* Jamie Lokier: > I hope the above cannot convert O_NOACCESS to O_RDWR without checking > that you have access to the file. It doesn't. Here's what I did to reproduce: $ mkdir /tmp/xyz $ touch /tmp/xyz/123 $ tail -f /tmp/xyz/123 And in another terminal: $ chmod 000 /tmp/xyz $ echo foo > /tmp/xyz/123 bash: /tmp/xyz/123: Permission denied $ $ echo foo > /proc/$pid_of_tail/fd/5 And the first terminal prints "foo". It fails if the file it self is not writeable, only the access check on the path is bypassed. I still think this is wrong. FWIW, fcntl(F_SETFL) is documented to ignore O_RDWR etc. flags. For /proc/PID/fd, it probably makes sense to check the current access flags on the object, and the original open mode. Rechecking the path seems impossible because it has unclear semantics. The whole thing is a bit worrisome because it may turn file descriptor information leaks into something worse. -- Florian Weimer <fweimer@xxxxxx> BFK edv-consulting GmbH http://www.bfk.de/ Kriegsstraße 100 tel: +49-721-96201-1 D-76133 Karlsruhe fax: +49-721-96201-99 -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
