On Thu, May 20, 2021 at 05:43:58PM -0700, James Bottomley wrote:
> 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 hash of the PCRs to use the same hash
> algorithm as the one passed in. 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 locking the key to this
> value of PCR 16 with a parent key of 81000001 would be:
>
> keyctl add trusted kmk "new 32 keyhandle=0x81000001 hash=sha1 pcrinfo=030000016768033e216468247bd031a0a2d9876d79818f8f" @u
>
> Signed-off-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
API looks sane.
> ---
> .../security/keys/trusted-encrypted.rst | 36 +-
> include/keys/trusted-type.h | 5 +-
> include/linux/tpm.h | 3 +
> security/keys/Kconfig | 2 +
> security/keys/trusted-keys/Makefile | 1 +
> security/keys/trusted-keys/tpm2-policy.c | 359 ++++++++++++++++++
> security/keys/trusted-keys/tpm2-policy.h | 30 ++
> security/keys/trusted-keys/tpm2key.asn1 | 13 +
> security/keys/trusted-keys/trusted_core.c | 8 +-
> security/keys/trusted-keys/trusted_tpm2.c | 86 ++++-
> 10 files changed, 530 insertions(+), 13 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 80d5a5af62a1..5c66f29b7a1c 100644
> --- a/Documentation/security/keys/trusted-encrypted.rst
> +++ b/Documentation/security/keys/trusted-encrypted.rst
> @@ -156,7 +156,10 @@ 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)
> @@ -254,6 +257,20 @@ 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 (TPM specific) a trusted key under new PCR values::
>
> $ keyctl update 268728824 "update pcrinfo=`cat pcr.blob`"
> @@ -325,11 +342,17 @@ policy::
> TPMKey ::= SEQUENCE {
> type OBJECT IDENTIFIER
> emptyAuth [0] EXPLICIT BOOLEAN OPTIONAL
> + policy [1] EXPLICIT SEQUENCE OF TPMPolicy OPTIONAL
> parent INTEGER
> pubkey OCTET STRING
> privkey OCTET STRING
> }
>
> + TPMPolicy ::= SEQUENCE {
> + CommandCode [0] EXPLICIT INTEGER
> + CommandPolicy [1] EXPLICIT OCTET STRING
> + }
> +
> type is what distinguishes the key even in binary form since the OID
> is provided by the TCG to be unique and thus forms a recognizable
> binary pattern at offset 3 in the key. The OIDs currently made
> @@ -355,6 +378,17 @@ is false or not present, the key requires an explicit authorization
> phrase. This is used by most user space consumers to decide whether
> to prompt for a password.
>
> +policy represents a sequence of one or more policy statements that
> +must be executed successfully into a session policy register. If
> +policy isn't present then no policy is required to unlock the key, but
> +if it is, commandCode is the TPM 2.0 command code of the policy
> +instruction that must be executed and CommandPolicy represents the
> +binary parameter area of the policy command.
> +
> +Note that the current sequential execution requirement means that only
> +AND based policy can be constructed at the moment, so TPM2_PolicyOR is
> +not currently supported.
> +
> parent represents the parent key handle, either in the 0x81 MSO space,
> like 0x81000001 for the RSA primary storage key. Userspace programmes
> also support specifying the primary handle in the 0x40 MSO space. If
> diff --git a/include/keys/trusted-type.h b/include/keys/trusted-type.h
> index d89fa2579ac0..749dadbd72e7 100644
> --- a/include/keys/trusted-type.h
> +++ b/include/keys/trusted-type.h
> @@ -20,9 +20,11 @@
> #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;
> @@ -31,6 +33,7 @@ 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 aa11fe323c56..298321fe07ee 100644
> --- a/include/linux/tpm.h
> +++ b/include/linux/tpm.h
> @@ -230,10 +230,12 @@ enum tpm2_command_codes {
> TPM2_CC_CONTEXT_LOAD = 0x0161,
> TPM2_CC_CONTEXT_SAVE = 0x0162,
> TPM2_CC_FLUSH_CONTEXT = 0x0165,
> + 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,
> @@ -242,6 +244,7 @@ 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 64b81abd087e..8a79f4faba97 100644
> --- a/security/keys/Kconfig
> +++ b/security/keys/Kconfig
> @@ -74,6 +74,8 @@ config TRUSTED_KEYS
> select CRYPTO
> select CRYPTO_HMAC
> select CRYPTO_SHA1
> + select CRYPTO_SHA256
> + select CRYPTO_SHA512
> select CRYPTO_HASH_INFO
> select ASN1_ENCODER
> select OID_REGISTRY
> diff --git a/security/keys/trusted-keys/Makefile b/security/keys/trusted-keys/Makefile
> index feb8b6c3cc79..39c598c4d2ef 100644
> --- a/security/keys/trusted-keys/Makefile
> +++ b/security/keys/trusted-keys/Makefile
> @@ -10,5 +10,6 @@ trusted-y += trusted_tpm1.o
> $(obj)/trusted_tpm2.o: $(obj)/tpm2key.asn1.h
> trusted-y += trusted_tpm2.o
> trusted-y += tpm2key.asn1.o
> +trusted-y += tpm2-policy.o
>
> trusted-$(CONFIG_TEE) += trusted_tee.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..b05b2953d5ea
> --- /dev/null
> +++ b/security/keys/trusted-keys/tpm2-policy.c
> @@ -0,0 +1,359 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2019 James.Bottomley@xxxxxxxxxxxxxxxxxxxxx
> + */
> +
> +#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"
> +
> +/* used by ASN.1 parser only to extract policy code */
> +int tpm2_key_code(void *context, size_t hdrlen,
> + unsigned char tag,
> + const void *value, size_t vlen)
> +{
Why the function name is tpm2_key_code() but the comment phrases
"policy code". Some sort of verb of action would be nice, e.g.
tpm2_extract_*_code(), expecially since this isn't idempotent
function.
