[PATCH v5 net 0/5] tcp/udp: Fix memory leaks and data races around IPV6_ADDRFORM.

[PATCH v5 net 0/5] tcp/udp: Fix memory leaks and data races around IPV6_ADDRFORM.

[Kuniyuki Iwashima]

This series fixes some memory leaks and data races caused in the
same scenario where one thread converts an IPv6 socket into IPv4
with IPV6_ADDRFORM and another accesses the socket concurrently.


Changes:
  v5:
    * Patch 1 & 5
      * Rebase and resolve conflicts with 24426654ed3a and 34704ef024ae

    * Patch 3:
      * Remove 'inline' from udplite_sk_init()
      * Remove EXPORT_SYMBOL_GPL(inet6_sock_destruct)

  v4: https://lore.kernel.org/netdev/20221004171802.40968-1-kuniyu@amazon.com/
    * Patch 3:
      * Change UDPv6 Lite's sk->sk_prot->init() and sk->destruct() as well.
      * Move udplite_sk_init() from udplite.h to udplite.c.

  v3 (Resend): https://lore.kernel.org/netdev/20221003154425.49458-1-kuniyu@amazon.com/
    * CC blamed commits' EHOSTUNREACH authors to make patchwork happy

  v3: https://lore.kernel.org/netdev/20220929012542.55424-1-kuniyu@amazon.com/
    * Patch 2:
      * Add comment for np->rxopt.all = 0
      * Add inet6_cleanup_sock()
    * Patch 3:
      * Call inet6_cleanup_sock() instead of inet6_destroy_sock()

  v2: https://lore.kernel.org/netdev/20220928002741.64237-1-kuniyu@amazon.com/
    * Patch 3:
      * Move inet6_destroy_sock() from sk_prot->destroy()
        to sk->sk_destruct() and fix CONFIG_IPV6=m build failure
    * Patch 5:
      * Add WRITE_ONCE()s in tcp_v6_connect()
      * Add Reported-by tags and KCSAN log in changelog

  v1: https://lore.kernel.org/netdev/20220927161209.32939-1-kuniyu@amazon.com/


Kuniyuki Iwashima (5):
  tcp/udp: Fix memory leak in ipv6_renew_options().
  udp: Call inet6_destroy_sock() in setsockopt(IPV6_ADDRFORM).
  tcp/udp: Call inet6_destroy_sock() in IPv6 sk->sk_destruct().
  ipv6: Fix data races around sk->sk_prot.
  tcp: Fix data races around icsk->icsk_af_ops.

 include/net/ipv6.h       |  2 ++
 include/net/udp.h        |  2 +-
 include/net/udplite.h    |  8 --------
 net/core/sock.c          |  6 ++++--
 net/ipv4/af_inet.c       | 23 ++++++++++++++++-------
 net/ipv4/tcp.c           | 10 ++++++----
 net/ipv4/udp.c           |  9 ++++++---
 net/ipv4/udplite.c       |  8 ++++++++
 net/ipv6/af_inet6.c      | 14 +++++++++++++-
 net/ipv6/ipv6_sockglue.c | 34 +++++++++++++++++++---------------
 net/ipv6/tcp_ipv6.c      |  6 ++++--
 net/ipv6/udp.c           | 15 ++++++++++++++-
 net/ipv6/udp_impl.h      |  1 +
 net/ipv6/udplite.c       |  9 ++++++++-
 14 files changed, 102 insertions(+), 45 deletions(-)

-- 
2.30.2

[PATCH v5 net 1/5] tcp/udp: Fix memory leak in ipv6_renew_options().

[Kuniyuki Iwashima]

syzbot reported a memory leak [0] related to IPV6_ADDRFORM.

The scenario is that while one thread is converting an IPv6 socket into
IPv4 with IPV6_ADDRFORM, another thread calls do_ipv6_setsockopt() and
allocates memory to inet6_sk(sk)->XXX after conversion.

