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 D299B7869A for ; Fri, 16 Feb 2024 13:07:50 +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=1708088872; cv=none; b=oy6Uv/s5l4gtCH8XaMEE5YpLw5T6qsg/QFfb8ev4/LpxvdARJ+sS0ZAo9+V7ntyGA/k5lGZe1IYrg3yYplE74fthQp7xRQKNW7OlNOJvxaa6d5/0p+q4H6R37fW9jbGQ5SJ4b5mW6FKU9izsrxpkrs43Up2HFekStGAWIN6A3qo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708088872; c=relaxed/simple; bh=pPG3R/OErTmWA1YaPaPl80i0l8sVL+bI6w7kjgG1990=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=uGXmHHoUpVQl5jsb4G4gBggH07erwm2DJCWDXiXwMgFILbt7JNScZZmL0wLYHj/4ySOc8QG90JYWo0BX84TMeu+dfq3CcxIe0SAEvVi6xzOwBneL2c7TFVgNyFMsDxdcG8gZbQaM0qmjKz+KgYdCk6ShVLv51hnhx1PlQsvvINQ= 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=bA7+kPop; 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="bA7+kPop" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1708088869; 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=YEE5vefXCxxll9I1yPyvGhbZ4bDFBlmFBtJG7JnBVrQ=; b=bA7+kPopB/agPkcrEvITHQ3Gcm/ZySjM21suSDR71n8MKIGwuhXNLous5ZeKQYANJKfLth S+jedeY6OILV8Xwfgdf/HjacGU6cUQJd5n9EJ33nD19bAUPGgwfNfpoeebJ+Z3hLSK40Rb VR+gFJlS1Z+QZTjNOTYCdhEhYsbWOGo= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-21-S_YwwsXwMYGM4fFK26JqPw-1; Fri, 16 Feb 2024 08:07:46 -0500 X-MC-Unique: S_YwwsXwMYGM4fFK26JqPw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (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 0451685A589; Fri, 16 Feb 2024 13:07:46 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.226.116]) by smtp.corp.redhat.com (Postfix) with SMTP id 27FF52166AE5; Fri, 16 Feb 2024 13:07:43 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Fri, 16 Feb 2024 14:06:28 +0100 (CET) Date: Fri, 16 Feb 2024 14:06:25 +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 v2 2/2] pidfd: change pidfd_send_signal() to respect PIDFD_THREAD Message-ID: <20240216130625.GA8723@redhat.com> References: <20240209-radeln-untrennbar-9d4ae05aa4cc@brauner> <20240209155644.GD3282@redhat.com> <20240210-abfinden-beimessen-2dbfea59b0da@brauner> <20240210123033.GA27557@redhat.com> <20240210-dackel-getan-619c70fefa62@brauner> <20240210131518.GC27557@redhat.com> <20240210-chihuahua-hinzog-3945b6abd44a@brauner> <20240210165133.GD27557@redhat.com> <20240214123655.GB16265@redhat.com> <20240216-albern-aufwiegen-1de327c7dafd@brauner> Precedence: bulk X-Mailing-List: linux-api@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: <20240216-albern-aufwiegen-1de327c7dafd@brauner> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.6 On 02/16, Christian Brauner wrote: > > On Wed, Feb 14, 2024 at 01:36:56PM +0100, Oleg Nesterov wrote: > > > > and I am not sure that task_pid(current) == pid should allow > > the "arbitrary signals" if PIDFD_SIGNAL_PROCESS_GROUP. > > > > Perhaps > > > > /* Only allow sending arbitrary signals to yourself. */ > > ret = -EPERM; > > if ((task_pid(current) != pid || type == PIDTYPE_PGID) && > > (kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL) > > goto err; > > Honestly, we should probably just do: > > if (kinfo->si_code != SI_USER) > goto err Hmm. This doesn't look right. The purpose of the current check is to forbid SI_TKILL and si_code >= 0, and SI_USER == 0. SI_USER means that the target can trust the values of si_pid/si_uid in siginfo. > + if (kinfo.si_code != SI_USER) > goto err; See above... Oleg.