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Received: from [127.0.0.2] (localhost [127.0.0.1]) by hr2.samba.org with esmtpsa (TLS1.3:ECDHE_SECP256R1__ECDSA_SECP256R1_SHA256__CHACHA20_POLY1305:256) (Exim) id 1vxEKT-00000009ghv-2Ieg; Tue, 03 Mar 2026 01:13:41 +0000 Message-ID: <901186d6-ade6-4949-9a1e-773c082cc5cf@samba.org> Date: Mon, 2 Mar 2026 17:13:22 -0800 Precedence: bulk X-Mailing-List: linux-cifs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [Samba] SMB3 Unix Extensions - creating special files To: samba@lists.samba.org, linux-cifs@vger.kernel.org References: <1124e7cd-6a46-40a6-9f44-b7664a66654b@ed.ac.uk> <7082aea3-b28b-4ef5-9b5c-64d5d8b78cbc@samba.org> <45403dd0-b481-431b-8641-234978e48b1b@samba.org> <4d0f156024f06daf3e0c3794c3fed854@manguebit.org> <0e9ebf38-6aa6-4498-a2cc-726b9c84aa4f@ed.ac.uk> <1ee7cccb5fc35163cd8d0ed7777b37c0@manguebit.org> <63195a70-5978-4389-8016-6f2591d262d6@math.lsu.edu> Content-Language: en-US From: Jeremy Allison Autocrypt: addr=jra@samba.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 3/2/26 4:41 PM, Nikkos Svoboda via samba wrote: > >   Jumping in here briefly, I believe the "default" symlink style > requested by the client mount options is now "symlink=native", which > creates the 0-sized files with extended attributes on the server. > >   I'd also like to know:  Is it intended to allow creation of "actual" > symlinks on a supported server filesystem via unix 3.1.1 Extensions? The > mount option "symlink=unix" (which creates "actual" symlinks on the > server), when used with SMB 3.1.1 unix extensions, causes symlink > creation to fail on the client with "Operation not supported" (client > kernel 6.17, ubuntu 24.04). That mount option appears to be referred to > as "SMB1 unix create symlink command" which I presume means it is > limited to the SMB1 unix extensions. > >   The archived e-mail conversation chain here (though it includes some > outdated information) helped me to understand some of what the symlink= > and reparse= mount options were intended for: > https://lwn.net/ml/all/20241007183650.aw3skuztljpgk2bs@pali/ The goal (at least when I was involved with this effort) was to explicitly *ban* SMB3 UNIX extensions ever from creating server-side symlinks. Such activities are inherently unsafe and a source of many, many CVE's.