[PATCH v2 4/6] KEYS: trusted: Move tpm2_key_decode() to the TPM driver

Jarkko Sakkinen
2024-05-21T03:17:15Z

Move tpm2_key_decode() to the TPM driver and export the symbols to make
them callable from trusted keys. It can re-used for asymmetric keys.

Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
v2:
Do not allocate blob twice. Use the one inside struct tpm2_key.
---
drivers/char/tpm/Kconfig | 1 +
drivers/char/tpm/Makefile | 5 +
drivers/char/tpm/tpm2_key.c | 111 +++++++++++++++
.../char/tpm}/tpm2key.asn1 | 0
include/crypto/tpm2_key.h | 33 +++++
security/keys/trusted-keys/Makefile | 2 -
security/keys/trusted-keys/trusted_tpm2.c | 127 +++---------------
7 files changed, 167 insertions(+), 112 deletions(-)
create mode 100644 drivers/char/tpm/tpm2_key.c
rename {security/keys/trusted-keys => drivers/char/tpm}/tpm2key.asn1 (100%)
create mode 100644 include/crypto/tpm2_key.h

diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
index e63a6a17793c..de2f4093c939 100644
--- a/drivers/char/tpm/Kconfig
+++ b/drivers/char/tpm/Kconfig
@@ -7,6 +7,7 @@ menuconfig TCG_TPM
tristate "TPM Hardware Support"
depends on HAS_IOMEM
imply SECURITYFS
+ select ASN1
select CRYPTO
select CRYPTO_HASH_INFO
help
diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile
index 4c695b0388f3..071437058ef6 100644
--- a/drivers/char/tpm/Makefile
+++ b/drivers/char/tpm/Makefile
@@ -17,6 +17,11 @@ tpm-y += eventlog/tpm1.o
tpm-y += eventlog/tpm2.o
tpm-y += tpm-buf.o

+# TPM2 Asymmetric Key
+$(obj)/trusted_tpm2.o: $(obj)/tpm2key.asn1.h
+tpm-y += tpm2key.asn1.o
+tpm-y += tpm2_key.o
+
tpm-$(CONFIG_TCG_TPM2_HMAC) += tpm2-sessions.o
tpm-$(CONFIG_ACPI) += tpm_ppi.o eventlog/acpi.o
tpm-$(CONFIG_EFI) += eventlog/efi.o
diff --git a/drivers/char/tpm/tpm2_key.c b/drivers/char/tpm/tpm2_key.c
new file mode 100644
index 000000000000..0112362e432e
--- /dev/null
+++ b/drivers/char/tpm/tpm2_key.c
@@ -0,0 +1,111 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/oid_registry.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <crypto/tpm2_key.h>
+#include <asm/unaligned.h>
+#include "tpm2key.asn1.h"
+
+#undef pr_fmt
+#define pr_fmt(fmt) "tpm2_key: "fmt
+
+int tpm2_key_parent(void *context, size_t hdrlen,
+ unsigned char tag,
+ const void *value, size_t vlen)
+{
+ struct tpm2_key *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 *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 *ctx = context;
+
+ ctx->priv = value;
+ ctx->priv_len = vlen;
+
+ return 0;
+}
+
+/**
+ * tpm_key_decode() - Decode TPM2 ASN.1 key.
+ * @src: ASN.1 source.
+ * @src_len: ASN.1 source length.
+ * @key: TPM2 asymmetric key.
+ * @max_key_len: Maximum length of the TPM2 asymmetric key.
+ *
+ * Decodes TPM2 ASN.1 key on success. Returns POSIX error code on failure.
+ */
+int tpm2_key_decode(const u8 *src, u32 src_len, struct tpm2_key *key,
+ u32 max_key_len)
+{
+ struct tpm2_key ctx;
+ u32 blob_len;
+ int ret;
+
+ memset(&ctx, 0, sizeof(ctx));
+
+ ret = asn1_ber_decoder(&tpm2key_decoder, &ctx, src, src_len);
+ if (ret < 0)
+ return ret;
+
+ blob_len = ctx.priv_len + ctx.pub_len;
+ if (blob_len > max_key_len)
+ return -E2BIG;
+
+ ctx.blob_len = blob_len;
+ ctx.blob = kmalloc(blob_len, GFP_KERNEL);
+ if (!ctx.blob)
+ return -ENOMEM;
+
+ memcpy((void *)ctx.blob, ctx.priv, ctx.priv_len);
+ memcpy((void *)ctx.blob + ctx.priv_len, ctx.pub, ctx.pub_len);
+ ctx.priv = ctx.blob;
+ ctx.pub = ctx.blob + ctx.priv_len;
+
+ memcpy(key, &ctx, sizeof(ctx));
+ return 0;
+}
+EXPORT_SYMBOL_GPL(tpm2_key_decode);
diff --git a/security/keys/trusted-keys/tpm2key.asn1 b/drivers/char/tpm/tpm2key.asn1
similarity index 100%
rename from security/keys/trusted-keys/tpm2key.asn1
rename to drivers/char/tpm/tpm2key.asn1
diff --git a/include/crypto/tpm2_key.h b/include/crypto/tpm2_key.h
new file mode 100644
index 000000000000..acf41b2e0c92
--- /dev/null
+++ b/include/crypto/tpm2_key.h
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef __LINUX_TPM2_KEY_H__
+#define __LINUX_TPM2_KEY_H__
+
+#include <linux/slab.h>
+
+/*
+ * TPM2 ASN.1 key
+ */
+struct tpm2_key {
+ u32 parent;
+ const u8 *blob;
+ u32 blob_len;
+ const u8 *pub;
+ u32 pub_len;
+ const u8 *priv;
+ u32 priv_len;
+};
+
+int tpm2_key_decode(const u8 *src, u32 src_len, struct tpm2_key *key,
+ u32 max_key_len);
+
+/**
+ * tpm2_key_free() - Release TPM2 asymmetric key resources and reset values
+ * @key: TPM2 asymmetric key.
+ */
+static inline void tpm2_key_destroy(struct tpm2_key *key)
+{
+ kfree(key->blob);
+ memset(key, 0, sizeof(*key));
+}
+
+#endif /* __LINUX_TPM2_KEY_H__ */
diff --git a/security/keys/trusted-keys/Makefile b/security/keys/trusted-keys/Makefile
index f0f3b27f688b..2674d5c10fc9 100644
--- a/security/keys/trusted-keys/Makefile
+++ b/security/keys/trusted-keys/Makefile
@@ -7,9 +7,7 @@ obj-$(CONFIG_TRUSTED_KEYS) += trusted.o
trusted-y += trusted_core.o
trusted-$(CONFIG_TRUSTED_KEYS_TPM) += trusted_tpm1.o

