net: convert sock.sk_refcnt from atomic_t to refcount_t

refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.

This patch uses refcount_inc_not_zero() instead of
atomic_inc_not_zero_hint() due to absense of a _hint()
version of refcount API. If the hint() version must
be used, we might need to revisit API.

Signed-off-by: Elena Reshetova <[email protected]>
Signed-off-by: Hans Liljestrand <[email protected]>
Signed-off-by: Kees Cook <[email protected]>
Signed-off-by: David Windsor <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

crypto/algif_aead.c

@@ -877,7 +877,7 @@ static void aead_sock_destruct(struct sock *sk)
 	unsigned int ivlen = crypto_aead_ivsize(
 				crypto_aead_reqtfm(&ctx->aead_req));
 
-	WARN_ON(atomic_read(&sk->sk_refcnt) != 0);
+	WARN_ON(refcount_read(&sk->sk_refcnt) != 0);
 	aead_put_sgl(sk);
 	sock_kzfree_s(sk, ctx->iv, ivlen);
 	sock_kfree_s(sk, ctx, ctx->len);

include/net/inet_hashtables.h

@@ -32,7 +32,7 @@
 #include <net/tcp_states.h>
 #include <net/netns/hash.h>
 
-#include <linux/atomic.h>
+#include <linux/refcount.h>
 #include <asm/byteorder.h>
 
 /* This is for all connections with a full identity, no wildcards.
@@ -334,7 +334,7 @@ static inline struct sock *inet_lookup(struct net *net,
 	sk = __inet_lookup(net, hashinfo, skb, doff, saddr, sport, daddr,
 			   dport, dif, &refcounted);
 
-	if (sk && !refcounted && !atomic_inc_not_zero(&sk->sk_refcnt))
+	if (sk && !refcounted && !refcount_inc_not_zero(&sk->sk_refcnt))
 		sk = NULL;
 	return sk;
 }

include/net/request_sock.h

@@ -19,6 +19,7 @@
 #include <linux/spinlock.h>
 #include <linux/types.h>
 #include <linux/bug.h>
+#include <linux/refcount.h>
 
 #include <net/sock.h>
 
@@ -89,7 +90,7 @@ reqsk_alloc(const struct request_sock_ops *ops, struct sock *sk_listener,
 		return NULL;
 	req->rsk_listener = NULL;
 	if (attach_listener) {
-		if (unlikely(!atomic_inc_not_zero(&sk_listener->sk_refcnt))) {
+		if (unlikely(!refcount_inc_not_zero(&sk_listener->sk_refcnt))) {
 			kmem_cache_free(ops->slab, req);
 			return NULL;
 		}
@@ -100,15 +101,15 @@ reqsk_alloc(const struct request_sock_ops *ops, struct sock *sk_listener,
 	sk_node_init(&req_to_sk(req)->sk_node);
 	sk_tx_queue_clear(req_to_sk(req));
 	req->saved_syn = NULL;
-	atomic_set(&req->rsk_refcnt, 0);
+	refcount_set(&req->rsk_refcnt, 0);
 
 	return req;
 }
 
 static inline void reqsk_free(struct request_sock *req)
 {
 	/* temporary debugging */
-	WARN_ON_ONCE(atomic_read(&req->rsk_refcnt) != 0);
+	WARN_ON_ONCE(refcount_read(&req->rsk_refcnt) != 0);
 
 	req->rsk_ops->destructor(req);
 	if (req->rsk_listener)
@@ -119,7 +120,7 @@ static inline void reqsk_free(struct request_sock *req)
 
 static inline void reqsk_put(struct request_sock *req)
 {
-	if (atomic_dec_and_test(&req->rsk_refcnt))
+	if (refcount_dec_and_test(&req->rsk_refcnt))
 		reqsk_free(req);
 }
 

include/net/sock.h

@@ -66,6 +66,7 @@
 #include <linux/poll.h>
 
 #include <linux/atomic.h>
+#include <linux/refcount.h>
 #include <net/dst.h>
 #include <net/checksum.h>
 #include <net/tcp_states.h>
@@ -219,7 +220,7 @@ struct sock_common {
 		u32		skc_tw_rcv_nxt; /* struct tcp_timewait_sock  */
 	};
 
