diff options
| -rw-r--r-- | crypto/asymmetric_keys/Kconfig | 9 | ||||
| -rw-r--r-- | crypto/asymmetric_keys/Makefile | 11 | ||||
| -rw-r--r-- | crypto/asymmetric_keys/tpm.asn1 | 5 | ||||
| -rw-r--r-- | crypto/asymmetric_keys/tpm_parser.c | 102 |
4 files changed, 127 insertions, 0 deletions
diff --git a/crypto/asymmetric_keys/Kconfig b/crypto/asymmetric_keys/Kconfig index b75555c7d8ae..88353a9ebc9b 100644 --- a/crypto/asymmetric_keys/Kconfig +++ b/crypto/asymmetric_keys/Kconfig @@ -52,6 +52,15 @@ config PKCS8_PRIVATE_KEY_PARSER private key data and provides the ability to instantiate a crypto key from that data. +config TPM_KEY_PARSER + tristate "TPM private key parser" + depends on ASYMMETRIC_TPM_KEY_SUBTYPE + select ASN1 + help + This option provides support for parsing TPM format blobs for + private key data and provides the ability to instantiate a crypto key + from that data. + config PKCS7_MESSAGE_PARSER tristate "PKCS#7 message parser" depends on X509_CERTIFICATE_PARSER diff --git a/crypto/asymmetric_keys/Makefile b/crypto/asymmetric_keys/Makefile index 73fbe650ff1d..28b91adba2ae 100644 --- a/crypto/asymmetric_keys/Makefile +++ b/crypto/asymmetric_keys/Makefile @@ -75,3 +75,14 @@ verify_signed_pefile-y := \ $(obj)/mscode_parser.o: $(obj)/mscode.asn1.h $(obj)/mscode.asn1.h $(obj)/mscode.asn1.o: $(obj)/mscode.asn1.c $(obj)/mscode.asn1.h + +# +# TPM private key parsing +# +obj-$(CONFIG_TPM_KEY_PARSER) += tpm_key_parser.o +tpm_key_parser-y := \ + tpm.asn1.o \ + tpm_parser.o + +$(obj)/tpm_parser.o: $(obj)/tpm.asn1.h +$(obj)/tpm.asn1.o: $(obj)/tpm.asn1.c $(obj)/tpm.asn1.h diff --git a/crypto/asymmetric_keys/tpm.asn1 b/crypto/asymmetric_keys/tpm.asn1 new file mode 100644 index 000000000000..d7f194232f30 --- /dev/null +++ b/crypto/asymmetric_keys/tpm.asn1 @@ -0,0 +1,5 @@ +-- +-- Unencryted TPM Blob. For details of the format, see: +-- http://david.woodhou.se/draft-woodhouse-cert-best-practice.html#I-D.mavrogiannopoulos-tpmuri +-- +PrivateKeyInfo ::= OCTET STRING ({ tpm_note_key }) diff --git a/crypto/asymmetric_keys/tpm_parser.c b/crypto/asymmetric_keys/tpm_parser.c new file mode 100644 index 000000000000..96405d8dcd98 --- /dev/null +++ b/crypto/asymmetric_keys/tpm_parser.c @@ -0,0 +1,102 @@ +// SPDX-License-Identifier: GPL-2.0 +#define pr_fmt(fmt) "TPM-PARSER: "fmt +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/export.h> +#include <linux/slab.h> +#include <linux/err.h> +#include <keys/asymmetric-subtype.h> +#include <keys/asymmetric-parser.h> +#include <crypto/asym_tpm_subtype.h> +#include "tpm.asn1.h" + +struct tpm_parse_context { + const void *blob; + u32 blob_len; +}; + +/* + * Note the key data of the ASN.1 blob. + */ +int tpm_note_key(void *context, size_t hdrlen, + unsigned char tag, + const void *value, size_t vlen) +{ + struct tpm_parse_context *ctx = context; + + ctx->blob = value; + ctx->blob_len = vlen; + + return 0; +} + +/* + * Parse a TPM-encrypted private key blob. + */ +static struct tpm_key *tpm_parse(const void *data, size_t datalen) +{ + struct tpm_parse_context ctx; + long ret; + + memset(&ctx, 0, sizeof(ctx)); + + /* Attempt to decode the private key */ + ret = asn1_ber_decoder(&tpm_decoder, &ctx, data, datalen); + if (ret < 0) + goto error; + + return tpm_key_create(ctx.blob, ctx.blob_len); + +error: + return ERR_PTR(ret); +} +/* + * Attempt to parse a data blob for a key as a TPM private key blob. + */ +static int tpm_key_preparse(struct key_preparsed_payload *prep) +{ + struct tpm_key *tk; + + /* + * TPM 1.2 keys are max 2048 bits long, so assume the blob is no + * more than 4x that + */ + if (prep->datalen > 256 * 4) + return -EMSGSIZE; + + tk = tpm_parse(prep->data, prep->datalen); + + if (IS_ERR(tk)) + return PTR_ERR(tk); + + /* We're pinning the module by being linked against it */ + __module_get(asym_tpm_subtype.owner); + prep->payload.data[asym_subtype] = &asym_tpm_subtype; + prep->payload.data[asym_key_ids] = NULL; + prep->payload.data[asym_crypto] = tk; + prep->payload.data[asym_auth] = NULL; + prep->quotalen = 100; + return 0; +} + +static struct asymmetric_key_parser tpm_key_parser = { + .owner = THIS_MODULE, + .name = "tpm_parser", + .parse = tpm_key_preparse, +}; + +static int __init tpm_key_init(void) +{ + return register_asymmetric_key_parser(&tpm_key_parser); +} + +static void __exit tpm_key_exit(void) +{ + unregister_asymmetric_key_parser(&tpm_key_parser); +} + +module_init(tpm_key_init); +module_exit(tpm_key_exit); + +MODULE_DESCRIPTION("TPM private key-blob parser"); +MODULE_LICENSE("GPL v2"); |