architex/lib/matrix_server/state_resolution/authorization.ex

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Elixir
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defmodule MatrixServer.StateResolution.Authorization do
import MatrixServer.StateResolution
import Ecto.Query
alias MatrixServer.{Repo, Event}
def authorized?(%Event{type: "m.room.create", prev_events: prev_events}, %{}),
do: prev_events == []
# Check rule: 5.2.1
def authorized?(%Event{type: "m.room.member", state_key: state_key}, %{
{"m.room.create", ""} => %Event{content: %{"creator" => creator}}
}),
do: state_key == creator
def authorized?(
%Event{type: "m.room.member", sender: sender, content: %{"membership" => "join"}},
state_set
) do
join_rule = get_join_rule(state_set)
membership = get_membership(sender, state_set)
# Check rules: 5.2.3, 5.2.4, 5.2.5
cond do
membership == "ban" -> false
join_rule == "invite" -> membership in ["invite", "join"]
join_rule == "public" -> true
true -> false
end
end
# TODO: rule 5.3.1
def authorized?(
%Event{
type: "m.room.member",
content: %{"membership" => "invite", "third_party_invite" => _}
},
_
),
do: false
def authorized?(
%Event{
type: "m.room.member",
sender: sender,
content: %{"membership" => "invite"},
state_key: state_key
},
state_set
) do
sender_membership = get_membership(sender, state_set)
target_membership = get_membership(state_key, state_set)
power_levels = get_power_levels(state_set)
# Check rules: 5.3.2, 5.3.3, 5.3.4
cond do
sender_membership != "join" -> false
target_membership in ["join", "ban"] -> false
has_power_level(sender, power_levels, :invite) -> true
true -> false
end
end
def authorized?(
%Event{
type: "m.room.member",
sender: sender,
content: %{"membership" => "leave"},
state_key: sender
},
state_set
) do
# Check rule: 5.4.1
get_membership(sender, state_set) in ["invite", "join"]
end
def authorized?(
%Event{
type: "m.room.member",
sender: sender,
content: %{"membership" => "leave"},
state_key: state_key
},
state_set
) do
sender_membership = get_membership(sender, state_set)
target_membership = get_membership(state_key, state_set)
power_levels = get_power_levels(state_set)
sender_pl = get_user_power_level(sender, power_levels)
target_pl = get_user_power_level(state_key, power_levels)
# Check rules: 5.4.2, 5.4.3, 5.4.4
cond do
sender_membership != "join" -> false
target_membership == "ban" and not has_power_level(sender, power_levels, :ban) -> false
has_power_level(sender, power_levels, :kick) and target_pl < sender_pl -> true
true -> false
end
end
def authorized?(
%Event{
type: "m.room.member",
sender: sender,
content: %{"membership" => "ban"},
state_key: state_key
},
state_set
) do
sender_membership = get_membership(sender, state_set)
power_levels = get_power_levels(state_set)
sender_pl = get_user_power_level(sender, power_levels)
target_pl = get_user_power_level(state_key, power_levels)
# Check rules: 5.5.1, 5.5.2
cond do
sender_membership != "join" -> false
has_power_level(sender, power_levels, :ban) and target_pl < sender_pl -> true
true -> false
end
end
# Check rule: 5.6
def authorized?(%Event{type: "m.room.member"}, _), do: false
def authorized?(%Event{sender: sender} = event, state_set) do
# Check rule: 6
get_membership(sender, state_set) == "join" and _authorized?(event, state_set)
end
defp _authorized?(%Event{type: "m.room.third_party_invite", sender: sender}, state_set) do
# Check rule: 7.1
has_power_level(sender, state_set, :invite)
end
defp _authorized?(%Event{state_key: state_key, sender: sender} = event, state_set) do
power_levels = get_power_levels(state_set)
# Check rules: 8, 9
cond do
not has_power_level(sender, power_levels, {:event, event}) -> false
