1 files changed, 358 insertions, 308 deletions

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 7b344035bfe3..8e5151f0c6e4 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -59,7 +59,6 @@
 #include <linux/rhashtable.h>
 #include <asm/cacheflush.h>
 #include <linux/hash.h>
-#include <linux/genetlink.h>
 #include <linux/net_namespace.h>
 #include <linux/nospec.h>
 #include <linux/btf_ids.h>
@@ -73,6 +72,7 @@
 #include <trace/events/netlink.h>
 
 #include "af_netlink.h"
+#include "genetlink.h"
 
 struct listeners {
 	struct rcu_head		rcu;
@@ -84,7 +84,7 @@ struct listeners {
 
 static inline int netlink_is_kernel(struct sock *sk)
 {
-	return nlk_sk(sk)->flags & NETLINK_F_KERNEL_SOCKET;
+	return nlk_test_bit(KERNEL_SOCKET, sk);
 }
 
 struct netlink_table *nl_table __read_mostly;
@@ -130,7 +130,7 @@ static const char *const nlk_cb_mutex_key_strings[MAX_LINKS + 1] = {
 	"nlk_cb_mutex-MAX_LINKS"
 };
 
-static int netlink_dump(struct sock *sk);
+static int netlink_dump(struct sock *sk, bool lock_taken);
 
 /* nl_table locking explained:
  * Lookup and traversal are protected with an RCU read-side lock. Insertion
@@ -159,13 +159,15 @@ EXPORT_SYMBOL(do_trace_netlink_extack);
 
 static inline u32 netlink_group_mask(u32 group)
 {
+	if (group > 32)
+		return 0;
 	return group ? 1 << (group - 1) : 0;
 }
 
 static struct sk_buff *netlink_to_full_skb(const struct sk_buff *skb,
 					   gfp_t gfp_mask)
 {
-	unsigned int len = skb_end_offset(skb);
+	unsigned int len = skb->len;
 	struct sk_buff *new;
 
 	new = alloc_skb(len, gfp_mask);
@@ -347,16 +349,14 @@ static void netlink_deliver_tap_kernel(struct sock *dst, struct sock *src,
 
 static void netlink_overrun(struct sock *sk)
 {
-	struct netlink_sock *nlk = nlk_sk(sk);
-
-	if (!(nlk->flags & NETLINK_F_RECV_NO_ENOBUFS)) {
+	if (!nlk_test_bit(RECV_NO_ENOBUFS, sk)) {
 		if (!test_and_set_bit(NETLINK_S_CONGESTED,
 				      &nlk_sk(sk)->state)) {
-			sk->sk_err = ENOBUFS;
+			WRITE_ONCE(sk->sk_err, ENOBUFS);
 			sk_error_report(sk);
 		}
 	}
-	atomic_inc(&sk->sk_drops);
+	sk_drops_inc(sk);
 }
 
 static void netlink_rcv_wake(struct sock *sk)
@@ -374,7 +374,7 @@ static void netlink_skb_destructor(struct sk_buff *skb)
 	if (is_vmalloc_addr(skb->head)) {
 		if (!skb->cloned ||
 		    !atomic_dec_return(&(skb_shinfo(skb)->dataref)))
-			vfree(skb->head);
+			vfree_atomic(skb->head);
 
 		skb->head = NULL;
 	}
@@ -387,21 +387,11 @@ static void netlink_skb_set_owner_r(struct sk_buff *skb, struct sock *sk)
 	WARN_ON(skb->sk != NULL);
 	skb->sk = sk;
 	skb->destructor = netlink_skb_destructor;
-	atomic_add(skb->truesize, &sk->sk_rmem_alloc);
 	sk_mem_charge(sk, skb->truesize);
 }
 
 static void netlink_sock_destruct(struct sock *sk)
 {
-	struct netlink_sock *nlk = nlk_sk(sk);
-
-	if (nlk->cb_running) {
-		if (nlk->cb.done)
-			nlk->cb.done(&nlk->cb);
-		module_put(nlk->cb.module);
-		kfree_skb(nlk->cb.skb);
-	}
-
 	skb_queue_purge(&sk->sk_receive_queue);
 
 	if (!sock_flag(sk, SOCK_DEAD)) {
@@ -414,14 +404,6 @@ static void netlink_sock_destruct(struct sock *sk)
 	WARN_ON(nlk_sk(sk)->groups);
 }
 
-static void netlink_sock_destruct_work(struct work_struct *work)
-{
-	struct netlink_sock *nlk = container_of(work, struct netlink_sock,
-						work);
-
-	sk_free(&nlk->sk);
-}
-
 /* This lock without WQ_FLAG_EXCLUSIVE is good on UP and it is _very_ bad on
  * SMP. Look, when several writers sleep and reader wakes them up, all but one
  * immediately hit write lock and grab all the cpus. Exclusive sleep solves
@@ -578,7 +560,9 @@ static int netlink_insert(struct sock *sk, u32 portid)
 	if (nlk_sk(sk)->bound)
 		goto err;
 
-	nlk_sk(sk)->portid = portid;
+	/* portid can be read locklessly from netlink_getname(). */
+	WRITE_ONCE(nlk_sk(sk)->portid, portid);
+
 	sock_hold(sk);
 
 	err = __netlink_insert(table, sk);
@@ -612,10 +596,8 @@ static void netlink_remove(struct sock *sk)
 
 	table = &nl_table[sk->sk_protocol];
 	if (!rhashtable_remove_fast(&table->hash, &nlk_sk(sk)->node,
-				    netlink_rhashtable_params)) {
-		WARN_ON(refcount_read(&sk->sk_refcnt) == 1);
+				    netlink_rhashtable_params))
 		__sock_put(sk);
-	}
 
 	netlink_table_grab();
 	if (nlk_sk(sk)->subscriptions) {
@@ -634,8 +616,7 @@ static struct proto netlink_proto = {
 };
 
 static int __netlink_create(struct net *net, struct socket *sock,
-			    struct mutex *cb_mutex, int protocol,
-			    int kern)
+			    int protocol, int kern)
 {
 	struct sock *sk;
 	struct netlink_sock *nlk;
@@ -649,15 +630,10 @@ static int __netlink_create(struct net *net, struct socket *sock,
 	sock_init_data(sock, sk);
 
 	nlk = nlk_sk(sk);
-	if (cb_mutex) {
-		nlk->cb_mutex = cb_mutex;
-	} else {
-		nlk->cb_mutex = &nlk->cb_def_mutex;
-		mutex_init(nlk->cb_mutex);
-		lockdep_set_class_and_name(nlk->cb_mutex,
+	mutex_init(&nlk->nl_cb_mutex);
+	lockdep_set_class_and_name(&nlk->nl_cb_mutex,
 					   nlk_cb_mutex_keys + protocol,
 					   nlk_cb_mutex_key_strings[protocol]);
-	}
 	init_waitqueue_head(&nlk->wait);
 
 	sk->sk_destruct = netlink_sock_destruct;
@@ -669,10 +645,10 @@ static int netlink_create(struct net *net, struct socket *sock, int protocol,
 			  int kern)
 {
 	struct module *module = NULL;
-	struct mutex *cb_mutex;
 	struct netlink_sock *nlk;
 	int (*bind)(struct net *net, int group);
 	void (*unbind)(struct net *net, int group);
+	void (*release)(struct sock *sock, unsigned long *groups);
 	int err = 0;
 
 	sock->state = SS_UNCONNECTED;
@@ -697,15 +673,15 @@ static int netlink_create(struct net *net, struct socket *sock, int protocol,
 		module = nl_table[protocol].module;
 	else
 		err = -EPROTONOSUPPORT;
-	cb_mutex = nl_table[protocol].cb_mutex;
 	bind = nl_table[protocol].bind;
 	unbind = nl_table[protocol].unbind;
+	release = nl_table[protocol].release;
 	netlink_unlock_table();
 
 	if (err < 0)
 		goto out;
 
