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af_netlink.c
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af_netlink.c
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/*
* NETLINK Kernel-user communication protocol.
*
* Authors: Alan Cox <[email protected]>
* Alexey Kuznetsov <[email protected]>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Tue Jun 26 14:36:48 MEST 2001 Herbert "herp" Rosmanith
* added netlink_proto_exit
* Tue Jan 22 18:32:44 BRST 2002 Arnaldo C. de Melo <[email protected]>
* use nlk_sk, as sk->protinfo is on a diet 8)
* Fri Jul 22 19:51:12 MEST 2005 Harald Welte <[email protected]>
* - inc module use count of module that owns
* the kernel socket in case userspace opens
* socket of same protocol
* - remove all module support, since netlink is
* mandatory if CONFIG_NET=y these days
*/
#include <linux/module.h>
#include <linux/capability.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/socket.h>
#include <linux/un.h>
#include <linux/fcntl.h>
#include <linux/termios.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <asm/uaccess.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/rtnetlink.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/notifier.h>
#include <linux/security.h>
#include <linux/jhash.h>
#include <linux/jiffies.h>
#include <linux/random.h>
#include <linux/bitops.h>
#include <linux/mm.h>
#include <linux/types.h>
#include <linux/audit.h>
#include <linux/mutex.h>
#include <net/net_namespace.h>
#include <net/sock.h>
#include <net/scm.h>
#include <net/netlink.h>
#define NLGRPSZ(x) (ALIGN(x, sizeof(unsigned long) * 8) / 8)
#define NLGRPLONGS(x) (NLGRPSZ(x)/sizeof(unsigned long))
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;
wait_queue_head_t wait;
struct netlink_callback *cb;
struct mutex *cb_mutex;
struct mutex cb_def_mutex;
void (*netlink_rcv)(struct sk_buff *skb);
void (*netlink_bind)(int group);
struct module *module;
};
struct listeners {
struct rcu_head rcu;
unsigned long masks[0];
};
#define NETLINK_KERNEL_SOCKET 0x1
#define NETLINK_RECV_PKTINFO 0x2
#define NETLINK_BROADCAST_SEND_ERROR 0x4
#define NETLINK_RECV_NO_ENOBUFS 0x8
static inline struct netlink_sock *nlk_sk(struct sock *sk)
{
return container_of(sk, struct netlink_sock, sk);
}
static inline int netlink_is_kernel(struct sock *sk)
{
return nlk_sk(sk)->flags & NETLINK_KERNEL_SOCKET;
}
struct nl_portid_hash {
struct hlist_head *table;
unsigned long rehash_time;
unsigned int mask;
unsigned int shift;
unsigned int entries;
unsigned int max_shift;
u32 rnd;
};
struct netlink_table {
struct nl_portid_hash hash;
struct hlist_head mc_list;
struct listeners __rcu *listeners;
unsigned int flags;
unsigned int groups;
struct mutex *cb_mutex;
struct module *module;
void (*bind)(int group);
int registered;
};
static struct netlink_table *nl_table;
static DECLARE_WAIT_QUEUE_HEAD(nl_table_wait);
static int netlink_dump(struct sock *sk);
static DEFINE_RWLOCK(nl_table_lock);
static atomic_t nl_table_users = ATOMIC_INIT(0);
#define nl_deref_protected(X) rcu_dereference_protected(X, lockdep_is_held(&nl_table_lock));
static ATOMIC_NOTIFIER_HEAD(netlink_chain);
static inline u32 netlink_group_mask(u32 group)
{
return group ? 1 << (group - 1) : 0;
}
static inline struct hlist_head *nl_portid_hashfn(struct nl_portid_hash *hash, u32 portid)
{
return &hash->table[jhash_1word(portid, hash->rnd) & hash->mask];
}
static void netlink_destroy_callback(struct netlink_callback *cb)
{
kfree_skb(cb->skb);
kfree(cb);
}
static void netlink_consume_callback(struct netlink_callback *cb)
{
consume_skb(cb->skb);
kfree(cb);
}
static void netlink_sock_destruct(struct sock *sk)
{
struct netlink_sock *nlk = nlk_sk(sk);
if (nlk->cb) {
if (nlk->cb->done)
nlk->cb->done(nlk->cb);
module_put(nlk->cb->module);
netlink_destroy_callback(nlk->cb);
}
skb_queue_purge(&sk->sk_receive_queue);
if (!sock_flag(sk, SOCK_DEAD)) {
printk(KERN_ERR "Freeing alive netlink socket %p\n", sk);
return;
}
WARN_ON(atomic_read(&sk->sk_rmem_alloc));
WARN_ON(atomic_read(&sk->sk_wmem_alloc));
WARN_ON(nlk_sk(sk)->groups);
}
/* This lock without WQ_FLAG_EXCLUSIVE is good on UP and it is _very_ bad on
* SMP. Look, when several writers sleep and reader wakes them up, all but one
* immediately hit write lock and grab all the cpus. Exclusive sleep solves
* this, _but_ remember, it adds useless work on UP machines.
