more stuff

2026-09-19 21:57:06 +02:00
parent 1e9a1ebf4d
commit 831308b2ad
61 changed files with 777 additions and 837 deletions
@@ -0,0 +1,108 @@
+#!/usr/bin/env python3
+# Small script to print all options available inside a built kernel.
+# fmt: off
+import sys
+
+from elftools.elf.elffile import ELFFile
+
+SIZEOF_PTR = 8
+SIZEOF_STRUCT = 40
+ENDIAN = "little"
+
+
+if __name__ == "__main__":
+    if len(sys.argv) < 2:
+        print("Provide a path to the kernel binary to use")
+        sys.exit(1)
+
+    with open(sys.argv[1], "rb") as elffile:
+        file = ELFFile(elffile)
+        section = file.get_section_by_name(".cmdline")
+        if section == None:
+            sys.exit(1)
+
+        cmdline_data = section.data()
+        num_options = int(section.data_size / SIZEOF_PTR)
+
+        print(f"Kernel contains {num_options} options:")
+
+        for i in range(num_options):
+            # Read "struct cmdline_option*"
+            addr = int.from_bytes(cmdline_data[(i * SIZEOF_PTR) :][:SIZEOF_PTR], byteorder=ENDIAN)
+            elffile.seek(next(file.address_offsets(start=addr)))
+            option = elffile.read(SIZEOF_STRUCT)
+
+            # Name
+            name = ""
+            name_ptr = int.from_bytes(option[0:][:SIZEOF_PTR], byteorder=ENDIAN)
+            elffile.seek(next(file.address_offsets(start=name_ptr)))
+            while True:
+                b = int.from_bytes(elffile.read(1))
+                if b == 0:
+                    break
+                name += chr(b)
+
+            # Description
+            desc = ""
+            desc_ptr = int.from_bytes(option[8:][:SIZEOF_PTR], byteorder=ENDIAN)
+            elffile.seek(next(file.address_offsets(start=desc_ptr)))
+            while True:
+                b = int.from_bytes(elffile.read(1))
+                if b == 0:
+                    break
+                desc += chr(b)
+
+            # Type
+            kind_str = "unknown"
+            kind = int.from_bytes(option[16:][:4], byteorder=ENDIAN)
+            match kind:
+                case 0:
+                    kind_str = "string"
+                case 1:
+                    kind_str = "bool"
+                case 2:
+                    kind_str = "integer"
+                case 2:
+                    kind_str = "unsigned integer"
+
+            # Skip function pointer
+
+            # Allowed values
+            limit = ""
+            limit_ptr = int.from_bytes(option[32:][:SIZEOF_PTR], byteorder=ENDIAN)
+
+            if limit_ptr != 0:
+                elffile.seek(next(file.address_offsets(start=limit_ptr)))
+                match kind:
+                    case 0:
+                        limit = []
+                        i = 0
+                        while True:
+                            ptr = next(file.address_offsets(start=limit_ptr + i * SIZEOF_PTR))
+                            elffile.seek(ptr)
+                            str_ptr = int.from_bytes(elffile.read(SIZEOF_PTR), byteorder=ENDIAN)
+                            if str_ptr == 0:
+                                break
+
+                            strstr_off = next(file.address_offsets(start=str_ptr))
+                            val = ""
+                            elffile.seek(strstr_off)
+                            while True:
+                                b = int.from_bytes(elffile.read(1))
+                                if b == 0:
+                                    break
+                                val += chr(b)
+                            i += 1
+                            limit.append(val)
+
+                    case 2:
+                        min = int.from_bytes(elffile.read(SIZEOF_PTR), byteorder=ENDIAN, signed=True)
+                        max = int.from_bytes(elffile.read(SIZEOF_PTR), byteorder=ENDIAN)
+                        limit = f"[{min}, {max}]"
+
+                    case 3:
+                        min = int.from_bytes(elffile.read(SIZEOF_PTR), byteorder=ENDIAN)
+                        max = int.from_bytes(elffile.read(SIZEOF_PTR), byteorder=ENDIAN)
+                        limit = f"[{min}, {max}]"
+
+            print(f"- {name}:\t{desc} ({kind_str}) {limit if len(limit) != 0 else ""}")