-	err = __netlink_create(net, sock, cb_mutex, protocol, kern);
+	err = __netlink_create(net, sock, protocol, kern);
 	if (err < 0)
 		goto out_module;
 
@@ -715,6 +691,7 @@ static int netlink_create(struct net *net, struct socket *sock, int protocol,
 	nlk->module = module;
 	nlk->netlink_bind = bind;
 	nlk->netlink_unbind = unbind;
+	nlk->netlink_release = release;
 out:
 	return err;
 
@@ -734,12 +711,6 @@ static void deferred_put_nlk_sk(struct rcu_head *head)
 	if (!refcount_dec_and_test(&sk->sk_refcnt))
 		return;
 
-	if (nlk->cb_running && nlk->cb.done) {
-		INIT_WORK(&nlk->work, netlink_sock_destruct_work);
-		schedule_work(&nlk->work);
-		return;
-	}
-
 	sk_free(sk);
 }
 
@@ -759,6 +730,8 @@ static int netlink_release(struct socket *sock)
 	 * OK. Socket is unlinked, any packets that arrive now
 	 * will be purged.
 	 */
+	if (nlk->netlink_release)
+		nlk->netlink_release(sk, nlk->groups);
 
 	/* must not acquire netlink_table_lock in any way again before unbind
 	 * and notifying genetlink is done as otherwise it might deadlock
@@ -789,6 +762,15 @@ static int netlink_release(struct socket *sock)
 				NETLINK_URELEASE, &n);
 	}
 
+	/* Terminate any outstanding dump */
+	if (nlk->cb_running) {
+		if (nlk->cb.done)
+			nlk->cb.done(&nlk->cb);
+		module_put(nlk->cb.module);
+		kfree_skb(nlk->cb.skb);
+		WRITE_ONCE(nlk->cb_running, false);
+	}
+
 	module_put(nlk->module);
 
 	if (netlink_is_kernel(sk)) {
@@ -810,6 +792,7 @@ static int netlink_release(struct socket *sock)
 	}
 
 	sock_prot_inuse_add(sock_net(sk), &netlink_proto, -1);
+
 	call_rcu(&nlk->rcu, deferred_put_nlk_sk);
 	return 0;
 }
@@ -833,7 +816,7 @@ retry:
 		/* Bind collision, search negative portid values. */
 		if (rover == -4096)
 			/* rover will be in range [S32_MIN, -4097] */
-			rover = S32_MIN + prandom_u32_max(-4096 - S32_MIN);
+			rover = S32_MIN + get_random_u32_below(-4096 - S32_MIN);
 		else if (rover >= -4096)
 			rover = -4097;
 		portid = rover--;
@@ -983,7 +966,7 @@ static void netlink_undo_bind(int group, long unsigned int groups,
 			nlk->netlink_unbind(sock_net(sk), undo + 1);
 }
 
-static int netlink_bind(struct socket *sock, struct sockaddr *addr,
+static int netlink_bind(struct socket *sock, struct sockaddr_unsized *addr,
 			int addr_len)
 {
 	struct sock *sk = sock->sk;
@@ -1071,7 +1054,7 @@ unlock:
 	return err;
 }
 
-static int netlink_connect(struct socket *sock, struct sockaddr *addr,
+static int netlink_connect(struct socket *sock, struct sockaddr_unsized *addr,
 			   int alen, int flags)
 {
 	int err = 0;
@@ -1083,9 +1066,11 @@ static int netlink_connect(struct socket *sock, struct sockaddr *addr,
 		return -EINVAL;
 
 	if (addr->sa_family == AF_UNSPEC) {
-		sk->sk_state	= NETLINK_UNCONNECTED;
-		nlk->dst_portid	= 0;
-		nlk->dst_group  = 0;
+		/* paired with READ_ONCE() in netlink_getsockbyportid() */
+		WRITE_ONCE(sk->sk_state, NETLINK_UNCONNECTED);
+		/* dst_portid and dst_group can be read locklessly */
+		WRITE_ONCE(nlk->dst_portid, 0);
+		WRITE_ONCE(nlk->dst_group, 0);
 		return 0;
 	}
 	if (addr->sa_family != AF_NETLINK)
@@ -1106,9 +1091,11 @@ static int netlink_connect(struct socket *sock, struct sockaddr *addr,
 		err = netlink_autobind(sock);
 
 	if (err == 0) {
-		sk->sk_state	= NETLINK_CONNECTED;
-		nlk->dst_portid = nladdr->nl_pid;
-		nlk->dst_group  = ffs(nladdr->nl_groups);
+		/* paired with READ_ONCE() in netlink_getsockbyportid() */
+		WRITE_ONCE(sk->sk_state, NETLINK_CONNECTED);
+		/* dst_portid and dst_group can be read locklessly */
+		WRITE_ONCE(nlk->dst_portid, nladdr->nl_pid);
+		WRITE_ONCE(nlk->dst_group, ffs(nladdr->nl_groups));
 	}
 
 	return err;
@@ -1125,10 +1112,12 @@ static int netlink_getname(struct socket *sock, struct sockaddr *addr,
 	nladdr->nl_pad = 0;
 
 	if (peer) {
-		nladdr->nl_pid = nlk->dst_portid;
-		nladdr->nl_groups = netlink_group_mask(nlk->dst_group);
+		/* Paired with WRITE_ONCE() in netlink_connect() */
+		nladdr->nl_pid = READ_ONCE(nlk->dst_portid);
+		nladdr->nl_groups = netlink_group_mask(READ_ONCE(nlk->dst_group));
 	} else {
-		nladdr->nl_pid = nlk->portid;
+		/* Paired with WRITE_ONCE() in netlink_insert() */
+		nladdr->nl_pid = READ_ONCE(nlk->portid);
 		netlink_lock_table();
 		nladdr->nl_groups = nlk->groups ? nlk->groups[0] : 0;
 		netlink_unlock_table();
@@ -1155,19 +1144,25 @@ static struct sock *netlink_getsockbyportid(struct sock *ssk, u32 portid)
 
 	/* Don't bother queuing skb if kernel socket has no input function */
 	nlk = nlk_sk(sock);
-	if (sock->sk_state == NETLINK_CONNECTED &&
-	    nlk->dst_portid != nlk_sk(ssk)->portid) {
+	/* dst_portid and sk_state can be changed in netlink_connect() */
+	if (READ_ONCE(sock->sk_state) == NETLINK_CONNECTED &&
+	    READ_ONCE(nlk->dst_portid) != nlk_sk(ssk)->portid) {
 		sock_put(sock);
 		return ERR_PTR(-ECONNREFUSED);
 	}
 	return sock;
 }
 
-struct sock *netlink_getsockbyfilp(struct file *filp)
+struct sock *netlink_getsockbyfd(int fd)
 {
-	struct inode *inode = file_inode(filp);
+	CLASS(fd, f)(fd);
+	struct inode *inode;
 	struct sock *sock;
 