*/
void netlink_table_grab(void)
__acquires(nl_table_lock)
{
might_sleep();
write_lock_irq(&nl_table_lock);
if (atomic_read(&nl_table_users)) {
DECLARE_WAITQUEUE(wait, current);
add_wait_queue_exclusive(&nl_table_wait, &wait);
for (;;) {
set_current_state(TASK_UNINTERRUPTIBLE);
if (atomic_read(&nl_table_users) == 0)
break;
write_unlock_irq(&nl_table_lock);
schedule();
write_lock_irq(&nl_table_lock);
}
__set_current_state(TASK_RUNNING);
remove_wait_queue(&nl_table_wait, &wait);
}
}
void netlink_table_ungrab(void)
__releases(nl_table_lock)
{
write_unlock_irq(&nl_table_lock);
wake_up(&nl_table_wait);
}
static inline void
netlink_lock_table(void)
{
/* read_lock() synchronizes us to netlink_table_grab */
read_lock(&nl_table_lock);
atomic_inc(&nl_table_users);
read_unlock(&nl_table_lock);
}
static inline void
netlink_unlock_table(void)
{
if (atomic_dec_and_test(&nl_table_users))
wake_up(&nl_table_wait);
}
static struct sock *netlink_lookup(struct net *net, int protocol, u32 portid)
{
struct nl_portid_hash *hash = &nl_table[protocol].hash;
struct hlist_head *head;
struct sock *sk;
struct hlist_node *node;
read_lock(&nl_table_lock);
head = nl_portid_hashfn(hash, portid);
sk_for_each(sk, node, head) {
if (net_eq(sock_net(sk), net) && (nlk_sk(sk)->portid == portid)) {
sock_hold(sk);
goto found;
}
}
sk = NULL;
found:
read_unlock(&nl_table_lock);
return sk;
}
static struct hlist_head *nl_portid_hash_zalloc(size_t size)
{
if (size <= PAGE_SIZE)
return kzalloc(size, GFP_ATOMIC);
else
return (struct hlist_head *)
__get_free_pages(GFP_ATOMIC | __GFP_ZERO,
get_order(size));
}
static void nl_portid_hash_free(struct hlist_head *table, size_t size)
{
if (size <= PAGE_SIZE)
kfree(table);
else
free_pages((unsigned long)table, get_order(size));
}
static int nl_portid_hash_rehash(struct nl_portid_hash *hash, int grow)
{
unsigned int omask, mask, shift;
size_t osize, size;
struct hlist_head *otable, *table;
int i;
omask = mask = hash->mask;
osize = size = (mask + 1) * sizeof(*table);
shift = hash->shift;
if (grow) {
if (++shift > hash->max_shift)
return 0;
mask = mask * 2 + 1;
size *= 2;
}
table = nl_portid_hash_zalloc(size);
if (!table)
return 0;
otable = hash->table;
hash->table = table;
hash->mask = mask;
hash->shift = shift;
get_random_bytes(&hash->rnd, sizeof(hash->rnd));
for (i = 0; i <= omask; i++) {
struct sock *sk;
struct hlist_node *node, *tmp;
sk_for_each_safe(sk, node, tmp, &otable[i])
__sk_add_node(sk, nl_portid_hashfn(hash, nlk_sk(sk)->portid));
}
nl_portid_hash_free(otable, osize);
hash->rehash_time = jiffies + 10 * 60 * HZ;
return 1;
}
