[PATCH 0/3] elf: load the main program from AT_EXECFD

[Florian Weimer]

* Christian Brauner:

>> What does /proc/self/exe look like for such processes?  Does GDB work?
>> There are two cases to consider: launching with GDB, and attaching GDB
>> to a running process with the -p option.
>
> Right, I checked that.
>
> /proc/self/exe is ld.so. The kernel exec'd ld.so, so it names ld.so
> whether the program arrived via AT_EXECFD, via --program-fd, or via a
> plain "ld.so PROG" command line.

Yeah, and that causes problems with binaries that try to be relocatable.
We don't have a very convenient way to get the correct path in those
scenarios, so a lot of code uses /proc/self/exe instead.

I'm wondering if we can use the checkpoint-restore facilities (the
restore parts) to fix this: load ld.so another time, transfer control to
it, and instruct it to unmap the first copy and then invoke the
necessary prctls to make the process look exactly like a directly
invoked process.

Thanks,
Florian