From patchwork Mon Dec 9 08:53:22 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Antonio Quartulli X-Patchwork-Id: 848554 Received: from mail-wr1-f46.google.com (mail-wr1-f46.google.com [209.85.221.46]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E07C3215F59 for ; Mon, 9 Dec 2024 08:53:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.46 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733734400; cv=none; b=iSa85WIZ+kLgxMy9pmmcK3Dph+1lQbPyC0ukS+KyoGdkoswASKDKaa7cIlEtQrN9psOD5aUIiJ/xCNPJuJRUDonvwZBSgIUWvK94330gxQpmAneZpFjYopyqvWP6md9j9YDcpI+9IWSCprnMskgm4RM/5HJnSqubVofB7JbDyFQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733734400; c=relaxed/simple; bh=neS/+0qWJqF8Z7Wgo3VzoX3OM8bNHfa0Vevx+f0f3Ls=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=rIhsRpxhBq72oAkKoqyvdPOYoVpKAdjmng0h8csq+ic/UnFGooiIu6MUf5zNRGQFgnwDgWTdmHJZ4dSSJLQq4gXfUN+xq/GrsZ6pC5y7u7gjuUnfA1VSVPp4Q9+ti3l9N5jufkstoF3jYoZox5n9C86z675wFsem2Iok1heuQko= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=openvpn.net; spf=pass smtp.mailfrom=openvpn.com; dkim=pass (2048-bit key) header.d=openvpn.net header.i=@openvpn.net header.b=HOsVj1md; arc=none smtp.client-ip=209.85.221.46 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=openvpn.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=openvpn.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=openvpn.net header.i=@openvpn.net header.b="HOsVj1md" Received: by mail-wr1-f46.google.com with SMTP id ffacd0b85a97d-38637614567so725528f8f.3 for ; Mon, 09 Dec 2024 00:53:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=openvpn.net; s=google; t=1733734395; x=1734339195; darn=vger.kernel.org; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:from:to:cc:subject:date:message-id :reply-to; bh=qGTX6bsSUfHp3feyAtZvFNRrvKLiQ67eLp8Tyq9Lxvg=; b=HOsVj1mdGfzmpfzr1EHfD9rU6nxmvJant9NwEAWc8kSdR39I4zWzuA37CEP+T/Lma+ pXZWUPCuCXH2q31eXRrIx+n8zltLGV69Xfbh5ESr0nBkyWkLe4IXl1WLoi+TTA/I/HD2 hnH3lzD8cG19ubheA9JvZ0dr1OlkTLt0TwriYElO9WXLdLzWwJdVt39Bfzq/pVlyq6nP qzydwMFP7tuhalQn0wku9vkQNOnbPoY8Rmzsa0XTfXYKRtcKZmNHUCsjnTKLiupmUR/v veJ3ZWu0xIDcRP66ubJB4Bmfx5cNe0X9PDFwJwSaQ8qttWJc9he8AGDq8tpUjAkRl8em WHlg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1733734395; x=1734339195; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=qGTX6bsSUfHp3feyAtZvFNRrvKLiQ67eLp8Tyq9Lxvg=; b=Jzw4Kd27Q7VBexZ2sXyqs7IzBqC5QaGEQBREn1U9zT8Z4CVLvAK7aNwhxSF3PANnFU loJfJ5KXjagzY2nNKFd7jvVWHNps3nebWY1blaTHNAhx/FX2qCysgmg0so9ze1OpIQck fmbFCAOG6sBivqzynTPQuryKBt7ki8W//vSXk3vr+w3Olj6LHkx3OguV/lRWR0txdU/3 +1c/YEev3Iy9T0YHYjiz5vsD6YiSia4Ef29maOUi7NNlC+whC8pZYp3fPKw90oxnPuWN uM5ZnyAhnW7m0AKasJ3J861r8/IcC952JdXXLVAdvCqSB98l5cViYi3CaK8CmnmKj6tk fBTQ== X-Forwarded-Encrypted: i=1; AJvYcCX0ZTvEV492LdKECGwdpQIq2lr8trBfVZj2//tN2ed9i223iX5Tx8ujZl8i1+lSl4Z9zpchAq5k6GbRl2btNfY=@vger.kernel.org X-Gm-Message-State: AOJu0Yz++B40f4gokdEiGZPN58Yox1oUOehLXELOz6LACrCB4oJAv8Ey wI2/lIHAmaip6wUmA3T/whRFI2DTEtn+XPXNwOxg/YFpEY37OCsf8kpxJcUT0ahbIurzSBgutTI P X-Gm-Gg: ASbGnctY+3xW1PoHuA3iWUCyc4v0E/mCq8r6O/oTfsrRE1Ro1O9xOaJzZAzfMlmRAiW zD0PGBAGW0ge1OtyJoRqlfkaygCR4tNUIVO9h1pUg1xzgCKyYJM7oUA99Srr4qPmoMC+SjRLR8G GmkCWkhMDhHQ7YWkUL09oncpuLA7Rw2Kp3yLpvnQJNZcVXSW34rBozuwN6uQjKUukbt+QSwhsMI