This change introduces a parallel path in the kernel for retrieving
the local id, flags, if_index for an addr entry in the context of
an MPTCP connection that's being managed by a userspace PM. The
userspace and in-kernel PM modes deviate in their procedures for
obtaining this information.

Signed-off-by: Kishen Maloor <kishen.maloor@intel.com>
---
 net/mptcp/pm_netlink.c | 95 ++++++++++++++++++++++++++++--------------
 net/mptcp/protocol.h   |  3 +-
 net/mptcp/subflow.c    |  2 +-
 3 files changed, 67 insertions(+), 33 deletions(-)

diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index 836f6df9f744..a258593f2cb1 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -1036,31 +1036,47 @@ int mptcp_pm_nl_get_local_id(struct mptcp_sock *msk, struct sock_common *skc)
 
 	pernet = net_generic(sock_net((struct sock *)msk), pm_nl_pernet_id);
 
-	rcu_read_lock();
-	list_for_each_entry_rcu(entry, &pernet->local_addr_list, list) {
-		if (mptcp_addresses_equal(&entry->addr, &skc_local, entry->addr.port)) {
-			ret = entry->addr.id;
-			break;
+	if (mptcp_pm_is_kernel(msk)) {
+		rcu_read_lock();
+		list_for_each_entry_rcu(entry, &pernet->local_addr_list, list) {
+			if (mptcp_addresses_equal(&entry->addr, &skc_local, entry->addr.port)) {
+				ret = entry->addr.id;
+				break;
+			}
 		}
+		rcu_read_unlock();
+		if (ret >= 0)
+			return ret;
+
+		/* address not found, add to local list */
+		entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
+		if (!entry)
+			return -ENOMEM;
+
+		entry->addr = skc_local;
+		entry->addr.id = 0;
+		entry->addr.port = 0;
+		entry->ifindex = 0;
+		entry->flags = MPTCP_PM_ADDR_FLAG_IMPLICIT;
+		entry->lsk = NULL;
+		ret = mptcp_pm_nl_append_new_local_addr(pernet, entry);
+		if (ret < 0)
+			kfree(entry);
+	} else if (mptcp_pm_is_userspace(msk)) {
+		struct mptcp_pm_addr_entry new_entry;
+		__be16 msk_sport =  ((struct inet_sock *)
+				     inet_sk((struct sock *)msk))->inet_sport;
+
+		memset(&new_entry, 0, sizeof(struct mptcp_pm_addr_entry));
+		new_entry.addr = skc_local;
+		new_entry.addr.id = 0;
+		new_entry.flags = MPTCP_PM_ADDR_FLAG_IMPLICIT;
+
+		if (new_entry.addr.port == msk_sport)
+			new_entry.addr.port = 0;
+
+		ret = mptcp_userspace_pm_append_new_local_addr(msk, &new_entry);
 	}
-	rcu_read_unlock();
-	if (ret >= 0)
-		return ret;
-
-	/* address not found, add to local list */
-	entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
-	if (!entry)
-		return -ENOMEM;
-
-	entry->addr = skc_local;
-	entry->addr.id = 0;
-	entry->addr.port = 0;
-	entry->ifindex = 0;
-	entry->flags = MPTCP_PM_ADDR_FLAG_IMPLICIT;
-	entry->lsk = NULL;
-	ret = mptcp_pm_nl_append_new_local_addr(pernet, entry);
-	if (ret < 0)
-		kfree(entry);
 
 	return ret;
 }
@@ -1298,22 +1314,39 @@ static int mptcp_nl_cmd_add_addr(struct sk_buff *skb, struct genl_info *info)
 	return 0;
 }
 
-int mptcp_pm_get_flags_and_ifindex_by_id(struct net *net, unsigned int id,
+int mptcp_pm_get_flags_and_ifindex_by_id(struct mptcp_sock *msk, unsigned int id,
 					 u8 *flags, int *ifindex)
 {
-	struct mptcp_pm_addr_entry *entry;
+	struct mptcp_pm_addr_entry *entry, *match = NULL;
+	struct sock *sk = (struct sock *)msk;
+	struct net *net = sock_net(sk);
 
