[PATCH v2 1/5] netlink: Reverse the patch which removed filtering

From: Anjali Kulkarni
Date: Tue Mar 14 2023 - 22:20:00 EST


To use filtering at the connector & cn_proc layers, we need to enable
filtering in the netlink layer. This reverses the patch which removed
netlink filtering.

Signed-off-by: Anjali Kulkarni <anjali.k.kulkarni@xxxxxxxxxx>
---
include/linux/netlink.h | 5 +++++
net/netlink/af_netlink.c | 25 +++++++++++++++++++++++--
2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index c43ac7690eca..866bbc5a4c8d 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -206,6 +206,11 @@ bool netlink_strict_get_check(struct sk_buff *skb);
int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock);
int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid,
__u32 group, gfp_t allocation);
+int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb,
+ __u32 portid, __u32 group, gfp_t allocation,
+ int (*filter)(struct sock *dsk,
+ struct sk_buff *skb, void *data),
+ void *filter_data);
int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code);
int netlink_register_notifier(struct notifier_block *nb);
int netlink_unregister_notifier(struct notifier_block *nb);
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index c64277659753..003c7e6ec9be 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1432,6 +1432,8 @@ struct netlink_broadcast_data {
int delivered;
gfp_t allocation;
struct sk_buff *skb, *skb2;
+ int (*tx_filter)(struct sock *dsk, struct sk_buff *skb, void *data);
+ void *tx_data;
};

static void do_one_broadcast(struct sock *sk,
@@ -1485,6 +1487,11 @@ static void do_one_broadcast(struct sock *sk,
p->delivery_failure = 1;
goto out;
}
+ if (p->tx_filter && p->tx_filter(sk, p->skb2, p->tx_data)) {
+ kfree_skb(p->skb2);
+ p->skb2 = NULL;
+ goto out;
+ }
if (sk_filter(sk, p->skb2)) {
kfree_skb(p->skb2);
p->skb2 = NULL;
@@ -1507,8 +1514,12 @@ static void do_one_broadcast(struct sock *sk,
sock_put(sk);
}

-int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, u32 portid,
- u32 group, gfp_t allocation)
+int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb,
+ u32 portid,
+ u32 group, gfp_t allocation,
+ int (*filter)(struct sock *dsk,
+ struct sk_buff *skb, void *data),
+ void *filter_data)
{
struct net *net = sock_net(ssk);
struct netlink_broadcast_data info;
@@ -1527,6 +1538,8 @@ int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, u32 portid,
info.allocation = allocation;
info.skb = skb;
info.skb2 = NULL;
+ info.tx_filter = filter;
+ info.tx_data = filter_data;

/* While we sleep in clone, do not allow to change socket list */

@@ -1552,6 +1565,14 @@ int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, u32 portid,
}
return -ESRCH;
}
+EXPORT_SYMBOL(netlink_broadcast_filtered);
+
+int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, u32 portid,
+ u32 group, gfp_t allocation)
+{
+ return netlink_broadcast_filtered(ssk, skb, portid, group, allocation,
+ NULL, NULL);
+}
EXPORT_SYMBOL(netlink_broadcast);

struct netlink_set_err_data {
--
2.39.2