mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-10-03 23:58:05 +00:00
ee1c244219
In addition to the problem Jeff Layton reported, I looked at the code and reproduced the same warning by subscribing and removing the genl family with a socket still open. This is a fairly tricky race which originates in the fact that generic netlink allows the family to go away while sockets are still open - unlike regular netlink which has a module refcount for every open socket so in general this cannot be triggered. Trying to resolve this issue by the obvious locking isn't possible as it will result in deadlocks between unregistration and group unbind notification (which incidentally lockdep doesn't find due to the home grown locking in the netlink table.) To really resolve this, introduce a "closing socket" reference counter (for generic netlink only, as it's the only affected family) in the core netlink code and use that in generic netlink to wait for all the sockets that are being closed at the same time as a generic netlink family is removed. This fixes the race that when a socket is closed, it will should call the unbind, but if the family is removed at the same time the unbind will not find it, leading to the warning. The real problem though is that in this case the unbind could actually find a new family that is registered to have a multicast group with the same ID, and call its mcast_unbind() leading to confusing. Also remove the warning since it would still trigger, but is now no longer a problem. This also moves the code in af_netlink.c to before unreferencing the module to avoid having the same problem in the normal non-genl case. Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
79 lines
1.8 KiB
C
79 lines
1.8 KiB
C
#ifndef _AF_NETLINK_H
|
|
#define _AF_NETLINK_H
|
|
|
|
#include <linux/rhashtable.h>
|
|
#include <linux/atomic.h>
|
|
#include <net/sock.h>
|
|
|
|
#define NLGRPSZ(x) (ALIGN(x, sizeof(unsigned long) * 8) / 8)
|
|
#define NLGRPLONGS(x) (NLGRPSZ(x)/sizeof(unsigned long))
|
|
|
|
struct netlink_ring {
|
|
void **pg_vec;
|
|
unsigned int head;
|
|
unsigned int frames_per_block;
|
|
unsigned int frame_size;
|
|
unsigned int frame_max;
|
|
|
|
unsigned int pg_vec_order;
|
|
unsigned int pg_vec_pages;
|
|
unsigned int pg_vec_len;
|
|
|
|
atomic_t pending;
|
|
};
|
|
|
|
struct netlink_sock {
|
|
/* struct sock has to be the first member of netlink_sock */
|
|
struct sock sk;
|
|
u32 portid;
|
|
u32 dst_portid;
|
|
u32 dst_group;
|
|
u32 flags;
|
|
u32 subscriptions;
|
|
u32 ngroups;
|
|
unsigned long *groups;
|
|
unsigned long state;
|
|
size_t max_recvmsg_len;
|
|
wait_queue_head_t wait;
|
|
bool cb_running;
|
|
struct netlink_callback cb;
|
|
struct mutex *cb_mutex;
|
|
struct mutex cb_def_mutex;
|
|
void (*netlink_rcv)(struct sk_buff *skb);
|
|
int (*netlink_bind)(struct net *net, int group);
|
|
void (*netlink_unbind)(struct net *net, int group);
|
|
struct module *module;
|
|
#ifdef CONFIG_NETLINK_MMAP
|
|
struct mutex pg_vec_lock;
|
|
struct netlink_ring rx_ring;
|
|
struct netlink_ring tx_ring;
|
|
atomic_t mapped;
|
|
#endif /* CONFIG_NETLINK_MMAP */
|
|
|
|
struct rhash_head node;
|
|
};
|
|
|
|
static inline struct netlink_sock *nlk_sk(struct sock *sk)
|
|
{
|
|
return container_of(sk, struct netlink_sock, sk);
|
|
}
|
|
|
|
struct netlink_table {
|
|
struct rhashtable hash;
|
|
struct hlist_head mc_list;
|
|
struct listeners __rcu *listeners;
|
|
unsigned int flags;
|
|
unsigned int groups;
|
|
struct mutex *cb_mutex;
|
|
struct module *module;
|
|
int (*bind)(struct net *net, int group);
|
|
void (*unbind)(struct net *net, int group);
|
|
bool (*compare)(struct net *net, struct sock *sock);
|
|
int registered;
|
|
};
|
|
|
|
extern struct netlink_table *nl_table;
|
|
extern rwlock_t nl_table_lock;
|
|
extern struct mutex nl_sk_hash_lock;
|
|
|
|
#endif
|