From 77e73d70a9b81a7bbd8e49be52612fc62a9f9502 Mon Sep 17 00:00:00 2001
From: Qrius <qrius@quirio.net>
Date: Tue, 6 May 2025 14:22:33 +0200
Subject: Disable unsafe code execution by default

---
 src/smp/__init__.py        | 9 +++++++++
 src/smp/builtins.py        | 4 ++++
 src/smp/macro_processor.py | 8 ++++++--
 3 files changed, 19 insertions(+), 2 deletions(-)

(limited to 'src/smp')

diff --git a/src/smp/__init__.py b/src/smp/__init__.py
index f7cb937..2cdf2fe 100644
--- a/src/smp/__init__.py
+++ b/src/smp/__init__.py
@@ -41,6 +41,13 @@ def main():
         action="store_true",
         help="Prefix builtins with smp_",
     )
+    parser.add_argument(
+        "-U",
+        "--unsafe",
+        default=False,
+        action="store_true",
+        help="Allow unsafe code execution",
+    )
     parser.add_argument(
         "file", nargs="?", default=None, help='Input file or "-" for stdin'
     )
@@ -50,6 +57,8 @@ def main():
     macro_processor_state = smp.macro_processor.MacroProcessorState()
     prefix = "smp_" if args.prefix_builtins else ""
     macro_processor = macro_processor_state.macro_processor(prefix=prefix)
+    if args.unsafe:
+        macro_processor.unsafe_code_execution = True
 
     for key, value in args.D.items():
         macro_processor.define_macro(key, value)
diff --git a/src/smp/builtins.py b/src/smp/builtins.py
index 36cc380..6beb224 100644
--- a/src/smp/builtins.py
+++ b/src/smp/builtins.py
@@ -113,11 +113,15 @@ def smp_builtin_include_verbatim(macro_processor, filename):
 
 
 def smp_builtin_shell(macro_processor, cmd_args):
+    if not macro_processor.unsafe_code_execution:
+        raise Exception("unsafe code execution now allowed!")
     cmd_args = macro_processor.process_input(cmd_args)
     return subprocess.check_output(cmd_args, shell=True).decode()
 
 
 def smp_builtin_eval(macro_processor, expression):
+    if not macro_processor.unsafe_code_execution:
+        raise Exception("unsafe code execution now allowed!")
     r = eval(
         expression,
         macro_processor.py_local_env_current,
diff --git a/src/smp/macro_processor.py b/src/smp/macro_processor.py
index a473db4..d5f4e8e 100644
--- a/src/smp/macro_processor.py
+++ b/src/smp/macro_processor.py
@@ -76,6 +76,8 @@ class MacroProcessor:
 
     expansion_stack: list[Any]
 
+    unsafe_code_execution: bool = False
+
     def __init__(self, prefix=""):
         self.macros = dict()
         self.macro_invocations = list()
@@ -140,7 +142,7 @@ class MacroProcessor:
         return self.macros.get(f"{sub_prefix}{macro_name}", default)
 
     def _define_metadata(self, macro_name, macro_value):
-        sub_prefix = (self._get_macro_builtin("metadata_prefix"))
+        sub_prefix = self._get_macro_builtin("metadata_prefix")
         self.define_macro(f"{sub_prefix}{macro_name}", macro_value)
 
     def log_warning(self, message):
@@ -351,7 +353,7 @@ class MacroProcessor:
                     i += 1
                     continue
 
-                if c == "%" and peek == "(":
+                if self.unsafe_code_execution and c == "%" and peek == "(":
                     state = ParserState.IN_CODE
                     i += 2
                     state_start = i
@@ -499,6 +501,8 @@ class MacroProcessor:
             elif state == ParserState.IN_CODE:
                 if c == ")" and peek == "%":
                     try:
+                        if not self.unsafe_code_execution:
+                            raise Exception("unsafe code execution now allowed!")
                         self._enter_frame("inline_code", file, linenr, input)
                         f = StringIO()
                         with redirect_stdout(f):
-- 
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