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// Copyright 2024 The Matrix.org Foundation C.I.C.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
use std::cmp::Ordering;
use ruma::{DeviceId, OwnedDeviceId, OwnedUserId, UserId};
use serde::{Deserialize, Serialize};
use vodozemac::Ed25519PublicKey;
use crate::types::DeviceKeys;
/// Information about the sender of a megolm session where we know the
/// cross-signing identity of the sender.
#[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
pub struct KnownSenderData {
/// The user ID of the user who established this session.
pub user_id: OwnedUserId,
/// The device ID of the device that send the session.
/// This is an `Option` for backwards compatibility, but we should always
/// populate it on creation.
pub device_id: Option<OwnedDeviceId>,
/// The cross-signing key of the user who established this session.
pub master_key: Box<Ed25519PublicKey>,
}
/// Information on the device and user that sent the megolm session data to us
///
/// Sessions start off in `UnknownDevice` state, and progress into `DeviceInfo`
/// state when we get the device info. Finally, if we can look up the sender
/// using the device info, the session can be moved into
/// `VerificationViolation`, `SenderUnverified`, or
/// `SenderVerified` state, depending on the verification status of the user.
/// If the user's verification state changes, the state may change accordingly.
#[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
#[serde(from = "SenderDataReader")]
pub enum SenderData {
/// We have not yet found the (signed) device info for the sending device,
/// or we did find a device but it does not own the session.
UnknownDevice {
/// Was this session created before we started collecting trust
/// information about sessions? If so, we may choose to display its
/// messages even though trust info is missing.
legacy_session: bool,
/// If true, we found the device but it was not the owner of the
/// session. If false, we could not find the device.
#[serde(skip_serializing_if = "std::ops::Not::not")]
#[serde(default)]
owner_check_failed: bool,
},
/// We have the signed device info for the sending device, but not yet the
/// cross-signing key that it was signed with.
DeviceInfo {
/// Information about the device that sent the to-device message
/// creating this session.
device_keys: DeviceKeys,
/// Was this session created before we started collecting trust
/// information about sessions? If so, we may choose to display its
/// messages even though trust info is missing.
legacy_session: bool,
},
/// We have found proof that this user, with this cross-signing key, sent
/// the to-device message that established this session, but we have not yet
/// verified the cross-signing key, and we had verified a previous
/// cross-signing key for this user.
VerificationViolation(KnownSenderData),
/// We have found proof that this user, with this cross-signing key, sent
/// the to-device message that established this session, but we have not yet
/// verified the cross-signing key.
SenderUnverified(KnownSenderData),
/// We have found proof that this user, with this cross-signing key, sent
/// the to-device message that established this session, and we have
/// verified the cross-signing key.
SenderVerified(KnownSenderData),
}
impl SenderData {
/// Create a [`SenderData`] which contains no device info.
pub fn unknown() -> Self {
Self::UnknownDevice { legacy_session: false, owner_check_failed: false }
}
/// Create a [`SenderData`] which contains device info.
pub fn device_info(device_keys: DeviceKeys) -> Self {
Self::DeviceInfo { device_keys, legacy_session: false }
}
/// Create a [`SenderData`] with a known but unverified sender, where the
/// sender was previously verified.
pub fn sender_verification_violation(
user_id: &UserId,
device_id: &DeviceId,
master_key: Ed25519PublicKey,
) -> Self {
Self::VerificationViolation(KnownSenderData {
user_id: user_id.to_owned(),
device_id: Some(device_id.to_owned()),
master_key: Box::new(master_key),
})
}
/// Create a [`SenderData`] with a known but unverified sender.
pub fn sender_unverified(
user_id: &UserId,
device_id: &DeviceId,
master_key: Ed25519PublicKey,
) -> Self {
Self::SenderUnverified(KnownSenderData {
user_id: user_id.to_owned(),
device_id: Some(device_id.to_owned()),
master_key: Box::new(master_key),
})
}
/// Create a [`SenderData`] with a verified sender.
pub fn sender_verified(
user_id: &UserId,
device_id: &DeviceId,
master_key: Ed25519PublicKey,
) -> Self {
Self::SenderVerified(KnownSenderData {
user_id: user_id.to_owned(),
device_id: Some(device_id.to_owned()),
master_key: Box::new(master_key),
})
}
/// Create a [`SenderData`] which has the legacy flag set. Caution: messages
/// within sessions with this flag will be displayed in some contexts,
/// even when we are unable to verify the sender.
///
/// The returned struct contains no device info.
pub fn legacy() -> Self {
Self::UnknownDevice { legacy_session: true, owner_check_failed: false }
}
/// Returns `Greater` if this `SenderData` represents a greater level of
/// trust than the supplied one, `Equal` if they have the same level, and
/// `Less` if the supplied one has a greater level of trust.
