm_buf {
 };
 
 enum tpm2_object_attributes {
+	TPM2_OA_FIXED_TPM		= BIT(1),
+	TPM2_OA_FIXED_PARENT		= BIT(4),
 	TPM2_OA_USER_WITH_AUTH		= BIT(6),
 };
 
diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index e8dcc47b3388..905c5ca4d51c 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -231,6 +231,7 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 	unsigned int blob_len;
 	struct tpm_buf buf;
 	u32 hash;
+	u32 flags;
 	int i;
 	int rc;
 
@@ -259,31 +260,32 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 			     TPM_DIGEST_SIZE);
 
 	/* sensitive */
-	tpm_buf_append_u16(&buf, 4 + options->blobauth_len + payload->key_len + 1);
+	tpm_buf_append_u16(&buf, 4 + options->blobauth_len + payload->key_len);
 
 	tpm_buf_append_u16(&buf, options->blobauth_len);
 	if (options->blobauth_len)
 		tpm_buf_append(&buf, options->blobauth, options->blobauth_len);
 
-	tpm_buf_append_u16(&buf, payload->key_len + 1);
+	tpm_buf_append_u16(&buf, payload->key_len);
 	tpm_buf_append(&buf, payload->key, payload->key_len);
-	tpm_buf_append_u8(&buf, payload->migratable);
 
 	/* public */
 	tpm_buf_append_u16(&buf, 14 + options->policydigest_len);
 	tpm_buf_append_u16(&buf, TPM_ALG_KEYEDHASH);
 	tpm_buf_append_u16(&buf, hash);
 
+	/* key properties */
+	flags = 0;
+	flags |= options->policydigest_len ? 0 : TPM2_OA_USER_WITH_AUTH;
+	flags |= payload->migratable ? (TPM2_OA_FIXED_TPM |
+					TPM2_OA_FIXED_PARENT) : 0;
+	tpm_buf_append_u32(&buf, flags);
+
 	/* policy */
-	if (options->policydigest_len) {
-		tpm_buf_append_u32(&buf, 0);
-		tpm_buf_append_u16(&buf, options->policydigest_len);
+	tpm_buf_append_u16(&buf, options->policydigest_len);
+	if (options->policydigest_len)
 		tpm_buf_append(&buf, options->policydigest,
 			       options->policydigest_len);
-	} else {
-		tpm_buf_append_u32(&buf, TPM2_OA_USER_WITH_AUTH);
-		tpm_buf_append_u16(&buf, 0);
-	}
 
 	/* public parameters */
 	tpm_buf_append_u16(&buf, TPM_ALG_NULL);
@@ -356,8 +358,9 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
 	unsigned int private_len;
 	unsigned int public_len;
 	unsigned int blob_len;
-	u8 *blob;
+	u8 *blob, *pub;
 	int rc;
+	u32 attrs;
 
 	rc = tpm2_key_decode(payload, options, &blob);
 	if (rc) {
@@ -384,6 +387,16 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
 	if (private_len + 2 + public_len + 2 > payload->blob_len)
 		return -E2BIG;
 
+	pub = blob + 2 + private_len + 2;
+	/* key attributes are always at offset 4 */
+	attrs = get_unaligned_be32(pub + 4);
+
+	if ((attrs & (TPM2_OA_FIXED_TPM | TPM2_OA_FIXED_PARENT)) ==
+	    (TPM2_OA_FIXED_TPM | TPM2_OA_FIXED_PARENT))
+		payload->migratable = 0;
+	else
+		payload->migratable = 1;
+
 	blob_len = private_len + public_len + 4;
 	if (blob_len > payload->blob_len)
 		return -E2BIG;
@@ -464,7 +477,7 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 	if (!rc) {
 		data_len = be16_to_cpup(
 			(__be16 *) &buf.data[TPM_HEADER_SIZE + 4]);
-		if (data_len < MIN_KEY_SIZE ||  data_len > MAX_KEY_SIZE + 1) {
+		if (data_len < MIN_KEY_SIZE ||  data_len > MAX_KEY_SIZE) {
 			rc = -EFAULT;
 			goto out;
 		}
@@ -475,9 +488,19 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 		}
 		data = &buf.data[TPM_HEADER_SIZE + 6];
 
-		memcpy(payload->key, data, data_len - 1);
-		payload->key_len = data_len - 1;
-		payload->migratable = data[data_len - 1];
+		if (payload->old_format) {
+			/* migratable flag is at the end of the key */
+			memcpy(payload->key, data, data_len - 1);
+			payload->key_len = data_len - 1;
+			payload->migratable = data[data_len - 1];
+		} else {
+			/*
+			 * migratable flag already collected from key
+			 * attributes
+			 */
+			memcpy(payload->key, data, data_len);
+			payload->key_len = data_len;
+		}
 	}
 
 out:
-- 
2.16.4


^ permalink raw reply	[flat|nested] 19+ messages in thread

* [PATCH v8 6/8] security: keys: trusted: add PCR policy to TPM2 keys
  2020-03-10  5:15 [PATCH v8 0/8] TPM 2.0 trusted keys with attached policy James Bottomley
                   ` (4 preceding siblings ...)
  2020-03-10  5:16 ` [PATCH v8 5/8] security: keys: trusted: Make sealed key properly interoperable James Bottomley
@ 2020-03-10  5:16 ` James Bottomley
  2020-03-10  5:16 ` [PATCH v8 7/8] security: keys: trusted: add ability to specify arbitrary policy James Bottomley
                   ` (4 subsequent siblings)
  10 siblings, 0 replies; 19+ messages in thread
From: James Bottomley @ 2020-03-10  5:16 UTC (permalink / raw)
  To: linux-integrity; +Cc: Mimi Zohar, Jarkko Sakkinen, David Woodhouse, keyrings

This commit adds the ability to specify a PCR lock policy to TPM2
keys.  There is a complexity in that the creator of the key must chose
either to use a PCR lock policy or to use authentication.  At the
current time they can't use both due to a complexity with the way
authentication works when policy registers are in use.  The way to
construct a pcrinfo statement for a key is simply to use the
TPMS_PCR_SELECT structure to specify the PCRs and follow this by a
hash of all their values in order of ascending PCR number.

For simplicity, we require the policy name hash and the hash used for
the PCRs to be the same.  Thus to construct a policy around the value
of the resettable PCR 16 using the sha1 bank, first reset the pcr to
zero giving a hash of all zeros as:

6768033e216468247bd031a0a2d9876d79818f8f

Then the TPMS_PCR_SELECT value for PCR 16 is

03000001

So create a new 32 byte key with a policy policy locking the key to
this value of PCR 16 with a parent key of 81000001 would be:

keyctl new 32 keyhandle=0x81000001 hash=sha1 pcrinfo=030000016768033e216468247bd
031a0a2d9876d79818f8f" @u

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

---

v2: fix for new ASN.1 API eliminating hack in place and check lengths
v8: recover patch and fix offsets for hash and size
---
 Documentation/security/keys/trusted-encrypted.rst |  19 +-
 include/keys/trusted-type.h                       |   5 +-
 include/linux/tpm.h                               |   5 +
 security/keys/Kconfig                             |   2 +
 security/keys/trusted-keys/Makefile               |   2 +-
 security/keys/trusted-keys/tpm2-policy.c          | 372 ++++++++++++++++++++++
 security/keys/trusted-keys/tpm2-policy.h          |  30 ++
 security/keys/trusted-keys/tpm2key.asn1           |   4 +-
 security/keys/trusted-keys/trusted_tpm1.c         |   7 +-
 security/keys/trusted-keys/trusted_tpm2.c         |  86 ++++-
 10 files changed, 516 insertions(+), 16 deletions(-)
 create mode 100644 security/keys/trusted-keys/tpm2-policy.c
 create mode 100644 security/keys/trusted-keys/tpm2-policy.h

diff --git a/Documentation/security/keys/trusted-encrypted.rst b/Documentation/security/keys/trusted-encrypted.rst
index 50ac8bcd6970..053344c4df5b 100644
--- a/Documentation/security/keys/trusted-encrypted.rst
+++ b/Documentation/security/keys/trusted-encrypted.rst
@@ -60,7 +60,10 @@ Usage::
                      (40 ascii zeros)
        blobauth=     ascii hex auth for sealed data default 0x00...
                      (40 ascii zeros)
-       pcrinfo=	     ascii hex of PCR_INFO or PCR_INFO_LONG (no default)
+       pcrinfo=      ascii hex of PCR_INFO or PCR_INFO_LONG (no
+                     default) on TPM 1.2 and a TPMS_PCR_SELECTION
+                     coupled with a hash of all the selected PCRs on
+                     TPM 2.0 using the selected hash.
        pcrlock=	     pcr number to be extended to "lock" blob
        migratable=   0|1 indicating permission to reseal to new PCR values,
                      default 1 (resealing allowed)
@@ -151,6 +154,20 @@ Load a trusted key from the saved blob::
     f1f8fff03ad0acb083725535636addb08d73dedb9832da198081e5deae84bfaf0409c22b
     e4a8aea2b607ec96931e6f4d4fe563ba
 
+Create a trusted key on TPM 2.0 using an all zero value of PCR16 and
+using the NV storage root 81000001 as the parent::
+
+    $ keyctl add trusted kmk "new 32 keyhandle=0x81000001 hash=sha1 pcrinfo=030000016768033e216468247bd031a0a2d9876d79818f8f" @u
+
+Note the TPMS_PCR_SELECT value for PCR 16 is 03000001 because all
+current TPMs have 24 PCRs, so the initial 03 says there are three
+following bytes of selection and then because the bytes are big
+endian, 16 is bit zero of byte 2. the hash is the sha1 sum of all
+zeros (the value of PCR 16)::
+
+    $ dd if=/dev/zero bs=1 count=20 2>/dev/null|sha1sum
+    6768033e216468247bd031a0a2d9876d79818f8f
+
 Reseal a trusted key under new pcr values::
 
     $ keyctl update 268728824 "update pcrinfo=`cat pcr.blob`"
diff --git a/include/keys/trusted-type.h b/include/keys/trusted-type.h
index b2d87ad21714..c117bf598230 100644
--- a/include/keys/trusted-type.h
+++ b/include/keys/trusted-type.h
@@ -14,9 +14,11 @@
 #define MIN_KEY_SIZE			32
 #define MAX_KEY_SIZE			128
 #define MAX_BLOB_SIZE			512
-#define MAX_PCRINFO_SIZE		64
+#define MAX_PCRINFO_SIZE		128
 #define MAX_DIGEST_SIZE			64
 
