Restore 'forbidden in restricted mode' errors

Author: edolstra

src/libexpr/eval.cc

@@ -3069,6 +3069,11 @@ SourcePath EvalState::findFile(const LookupPath & lookupPath, const std::string_
 
         auto res = (r / CanonPath(suffix)).resolveSymlinks();
         if (res.pathExists()) return res;
+
+        // Backward compatibility hack: throw an exception if access
+        // to this path is not allowed.
+        if (auto accessor = res.accessor.dynamic_pointer_cast<FilteringSourceAccessor>())
+            accessor->checkAccess(res.path);
     }
 
     if (hasPrefix(path, "nix/"))
@@ -3139,6 +3144,11 @@ std::optional<SourcePath> EvalState::resolveLookupPathPath(const LookupPath::Pat
         if (path.resolveSymlinks().pathExists())
             return finish(std::move(path));
         else {
+            // Backward compatibility hack: throw an exception if access
+            // to this path is not allowed.
+            if (auto accessor = path.accessor.dynamic_pointer_cast<FilteringSourceAccessor>())
+                accessor->checkAccess(path.path);
+
             logWarning({
                 .msg = HintFmt("Nix search path entry '%1%' does not exist, ignoring", value)
             });

tests/functional/restricted.sh

@@ -23,7 +23,7 @@ nix-instantiate --restrict-eval ./simple.nix -I src1=./simple.nix -I src2=./conf
 (! nix-instantiate --restrict-eval --eval -E 'builtins.readFile ./simple.nix')
 nix-instantiate --restrict-eval --eval -E 'builtins.readFile ./simple.nix' -I src=../..
 
-expectStderr 1 nix-instantiate --restrict-eval --eval -E 'let __nixPath = [ { prefix = "foo"; path = ./.; } ]; in builtins.readFile <foo/simple.nix>' #| grepQuiet "forbidden in restricted mode"
+expectStderr 1 nix-instantiate --restrict-eval --eval -E 'let __nixPath = [ { prefix = "foo"; path = ./.; } ]; in builtins.readFile <foo/simple.nix>' | grepQuiet "forbidden in restricted mode"
 nix-instantiate --restrict-eval --eval -E 'let __nixPath = [ { prefix = "foo"; path = ./.; } ]; in builtins.readFile <foo/simple.nix>' -I src=.
 
 p=$(nix eval --raw --expr "builtins.fetchurl file://${_NIX_TEST_SOURCE_DIR}/restricted.sh" --impure --restrict-eval --allowed-uris "file://${_NIX_TEST_SOURCE_DIR}")
@@ -53,9 +53,9 @@ mkdir -p $TEST_ROOT/tunnel.d $TEST_ROOT/foo2
 ln -sfn .. $TEST_ROOT/tunnel.d/tunnel
 echo foo > $TEST_ROOT/bar
 
-expectStderr 1 nix-instantiate --restrict-eval --eval -E "let __nixPath = [ { prefix = \"foo\"; path = $TEST_ROOT/tunnel.d; } ]; in builtins.readFile <foo/tunnel/bar>" -I $TEST_ROOT/tunnel.d #| grepQuiet "forbidden in restricted mode"
+expectStderr 1 nix-instantiate --restrict-eval --eval -E "let __nixPath = [ { prefix = \"foo\"; path = $TEST_ROOT/tunnel.d; } ]; in builtins.readFile <foo/tunnel/bar>" -I $TEST_ROOT/tunnel.d | grepQuiet "forbidden in restricted mode"
 
-expectStderr 1 nix-instantiate --restrict-eval --eval -E "let __nixPath = [ { prefix = \"foo\"; path = $TEST_ROOT/tunnel.d; } ]; in builtins.readDir <foo/tunnel/foo2>" -I $TEST_ROOT/tunnel.d #| grepQuiet "forbidden in restricted mode"
+expectStderr 1 nix-instantiate --restrict-eval --eval -E "let __nixPath = [ { prefix = \"foo\"; path = $TEST_ROOT/tunnel.d; } ]; in builtins.readDir <foo/tunnel/foo2>" -I $TEST_ROOT/tunnel.d | grepQuiet "forbidden in restricted mode"
 
 # Reading the parents of allowed paths should show only the ancestors of the allowed paths.
 [[ $(nix-instantiate --restrict-eval --eval -E "let __nixPath = [ { prefix = \"foo\"; path = $TEST_ROOT/tunnel.d; } ]; in builtins.readDir <foo/tunnel>" -I $TEST_ROOT/tunnel.d) == '{ "tunnel.d" = "directory"; }' ]]