Date: Thu, 25 Apr 1996 07:13:55 -0400 From: "Frank E. Terhaar-Yonkers" <fty@mcnc.org> To: bde@zeta.org.au, sos@FreeBSD.org Cc: current@FreeBSD.org, freebsd-current@FreeBSD.org Subject: Re: minor syscons bogon Message-ID: <199604251113.HAA02980@robin.mcnc.org.mcnc.org>
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Does anything actually use this kludge? Like, how would an application even know that /dev/ttyv[MAXCONS] == /dev/console ? This is very ugly. - Frank >> >> if (unit == MAXCONS) >> >> return CONSOLE_TTY; > >Note that (unit == MAXCONS) case is handled 2 lines after the patched >line, and this handling is always a no-op if the patch is applied. Thus >the patch is at best incomplete. > >There are certainly some bugs here. If /dev/ttyvn exists for n = >MAXCONS, then /dev/ttyvn is more or less an alias for /dev/console. >This causes security holes if /dev/ttyvn has weaker ownership or >permissions than /dev/console. Opening and closing /dev/ttyvn messes up >last-close stuff for /dev/console (e.g., last-closing /dev/ttyvn nukes >the console tty's pgrp and session pointers). > >The problem is easy to work around: don't create /dev/ttyvn for n = >MAXCONS. I consider requiring this to be acceptable, although the bug >is in the kernel. Root should be very careful about the ownerships, >permissions and existence of all devices. There are many similar kernel >bugs, because many drivers don't fully decode the minor number. E.g., >the vn driver with slices disabled only decodes 5 unit bits, so there >are 2^27 aliases for each device, 13 of which are created by `sh MAKEDEV >vn0'. > >Bruce > \\\\////\\\\////\\\\\////\\\\\////\\\\////\\\\////\\\\////\\\\////\\\\////\\\\ Frank Terhaar-Yonkers, Manager High Performance Computing and Communications Research MCNC PO Box 12889 3021 Cornwallis Road Research Triangle Park, North Carolina 27709-2889 fty@mcnc.org voice (919)248-1417 FAX (919)248-1455 http://www.mcnc.org/hpcc.html
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