openmls/group/public_group/staged_commit.rs
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use super::{super::errors::*, *};
use crate::{
framing::{mls_auth_content::AuthenticatedContent, mls_content::FramedContentBody, Sender},
group::{
mls_group::staged_commit::StagedCommitState, proposal_store::ProposalQueue, StagedCommit,
},
messages::{proposals::ProposalOrRef, Commit},
};
#[derive(Debug, Serialize, Deserialize)]
#[cfg_attr(any(test, feature = "test-utils"), derive(Clone, PartialEq))]
pub struct PublicStagedCommitState {
pub(super) staged_diff: StagedPublicGroupDiff,
pub(super) update_path_leaf_node: Option<LeafNode>,
}
impl PublicStagedCommitState {
pub fn new(
staged_diff: StagedPublicGroupDiff,
update_path_leaf_node: Option<LeafNode>,
) -> Self {
Self {
staged_diff,
update_path_leaf_node,
}
}
pub(crate) fn into_staged_diff(self) -> StagedPublicGroupDiff {
self.staged_diff
}
pub fn update_path_leaf_node(&self) -> Option<&LeafNode> {
self.update_path_leaf_node.as_ref()
}
pub fn staged_diff(&self) -> &StagedPublicGroupDiff {
&self.staged_diff
}
}
impl PublicGroup {
pub(crate) fn validate_commit<'a>(
&self,
mls_content: &'a AuthenticatedContent,
crypto: &impl OpenMlsCrypto,
) -> Result<(&'a Commit, ProposalQueue, LeafNodeIndex), StageCommitError> {
let ciphersuite = self.ciphersuite();
// Verify epoch
// https://validation.openmls.tech/#valn1201
if mls_content.epoch() != self.group_context().epoch() {
log::error!(
"Epoch mismatch. Got {:?}, expected {:?}",
mls_content.epoch(),
self.group_context().epoch()
);
return Err(StageCommitError::EpochMismatch);
}
// Extract Commit & Confirmation Tag from PublicMessage
let commit = match mls_content.content() {
FramedContentBody::Commit(commit) => commit,
_ => return Err(StageCommitError::WrongPlaintextContentType),
};
let sender = mls_content.sender();
if sender == &Sender::NewMemberCommit {
// External commit, there MUST be a path
// https://validation.openmls.tech/#valn0405
if commit.path.is_none() {
return Err(ExternalCommitValidationError::NoPath.into());
}
// ValSem244: External Commit, There MUST NOT be any referenced proposals.
// https://validation.openmls.tech/#valn0406
if commit
.proposals
.iter()
.any(|proposal| matches!(proposal, ProposalOrRef::Reference(_)))
{
return Err(ExternalCommitValidationError::ReferencedProposal.into());
}
let number_of_remove_proposals = commit
.proposals
.iter()
.filter(|prop| matches!(prop, ProposalOrRef::Proposal(Proposal::Remove(_))))
.count();
// https://validation.openmls.tech/#valn0402
if number_of_remove_proposals > 1 {
return Err(ExternalCommitValidationError::MultipleExternalInitProposals.into());
}
}
// Build a queue with all proposals from the Commit and check that we have all
// of the proposals by reference locally
// ValSem240: Commit must not cover inline self Remove proposal
let proposal_queue = ProposalQueue::from_committed_proposals(
ciphersuite,
crypto,
commit.proposals.as_slice().to_vec(),
self.proposal_store(),
sender,
)
.map_err(|e| {
log::error!("Error building the proposal queue for the commit ({e:?})");
match e {
FromCommittedProposalsError::LibraryError(e) => StageCommitError::LibraryError(e),
FromCommittedProposalsError::ProposalNotFound => StageCommitError::MissingProposal,
FromCommittedProposalsError::SelfRemoval => StageCommitError::AttemptedSelfRemoval,
}
})?;
// https://validation.openmls.tech/#valn1207
if let Some(update_path) = &commit.path {
self.validate_leaf_node(update_path.leaf_node())?;
}
// Validate the staged proposals. This implements https://validation.openmls.tech/#valn1204.
// This is done by doing the following checks:
// ValSem101
// ValSem102
// ValSem103
// ValSem104
self.validate_key_uniqueness(&proposal_queue, Some(commit))?;
// ValSem105
self.validate_add_proposals(&proposal_queue)?;
// ValSem106
// ValSem109
self.validate_capabilities(&proposal_queue)?;
// ValSem107
// ValSem108
self.validate_remove_proposals(&proposal_queue)?;
// ValSem113: All Proposals: The proposal type must be supported by all
// members of the group
self.validate_proposal_type_support(&proposal_queue)?;
// ValSem208
// ValSem209
self.validate_group_context_extensions_proposal(&proposal_queue)?;
// ValSem401
// ValSem402
// ValSem403
self.validate_pre_shared_key_proposals(&proposal_queue)?;
match sender {
Sender::Member(leaf_index) => {
// ValSem110
// ValSem111
// ValSem112
self.validate_update_proposals(&proposal_queue, *leaf_index)?;
self.validate_no_external_init_proposals(&proposal_queue)?;
}
Sender::External(_) => {
// A commit cannot be issued by a pre-configured sender.
return Err(StageCommitError::SenderTypeExternal);
}
Sender::NewMemberProposal => {
// A commit cannot be issued by a `NewMemberProposal` sender.
return Err(StageCommitError::SenderTypeNewMemberProposal);
}
Sender::NewMemberCommit => {
// ValSem240: External Commit, inline Proposals: There MUST be at least one ExternalInit proposal.