Then, the converted sk with (tcp|udp)_prot never frees the IPv6 resources,
which inet6_destroy_sock() should have cleaned up.

setsockopt(IPV6_ADDRFORM)                 setsockopt(IPV6_DSTOPTS)
+-----------------------+                 +----------------------+
- do_ipv6_setsockopt(sk, ...)
  - sockopt_lock_sock(sk)                 - do_ipv6_setsockopt(sk, ...)
    - lock_sock(sk)                         ^._ called via tcpv6_prot
  - WRITE_ONCE(sk->sk_prot, &tcp_prot)          before WRITE_ONCE()
  - xchg(&np->opt, NULL)
  - txopt_put(opt)
  - sockopt_release_sock(sk)
    - release_sock(sk)                      - sockopt_lock_sock(sk)
                                              - lock_sock(sk)
                                            - ipv6_set_opt_hdr(sk, ...)
                                              - ipv6_update_options(sk, opt)
                                                - xchg(&inet6_sk(sk)->opt, opt)
                                                  ^._ opt is never freed.

                                            - sockopt_release_sock(sk)
                                              - release_sock(sk)

Since IPV6_DSTOPTS allocates options under lock_sock(), we can avoid this
memory leak by testing whether sk_family is changed by IPV6_ADDRFORM after
acquiring the lock.

This issue exists from the initial commit between IPV6_ADDRFORM and
IPV6_PKTOPTIONS.

[0]:
BUG: memory leak
unreferenced object 0xffff888009ab9f80 (size 96):
  comm "syz-executor583", pid 328, jiffies 4294916198 (age 13.034s)
  hex dump (first 32 bytes):
    01 00 00 00 48 00 00 00 08 00 00 00 00 00 00 00  ....H...........
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<000000002ee98ae1>] kmalloc include/linux/slab.h:605 [inline]
    [<000000002ee98ae1>] sock_kmalloc+0xb3/0x100 net/core/sock.c:2566
    [<0000000065d7b698>] ipv6_renew_options+0x21e/0x10b0 net/ipv6/exthdrs.c:1318
    [<00000000a8c756d7>] ipv6_set_opt_hdr net/ipv6/ipv6_sockglue.c:354 [inline]
    [<00000000a8c756d7>] do_ipv6_setsockopt.constprop.0+0x28b7/0x4350 net/ipv6/ipv6_sockglue.c:668
    [<000000002854d204>] ipv6_setsockopt+0xdf/0x190 net/ipv6/ipv6_sockglue.c:1021
    [<00000000e69fdcf8>] tcp_setsockopt+0x13b/0x2620 net/ipv4/tcp.c:3789
    [<0000000090da4b9b>] __sys_setsockopt+0x239/0x620 net/socket.c:2252
    [<00000000b10d192f>] __do_sys_setsockopt net/socket.c:2263 [inline]
    [<00000000b10d192f>] __se_sys_setsockopt net/socket.c:2260 [inline]
    [<00000000b10d192f>] __x64_sys_setsockopt+0xbe/0x160 net/socket.c:2260
    [<000000000a80d7aa>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
    [<000000000a80d7aa>] do_syscall_64+0x38/0x90 arch/x86/entry/common.c:80
    [<000000004562b5c6>] entry_SYSCALL_64_after_hwframe+0x63/0xcd

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 net/ipv6/ipv6_sockglue.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index 2d2f4dd9e5df..408345fc4c5c 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -419,6 +419,12 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
 		rtnl_lock();
 	sockopt_lock_sock(sk);
 
+	/* Another thread has converted the socket into IPv4 with
+	 * IPV6_ADDRFORM concurrently.
+	 */
+	if (unlikely(sk->sk_family != AF_INET6))
+		goto unlock;
+
 	switch (optname) {
 
 	case IPV6_ADDRFORM:
@@ -994,6 +1000,7 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
 		break;
 	}
 
+unlock:
 	sockopt_release_sock(sk);
 	if (needs_rtnl)
 		rtnl_unlock();
-- 
2.30.2

[PATCH v5 net 2/5] udp: Call inet6_destroy_sock() in setsockopt(IPV6_ADDRFORM).