JGxKwNxZDYVHOGatgnpyI8z6U1J0C6287U4KqhBb1yl+IInyrvKFK07+Ad+ X-Google-Smtp-Source: AGHT+IGDzmW3tCzfM79GbDaPZOaMTQrHsZZ5RRB4SMX+nsVLifwjbxFOZsjY74xhpPsIToi/akxYCw== X-Received: by 2002:a5d:47a8:0:b0:385:d7a7:ad60 with SMTP id ffacd0b85a97d-3862b34f675mr8913289f8f.3.1733734394661; Mon, 09 Dec 2024 00:53:14 -0800 (PST) Received: from serenity.mandelbit.com ([2001:67c:2fbc:1:c60f:6f50:7258:1f7]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38621fbbea8sm12439844f8f.97.2024.12.09.00.53.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Dec 2024 00:53:14 -0800 (PST) From: Antonio Quartulli Date: Mon, 09 Dec 2024 09:53:22 +0100 Subject: [PATCH net-next v14 13/22] ovpn: implement peer lookup logic Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20241209-b4-ovpn-v14-13-ea243cf16417@openvpn.net> References: <20241209-b4-ovpn-v14-0-ea243cf16417@openvpn.net> In-Reply-To: <20241209-b4-ovpn-v14-0-ea243cf16417@openvpn.net> To: netdev@vger.kernel.org, Eric Dumazet , Jakub Kicinski , Paolo Abeni , Donald Hunter , Antonio Quartulli , Shuah Khan , sd@queasysnail.net, ryazanov.s.a@gmail.com, Andrew Lunn Cc: Simon Horman , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=11634; i=antonio@openvpn.net; h=from:subject:message-id; bh=neS/+0qWJqF8Z7Wgo3VzoX3OM8bNHfa0Vevx+f0f3Ls=; b=owEBbQGS/pANAwAIAQtw5TqgONWHAcsmYgBnVrATi90N7pJqaUAZSCQrkk3iMGf0I+CMGuP3b dUu7oZGbXWJATMEAAEIAB0WIQSZq9xs+NQS5N5fwPwLcOU6oDjVhwUCZ1awEwAKCRALcOU6oDjV h2GeCACBm0SN+KdYRTgc3IA5wBNMWivwv1c7aV84bgq/QYETMkaDAgtDSRReAG99XujJoeetN6k 1oqgX3qdGs/vTQGCNAvJqlqxPDaa4nmoqQnYPc/AloQ5jrxcfVVGeyAUlbYB/D66yV/k028Tw84 QCjwv8aeqga3A3fEocJGsWzHugC9K3pW2usPXYlFE4OlLm7mZnBXZncJTyFyH1JS9UNcyxPSfa9 8tfwa+0TXtOKrpIcbLAnpoWMcqcLBJfAPezvrc50S8KOAkwAZLjDKAOvRhSHWfbvzm5HWnTHnV0 8JdguMfXDmMu6aVZLmYQYt3kQfa5uUWx0qQDzcKXvKrzwAoS X-Developer-Key: i=antonio@openvpn.net; a=openpgp; fpr=CABDA1282017C267219885C748F0CCB68F59D14C In a multi-peer scenario there are a number of situations when a specific peer needs to be looked up. We may want to lookup a peer by: 1. its ID 2. its VPN destination IP 3. its transport IP/port couple For each of the above, there is a specific routing table referencing all peers for fast look up. Case 2. is a bit special in the sense that an outgoing packet may not be sent to the peer VPN IP directly, but rather to a network behind it. For this reason we first perform a nexthop lookup in the system routing table and then we use the retrieved nexthop as peer search key. Signed-off-by: Antonio Quartulli --- drivers/net/ovpn/peer.c | 301 ++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 291 insertions(+), 10 deletions(-) diff --git a/drivers/net/ovpn/peer.c b/drivers/net/ovpn/peer.c index 9f213ccacfaf8170b9c23730498f156360774d7e..5e78c984ef302ae17ef8481bb10ac382e5d11e31 100644 --- a/drivers/net/ovpn/peer.c +++ b/drivers/net/ovpn/peer.c @@ -10,6 +10,7 @@ #include #include #include +#include #include "ovpnstruct.h" #include "bind.h" @@ -136,6 +137,121 @@ static int ovpn_peer_skb_to_sockaddr(struct sk_buff *skb, return -1; } +/** + * ovpn_nexthop_from_skb4 - retrieve IPv4 nexthop for outgoing skb + * @skb: the outgoing packet + * + * Return: