Merge branch 'sctp-Some-sockopt-optlen-fixes'

Marcelo Ricardo Leitner says:

====================
sctp: Some sockopt optlen fixes

Hangbin Liu reported that some SCTP sockopt are allowing the user to get
the kernel to allocate really large buffers by not having a ceiling on
optlen.

This patchset address this issue (in patch 2), replace an GFP_ATOMIC
that isn't needed and avoid calculating the option size multiple times
in some setsockopt.
====================
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/socket.c

@@ -2277,7 +2277,7 @@ static int sctp_setsockopt_events(struct sock *sk, char __user *optval,
 
 		if (asoc && sctp_outq_is_empty(&asoc->outqueue)) {
 			event = sctp_ulpevent_make_sender_dry_event(asoc,
-					GFP_ATOMIC);
+					GFP_USER | __GFP_NOWARN);
 			if (!event)
 				return -ENOMEM;
 
@@ -3498,6 +3498,8 @@ static int sctp_setsockopt_hmac_ident(struct sock *sk,
 
 	if (optlen < sizeof(struct sctp_hmacalgo))
 		return -EINVAL;
+	optlen = min_t(unsigned int, optlen, sizeof(struct sctp_hmacalgo) +
+					     SCTP_AUTH_NUM_HMACS * sizeof(u16));
 
 	hmacs = memdup_user(optval, optlen);
 	if (IS_ERR(hmacs))
@@ -3536,6 +3538,11 @@ static int sctp_setsockopt_auth_key(struct sock *sk,
 
 	if (optlen <= sizeof(struct sctp_authkey))
 		return -EINVAL;
+	/* authkey->sca_keylength is u16, so optlen can't be bigger than
+	 * this.
+	 */
+	optlen = min_t(unsigned int, optlen, USHRT_MAX +
+					     sizeof(struct sctp_authkey));
 
 	authkey = memdup_user(optval, optlen);
 	if (IS_ERR(authkey))
@@ -3893,6 +3900,9 @@ static int sctp_setsockopt_reset_streams(struct sock *sk,
 
 	if (optlen < sizeof(*params))
 		return -EINVAL;
+	/* srs_number_streams is u16, so optlen can't be bigger than this. */
+	optlen = min_t(unsigned int, optlen, USHRT_MAX +
+					     sizeof(__u16) * sizeof(*params));
 
 	params = memdup_user(optval, optlen);
 	if (IS_ERR(params))
@@ -5015,7 +5025,7 @@ static int sctp_getsockopt_autoclose(struct sock *sk, int len, char __user *optv
 	len = sizeof(int);
 	if (put_user(len, optlen))
 		return -EFAULT;
-	if (copy_to_user(optval, &sctp_sk(sk)->autoclose, sizeof(int)))
+	if (copy_to_user(optval, &sctp_sk(sk)->autoclose, len))
 		return -EFAULT;
 	return 0;
 }
@@ -5645,6 +5655,9 @@ static int sctp_getsockopt_local_addrs(struct sock *sk, int len,
 		err = -EFAULT;
 		goto out;
 	}
+	/* XXX: We should have accounted for sizeof(struct sctp_getaddrs) too,
+	 * but we can't change it anymore.
+	 */
 	if (put_user(bytes_copied, optlen))
 		err = -EFAULT;
 out:
@@ -6081,7 +6094,7 @@ static int sctp_getsockopt_maxseg(struct sock *sk, int len,
 		params.assoc_id = 0;
 	} else if (len >= sizeof(struct sctp_assoc_value)) {
 		len = sizeof(struct sctp_assoc_value);
-		if (copy_from_user(&params, optval, sizeof(params)))
+		if (copy_from_user(&params, optval, len))
 			return -EFAULT;
 	} else
 		return -EINVAL;
@@ -6251,7 +6264,9 @@ static int sctp_getsockopt_active_key(struct sock *sk, int len,
 
 	if (len < sizeof(struct sctp_authkeyid))
 		return -EINVAL;
-	if (copy_from_user(&val, optval, sizeof(struct sctp_authkeyid)))
+
+	len = sizeof(struct sctp_authkeyid);
+	if (copy_from_user(&val, optval, len))
 		return -EFAULT;
 
 	asoc = sctp_id2assoc(sk, val.scact_assoc_id);
@@ -6263,7 +6278,6 @@ static int sctp_getsockopt_active_key(struct sock *sk, int len,
 	else
 		val.scact_keynumber = ep->active_key_id;
 
-	len = sizeof(struct sctp_authkeyid);
 	if (put_user(len, optlen))
 		return -EFAULT;
 	if (copy_to_user(optval, &val, len))
@@ -6289,7 +6303,7 @@ static int sctp_getsockopt_peer_auth_chunks(struct sock *sk, int len,
 	if (len < sizeof(struct sctp_authchunks))
 		return -EINVAL;
 
-	if (copy_from_user(&val, optval, sizeof(struct sctp_authchunks)))
+	if (copy_from_user(&val, optval, sizeof(val)))
 		return -EFAULT;
 
 	to = p->gauth_chunks;
@@ -6334,7 +6348,7 @@ static int sctp_getsockopt_local_auth_chunks(struct sock *sk, int len,
 	if (len < sizeof(struct sctp_authchunks))
 		return -EINVAL;
 
-	if (copy_from_user(&val, optval, sizeof(struct sctp_authchunks)))
+	if (copy_from_user(&val, optval, sizeof(val)))
 		return -EFAULT;
 
 	to = p->gauth_chunks;