[Kuniyuki Iwashima]

Commit 4b340ae20d0e ("IPv6: Complete IPV6_DONTFRAG support") forgot
to add a change to free inet6_sk(sk)->rxpmtu while converting an IPv6
socket into IPv4 with IPV6_ADDRFORM.  After conversion, sk_prot is
changed to udp_prot and ->destroy() never cleans it up, resulting in
a memory leak.

This is due to the discrepancy between inet6_destroy_sock() and
IPV6_ADDRFORM, so let's call inet6_destroy_sock() from IPV6_ADDRFORM
to remove the difference.

However, this is not enough for now because rxpmtu can be changed
without lock_sock() after commit 03485f2adcde ("udpv6: Add lockless
sendmsg() support").  We will fix this case in the following patch.

Note we will rename inet6_destroy_sock() to inet6_cleanup_sock() and
remove unnecessary inet6_destroy_sock() calls in sk_prot->destroy()
in the future.

Fixes: 4b340ae20d0e ("IPv6: Complete IPV6_DONTFRAG support")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
Cc: Brian Haley <brian.haley@hp.com>
---
 include/net/ipv6.h       |  1 +
 net/ipv6/af_inet6.c      |  6 ++++++
 net/ipv6/ipv6_sockglue.c | 20 ++++++++------------
 3 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index d664ba5812d8..335a49ecd8a0 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -1182,6 +1182,7 @@ void ipv6_icmp_error(struct sock *sk, struct sk_buff *skb, int err, __be16 port,
 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);
 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/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index d40b7d60e00e..ded827944fa6 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -510,6 +510,12 @@ void inet6_destroy_sock(struct sock *sk)
 }
 EXPORT_SYMBOL_GPL(inet6_destroy_sock);
 
+void inet6_cleanup_sock(struct sock *sk)
+{
+	inet6_destroy_sock(sk);
+}
+EXPORT_SYMBOL_GPL(inet6_cleanup_sock);
+
 /*
  *	This does both peername and sockname.
  */
diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index 408345fc4c5c..a20edae868fd 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -431,9 +431,6 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
 		if (optlen < sizeof(int))
 			goto e_inval;
 		if (val == PF_INET) {
-			struct ipv6_txoptions *opt;
-			struct sk_buff *pktopt;
-
 			if (sk->sk_type == SOCK_RAW)
 				break;
 
@@ -464,7 +461,6 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
 				break;
 			}
 
-			fl6_free_socklist(sk);
 			__ipv6_sock_mc_close(sk);
 			__ipv6_sock_ac_close(sk);
 
@@ -501,14 +497,14 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
 				sk->sk_socket->ops = &inet_dgram_ops;
 				sk->sk_family = PF_INET;
 			}
-			opt = xchg((__force struct ipv6_txoptions **)&np->opt,
-				   NULL);
-			if (opt) {
-				atomic_sub(opt->tot_len, &sk->sk_omem_alloc);
-				txopt_put(opt);
-			}
-			pktopt = xchg(&np->pktoptions, NULL);
-			kfree_skb(pktopt);
+
+			/* Disable all options not to allocate memory anymore,
+			 * but there is still a race.  See the lockless path
+			 * in udpv6_sendmsg() and ipv6_local_rxpmtu().
+			 */
+			np->rxopt.all = 0;
+
+			inet6_cleanup_sock(sk);
 
 			/*
 			 * ... and add it to the refcnt debug socks count
-- 
2.30.2

[PATCH v5 net 3/5] tcp/udp: Call inet6_destroy_sock() in IPv6 sk->sk_destruct().

