Change loader for programs

[Emmanuel QUEMENER <emmanuel.quemener@free.fr>]

Hello world,

I would like to ask a rookie question about the possibility to reassign
by substitution a new loader (/lib/ld-linux.so.2 or alike) to each program.

In fact, I know that it's possible to launch it for example echo by
using /new/path/lib/ld-2.3.2 /new/path/bin/echo but I would like to do
it without specifiing boot loader.

I've investigate in elf tools and I've found objdump and objcopy.

I discover by objdump that the loader is specified in .interp section.
So I try the following commands

cd /tmp
objcopy --remove-section=.interp /bin/echo /tmp/echo
echo -n "/lib/ld-linux.so.2" > foo
objcopy --add-section .interp=foo /tmp/echo /tmp/echo.new

and, unfortunately:

./echo.new
bash: ./echo.new: cannot execute binary file

With objdump, here are my output :

$ objdump -Sl -j .interp /tmp/echo.new

/tmp/echo.new:     format de fichier elf32-i386

Déassemblage de la section .interp:

00000000 <opterr-0x804c460>:
   0:   2f                      das
   1:   6c                      insb   (%dx),%es:(%edi)
   2:   69 62 2f 6c 64 2d 6c    imul   $0x6c2d646c,0x2f(%edx),%esp
   9:   69 6e 75 78 2e 73 6f    imul   $0x6f732e78,0x75(%esi),%ebp
  10:   2e                      cs
  11:   32                      .byte 0x32

$ objdump -Sl -j .interp /bin/echo

/bin/echo:     format de fichier elf32-i386

Déassemblage de la section .interp:

08048114 <.interp>:
 8048114:       2f                      das
 8048115:       6c                      insb   (%dx),%es:(%edi)
 8048116:       69 62 2f 6c 64 2d 6c    imul   $0x6c2d646c,0x2f(%edx),%esp
 804811d:       69 6e 75 78 2e 73 6f    imul   $0x6f732e78,0x75(%esi),%ebp
 8048124:       2e 32 00                xor    %cs:(%eax),%al

This changing loader property would help me to have an operational
Debian system on a user (non chroot account).

Thanks for answer

EQ