add missing method to_linux_x86_elf_dll

[qdbp]

I was using msfvenom as follows:
msfvenom -a x86 --platform linux -f elf-so -p linux/x86/adduser
It failed with:

Error: undefined method `to_linux_x86_elf_dll' for Msf::Util::EXE:Class
Did you mean?  to_linux_x64_elf_dll
               to_linux_x86_elf

It looked like the formulaic method definition for to_linux_x86_elf_dll was missing, even though the template file template_x86_linux_dll.bin was there. Therefore, I added the method.

Verification

After this change, the command above seems to produce a valid ELF-32 shared object.

• Start msfconsole
• Start msfvenom -a x86 --platform linux -f elf-so -p linux/x86/adduser
• Verify the thing does what it should

[timwr]

Great fix! Many thanks.

$ msfvenom -f elf-so -p linux/x86/exec CMD="echo so" -o elf.so
No platform was selected, choosing Msf::Module::Platform::Linux from the payload
No Arch selected, selecting Arch: x86 from the payload
No encoder or badchars specified, outputting raw payload
Payload size: 43 bytes
Final size of elf-so file: 289 bytes
Saved as: elf.so
$ LD_PRELOAD=$(realpath elf.so) ./elf-Linux-x86-bash
so

[timwr]

Release Notes

This fix resolves an issue with Linux x86 elf shared object generation.