+	if (fd_empty(f))
+		return ERR_PTR(-EBADF);
+
+	inode = file_inode(fd_file(f));
 	if (!S_ISSOCK(inode->i_mode))
 		return ERR_PTR(-ENOTSOCK);
 
@@ -1179,26 +1174,23 @@ struct sock *netlink_getsockbyfilp(struct file *filp)
 	return sock;
 }
 
-static struct sk_buff *netlink_alloc_large_skb(unsigned int size,
-					       int broadcast)
+struct sk_buff *netlink_alloc_large_skb(unsigned int size, int broadcast)
 {
+	size_t head_size = SKB_HEAD_ALIGN(size);
 	struct sk_buff *skb;
 	void *data;
 
-	if (size <= NLMSG_GOODSIZE || broadcast)
+	if (head_size <= PAGE_SIZE || broadcast)
 		return alloc_skb(size, GFP_KERNEL);
 
-	size = SKB_DATA_ALIGN(size) +
-	       SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
-
-	data = vmalloc(size);
-	if (data == NULL)
+	data = kvmalloc(head_size, GFP_KERNEL);
+	if (!data)
 		return NULL;
 
-	skb = __build_skb(data, size);
-	if (skb == NULL)
-		vfree(data);
-	else
+	skb = __build_skb(data, head_size);
+	if (!skb)
+		kvfree(data);
+	else if (is_vmalloc_addr(data))
 		skb->destructor = netlink_skb_destructor;
 
 	return skb;
@@ -1217,41 +1209,48 @@ static struct sk_buff *netlink_alloc_large_skb(unsigned int size,
 int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
 		      long *timeo, struct sock *ssk)
 {
+	DECLARE_WAITQUEUE(wait, current);
 	struct netlink_sock *nlk;
+	unsigned int rmem;
 
 	nlk = nlk_sk(sk);
+	rmem = atomic_add_return(skb->truesize, &sk->sk_rmem_alloc);
 
-	if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
-	     test_bit(NETLINK_S_CONGESTED, &nlk->state))) {
-		DECLARE_WAITQUEUE(wait, current);
-		if (!*timeo) {
-			if (!ssk || netlink_is_kernel(ssk))
-				netlink_overrun(sk);
-			sock_put(sk);
-			kfree_skb(skb);
-			return -EAGAIN;
-		}
-
-		__set_current_state(TASK_INTERRUPTIBLE);
-		add_wait_queue(&nlk->wait, &wait);
+	if ((rmem == skb->truesize || rmem <= READ_ONCE(sk->sk_rcvbuf)) &&
+	    !test_bit(NETLINK_S_CONGESTED, &nlk->state)) {
+		netlink_skb_set_owner_r(skb, sk);
+		return 0;
+	}
 
-		if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
-		     test_bit(NETLINK_S_CONGESTED, &nlk->state)) &&
-		    !sock_flag(sk, SOCK_DEAD))
-			*timeo = schedule_timeout(*timeo);
+	atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
 
-		__set_current_state(TASK_RUNNING);
-		remove_wait_queue(&nlk->wait, &wait);
+	if (!*timeo) {
+		if (!ssk || netlink_is_kernel(ssk))
+			netlink_overrun(sk);
 		sock_put(sk);
+		kfree_skb(skb);
+		return -EAGAIN;
+	}
 
-		if (signal_pending(current)) {
-			kfree_skb(skb);
-			return sock_intr_errno(*timeo);
-		}
-		return 1;
+	__set_current_state(TASK_INTERRUPTIBLE);
+	add_wait_queue(&nlk->wait, &wait);
+	rmem = atomic_read(&sk->sk_rmem_alloc);
+
+	if (((rmem && rmem + skb->truesize > READ_ONCE(sk->sk_rcvbuf)) ||
+	     test_bit(NETLINK_S_CONGESTED, &nlk->state)) &&
+	    !sock_flag(sk, SOCK_DEAD))
+		*timeo = schedule_timeout(*timeo);
+
+	__set_current_state(TASK_RUNNING);
+	remove_wait_queue(&nlk->wait, &wait);
+	sock_put(sk);
+
+	if (signal_pending(current)) {
+		kfree_skb(skb);
+		return sock_intr_errno(*timeo);
 	}
-	netlink_skb_set_owner_r(skb, sk);
-	return 0;
+
+	return 1;
 }
 
 static int __netlink_sendskb(struct sock *sk, struct sk_buff *skb)
@@ -1283,6 +1282,7 @@ static struct sk_buff *netlink_trim(struct sk_buff *skb, gfp_t allocation)
 {
 	int delta;
 
+	skb_assert_len(skb);
 	WARN_ON(skb->sk != NULL);
 	delta = skb->end - skb->tail;
 	if (is_vmalloc_addr(skb->head) || delta * 2 < skb->truesize)
@@ -1311,6 +1311,7 @@ static int netlink_unicast_kernel(struct sock *sk, struct sk_buff *skb,
 	ret = -ECONNREFUSED;
 	if (nlk->netlink_rcv != NULL) {
 		ret = skb->len;
+		atomic_add(skb->truesize, &sk->sk_rmem_alloc);
 		netlink_skb_set_owner_r(skb, sk);
 		NETLINK_CB(skb).sk = ssk;
 		netlink_deliver_tap_kernel(sk, ssk, skb);
@@ -1380,22 +1381,26 @@ EXPORT_SYMBOL_GPL(netlink_has_listeners);
 
 bool netlink_strict_get_check(struct sk_buff *skb)
 {
-	const struct netlink_sock *nlk = nlk_sk(NETLINK_CB(skb).sk);
-
-	return nlk->flags & NETLINK_F_STRICT_CHK;
+	return nlk_test_bit(STRICT_CHK, NETLINK_CB(skb).sk);
 }
 EXPORT_SYMBOL_GPL(netlink_strict_get_check);
 
 static int netlink_broadcast_deliver(struct sock *sk, struct sk_buff *skb)
 {
 	struct netlink_sock *nlk = nlk_sk(sk);
+	unsigned int rmem, rcvbuf;
 
-	if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf &&
+	rmem = atomic_add_return(skb->truesize, &sk->sk_rmem_alloc);
+	rcvbuf = READ_ONCE(sk->sk_rcvbuf);
+
+	if ((rmem == skb->truesize || rmem <= rcvbuf) &&
 	    !test_bit(NETLINK_S_CONGESTED, &nlk->state)) {
 		netlink_skb_set_owner_r(skb, sk);
 		__netlink_sendskb(sk, skb);
-		return atomic_read(&sk->sk_rmem_alloc) > (sk->sk_rcvbuf >> 1);
+		return rmem > (rcvbuf >> 1);
 	}
+
+	atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
 	return -1;
 }
 
