KEYS: asym_tpm: add skeleton for asym_tpm [ver #2]

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>
Tested-by: Marcel Holtmann <marcel@holtmann.org>
Reviewed-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: James Morris <james.morris@microsoft.com>

4 files changed, 118 insertions, 0 deletions

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 */