[Kuniyuki Iwashima]

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, ...)
  - sockopt_lock_sock(sk)                   ^._ called via udpv6_prot
    - lock_sock(sk)                             before WRITE_ONCE()
  - WRITE_ONCE(sk->sk_prot, &tcp_prot)
  - inet6_destroy_sock()                    - if (!corkreq)
  - sockopt_release_sock(sk)                  - ip6_make_skb(sk, ...)
    - release_sock(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.

                                                - goto out_no_dst;

                                            - 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@amazon.com>
---
Cc: Vladislav Yasevich <vyasevic@redhat.com>
---
 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   |  8 +++++++-
 net/ipv6/udp.c        | 15 ++++++++++++++-
 net/ipv6/udp_impl.h   |  1 +
 net/ipv6/udplite.c    |  9 ++++++++-
 9 files changed, 46 insertions(+), 15 deletions(-)

diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 335a49ecd8a0..37943ba3a73c 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -1183,6 +1183,7 @@ 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 d63118ce5900..8126f67d18b3 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..e0c9cc39b81e 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 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 ded827944fa6..024191004982 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -109,6 +109,12 @@ 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);
+}
+
 static int inet6_create(struct net *net, struct socket *sock, int protocol,
 			int kern)
 {
@@ -201,7 +207,7 @@ 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 91e795bb9ade..8d09f0ea5b8c 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,
@@ -1733,7 +1746,7 @@ 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

[PATCH v5 net 4/5] ipv6: Fix data races around sk->sk_prot.

[Kuniyuki Iwashima]

Commit 086d49058cd8 ("ipv6: annotate some data-races around sk->sk_prot")
fixed some data-races around sk->sk_prot but it was not enough.

Some functions in inet6_(stream|dgram)_ops still access sk->sk_prot
without lock_sock() or rtnl_lock(), so they need READ_ONCE() to avoid
load tearing.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 net/core/sock.c          |  6 ++++--
 net/ipv4/af_inet.c       | 23 ++++++++++++++++-------
 net/ipv6/ipv6_sockglue.c |  4 ++--
 3 files changed, 22 insertions(+), 11 deletions(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index eeb6cbac6f49..a3ba0358c77c 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -3610,7 +3610,8 @@ int sock_common_getsockopt(struct socket *sock, int level, int optname,
 {
 	struct sock *sk = sock->sk;
 
-	return sk->sk_prot->getsockopt(sk, level, optname, optval, optlen);
+	/* IPV6_ADDRFORM can change sk->sk_prot under us. */
+	return READ_ONCE(sk->sk_prot)->getsockopt(sk, level, optname, optval, optlen);
 }
 EXPORT_SYMBOL(sock_common_getsockopt);
 
@@ -3636,7 +3637,8 @@ int sock_common_setsockopt(struct socket *sock, int level, int optname,
 {
 	struct sock *sk = sock->sk;
 
-	return sk->sk_prot->setsockopt(sk, level, optname, optval, optlen);
+	/* IPV6_ADDRFORM can change sk->sk_prot under us. */
+	return READ_ONCE(sk->sk_prot)->setsockopt(sk, level, optname, optval, optlen);
 }
 EXPORT_SYMBOL(sock_common_setsockopt);
 
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index e2c219382345..3dd02396517d 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -558,22 +558,27 @@ int inet_dgram_connect(struct socket *sock, struct sockaddr *uaddr,
 		       int addr_len, int flags)
 {
 	struct sock *sk = sock->sk;
+	const struct proto *prot;
 	int err;
 
 	if (addr_len < sizeof(uaddr->sa_family))
 		return -EINVAL;
+
+	/* IPV6_ADDRFORM can change sk->sk_prot under us. */
+	prot = READ_ONCE(sk->sk_prot);
+
 	if (uaddr->sa_family == AF_UNSPEC)
-		return sk->sk_prot->disconnect(sk, flags);
+		return prot->disconnect(sk, flags);
 
