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GP-3887: Update Debugger course for Trace RMI.

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GhidraDocs/GhidraClass/Debugger/A1-GettingStarted.html
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@ -128,16 +128,14 @@ icon in my Tool Chest</a></li>
<li><a href="#there-is-no-debug-launch-icon-in-the-global-toolbar"
id="toc-there-is-no-debug-launch-icon-in-the-global-toolbar">There is no
Debug / Launch icon in the global toolbar</a></li>
<li><a href="#there-is-no-gdb-option-in-the-launch-drop-down"
id="toc-there-is-no-gdb-option-in-the-launch-drop-down">There is no
<strong>gdb</strong> option in the launch drop-down</a></li>
<li><a
href="#there-is-no-debug-termmines-in-gdb-locally-in-vm-option-in-the-launch-drop-down"
id="toc-there-is-no-debug-termmines-in-gdb-locally-in-vm-option-in-the-launch-drop-down">There
is no “Debug termmines in GDB locally IN-VM” option in the launch
drop-down</a></li>
<li><a
href="#the-launch-hangs-for-several-seconds-and-then-prompt-for-a-recorder"
id="toc-the-launch-hangs-for-several-seconds-and-then-prompt-for-a-recorder">The
launch hangs for several seconds and then prompt for a
“recorder”</a></li>
href="#the-launch-hangs-for-several-seconds-and-then-i-get-prompted-with-a-wall-of-text"
id="toc-the-launch-hangs-for-several-seconds-and-then-i-get-prompted-with-a-wall-of-text">The
launch hangs for several seconds and then I get prompted with a wall of
text</a></li>
<li><a href="#the-dynamic-listing-is-empty"
id="toc-the-dynamic-listing-is-empty">The Dynamic Listing is
empty</a></li>
@ -192,8 +190,16 @@ trust. For <code>termmines</code>, the risk is negligible. Run it:</p>
<div class="sourceCode" id="cb2"><pre
class="sourceCode bash"><code class="sourceCode bash"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="ex">./termmines</span></span></code></pre></div>
<p>You should see a 9x9 grid and a cursor you can move with the arrow
keys. Hit <strong>Ctrl-C</strong> to exit. Probe it for help. Most Linux
programs accept a <code>-h</code> argument for help:</p>
keys.</p>
<figure>
<img src="images/GettingStarted_Termmines.png"
alt="Termmines running in a Terminal" />
<figcaption aria-hidden="true">Termmines running in a
Terminal</figcaption>
</figure>
<p>Hit <strong><code>CTRL</code>-<code>C</code></strong> to exit. Probe
it for help. Most Linux programs accept a <code>-h</code> argument for
help:</p>
<div class="sourceCode" id="cb3"><pre
class="sourceCode bash"><code class="sourceCode bash"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a><span class="ex">./termmines</span> <span class="at">-h</span></span></code></pre></div>
<p>You should now have all the information you need to understand how
@ -223,7 +229,18 @@ open</figcaption>
</figure></li>
<li><p>In the Debugger tool, click the dropdown ▾ for the debug <img
src="images/debugger.png" alt="debug button" /> icon in the global tool
bar, and select “Debug termmines in GDB locally IN-VM.”</p></li>
bar, and select <strong>Configure and Launch termmines using… →
gdb</strong>.</p>
<figure>
<img src="images/GettingStarted_LaunchGDBDialog.png"
alt="Launch GDB Dialog" />
<figcaption aria-hidden="true">Launch GDB Dialog</figcaption>
</figure></li>
<li><p>Change the <strong>Run Command</strong> to “start” (not
“starti”). <strong>NOTE</strong>: In practice, this is rarely
recommended, because most targets do not export their <code>main</code>
function.</p></li>
<li><p>Click the <strong>Launch</strong> button in the dialog.</p></li>
