5 files changed, 63 insertions, 0 deletions

diff --git a/include/net/af_unix.h b/include/net/af_unix.h
index 627ea8e2d915..c270877a5256 100644
--- a/include/net/af_unix.h
+++ b/include/net/af_unix.h
@@ -22,9 +22,17 @@ extern unsigned int unix_tot_inflight;
 
 void unix_inflight(struct user_struct *user, struct file *fp);
 void unix_notinflight(struct user_struct *user, struct file *fp);
+int unix_prepare_fpl(struct scm_fp_list *fpl);
+void unix_destroy_fpl(struct scm_fp_list *fpl);
 void unix_gc(void);
 void wait_for_unix_gc(struct scm_fp_list *fpl);
 
+struct unix_vertex {
+	struct list_head edges;
+	struct list_head entry;
+	unsigned long out_degree;
+};
+
 struct sock *unix_peer_get(struct sock *sk);
 
 #define UNIX_HASH_MOD	(256 - 1)
@@ -62,6 +70,7 @@ struct unix_sock {
 	struct path		path;
 	struct mutex		iolock, bindlock;
 	struct sock		*peer;
+	struct unix_vertex	*vertex;
 	struct list_head	link;
 	unsigned long		inflight;
 	spinlock_t		lock;
diff --git a/include/net/scm.h b/include/net/scm.h
index 92276a2c5543..e34321b6e204 100644
--- a/include/net/scm.h
+++ b/include/net/scm.h
@@ -27,6 +27,9 @@ struct scm_fp_list {
 	short			count;
 	short			count_unix;
 	short			max;
+#ifdef CONFIG_UNIX
+	struct list_head	vertices;
+#endif
 	struct user_struct	*user;
 	struct file		*fp[SCM_MAX_FD];
 };
diff --git a/net/core/scm.c b/net/core/scm.c
index 9cd4b0a01cd6..87dfec1c3378 100644
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -89,6 +89,9 @@ static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp)
 		fpl->count_unix = 0;
 		fpl->max = SCM_MAX_FD;
 		fpl->user = NULL;
+#if IS_ENABLED(CONFIG_UNIX)
+		INIT_LIST_HEAD(&fpl->vertices);
+#endif
 	}
 	fpp = &fpl->fp[fpl->count];
 
@@ -376,8 +379,12 @@ struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
 	if (new_fpl) {
 		for (i = 0; i < fpl->count; i++)
 			get_file(fpl->fp[i]);
+
 		new_fpl->max = new_fpl->count;
 		new_fpl->user = get_uid(fpl->user);
+#if IS_ENABLED(CONFIG_UNIX)
+		INIT_LIST_HEAD(&new_fpl->vertices);
+#endif
 	}
 	return new_fpl;
 }
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 5b41e2321209..a3b25d311560 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -980,6 +980,7 @@ static struct sock *unix_create1(struct net *net, struct socket *sock, int kern,
 	sk->sk_destruct		= unix_sock_destructor;
 	u = unix_sk(sk);
 	u->inflight = 0;
+	u->vertex = NULL;
 	u->path.dentry = NULL;
 	u->path.mnt = NULL;
 	spin_lock_init(&u->lock);
@@ -1805,6 +1806,9 @@ static int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb)
 	for (i = scm->fp->count - 1; i >= 0; i--)
 		unix_inflight(scm->fp->user, scm->fp->fp[i]);
 
+	if (unix_prepare_fpl(UNIXCB(skb).fp))
+		return -ENOMEM;
+
 	return 0;
 }
 
@@ -1815,6 +1819,8 @@ static void unix_detach_fds(struct scm_cookie *scm, struct sk_buff *skb)
 	scm->fp = UNIXCB(skb).fp;
 	UNIXCB(skb).fp = NULL;
 
+	unix_destroy_fpl(scm->fp);
+
 	for (i = scm->fp->count - 1; i >= 0; i--)
 		unix_notinflight(scm->fp->user, scm->fp->fp[i]);
 }
diff --git a/net/unix/garbage.c b/net/unix/garbage.c
index fa39b6265238..75bdf66b81df 100644
--- a/net/unix/garbage.c
+++ b/net/unix/garbage.c
@@ -101,6 +101,44 @@ struct unix_sock *unix_get_socket(struct file *filp)
 	return NULL;
 }
 
+static void unix_free_vertices(struct scm_fp_list *fpl)
+{
+	struct unix_vertex *vertex, *next_vertex;
+
+	list_for_each_entry_safe(vertex, next_vertex, &fpl->vertices, entry) {
+		list_del(&vertex->entry);
+		kfree(vertex);
+	}
+}
+
+int unix_prepare_fpl(struct scm_fp_list *fpl)
+{
+	struct unix_vertex *vertex;
+	int i;
+
+	if (!fpl->count_unix)
+		return 0;
+
+	for (i = 0; i < fpl->count_unix; i++) {
+		vertex = kmalloc(sizeof(*vertex), GFP_KERNEL);
+		if (!vertex)
+			goto err;
+
+		list_add(&vertex->entry, &fpl->vertices);
+	}
+
+	return 0;
+
+err:
+	unix_free_vertices(fpl);
+	return -ENOMEM;
+}
+
+void unix_destroy_fpl(struct scm_fp_list *fpl)
+{
+	unix_free_vertices(fpl);
+}
+
 DEFINE_SPINLOCK(unix_gc_lock);
 unsigned int unix_tot_inflight;
 static LIST_HEAD(gc_candidates);