 	if (BPF_CGROUP_PRE_CONNECT_ENABLED(sk)) {
-		err = sk->sk_prot->pre_connect(sk, uaddr, addr_len);
+		err = prot->pre_connect(sk, uaddr, addr_len);
 		if (err)
 			return err;
 	}
 
 	if (data_race(!inet_sk(sk)->inet_num) && inet_autobind(sk))
 		return -EAGAIN;
-	return sk->sk_prot->connect(sk, uaddr, addr_len);
+	return prot->connect(sk, uaddr, addr_len);
 }
 EXPORT_SYMBOL(inet_dgram_connect);
 
@@ -734,10 +739,11 @@ EXPORT_SYMBOL(inet_stream_connect);
 int inet_accept(struct socket *sock, struct socket *newsock, int flags,
 		bool kern)
 {
-	struct sock *sk1 = sock->sk;
+	struct sock *sk1 = sock->sk, *sk2;
 	int err = -EINVAL;
-	struct sock *sk2 = sk1->sk_prot->accept(sk1, flags, &err, kern);
 
+	/* IPV6_ADDRFORM can change sk->sk_prot under us. */
+	sk2 = READ_ONCE(sk1->sk_prot)->accept(sk1, flags, &err, kern);
 	if (!sk2)
 		goto do_err;
 
@@ -825,12 +831,15 @@ ssize_t inet_sendpage(struct socket *sock, struct page *page, int offset,
 		      size_t size, int flags)
 {
 	struct sock *sk = sock->sk;
+	const struct proto *prot;
 
 	if (unlikely(inet_send_prepare(sk)))
 		return -EAGAIN;
 
-	if (sk->sk_prot->sendpage)
-		return sk->sk_prot->sendpage(sk, page, offset, size, flags);
+	/* IPV6_ADDRFORM can change sk->sk_prot under us. */
+	prot = READ_ONCE(sk->sk_prot);
+	if (prot->sendpage)
+		return prot->sendpage(sk, page, offset, size, flags);
 	return sock_no_sendpage(sock, page, offset, size, flags);
 }
 EXPORT_SYMBOL(inet_sendpage);
diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index a20edae868fd..d7207a546aec 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -477,7 +477,7 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
 				sock_prot_inuse_add(net, sk->sk_prot, -1);
 				sock_prot_inuse_add(net, &tcp_prot, 1);
 
-				/* Paired with READ_ONCE(sk->sk_prot) in net/ipv6/af_inet6.c */
+				/* Paired with READ_ONCE(sk->sk_prot) in inet6_stream_ops */
 				WRITE_ONCE(sk->sk_prot, &tcp_prot);
 				icsk->icsk_af_ops = &ipv4_specific;
 				sk->sk_socket->ops = &inet_stream_ops;
@@ -492,7 +492,7 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
 				sock_prot_inuse_add(net, sk->sk_prot, -1);
 				sock_prot_inuse_add(net, prot, 1);
 
-				/* Paired with READ_ONCE(sk->sk_prot) in net/ipv6/af_inet6.c */
+				/* Paired with READ_ONCE(sk->sk_prot) in inet6_dgram_ops */
 				WRITE_ONCE(sk->sk_prot, prot);
 				sk->sk_socket->ops = &inet_dgram_ops;
 				sk->sk_family = PF_INET;
-- 
2.30.2

[PATCH v5 net 5/5] tcp: Fix data races around icsk->icsk_af_ops.

[Kuniyuki Iwashima]

setsockopt(IPV6_ADDRFORM) and tcp_v6_connect() change icsk->icsk_af_ops
under lock_sock(), but tcp_(get|set)sockopt() read it locklessly.  To
avoid load/store tearing, we need to add READ_ONCE() and WRITE_ONCE()
for the reads and writes.

