libvirt users - Jan 2022 - Failed in using LD_PRELOAD to hook mmap system call in qemu(through libvirt)

Dear sir: 
    I want to hook mmap system call in qemu, and I use libvirt
to passthrough the environment argument like
this:<qemu:commandline&gt;   <qemu:env name='LD_PRELOAD'
value='/glibcHookMMAP.so'/&gt;
</qemu:commandline&gt;&nbsp; &nbsp; But it failed. I can hardly
find out what is the matter! The log in libvirt like this:ERROR: ld.so: object
'/glibcHookMMAP.so' from LD_PRELOAD cannot be preloaded (cannot open
shared object file): ignored.&nbsp; &nbsp; Firstly, I think it's the
problem of authority. But the file glibcHookMMAP.so has been done with command
`chmod 777`.&nbsp; &nbsp; My environment is as follows:&nbsp;Ubuntu
18.04.2 Linux 5.4.0-92&nbsp;libvirt 4.0.0&nbsp;qemu 2.11.1
&nbsp; &nbsp;&nbsp;Look forward to your feedbacks.




&nbsp; &nbsp; Sincerely yours
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On Thu, Jan 06, 2022 at 07:44:25PM +0800, Xiong? wrote:
> Dear sir: 
>     I want to hook mmap system call in qemu, and I use
> libvirt to passthrough the environment argument like this:
>  <qemu:commandline>
>    <qemu:env name='LD_PRELOAD'
value='/glibcHookMMAP.so'/>
>  </qemu:commandline>
> But it failed. I can hardly find out what is the matter!
> The log in libvirt like this:ERROR: ld.so: object
> '/glibcHookMMAP.so' from LD_PRELOAD cannot be preloaded
> (cannot open shared object file): ignored.    Firstly,
> I think it's the problem of authority. But the file
> glibcHookMMAP.so has been done with command `chmod 777`.
> My environment is as follows: Ubuntu 18.04.2 Linux
> 5.4.0-92 libvirt 4.0.0 qemu 2.11.1
Aside from normal file permissions, the other likely problem on Ubuntu
will be AppArmor policy. It likely won't allow QEMU to load files from
the / directory - if you put your .so in /usr/local/lib it might
work.



Regards,
Daniel
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