static inline int nl_portid_hash_dilute(struct nl_portid_hash *hash, int len)
{
int avg = hash->entries >> hash->shift;
if (unlikely(avg > 1) && nl_portid_hash_rehash(hash, 1))
return 1;
if (unlikely(len > avg) && time_after(jiffies, hash->rehash_time)) {
nl_portid_hash_rehash(hash, 0);
return 1;
}
return 0;
}
static const struct proto_ops netlink_ops;
static void
netlink_update_listeners(struct sock *sk)
{
struct netlink_table *tbl = &nl_table[sk->sk_protocol];
struct hlist_node *node;
unsigned long mask;
unsigned int i;
struct listeners *listeners;
listeners = nl_deref_protected(tbl->listeners);
if (!listeners)
return;
for (i = 0; i < NLGRPLONGS(tbl->groups); i++) {
mask = 0;
sk_for_each_bound(sk, node, &tbl->mc_list) {
if (i < NLGRPLONGS(nlk_sk(sk)->ngroups))
mask |= nlk_sk(sk)->groups[i];
}
listeners->masks[i] = mask;
}
/* this function is only called with the netlink table "grabbed", which
* makes sure updates are visible before bind or setsockopt return. */
}
static int netlink_insert(struct sock *sk, struct net *net, u32 portid)
{
struct nl_portid_hash *hash = &nl_table[sk->sk_protocol].hash;
struct hlist_head *head;
int err = -EADDRINUSE;
struct sock *osk;
struct hlist_node *node;
int len;
netlink_table_grab();
head = nl_portid_hashfn(hash, portid);
len = 0;
sk_for_each(osk, node, head) {
if (net_eq(sock_net(osk), net) && (nlk_sk(osk)->portid == portid))
break;
len++;
}
if (node)
goto err;
err = -EBUSY;
if (nlk_sk(sk)->portid)
goto err;
err = -ENOMEM;
if (BITS_PER_LONG > 32 && unlikely(hash->entries >= UINT_MAX))
goto err;
if (len && nl_portid_hash_dilute(hash, len))
head = nl_portid_hashfn(hash, portid);
hash->entries++;
nlk_sk(sk)->portid = portid;
sk_add_node(sk, head);
err = 0;
err:
netlink_table_ungrab();
return err;
}
static void netlink_remove(struct sock *sk)
{
netlink_table_grab();
if (sk_del_node_init(sk))
nl_table[sk->sk_protocol].hash.entries--;
if (nlk_sk(sk)->subscriptions)
__sk_del_bind_node(sk);
netlink_table_ungrab();
}
static struct proto netlink_proto = {
.name = "NETLINK",
.owner = THIS_MODULE,
.obj_size = sizeof(struct netlink_sock),
};
static int __netlink_create(struct net *net, struct socket *sock,
struct mutex *cb_mutex, int protocol)
{
struct sock *sk;
struct netlink_sock *nlk;
sock->ops = &netlink_ops;
sk = sk_alloc(net, PF_NETLINK, GFP_KERNEL, &netlink_proto);
if (!sk)
return -ENOMEM;
sock_init_data(sock, sk);
nlk = nlk_sk(sk);
if (cb_mutex) {
nlk->cb_mutex = cb_mutex;
} else {
nlk->cb_mutex = &nlk->cb_def_mutex;
mutex_init(nlk->cb_mutex);
}
init_waitqueue_head(&nlk->wait);
sk->sk_destruct = netlink_sock_destruct;
