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Date:      Tue, 03 May 2005 04:10:18 -0700
From:      Colin Percival <cperciva@freebsd.org>
To:        Danny Braniss <danny@cs.huji.ac.il>
Cc:        current@freebsd.org
Subject:   Re: MNT_USER?
Message-ID:  <42775C1A.2080400@freebsd.org>
In-Reply-To: <E1DSv8D-000EwW-37@cs1.cs.huji.ac.il>
References:  <E1DSv8D-000EwW-37@cs1.cs.huji.ac.il>

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Danny Braniss wrote:
> BTW, this, the MNT_NOEXEC, uncovered, IMHO, a bug in libexec/rtld-elf/rtld.c
> where it's now checking for MNT_NOEXEC, but only if LD_LIBRARY_PATH is set!

This is not a bug.  Checking for MNT_NOEXEC adds a cost in performance, and
it is not necessary if LD_LIBRARY_PATH, LD_PRELOAD, and LD_LIBMAP* are not
set -- based on the assumption, that is, that no (sane) sysadmin would ever
put a MNT_NOEXEC-mounted filesystem into the default library path.

I agree that it's a bit counter-intuitive, but it's really just a case of
saving time by not checking for something which should Never Happen. :-)

Colin Percival
PS. Bravo to Ian for tracking down the bug in NFS -- I spent a while looking
for this, but got hopelessly lost.



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