+#define TPM2_MAX_POLICIES		16
+
 struct trusted_key_payload {
 	struct rcu_head rcu;
 	unsigned int key_len;
@@ -25,6 +27,7 @@ struct trusted_key_payload {
 	unsigned char old_format;
 	unsigned char key[MAX_KEY_SIZE + 1];
 	unsigned char blob[MAX_BLOB_SIZE];
+	struct tpm2_policies *policies;
 };
 
 struct trusted_key_options {
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index cd46ab27baa5..e32e9728adce 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -222,10 +222,14 @@ enum tpm2_command_codes {
 	TPM2_CC_CONTEXT_LOAD	        = 0x0161,
 	TPM2_CC_CONTEXT_SAVE	        = 0x0162,
 	TPM2_CC_FLUSH_CONTEXT	        = 0x0165,
+	TPM2_CC_POLICY_AUTHVALUE	= 0x016B,
+	TPM2_CC_POLICY_COUNTER_TIMER	= 0x016D,
+	TPM2_CC_START_AUTH_SESS		= 0x0176,
 	TPM2_CC_VERIFY_SIGNATURE        = 0x0177,
 	TPM2_CC_GET_CAPABILITY	        = 0x017A,
 	TPM2_CC_GET_RANDOM	        = 0x017B,
 	TPM2_CC_PCR_READ	        = 0x017E,
+	TPM2_CC_POLICY_PCR		= 0x017F,
 	TPM2_CC_PCR_EXTEND	        = 0x0182,
 	TPM2_CC_EVENT_SEQUENCE_COMPLETE = 0x0185,
 	TPM2_CC_HASH_SEQUENCE_START     = 0x0186,
@@ -234,6 +238,7 @@ enum tpm2_command_codes {
 };
 
 enum tpm2_permanent_handles {
+	TPM2_RH_NULL		= 0x40000007,
 	TPM2_RS_PW		= 0x40000009,
 };
 
diff --git a/security/keys/Kconfig b/security/keys/Kconfig
index 47c041563d41..d65f7614709a 100644
--- a/security/keys/Kconfig
+++ b/security/keys/Kconfig
@@ -76,6 +76,8 @@ config TRUSTED_KEYS
 	select CRYPTO
 	select CRYPTO_HMAC
 	select CRYPTO_SHA1
+	select CRYPTO_SHA256
+	select CRYPTO_SHA512
 	select CRYPTO_HASH_INFO
 	help
 	  This option provides support for creating, sealing, and unsealing
diff --git a/security/keys/trusted-keys/Makefile b/security/keys/trusted-keys/Makefile
index e0198641eff2..194febacf362 100644
--- a/security/keys/trusted-keys/Makefile
+++ b/security/keys/trusted-keys/Makefile
@@ -5,4 +5,4 @@
 
 obj-$(CONFIG_TRUSTED_KEYS) += trusted.o
 trusted-y += trusted_tpm1.o
-trusted-y += trusted_tpm2.o tpm2key.asn1.o
+trusted-y += trusted_tpm2.o tpm2key.asn1.o tpm2-policy.o
diff --git a/security/keys/trusted-keys/tpm2-policy.c b/security/keys/trusted-keys/tpm2-policy.c
new file mode 100644
index 000000000000..080a76e879fd
--- /dev/null
+++ b/security/keys/trusted-keys/tpm2-policy.c
@@ -0,0 +1,372 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2019 James.Bottomley@HansenPartnership.com
+ */
+
+#include <linux/asn1_encoder.h>
+#include <linux/err.h>
+#include <linux/types.h>
+#include <linux/printk.h>
+#include <linux/string.h>
+#include <linux/tpm.h>
+
+#include <asm/unaligned.h>
+
+#include <crypto/hash.h>
+
+#include <keys/trusted-type.h>
+#include <keys/trusted_tpm.h>
+
+#include "tpm2key.asn1.h"
+#include "tpm2-policy.h"
+
+int tpm2_key_code(void *context, size_t hdrlen,
+		  unsigned char tag,
+		  const void *value, size_t vlen)
+{
+	struct tpm2_key_context *ctx = context;
+	u32 code = 0;
+	const u8 *v = value;
+	int i;
+
+	for (i = 0; i < vlen; i++) {
+		code <<= 8;
+		code |= v[i];
+	}
+
+	ctx->policy_code[ctx->policy_count] = code;
+
+	return 0;
+}
+
+int tpm2_key_policy(void *context, size_t hdrlen,
+		  unsigned char tag,
+		  const void *value, size_t vlen)
+{
+	struct tpm2_key_context *ctx = context;
+
+	ctx->policies[ctx->policy_count] = value;
+	ctx->policy_len[ctx->policy_count++] = vlen;
+
+	return 0;
+}
+
+/* we only support a limited number of policy statement so
+ * make sure we don't have anything we can't support
+ */
+static int tpm2_validate_policy(struct tpm2_policies *pols)
+{
+	int i;
+
+	if (pols->count == 0)
+		return 0;
+
+	for (i = 0; i < pols->count; i++) {
+		switch (pols->code[i]) {
+		case TPM2_CC_POLICY_COUNTER_TIMER:
+		case TPM2_CC_POLICY_PCR:
+		case TPM2_CC_POLICY_AUTHVALUE:
+			break;
+		default:
+			printk(KERN_INFO "tpm2 policy 0x%x is unsupported",
+			       pols->code[i]);
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * tpm2_key_process_policy - collect the policty from the context
+ * @ctx: the context to collect from
+ * @payload: the payload structure to place it in
+ *
+ * THis function sizes the policy statements and allocates space
+ * within the payload to receive them before copying them over.  It
+ * should be used after the ber decoder has completed successfully
+ */
+int tpm2_key_policy_process(struct tpm2_key_context *ctx,
+			    struct trusted_key_payload *payload)
+{
+	int tot_len = 0;
+	u8 *buf;
+	int i, ret, len = 0;
+	struct tpm2_policies *pols;
+
+	if (ctx->policy_count == 0)
+		return 0;
+
+	for (i = 0; i < ctx->policy_count; i++)
+		tot_len += ctx->policy_len[i];
+	tot_len += sizeof(*pols);
+
+	pols = kmalloc(tot_len, GFP_KERNEL);
+	if (!pols)
+		return -ENOMEM;
+
+	payload->policies = pols;
+	buf = (u8 *)(pols + 1);
+
+	for (i = 0; i < ctx->policy_count; i++) {
+		pols->policies[i] = &buf[len];
+		pols->len[i] = ctx->policy_len[i];
+		pols->code[i] = ctx->policy_code[i];
+		if (pols->len[i])
+			memcpy(pols->policies[i], ctx->policies[i],
+			       ctx->policy_len[i]);
+		len += ctx->policy_len[i];
+	}
+	pols->count = ctx->policy_count;
+
+	ret = tpm2_validate_policy(pols);
+	if (ret) {
+		kfree(pols);
+		payload->policies = NULL;
+	}
+
+	/* capture the hash and size */
+
+	/* the hash is the second algorithm */
+	pols->hash = get_unaligned_be16(&ctx->pub[4]);
+	/* and the digest appears after the attributes */
+	pols->hash_size = get_unaligned_be16(&ctx->pub[10]);
+
+	return ret;
+}
+
+int tpm2_generate_policy_digest(struct tpm2_policies *pols,
+				u32 hash, u8 *policydigest, u32 *plen)
+{
+	int i;
+	struct crypto_shash *tfm;
+	int rc;
+
+	if (pols->count == 0)
+		return 0;
+
+	tfm = crypto_alloc_shash(hash_algo_name[hash], 0, 0);
+	if (IS_ERR(tfm))
+		return PTR_ERR(tfm);
+
+	rc = crypto_shash_digestsize(tfm);
+	if (WARN(rc > MAX_DIGEST_SIZE,
+		 "BUG: trusted key code has alg %s with digest too large (%d)",
+		 hash_algo_name[hash], rc)) {
+		rc = -EINVAL;
+		goto err;
+	}
+
+	pols->hash = hash;
+	pols->hash_size = rc;
+	*plen = rc;
+
+	/* policy digests always start out all zeros */
+	memset(policydigest, 0, rc);
+
+	for (i = 0; i < pols->count; i++) {
+		u8 *policy = pols->policies[i];
+		int len = pols->len[i];
+		u32 cmd = pols->code[i];
+		u8 digest[MAX_DIGEST_SIZE];
+		u8 code[4];
+		SHASH_DESC_ON_STACK(sdesc, tfm);
+
+		sdesc->tfm = tfm;
+		rc = crypto_shash_init(sdesc);
+		if (rc)
+			goto err;
+
+		/* first hash the previous digest */
+		crypto_shash_update(sdesc, policydigest, *plen);
+
+		/* then hash the command code */
+		put_unaligned_be32(cmd, code);
+		crypto_shash_update(sdesc, code, 4);
+
+		/* commands that need special handling */
+		if (cmd == TPM2_CC_POLICY_COUNTER_TIMER) {
+			SHASH_DESC_ON_STACK(sdesc1, tfm);
+
+			sdesc1->tfm = tfm;
+
+			/* counter timer policies are double hashed */
+			crypto_shash_digest(sdesc1, policy, len,
+					    digest);
+			policy = digest;
+			len = *plen;
+		}
+
+		crypto_shash_update(sdesc, policy, len);
+
+		/* now output the intermediate to the policydigest */
+		crypto_shash_final(sdesc, policydigest);
+
+	}
+	rc = 0;
+
+ err:
+	crypto_free_shash(tfm);
+	return rc;
+}
+
+int tpm2_encode_policy(struct tpm2_policies *pols, u8 **data, u32 *len)
+{
+	const int SCRATCH_SIZE = PAGE_SIZE;
+	u8 *buf = kmalloc(2 * SCRATCH_SIZE, GFP_KERNEL);
+	u8 *work = buf + SCRATCH_SIZE;
+	u8 *ptr;
+	u8 *end_work = work + SCRATCH_SIZE;
+	int i, ret;
+
+	if (!buf)
+		return -ENOMEM;
+
+	for (i = 0; i < pols->count; i++) {
+		u8 *seq, *tag;
+		u32 cmd = pols->code[i];
+
+		if (WARN(work - buf + 14 + pols->len[i] > 2 * SCRATCH_SIZE,
+			 "BUG: scratch buffer is too small"))
+			return -EINVAL;
+
+		work = asn1_encode_sequence(work, end_work, NULL, -1);
+		seq = work;
+
+		work = asn1_encode_tag(work, end_work, 0, NULL, -1);
+		tag = work;
+
+		work = asn1_encode_integer(work, end_work, cmd);
+		asn1_encode_tag(tag, end_work, 0, NULL, work - tag);
+
+		work = asn1_encode_tag(work, end_work, 1, NULL, -1);
+		tag = work;
+
+		work = asn1_encode_octet_string(work, end_work,
+						pols->policies[i],
+						pols->len[i]);
+
+		asn1_encode_tag(tag, end_work, 1, NULL, work - tag);
+
+		seq = asn1_encode_sequence(seq, end_work, NULL, work - seq);
+		if (IS_ERR(seq)) {
+			ret = PTR_ERR(seq);
+			goto err;
+		}
+	}
+	ptr = asn1_encode_sequence(buf, buf + SCRATCH_SIZE, buf + PAGE_SIZE,
+				   work - buf - PAGE_SIZE);
+	if (IS_ERR(ptr)) {
+		ret = PTR_ERR(ptr);
+		goto err;
+	}
+
+	*data = buf;
+	*len = ptr - buf;
+
+	return 0;
+
+ err:
+	kfree(buf);
+	return ret;
+}
+
+int tpm2_start_policy_session(struct tpm_chip *chip, u16 hash, u32 *handle)
+{
+	struct tpm_buf buf;
+	int rc;
+	int i;
+
+	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_START_AUTH_SESS);
+	if (rc)
+		return rc;
+
+	/* NULL salt key handle */
+	tpm_buf_append_u32(&buf, TPM2_RH_NULL);
+
+	/* NULL bind key handle */
+	tpm_buf_append_u32(&buf, TPM2_RH_NULL);
+
+	/* empty nonce caller */
+	tpm_buf_append_u16(&buf, 20);
+	for (i = 0; i < 20; i++)
+		tpm_buf_append_u8(&buf, 0);
+
+	/* empty auth */
+	tpm_buf_append_u16(&buf, 0);
+
+	/* session type policy */
+	tpm_buf_append_u8(&buf, 0x01);
+
+	/* symmetric encryption parameters */
+
+	/* symmetric algorithm  */
+	tpm_buf_append_u16(&buf, TPM_ALG_NULL);
+
+	/* hash algorithm for session */
+	tpm_buf_append_u16(&buf, hash);
+
+	rc = tpm_send(chip, buf.data, tpm_buf_length(&buf));
+	if (rc)
+		goto out;
+
+	*handle = get_unaligned_be32(buf.data + TPM_HEADER_SIZE);
+
+ out:
+	tpm_buf_destroy(&buf);
+
+	return rc <= 0 ? rc : -EPERM;
+}
+
+int tpm2_get_policy_session(struct tpm_chip *chip, struct tpm2_policies *pols,
+			    u32 *handle)
+{
+	int i, rc;
+	const char *failure;
+
+	rc = tpm2_start_policy_session(chip, pols->hash, handle);
+	if (rc)
+		return rc;
+
+	for (i = 0; i < pols->count; i++) {
+		u32 cmd = pols->code[i];
+		struct tpm_buf buf;
+
+		rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, cmd);
+		if (rc)
+			return rc;
+
+		tpm_buf_append_u32(&buf, *handle);
+
+		switch (cmd) {
+		case TPM2_CC_POLICY_PCR:
+			failure = "PCR";
+			/*
+			 * for reasons best known to the TCG we have
+			 * to reverse the two arguments to send to the
+			 * policy command
+			 */
+			tpm_buf_append_u16(&buf, pols->hash_size);
+			tpm_buf_append(&buf, pols->policies[i] + pols->len[i] -
+				       pols->hash_size, pols->hash_size);
+			tpm_buf_append(&buf, pols->policies[i],
+				       pols->len[i] - pols->hash_size);
+			break;
+		default:
+			failure = "unknown policy";
+			break;
+		}
+
+		rc = tpm_send(chip, buf.data, tpm_buf_length(&buf));
+		tpm_buf_destroy(&buf);
+		if (rc) {
+			printk(KERN_NOTICE "TPM policy %s failed, rc=%d\n",
+			       failure, rc);
+			tpm2_flush_context(chip, *handle);
+			*handle = 0;
+			return -EPERM;
+		}
+	}
+
+	return 0;
+}
diff --git a/security/keys/trusted-keys/tpm2-policy.h b/security/keys/trusted-keys/tpm2-policy.h
new file mode 100644
index 000000000000..46bf1f0a9325
--- /dev/null
+++ b/security/keys/trusted-keys/tpm2-policy.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+struct tpm2_key_context {
+	u32 parent;
+	const u8 *pub;
+	u32 pub_len;
+	const u8 *priv;
+	u32 priv_len;
+	const u8 *policies[TPM2_MAX_POLICIES];
+	u32 policy_code[TPM2_MAX_POLICIES];
+	u16 policy_len[TPM2_MAX_POLICIES];
+	u8 policy_count;
+};
+
+struct tpm2_policies {
+	u32 code[TPM2_MAX_POLICIES];
+	u8 *policies[TPM2_MAX_POLICIES];
+	u16 len[TPM2_MAX_POLICIES];
+	u8 count;
+	u16 hash;
+	u16 hash_size;
+};
+
+int tpm2_key_policy_process(struct tpm2_key_context *ctx,
+			    struct trusted_key_payload *payload);
+int tpm2_generate_policy_digest(struct tpm2_policies *pols, u32 hash,
+				u8 *policydigest, u32 *plen);
+int tpm2_encode_policy(struct tpm2_policies *pols, u8 **data, u32 *len);
+int tpm2_get_policy_session(struct tpm_chip *chip, struct tpm2_policies *pols,
+			    u32 *handle);
diff --git a/security/keys/trusted-keys/tpm2key.asn1 b/security/keys/trusted-keys/tpm2key.asn1
index 660b3fa917ae..93e442d713fc 100644
--- a/security/keys/trusted-keys/tpm2key.asn1
+++ b/security/keys/trusted-keys/tpm2key.asn1
@@ -18,6 +18,6 @@ TPMKey ::= SEQUENCE {
 TPMPolicySequence ::= SEQUENCE OF TPMPolicy
 