@@ -1410,6 +1415,8 @@ struct netlink_broadcast_data {
 	int delivered;
 	gfp_t allocation;
 	struct sk_buff *skb, *skb2;
+	int (*tx_filter)(struct sock *dsk, struct sk_buff *skb, void *data);
+	void *tx_data;
 };
 
 static void do_one_broadcast(struct sock *sk,
@@ -1426,7 +1433,7 @@ static void do_one_broadcast(struct sock *sk,
 		return;
 
 	if (!net_eq(sock_net(sk), p->net)) {
-		if (!(nlk->flags & NETLINK_F_LISTEN_ALL_NSID))
+		if (!nlk_test_bit(LISTEN_ALL_NSID, sk))
 			return;
 
 		if (!peernet_has_id(sock_net(sk), p->net))
@@ -1459,10 +1466,17 @@ static void do_one_broadcast(struct sock *sk,
 		netlink_overrun(sk);
 		/* Clone failed. Notify ALL listeners. */
 		p->failure = 1;
-		if (nlk->flags & NETLINK_F_BROADCAST_SEND_ERROR)
+		if (nlk_test_bit(BROADCAST_SEND_ERROR, sk))
 			p->delivery_failure = 1;
 		goto out;
 	}
+
+	if (p->tx_filter && p->tx_filter(sk, p->skb2, p->tx_data)) {
+		kfree_skb(p->skb2);
+		p->skb2 = NULL;
+		goto out;
+	}
+
 	if (sk_filter(sk, p->skb2)) {
 		kfree_skb(p->skb2);
 		p->skb2 = NULL;
@@ -1474,7 +1488,7 @@ static void do_one_broadcast(struct sock *sk,
 	val = netlink_broadcast_deliver(sk, p->skb2);
 	if (val < 0) {
 		netlink_overrun(sk);
-		if (nlk->flags & NETLINK_F_BROADCAST_SEND_ERROR)
+		if (nlk_test_bit(BROADCAST_SEND_ERROR, sk))
 			p->delivery_failure = 1;
 	} else {
 		p->congested |= val;
@@ -1485,8 +1499,11 @@ out:
 	sock_put(sk);
 }
 
-int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, u32 portid,
-		      u32 group, gfp_t allocation)
+int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb,
+			       u32 portid,
+			       u32 group, gfp_t allocation,
+			       netlink_filter_fn filter,
+			       void *filter_data)
 {
 	struct net *net = sock_net(ssk);
 	struct netlink_broadcast_data info;
@@ -1505,6 +1522,8 @@ int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, u32 portid,
 	info.allocation = allocation;
 	info.skb = skb;
 	info.skb2 = NULL;
+	info.tx_filter = filter;
+	info.tx_data = filter_data;
 
 	/* While we sleep in clone, do not allow to change socket list */
 
@@ -1530,6 +1549,14 @@ int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, u32 portid,
 	}
 	return -ESRCH;
 }
+EXPORT_SYMBOL(netlink_broadcast_filtered);
+
+int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, u32 portid,
+		      u32 group, gfp_t allocation)
+{
+	return netlink_broadcast_filtered(ssk, skb, portid, group, allocation,
+					  NULL, NULL);
+}
 EXPORT_SYMBOL(netlink_broadcast);
 
 struct netlink_set_err_data {
@@ -1554,12 +1581,12 @@ static int do_one_set_err(struct sock *sk, struct netlink_set_err_data *p)
 	    !test_bit(p->group - 1, nlk->groups))
 		goto out;
 
-	if (p->code == ENOBUFS && nlk->flags & NETLINK_F_RECV_NO_ENOBUFS) {
+	if (p->code == ENOBUFS && nlk_test_bit(RECV_NO_ENOBUFS, sk)) {
 		ret = 1;
 		goto out;
 	}
 
-	sk->sk_err = p->code;
+	WRITE_ONCE(sk->sk_err, p->code);
 	sk_error_report(sk);
 out:
 	return ret;
@@ -1578,6 +1605,7 @@ out:
 int netlink_set_err(struct sock *ssk, u32 portid, u32 group, int code)
 {
 	struct netlink_set_err_data info;
+	unsigned long flags;
 	struct sock *sk;
 	int ret = 0;
 
@@ -1587,12 +1615,12 @@ int netlink_set_err(struct sock *ssk, u32 portid, u32 group, int code)
 	/* sk->sk_err wants a positive error value */
 	info.code = -code;
 
-	read_lock(&nl_table_lock);
+	read_lock_irqsave(&nl_table_lock, flags);
 
 	sk_for_each_bound(sk, &nl_table[ssk->sk_protocol].mc_list)
 		ret += do_one_set_err(sk, &info);
 
-	read_unlock(&nl_table_lock);
+	read_unlock_irqrestore(&nl_table_lock, flags);
 	return ret;
 }
 EXPORT_SYMBOL(netlink_set_err);
@@ -1606,10 +1634,7 @@ static void netlink_update_socket_mc(struct netlink_sock *nlk,
 
 	old = test_bit(group - 1, nlk->groups);
 	subscriptions = nlk->subscriptions - old + new;
-	if (new)
-		__set_bit(group - 1, nlk->groups);
-	else
-		__clear_bit(group - 1, nlk->groups);
+	__assign_bit(group - 1, nlk->groups, new);
 	netlink_update_subscriptions(&nlk->sk, subscriptions);
 	netlink_update_listeners(&nlk->sk);
 }
@@ -1620,7 +1645,7 @@ static int netlink_setsockopt(struct socket *sock, int level, int optname,
 	struct sock *sk = sock->sk;
 	struct netlink_sock *nlk = nlk_sk(sk);
 	unsigned int val = 0;
-	int err;
+	int nr = -1;
 
 	if (level != SOL_NETLINK)
 		return -ENOPROTOOPT;
@@ -1631,14 +1656,12 @@ static int netlink_setsockopt(struct socket *sock, int level, int optname,
 
 	switch (optname) {
 	case NETLINK_PKTINFO:
-		if (val)
-			nlk->flags |= NETLINK_F_RECV_PKTINFO;
-		else
-			nlk->flags &= ~NETLINK_F_RECV_PKTINFO;
-		err = 0;
+		nr = NETLINK_F_RECV_PKTINFO;
 		break;
 	case NETLINK_ADD_MEMBERSHIP:
 	case NETLINK_DROP_MEMBERSHIP: {
+		int err;
+
 		if (!netlink_allowed(sock, NL_CFG_F_NONROOT_RECV))
 			return -EPERM;
 		err = netlink_realloc_groups(sk);
@@ -1658,61 +1681,38 @@ static int netlink_setsockopt(struct socket *sock, int level, int optname,
 		if (optname == NETLINK_DROP_MEMBERSHIP && nlk->netlink_unbind)
 			nlk->netlink_unbind(sock_net(sk), val);
 
