[PATCH RFC v2 4/5] KEYS: trusted: Migrate tpm2_key_{encode,decode}() to TPM driver

Jarkko Sakkinen
2024-05-19T00:26:58Z

Migrate tpm2_key_{encode,decode}() to TPM driver and export the symbols
to make them callable from trusted keys.

Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
drivers/char/tpm/Kconfig | 5 +
drivers/char/tpm/Makefile | 5 +
drivers/char/tpm/tpm2_key.c | 181 +++++++++++++++++
.../char/tpm}/tpm2key.asn1 | 0
include/crypto/tpm2_key.h | 33 ++++
security/keys/trusted-keys/Makefile | 2 -
security/keys/trusted-keys/trusted_tpm2.c | 187 ++----------------
7 files changed, 242 insertions(+), 171 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 db41301e63f2..d5d06cc96932 100644
--- a/drivers/char/tpm/Kconfig
+++ b/drivers/char/tpm/Kconfig
@@ -3,10 +3,15 @@
# TPM device configuration
#

+config TCG_TPM2_KEY
+ bool
+
menuconfig TCG_TPM
tristate "TPM Hardware Support"
depends on HAS_IOMEM
imply SECURITYFS
+ select ASN1
+ select ASN1_ENCODER
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..e09441efb0f0
--- /dev/null
+++ b/drivers/char/tpm/tpm2_key.c
@@ -0,0 +1,181 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#define pr_fmt(fmt) "tpm2_key: "fmt
+
+#include <linux/asn1_encoder.h>
+#include <linux/asn1_decoder.h>
+#include <linux/oid_registry.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <crypto/tpm2_key.h>
+#include <asm/unaligned.h>
+#include <keys/trusted-type.h>
+#include "tpm2key.asn1.h"
+
+static u32 tpm2key_oid[] = { 2, 23, 133, 10, 1, 5 };
+
+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;
+}
+
+/**
+ * tpm2_key_encode() - Encode TPM2 ASN.1 key.
+ * @blob: Decoded blob.
+ * @blob_auth_len: Authorization length.
+ * @key_handle: TPM2 handle of the key.
+ * @src: ASN.1 source.
+ *
+ * Encodes TPM2 ASN.1 key on success. Returns POSIX error code on failure.
+ */
+int tpm2_key_encode(u8 *blob, u32 blob_auth_len, u32 key_handle, u8 *src)
+{
+ 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 (blob_auth_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, key_handle);
+ work = asn1_encode_octet_string(work, end_work, pub, pub_len);
+ work = asn1_encode_octet_string(work, end_work, priv, priv_len);
+
+ work1 = blob;
+ work1 = asn1_encode_sequence(work1, work1 + MAX_BLOB_SIZE, scratch, work - scratch);
+ if (IS_ERR(work1)) {
+ ret = PTR_ERR(work1);
+ pr_err("ASN.1 encoder failed with %d\n", ret);
+ return ret;
+ }
+
+ return work1 - blob;
+}
+EXPORT_SYMBOL_GPL(tpm2_key_encode);
+
+/**
+ * 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;
+ int ret;
+
+ memset(&ctx, 0, sizeof(ctx));
+
+ ret = asn1_ber_decoder(&tpm2key_decoder, &ctx, src, src_len);
+ if (ret < 0)
+ return ret;
+
+ if (ctx.priv_len + ctx.pub_len > max_key_len)
+ return -EINVAL;
+
+ ctx.priv = kmemdup(ctx.priv, ctx.priv_len, GFP_KERNEL);
+ if (!ctx.priv)
+ return -ENOMEM;
+
+ ctx.pub = kmemdup(ctx.pub, ctx.pub_len, GFP_KERNEL);
+ if (!ctx.pub) {
+ kfree(ctx.priv);
+ return -ENOMEM;
+ }
+
+ 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..e5d3330afef5
--- /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 *pub;
+ u32 pub_len;
+ const u8 *priv;
+ u32 priv_len;
+};
+
+int tpm2_key_encode(u8 *blob, u32 blob_auth_len, u32 key_handle, u8 *src);
+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->priv);
+ kfree(key->pub);
+ 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 dbdd6a318b8b..3e1140914ca4 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},
@@ -26,169 +25,6 @@ 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;
- 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"))
- 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 (IS_ERR(work1)) {
- ret = PTR_ERR(work1);
- pr_err("ASN.1 encode error %d\n", ret);
- return ret;
- }
-
- 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;
-}
-
/**
* tpm2_buf_append_auth() - append TPMS_AUTH_COMMAND to the buffer.
*
@@ -338,7 +174,8 @@ 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_key_encode(payload->blob, options->blobauth_len,
+ options->keyhandle, &buf.data[offset]);

out:
tpm_buf_destroy(&sized);
@@ -378,20 +215,32 @@ 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;
+ struct tpm2_key key;
+ struct tpm_buf buf;
u8 *blob, *pub;
int rc;
u32 attrs;

- rc = tpm2_key_decode(payload, options, &blob);
+ rc = tpm2_key_decode(payload->blob, payload->blob_len, &key,
+ MAX_BLOB_SIZE);
if (rc) {
- /* old form */
+ /* legacy format: */
blob = payload->blob;
payload->old_format = 1;
+ } else {
+ blob = kmalloc(key.priv_len + key.pub_len + 4, GFP_KERNEL);
+ if (blob) {
+ options->keyhandle = key.parent;
+ memcpy(blob, key.priv, key.priv_len);
+ memcpy(&blob[key.priv_len], key.pub, key.pub_len);
+ }
}
+ tpm2_key_destroy(&key);
+ if (!blob)
+ return -ENOMEM;

/* new format carries keyhandle but old format doesn't */
if (!options->keyhandle)
--
2.45.1