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102 lines
2.2 KiB
102 lines
2.2 KiB
// SPDX-License-Identifier: GPL-2.0 |
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#define pr_fmt(fmt) "TPM-PARSER: "fmt |
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#include <linux/module.h> |
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#include <linux/kernel.h> |
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#include <linux/export.h> |
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#include <linux/slab.h> |
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#include <linux/err.h> |
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#include <keys/asymmetric-subtype.h> |
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#include <keys/asymmetric-parser.h> |
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#include <crypto/asym_tpm_subtype.h> |
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#include "tpm.asn1.h" |
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struct tpm_parse_context { |
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const void *blob; |
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u32 blob_len; |
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}; |
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/* |
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* Note the key data of the ASN.1 blob. |
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*/ |
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int tpm_note_key(void *context, size_t hdrlen, |
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unsigned char tag, |
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const void *value, size_t vlen) |
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{ |
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struct tpm_parse_context *ctx = context; |
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ctx->blob = value; |
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ctx->blob_len = vlen; |
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return 0; |
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} |
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/* |
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* Parse a TPM-encrypted private key blob. |
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*/ |
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static struct tpm_key *tpm_parse(const void *data, size_t datalen) |
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{ |
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struct tpm_parse_context ctx; |
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long ret; |
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memset(&ctx, 0, sizeof(ctx)); |
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/* Attempt to decode the private key */ |
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ret = asn1_ber_decoder(&tpm_decoder, &ctx, data, datalen); |
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if (ret < 0) |
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goto error; |
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return tpm_key_create(ctx.blob, ctx.blob_len); |
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error: |
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return ERR_PTR(ret); |
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} |
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/* |
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* Attempt to parse a data blob for a key as a TPM private key blob. |
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*/ |
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static int tpm_key_preparse(struct key_preparsed_payload *prep) |
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{ |
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struct tpm_key *tk; |
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/* |
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* TPM 1.2 keys are max 2048 bits long, so assume the blob is no |
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* more than 4x that |
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*/ |
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if (prep->datalen > 256 * 4) |
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return -EMSGSIZE; |
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tk = tpm_parse(prep->data, prep->datalen); |
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if (IS_ERR(tk)) |
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return PTR_ERR(tk); |
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/* We're pinning the module by being linked against it */ |
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__module_get(asym_tpm_subtype.owner); |
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prep->payload.data[asym_subtype] = &asym_tpm_subtype; |
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prep->payload.data[asym_key_ids] = NULL; |
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prep->payload.data[asym_crypto] = tk; |
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prep->payload.data[asym_auth] = NULL; |
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prep->quotalen = 100; |
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return 0; |
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} |
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static struct asymmetric_key_parser tpm_key_parser = { |
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.owner = THIS_MODULE, |
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.name = "tpm_parser", |
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.parse = tpm_key_preparse, |
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}; |
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static int __init tpm_key_init(void) |
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{ |
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return register_asymmetric_key_parser(&tpm_key_parser); |
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} |
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static void __exit tpm_key_exit(void) |
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{ |
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unregister_asymmetric_key_parser(&tpm_key_parser); |
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} |
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module_init(tpm_key_init); |
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module_exit(tpm_key_exit); |
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MODULE_DESCRIPTION("TPM private key-blob parser"); |
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MODULE_LICENSE("GPL v2");
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