<li><p>Wait a bit then verify the Dynamic Listing window (top) is
displaying disassembly code.</p>
<figure>
@ -236,20 +253,18 @@ termmines</figcaption>
</section>
<section id="launching-on-windows" class="level2">
<h2>Launching on Windows</h2>
<p>On Windows, we will use dbgeng to debug the specimen. This is the
engine that backs WinDbg. You may choose an alternative Minesweeper,
since terminal applications are less representative of Windows
executables. Follow the same process as for Linux, except import
<code>termmines.exe</code> and select “Debug termmines.exe in dbgeng
locally IN-VM.”</p>
<p>On Windows, we will use the Windows Debugger dbgeng.dll to debug the
specimen. This is the engine that backs WinDbg. You may choose an
alternative Minesweeper, since terminal applications are less
representative of Windows executables. Follow the same process as for
Linux, except import <code>termmines.exe</code> and select
<strong>Configure and Launch termmines.exe using… → dbgeng</strong>.</p>
</section>
<section id="launching-on-macos" class="level2">
<h2>Launching on macOS</h2>
<p>Unfortunately, things are not so simple on macOS. See the
instructions for <a
href="../../../Ghidra/Debug/Debugger-swig-lldb/InstructionsForBuildingLLDBInterface.txt">Building
LLDB-Java Bindings</a>. Once built, follow the same process as for
Linux, except select “Debug termmines in LLDB locally IN-VM.”</p>
<p>On macOS, we will use LLDB to debug the specimen. This is the
debugger included with Xcode. Follow the same process as for Linux,
except choose <strong>lldb</strong> in the last menu.</p>
</section>
<section id="troubleshooting" class="level2">
<h2>Troubleshooting</h2>
@ -280,73 +295,71 @@ tool. If it is still not there, then you may need to re-import the
default Debugger tool as under the previous heading. If it is still not
there, your installation may be corrupt.</p>
</section>
<section
id="there-is-no-debug-termmines-in-gdb-locally-in-vm-option-in-the-launch-drop-down"
<section id="there-is-no-gdb-option-in-the-launch-drop-down"
class="level3">
<h3>There is no “Debug termmines in GDB locally IN-VM” option in the
launch drop-down</h3>
<p>You may need to install GDB and/or configure Ghidra with its
location. If you have a copy or custom build of GDB in a non-system
path, note its full path. If you intend to use the system’s copy of GDB,
then in a terminal:</p>
<div class="sourceCode" id="cb4"><pre
class="sourceCode bash"><code class="sourceCode bash"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="fu">which</span> gdb</span></code></pre></div>
<p>Note the path given. (If you get an error, then you need to install
GDB.) In a terminal, type the full path of GDB to ensure it executes
properly. Type <code>q</code> to quit GDB.</p>
<ol type="1">
<li>From the Debugger Targets window, click the Connect <img
src="images/connect.png" alt="connect button" /> button.</li>
<li>In the Connect dialog, select “gdb” from the dropdown at the
top.</li>
<li>Enter the full path, e.g., <code>/usr/bin/gdb</code>, in the “GDB
launch command” field.</li>
<li>Click “Connect”</li>
<li>If you get an Interpreter window, then things have gone well.</li>
<li>Type <code>echo test</code> into it to verify it’s responsive, then
type <code>q</code> to disconnect.</li>
<li>Close the Debugger tool, then retry.</li>
</ol>
<h3>There is no <strong>gdb</strong> option in the launch drop-down</h3>
<p>You may have an older Debugger tool still configured for
Recorder-based targets. We are transitioning to TraceRmi-based targets.
