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On 06/08/14 04:31, "Tóth Attila" wrote: |
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> 2014.Június 8.(V) 02:55 időpontban Anthony G. Basile ezt írta: |
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>> On 06/07/14 17:48, "Tóth Attila" wrote: |
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>>> 2014.Június 7.(Szo) 23:22 időpontban Alex Efros ezt írta: |
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>>>> Some time ago I noticed this in kernel logs: |
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>>>> kern.alert: grsec: denied RWX mmap of <anonymous mapping> by |
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>>>> /usr/lib64/python-exec/python2.7/layman[layman:9717] uid/euid:0/0 |
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>>>> gid/egid:0/0, parent /bin/bash[sh:9695] uid/euid:0/0 gid/egid:0/0 |
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>>>> |
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>>>> Looks like it doesn't break layman, but I still wonder why it happens |
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>>>> and |
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>>>> is it possible to fix this (without paxmarking python, of course)? |
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>>> |
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>>> I don't see this in my logs. The python executable has the "E" flag on |
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>>> my |
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>>> systems. |
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>>> |
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>>> Dw. |
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>>> |
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>> |
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>> Okay I need to document this loudly --- not sure how to do that except |
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>> to just keep repeating it until it becomes public knowledge: |
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>> |
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>> When running with a pax kernel, you must enable EMUTRAMP in your Kconfig |
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>> and you must paxmark your python exe's with E. Note: EMUTRAMP is on by |
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>> default and the ebuild automatically does the markings for you, so leave |
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>> the defaults alone. |
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>> |
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>> If you don't, python apps will hit rwx mmap denials by the pax kernel. |
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>> Things like libffi try to work around this by spitting out little |
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>> snippets of code to the filesystem when the mmap fails; but, if you have |
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>> strict TPE on, even this workaround fails and you get a pretty dead |
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>> system (all python apps badly crippled). There are various ways around |
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>> this but we've settled on the EMUTRAMP solution. See |
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> |
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> I see a problem here, that Alex has python binaries installed on his |
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> system with inconsistent PAX markings (PT: e, XATTR: E). I don't know his |
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> kernel config, but in my experience these flags can get misinterpreted |
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> instead of taking the XATTR:E flag or the default EMUTRAMP enabled. |
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> Despite it is not advised to keep both PT and XATTR markings on a system |
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> at the same time, some users may still have both and run into problems |
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> like Alex. |
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> I introduced kinda chpax init style logic as a workaround on my systems to |
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> double check sensitive binaries have correct PAX markings. |
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> Can we expect these symptoms to go away by the advent of the new hardened |
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> install helper? |
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> |
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> BR: Dw. |
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> |
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|
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Remember that the kernel decides what markings to look at. So if you |
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have XATTR_PAX enabled in the kernel, that's what it will look at and it |
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will ignore the other markings. In userland, the safest thing to do so |
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far is to enable both XATTR and PT markings in make.conf using |
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PAX_MARKINGS="XT PT". This will make sure the eclass does both markings. |
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|
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I've been slow (ie stuck) on how portage does wrapping but finally |
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figured out the issues. Today hopefully I'll have install-xattr wrapper |
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working with portage. Then its a matter of politicking it into portage. |
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At that point we will have end-to-end xattr support in portage and |
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people should be able to run a pure XATTR system. |
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|
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-- |
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Anthony G. Basile, Ph. D. |
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Chair of Information Technology |
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D'Youville College |
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Buffalo, NY 14201 |
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(716) 829-8197 |
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