-		err = 0;
 		break;
 	}
 	case NETLINK_BROADCAST_ERROR:
-		if (val)
-			nlk->flags |= NETLINK_F_BROADCAST_SEND_ERROR;
-		else
-			nlk->flags &= ~NETLINK_F_BROADCAST_SEND_ERROR;
-		err = 0;
+		nr = NETLINK_F_BROADCAST_SEND_ERROR;
 		break;
 	case NETLINK_NO_ENOBUFS:
+		assign_bit(NETLINK_F_RECV_NO_ENOBUFS, &nlk->flags, val);
 		if (val) {
-			nlk->flags |= NETLINK_F_RECV_NO_ENOBUFS;
 			clear_bit(NETLINK_S_CONGESTED, &nlk->state);
 			wake_up_interruptible(&nlk->wait);
-		} else {
-			nlk->flags &= ~NETLINK_F_RECV_NO_ENOBUFS;
 		}
-		err = 0;
 		break;
 	case NETLINK_LISTEN_ALL_NSID:
 		if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_BROADCAST))
 			return -EPERM;
-
-		if (val)
-			nlk->flags |= NETLINK_F_LISTEN_ALL_NSID;
-		else
-			nlk->flags &= ~NETLINK_F_LISTEN_ALL_NSID;
-		err = 0;
+		nr = NETLINK_F_LISTEN_ALL_NSID;
 		break;
 	case NETLINK_CAP_ACK:
-		if (val)
-			nlk->flags |= NETLINK_F_CAP_ACK;
-		else
-			nlk->flags &= ~NETLINK_F_CAP_ACK;
-		err = 0;
+		nr = NETLINK_F_CAP_ACK;
 		break;
 	case NETLINK_EXT_ACK:
-		if (val)
-			nlk->flags |= NETLINK_F_EXT_ACK;
-		else
-			nlk->flags &= ~NETLINK_F_EXT_ACK;
-		err = 0;
+		nr = NETLINK_F_EXT_ACK;
 		break;
 	case NETLINK_GET_STRICT_CHK:
-		if (val)
-			nlk->flags |= NETLINK_F_STRICT_CHK;
-		else
-			nlk->flags &= ~NETLINK_F_STRICT_CHK;
-		err = 0;
+		nr = NETLINK_F_STRICT_CHK;
 		break;
 	default:
-		err = -ENOPROTOOPT;
+		return -ENOPROTOOPT;
 	}
-	return err;
+	if (nr >= 0)
+		assign_bit(nr, &nlk->flags, val);
+	return 0;
 }
 
 static int netlink_getsockopt(struct socket *sock, int level, int optname,
@@ -1720,7 +1720,8 @@ static int netlink_getsockopt(struct socket *sock, int level, int optname,
 {
 	struct sock *sk = sock->sk;
 	struct netlink_sock *nlk = nlk_sk(sk);
-	int len, val, err;
+	unsigned int flag;
+	int len, val;
 
 	if (level != SOL_NETLINK)
 		return -ENOPROTOOPT;
@@ -1732,39 +1733,17 @@ static int netlink_getsockopt(struct socket *sock, int level, int optname,
 
 	switch (optname) {
 	case NETLINK_PKTINFO:
-		if (len < sizeof(int))
-			return -EINVAL;
-		len = sizeof(int);
-		val = nlk->flags & NETLINK_F_RECV_PKTINFO ? 1 : 0;
-		if (put_user(len, optlen) ||
-		    put_user(val, optval))
-			return -EFAULT;
-		err = 0;
+		flag = NETLINK_F_RECV_PKTINFO;
 		break;
 	case NETLINK_BROADCAST_ERROR:
-		if (len < sizeof(int))
-			return -EINVAL;
-		len = sizeof(int);
-		val = nlk->flags & NETLINK_F_BROADCAST_SEND_ERROR ? 1 : 0;
-		if (put_user(len, optlen) ||
-		    put_user(val, optval))
-			return -EFAULT;
-		err = 0;
+		flag = NETLINK_F_BROADCAST_SEND_ERROR;
 		break;
 	case NETLINK_NO_ENOBUFS:
-		if (len < sizeof(int))
-			return -EINVAL;
-		len = sizeof(int);
-		val = nlk->flags & NETLINK_F_RECV_NO_ENOBUFS ? 1 : 0;
-		if (put_user(len, optlen) ||
-		    put_user(val, optval))
-			return -EFAULT;
-		err = 0;
+		flag = NETLINK_F_RECV_NO_ENOBUFS;
 		break;
 	case NETLINK_LIST_MEMBERSHIPS: {
-		int pos, idx, shift;
+		int pos, idx, shift, err = 0;
 
-		err = 0;
 		netlink_lock_table();
 		for (pos = 0; pos * 8 < nlk->ngroups; pos += sizeof(u32)) {
 			if (len - pos < sizeof(u32))
@@ -1778,43 +1757,38 @@ static int netlink_getsockopt(struct socket *sock, int level, int optname,
 				break;
 			}
 		}
-		if (put_user(ALIGN(nlk->ngroups / 8, sizeof(u32)), optlen))
+		if (put_user(ALIGN(BITS_TO_BYTES(nlk->ngroups), sizeof(u32)), optlen))
 			err = -EFAULT;
 		netlink_unlock_table();
-		break;
+		return err;
 	}
+	case NETLINK_LISTEN_ALL_NSID:
+		flag = NETLINK_F_LISTEN_ALL_NSID;
+		break;
 	case NETLINK_CAP_ACK:
-		if (len < sizeof(int))
-			return -EINVAL;
-		len = sizeof(int);
-		val = nlk->flags & NETLINK_F_CAP_ACK ? 1 : 0;
-		if (put_user(len, optlen) ||
-		    put_user(val, optval))
-			return -EFAULT;
-		err = 0;
+		flag = NETLINK_F_CAP_ACK;
 		break;
 	case NETLINK_EXT_ACK:
-		if (len < sizeof(int))
-			return -EINVAL;
-		len = sizeof(int);
-		val = nlk->flags & NETLINK_F_EXT_ACK ? 1 : 0;
-		if (put_user(len, optlen) || put_user(val, optval))
-			return -EFAULT;
-		err = 0;
+		flag = NETLINK_F_EXT_ACK;
 		break;
 	case NETLINK_GET_STRICT_CHK:
-		if (len < sizeof(int))
-			return -EINVAL;
-		len = sizeof(int);
-		val = nlk->flags & NETLINK_F_STRICT_CHK ? 1 : 0;
-		if (put_user(len, optlen) || put_user(val, optval))
-			return -EFAULT;
-		err = 0;
+		flag = NETLINK_F_STRICT_CHK;
 		break;
 	default:
-		err = -ENOPROTOOPT;
+		return -ENOPROTOOPT;
 	}
-	return err;
+
+	if (len < sizeof(int))
+		return -EINVAL;
+
+	len = sizeof(int);
+	val = test_bit(flag, &nlk->flags);
+
+	if (put_user(len, optlen) ||
+	    copy_to_user(optval, &val, len))
+		return -EFAULT;
+
+	return 0;
 }
 
 static void netlink_cmsg_recv_pktinfo(struct msghdr *msg, struct sk_buff *skb)
@@ -1873,8 +1847,9 @@ static int netlink_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
 			goto out;
 		netlink_skb_flags |= NETLINK_SKB_DST;
 	} else {
-		dst_portid = nlk->dst_portid;
-		dst_group = nlk->dst_group;
+		/* Paired with WRITE_ONCE() in netlink_connect() */
+		dst_portid = READ_ONCE(nlk->dst_portid);
+		dst_group = READ_ONCE(nlk->dst_group);
 	}
 
 	/* Paired with WRITE_ONCE() in netlink_insert() */
@@ -1929,8 +1904,7 @@ static int netlink_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 	struct scm_cookie scm;
 	struct sock *sk = sock->sk;
 	struct netlink_sock *nlk = nlk_sk(sk);
-	int noblock = flags & MSG_DONTWAIT;
-	size_t copied;
+	size_t copied, max_recvmsg_len;
 	struct sk_buff *skb, *data_skb;
 	int err, ret;
 
@@ -1939,7 +1913,7 @@ static int netlink_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 
 	copied = 0;
 
-	skb = skb_recv_datagram(sk, flags, noblock, &err);
+	skb = skb_recv_datagram(sk, flags, &err);
 	if (skb == NULL)
 		goto out;
 
@@ -1963,9 +1937,10 @@ static int netlink_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 #endif
 
