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([2001:67c:2fbc:1:3fbc:2352:116e:c517]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-433cde05898sm21624965e9.9.2024.11.22.01.40.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 22 Nov 2024 01:40:57 -0800 (PST) Message-ID: <5eaf74fb-ad13-4371-95b8-7a5f1f3a9cda@openvpn.net> Date: Fri, 22 Nov 2024 10:41:26 +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 15/23] ovpn: implement keepalive mechanism From: Antonio Quartulli To: Sabrina Dubroca Cc: Eric Dumazet , Jakub Kicinski , Paolo Abeni , Donald Hunter , Shuah Khan , ryazanov.s.a@gmail.com, 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-v11-15-de4698c73a25@openvpn.net> <189dbeea-127a-47e8-84f8-c8cf1cc03536@openvpn.net> Content-Language: en-US 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: <189dbeea-127a-47e8-84f8-c8cf1cc03536@openvpn.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 12/11/2024 14:20, Antonio Quartulli wrote: [...] >>> +static int ovpn_peer_del_nolock(struct ovpn_peer *peer, >>> +                enum ovpn_del_peer_reason reason) >>> +{ >>> +    switch (peer->ovpn->mode) { >>> +    case OVPN_MODE_MP: >> >> I think it would be nice to add >> >>      lockdep_assert_held(&peer->ovpn->peers->lock); Sabrina, in other places I have used the sparse notation __must_hold() instead. Is there any preference in regards to lockdep vs sparse? I could switch them all to lockdep_assert_held if needed. Regards, >> >>> +        return ovpn_peer_del_mp(peer, reason); >>> +    case OVPN_MODE_P2P: >> >> and here >> >>      lockdep_assert_held(&peer->ovpn->lock); > > Yeah, good idea. > __must_hold() can't work here, so lockdep_assert_held is definitely the > way to go. > >> >> (I had to check that ovpn_peer_del_nolock is indeed called with those >> locks held since they're taken by ovpn_peer_keepalive_work_{mp,p2p}, >> adding these assertions would make it clear that ovpn_peer_del_nolock >> is not an unsafe version of ovpn_peer_del) > > Right, it makes sense. > >> >>> +        return ovpn_peer_del_p2p(peer, reason); >>> +    default: >>> +        return -EOPNOTSUPP; >>> +    } >>> +} >>> + >>>   /** >>>    * ovpn_peers_free - free all peers in the instance >>>    * @ovpn: the instance whose peers should be released >>> @@ -830,3 +871,150 @@ void ovpn_peers_free(struct ovpn_struct *ovpn) >>>           ovpn_peer_unhash(peer, OVPN_DEL_PEER_REASON_TEARDOWN); >>>       spin_unlock_bh(&ovpn->peers->lock); >>>   } >>> + >>> +static time64_t ovpn_peer_keepalive_work_single(struct ovpn_peer *peer, >>> +                        time64_t now) >>> +{ >>> +    time64_t next_run1, next_run2, delta; >>> +    unsigned long timeout, interval; >>> +    bool expired; >>> + >>> +    spin_lock_bh(&peer->lock); >>> +    /* we expect both timers to be configured at the same time, >>> +     * therefore bail out if either is not set >>> +     */ >>> +    if (!peer->keepalive_timeout || !peer->keepalive_interval) { >>> +        spin_unlock_bh(&peer->lock); >>> +        return 0; >>> +    } >>> + >>> +    /* check for peer timeout */ >>> +    expired = false; >>> +    timeout = peer->keepalive_timeout; >>> +    delta = now - peer->last_recv; >> >> I'm not sure that's always > 0 if we finish decrypting a packet just >> as the workqueue starts: >> >>    ovpn_peer_keepalive_work >>      now = ... >> >>                                         ovpn_decrypt_post >>                                           peer->last_recv = ... >> >>    ovpn_peer_keepalive_work_single >>      delta: now < peer->last_recv >> > > Yeah, there is nothing preventing this from happening...but is this > truly a problem? The math should still work, no? > > However: > >> >> >>> +    if (delta < timeout) { >>> +        peer->keepalive_recv_exp = now + timeout - delta; >> >> I'd shorten that to >> >>      peer->keepalive_recv_exp = peer->last_recv + timeout; >> >> it's a bit more readable to my eyes and avoids risks of wrapping >> values. >> >> So I'd probably get rid of delta and go with: >> >>      last_recv = READ_ONCE(peer->last_recv) >>      if (now < last_recv + timeout) { >>          peer->keepalive_recv_exp = last_recv + timeout; >>          next_run1 = peer->keepalive_recv_exp; >>      } else if ... >> >>> +        next_run1 = peer->keepalive_recv_exp; >>> +    } else if (peer->keepalive_recv_exp > now) { >>> +        next_run1 = peer->keepalive_recv_exp; >>> +    } else { >>> +        expired = true; >>> +    } > > I agree this is simpler to read and gets rid of some extra operations. > > [note: I took inspiration from nat_keepalive_work_single() - it could be > simplified as well I guess] > >> >> [...] >>> +    /* check for peer keepalive */ >>> +    expired = false; >>> +    interval = peer->keepalive_interval; >>> +    delta = now - peer->last_sent; >>> +    if (delta < interval) { >>> +        peer->keepalive_xmit_exp = now + interval - delta; >>> +        next_run2 = peer->keepalive_xmit_exp; >> >> and same here > > Yeah, will change both. Thanks! > > > Regards, > > -- Antonio Quartulli OpenVPN Inc.