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tpm: add policy auth for EK to activate crendential
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Signed-off-by: Thore Sommer <[email protected]>
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@THS-on
THS-on committed Nov 12, 2024
1 parent ca807fb commit 936cce0
Showing 1 changed file with 115 additions and 28 deletions.
143 changes: 115 additions & 28 deletions keylime/src/tpm.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,9 @@ use log::*;
use std::convert::{TryFrom, TryInto};
use std::str::FromStr;
use thiserror::Error;
use tss_esapi::handles::SessionHandle;
use tss_esapi::interface_types::session_handles::PolicySession;
use tss_esapi::structures::{DigestList, SymmetricDefinition};

use openssl::{
hash::{Hasher, MessageDigest},
Expand All @@ -18,9 +21,7 @@ use openssl::{

use tss_esapi::{
abstraction::{
ak,
cipher::Cipher,
ek,
ak, ek,
pcr::{read_all, PcrData},
DefaultKey,
},
Expand Down Expand Up @@ -107,6 +108,47 @@ const IAK_AUTH_POLICY_SHA256: [u8; 32] = [
];
const UNIQUE_IAK: [u8; 3] = [0x49, 0x41, 0x4b];

// Source: TCG EK Credential Profile for TPM Family 2.0; Level 0 Version 2.5 Revision 2
// Section B.6
const POLICY_A_SHA384: [u8; 48] = [
0x8b, 0xbf, 0x22, 0x66, 0x53, 0x7c, 0x17, 0x1c, 0xb5, 0x6e, 0x40, 0x3c,
0x4d, 0xc1, 0xd4, 0xb6, 0x4f, 0x43, 0x26, 0x11, 0xdc, 0x38, 0x6e, 0x6f,
0x53, 0x20, 0x50, 0xc3, 0x27, 0x8c, 0x93, 0x0e, 0x14, 0x3e, 0x8b, 0xb1,
0x13, 0x38, 0x24, 0xcc, 0xb4, 0x31, 0x05, 0x38, 0x71, 0xc6, 0xdb, 0x53,
];
const POLICY_A_SHA512: [u8; 64] = [
0x1e, 0x3b, 0x76, 0x50, 0x2c, 0x8a, 0x14, 0x25, 0xaa, 0x0b, 0x7b, 0x3f,
0xc6, 0x46, 0xa1, 0xb0, 0xfa, 0xe0, 0x63, 0xb0, 0x3b, 0x53, 0x68, 0xf9,
0xc4, 0xcd, 0xde, 0xca, 0xff, 0x08, 0x91, 0xdd, 0x68, 0x2b, 0xac, 0x1a,
0x85, 0xd4, 0xd8, 0x32, 0xb7, 0x81, 0xea, 0x45, 0x19, 0x15, 0xde, 0x5f,
0xc5, 0xbf, 0x0d, 0xc4, 0xa1, 0x91, 0x7c, 0xd4, 0x2f, 0xa0, 0x41, 0xe3,
0xf9, 0x98, 0xe0, 0xee,
];
const POLICY_A_SM3_256: [u8; 32] = [
0xc6, 0x7f, 0x7d, 0x35, 0xf6, 0x6f, 0x3b, 0xec, 0x13, 0xc8, 0x9f, 0xe8,
0x98, 0x92, 0x1c, 0x65, 0x1b, 0x0c, 0xb5, 0xa3, 0x8a, 0x92, 0x69, 0x0a,
0x62, 0xa4, 0x3c, 0x00, 0x12, 0xe4, 0xfb, 0x8b,
];
const POLICY_C_SHA384: [u8; 48] = [
0xd6, 0x03, 0x2c, 0xe6, 0x1f, 0x2f, 0xb3, 0xc2, 0x40, 0xeb, 0x3c, 0xf6,
0xa3, 0x32, 0x37, 0xef, 0x2b, 0x6a, 0x16, 0xf4, 0x29, 0x3c, 0x22, 0xb4,
0x55, 0xe2, 0x61, 0xcf, 0xfd, 0x21, 0x7a, 0xd5, 0xb4, 0x94, 0x7c, 0x2d,
0x73, 0xe6, 0x30, 0x05, 0xee, 0xd2, 0xdc, 0x2b, 0x35, 0x93, 0xd1, 0x65,
];
const POLICY_C_SHA512: [u8; 64] = [
0x58, 0x9e, 0xe1, 0xe1, 0x46, 0x54, 0x47, 0x16, 0xe8, 0xde, 0xaf, 0xe6,
0xdb, 0x24, 0x7b, 0x01, 0xb8, 0x1e, 0x9f, 0x9c, 0x7d, 0xd1, 0x6b, 0x81,
0x4a, 0xa1, 0x59, 0x13, 0x87, 0x49, 0x10, 0x5f, 0xba, 0x53, 0x88, 0xdd,
0x1d, 0xea, 0x70, 0x2f, 0x35, 0x24, 0x0c, 0x18, 0x49, 0x33, 0x12, 0x1e,
0x2c, 0x61, 0xb8, 0xf5, 0x0d, 0x3e, 0xf9, 0x13, 0x93, 0xa4, 0x9a, 0x38,
0xc3, 0xf7, 0x3f, 0xc8,
];
const POLICY_C_SM3_256: [u8; 32] = [
0x2d, 0x4e, 0x81, 0x57, 0x8c, 0x35, 0x31, 0xd9, 0xbd, 0x1c, 0xdd, 0x7d,
0x02, 0xba, 0x29, 0x8d, 0x56, 0x99, 0xa3, 0xe3, 0x9f, 0xc3, 0x55, 0x1b,
0xfe, 0xff, 0xcf, 0x13, 0x2b, 0x49, 0xe1, 0x1d,
];

