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Made binfmt only handle v1 FatElf binaries. |
M3Henry
commented
Oct 12, 2024
| if(MEMFD) | ||
| add_fatelf_executable(fatelf-exec) | ||
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| find_program(BINFMT systemd-binfmt PATHS /usr/lib/systemd) |
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I'm on the fence as to whether /usr/lib ought to be replaced with ${CMAKE_INSTALL_FULL_LIBDIR}.
M3Henry
commented
Oct 12, 2024
Add the ability to execute fatelf binaries from a memfd with fatelf-exec. It reads its own ELF header via /proc/self/exe to determine the target. Use systemd-binfmt to tell the kernel to execute FatElf with fatelf-exec. Future improvements: * Read into a mmap of the memfd. * Be aware of non-exact record matches which are compatible with the OS. e.g. Linux x86 & x32 binaries can run on x86_64. * Compile time knowledge of current architecture to avoid /proc/self/exe. * OpenBSD support may be possible with shm_mkstemp. * Defer to other binfmt handlers?
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Thanks for your work coming up with a sensible spec. I stumbled across
systemd-binfmtrecently and remembered FatElf.As it stands,
fatelf-execcopies the contained ELF into an anonymous memory backed file and executes it. This works for statically linked binaries and dynamically linked binaries that are linked to normal ELF dynamic libraries.For the use case of FatElf dynamic libraries, this does not provide a solution, though it could be possible in theory to shim
ld-linux.sosomehow.It turns out there is demand for this sort of thing. Though it seems one only gets support when done with clever tricks: APE