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Message-ID: <CAJnrk1bUZWPy0r7BHk6wa0V8Bg4WBiNnForm_V+BK5t_KMj47Q@mail.gmail.com>
Date: Mon, 21 Nov 2022 16:11:49 -0800
From: Joanne Koong <joannelkoong@...il.com>
To: Kuniyuki Iwashima <kuniyu@...zon.com>
Cc: "David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>,
Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
David Ahern <dsahern@...nel.org>,
Arnaldo Carvalho de Melo <acme@...driva.com>,
Martin KaFai Lau <martin.lau@...nel.org>,
Mat Martineau <mathew.j.martineau@...ux.intel.com>,
"Ziyang Xuan (William)" <william.xuanziyang@...wei.com>,
Stephen Hemminger <stephen@...workplumber.org>,
Pengfei Xu <pengfei.xu@...el.com>,
Kuniyuki Iwashima <kuni1840@...il.com>, netdev@...r.kernel.org,
dccp@...r.kernel.org
Subject: Re: [PATCH v4 net 3/4] dccp/tcp: Update saddr under bhash's lock.
On Fri, Nov 18, 2022 at 5:50 PM Kuniyuki Iwashima <kuniyu@...zon.com> wrote:
>
> When we call connect() for a socket bound to a wildcard address, we update
> saddr locklessly. However, it could result in a data race; another thread
> iterating over bhash might see a corrupted address.
>
> Let's update saddr under the bhash bucket's lock.
>
> Fixes: 3df80d9320bc ("[DCCP]: Introduce DCCPv6")
> Fixes: 7c657876b63c ("[DCCP]: Initial implementation")
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
Acked-by: Joanne Koong <joannelkoong@...il.com>
> ---
> include/net/inet_hashtables.h | 2 +-
> net/dccp/ipv4.c | 22 ++++-------------
> net/dccp/ipv6.c | 23 ++++--------------
> net/ipv4/af_inet.c | 11 +--------
> net/ipv4/inet_hashtables.c | 45 ++++++++++++++++++++++++++++++-----
> net/ipv4/tcp_ipv4.c | 20 ++++------------
> net/ipv6/tcp_ipv6.c | 19 +++------------
> 7 files changed, 56 insertions(+), 86 deletions(-)
>
> diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
> index 3af1e927247d..ba06e8b52264 100644
> --- a/include/net/inet_hashtables.h
> +++ b/include/net/inet_hashtables.h
> @@ -281,7 +281,7 @@ inet_bhash2_addr_any_hashbucket(const struct sock *sk, const struct net *net, in
> * sk_v6_rcv_saddr (ipv6) changes after it has been binded. The socket's
> * rcv_saddr field should already have been updated when this is called.
> */
> -int inet_bhash2_update_saddr(struct inet_bind_hashbucket *prev_saddr, struct sock *sk);
> +int inet_bhash2_update_saddr(struct sock *sk, void *saddr, int family);
>
> void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
> struct inet_bind2_bucket *tb2, unsigned short port);
> diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
> index 40640c26680e..95e376e3b911 100644
> --- a/net/dccp/ipv4.c
> +++ b/net/dccp/ipv4.c
> @@ -45,11 +45,10 @@ static unsigned int dccp_v4_pernet_id __read_mostly;
> int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
> {
> const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
> - struct inet_bind_hashbucket *prev_addr_hashbucket = NULL;
> - __be32 daddr, nexthop, prev_sk_rcv_saddr;
> struct inet_sock *inet = inet_sk(sk);
> struct dccp_sock *dp = dccp_sk(sk);
> __be16 orig_sport, orig_dport;
> + __be32 daddr, nexthop;
> struct flowi4 *fl4;
> struct rtable *rt;
> int err;
> @@ -91,26 +90,13 @@ int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
> daddr = fl4->daddr;
>
> if (inet->inet_saddr == 0) {
> - if (inet_csk(sk)->icsk_bind2_hash) {
> - prev_addr_hashbucket =
> - inet_bhashfn_portaddr(&dccp_hashinfo, sk,
> - sock_net(sk),
> - inet->inet_num);
> - prev_sk_rcv_saddr = sk->sk_rcv_saddr;
> - }
> - inet->inet_saddr = fl4->saddr;
> - }
> -
> - sk_rcv_saddr_set(sk, inet->inet_saddr);
> -
> - if (prev_addr_hashbucket) {
> - err = inet_bhash2_update_saddr(prev_addr_hashbucket, sk);
> + err = inet_bhash2_update_saddr(sk, &fl4->saddr, AF_INET);
> if (err) {
> - inet->inet_saddr = 0;
> - sk_rcv_saddr_set(sk, prev_sk_rcv_saddr);
> ip_rt_put(rt);
> return err;
> }
> + } else {