Thanks to Eric Dumazet for providing the syzbot report:

BUG: KCSAN: data-race in tcp_setsockopt / tcp_v6_connect

write to 0xffff88813c624518 of 8 bytes by task 23936 on cpu 0:
tcp_v6_connect+0x5b3/0xce0 net/ipv6/tcp_ipv6.c:240
__inet_stream_connect+0x159/0x6d0 net/ipv4/af_inet.c:660
inet_stream_connect+0x44/0x70 net/ipv4/af_inet.c:724
__sys_connect_file net/socket.c:1976 [inline]
__sys_connect+0x197/0x1b0 net/socket.c:1993
__do_sys_connect net/socket.c:2003 [inline]
__se_sys_connect net/socket.c:2000 [inline]
__x64_sys_connect+0x3d/0x50 net/socket.c:2000
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff88813c624518 of 8 bytes by task 23937 on cpu 1:
tcp_setsockopt+0x147/0x1c80 net/ipv4/tcp.c:3789
sock_common_setsockopt+0x5d/0x70 net/core/sock.c:3585
__sys_setsockopt+0x212/0x2b0 net/socket.c:2252
__do_sys_setsockopt net/socket.c:2263 [inline]
__se_sys_setsockopt net/socket.c:2260 [inline]
__x64_sys_setsockopt+0x62/0x70 net/socket.c:2260
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0xffffffff8539af68 -> 0xffffffff8539aff8

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 23937 Comm: syz-executor.5 Not tainted
6.0.0-rc4-syzkaller-00331-g4ed9c1e971b1-dirty #0

Hardware name: Google Google Compute Engine/Google Compute Engine,
BIOS Google 08/26/2022

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: syzbot <syzkaller@googlegroups.com>
Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 net/ipv4/tcp.c           | 10 ++++++----
 net/ipv6/ipv6_sockglue.c |  3 ++-
 net/ipv6/tcp_ipv6.c      |  6 ++++--
 3 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 0c51abeee172..f8232811a5be 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3796,8 +3796,9 @@ int tcp_setsockopt(struct sock *sk, int level, int optname, sockptr_t optval,
 	const struct inet_connection_sock *icsk = inet_csk(sk);
 
 	if (level != SOL_TCP)
-		return icsk->icsk_af_ops->setsockopt(sk, level, optname,
-						     optval, optlen);
+		/* Paired with WRITE_ONCE() in do_ipv6_setsockopt() and tcp_v6_connect() */
+		return READ_ONCE(icsk->icsk_af_ops)->setsockopt(sk, level, optname,
+								optval, optlen);
 	return do_tcp_setsockopt(sk, level, optname, optval, optlen);
 }
 EXPORT_SYMBOL(tcp_setsockopt);
@@ -4396,8 +4397,9 @@ int tcp_getsockopt(struct sock *sk, int level, int optname, char __user *optval,
 	struct inet_connection_sock *icsk = inet_csk(sk);
 
 	if (level != SOL_TCP)
-		return icsk->icsk_af_ops->getsockopt(sk, level, optname,
-						     optval, optlen);
+		/* Paired with WRITE_ONCE() in do_ipv6_setsockopt() and tcp_v6_connect() */
+		return READ_ONCE(icsk->icsk_af_ops)->getsockopt(sk, level, optname,
+								optval, optlen);
 	return do_tcp_getsockopt(sk, level, optname, USER_SOCKPTR(optval),
 				 USER_SOCKPTR(optlen));
 }
diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index d7207a546aec..532f4478c884 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -479,7 +479,8 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
 
