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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Kuniyuki Iwashima , Willem de Bruijn , metze@samba.org, axboe@kernel.dk, Stanislav Fomichev , io-uring@vger.kernel.org, bpf@vger.kernel.org, netdev@vger.kernel.org, Linus Torvalds , linux-kernel@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH net-next v3 0/4] net: move .getsockopt away from __user buffers Message-ID: References: <20260408-getsockopt-v3-0-061bb9cb355d@debian.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260408-getsockopt-v3-0-061bb9cb355d@debian.org> On 04/08, Breno Leitao wrote: > Currently, the .getsockopt callback requires __user pointers: > > int (*getsockopt)(struct socket *sock, int level, > int optname, char __user *optval, int __user *optlen); > > This prevents kernel callers (io_uring, BPF) from using getsockopt on > levels other than SOL_SOCKET, since they pass kernel pointers. > > Following Linus' suggestion [0], this series introduces sockopt_t, a > type-safe wrapper around iov_iter, and a getsockopt_iter callback that > works with both user and kernel buffers. AF_PACKET and CAN raw are > converted as initial users, with selftests covering the trickiest > conversion patterns. > > [0] https://lore.kernel.org/all/CAHk-=whmzrO-BMU=uSVXbuoLi-3tJsO=0kHj1BCPBE3F2kVhTA@mail.gmail.com/ > > Updates from v2 to v3: > > * Use two iov in sockopt_t instead of a single one: > a) .iter_in that is populated by the caller and will be read-only in > the protocols callback. > > b) .iter_out will be populated by the protocol and it will be sent > back to the caller. > > - This will avoid changing the protocol reset and changing the data > source at the callback, making the driver callback implementation > and converstion saner. > > * created sockptr_to_sockopt() to convert sockptr to sockopt, making the > call to getsockopt_iter straight-forward > > Link: https://lore.kernel.org/all/CAHk-=whmzrO-BMU=uSVXbuoLi-3tJsO=0kHj1BCPBE3F2kVhTA@mail.gmail.com/ [0] > --- > Changes in v3: > - Create Two iov in sockopt_t instead of a single one (Stanislav Fomichev) > - Implement the sockptr_to_sockopt() helper (Stanislav Fomichev) > - Link to v2: https://patch.msgid.link/20260401-getsockopt-v2-0-611df6771aff@debian.org > > Changes in v2: > - Restore optlen even on error path (getsockopt_iter fails) > - Move af_packet.c and can instead of netlink (given these are the most > complicate ones). > - Link to v1: https://patch.msgid.link/20260130-getsockopt-v1-0-9154fcff6f95@debian.org LGTM! Not sure what's your plan for the selftest? You wanna keep it outside or maybe repost v4 with it? Acked-by: Stanislav Fomichev I'm also not sure your unconditional 'copy-optlen-back' will work for every proto, but I think we can put something into sockopt_t to make it avoid the copy if needed in the future.