From: Peter Xu <peterx@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Hugh Dickins <hughd@google.com>,
Luis Chamberlain <mcgrof@kernel.org>,
Maxime Coquelin <maxime.coquelin@redhat.com>,
kvm@vger.kernel.org, Jerome Glisse <jglisse@redhat.com>,
Pavel Emelyanov <xemul@virtuozzo.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Martin Cracauer <cracauer@cons.org>,
Denis Plotnikov <dplotnikov@virtuozzo.com>,
linux-mm@kvack.org, Marty McFadden <mcfadden8@llnl.gov>,
Maya Gokhale <gokhale2@llnl.gov>,
Mike Kravetz <mike.kravetz@oracle.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
Kees Cook <keescook@chromium.org>, Mel Gorman <mgorman@suse.de>,
"Kirill A . Shutemov" <kirill@shutemov.name>,
linux-fsdevel@vger.kernel.org,
"Dr . David Alan Gilbert" <dgilbert@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 3/3] userfaultfd: apply unprivileged_userfaultfd check
Date: Mon, 11 Mar 2019 17:58:40 +0800 [thread overview]
Message-ID: <20190311095840.GA14108@xz-x1> (raw)
In-Reply-To: <20190311093701.15734-4-peterx@redhat.com>
On Mon, Mar 11, 2019 at 05:37:01PM +0800, Peter Xu wrote:
> Apply the unprivileged_userfaultfd check when doing userfaultfd
> syscall. We didn't check it in other paths of userfaultfd (e.g., the
> ioctl() path) because we don't want to drag down the fast path of
> userfaultfd, as suggested by Andrea.
>
> Suggested-by: Andrea Arcangeli <aarcange@redhat.com>
> Suggested-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
> fs/userfaultfd.c | 25 +++++++++++++++++++++++++
> 1 file changed, 25 insertions(+)
>
> diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
> index c2188464555a..effdcfc88629 100644
> --- a/fs/userfaultfd.c
> +++ b/fs/userfaultfd.c
> @@ -951,6 +951,28 @@ void userfaultfd_unmap_complete(struct mm_struct *mm, struct list_head *uf)
> }
> }
>
> +/* Whether current process allows to use userfaultfd syscalls */
> +static bool userfaultfd_allowed(void)
> +{
> + bool allowed = false;
> +
> + switch (unprivileged_userfaultfd) {
> + case UFFD_UNPRIV_ENABLED:
> + allowed = true;
> + break;
> + case UFFD_UNPRIV_KVM:
> + allowed = !!test_bit(MMF_USERFAULTFD_ALLOW,
> + ¤t->mm->flags);
> + /* Fall through */
Sorry I should squash this in otherwise compilation of !CONFIG_KVM
will break:
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index effdcfc88629..1b3fa5935643 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -960,10 +960,12 @@ static bool userfaultfd_allowed(void)
case UFFD_UNPRIV_ENABLED:
allowed = true;
break;
+#if IS_ENABLED(CONFIG_KVM)
case UFFD_UNPRIV_KVM:
allowed = !!test_bit(MMF_USERFAULTFD_ALLOW,
¤t->mm->flags);
/* Fall through */
+#endif
case UFFD_UNPRIV_DISABLED:
allowed = allowed || ns_capable(current_user_ns(),
CAP_SYS_PTRACE);
Will wait for more comments before I repost. Sorry for the noise.
Regards,
--
Peter Xu
next prev parent reply other threads:[~2019-03-11 9:58 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-11 9:36 [PATCH 0/3] userfaultfd: allow to forbid unprivileged users Peter Xu
2019-03-11 9:36 ` [PATCH 1/3] userfaultfd/sysctl: introduce unprivileged_userfaultfd Peter Xu
2019-03-12 6:58 ` Mike Rapoport
2019-03-12 12:26 ` Peter Xu
2019-03-12 13:53 ` Mike Rapoport
2019-03-11 9:37 ` [PATCH 2/3] kvm/mm: introduce MMF_USERFAULTFD_ALLOW flag Peter Xu
2019-03-11 9:37 ` [PATCH 3/3] userfaultfd: apply unprivileged_userfaultfd check Peter Xu
2019-03-11 9:58 ` Peter Xu [this message]
2019-03-12 7:01 ` [PATCH 0/3] userfaultfd: allow to forbid unprivileged users Mike Rapoport
2019-03-12 12:29 ` Peter Xu
2019-03-12 7:49 ` Kirill A. Shutemov
2019-03-12 12:43 ` Peter Xu
2019-03-12 19:59 ` Mike Kravetz
2019-03-13 6:00 ` Peter Xu
2019-03-13 8:22 ` Paolo Bonzini
2019-03-13 18:52 ` Andrea Arcangeli
2019-03-13 19:12 ` Paolo Bonzini
2019-03-13 23:44 ` Andrea Arcangeli
2019-03-14 10:58 ` Paolo Bonzini
2019-03-14 15:23 ` Alexei Starovoitov
2019-03-14 16:00 ` Paolo Bonzini
2019-03-14 16:16 ` Andrea Arcangeli
2019-03-15 16:09 ` Kees Cook
2019-03-13 20:01 ` Mike Kravetz
2019-03-13 23:55 ` Andrea Arcangeli
2019-03-14 3:32 ` Mike Kravetz
2019-03-13 17:50 ` Mike Kravetz
2019-03-15 8:26 ` Peter Xu
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