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From: Dan_Jacobson@ATT.COM
Newsgroups: comp.emacs,alt.security
Subject: Re: Emacs Auto-Save Security
Message-ID: <1991May22.011248.13542@cbfsb.att.com>
Date: 22 May 91 01:12:48 GMT
References: <11564.9105201105@seq.hull.ac.uk>
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In-Reply-To: sm2@sequent.cc.hull.ac.uk's message of 20 May 91 11: 05:26 GMT
Originator: danj1@cbnewsf.cb.att.com

>>>>> On 20 May 91 11:05:26 GMT, sm2@sequent.cc.hull.ac.uk (Simon Marshall) said:

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

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

Simon> 	Auto-saving is done on some buffers that are not visiting a
Simon> file (*mail* being one such example), so it cannot get
Simon> permission bits that way.

here's what i use for the mail buffers

(let ((tmp (expand-file-name "~/.mail/"))) ; .mail == 700 mode
  (if (file-directory-p tmp)
      (setq vm-folder-directory tmp)
    (setq vm-folder-directory (expand-file-name "~/"))))

(setq mail-archive-file-name (concat vm-folder-directory "outbox"))
(setq mail-mode-hook
      (function
       (lambda ()

;;;at last: can save the "*mail*" auto-save buffer in a protected
;;;directory, so I don't have to set a restrictive (077) umask.
;;;[idea is thanks to Kyle Jones]
;;;	       (and (string= buffer-auto-save-file-name
;;;			     (expand-file-name "~/#%*mail*#"))
		    (setq buffer-auto-save-file-name
			  (concat vm-folder-directory "#%*mail"
				  (int-to-string (random t)))
			  ;; VM5: "#_reply_to_Kyle_Jones#" still to long
			  ;; maybe "#-5421Kyle_Jones" is cooler
			  );)
		    )))
;;(I have a cron job regularly clean out any old mail backups that are
;;produced when i change my mind and dont send a e-mail)