| 1203 |
I made "(current->uid == 0 && current->euid == 0)" requirement optional. |
I made "(current->uid == 0 && current->euid == 0)" requirement optional. |
| 1204 |
If this requirement is disabled, only "conventional DAC permission |
If this requirement is disabled, only "conventional DAC permission |
| 1205 |
checks" and "/proc/ccs/manager checks" are used. |
checks" and "/proc/ccs/manager checks" are used. |
| 1206 |
|
|
| 1207 |
|
Fix 2008/02/29 |
| 1208 |
|
|
| 1209 |
|
@ Add sleep_on_violation feature. |
| 1210 |
|
|
| 1211 |
|
Some exploit codes (e.g. trans2open for Samba) continue running |
| 1212 |
|
until it achieves the purpose of the exploit code (e.g. invoke /bin/sh). |
| 1213 |
|
|
| 1214 |
|
If such code is injected due to buffer overflow but the kernel |
| 1215 |
|
rejects the request, it triggers infinite "Permission denied" loop. |
| 1216 |
|
As a result, the CPU usage becomes 100% and gives bad effects to |
| 1217 |
|
the rest of processes. |
| 1218 |
|
This is a side effect of rejecting the request from the exploit code |
| 1219 |
|
which wouldn't happen if the request from the exploit code was granted. |
| 1220 |
|
|
| 1221 |
|
To avoid such CPU consumption, I added a penalty that forcibly |
| 1222 |
|
sleeps for specified period when a request is rejected. |
| 1223 |
|
|
| 1224 |
|
This penalty doesn't work if the exploit code does nothing but |
| 1225 |
|
continue running, but I think most exploit code's purpose is |
| 1226 |
|
to start some program rather than to slow down the target system. |
| 1227 |
|
|
| 1228 |
|
@ Add alt_exec feature. |
| 1229 |
|
|
| 1230 |
|
Since TOMOYO Linux's approach is "know all essential requests in advance |
| 1231 |
|
and create policy that permits only them", you can regard anomalous |
| 1232 |
|
requests as attacks (if you want to do so). |
| 1233 |
|
|
| 1234 |
|
Common MAC implementations merely reject requests that violate policy. |
| 1235 |
|
But I added a special handler for execve() to TOMOYO Linux. |
| 1236 |
|
|
| 1237 |
|
This handler is triggered when a process requested to execute a program |
| 1238 |
|
but the request was rejected by the policy. |
| 1239 |
|
This handler executes a program specified by the administrator |
| 1240 |
|
instead of a program requested by the process. |
| 1241 |
|
|
| 1242 |
|
Most attackers attempt to execute /bin/sh to start something malicious. |
| 1243 |
|
Attackers execute an exploit code using buffer overflow vulnerability |
| 1244 |
|
to steal control of a process. But this handler can get back control |
| 1245 |
|
if an exploit code requests execve() that is not permitted by policy. |
| 1246 |
|
|
| 1247 |
|
By default, this handler does nothing (i.e. merely reject execve() |
| 1248 |
|
request). You can specify any program to start what you want to do. |
| 1249 |
|
|
| 1250 |
|
You can redirect attackers to somewhere else (e.g. honeypot). |
| 1251 |
|
This makes it possible to act your Linux box as an on-demand honeypot |
| 1252 |
|
while keeping regular services for your usage. |
| 1253 |
|
|
| 1254 |
|
You can collect information of the attacker (e.g. IP address) and |
| 1255 |
|
update firewall configuration. |
| 1256 |
|
|
| 1257 |
|
You can silently terminate a process who requested execve() |
| 1258 |
|
that is not permitted by policy. |
| 1259 |
|
|
| 1260 |
|
Fix 2008/03/03 |
| 1261 |
|
|
| 1262 |
|
@ Add "force_alt_exec" keyword. |
| 1263 |
|
|
| 1264 |
|
To be able to fully utilize "alt_exec" feature, |
| 1265 |
|
I added "force_alt_exec" keyword so that |
| 1266 |
|
all execute requests are replaced by the execute request of a program |
