From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.hallyn.com (mail.hallyn.com [178.63.66.53]) (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 9B44D28373; Sun, 6 Apr 2025 14:23:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=178.63.66.53 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743949412; cv=none; b=p6kUpZbpTJXeiKiT4N6YjnZcGanMa0PQvpQ3WrJv7LNv+hHfFc000DQ67aL/mTpCowb74BwIO2pYJVNZl8j/hICmb572UykpWoZ9Dn0mU2vMGJFYxXUXjPK0BAaVgi+tiQhCjUPFHqmZ3qB4EVs30RFiFqMCEu+8b4papk9ZH2c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743949412; c=relaxed/simple; bh=Sugg6vXRZWEHMje5mnBq1cZ/jDPpChJwmNu+T5NdV1o=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=NPe0f96gHKmdb+Xc/opkf3MuZ/KQbff/9u/17nHjKzOzm5UgK2akU74mgUlLkpWKxRAgWmhNS3v9Mz7d8pOYHzMaD7LhfsR2vToRgduSS82fVaek4LcBCfisdkS1aWCLCvnNrGybjNCHqqn2r+HSibfiZDAI8SbnP7Ti3iYJOLg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=hallyn.com; spf=pass smtp.mailfrom=mail.hallyn.com; arc=none smtp.client-ip=178.63.66.53 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=hallyn.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mail.hallyn.com Received: by mail.hallyn.com (Postfix, from userid 1001) id E809EE01; Sun, 6 Apr 2025 09:15:01 -0500 (CDT) Date: Sun, 6 Apr 2025 09:15:01 -0500 From: "Serge E. Hallyn" To: Jason Gunthorpe Cc: Parav Pandit , "Eric W. Biederman" , "linux-rdma@vger.kernel.org" , "linux-security-module@vger.kernel.org" , "serge@hallyn.com" , Leon Romanovsky Subject: Re: [PATCH] RDMA/uverbs: Consider capability of the process that opens the file Message-ID: <20250406141501.GA481691@mail.hallyn.com> References: <20250313050832.113030-1-parav@nvidia.com> <20250317193148.GU9311@nvidia.com> <20250318112049.GC9311@nvidia.com> <87ldt2yur4.fsf@email.froward.int.ebiederm.org> <20250318225709.GC9311@nvidia.com> <20250404151347.GC1336818@nvidia.com> Precedence: bulk X-Mailing-List: linux-security-module@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: <20250404151347.GC1336818@nvidia.com> On Fri, Apr 04, 2025 at 12:13:47PM -0300, Jason Gunthorpe wrote: > On Fri, Apr 04, 2025 at 02:53:30PM +0000, Parav Pandit wrote: > > To summarize, > > > > 1. A process can open an RDMA resource (such as a raw QP, raw flow entry, or similar 'raw' resource) > > through the fd using ioctl(), if it has the appropriate capability, which in this case is CAP_NET_RAW. > > This is similar to a process that opens a raw socket. > > > > 2. Given that RDMA uses ioctl() for resource creation, there isn't a security concern surrounding > > the read()/write() system calls. > > > > 3. If process A, which does not have CAP_NET_RAW, passes the opened fd to another privileged > > process B, which has CAP_NET_RAW, process B can open the raw RDMA resource. > > This is still within the kernel-defined security boundary, similar to a raw socket. > > > > 4. If process A, which has the CAP_NET_RAW capability, passes the file descriptor to Process B, which does not have CAP_NET_RAW, Process B will not be able to open the raw RDMA resource. > > > > Do we agree on this Eric? > > This is our model, I consider it uAPI, so I don't belive we can change > it without an extreme reason.. > > > 5. the process's capability check should be done in the right user namespace. > > (instead of current in default user ns). > > The right user namespace is the one which created the net namespace. > > This is because rdma networking resources are governed by the net namespace. > > This all makes my head hurt. The right user namespace is the one that > is currently active for the invoking process, I couldn't understand > why we have net namespaces refer to user namespaces :\ A user at any time can create a new user namespace, without creating a new network namespace, and have privilege in that user namespace, over resources owned by the user namespace. So if a user can create a new user namespace, then say "hey I have CAP_NET_ADMIN over current_user_ns, so give me access to the RDMA resources belonging to my current_net_ns", that's a problem. So that's why the check should be ns_capable(device->net->user-ns, CAP_NET_ADMIN) and not ns_capable(current_user_ns, CAP_NET_ADMIN). -serge