1 files changed, 73 insertions, 0 deletions
diff --git a/src/Agent.Windows/Network/TaskNetworkPolicy.cs b/src/Agent.Windows/Network/TaskNetworkPolicy.cs
new file mode 100644
index 0000000..59b2602
--- /dev/null
+++ b/src/Agent.Windows/Network/TaskNetworkPolicy.cs
@@ -0,0 +1,73 @@
+using System.Security.Principal;
+using Agent.Windows.Recovery;
+using Agent.Windows.Security;
+
+namespace Agent.Windows.Network;
+
+public sealed class TaskNetworkPolicy : IDisposable
+{
+    private readonly WfpDynamicSession _session;
+    private readonly TaskResourceJournal _journal;
+    private readonly ISecurityAuditSink _audit;
+    private readonly Guid _entryId;
+    private readonly SecurityIdentifier _appContainerSid;
+    private readonly Guid _loopbackEntryId;
+    private readonly bool _loopbackAdded;
+    private bool _disposed;
+
+    private TaskNetworkPolicy(WfpDynamicSession session, TaskResourceJournal journal, ISecurityAuditSink audit, Guid entryId,
+        SecurityIdentifier appContainerSid, Guid loopbackEntryId, bool loopbackAdded)
+    {
+        _session = session; _journal = journal; _audit = audit; _entryId = entryId;
+        _appContainerSid = appContainerSid; _loopbackEntryId = loopbackEntryId; _loopbackAdded = loopbackAdded;
+    }
+
+    public static TaskNetworkPolicy Apply(TaskResourceJournal journal, SecurityIdentifier appContainerSid, IReadOnlyList<NetworkEndpoint> allowances, ISecurityAuditSink audit)
+    {
+        bool originallyExempt = LoopbackExemption.Contains(appContainerSid);
+        Guid loopbackEntryId = journal.Prepare("network.loopback_exemption", appContainerSid.Value,
+            new Dictionary<string, string> { ["originally_present"] = originallyExempt.ToString() });
+        bool loopbackAdded = false;
+        Guid entryId = journal.Prepare("wfp.dynamic", appContainerSid.Value, new Dictionary<string, string>
+        {
+            ["session"] = "dynamic", ["allowances"] = string.Join(',', allowances.Select(static item => $"{item.Address}:{item.Port}"))
+        });
+        WfpDynamicSession session = WfpDynamicSession.Open();
+        try
+        {
+            loopbackAdded = LoopbackExemption.Ensure(appContainerSid);
+            journal.MarkApplied(loopbackEntryId, new Dictionary<string, string> { ["added"] = loopbackAdded.ToString() });
+            IReadOnlyList<ulong> ids = session.ApplyDefaultBlock(appContainerSid, allowances);
+            journal.MarkApplied(entryId, new Dictionary<string, string> { ["filter_ids"] = string.Join(',', ids) });
+            audit.Write(new(DateTimeOffset.UtcNow, journal.TaskId, "wfp.apply", "applied", new Dictionary<string, string>
+            {
+                ["ipv4_ipv6_default_block"] = "true", ["filter_count"] = ids.Count.ToString(), ["session"] = "dynamic"
+            }));
+            audit.Write(new(DateTimeOffset.UtcNow, journal.TaskId, "network.loopback.apply", loopbackAdded ? "added" : "preserved",
+                new Dictionary<string, string> { ["app_container_sid"] = appContainerSid.Value }));
+            return new(session, journal, audit, entryId, appContainerSid, loopbackEntryId, loopbackAdded);
+        }
+        catch
+        {
+            session.Dispose();
+            journal.MarkCleaned(entryId);
+            if (loopbackAdded) LoopbackExemption.Remove(appContainerSid);
+            journal.MarkCleaned(loopbackEntryId);
+            throw;
+        }
+    }
+
+    public void Dispose()
+    {
+        if (_disposed) return;
+        _session.RemovePolicy();
+        _session.Dispose();
+        _journal.MarkCleaned(_entryId);
+        if (_loopbackAdded) LoopbackExemption.Remove(_appContainerSid);
+        _journal.MarkCleaned(_loopbackEntryId);
+        _audit.Write(new(DateTimeOffset.UtcNow, _journal.TaskId, "wfp.remove", "removed", new Dictionary<string, string> { ["residual_filters"] = "0" }));
+        _audit.Write(new(DateTimeOffset.UtcNow, _journal.TaskId, "network.loopback.remove", "removed",
+            new Dictionary<string, string> { ["residual_exemptions"] = LoopbackExemption.Contains(_appContainerSid) ? "preexisting" : "0" }));
+        _disposed = true;
+    }
+}