 	*flags = 0;
 	*ifindex = 0;
 
 	if (id) {
-		rcu_read_lock();
-		entry = __lookup_addr_by_id(net_generic(net, pm_nl_pernet_id), id);
-		if (entry) {
-			*flags = entry->flags;
-			*ifindex = entry->ifindex;
+		if (mptcp_pm_is_kernel(msk)) {
+			rcu_read_lock();
+			entry = __lookup_addr_by_id(net_generic(net, pm_nl_pernet_id), id);
+			if (entry) {
+				*flags = entry->flags;
+				*ifindex = entry->ifindex;
+			}
+			rcu_read_unlock();
+		} else {
+			spin_lock_bh(&msk->pm.lock);
+			list_for_each_entry(entry, &msk->pm.userspace_pm_local_addr_list, list) {
+				if (id == entry->addr.id) {
+					match = entry;
+					break;
+				}
+			}
+			spin_unlock_bh(&msk->pm.lock);
+			if (match) {
+				*flags = match->flags;
+				*ifindex = match->ifindex;
+			}
 		}
-		rcu_read_unlock();
 	}
 
 	return 0;
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 40dabf9462a8..4ae3253d7f9a 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -775,7 +775,8 @@ mptcp_pm_del_add_timer(struct mptcp_sock *msk,
 struct mptcp_pm_add_entry *
 mptcp_lookup_anno_list_by_saddr(const struct mptcp_sock *msk,
 				const struct mptcp_addr_info *addr);
-int mptcp_pm_get_flags_and_ifindex_by_id(struct net *net, unsigned int id,
+int mptcp_pm_get_flags_and_ifindex_by_id(struct mptcp_sock *msk,
+					 unsigned int id,
 					 u8 *flags, int *ifindex);
 
 int mptcp_pm_announce_addr(struct mptcp_sock *msk,
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index a0e7af33fb26..6d59336a8e1e 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -1468,7 +1468,7 @@ int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,
 	if (local_id)
 		subflow_set_local_id(subflow, local_id);
 
-	mptcp_pm_get_flags_and_ifindex_by_id(sock_net(sk), local_id,
+	mptcp_pm_get_flags_and_ifindex_by_id(msk, local_id,
 					     &flags, &ifindex);
 	subflow->remote_key = msk->remote_key;
 	subflow->local_key = msk->local_key;
-- 
2.31.1

On Mon, 28 Mar 2022, Kishen Maloor wrote:

> This change introduces a parallel path in the kernel for retrieving
> the local id, flags, if_index for an addr entry in the context of
> an MPTCP connection that's being managed by a userspace PM. The
> userspace and in-kernel PM modes deviate in their procedures for
> obtaining this information.
>
> Signed-off-by: Kishen Maloor <kishen.maloor@intel.com>
> ---
> net/mptcp/pm_netlink.c | 95 ++++++++++++++++++++++++++++--------------
> net/mptcp/protocol.h   |  3 +-
> net/mptcp/subflow.c    |  2 +-
> 3 files changed, 67 insertions(+), 33 deletions(-)
>
> diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
> index 836f6df9f744..a258593f2cb1 100644
> --- a/net/mptcp/pm_netlink.c
> +++ b/net/mptcp/pm_netlink.c
> @@ -1036,31 +1036,47 @@ int mptcp_pm_nl_get_local_id(struct mptcp_sock *msk, struct sock_common *skc)
>
> 	pernet = net_generic(sock_net((struct sock *)msk), pm_nl_pernet_id);
>
> -	rcu_read_lock();
> -	list_for_each_entry_rcu(entry, &pernet->local_addr_list, list) {
> -		if (mptcp_addresses_equal(&entry->addr, &skc_local, entry->addr.port)) {
> -			ret = entry->addr.id;
> -			break;
> +	if (mptcp_pm_is_kernel(msk)) {
> +		rcu_read_lock();
> +		list_for_each_entry_rcu(entry, &pernet->local_addr_list, list) {
> +			if (mptcp_addresses_equal(&entry->addr, &skc_local, entry->addr.port)) {
> +				ret = entry->addr.id;
> +				break;
> +			}
> 		}
> +		rcu_read_unlock();
> +		if (ret >= 0)
> +			return ret;
> +
> +		/* address not found, add to local list */
> +		entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
> +		if (!entry)
> +			return -ENOMEM;
> +
> +		entry->addr = skc_local;
> +		entry->addr.id = 0;
> +		entry->addr.port = 0;
> +		entry->ifindex = 0;
> +		entry->flags = MPTCP_PM_ADDR_FLAG_IMPLICIT;
> +		entry->lsk = NULL;
> +		ret = mptcp_pm_nl_append_new_local_addr(pernet, entry);
> +		if (ret < 0)
> +			kfree(entry);
> +	} else if (mptcp_pm_is_userspace(msk)) {
> +		struct mptcp_pm_addr_entry new_entry;
> +		__be16 msk_sport =  ((struct inet_sock *)
> +				     inet_sk((struct sock *)msk))->inet_sport;
> +
> +		memset(&new_entry, 0, sizeof(struct mptcp_pm_addr_entry));
> +		new_entry.addr = skc_local;
> +		new_entry.addr.id = 0;
> +		new_entry.flags = MPTCP_PM_ADDR_FLAG_IMPLICIT;
> +
> +		if (new_entry.addr.port == msk_sport)
> +			new_entry.addr.port = 0;
> +
> +		ret = mptcp_userspace_pm_append_new_local_addr(msk, &new_entry);
> 	}
> -	rcu_read_unlock();
> -	if (ret >= 0)
> -		return ret;
> -
> -	/* address not found, add to local list */
> -	entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
> -	if (!entry)
> -		return -ENOMEM;
> -
> -	entry->addr = skc_local;
> -	entry->addr.id = 0;
> -	entry->addr.port = 0;
> -	entry->ifindex = 0;
> -	entry->flags = MPTCP_PM_ADDR_FLAG_IMPLICIT;
> -	entry->lsk = NULL;
> -	ret = mptcp_pm_nl_append_new_local_addr(pernet, entry);
> -	if (ret < 0)
> -		kfree(entry);
>
> 	return ret;
> }
> @@ -1298,22 +1314,39 @@ static int mptcp_nl_cmd_add_addr(struct sk_buff *skb, struct genl_info *info)
> 	return 0;
> }
>
> -int mptcp_pm_get_flags_and_ifindex_by_id(struct net *net, unsigned int id,
> +int mptcp_pm_get_flags_and_ifindex_by_id(struct mptcp_sock *msk, unsigned int id,
> 					 u8 *flags, int *ifindex)
> {
> -	struct mptcp_pm_addr_entry *entry;
> +	struct mptcp_pm_addr_entry *entry, *match = NULL;
> +	struct sock *sk = (struct sock *)msk;
> +	struct net *net = sock_net(sk);
>
> 	*flags = 0;
> 	*ifindex = 0;
>
> 	if (id) {
> -		rcu_read_lock();
> -		entry = __lookup_addr_by_id(net_generic(net, pm_nl_pernet_id), id);
> -		if (entry) {
> -			*flags = entry->flags;
> -			*ifindex = entry->ifindex;
> +		if (mptcp_pm_is_kernel(msk)) {
> +			rcu_read_lock();
> +			entry = __lookup_addr_by_id(net_generic(net, pm_nl_pernet_id), id);

