Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762152AbZJOCW2 (ORCPT ); Wed, 14 Oct 2009 22:22:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761862AbZJOCW1 (ORCPT ); Wed, 14 Oct 2009 22:22:27 -0400 Received: from mail-iw0-f180.google.com ([209.85.223.180]:55344 "EHLO mail-iw0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760893AbZJOCWZ convert rfc822-to-8bit (ORCPT ); Wed, 14 Oct 2009 22:22:25 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=twaijerjoq9xcPShnFWWd4mzsxP+x9bYTF/TIQFyBF1CPr5RJ9LePIEGS4GNXgDmiv sn8ndDnHfHZU/4kFCaM2GUZVD5pLeHq0yJ+ZjDfqt2Z07VUzmVRHb8JMz70xSSwTwGPR RJpo7jrmMdZy4EDFgvdKhKbQqoO+m2gNymmR0= MIME-Version: 1.0 In-Reply-To: <18475.1255529305@redhat.com> References: <1255516134-4838-1-git-send-email-graff.yang@gmail.com> <18475.1255529305@redhat.com> Date: Thu, 15 Oct 2009 10:21:49 +0800 Message-ID: <7d86d44a0910141921j28ddc50cxb2d9386c5ad99db9@mail.gmail.com> Subject: Re: [PATCH] mm/nommu.c: Fix improperly call of security API in mmap From: graff yang To: David Howells Cc: linux-kernel@vger.kernel.org, gyang@blackfin.uclinux.org, akpm@linux-foundation.org, uclinux-dist-devel@blackfin.uclinux.org, Graff Yang , linux-security-module@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4438 Lines: 117 Hi, David, Thanks your patch, I will test it. On Wed, Oct 14, 2009 at 10:08 PM, David Howells wrote: > wrote: > >> The original code calling security_file_mmap() use user's hint address >> as it's 5th argument(addr). This is improper, as the hint address may be >> NULL. >> In this case, the security_file_mmap() may incorrectly return -EPERM. >> >> This patch moved the calling of security_file_mmap() out of >> validate_mmap_request() to do_mmap_pgoff(), and call this >> security API with the address that attempting to mmap. > > I think this is the wrong approach.  Firstly, the hint is cleared in NOMMU > mode, and secondly, I think that the check against the minimum LSM address is > pointless in NOMMU mode too. > > So I think the attached patch is a better approach. > > David > --- > From: David Howells > > NOMMU: Ignore the address parameter in the file_mmap() security check > > Ignore the address parameter in the various file_mmap() security checks when > CONFIG_MMU=n as the address hint is ignored under those circumstances, and in > any case the minimum mapping address check is pointless in NOMMU mode. > > Signed-off-by: David Howells > --- > >  include/linux/security.h |    1 + >  mm/nommu.c               |    2 +- >  security/commoncap.c     |    2 ++ >  security/selinux/hooks.c |    2 ++ >  4 files changed, 6 insertions(+), 1 deletions(-) > > > diff --git a/include/linux/security.h b/include/linux/security.h > index 239e40d..0583f16 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -593,6 +593,7 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts) >  *     @reqprot contains the protection requested by the application. >  *     @prot contains the protection that will be applied by the kernel. >  *     @flags contains the operational flags. > + *     @addr contains the mapping address, and should be ignored in NOMMU mode. >  *     Return 0 if permission is granted. >  * @file_mprotect: >  *     Check permissions before changing memory access permissions. > diff --git a/mm/nommu.c b/mm/nommu.c > index 3c3b4b2..cfea46c 100644 > --- a/mm/nommu.c > +++ b/mm/nommu.c > @@ -974,7 +974,7 @@ static int validate_mmap_request(struct file *file, >        } > >        /* allow the security API to have its say */ > -       ret = security_file_mmap(file, reqprot, prot, flags, addr, 0); > +       ret = security_file_mmap(file, reqprot, prot, flags, 0, 0); >        if (ret < 0) >                return ret; > > diff --git a/security/commoncap.c b/security/commoncap.c > index fe30751..ac1f745 100644 > --- a/security/commoncap.c > +++ b/security/commoncap.c > @@ -1005,6 +1005,7 @@ int cap_file_mmap(struct file *file, unsigned long reqprot, >  { >        int ret = 0; > > +#ifdef CONFIG_MMU >        if (addr < dac_mmap_min_addr) { >                ret = cap_capable(current, current_cred(), CAP_SYS_RAWIO, >                                  SECURITY_CAP_AUDIT); > @@ -1012,5 +1013,6 @@ int cap_file_mmap(struct file *file, unsigned long reqprot, >                if (ret == 0) >                        current->flags |= PF_SUPERPRIV; >        } > +#endif >        return ret; >  } > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c > index bb230d5..93d61f8 100644 > --- a/security/selinux/hooks.c > +++ b/security/selinux/hooks.c > @@ -3046,6 +3046,7 @@ static int selinux_file_mmap(struct file *file, unsigned long reqprot, >                             unsigned long addr, unsigned long addr_only) >  { >        int rc = 0; > +#ifdef CONFIG_MMU >        u32 sid = current_sid(); > >        /* > @@ -3060,6 +3061,7 @@ static int selinux_file_mmap(struct file *file, unsigned long reqprot, >                if (rc) >                        return rc; >        } > +#endif > >        /* do DAC check on address space usage */ >        rc = cap_file_mmap(file, reqprot, prot, flags, addr, addr_only); > -- -Graff -- 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/