 TPMPolicy ::= SEQUENCE {
-	commandCode		[0] EXPLICIT INTEGER,
-	commandPolicy		[1] EXPLICIT OCTET STRING
+	commandCode		[0] EXPLICIT INTEGER ({tpm2_key_code}),
+	commandPolicy		[1] EXPLICIT OCTET STRING ({tpm2_key_policy})
 	}
diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c
index 77e16caa6a65..08e7bb89f7bf 100644
--- a/security/keys/trusted-keys/trusted_tpm1.c
+++ b/security/keys/trusted-keys/trusted_tpm1.c
@@ -1065,6 +1065,7 @@ static void trusted_rcu_free(struct rcu_head *rcu)
 	struct trusted_key_payload *p;
 
 	p = container_of(rcu, struct trusted_key_payload, rcu);
+	kzfree(p->policies);
 	kzfree(p);
 }
 
@@ -1184,7 +1185,11 @@ static long trusted_read(const struct key *key, char __user *buffer,
  */
 static void trusted_destroy(struct key *key)
 {
-	kzfree(key->payload.data[0]);
+	struct trusted_key_payload *p;
+
+	p = key->payload.data[0];
+	kzfree(p->policies);
+	kzfree(p);
 }
 
 struct key_type key_type_trusted = {
diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index 905c5ca4d51c..98c65431ca75 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -17,6 +17,7 @@
 #include <asm/unaligned.h>
 
 #include "tpm2key.asn1.h"
+#include "tpm2-policy.h"
 
 static struct tpm2_hash tpm2_hash_map[] = {
 	{HASH_ALGO_SHA1, TPM_ALG_SHA1},
@@ -62,6 +63,21 @@ static int tpm2_key_encode(struct trusted_key_payload *payload,
 		work = asn1_encode_tag(work, end_work, 0, bool, w - bool);
 	}
 
+	if (payload->policies) {
+		u8 *encoded_pols;
+		u32 encoded_pol_len;
+		int ret;
+
+		ret = tpm2_encode_policy(payload->policies, &encoded_pols,
+					 &encoded_pol_len);
+		if (ret)
+			return ret;
+
+		work = asn1_encode_tag(work, end_work, 1, encoded_pols,
+				       encoded_pol_len);
+		kfree(encoded_pols);
+	}
+
 	/*
 	 * Assume both octet strings will encode to a 2 byte definite length
 	 *
@@ -85,14 +101,6 @@ static int tpm2_key_encode(struct trusted_key_payload *payload,
 	return work1 - payload->blob;
 }
 
-struct tpm2_key_context {
-	u32 parent;
-	const u8 *pub;
-	u32 pub_len;
-	const u8 *priv;
-	u32 priv_len;
-};
-
 static int tpm2_key_decode(struct trusted_key_payload *payload,
 			   struct trusted_key_options *options,
 			   u8 **buf)
@@ -115,6 +123,12 @@ static int tpm2_key_decode(struct trusted_key_payload *payload,
 	if (!blob)
 		return -ENOMEM;
 
+	ret = tpm2_key_policy_process(&ctx, payload);
+	if (ret) {
+		kfree(blob);
+		return ret;
+	}
+
 	*buf = blob;
 	options->keyhandle = ctx.parent;
 
@@ -248,6 +262,42 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 	if (!options->keyhandle)
 		return -EINVAL;
 
+	if (options->pcrinfo_len != 0) {
+		struct tpm2_policies *pols;
+		static u8 *scratch;
+		/* 4 array len, 2 hash alg */
+		const int len = 4 + 2 + options->pcrinfo_len;
+
+		pols = kmalloc(sizeof(*pols) + len, GFP_KERNEL);
+		if (!pols)
+			return -ENOMEM;
+
+		pols->count = 1;
+		pols->len[0] = len;
+		scratch = (u8 *)(pols + 1);
+		pols->policies[0] = scratch;
+		pols->code[0] = TPM2_CC_POLICY_PCR;
+
+		put_unaligned_be32(1, &scratch[0]);
+		put_unaligned_be16(hash, &scratch[4]);
+		memcpy(&scratch[6], options->pcrinfo, options->pcrinfo_len);
+		payload->policies = pols;
+	}
+
+	if (options->policydigest_len != 0 && payload->policies) {
+		/* can't specify both a digest and a policy */
+		return -EINVAL;
+	}
+
+	if (payload->policies) {
+		rc = tpm2_generate_policy_digest(payload->policies,
+						 options->hash,
+						 options->policydigest,
+						 &options->policydigest_len);
+		if (rc)
+			return rc;
+	}
+
 	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE);
 	if (rc)
 		return rc;
@@ -456,21 +506,37 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 	u16 data_len;
 	u8 *data;
 	int rc;
+	u32 policyhandle;
+
+	if (payload->policies && options->policyhandle)
+		/* can't have both a passed in policy and a key resident one */
+		return -EINVAL;
 
 	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL);
 	if (rc)
 		return rc;
 
+	if (payload->policies) {
+		rc = tpm2_get_policy_session(chip, payload->policies,
+					     &policyhandle);
+		if (rc)
+			return rc;
+	} else {
+		policyhandle = options->policyhandle;
+	}
+
 	tpm_buf_append_u32(&buf, blob_handle);
 	tpm2_buf_append_auth(&buf,
-			     options->policyhandle ?
-			     options->policyhandle : TPM2_RS_PW,
+			     policyhandle ?
+			     policyhandle : TPM2_RS_PW,
 			     NULL /* nonce */, 0,
 			     TPM2_SA_CONTINUE_SESSION,
 			     options->blobauth /* hmac */,
 			     options->blobauth_len);
 
 	rc = tpm_send(chip, buf.data, tpm_buf_length(&buf));
+	if (payload->policies)
+		tpm2_flush_context(chip, policyhandle);
 	if (rc > 0)
 		rc = -EPERM;
 
-- 
2.16.4


^ permalink raw reply	[flat|nested] 19+ messages in thread

* [PATCH v8 7/8] security: keys: trusted: add ability to specify arbitrary policy
  2020-03-10  5:15 [PATCH v8 0/8] TPM 2.0 trusted keys with attached policy James Bottomley
                   ` (5 preceding siblings ...)
  2020-03-10  5:16 ` [PATCH v8 6/8] security: keys: trusted: add PCR policy to TPM2 keys James Bottomley
@ 2020-03-10  5:16 ` James Bottomley
  2020-03-10  5:16 ` [PATCH v8 8/8] security: keys: trusted: implement counter/timer policy James Bottomley
                   ` (3 subsequent siblings)
  10 siblings, 0 replies; 19+ messages in thread
From: James Bottomley @ 2020-03-10  5:16 UTC (permalink / raw)
  To: linux-integrity; +Cc: Mimi Zohar, Jarkko Sakkinen, David Woodhouse, keyrings

This patch adds a policy= argument to key creation.  The policy is the
standard tss policymaker format and each separate policy line must
have a newline after it.

