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connector/cn_proc: Add filtering to fix some bugs

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The current proc connector code has the foll. bugs - if there are more
than one listeners for the proc connector messages, and one of them
deregisters for listening using PROC_CN_MCAST_IGNORE, they will still get
all proc connector messages, as long as there is another listener.

Another issue is if one client calls PROC_CN_MCAST_LISTEN, and another one
calls PROC_CN_MCAST_IGNORE, then both will end up not getting any messages.

This patch adds filtering and drops packet if client has sent
PROC_CN_MCAST_IGNORE. This data is stored in the client socket's
sk_user_data. In addition, we only increment or decrement
proc_event_num_listeners once per client. This fixes the above issues.

cn_release is the release function added for NETLINK_CONNECTOR. It uses
the newly added netlink_release function added to netlink_sock. It will
free sk_user_data.

Signed-off-by: Anjali Kulkarni <anjali.k.kulkarni@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Anjali Kulkarni
2023-07-19 13:18:18 -07:00
committed by David S. Miller
parent a4c9a56e6a
commit 2aa1f7a1f4
5 changed files with 100 additions and 35 deletions
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8
include/linux/connector.h
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@@ -90,13 +90,19 @@ void cn_del_callback(const struct cb_id *id);
* If @group is not zero, then message will be delivered
* to the specified group.
* @gfp_mask: GFP mask.
* @filter: Filter function to be used at netlink layer.
* @filter_data:Filter data to be supplied to the filter function
*
* It can be safely called from softirq context, but may silently
* fail under strong memory pressure.
*
* If there are no listeners for given group %-ESRCH can be returned.
*/
int cn_netlink_send_mult(struct cn_msg *msg, u16 len, u32 portid, u32 group, gfp_t gfp_mask);
int cn_netlink_send_mult(struct cn_msg *msg, u16 len, u32 portid,
u32 group, gfp_t gfp_mask,
int (*filter)(struct sock *dsk, struct sk_buff *skb,
void *data),
void *filter_data);
/**
* cn_netlink_send - Sends message to the specified groups.