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([2001:67c:2fbc:1:f55:fe70:5486:7392]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-aa50b2f0899sm16627766b.61.2024.11.21.13.35.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 21 Nov 2024 13:35:50 -0800 (PST) Message-ID: Date: Thu, 21 Nov 2024 22:36:19 +0100 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next v11 07/23] ovpn: introduce the ovpn_socket object To: Sergey Ryazanov Cc: Eric Dumazet , Jakub Kicinski , Paolo Abeni , Donald Hunter , Shuah Khan , sd@queasysnail.net, Andrew Lunn , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org References: <20241029-b4-ovpn-v11-0-de4698c73a25@openvpn.net> <20241029-b4-ovpn-v11-7-de4698c73a25@openvpn.net> <62d382f8-ea45-4157-b54b-8fed7bdafcca@gmail.com> <1dffb833-1688-4572-bbf8-c6524cd84402@openvpn.net> Content-Language: en-US From: Antonio Quartulli Autocrypt: addr=antonio@openvpn.net; keydata= xsFNBFN3k+ABEADEvXdJZVUfqxGOKByfkExNpKzFzAwHYjhOb3MTlzSLlVKLRIHxe/Etj13I X6tcViNYiIiJxmeHAH7FUj/yAISW56lynAEt7OdkGpZf3HGXRQz1Xi0PWuUINa4QW+ipaKmv voR4b1wZQ9cZ787KLmu10VF1duHW/IewDx9GUQIzChqQVI3lSHRCo90Z/NQ75ZL/rbR3UHB+ EWLIh8Lz1cdE47VaVyX6f0yr3Itx0ZuyIWPrctlHwV5bUdA4JnyY3QvJh4yJPYh9I69HZWsj qplU2WxEfM6+OlaM9iKOUhVxjpkFXheD57EGdVkuG0YhizVF4p9MKGB42D70pfS3EiYdTaKf WzbiFUunOHLJ4hyAi75d4ugxU02DsUjw/0t0kfHtj2V0x1169Hp/NTW1jkqgPWtIsjn+dkde dG9mXk5QrvbpihgpcmNbtloSdkRZ02lsxkUzpG8U64X8WK6LuRz7BZ7p5t/WzaR/hCdOiQCG RNup2UTNDrZpWxpwadXMnJsyJcVX4BAKaWGsm5IQyXXBUdguHVa7To/JIBlhjlKackKWoBnI Ojl8VQhVLcD551iJ61w4aQH6bHxdTjz65MT2OrW/mFZbtIwWSeif6axrYpVCyERIDEKrX5AV rOmGEaUGsCd16FueoaM2Hf96BH3SI3/q2w+g058RedLOZVZtyQARAQABzSdBbnRvbmlvIFF1 YXJ0dWxsaSA8YW50b25pb0BvcGVudnBuLm5ldD7Cwa0EEwEIAFcCGwMFCwkIBwMFFQoJCAsF FgIDAQACHgECF4AFCRWQ2TIWIQTKvaEoIBfCZyGYhcdI8My2j1nRTAUCYRUquBgYaGtwczov L2tleXMub3BlbnBncC5vcmcACgkQSPDMto9Z0UzmcxAAjzLeD47We0R4A/14oDKlZxXO0mKL fCzaWFsdhQCDhZkgxoHkYRektK2cEOh4Vd+CnfDcPs/iZ1i2+Zl+va79s4fcUhRReuwi7VCg 7nHiYSNC7qZo84Wzjz3RoGYyJ6MKLRn3zqAxUtFECoS074/JX1sLG0Z3hi19MBmJ/teM84GY IbSvRwZu+VkJgIvZonFZjbwF7XyoSIiEJWQC+AKvwtEBNoVOMuH0tZsgqcgMqGs6lLn66RK4 tMV1aNeX6R+dGSiu11i+9pm7sw8tAmsfu3kQpyk4SB3AJ0jtXrQRESFa1+iemJtt+RaSE5LK 5sGLAO+oN+DlE0mRNDQowS6q/GBhPCjjbTMcMfRoWPCpHZZfKpv5iefXnZ/xVj7ugYdV2T7z r6VL2BRPNvvkgbLZgIlkWyfxRnGh683h4vTqRqTb1wka5pmyBNAv7vCgqrwfvaV1m7J9O4B5 PuRjYRelmCygQBTXFeJAVJvuh2efFknMh41R01PP2ulXAQuVYEztq3t3Ycw6+HeqjbeqTF8C DboqYeIM18HgkOqRrn3VuwnKFNdzyBmgYh/zZx/dJ3yWQi/kfhR6TawAwz6GdbQGiu5fsx5t u14WBxmzNf9tXK7hnXcI24Z1z6e5jG6U2Swtmi8sGSh6fqV4dBKmhobEoS7Xl496JN2NKuaX jeWsF2rOwE0EZmhJFwEIAOAWiIj1EYkbikxXSSP3AazkI+Y/ICzdFDmiXXrYnf/mYEzORB0K vqNRQOdLyjbLKPQwSjYEt1uqwKaD1LRLbA7FpktAShDK4yIljkxhvDI8semfQ5WE/1Jj/I/Q U+4VXhkd6UvvpyQt/LiWvyAfvExPEvhiMnsg2zkQbBQ/M4Ns7ck0zQ4BTAVzW/GqoT2z03mg p1FhxkfzHMKPQ6ImEpuY5cZTQwrBUgWif6HzCtQJL7Ipa2fFnDaIHQeiJG0RXl/g9x3YlwWG sxOFrpWWsh6GI0Mo2W2nkinEIts48+wNDBCMcMlOaMYpyAI7fT5ziDuG2CBA060ZT7qqdl6b aXUAEQEAAcLBfAQYAQgAJhYhBMq9oSggF8JnIZiFx0jwzLaPWdFMBQJmaEkXAhsMBQkB4TOA AAoJEEjwzLaPWdFMbRUP/0t5FrjF8KY6uCU4Tx029NYKDN9zJr0CVwSGsNfC8WWonKs66QE1 pd6xBVoBzu5InFRWa2ed6d6vBw2BaJHC0aMg3iwwBbEgPn4Jx89QfczFMJvFm+MNc2DLDrqN zaQSqBzQ5SvUjxh8lQ+iqAhi0MPv4e2YbXD0ROyO+ITRgQVZBVXoPm4IJGYWgmVmxP34oUQh BM7ipfCVbcOFU5OPhd9/jn1BCHzir+/i0fY2Z/aexMYHwXUMha/itvsBHGcIEYKk7PL9FEfs wlbq+vWoCtUTUc0AjDgB76AcUVxxJtxxpyvES9aFxWD7Qc+dnGJnfxVJI0zbN2b37fX138Bf 27NuKpokv0sBnNEtsD7TY4gBz4QhvRNSBli0E5bGUbkM31rh4Iz21Qk0cCwR9D/vwQVsgPvG