UPSTREAM: af_unix: Save listener for embryo socket.

commit aed6ecef55d70de3762ce41c561b7f547dbaf107 upstream.

This is a prep patch for the following change, where we need to
fetch the listening socket from the successor embryo socket
during GC.

We add a new field to struct unix_sock to save a pointer to a
listening socket.

We set it when connect() creates a new socket, and clear it when
accept() is called.

Bug: 404256079
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/r/20240325202425.60930-8-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 36f924e4bf)
Signed-off-by: Lee Jones <joneslee@google.com>
Change-Id: I14341c883851e56a047d6e2a92c4f6a52c658f67

android/abi_gki_aarch64.stg

@@ -100499,10 +100499,10 @@ member {
   offset: 128
 }
 member {
-  id: 0x80572460
+  id: 0x805723f7
   name: "gc_flags"
   type_id: 0x33756485
-  offset: 8192
+  offset: 8256
 }
 member {
   id: 0x8fd944b0
@@ -112772,10 +112772,10 @@ member {
   offset: 16320
 }
 member {
-  id: 0x79c0c441
+  id: 0x79c0ce48
   name: "inflight"
   type_id: 0x33756485
-  offset: 8064
+  offset: 8128
 }
 member {
   id: 0x79f74293
@@ -123475,17 +123475,17 @@ member {
   type_id: 0xd3c80119
   offset: 1024
 }
-member {
-  id: 0x556d5327
-  name: "link"
-  type_id: 0xd3c80119
-  offset: 7936
-}
 member {
   id: 0x556d57ec
   name: "link"
   type_id: 0xd3c80119
 }
+member {
+  id: 0x556d5b03
+  name: "link"
+  type_id: 0xd3c80119
+  offset: 8000
+}
 member {
   id: 0x556d5d6f
   name: "link"
@@ -124338,6 +124338,12 @@ member {
   type_id: 0x2c912323
   offset: 768
 }
+member {
+  id: 0xe2a2a0b6
+  name: "listener"
+  type_id: 0x1d44326e
+  offset: 7936
+}
 member {
   id: 0xe2a2a2d7
   name: "listener"
@@ -125016,12 +125022,6 @@ member {
   type_id: 0xf313e71a
   offset: 32
 }
-member {
-  id: 0x2d1fe1e3
-  name: "lock"
-  type_id: 0xf313e71a
-  offset: 8128
-}
 member {
   id: 0x2d1fe1f3
   name: "lock"
@@ -125202,6 +125202,12 @@ member {
   type_id: 0xf313e71a
   offset: 320
 }
+member {
+  id: 0x2d1feb84
+  name: "lock"
+  type_id: 0xf313e71a
+  offset: 8192
+}
 member {
   id: 0x2d1feb9a
   name: "lock"
@@ -277505,10 +277511,11 @@ struct_union {
     member_id: 0xd38b8035
     member_id: 0xb794a532
     member_id: 0x5eddc09d
-    member_id: 0x556d5327
-    member_id: 0x79c0c441
-    member_id: 0x2d1fe1e3
-    member_id: 0x80572460
+    member_id: 0xe2a2a0b6
+    member_id: 0x556d5b03
+    member_id: 0x79c0ce48
+    member_id: 0x2d1feb84
+    member_id: 0x805723f7
     member_id: 0x337f3f92
     member_id: 0x6a6786bf
     member_id: 0xac8121db

android/abi_gki_aarch64.stg.allowed_breaks

@@ -179,3 +179,8 @@ type 'struct unix_vertex' changed
   member 'unsigned long lowlink' was added
   member 'bool on_stack' was added
 
+type 'struct unix_sock' changed
+  member 'struct sock* listener' was added
+  4 members ('struct list_head link' .. 'unsigned long gc_flags') changed
+    offset changed by 64
+

include/net/af_unix.h

@@ -84,6 +84,7 @@ struct unix_sock {
 	struct mutex		iolock, bindlock;
 	struct sock		*peer;
 	struct unix_vertex	*vertex;
+	struct sock		*listener;
 	struct list_head	link;
 	unsigned long		inflight;
 	spinlock_t		lock;

net/unix/af_unix.c

@@ -978,6 +978,7 @@ static struct sock *unix_create1(struct net *net, struct socket *sock, int kern,
 	sk->sk_max_ack_backlog	= READ_ONCE(net->unx.sysctl_max_dgram_qlen);
 	sk->sk_destruct		= unix_sock_destructor;
 	u = unix_sk(sk);
+	u->listener = NULL;
 	u->inflight = 0;
 	u->vertex = NULL;
 	u->path.dentry = NULL;
@@ -1582,6 +1583,7 @@ restart:
 	newsk->sk_type		= sk->sk_type;
 	init_peercred(newsk);
 	newu = unix_sk(newsk);
+	newu->listener = other;
 	RCU_INIT_POINTER(newsk->sk_wq, &newu->peer_wq);
 	otheru = unix_sk(other);
 
@@ -1677,8 +1679,8 @@ static int unix_accept(struct socket *sock, struct socket *newsock, int flags,
 		       bool kern)
 {
 	struct sock *sk = sock->sk;
-	struct sock *tsk;
 	struct sk_buff *skb;
+	struct sock *tsk;
 	int err;
 
 	err = -EOPNOTSUPP;
@@ -1703,6 +1705,7 @@ static int unix_accept(struct socket *sock, struct socket *newsock, int flags,
 	}
 
 	tsk = skb->sk;
+	unix_sk(tsk)->listener = NULL;
 	skb_free_datagram(sk, skb);
 	wake_up_interruptible(&unix_sk(sk)->peer_wait);