tipc: convert legacy nl bearer enable/disable to nl compat

Introduce a framework for transcoding legacy nl action into actions
(.doit) calls from the new nl API. This is done by converting the
incoming TLV data into netlink data with nested netlink attributes.
Unfortunately due to the randomness of the legacy API we can't do this
generically so each legacy netlink command requires a specific
transcoding recipe. In this case for bearer enable and bearer disable.

Convert TIPC_CMD_ENABLE_BEARER and TIPC_CMD_DISABLE_BEARER into doit
compat calls.

Signed-off-by: Richard Alpe <[e-mail]>
Reviewed-by: Erik Hugne <[e-mail]>
Reviewed-by: Ying Xue <[e-mail]>
Reviewed-by: Jon Maloy <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/uapi/linux/tipc_config.h

···
 	return ntohs(tlv->tlv_len);
 }
 
+static inline int TLV_CHECK_TYPE(struct tlv_desc *tlv,  __u16 type)
+{
+	return (ntohs(tlv->tlv_type) == type);
+}
+
 static inline int TLV_SET(void *tlv, __u16 type, void *data, __u16 len)
 {
 	struct tlv_desc *tlv_ptr;

net/tipc/bearer.c

···
 /**
  * tipc_enable_bearer - enable bearer with the given name
  */
-int tipc_enable_bearer(struct net *net, const char *name, u32 disc_domain,
-		       u32 priority)
+static int tipc_enable_bearer(struct net *net, const char *name,
+			      u32 disc_domain, u32 priority)
 {
 	struct tipc_net *tn = net_generic(net, tipc_net_id);
 	struct tipc_bearer *b_ptr;
···
 		}
 	}
 	kfree_rcu(b_ptr, rcu);
-}
-
-int tipc_disable_bearer(struct net *net, const char *name)
-{
-	struct tipc_bearer *b_ptr;
-	int res;
-
-	b_ptr = tipc_bearer_find(net, name);
-	if (b_ptr == NULL) {
-		pr_warn("Attempt to disable unknown bearer <%s>\n", name);
-		res = -EINVAL;
-	} else {
-		bearer_disable(net, b_ptr, false);
-		res = 0;
-	}
-	return res;
 }
 
 int tipc_enable_l2_media(struct net *net, struct tipc_bearer *b)
···
 	char *name;
 	struct tipc_bearer *bearer;
 	struct nlattr *attrs[TIPC_NLA_BEARER_MAX + 1];
-	struct net *net = genl_info_net(info);
+	struct net *net = sock_net(skb->sk);
 
 	if (!info->attrs[TIPC_NLA_BEARER])
 		return -EINVAL;
···
 
 int tipc_nl_bearer_enable(struct sk_buff *skb, struct genl_info *info)
 {
-	struct net *net = genl_info_net(info);
-	struct tipc_net *tn = net_generic(net, tipc_net_id);
 	int err;
 	char *bearer;
 	struct nlattr *attrs[TIPC_NLA_BEARER_MAX + 1];
+	struct net *net = sock_net(skb->sk);
+	struct tipc_net *tn = net_generic(net, tipc_net_id);
 	u32 domain;
 	u32 prio;
 

net/tipc/bearer.h

···
  */
 
 void tipc_rcv(struct net *net, struct sk_buff *skb, struct tipc_bearer *b_ptr);
-int tipc_enable_bearer(struct net *net, const char *bearer_name,
-		       u32 disc_domain, u32 priority);
-int tipc_disable_bearer(struct net *net, const char *name);
 
