mptcp: pm: use NL_SET_ERR_MSG_ATTR when possible

Instead of only returning a text message with GENL_SET_ERR_MSG(),
NL_SET_ERR_MSG_ATTR() can help the userspace developers by also
reporting which attribute is faulty.

When the error is specific to an attribute, NL_SET_ERR_MSG_ATTR() is now
used. The error messages have not been modified in this commit.

v2:
 - update the code related mptcp_userspace_pm_remove_id_zero_address()
   since a new patch to drop "info" parameter of this patch is added.

v3:
 - not use NL_SET_ERR_MSG_ATTR in mptcp_pm_nl_set_flags(), since 'attr'
   will be removed in the commit "mptcp: add local & remote parameters for
   set_flags".

Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>

Author: matttbe

net/mptcp/pm_netlink.c

@@ -1407,18 +1407,21 @@ int mptcp_pm_nl_add_addr_doit(struct sk_buff *skb, struct genl_info *info)
 		return ret;
 
 	if (addr.addr.port && !address_use_port(&addr)) {
-		GENL_SET_ERR_MSG(info, "flags must have signal and not subflow when using port");
+		NL_SET_ERR_MSG_ATTR(info->extack, attr,
+				    "flags must have signal and not subflow when using port");
 		return -EINVAL;
 	}
 
 	if (addr.flags & MPTCP_PM_ADDR_FLAG_SIGNAL &&
 	    addr.flags & MPTCP_PM_ADDR_FLAG_FULLMESH) {
-		GENL_SET_ERR_MSG(info, "flags mustn't have both signal and fullmesh");
+		NL_SET_ERR_MSG_ATTR(info->extack, attr,
+				    "flags mustn't have both signal and fullmesh");
 		return -EINVAL;
 	}
 
 	if (addr.flags & MPTCP_PM_ADDR_FLAG_IMPLICIT) {
-		GENL_SET_ERR_MSG(info, "can't create IMPLICIT endpoint");
+		NL_SET_ERR_MSG_ATTR(info->extack, attr,
+				    "can't create IMPLICIT endpoint");
 		return -EINVAL;
 	}
 
@@ -1616,7 +1619,7 @@ int mptcp_pm_nl_del_addr_doit(struct sk_buff *skb, struct genl_info *info)
 	spin_lock_bh(&pernet->lock);
 	entry = __lookup_addr_by_id(pernet, addr.addr.id);
 	if (!entry) {
-		GENL_SET_ERR_MSG(info, "address not found");
+		NL_SET_ERR_MSG_ATTR(info->extack, attr, "address not found");
 		spin_unlock_bh(&pernet->lock);
 		return -EINVAL;
 	}
@@ -1802,7 +1805,7 @@ int mptcp_pm_nl_get_addr(struct sk_buff *skb, struct genl_info *info)
 	rcu_read_lock();
 	entry = __lookup_addr_by_id(pernet, addr.addr.id);
 	if (!entry) {
-		GENL_SET_ERR_MSG(info, "address not found");
+		NL_SET_ERR_MSG_ATTR(info->extack, attr, "address not found");
 		ret = -EINVAL;
 		goto unlock_fail;
 	}

net/mptcp/pm_userspace.c

@@ -189,7 +189,8 @@ static struct mptcp_sock *mptcp_userspace_pm_get_sock(const struct genl_info *in
 	}
 
 	if (!mptcp_pm_is_userspace(msk)) {
-		GENL_SET_ERR_MSG(info, "userspace PM not selected");
+		NL_SET_ERR_MSG_ATTR(info->extack, token,
+				    "userspace PM not selected");
 		sock_put((struct sock *)msk);
 		return NULL;
 	}
@@ -233,7 +234,8 @@ int mptcp_pm_nl_announce_doit(struct sk_buff *skb, struct genl_info *info)
 
 	err = mptcp_userspace_pm_append_new_local_addr(msk, &addr_val, false);
 	if (err < 0) {
-		GENL_SET_ERR_MSG(info, "did not match address and id");
+		NL_SET_ERR_MSG_ATTR(info->extack, addr,
+				    "did not match address and id");
 		goto announce_err;
 	}
 
@@ -388,7 +390,7 @@ int mptcp_pm_nl_subflow_create_doit(struct sk_buff *skb, struct genl_info *info)
 		goto create_err;
 
 	if (entry.flags & MPTCP_PM_ADDR_FLAG_SIGNAL) {
-		GENL_SET_ERR_MSG(info, "invalid addr flags");
+		NL_SET_ERR_MSG_ATTR(info->extack, laddr, "invalid addr flags");
 		err = -EINVAL;
 		goto create_err;
 	}
@@ -407,7 +409,8 @@ int mptcp_pm_nl_subflow_create_doit(struct sk_buff *skb, struct genl_info *info)
 
 	err = mptcp_userspace_pm_append_new_local_addr(msk, &entry, false);
 	if (err < 0) {
-		GENL_SET_ERR_MSG(info, "did not match address and id");
+		NL_SET_ERR_MSG_ATTR(info->extack, laddr,
+				    "did not match address and id");
 		goto create_err;
 	}
 
@@ -724,7 +727,7 @@ int mptcp_userspace_pm_get_addr(struct sk_buff *skb,
 	spin_lock_bh(&msk->pm.lock);
 	entry = mptcp_userspace_pm_lookup_addr_by_id(msk, addr.addr.id);
 	if (!entry) {
-		GENL_SET_ERR_MSG(info, "address not found");
+		NL_SET_ERR_MSG_ATTR(info->extack, attr, "address not found");
 		ret = -EINVAL;
 		goto unlock_fail;
 	}