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final changes to CTAP2.1 algorithm (#299)

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This commit is contained in:
kaczmarczyck
2021-04-07 09:07:46 +02:00
committed by GitHub
parent e7797a5683
commit 6216a3214d
4 changed files with 154 additions and 95 deletions
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143
src/ctap/mod.rs
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@@ -554,6 +554,68 @@ where
false
};
// MakeCredential always requires user presence.
// User verification depends on the PIN auth inputs, which are checked here.
// The ED flag is added later, if applicable.
let has_uv = pin_uv_auth_param.is_some();
let mut flags = match pin_uv_auth_param {
Some(pin_uv_auth_param) => {
// This case is not mentioned in CTAP2.1, so we keep 2.0 logic.
if self.persistent_store.pin_hash()?.is_none() {
return Err(Ctap2StatusCode::CTAP2_ERR_PIN_NOT_SET);
}
self.client_pin.verify_pin_uv_auth_token(
&client_data_hash,
&pin_uv_auth_param,
pin_uv_auth_protocol.ok_or(Ctap2StatusCode::CTAP2_ERR_MISSING_PARAMETER)?,
)?;
self.client_pin
.has_permission(PinPermission::MakeCredential)?;
self.client_pin.check_user_verified_flag()?;
// Checking for the correct permissions_rp_id is specified earlier.
// Error codes are identical though, so the implementation can be identical with
// GetAssertion.
self.client_pin.ensure_rp_id_permission(&rp_id)?;
UV_FLAG
}
None => {
if options.uv {
return Err(Ctap2StatusCode::CTAP2_ERR_INVALID_OPTION);
}
if self.persistent_store.has_always_uv()? {
return Err(Ctap2StatusCode::CTAP2_ERR_PUAT_REQUIRED);
}
// Corresponds to makeCredUvNotRqd set to true.
if options.rk && self.persistent_store.pin_hash()?.is_some() {
return Err(Ctap2StatusCode::CTAP2_ERR_PUAT_REQUIRED);
}
0x00
}
};
flags |= UP_FLAG | AT_FLAG;
let rp_id_hash = Sha256::hash(rp_id.as_bytes());
if let Some(exclude_list) = exclude_list {
for cred_desc in exclude_list {
if self
.persistent_store
.find_credential(&rp_id, &cred_desc.key_id, !has_uv)?
.is_some()
|| self
.decrypt_credential_source(cred_desc.key_id, &rp_id_hash)?
.is_some()
{
// Perform this check, so bad actors can't brute force exclude_list
// without user interaction.
let _ = (self.check_user_presence)(cid);
return Err(Ctap2StatusCode::CTAP2_ERR_CREDENTIAL_EXCLUDED);
}
}
}
(self.check_user_presence)(cid)?;
self.client_pin.clear_token_flags();
let mut cred_protect_policy = extensions.cred_protect;
if cred_protect_policy.unwrap_or(CredentialProtectionPolicy::UserVerificationOptional)
< DEFAULT_CRED_PROTECT.unwrap_or(CredentialProtectionPolicy::UserVerificationOptional)
@@ -576,74 +638,17 @@ where
None
};
let has_extension_output = extensions.hmac_secret
|| cred_protect_policy.is_some()
|| extensions.cred_protect.is_some()
|| min_pin_length
|| has_cred_blob_output;
if has_extension_output {
flags |= ED_FLAG
};
let large_blob_key = match (options.rk, extensions.large_blob_key) {
(true, Some(true)) => Some(self.rng.gen_uniform_u8x32().to_vec()),
_ => None,
};
let rp_id_hash = Sha256::hash(rp_id.as_bytes());
if let Some(exclude_list) = exclude_list {
for cred_desc in exclude_list {
if self
.persistent_store
.find_credential(&rp_id, &cred_desc.key_id, pin_uv_auth_param.is_none())?
.is_some()
|| self
.decrypt_credential_source(cred_desc.key_id, &rp_id_hash)?
.is_some()
{
// Perform this check, so bad actors can't brute force exclude_list
// without user interaction.
