/usr/share/doc/user-mode-linux-doc/html/hppfs.html is in user-mode-linux-doc 20060501-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 | <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
"http://www.w3.org/TR/REC-html40/loose.dtd">
<html>
<head>
<meta content="text/html; charset=iso-8859-1" http-equiv="Content-Type">
<title>The Honeypot procfs</title>
</head>
<body alink="#FF0000" vlink="#55188A" link="#0000EF" bgcolor="#FFFFFF" text="#000099">
<table border="0">
<tr align="left">
<td valign="top">
<table border="0">
<tr align="left"><td valign="top" >
<img src="uml-small.png" height="171" width="120"/>
</td></tr>
<tr align="left"><td valign="top" bgcolor="#e0e0e0">
<font size="-1"><a href="index.html">Site Home Page</a></font>
<br>
<font size="-1"><a href="http://uml.harlowhill.com">The UML Wiki</a></font>
<br>
<font size="-1"><a href="http://usermodelinux.org">UML Community Site</a></font>
<br>
<font size="-1"><a href="roadmap.html">The UML roadmap</a></font>
<br>
<font size="-1"><a href="uses.html">What it's good for</a></font>
<br>
<font size="-1"><a href="case-studies.html">Case Studies</a></font>
<br>
<font size="-1"><a href="kernel.html">Kernel Capabilities</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/dl-sf.html">Downloading it</a></font>
<br>
<font size="-1"><a href="run.html">Running it</a></font>
<br>
<font size="-1"><a href="compile.html">Compiling</a></font>
<br>
<font size="-1"><a href="install.html">Installation</a></font>
<br>
<font size="-1"><a href="skas.html">Skas Mode</a></font>
<br>
<font size="-1"><a href="patches.html">Incremental Patches</a></font>
<br>
<font size="-1"><a href="tests.html">Test Suite</a></font>
<br>
<font size="-1"><a href="devanon.html">Host memory use</a></font>
<br>
<font size="-1"><a href="fs_making.html">Building filesystems</a></font>
<br>
<font size="-1"><a href="faq.html">Troubles</a></font>
<br>
<font size="-1"><a href="contrib.html">User Contributions</a></font>
<br>
<font size="-1"><a href="links.html">Related Links</a></font>
<br>
<font size="-1"><a href="todo.html">The ToDo list</a></font>
<br>
<font size="-1"><a href="projects.html">Projects</a></font>
<br>
<font size="-1"><a href="diary.html">Diary</a></font>
<br>
<font size="-1"><a href="thanks.html">Thanks</a></font>
<br>
<font size="-1"><a href="contacts.html">Contacts</a></font>
</td></tr>
<tr align="left"><td valign="top" bgcolor="#e0e0e0">Tutorials<br>
<font size="-1"><a href="UserModeLinux-HOWTO.html">The HOWTO (html)</a></font>
<br>
<font size="-1"><a href="UserModeLinux-HOWTO.txt.gz">The HOWTO (text)</a></font>
<br>
<font size="-1"><a href="hostfs.html">Host file access</a></font>
<br>
<font size="-1"><a href="input.html">Device inputs</a></font>
<br>
<font size="-1"><a href="shared_fs.html">Sharing filesystems</a></font>
<br>
<font size="-1"><a href="fs.html">Creating filesystems</a></font>
<br>
<font size="-1"><a href="resize.html">Resizing filesystems</a></font>
<br>
<font size="-1"><a href="networking.html">Virtual Networking</a></font>
<br>
<font size="-1"><a href="mconsole.html">Management Console</a></font>
<br>
<font size="-1"><a href="debugging.html">Kernel Debugging</a></font>
<br>
<font size="-1"><a href="honeypots.html">UML Honeypots</a></font>
<br>
<font size="-1"><a href="gprof.html">gprof and gcov</a></font>
<br>
<font size="-1"><a href="xtut.html">Running X</a></font>
<br>
<font size="-1"><a href="trouble.html">Diagnosing problems</a></font>
<br>
<font size="-1"><a href="config.html">Configuration</a></font>
<br>
<font size="-1"><a href="slack_readme.html">Installing Slackware</a></font>
<br>
<font size="-1"><a href="arch-port.html">Porting UML</a></font>
<br>
<font size="-1"><a href="iomem.html">IO memory emulation</a></font>
<br>
<font size="-1"><a href="2G-2G.html">UML on 2G/2G hosts</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/lksct/index.html">Adding a UML system call</a></font>
<br>
