Messages in this thread | | | From | "Albert D. Cahalan" <> | Subject | Re: caps in elf, next itteration (the hack get's bigger) | Date | Fri, 9 Apr 1999 19:23:36 -0400 (EDT) |
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Ulrich Drepper writes:
> I've not seen this patch but I've seen a bit of the old patches. I've > a big problem with changing the signalture (the first four bytes). > This should not be done and definitely is completely unnecessary.
The need: No existing kernel can run the executable.
> What should be done instead is registering an OS ABI and an ABI > version. The draft for the ELF standard revision defines bytes 7 and > 8 of the ELF header for this purpose. This information is as easy to > read the the signature in the first four bytes.
Great, but only if existing kernels check the version. If not, there would be a huge security hole.
I expect that the header must be mangled, unless you have some other way to stop old (unpatched) kernels from running the executable.
> So, any solution should there be implemented as follows: > > - register ELFOSABI_LINUX > > I could probably do this if it's wanted
As you may have guessed (by the tack-it-on-the-end hack), ELF format knowledge is surprisingly hard to find. Help is welcome. I and several other people will be abusing the format this weekend.
Q: What is the easiest way to modify an ELF section, adding it if it does not already exist? Are there naming or ordering rules?
> For more information see the ELF draft or elf.h in glibc 2.1.
I hope that is on the web somewhere.
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