sk->sk_protocol = protocol;
return 0;
}
static int netlink_create(struct net *net, struct socket *sock, int protocol,
int kern)
{
struct module *module = NULL;
struct mutex *cb_mutex;
struct netlink_sock *nlk;
void (*bind)(int group);
int err = 0;
sock->state = SS_UNCONNECTED;
if (sock->type != SOCK_RAW && sock->type != SOCK_DGRAM)
return -ESOCKTNOSUPPORT;
if (protocol < 0 || protocol >= MAX_LINKS)
return -EPROTONOSUPPORT;
netlink_lock_table();
#ifdef CONFIG_MODULES
if (!nl_table[protocol].registered) {
netlink_unlock_table();
request_module("net-pf-%d-proto-%d", PF_NETLINK, protocol);
netlink_lock_table();
}
#endif
if (nl_table[protocol].registered &&
try_module_get(nl_table[protocol].module))
module = nl_table[protocol].module;
else
err = -EPROTONOSUPPORT;
cb_mutex = nl_table[protocol].cb_mutex;
bind = nl_table[protocol].bind;
netlink_unlock_table();
if (err < 0)
goto out;
err = __netlink_create(net, sock, cb_mutex, protocol);
if (err < 0)
goto out_module;
local_bh_disable();
sock_prot_inuse_add(net, &netlink_proto, 1);
local_bh_enable();
nlk = nlk_sk(sock->sk);
nlk->module = module;
nlk->netlink_bind = bind;
out:
return err;
out_module:
module_put(module);
goto out;
}
static int netlink_release(struct socket *sock)
{
struct sock *sk = sock->sk;
struct netlink_sock *nlk;
if (!sk)
return 0;
netlink_remove(sk);
sock_orphan(sk);
nlk = nlk_sk(sk);
/*
* OK. Socket is unlinked, any packets that arrive now
* will be purged.
*/
sock->sk = NULL;
wake_up_interruptible_all(&nlk->wait);
skb_queue_purge(&sk->sk_write_queue);
if (nlk->portid) {
struct netlink_notify n = {
.net = sock_net(sk),
.protocol = sk->sk_protocol,
.portid = nlk->portid,
};
atomic_notifier_call_chain(&netlink_chain,
NETLINK_URELEASE, &n);
}
module_put(nlk->module);
netlink_table_grab();
if (netlink_is_kernel(sk)) {
BUG_ON(nl_table[sk->sk_protocol].registered == 0);
if (--nl_table[sk->sk_protocol].registered == 0) {
struct listeners *old;
old = nl_deref_protected(nl_table[sk->sk_protocol].listeners);
RCU_INIT_POINTER(nl_table[sk->sk_protocol].listeners, NULL);
kfree_rcu(old, rcu);
nl_table[sk->sk_protocol].module = NULL;
nl_table[sk->sk_protocol].bind = NULL;
nl_table[sk->sk_protocol].flags = 0;
nl_table[sk->sk_protocol].registered = 0;
}
} else if (nlk->subscriptions) {
netlink_update_listeners(sk);
}
netlink_table_ungrab();
kfree(nlk->groups);
nlk->groups = NULL;
local_bh_disable();
sock_prot_inuse_add(sock_net(sk), &netlink_proto, -1);
local_bh_enable();
sock_put(sk);
return 0;
}
static int netlink_autobind(struct socket *sock)
{
struct sock *sk = sock->sk;
struct net *net = sock_net(sk);