Thus to construct a policy requiring authorized value and pcr 16
locking using a sha256 hash, the policy (policy.txt) file would be two
lines:

0000017F00000001000B03000001303095B49BE85E381E5B20E557E46363EF55B0F43B132C2D8E3DE9AC436656F2
0000016b

This can be inserted into the key with

keyctl add trusted kmk "new 32 policy=`cat policy.txt` keyhandle=0x81000001 hash=sha256" @u

Note that although a few policies work like this, most require special
handling which must be added to the kernel policy construction
routine.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
---
 Documentation/security/keys/trusted-encrypted.rst | 16 +++++++
 security/keys/trusted-keys/tpm2-policy.c          | 53 +++++++++++++++++++++++
 security/keys/trusted-keys/tpm2-policy.h          |  1 +
 security/keys/trusted-keys/trusted_tpm1.c         | 15 +++++++
 4 files changed, 85 insertions(+)

diff --git a/Documentation/security/keys/trusted-encrypted.rst b/Documentation/security/keys/trusted-encrypted.rst
index 053344c4df5b..b68d3eb73f00 100644
--- a/Documentation/security/keys/trusted-encrypted.rst
+++ b/Documentation/security/keys/trusted-encrypted.rst
@@ -76,6 +76,9 @@ Usage::
        policyhandle= handle to an authorization policy session that defines the
                      same policy and with the same hash algorithm as was used to
                      seal the key.
+       policy=       specify an arbitrary set of policies.  These must
+                     be in policymaker format with each separate
+                     policy line newline terminated.
 
 "keyctl print" returns an ascii hex copy of the sealed key, which is in standard
 TPM_STORED_DATA format.  The key length for new keys are always in bytes.
@@ -168,6 +171,19 @@ zeros (the value of PCR 16)::
     $ dd if=/dev/zero bs=1 count=20 2>/dev/null|sha1sum
     6768033e216468247bd031a0a2d9876d79818f8f
 
+You can also specify arbitrary policy in policymaker format, so a two
+value policy (the pcr example above and authvalue) would look like
+this in policymaker format::
+
+    0000017F000000010004030000016768033e216468247bd031a0a2d9876d79818f8f
+    0000016b
+
+This can be placed in a file (say policy.txt) and then added to the key as::
+
+    $ keyctl add trusted kmk "new 32 keyhandle=0x81000001 hash=sha1 policy=`cat policy.txt`" @u
+
+The newlines in the file policy.txt will be automatically processed.
+
 Reseal a trusted key under new pcr values::
 
     $ keyctl update 268728824 "update pcrinfo=`cat pcr.blob`"
diff --git a/security/keys/trusted-keys/tpm2-policy.c b/security/keys/trusted-keys/tpm2-policy.c
index 080a76e879fd..87a13e607eca 100644
--- a/security/keys/trusted-keys/tpm2-policy.c
+++ b/security/keys/trusted-keys/tpm2-policy.c
@@ -370,3 +370,56 @@ int tpm2_get_policy_session(struct tpm_chip *chip, struct tpm2_policies *pols,
 
 	return 0;
 }
+
+int tpm2_parse_policies(struct tpm2_policies **ppols, char *str)
+{
+	struct tpm2_policies *pols;
+	char *p;
+	u8 *ptr;
+	int i = 0, left = PAGE_SIZE, res;
+
+	pols = kmalloc(left, GFP_KERNEL);
+	if (!pols)
+		return -ENOMEM;
+
+	ptr = (u8 *)(pols + 1);
+	left -= ptr - (u8 *)pols;
+
+	while ((p = strsep(&str, "\n"))) {
+		if (*p == '\0' || *p == '\n')
+			continue;
+
+		pols->len[i] = strlen(p)/2;
+		if (pols->len[i] > left) {
+			res = -E2BIG;
+			goto err;
+		}
+
+		res = hex2bin(ptr, p, pols->len[i]);
+		if (res)
+			goto err;
+
+		/* get command code and skip past */
+		pols->code[i] = get_unaligned_be32(ptr);
+		pols->policies[i] = ptr + 4;
+		ptr += pols->len[i];
+		left -= pols->len[i];
+		pols->len[i] -= 4;
+
+		/*
+		 * FIXME: this does leave the code embedded in dead
+		 * regions of the memory, but it's easier than
+		 * hexdumping to a temporary or copying over
+		 */
+		i++;
+	}
+
+	pols->count = i;
+	*ppols = pols;
+
+	return 0;
+
+ err:
+	kfree(pols);
+	return res;
+}
diff --git a/security/keys/trusted-keys/tpm2-policy.h b/security/keys/trusted-keys/tpm2-policy.h
index 46bf1f0a9325..0da013116c1c 100644
--- a/security/keys/trusted-keys/tpm2-policy.h
+++ b/security/keys/trusted-keys/tpm2-policy.h
@@ -28,3 +28,4 @@ int tpm2_generate_policy_digest(struct tpm2_policies *pols, u32 hash,
 int tpm2_encode_policy(struct tpm2_policies *pols, u8 **data, u32 *len);
 int tpm2_get_policy_session(struct tpm_chip *chip, struct tpm2_policies *pols,
 			    u32 *handle);
+int tpm2_parse_policies(struct tpm2_policies **ppols, char *str);
diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c
index 08e7bb89f7bf..242181c6304b 100644
--- a/security/keys/trusted-keys/trusted_tpm1.c
+++ b/security/keys/trusted-keys/trusted_tpm1.c
@@ -29,6 +29,8 @@
 
 #include <keys/trusted_tpm.h>
 
+#include "tpm2-policy.h"
+
 static const char hmac_alg[] = "hmac(sha1)";
 static const char hash_alg[] = "sha1";
 static struct tpm_chip *chip;
@@ -709,6 +711,7 @@ enum {
 	Opt_hash,
 	Opt_policydigest,
 	Opt_policyhandle,
+	Opt_policy,
 };
 
 static const match_table_t key_tokens = {
@@ -724,6 +727,7 @@ static const match_table_t key_tokens = {
 	{Opt_hash, "hash=%s"},
 	{Opt_policydigest, "policydigest=%s"},
 	{Opt_policyhandle, "policyhandle=%s"},
+	{Opt_policy, "policy=%s"},
 	{Opt_err, NULL}
 };
 
@@ -854,6 +858,17 @@ static int getoptions(char *c, struct trusted_key_payload *pay,
 				return -EINVAL;
 			opt->policyhandle = handle;
 			break;
+
+		case Opt_policy:
+			if (pay->policies)
+				return -EINVAL;
+			if (!tpm2)
+				return -EINVAL;
+			res = tpm2_parse_policies(&pay->policies, args[0].from);
+			if (res)
+				return res;
+			break;
+
 		default:
 			return -EINVAL;
 		}
-- 
2.16.4


^ permalink raw reply	[flat|nested] 19+ messages in thread

* [PATCH v8 8/8] security: keys: trusted: implement counter/timer policy
  2020-03-10  5:15 [PATCH v8 0/8] TPM 2.0 trusted keys with attached policy James Bottomley
                   ` (6 preceding siblings ...)
  2020-03-10  5:16 ` [PATCH v8 7/8] security: keys: trusted: add ability to specify arbitrary policy James Bottomley
@ 2020-03-10  5:16 ` James Bottomley
  2020-03-19 16:47 ` [PATCH v8 1/8] lib: add ASN.1 encoder David Howells
                   ` (2 subsequent siblings)
  10 siblings, 0 replies; 19+ messages in thread
From: James Bottomley @ 2020-03-10  5:16 UTC (permalink / raw)
  To: linux-integrity; +Cc: Mimi Zohar, Jarkko Sakkinen, David Woodhouse, keyrings

This is actually a generic policy allowing a range of comparisons
against any value set in the TPM Clock, which includes things like the
reset count, a monotonic millisecond count and the restart count.  The
most useful comparison is against the millisecond count for expiring
keys.  However, you have to remember that currently Linux doesn't try
to sync the epoch timer with the TPM, so the expiration is actually
measured in how long the TPM itself has been powered on ... the TPM
timer doesn't count while the system is powered down.  The millisecond
counter is a u64 quantity found at offset 8 in the timer structure,
and the <= comparision operand is 9, so a policy set to expire after the
TPM has been up for 100 seconds would look like

0000016d00000000000f424000080009

Where 0x16d is the counter timer policy code and 0xf4240 is 100 000 in
hex.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
---
 Documentation/security/keys/trusted-encrypted.rst | 29 ++++++++++++++++
 include/linux/tpm.h                               |  1 +
 security/keys/trusted-keys/tpm2-policy.c          | 40 ++++++++++++++++++++++-
 security/keys/trusted-keys/trusted_tpm2.c         | 36 +++++++++++++++++++-
 4 files changed, 104 insertions(+), 2 deletions(-)

diff --git a/Documentation/security/keys/trusted-encrypted.rst b/Documentation/security/keys/trusted-encrypted.rst
index b68d3eb73f00..53a6196c7df9 100644
--- a/Documentation/security/keys/trusted-encrypted.rst
+++ b/Documentation/security/keys/trusted-encrypted.rst
@@ -241,3 +241,32 @@ about the usage can be found in the file
 Another new format 'enc32' has been defined in order to support encrypted keys
 with payload size of 32 bytes. This will initially be used for nvdimm security
 but may expand to other usages that require 32 bytes payload.
+
+Appendix
+--------
+
+TPM 2.0 Policies
+----------------
+
+The current TPM supports PCR lock policies as documented above and
+CounterTimer policies which can be used to create expiring keys.  One
+caveat with expiring keys is that the TPM millisecond counter does not
+update while a system is powered off and Linux does not sync the TPM
+millisecond count with its internal clock, so the best you can expire
+in is in terms of how long any given TPM has been powered on.  (FIXME:
+Linux should simply update the millisecond clock to the current number
+of seconds past the epoch on boot).
+
+A CounterTimer policy is expressed in terms of length and offset
+against the TPM clock structure (TPMS_TIME_INFO), which looks like the
+packed structure::
+
+    struct tpms_time_info {
+            u64 uptime;       /* time in ms since last start or reset */
+	    u64 clock;        /* cumulative uptime in ms */
+	    u32 resetcount;   /* numer of times the TPM has been reset */
+	    u32 restartcount; /* number of times the TPM has been restarted */
+	    u8  safe          /* time was safely loaded from NVRam */
+    };
+
+The usual comparison for expiring keys is against clock, at offset 8.
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index e32e9728adce..5026a06977e1 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -233,6 +233,7 @@ enum tpm2_command_codes {
 	TPM2_CC_PCR_EXTEND	        = 0x0182,
 	TPM2_CC_EVENT_SEQUENCE_COMPLETE = 0x0185,
 	TPM2_CC_HASH_SEQUENCE_START     = 0x0186,
+	TPM2_CC_POLICY_PASSWORD		= 0x018c,
 	TPM2_CC_CREATE_LOADED           = 0x0191,
 	TPM2_CC_LAST		        = 0x0193, /* Spec 1.36 */
 };
diff --git a/security/keys/trusted-keys/tpm2-policy.c b/security/keys/trusted-keys/tpm2-policy.c
index 87a13e607eca..bd8eb02e1094 100644
--- a/security/keys/trusted-keys/tpm2-policy.c
+++ b/security/keys/trusted-keys/tpm2-policy.c
@@ -197,7 +197,8 @@ int tpm2_generate_policy_digest(struct tpm2_policies *pols,
 			len = *plen;
 		}
 
