Make parsing more strict

tools/inject.py

@@ -33,6 +33,7 @@
 # 16-Mar-2018 Howard McLauchlan Created this.
 
 import argparse
+import re
 from bcc import BPF
 
 
@@ -350,6 +351,7 @@ def _parse_frames(self):
  frames = []
  cur_frame = []
  i = 0
+ last_frame_added = 0
 
  while i < len(data):
  # improper input
@@ -360,6 +362,10 @@ def _parse_frames(self):
  count -= c == ')'
  if not count:
  if c == '\0' or (c == '=' and data[i + 1] == '>'):
+ # This block is closing a chunk. This means cur_frame must
+ # have something in it.
+ if not cur_frame:
+ raise Exception("Cannot parse spec, missing parens")
  if len(cur_frame) == 2:
  frame = tuple(cur_frame)
  elif cur_frame[0][0] == '(':
@@ -373,7 +379,12 @@ def _parse_frames(self):
  elif c == ')':
  cur_frame.append(data[start:i + 1].strip())
  start = i + 1
+ last_frame_added = start
  i += 1
+
+ # We only permit spaces after the last frame
+ if self.spec[last_frame_added:].strip():
+ raise Exception("Invalid characters found after last frame");
  # improper input
  if count:
  raise Exception("Check your parentheses")
@@ -389,7 +400,9 @@ def _parse_spec(self):
  func, pred = f[0], f[1]
 
  if not self._validate_predicate(pred):
- raise Exception
+ raise Exception("Invalid predicate")
+ if not self._validate_identifier(func):
+ raise Exception("Invalid function identifier")
  tup = (pred, absolute_order)
 
  if func not in self.map:
@@ -405,6 +418,16 @@ def _parse_spec(self):
 
  self.length = absolute_order
 
+ def _validate_identifier(self, func):
+ # We've already established paren balancing. We will only look for
+ # identifier validity here.
+ paren_index = func.find("(")
+ potential_id = func[:paren_index]
+ pattern = '[_a-zA-z][_a-zA-Z0-9]*$'
+ if re.match(pattern, potential_id):
+ return True
+ return False
+
  def _validate_predicate(self, pred):
 
  if len(pred) > 0 and pred[0] == "(":