the IPv4 of the nexthop + */ +static __be32 ovpn_nexthop_from_skb4(struct sk_buff *skb) +{ + const struct rtable *rt = skb_rtable(skb); + + if (rt && rt->rt_uses_gateway) + return rt->rt_gw4; + + return ip_hdr(skb)->daddr; +} + +/** + * ovpn_nexthop_from_skb6 - retrieve IPv6 nexthop for outgoing skb + * @skb: the outgoing packet + * + * Return: the IPv6 of the nexthop + */ +static struct in6_addr ovpn_nexthop_from_skb6(struct sk_buff *skb) +{ + const struct rt6_info *rt = skb_rt6_info(skb); + + if (!rt || !(rt->rt6i_flags & RTF_GATEWAY)) + return ipv6_hdr(skb)->daddr; + + return rt->rt6i_gateway; +} + +/* variable name __tbl2 needs to be different from __tbl1 + * in the macro below to avoid confusing clang + */ +#define ovpn_get_hash_slot(_tbl, _key, _key_len) ({ \ + typeof(_tbl) *__tbl2 = &(_tbl); \ + jhash(_key, _key_len, 0) % HASH_SIZE(*__tbl2); \ +}) + +#define ovpn_get_hash_head(_tbl, _key, _key_len) ({ \ + typeof(_tbl) *__tbl1 = &(_tbl); \ + &(*__tbl1)[ovpn_get_hash_slot(*__tbl1, _key, _key_len)];\ +}) + +/** + * ovpn_peer_get_by_vpn_addr4 - retrieve peer by its VPN IPv4 address + * @ovpn: the openvpn instance to search + * @addr: VPN IPv4 to use as search key + * + * Refcounter is not increased for the returned peer. + * + * Return: the peer if found or NULL otherwise + */ +static struct ovpn_peer *ovpn_peer_get_by_vpn_addr4(struct ovpn_priv *ovpn, + __be32 addr) +{ + struct hlist_nulls_head *nhead; + struct hlist_nulls_node *ntmp; + struct ovpn_peer *tmp; + unsigned int slot; + +begin: + slot = ovpn_get_hash_slot(ovpn->peers->by_vpn_addr, &addr, + sizeof(addr)); + nhead = &ovpn->peers->by_vpn_addr[slot]; + + hlist_nulls_for_each_entry_rcu(tmp, ntmp, nhead, hash_entry_addr4) + if (addr == tmp->vpn_addrs.ipv4.s_addr) + return tmp; + + /* item may have moved during lookup - check nulls and restart + * if that's the case + */ + if (get_nulls_value(ntmp) != slot) + goto begin; + + return NULL; +} + +/** + * ovpn_peer_get_by_vpn_addr6 - retrieve peer by its VPN IPv6 address + * @ovpn: the openvpn instance to search + * @addr: VPN IPv6 to use as search key + * + * Refcounter is not increased for the returned peer. + * + * Return: the peer if found or NULL otherwise + */ +static struct ovpn_peer *ovpn_peer_get_by_vpn_addr6(struct ovpn_priv *ovpn, + struct in6_addr *addr) +{ + struct hlist_nulls_head *nhead; + struct hlist_nulls_node *ntmp; + struct ovpn_peer *tmp; + unsigned int slot; + +begin: + slot = ovpn_get_hash_slot(ovpn->peers->by_vpn_addr, addr, + sizeof(*addr)); + nhead = &ovpn->peers->by_vpn_addr[slot]; + + hlist_nulls_for_each_entry_rcu(tmp, ntmp, nhead, hash_entry_addr6) + if (ipv6_addr_equal(addr, &tmp->vpn_addrs.ipv6)) + return tmp; + + /* item may have moved during lookup - check nulls and restart + * if that's the case + */ + if (get_nulls_value(ntmp) != slot) + goto begin; + + return NULL; +} + /** * ovpn_peer_transp_match - check if sockaddr and peer binding match * @peer: the peer to get the binding from @@ -213,14 +329,43 @@ ovpn_peer_get_by_transp_addr_p2p(struct ovpn_priv *ovpn, struct ovpn_peer *ovpn_peer_get_by_transp_addr(struct ovpn_priv *ovpn, struct sk_buff *skb) { - struct ovpn_peer *peer = NULL; + struct ovpn_peer *tmp, *peer = NULL; struct sockaddr_storage ss = { 0 }; + struct hlist_nulls_head *nhead; + struct hlist_nulls_node *ntmp; + unsigned int slot; + size_t sa_len; - if (unlikely(!ovpn_peer_skb_to_sockaddr(skb, &ss))) + sa_len = ovpn_peer_skb_to_sockaddr(skb, &ss); + if (unlikely(sa_len < 0)) return NULL; if (ovpn->mode == OVPN_MODE_P2P) - peer = ovpn_peer_get_by_transp_addr_p2p(ovpn, &ss); + return ovpn_peer_get_by_transp_addr_p2p(ovpn, &ss); + + rcu_read_lock(); +begin: + slot = ovpn_get_hash_slot(ovpn->peers->by_transp_addr, &ss, sa_len); + nhead = &ovpn->peers->by_transp_addr[slot]; + + hlist_nulls_for_each_entry_rcu(tmp, ntmp, nhead, + hash_entry_transp_addr) { + if (!ovpn_peer_transp_match(tmp, &ss)) + continue; + + if (!ovpn_peer_hold(tmp)) + continue; + + peer = tmp; + break; + } + + /* item may have moved during lookup - check nulls and restart + * if that's the case + */ + if (!peer && get_nulls_value(ntmp) != slot) + goto begin; + rcu_read_unlock(); return peer; } @@ -255,10 +400,27 @@ static struct ovpn_peer *ovpn_peer_get_by_id_p2p(struct ovpn_priv *ovpn, */ struct ovpn_peer *ovpn_peer_get_by_id(struct ovpn_priv *ovpn, u32 peer_id) { - struct ovpn_peer *peer = NULL; + struct ovpn_peer *tmp, *peer = NULL; + struct hlist_head *head; if (ovpn->mode == OVPN_MODE_P2P) - peer = ovpn_peer_get_by_id_p2p(ovpn, peer_id); + return ovpn_peer_get_by_id_p2p(ovpn, peer_id); + + head = ovpn_get_hash_head(ovpn->peers->by_id, &peer_id, + sizeof(peer_id)); + + rcu_read_lock(); + hlist_for_each_entry_rcu(tmp, head, hash_entry_id) { + if (tmp->id != peer_id) + continue; + + if (!ovpn_peer_hold(tmp)) + continue; + + peer = tmp; + break; + } + rcu_read_unlock(); return peer; } @@ -280,6 +442,8 @@ struct ovpn_peer *ovpn_peer_get_by_dst(struct ovpn_priv *ovpn, struct sk_buff *skb) { struct ovpn_peer *peer = NULL; + struct in6_addr addr6; + __be32 addr4; /* in P2P mode, no matter the destination, packets are always sent to * the single peer listening on the other side @@ -290,11 +454,109 @@ struct ovpn_peer *ovpn_peer_get_by_dst(struct ovpn_priv *ovpn, if (unlikely(peer && !ovpn_peer_hold(peer))) peer = NULL; rcu_read_unlock(); + return peer; } + rcu_read_lock(); + switch (skb->protocol) { + case htons(ETH_P_IP): + addr4 = ovpn_nexthop_from_skb4(skb); + peer = ovpn_peer_get_by_vpn_addr4(ovpn, addr4); + break; + case htons(ETH_P_IPV6): + addr6 = ovpn_nexthop_from_skb6(skb); + peer = ovpn_peer_get_by_vpn_addr6(ovpn, &addr6); + break; + } + + if (unlikely(peer && !ovpn_peer_hold(peer))) + peer = NULL; + rcu_read_unlock(); + return peer; } +/** + * ovpn_nexthop_from_rt4 - look up the IPv4 nexthop for the given destination + * @ovpn: the private data representing the current VPN session + * @dest: the destination to be looked up + * + * Looks up in the IPv4 system routing table the IP of the nexthop to be used + * to reach the destination passed as argument. If no nexthop can be found, the + * destination itself is returned as it probably has to be used as nexthop. + * + * Return: the IP of the next hop if found or dest itself otherwise + */ +static __be32 ovpn_nexthop_from_rt4(struct ovpn_priv *ovpn, __be32 dest) +{ + struct