1 |
2014.Június 8.(V) 02:55 időpontban Anthony G. Basile ezt írta: |
2 |
> On 06/07/14 17:48, "Tóth Attila" wrote: |
3 |
>> 2014.Június 7.(Szo) 23:22 időpontban Alex Efros ezt írta: |
4 |
>>> Some time ago I noticed this in kernel logs: |
5 |
>>> kern.alert: grsec: denied RWX mmap of <anonymous mapping> by |
6 |
>>> /usr/lib64/python-exec/python2.7/layman[layman:9717] uid/euid:0/0 |
7 |
>>> gid/egid:0/0, parent /bin/bash[sh:9695] uid/euid:0/0 gid/egid:0/0 |
8 |
>>> |
9 |
>>> Looks like it doesn't break layman, but I still wonder why it happens |
10 |
>>> and |
11 |
>>> is it possible to fix this (without paxmarking python, of course)? |
12 |
>> |
13 |
>> I don't see this in my logs. The python executable has the "E" flag on |
14 |
>> my |
15 |
>> systems. |
16 |
>> |
17 |
>> Dw. |
18 |
>> |
19 |
> |
20 |
> Okay I need to document this loudly --- not sure how to do that except |
21 |
> to just keep repeating it until it becomes public knowledge: |
22 |
> |
23 |
> When running with a pax kernel, you must enable EMUTRAMP in your Kconfig |
24 |
> and you must paxmark your python exe's with E. Note: EMUTRAMP is on by |
25 |
> default and the ebuild automatically does the markings for you, so leave |
26 |
> the defaults alone. |
27 |
> |
28 |
> If you don't, python apps will hit rwx mmap denials by the pax kernel. |
29 |
> Things like libffi try to work around this by spitting out little |
30 |
> snippets of code to the filesystem when the mmap fails; but, if you have |
31 |
> strict TPE on, even this workaround fails and you get a pretty dead |
32 |
> system (all python apps badly crippled). There are various ways around |
33 |
> this but we've settled on the EMUTRAMP solution. See |
34 |
|
35 |
I see a problem here, that Alex has python binaries installed on his |
36 |
system with inconsistent PAX markings (PT: e, XATTR: E). I don't know his |
37 |
kernel config, but in my experience these flags can get misinterpreted |
38 |
instead of taking the XATTR:E flag or the default EMUTRAMP enabled. |
39 |
Despite it is not advised to keep both PT and XATTR markings on a system |
40 |
at the same time, some users may still have both and run into problems |
41 |
like Alex. |
42 |
I introduced kinda chpax init style logic as a workaround on my systems to |
43 |
double check sensitive binaries have correct PAX markings. |
44 |
Can we expect these symptoms to go away by the advent of the new hardened |
45 |
install helper? |
46 |
|
47 |
BR: Dw. |
48 |
-- |
49 |
dr Tóth Attila, Radiológus, 06-20-825-8057 |
50 |
Attila Toth MD, Radiologist, +36-20-825-8057 |