 /*
  * Routines made available to TIPC by supported media types

net/tipc/config.c

···
 	return buf;
 }
 
-static struct sk_buff *cfg_enable_bearer(struct net *net)
-{
-	struct tipc_bearer_config *args;
-
-	if (!TLV_CHECK(req_tlv_area, req_tlv_space, TIPC_TLV_BEARER_CONFIG))
-		return tipc_cfg_reply_error_string(TIPC_CFG_TLV_ERROR);
-
-	args = (struct tipc_bearer_config *)TLV_DATA(req_tlv_area);
-	if (tipc_enable_bearer(net, args->name,
-			       ntohl(args->disc_domain),
-			       ntohl(args->priority)))
-		return tipc_cfg_reply_error_string("unable to enable bearer");
-
-	return tipc_cfg_reply_none();
-}
-
-static struct sk_buff *cfg_disable_bearer(struct net *net)
-{
-	if (!TLV_CHECK(req_tlv_area, req_tlv_space, TIPC_TLV_BEARER_NAME))
-		return tipc_cfg_reply_error_string(TIPC_CFG_TLV_ERROR);
-
-	if (tipc_disable_bearer(net, (char *)TLV_DATA(req_tlv_area)))
-		return tipc_cfg_reply_error_string("unable to disable bearer");
-
-	return tipc_cfg_reply_none();
-}
-
 static struct sk_buff *cfg_set_own_addr(struct net *net)
 {
 	struct tipc_net *tn = net_generic(net, tipc_net_id);
···
 	case TIPC_CMD_SET_LINK_WINDOW:
 		rep_tlv_buf = tipc_link_cmd_config(net, req_tlv_area,
 						   req_tlv_space, cmd);
-		break;
-	case TIPC_CMD_ENABLE_BEARER:
-		rep_tlv_buf = cfg_enable_bearer(net);
-		break;
-	case TIPC_CMD_DISABLE_BEARER:
-		rep_tlv_buf = cfg_disable_bearer(net);
 		break;
 	case TIPC_CMD_SET_NODE_ADDR:
 		rep_tlv_buf = cfg_set_own_addr(net);

net/tipc/netlink_compat.c

···
 struct tipc_nl_compat_msg {
 	u16 cmd;
 	int rep_size;
+	int req_type;
 	struct sk_buff *rep;
 	struct tlv_desc *req;
 	struct sock *dst_sk;
···
 struct tipc_nl_compat_cmd_dump {
 	int (*dumpit)(struct sk_buff *, struct netlink_callback *);
 	int (*format)(struct tipc_nl_compat_msg *msg, struct nlattr **attrs);
+};
+
+struct tipc_nl_compat_cmd_doit {
+	int (*doit)(struct sk_buff *skb, struct genl_info *info);
+	int (*transcode)(struct sk_buff *skb, struct tipc_nl_compat_msg *msg);
 };
 
 static int tipc_skb_tailroom(struct sk_buff *skb)
···
 	return err;
 }
 
+static int __tipc_nl_compat_doit(struct tipc_nl_compat_cmd_doit *cmd,
+				 struct tipc_nl_compat_msg *msg)
+{
+	int err;
+	struct sk_buff *doit_buf;
+	struct sk_buff *trans_buf;
+	struct nlattr **attrbuf;
+	struct genl_info info;
+
+	trans_buf = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
+	if (!trans_buf)
+		return -ENOMEM;
+
+	err = (*cmd->transcode)(trans_buf, msg);
+	if (err)
+		goto trans_out;
+
+	attrbuf = kmalloc((tipc_genl_family.maxattr + 1) *
+			sizeof(struct nlattr *), GFP_KERNEL);
+	if (!attrbuf) {
+		err = -ENOMEM;
+		goto trans_out;
+	}
+
+	err = nla_parse(attrbuf, tipc_genl_family.maxattr,
+			(const struct nlattr *)trans_buf->data,
+			trans_buf->len, NULL);
+	if (err)
+		goto parse_out;
+
+	doit_buf = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
+	if (!doit_buf) {
+		err = -ENOMEM;
+		goto parse_out;
+	}
+
+	doit_buf->sk = msg->dst_sk;
+
+	memset(&info, 0, sizeof(info));
+	info.attrs = attrbuf;
+
+	err = (*cmd->doit)(doit_buf, &info);
+
+	kfree_skb(doit_buf);
+parse_out:
+	kfree(attrbuf);
+trans_out:
+	kfree_skb(trans_buf);
+
+	return err;
+}
+
+static int tipc_nl_compat_doit(struct tipc_nl_compat_cmd_doit *cmd,
+			       struct tipc_nl_compat_msg *msg)
+{
+	int err;
+
+	if (msg->req_type && !TLV_CHECK_TYPE(msg->req, msg->req_type))
+		return -EINVAL;
+
+	err = __tipc_nl_compat_doit(cmd, msg);
+	if (err)
+		return err;
+
+	/* The legacy API considered an empty message a success message */
+	msg->rep = tipc_tlv_alloc(0);
+	if (!msg->rep)
+		return -ENOMEM;
+
+	return 0;
+}
+
 static int tipc_nl_compat_bearer_dump(struct tipc_nl_compat_msg *msg,
 				      struct nlattr **attrs)
 {
···
 			    nla_len(bearer[TIPC_NLA_BEARER_NAME]));
 }
 