> + sk_rcv_saddr_set(sk, inet->inet_saddr);
> }
>
> inet->inet_dport = usin->sin_port;
> diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
> index 626166cb6d7e..94c101ed57a9 100644
> --- a/net/dccp/ipv6.c
> +++ b/net/dccp/ipv6.c
> @@ -934,26 +934,11 @@ static int dccp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
> }
>
> if (saddr == NULL) {
> - struct inet_bind_hashbucket *prev_addr_hashbucket = NULL;
> - struct in6_addr prev_v6_rcv_saddr;
> -
> - if (icsk->icsk_bind2_hash) {
> - prev_addr_hashbucket = inet_bhashfn_portaddr(&dccp_hashinfo,
> - sk, sock_net(sk),
> - inet->inet_num);
> - prev_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
> - }
> -
> saddr = &fl6.saddr;
> - sk->sk_v6_rcv_saddr = *saddr;
> -
> - if (prev_addr_hashbucket) {
> - err = inet_bhash2_update_saddr(prev_addr_hashbucket, sk);
> - if (err) {
> - sk->sk_v6_rcv_saddr = prev_v6_rcv_saddr;
> - goto failure;
> - }
> - }
> +
> + err = inet_bhash2_update_saddr(sk, saddr, AF_INET6);
> + if (err)
> + goto failure;
> }
>
> /* set the source address */
> diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
> index 4728087c42a5..0da679411330 100644
> --- a/net/ipv4/af_inet.c
> +++ b/net/ipv4/af_inet.c
> @@ -1230,7 +1230,6 @@ EXPORT_SYMBOL(inet_unregister_protosw);
>
> static int inet_sk_reselect_saddr(struct sock *sk)
> {
> - struct inet_bind_hashbucket *prev_addr_hashbucket;
> struct inet_sock *inet = inet_sk(sk);
> __be32 old_saddr = inet->inet_saddr;
> __be32 daddr = inet->inet_daddr;
> @@ -1260,16 +1259,8 @@ static int inet_sk_reselect_saddr(struct sock *sk)
> return 0;
> }
>
> - prev_addr_hashbucket =
> - inet_bhashfn_portaddr(tcp_or_dccp_get_hashinfo(sk), sk,
> - sock_net(sk), inet->inet_num);
> -
> - inet->inet_saddr = inet->inet_rcv_saddr = new_saddr;
> -
> - err = inet_bhash2_update_saddr(prev_addr_hashbucket, sk);
> + err = inet_bhash2_update_saddr(sk, &new_saddr, AF_INET);
> if (err) {
> - inet->inet_saddr = old_saddr;
> - inet->inet_rcv_saddr = old_saddr;
> ip_rt_put(rt);
> return err;
> }
> diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
> index d745f962745e..18ef370af113 100644
> --- a/net/ipv4/inet_hashtables.c
> +++ b/net/ipv4/inet_hashtables.c
> @@ -858,14 +858,34 @@ inet_bhash2_addr_any_hashbucket(const struct sock *sk, const struct net *net, in
> return &hinfo->bhash2[hash & (hinfo->bhash_size - 1)];
> }
>
> -int inet_bhash2_update_saddr(struct inet_bind_hashbucket *prev_saddr, struct sock *sk)
> +static void inet_update_saddr(struct sock *sk, void *saddr, int family)
> +{
> + if (family == AF_INET) {
> + inet_sk(sk)->inet_saddr = *(__be32 *)saddr;
> + sk_rcv_saddr_set(sk, inet_sk(sk)->inet_saddr);
> + }
> +#if IS_ENABLED(CONFIG_IPV6)
> + else {
> + sk->sk_v6_rcv_saddr = *(struct in6_addr *)saddr;
> + }
> +#endif
> +}
> +
> +int inet_bhash2_update_saddr(struct sock *sk, void *saddr, int family)
> {
> struct inet_hashinfo *hinfo = tcp_or_dccp_get_hashinfo(sk);
> + struct inet_bind_hashbucket *head, *head2;
> struct inet_bind2_bucket *tb2, *new_tb2;
> int l3mdev = inet_sk_bound_l3mdev(sk);
> - struct inet_bind_hashbucket *head2;
> int port = inet_sk(sk)->inet_num;
> struct net *net = sock_net(sk);
> + int bhash;
> +
> + if (!inet_csk(sk)->icsk_bind2_hash) {
> + /* Not bind()ed before. */
> + inet_update_saddr(sk, saddr, family);
> + return 0;
> + }
>
> /* Allocate a bind2 bucket ahead of time to avoid permanently putting
> * the bhash2 table in an inconsistent state if a new tb2 bucket
> @@ -875,14 +895,25 @@ int inet_bhash2_update_saddr(struct inet_bind_hashbucket *prev_saddr, struct soc
> if (!new_tb2)
> return -ENOMEM;
>
> + bhash = inet_bhashfn(net, port, hinfo->bhash_size);
> + head = &hinfo->bhash[bhash];
> head2 = inet_bhashfn_portaddr(hinfo, sk, net, port);
>
> - spin_lock_bh(&prev_saddr->lock);
> + /* If we change saddr locklessly, another thread
> + * iterating over bhash might see corrupted address.
