[PATCH v4 net 3/5] tcp/udp: Call inet6_destroy_sock() in IPv6 sk->sk_destruct().

From: Kuniyuki Iwashima
Date: Tue Oct 04 2022 - 13:19:36 EST

Originally, inet6_sk(sk)->XXX were changed under lock_sock(), so we were
able to clean them up by calling inet6_destroy_sock() during the IPv6 ->
IPv4 conversion by IPV6_ADDRFORM. However, commit 03485f2adcde ("udpv6:
Add lockless sendmsg() support") added a lockless memory allocation path,
which could cause a memory leak:

setsockopt(IPV6_ADDRFORM) sendmsg()
+-----------------------+ +-------+
- do_ipv6_setsockopt(sk, ...) - udpv6_sendmsg(sk, ...)
- lock_sock(sk) ^._ called via udpv6_prot
- WRITE_ONCE(sk->sk_prot, &tcp_prot) before WRITE_ONCE()
- inet6_destroy_sock()
- release_sock(sk) - ip6_make_skb(sk, ...)
^._ lockless fast path for
the non-corking case

- __ip6_append_data(sk, ...)
- ipv6_local_rxpmtu(sk, ...)
- xchg(&np->rxpmtu, skb)
^._ rxpmtu is never freed.

- lock_sock(sk)

For now, rxpmtu is only the case, but not to miss the future change
and a similar bug fixed in commit e27326009a3d ("net: ping6: Fix
memleak in ipv6_renew_options()."), let's set a new function to IPv6
sk->sk_destruct() and call inet6_cleanup_sock() there. Since the
conversion does not change sk->sk_destruct(), we can guarantee that
we can clean up IPv6 resources finally.

We can now remove all inet6_destroy_sock() calls from IPv6 protocol
specific ->destroy() functions, but such changes are invasive to
backport. So they can be posted as a follow-up later for net-next.

Fixes: 03485f2adcde ("udpv6: Add lockless sendmsg() support")
Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
---
Cc: Vladislav Yasevich <vyasevic@xxxxxxxxxx>
---
include/net/ipv6.h | 1 +
include/net/udp.h | 2 +-
include/net/udplite.h | 8 --------
net/ipv4/udp.c | 9 ++++++---
net/ipv4/udplite.c | 8 ++++++++
net/ipv6/af_inet6.c | 9 ++++++++-
net/ipv6/udp.c | 15 ++++++++++++++-
net/ipv6/udp_impl.h | 1 +
net/ipv6/udplite.c | 9 ++++++++-
9 files changed, 47 insertions(+), 15 deletions(-)

diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index dfa70789b771..e7ec3e8cd52e 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -1179,6 +1179,7 @@ void ipv6_local_error(struct sock *sk, int err, struct flowi6 *fl6, u32 info);
void ipv6_local_rxpmtu(struct sock *sk, struct flowi6 *fl6, u32 mtu);

void inet6_cleanup_sock(struct sock *sk);
+void inet6_sock_destruct(struct sock *sk);
int inet6_release(struct socket *sock);
int inet6_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len);
int inet6_getname(struct socket *sock, struct sockaddr *uaddr,
diff --git a/include/net/udp.h b/include/net/udp.h
index 5ee88ddf79c3..fee053bcd17c 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -247,7 +247,7 @@ static inline bool udp_sk_bound_dev_eq(struct net *net, int bound_dev_if,
}

/* net/ipv4/udp.c */
-void udp_destruct_sock(struct sock *sk);
+void udp_destruct_common(struct sock *sk);
void skb_consume_udp(struct sock *sk, struct sk_buff *skb, int len);
int __udp_enqueue_schedule_skb(struct sock *sk, struct sk_buff *skb);
void udp_skb_destructor(struct sock *sk, struct sk_buff *skb);
diff --git a/include/net/udplite.h b/include/net/udplite.h
index 0143b373602e..299c14ce2bb9 100644
--- a/include/net/udplite.h
+++ b/include/net/udplite.h
@@ -25,14 +25,6 @@ static __inline__ int udplite_getfrag(void *from, char *to, int offset,
return copy_from_iter_full(to, len, &msg->msg_iter) ? 0 : -EFAULT;
}

-/* Designate sk as UDP-Lite socket */
-static inline int udplite_sk_init(struct sock *sk)
-{
- udp_init_sock(sk);
- udp_sk(sk)->pcflag = UDPLITE_BIT;
- return 0;
-}
-
/*
* Checksumming routines
*/
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 560d9eadeaa5..48adb418e404 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1598,7 +1598,7 @@ int __udp_enqueue_schedule_skb(struct sock *sk, struct sk_buff *skb)
}
EXPORT_SYMBOL_GPL(__udp_enqueue_schedule_skb);

-void udp_destruct_sock(struct sock *sk)
+void udp_destruct_common(struct sock *sk)
{
/* reclaim completely the forward allocated memory */
struct udp_sock *up = udp_sk(sk);
@@ -1611,10 +1611,14 @@ void udp_destruct_sock(struct sock *sk)
kfree_skb(skb);
}
udp_rmem_release(sk, total, 0, true);
+}
+EXPORT_SYMBOL_GPL(udp_destruct_common);