 				/* Paired with READ_ONCE(sk->sk_prot) in inet6_stream_ops */
 				WRITE_ONCE(sk->sk_prot, &tcp_prot);
-				icsk->icsk_af_ops = &ipv4_specific;
+				/* Paired with READ_ONCE() in tcp_(get|set)sockopt() */
+				WRITE_ONCE(icsk->icsk_af_ops, &ipv4_specific);
 				sk->sk_socket->ops = &inet_stream_ops;
 				sk->sk_family = PF_INET;
 				tcp_sync_mss(sk, icsk->icsk_pmtu_cookie);
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index a8adda623da1..2a3f9296df1e 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -238,7 +238,8 @@ static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
 		sin.sin_port = usin->sin6_port;
 		sin.sin_addr.s_addr = usin->sin6_addr.s6_addr32[3];
 
-		icsk->icsk_af_ops = &ipv6_mapped;
+		/* Paired with READ_ONCE() in tcp_(get|set)sockopt() */
+		WRITE_ONCE(icsk->icsk_af_ops, &ipv6_mapped);
 		if (sk_is_mptcp(sk))
 			mptcpv6_handle_mapped(sk, true);
 		sk->sk_backlog_rcv = tcp_v4_do_rcv;
@@ -250,7 +251,8 @@ static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
 
 		if (err) {
 			icsk->icsk_ext_hdr_len = exthdrlen;
-			icsk->icsk_af_ops = &ipv6_specific;
+			/* Paired with READ_ONCE() in tcp_(get|set)sockopt() */
+			WRITE_ONCE(icsk->icsk_af_ops, &ipv6_specific);
 			if (sk_is_mptcp(sk))
 				mptcpv6_handle_mapped(sk, false);
 			sk->sk_backlog_rcv = tcp_v6_do_rcv;
-- 
2.30.2

Re: [PATCH v5 net 2/5] udp: Call inet6_destroy_sock() in setsockopt(IPV6_ADDRFORM).

[Paolo Abeni]

On Thu, 2022-10-06 at 11:53 -0700, Kuniyuki Iwashima wrote:
> Commit 4b340ae20d0e ("IPv6: Complete IPV6_DONTFRAG support") forgot
> to add a change to free inet6_sk(sk)->rxpmtu while converting an IPv6
> socket into IPv4 with IPV6_ADDRFORM.  After conversion, sk_prot is
> changed to udp_prot and ->destroy() never cleans it up, resulting in
> a memory leak.
> 
> This is due to the discrepancy between inet6_destroy_sock() and
> IPV6_ADDRFORM, so let's call inet6_destroy_sock() from IPV6_ADDRFORM
> to remove the difference.
> 
> However, this is not enough for now because rxpmtu can be changed
> without lock_sock() after commit 03485f2adcde ("udpv6: Add lockless
> sendmsg() support").  We will fix this case in the following patch.
> 
> Note we will rename inet6_destroy_sock() to inet6_cleanup_sock() and
> remove unnecessary inet6_destroy_sock() calls in sk_prot->destroy()
> in the future.
> 
> Fixes: 4b340ae20d0e ("IPv6: Complete IPV6_DONTFRAG support")
> Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
> ---
> Cc: Brian Haley <brian.haley@hp.com>
> ---
>  include/net/ipv6.h       |  1 +
>  net/ipv6/af_inet6.c      |  6 ++++++
>  net/ipv6/ipv6_sockglue.c | 20 ++++++++------------
>  3 files changed, 15 insertions(+), 12 deletions(-)
> 
> diff --git a/include/net/ipv6.h b/include/net/ipv6.h
> index d664ba5812d8..335a49ecd8a0 100644
> --- a/include/net/ipv6.h
> +++ b/include/net/ipv6.h
> @@ -1182,6 +1182,7 @@ void ipv6_icmp_error(struct sock *sk, struct sk_buff *skb, int err, __be16 port,
>  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);
>  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/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
> index d40b7d60e00e..ded827944fa6 100644
> --- a/net/ipv6/af_inet6.c
> +++ b/net/ipv6/af_inet6.c
> @@ -510,6 +510,12 @@ void inet6_destroy_sock(struct sock *sk)
>  }
>  EXPORT_SYMBOL_GPL(inet6_destroy_sock);
>  
> +void inet6_cleanup_sock(struct sock *sk)
> +{
> +	inet6_destroy_sock(sk);
> +}
> +EXPORT_SYMBOL_GPL(inet6_cleanup_sock);
> +
>  /*
>   *	This does both peername and sockname.
>   */
> diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
> index 408345fc4c5c..a20edae868fd 100644
> --- a/net/ipv6/ipv6_sockglue.c
> +++ b/net/ipv6/ipv6_sockglue.c
> @@ -431,9 +431,6 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
>  		if (optlen < sizeof(int))
>  			goto e_inval;
>  		if (val == PF_INET) {
> -			struct ipv6_txoptions *opt;
> -			struct sk_buff *pktopt;
> -
>  			if (sk->sk_type == SOCK_RAW)
>  				break;
>  
> @@ -464,7 +461,6 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
>  				break;
>  			}
>  
> -			fl6_free_socklist(sk);
>  			__ipv6_sock_mc_close(sk);
>  			__ipv6_sock_ac_close(sk);
>  
> @@ -501,14 +497,14 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
>  				sk->sk_socket->ops = &inet_dgram_ops;
>  				sk->sk_family = PF_INET;
>  			}
> -			opt = xchg((__force struct ipv6_txoptions **)&np->opt,
> -				   NULL);
> -			if (opt) {
> -				atomic_sub(opt->tot_len, &sk->sk_omem_alloc);
> -				txopt_put(opt);
> -			}
> -			pktopt = xchg(&np->pktoptions, NULL);
> -			kfree_skb(pktopt);
> +
> +			/* Disable all options not to allocate memory anymore,
> +			 * but there is still a race.  See the lockless path
> +			 * in udpv6_sendmsg() and ipv6_local_rxpmtu().
> +			 */
> +			np->rxopt.all = 0;
> +
> +			inet6_cleanup_sock(sk);

