| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <7e91bea34552472757a8eec425d1d10643ca584b.camel@sipsolutions.net>
Date: Tue, 25 Feb 2025 13:24:49 +0100
From: Benjamin Berg <benjamin@...solutions.net>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: "jeffxu@...omium.org" <jeffxu@...omium.org>, "Jason@...c4.com"
<Jason@...c4.com>, "adobriyan@...il.com" <adobriyan@...il.com>,
"deller@....de" <deller@....de>, "gerg@...nel.org" <gerg@...nel.org>,
"anna-maria@...utronix.de" <anna-maria@...utronix.de>,
"davem@...emloft.net" <davem@...emloft.net>, "avagin@...il.com"
<avagin@...il.com>, "mhocko@...e.com" <mhocko@...e.com>, "enh@...gle.com"
<enh@...gle.com>, "thomas.weissschuh@...utronix.de"
<thomas.weissschuh@...utronix.de>, "hch@....de" <hch@....de>,
"hca@...ux.ibm.com" <hca@...ux.ibm.com>, "peterz@...radead.org"
<peterz@...radead.org>, "adhemerval.zanella@...aro.org"
<adhemerval.zanella@...aro.org>, "linux-kernel@...r.kernel.org"
<linux-kernel@...r.kernel.org>, "ojeda@...nel.org" <ojeda@...nel.org>,
"jannh@...gle.com" <jannh@...gle.com>, "f.fainelli@...il.com"
<f.fainelli@...il.com>, "sroettger@...gle.com" <sroettger@...gle.com>,
"ardb@...gle.com" <ardb@...gle.com>, "jorgelo@...omium.org"
<jorgelo@...omium.org>, "rdunlap@...radead.org" <rdunlap@...radead.org>,
"mark.rutland@....com" <mark.rutland@....com>, "Liam.Howlett@...cle.com"
<Liam.Howlett@...cle.com>, "vbabka@...e.cz" <vbabka@...e.cz>,
"mpe@...erman.id.au" <mpe@...erman.id.au>, "oleg@...hat.com"
<oleg@...hat.com>, "willy@...radead.org" <willy@...radead.org>,
"keescook@...omium.org" <keescook@...omium.org>, "peterx@...hat.com"
<peterx@...hat.com>, "mike.rapoport@...il.com" <mike.rapoport@...il.com>,
"mingo@...nel.org" <mingo@...nel.org>, "rientjes@...gle.com"
<rientjes@...gle.com>, "groeck@...omium.org" <groeck@...omium.org>,
"linus.walleij@...aro.org" <linus.walleij@...aro.org>,
"pedro.falcato@...il.com" <pedro.falcato@...il.com>, "ardb@...nel.org"
<ardb@...nel.org>, "42.hyeyoo@...il.com" <42.hyeyoo@...il.com>,
"linux-mm@...ck.org" <linux-mm@...ck.org>, "johannes@...solutions.net"
<johannes@...solutions.net>, "linux-hardening@...r.kernel.org"
<linux-hardening@...r.kernel.org>, "torvalds@...ux-foundation.org"
<torvalds@...ux-foundation.org>, "akpm@...ux-foundation.org"
<akpm@...ux-foundation.org>, "dave.hansen@...ux.intel.com"
<dave.hansen@...ux.intel.com>, "aleksandr.mikhalitsyn@...onical.com"
<aleksandr.mikhalitsyn@...onical.com>
Subject: Re: [PATCH v7 5/7] mseal, system mappings: enable uml architecture
Hi,
On Tue, 2025-02-25 at 10:37 +0000, Lorenzo Stoakes wrote:
> On Tue, Feb 25, 2025 at 08:45:21AM +0000, Berg, Benjamin wrote:
> > Hi,
> >
> > On Tue, 2025-02-25 at 06:22 +0000, Lorenzo Stoakes wrote:
> > > On Mon, Feb 24, 2025 at 10:52:44PM +0000, jeffxu@...omium.org wrote:
> > > > From: Jeff Xu <jeffxu@...omium.org>
> > > >
> > > > Provide support for CONFIG_MSEAL_SYSTEM_MAPPINGS on UML, covering
> > > > the vdso.
> > > >
> > > > Testing passes on UML.
> > >
> > > Maybe expand on this by stating that it has been confirmed by Benjamin (I
> > > _believe_) that UML has no need for problematic relocation so this is known to
> > > be good.