+static void udp_destruct_sock(struct sock *sk)
+{
+ udp_destruct_common(sk);
inet_sock_destruct(sk);
}
-EXPORT_SYMBOL_GPL(udp_destruct_sock);

int udp_init_sock(struct sock *sk)
{
@@ -1622,7 +1626,6 @@ int udp_init_sock(struct sock *sk)
sk->sk_destruct = udp_destruct_sock;
return 0;
}
-EXPORT_SYMBOL_GPL(udp_init_sock);

void skb_consume_udp(struct sock *sk, struct sk_buff *skb, int len)
{
diff --git a/net/ipv4/udplite.c b/net/ipv4/udplite.c
index 6e08a76ae1e7..4785ac4a8719 100644
--- a/net/ipv4/udplite.c
+++ b/net/ipv4/udplite.c
@@ -17,6 +17,14 @@
struct udp_table udplite_table __read_mostly;
EXPORT_SYMBOL(udplite_table);

+/* Designate sk as UDP-Lite socket */
+static inline int udplite_sk_init(struct sock *sk)
+{
+ udp_init_sock(sk);
+ udp_sk(sk)->pcflag = UDPLITE_BIT;
+ return 0;
+}
+
static int udplite_rcv(struct sk_buff *skb)
{
return __udp4_lib_rcv(skb, &udplite_table, IPPROTO_UDPLITE);
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 83b9e432f3df..ce5378b78ec9 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -109,6 +109,13 @@ static __inline__ struct ipv6_pinfo *inet6_sk_generic(struct sock *sk)
return (struct ipv6_pinfo *)(((u8 *)sk) + offset);
}

+void inet6_sock_destruct(struct sock *sk)
+{
+ inet6_cleanup_sock(sk);
+ inet_sock_destruct(sk);
+}
+EXPORT_SYMBOL_GPL(inet6_sock_destruct);
+
static int inet6_create(struct net *net, struct socket *sock, int protocol,
int kern)
{
@@ -201,7 +208,7 @@ static int inet6_create(struct net *net, struct socket *sock, int protocol,
inet->hdrincl = 1;
}

- sk->sk_destruct = inet_sock_destruct;
+ sk->sk_destruct = inet6_sock_destruct;
sk->sk_family = PF_INET6;
sk->sk_protocol = protocol;

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 3366d6a77ff2..4bdeb66eea34 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -56,6 +56,19 @@
#include <trace/events/skb.h>
#include "udp_impl.h"

+static void udpv6_destruct_sock(struct sock *sk)
+{
+ udp_destruct_common(sk);
+ inet6_sock_destruct(sk);
+}
+
+int udpv6_init_sock(struct sock *sk)
+{
+ skb_queue_head_init(&udp_sk(sk)->reader_queue);
+ sk->sk_destruct = udpv6_destruct_sock;
+ return 0;
+}
+
static u32 udp6_ehashfn(const struct net *net,
const struct in6_addr *laddr,
const u16 lport,
@@ -1723,7 +1736,7 @@ struct proto udpv6_prot = {
.connect = ip6_datagram_connect,
.disconnect = udp_disconnect,
.ioctl = udp_ioctl,
- .init = udp_init_sock,
+ .init = udpv6_init_sock,
.destroy = udpv6_destroy_sock,
.setsockopt = udpv6_setsockopt,
.getsockopt = udpv6_getsockopt,
diff --git a/net/ipv6/udp_impl.h b/net/ipv6/udp_impl.h
index 4251e49d32a0..0590f566379d 100644
--- a/net/ipv6/udp_impl.h
+++ b/net/ipv6/udp_impl.h
@@ -12,6 +12,7 @@ int __udp6_lib_rcv(struct sk_buff *, struct udp_table *, int);
int __udp6_lib_err(struct sk_buff *, struct inet6_skb_parm *, u8, u8, int,
__be32, struct udp_table *);

+int udpv6_init_sock(struct sock *sk);
int udp_v6_get_port(struct sock *sk, unsigned short snum);
void udp_v6_rehash(struct sock *sk);

diff --git a/net/ipv6/udplite.c b/net/ipv6/udplite.c
index b70725856259..67eaf3ca14ce 100644
--- a/net/ipv6/udplite.c
+++ b/net/ipv6/udplite.c
@@ -12,6 +12,13 @@
#include <linux/proc_fs.h>
#include "udp_impl.h"

+static int udplitev6_sk_init(struct sock *sk)
+{
+ udpv6_init_sock(sk);
+ udp_sk(sk)->pcflag = UDPLITE_BIT;
+ return 0;
+}
+
static int udplitev6_rcv(struct sk_buff *skb)
{
return __udp6_lib_rcv(skb, &udplite_table, IPPROTO_UDPLITE);
@@ -38,7 +45,7 @@ struct proto udplitev6_prot = {
.connect = ip6_datagram_connect,
.disconnect = udp_disconnect,
.ioctl = udp_ioctl,
- .init = udplite_sk_init,
+ .init = udplitev6_sk_init,
.destroy = udpv6_destroy_sock,
.setsockopt = udpv6_setsockopt,
.getsockopt = udpv6_getsockopt,
--
2.30.2