// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2004 IBM Corporation
* 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>
#include <linux/tpm_command.h>
#include <keys/trusted-type.h>
#include <keys/trusted_tpm.h>
#include <linux/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},
{HASH_ALGO_SHA384, TPM_ALG_SHA384},
{HASH_ALGO_SHA512, TPM_ALG_SHA512},
{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;
int ret;
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")) {
ret = PTR_ERR(w);
goto err;
}
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")) {
ret = -EINVAL;
goto err;
}
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 (IS_ERR(work1)) {
ret = PTR_ERR(work1);
pr_err("BUG: ASN.1 encoder failed with %d\n", ret);
goto err;
}
kfree(scratch);
return work1 - payload->blob;
err:
kfree(scratch);
return ret;
}
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;
}
/**
* tpm2_buf_append_auth() - append TPMS_AUTH_COMMAND to the buffer.
*
* @buf: an allocated tpm_buf instance
* @session_handle: session handle
* @nonce: the session nonce, may be NULL if not used
* @nonce_len: the session nonce length, may be 0 if not used
* @attributes: the session attributes
* @hmac: the session HMAC or password, may be NULL if not used
* @hmac_len: the session HMAC or password length, maybe 0 if not used
*/
static void tpm2_buf_append_auth(struct tpm_buf *buf, u32 session_handle,
const u8 *nonce, u16 nonce_len,
u8 attributes,
const u8 *hmac, u16 hmac_len)
{
tpm_buf_append_u32(buf, 9 + nonce_len + hmac_len);
tpm_buf_append_u32(buf, session_handle);
tpm_buf_append_u16(buf, nonce_len);
if (nonce && nonce_len)
tpm_buf_append(buf, nonce, nonce_len);
tpm_buf_append_u8(buf, attributes);
tpm_buf_append_u16(buf, hmac_len);
if (hmac && hmac_len)
tpm_buf_append(buf, hmac, hmac_len);
}
/**
* tpm2_seal_trusted() - seal the payload of a trusted key
*
* @chip: TPM chip to use
* @payload: the key data in clear and encrypted form
* @options: authentication values and other options
*
* Return: < 0 on error and 0 on success.
*/
int tpm2_seal_trusted(struct tpm_chip *chip,
struct trusted_key_payload *payload,
struct trusted_key_options *options)
{
off_t offset = TPM_HEADER_SIZE;
struct tpm_buf buf, sized;
int blob_len = 0;
u32 hash;
u32 flags;
int i;
int rc;
for (i = 0; i < ARRAY_SIZE(tpm2_hash_map); i++) {
if (options->hash == tpm2_hash_map[i].crypto_id) {
hash = tpm2_hash_map[i].tpm_id;
break;
}
}
if (i == ARRAY_SIZE(tpm2_hash_map))
return -EINVAL;
if (!options->keyhandle)
return -EINVAL;
rc = tpm_try_get_ops(chip);
if (rc)
return rc;
rc = tpm2_start_auth_session(chip);
if (rc)
goto out_put;
rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE);
if (rc) {
tpm2_end_auth_session(chip);
goto out_put;
}
rc = tpm_buf_init_sized(&sized);
if (rc) {
tpm_buf_destroy(&buf);
tpm2_end_auth_session(chip);
goto out_put;
}
tpm_buf_append_name(chip, &buf, options->keyhandle, NULL);
tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_DECRYPT,
options->keyauth, TPM_DIGEST_SIZE);
/* sensitive */
tpm_buf_append_u16(&sized, options->blobauth_len);
if (options->blobauth_len)
tpm_buf_append(&sized, options->blobauth, options->blobauth_len);
tpm_buf_append_u16(&sized, payload->key_len);
tpm_buf_append(&sized, payload->key, payload->key_len);
tpm_buf_append(&buf, sized.data, sized.length);
/* public */
tpm_buf_reset_sized(&sized);
tpm_buf_append_u16(&sized, TPM_ALG_KEYEDHASH);
tpm_buf_append_u16(&sized, hash);
/* key properties */
flags = 0;
flags |= options->policydigest_len ? 0 : TPM2_OA_USER_WITH_AUTH;
flags |= payload->migratable ? 0 : (TPM2_OA_FIXED_TPM | TPM2_OA_FIXED_PARENT);
tpm_buf_append_u32(&sized, flags);
/* policy */
tpm_buf_append_u16(&sized, options->policydigest_len);
if (options->policydigest_len)
tpm_buf_append(&sized, options->policydigest, options->policydigest_len);
/* public parameters */
tpm_buf_append_u16(&sized, TPM_ALG_NULL);
tpm_buf_append_u16(&sized, 0);
tpm_buf_append(&buf, sized.data, sized.length);
/* outside info */
tpm_buf_append_u16(&buf, 0);
/* creation PCR */
tpm_buf_append_u32(&buf, 0);
if (buf.flags & TPM_BUF_OVERFLOW) {
rc = -E2BIG;
tpm2_end_auth_session(chip);
goto out;
}
tpm_buf_fill_hmac_session(chip, &buf);
rc = tpm_transmit_cmd(chip, &buf, 4, "sealing data");
rc = tpm_buf_check_hmac_response(chip, &buf, rc);
if (rc)
goto out;
blob_len = tpm_buf_read_u32(&buf, &offset);
if (blob_len > MAX_BLOB_SIZE || buf.flags & TPM_BUF_BOUNDARY_ERROR) {
rc = -E2BIG;
goto out;
}
if (buf.length - offset < blob_len) {
rc = -EFAULT;
goto out;
}
blob_len = tpm2_key_encode(payload, options, &buf.data[offset], blob_len);
out:
tpm_buf_destroy(&sized);
tpm_buf_destroy(&buf);
if (rc > 0) {
if (tpm2_rc_value(rc) == TPM2_RC_HASH)
rc = -EINVAL;
else
rc = -EPERM;
}
if (blob_len < 0)
rc = blob_len;
else
payload->blob_len = blob_len;
out_put:
tpm_put_ops(chip);
return rc;
}
/**
* tpm2_load_cmd() - execute a TPM2_Load command
*
* @chip: TPM chip to use
* @payload: the key data in clear and encrypted form
* @options: authentication values and other options
* @blob_handle: returned blob handle
*
* Return: 0 on success.