-	atomic_t		skc_refcnt;
+	refcount_t		skc_refcnt;
 	/* private: */
 	int                     skc_dontcopy_end[0];
 	union {
@@ -611,15 +612,15 @@ static inline bool __sk_del_node_init(struct sock *sk)
 
 static __always_inline void sock_hold(struct sock *sk)
 {
-	atomic_inc(&sk->sk_refcnt);
+	refcount_inc(&sk->sk_refcnt);
 }
 
 /* Ungrab socket in the context, which assumes that socket refcnt
    cannot hit zero, f.e. it is true in context of any socketcall.
  */
 static __always_inline void __sock_put(struct sock *sk)
 {
-	atomic_dec(&sk->sk_refcnt);
+	refcount_dec(&sk->sk_refcnt);
 }
 
 static inline bool sk_del_node_init(struct sock *sk)
@@ -628,7 +629,7 @@ static inline bool sk_del_node_init(struct sock *sk)
 
 	if (rc) {
 		/* paranoid for a while -acme */
-		WARN_ON(atomic_read(&sk->sk_refcnt) == 1);
+		WARN_ON(refcount_read(&sk->sk_refcnt) == 1);
 		__sock_put(sk);
 	}
 	return rc;
@@ -650,7 +651,7 @@ static inline bool sk_nulls_del_node_init_rcu(struct sock *sk)
 
 	if (rc) {
 		/* paranoid for a while -acme */
-		WARN_ON(atomic_read(&sk->sk_refcnt) == 1);
+		WARN_ON(refcount_read(&sk->sk_refcnt) == 1);
 		__sock_put(sk);
 	}
 	return rc;
@@ -1144,9 +1145,9 @@ static inline void sk_refcnt_debug_dec(struct sock *sk)
 
 static inline void sk_refcnt_debug_release(const struct sock *sk)
 {
-	if (atomic_read(&sk->sk_refcnt) != 1)
+	if (refcount_read(&sk->sk_refcnt) != 1)
 		printk(KERN_DEBUG "Destruction of the %s socket %p delayed, refcnt=%d\n",
-		       sk->sk_prot->name, sk, atomic_read(&sk->sk_refcnt));
+		       sk->sk_prot->name, sk, refcount_read(&sk->sk_refcnt));
 }
 #else /* SOCK_REFCNT_DEBUG */
 #define sk_refcnt_debug_inc(sk) do { } while (0)
@@ -1636,7 +1637,7 @@ void sock_init_data(struct socket *sock, struct sock *sk);
 /* Ungrab socket and destroy it, if it was the last reference. */
 static inline void sock_put(struct sock *sk)
 {
-	if (atomic_dec_and_test(&sk->sk_refcnt))
+	if (refcount_dec_and_test(&sk->sk_refcnt))
 		sk_free(sk);
 }
 /* Generic version of sock_put(), dealing with all sockets

net/atm/proc.c

@@ -211,7 +211,7 @@ static void vcc_info(struct seq_file *seq, struct atm_vcc *vcc)
 		   vcc->flags, sk->sk_err,
 		   sk_wmem_alloc_get(sk), sk->sk_sndbuf,
 		   sk_rmem_alloc_get(sk), sk->sk_rcvbuf,
-		   atomic_read(&sk->sk_refcnt));
+		   refcount_read(&sk->sk_refcnt));
 }
 
 static void svc_info(struct seq_file *seq, struct atm_vcc *vcc)

net/bluetooth/af_bluetooth.c

@@ -657,7 +657,7 @@ static int bt_seq_show(struct seq_file *seq, void *v)
 		seq_printf(seq,
 			   "%pK %-6d %-6u %-6u %-6u %-6lu %-6lu",
 			   sk,
-			   atomic_read(&sk->sk_refcnt),
+			   refcount_read(&sk->sk_refcnt),
 			   sk_rmem_alloc_get(sk),
 			   sk_wmem_alloc_get(sk),
 			   from_kuid(seq_user_ns(seq), sock_i_uid(sk)),

net/bluetooth/rfcomm/sock.c

@@ -197,7 +197,7 @@ static void rfcomm_sock_kill(struct sock *sk)
 	if (!sock_flag(sk, SOCK_ZAPPED) || sk->sk_socket)
 		return;
 
