From d7619d6170ea6484bfc39944c4224aa20f5d4ba4 Mon Sep 17 00:00:00 2001
From: Matt Tressler <matthewtressler10@gmail.com>
Date: Mon, 3 Aug 2020 11:59:35 -0400
Subject: [PATCH] created linux_check_idt; plugin currently is not finding the
 module names for each entry in idt table

---
 .../framework/plugins/linux/check_idt.py      | 94 +++++++++++++++++++
 1 file changed, 94 insertions(+)
 create mode 100644 volatility/framework/plugins/linux/check_idt.py

diff --git a/volatility/framework/plugins/linux/check_idt.py b/volatility/framework/plugins/linux/check_idt.py
new file mode 100644
index 000000000..bc327bdab
--- /dev/null
+++ b/volatility/framework/plugins/linux/check_idt.py
@@ -0,0 +1,94 @@
+# This file is Copyright 2019 Volatility Foundation and licensed under the Volatility Software License 1.0
+# which is available at https://www.volatilityfoundation.org/license/vsl-v1.0
+#
+
+import logging
+from typing import List
+
+from volatility.framework import interfaces, renderers, constants, contexts, exceptions, symbols
+from volatility.framework.configuration import requirements
+from volatility.framework.renderers import format_hints
+from volatility.framework.symbols import linux
+from volatility.plugins.linux import lsmod
+
+vollog = logging.getLogger(__name__)
+
+
+class Check_idt(interfaces.plugins.PluginInterface):
+    """ Checks if the IDT has been altered """
+
+    @classmethod
+    def get_requirements(cls) -> List[interfaces.configuration.RequirementInterface]:
+        return [
+            requirements.TranslationLayerRequirement(name='primary',
+                                                     description='Memory layer for the kernel',
+                                                     architectures=["Intel32", "Intel64"]),
+
+            requirements.SymbolTableRequirement(name="vmlinux", description="Linux kernel symbols"),
+            
+            requirements.PluginRequirement(name='lsmod', plugin=lsmod.Lsmod, version=(1, 0, 0))
+        ]
+
+    def _generator(self):
+        vmlinux = contexts.Module(self.context, self.config['vmlinux'], self.config['primary'], 0)
+
+        modules = lsmod.Lsmod.list_modules(self.context, self.config['primary'], self.config['vmlinux'])
+
+        handlers = linux.LinuxUtilities.generate_kernel_handler_info(self.context, self.config['primary'], self.config['vmlinux'], modules)
+
+
+        is_32bit = not symbols.symbol_table_is_64bit(self.context, self.config["vmlinux"])
+
+        tblsz = 256
+
+        # hw handlers + system call
+        check_idxs = list(range(0, 20)) + [128]
+
+        if is_32bit:
+            if vmlinux.has_type("gate_struct"):
+                idt_type = "gate_struct"
+            else:
+                idt_type = "desc_struct"
+        else:
+            if vmlinux.has_type("gate_struct64"):
+                idt_type = "gate_struct64"
+            elif vmlinux.has_type("gate_struct"):
+                idt_type = "gate_struct"
+            else:
+                idt_type = "idt_desc"
+
+        # this is written as a list b/c there are supposdly kernels with per-CPU IDTs
+        # but I haven't found one yet... 
+        # ^ This is from vol2. Not sure if this should stay a list or if object_from_symbol
+        # would even give u a multi-element list
+        addrs = [vmlinux.object_from_symbol("idt_table")]
+
+        for tableaddr in addrs:
+            table = vmlinux.object(object_type='array', offset=tableaddr.vol.offset, subtype=vmlinux.get_type(idt_type), count=tblsz)
+
+            for i in check_idxs:
+                ent = table[i]
+
+                if not ent:
+                    continue
+
+                if hasattr(ent, "Address"):
+                    idt_addr = ent.Address
+                else:
+                    low = ent.offset_low
+                    middle = ent.offset_middle
+
+                    if hasattr(ent, "offset_high"):
+                        high = ent.offset_high
+                    else:
+                        high = 0
+
+                    idt_addr = (high << 32) | (middle << 16) | low
+
+                module_name, symbol_name = linux.LinuxUtilities.lookup_module_address(self.context, handlers, idt_addr)
+
+                yield(0, [format_hints.Hex(i), format_hints.Hex(idt_addr), module_name, symbol_name])
+        
+
+    def run(self):
+        return renderers.TreeGrid([("Index", format_hints.Hex), ("Address", format_hints.Hex), ("Module", str), ("Symbol", str)], self._generator())