mptcp_pm_parse_entry() will check if the given attribute is defined. If
not, it will return a generic error: "missing address info".

It might then not be clear for the userspace developer which attribute
is missing, especially when the command takes multiple addresses.

By using GENL_REQ_ATTR_CHECK(), the userspace will get a hint about
which attribute is missing, making thing clearer. Note that this is what
was already done for most of the other MPTCP NL commands, this patch
simply adds the missing ones.

Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 net/mptcp/pm_netlink.c   | 26 +++++++++++++++++++++-----
 net/mptcp/pm_userspace.c | 15 ++++++++++++---
 2 files changed, 33 insertions(+), 8 deletions(-)

diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index 3bb213e2a967e87d4244dc0f1ba58d3ba21fb371..1eaaf91eb978b5e85dd5fc11d616ba48809e2915 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -1393,11 +1393,15 @@ static bool mptcp_pm_has_addr_attr_id(const struct nlattr *attr,
 
 int mptcp_pm_nl_add_addr_doit(struct sk_buff *skb, struct genl_info *info)
 {
-	struct nlattr *attr = info->attrs[MPTCP_PM_ENDPOINT_ADDR];
 	struct pm_nl_pernet *pernet = genl_info_pm_nl(info);
 	struct mptcp_pm_addr_entry addr, *entry;
+	struct nlattr *attr;
 	int ret;
 
+	if (GENL_REQ_ATTR_CHECK(info, MPTCP_PM_ENDPOINT_ADDR))
+		return -EINVAL;
+
+	attr = info->attrs[MPTCP_PM_ENDPOINT_ADDR];
 	ret = mptcp_pm_parse_entry(attr, info, true, &addr);
 	if (ret < 0)
 		return ret;
@@ -1590,12 +1594,16 @@ static int mptcp_nl_remove_id_zero_address(struct net *net,
 
 int mptcp_pm_nl_del_addr_doit(struct sk_buff *skb, struct genl_info *info)
 {
-	struct nlattr *attr = info->attrs[MPTCP_PM_ENDPOINT_ADDR];
 	struct pm_nl_pernet *pernet = genl_info_pm_nl(info);
 	struct mptcp_pm_addr_entry addr, *entry;
 	unsigned int addr_max;
+	struct nlattr *attr;
 	int ret;
 
+	if (GENL_REQ_ATTR_CHECK(info, MPTCP_PM_ENDPOINT_ADDR))
+		return -EINVAL;
+
+	attr = info->attrs[MPTCP_PM_ENDPOINT_ADDR];
 	ret = mptcp_pm_parse_entry(attr, info, false, &addr);
 	if (ret < 0)
 		return ret;
@@ -1767,13 +1775,17 @@ int mptcp_nl_fill_addr(struct sk_buff *skb,
 
 int mptcp_pm_nl_get_addr(struct sk_buff *skb, struct genl_info *info)
 {
-	struct nlattr *attr = info->attrs[MPTCP_PM_ENDPOINT_ADDR];
 	struct pm_nl_pernet *pernet = genl_info_pm_nl(info);
 	struct mptcp_pm_addr_entry addr, *entry;
 	struct sk_buff *msg;
+	struct nlattr *attr;
 	void *reply;
 	int ret;
 
+	if (GENL_REQ_ATTR_CHECK(info, MPTCP_PM_ENDPOINT_ADDR))
+		return -EINVAL;
+
+	attr = info->attrs[MPTCP_PM_ENDPOINT_ADDR];
 	ret = mptcp_pm_parse_entry(attr, info, false, &addr);
 	if (ret < 0)
 		return ret;
@@ -1989,18 +2001,20 @@ static int mptcp_nl_set_flags(struct net *net,
 int mptcp_pm_nl_set_flags(struct sk_buff *skb, struct genl_info *info)
 {
 	struct mptcp_pm_addr_entry addr = { .addr = { .family = AF_UNSPEC }, };
-	struct nlattr *attr = info->attrs[MPTCP_PM_ATTR_ADDR];
 	u8 changed, mask = MPTCP_PM_ADDR_FLAG_BACKUP |
 			   MPTCP_PM_ADDR_FLAG_FULLMESH;
 	struct net *net = sock_net(skb->sk);
 	struct mptcp_pm_addr_entry *entry;
 	struct pm_nl_pernet *pernet;
+	struct nlattr *attr;
 	u8 lookup_by_id = 0;
 	u8 bkup = 0;
 	int ret;
 
