Jim,
Your assumption that the same file descriptor is being re-opened is
wrong!
The file descriptor retrieved via /proc is a new one. It is not the
same as the
initial read-only.
Do a strace on your test and you will see that the 'file descriptor'
in /proc
will be accessed as an
Jim,
Sorry, but your 'prove' below is wrong!
You are opening the locked down file as root and passing that
fd as input to the nobody process.
So nobody is not opening /dir/file.txt (he can't because he hasn't
access to it via /dir) but root is...
Therefor the write to the fd is failing,
Pavel,
Proc does not need to be fixed, because /proc is referring to a file
inode.
And due to the fact that it's being presented in /proc as an fd, you
treat it
as an fd, therefor your expectations do not match.
Your assumptions is; because you accessed the world writable file via
a
...
Best regards,
Marco
On 27 okt 2009, at 13:56, p...@maths.usyd.edu.au wrote:
Marco Verschuur ma...@osp.nl wrote:
And due to the actual file permissions the read-only fd can easily
changed to read-write.
How would you do that? Cannot use fcntl() as that would not let you.
Cheers, Paul
Why not?!?
File permissions allow everybody write access to the file.
The path via /proc to the file has been created when the initial path
via /tmp was wide open.
Closing the initial path via /tmp has no effect on the /proc path
And due to the actual file permissions the read-only fd can