Delete your Debugger tool and re-import the default one using the
instructions above. If it is still not there, it’s possible your
installation is corrupt. Search for a file called
<code>local-gdb.sh</code> in your installation. Unlike the previous
system, Trace RMI will not probe your system for dependencies nor hide
incompatible launchers. All installed launchers should be present in the
menus, even though some may not work on your configuration.</p>
</section>
<section
id="the-launch-hangs-for-several-seconds-and-then-prompt-for-a-recorder"
id="the-launch-hangs-for-several-seconds-and-then-i-get-prompted-with-a-wall-of-text"
class="level3">
<h3>The launch hangs for several seconds and then prompt for a
“recorder”</h3>
<p>You probably have a stale GDB connection, so when you launched you
now have multiple connections. For the prompt, select the option with
the highest score. Examine the Targets window to confirm you have
multiple GDB connections. If you know which is the stale connection, you
can right-click it and choose <strong>Disconnect</strong>. Otherwise,
use <strong>Disconnect All</strong> from the drop-down menu and
re-launch.</p>
<h3>The launch hangs for several seconds and then I get prompted with a
wall of text</h3>
<p>Read the wall of text. The first line should tell you the exception
that it encountered. Often this is a timeout. Press the
<strong>Keep</strong> button and then find the Terminal, usually in the
bottom right. If you do not see it there, check the <strong>Window →
Terminals</strong> menu. Once you have found the Terminal, check its
output <em>starting at the top</em> for diagnostic messages. If you have
something like <code>bash: gdb: command not found</code>, it is because
you are missing <code>gdb</code>, or you need to tell Ghidra where to
find it.</p>
<p>If it is just missing, then install it and try again. If you need to
tell Ghidra where it is, then in the launcher drop-down, select
<strong>Configure and Launch termmines using… → gdb</strong>. DO NOT
select <strong>Re-launch termmines using gdb</strong>, since this will
not allow you to correct the configuration.</p>
</section>
<section id="the-dynamic-listing-is-empty" class="level3">
<h3>The Dynamic Listing is empty</h3>
<p>Check for an actual connection. You should see an entry in the
Debugger Targets window, a populated Object window, and there should be
an Interpreter window. If not, then your GDB connector may not be
configured properly. Try the steps under the previous heading.</p>
<p>If you have an Interpreter window, there are several
<strong>Connection Manager</strong> window, a populated
<strong>Model</strong> window, and there should be a
<strong>Terminal</strong> window. If not, then your GDB connector may
not be configured properly. Try the steps under the previous
heading.</p>
<p>If you have a <strong>Terminal</strong> window, there are several
possibilities:</p>
<section id="ghidra-or-gdb-failed-to-launch-the-target" class="level4">
<h4>Ghidra or GDB failed to launch the target:</h4>
<p>Check that the original <code>termmines</code> exists and is
executable. It must be at the path from where it was originally
imported. If you imported from a share, consider copying it locally,
setting its permissions, then re-importing.</p>
<p>If this is the case, you should see an error message in the Terminal,
e.g.: <code>termmines: no such file or directory</code>. Check that the
original <code>termmines</code> exists and is executable. You may also
need to adjust the <strong>Image</strong> option when configuring the
launch.</p>
</section>
<section id="the-target-was-launched-but-immediately-terminated"
class="level4">
<h4>The target was launched, but immediately terminated:</h4>
<p>Check that the specimen has a <code>main</code> symbol. NOTE: It is
<p>If this is the case, you should see a message in the Terminal, e.g.:
<code>[Inferior 1 (process 1234) exited normally]</code>. Check that the
specimen has a <code>main</code> symbol. <strong>NOTE</strong>: It is
not sufficient to place a <code>main</code> label in Ghidra. The
original file must have a <code>main</code> symbol.</p>
<p>Alternatively, in the menus try <strong>Debugger → Debug termmines →
in GDB locally IN-VM</strong>, and select “Use starti.” This will break
at the system entry point. If you have labeled <code>main</code> in
Ghidra, then you can place a breakpoint there and continue — these
features are covered later in the course.</p>
<p>Alternatively, in the menus try <strong>Debugger → Configure and
Launch termmines using → gdb</strong>, and select “starti” for
<strong>Run Command</strong>. This will break at the system entry point.