-	BT_DBG("sk %p state %d refcnt %d", sk, sk->sk_state, atomic_read(&sk->sk_refcnt));
+	BT_DBG("sk %p state %d refcnt %d", sk, sk->sk_state, refcount_read(&sk->sk_refcnt));
 
 	/* Kill poor orphan */
 	bt_sock_unlink(&rfcomm_sk_list, sk);

net/core/skbuff.c

@@ -3844,7 +3844,7 @@ struct sk_buff *skb_clone_sk(struct sk_buff *skb)
 	struct sock *sk = skb->sk;
 	struct sk_buff *clone;
 
-	if (!sk || !atomic_inc_not_zero(&sk->sk_refcnt))
+	if (!sk || !refcount_inc_not_zero(&sk->sk_refcnt))
 		return NULL;
 
 	clone = skb_clone(skb, GFP_ATOMIC);
@@ -3915,7 +3915,7 @@ void skb_complete_tx_timestamp(struct sk_buff *skb,
 	/* Take a reference to prevent skb_orphan() from freeing the socket,
 	 * but only if the socket refcount is not zero.
 	 */
-	if (likely(atomic_inc_not_zero(&sk->sk_refcnt))) {
+	if (likely(refcount_inc_not_zero(&sk->sk_refcnt))) {
 		*skb_hwtstamps(skb) = *hwtstamps;
 		__skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND, false);
 		sock_put(sk);
@@ -3997,7 +3997,7 @@ void skb_complete_wifi_ack(struct sk_buff *skb, bool acked)
 	/* Take a reference to prevent skb_orphan() from freeing the socket,
 	 * but only if the socket refcount is not zero.
 	 */
-	if (likely(atomic_inc_not_zero(&sk->sk_refcnt))) {
+	if (likely(refcount_inc_not_zero(&sk->sk_refcnt))) {
 		err = sock_queue_err_skb(sk, skb);
 		sock_put(sk);
 	}

net/core/sock.c

@@ -1708,7 +1708,7 @@ struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority)
 		 * (Documentation/RCU/rculist_nulls.txt for details)
 		 */
 		smp_wmb();
-		atomic_set(&newsk->sk_refcnt, 2);
+		refcount_set(&newsk->sk_refcnt, 2);
 
 		/*
 		 * Increment the counter in the same struct proto as the master
@@ -1851,7 +1851,7 @@ void skb_orphan_partial(struct sk_buff *skb)
 		) {
 		struct sock *sk = skb->sk;
 
-		if (atomic_inc_not_zero(&sk->sk_refcnt)) {
+		if (refcount_inc_not_zero(&sk->sk_refcnt)) {
 			WARN_ON(refcount_sub_and_test(skb->truesize, &sk->sk_wmem_alloc));
 			skb->destructor = sock_efree;
 		}
@@ -2687,7 +2687,7 @@ void sock_init_data(struct socket *sock, struct sock *sk)
 	 * (Documentation/RCU/rculist_nulls.txt for details)
 	 */
 	smp_wmb();
-	atomic_set(&sk->sk_refcnt, 1);
+	refcount_set(&sk->sk_refcnt, 1);
 	atomic_set(&sk->sk_drops, 0);
 }
 EXPORT_SYMBOL(sock_init_data);

net/ipv4/inet_connection_sock.c

@@ -756,7 +756,7 @@ static void reqsk_queue_hash_req(struct request_sock *req,
 	 * are committed to memory and refcnt initialized.
 	 */
 	smp_wmb();
-	atomic_set(&req->rsk_refcnt, 2 + 1);
+	refcount_set(&req->rsk_refcnt, 2 + 1);
 }
 