// ValSem241: External Commit, inline Proposals: There MUST be at most one ExternalInit proposal.
// ValSem242: External Commit must only cover inline proposal in allowlist (ExternalInit, Remove, PreSharedKey)
self.validate_external_commit(&proposal_queue)?;
}
}
// Now we can actually look at the public keys as they might have changed.
let sender_index = match sender {
Sender::Member(leaf_index) => *leaf_index,
Sender::NewMemberCommit => {
let inline_proposals = commit.proposals.iter().filter_map(|p| {
if let ProposalOrRef::Proposal(inline_proposal) = p {
Some(Some(inline_proposal))
} else {
None
}
});
self.leftmost_free_index(inline_proposals)?
}
_ => {
return Err(StageCommitError::SenderTypeExternal);
}
};
Ok((commit, proposal_queue, sender_index))
}
// Check that no external init proposal occurs. Needed only for regular commits.
// [valn0310](https://validation.openmls.tech/#valn0310)
fn validate_no_external_init_proposals(
&self,
proposal_queue: &ProposalQueue,
) -> Result<(), ProposalValidationError> {
for proposal in proposal_queue.queued_proposals() {
if matches!(
proposal.proposal().proposal_type(),
ProposalType::ExternalInit
) {
return Err(ProposalValidationError::ExternalInitProposalInRegularCommit);
}
}
Ok(())
}
/// Stages a commit message that was sent by another group member.
/// This function does the following:
/// - Applies the proposals covered by the commit to the tree
/// - Applies the (optional) update path to the tree
/// - Updates the [`GroupContext`]
/// - Decrypts and derives the path secrets
/// - Initializes the key schedule for epoch rollover
/// - Verifies the confirmation tag
///
/// Returns a [`StagedCommit`] that can be inspected and later merged into
/// the group state either with [`MlsGroup::merge_commit()`] or
/// [`PublicGroup::merge_diff()`] This function does the following checks:
/// - ValSem101
/// - ValSem102
/// - ValSem104
/// - ValSem105
/// - ValSem106
/// - ValSem107
/// - ValSem108
/// - ValSem110
/// - ValSem111
/// - ValSem112
/// - ValSem200
/// - ValSem201
/// - ValSem202: Path must be the right length
/// - ValSem203: Path secrets must decrypt correctly
/// - ValSem204: Public keys from Path must be verified and match the
/// private keys from the direct path
/// - ValSem205
/// - ValSem240
/// - ValSem241
/// - ValSem242
/// - ValSem244
///
/// Returns an error if the given commit was sent by the owner of this
/// group.
pub(crate) fn stage_commit(
&self,
mls_content: &AuthenticatedContent,
crypto: &impl OpenMlsCrypto,
) -> Result<StagedCommit, StageCommitError> {
let (commit, proposal_queue, sender_index) = self.validate_commit(mls_content, crypto)?;
let staged_diff = self.stage_diff(mls_content, &proposal_queue, sender_index, crypto)?;
let staged_state = PublicStagedCommitState {
staged_diff,
update_path_leaf_node: commit.path.as_ref().map(|p| p.leaf_node().clone()),
};
let staged_commit_state = StagedCommitState::PublicState(Box::new(staged_state));
Ok(StagedCommit::new(proposal_queue, staged_commit_state))
}
fn stage_diff(
&self,
mls_content: &AuthenticatedContent,
proposal_queue: &ProposalQueue,
sender_index: LeafNodeIndex,
crypto: &impl OpenMlsCrypto,
) -> Result<StagedPublicGroupDiff, StageCommitError> {
let ciphersuite = self.ciphersuite();
let mut diff = self.empty_diff();
let apply_proposals_values = diff.apply_proposals(proposal_queue, None)?;
let commit = match mls_content.content() {
FramedContentBody::Commit(commit) => commit,
_ => return Err(StageCommitError::WrongPlaintextContentType),
};
// Determine if Commit has a path
if let Some(update_path) = &commit.path {
// Update the public group
// ValSem202: Path must be the right length
diff.apply_received_update_path(crypto, ciphersuite, sender_index, update_path)?;
} else if apply_proposals_values.path_required {
// ValSem201
// https://validation.openmls.tech/#valn1206
return Err(StageCommitError::RequiredPathNotFound);
};
// Update group context
diff.update_group_context(crypto, apply_proposals_values.extensions.clone())?;
// Update the confirmed transcript hash before we compute the confirmation tag.
diff.update_confirmed_transcript_hash(crypto, mls_content)?;
let received_confirmation_tag = mls_content
.confirmation_tag()
.ok_or(StageCommitError::ConfirmationTagMissing)?;
// If we have private key material, derive the secrets for the next
// epoch and check the confirmation tag.
diff.update_interim_transcript_hash(
ciphersuite,
crypto,
received_confirmation_tag.clone(),
)?;
let staged_diff = diff.into_staged_diff(crypto, ciphersuite)?;
Ok(staged_diff)
}
/// Merges a [StagedCommit] into the public group state.
pub fn merge_commit<Storage: PublicStorageProvider>(
&mut self,
storage: &Storage,
staged_commit: StagedCommit,
) -> Result<(), MergeCommitError<Storage::Error>> {
match staged_commit.into_state() {
StagedCommitState::PublicState(staged_state) => {
self.merge_diff(staged_state.staged_diff);
}
StagedCommitState::GroupMember(_) => (),
}
self.proposal_store.empty();
storage
.clear_proposal_queue::<GroupId, ProposalRef>(self.group_id())
.map_err(MergeCommitError::StorageError)?;
self.store(storage).map_err(MergeCommitError::StorageError)
}
}