If you have labeled <code>main</code> in Ghidra, then you can place a
breakpoint there and continue — these features are covered later in the
course.</p>
<p>Alternatively, try debugging the target in GDB from a separate
terminal completely outside of Ghidra to see if things work as
expected.</p>
@ -356,37 +369,37 @@ class="level4">
<h4>The target was launched, but has not stopped, yet</h4>
<p>Try pressing the Interrupt <img src="images/interrupt.png"
alt="interrupt button" /> button. If that doesn’t work or is
unsatisfactory, try the remedies under the previous heading — for an
immediately terminating target.</p>
unsatisfactory, try the remedies under the previous heading.</p>
</section>
<section
id="you-hit-an-uncommon-bug-where-the-memory-map-is-not-applied-properly"
class="level4">
<h4>You hit an uncommon bug where the memory map is not applied
properly</h4>
<p>This is the case if the Dynamic Listing is completely blank but the
Regions window is replete. The Dynamic Listing just needs to be kicked a
little. The easiest way is to step once, using the <img
src="images/stepinto.png" alt="step into" /> Step Into button in the
main toolbar. If this is not desirable, then you can toggle
<strong>Force Full View</strong> back and forth. In the Regions window,
use the drop-down menu to toggle it on, then toggle it off. The Dynamic
Listing should now be populated. To go to the program counter,
double-click the “pc = …” label in the top right.</p>
<p>This is the case if the <strong>Dynamic Listing</strong> is
completely blank but the <strong>Regions</strong> window is replete. The
<strong>Dynamic Listing</strong> just needs to be kicked a little. The
easiest way is to step once, using the <img src="images/stepinto.png"
alt="step into" /> <strong>Step Into</strong> button in the main
toolbar. If this is not desirable, then you can toggle <strong>Force
Full View</strong> back and forth. In the <strong>Regions</strong>
window, use the drop-down menu to toggle it on, then toggle it off. The
<strong>Dynamic Listing</strong> should now be populated. To go to the
program counter, double-click the “pc = …” label in the top right.</p>
</section>
<section id="something-else-has-gone-wrong" class="level4">
<h4>Something else has gone wrong</h4>
<p>Try typing <code>info inferiors</code> and similar GDB diagnostic
commands into the Interpreter.</p>
commands into the <strong>Terminal</strong>.</p>
</section>
</section>
<section
id="the-listings-are-in-sync-but-the-dynamic-listing-is-grey-00s"
class="level3">
<h3>The listings are in sync, but the Dynamic Listing is grey 00s</h3>
<p>Check the Auto-Read drop-down near the top right of the Dynamic
Listing. It should be set to <strong>Read Visible Memory, RO
Once</strong>.</p>
<p>Check the <strong>Auto-Read</strong> drop-down near the top right of
the <strong>Dynamic Listing</strong>. It should be set to <strong>Read
Visible Memory, RO Once</strong>.</p>
</section>
</section>
<section id="exercise-launch-termmines" class="level2">
@ -395,63 +408,66 @@ Once</strong>.</p>
<code>termmines</code> and/or start a new Ghidra Project. Starting from
the beginning, import <code>termmines</code> and launch it in the Ghidra
Debugger with GDB. When your tool looks like the screenshot with a
populated Dynamic Listing, you have completed the exercise. Disconnect
before proceeding to the next exercise.</p>
populated <strong>Dynamic Listing</strong>, you have completed the
exercise. Disconnect before proceeding to the next exercise.</p>
</section>
<section id="customized-launching" class="level2">
<h2>Customized Launching</h2>
<p>For this specimen, you may occasionally need to provide custom
command-line parameters. By default, Ghidra attempts to launch the
target without any parameters. In the menus, use <strong>Debugger →
Debug termmmines → in GDB locally IN-VM</strong> to launch with
customizations. Ghidra will remember these customizations the next time
you launch using the drop-down button from the toolbar. The first dialog
allows you to customize the connection to the back-end debugger. Unless
you have a special copy of GDB, you should probably just click Connect.
The second dialog allows you to customize how the back-end debugger
launches the target. This is where you tweak the command line. You can
also change the actual image, in case it has moved or you want to
experiment with a patched version.</p>
target without any parameters. In the <strong>Debugger</strong> menu, or
the <strong>Launch</strong> button’s drop-down menu, use
<strong>Configure and Launch termmmines → gdb</strong> to adjust your
configuration. This is where you can specify the image path and
command-line parameters of your target. Ghidra will remember this
configuration the next time you launch using the drop-down button from
the toolbar. Launchers with memorized configurations are presented as
<strong>Re-launch termmines using…</strong> options. Using one of those
entries will re-launch with the saved configuration rather than
prompting.</p>
</section>
<section id="exercise-launch-with-command-line-help" class="level2">
<h2>Exercise: Launch with Command-line Help</h2>
<p>Launch the specimen so that it prints its usage. When successful, you
will see the usage info in the Debugger’s Interpreter window.
<strong>NOTE</strong>: The process will terminate after printing its
usage, and as a result, the rest of the UI will be mostly empty.</p>
will see the usage info in the Debugger’s <strong>Terminal</strong>
window. <strong>NOTE</strong>: The process will terminate after printing
its usage, and as a result, the rest of the UI will be mostly empty.</p>
</section>
<section id="attaching" class="level2">
<h2>Attaching</h2>
<p>Attaching is slightly more advanced, but because the target will need
to read from stdin, and Ghidra does not properly attach the Interpreter
to stdin, we will need to launch the target in a terminal and attach to
it instead. Note this technique is only possible because the target
waits for input. Depending on the task for future exercises, you may
still need to launch from the Debugger instead of attaching.</p>
<p>Attaching is slightly more advanced, but can be useful if the target
is part of a larger system, and it needs to be running <em>in situ</em>.
