From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59501) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z4Y5V-0002GX-JX for qemu-devel@nongnu.org; Mon, 15 Jun 2015 13:22:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Z4Y5R-0000Li-AQ for qemu-devel@nongnu.org; Mon, 15 Jun 2015 13:22:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39854) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z4Y5R-0000LE-5o for qemu-devel@nongnu.org; Mon, 15 Jun 2015 13:22:17 -0400 From: Andrea Arcangeli Date: Mon, 15 Jun 2015 19:22:05 +0200 Message-Id: <1434388931-24487-2-git-send-email-aarcange@redhat.com> In-Reply-To: <1434388931-24487-1-git-send-email-aarcange@redhat.com> References: <1434388931-24487-1-git-send-email-aarcange@redhat.com> Subject: [Qemu-devel] [PATCH 1/7] userfaultfd: require UFFDIO_API before other ioctls List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, qemu-devel@nongnu.org, kvm@vger.kernel.org Cc: zhang.zhanghailiang@huawei.com, Pavel Emelyanov , Johannes Weiner , Hugh Dickins , "Dr. David Alan Gilbert" , Sanidhya Kashyap , Dave Hansen , Andres Lagar-Cavilla , Mel Gorman , Paolo Bonzini , "Kirill A. Shutemov" , "Huangpeng (Peter)" , Andy Lutomirski , Linus Torvalds , Peter Feiner UFFDIO_API was already forced before read/poll could work. This makes the code more strict to force it also for all other ioctls. All users would already have been required to call UFFDIO_API before invoking other ioctls but this makes it more explicit. This will ensure we can change all ioctls (all but UFFDIO_API/struct uffdio_api) with a bump of uffdio_api.api. There's no actual plan or need to change the API or the ioctl, the current API already should cover fine even the non cooperative usage, but this is just for the longer term future just in case. Signed-off-by: Andrea Arcangeli --- fs/userfaultfd.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 5f11678..b69d236 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -1115,6 +1115,12 @@ static long userfaultfd_ioctl(struct file *file, unsigned cmd, int ret = -EINVAL; struct userfaultfd_ctx *ctx = file->private_data; + if (cmd != UFFDIO_API) { + if (ctx->state == UFFD_STATE_WAIT_API) + return -EINVAL; + BUG_ON(ctx->state != UFFD_STATE_RUNNING); + } + switch(cmd) { case UFFDIO_API: ret = userfaultfd_api(ctx, arg);