Commit eb4cb008 authored by Craig Gallek's avatar Craig Gallek Committed by David S. Miller
Browse files

sock_diag: define destruction multicast groups 



These groups will contain socket-destruction events for
AF_INET/AF_INET6, IPPROTO_TCP/IPPROTO_UDP.

Near the end of socket destruction, a check for listeners is
performed.  In the presence of a listener, rather than completely
cleanup the socket, a unit of work will be added to a private
work queue which will first broadcast information about the socket
and then finish the cleanup operation.

Signed-off-by: default avatarCraig Gallek <kraig@google.com>
Acked-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 916035dd

include/linux/sock_diag.h

+42 −0
Original line number Diff line number Diff line 
#ifndef __SOCK_DIAG_H__

#define __SOCK_DIAG_H__



#include <linux/netlink.h>

#include <linux/user_namespace.h>

#include <net/net_namespace.h>

#include <net/sock.h>

#include <uapi/linux/sock_diag.h>



struct sk_buff;
@@ -11,6 +14,7 @@ struct sock; 
struct sock_diag_handler {

	__u8 family;

	int (*dump)(struct sk_buff *skb, struct nlmsghdr *nlh);

	int (*get_info)(struct sk_buff *skb, struct sock *sk);

};



int sock_diag_register(const struct sock_diag_handler *h);
@@ -26,4 +30,42 @@ int sock_diag_put_meminfo(struct sock *sk, struct sk_buff *skb, int attr); 
int sock_diag_put_filterinfo(bool may_report_filterinfo, struct sock *sk,

			     struct sk_buff *skb, int attrtype);



static inline

enum sknetlink_groups sock_diag_destroy_group(const struct sock *sk)

{

	switch (sk->sk_family) {

	case AF_INET:

		switch (sk->sk_protocol) {

		case IPPROTO_TCP:

			return SKNLGRP_INET_TCP_DESTROY;

		case IPPROTO_UDP:

			return SKNLGRP_INET_UDP_DESTROY;

		default:

			return SKNLGRP_NONE;

		}

	case AF_INET6:

		switch (sk->sk_protocol) {

		case IPPROTO_TCP:

			return SKNLGRP_INET6_TCP_DESTROY;

		case IPPROTO_UDP:

			return SKNLGRP_INET6_UDP_DESTROY;

		default:

			return SKNLGRP_NONE;

		}

	default:

		return SKNLGRP_NONE;

	}

}



static inline

bool sock_diag_has_destroy_listeners(const struct sock *sk)

{

	const struct net *n = sock_net(sk);

	const enum sknetlink_groups group = sock_diag_destroy_group(sk);



	return group != SKNLGRP_NONE && n->diag_nlsk &&

		netlink_has_listeners(n->diag_nlsk, group);

}

void sock_diag_broadcast_destroy(struct sock *sk);



#endif

include/net/sock.h

+1 −0
Original line number Diff line number Diff line
@@ -1518,6 +1518,7 @@ static inline void unlock_sock_fast(struct sock *sk, bool slow) 
struct sock *sk_alloc(struct net *net, int family, gfp_t priority,

		      struct proto *prot, int kern);

void sk_free(struct sock *sk);

void sk_destruct(struct sock *sk);

struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority);



struct sk_buff *sock_wmalloc(struct sock *sk, unsigned long size, int force,

include/uapi/linux/sock_diag.h

+10 −0
Original line number Diff line number Diff line
@@ -23,4 +23,14 @@ enum { 
	SK_MEMINFO_VARS,

};



enum sknetlink_groups {

	SKNLGRP_NONE,

	SKNLGRP_INET_TCP_DESTROY,

	SKNLGRP_INET_UDP_DESTROY,

	SKNLGRP_INET6_TCP_DESTROY,

	SKNLGRP_INET6_UDP_DESTROY,

	__SKNLGRP_MAX,

};

#define SKNLGRP_MAX	(__SKNLGRP_MAX - 1)



#endif /* _UAPI__SOCK_DIAG_H__ */

net/core/sock.c

+10 −1
Original line number Diff line number Diff line
@@ -131,6 +131,7 @@ 
#include <linux/ipsec.h>

#include <net/cls_cgroup.h>

#include <net/netprio_cgroup.h>

#include <linux/sock_diag.h>



#include <linux/filter.h>
@@ -1423,7 +1424,7 @@ struct sock *sk_alloc(struct net *net, int family, gfp_t priority, 
}

EXPORT_SYMBOL(sk_alloc);



static void __sk_free(struct sock *sk)

void sk_destruct(struct sock *sk)

{

	struct sk_filter *filter;
@@ -1451,6 +1452,14 @@ static void __sk_free(struct sock *sk) 
	sk_prot_free(sk->sk_prot_creator, sk);

}



static void __sk_free(struct sock *sk)

{

	if (unlikely(sock_diag_has_destroy_listeners(sk)))

		sock_diag_broadcast_destroy(sk);

	else

		sk_destruct(sk);

