Extend TPMKey ASN.1 speciication [1] with an optional 'parentName' attribute containing TPM name of the parent key (in other words, TPMT_HA blob).
The life-cycle for trusted keys will now proceed as follows: 1. Encode parent's name to the 'paretName' during tpm2_key_encode(). 2. During tpm2_unseal_trusted, read parent's name from 'parentName'. When the attribute is not available, fallback on doing tpm2_read_public(). In other words, in the common (i.e., not loading a legacy key blob), tpm2_read_public() will now only happen at the time when a key is first created. [1] https://www.hansenpartnership.com/draft-bottomley-tpm2-keys.txt Signed-off-by: Jarkko Sakkinen <[email protected]> --- v2: - A new patch. --- security/keys/trusted-keys/tpm2key.asn1 | 17 +++- security/keys/trusted-keys/trusted_tpm2.c | 97 ++++++++++++++++------- 2 files changed, 84 insertions(+), 30 deletions(-) diff --git a/security/keys/trusted-keys/tpm2key.asn1 b/security/keys/trusted-keys/tpm2key.asn1 index f57f869ad600..080f0e399982 100644 --- a/security/keys/trusted-keys/tpm2key.asn1 +++ b/security/keys/trusted-keys/tpm2key.asn1 @@ -1,11 +1,26 @@ --- --- ASN.1 for TPM 2.0 keys --- +TPMPolicy ::= SEQUENCE { + commandCode [0] EXPLICIT INTEGER, + commandPolicy [1] EXPLICIT OCTET STRING +} + +TPMAuthPolicy ::= SEQUENCE { + name [0] EXPLICIT UTF8String OPTIONAL, + policy [1] EXPLICIT SEQUENCE OF TPMPolicy +} TPMKey ::= SEQUENCE { type OBJECT IDENTIFIER ({tpm2_key_type}), emptyAuth [0] EXPLICIT BOOLEAN OPTIONAL, + policy [1] EXPLICIT SEQUENCE OF TPMPolicy OPTIONAL, + secret [2] EXPLICIT OCTET STRING OPTIONAL, + authPolicy [3] EXPLICIT SEQUENCE OF TPMAuthPolicy OPTIONAL, + description [4] EXPLICIT UTF8String OPTIONAL, + rsaParent [5] EXPLICIT BOOLEAN OPTIONAL, + parentName [6] EXPLICIT OCTET STRING ({tpm2_key_parent_name}), parent INTEGER ({tpm2_key_parent}), pubkey OCTET STRING ({tpm2_key_pub}), privkey OCTET STRING ({tpm2_key_priv}) - } +} diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c index 88bafbcc011a..3608dc9f7fa4 100644 --- a/security/keys/trusted-keys/trusted_tpm2.c +++ b/security/keys/trusted-keys/trusted_tpm2.c @@ -20,16 +20,26 @@ static u32 tpm2key_oid[] = { 2, 23, 133, 10, 1, 5 }; +enum tpm_key_tag { + TPM_KEY_TAG_EMPTY_AUTH = 0, + TPM_KEY_TAG_POLICY = 1, + TPM_KEY_TAG_SECRET = 2, + TPM_KEY_TAG_AUTH_POLICY = 3, + TPM_KEY_TAG_DESCRIPTION = 4, + TPM_KEY_TAG_RSA_PARENT = 5, + TPM_KEY_TAG_PARENT_NAME = 6, +}; + static int tpm2_key_encode(struct trusted_key_payload *payload, struct trusted_key_options *options, - u8 *src, u32 len) + u8 *src, u32 len, u8 *parent_name, + u16 parent_name_size) { 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; + u8 *end_work, *name_end; u16 priv_len, pub_len; + u8 *work, *work1; + u8 *priv, *pub; int ret; priv_len = get_unaligned_be16(src) + 2; @@ -40,23 +50,41 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, pub_len = get_unaligned_be16(src) + 2; pub = src; + u8 *scratch __free(kfree) = kmalloc(SCRATCH_SIZE, GFP_KERNEL); if (!scratch) return -ENOMEM; + work = scratch; + end_work = scratch + SCRATCH_SIZE; + 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")) { - ret = PTR_ERR(w); - goto err; + u8 *bool_end; + u8 bool[3]; + + bool_end = asn1_encode_boolean(&bool[0], &bool[sizeof(bool)], + true); + if (IS_ERR(bool_end)) { + pr_err("BUG: