How to hook bios function?!

How to hook bios function?!

[Navid Movahedi]

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Hi
Does grub2 have a mechanism to hook bios disk read function (int 0x13) and
replace it with a new function? if it is possible how can i do that and
which part of code is responsible for it?

Thanks

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Re: How to hook bios function?!

[Andrei Borzenkov]

On Tue, Feb 17, 2015 at 9:12 AM, Navid Movahedi <n.movahedi67@gmail.com> wrote:
> Hi
> Does grub2 have a mechanism to hook bios disk read function (int 0x13) and
> replace it with a new function? if it is possible how can i do that and
> which part of code is responsible for it?

I'm not aware of any generic code to install resident handler. Special
case is drivemap command which does exactly that. What exactly are you
trying to do?

Re: How to hook bios function?!

[Navid Movahedi]

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Thanks Andrei

I have systems with windows partition encrypted and i want to patch grub2
to boot windows from this partition. as you know in order to boot windows,
bootmgr and winload use int 0x13 to load windows kernel from disk, so i
need to hook interrupt 0x13 to decrypt disk on the fly.

Another question: After the bios hooking is done i need to do this process
for UEFI, Does grub2 support UEFI disk routines hooking? and How?

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Re: How to hook bios function?!

[Navid Movahedi]

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I found function grub_disk_read in include/grub/disk.h that is implemented
in grub-core/kern/disk.c . If i add my decryption algorithm to this
function, Does this modified function do the job after chainload to windows
boot manager?

On Tue, Feb 17, 2015 at 2:17 PM, Navid Movahedi <n.movahedi67@gmail.com>
wrote:

> Thanks Andrei
>
> I have systems with windows partition encrypted and i want to patch grub2
> to boot windows from this partition. as you know in order to boot windows,
> bootmgr and winload use int 0x13 to load windows kernel from disk, so i
> need to hook interrupt 0x13 to decrypt disk on the fly.
>
> Another question: After the bios hooking is done i need to do this process
> for UEFI, Does grub2 support UEFI disk routines hooking? and How?
>

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Re: How to hook bios function?!

[Vladimir 'phcoder' Serbinenko]

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No
Le 2015-02-17 12:15, "Navid Movahedi" <n.movahedi67@gmail.com> a écrit :
>
> I found function grub_disk_read in include/grub/disk.h that is
implemented in grub-core/kern/disk.c . If i add my decryption algorithm to
this function, Does this modified function do the job after chainload to
windows boot manager?
>
No
> On Tue, Feb 17, 2015 at 2:17 PM, Navid Movahedi <n.movahedi67@gmail.com>
wrote:
>>
>> Thanks Andrei
>>
>> I have systems with windows partition encrypted and i want to patch
grub2 to boot windows from this partition. as you know in order to boot
windows, bootmgr and winload use int 0x13 to load windows kernel from disk,
so i need to hook interrupt 0x13 to decrypt disk on the fly.
>>
Drivemap is a good example on achieving sth like this.
>> Another question: After the bios hooking is done i need to do this
process for UEFI, Does grub2 support UEFI disk routines hooking? and How?
>
Read EFI spec
>
>
> _______________________________________________
> Grub-devel mailing list
> Grub-devel@gnu.org
> https://lists.gnu.org/mailman/listinfo/grub-devel
>

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