struct nl_portid_hash *hash = &nl_table[sk->sk_protocol].hash;
struct hlist_head *head;
struct sock *osk;
struct hlist_node *node;
s32 portid = task_tgid_vnr(current);
int err;
static s32 rover = -4097;
retry:
cond_resched();
netlink_table_grab();
head = nl_portid_hashfn(hash, portid);
sk_for_each(osk, node, head) {
if (!net_eq(sock_net(osk), net))
continue;
if (nlk_sk(osk)->portid == portid) {
/* Bind collision, search negative portid values. */
portid = rover--;
if (rover > -4097)
rover = -4097;
netlink_table_ungrab();
goto retry;
}
}
netlink_table_ungrab();
err = netlink_insert(sk, net, portid);
if (err == -EADDRINUSE)
goto retry;
/* If 2 threads race to autobind, that is fine. */
if (err == -EBUSY)
err = 0;
return err;
}
static inline int netlink_capable(const struct socket *sock, unsigned int flag)
{
return (nl_table[sock->sk->sk_protocol].flags & flag) ||
ns_capable(sock_net(sock->sk)->user_ns, CAP_NET_ADMIN);
}
static void
netlink_update_subscriptions(struct sock *sk, unsigned int subscriptions)
{
struct netlink_sock *nlk = nlk_sk(sk);
if (nlk->subscriptions && !subscriptions)
__sk_del_bind_node(sk);
else if (!nlk->subscriptions && subscriptions)
sk_add_bind_node(sk, &nl_table[sk->sk_protocol].mc_list);
nlk->subscriptions = subscriptions;
}
static int netlink_realloc_groups(struct sock *sk)
{
struct netlink_sock *nlk = nlk_sk(sk);
unsigned int groups;
unsigned long *new_groups;
int err = 0;
netlink_table_grab();
groups = nl_table[sk->sk_protocol].groups;
if (!nl_table[sk->sk_protocol].registered) {
err = -ENOENT;
goto out_unlock;
}
if (nlk->ngroups >= groups)
goto out_unlock;
new_groups = krealloc(nlk->groups, NLGRPSZ(groups), GFP_ATOMIC);
if (new_groups == NULL) {
err = -ENOMEM;
goto out_unlock;
}
memset((char *)new_groups + NLGRPSZ(nlk->ngroups), 0,
NLGRPSZ(groups) - NLGRPSZ(nlk->ngroups));
nlk->groups = new_groups;
nlk->ngroups = groups;
out_unlock:
netlink_table_ungrab();
return err;
}
static int netlink_bind(struct socket *sock, struct sockaddr *addr,
int addr_len)
{
struct sock *sk = sock->sk;
struct net *net = sock_net(sk);
struct netlink_sock *nlk = nlk_sk(sk);
struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
int err;
if (addr_len < sizeof(struct sockaddr_nl))
return -EINVAL;
if (nladdr->nl_family != AF_NETLINK)
return -EINVAL;
/* Only superuser is allowed to listen multicasts */
if (nladdr->nl_groups) {
if (!netlink_capable(sock, NL_CFG_F_NONROOT_RECV))
return -EPERM;
err = netlink_realloc_groups(sk);
if (err)
return err;
}
if (nlk->portid) {
if (nladdr->nl_pid != nlk->portid)
return -EINVAL;
} else {
err = nladdr->nl_pid ?
