tools: add headerparser as a tool to assist in writing system call descriptions

The tool can be found inside tools/syz-headerparser. Details on how to use
headerparser can be found inside docs/headerparser_usage.md.

1 files changed, 250 insertions, 0 deletions

diff --git a/tools/syz-headerparser/headerlib/struct_walker.py b/tools/syz-headerparser/headerlib/struct_walker.py
new file mode 100644
index 000000000..94cc89895
--- /dev/null
+++ b/tools/syz-headerparser/headerlib/struct_walker.py
@@ -0,0 +1,250 @@
+# Copyright 2017 syzkaller project authors. All rights reserved.
+# Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+'''
+This module provides classes which implement AST traversal in order to extract
+items belonging to a struct.
+'''
+
+import collections
+import logging
+
+from pycparser import c_ast
+from header_preprocessor import HeaderFilePreprocessor
+
+
+class StructWalkerException(Exception):
+    pass
+
+
+class StructWalker(c_ast.NodeVisitor):
+    '''
+    Given an ast obtained by parsing a header file, return a hierarchy
+    dictionary. The ast is expected to be of type pycparser.c_ast.FileAST.
+
+    Usage :
+
+    >>> import tempfile
+    >>> t = tempfile.NamedTemporaryFile()
+    >>> contents = """
+    ... #define STRUCT_SIZE 1337
+    ... struct ARRAY_OF_POINTERS_CONTAINER {
+    ... 	unsigned int *ptr[10];
+    ... 	int **n;
+    ... };
+    ... struct ARRAY_CONTAINER {
+    ... 	  int g[10];
+    ... 		  int h[20][30];
+    ... };
+    ... struct REGULAR_STRUCT {
+    ... 	int x;
+    ... 	char *y;
+    ... 	void *ptr;
+    ... };
+    ... struct STRUCT_WITH_STRUCT_PTR {
+    ... 	struct REGULAR_STRUCT *struct_ptr;
+    ... 	int z;
+    ... };
+    ... struct STRUCT_WITH_STRUCT_INST {
+    ... 	struct REGULAR_STRUCT regular_struct_inst;
+    ... 	int a;
+    ... };
+    ... struct STRUCT_WITH_STRUCT_ARRAY {
+    ... 	struct REGULAR_STRUCT regular_struct_array[100];
+    ... 	int b;
+    ... };
+    ... struct STRUCT_WITH_ANONYMOUS_STRUCT {
+    ... 	struct {
+    ... 		int g;
+    ... 		int h;
+    ... 		int i;
+    ... 	} anonymous_struct;
+    ... };
+    ... struct STRUCT_WITH_ANONYMOUS_UNION {
+    ... 	union {
+    ... 		int t;
+    ... 		char r[100];
+    ... 	} anonymous_union;
+    ... };
+    ... struct STRUCT_WITH_STRUCT_ARRAY_SIZE_MACRO {
+    ... 	struct REGULAR_STRUCT regular_struct_array[STRUCT_SIZE];
+    ... };
+    ... struct STRUCT_WITH_2D_ARRAY_INST {
+    ... 	struct REGULAR_STRUCT regular_struct_array_2D[10][10];
+    ... };
+    ... struct NESTED_ANONYMOUS_STRUCT {
+    ... 	struct {
+    ... 		int x;
+    ... 		struct {
+    ... 			int y;
+    ... 			int z;
+    ... 		} level_2;
+    ... 	} level_1;
+    ... };
+    ... """
+	>>> t.write(contents) ; t.flush()
+    >>> struct_walker = StructWalker(filenames=[t.name])
+    >>> local_hierarchy = struct_walker.generate_local_hierarchy()
+    >>> for k in local_hierarchy:
+    ...     print k
+    ...     print local_hierarchy[k]
+    ARRAY_OF_POINTERS_CONTAINER
+    [('unsigned int*[10]', 'ptr'), ('int**', 'n')]
+    STRUCT_WITH_STRUCT_ARRAY_SIZE_MACRO
+    [('struct REGULAR_STRUCT[1337]', 'regular_struct_array')]
+    STRUCT_WITH_2D_ARRAY_INST
+    [('struct REGULAR_STRUCT[10][10]', 'regular_struct_array_2D')]
+    STRUCT_WITH_STRUCT_ARRAY
+    [('struct REGULAR_STRUCT[100]', 'regular_struct_array'), ('int', 'b')]
+    NESTED_ANONYMOUS_STRUCT
+    [('int', 'level_1.x'), ('int', 'level_1.level_2.y'), ('int', 'level_1.level_2.z')]
+    STRUCT_WITH_ANONYMOUS_STRUCT
+    [('int', 'anonymous_struct.g'), ('int', 'anonymous_struct.h'), ('int', 'anonymous_struct.i')]
+    STRUCT_WITH_ANONYMOUS_UNION
+    [('int', 'anonymous_union.t'), ('char[100]', 'anonymous_union.r')]
+    STRUCT_WITH_STRUCT_INST
+    [('struct REGULAR_STRUCT', 'regular_struct_inst'), ('int', 'a')]
+    ARRAY_CONTAINER
+    [('int[10]', 'g'), ('int[20][30]', 'h')]
+    REGULAR_STRUCT
+    [('int', 'x'), ('char*', 'y'), ('void*', 'ptr')]
+    STRUCT_WITH_STRUCT_PTR
+    [('struct REGULAR_STRUCT*', 'struct_ptr'), ('int', 'z')]
+    '''
+
+    def __init__(self, ast=None, filenames=[], include_lines='', loglvl=logging.INFO):
+        super(StructWalker, self).__init__()
+        self.ast = ast
+        self.filenames = filenames
+
+        if not filenames and not ast:
+            raise StructWalkerException('Specify either "filename" or "ast" to create'
+                                        'StructParser object')
+
+        if not self.ast:
+            self.ast = HeaderFilePreprocessor(self.filenames, include_lines=include_lines,
+                                              loglvl=loglvl).get_ast()
+
+        self.include_lines = include_lines
+        self.local_structs_hierarchy = {}
+        self._setuplogging(loglvl)
+
+    def _setuplogging(self, loglvl):
+        self.logger = logging.getLogger(self.__class__.__name__)