rtable *rt; + struct flowi4 fl = { + .daddr = dest + }; + + rt = ip_route_output_flow(dev_net(ovpn->dev), &fl, NULL); + if (IS_ERR(rt)) { + net_dbg_ratelimited("%s: no route to host %pI4\n", + netdev_name(ovpn->dev), &dest); + /* if we end up here this packet is probably going to be + * thrown away later + */ + return dest; + } + + if (!rt->rt_uses_gateway) + goto out; + + dest = rt->rt_gw4; +out: + ip_rt_put(rt); + return dest; +} + +/** + * ovpn_nexthop_from_rt6 - look up the IPv6 nexthop for the given destination + * @ovpn: the private data representing the current VPN session + * @dest: the destination to be looked up + * + * Looks up in the IPv6 system routing table the IP of the nexthop to be used + * to reach the destination passed as argument. If no nexthop can be found, the + * destination itself is returned as it probably has to be used as nexthop. + * + * Return: the IP of the next hop if found or dest itself otherwise + */ +static struct in6_addr ovpn_nexthop_from_rt6(struct ovpn_priv *ovpn, + struct in6_addr dest) +{ +#if IS_ENABLED(CONFIG_IPV6) + struct dst_entry *entry; + struct rt6_info *rt; + struct flowi6 fl = { + .daddr = dest, + }; + + entry = ipv6_stub->ipv6_dst_lookup_flow(dev_net(ovpn->dev), NULL, &fl, + NULL); + if (IS_ERR(entry)) { + net_dbg_ratelimited("%s: no route to host %pI6c\n", + netdev_name(ovpn->dev), &dest); + /* if we end up here this packet is probably going to be + * thrown away later + */ + return dest; + } + + rt = dst_rt6_info(entry); + + if (!(rt->rt6i_flags & RTF_GATEWAY)) + goto out; + + dest = rt->rt6i_gateway; +out: + dst_release((struct dst_entry *)rt); +#endif + return dest; +} + /** * ovpn_peer_check_by_src - check that skb source is routed via peer * @ovpn: the openvpn instance to search @@ -307,21 +569,40 @@ bool ovpn_peer_check_by_src(struct ovpn_priv *ovpn, struct sk_buff *skb, struct ovpn_peer *peer) { bool match = false; + struct in6_addr addr6; + __be32 addr4; if (ovpn->mode == OVPN_MODE_P2P) { /* in P2P mode, no matter the destination, packets are always * sent to the single peer listening on the other side */ - match = (peer == rcu_access_pointer(ovpn->peer)); + return peer == rcu_access_pointer(ovpn->peer); + } + + /* This function performs a reverse path check, therefore we now + * lookup the nexthop we would use if we wanted to route a packet + * to the source IP. If the nexthop matches the sender we know the + * latter is valid and we allow the packet to come in + */ + + switch (skb->protocol) { + case htons(ETH_P_IP): + addr4 = ovpn_nexthop_from_rt4(ovpn, ip_hdr(skb)->saddr); + rcu_read_lock(); + match = (peer == ovpn_peer_get_by_vpn_addr4(ovpn, addr4)); + rcu_read_unlock(); + break; + case htons(ETH_P_IPV6): + addr6 = ovpn_nexthop_from_rt6(ovpn, ipv6_hdr(skb)->saddr); + rcu_read_lock(); + match = (peer == ovpn_peer_get_by_vpn_addr6(ovpn, &addr6)); + rcu_read_unlock(); + break; } return match; } -#define ovpn_get_hash_head(_tbl, _key, _key_len) ({ \ - typeof(_tbl) *__tbl = &(_tbl); \ - (&(*__tbl)[jhash(_key, _key_len, 0) % HASH_SIZE(*__tbl)]); }) \ - /** * ovpn_peer_add_mp - add peer to related tables in a MP instance * @ovpn: the instance to add the peer to