KEYS: asym_tpm: extract key size & public key [ver #2] (f8c54e1a) · Commits · 戴 / test

crypto/asymmetric_keys/asym_tpm.c

+112 −0

Original line number	Diff line number	Diff line
		@@ -7,6 +7,7 @@
		#include <linux/seq_file.h>
		#include <linux/scatterlist.h>
		#include <linux/tpm.h>
		#include <asm/unaligned.h>
		#include <keys/asymmetric-subtype.h>
		#include <crypto/asym_tpm_subtype.h>

		@@ -37,6 +38,110 @@ static void asym_tpm_destroy(void payload0, void payload3)
		kfree(tk);
		}

		/*
		* Parse enough information out of TPM_KEY structure:
		* TPM_STRUCT_VER -> 4 bytes
		* TPM_KEY_USAGE -> 2 bytes
		* TPM_KEY_FLAGS -> 4 bytes
		* TPM_AUTH_DATA_USAGE -> 1 byte
		* TPM_KEY_PARMS -> variable
		* UINT32 PCRInfoSize -> 4 bytes
		* BYTE* -> PCRInfoSize bytes
		* TPM_STORE_PUBKEY
		* UINT32 encDataSize;
		* BYTE* -> encDataSize;
		*
		* TPM_KEY_PARMS:
		* TPM_ALGORITHM_ID -> 4 bytes
		* TPM_ENC_SCHEME -> 2 bytes
		* TPM_SIG_SCHEME -> 2 bytes
		* UINT32 parmSize -> 4 bytes
		* BYTE* -> variable
		*/
		static int extract_key_parameters(struct tpm_key *tk)
		{
		const void *cur = tk->blob;
		uint32_t len = tk->blob_len;
		const void *pub_key;
		uint32_t sz;
		uint32_t key_len;

		if (len < 11)
		return -EBADMSG;

		/* Ensure this is a legacy key */
		if (get_unaligned_be16(cur + 4) != 0x0015)
		return -EBADMSG;

		/* Skip to TPM_KEY_PARMS */
		cur += 11;
		len -= 11;

		if (len < 12)
		return -EBADMSG;

		/* Make sure this is an RSA key */
		if (get_unaligned_be32(cur) != 0x00000001)
		return -EBADMSG;

		/* Make sure this is TPM_ES_RSAESPKCSv15 encoding scheme */
		if (get_unaligned_be16(cur + 4) != 0x0002)
		return -EBADMSG;

		/* Make sure this is TPM_SS_RSASSAPKCS1v15_DER signature scheme */
		if (get_unaligned_be16(cur + 6) != 0x0003)
		return -EBADMSG;

		sz = get_unaligned_be32(cur + 8);
		if (len < sz + 12)
		return -EBADMSG;

		/* Move to TPM_RSA_KEY_PARMS */
		len -= 12;
		cur += 12;

		/* Grab the RSA key length */
		key_len = get_unaligned_be32(cur);

		switch (key_len) {
		case 512:
		case 1024:
		case 1536:
		case 2048:
		break;
		default:
		return -EINVAL;
		}

		/* Move just past TPM_KEY_PARMS */
		cur += sz;
		len -= sz;

		if (len < 4)
		return -EBADMSG;

		sz = get_unaligned_be32(cur);
		if (len < 4 + sz)
		return -EBADMSG;

		/* Move to TPM_STORE_PUBKEY */
		cur += 4 + sz;
		len -= 4 + sz;

		/* Grab the size of the public key, it should jive with the key size */
		sz = get_unaligned_be32(cur);
		if (sz > 256)
		return -EINVAL;

		pub_key = cur + 4;

		tk->key_len = key_len;
		tk->pub_key = pub_key;
		tk->pub_key_len = sz;

		return 0;
		}

		/* Given the blob, parse it and load it into the TPM */
		struct tpm_key tpm_key_create(const void blob, uint32_t blob_len)
		{
		@@ -64,8 +169,15 @@ struct tpm_key tpm_key_create(const void blob, uint32_t blob_len)

		tk->blob_len = blob_len;

		r = extract_key_parameters(tk);
		if (r < 0)
		goto error_extract;

		return tk;

		error_extract:
		kfree(tk->blob);
		tk->blob_len = 0;
		error_memdup:
		kfree(tk);
		error:

include/crypto/asym_tpm_subtype.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -7,6 +7,9 @@
		struct tpm_key {
		void *blob;
		u32 blob_len;
		uint16_t key_len; /* Size in bits of the key */
		const void pub_key; / pointer inside blob to the public key bytes */
		uint16_t pub_key_len; /* length of the public key */
		};

		struct tpm_key tpm_key_create(const void blob, uint32_t blob_len);

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