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([2620:10d:c092:600::1:558d]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-acb6ec42af6sm623375166b.43.2025.04.22.01.43.47 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 22 Apr 2025 01:43:48 -0700 (PDT) Message-ID: <484ecaad-56de-4c0d-b7fa-a3337557b0bf@gmail.com> Date: Tue, 22 Apr 2025 09:45:04 +0100 Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next v9 2/9] net: add get_netmem/put_netmem support To: Mina Almasry , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, io-uring@vger.kernel.org, virtualization@lists.linux.dev, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org Cc: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Donald Hunter , Jonathan Corbet , Andrew Lunn , Jeroen de Borst , Harshitha Ramamurthy , Kuniyuki Iwashima , Willem de Bruijn , Jens Axboe , David Ahern , Neal Cardwell , "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , =?UTF-8?Q?Eugenio_P=C3=A9rez?= , Stefan Hajnoczi , Stefano Garzarella , Shuah Khan , sdf@fomichev.me, dw@davidwei.uk, Jamal Hadi Salim , Victor Nogueira , Pedro Tammela , Samiullah Khawaja References: <20250417231540.2780723-1-almasrymina@google.com> <20250417231540.2780723-3-almasrymina@google.com> Content-Language: en-US From: Pavel Begunkov In-Reply-To: <20250417231540.2780723-3-almasrymina@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 4/18/25 00:15, Mina Almasry wrote: > Currently net_iovs support only pp ref counts, and do not support a > page ref equivalent. Makes me wonder why it's needed. In theory, nobody should ever be taking page references without going through struct ubuf_info handling first, all in kernel users of these pages should always be paired with ubuf_info, as it's user memory, it's not stable, and without ubuf_info the user is allowed to overwrite it. Maybe there are some gray area cases like packet inspection or tracing? However in this case, after the ubuf_info is dropped, the user can overwrite the memory with its secrets. Definitely iffy in security terms. -- Pavel Begunkov