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Subject[PATCH 10/22] KEYS: asym_tpm: add skeleton for asym_tpm
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Date
From: Denis Kenzior <denkenz@gmail.com>

This patch adds the basic skeleton for the asym_tpm asymmetric key
subtype.

Signed-off-by: Denis Kenzior <denkenz@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
---

crypto/asymmetric_keys/Kconfig | 11 +++++
crypto/asymmetric_keys/Makefile | 1
crypto/asymmetric_keys/asym_tpm.c | 90 +++++++++++++++++++++++++++++++++++++
include/crypto/asym_tpm_subtype.h | 16 +++++++
4 files changed, 118 insertions(+)
create mode 100644 crypto/asymmetric_keys/asym_tpm.c
create mode 100644 include/crypto/asym_tpm_subtype.h

diff --git a/crypto/asymmetric_keys/Kconfig b/crypto/asymmetric_keys/Kconfig
index 66a7dad7ed3d..b75555c7d8ae 100644
--- a/crypto/asymmetric_keys/Kconfig
+++ b/crypto/asymmetric_keys/Kconfig
@@ -21,6 +21,17 @@ config ASYMMETRIC_PUBLIC_KEY_SUBTYPE
appropriate hash algorithms (such as SHA-1) must be available.
ENOPKG will be reported if the requisite algorithm is unavailable.

+config ASYMMETRIC_TPM_KEY_SUBTYPE
+ tristate "Asymmetric TPM backed private key subtype"
+ depends on TCG_TPM
+ select CRYPTO_HMAC
+ select CRYPTO_SHA1
+ select CRYPTO_HASH_INFO
+ help
+ This option provides support for TPM backed private key type handling.
+ Operations such as sign, verify, encrypt, decrypt are performed by
+ the TPM after the private key is loaded.
+
config X509_CERTIFICATE_PARSER
tristate "X.509 certificate parser"
depends on ASYMMETRIC_PUBLIC_KEY_SUBTYPE
diff --git a/crypto/asymmetric_keys/Makefile b/crypto/asymmetric_keys/Makefile
index c38424f55b08..73fbe650ff1d 100644
--- a/crypto/asymmetric_keys/Makefile
+++ b/crypto/asymmetric_keys/Makefile
@@ -11,6 +11,7 @@ asymmetric_keys-y := \
signature.o

obj-$(CONFIG_ASYMMETRIC_PUBLIC_KEY_SUBTYPE) += public_key.o
+obj-$(CONFIG_ASYMMETRIC_TPM_KEY_SUBTYPE) += asym_tpm.o

#
# X.509 Certificate handling
diff --git a/crypto/asymmetric_keys/asym_tpm.c b/crypto/asymmetric_keys/asym_tpm.c
new file mode 100644
index 000000000000..d0b2b97e8e54
--- /dev/null
+++ b/crypto/asymmetric_keys/asym_tpm.c
@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: GPL-2.0
+#define pr_fmt(fmt) "ASYM-TPM: "fmt
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/export.h>
+#include <linux/kernel.h>
+#include <linux/seq_file.h>
+#include <linux/scatterlist.h>
+#include <linux/tpm.h>
+#include <keys/asymmetric-subtype.h>
+#include <crypto/asym_tpm_subtype.h>
+
+/*
+ * Provide a part of a description of the key for /proc/keys.
+ */
+static void asym_tpm_describe(const struct key *asymmetric_key,
+ struct seq_file *m)
+{
+ struct tpm_key *tk = asymmetric_key->payload.data[asym_crypto];
+
+ if (!tk)
+ return;
+
+ seq_printf(m, "TPM1.2/Blob");
+}
+
+static void asym_tpm_destroy(void *payload0, void *payload3)
+{
+ struct tpm_key *tk = payload0;
+
+ if (!tk)
+ return;
+
+ kfree(tk->blob);
+ tk->blob_len = 0;
+
+ kfree(tk);
+}
+
+/* Given the blob, parse it and load it into the TPM */
+struct tpm_key *tpm_key_create(const void *blob, uint32_t blob_len)
+{
+ int r;
+ struct tpm_key *tk;
+
+ r = tpm_is_tpm2(NULL);
+ if (r < 0)
+ goto error;
+
+ /* We don't support TPM2 yet */
+ if (r > 0) {
+ r = -ENODEV;
+ goto error;
+ }
+
+ r = -ENOMEM;
+ tk = kzalloc(sizeof(struct tpm_key), GFP_KERNEL);
+ if (!tk)
+ goto error;
+
+ tk->blob = kmemdup(blob, blob_len, GFP_KERNEL);
+ if (!tk->blob)
+ goto error_memdup;
+
+ tk->blob_len = blob_len;
+
+ return tk;
+
+error_memdup:
+ kfree(tk);
+error:
+ return ERR_PTR(r);
+}
+EXPORT_SYMBOL_GPL(tpm_key_create);
+
+/*
+ * TPM-based asymmetric key subtype
+ */
+struct asymmetric_key_subtype asym_tpm_subtype = {
+ .owner = THIS_MODULE,
+ .name = "asym_tpm",
+ .name_len = sizeof("asym_tpm") - 1,
+ .describe = asym_tpm_describe,
+ .destroy = asym_tpm_destroy,
+};
+EXPORT_SYMBOL_GPL(asym_tpm_subtype);
+
+MODULE_DESCRIPTION("TPM based asymmetric key subtype");
+MODULE_AUTHOR("Intel Corporation");
+MODULE_LICENSE("GPL v2");
diff --git a/include/crypto/asym_tpm_subtype.h b/include/crypto/asym_tpm_subtype.h
new file mode 100644
index 000000000000..03550b850998
--- /dev/null
+++ b/include/crypto/asym_tpm_subtype.h
@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0
+#ifndef _LINUX_ASYM_TPM_SUBTYPE_H
+#define _LINUX_ASYM_TPM_SUBTYPE_H
+
+#include <linux/keyctl.h>
+
+struct tpm_key {
+ void *blob;
+ u32 blob_len;
+};
+
+struct tpm_key *tpm_key_create(const void *blob, uint32_t blob_len);
+
+extern struct asymmetric_key_subtype asym_tpm_subtype;
+
+#endif /* _LINUX_ASYM_TPM_SUBTYPE_H */
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