For this section, we will just run <code>termmines</code> in a separate
terminal and then attach to it from Ghidra. This used to be required,
because the older Recorder-based system did not provide target I/O, but
this limitation is overcome by the new <strong>Terminal</strong> window
when using Trace RMI. Note this technique is only possible because the
target waits for input.</p>
<ol type="1">
<li>Run <code>termmines</code> in a proper terminal with the desired
command-line parameters.</li>
<li>In the Ghidra Debugger, find the Targets window, and click the <img
src="images/connect.png" alt="connect" /> Connect button.</li>
<li>Select “gdb” from the drop-down box.</li>
<li>This dialog should look familiar from the Customized Launching
section. Just click the Connect button.</li>
<li>In the Objects window (below the Targets window), expand the node
labeled “Available.”</li>
<li>Run <code>termmines</code> in a terminal outside of Ghidra with the
desired command-line parameters.</li>
<li>In the Ghidra Debugger, use the <strong>Launch</strong> button
drop-down and select <strong>Configured and Launch termmines using… →
raw gdb</strong>. The “raw” connector will give us a GDB session without
a target.</li>
<li>Ghidra needs to know the location of gdb and the architecture of the
intended target. The defaults are correct for 64-bit x86 targets using
the system’s copy of GDB. Probably, you can just click
<strong>Launch</strong>.</li>
<li>In the <strong>Model</strong> window (to the left), expand the
<em>Available</em> node.</li>
<li>In the filter box, type <code>termmines</code>.</li>
<li>Right-click on the termmines process and select Attach. If this
fails, select Available again, and click the
<img alt="refresh" src="images/view-refresh.png" width="16px"> Refresh
button.</li>
<li>Note the PID, e.g. 1234, then in the <strong>Terminal</strong> type,
e.g., <code>attach 1234</code>.</li>
</ol>
</section>
<section id="exercise-attach" class="level2">
<h2>Exercise: Attach</h2>
<p>Try attaching on your own, if you have not already. Check your work
by typing <code>bt</code> into the Interpreter. If you are in
<code>read</code> you have completed this exercise. Disconnect before
proceeding to the next module: <a href="A2-UITour.html">A Tour of the
UI</a></p>
by typing <code>bt</code> into the <strong>Terminal</strong>. If you are
in <code>read</code> you have completed this exercise. Quit GDB from the
<strong>Terminal</strong> before proceeding to the next module: <a
href="A2-UITour.html">A Tour of the UI</a></p>
</section>
<section id="troubleshooting-1" class="level2">
<h2>Troubleshooting</h2>
@ -464,14 +480,15 @@ be traced by any other process and then executes a shell command. Using
specimen in the permissive process, and thus you can attach to it as if
<code>ptrace_scope=0</code>, but without reducing the security of the
rest of the system. For example:</p>
<div class="sourceCode" id="cb5"><pre
class="sourceCode bash"><code class="sourceCode bash"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="ex">./anyptracer</span> <span class="st">&#39;exec ./termmines&#39;</span></span></code></pre></div>
<div class="sourceCode" id="cb4"><pre
class="sourceCode bash"><code class="sourceCode bash"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="ex">./anyptracer</span> <span class="st">&#39;exec ./termmines&#39;</span></span></code></pre></div>
<p>Alternatively, if you have root access, you can rectify the issue
using the relevant documentation available online.
<strong>Beware!</strong> You should not modify this setting on your
daily driver, as this substantially reduces the security of your system.
Any compromised process would be allowed to attach to and steal data,
e.g., credentials, from any other process owned by the same user.</p>
<strong>Beware!</strong> You should not set <code>ptrace_scope=0</code>
globally, except on a system set aside for debugging, as this
substantially reduces the security of that system. Any compromised
process would be allowed to attach to and steal data, e.g., credentials,
from any other process owned by the same user.</p>
</section>
</section>
</body>