 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,

net/ipv4/inet_hashtables.c

@@ -246,7 +246,7 @@ EXPORT_SYMBOL_GPL(__inet_lookup_listener);
 /* All sockets share common refcount, but have different destructors */
 void sock_gen_put(struct sock *sk)
 {
-	if (!atomic_dec_and_test(&sk->sk_refcnt))
+	if (!refcount_dec_and_test(&sk->sk_refcnt))
 		return;
 
 	if (sk->sk_state == TCP_TIME_WAIT)
@@ -287,7 +287,7 @@ struct sock *__inet_lookup_established(struct net *net,
 			continue;
 		if (likely(INET_MATCH(sk, net, acookie,
 				      saddr, daddr, ports, dif))) {
-			if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt)))
+			if (unlikely(!refcount_inc_not_zero(&sk->sk_refcnt)))
 				goto out;
 			if (unlikely(!INET_MATCH(sk, net, acookie,
 						 saddr, daddr, ports, dif))) {

net/ipv4/inet_timewait_sock.c

@@ -76,7 +76,7 @@ void inet_twsk_free(struct inet_timewait_sock *tw)
 
 void inet_twsk_put(struct inet_timewait_sock *tw)
 {
-	if (atomic_dec_and_test(&tw->tw_refcnt))
+	if (refcount_dec_and_test(&tw->tw_refcnt))
 		inet_twsk_free(tw);
 }
 EXPORT_SYMBOL_GPL(inet_twsk_put);
@@ -131,7 +131,7 @@ void __inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk,
 	 * We can use atomic_set() because prior spin_lock()/spin_unlock()
 	 * committed into memory all tw fields.
 	 */
-	atomic_set(&tw->tw_refcnt, 4);
+	refcount_set(&tw->tw_refcnt, 4);
 	inet_twsk_add_node_rcu(tw, &ehead->chain);
 
 	/* Step 3: Remove SK from hash chain */
@@ -195,7 +195,7 @@ struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk,
 		 * to a non null value before everything is setup for this
 		 * timewait socket.
 		 */
-		atomic_set(&tw->tw_refcnt, 0);
+		refcount_set(&tw->tw_refcnt, 0);
 
 		__module_get(tw->tw_prot->owner);
 	}
@@ -278,7 +278,7 @@ void inet_twsk_purge(struct inet_hashinfo *hashinfo, int family)
 				atomic_read(&twsk_net(tw)->count))
 				continue;
 
-			if (unlikely(!atomic_inc_not_zero(&tw->tw_refcnt)))
+			if (unlikely(!refcount_inc_not_zero(&tw->tw_refcnt)))
 				continue;
 
 			if (unlikely((tw->tw_family != family) ||

net/ipv4/ping.c

@@ -290,7 +290,7 @@ void ping_close(struct sock *sk, long timeout)
 {
 	pr_debug("ping_close(sk=%p,sk->num=%u)\n",
 		 inet_sk(sk), inet_sk(sk)->inet_num);
-	pr_debug("isk->refcnt = %d\n", sk->sk_refcnt.counter);
+	pr_debug("isk->refcnt = %d\n", refcount_read(&sk->sk_refcnt));
 
 	sk_common_release(sk);
 }
@@ -1127,7 +1127,7 @@ static void ping_v4_format_sock(struct sock *sp, struct seq_file *f,
 		0, 0L, 0,
 		from_kuid_munged(seq_user_ns(f), sock_i_uid(sp)),
 		0, sock_i_ino(sp),
-		atomic_read(&sp->sk_refcnt), sp,
+		refcount_read(&sp->sk_refcnt), sp,
 		atomic_read(&sp->sk_drops));
 }
 

net/ipv4/raw.c

@@ -1063,7 +1063,7 @@ static void raw_sock_seq_show(struct seq_file *seq, struct sock *sp, int i)
 		0, 0L, 0,
 		from_kuid_munged(seq_user_ns(seq), sock_i_uid(sp)),
 		0, sock_i_ino(sp),
-		atomic_read(&sp->sk_refcnt), sp, atomic_read(&sp->sk_drops));
+		refcount_read(&sp->sk_refcnt), sp, atomic_read(&sp->sk_drops));
 }
 
 static int raw_seq_show(struct seq_file *seq, void *v)

net/ipv4/syncookies.c

@@ -213,7 +213,7 @@ struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
 	child = icsk->icsk_af_ops->syn_recv_sock(sk, skb, req, dst,
 						 NULL, &own_req);
 	if (child) {
-		atomic_set(&req->rsk_refcnt, 1);
+		refcount_set(&req->rsk_refcnt, 1);
 		tcp_sk(child)->tsoffset = tsoff;
 		sock_rps_save_rxhash(child, skb);
 		inet_csk_reqsk_queue_add(sk, req, child);

net/ipv4/tcp_fastopen.c

@@ -214,7 +214,7 @@ static struct sock *tcp_fastopen_create_child(struct sock *sk,
 	inet_csk_reset_xmit_timer(child, ICSK_TIME_RETRANS,
 				  TCP_TIMEOUT_INIT, TCP_RTO_MAX);
 
