From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 616BB763EF for ; Thu, 8 Feb 2024 13:55:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707400514; cv=none; b=hLG0mnlbaTE8ebuiqATwdgBm7/E+U1+RIzMh9tMSCHxsudF9iG9xioFZxFGVrmyxwo8rmNAhFwrPVooTqSJqWI+rFiMlAkb+xOpGxLi/LflzPizm0vk0tK77GbLtr0xH0heUi1IqG3TIjWEmGRfIwOuRl04Keqy68YtflinBxr0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707400514; c=relaxed/simple; bh=eBOpj9vr+ze6ckMI+1qnwlUv9z5G8N5Eo92iW2xOv04=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ewqn34X8L7FXQmoSLEiY0Iv4okuFAj+N68/EknyXGJnVEv2CitlfQUHsX3gOHQdmRDM/t8ypsBffklz4El1v3PvCuiAlz3KqzNp5kBe8fsLLKaYgSVVv7A1yt0AIXXKMwzndgeZjBjldcrN1GEY1vahcwfvt8AuRJ+8/crK8C4o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=bNn39s19; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="bNn39s19" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1707400510; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=/fcEFVTR0rsXTj+Grlw2xqYc8J4he9PWeVGkbhbY1/Q=; b=bNn39s19j2a+J156nRCkJ+ocxuXh6wEja8IIxklRUP2mX6fH0+rQw/BUftwS3nmaYw86RJ 4vwKpz9atUbTXrwmrA6i0Q1v10C62KYfXTg4V09VtZ4Cqwk36bm3DkBcVfUJXKam+tYYfB recHLQDTnl2j23DQHoDL8TjvDP8jBg0= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-177-PD0hYRglPcifZwAOdlIWrQ-1; Thu, 08 Feb 2024 08:55:03 -0500 X-MC-Unique: PD0hYRglPcifZwAOdlIWrQ-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 19F061C09839; Thu, 8 Feb 2024 13:55:03 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.224.158]) by smtp.corp.redhat.com (Postfix) with SMTP id A1D01492BC7; Thu, 8 Feb 2024 13:55:01 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Thu, 8 Feb 2024 14:53:47 +0100 (CET) Date: Thu, 8 Feb 2024 14:53:45 +0100 From: Oleg Nesterov To: Christian Brauner Cc: Andy Lutomirski , "Eric W. Biederman" , Tycho Andersen , linux-api@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] pidfd: change pidfd_send_signal() to respect PIDFD_THREAD Message-ID: <20240208135344.GD19801@redhat.com> References: <20240207114549.GA12697@redhat.com> <20240208-fragt-prospekt-7866333b15f0@brauner> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240208-fragt-prospekt-7866333b15f0@brauner> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.9 On 02/08, Christian Brauner wrote: > > On Wed, Feb 07, 2024 at 12:45:49PM +0100, Oleg Nesterov wrote: > > + type = (f.file->f_flags & PIDFD_THREAD) ? PIDTYPE_PID : PIDTYPE_TGID; > > + ret = kill_pid_info_type(sig, &kinfo, pid, type); > > If the user doesn't provide siginfo then the kernel fills in the info in > prepare_kill_siginfo() a few lines above. That sets info->si_code to > SI_USER even for the PIDFD_THREAD case. Whenever the info is filled in > by the kernel it's not exactly userspace impersonating anything plus we > know that what we're sending to is a pidfd by the type of the pidfd. So > it feels like we should fill in SI_TKILL here as well? Hmm. Agreed, will do, thanks. But then I think this needs another preparational 1/2 patch. prepare_kill_siginfo() should have a new arg so that do_tkill() could use it too. (offtopic, but may be the "Only allow sending arbitrary signals to yourself" check in pidfd_send_signal() needs another helper, do_rt_sigqueueinfo() does the same check). > I would also suggest we update the obsolete comment on top of > pidfd_send_signal() along the lines of: Ah, indeed, thanks. Oleg.