Date: Tue, 16 Jan 2007 03:17:10 +0100 From: Dirk Engling <erdgeist@erdgeist.org> To: Colin Percival <cperciva@freebsd.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: <45AC35A6.7090103@erdgeist.org> In-Reply-To: <45AC2E9F.20901@freebsd.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> <45AC2E9F.20901@freebsd.org>
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Colin Percival wrote: > 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)); You are right. Atomically in binary is not atomical enough. mv in its rename()-form will do the job, so we need to create a file in . by mktemp and mv it to the real name when filled. Regards erdgeist -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.3 (Darwin) iD8DBQFFrDWmImmQdUyYEgkRAgSgAJ0c5mcaM4LByBUE0LC1Iqdj8ZFSAACdF9qM fFETX4I+Fvue0u+343bBG8c= =MkSh -----END PGP SIGNATURE-----
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