On Sat, 6 Jun 2020 at 20:32, Jakub Wilk <jwilk@xxxxxxxxx> wrote:
>
> * Jonny Grant <jg@xxxxxxxx>, 2020-06-06, 16:45:
> >>>3) Could i ask to clarify my understanding. For this "The binary
> >>>being executed by the process does not have read permission enabled."
> >>>-- is this when the binary permissions are changed after it starts
> >>>running?
> >>No, AFAICS the permission check is done when the process starts.
> >How can the process start if the binary file doesn't have read
> >permissions enabled?
>
> It's a bit weird, but the kernel doesn't mind:
>
> $ cp /bin/ls .
> $ chmod a-r ls
> $ ./ls -l ls
> --wx--x--x 1 jwilk jwilk 138856 Jun 6 20:22 ls
And from core(5):
There are various circumstances in which a core dump file is not
produced:
...
* The binary being executed by the process does not have read
permission enabled.
So, the binary can be executed, but not read, and will not do a core
dump (since that might be readable).
Thanks,
Michael
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
