Commit 633f5b6b authored by David S. Miller's avatar David S. Miller

Merge branch 'net-initialize-fastreuse-on-inet_inherit_port'

Tim Froidcoeur says:

====================
net: initialize fastreuse on inet_inherit_port

In the case of TPROXY, bind_conflict optimizations for SO_REUSEADDR or
SO_REUSEPORT are broken, possibly resulting in O(n) instead of O(1) bind
behaviour or in the incorrect reuse of a bind.

the kernel keeps track for each bind_bucket if all sockets in the
bind_bucket support SO_REUSEADDR or SO_REUSEPORT in two fastreuse flags.
These flags allow skipping the costly bind_conflict check when possible
(meaning when all sockets have the proper SO_REUSE option).

For every socket added to a bind_bucket, these flags need to be updated.
As soon as a socket that does not support reuse is added, the flag is
set to false and will never go back to true, unless the bind_bucket is
deleted.

Note that there is no mechanism to re-evaluate these flags when a socket
is removed (this might make sense when removing a socket that would not
allow reuse; this leaves room for a future patch).

For this optimization to work, it is mandatory that these flags are
properly initialized and updated.

When a child socket is created from a listen socket in
__inet_inherit_port, the TPROXY case could create a new bind bucket
without properly initializing these flags, thus preventing the
optimization to work. Alternatively, a socket not allowing reuse could
be added to an existing bind bucket without updating the flags, causing
bind_conflict to never be called as it should.

Patch 1/2 refactors the fastreuse update code in inet_csk_get_port into a
small helper function, making the actual fix tiny and easier to understand.

Patch 2/2 calls this new helper when __inet_inherit_port decides to create
a new bind_bucket or use a different bind_bucket than the one of the listen
socket.