And prototype can realigned to two lines, instead of three.
> + struct tpm2_key_context *ctx = context;
> + u32 code = 0;
> + const u8 *v = value;
const u8 *v = value;
u32 code = 0;
> + int i;
> +
> + for (i = 0; i < vlen; i++) {
> + code <<= 8;
> + code |= v[i];
> + }
> +
> + ctx->policy_code[ctx->policy_count] = code;
> +
> + return 0;
> +}
> +
> +/* used by ASN.1 parser only to extract policy sequence */
> +int tpm2_key_policy(void *context, size_t hdrlen,
> + unsigned char tag,
> + const void *value, size_t vlen)
Ditto.
> +{
> + 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
> + */
I'd prefer if sentences are always written properly, i.e. so that
they start with a capital etc.
Also, the comment should be
/*
* Text
*/
according to kdoc documentation.
> +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_PCR:
> + break;
> + default:
> + pr_warn("tpm2 policy 0x%x is unsupported",
Acronym is written incorrectly. It should be "TPM2". Also, since this isn't
any sort of kernel issue when it happens, this should be pr_info().
It's also lacking "\n".
> + pols->code[i]);
> + return -EINVAL;
> + }
The switch-case statement serves zero purpose here, i.e. please change to:
if (pols->code[i] != TPM2_CC_POLICY_PCR)
pr_info("TPM2 policy 0x%x is unsupported.\n", pols->code[i]);
> + }
> +
> + 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
Should be aligned with tabs:
https://www.kernel.org/doc/Documentation/kernel-doc-nano-HOWTO.txt
Also, I'm wondering why this has a verb in the function name, while
earlier didn't. There's no coherence.
> + *
> + * THis function sizes the policy statements and allocates space
"This"
> + * 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 */
Quite useless comment.
> +
> + /* 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]);
Would be nice to have comments written both proper form and language, e.g.
/* The hash is the second algorithm. */
pols->hash = get_unaligned_be16(&ctx->pub[4]);
/* The digest appears after the attributes. */
pols->hash_size = get_unaligned_be16(&ctx->pub[10]);
(also the empty line in-between is essential to make comments readable)
> +
> + 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 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);
> +
> + 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;
> +}
> +
> +static 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_transmit_cmd(chip, &buf, 0, "start policy session");
> + 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_transmit_cmd(chip, &buf, 0, "send policy");
> + tpm_buf_destroy(&buf);
> + if (rc) {
> + dev_err(&chip->dev, "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 f57f869ad600..1684bd8f725e 100644
> --- a/security/keys/trusted-keys/tpm2key.asn1
> +++ b/security/keys/trusted-keys/tpm2key.asn1
> @@ -1,11 +1,24 @@
> ---
> --- ASN.1 for TPM 2.0 keys
> ---
> +--- 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,
> 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 ({tpm2_key_code}),
> + commandPolicy [1] EXPLICIT OCTET STRING ({tpm2_key_policy})
> + }
> diff --git a/security/keys/trusted-keys/trusted_core.c b/security/keys/trusted-keys/trusted_core.c
> index d5c891d8d353..7a41c64e67b0 100644
> --- a/security/keys/trusted-keys/trusted_core.c
> +++ b/security/keys/trusted-keys/trusted_core.c
> @@ -209,6 +209,7 @@ static void trusted_rcu_free(struct rcu_head *rcu)
> struct trusted_key_payload *p;
>
> p = container_of(rcu, struct trusted_key_payload, rcu);
> + kfree_sensitive(p->policies);
> kfree_sensitive(p);
> }
>
> @@ -299,7 +300,12 @@ static long trusted_read(const struct key *key, char *buffer,
> */
> static void trusted_destroy(struct key *key)
> {
> - kfree_sensitive(key->payload.data[0]);
> +
> + struct trusted_key_payload *p;
> +
> + p = key->payload.data[0];
> + kfree_sensitive(p->policies);
> + kfree_sensitive(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 0165da386289..a218f982fef5 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_try_get_ops(chip);
> if (rc)
> return rc;
> @@ -464,21 +514,37 @@ 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_transmit_cmd(chip, &buf, 6, "unsealing");
> + if (payload->policies)
> + tpm2_flush_context(chip, policyhandle);
Empty line (probably other similar places scattered here and there).
> if (rc > 0)
> rc = -EPERM;
>
> --
> 2.26.2
>
>
I did not check everything. I think the API looks decent, just patches
need a lot of polishing.
/Jarkko