 	/* Record the max length of recvmsg() calls for future allocations */
-	nlk->max_recvmsg_len = max(nlk->max_recvmsg_len, len);
-	nlk->max_recvmsg_len = min_t(size_t, nlk->max_recvmsg_len,
-				     SKB_WITH_OVERHEAD(32768));
+	max_recvmsg_len = max(READ_ONCE(nlk->max_recvmsg_len), len);
+	max_recvmsg_len = min_t(size_t, max_recvmsg_len,
+				SKB_WITH_OVERHEAD(32768));
+	WRITE_ONCE(nlk->max_recvmsg_len, max_recvmsg_len);
 
 	copied = data_skb->len;
 	if (len < copied) {
@@ -1973,7 +1948,6 @@ static int netlink_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 		copied = len;
 	}
 
-	skb_reset_transport_header(data_skb);
 	err = skb_copy_datagram_msg(data_skb, 0, msg, copied);
 
 	if (msg->msg_name) {
@@ -1985,9 +1959,9 @@ static int netlink_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 		msg->msg_namelen = sizeof(*addr);
 	}
 
-	if (nlk->flags & NETLINK_F_RECV_PKTINFO)
+	if (nlk_test_bit(RECV_PKTINFO, sk))
 		netlink_cmsg_recv_pktinfo(msg, skb);
-	if (nlk->flags & NETLINK_F_LISTEN_ALL_NSID)
+	if (nlk_test_bit(LISTEN_ALL_NSID, sk))
 		netlink_cmsg_listen_all_nsid(sk, msg, skb);
 
 	memset(&scm, 0, sizeof(scm));
@@ -1997,11 +1971,11 @@ static int netlink_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 
 	skb_free_datagram(sk, skb);
 
-	if (nlk->cb_running &&
+	if (READ_ONCE(nlk->cb_running) &&
 	    atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf / 2) {
-		ret = netlink_dump(sk);
+		ret = netlink_dump(sk, false);
 		if (ret) {
-			sk->sk_err = -ret;
+			WRITE_ONCE(sk->sk_err, -ret);
 			sk_error_report(sk);
 		}
 	}
@@ -2031,7 +2005,6 @@ __netlink_kernel_create(struct net *net, int unit, struct module *module,
 	struct sock *sk;
 	struct netlink_sock *nlk;
 	struct listeners *listeners = NULL;
-	struct mutex *cb_mutex = cfg ? cfg->cb_mutex : NULL;
 	unsigned int groups;
 
 	BUG_ON(!nl_table);
@@ -2042,7 +2015,7 @@ __netlink_kernel_create(struct net *net, int unit, struct module *module,
 	if (sock_create_lite(PF_NETLINK, SOCK_DGRAM, unit, &sock))
 		return NULL;
 
-	if (__netlink_create(net, sock, cb_mutex, unit, 1) < 0)
+	if (__netlink_create(net, sock, unit, 1) < 0)
 		goto out_sock_release_nosk;
 
 	sk = sock->sk;
@@ -2064,20 +2037,18 @@ __netlink_kernel_create(struct net *net, int unit, struct module *module,
 		goto out_sock_release;
 
 	nlk = nlk_sk(sk);
-	nlk->flags |= NETLINK_F_KERNEL_SOCKET;
+	set_bit(NETLINK_F_KERNEL_SOCKET, &nlk->flags);
 
 	netlink_table_grab();
 	if (!nl_table[unit].registered) {
 		nl_table[unit].groups = groups;
 		rcu_assign_pointer(nl_table[unit].listeners, listeners);
-		nl_table[unit].cb_mutex = cb_mutex;
 		nl_table[unit].module = module;
 		if (cfg) {
 			nl_table[unit].bind = cfg->bind;
 			nl_table[unit].unbind = cfg->unbind;
+			nl_table[unit].release = cfg->release;
 			nl_table[unit].flags = cfg->flags;
-			if (cfg->compare)
-				nl_table[unit].compare = cfg->compare;
 		}
 		nl_table[unit].registered = 1;
 	} else {
@@ -2158,8 +2129,9 @@ void __netlink_clear_multicast_users(struct sock *ksk, unsigned int group)
 {
 	struct sock *sk;
 	struct netlink_table *tbl = &nl_table[ksk->sk_protocol];
+	struct hlist_node *tmp;
 
-	sk_for_each_bound(sk, &tbl->mc_list)
+	sk_for_each_bound_safe(sk, tmp, &tbl->mc_list)
 		netlink_update_socket_mc(nlk_sk(sk), group, 0);
 }
 
@@ -2181,6 +2153,70 @@ __nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int fla
 }
 EXPORT_SYMBOL(__nlmsg_put);
 
+static size_t
+netlink_ack_tlv_len(struct netlink_sock *nlk, int err,
+		    const struct netlink_ext_ack *extack)
+{
+	size_t tlvlen;
+
+	if (!extack || !test_bit(NETLINK_F_EXT_ACK, &nlk->flags))
+		return 0;
+
+	tlvlen = 0;
+	if (extack->_msg)
+		tlvlen += nla_total_size(strlen(extack->_msg) + 1);
+	if (extack->cookie_len)
+		tlvlen += nla_total_size(extack->cookie_len);
+
+	/* Following attributes are only reported as error (not warning) */
+	if (!err)
+		return tlvlen;
+
+	if (extack->bad_attr)
+		tlvlen += nla_total_size(sizeof(u32));
+	if (extack->policy)
+		tlvlen += netlink_policy_dump_attr_size_estimate(extack->policy);
+	if (extack->miss_type)
+		tlvlen += nla_total_size(sizeof(u32));
+	if (extack->miss_nest)
+		tlvlen += nla_total_size(sizeof(u32));
+
+	return tlvlen;
+}
+
+static bool nlmsg_check_in_payload(const struct nlmsghdr *nlh, const void *addr)
+{
+	return !WARN_ON(addr < nlmsg_data(nlh) ||
+			addr - (const void *) nlh >= nlh->nlmsg_len);
+}
+
+static void
+netlink_ack_tlv_fill(struct sk_buff *skb, const struct nlmsghdr *nlh, int err,
+		     const struct netlink_ext_ack *extack)
+{
+	if (extack->_msg)
+		WARN_ON(nla_put_string(skb, NLMSGERR_ATTR_MSG, extack->_msg));
+	if (extack->cookie_len)
+		WARN_ON(nla_put(skb, NLMSGERR_ATTR_COOKIE,
+				extack->cookie_len, extack->cookie));
+
+	if (!err)
+		return;
+
+	if (extack->bad_attr && nlmsg_check_in_payload(nlh, extack->bad_attr))
+		WARN_ON(nla_put_u32(skb, NLMSGERR_ATTR_OFFS,
+				    (u8 *)extack->bad_attr - (const u8 *)nlh));
+	if (extack->policy)
+		netlink_policy_dump_write_attr(skb, extack->policy,
+					       NLMSGERR_ATTR_POLICY);
+	if (extack->miss_type)
+		WARN_ON(nla_put_u32(skb, NLMSGERR_ATTR_MISS_TYPE,
+				    extack->miss_type));
+	if (extack->miss_nest && nlmsg_check_in_payload(nlh, extack->miss_nest))
+		WARN_ON(nla_put_u32(skb, NLMSGERR_ATTR_MISS_NEST,
+				    (u8 *)extack->miss_nest - (const u8 *)nlh));
+}
+
 /*
  * It looks a bit ugly.
  * It would be better to create kernel thread.
@@ -2191,6 +2227,7 @@ static int netlink_dump_done(struct netlink_sock *nlk, struct sk_buff *skb,
 			     struct netlink_ext_ack *extack)
 {
 	struct nlmsghdr *nlh;
+	size_t extack_len;
 
 	nlh = nlmsg_put_answer(skb, cb, NLMSG_DONE, sizeof(nlk->dump_done_errno),
 			       NLM_F_MULTI | cb->answer_flags);
@@ -2200,45 +2237,50 @@ static int netlink_dump_done(struct netlink_sock *nlk, struct sk_buff *skb,
 	nl_dump_check_consistent(cb, nlh);
 	memcpy(nlmsg_data(nlh), &nlk->dump_done_errno, sizeof(nlk->dump_done_errno));
 
