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dkim=pass header.d=paul-moore-com.20210112.gappssmtp.com header.s=20210112 header.b="FGMgDJ/U"; spf=none (imf10.hostedemail.com: domain of paul@paul-moore.com has no SPF policy when checking 209.85.221.42) smtp.mailfrom=paul@paul-moore.com; dmarc=none X-Rspamd-Server: rspam02 X-Rspam-User: X-Stat-Signature: kwdgq9e1pgsa9tma5eqynwhgbi6y1bk3 X-HE-Tag: 1657660617-447053 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Jul 12, 2022 at 10:22 AM Peter Xu wrote: > On Fri, Jul 08, 2022 at 11:34:51AM +0200, Ondrej Mosnacek wrote: > > Since userfaultfd doesn't implement a write operation, it is more > > appropriate to open it read-only. > > > > When userfaultfds are opened read-write like it is now, and such fd is > > passed from one process to another, SELinux will check both read and > > write permissions for the target process, even though it can't actually > > do any write operation on the fd later. > > > > Inspired by the following bug report, which has hit the SELinux scenario > > described above: > > https://bugzilla.redhat.com/show_bug.cgi?id=1974559 > > > > Reported-by: Robert O'Callahan > > Fixes: 86039bd3b4e6 ("userfaultfd: add new syscall to provide memory externalization") > > Signed-off-by: Ondrej Mosnacek > > Acked-by: Peter Xu Thanks Peter. -- paul-moore.com