From owner-freebsd-questions Wed May 23 14:40:38 2001 Delivered-To: freebsd-questions@freebsd.org Received: from pemaquid.safeport.com (pemaquid.safeport.com [204.156.12.58]) by hub.freebsd.org (Postfix) with ESMTP id 286F437B423 for ; Wed, 23 May 2001 14:40:34 -0700 (PDT) (envelope-from doug@safeport.com) Received: from localhost (doug@localhost) by pemaquid.safeport.com (8.11.1/8.11.1) with ESMTP id f4NLeK306694 for ; Wed, 23 May 2001 17:40:21 -0400 (EDT) (envelope-from doug@safeport.com) X-Authentication-Warning: pemaquid.safeport.com: doug owned process doing -bs Date: Wed, 23 May 2001 17:40:20 -0400 (EDT) From: To: freebsd-questions@FreeBSD.ORG Subject: /dev/io: Operation not permitted Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG I have a 4.3 system where root can not write to /dev/io. I assume I have screwed something up but I am told the permissions: crw------- 1 root wheel 2, 14 May 9 19:56 /dev/io are okay and indeed matches my other systems. The man page io(4) would suggest this is hard to do: DESCRIPTION The special file /dev/io is a controlled security hole that allows a pro- cess to gain I/O privileges (which are normally reserved for kernel- internal code). Any process that holds a file descriptor on /dev/io open will get its IOPL bits in the flag register set, thus allowing it to per- form direct I/O operations. This can be useful in order to write user- land programs that handle some hardware directly. The entire access control is handled by the file access permissions of /dev/io, so care should be taken in granting rights for this device. Note that even read/only access will grant the full I/O privileges. However: Last login: Tue May 22 18:21:34 2001 from pemaquid.boltsys Copyright (c) 1980, 1983, 1986, 1988, 1990, 1991, 1993, 1994 The Regents of the University of California. All rights reserved. FreeBSD 4.3-RELEASE (GENERIC) #0: Sat Apr 21 10:54:49 GMT 2001 Welcome to FreeBSD! mneme:~> su Password: mneme:/home/doug# echo "poo I say" > /dev/io /dev/io: Operation not permitted. __________________________________________ The reason I care is XFree86 -configure fail with the same error. This system was installed from ftp.freebsd.org on 5/20 _____ Douglas Denault doug@safeport.com Voice: 301-469-8766 Fax: 301-469-0601 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message