String.starts_with?(state_key, "@") and state_key != sender -> false
true -> __authorized?(event, state_set)
end
end
defp __authorized?(
%Event{type: "m.room.power_levels", sender: sender, content: content},
state_set
) do
current_pls = get_power_levels(state_set)
new_pls = content
sender_pl = get_user_power_level(sender, new_pls)
# Check rules: 10.2, 10.3, 10.4, 10.5
cond do
not is_map_key(state_set, {"m.room.power_levels", ""}) -> true
not authorize_power_levels(sender, sender_pl, current_pls, new_pls) -> false
true -> true
end
end
# TODO: Rule 11
defp __authorized?(_, _), do: true
defp get_power_levels(state_set) do
case state_set[{"m.room.power_levels", ""}] do
%Event{content: content} -> content
nil -> nil
end
end
defp get_join_rule(state_set) do
case state_set[{"m.room.join_rules", ""}] do
%Event{content: %{"join_rule" => join_rule}} -> join_rule
nil -> nil
end
end
defp get_membership(user, state_set) do
case state_set[{"m.room.member", user}] do
%Event{content: %{"membership" => membership}} -> membership
nil -> nil
end
end
defp has_power_level(user, power_levels, action) do
user_pl = get_user_power_level(user, power_levels)
action_pl = get_action_power_level(action, power_levels)
user_pl >= action_pl
end
defp get_user_power_level(user, %{"users" => users}) when is_map_key(users, user),
do: users[user]
defp get_user_power_level(_, %{"users_default" => pl}), do: pl
defp get_user_power_level(_, _), do: 0
defp get_action_power_level(:invite, %{"invite" => pl}), do: pl
defp get_action_power_level(:invite, _), do: 50
defp get_action_power_level(:ban, %{"ban" => pl}), do: pl
defp get_action_power_level(:ban, _), do: 50
defp get_action_power_level(:redact, %{"redact" => pl}), do: pl
defp get_action_power_level(:redact, _), do: 50
defp get_action_power_level({:event, %Event{type: type}}, %{"events" => events})
when is_map_key(events, type),
do: events[type]
defp get_action_power_level({:event, event}, power_levels) do
if Event.is_state_event(event) do
case power_levels do
%{"state_default" => pl} -> pl
%{} -> 50
_ -> 0
end
else
case power_levels do
%{"events_default" => pl} -> pl
_ -> 0
end
end
end
defp authorize_power_levels(
user,
user_pl,
%{"events" => current_events, "users" => current_users} = current_pls,
%{"events" => new_events, "users" => new_users} = new_pls
) do
keys = ["users_default", "events_default", "state_default", "ban", "redact", "kick", "invite"]
valid_power_level_key_changes(Map.take(current_pls, keys), Map.take(new_pls, keys), user_pl) and
valid_power_level_key_changes(current_events, new_events, user_pl) and
valid_power_level_key_changes(current_users, new_users, user_pl) and
valid_power_level_users_changes(current_users, new_users, user, user_pl)
end
defp valid_power_level_key_changes(l1, l2, user_pl) do
set1 = MapSet.new(l1)
set2 = MapSet.new(l2)
MapSet.difference(
MapSet.union(set1, set2),
MapSet.intersection(set1, set2)
)
|> Enum.group_by(&elem(&1, 0), &elem(&1, 1))
|> Enum.all?(fn {_k, values} ->
Enum.all?(values, &(&1 <= user_pl))
end)
end
defp valid_power_level_users_changes(current_users, new_users, user, user_pl) do
set1 = MapSet.new(current_users)
set2 = MapSet.new(new_users)
MapSet.difference(
MapSet.union(set1, set2),
MapSet.intersection(set1, set2)
)
|> Enum.all?(fn
{_k, values} when length(values) != 2 -> true
{k, _} when k == user -> true
{_k, [old_value, _]} -> old_value != user_pl
end)
end
def authorized_by_auth_events?(%Event{auth_events: auth_event_ids} = event) do
# We assume the auth events are validated beforehand.
state_set =
Event
|> where([e], e.event_id in ^auth_event_ids)
|> Repo.all()
|> Enum.reduce(%{}, &update_state_set/2)
authorized?(event, state_set)
end
end