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crypto: Start checking and cancelling our SAS flows.

master
Damir Jelić 2020-07-24 17:51:20 +02:00
parent 46c1657643
commit 670755bfce
2 changed files with 136 additions and 32 deletions
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2
matrix_sdk_crypto/src/verification/mod.rs
View File

@ -26,7 +26,7 @@ use crate::{Account, Device};
#[allow(dead_code)]
mod sas;
#[derive(Clone)]
#[derive(Clone, Debug)]
struct SasIds {
account: Account,
other_device: Device,

148
matrix_sdk_crypto/src/verification/sas.rs
View File

@ -20,6 +20,7 @@ use olm_rs::sas::OlmSas;
use matrix_sdk_common::events::{
key::verification::{
accept::AcceptEventContent,
cancel::CancelCode,
key::KeyEventContent,
mac::MacEventContent,
start::{MSasV1Content, MSasV1ContentOptions, StartEventContent},
@ -35,6 +36,7 @@ use super::{get_decimal, get_emoji, get_mac_content, receive_mac_event, SasIds};
use crate::{Account, Device};
#[derive(Clone)]
/// Short authentication string object.
struct Sas {
inner: Arc<Mutex<InnerSas>>,
account: Account,
@ -42,14 +44,26 @@ struct Sas {
}
impl Sas {
/// Get our own user id.
fn user_id(&self) -> &UserId {
self.account.user_id()
}
/// Get our own device id.
fn device_id(&self) -> &DeviceId {
self.account.device_id()
}
/// Start a new SAS auth flow with the given device.
///
/// # Arguments
///
/// * `account` - Our own account.
///
/// * `other_device` - The other device which we are going to verify.
///
/// Returns the new `Sas` object and a `StartEventContent` that needs to be
/// sent out through the server to the other device.
fn start(account: Account, other_device: Device) -> (Sas, StartEventContent) {
let (inner, content) = InnerSas::start(account.clone(), other_device.clone());
@ -62,6 +76,16 @@ impl Sas {
(sas, content)
}
/// Create a new Sas object from a m.key.verification.start request.
///
/// # Arguments
///
/// * `account` - Our own account.
///
/// * `other_device` - The other device which we are going to verify.
///
/// * `event` - The m.key.verification.start event that was sent to us by
/// the other side.
fn from_start_event(
account: Account,
other_device: Device,
@ -126,6 +150,7 @@ enum InnerSas {
Confirmed(SasState<Confirmed>),
MacReceived(SasState<MacReceived>),
Done(SasState<Done>),
Canceled(SasState<Canceled>),
}
impl InnerSas {
@ -140,11 +165,10 @@ impl InnerSas {
other_device: Device,
event: &ToDeviceEvent<StartEventContent>,
) -> InnerSas {
InnerSas::Started(SasState::<Started>::from_start_event(
account,
other_device,
event,
))
match SasState::<Started>::from_start_event(account, other_device, event) {
Ok(s) => InnerSas::Started(s),
Err(s) => InnerSas::Canceled(s),
}
}
fn accept(&self) -> Option<AcceptEventContent> {
@ -304,21 +328,31 @@ struct SasState<S: Clone> {
state: Arc<S>,
}
impl<S: Clone + std::fmt::Debug> std::fmt::Debug for SasState<S> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
f.debug_struct("SasState")
.field("ids", &self.ids)
.field("flow_id", &self.verification_flow_id)
.field("state", &self.state)
.finish()
}
}
/// The initial SAS state.
#[derive(Clone)]
#[derive(Clone, Debug)]
struct Created {
protocol_definitions: MSasV1ContentOptions,
}
/// The initial SAS state if the other side started the SAS verification.
#[derive(Clone)]
#[derive(Clone, Debug)]
struct Started {
protocol_definitions: MSasV1Content,
}
/// The SAS state we're going to be in after the other side accepted our
/// verification start event.
#[derive(Clone)]
#[derive(Clone, Debug)]
struct Accepted {
accepted_protocols: Arc<AcceptedProtocols>,
commitment: String,
@ -328,7 +362,7 @@ struct Accepted {
/// other participant.
///
/// From now on we can show the short auth string to the user.
#[derive(Clone)]
#[derive(Clone, Debug)]
struct KeyReceived {
we_started: bool,
accepted_protocols: Arc<AcceptedProtocols>,
@ -337,7 +371,7 @@ struct KeyReceived {