Boolean failed to encode\n"); + return PTR_ERR(bool_end); } - work = asn1_encode_tag(work, end_work, 0, bool, w - bool); + + work = asn1_encode_tag(work, end_work, TPM_KEY_TAG_EMPTY_AUTH, + bool, bool_end - bool); } + u8 *name_encoded __free(kfree) = kmalloc(SCRATCH_SIZE, GFP_KERNEL); + if (!name_encoded) + return -ENOMEM; + + name_end = asn1_encode_octet_string(&name_encoded[0], + &name_encoded[SCRATCH_SIZE], + parent_name, parent_name_size); + work = asn1_encode_tag(work, end_work, TPM_KEY_TAG_PARENT_NAME, + name_encoded, name_end - name_encoded); + /* * Assume both octet strings will encode to a 2 byte definite length * @@ -65,8 +93,7 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, */ if (WARN(work - scratch + pub_len + priv_len + 14 > SCRATCH_SIZE, "BUG: scratch buffer is too small")) { - ret = -EINVAL; - goto err; + return -EINVAL; } work = asn1_encode_integer(work, end_work, options->keyhandle); @@ -79,15 +106,10 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, if (IS_ERR(work1)) { ret = PTR_ERR(work1); pr_err("BUG: ASN.1 encoder failed with %d\n", ret); - goto err; + return ret; } - kfree(scratch); return work1 - payload->blob; - -err: - kfree(scratch); - return ret; } struct tpm2_key_context { @@ -96,11 +118,13 @@ struct tpm2_key_context { u32 pub_len; const u8 *priv; u32 priv_len; + const u8 *name; + u32 name_len; }; static int tpm2_key_decode(struct trusted_key_payload *payload, struct trusted_key_options *options, - u8 **buf) + u8 **buf, u8 *parent_name, u16 *parent_name_size) { int ret; struct tpm2_key_context ctx; @@ -127,6 +151,8 @@ static int tpm2_key_decode(struct trusted_key_payload *payload, blob += ctx.priv_len; memcpy(blob, ctx.pub, ctx.pub_len); + memcpy(parent_name, ctx.name, ctx.name_len); + *parent_name_size = ctx.name_len; return 0; } @@ -190,6 +216,16 @@ int tpm2_key_priv(void *context, size_t hdrlen, return 0; } +int tpm2_key_parent_name(void *context, size_t hdrlen, unsigned char tag, + const void *value, size_t vlen) +{ + struct tpm2_key_context *ctx = context; + + ctx->name = value; + ctx->name_len = vlen; + + return 0; +} /** * tpm2_buf_append_auth() - append TPMS_AUTH_COMMAND to the buffer. * @@ -347,7 +383,8 @@ 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, options, &buf.data[offset], + blob_len, parent_name, parent_name_size); if (blob_len < 0) rc = blob_len; @@ -602,7 +639,7 @@ int tpm2_unseal_trusted(struct tpm_chip *chip, * Try to decode the provided blob as an ASN.1 blob. Assume that the * blob is in the legacy format if decoding does not end successfully. */ - rc = tpm2_key_decode(payload, options, &blob); + rc = tpm2_key_decode(payload, options, &blob, &parent_name[0], &parent_name_size); if (rc) { blob = payload->blob; payload->old_format = 1; @@ -613,16 +650,18 @@ int tpm2_unseal_trusted(struct tpm_chip *chip, if (!options->keyhandle) return -EINVAL; + if (!parent_name_size) { + rc = tpm2_read_public(chip, options->keyhandle, parent_name); + if (rc < 0) + goto out; + + parent_name_size = rc; + } + rc = tpm_try_get_ops(chip); if (rc) return rc; - rc = tpm2_read_public(chip, options->keyhandle, parent_name); - if (rc < 0) - goto out; - - parent_name_size = rc; - rc = tpm2_load_cmd(chip, payload, options, parent_name, parent_name_size, blob, &blob_handle); if (rc) -- 2.52.0
