[PATCH net-next v10 2/6] netlink: Add new netlink_release function

Anjali Kulkarni
2023-07-19T20:19:31Z

A new function netlink_release is added in netlink_sock to store the
protocol's release function. This is called when the socket is deleted.
This can be supplied by the protocol via the release function in
netlink_kernel_cfg. This is being added for the NETLINK_CONNECTOR
protocol, so it can free it's data when socket is deleted.

Signed-off-by: Anjali Kulkarni <anjali.k.kulkarni@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
---
include/linux/netlink.h | 1 +
net/netlink/af_netlink.c | 6 ++++++
net/netlink/af_netlink.h | 4 ++++
3 files changed, 11 insertions(+)

diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index 3a6563681b50..75d7de34c908 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -50,6 +50,7 @@ struct netlink_kernel_cfg {
struct mutex *cb_mutex;
int (*bind)(struct net *net, int group);
void (*unbind)(struct net *net, int group);
+ void (*release) (struct sock *sk, unsigned long *groups);
};

struct sock *__netlink_kernel_create(struct net *net, int unit,
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 6c0bcde620e8..96c605e45235 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -677,6 +677,7 @@ static int netlink_create(struct net *net, struct socket *sock, int protocol,
struct netlink_sock *nlk;
int (*bind)(struct net *net, int group);
void (*unbind)(struct net *net, int group);
+ void (*release)(struct sock *sock, unsigned long *groups);
int err = 0;

sock->state = SS_UNCONNECTED;
@@ -704,6 +705,7 @@ static int netlink_create(struct net *net, struct socket *sock, int protocol,
cb_mutex = nl_table[protocol].cb_mutex;
bind = nl_table[protocol].bind;
unbind = nl_table[protocol].unbind;
+ release = nl_table[protocol].release;
netlink_unlock_table();

if (err < 0)
@@ -719,6 +721,7 @@ static int netlink_create(struct net *net, struct socket *sock, int protocol,
nlk->module = module;
nlk->netlink_bind = bind;
nlk->netlink_unbind = unbind;
+ nlk->netlink_release = release;
out:
return err;

@@ -763,6 +766,8 @@ static int netlink_release(struct socket *sock)
* OK. Socket is unlinked, any packets that arrive now
* will be purged.
*/
+ if (nlk->netlink_release)
+ nlk->netlink_release(sk, nlk->groups);

/* must not acquire netlink_table_lock in any way again before unbind
* and notifying genetlink is done as otherwise it might deadlock
@@ -2089,6 +2094,7 @@ __netlink_kernel_create(struct net *net, int unit, struct module *module,
if (cfg) {
nl_table[unit].bind = cfg->bind;
nl_table[unit].unbind = cfg->unbind;
+ nl_table[unit].release = cfg->release;
nl_table[unit].flags = cfg->flags;
}
nl_table[unit].registered = 1;
diff --git a/net/netlink/af_netlink.h b/net/netlink/af_netlink.h
index 90a3198a9b7f..fd424cd63f31 100644
--- a/net/netlink/af_netlink.h
+++ b/net/netlink/af_netlink.h
@@ -42,6 +42,8 @@ struct netlink_sock {
void (*netlink_rcv)(struct sk_buff *skb);
int (*netlink_bind)(struct net *net, int group);
void (*netlink_unbind)(struct net *net, int group);
+ void (*netlink_release)(struct sock *sk,
+ unsigned long *groups);
struct module *module;

struct rhash_head node;
@@ -64,6 +66,8 @@ struct netlink_table {
struct module *module;
int (*bind)(struct net *net, int group);
void (*unbind)(struct net *net, int group);
+ void (*release)(struct sock *sk,
+ unsigned long *groups);
int registered;
};

--
2.41.0