ioRqhvFWtLsEt/xKolOmUWA/jP0p8wnQ+3jY6a/DJ+o5LnVFzFqbK3fSojKbfr3bY33iZTSj DX9A4BcohRyqhnpNYyHL36gaOnNnOc+uXFCdoQkI531hXjzIsVs2OlfRufuDrWwAv+em2uOT BnRX9nFx9kPSO42TkFK55Dr5EDeBO3v33recscuB8VVN5xvh0GV57Qre+9sJrEq7Es9W609a +M0yRJWJEjFnMa/jsGZ+QyLD5QTL6SGuZ9gKI3W1SfFZOzV7hHsxPTZ6 Organization: OpenVPN Inc. In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 21/11/2024 00:58, Sergey Ryazanov wrote: > On 15.11.2024 16:28, Antonio Quartulli wrote: >> On 10/11/2024 19:26, Sergey Ryazanov wrote: >>> On 29.10.2024 12:47, Antonio Quartulli wrote: > > [...] > >>>> +static bool ovpn_socket_hold(struct ovpn_socket *sock) >>>> +{ >>>> +    return kref_get_unless_zero(&sock->refcount); >>> >>> Why do we need to wrap this kref acquiring call into the function. >>> Why we cannot simply call kref_get_unless_zero() from ovpn_socket_get()? >> >> Generally I prefer to keep the API among objects consistent. >> In this specific case, it means having hold() and put() helpers in >> order to avoid calling kref_* functions directly in the code. >> >> This is a pretty simple case because hold() is called only once, but I >> still like to be consistent. > > Make sense. The counterpart ovpn_socket_hold() function declared in the > header file. Probably that's why I missed it. Shall we move the holding > routine there as well? I prefer not to, because that function is used only in socket.c. Moving/declaring it in socket.h would export a symbols that is not used anywhere else. The _put() variant is instead use in peer.c, thus it is exported. > > [...] > >>>> +int ovpn_udp_socket_attach(struct socket *sock, struct ovpn_struct >>>> *ovpn) >>>> +{ >>>> +    struct ovpn_socket *old_data; >>>> +    int ret = 0; >>>> + >>>> +    /* sanity check */ >>>> +    if (sock->sk->sk_protocol != IPPROTO_UDP) { >>> >>> The function will be called only for a UDP socket. The caller makes >>> sure this is truth. So, why do we need this check? >> >> To avoid this function being copied/called somewhere else in the >> future and we forget about this critical assumption. > > Shall we do the same for all other functions in this file? E.g. > ovpn_udp_socket_detach/ovpn_udp_send_skb? Those functions work on a socket that is already owned, thus it already passed this precheck, while _attach() is the one seeing the new socket for the first time. If this check is triggered it would only be due to a bug. Hence the DEBUG_NET_WARN_ON_ONCE(). > And who is giving guarantee > that the code will be copied together with the check? No guarantee is given :) > >> Indeed it's a just sanity check. > > Shall we check for pointers validity before dereferencing them? > > if (!ovpn || !sock || !sock->sk || !sock->sk->sk_protocol != IPPROTO_UDP) { > > With the above questions I would like to show that it's endless number > of possible mistakes. And no matter how much do we check, a creative > engineer will find a way to ruin the kernel. > > So, is it worth to spend code lines for checking socket for being UDP > inside a function that has '_udp_' in its name and is called only inside > the module? Are you suggesting we should drop any kind of check for functions called only within the module? I am not sure I follow.. Anyway, I am dropping the check at the beginning in the function. Regards, > >>>> +        DEBUG_NET_WARN_ON_ONCE(1); >>>> +        return -EINVAL; >>>> +    } > > -- > Sergey -- Antonio Quartulli OpenVPN Inc.