///
/// So calling this method on a `SenderKnown` or `DeviceInfo` `SenderData`
/// would return `Greater` if passed an `UnknownDevice` as its
/// argument, and a `SenderKnown` with `master_key_verified == true`
/// would return `Greater` if passed a `SenderKnown` with
/// `master_key_verified == false`.
pub(crate) fn compare_trust_level(&self, other: &Self) -> Ordering {
self.trust_number().cmp(&other.trust_number())
}
/// Internal function to give a numeric value of how much trust this
/// `SenderData` represents. Used to make the implementation of
/// compare_trust_level simpler.
fn trust_number(&self) -> u8 {
match self {
SenderData::UnknownDevice { .. } => 0,
SenderData::DeviceInfo { .. } => 1,
SenderData::VerificationViolation(..) => 2,
SenderData::SenderUnverified(..) => 3,
SenderData::SenderVerified(..) => 4,
}
}
/// Return our type as a [`SenderDataType`].
pub fn to_type(&self) -> SenderDataType {
match self {
Self::UnknownDevice { .. } => SenderDataType::UnknownDevice,
Self::DeviceInfo { .. } => SenderDataType::DeviceInfo,
Self::VerificationViolation { .. } => SenderDataType::VerificationViolation,
Self::SenderUnverified { .. } => SenderDataType::SenderUnverified,
Self::SenderVerified { .. } => SenderDataType::SenderVerified,
}
}
}
/// Used when deserialising and the sender_data property is missing.
/// If we are deserialising an InboundGroupSession session with missing
/// sender_data, this must be a legacy session (i.e. it was created before we
/// started tracking sender data). We set its legacy flag to true, so we can
/// populate it with trust information if it is available later.
impl Default for SenderData {
fn default() -> Self {
Self::legacy()
}
}
/// Deserialisation type, to handle conversion from older formats
#[derive(Deserialize)]
enum SenderDataReader {
UnknownDevice {
legacy_session: bool,
#[serde(default)]
owner_check_failed: bool,
},
DeviceInfo {
device_keys: DeviceKeys,
legacy_session: bool,
},
VerificationViolation(KnownSenderData),
SenderUnverified(KnownSenderData),
SenderVerified(KnownSenderData),
// If we read this older variant, it gets changed to SenderUnverified or
// SenderVerified, depending on the master_key_verified flag.
SenderKnown {
user_id: OwnedUserId,
device_id: Option<OwnedDeviceId>,
master_key: Box<Ed25519PublicKey>,
master_key_verified: bool,
},
}
impl From<SenderDataReader> for SenderData {
fn from(data: SenderDataReader) -> Self {
match data {
SenderDataReader::UnknownDevice { legacy_session, owner_check_failed } => {
Self::UnknownDevice { legacy_session, owner_check_failed }
}
SenderDataReader::DeviceInfo { device_keys, legacy_session } => {
Self::DeviceInfo { device_keys, legacy_session }
}
SenderDataReader::VerificationViolation(data) => Self::VerificationViolation(data),
SenderDataReader::SenderUnverified(data) => Self::SenderUnverified(data),
SenderDataReader::SenderVerified(data) => Self::SenderVerified(data),
SenderDataReader::SenderKnown {
user_id,
device_id,
master_key,
master_key_verified,
} => {
let known_sender_data = KnownSenderData { user_id, device_id, master_key };
if master_key_verified {
Self::SenderVerified(known_sender_data)
} else {
Self::SenderUnverified(known_sender_data)
}
}
}
}
}
/// Used when serializing [`crate::olm::group_sessions::InboundGroupSession`]s.
/// We want just the type of the session's [`SenderData`] to be queryable, so we
/// store the type as a separate column/property in the database.
#[derive(Clone, Copy, Debug, PartialEq, Deserialize, Serialize)]
pub enum SenderDataType {
/// The [`SenderData`] is of type `UnknownDevice`.
UnknownDevice = 1,
/// The [`SenderData`] is of type `DeviceInfo`.
DeviceInfo = 2,
/// The [`SenderData`] is of type `VerificationViolation`.
VerificationViolation = 3,
/// The [`SenderData`] is of type `SenderUnverified`.
SenderUnverified = 4,
/// The [`SenderData`] is of type `SenderVerified`.
SenderVerified = 5,
}
#[cfg(test)]
mod tests {
use std::{cmp::Ordering, collections::BTreeMap};
use assert_matches2::assert_let;
use ruma::{device_id, owned_device_id, owned_user_id, user_id};
use vodozemac::Ed25519PublicKey;
use super::SenderData;
use crate::types::{DeviceKeys, Signatures};
#[test]
fn serializing_unknown_device_correctly_preserves_owner_check_failed_if_true() {
// Given an unknown device SenderData with failed owner check
let start = SenderData::UnknownDevice { legacy_session: false, owner_check_failed: true };
// When we round-trip it to JSON and back
let json = serde_json::to_string(&start).unwrap();
let end: SenderData = serde_json::from_str(&json).unwrap();
// Then the failed owner check flag is preserved
assert_let!(SenderData::UnknownDevice { owner_check_failed, .. } = &end);
assert!(owner_check_failed);
// And for good measure, everything is preserved
assert_eq!(start, end);
}
#[test]
fn serializing_unknown_device_without_failed_owner_check_excludes_it() {
// Given an unknown device SenderData with owner_check_failed==false
let start = SenderData::UnknownDevice { legacy_session: false, owner_check_failed: false };
// When we write it to JSON
let json = serde_json::to_string(&start).unwrap();
// Then the JSON does not mention `owner_check_failed`
assert!(!json.contains("owner_check_failed"), "JSON contains 'owner_check_failed'!");
// And for good measure, it round-trips fully
let end: SenderData = serde_json::from_str(&json).unwrap();
assert_eq!(start, end);
}
#[test]
fn deserializing_unknown_device_with_extra_retry_info_ignores_it() {
// Previously, SenderData contained `retry_details` but it is no longer needed -
// just check that we are able to deserialize even if it is present.