netlink_insert(sk, net, nladdr->nl_pid) :
netlink_autobind(sock);
if (err)
return err;
}
if (!nladdr->nl_groups && (nlk->groups == NULL || !(u32)nlk->groups[0]))
return 0;
netlink_table_grab();
netlink_update_subscriptions(sk, nlk->subscriptions +
hweight32(nladdr->nl_groups) -
hweight32(nlk->groups[0]));
nlk->groups[0] = (nlk->groups[0] & ~0xffffffffUL) | nladdr->nl_groups;
netlink_update_listeners(sk);
netlink_table_ungrab();
if (nlk->netlink_bind && nlk->groups[0]) {
int i;
for (i=0; i<nlk->ngroups; i++) {
if (test_bit(i, nlk->groups))
nlk->netlink_bind(i);
}
}
return 0;
}
static int netlink_connect(struct socket *sock, struct sockaddr *addr,
int alen, int flags)
{
int err = 0;
struct sock *sk = sock->sk;
struct netlink_sock *nlk = nlk_sk(sk);
struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
if (alen < sizeof(addr->sa_family))
return -EINVAL;
if (addr->sa_family == AF_UNSPEC) {
sk->sk_state = NETLINK_UNCONNECTED;
nlk->dst_portid = 0;
nlk->dst_group = 0;
return 0;
}
if (addr->sa_family != AF_NETLINK)
return -EINVAL;
/* Only superuser is allowed to send multicasts */
if (nladdr->nl_groups && !netlink_capable(sock, NL_CFG_F_NONROOT_SEND))
return -EPERM;
if (!nlk->portid)
err = netlink_autobind(sock);
if (err == 0) {
sk->sk_state = NETLINK_CONNECTED;
nlk->dst_portid = nladdr->nl_pid;
nlk->dst_group = ffs(nladdr->nl_groups);
}
return err;
}
static int netlink_getname(struct socket *sock, struct sockaddr *addr,
int *addr_len, int peer)
{
struct sock *sk = sock->sk;
struct netlink_sock *nlk = nlk_sk(sk);
DECLARE_SOCKADDR(struct sockaddr_nl *, nladdr, addr);
nladdr->nl_family = AF_NETLINK;
nladdr->nl_pad = 0;
*addr_len = sizeof(*nladdr);
if (peer) {
nladdr->nl_pid = nlk->dst_portid;
nladdr->nl_groups = netlink_group_mask(nlk->dst_group);
} else {
nladdr->nl_pid = nlk->portid;
nladdr->nl_groups = nlk->groups ? nlk->groups[0] : 0;
}
return 0;
}
static void netlink_overrun(struct sock *sk)
{
struct netlink_sock *nlk = nlk_sk(sk);
if (!(nlk->flags & NETLINK_RECV_NO_ENOBUFS)) {
if (!test_and_set_bit(0, &nlk_sk(sk)->state)) {
sk->sk_err = ENOBUFS;
sk->sk_error_report(sk);
}
}
atomic_inc(&sk->sk_drops);
}
static struct sock *netlink_getsockbyportid(struct sock *ssk, u32 portid)
{
struct sock *sock;
struct netlink_sock *nlk;
sock = netlink_lookup(sock_net(ssk), ssk->sk_protocol, portid);
if (!sock)
return ERR_PTR(-ECONNREFUSED);
/* Don't bother queuing skb if kernel socket has no input function */
nlk = nlk_sk(sock);
if (sock->sk_state == NETLINK_CONNECTED &&
nlk->dst_portid != nlk_sk(ssk)->portid) {
sock_put(sock);
return ERR_PTR(-ECONNREFUSED);
}
return sock;
}
struct sock *netlink_getsockbyfilp(struct file *filp)
{
struct inode *inode = filp->f_path.dentry->d_inode;
struct sock *sock;
if (!S_ISSOCK(inode->i_mode))
return ERR_PTR(-ENOTSOCK);
sock = SOCKET_I(inode)->sk;
if (sock->sk_family != AF_NETLINK)
return ERR_PTR(-EINVAL);
sock_hold(sock);
return sock;
}
/*
* Attach a skb to a netlink socket.
* The caller must hold a reference to the destination socket. On error, the
* reference is dropped. The skb is not send to the destination, just all
* all error checks are performed and memory in the queue is reserved.
* Return values:
* < 0: error. skb freed, reference to sock dropped.
* 0: continue
* 1: repeat lookup - reference dropped while waiting for socket memory.
