From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Subject: Re: max symlink = 5? ?bug? ?feature deficit? Date: Sun, 12 Feb 2006 12:36:37 -0700 Message-ID: <20060212193637.GI12822@parisc-linux.org> References: <43ED5A7B.7040908@tlinx.org> <20060212180601.GU27946@ftp.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Linda Walsh , Linux-Kernel , linux-fsdevel@vger.kernel.org Return-path: Received: from palinux.external.hp.com ([192.25.206.14]:7583 "EHLO palinux.hppa") by vger.kernel.org with ESMTP id S1751434AbWBLTgi (ORCPT ); Sun, 12 Feb 2006 14:36:38 -0500 To: Al Viro Content-Disposition: inline In-Reply-To: <20060212180601.GU27946@ftp.linux.org.uk> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Sun, Feb 12, 2006 at 06:06:01PM +0000, Al Viro wrote: > On Fri, Feb 10, 2006 at 07:31:07PM -0800, Linda Walsh wrote: > > The maximum number of followed symlinks seems to be set to 5. > > > > This seems small when compared to other filesystem limits. > > Is there some objection to it being raised? Should it be > > something like Glib's '20' or '255'? Just a note (which Al probably considered too obvious to point out), but MAX_NESTED_LINKS isn't the maximum number of followed symlinks. It's the number of recursions we're limited to. The maximum number of symlinks followed is 40 (see fs/namei.c:do_follow_link). Al, would it be worth making 40 an enumerated constant in the same enumeration as MAX_NESTED_LINKS? Something like this: Index: include/linux/namei.h =================================================================== RCS file: /var/cvs/linux-2.6/include/linux/namei.h,v retrieving revision 1.4 diff -u -p -r1.4 namei.h --- include/linux/namei.h 12 Nov 2005 04:09:17 -0000 1.4 +++ include/linux/namei.h 12 Feb 2006 19:35:31 -0000 @@ -11,7 +11,10 @@ struct open_intent { struct file *file; }; -enum { MAX_NESTED_LINKS = 5 }; +enum { + MAX_NESTED_LINKS = 5, + MAX_FOLLOW_SYMLINKS = 40, +}; struct nameidata { struct dentry *dentry; Index: fs/namei.c =================================================================== RCS file: /var/cvs/linux-2.6/fs/namei.c,v retrieving revision 1.31 diff -u -p -r1.31 namei.c --- fs/namei.c 12 Nov 2005 04:08:32 -0000 1.31 +++ fs/namei.c 12 Feb 2006 19:35:31 -0000 @@ -598,7 +598,7 @@ static inline int do_follow_link(struct int err = -ELOOP; if (current->link_count >= MAX_NESTED_LINKS) goto loop; - if (current->total_link_count >= 40) + if (current->total_link_count >= MAX_FOLLOW_SYMLINKS) goto loop; BUG_ON(nd->depth >= MAX_NESTED_LINKS); cond_resched();