linux-kernel - Re: Is PIE randomization breaking klibc binaries?

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Date:	Tue, 24 Jul 2007 16:57:33 -0400
From:	Chuck Ebbert <cebbert@...hat.com>
To:	Chuck Ebbert <cebbert@...hat.com>
CC:	"H. Peter Anvin" <hpa@...or.com>,
	Ulrich Kunitz <kune@...ne-taler.de>,
	linux-kernel@...r.kernel.org, honza@...os.cz, jkosina@...e.cz
Subject: Re: Is PIE randomization breaking klibc binaries?

On 07/24/2007 04:34 PM, Chuck Ebbert wrote:
> On 07/20/2007 06:05 PM, H. Peter Anvin wrote:
>>> It looks like that the PIE randomization patch breaks klibc
>>> binaries on x86-64.
>>>
>> Interesting.
>>
>> klibc binaries are indeed statically linked, but composed of two
>> different ELF images: the application itself and the shared libary
>> (which is referenced from the application header as the "interpreter").
>>  Neither of these is an ET_DYN file; they are both ET_EXEC, so it
>> *should* be unaffected by the PIE randomization patch.  Obviously, that
>> seems to not be the case.
>>
>> My guess is that this patch mishandles interpreter images which are
>> ET_EXEC.  Jan, any insight?
> 
> Well, they don't run on Fedora 6 either (which has the same code, it's
> part of exec-shield):
> 
> $ strace ./cat
> execve("./cat", ["./cat"], [/* 55 vars */]) = -1 ENOENT (No such file or directory)
> ...
> $ file cat
> cat: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), statically linked (uses shared libs), stripped
> 
> Funny nobody noticed that before...
> 

After installing klibc.so and klibc-<ID>.so into /lib everything works:

Program Headers:
  Type           Offset   VirtAddr   PhysAddr   FileSiz  MemSiz   Flg Align
  PHDR           0x000034 0x08048034 0x08048034 0x0000a0 0x0000a0 R E 0x4
  INTERP         0x0000d4 0x080480d4 0x080480d4 0x00002a 0x00002a R   0x1
        [Requesting program interpreter: /lib/klibc-58kBUyV_qhVvkMnaxy8A7N8rLak.so]

Ulrich, did your initrd contain the correct .so? Did you try rebuilding klibc after
building the new kernel?
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