* -E2BIG on wrong payload size.
* -EPERM on tpm error status.
* < 0 error from tpm_send.
*/
static int tpm2_load_cmd(struct tpm_chip *chip,
struct trusted_key_payload *payload,
struct trusted_key_options *options,
u32 *blob_handle)
{
struct tpm_buf buf;
unsigned int private_len;
unsigned int public_len;
unsigned int blob_len;
u8 *blob, *pub;
int rc;
u32 attrs;
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;
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;
rc = tpm2_start_auth_session(chip);
if (rc)
return rc;
rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_LOAD);
if (rc) {
tpm2_end_auth_session(chip);
return rc;
}
tpm_buf_append_name(chip, &buf, options->keyhandle, NULL);
tpm_buf_append_hmac_session(chip, &buf, 0, options->keyauth,
TPM_DIGEST_SIZE);
tpm_buf_append(&buf, blob, blob_len);
if (buf.flags & TPM_BUF_OVERFLOW) {
rc = -E2BIG;
tpm2_end_auth_session(chip);
goto out;
}
tpm_buf_fill_hmac_session(chip, &buf);
rc = tpm_transmit_cmd(chip, &buf, 4, "loading blob");
rc = tpm_buf_check_hmac_response(chip, &buf, rc);
if (!rc)
*blob_handle = be32_to_cpup(
(__be32 *) &buf.data[TPM_HEADER_SIZE]);
out:
if (blob != payload->blob)
kfree(blob);
tpm_buf_destroy(&buf);
if (rc > 0)
rc = -EPERM;
return rc;
}
/**
* tpm2_unseal_cmd() - execute a TPM2_Unload command
*
* @chip: TPM chip to use
* @payload: the key data in clear and encrypted form
* @options: authentication values and other options
* @blob_handle: blob handle
*
* Return: 0 on success
* -EPERM on tpm error status
* < 0 error from tpm_send
*/
static int tpm2_unseal_cmd(struct tpm_chip *chip,
struct trusted_key_payload *payload,
struct trusted_key_options *options,
u32 blob_handle)
{
struct tpm_buf buf;
u16 data_len;
u8 *data;
int rc;
rc = tpm2_start_auth_session(chip);
if (rc)
return rc;
rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL);
if (rc) {
tpm2_end_auth_session(chip);
return rc;
}
tpm_buf_append_name(chip, &buf, blob_handle, NULL);
if (!options->policyhandle) {
tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_ENCRYPT,
options->blobauth,
options->blobauth_len);
} else {
/*
* FIXME: The policy session was generated outside the
* kernel so we don't known the nonce and thus can't
* calculate a HMAC on it. Therefore, the user can
* only really use TPM2_PolicyPassword and we must
* send down the plain text password, which could be
* intercepted. We can still encrypt the returned
* key, but that's small comfort since the interposer
* could repeat our actions with the exfiltrated
* password.
*/
tpm2_buf_append_auth(&buf, options->policyhandle,
NULL /* nonce */, 0, 0,
options->blobauth, options->blobauth_len);
tpm_buf_append_hmac_session_opt(chip, &buf, TPM2_SA_ENCRYPT,
NULL, 0);
}
tpm_buf_fill_hmac_session(chip, &buf);
rc = tpm_transmit_cmd(chip, &buf, 6, "unsealing");
rc = tpm_buf_check_hmac_response(chip, &buf, rc);
if (rc > 0)
rc = -EPERM;
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) {
rc = -EFAULT;
goto out;
}
if (tpm_buf_length(&buf) < TPM_HEADER_SIZE + 6 + data_len) {
rc = -EFAULT;
goto out;
}
data = &buf.data[TPM_HEADER_SIZE + 6];
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:
tpm_buf_destroy(&buf);
return rc;
}
/**
* tpm2_unseal_trusted() - unseal the payload of a trusted key
*
* @chip: TPM chip to use
* @payload: the key data in clear and encrypted form
* @options: authentication values and other options
*
* Return: Same as with tpm_send.
*/
int tpm2_unseal_trusted(struct tpm_chip *chip,
struct trusted_key_payload *payload,
struct trusted_key_options *options)
{
u32 blob_handle;
int rc;
rc = tpm_try_get_ops(chip);
if (rc)
return rc;
rc = tpm2_load_cmd(chip, payload, options, &blob_handle);
if (rc)
goto out;
rc = tpm2_unseal_cmd(chip, payload, options, blob_handle);
tpm2_flush_context(chip, blob_handle);
out:
tpm_put_ops(chip);
return rc;
}
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