diff options
| -rw-r--r-- | crypto/asymmetric_keys/asym_tpm.c | 112 | ||||
| -rw-r--r-- | include/crypto/asym_tpm_subtype.h | 3 |
2 files changed, 115 insertions, 0 deletions
diff --git a/crypto/asymmetric_keys/asym_tpm.c b/crypto/asymmetric_keys/asym_tpm.c index d0b2b97e8e54..308c51e055a4 100644 --- a/crypto/asymmetric_keys/asym_tpm.c +++ b/crypto/asymmetric_keys/asym_tpm.c @@ -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: diff --git a/include/crypto/asym_tpm_subtype.h b/include/crypto/asym_tpm_subtype.h index 03550b850998..48198c36d6b9 100644 --- a/include/crypto/asym_tpm_subtype.h +++ b/include/crypto/asym_tpm_subtype.h @@ -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); |