*/
int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
long *timeo, struct sock *ssk)
{
struct netlink_sock *nlk;
nlk = nlk_sk(sk);
if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
test_bit(0, &nlk->state)) {
DECLARE_WAITQUEUE(wait, current);
if (!*timeo) {
if (!ssk || netlink_is_kernel(ssk))
netlink_overrun(sk);
sock_put(sk);
kfree_skb(skb);
return -EAGAIN;
}
__set_current_state(TASK_INTERRUPTIBLE);
add_wait_queue(&nlk->wait, &wait);
if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
test_bit(0, &nlk->state)) &&
!sock_flag(sk, SOCK_DEAD))
*timeo = schedule_timeout(*timeo);
__set_current_state(TASK_RUNNING);
remove_wait_queue(&nlk->wait, &wait);
sock_put(sk);
if (signal_pending(current)) {
kfree_skb(skb);
return sock_intr_errno(*timeo);
}
return 1;
}
skb_set_owner_r(skb, sk);
return 0;
}
static int __netlink_sendskb(struct sock *sk, struct sk_buff *skb)
{
int len = skb->len;
skb_queue_tail(&sk->sk_receive_queue, skb);
sk->sk_data_ready(sk, len);
return len;
}
int netlink_sendskb(struct sock *sk, struct sk_buff *skb)
{
int len = __netlink_sendskb(sk, skb);
sock_put(sk);
return len;
}
void netlink_detachskb(struct sock *sk, struct sk_buff *skb)
{
kfree_skb(skb);
sock_put(sk);
}
static struct sk_buff *netlink_trim(struct sk_buff *skb, gfp_t allocation)
{
int delta;
skb_orphan(skb);
delta = skb->end - skb->tail;
if (delta * 2 < skb->truesize)
return skb;
if (skb_shared(skb)) {
struct sk_buff *nskb = skb_clone(skb, allocation);
if (!nskb)
return skb;
consume_skb(skb);
skb = nskb;
}
if (!pskb_expand_head(skb, 0, -delta, allocation))
skb->truesize -= delta;
return skb;
}
static void netlink_rcv_wake(struct sock *sk)
{
struct netlink_sock *nlk = nlk_sk(sk);
if (skb_queue_empty(&sk->sk_receive_queue))
clear_bit(0, &nlk->state);
if (!test_bit(0, &nlk->state))
wake_up_interruptible(&nlk->wait);
}
static int netlink_unicast_kernel(struct sock *sk, struct sk_buff *skb,
struct sock *ssk)
{
int ret;
struct netlink_sock *nlk = nlk_sk(sk);
ret = -ECONNREFUSED;
if (nlk->netlink_rcv != NULL) {
ret = skb->len;
skb_set_owner_r(skb, sk);
NETLINK_CB(skb).ssk = ssk;
nlk->netlink_rcv(skb);
consume_skb(skb);
} else {
kfree_skb(skb);
}
sock_put(sk);
return ret;
}
int netlink_unicast(struct sock *ssk, struct sk_buff *skb,
u32 portid, int nonblock)
{
struct sock *sk;
int err;
long timeo;
skb = netlink_trim(skb, gfp_any());
timeo = sock_sndtimeo(ssk, nonblock);
retry:
sk = netlink_getsockbyportid(ssk, portid);
if (IS_ERR(sk)) {
kfree_skb(skb);
return PTR_ERR(sk);
}
if (netlink_is_kernel(sk))
return netlink_unicast_kernel(sk, skb, ssk);
if (sk_filter(sk, skb)) {
err = skb->len;
kfree_skb(skb);
sock_put(sk);
return err;
}
err = netlink_attachskb(sk, skb, &timeo, ssk);
if (err == 1)
goto retry;
if (err)
return err;
return netlink_sendskb(sk, skb);
}
EXPORT_SYMBOL(netlink_unicast);
int netlink_has_listeners(struct sock *sk, unsigned int group)
{
int res = 0;
struct listeners *listeners;
BUG_ON(!netlink_is_kernel(sk));
rcu_read_lock();
listeners = rcu_dereference(nl_table[sk->sk_protocol].listeners);
if (listeners && group - 1 < nl_table[sk->sk_protocol].groups)
res = test_bit(group - 1, listeners->masks);