+static int tipc_nl_compat_bearer_enable(struct sk_buff *skb,
+					struct tipc_nl_compat_msg *msg)
+{
+	struct nlattr *prop;
+	struct nlattr *bearer;
+	struct tipc_bearer_config *b;
+
+	b = (struct tipc_bearer_config *)TLV_DATA(msg->req);
+
+	bearer = nla_nest_start(skb, TIPC_NLA_BEARER);
+	if (!bearer)
+		return -EMSGSIZE;
+
+	if (nla_put_string(skb, TIPC_NLA_BEARER_NAME, b->name))
+		return -EMSGSIZE;
+
+	if (nla_put_u32(skb, TIPC_NLA_BEARER_DOMAIN, ntohl(b->disc_domain)))
+		return -EMSGSIZE;
+
+	if (ntohl(b->priority) <= TIPC_MAX_LINK_PRI) {
+		prop = nla_nest_start(skb, TIPC_NLA_BEARER_PROP);
+		if (!prop)
+			return -EMSGSIZE;
+		if (nla_put_u32(skb, TIPC_NLA_PROP_PRIO, ntohl(b->priority)))
+			return -EMSGSIZE;
+		nla_nest_end(skb, prop);
+	}
+	nla_nest_end(skb, bearer);
+
+	return 0;
+}
+
+static int tipc_nl_compat_bearer_disable(struct sk_buff *skb,
+					 struct tipc_nl_compat_msg *msg)
+{
+	char *name;
+	struct nlattr *bearer;
+
+	name = (char *)TLV_DATA(msg->req);
+
+	bearer = nla_nest_start(skb, TIPC_NLA_BEARER);
+	if (!bearer)
+		return -EMSGSIZE;
+
+	if (nla_put_string(skb, TIPC_NLA_BEARER_NAME, name))
+		return -EMSGSIZE;
+
+	nla_nest_end(skb, bearer);
+
+	return 0;
+}
+
 static int tipc_nl_compat_handle(struct tipc_nl_compat_msg *msg)
 {
 	struct tipc_nl_compat_cmd_dump dump;
+	struct tipc_nl_compat_cmd_doit doit;
 
 	memset(&dump, 0, sizeof(dump));
+	memset(&doit, 0, sizeof(doit));
 
 	switch (msg->cmd) {
 	case TIPC_CMD_GET_BEARER_NAMES:
···
 		dump.dumpit = tipc_nl_bearer_dump;
 		dump.format = tipc_nl_compat_bearer_dump;
 		return tipc_nl_compat_dumpit(&dump, msg);
+	case TIPC_CMD_ENABLE_BEARER:
+		msg->req_type = TIPC_TLV_BEARER_CONFIG;
+		doit.doit = tipc_nl_bearer_enable;
+		doit.transcode = tipc_nl_compat_bearer_enable;
+		return tipc_nl_compat_doit(&doit, msg);
+	case TIPC_CMD_DISABLE_BEARER:
+		msg->req_type = TIPC_TLV_BEARER_NAME;
+		doit.doit = tipc_nl_bearer_disable;
+		doit.transcode = tipc_nl_compat_bearer_disable;
+		return tipc_nl_compat_doit(&doit, msg);
 	}
 
 	return -EOPNOTSUPP;
···
 
 	switch (req->cmd) {
 	case TIPC_CMD_GET_BEARER_NAMES:
+	case TIPC_CMD_ENABLE_BEARER:
+	case TIPC_CMD_DISABLE_BEARER:
 		return tipc_nl_compat_recv(skb, info);
 	}