/// TpmError wraps all possible errors raised in tpm.rs
#[derive(Error, Debug)]
pub enum TpmError {
Expand Down Expand Up @@ -1153,18 +1195,13 @@ impl Context {
fn create_empty_session(
&mut self,
ses_type: SessionType,
symmetric: SymmetricDefinition,
hash_alg: HashingAlgorithm,

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) -> Result<AuthSession> {
let Some(session) = self
.inner
.start_auth_session(
None,
None,
None,
ses_type,
Cipher::aes_128_cfb().try_into().map_err(|source| {
TpmError::TSSSymmetricDefinitionFromCipher { source }
})?,
HashingAlgorithm::Sha256,
None, None, None, ses_type, symmetric, hash_alg,
)
.map_err(|source| {
TpmError::TSSStartAuthenticationSessionError { source }
Expand Down Expand Up @@ -1194,26 +1231,76 @@ impl Context {
ek: KeyHandle,
) -> Result<Digest> {
let (credential, secret) = parse_cred_and_secret(keyblob)?;
let mut policy_digests = DigestList::new();
let (parent_public, _, _) = self.inner.read_public(ek)?;
let ek_hash_alg = parent_public.name_hashing_algorithm();
let ek_symmetric =
parent_public.symmetric_algorithm().ok_or_else(|| {
TpmError::TSSReadPublicError {

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source: tss_esapi::Error::WrapperError(
tss_esapi::WrapperErrorKind::InvalidParam,
),
}
})?;
match ek_hash_alg {
HashingAlgorithm::Sha384 => {
policy_digests
.add(Digest::try_from(POLICY_A_SHA384.as_slice())?)?;
policy_digests
.add(Digest::try_from(POLICY_C_SHA384.as_slice())?)?;
}
HashingAlgorithm::Sha512 => {
policy_digests
.add(Digest::try_from(POLICY_A_SHA512.as_slice())?)?;
policy_digests
.add(Digest::try_from(POLICY_C_SHA512.as_slice())?)?;
}
HashingAlgorithm::Sm3_256 => {
policy_digests
.add(Digest::try_from(POLICY_A_SM3_256.as_slice())?)?;
policy_digests

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.add(Digest::try_from(POLICY_C_SM3_256.as_slice())?)?;
}
_ => (),
};

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let ek_auth = self.create_empty_session(SessionType::Policy)?;

// We authorize ses2 with PolicySecret(ENDORSEMENT) as per PolicyA
let _ = self.inner.execute_with_nullauth_session(|context| {
context.policy_secret(
ek_auth.try_into()?,
AuthHandle::Endorsement,
Default::default(),
Default::default(),
Default::default(),
None,
)
})?;
let ek_auth = self.create_empty_session(
SessionType::Policy,

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ek_symmetric.into(),
ek_hash_alg,
)?;

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// We authorize session according to the EK profile spec

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self.inner
.execute_with_sessions(
(Some(AuthSession::Password), Some(ek_auth), None),
|context| {
context.activate_credential(ak, ek, credential, secret)
.execute_with_temporary_object(
SessionHandle::from(ek_auth).into(),
|ctx, _| {
let _ = ctx.execute_with_nullauth_session(|ctx| {

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ctx.policy_secret(
PolicySession::try_from(ek_auth)?,

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AuthHandle::Endorsement,
Default::default(),
Default::default(),
Default::default(),
None,
)
})?;

if !policy_digests.is_empty() {
ctx.policy_or(
PolicySession::try_from(ek_auth)?,
policy_digests,
)?
}

ctx.execute_with_sessions(
(Some(AuthSession::Password), Some(ek_auth), None),
|ctx| {
ctx.activate_credential(
ak, ek, credential, secret,
)
},
)
},
)
.map_err(TpmError::from)
Expand Down

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