-	atomic_set(&req->rsk_refcnt, 2);
+	refcount_set(&req->rsk_refcnt, 2);
 
 	/* Now finish processing the fastopen child socket. */
 	inet_csk(child)->icsk_af_ops->rebuild_header(child);

net/ipv4/tcp_ipv4.c

@@ -2323,7 +2323,7 @@ static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i)
 		from_kuid_munged(seq_user_ns(f), sock_i_uid(sk)),
 		icsk->icsk_probes_out,
 		sock_i_ino(sk),
-		atomic_read(&sk->sk_refcnt), sk,
+		refcount_read(&sk->sk_refcnt), sk,
 		jiffies_to_clock_t(icsk->icsk_rto),
 		jiffies_to_clock_t(icsk->icsk_ack.ato),
 		(icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong,
@@ -2349,7 +2349,7 @@ static void get_timewait4_sock(const struct inet_timewait_sock *tw,
 		" %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK",
 		i, src, srcp, dest, destp, tw->tw_substate, 0, 0,
 		3, jiffies_delta_to_clock_t(delta), 0, 0, 0, 0,
-		atomic_read(&tw->tw_refcnt), tw);
+		refcount_read(&tw->tw_refcnt), tw);
 }
 
 #define TMPSZ 150

net/ipv4/udp.c

@@ -577,7 +577,7 @@ struct sock *udp4_lib_lookup(struct net *net, __be32 saddr, __be16 sport,
 
 	sk = __udp4_lib_lookup(net, saddr, sport, daddr, dport,
 			       dif, &udp_table, NULL);
-	if (sk && !atomic_inc_not_zero(&sk->sk_refcnt))
+	if (sk && !refcount_inc_not_zero(&sk->sk_refcnt))
 		sk = NULL;
 	return sk;
 }
@@ -2242,7 +2242,7 @@ void udp_v4_early_demux(struct sk_buff *skb)
 					     uh->source, iph->saddr, dif);
 	}
 
-	if (!sk || !atomic_inc_not_zero_hint(&sk->sk_refcnt, 2))
+	if (!sk || !refcount_inc_not_zero(&sk->sk_refcnt))
 		return;
 
 	skb->sk = sk;
@@ -2691,7 +2691,7 @@ static void udp4_format_sock(struct sock *sp, struct seq_file *f,
 		0, 0L, 0,
 		from_kuid_munged(seq_user_ns(f), sock_i_uid(sp)),
 		0, sock_i_ino(sp),
-		atomic_read(&sp->sk_refcnt), sp,
+		refcount_read(&sp->sk_refcnt), sp,
 		atomic_read(&sp->sk_drops));
 }
 

net/ipv4/udp_diag.c

@@ -55,7 +55,7 @@ static int udp_dump_one(struct udp_table *tbl, struct sk_buff *in_skb,
 				req->id.idiag_dport,
 				req->id.idiag_if, tbl, NULL);
 #endif
-	if (sk && !atomic_inc_not_zero(&sk->sk_refcnt))
+	if (sk && !refcount_inc_not_zero(&sk->sk_refcnt))
 		sk = NULL;
 	rcu_read_unlock();
 	err = -ENOENT;
@@ -206,7 +206,7 @@ static int __udp_diag_destroy(struct sk_buff *in_skb,
 		return -EINVAL;
 	}
 
-	if (sk && !atomic_inc_not_zero(&sk->sk_refcnt))
+	if (sk && !refcount_inc_not_zero(&sk->sk_refcnt))
 		sk = NULL;
 
 	rcu_read_unlock();