(self.check_user_presence)(cid)?;
return Err(Ctap2StatusCode::CTAP2_ERR_CREDENTIAL_EXCLUDED);
}
}
}
// MakeCredential always requires user presence.
// User verification depends on the PIN auth inputs, which are checked here.
let ed_flag = if has_extension_output { ED_FLAG } else { 0 };
let flags = match pin_uv_auth_param {
Some(pin_uv_auth_param) => {
if self.persistent_store.pin_hash()?.is_none() {
// Specification is unclear, could be CTAP2_ERR_INVALID_OPTION.
return Err(Ctap2StatusCode::CTAP2_ERR_PIN_NOT_SET);
}
self.client_pin.verify_pin_uv_auth_token(
&client_data_hash,
&pin_uv_auth_param,
pin_uv_auth_protocol.ok_or(Ctap2StatusCode::CTAP2_ERR_MISSING_PARAMETER)?,
)?;
self.client_pin
.has_permission(PinPermission::MakeCredential)?;
self.client_pin.check_user_verified_flag()?;
// Checking for the correct permissions_rp_id is specified earlier.
// Error codes are identical though, so the implementation can be identical with
// GetAssertion.
self.client_pin.ensure_rp_id_permission(&rp_id)?;
UP_FLAG | UV_FLAG | AT_FLAG | ed_flag
}
None => {
if self.persistent_store.has_always_uv()? {
return Err(Ctap2StatusCode::CTAP2_ERR_PUAT_REQUIRED);
}
// Corresponds to makeCredUvNotRqd set to true.
if options.rk && self.persistent_store.pin_hash()?.is_some() {
return Err(Ctap2StatusCode::CTAP2_ERR_PUAT_REQUIRED);
}
if options.uv {
return Err(Ctap2StatusCode::CTAP2_ERR_INVALID_OPTION);
}
UP_FLAG | AT_FLAG | ed_flag
}
};
(self.check_user_presence)(cid)?;
self.client_pin.clear_token_flags();
let sk = crypto::ecdsa::SecKey::gensk(self.rng);
let pk = sk.genpk();
@@ -699,9 +704,10 @@ where
} else {
None
};
let cred_protect_output = extensions.cred_protect.and(cred_protect_policy);
let extensions_output = cbor_map_options! {
"hmac-secret" => hmac_secret_output,
"credProtect" => cred_protect_policy,
"credProtect" => cred_protect_output,
"minPinLength" => min_pin_length_output,
"credBlob" => cred_blob_output,
};
@@ -904,8 +910,8 @@ where
let has_uv = pin_uv_auth_param.is_some();
let mut flags = match pin_uv_auth_param {
Some(pin_uv_auth_param) => {
// This case is not mentioned in CTAP2.1, so we keep 2.0 logic.
if self.persistent_store.pin_hash()?.is_none() {
// Specification is unclear, could be CTAP2_ERR_UNSUPPORTED_OPTION.
return Err(Ctap2StatusCode::CTAP2_ERR_PIN_NOT_SET);
}
self.client_pin.verify_pin_uv_auth_token(
@@ -923,12 +929,12 @@ where
UV_FLAG
}
None => {
if self.persistent_store.has_always_uv()? {
return Err(Ctap2StatusCode::CTAP2_ERR_PUAT_REQUIRED);
}
if options.uv {
return Err(Ctap2StatusCode::CTAP2_ERR_INVALID_OPTION);
}
if options.up && self.persistent_store.has_always_uv()? {
return Err(Ctap2StatusCode::CTAP2_ERR_PUAT_REQUIRED);
}
0x00
}
};
@@ -970,15 +976,14 @@ where
(credential, stored_credentials)
};
let credential = credential.ok_or(Ctap2StatusCode::CTAP2_ERR_NO_CREDENTIALS)?;
// This check comes before CTAP2_ERR_NO_CREDENTIALS in CTAP 2.0.
// For CTAP 2.1, it was moved to a later protocol step.
if options.up {
(self.check_user_presence)(cid)?;
self.client_pin.clear_token_flags();
}
let credential = credential.ok_or(Ctap2StatusCode::CTAP2_ERR_NO_CREDENTIALS)?;
self.increment_global_signature_counter()?;
let assertion_input = AssertionInput {