netdev - [PATCH 03/51] sctp: pass a kernel pointer to __sctp_setsockopt

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Date:   Sun, 19 Jul 2020 09:21:40 +0200
From:   Christoph Hellwig <hch@....de>
To:     Vlad Yasevich <vyasevich@...il.com>,
        Neil Horman <nhorman@...driver.com>,
        Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        David Laight <David.Laight@...LAB.COM>,
        linux-sctp@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH 03/51] sctp: pass a kernel pointer to __sctp_setsockopt_connectx

Use the kernel pointer that sctp_setsockopt has available instead of
directly handling the user pointer.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 net/sctp/socket.c | 50 ++++++++++++++++++-----------------------------
 1 file changed, 19 insertions(+), 31 deletions(-)

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 85ba5155b177b1..44cf2848146a91 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -1286,36 +1286,29 @@ static int __sctp_connect(struct sock *sk, struct sockaddr *kaddrs,
  * it.
  *
  * sk        The sk of the socket
- * addrs     The pointer to the addresses in user land
+ * addrs     The pointer to the addresses
  * addrssize Size of the addrs buffer
  *
  * Returns >=0 if ok, <0 errno code on error.
  */
-static int __sctp_setsockopt_connectx(struct sock *sk,
-				      struct sockaddr __user *addrs,
-				      int addrs_size,
-				      sctp_assoc_t *assoc_id)
+static int __sctp_setsockopt_connectx(struct sock *sk, struct sockaddr *kaddrs,
+				      int addrs_size, sctp_assoc_t *assoc_id)
 {
-	struct sockaddr *kaddrs;
 	int err = 0, flags = 0;
 
 	pr_debug("%s: sk:%p addrs:%p addrs_size:%d\n",
-		 __func__, sk, addrs, addrs_size);
+		 __func__, sk, kaddrs, addrs_size);
 
 	/* make sure the 1st addr's sa_family is accessible later */
 	if (unlikely(addrs_size < sizeof(sa_family_t)))
 		return -EINVAL;
 
-	kaddrs = memdup_user(addrs, addrs_size);
-	if (IS_ERR(kaddrs))
-		return PTR_ERR(kaddrs);
-
 	/* Allow security module to validate connectx addresses. */
 	err = security_sctp_bind_connect(sk, SCTP_SOCKOPT_CONNECTX,
 					 (struct sockaddr *)kaddrs,
 					  addrs_size);
 	if (err)
-		goto out_free;
+		return err;
 
 	/* in-kernel sockets don't generally have a file allocated to them
 	 * if all they do is call sock_create_kern().
@@ -1323,12 +1316,7 @@ static int __sctp_setsockopt_connectx(struct sock *sk,
 	if (sk->sk_socket->file)
 		flags = sk->sk_socket->file->f_flags;
 
-	err = __sctp_connect(sk, kaddrs, addrs_size, flags, assoc_id);
-
-out_free:
-	kfree(kaddrs);
-
-	return err;
+	return __sctp_connect(sk, kaddrs, addrs_size, flags, assoc_id);
 }
 
 /*
@@ -1336,10 +1324,10 @@ static int __sctp_setsockopt_connectx(struct sock *sk,
  * to the option that doesn't provide association id.
  */
 static int sctp_setsockopt_connectx_old(struct sock *sk,
-					struct sockaddr __user *addrs,
+					struct sockaddr *kaddrs,
 					int addrs_size)
 {
-	return __sctp_setsockopt_connectx(sk, addrs, addrs_size, NULL);
+	return __sctp_setsockopt_connectx(sk, kaddrs, addrs_size, NULL);
 }
 
 /*
@@ -1349,13 +1337,13 @@ static int sctp_setsockopt_connectx_old(struct sock *sk,
  * always positive.
  */
 static int sctp_setsockopt_connectx(struct sock *sk,
-				    struct sockaddr __user *addrs,
+				    struct sockaddr *kaddrs,
 				    int addrs_size)
 {
 	sctp_assoc_t assoc_id = 0;
 	int err = 0;
 
-	err = __sctp_setsockopt_connectx(sk, addrs, addrs_size, &assoc_id);
+	err = __sctp_setsockopt_connectx(sk, kaddrs, addrs_size, &assoc_id);
 
 	if (err)
 		return err;
@@ -1385,6 +1373,7 @@ static int sctp_getsockopt_connectx3(struct sock *sk, int len,
 {
 	struct sctp_getaddrs_old param;
 	sctp_assoc_t assoc_id = 0;
+	struct sockaddr *kaddrs;
 	int err = 0;
 
 #ifdef CONFIG_COMPAT
@@ -1408,9 +1397,12 @@ static int sctp_getsockopt_connectx3(struct sock *sk, int len,
 			return -EFAULT;
 	}
 
-	err = __sctp_setsockopt_connectx(sk, (struct sockaddr __user *)
-					 param.addrs, param.addr_num,
-					 &assoc_id);
+	kaddrs = memdup_user(param.addrs, param.addr_num);
+	if (IS_ERR(kaddrs))
+		return PTR_ERR(kaddrs);
+
+	err = __sctp_setsockopt_connectx(sk, kaddrs, param.addr_num, &assoc_id);
+	kfree(kaddrs);
 	if (err == 0 || err == -EINPROGRESS) {
 		if (copy_to_user(optval, &assoc_id, sizeof(assoc_id)))
 			return -EFAULT;
@@ -4700,16 +4692,12 @@ static int sctp_setsockopt(struct sock *sk, int level, int optname,
 
 	case SCTP_SOCKOPT_CONNECTX_OLD:
 		/* 'optlen' is the size of the addresses buffer. */
-		retval = sctp_setsockopt_connectx_old(sk,
-					    (struct sockaddr __user *)optval,
-					    optlen);
+		retval = sctp_setsockopt_connectx_old(sk, kopt, optlen);
 		break;
 
 	case SCTP_SOCKOPT_CONNECTX:
 		/* 'optlen' is the size of the addresses buffer. */
-		retval = sctp_setsockopt_connectx(sk,
-					    (struct sockaddr __user *)optval,
-					    optlen);
+		retval = sctp_setsockopt_connectx(sk, kopt, optlen);
 		break;
 
 	case SCTP_DISABLE_FRAGMENTS:
-- 
2.27.0