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Hermes SMTP Server) with ESMTPA ID b52a058941d94202e488719cef4d9678; Thu, 22 Oct 2026 17:00:19 +0000 (UTC) Message-ID: <018ca365-ce9b-424c-b600-bd9c8aefc9a1@schaufler-ca.com> Date: Thu, 22 Oct 2026 10:00:16 -0700 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v2 00/41] UUID and GUID user and group ids (*_r system calls) To: Jan Koester , Christian Brauner , Alexander Viro , "Serge E. Hallyn" Cc: Jan Kara , "Theodore Y. Ts'o" , Paul Moore , Arnd Bergmann , linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-security-module@vger.kernel.org, linux-arch@vger.kernel.org, linux-ext4@vger.kernel.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, netdev@vger.kernel.org, audit@vger.kernel.org, keyrings@vger.kernel.org, linux-kernel@vger.kernel.org, Casey Schaufler References: Content-Language: en-US From: Casey Schaufler In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Mailer: WebService/1.1.26740 mail.backend.jedi.jws.acl:role.jedi.acl.token.atz.jws.hermes.yahoo On 10/20/2026 8:15 PM, Jan Koester wrote: > Hi, > > this RFC series lets a user or group id be a UUID (RFC 9562, version 4) > or a Microsoft GUID as well as a classic 32-bit number. Processes can run > as such a user, files can be owned by one, and credentials, ACLs, keys, > System V IPC, sockets, signals, audit and procfs carry the whole id. I can't see this being acceptable for a variety of reasons, including but not limited to performance and configuration complexity. It's a general solution for a special case or two, and the impact is significant. If you're willing to use a UUID and/or GUID in addition to a UID/GID instead of in place of it you could consider implementing this as an LSM. There are a number of issues you'd still run into there (e.g. UDS attributes) and I can't say if the resulting behavior would be what you're looking for. I also can't say that the security community would necessarily be any happier with it than the general population, but if you really want this it might be worth a shot.