Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751825Ab3JGEj0 (ORCPT ); Mon, 7 Oct 2013 00:39:26 -0400 Received: from static.92.5.9.176.clients.your-server.de ([176.9.5.92]:42175 "EHLO hallynmail2" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751683Ab3JGEjY (ORCPT ); Mon, 7 Oct 2013 00:39:24 -0400 Date: Mon, 7 Oct 2013 04:39:19 +0000 From: "Serge E. Hallyn" To: "Eric W. Biederman" Cc: Miklos Szeredi , "Serge E. Hallyn" , Al Viro , Linux-Fsdevel , Kernel Mailing List , Andy Lutomirski , Rob Landley , Linus Torvalds Subject: Re: [RFC][PATCH 4/3] vfs: Allow rmdir to remove mounts in all but the current mount namespace Message-ID: <20131007043919.GB10284@mail.hallyn.com> References: <87a9kkax0j.fsf@xmission.com> <8761v7h2pt.fsf@tw-ebiederman.twitter.com> <87li281wx6.fsf_-_@xmission.com> <87a9ioo37a.fsf_-_@xmission.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87a9ioo37a.fsf_-_@xmission.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2176 Lines: 71 Quoting Eric W. Biederman (ebiederm@xmission.com): > > Programs have been known to test for empty directories by attempting > to remove them. To keep from violating the principle of least > surprise don't let directories the caller can see with someting > mounted on them be deleted. Do you think we should do the same thing for over-mounted file at vfs_unlink()? > With a little luck this may prevent commands stupid commands > like rm -rf from eating your system. > > Signed-off-by: "Eric W. Biederman" > --- > fs/namei.c | 21 +++++++++++++++++++++ > 1 files changed, 21 insertions(+), 0 deletions(-) > > diff --git a/fs/namei.c b/fs/namei.c > index b18b017c946b..b9cae480ac27 100644 > --- a/fs/namei.c > +++ b/fs/namei.c > @@ -3547,6 +3547,20 @@ void dentry_unhash(struct dentry *dentry) > spin_unlock(&dentry->d_lock); > } > > +static bool covered(struct vfsmount *mnt, struct dentry *dentry) > +{ > + /* test to see if a dentry is covered with a mount in > + * the current mount namespace. > + */ > + bool is_covered; > + > + rcu_read_lock(); > + is_covered = d_mountpoint(dentry) && __lookup_mnt(mnt, dentry, 1); > + rcu_read_unlock(); > + > + return is_covered; > +} > + > int vfs_rmdir(struct inode *dir, struct dentry *dentry) > { > int error = may_delete(dir, dentry, 1); > @@ -3619,6 +3633,9 @@ retry: > error = -ENOENT; > goto exit3; > } > + error = -EBUSY; > + if (covered(nd.path.mnt, dentry)) > + goto exit3; > error = security_path_rmdir(&nd.path, dentry); > if (error) > goto exit3; > @@ -4155,6 +4172,10 @@ retry: > error = -ENOTEMPTY; > if (new_dentry == trap) > goto exit5; > + error = -EBUSY; > + if (new_dentry->d_inode && S_ISDIR(new_dentry->d_inode->i_mode) && > + covered(newnd.path.mnt, new_dentry)) > + goto exit5; > > error = security_path_rename(&oldnd.path, old_dentry, > &newnd.path, new_dentry); > -- > 1.7.5.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/