-	pernet = pm_nl_get_pernet(net);
+	if (GENL_REQ_ATTR_CHECK(info, MPTCP_PM_ATTR_ADDR))
+		return -EINVAL;
 
+	attr = info->attrs[MPTCP_PM_ATTR_ADDR];
 	ret = mptcp_pm_parse_entry(attr, info, false, &addr);
 	if (ret < 0)
 		return ret;
@@ -2017,6 +2031,8 @@ int mptcp_pm_nl_set_flags(struct sk_buff *skb, struct genl_info *info)
 	if (addr.flags & MPTCP_PM_ADDR_FLAG_BACKUP)
 		bkup = 1;
 
+	pernet = pm_nl_get_pernet(net);
+
 	spin_lock_bh(&pernet->lock);
 	entry = lookup_by_id ? __lookup_addr_by_id(pernet, addr.addr.id) :
 			       __lookup_addr(pernet, &addr.addr);
diff --git a/net/mptcp/pm_userspace.c b/net/mptcp/pm_userspace.c
index 51943ca6ddb607e1dfea393525cccf5cbed7cfac..f5515b2305f41fafa7ef0627ed838b9d0db14aa9 100644
--- a/net/mptcp/pm_userspace.c
+++ b/net/mptcp/pm_userspace.c
@@ -570,20 +570,24 @@ int mptcp_userspace_pm_set_flags(struct sk_buff *skb, struct genl_info *info)
 {
 	struct mptcp_pm_addr_entry loc = { .addr = { .family = AF_UNSPEC }, };
 	struct mptcp_pm_addr_entry rem = { .addr = { .family = AF_UNSPEC }, };
-	struct nlattr *attr_rem = info->attrs[MPTCP_PM_ATTR_ADDR_REMOTE];
-	struct nlattr *attr = info->attrs[MPTCP_PM_ATTR_ADDR];
 	struct mptcp_pm_addr_entry *entry;
+	struct nlattr *attr, *attr_rem;
 	struct mptcp_sock *msk;
 	int ret = -EINVAL;
 	struct sock *sk;
 	u8 bkup = 0;
 
+	if (GENL_REQ_ATTR_CHECK(info, MPTCP_PM_ATTR_ADDR) ||
+	    GENL_REQ_ATTR_CHECK(info, MPTCP_PM_ATTR_ADDR_REMOTE))
+		return ret;
+
 	msk = mptcp_userspace_pm_get_sock(info);
 	if (!msk)
 		return ret;
 
 	sk = (struct sock *)msk;
 
+	attr = info->attrs[MPTCP_PM_ATTR_ADDR];
 	ret = mptcp_pm_parse_entry(attr, info, false, &loc);
 	if (ret < 0)
 		goto set_flags_err;
@@ -595,6 +599,7 @@ int mptcp_userspace_pm_set_flags(struct sk_buff *skb, struct genl_info *info)
 		goto set_flags_err;
 	}
 
+	attr_rem = info->attrs[MPTCP_PM_ATTR_ADDR_REMOTE];
 	ret = mptcp_pm_parse_entry(attr_rem, info, false, &rem);
 	if (ret < 0)
 		goto set_flags_err;
@@ -683,20 +688,24 @@ int mptcp_userspace_pm_dump_addr(struct sk_buff *msg,
 int mptcp_userspace_pm_get_addr(struct sk_buff *skb,
 				struct genl_info *info)
 {
-	struct nlattr *attr = info->attrs[MPTCP_PM_ENDPOINT_ADDR];
 	struct mptcp_pm_addr_entry addr, *entry;
 	struct mptcp_sock *msk;
 	struct sk_buff *msg;
+	struct nlattr *attr;
 	int ret = -EINVAL;
 	struct sock *sk;
 	void *reply;
 
+	if (GENL_REQ_ATTR_CHECK(info, MPTCP_PM_ENDPOINT_ADDR))
+		return ret;
+
 	msk = mptcp_userspace_pm_get_sock(info);
 	if (!msk)
 		return ret;
 
 	sk = (struct sock *)msk;
 
+	attr = info->attrs[MPTCP_PM_ENDPOINT_ADDR];
 	ret = mptcp_pm_parse_entry(attr, info, false, &addr);
 	if (ret < 0)
 		goto out;

-- 
2.47.1