<font size="-1"><a href="nesting.html">Running nested UMLs</a></font>
</td></tr>
<tr align="left"><td valign="top" bgcolor="#e0e0e0">How you can help<br>
<font size="-1"><a href="help-gen.html">Overview</a></font>
<br>
<font size="-1"><a href="help-doc.html">Documentation</a></font>
<br>
<font size="-1"><a href="help-userspace.html">Utilities</a></font>
<br>
<font size="-1"><a href="help-kernel-v1.html">Kernel bugs</a></font>
<br>
<font size="-1"><a href="projects.html">Kernel projects</a></font>
</td></tr>
<tr align="left"><td valign="top" bgcolor="#e0e0e0">Screenshots<br>
<font size="-1"><a href="net.html">A virtual network</a></font>
<br>
<font size="-1"><a href="x.html">An X session</a></font>
</td></tr>
<tr align="left"><td valign="top" bgcolor="#e0e0e0">Transcripts<br>
<font size="-1"><a href="login.html">A login session</a></font>
<br>
<font size="-1"><a href="debug-session.html">A debugging session</a></font>
<br>
<font size="-1"><a href="slackinst.html">Slackware installation</a></font>
</td></tr>
<tr align="left"><td valign="top" bgcolor="#e0e0e0">Reference<br>
<font size="-1"><a href="switches.html">Kernel switches</a></font>
<br>
<font size="-1"><a href="slack_readme.html">Slackware README</a></font>
</td></tr>
<tr align="left"><td valign="top" bgcolor="#e0e0e0">Papers<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/als2000/index.html">ALS 2000 paper (html)</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/als2000.tex">ALS 2000 paper (TeX)</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/als2000/slides.html">ALS 2000 slides</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/lca2001/lca.html">LCA 2001 slides</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/ols2001/index.html">OLS 2001 paper (html)</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/ols2001.tex">OLS 2001 paper (TeX)</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/als2001/index.html">ALS 2001 paper (html)</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/als2001.tex">ALS 2001 paper (TeX)</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/ists2002/umlsec.htm">UML security (html)</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/lca2002/lca2002.htm">LCA 2002 (html)</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/wvu2002/wvu2002.htm">WVU 2002 (html)</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/ists_rt/ists_rt.htm">Security Roundtable (html)</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/ols2002/ols2002.html">OLS 2002 slides</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/lwe2005/LWE2005.html">LWE 2005 slides</a></font>
</td></tr>
<tr align="left"><td valign="top" bgcolor="#e0e0e0">Fun and Games<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/cgi-bin/hangman">Kernel Hangman</a></font>
<br>
<font size="-1"><a href="sdotm.html">Disaster of the Month</a></font>
</td></tr>
</table>
</td>
<td valign="top" align="left">
<center>
<h3>The Honeypot procfs</h3>
</center>
hppfs reads a proc hierarchy in the current working directory
on the host of the UML. When a UML process accesses a /proc entry,
hppfs consults the corresponding entry in this hierarchy to decide what
to do. This entry is a directory which contains a file which
describes what to do with that entry. The possibilities are as
follows:
<ul>
<li>
No entry on the host - hppfs passes the operation on to the UML /proc
- effectively this means that entry is unmodified. Most /proc entries
contain no information about whether the machine is a UML, so these
can be left alone.
</li>
<li>
The host entry is a normal file or symlink - the contents of this file
(or target of the link) will replace the UML /proc entry. This is
appropriate for /proc entries, such as /proc/cmdline, which can be
replaced by the corresponding /proc entry on the host. It is also
appropriate for entries which must be changed, but which are static.
In this case, you'd drop the static file into the host proc hierarchy
for that UML.