}



void sk_free(struct sock *sk)

{

	/*

net/core/sock_diag.c

+85 −0
Original line number Diff line number Diff line
@@ -5,6 +5,9 @@ 
#include <net/net_namespace.h>

#include <linux/module.h>

#include <net/sock.h>

#include <linux/kernel.h>

#include <linux/tcp.h>

#include <linux/workqueue.h>



#include <linux/inet_diag.h>

#include <linux/sock_diag.h>
@@ -12,6 +15,7 @@ 
static const struct sock_diag_handler *sock_diag_handlers[AF_MAX];

static int (*inet_rcv_compat)(struct sk_buff *skb, struct nlmsghdr *nlh);

static DEFINE_MUTEX(sock_diag_table_mutex);

static struct workqueue_struct *broadcast_wq;



static u64 sock_gen_cookie(struct sock *sk)

{
@@ -101,6 +105,62 @@ out: 
}

EXPORT_SYMBOL(sock_diag_put_filterinfo);



struct broadcast_sk {

	struct sock *sk;

	struct work_struct work;

};



static size_t sock_diag_nlmsg_size(void)

{

	return NLMSG_ALIGN(sizeof(struct inet_diag_msg)

	       + nla_total_size(sizeof(u8)) /* INET_DIAG_PROTOCOL */

	       + nla_total_size(sizeof(struct tcp_info))); /* INET_DIAG_INFO */

}



static void sock_diag_broadcast_destroy_work(struct work_struct *work)

{

	struct broadcast_sk *bsk =

		container_of(work, struct broadcast_sk, work);

	struct sock *sk = bsk->sk;

	const struct sock_diag_handler *hndl;

	struct sk_buff *skb;

	const enum sknetlink_groups group = sock_diag_destroy_group(sk);

	int err = -1;



	WARN_ON(group == SKNLGRP_NONE);



	skb = nlmsg_new(sock_diag_nlmsg_size(), GFP_KERNEL);

	if (!skb)

		goto out;



	mutex_lock(&sock_diag_table_mutex);

	hndl = sock_diag_handlers[sk->sk_family];

	if (hndl && hndl->get_info)

		err = hndl->get_info(skb, sk);

	mutex_unlock(&sock_diag_table_mutex);



	if (!err)

		nlmsg_multicast(sock_net(sk)->diag_nlsk, skb, 0, group,

				GFP_KERNEL);

	else

		kfree_skb(skb);

out:

	sk_destruct(sk);

	kfree(bsk);

}



void sock_diag_broadcast_destroy(struct sock *sk)

{

	/* Note, this function is often called from an interrupt context. */

	struct broadcast_sk *bsk =

		kmalloc(sizeof(struct broadcast_sk), GFP_ATOMIC);

	if (!bsk)

		return sk_destruct(sk);

	bsk->sk = sk;

	INIT_WORK(&bsk->work, sock_diag_broadcast_destroy_work);

	queue_work(broadcast_wq, &bsk->work);

}



void sock_diag_register_inet_compat(int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh))

{

	mutex_lock(&sock_diag_table_mutex);
@@ -211,10 +271,32 @@ static void sock_diag_rcv(struct sk_buff *skb) 
	mutex_unlock(&sock_diag_mutex);

}



static int sock_diag_bind(struct net *net, int group)

{

	switch (group) {

	case SKNLGRP_INET_TCP_DESTROY:

	case SKNLGRP_INET_UDP_DESTROY:

		if (!sock_diag_handlers[AF_INET])

			request_module("net-pf-%d-proto-%d-type-%d", PF_NETLINK,

				       NETLINK_SOCK_DIAG, AF_INET);

		break;

	case SKNLGRP_INET6_TCP_DESTROY:

	case SKNLGRP_INET6_UDP_DESTROY:

		if (!sock_diag_handlers[AF_INET6])

			request_module("net-pf-%d-proto-%d-type-%d", PF_NETLINK,

				       NETLINK_SOCK_DIAG, AF_INET);

		break;

	}

	return 0;

}



static int __net_init diag_net_init(struct net *net)

{

	struct netlink_kernel_cfg cfg = {

		.groups	= SKNLGRP_MAX,

		.input	= sock_diag_rcv,

		.bind	= sock_diag_bind,

		.flags	= NL_CFG_F_NONROOT_RECV,

	};



	net->diag_nlsk = netlink_kernel_create(net, NETLINK_SOCK_DIAG, &cfg);
@@ -234,12 +316,15 @@ static struct pernet_operations diag_net_ops = { 


static int __init sock_diag_init(void)

{

	broadcast_wq = alloc_workqueue("sock_diag_events", 0, 0);

	BUG_ON(!broadcast_wq);

	return register_pernet_subsys(&diag_net_ops);

}



static void __exit sock_diag_exit(void)

{

	unregister_pernet_subsys(&diag_net_ops);

	destroy_workqueue(broadcast_wq);

}



module_init(sock_diag_init);

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