Date: Mon, 27 Mar 2000 14:17:52 -0700 From: Warner Losh <imp@village.org> To: David Malone <dwmalone@maths.tcd.ie> Cc: hackers@FreeBSD.ORG, des@FreeBSD.ORG, pb@FreeBSD.ORG Subject: Re: Linprocfs observation. Message-ID: <200003272117.OAA99918@harmony.village.org> In-Reply-To: Your message of "Mon, 27 Mar 2000 21:01:19 %2B0100." <200003272101.aa58489@salmon.maths.tcd.ie> References: <200003272101.aa58489@salmon.maths.tcd.ie>
next in thread | previous in thread | raw e-mail | index | archive | help
In message <200003272101.aa58489@salmon.maths.tcd.ie> David Malone writes: : The "file" file was removed from FreeBSD's /proc code (in 4.0 and : 5.0) because of this, but it is probably important for Linux : emulation so it can't really be removed from the linprocfs code. : I guess this probably warrants at least a note in the man page. File was removed because it was a huge, gaping security hole. It was effectively hard link to the file in question and circumvented some of the usual security protections that the file would otherwise be protected by. : Linux itself is not subject to this problem because it's exe file : is a synthetic symlink pointing to the executable, not something : which returns the executables actual vnode. And that's why it is still in the tree. A symbolic link doesn't have the security issues that the hard link has. : Also, on Linux the : symlink is only readable by the process' owner. This suggests the : following possible work around: : 1) Add a directory /linproc/pid/private which is only : executable and readable by the process' owner. : 2) Make the "exe" file in /linproc/pid/ a symlink to : "./private/exe", which is the file which gives : you the executables real vnode. : I think this will give the same behavior as the Linux procfs, and : expose less suid stuff. It would be necessary to do something very : like this if we ever have to implement /linproc/pid/fd/xx. Why bother? No body should be using file/exe at all. It is a useless misfeature. What actually uses it? Warner To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200003272117.OAA99918>