/// The SAS state we're going to be in after the user has confirmed that the
/// short auth string matches. We still need to receive a MAC event from the
/// other side.
#[derive(Clone)]
#[derive(Clone, Debug)]
struct Confirmed {
accepted_protocols: Arc<AcceptedProtocols>,
}
@ -345,7 +379,7 @@ struct Confirmed {
/// The SAS state we're going to be in after we receive a MAC event from the
/// other side. Our own user still needs to confirm that the short auth string
/// matches.
#[derive(Clone)]
#[derive(Clone, Debug)]
struct MacReceived {
we_started: bool,
verified_devices: Arc<Vec<Box<DeviceId>>>,
@ -356,12 +390,18 @@ struct MacReceived {
///
/// We can now mark the device in our verified devices lits as verified and sign
/// the master keys in the verified devices list.
#[derive(Clone)]
#[derive(Clone, Debug)]
struct Done {
verified_devices: Arc<Vec<Box<DeviceId>>>,
verified_master_keys: Arc<Vec<String>>,
}
#[derive(Clone, Debug)]
struct Canceled {
cancel_code: CancelCode,
reason: &'static str,
}
impl<S: Clone> SasState<S> {
/// Get our own user id.
pub fn user_id(&self) -> &UserId {
@ -462,16 +502,35 @@ impl SasState<Started> {
account: Account,
other_device: Device,
event: &ToDeviceEvent<StartEventContent>,
) -> SasState<Started> {
// TODO check if we support the suggested protocols and cancel if we
// don't
let content = if let StartEventContent::MSasV1(content) = &event.content {
content
} else {
panic!("Invalid sas version")
};
) -> Result<SasState<Started>, SasState<Canceled>> {
if let StartEventContent::MSasV1(content) = &event.content {
if !content
.key_agreement_protocols
.contains(&KeyAgreementProtocol::Curve25519HkdfSha256)
|| !content
.message_authentication_codes
.contains(&MessageAuthenticationCode::HkdfHmacSha256)
|| !content.hashes.contains(&HashAlgorithm::Sha256)
|| (!content
.short_authentication_string
.contains(&ShortAuthenticationString::Decimal)
&& !content
.short_authentication_string
.contains(&ShortAuthenticationString::Emoji))
{
Err(SasState {
inner: Arc::new(Mutex::new(OlmSas::new())),
SasState {
ids: SasIds {
account,
other_device,
},
verification_flow_id: Arc::new(content.transaction_id.clone()),
state: Arc::new(Canceled::new(CancelCode::UnknownMethod)),
})
} else {
Ok(SasState {
inner: Arc::new(Mutex::new(OlmSas::new())),
ids: SasIds {
@ -484,6 +543,23 @@ impl SasState<Started> {
state: Arc::new(Started {
protocol_definitions: content.clone(),
}),
})
}
} else {
Err(SasState {
inner: Arc::new(Mutex::new(OlmSas::new())),
ids: SasIds {
account,
other_device,
},
// TODO we can't get to the transaction id currently since it's
// behind the an enum.
verification_flow_id: Arc::new("".to_owned()),
state: Arc::new(Canceled::new(CancelCode::UnknownMethod)),
})
}
}
@ -772,6 +848,34 @@ impl SasState<Done> {
}
}
impl Canceled {
fn new(code: CancelCode) -> Canceled {
let reason = match code {
CancelCode::Accepted => {
"A m.key.verification.request was accepted by a different device."
}
CancelCode::InvalidMessage => "The received message was invalid.",
CancelCode::KeyMismatch => "The expected key did not match the verified one",
CancelCode::Timeout => "The verification process timed out.",
CancelCode::UnexpectedMessage => "The device received an unexpected message.",
CancelCode::UnknownMethod => {
"The device does not know how to handle the requested method."
}
CancelCode::UnknownTransaction => {
"The device does not know about the given transaction ID."
}
CancelCode::User => "The user cancelled the verification.",
CancelCode::UserMismatch => "The expected user did not match the verified user",
_ => unimplemented!(),
};
Canceled {
cancel_code: code,
reason,
}
}
}
#[cfg(test)]
mod test {
use std::convert::TryFrom;
@ -836,7 +940,7 @@ mod test {
let bob_sas = SasState::<Started>::from_start_event(bob.clone(), alice_device, &event);
(alice_sas, bob_sas)
(alice_sas, bob_sas.unwrap())
}
#[tokio::test]