> >
> > I may well be misreading this message, but this sounds to me that this
> > is a misinterpretation. So, just to clarify in case that is needed.
> >
> > CONFIG_MSEAL_SYSTEM_MAPPINGS does work fine for the UML kernel.
> > However, the UML kernel is a normal userspace application itself and
> > for this application to run, the host kernel must have the feature
> > disabled.
> >
> > So, UML supports the feature. But it still *cannot* run on a host
> > machine that has the feature enabled.
>
> Sigh ok. Apologies if I misunderstood.
>
> Is there any point having this for the 'guest' system? I mean security wise are
> we concerned about sealing of system mappings?
>
> I feel like having this here might just add confusion and churn if it's not
> useful.
>
> If this is useless for UML guest, let's just drop this patch.
I figured it is not a lot of churn and there isn't really any cost to
enabling the feature.
That said, the only possible real-life use case I can see is doing MM
subsystem testing using UML. We certainly do not need the feature to
run our UML based wireless stack and driver tests.
Benjamin
>
> >
> > Benjamin
> >
> > >
> > > >
> > > > Signed-off-by: Jeff Xu <jeffxu@...omium.org>
> > > > Tested-by: Benjamin Berg <benjamin.berg@...el.com>
> > >
> > > Anyway I know UML has at any rate been confirmed to be good to go +
> > > patch looks
> > > fine, so:
> > >
> > > Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
>
> OK guess drop this tag please until we can figure this out, sorry Jeff.
>
> > >
> > > > ---
> > > > arch/um/Kconfig | 1 +
> > > > arch/x86/um/vdso/vma.c | 6 ++++--
> > > > 2 files changed, 5 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/arch/um/Kconfig b/arch/um/Kconfig
> > > > index 18051b1cfce0..eb2d439a5334 100644
> > > > --- a/arch/um/Kconfig
> > > > +++ b/arch/um/Kconfig
> > > > @@ -10,6 +10,7 @@ config UML
> > > > select ARCH_HAS_FORTIFY_SOURCE
> > > > select ARCH_HAS_GCOV_PROFILE_ALL
> > > > select ARCH_HAS_KCOV
> > > > + select ARCH_HAS_MSEAL_SYSTEM_MAPPINGS
> > > > select ARCH_HAS_STRNCPY_FROM_USER
> > > > select ARCH_HAS_STRNLEN_USER
> > > > select HAVE_ARCH_AUDITSYSCALL
> > > > diff --git a/arch/x86/um/vdso/vma.c b/arch/x86/um/vdso/vma.c
> > > > index f238f7b33cdd..fdfba858ffc9 100644
> > > > --- a/arch/x86/um/vdso/vma.c
> > > > +++ b/arch/x86/um/vdso/vma.c
> > > > @@ -54,6 +54,7 @@ int arch_setup_additional_pages(struct
> > > > linux_binprm *bprm, int uses_interp)
> > > > {
> > > > struct vm_area_struct *vma;
> > > > struct mm_struct *mm = current->mm;
> > > > + unsigned long vm_flags;
> > > > static struct vm_special_mapping vdso_mapping = {
> > > > .name = "[vdso]",
> > > > };
> > > > @@ -65,9 +66,10 @@ int arch_setup_additional_pages(struct
> > > > linux_binprm *bprm, int uses_interp)
> > > > return -EINTR;
> > > >
> > > > vdso_mapping.pages = vdsop;
> > > > + vm_flags =
> > > > VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC;
> > > > + vm_flags |= VM_SEALED_SYSMAP;
> > > > vma = _install_special_mapping(mm, um_vdso_addr,
> > > > PAGE_SIZE,
> > > > - VM_READ|VM_EXEC|
> > > > - VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
> > > > + vm_flags,
> > > > &vdso_mapping);
> > > >
> > > > mmap_write_unlock(mm);
> > > > --
> > > > 2.48.1.658.g4767266eb4-goog
> > > >
> >
> > Intel Deutschland GmbH
> > Registered Address: Am Campeon 10, 85579 Neubiberg, Germany
> > Tel: +49 89 99 8853-0, www.intel.de
> > Managing Directors: Sean Fennelly, Jeffrey Schneiderman, Tiffany Doon Silva
> > Chairperson of the Supervisory Board: Nicole Lau
> > Registered Office: Munich
> > Commercial Register: Amtsgericht Muenchen HRB 186928
Powered by blists - more mailing lists