</li>
<li>
The host entry is a directory and contains
<ul>
<li>
"remove" (a normal file) - this causes the entry to disappear from the
UML /proc. This can be used to remove things which don't exist on
physical machines, such as /proc/exitcode and /proc/mconsole.
</li>
<li>
"r" (a unix socket) - this causes the entry to be generated on
demand by the process attached to the socket. This is useful for
entries which must be dynamically generated, but can be generated from
scratch on the host.
</li>
<li>
"rw" (a unix socket) - this is similar to "r", except that the current
UML /proc contents of that entry are written to the socket before the
new contents are read. This allows the host process to filter the UML
/proc data. This is useful when data must be removed from a UML /proc
entry.
</li>
</ul>
</li>
</ul>
The files inside /proc/<i>pid</i> need slightly special handling
because you can't know on the host what pids are going to be present
inside UML. UML looks in the pid subdirectory of the host's shadow
proc for all modifications of UML /proc/<i>pid</i> entries.
<p>
The uml_utilities tarball (under honeypot/) contains a few things to
simplify the disguising of a UML's /proc:
<ul>
<li>
hppfs.pm - A perl module which acts as a server for any dynamic proc
entries that need to be generated.
</li>
<li>
hppfslib.pm - A library which contains a set of utilities for
constructing a fake proc environment.
</li>
<li>
honeypot.pl - A sample driver for hppfs.pm and hppfslib.pm which
overrides a number of UML /proc entries in various ways.
</li>
</ul>
<a name="Example"/><table width="100%" bgcolor="#e0e0e0">
<tr>
<td>
<b>
<font color="black">Example</font>
</b>
</td>
</tr>
</table>
<blockquote head="Example">
Here is an example of setting up a customized UML /proc using hppfs.
<p>
First, boot a UML with hppfs enabled ('grep hppfs /proc/filesystems'
to check). Login in and mount hppfs over /proc:
<blockquote>
<tt>
<font color="#000000" where="UML">UML# mount none /proc -t hppfs</font>
</tt>
</blockquote>
ls /proc and notice that it doesn't seem any different than before:
<tt>
<pre>
<font size="-1">
usermode:~# ls /proc
1 130 137 7 devices interrupts loadavg mtd swaps
100 131 140 8 dma iomem locks net sys
104 132 2 93 driver ioports meminfo partitions sysvipc
109 133 3 95 execdomains irq misc scsi tty
121 134 4 bus exitcode kcore mm self uptime
126 135 5 cmdline filesystems kmsg modules slabinfo version
129 136 6 cpuinfo fs ksyms mounts stat
</font>
</pre>
</tt>
Create a proc directory in the current working directory of the UML
<blockquote>
<tt>
<font color="#000000" where="host">host% mkdir proc</font>
</tt>
</blockquote>
Now, put something into proc/cmdline
<blockquote>
<tt>
<font color="#000000" where="host">host% echo 'hi there' > proc/cmdline</font>
</tt>
</blockquote>
and look at the UML's /proc/cmdline
<tt>
<pre>
<font size="-1">
usermode#~: cat /proc/cmdline
hi there
</font>
</pre>
</tt>
This should give you a good idea of how to make simple modifications
to the UML's /proc. A more realistic example would be to make
/proc/cmdline the same as on the host. You can do this by copying the
host's /proc/cmdline into proc, but a symbolic link will work, too:
<blockquote>
<tt>
<font color="#000000" where="host">host% ln -s /proc/cmdline proc/cmdline</font>
</tt>
</blockquote>
<tt>
<pre>
<font size="-1">
usermode:~# cat /proc/cmdline
auto BOOT_IMAGE=2.4.19 ro root=306 BOOT_FILE=/boot/vmlinuz
</font>
</pre>
</tt>
With that step, you removed one way for an intruder to fingerprint the
machine as a UML. There are a bunch of others, and it would be nice
to automate the creation of realistic, fake data for them as well.