-		crypto_shash_update(sdesc, policy, len);
+		if (len)
+			crypto_shash_update(sdesc, policy, len);
 
 		/* now output the intermediate to the policydigest */
 		crypto_shash_final(sdesc, policydigest);
@@ -332,6 +333,16 @@ int tpm2_get_policy_session(struct tpm_chip *chip, struct tpm2_policies *pols,
 		u32 cmd = pols->code[i];
 		struct tpm_buf buf;
 
+		if (cmd == TPM2_CC_POLICY_AUTHVALUE)
+			/*
+			 * both PolicyAuthValue and PolicyPassword
+			 * hash to the same thing, but one triggers
+			 * HMAC authentication and the other simple
+			 * authentication.  Since we have no HMAC
+			 * code, we're choosing the simple
+			 */
+			cmd = TPM2_CC_POLICY_PASSWORD;
+
 		rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, cmd);
 		if (rc)
 			return rc;
@@ -352,8 +363,35 @@ int tpm2_get_policy_session(struct tpm_chip *chip, struct tpm2_policies *pols,
 			tpm_buf_append(&buf, pols->policies[i],
 				       pols->len[i] - pols->hash_size);
 			break;
+
+		case TPM2_CC_POLICY_COUNTER_TIMER: {
+			/*
+			 * the format of this is the last two u16
+			 * quantities are the offset and operation
+			 * respectively.  The rest is operandB which
+			 * must be zero padded in a hash digest
+			 */
+			u16 opb_len = pols->len[i] - 4;
+
+			if (opb_len > pols->hash_size)
+				return -EINVAL;
+
+			tpm_buf_append_u16(&buf, opb_len);
+			tpm_buf_append(&buf, pols->policies[i], opb_len);
+
+			/* offset and operand*/
+			tpm_buf_append(&buf, pols->policies[i] + opb_len, 4);
+			failure = "Counter Timer";
+
+			break;
+		}
+
 		default:
 			failure = "unknown policy";
+			if (pols->len[i])
+				tpm_buf_append(&buf, pols->policies[i],
+					       pols->len[i]);
+
 			break;
 		}
 
diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index 98c65431ca75..3ec01ed874d9 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -248,6 +248,7 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 	u32 flags;
 	int i;
 	int rc;
+	static const int POLICY_SIZE = 2 * PAGE_SIZE;
 
 	for (i = 0; i < ARRAY_SIZE(tpm2_hash_map); i++) {
 		if (options->hash == tpm2_hash_map[i].crypto_id) {
@@ -268,7 +269,7 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 		/* 4 array len, 2 hash alg */
 		const int len = 4 + 2 + options->pcrinfo_len;
 
-		pols = kmalloc(sizeof(*pols) + len, GFP_KERNEL);
+		pols = kmalloc(POLICY_SIZE, GFP_KERNEL);
 		if (!pols)
 			return -ENOMEM;
 
@@ -289,6 +290,39 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 		return -EINVAL;
 	}
 
+	/*
+	 * if we already have a policy, we have to add authorization
+	 * to it.  If we don't, we can simply follow the usual
+	 * non-policy route.
+	 */
+	if (options->blobauth_len != 0 && payload->policies) {
+		struct tpm2_policies *pols;
+		static u8 *scratch;
+		int i;
+		bool found = false;
+
+		pols = payload->policies;
+
+		/* make sure it's not already in policy */
+		for (i = 0; i < pols->count; i++) {
+			if (pols->code[i] == TPM2_CC_POLICY_AUTHVALUE) {
+				found = true;
+
+				break;
+			}
+		}
+
+		if (!found) {
+			i = pols->count++;
+			scratch = pols->policies[i - 1] + pols->len[i - 1];
+
+			/* the TPM2_PolicyPassword command has no payload */
+			pols->policies[i] = scratch;
+			pols->len[i] = 0;
+			pols->code[i] = TPM2_CC_POLICY_AUTHVALUE;
+		}
+	}
+
 	if (payload->policies) {
 		rc = tpm2_generate_policy_digest(payload->policies,
 						 options->hash,
-- 
2.16.4


^ permalink raw reply	[flat|nested] 19+ messages in thread

* Re: [PATCH v8 1/8] lib: add ASN.1 encoder
  2020-03-10  5:15 [PATCH v8 0/8] TPM 2.0 trusted keys with attached policy James Bottomley
                   ` (7 preceding siblings ...)
  2020-03-10  5:16 ` [PATCH v8 8/8] security: keys: trusted: implement counter/timer policy James Bottomley
@ 2020-03-19 16:47 ` David Howells
  2020-03-19 17:31   ` James Bottomley
  2020-03-19 19:12   ` David Howells
  2020-03-19 16:48 ` [PATCH v8 2/8] oid_registry: Add TCG defined OIDS for TPM keys David Howells
  2020-03-19 16:57 ` [PATCH v8 6/8] security: keys: trusted: add PCR policy to TPM2 keys David Howells
  10 siblings, 2 replies; 19+ messages in thread
From: David Howells @ 2020-03-19 16:47 UTC (permalink / raw)
  To: James Bottomley
  Cc: dhowells, linux-integrity, Mimi Zohar, Jarkko Sakkinen,
	David Woodhouse, keyrings

James Bottomley <James.Bottomley@HansenPartnership.com> wrote:

> + * Copyright (C) 2019 James.Bottomley@HansenPartnership.com

2020?

> +unsigned char *
> +asn1_encode_integer(unsigned char *data, const unsigned char *end_data,
> +		    s64 integer);

I wonder if we should actually use u8 rather than unsigned char for data
pointers like this.  That applies to asn1_ber_decoder() also.

You should be able to precalculate the length from fls64() or ilog2(), e.g.:

	static size_t asn1_uint_len(unsigned long long integer)
	{
		size_t l = integer ? fls64(integer) : 1;
		return l / 8 + 1;
	}

See attached toy program.

> +/**
> + * asn1_encode_tag() - add a tag for optional or explicit value
> + * @data:	pointer to place tag at
> + * @end_data:	end of data pointer, points one beyond last usable byte in @data
> + * @tag:	tag to be placed
> + * @string:	the data to be tagged
> + * @len:	the length of the data to be tagged
> + *
> + * Note this currently only handles short form tags < 31.  To encode
> + * in place pass a NULL @string and -1 for @len; all this will do is
> + * add an indefinite length tag and update the data pointer to the
> + * place where the tag contents should be placed.  After the data is
> + * placed, repeat the prior statement but now with the known length.
> + * In order to avoid having to keep both before and after pointers,
> + * the repeat expects to be called with @data pointing to where the
> + * first encode placed it.
> + */

I wonder if it's worth appending a note to the comment that if indefinite
length encoding is selected, then the result is not DER-compliant and may not
be CER-compliant since you're advertising BER/DER/CER.

> +	if (*data_len < 1)
> +		return -EINVAL;

ENOBUFS?  I guess it doesn't really matter.

David
---
#include <stdio.h>

static inline int fls64(unsigned long long x)
{
	int bitpos = -1;
	/*
	 * AMD64 says BSRQ won't clobber the dest reg if x==0; Intel64 says the
	 * dest reg is undefined if x==0, but their CPU architect says its
	 * value is written to set it to the same as before.
	 */
	asm("bsrq %1,%q0"
	    : "+r" (bitpos)
	    : "rm" (x));
	return bitpos + 1;
}

static const unsigned long long vals[] = {
	0x1000000, 0xffffff, 0x800000, 0x7fffff,
	0x100000, 0xfffff, 0x80000, 0x7ffff,
	0x10000, 0xffff, 0x8000, 0x7fff,
	0x1000, 0xfff, 0x800, 0x7ff,
	0x100, 0xff, 0x80, 0x7f,
	3, 2, 1, 0
};

static size_t asn1_uint_len(unsigned long long integer)
{
	size_t l = integer ? fls64(integer) : 1;
	return l / 8 + 1;
}

int main()
{
	const unsigned long long *p = vals;
	unsigned long long integer;

	do {
		integer = *p++;
		printf("len: %16llx -> %zu\n", integer, asn1_uint_len(integer));
	} while (integer);
}


^ permalink raw reply	[flat|nested] 19+ messages in thread

* Re: [PATCH v8 2/8] oid_registry: Add TCG defined OIDS for TPM keys
  2020-03-10  5:15 [PATCH v8 0/8] TPM 2.0 trusted keys with attached policy James Bottomley
                   ` (8 preceding siblings ...)
  2020-03-19 16:47 ` [PATCH v8 1/8] lib: add ASN.1 encoder David Howells
@ 2020-03-19 16:48 ` David Howells
  2020-03-19 16:57 ` [PATCH v8 6/8] security: keys: trusted: add PCR policy to TPM2 keys David Howells
  10 siblings, 0 replies; 19+ messages in thread
From: David Howells @ 2020-03-19 16:48 UTC (permalink / raw)
  To: James Bottomley
  Cc: dhowells, linux-integrity, Mimi Zohar, Jarkko Sakkinen,
	David Woodhouse, keyrings

James Bottomley <James.Bottomley@HansenPartnership.com> wrote:

> The TCG has defined an OID prefix "2.23.133.10.1" for the various TPM
> key uses.  We've defined three of the available numbers:
> 
> 2.23.133.10.1.3 TPM Loadable key.  This is an asymmetric key (Usually
> 		RSA2048 or Elliptic Curve) which can be imported by a
> 		TPM2_Load() operation.
> 
> 2.23.133.10.1.4 TPM Importable Key.  This is an asymmetric key (Usually
> 		RSA2048 or Elliptic Curve) which can be imported by a
> 		TPM2_Import() operation.
> 
> Both loadable and importable keys are specific to a given TPM, the
> difference is that a loadable key is wrapped with the symmetric
> secret, so must have been created by the TPM itself.  An importable
> key is wrapped with a DH shared secret, and may be created without
> access to the TPM provided you know the public part of the parent key.
> 
> 2.23.133.10.1.5 TPM Sealed Data.  This is a set of data (up to 128
> 		bytes) which is sealed by the TPM.  It usually
> 		represents a symmetric key and must be unsealed before
> 		use.
> 
> The ASN.1 binary key form starts of with this OID as the first element
> of a sequence, giving the binary form a unique recognizable identity
> marker regardless of encoding.
> 
> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
> Acked-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

Reviewed-by: David Howells <dhowells@redhat.com>


^ permalink raw reply	[flat|nested] 19+ messages in thread

* Re: [PATCH v8 6/8] security: keys: trusted: add PCR policy to TPM2 keys
  2020-03-10  5:15 [PATCH v8 0/8] TPM 2.0 trusted keys with attached policy James Bottomley
                   ` (9 preceding siblings ...)
  2020-03-19 16:48 ` [PATCH v8 2/8] oid_registry: Add TCG defined OIDS for TPM keys David Howells
@ 2020-03-19 16:57 ` David Howells
  2020-03-19 18:59   ` James Bottomley
  10 siblings, 1 reply; 19+ messages in thread
From: David Howells @ 2020-03-19 16:57 UTC (permalink / raw)
  To: James Bottomley
  Cc: dhowells, linux-integrity, Mimi Zohar, Jarkko Sakkinen,
	David Woodhouse, keyrings

James Bottomley <James.Bottomley@HansenPartnership.com> wrote:

> keyctl new 32 keyhandle=0x81000001 hash=sha1 pcrinfo=030000016768033e216468247bd
> 031a0a2d9876d79818f8f" @u

I think part of this got lost.  There's only one '"' for a start.