-$(obj)/trusted_tpm2.o: $(obj)/tpm2key.asn1.h
trusted-$(CONFIG_TRUSTED_KEYS_TPM) += trusted_tpm2.o
-trusted-$(CONFIG_TRUSTED_KEYS_TPM) += tpm2key.asn1.o

trusted-$(CONFIG_TRUSTED_KEYS_TEE) += trusted_tee.o

diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index ec59f9389a2d..f255388d32b8 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -13,11 +13,10 @@

#include <keys/trusted-type.h>
#include <keys/trusted_tpm.h>
+#include <crypto/tpm2_key.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},
@@ -28,9 +27,9 @@ static struct tpm2_hash tpm2_hash_map[] = {

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)
+static int tpm2_trusted_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);
@@ -100,106 +99,6 @@ static int tpm2_key_encode(struct trusted_key_payload *payload,
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.
*
@@ -349,7 +248,8 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
goto out;
}

- blob_len = tpm2_key_encode(payload, options, &buf.data[offset], blob_len);
+ blob_len = tpm2_trusted_key_encode(payload, options, &buf.data[offset],
+ blob_len);

out:
tpm_buf_destroy(&sized);
@@ -389,21 +289,27 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
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;
+ struct tpm2_key key;
+ struct tpm_buf buf;
+ const u8 *blob, *pub;
int rc;
u32 attrs;

- rc = tpm2_key_decode(payload, options, &blob);
+ rc = tpm2_key_decode(payload->blob, payload->blob_len, &key, PAGE_SIZE);
if (rc) {
/* old form */
blob = payload->blob;
payload->old_format = 1;
+ } else {
+ blob = key.blob;
}

+ if (!blob)
+ return -ENOMEM;
+
/* new format carries keyhandle but old format doesn't */
if (!options->keyhandle)
return -EINVAL;
@@ -467,7 +373,8 @@ static int tpm2_load_cmd(struct tpm_chip *chip,

out:
if (blob != payload->blob)
- kfree(blob);
+ tpm2_key_destroy(&key);
+
tpm_buf_destroy(&buf);

if (rc > 0)
--
2.45.1