Another conflict here due to the "mptcp: add pm_nl_pernet helpers" 
commit, the changes in existing code would be avoided with Paolo's 
suggestion to add a thin layer to call this function (unmodified) or a 
separate version for the userspace PM.

But also be sure to use the new pm_nl_pernet helpers in the new userspace 
PM code.


--
Mat Martineau
Intel

On Mon, 2022-03-28 at 22:14 -0400, Kishen Maloor wrote:
> This change introduces a parallel path in the kernel for retrieving
> the local id, flags, if_index for an addr entry in the context of
> an MPTCP connection that's being managed by a userspace PM. The
> userspace and in-kernel PM modes deviate in their procedures for
> obtaining this information.

I'm sorry, but I was not able to give feedback earlier. I really think
it would be better do the 'if (mptcp_pm_is_kernel(msk))' in a thin
layer, and add the new code into pm_userspace.c

e.g. this patch has a relatively large diffstat because quite a bit of
existing code is just re-indented, with the proposed schema that will
be avoided.

Thanks!

Paolo

On 4/1/22 8:03 AM, Paolo Abeni wrote:
> On Mon, 2022-03-28 at 22:14 -0400, Kishen Maloor wrote:
>> This change introduces a parallel path in the kernel for retrieving
>> the local id, flags, if_index for an addr entry in the context of
>> an MPTCP connection that's being managed by a userspace PM. The
>> userspace and in-kernel PM modes deviate in their procedures for
>> obtaining this information.
> 
> I'm sorry, but I was not able to give feedback earlier. I really think
> it would be better do the 'if (mptcp_pm_is_kernel(msk))' in a thin
> layer, and add the new code into pm_userspace.c
> 
> e.g. this patch has a relatively large diffstat because quite a bit of
> existing code is just re-indented, with the proposed schema that will
> be avoided.

I have moved code from the 2 functions that had explicit in-kernel vs
userspace PM branches into matching functions inside pm_userspace.c.
Hopefully that makes it cleaner.

> 
> Thanks!
> 
> Paolo
>