David


^ permalink raw reply	[flat|nested] 19+ messages in thread

* Re: [PATCH v8 1/8] lib: add ASN.1 encoder
  2020-03-19 16:47 ` [PATCH v8 1/8] lib: add ASN.1 encoder David Howells
@ 2020-03-19 17:31   ` James Bottomley
  2020-03-19 19:12   ` David Howells
  1 sibling, 0 replies; 19+ messages in thread
From: James Bottomley @ 2020-03-19 17:31 UTC (permalink / raw)
  To: David Howells
  Cc: linux-integrity, Mimi Zohar, Jarkko Sakkinen, David Woodhouse, keyrings

On Thu, 2020-03-19 at 16:47 +0000, David Howells wrote:
> James Bottomley <James.Bottomley@HansenPartnership.com> wrote:
> 
> > + * Copyright (C) 2019 James.Bottomley@HansenPartnership.com
> 
> 2020?

Actually, no, under the Berne convention it should be the date the work
was committed to a fixed medium.  In theory, that's the first git
commit I did in my internal repository.  There's a lot of wiggle room
in this: authors tend to use the date the manuscript was completed, not
when it was started, for instance, but 2019 would seem to be the more
accurate year even so.

> > +unsigned char *
> > +asn1_encode_integer(unsigned char *data, const unsigned char
> > *end_data,
> > +		    s64 integer);
> 
> I wonder if we should actually use u8 rather than unsigned char for
> data pointers like this.  That applies to asn1_ber_decoder() also.

I followed exactly what you did in asn1_decoder.c ... I think there's
value in having a completely signature consistent interface.  Of
course, if you want to alter the encoder and decoder to u8 that can be
done as a follow on patch.

> You should be able to precalculate the length from fls64() or
> ilog2(), e.g.:
> 
> 	static size_t asn1_uint_len(unsigned long long integer)
> 	{
> 		size_t l = integer ? fls64(integer) : 1;
> 		return l / 8 + 1;
> 	}
> 
> See attached toy program.

We can, but it adds a lot of complexity for pretty much no gain: it's
no real hassle to begin the encoding and then find the buffer is too
short, and the code is definitely much easier to follow.

> > +/**
> > + * asn1_encode_tag() - add a tag for optional or explicit value
> > + * @data:	pointer to place tag at
> > + * @end_data:	end of data pointer, points one beyond last
> > usable byte in @data
> > + * @tag:	tag to be placed
> > + * @string:	the data to be tagged
> > + * @len:	the length of the data to be tagged
> > + *
> > + * Note this currently only handles short form tags < 31.  To
> > encode
> > + * in place pass a NULL @string and -1 for @len; all this will do
> > is
> > + * add an indefinite length tag and update the data pointer to the
> > + * place where the tag contents should be placed.  After the data
> > is
> > + * placed, repeat the prior statement but now with the known
> > length.
> > + * In order to avoid having to keep both before and after
> > pointers,
> > + * the repeat expects to be called with @data pointing to where
> > the
> > + * first encode placed it.
> > + */
> 
> I wonder if it's worth appending a note to the comment that if
> indefinite length encoding is selected, then the result is not DER-
> compliant and may not be CER-compliant since you're advertising
> BER/DER/CER.

We only encode definite length currently, so the comment is superfluous
(and probably confusing if you don't know the difference between
DER/BER and CER).  Let's add something like this iff we ever start to
use indefinite lengths in the encoder.

> > +	if (*data_len < 1)
> > +		return -EINVAL;
> 
> ENOBUFS?  I guess it doesn't really matter.

This error gets sent to the user who's not doing to know why because
it's a kernel internal length we got wrong ... let's just keep EINVAL
which is our default "something went wrong" error.

> David
> ---
> #include <stdio.h>
> 
> static inline int fls64(unsigned long long x)
> {
> 	int bitpos = -1;
> 	/*
> 	 * AMD64 says BSRQ won't clobber the dest reg if x==0; Intel64
> says the
> 	 * dest reg is undefined if x==0, but their CPU architect says
> its
> 	 * value is written to set it to the same as before.
> 	 */
> 	asm("bsrq %1,%q0"
> 	    : "+r" (bitpos)
> 	    : "rm" (x));
> 	return bitpos + 1;
> }
> 
> static const unsigned long long vals[] = {
> 	0x1000000, 0xffffff, 0x800000, 0x7fffff,
> 	0x100000, 0xfffff, 0x80000, 0x7ffff,
> 	0x10000, 0xffff, 0x8000, 0x7fff,
> 	0x1000, 0xfff, 0x800, 0x7ff,
> 	0x100, 0xff, 0x80, 0x7f,
> 	3, 2, 1, 0
> };
> 
> static size_t asn1_uint_len(unsigned long long integer)
> {
> 	size_t l = integer ? fls64(integer) : 1;
> 	return l / 8 + 1;
> }
> 
> int main()
> {
> 	const unsigned long long *p = vals;
> 	unsigned long long integer;
> 
> 	do {
> 		integer = *p++;
> 		printf("len: %16llx -> %zu\n", integer,
> asn1_uint_len(integer));
> 	} while (integer);
> }
> 


^ permalink raw reply	[flat|nested] 19+ messages in thread

* Re: [PATCH v8 6/8] security: keys: trusted: add PCR policy to TPM2 keys
  2020-03-19 16:57 ` [PATCH v8 6/8] security: keys: trusted: add PCR policy to TPM2 keys David Howells
@ 2020-03-19 18:59   ` James Bottomley
  0 siblings, 0 replies; 19+ messages in thread
From: James Bottomley @ 2020-03-19 18:59 UTC (permalink / raw)
  To: David Howells
  Cc: linux-integrity, Mimi Zohar, Jarkko Sakkinen, David Woodhouse, keyrings

On Thu, 2020-03-19 at 16:57 +0000, David Howells wrote:
> James Bottomley <James.Bottomley@HansenPartnership.com> wrote:
> 
> > keyctl new 32 keyhandle=0x81000001 hash=sha1
> > pcrinfo=030000016768033e216468247bd
> > 031a0a2d9876d79818f8f" @u
> 
> I think part of this got lost.  There's only one '"' for a start.

Yes, it's a cut and paste error in the change log.  It was cut out of
the additions to Documentation/security/keys/trusted-encrypted.rst and
should read

keyctl add trusted kmk "new 32 keyhandle=0x81000001 hash=sha1 pcrinfo=030000016768033e216468247bd031a0a2d9876d79818f8f" @u

James


^ permalink raw reply	[flat|nested] 19+ messages in thread

* Re: [PATCH v8 1/8] lib: add ASN.1 encoder
  2020-03-19 16:47 ` [PATCH v8 1/8] lib: add ASN.1 encoder David Howells
  2020-03-19 17:31   ` James Bottomley
@ 2020-03-19 19:12   ` David Howells
  2020-03-19 20:07     ` James Bottomley
  1 sibling, 1 reply; 19+ messages in thread
From: David Howells @ 2020-03-19 19:12 UTC (permalink / raw)
  To: James Bottomley
  Cc: dhowells, linux-integrity, Mimi Zohar, Jarkko Sakkinen,
	David Woodhouse, keyrings

James Bottomley <James.Bottomley@HansenPartnership.com> wrote:

> > I wonder if it's worth appending a note to the comment that if
> > indefinite length encoding is selected, then the result is not DER-
> > compliant and may not be CER-compliant since you're advertising
> > BER/DER/CER.
> 
> We only encode definite length currently, so the comment is superfluous
> (and probably confusing if you don't know the difference between
> DER/BER and CER).  Let's add something like this iff we ever start to
> use indefinite lengths in the encoder.

Your code appears to actually do indefinite length encoding if -1 is passed as
len to asn1_encode_tag().  The kdoc says:

	To encode in place pass a NULL @string and -1 for @len; all this will
	do is add an indefinite length tag and update the data pointer to the
	place where the tag contents should be placed.

Granted, your patches might not use it, but you're making a generic ASN.1
encoder library.

David


^ permalink raw reply	[flat|nested] 19+ messages in thread

* Re: [PATCH v8 1/8] lib: add ASN.1 encoder
  2020-03-10  5:16 ` [PATCH v8 1/8] lib: add ASN.1 encoder James Bottomley
@ 2020-03-19 19:16   ` Eric Biggers
  0 siblings, 0 replies; 19+ messages in thread
From: Eric Biggers @ 2020-03-19 19:16 UTC (permalink / raw)
  To: James Bottomley
  Cc: linux-integrity, Mimi Zohar, Jarkko Sakkinen, David Woodhouse, keyrings

On Mon, Mar 09, 2020 at 10:16:00PM -0700, James Bottomley wrote:
> We have a need in the TPM2 trusted keys to return the ASN.1 form of
> the TPM key blob so it can be operated on by tools outside of the
> kernel.  The specific tools are the openssl_tpm2_engine, openconnect
> and the Intel tpm2-tss-engine.  To do that, we have to be able to read
> and write the same binary key format the tools use.  The current ASN.1
> decoder does fine for reading, but we need pieces of an ASN.1 encoder
> to write the key blob in binary compatible form.
> 
> For backwards compatibility, the trusted key reader code will still
> accept the two TPM2B quantities that it uses today, but the writer
> will only output the ASN.1 form.
> 
> The current implementation only encodes the ASN.1 bits we actually need.
[...]
> diff --git a/lib/Makefile b/lib/Makefile
> index 611872c06926..1a9169ef2bed 100644
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -237,7 +237,7 @@ obj-$(CONFIG_INTERVAL_TREE_TEST) += interval_tree_test.o
>  
>  obj-$(CONFIG_PERCPU_TEST) += percpu_test.o
>  
> -obj-$(CONFIG_ASN1) += asn1_decoder.o
> +obj-$(CONFIG_ASN1) += asn1_decoder.o asn1_encoder.o
>  
>  obj-$(CONFIG_FONT_SUPPORT) += fonts/
>  

Shouldn't there be separate kconfig options CONFIG_ASN1_DECODER and
CONFIG_ASN1_ENCODER so that the kernel doesn't get bloated for most users, who
will only need the decoder?

