From: Geliang Tang <tanggeliang@kylinos.cn>

The following code in mptcp_userspace_pm_get_local_id() that assigns "skc"
to "new_entry" is not allowed in BPF if we use the same code to implement
the get_local_id() interface of a BFP path manager:

	memset(&new_entry, 0, sizeof(struct mptcp_pm_addr_entry));
	new_entry.addr = *skc;
	new_entry.addr.id = 0;
	new_entry.flags = MPTCP_PM_ADDR_FLAG_IMPLICIT;

To solve the issue, this patch moves this assignment to "new_entry" forward
to mptcp_pm_get_local_id(), and then passing "new_entry" as a parameter to
both mptcp_pm_nl_get_local_id() and mptcp_userspace_pm_get_local_id().

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 net/mptcp/pm.c           | 11 ++++++++---
 net/mptcp/pm_netlink.c   |  9 ++++-----
 net/mptcp/pm_userspace.c | 17 ++++++-----------
 net/mptcp/protocol.h     |  6 ++++--
 4 files changed, 22 insertions(+), 21 deletions(-)

diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index 16cacce6c10f..94620ab172b7 100644
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -403,20 +403,25 @@ bool mptcp_pm_rm_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
 
 int mptcp_pm_get_local_id(struct mptcp_sock *msk, struct sock_common *skc)
 {
-	struct mptcp_addr_info skc_local;
+	struct mptcp_pm_addr_entry skc_local;
 	struct mptcp_addr_info msk_local;
 
 	if (WARN_ON_ONCE(!msk))
 		return -1;
 
+	memset(&skc_local, 0, sizeof(struct mptcp_pm_addr_entry));
+
 	/* The 0 ID mapping is defined by the first subflow, copied into the msk
 	 * addr
 	 */
 	mptcp_local_address((struct sock_common *)msk, &msk_local);
-	mptcp_local_address((struct sock_common *)skc, &skc_local);
-	if (mptcp_addresses_equal(&msk_local, &skc_local, false))
+	mptcp_local_address((struct sock_common *)skc, &skc_local.addr);
+	if (mptcp_addresses_equal(&msk_local, &skc_local.addr, false))
 		return 0;
 
+	skc_local.addr.id = 0;
+	skc_local.flags = MPTCP_PM_ADDR_FLAG_IMPLICIT;
+
 	if (mptcp_pm_is_userspace(msk))
 		return mptcp_userspace_pm_get_local_id(msk, &skc_local);
 	return mptcp_pm_nl_get_local_id(msk, &skc_local);
diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index d4328443d844..0a0fe890c53d 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -1139,7 +1139,8 @@ static int mptcp_pm_nl_create_listen_socket(struct sock *sk,
 	return err;
 }
 
-int mptcp_pm_nl_get_local_id(struct mptcp_sock *msk, struct mptcp_addr_info *skc)
+int mptcp_pm_nl_get_local_id(struct mptcp_sock *msk,
+			     struct mptcp_pm_addr_entry *skc)
 {
 	struct mptcp_pm_addr_entry *entry;
 	struct pm_nl_pernet *pernet;
@@ -1148,7 +1149,7 @@ int mptcp_pm_nl_get_local_id(struct mptcp_sock *msk, struct mptcp_addr_info *skc
 	pernet = pm_nl_get_pernet_from_msk(msk);
 
 	rcu_read_lock();
-	entry = __lookup_addr(pernet, skc);
+	entry = __lookup_addr(pernet, &skc->addr);
 	ret = entry ? entry->addr.id : -1;
 	rcu_read_unlock();
 	if (ret >= 0)
@@ -1159,11 +1160,9 @@ int mptcp_pm_nl_get_local_id(struct mptcp_sock *msk, struct mptcp_addr_info *skc
 	if (!entry)
 		return -ENOMEM;
 
-	entry->addr = *skc;
-	entry->addr.id = 0;
+	*entry = *skc;
 	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, true);
 	if (ret < 0)
diff --git a/net/mptcp/pm_userspace.c b/net/mptcp/pm_userspace.c
index 6bf6a20ef7f3..5b3ee43130be 100644
--- a/net/mptcp/pm_userspace.c
+++ b/net/mptcp/pm_userspace.c
@@ -131,27 +131,22 @@ mptcp_userspace_pm_lookup_addr_by_id(struct mptcp_sock *msk, unsigned int id)
 }
 
 int mptcp_userspace_pm_get_local_id(struct mptcp_sock *msk,
-				    struct mptcp_addr_info *skc)
+				    struct mptcp_pm_addr_entry *skc)
 {
-	struct mptcp_pm_addr_entry *entry = NULL, new_entry;
 	__be16 msk_sport =  ((struct inet_sock *)
 			     inet_sk((struct sock *)msk))->inet_sport;
+	struct mptcp_pm_addr_entry *entry;
 
 	spin_lock_bh(&msk->pm.lock);
-	entry = mptcp_userspace_pm_lookup_addr(msk, skc);
+	entry = mptcp_userspace_pm_lookup_addr(msk, &skc->addr);
 	spin_unlock_bh(&msk->pm.lock);
 	if (entry)
 		return entry->addr.id;
 
-	memset(&new_entry, 0, sizeof(struct mptcp_pm_addr_entry));
-	new_entry.addr = *skc;
-	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;
+	if (skc->addr.port == msk_sport)
+		skc->addr.port = 0;
 
