net/xfrm/compat: Copy xfrm_spdattr_type_t atributes

The attribute-translator has to take in mind maxtype, that is
xfrm_link::nla_max. When it is set, attributes are not of xfrm_attr_type_t.
Currently, they can be only XFRMA_SPD_MAX (message XFRM_MSG_NEWSPDINFO),
their UABI is the same for 64/32-bit, so just copy them.

Thanks to YueHaibing for reporting this:
In xfrm_user_rcv_msg_compat() if maxtype is not zero and less than
XFRMA_MAX, nlmsg_parse_deprecated() do not initialize attrs array fully.
xfrm_xlate32() will access uninit 'attrs[i]' while iterating all attrs
array.

KASAN: probably user-memory-access in range [0x0000000041b58ab0-0x0000000041b58ab7]
CPU: 0 PID: 15799 Comm: syz-executor.2 Tainted: G W 5.14.0-rc1-syzkaller #0
RIP: 0010:nla_type include/net/netlink.h:1130 [inline]
RIP: 0010:xfrm_xlate32_attr net/xfrm/xfrm_compat.c:410 [inline]
RIP: 0010:xfrm_xlate32 net/xfrm/xfrm_compat.c:532 [inline]
RIP: 0010:xfrm_user_rcv_msg_compat+0x5e5/0x1070 net/xfrm/xfrm_compat.c:577
[...]
Call Trace:
xfrm_user_rcv_msg+0x556/0x8b0 net/xfrm/xfrm_user.c:2774
netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2504
xfrm_netlink_rcv+0x6b/0x90 net/xfrm/xfrm_user.c:2824
netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1340
netlink_sendmsg+0x86d/0xdb0 net/netlink/af_netlink.c:1929
sock_sendmsg_nosec net/socket.c:702 [inline]

Fixes: 5106f4a8acff ("xfrm/compat: Add 32=>64-bit messages translator")
Cc: <[e-mail]>
Reported-by: YueHaibing <[e-mail]>
Signed-off-by: Dmitry Safonov <[e-mail]>
Signed-off-by: Steffen Klassert <[e-mail]>

net/xfrm/xfrm_compat.c

···
 	len = nlmsg_attrlen(nlh_src, xfrm_msg_min[type]);
 
 	nla_for_each_attr(nla, attrs, len, remaining) {
-		int err = xfrm_xlate64_attr(dst, nla);
+		int err;
 
+		switch (type) {
+		case XFRM_MSG_NEWSPDINFO:
+			err = xfrm_nla_cpy(dst, nla, nla_len(nla));
+			break;
+		default:
+			err = xfrm_xlate64_attr(dst, nla);
+			break;
+		}
 		if (err)
 			return err;
 	}
···
 
 /* Calculates len of translated 64-bit message. */
 static size_t xfrm_user_rcv_calculate_len64(const struct nlmsghdr *src,
-					    struct nlattr *attrs[XFRMA_MAX+1])
+					    struct nlattr *attrs[XFRMA_MAX + 1],
+					    int maxtype)
 {
 	size_t len = nlmsg_len(src);
 
···
 	case XFRM_MSG_POLEXPIRE:
 		len += 8;
 		break;
+	case XFRM_MSG_NEWSPDINFO:
+		/* attirbutes are xfrm_spdattr_type_t, not xfrm_attr_type_t */
+		return len;
 	default:
 		break;
 	}
+
+	/* Unexpected for anything, but XFRM_MSG_NEWSPDINFO, please
+	 * correct both 64=>32-bit and 32=>64-bit translators to copy
+	 * new attributes.
+	 */
+	if (WARN_ON_ONCE(maxtype))
+		return len;
 
 	if (attrs[XFRMA_SA])
 		len += 4;
···
 
 static int xfrm_xlate32(struct nlmsghdr *dst, const struct nlmsghdr *src,
 			struct nlattr *attrs[XFRMA_MAX+1],
-			size_t size, u8 type, struct netlink_ext_ack *extack)
+			size_t size, u8 type, int maxtype,
+			struct netlink_ext_ack *extack)
 {
 	size_t pos;
 	int i;
···
 	}
 	pos = dst->nlmsg_len;
 
+	if (maxtype) {
+		/* attirbutes are xfrm_spdattr_type_t, not xfrm_attr_type_t */
+		WARN_ON_ONCE(src->nlmsg_type != XFRM_MSG_NEWSPDINFO);
+
+		for (i = 1; i <= maxtype; i++) {
+			int err;
+
+			if (!attrs[i])
+				continue;
+
+			/* just copy - no need for translation */
+			err = xfrm_attr_cpy32(dst, &pos, attrs[i], size,
+					nla_len(attrs[i]), nla_len(attrs[i]));
+			if (err)
+				return err;
+		}
+		return 0;
+	}
+
 	for (i = 1; i < XFRMA_MAX + 1; i++) {
 		int err;
 
···
 	if (err < 0)
 		return ERR_PTR(err);
 
-	len = xfrm_user_rcv_calculate_len64(h32, attrs);
+	len = xfrm_user_rcv_calculate_len64(h32, attrs, maxtype);
 	/* The message doesn't need translation */
 	if (len == nlmsg_len(h32))
 		return NULL;
···
 	if (!h64)
 		return ERR_PTR(-ENOMEM);
 
-	err = xfrm_xlate32(h64, h32, attrs, len, type, extack);
+	err = xfrm_xlate32(h64, h32, attrs, len, type, maxtype, extack);
 	if (err < 0) {
 		kvfree(h64);
 		return ERR_PTR(err);