- Eric

^ permalink raw reply	[flat|nested] 19+ messages in thread

* Re: [PATCH v8 1/8] lib: add ASN.1 encoder
  2020-03-19 19:12   ` David Howells
@ 2020-03-19 20:07     ` James Bottomley
  0 siblings, 0 replies; 19+ messages in thread
From: James Bottomley @ 2020-03-19 20:07 UTC (permalink / raw)
  To: David Howells
  Cc: linux-integrity, Mimi Zohar, Jarkko Sakkinen, David Woodhouse, keyrings

On Thu, 2020-03-19 at 19:12 +0000, David Howells wrote:
> James Bottomley <James.Bottomley@HansenPartnership.com> wrote:
> 
> > > I wonder if it's worth appending a note to the comment that if
> > > indefinite length encoding is selected, then the result is not
> > > DER-compliant and may not be CER-compliant since you're
> > > advertising BER/DER/CER.
> > 
> > We only encode definite length currently, so the comment is
> > superfluous (and probably confusing if you don't know the
> > difference between DER/BER and CER).  Let's add something like this
> > iff we ever start to use indefinite lengths in the encoder.
> 
> Your code appears to actually do indefinite length encoding if -1 is
> passed as len to asn1_encode_tag().  The kdoc says:
> 
> 	To encode in place pass a NULL @string and -1 for @len; all
> this will do is add an indefinite length tag and update the data
> pointer to the place where the tag contents should be placed.
> 
> Granted, your patches might not use it, but you're making a generic
> ASN.1 encoder library.

That was a thing the other David asked for.  But actually, I think the
comment is a lie:  the first time around we encode a definite length
for the max buffer size and on the recode we do the length for the
actual buffer size, so we never actually place an indefinite length tag
there ... I think David wanted us to, to keep the ASN.1 always legal,
but the max len thing does that too so I must have changed it without
updating the comment, I'll fix that.

James


^ permalink raw reply	[flat|nested] 19+ messages in thread

* Re: [PATCH v8 1/8] lib: add ASN.1 encoder
  2020-03-10  5:09 ` [PATCH v8 1/8] lib: add ASN.1 encoder James Bottomley
@ 2020-03-10 15:22   ` James Bottomley
  0 siblings, 0 replies; 19+ messages in thread
From: James Bottomley @ 2020-03-10 15:22 UTC (permalink / raw)
  To: linux-integrity; +Cc: Mimi Zohar, Jarkko Sakkinen, David Woodhouse, keyrings

On Mon, 2020-03-09 at 22:09 -0700, James Bottomley wrote:
> We have a need in the TPM2 trusted keys to return the ASN.1 form of
> the TPM key blob so it can be operated on by tools outside of the
> kernel.  The specific tools are the openssl_tpm2_engine, openconnect
> and the Intel tpm2-tss-engine.  To do that, we have to be able to
> read and write the same binary key format the tools use.  The current
> ASN.1 decoder does fine for reading, but we need pieces of an ASN.1
> encoder to write the key blob in binary compatible form.
> 
> For backwards compatibility, the trusted key reader code will still
> accept the two TPM2B quantities that it uses today, but the writer
> will only output the ASN.1 form.
> 
> The current implementation only encodes the ASN.1 bits we actually
> need.
> 
> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com
> >

Sorry, screwed up on tags here (forgot to add reviewed-by:).  I've
resent the entire patch set here:

https://lore.kernel.org/linux-integrity/20200310051607.30334-1-James.Bottomley@HansenPartnership.com/

James


^ permalink raw reply	[flat|nested] 19+ messages in thread

* [PATCH v8 1/8] lib: add ASN.1 encoder
  2020-03-10  5:09 [PATCH v8 0/8] TPM 2.0 trusted keys with attached policy James Bottomley
@ 2020-03-10  5:09 ` James Bottomley
  2020-03-10 15:22   ` James Bottomley
  0 siblings, 1 reply; 19+ messages in thread
From: James Bottomley @ 2020-03-10  5:09 UTC (permalink / raw)
  To: linux-integrity; +Cc: Mimi Zohar, Jarkko Sakkinen, David Woodhouse, keyrings

We have a need in the TPM2 trusted keys to return the ASN.1 form of
the TPM key blob so it can be operated on by tools outside of the
kernel.  The specific tools are the openssl_tpm2_engine, openconnect
and the Intel tpm2-tss-engine.  To do that, we have to be able to read
and write the same binary key format the tools use.  The current ASN.1
decoder does fine for reading, but we need pieces of an ASN.1 encoder
to write the key blob in binary compatible form.

For backwards compatibility, the trusted key reader code will still
accept the two TPM2B quantities that it uses today, but the writer
will only output the ASN.1 form.

The current implementation only encodes the ASN.1 bits we actually need.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

---

v2: updated API to use indefinite length, and made symbol exports gpl
v3: add data length error handling
v4: use end_data instead of data_len pointer
v5: mention tools and space out code
v7: reverse christmas tree variable definitions and better spacing
---
 include/linux/asn1_encoder.h |  32 ++++
 lib/Makefile                 |   2 +-
 lib/asn1_encoder.c           | 431 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 464 insertions(+), 1 deletion(-)
 create mode 100644 include/linux/asn1_encoder.h
 create mode 100644 lib/asn1_encoder.c

diff --git a/include/linux/asn1_encoder.h b/include/linux/asn1_encoder.h
new file mode 100644
index 000000000000..08cd0c2ad34f
--- /dev/null
+++ b/include/linux/asn1_encoder.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef _LINUX_ASN1_ENCODER_H
+#define _LINUX_ASN1_ENCODER_H
+
+#include <linux/types.h>
+#include <linux/asn1.h>
+#include <linux/asn1_ber_bytecode.h>
+#include <linux/bug.h>
+
+#define asn1_oid_len(oid) (sizeof(oid)/sizeof(u32))
+unsigned char *
+asn1_encode_integer(unsigned char *data, const unsigned char *end_data,
+		    s64 integer);
+unsigned char *
+asn1_encode_oid(unsigned char *data, const unsigned char *end_data,
+		u32 oid[], int oid_len);
+unsigned char *
+asn1_encode_tag(unsigned char *data, const unsigned char *end_data,
+		u32 tag, const unsigned char *string, int len);
+unsigned char *
+asn1_encode_octet_string(unsigned char *data,
+			 const unsigned char *end_data,
+			 const unsigned char *string, u32 len);
+unsigned char *
+asn1_encode_sequence(unsigned char *data, const unsigned char *end_data,
+		     const unsigned char *seq, int len);
+unsigned char *
+asn1_encode_boolean(unsigned char *data, const unsigned char *end_data,
+		    bool val);
+
+#endif
diff --git a/lib/Makefile b/lib/Makefile
index 611872c06926..1a9169ef2bed 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -237,7 +237,7 @@ obj-$(CONFIG_INTERVAL_TREE_TEST) += interval_tree_test.o
 
 obj-$(CONFIG_PERCPU_TEST) += percpu_test.o
 
-obj-$(CONFIG_ASN1) += asn1_decoder.o
+obj-$(CONFIG_ASN1) += asn1_decoder.o asn1_encoder.o
 