let json = r#"
{
"UnknownDevice":{
"retry_details":{
"retry_count":3,
"next_retry_time_ms":10000
},
"legacy_session":false
}
}
"#;
let end: SenderData = serde_json::from_str(json).expect("Failed to parse!");
assert_let!(SenderData::UnknownDevice { .. } = end);
}
#[test]
fn deserializing_senderknown_without_device_id_defaults_to_none() {
let json = r#"
{
"SenderKnown":{
"user_id":"@u:s.co",
"master_key":[
150,140,249,139,141,29,63,230,179,14,213,175,176,61,11,255,
26,103,10,51,100,154,183,47,181,117,87,204,33,215,241,92
],
"master_key_verified":true
}
}
"#;
let end: SenderData = serde_json::from_str(json).expect("Failed to parse!");
assert_let!(SenderData::SenderVerified { .. } = end);
}
#[test]
fn equal_sessions_have_same_trust_level() {
let unknown = SenderData::unknown();
let device_keys = SenderData::device_info(DeviceKeys::new(
owned_user_id!("@u:s.co"),
owned_device_id!("DEV"),
Vec::new(),
BTreeMap::new(),
Signatures::new(),
));
let master_key =
Ed25519PublicKey::from_base64("2/5LWJMow5zhJqakV88SIc7q/1pa8fmkfgAzx72w9G4").unwrap();
let sender_unverified =
SenderData::sender_unverified(user_id!("@u:s.co"), device_id!("DEV"), master_key);
let sender_verified =
SenderData::sender_verified(user_id!("@u:s.co"), device_id!("DEV"), master_key);
assert_eq!(unknown.compare_trust_level(&unknown), Ordering::Equal);
assert_eq!(device_keys.compare_trust_level(&device_keys), Ordering::Equal);
assert_eq!(sender_unverified.compare_trust_level(&sender_unverified), Ordering::Equal);
assert_eq!(sender_verified.compare_trust_level(&sender_verified), Ordering::Equal);
}
#[test]
fn more_trust_data_makes_you_more_trusted() {
let unknown = SenderData::unknown();
let device_keys = SenderData::device_info(DeviceKeys::new(
owned_user_id!("@u:s.co"),
owned_device_id!("DEV"),
Vec::new(),
BTreeMap::new(),
Signatures::new(),
));
let master_key =
Ed25519PublicKey::from_base64("2/5LWJMow5zhJqakV88SIc7q/1pa8fmkfgAzx72w9G4").unwrap();
let sender_verification_violation = SenderData::sender_verification_violation(
user_id!("@u:s.co"),
device_id!("DEV"),
master_key,
);
let sender_unverified =
SenderData::sender_unverified(user_id!("@u:s.co"), device_id!("DEV"), master_key);
let sender_verified =
SenderData::sender_verified(user_id!("@u:s.co"), device_id!("DEV"), master_key);
assert_eq!(unknown.compare_trust_level(&device_keys), Ordering::Less);
assert_eq!(unknown.compare_trust_level(&sender_verification_violation), Ordering::Less);
assert_eq!(unknown.compare_trust_level(&sender_unverified), Ordering::Less);
assert_eq!(unknown.compare_trust_level(&sender_verified), Ordering::Less);
assert_eq!(device_keys.compare_trust_level(&unknown), Ordering::Greater);
assert_eq!(sender_verification_violation.compare_trust_level(&unknown), Ordering::Greater);
assert_eq!(sender_unverified.compare_trust_level(&unknown), Ordering::Greater);
assert_eq!(sender_verified.compare_trust_level(&unknown), Ordering::Greater);
assert_eq!(device_keys.compare_trust_level(&sender_unverified), Ordering::Less);
assert_eq!(device_keys.compare_trust_level(&sender_verified), Ordering::Less);
assert_eq!(
sender_verification_violation.compare_trust_level(&device_keys),
Ordering::Greater
);
assert_eq!(sender_unverified.compare_trust_level(&device_keys), Ordering::Greater);
assert_eq!(sender_verified.compare_trust_level(&device_keys), Ordering::Greater);
assert_eq!(
sender_verification_violation.compare_trust_level(&sender_verified),
Ordering::Less
);
assert_eq!(
sender_verification_violation.compare_trust_level(&sender_unverified),
Ordering::Less
);
assert_eq!(sender_unverified.compare_trust_level(&sender_verified), Ordering::Less);
assert_eq!(sender_verified.compare_trust_level(&sender_unverified), Ordering::Greater);
}
}