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authorJames Bottomley <James.Bottomley@HansenPartnership.com>2021-01-27 11:06:16 -0800
committerJarkko Sakkinen <jarkko@kernel.org>2021-04-14 16:30:30 +0300
commitf2219745250f388edacabe6cca73654131c67d0a (patch)
tree051936ef02a33f9a08ab24994178b7cff3d6b946 /security/keys/trusted-keys/trusted_tpm2.c
parentde66514d934d70ce73c302ce0644b54970fc7196 (diff)
security: keys: trusted: use ASN.1 TPM2 key format for the blobs
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> Tested-by: Jarkko Sakkinen <jarkko@kernel.org> Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Diffstat (limited to 'security/keys/trusted-keys/trusted_tpm2.c')
-rw-r--r--security/keys/trusted-keys/trusted_tpm2.c210
1 files changed, 203 insertions, 7 deletions
diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index ac361aa7f3f1..68249db98a4c 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.
*
@@ -63,7 +228,7 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
struct trusted_key_payload *payload,
struct trusted_key_options *options)
{
- unsigned int blob_len;
+ int blob_len = 0;
struct tpm_buf buf;
u32 hash;
int i;
@@ -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;
@@ -152,8 +320,9 @@ 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;
+ blob_len = tpm2_key_encode(payload, options,
+ &buf.data[TPM_HEADER_SIZE + 4],
+ blob_len);
out:
tpm_buf_destroy(&buf);
@@ -164,6 +333,10 @@ out:
else
rc = -EPERM;
}
+ if (blob_len < 0)
+ return blob_len;
+
+ payload->blob_len = blob_len;
tpm_put_ops(chip);
return rc;
@@ -191,13 +364,34 @@ 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;
@@ -213,7 +407,7 @@ 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;
@@ -226,6 +420,8 @@ 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)