 obj-$(CONFIG_FONT_SUPPORT) += fonts/
 
diff --git a/lib/asn1_encoder.c b/lib/asn1_encoder.c
new file mode 100644
index 000000000000..24d45a838887
--- /dev/null
+++ b/lib/asn1_encoder.c
@@ -0,0 +1,431 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Simple encoder primitives for ASN.1 BER/DER/CER
+ *
+ * Copyright (C) 2019 James.Bottomley@HansenPartnership.com
+ */
+
+#include <linux/asn1_encoder.h>
+#include <linux/bug.h>
+#include <linux/string.h>
+#include <linux/module.h>
+
+/**
+ * asn1_encode_integer() - encode positive integer to ASN.1
+ * @data:	pointer to the pointer to the data
+ * @end_data:	end of data pointer, points one beyond last usable byte in @data
+ * @integer:	integer to be encoded
+ *
+ * This is a simplified encoder: it only currently does
+ * positive integers, but it should be simple enough to add the
+ * negative case if a use comes along.
+ */
+unsigned char *
+asn1_encode_integer(unsigned char *data, const unsigned char *end_data,
+		    s64 integer)
+{
+	int data_len = end_data - data;
+	unsigned char *d = &data[2];
+	bool found = false;
+	int i;
+
+	if (WARN(integer < 0,
+		 "BUG: integer encode only supports positive integers"))
+		return ERR_PTR(-EINVAL);
+
+	if (IS_ERR(data))
+		return data;
+
+	/* need at least 3 bytes for tag, length and integer encoding */
+	if (data_len < 3)
+		return ERR_PTR(-EINVAL);
+
+	/* remaining length where at d (the start of the integer encoding) */
+	data_len -= 2;
+
+	data[0] = _tag(UNIV, PRIM, INT);
+	if (integer == 0) {
+		*d++ = 0;
+		goto out;
+	}
+
+	for (i = sizeof(integer); i > 0 ; i--) {
+		int byte = integer >> (8 * (i - 1));
+
+		if (!found && byte == 0)
+			continue;
+
+		/*
+		 * for a positive number the first byte must have bit
+		 * 7 clear in two's complement (otherwise it's a
+		 * negative number) so prepend a leading zero if
+		 * that's not the case
+		 */
+		if (!found && (byte & 0x80)) {
+			/*
+			 * no check needed here, we already know we
+			 * have len >= 1
+			 */
+			*d++ = 0;
+			data_len--;
+		}
+
+		found = true;
+		if (data_len == 0)
+			return ERR_PTR(-EINVAL);
+
+		*d++ = byte;
+		data_len--;
+	}
+
+ out:
+	data[1] = d - data - 2;
+
+	return d;
+}
+EXPORT_SYMBOL_GPL(asn1_encode_integer);
+
+/* calculate the base 128 digit values setting the top bit of the first octet */
+static int asn1_encode_oid_digit(unsigned char **_data, int *data_len, u32 oid)
+{
+	unsigned char *data = *_data;
+	int start = 7 + 7 + 7 + 7;
+	int ret = 0;
+
+	if (*data_len < 1)
+		return -EINVAL;
+
+	/* quick case */
+	if (oid == 0) {
+		*data++ = 0x80;
+		(*data_len)--;
+		goto out;
+	}
+
+	while (oid >> start == 0)
+		start -= 7;
+
+	while (start > 0 && *data_len > 0) {
+		u8 byte;
+
+		byte = oid >> start;
+		oid = oid - (byte << start);
+		start -= 7;
+		byte |= 0x80;
+		*data++ = byte;
+		(*data_len)--;
+	}
+
+	if (*data_len > 0) {
+		*data++ = oid;
+		(*data_len)--;
+	} else {
+		ret = -EINVAL;
+	}
+
+ out:
+	*_data = data;
+	return ret;
+}
+
+/**
+ * asn1_encode_oid() - encode an oid to ASN.1
+ * @data:	position to begin encoding at
+ * @end_data:	end of data pointer, points one beyond last usable byte in @data
+ * @oid:	array of oids
+ * @oid_len:	length of oid array
+ *
+ * this encodes an OID up to ASN.1 when presented as an array of OID values
+ */
+unsigned char *
+asn1_encode_oid(unsigned char *data, const unsigned char *end_data,
+		u32 oid[], int oid_len)
+{
+	int data_len = end_data - data;
+	unsigned char *d = data + 2;
+	int i, ret;
+
+	if (WARN(oid_len < 2, "OID must have at least two elements"))
+		return ERR_PTR(-EINVAL);
+
+	if (WARN(oid_len > 32, "OID is too large"))
+		return ERR_PTR(-EINVAL);
+
+	if (IS_ERR(data))
+		return data;
+
+
+	/* need at least 3 bytes for tag, length and OID encoding */
+	if (data_len < 3)
+		return ERR_PTR(-EINVAL);
+
+	data[0] = _tag(UNIV, PRIM, OID);
+	*d++ = oid[0] * 40 + oid[1];
+
+	data_len -= 3;
+
+	ret = 0;
+
+	for (i = 2; i < oid_len; i++) {
+		ret = asn1_encode_oid_digit(&d, &data_len, oid[i]);
+		if (ret < 0)
+			return ERR_PTR(ret);
+	}
+
+	data[1] = d - data - 2;
+
+	return d;
+}
+EXPORT_SYMBOL_GPL(asn1_encode_oid);
+
+static int asn1_encode_length(unsigned char **data, int *data_len, int len)
+{
+	if (*data_len < 1)
+		return -EINVAL;
+
+	if (len < 0) {
+		*((*data)++) = ASN1_INDEFINITE_LENGTH;
+		(*data_len)--;
+		return 0;
+	}
+
+	if (len <= 0x7f) {
+		*((*data)++) = len;
+		(*data_len)--;
+		return 0;
+	}
+
+	if (*data_len < 2)
+		return -EINVAL;
+
+	if (len <= 0xff) {
+		*((*data)++) = 0x81;
+		*((*data)++) = len & 0xff;
+		*data_len -= 2;
+		return 0;
+	}
+
+	if (*data_len < 3)
+		return -EINVAL;
+
+	if (len <= 0xffff) {
+		*((*data)++) = 0x82;
+		*((*data)++) = (len >> 8) & 0xff;
+		*((*data)++) = len & 0xff;
+		*data_len -= 3;
+		return 0;
+	}
+
+	if (WARN(len > 0xffffff, "ASN.1 length can't be > 0xffffff"))
+		return -EINVAL;
+
+	if (*data_len < 4)
+		return -EINVAL;
+	*((*data)++) = 0x83;
+	*((*data)++) = (len >> 16) & 0xff;
+	*((*data)++) = (len >> 8) & 0xff;
+	*((*data)++) = len & 0xff;
+	*data_len -= 4;
+
+	return 0;
+}
+
+/**
+ * asn1_encode_tag() - add a tag for optional or explicit value
+ * @data:	pointer to place tag at
+ * @end_data:	end of data pointer, points one beyond last usable byte in @data
+ * @tag:	tag to be placed
+ * @string:	the data to be tagged
+ * @len:	the length of the data to be tagged
+ *
+ * Note this currently only handles short form tags < 31.  To encode
+ * in place pass a NULL @string and -1 for @len; all this will do is
+ * add an indefinite length tag and update the data pointer to the
+ * place where the tag contents should be placed.  After the data is
+ * placed, repeat the prior statement but now with the known length.
+ * In order to avoid having to keep both before and after pointers,
+ * the repeat expects to be called with @data pointing to where the
+ * first encode placed it.
+ */
+unsigned char *
+asn1_encode_tag(unsigned char *data, const unsigned char *end_data,
+		u32 tag, const unsigned char *string, int len)
+{
+	int data_len = end_data - data;
+	int ret;
+
+	if (WARN(tag > 30, "ASN.1 tag can't be > 30"))
+		return ERR_PTR(-EINVAL);
+
+	if (!string && WARN(len > 127,
+			    "BUG: recode tag is too big (>127)"))
+		return ERR_PTR(-EINVAL);
+
+	if (IS_ERR(data))
+		return data;
+
+	if (!string && len > 0) {
+		/*
+		 * we're recoding, so move back to the start of the
+		 * tag and install a dummy length because the real
+		 * data_len should be NULL
+		 */
+		data -= 2;
+		data_len = 2;
+	}
+
+	if (data_len < 2)
+		return ERR_PTR(-EINVAL);
+
+	*(data++) = _tagn(CONT, CONS, tag);
+	data_len--;
+	ret = asn1_encode_length(&data, &data_len, len);
+	if (ret < 0)
+		return ERR_PTR(ret);
+
+	if (!string)
+		return data;
+
+	if (data_len < len)
+		return ERR_PTR(-EINVAL);
+
+	memcpy(data, string, len);
+	data += len;
+
+	return data;
+}
+EXPORT_SYMBOL_GPL(asn1_encode_tag);
+
+/**
+ * asn1_encode_octet_string() - encode an ASN.1 OCTET STRING
+ * @data:	pointer to encode at
+ * @end_data:	end of data pointer, points one beyond last usable byte in @data
+ * @string:	string to be encoded
+ * @len:	length of string
+ *
+ * Note ASN.1 octet strings may contain zeros, so the length is obligatory.
+ */
+unsigned char *
+asn1_encode_octet_string(unsigned char *data,
+			 const unsigned char *end_data,
+			 const unsigned char *string, u32 len)
+{
+	int data_len = end_data - data;
+	int ret;
+
+	if (IS_ERR(data))
+		return data;
+
+	/* need minimum of 2 bytes for tag and length of zero length string */
+	if (data_len < 2)
+		return ERR_PTR(-EINVAL);
+
+	*(data++) = _tag(UNIV, PRIM, OTS);
+	data_len--;
+
+	ret = asn1_encode_length(&data, &data_len, len);
+	if (ret)
+		return ERR_PTR(ret);
+
+	if (data_len < len)
+		return ERR_PTR(-EINVAL);
+
+	memcpy(data, string, len);
+	data += len;
+
+	return data;
+}
+EXPORT_SYMBOL_GPL(asn1_encode_octet_string);
+
+/**
+ * asn1_encode_sequence() - wrap a byte stream in an ASN.1 SEQUENCE
+ * @data:	pointer to encode at
+ * @end_data:	end of data pointer, points one beyond last usable byte in @data
+ * @seq:	data to be encoded as a sequence
+ * @len:	length of the data to be encoded as a sequence
+ *
+ * Fill in a sequence.  To encode in place, pass NULL for @seq and -1
+ * for @len; then call again once the length is known (still with NULL
+ * for @seq). In order to avoid having to keep both before and after
+ * pointers, the repeat expects to be called with @data pointing to
+ * where the first encode placed it.
+ */
+unsigned char *
+asn1_encode_sequence(unsigned char *data, const unsigned char *end_data,
+		     const unsigned char *seq, int len)
+{
+	int data_len = end_data - data;
+	int ret;
+
+	if (!seq && WARN(len > 127,
+			 "BUG: recode sequence is too big (>127)"))
+		return ERR_PTR(-EINVAL);
+
+	if (IS_ERR(data))
+		return data;
+
+	if (!seq && len >= 0) {
+		/*
+		 * we're recoding, so move back to the start of the
+		 * sequence and install a dummy length because the
+		 * real length should be NULL
+		 */
+		data -= 2;
+		data_len = 2;
+	}
+
+	if (data_len < 2)
+		return ERR_PTR(-EINVAL);
+
+	*(data++) = _tag(UNIV, CONS, SEQ);
+	data_len--;
+
+	ret = asn1_encode_length(&data, &data_len, len);
+	if (ret)
+		return ERR_PTR(ret);
+
+	if (!seq)
+		return data;
+
+	if (data_len < len)
+		return ERR_PTR(-EINVAL);
+
+	memcpy(data, seq, len);
+	data += len;
+
+	return data;
+}
+EXPORT_SYMBOL_GPL(asn1_encode_sequence);
+
+/**
+ * asn1_encode_boolean() - encode a boolean value to ASN.1
+ * @data:	pointer to encode at
+ * @end_data:	end of data pointer, points one beyond last usable byte in @data
+ * @val:	the boolean true/false value
+ */
+unsigned char *
+asn1_encode_boolean(unsigned char *data, const unsigned char *end_data,
+		    bool val)
+{
+	int data_len = end_data - data;
+
+	if (IS_ERR(data))
+		return data;
+
+	/* booleans are 3 bytes: tag, length == 1 and value == 0 or 1 */
+	if (data_len < 3)
+		return ERR_PTR(-EINVAL);
+
+	*(data++) = _tag(UNIV, PRIM, BOOL);
+	data_len--;
+
+	asn1_encode_length(&data, &data_len, 1);
+
+	if (val)
+		*(data++) = 1;
+	else
+		*(data++) = 0;
+
+	return data;
+}
+EXPORT_SYMBOL_GPL(asn1_encode_boolean);
-- 
2.16.4


^ permalink raw reply	[flat|nested] 19+ messages in thread

end of thread, back to index

Thread overview: 19+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-03-10  5:15 [PATCH v8 0/8] TPM 2.0 trusted keys with attached policy James Bottomley
2020-03-10  5:16 ` [PATCH v8 1/8] lib: add ASN.1 encoder James Bottomley
2020-03-19 19:16   ` Eric Biggers
2020-03-10  5:16 ` [PATCH v8 2/8] oid_registry: Add TCG defined OIDS for TPM keys James Bottomley
2020-03-10  5:16 ` [PATCH v8 3/8] security: keys: trusted: fix TPM2 authorizations James Bottomley
2020-03-10  5:16 ` [PATCH v8 4/8] security: keys: trusted: use ASN.1 TPM2 key format for the blobs James Bottomley
2020-03-10  5:16 ` [PATCH v8 5/8] security: keys: trusted: Make sealed key properly interoperable James Bottomley
2020-03-10  5:16 ` [PATCH v8 6/8] security: keys: trusted: add PCR policy to TPM2 keys James Bottomley
2020-03-10  5:16 ` [PATCH v8 7/8] security: keys: trusted: add ability to specify arbitrary policy James Bottomley
2020-03-10  5:16 ` [PATCH v8 8/8] security: keys: trusted: implement counter/timer policy James Bottomley
2020-03-19 16:47 ` [PATCH v8 1/8] lib: add ASN.1 encoder David Howells
2020-03-19 17:31   ` James Bottomley
2020-03-19 19:12   ` David Howells
2020-03-19 20:07     ` James Bottomley
2020-03-19 16:48 ` [PATCH v8 2/8] oid_registry: Add TCG defined OIDS for TPM keys David Howells
2020-03-19 16:57 ` [PATCH v8 6/8] security: keys: trusted: add PCR policy to TPM2 keys David Howells
2020-03-19 18:59   ` James Bottomley
  -- strict thread matches above, loose matches on Subject: below --
2020-03-10  5:09 [PATCH v8 0/8] TPM 2.0 trusted keys with attached policy James Bottomley
2020-03-10  5:09 ` [PATCH v8 1/8] lib: add ASN.1 encoder James Bottomley
2020-03-10 15:22   ` James Bottomley

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