| 1267 |
|
specified by alt_exec feature. |
| 1268 |
|
|
| 1269 |
|
If this keyword is specified for a domain, the domain no longer |
| 1270 |
|
executes any programs regardless of the mode of file access control |
| 1271 |
|
(i.e. the domain won't execute even if MAC_FOR_FILE=0 ). |
| 1272 |
|
Instead, the domain executes the program specified by alt_exec feature |
| 1273 |
|
and the program specified by alt_exec feature validates the execute |
| 1274 |
|
request and executes it if it is appropriate to execute. |
| 1275 |
|
|
| 1276 |
|
If you can tolerate that there is no chance to return an error code |
| 1277 |
|
to the caller to tell the execute request was rejected, |
| 1278 |
|
this is more flexible approach than in-kernel execve() parameter |
| 1279 |
|
checking because we can do argv[] and envp[] checking easily. |
| 1280 |
|
|
| 1281 |
|
Fix 2008/03/04 |
| 1282 |
|
|
| 1283 |
|
@ Use string for access control mode. |
| 1284 |
|
|
| 1285 |
|
An integer expression for access control mode sometimes confuses |
| 1286 |
|
administrators because profile number is also an integer expression. |
| 1287 |
|
To avoid confusion between profile number and access control mode, |
| 1288 |
|
I introduced a string expression for access control mode. |
| 1289 |
|
|
| 1290 |
|
Modes which take an integer between 0 and 3. |
| 1291 |
|
|
| 1292 |
|
0 -> disabled |
| 1293 |
|
1 -> learning |
| 1294 |
|
2 -> permissive |
| 1295 |
|
3 -> enforcing |
| 1296 |
|
|
| 1297 |
|
Modes which take 0 or 1. |
| 1298 |
|
|
| 1299 |
|
0 -> disabled |
| 1300 |
|
1 -> enabled |
| 1301 |
|
|
| 1302 |
|
Fix 2008/03/10 |
| 1303 |
|
|
| 1304 |
|
@ Rename "force_alt_exec" keyword to "preferred_execute_handler". |
| 1305 |
|
|
| 1306 |
|
To be able to use different programs for validating execve() parameters, |
| 1307 |
|
I moved the location to specify the program's pathname from profile |
| 1308 |
|
to domain policy. |
| 1309 |
|
|
| 1310 |
|
The "preferred_execute_handler" keyword takes one pathname which is |
| 1311 |
|
invoked whenever execve() request is issued. Thus, any "allow_execute" |
| 1312 |
|
keywords in a domain with "preferred_execute_handler" are ignored. |
| 1313 |
|
This keyword is designed for validating expected/desirable execve() |
| 1314 |
|
requests in userspace, although there is no way to tell the caller |
| 1315 |
|
that the execve() request was rejected. |
| 1316 |
|
|
| 1317 |
|
@ Rename "alt_exec" keyword to "default_execute_handler". |
| 1318 |
|
|
| 1319 |
|
The "default_execute_handler" keyword takes one pathname which is |
| 1320 |
|
invoked only when execve() request was rejected. In other words, |
| 1321 |
|
this program is invoked only when the following conditions are met. |
| 1322 |
|
|
| 1323 |
|
(1) None of "allow_execute" keywords in the domain didn't match. |
| 1324 |
|
(2) The execve() request was rejected in enforcing mode. |
| 1325 |
|
(3) "preferred_execute_handler" keyword is not used by the domain. |
| 1326 |
|
|
| 1327 |
|
This keyword is designed for handling unexpected/undesirable execve() |
| 1328 |
|
requests, to redirect the process issuing such requests to somewhere. |
| 1329 |
|
|
| 1330 |
|
Fix 2008/03/18 |
| 1331 |
|
|
| 1332 |
|
@ Fix wrong/redundant locks in pre-vfs functions. |
| 1333 |
|
|
| 1334 |
|
lock_kernel()/unlock_kernel() in pre_vfs_rename() were redundant for |
| 1335 |
|
2.6 kernels. |
| 1336 |
|
|
| 1337 |
|
Locking order in pre_vfs_link() and pre_vfs_unlink() for 2.4 kernels |
| 1338 |
|
after 2.4.33 were different from before 2.4.32 . |
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