diff --git a/volatility3/framework/plugins/linux/envars.py b/volatility3/framework/plugins/linux/envars.py index aec3eeb14..bb6f52a7a 100644 --- a/volatility3/framework/plugins/linux/envars.py +++ b/volatility3/framework/plugins/linux/envars.py @@ -3,8 +3,9 @@ # import logging +from typing import Iterable, Tuple -from volatility3.framework import exceptions, renderers +from volatility3.framework import renderers, interfaces from volatility3.framework.configuration import requirements from volatility3.framework.interfaces import plugins from volatility3.framework.objects import utility @@ -17,7 +18,7 @@ class Envars(plugins.PluginInterface): """Lists processes with their environment variables""" _required_framework_version = (2, 13, 0) - _version = (1, 1, 0) + _version = (2, 0, 0) @classmethod def get_requirements(cls): @@ -39,76 +40,96 @@ class Envars(plugins.PluginInterface): ), ] + @staticmethod + def get_task_env_variables( + context: interfaces.context.ContextInterface, + task: interfaces.objects.ObjectInterface, + env_area_max_size: int = 8192, + ) -> Iterable[Tuple[str, str]]: + """Yields environment variables for a given task. + + Args: + context: The plugin's operational context. + task: The task object from which to extract environment variables. + + Yields: + Tuples of (key, value) representing each environment variable. + """ + + task_name = utility.array_to_string(task.comm) + task_pid = task.pid + env_start = task.mm.env_start + env_end = task.mm.env_end + env_area_size = env_end - env_start + if not (0 < env_area_size <= env_area_max_size): + vollog.debug( + f"Task {task_pid} {task_name} appears to have environment variables of size " + f"{env_area_size} bytes which fails the sanity checking, will not extract " + "any envars." + ) + return None + + # Get process layer to read envars from + proc_layer_name = task.add_process_layer() + if proc_layer_name is None: + return None + proc_layer = context.layers[proc_layer_name] + + # Ensure the entire buffer is readable to prevent relying on exception handling + if not proc_layer.is_valid(env_start, env_area_size): + # Not mapped / swapped out + vollog.debug( + f"Unable to read environment variables for {task_pid} {task_name} starting at " + f" virtual address 0x{env_start:x} for {env_area_size} bytes, will not " + "extract any envars." + ) + return None + + # Read the full task environment variable buffer. + envar_data = proc_layer.read(env_start, env_area_size) + + # Parse envar data, envars are null terminated, keys and values are separated by '=' + envar_data = envar_data.rstrip(b"\x00") + for envar_pair in envar_data.split(b"\x00"): + try: + env_key, env_value = envar_pair.decode().split("=", 1) + except ValueError: + # Some legitimate programs, like 'avahi-daemon', avoid reallocating the args + # and instead exploit the fact that the environment variables area is contiguous + # to the args. This allows them to include a longer process name in the listing, + # causing overwrites and incorrect results. In such cases, it's better to abort + # the current task rather than displaying misleading or incorrect output. + break + + yield env_key, env_value + def _generator(self, tasks): """Generates a listing of processes along with environment variables""" # walk the process list and return the envars for task in tasks: - pid = task.pid - - # get process name as string - name = utility.array_to_string(task.comm) - ppid = task.get_parent_pid() - - # kernel threads never have an mm as they do not have userland mappings - try: - mm = task.mm - except exceptions.InvalidAddressException: - # no mm so cannot get envars - vollog.debug( - f"Unable to access mm for task {pid} {name} it is likely a kernel thread, will not extract any envars." - ) - mm = None + if task.is_kernel_thread: continue - # if mm exists attempt to get envars - if mm: - # get process layer to read envars from - proc_layer_name = task.add_process_layer() - if proc_layer_name is None: - vollog.debug( - f"Unable to construct process layer for task {pid} {name}, will not extract any envars." - ) - continue - proc_layer = self.context.layers[proc_layer_name] + task_pid = task.pid + task_name = utility.array_to_string(task.comm) + task_ppid = task.get_parent_pid() - # get the size of the envars with sanity checking - envars_size = task.mm.env_end - task.mm.env_start - if not (0 < envars_size <= 8192): - vollog.debug( - f"Task {pid} {name} appears to have envars of size {envars_size} bytes which fails the sanity checking, will not extract any envars." - ) - continue - - # attempt to read all envars data - try: - envar_data = proc_layer.read(task.mm.env_start, envars_size) - except exceptions.InvalidAddressException: - vollog.debug( - f"Unable to read full envars for {pid} {name} starting at virtual offset {hex(task.mm.env_start)} for {envars_size} bytes, will not extract any envars." - ) - continue - - # parse envar data, envars are null terminated, keys and values are separated by '=' - envar_data = envar_data.rstrip(b"\x00") - for envar_pair in envar_data.split(b"\x00"): - try: - key, value = envar_pair.decode().split("=", 1) - except ValueError: - vollog.debug( - f"Unable to extract envars for {pid} {name} starting at virtual offset {hex(task.mm.env_start)}, they don't appear to be '=' separated" - ) - continue - yield (0, (pid, ppid, name, key, value)) + for env_key, env_value in self.get_task_env_variables(self.context, task): + yield (0, (task_pid, task_ppid, task_name, env_key, env_value)) def run(self): filter_func = pslist.PsList.create_pid_filter(self.config.get("pid", None)) - - return renderers.TreeGrid( - [("PID", int), ("PPID", int), ("COMM", str), ("KEY", str), ("VALUE", str)], - self._generator( - pslist.PsList.list_tasks( - self.context, self.config["kernel"], filter_func=filter_func - ) - ), + tasks = pslist.PsList.list_tasks( + self.context, self.config["kernel"], filter_func=filter_func ) + + headers = [ + ("PID", int), + ("PPID", int), + ("COMM", str), + ("KEY", str), + ("VALUE", str), + ] + + return renderers.TreeGrid(headers, self._generator(tasks))