From e5a3a50a701c519fe8d00229b4d43945434ef88d Mon Sep 17 00:00:00 2001
From: Filip Grzywok <f.grzywok@gmail.com>
Date: Thu, 28 Sep 2023 23:32:05 +0200
Subject: [PATCH] feat: Back vmmap with info proc mappings on newer qemu
 versions

---
 pwndbg/commands/vmmap.py | 10 +++++++-
 pwndbg/gdblib/qemu.py    |  9 +++++++
 pwndbg/gdblib/vmmap.py   | 51 +++++++++++++++++++++++++++++++++++++++-
 3 files changed, 68 insertions(+), 2 deletions(-)

diff --git a/pwndbg/commands/vmmap.py b/pwndbg/commands/vmmap.py
index 2fb985933..f583c8fc0 100644
--- a/pwndbg/commands/vmmap.py
+++ b/pwndbg/commands/vmmap.py
@@ -3,6 +3,7 @@ Command to print the virtual memory map a la /proc/self/maps.
 """
 from __future__ import annotations
 
+import re
 import argparse
 
 import gdb
@@ -151,9 +152,16 @@ def vmmap(
 
         print(M.get(page.vaddr, text=display_text, prefix=backtrace_prefix))
 
-    if pwndbg.gdblib.qemu.is_qemu():
+    if pwndbg.gdblib.qemu.is_qemu() and not pwndbg.gdblib.qemu.exec_file_supported():
         print("\n[QEMU target detected - vmmap result might not be accurate; see `help vmmap`]")
 
+    gdb_version = tuple(map(int, re.search(r"(\d+)[^\d]+(\d+)", gdb.VERSION).groups()))
+    
+    # Only GDB versions >=12 report permission info in info proc mappings. On older versions, we fallback on "rwx".
+    # * https://github.com/bminor/binutils-gdb/commit/29ef4c0699e1b46d41ade00ae07a54f979ea21cc
+    if pwndbg.gdblib.qemu.is_qemu_usermode() and gdb_version[0] < 12:
+        print("\n[GDB <=12.1 detected - vmmap cannot fetch permission information, defaulting to rwx]")
+
 
 parser = argparse.ArgumentParser(description="Add virtual memory map page.")
 parser.add_argument("start", help="Starting virtual address")
diff --git a/pwndbg/gdblib/qemu.py b/pwndbg/gdblib/qemu.py
index fdbf70fa9..f87ae8491 100644
--- a/pwndbg/gdblib/qemu.py
+++ b/pwndbg/gdblib/qemu.py
@@ -58,6 +58,15 @@ def is_qemu_kernel() -> bool:
     return is_qemu() and not is_usermode()
 
 
+@pwndbg.lib.cache.cache_until("stop")
+def exec_file_supported() -> bool:
+    """Returns ``True`` if the qemu target supports exec file feature.
+    Used in `vmmap` to determine whether qemu supports `info proc mappings`
+    """
+    response = gdb.execute("maintenance packet qSupported", to_string=True, from_tty=False)
+
+    return "exec-file" in response
+
 @start
 @pwndbg.lib.cache.cache_until("stop")
 def root() -> Any | None:
diff --git a/pwndbg/gdblib/vmmap.py b/pwndbg/gdblib/vmmap.py
index b124c1d85..209396a51 100644
--- a/pwndbg/gdblib/vmmap.py
+++ b/pwndbg/gdblib/vmmap.py
@@ -91,7 +91,10 @@ def get() -> tuple[pwndbg.lib.memory.Page, ...]:
     if is_corefile():
         return tuple(coredump_maps())
 
-    proc_maps = proc_pid_maps()
+    if pwndbg.gdblib.qemu.is_qemu_usermode():
+        proc_maps = info_proc_maps()
+    else:
+        proc_maps = proc_pid_maps()
 
     # The `proc_maps` is usually a tuple of Page objects but it can also be:
     #   None    - when /proc/$pid/maps does not exist/is not available
@@ -338,6 +341,52 @@ def coredump_maps():
     return tuple(pages)
 
 
+@pwndbg.lib.cache.cache_until("start", "stop")
+def info_proc_maps():
+    """
+    Parse the result of info proc mappings.
+    Returns:
+        A tuple of pwndbg.lib.memory.Page objects or None if
+        info proc mapping is not supported on the target.
+    """
+
+    try:
+        info_proc_mappings = pwndbg.gdblib.info.proc_mappings().splitlines()
+    except gdb.error:
+        # On qemu user emulation, we may get: gdb.error: Not supported on this target.
+        info_proc_mappings = []
+
+    pages = []
+    for line in info_proc_mappings:
+        # We look for lines like:
+        # ['0x555555555000', '0x555555556000', '0x1000', '0x1000', 'rw-p', '/home/user/a.out']
+        try:
+            split_line = line.split()
+
+            # Permission info is only available in GDB versions >=12
+            # https://github.com/bminor/binutils-gdb/commit/29ef4c0699e1b46d41ade00ae07a54f979ea21cc
+            # Assume "rw-p" on older gdb versions
+            if len(split_line) < 6:
+                start, _end, size, offset, objfile = split_line
+                perm = 'rwxp'
+            else:
+                start, _end, size, offset, perm, objfile = split_line
+            start, size, offset = int(start, 16), int(size, 16), int(offset, 16)
+        except (IndexError, ValueError):
+            continue
+
+        flags = 0
+        if "r" in perm:
+            flags |= 4
+        if "w" in perm:
+            flags |= 2
+        if "x" in perm:
+            flags |= 1
+
+        pages.append(pwndbg.lib.memory.Page(start, size, flags, offset, objfile))
+
+    return tuple(pages)
+
 @pwndbg.lib.cache.cache_until("start", "stop")
 def proc_pid_maps():
     """