af_unix: Copy unix_mkname() into unix_find_(bsd|abstract)().

We should not call unix_mkname() before unix_find_other() and instead do
the same thing where necessary based on the address type:

  - terminating the address with '\0' in unix_find_bsd()
  - calculating the hash in unix_find_abstract().
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/unix/af_unix.c

@@ -239,19 +239,25 @@ static int unix_validate_addr(struct sockaddr_un *sunaddr, int addr_len)
 	return 0;
 }
 
-static int unix_mkname(struct sockaddr_un *sunaddr, int len, unsigned int *hashp)
+static void unix_mkname_bsd(struct sockaddr_un *sunaddr, int addr_len)
 {
-	*hashp = 0;
-
-	if (sunaddr->sun_path[0]) {
-		/*
-		 * This may look like an off by one error but it is a bit more
+	/* This may look like an off by one error but it is a bit more
 	 * subtle.  108 is the longest valid AF_UNIX path for a binding.
 	 * sun_path[108] doesn't as such exist.  However in kernel space
 	 * we are guaranteed that it is a valid memory location in our
-		 * kernel address buffer.
+	 * kernel address buffer because syscall functions always pass
+	 * a pointer of struct sockaddr_storage which has a bigger buffer
+	 * than 108.
 	 */
-		((char *)sunaddr)[len] = 0;
+	((char *)sunaddr)[addr_len] = 0;
+}
+
+static int unix_mkname(struct sockaddr_un *sunaddr, int len, unsigned int *hashp)
+{
+	*hashp = 0;
+
+	if (sunaddr->sun_path[0]) {
+		unix_mkname_bsd(sunaddr, len);
 		len = strlen(sunaddr->sun_path) +
 			offsetof(struct sockaddr_un, sun_path) + 1;
 		return len;
@@ -958,13 +964,14 @@ static int unix_release(struct socket *sock)
 }
 
 static struct sock *unix_find_bsd(struct net *net, struct sockaddr_un *sunaddr,
-				  int type)
+				  int addr_len, int type)
 {
 	struct inode *inode;
 	struct path path;
 	struct sock *sk;
 	int err;
 
+	unix_mkname_bsd(sunaddr, addr_len);
 	err = kern_path(sunaddr->sun_path, LOOKUP_FOLLOW, &path);
 	if (err)
 		goto fail;
@@ -1002,9 +1009,9 @@ static struct sock *unix_find_bsd(struct net *net, struct sockaddr_un *sunaddr,
 
 static struct sock *unix_find_abstract(struct net *net,
 				       struct sockaddr_un *sunaddr,
-				       int addr_len, int type,
-				       unsigned int hash)
+				       int addr_len, int type)
 {
+	unsigned int hash = unix_hash_fold(csum_partial(sunaddr, addr_len, 0));
 	struct dentry *dentry;
 	struct sock *sk;
 
@@ -1021,15 +1028,14 @@ static struct sock *unix_find_abstract(struct net *net,
 
 static struct sock *unix_find_other(struct net *net,
 				    struct sockaddr_un *sunaddr,
-				    int addr_len, int type,
-				    unsigned int hash)
+				    int addr_len, int type)
 {
 	struct sock *sk;
 
 	if (sunaddr->sun_path[0])
-		sk = unix_find_bsd(net, sunaddr, type);
+		sk = unix_find_bsd(net, sunaddr, addr_len, type);
 	else
-		sk = unix_find_abstract(net, sunaddr, addr_len, type, hash);
+		sk = unix_find_abstract(net, sunaddr, addr_len, type);
 
 	return sk;
 }
@@ -1246,7 +1252,6 @@ static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr,
 	struct net *net = sock_net(sk);
 	struct sockaddr_un *sunaddr = (struct sockaddr_un *)addr;
 	struct sock *other;
-	unsigned int hash;
 	int err;
 
 	err = -EINVAL;
@@ -1258,11 +1263,6 @@ static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr,
 		if (err)
 			goto out;
 
-		err = unix_mkname(sunaddr, alen, &hash);
-		if (err < 0)
-			goto out;
-		alen = err;
-
 		if (test_bit(SOCK_PASSCRED, &sock->flags) &&
 		    !unix_sk(sk)->addr) {
 			err = unix_autobind(sk);
@@ -1271,7 +1271,7 @@ static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr,
 		}
 
 restart:
-		other = unix_find_other(net, sunaddr, alen, sock->type, hash);
+		other = unix_find_other(net, sunaddr, alen, sock->type);
 		if (IS_ERR(other)) {
 			err = PTR_ERR(other);
 			goto out;
@@ -1365,7 +1365,6 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
 	struct sock *newsk = NULL;
 	struct sock *other = NULL;
 	struct sk_buff *skb = NULL;
-	unsigned int hash;
 	int st;
 	int err;
 	long timeo;
@@ -1374,11 +1373,6 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
 	if (err)
 		goto out;
 
-	err = unix_mkname(sunaddr, addr_len, &hash);
-	if (err < 0)
-		goto out;
-	addr_len = err;
-
 	if (test_bit(SOCK_PASSCRED, &sock->flags) && !u->addr) {
 		err = unix_autobind(sk);
 		if (err)
@@ -1409,7 +1403,7 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
 
 restart:
 	/*  Find listening sock. */
-	other = unix_find_other(net, sunaddr, addr_len, sk->sk_type, hash);
+	other = unix_find_other(net, sunaddr, addr_len, sk->sk_type);
 	if (IS_ERR(other)) {
 		err = PTR_ERR(other);
 		other = NULL;
@@ -1807,9 +1801,7 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
 	struct unix_sock *u = unix_sk(sk);
 	DECLARE_SOCKADDR(struct sockaddr_un *, sunaddr, msg->msg_name);
 	struct sock *other = NULL;
-	int namelen = 0; /* fake GCC */
 	int err;
-	unsigned int hash;
 	struct sk_buff *skb;
 	long timeo;
 	struct scm_cookie scm;
@@ -1829,11 +1821,6 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
 		err = unix_validate_addr(sunaddr, msg->msg_namelen);
 		if (err)
 			goto out;
-
-		err = unix_mkname(sunaddr, msg->msg_namelen, &hash);
-		if (err < 0)
-			goto out;
-		namelen = err;
 	} else {
 		sunaddr = NULL;
 		err = -ENOTCONN;
@@ -1886,8 +1873,8 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
 		if (sunaddr == NULL)
 			goto out_free;
 
-		other = unix_find_other(net, sunaddr, namelen, sk->sk_type,
-					hash);
+		other = unix_find_other(net, sunaddr, msg->msg_namelen,
+					sk->sk_type);
 		if (IS_ERR(other)) {
 			err = PTR_ERR(other);
 			other = NULL;