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From: sm2@sequent.cc.hull.ac.uk (Simon Marshall)
Newsgroups: comp.emacs
Subject: Emacs Auto-Save Security
Keywords: Key, Quay, Qui
Message-ID: <11564.9105201105@seq.hull.ac.uk>
Date: 20 May 91 11:05:26 GMT
Sender: usenet@ucbvax.BERKELEY.EDU
Lines: 31


	For Emacs 18.55.2 (and 18.51.15).  This may have been changed in
     later versions, and is not really a bug - it just maybe that it never
     occurred to anyone before...

	When Emacs auto-saves a buffer visiting a file (using a different
     name), it uses the value of the file creation mask (typically given
     by "umask" on Unix) for the auto-save file's permission bits, not the
     permission bits of the file that the buffer is visiting.

	Assuming that you're not the type who has umask 077 as the first
     line in your ~/.cshrc file (but do those sort of people refuse to use
     Emacs on principle anyway? ;-), and have something like umask 022,
     any file you edit using Emacs which you have chosen to restrict
     access to in some way is effectively unrestricted once an auto-save
     is done.  If root uses Emacs to edit an access-restricted file, s/he
     better beware...

	Auto-saving is done on some buffers that are not visiting a file
     (*mail* being one such example), so it cannot get permission bits
     that way.  Also, you may tell Emacs to auto-save under the same name
     anyway.  However, when using a different name, it would be safer to
     use the visited file's permission bits if the buffer is visiting one,
     or a more cautious value.  Are there any patches for this?

	Simon.
_______________________________________________________________________________
Simon Marshall, Dept. of Computer Science, University of Hull, Hull HU6 7RX, UK
	      "``La la la la la la la la la'' means I love you."
	EMAIL:	S.Marshall@Hull.ac.uk		UUCP:	..!ukc!hu-cs!sm
    Telephone:	+44 482 465951 (office)		 Fax:	+44 482 466666