> + */
> + spin_lock_bh(&head->lock);
> +
> + spin_lock(&head2->lock);
> __sk_del_bind2_node(sk);
> inet_bind2_bucket_destroy(hinfo->bind2_bucket_cachep, inet_csk(sk)->icsk_bind2_hash);
> - spin_unlock_bh(&prev_saddr->lock);
> + spin_unlock(&head2->lock);
> +
> + inet_update_saddr(sk, saddr, family);
>
> - spin_lock_bh(&head2->lock);
> + head2 = inet_bhashfn_portaddr(hinfo, sk, net, port);
> +
> + spin_lock(&head2->lock);
> tb2 = inet_bind2_bucket_find(head2, net, port, l3mdev, sk);
> if (!tb2) {
> tb2 = new_tb2;
> @@ -890,7 +921,9 @@ int inet_bhash2_update_saddr(struct inet_bind_hashbucket *prev_saddr, struct soc
> }
> sk_add_bind2_node(sk, &tb2->owners);
> inet_csk(sk)->icsk_bind2_hash = tb2;
> - spin_unlock_bh(&head2->lock);
> + spin_unlock(&head2->lock);
> +
> + spin_unlock_bh(&head->lock);
>
> if (tb2 != new_tb2)
> kmem_cache_free(hinfo->bind2_bucket_cachep, new_tb2);
> diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
> index 6a3a732b584d..23dd7e9df2d5 100644
> --- a/net/ipv4/tcp_ipv4.c
> +++ b/net/ipv4/tcp_ipv4.c
> @@ -199,15 +199,14 @@ static int tcp_v4_pre_connect(struct sock *sk, struct sockaddr *uaddr,
> /* This will initiate an outgoing connection. */
> int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
> {
> - struct inet_bind_hashbucket *prev_addr_hashbucket = NULL;
> struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
> struct inet_timewait_death_row *tcp_death_row;
> - __be32 daddr, nexthop, prev_sk_rcv_saddr;
> struct inet_sock *inet = inet_sk(sk);
> struct tcp_sock *tp = tcp_sk(sk);
> struct ip_options_rcu *inet_opt;
> struct net *net = sock_net(sk);
> __be16 orig_sport, orig_dport;
> + __be32 daddr, nexthop;
> struct flowi4 *fl4;
> struct rtable *rt;
> int err;
> @@ -251,24 +250,13 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
> tcp_death_row = &sock_net(sk)->ipv4.tcp_death_row;
>
> if (!inet->inet_saddr) {
> - if (inet_csk(sk)->icsk_bind2_hash) {
> - prev_addr_hashbucket = inet_bhashfn_portaddr(tcp_death_row->hashinfo,
> - sk, net, inet->inet_num);
> - prev_sk_rcv_saddr = sk->sk_rcv_saddr;
> - }
> - inet->inet_saddr = fl4->saddr;
> - }
> -
> - sk_rcv_saddr_set(sk, inet->inet_saddr);
> -
> - if (prev_addr_hashbucket) {
> - err = inet_bhash2_update_saddr(prev_addr_hashbucket, sk);
> + err = inet_bhash2_update_saddr(sk, &fl4->saddr, AF_INET);
> if (err) {
> - inet->inet_saddr = 0;
> - sk_rcv_saddr_set(sk, prev_sk_rcv_saddr);
> ip_rt_put(rt);
> return err;
> }
> + } else {
> + sk_rcv_saddr_set(sk, inet->inet_saddr);
> }
>
> if (tp->rx_opt.ts_recent_stamp && inet->inet_daddr != daddr) {
> diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
> index 81b396e5cf79..2f3ca3190d26 100644
> --- a/net/ipv6/tcp_ipv6.c
> +++ b/net/ipv6/tcp_ipv6.c
> @@ -292,24 +292,11 @@ static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
> tcp_death_row = &sock_net(sk)->ipv4.tcp_death_row;
>
> if (!saddr) {
> - struct inet_bind_hashbucket *prev_addr_hashbucket = NULL;
> - struct in6_addr prev_v6_rcv_saddr;
> -
> - if (icsk->icsk_bind2_hash) {
> - prev_addr_hashbucket = inet_bhashfn_portaddr(tcp_death_row->hashinfo,
> - sk, net, inet->inet_num);
> - prev_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
> - }
> saddr = &fl6.saddr;
> - sk->sk_v6_rcv_saddr = *saddr;
>
> - if (prev_addr_hashbucket) {
> - err = inet_bhash2_update_saddr(prev_addr_hashbucket, sk);
> - if (err) {
> - sk->sk_v6_rcv_saddr = prev_v6_rcv_saddr;
> - goto failure;
> - }
> - }
> + err = inet_bhash2_update_saddr(sk, saddr, AF_INET6);
> + if (err)
> + goto failure;
> }
>
> /* set the source address */
> --
> 2.30.2
>
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