-	if (extack->_msg && nlk->flags & NETLINK_F_EXT_ACK) {
+	extack_len = netlink_ack_tlv_len(nlk, nlk->dump_done_errno, extack);
+	if (extack_len) {
 		nlh->nlmsg_flags |= NLM_F_ACK_TLVS;
-		if (!nla_put_string(skb, NLMSGERR_ATTR_MSG, extack->_msg))
+		if (skb_tailroom(skb) >= extack_len) {
+			netlink_ack_tlv_fill(skb, cb->nlh,
+					     nlk->dump_done_errno, extack);
 			nlmsg_end(skb, nlh);
+		}
 	}
 
 	return 0;
 }
 
-static int netlink_dump(struct sock *sk)
+static int netlink_dump(struct sock *sk, bool lock_taken)
 {
 	struct netlink_sock *nlk = nlk_sk(sk);
 	struct netlink_ext_ack extack = {};
 	struct netlink_callback *cb;
 	struct sk_buff *skb = NULL;
+	unsigned int rmem, rcvbuf;
+	size_t max_recvmsg_len;
 	struct module *module;
 	int err = -ENOBUFS;
 	int alloc_min_size;
 	int alloc_size;
 
-	mutex_lock(nlk->cb_mutex);
+	if (!lock_taken)
+		mutex_lock(&nlk->nl_cb_mutex);
 	if (!nlk->cb_running) {
 		err = -EINVAL;
 		goto errout_skb;
 	}
 
-	if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
-		goto errout_skb;
-
 	/* NLMSG_GOODSIZE is small to avoid high order allocations being
-	 * required, but it makes sense to _attempt_ a 16K bytes allocation
+	 * required, but it makes sense to _attempt_ a 32KiB allocation
 	 * to reduce number of system calls on dump operations, if user
 	 * ever provided a big enough buffer.
 	 */
 	cb = &nlk->cb;
 	alloc_min_size = max_t(int, cb->min_dump_alloc, NLMSG_GOODSIZE);
 
-	if (alloc_min_size < nlk->max_recvmsg_len) {
-		alloc_size = nlk->max_recvmsg_len;
+	max_recvmsg_len = READ_ONCE(nlk->max_recvmsg_len);
+	if (alloc_min_size < max_recvmsg_len) {
+		alloc_size = max_recvmsg_len;
 		skb = alloc_skb(alloc_size,
 				(GFP_KERNEL & ~__GFP_DIRECT_RECLAIM) |
 				__GFP_NOWARN | __GFP_NORETRY);
@@ -2250,8 +2292,15 @@ static int netlink_dump(struct sock *sk)
 	if (!skb)
 		goto errout_skb;
 
+	rcvbuf = READ_ONCE(sk->sk_rcvbuf);
+	rmem = atomic_add_return(skb->truesize, &sk->sk_rmem_alloc);
+	if (rmem != skb->truesize && rmem >= rcvbuf) {
+		atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
+		goto errout_skb;
+	}
+
 	/* Trim skb to allocated size. User is expected to provide buffer as
-	 * large as max(min_dump_alloc, 16KiB (mac_recvmsg_len capped at
+	 * large as max(min_dump_alloc, 32KiB (max_recvmsg_len capped at
 	 * netlink_recvmsg())). dump will pack as many smaller messages as
 	 * could fit within the allocated skb. skb is typically allocated
 	 * with larger space than required (could be as much as near 2x the
@@ -2261,17 +2310,35 @@ static int netlink_dump(struct sock *sk)
 	 * single netdev. The outcome is MSG_TRUNC error.
 	 */
 	skb_reserve(skb, skb_tailroom(skb) - alloc_size);
+
+	/* Make sure malicious BPF programs can not read unitialized memory
+	 * from skb->head -> skb->data
+	 */
+	skb_reset_network_header(skb);
+	skb_reset_mac_header(skb);
+
 	netlink_skb_set_owner_r(skb, sk);
 
 	if (nlk->dump_done_errno > 0) {
 		cb->extack = &extack;
+
 		nlk->dump_done_errno = cb->dump(skb, cb);
+
+		/* EMSGSIZE plus something already in the skb means
+		 * that there's more to dump but current skb has filled up.
+		 * If the callback really wants to return EMSGSIZE to user space
+		 * it needs to do so again, on the next cb->dump() call,
+		 * without putting data in the skb.
+		 */
+		if (nlk->dump_done_errno == -EMSGSIZE && skb->len)
+			nlk->dump_done_errno = skb->len;
+
 		cb->extack = NULL;
 	}
 
 	if (nlk->dump_done_errno > 0 ||
 	    skb_tailroom(skb) < nlmsg_total_size(sizeof(nlk->dump_done_errno))) {
-		mutex_unlock(nlk->cb_mutex);
+		mutex_unlock(&nlk->nl_cb_mutex);
 
 		if (sk_filter(sk, skb))
 			kfree_skb(skb);
@@ -2302,16 +2369,16 @@ static int netlink_dump(struct sock *sk)
 	if (cb->done)
 		cb->done(cb);
 
-	nlk->cb_running = false;
+	WRITE_ONCE(nlk->cb_running, false);
 	module = cb->module;
 	skb = cb->skb;
-	mutex_unlock(nlk->cb_mutex);
+	mutex_unlock(&nlk->nl_cb_mutex);
 	module_put(module);
 	consume_skb(skb);
 	return 0;
 
 errout_skb:
-	mutex_unlock(nlk->cb_mutex);
+	mutex_unlock(&nlk->nl_cb_mutex);
 	kfree_skb(skb);
 	return err;
 }
@@ -2320,8 +2387,8 @@ int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
 			 const struct nlmsghdr *nlh,
 			 struct netlink_dump_control *control)
 {
-	struct netlink_sock *nlk, *nlk2;
 	struct netlink_callback *cb;
+	struct netlink_sock *nlk;
 	struct sock *sk;
 	int ret;
 
@@ -2334,7 +2401,7 @@ int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
 	}
 
 	nlk = nlk_sk(sk);
-	mutex_lock(nlk->cb_mutex);
+	mutex_lock(&nlk->nl_cb_mutex);
 	/* A dump is in progress... */
 	if (nlk->cb_running) {
 		ret = -EBUSY;
@@ -2354,23 +2421,23 @@ int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
 	cb->data = control->data;
 	cb->module = control->module;
 	cb->min_dump_alloc = control->min_dump_alloc;
+	cb->flags = control->flags;
 	cb->skb = skb;
 