v4: - rebase on latest linux/net master branch
v3: - remove company disclaimer from automatic signature
v2: - remove unnecessary cast
====================
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 1b8ef142 d76f3351
...@@ -304,6 +304,10 @@ void inet_csk_listen_stop(struct sock *sk); ...@@ -304,6 +304,10 @@ void inet_csk_listen_stop(struct sock *sk);
void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr); void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr);
/* update the fast reuse flag when adding a socket */
void inet_csk_update_fastreuse(struct inet_bind_bucket *tb,
struct sock *sk);
struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu); struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu);
#define TCP_PINGPONG_THRESH 3 #define TCP_PINGPONG_THRESH 3
......
...@@ -296,6 +296,57 @@ static inline int sk_reuseport_match(struct inet_bind_bucket *tb, ...@@ -296,6 +296,57 @@ static inline int sk_reuseport_match(struct inet_bind_bucket *tb,
ipv6_only_sock(sk), true, false); ipv6_only_sock(sk), true, false);
} }
void inet_csk_update_fastreuse(struct inet_bind_bucket *tb,
struct sock *sk)
{
kuid_t uid = sock_i_uid(sk);
bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
if (hlist_empty(&tb->owners)) {
tb->fastreuse = reuse;
if (sk->sk_reuseport) {
tb->fastreuseport = FASTREUSEPORT_ANY;
tb->fastuid = uid;
tb->fast_rcv_saddr = sk->sk_rcv_saddr;
tb->fast_ipv6_only = ipv6_only_sock(sk);
tb->fast_sk_family = sk->sk_family;
#if IS_ENABLED(CONFIG_IPV6)
tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
#endif
} else {
tb->fastreuseport = 0;
}
} else {
if (!reuse)
tb->fastreuse = 0;
if (sk->sk_reuseport) {
/* We didn't match or we don't have fastreuseport set on
* the tb, but we have sk_reuseport set on this socket
* and we know that there are no bind conflicts with
* this socket in this tb, so reset our tb's reuseport
* settings so that any subsequent sockets that match
* our current socket will be put on the fast path.
*
* If we reset we need to set FASTREUSEPORT_STRICT so we
* do extra checking for all subsequent sk_reuseport
* socks.
*/
if (!sk_reuseport_match(tb, sk)) {
tb->fastreuseport = FASTREUSEPORT_STRICT;
tb->fastuid = uid;
tb->fast_rcv_saddr = sk->sk_rcv_saddr;
tb->fast_ipv6_only = ipv6_only_sock(sk);
tb->fast_sk_family = sk->sk_family;
#if IS_ENABLED(CONFIG_IPV6)
tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
#endif
}
} else {
tb->fastreuseport = 0;
}
}
}
/* Obtain a reference to a local port for the given sock, /* Obtain a reference to a local port for the given sock,
* if snum is zero it means select any available local port. * if snum is zero it means select any available local port.
* We try to allocate an odd port (and leave even ports for connect()) * We try to allocate an odd port (and leave even ports for connect())
...@@ -308,7 +359,6 @@ int inet_csk_get_port(struct sock *sk, unsigned short snum) ...@@ -308,7 +359,6 @@ int inet_csk_get_port(struct sock *sk, unsigned short snum)
struct inet_bind_hashbucket *head; struct inet_bind_hashbucket *head;
struct net *net = sock_net(sk); struct net *net = sock_net(sk);
struct inet_bind_bucket *tb = NULL; struct inet_bind_bucket *tb = NULL;
kuid_t uid = sock_i_uid(sk);
int l3mdev; int l3mdev;
l3mdev = inet_sk_bound_l3mdev(sk); l3mdev = inet_sk_bound_l3mdev(sk);
...@@ -345,49 +395,8 @@ int inet_csk_get_port(struct sock *sk, unsigned short snum) ...@@ -345,49 +395,8 @@ int inet_csk_get_port(struct sock *sk, unsigned short snum)
goto fail_unlock; goto fail_unlock;
} }
success: success:
if (hlist_empty(&tb->owners)) { inet_csk_update_fastreuse(tb, sk);
tb->fastreuse = reuse;
if (sk->sk_reuseport) {
tb->fastreuseport = FASTREUSEPORT_ANY;
tb->fastuid = uid;
tb->fast_rcv_saddr = sk->sk_rcv_saddr;
tb->fast_ipv6_only = ipv6_only_sock(sk);
tb->fast_sk_family = sk->sk_family;
#if IS_ENABLED(CONFIG_IPV6)
tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
#endif
} else {
tb->fastreuseport = 0;
}
} else {
if (!reuse)
tb->fastreuse = 0;
if (sk->sk_reuseport) {
/* We didn't match or we don't have fastreuseport set on
* the tb, but we have sk_reuseport set on this socket
* and we know that there are no bind conflicts with
* this socket in this tb, so reset our tb's reuseport
* settings so that any subsequent sockets that match
* our current socket will be put on the fast path.
*
* If we reset we need to set FASTREUSEPORT_STRICT so we
* do extra checking for all subsequent sk_reuseport
* socks.
*/
if (!sk_reuseport_match(tb, sk)) {
tb->fastreuseport = FASTREUSEPORT_STRICT;
tb->fastuid = uid;
tb->fast_rcv_saddr = sk->sk_rcv_saddr;
tb->fast_ipv6_only = ipv6_only_sock(sk);
tb->fast_sk_family = sk->sk_family;
#if IS_ENABLED(CONFIG_IPV6)
tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
#endif
}
} else {
tb->fastreuseport = 0;
}
}
if (!inet_csk(sk)->icsk_bind_hash) if (!inet_csk(sk)->icsk_bind_hash)
inet_bind_hash(sk, tb, port); inet_bind_hash(sk, tb, port);
WARN_ON(inet_csk(sk)->icsk_bind_hash != tb); WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);
......
...@@ -163,6 +163,7 @@ int __inet_inherit_port(const struct sock *sk, struct sock *child) ...@@ -163,6 +163,7 @@ int __inet_inherit_port(const struct sock *sk, struct sock *child)
return -ENOMEM; return -ENOMEM;
} }
} }
inet_csk_update_fastreuse(tb, child);
} }
inet_bind_hash(child, tb, port); inet_bind_hash(child, tb, port);
spin_unlock(&head->lock); spin_unlock(&head->lock);
......
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