I think there still a pending point raised from Eric here. 

"""
Once the v6 socket has been transformed to IPv4 one,
inet6_sock_destruct() is not going to be called.
"""

AFAICS the series is safe Kuniyuki noted:

"""
inet6_sock_destruct() is set to sk->sk_destruct(), which is not changed
by the transformation and will be called from __sk_destruct().
"""
[with the next patch]

@Eric are you fine with the above?

Thanks!

Paolo


>  
>  			/*
>  			 * ... and add it to the refcnt debug socks count

Re: [PATCH v5 net 0/5] tcp/udp: Fix memory leaks and data races around IPV6_ADDRFORM.

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Thu, 6 Oct 2022 11:53:44 -0700 you wrote:
> This series fixes some memory leaks and data races caused in the
> same scenario where one thread converts an IPv6 socket into IPv4
> with IPV6_ADDRFORM and another accesses the socket concurrently.
> 
> 
> Changes:
>   v5:
>     * Patch 1 & 5
>       * Rebase and resolve conflicts with 24426654ed3a and 34704ef024ae
> 
> [...]

Here is the summary with links:
  - [v5,net,1/5] tcp/udp: Fix memory leak in ipv6_renew_options().
    https://git.kernel.org/netdev/net/c/3c52c6bb831f
  - [v5,net,2/5] udp: Call inet6_destroy_sock() in setsockopt(IPV6_ADDRFORM).
    https://git.kernel.org/netdev/net/c/21985f43376c
  - [v5,net,3/5] tcp/udp: Call inet6_destroy_sock() in IPv6 sk->sk_destruct().
    https://git.kernel.org/netdev/net/c/d38afeec26ed
  - [v5,net,4/5] ipv6: Fix data races around sk->sk_prot.
    https://git.kernel.org/netdev/net/c/364f997b5cfe
  - [v5,net,5/5] tcp: Fix data races around icsk->icsk_af_ops.
    https://git.kernel.org/netdev/net/c/f49cd2f4d617

You are awesome, thank you!
-- 
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