+        formatter = logging.Formatter('DEBUG:%(name)s:%(message)s')
+        sh = logging.StreamHandler()
+        sh.setFormatter(formatter)
+        sh.setLevel(loglvl)
+        self.logger.addHandler(sh)
+        self.logger.setLevel(loglvl)
+
+    def _format_item(self, processed_item):
+        fmt_type = processed_item['type']
+        fmt_type = ' '.join(fmt_type)
+
+        self.logger.debug('_format_item : %s', processed_item)
+
+        if 'is_ptr' in processed_item and 'is_fnptr' not in processed_item:
+            fmt_type = '%s%s' % (fmt_type, '*' * processed_item['is_ptr'])
+
+        if 'is_array' in processed_item and 'array_size' in processed_item:
+            size_str = str(processed_item['array_size']).replace(', ', '][')
+            fmt_type = '%s%s' % (fmt_type, size_str)
+
+        fmt_identifier = processed_item['identifier']
+
+        return [(fmt_type, fmt_identifier)]
+
+    def _recursive_process_item(self, item_ast, processed_item, parent):
+        self.logger.debug('--- _recursive_process_item : %s', type(item_ast))
+        if isinstance(item_ast, c_ast.Decl):
+            processed_item['identifier'] = item_ast.name
+            return self._recursive_process_item(item_ast.type, processed_item, item_ast)
+
+        elif isinstance(item_ast, c_ast.TypeDecl):
+            return self._recursive_process_item(item_ast.type, processed_item, item_ast)
+
+        elif isinstance(item_ast, c_ast.IdentifierType):
+            if len(item_ast.names) > 0:
+                processed_item['type'] = item_ast.names
+                return self._format_item(processed_item)
+
+        elif (isinstance(item_ast, c_ast.Struct) or
+              isinstance(item_ast, c_ast.Union)):
+            if not item_ast.name:
+                nodename, _items_list = self._traverse_ast(item_ast, toplevel=False)
+                try:
+                    items_list = [(i[0], '%s.%s' % (parent.declname, i[1])) for i in _items_list]
+                except AttributeError as e:
+                    self.logger.info('-- Encountered anonymous_struct/anonymous_union with no name')
+                    raise StructWalkerException('Encountered anonymous_struct/anonymous_union with no name')
+
+                return items_list
+            else:
+                processed_item['type'] = ['struct %s' % (item_ast.name)]
+                return self._format_item(processed_item)
+
+        elif isinstance(item_ast, c_ast.PtrDecl):
+            if 'is_ptr' not in processed_item:
+                processed_item['is_ptr'] = 0
+            processed_item['is_ptr'] = processed_item['is_ptr'] + 1
+            return self._recursive_process_item(item_ast.type, processed_item, item_ast)
+
+        elif isinstance(item_ast, c_ast.ArrayDecl):
+            processed_item['is_array'] = True
+            if 'array_size' not in processed_item:
+                processed_item['array_size'] = []
+            processed_item['array_size'].append(int(item_ast.dim.value))
+            return self._recursive_process_item(item_ast.type, processed_item, item_ast)
+
+        elif isinstance(item_ast, c_ast.Enum):
+            processed_item['type'] = ['enum %s' % (item_ast.name)]
+            return self._format_item(processed_item)
+
+        elif isinstance(item_ast, c_ast.FuncDecl):
+            processed_item['is_fnptr'] = True
+            processed_item['type'] = ['void (*)()']
+            return self._format_item(processed_item)
+
+    def _traverse_ast(self, node, toplevel=True):
+        items_list = []
+
+        # Argument structs are used as types, hence anonymous top-level
+        # structs are ignored.
+        if toplevel and not node.name:
+            return None
+
+        if not node.children():
+            return None
+
+        self.logger.debug('>>> Struct name = %s, coord: %s', node.name, node.coord)
+        for child in node.children():
+            item = self._recursive_process_item(child[1], {}, None)
+            items_list.extend(item)
+
+        self.logger.debug('_traverse_ast returns: %s', str((node.name, items_list)))
+        return (node.name, items_list)
+
+    def visit_Struct(self, node, *a):
+        if node.name in self.local_structs_hierarchy:
+            self.logger.info('Encountered %s again. Ignoring.', repr(node.name))
+            return
+
+        try:
+            desc = self._traverse_ast(node)
+        except StructWalkerException as e:
+            self.logger.info('-- Exception raised by StructWalkerException in %s,'
+                             'inspect manually.',
+                             repr(node.name))
+            self.logger.info(str(e))
+            return
+
+        if not desc:
+            return
+
+        struct_name, struct_items = desc
+        self.local_structs_hierarchy[struct_name] = struct_items
+
+    def generate_local_hierarchy(self):
+        self.visit(self.ast)
+        return self.local_structs_hierarchy