Date: Mon, 15 Jan 2007 17:47:11 -0800 From: Colin Percival <cperciva@freebsd.org> To: Dirk Engling <erdgeist@erdgeist.org> Cc: freebsd-security@freebsd.org, Pawel Jakub Dawidek <pjd@freebsd.org> Subject: Re: HEADS UP: Re: FreeBSD Security Advisory FreeBSD-SA-07:01.jail Message-ID: <45AC2E9F.20901@freebsd.org> In-Reply-To: <45AC29EA.70009@erdgeist.org> References: <200701111841.l0BIfWOn015231@freefall.freebsd.org> <45A6DB76.40800@freebsd.org> <20070113112937.GI90718@garage.freebsd.pl> <45ABDC7C.6060407@erdgeist.org> <20070115210826.GA2839@garage.freebsd.pl> <45ABEEEE.4030609@erdgeist.org> <20070115220039.GB2839@garage.freebsd.pl> <45AC29EA.70009@erdgeist.org>
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Dirk Engling wrote:
> Please try the "cp -f" before guessing, what it might do ;)
>
> cp -f removes anything on that location before relinking the new file.
> Atomically.
No. `cp -f` unlinks the existing file and creates a new file, but will
still follow a symlink if one is created between the "unlink" syscall and
the "open" syscall.
/* remove existing destination file name,
* create a new file */
(void)unlink(to.p_path);
if (!lflag)
to_fd = open(to.p_path, O_WRONLY | O_TRUNC | O_CREAT,
fs->st_mode & ~(S_ISUID | S_ISGID));
Colin Percival
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