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Merge branch 'l2tp-fix-races-with-ipv4-mapped-ipv6-addresses'
Paolo Abeni says: ==================== l2tp: fix races with ipv4-mapped ipv6 addresses The syzbot reported an l2tp oops that uncovered some races in the l2tp xmit path and a partially related issue in the generic ipv6 code. We need to address them separately. v1 -> v2: - add missing fixes tag in patch 1 - fix several issues in patch 2 v2 -> v3: - dropped some unneeded chunks in patch 2 ==================== Reviewed-by: Guillaume Nault <g.nault@alphalink.fr> Signed-off-by: David S. Miller <davem@davemloft.net>
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38fbbc9c23
@ -146,10 +146,12 @@ int __ip6_datagram_connect(struct sock *sk, struct sockaddr *uaddr,
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struct sockaddr_in6 *usin = (struct sockaddr_in6 *) uaddr;
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struct inet_sock *inet = inet_sk(sk);
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struct ipv6_pinfo *np = inet6_sk(sk);
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struct in6_addr *daddr;
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struct in6_addr *daddr, old_daddr;
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__be32 fl6_flowlabel = 0;
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__be32 old_fl6_flowlabel;
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__be32 old_dport;
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int addr_type;
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int err;
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__be32 fl6_flowlabel = 0;
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if (usin->sin6_family == AF_INET) {
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if (__ipv6_only_sock(sk))
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@ -238,9 +240,13 @@ ipv4_connected:
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}
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}
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/* save the current peer information before updating it */
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old_daddr = sk->sk_v6_daddr;
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old_fl6_flowlabel = np->flow_label;
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old_dport = inet->inet_dport;
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sk->sk_v6_daddr = *daddr;
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np->flow_label = fl6_flowlabel;
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inet->inet_dport = usin->sin6_port;
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/*
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@ -250,11 +256,12 @@ ipv4_connected:
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err = ip6_datagram_dst_update(sk, true);
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if (err) {
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/* Reset daddr and dport so that udp_v6_early_demux()
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* fails to find this socket
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/* Restore the socket peer info, to keep it consistent with
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* the old socket state
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*/
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memset(&sk->sk_v6_daddr, 0, sizeof(sk->sk_v6_daddr));
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inet->inet_dport = 0;
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sk->sk_v6_daddr = old_daddr;
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np->flow_label = old_fl6_flowlabel;
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inet->inet_dport = old_dport;
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goto out;
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}
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@ -111,6 +111,13 @@ struct l2tp_net {
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spinlock_t l2tp_session_hlist_lock;
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};
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#if IS_ENABLED(CONFIG_IPV6)
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static bool l2tp_sk_is_v6(struct sock *sk)
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{
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return sk->sk_family == PF_INET6 &&
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!ipv6_addr_v4mapped(&sk->sk_v6_daddr);
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}
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#endif
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static inline struct l2tp_tunnel *l2tp_tunnel(struct sock *sk)
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{
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@ -1049,7 +1056,7 @@ static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
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/* Queue the packet to IP for output */
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skb->ignore_df = 1;
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#if IS_ENABLED(CONFIG_IPV6)
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if (tunnel->sock->sk_family == PF_INET6 && !tunnel->v4mapped)
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if (l2tp_sk_is_v6(tunnel->sock))
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error = inet6_csk_xmit(tunnel->sock, skb, NULL);
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else
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#endif
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@ -1112,6 +1119,15 @@ int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len
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goto out_unlock;
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}
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/* The user-space may change the connection status for the user-space
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* provided socket at run time: we must check it under the socket lock
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*/
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if (tunnel->fd >= 0 && sk->sk_state != TCP_ESTABLISHED) {
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kfree_skb(skb);
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ret = NET_XMIT_DROP;
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goto out_unlock;
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}
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/* Get routing info from the tunnel socket */
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skb_dst_drop(skb);
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skb_dst_set(skb, dst_clone(__sk_dst_check(sk, 0)));
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@ -1131,7 +1147,7 @@ int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len
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/* Calculate UDP checksum if configured to do so */
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#if IS_ENABLED(CONFIG_IPV6)
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if (sk->sk_family == PF_INET6 && !tunnel->v4mapped)
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if (l2tp_sk_is_v6(sk))
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udp6_set_csum(udp_get_no_check6_tx(sk),
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skb, &inet6_sk(sk)->saddr,
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&sk->sk_v6_daddr, udp_len);
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@ -1511,24 +1527,6 @@ int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32
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if (cfg != NULL)
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tunnel->debug = cfg->debug;
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#if IS_ENABLED(CONFIG_IPV6)
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if (sk->sk_family == PF_INET6) {
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struct ipv6_pinfo *np = inet6_sk(sk);
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if (ipv6_addr_v4mapped(&np->saddr) &&
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ipv6_addr_v4mapped(&sk->sk_v6_daddr)) {
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struct inet_sock *inet = inet_sk(sk);
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tunnel->v4mapped = true;
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inet->inet_saddr = np->saddr.s6_addr32[3];
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inet->inet_rcv_saddr = sk->sk_v6_rcv_saddr.s6_addr32[3];
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inet->inet_daddr = sk->sk_v6_daddr.s6_addr32[3];
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} else {
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tunnel->v4mapped = false;
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}
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}
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#endif
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/* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
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tunnel->encap = encap;
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if (encap == L2TP_ENCAPTYPE_UDP) {
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@ -188,9 +188,6 @@ struct l2tp_tunnel {
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struct sock *sock; /* Parent socket */
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int fd; /* Parent fd, if tunnel socket
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* was created by userspace */
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#if IS_ENABLED(CONFIG_IPV6)
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bool v4mapped;
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#endif
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struct work_struct del_work;
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