impdev

1 files changed, 69 insertions, 0 deletions

diff --git a/lib/dispatch/tool/files/sandbox.rb b/lib/dispatch/tool/files/sandbox.rb
new file mode 100644
index 0000000..6ceccb1
--- /dev/null
+++ b/lib/dispatch/tool/files/sandbox.rb
@@ -0,0 +1,69 @@
+# frozen_string_literal: true
+
+module Dispatch
+  module Tool
+    module Files
+      module Sandbox
+        module_function
+
+        def resolve_path(path, worktree_path:)
+          worktree_real = File.realpath(worktree_path)
+
+          # Join the path against the worktree root
+          joined = File.expand_path(path, worktree_real)
+
+          # Check the expanded (logical) path first — catches ../traversal and absolute paths
+          unless joined.start_with?("#{worktree_real}/") || joined == worktree_real
+            raise SandboxError, "Path '#{path}' resolves outside the worktree sandbox"
+          end
+
+          # For existing paths, resolve symlinks and verify the real path
+          if File.exist?(joined)
+            real = File.realpath(joined)
+
+            unless real.start_with?("#{worktree_real}/") || real == worktree_real
+              raise SandboxError, "Path '#{path}' resolves outside the worktree sandbox (symlink escape)"
+            end
+
+            real
+          else
+            # For non-existent paths, resolve as much of the existing prefix as possible
+            # to catch symlinked directory components pointing outside the worktree
+            parts = joined.delete_prefix("#{worktree_real}/").split("/")
+            current = worktree_real
+
+            parts.each_with_index do |part, i|
+              candidate = File.join(current, part)
+
+              if File.symlink?(candidate)
+                real_target = File.realpath(candidate)
+
+                unless real_target.start_with?("#{worktree_real}/") || real_target == worktree_real
+                  raise SandboxError, "Path '#{path}' resolves outside the worktree sandbox (symlink escape)"
+                end
+
+                current = real_target
+              elsif File.exist?(candidate)
+                current = File.realpath(candidate)
+              else
+                # Remainder of the path doesn't exist on disk — that's fine, return the logical path
+                remaining = parts[(i + 1)..]
+
+                return remaining.empty? ? candidate : File.join(candidate, *remaining)
+              end
+            end
+
+            current
+          end
+        end
+
+        def within_worktree?(path, worktree_path:)
+          resolve_path(path, worktree_path:)
+          true
+        rescue SandboxError
+          false
+        end
+      end
+    end
+  end
+end