<p>
Grab the uml_utilities tarball, unpack it, and cd into honeypot/. Run
honeypot.pl with the current directory of UML as an argument:
<blockquote>
<tt>
<font color="#000000" where="host">host% perl ./honeypot.pl ~/linux/2.4/um/</font>
</tt>
</blockquote>
honeypot.pl asks the hppfs module to
<ul>
<li>
create the directory:
<tt>
<pre>
<font size="-1">
my $hppfs = hppfs->new($dir);
</font>
</pre>
</tt>
</li>
<li>
initialize its contents:
<tt>
<pre>
<font size="-1">
$hppfs->add("devices" => remove_line("ubd"),
"uptime" => proc("uptime"),
"exitcode" => "remove",
"filesystems" => remove_line("hppfs"),
"interrupts" => proc("interrupts"),
"iomem" => proc("iomem"),
"ioports" => proc("ioports"),
"mounts" => remove_line("hppfs"),
"pid/mounts" => remove_line("hppfs"),
"version" => proc("version") );
</font>
</pre>
</tt>
</li>
<li>
call the hppfs server main loop, which will service requests from the
hppfs client inside UML for dynamic proc entries:
<tt>
<pre>
<font size="-1">
$hppfs->handler();
</font>
</pre>
</tt>
</li>
</ul>
If you look at the proc directory now, you will see a bunch of new
entries:
<tt>
<pre>
<font size="-1">
host% ls ~/linux/2.4/um/proc/
devices filesystems iomem mounts uptime
exitcode interrupts ioports pid version
</font>
</pre>
</tt>
These all need some sort of manipulation.
<ul>
<li>
Removal - /proc/exitcode is specific to UML; writing to it allows the
exit code of UML on the host to be changed. This obviously can't be
present in a honeypot, so the argument
<blockquote>
<tt>
<font color="#000000"> "exitcode" => "remove",</font>
</tt>
</blockquote>
to hppfs::add causes it to create an exitcode directory in proc on the
host:
<tt>
<pre>
<font size="-1">
host% ls -al ~/linux/2.4/um/proc/exitcode
total 8
drwxrw-rw- 2 jdike jdike 4096 Dec 18 14:43 .
drwxrw-rw- 11 jdike jdike 4096 Dec 18 14:43 ..
-rw-rw-rw- 1 jdike jdike 0 Dec 18 14:43 remove
</font>
</pre>
</tt>
The 'remove' entry tells hppfs to hide the UML /proc 'exitcode' file,
and 'ls /proc' inside the UML shows that it is indeed gone.
</li>
<li>
Fabrication - we've already seen an example of fabricating a proc
entry from scratch. Dropping a static file into proc will cause it to
replace the corresponding UML /proc entry. However, lots of /proc
files are dynamic, so looking at it twice and seeing exactly the same
data would be a tip-off that something's wrong. If the host's /proc
entry is usable, then a symbolic link from the shadow proc to /proc
will be fine. This is what these arguments to hppfs::add do:
<tt>
<pre>
<font size="-1">
"uptime" => proc("uptime"),
"interrupts" => proc("interrupts"),
"iomem" => proc("iomem"),
"ioports" => proc("ioports"),
"mounts" => remove_line("hppfs"),
"pid/mounts" => remove_line("hppfs"),
"version" => proc("version") );
</font>
</pre>
</tt>
</li>
(although the actual hppfslib implementation of proc() currently has
the hppfs server execute 'cat /proc/<file>')
<li>
Filtering - sometimes the host's /proc or anything else we can
generate on the host won't be right. Instead, we might want to take
the UML /proc file contents and manipulate them somehow. An example
is /proc/filesystems. In this honeypot, it contains an entry for
hppfs, which can't be allowed to remain. So, this argument to
hppfs::add causes that one line to be removed, leaving everything else
the same:
<tt>
<pre>
<font size="-1">
"filesystems" => remove_line("hppfs"),
</font>
</pre>
</tt>
</li>
<li>
Note the "pid/mounts" entry. That covers all references to any
/proc/<i>pid</i>/mounts file inside UML.
</li>
</ul>
</blockquote>
</td>
</tr>
</table>
<center>
<font size="-1">Hosted at </font>
<a href="http://sourceforge.net">
<img src="" width="88" height="31" border="0" alt="SourceForge Logo">
</a>
</center>
</body>
</html>
|