-	return mptcp_userspace_pm_append_new_local_addr(msk, &new_entry, true);
+	return mptcp_userspace_pm_append_new_local_addr(msk, skc, true);
 }
 
 bool mptcp_userspace_pm_is_backup(struct mptcp_sock *msk,
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 3d72ca155322..ef1d43406f9b 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -1126,8 +1126,10 @@ bool mptcp_pm_add_addr_signal(struct mptcp_sock *msk, const struct sk_buff *skb,
 bool mptcp_pm_rm_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
 			     struct mptcp_rm_list *rm_list);
 int mptcp_pm_get_local_id(struct mptcp_sock *msk, struct sock_common *skc);
-int mptcp_pm_nl_get_local_id(struct mptcp_sock *msk, struct mptcp_addr_info *skc);
-int mptcp_userspace_pm_get_local_id(struct mptcp_sock *msk, struct mptcp_addr_info *skc);
+int mptcp_pm_nl_get_local_id(struct mptcp_sock *msk,
+			     struct mptcp_pm_addr_entry *skc);
+int mptcp_userspace_pm_get_local_id(struct mptcp_sock *msk,
+				    struct mptcp_pm_addr_entry *skc);
 bool mptcp_pm_is_backup(struct mptcp_sock *msk, struct sock_common *skc);
 bool mptcp_pm_nl_is_backup(struct mptcp_sock *msk, struct mptcp_addr_info *skc);
 bool mptcp_userspace_pm_is_backup(struct mptcp_sock *msk, struct mptcp_addr_info *skc);
-- 
2.43.0

Hi Geliang,

On 20/02/2025 03:57, Geliang Tang wrote:
> From: Geliang Tang <tanggeliang@kylinos.cn>
> 
> The following code in mptcp_userspace_pm_get_local_id() that assigns "skc"
> to "new_entry" is not allowed in BPF if we use the same code to implement
> the get_local_id() interface of a BFP path manager:
> 
> 	memset(&new_entry, 0, sizeof(struct mptcp_pm_addr_entry));
> 	new_entry.addr = *skc;
> 	new_entry.addr.id = 0;
> 	new_entry.flags = MPTCP_PM_ADDR_FLAG_IMPLICIT;
> 
> To solve the issue, this patch moves this assignment to "new_entry" forward
> to mptcp_pm_get_local_id(), and then passing "new_entry" as a parameter to
> both mptcp_pm_nl_get_local_id() and mptcp_userspace_pm_get_local_id().
> 
> Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
> ---
>  net/mptcp/pm.c           | 11 ++++++++---
>  net/mptcp/pm_netlink.c   |  9 ++++-----
>  net/mptcp/pm_userspace.c | 17 ++++++-----------
>  net/mptcp/protocol.h     |  6 ++++--
>  4 files changed, 22 insertions(+), 21 deletions(-)
> 
> diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
> index 16cacce6c10f..94620ab172b7 100644
> --- a/net/mptcp/pm.c
> +++ b/net/mptcp/pm.c
> @@ -403,20 +403,25 @@ bool mptcp_pm_rm_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
>  
>  int mptcp_pm_get_local_id(struct mptcp_sock *msk, struct sock_common *skc)
>  {
> -	struct mptcp_addr_info skc_local;
> +	struct mptcp_pm_addr_entry skc_local;
>  	struct mptcp_addr_info msk_local;
>  
>  	if (WARN_ON_ONCE(!msk))
>  		return -1;
>  
> +	memset(&skc_local, 0, sizeof(struct mptcp_pm_addr_entry));

Detail: do we need memset? Can you not initialise it to 0 instead?

  struct mptcp_pm_addr_entry skc_local = { 0 };

> +
>  	/* The 0 ID mapping is defined by the first subflow, copied into the msk
>  	 * addr
>  	 */
>  	mptcp_local_address((struct sock_common *)msk, &msk_local);
> -	mptcp_local_address((struct sock_common *)skc, &skc_local);
> -	if (mptcp_addresses_equal(&msk_local, &skc_local, false))
> +	mptcp_local_address((struct sock_common *)skc, &skc_local.addr);
> +	if (mptcp_addresses_equal(&msk_local, &skc_local.addr, false))
>  		return 0;
>  
> +	skc_local.addr.id = 0;
> +	skc_local.flags = MPTCP_PM_ADDR_FLAG_IMPLICIT;
> +
>  	if (mptcp_pm_is_userspace(msk))
>  		return mptcp_userspace_pm_get_local_id(msk, &skc_local);
>  	return mptcp_pm_nl_get_local_id(msk, &skc_local);
> diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
> index d4328443d844..0a0fe890c53d 100644
> --- a/net/mptcp/pm_netlink.c
> +++ b/net/mptcp/pm_netlink.c

(...)

> @@ -1159,11 +1160,9 @@ int mptcp_pm_nl_get_local_id(struct mptcp_sock *msk, struct mptcp_addr_info *skc
>  	if (!entry)
>  		return -ENOMEM;
>  
> -	entry->addr = *skc;
> -	entry->addr.id = 0;
> +	*entry = *skc;
>  	entry->addr.port = 0;
>  	entry->ifindex = 0;
> -	entry->flags = MPTCP_PM_ADDR_FLAG_IMPLICIT;
>  	entry->lsk = NULL;
Small detail: is it still needed to reset all these info (except the
port number)?

If I'm not mistaken, now all the "entry" should be set to 0, no?

>  	ret = mptcp_pm_nl_append_new_local_addr(pernet, entry, true);
>  	if (ret < 0)
Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.