From mboxrd@z Thu Jan 1 00:00:00 1970 From: OGAWA Hirofumi Subject: Re: [patch 12/12] vfs: allow file truncations when both suid and write permissions set Date: Fri, 07 Aug 2009 20:02:14 +0900 Message-ID: <87prb7sx8p.fsf@devron.myhome.or.jp> References: <200908062310.n76NAIEo013014@imap1.linux-foundation.org> <87ocqs2w17.fsf@devron.myhome.or.jp> <4A7B9DC5.7080700@redhat.com> <871vno1cn7.fsf@devron.myhome.or.jp> <4A7BF394.8010302@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: akpm@linux-foundation.org, viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, eparis@redhat.com, esandeen@redhat.com, eteo@redhat.com To: Amerigo Wang Return-path: Received: from mail.parknet.ad.jp ([210.171.162.6]:43178 "EHLO mail.officemail.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757491AbZHGLCS (ORCPT ); Fri, 7 Aug 2009 07:02:18 -0400 In-Reply-To: <4A7BF394.8010302@redhat.com> (Amerigo Wang's message of "Fri, 07 Aug 2009 17:27:48 +0800") Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Amerigo Wang writes: >> static int selinux_inode_setattr(struct dentry *dentry, struct iattr *iattr) >> { >> const struct cred *cred = current_cred(); >> >> if (iattr->ia_valid & ATTR_FORCE) >> return 0; >> >> if (iattr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | >> ATTR_ATIME_SET | ATTR_MTIME_SET)) >> return dentry_has_perm(cred, NULL, dentry, FILE__SETATTR); >> >> return dentry_has_perm(cred, NULL, dentry, FILE__WRITE); >> } >> >> I guess it's assuming the ia_valid doesn't have (ATTR_MODE | ATTR_SIZE), >> but truncate() already does it, I don't know whether it's ok. > > No, here we should only force ATTR_KILL_SUID and/or ATTR_KILL_SGID. > do_truncate() has ATTR_SIZE and ATTR_FILE. I guess security module should do, ia_valid = iattr->ia_valid; if (!(ia_valid & ATTR_FORCE) && (ia_valid & ATTR_FORCE_MASK)) { err = dentry_has_perm(cred, NULL, dentry, FILE__SETATTR); if (err) return err; ia_valid &= ~ATTR_FORCE_MASK; } if (ia_valid & ATTR_NOT_FORCE_MASK) err = dentry_has_perm(cred, NULL, dentry, FILE__WRITE); return err; or something. Because do_truncate() already do (ATTR_MODE | ATTR_SIZE) without ATTR_FORCE. Thanks. -- OGAWA Hirofumi