-	nlk2 = nlk_sk(NETLINK_CB(skb).sk);
-	cb->strict_check = !!(nlk2->flags & NETLINK_F_STRICT_CHK);
+	cb->strict_check = nlk_test_bit(STRICT_CHK, NETLINK_CB(skb).sk);
 
 	if (control->start) {
+		cb->extack = control->extack;
 		ret = control->start(cb);
+		cb->extack = NULL;
 		if (ret)
 			goto error_put;
 	}
 
-	nlk->cb_running = true;
+	WRITE_ONCE(nlk->cb_running, true);
 	nlk->dump_done_errno = INT_MAX;
 
-	mutex_unlock(nlk->cb_mutex);
-
-	ret = netlink_dump(sk);
+	ret = netlink_dump(sk, true);
 
 	sock_put(sk);
 
@@ -2386,7 +2453,7 @@ error_put:
 	module_put(control->module);
 error_unlock:
 	sock_put(sk);
-	mutex_unlock(nlk->cb_mutex);
+	mutex_unlock(&nlk->nl_cb_mutex);
 error_free:
 	kfree_skb(skb);
 	return ret;
@@ -2400,68 +2467,57 @@ void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
 	struct nlmsghdr *rep;
 	struct nlmsgerr *errmsg;
 	size_t payload = sizeof(*errmsg);
-	size_t tlvlen = 0;
 	struct netlink_sock *nlk = nlk_sk(NETLINK_CB(in_skb).sk);
 	unsigned int flags = 0;
-	bool nlk_has_extack = nlk->flags & NETLINK_F_EXT_ACK;
+	size_t tlvlen;
 
-	/* Error messages get the original request appened, unless the user
+	/* Error messages get the original request appended, unless the user
 	 * requests to cap the error message, and get extra error data if
 	 * requested.
 	 */
-	if (nlk_has_extack && extack && extack->_msg)
-		tlvlen += nla_total_size(strlen(extack->_msg) + 1);
-
-	if (err && !(nlk->flags & NETLINK_F_CAP_ACK))
+	if (err && !test_bit(NETLINK_F_CAP_ACK, &nlk->flags))
 		payload += nlmsg_len(nlh);
 	else
 		flags |= NLM_F_CAPPED;
-	if (err && nlk_has_extack && extack && extack->bad_attr)
-		tlvlen += nla_total_size(sizeof(u32));
-	if (nlk_has_extack && extack && extack->cookie_len)
-		tlvlen += nla_total_size(extack->cookie_len);
-	if (err && nlk_has_extack && extack && extack->policy)
-		tlvlen += netlink_policy_dump_attr_size_estimate(extack->policy);
 
+	tlvlen = netlink_ack_tlv_len(nlk, err, extack);
 	if (tlvlen)
 		flags |= NLM_F_ACK_TLVS;
 
 	skb = nlmsg_new(payload + tlvlen, GFP_KERNEL);
-	if (!skb) {
-		NETLINK_CB(in_skb).sk->sk_err = ENOBUFS;
-		sk_error_report(NETLINK_CB(in_skb).sk);
-		return;
-	}
+	if (!skb)
+		goto err_skb;
 
-	rep = __nlmsg_put(skb, NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
-			  NLMSG_ERROR, payload, flags);
+	rep = nlmsg_put(skb, NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
+			NLMSG_ERROR, sizeof(*errmsg), flags);
+	if (!rep)
+		goto err_bad_put;
 	errmsg = nlmsg_data(rep);
 	errmsg->error = err;
-	memcpy(&errmsg->msg, nlh, payload > sizeof(*errmsg) ? nlh->nlmsg_len : sizeof(*nlh));
+	errmsg->msg = *nlh;
 
-	if (nlk_has_extack && extack) {
-		if (extack->_msg) {
-			WARN_ON(nla_put_string(skb, NLMSGERR_ATTR_MSG,
-					       extack->_msg));
-		}
-		if (err && extack->bad_attr &&
-		    !WARN_ON((u8 *)extack->bad_attr < in_skb->data ||
-			     (u8 *)extack->bad_attr >= in_skb->data +
-						       in_skb->len))
-			WARN_ON(nla_put_u32(skb, NLMSGERR_ATTR_OFFS,
-					    (u8 *)extack->bad_attr -
-					    (u8 *)nlh));
-		if (extack->cookie_len)
-			WARN_ON(nla_put(skb, NLMSGERR_ATTR_COOKIE,
-					extack->cookie_len, extack->cookie));
-		if (extack->policy)
-			netlink_policy_dump_write_attr(skb, extack->policy,
-						       NLMSGERR_ATTR_POLICY);
+	if (!(flags & NLM_F_CAPPED)) {
+		if (!nlmsg_append(skb, nlmsg_len(nlh)))
+			goto err_bad_put;
+
+		memcpy(nlmsg_data(&errmsg->msg), nlmsg_data(nlh),
+		       nlmsg_len(nlh));
 	}
 
+	if (tlvlen)
+		netlink_ack_tlv_fill(skb, nlh, err, extack);
+
 	nlmsg_end(skb, rep);
 
 	nlmsg_unicast(in_skb->sk, skb, NETLINK_CB(in_skb).portid);
+
+	return;
+
+err_bad_put:
+	nlmsg_free(skb);
+err_skb:
+	WRITE_ONCE(NETLINK_CB(in_skb).sk->sk_err, ENOBUFS);
+	sk_error_report(NETLINK_CB(in_skb).sk);
 }
 EXPORT_SYMBOL(netlink_ack);
 
@@ -2651,9 +2707,9 @@ static int netlink_native_seq_show(struct seq_file *seq, void *v)
 			   nlk->groups ? (u32)nlk->groups[0] : 0,
 			   sk_rmem_alloc_get(s),
 			   sk_wmem_alloc_get(s),
-			   nlk->cb_running,
+			   READ_ONCE(nlk->cb_running),
 			   refcount_read(&s->sk_refcnt),
-			   atomic_read(&s->sk_drops),
+			   sk_drops_read(s),
 			   sock_i_ino(s)
 			);
 
@@ -2761,7 +2817,6 @@ static const struct proto_ops netlink_ops = {
 	.sendmsg =	netlink_sendmsg,
 	.recvmsg =	netlink_recvmsg,
 	.mmap =		sock_no_mmap,
-	.sendpage =	sock_no_sendpage,
 };
 
 static const struct net_proto_family netlink_family_ops = {
@@ -2830,8 +2885,7 @@ static const struct rhashtable_params netlink_rhashtable_params = {
 };
 
 #if defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS)
-BTF_ID_LIST(btf_netlink_sock_id)
-BTF_ID(struct, netlink_sock)
+BTF_ID_LIST_SINGLE(btf_netlink_sock_id, struct, netlink_sock)
 
 static const struct bpf_iter_seq_info netlink_seq_info = {
 	.seq_ops		= &netlink_seq_ops,
@@ -2879,12 +2933,8 @@ static int __init netlink_proto_init(void)
 
 	for (i = 0; i < MAX_LINKS; i++) {
 		if (rhashtable_init(&nl_table[i].hash,
-				    &netlink_rhashtable_params) < 0) {
-			while (--i > 0)
-				rhashtable_destroy(&nl_table[i].hash);
-			kfree(nl_table);
+				    &netlink_rhashtable_params) < 0)
 			goto panic;
-		}
 	}
 
 	netlink_add_usersock_entry();