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af_netlink.c
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af_netlink.c
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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* NETLINK Kernel-user communication protocol.
*
* Authors: Alan Cox <alan@lxorguk.ukuu.org.uk>
* Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
* Patrick McHardy <kaber@trash.net>
*
* 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 <acme@conectiva.com.br>
* use nlk_sk, as sk->protinfo is on a diet 8)
* Fri Jul 22 19:51:12 MEST 2005 Harald Welte <laforge@gnumonks.org>
* - 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 <linux/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 <linux/vmalloc.h>
#include <linux/if_arp.h>
#include <linux/rhashtable.h>
#include <asm/cacheflush.h>
#include <linux/hash.h>
#include <linux/genetlink.h>
#include <linux/net_namespace.h>
#include <linux/nospec.h>
#include <net/net_namespace.h>
#include <net/netns/generic.h>
#include <net/sock.h>
#include <net/scm.h>
#include <net/netlink.h>
#include "af_netlink.h"
struct listeners {
struct rcu_head rcu;
unsigned long masks[];
};
/* state bits */
#define NETLINK_S_CONGESTED 0x0
static inline int netlink_is_kernel(struct sock *sk)
{
return nlk_sk(sk)->flags & NETLINK_F_KERNEL_SOCKET;
}
struct netlink_table *nl_table __read_mostly;
EXPORT_SYMBOL_GPL(nl_table);
static DECLARE_WAIT_QUEUE_HEAD(nl_table_wait);
static struct lock_class_key nlk_cb_mutex_keys[MAX_LINKS];
static const char *const nlk_cb_mutex_key_strings[MAX_LINKS + 1] = {
"nlk_cb_mutex-ROUTE",
"nlk_cb_mutex-1",
"nlk_cb_mutex-USERSOCK",
"nlk_cb_mutex-FIREWALL",
"nlk_cb_mutex-SOCK_DIAG",
"nlk_cb_mutex-NFLOG",
"nlk_cb_mutex-XFRM",
"nlk_cb_mutex-SELINUX",
"nlk_cb_mutex-ISCSI",
"nlk_cb_mutex-AUDIT",
"nlk_cb_mutex-FIB_LOOKUP",
"nlk_cb_mutex-CONNECTOR",
"nlk_cb_mutex-NETFILTER",
"nlk_cb_mutex-IP6_FW",
"nlk_cb_mutex-DNRTMSG",
"nlk_cb_mutex-KOBJECT_UEVENT",
"nlk_cb_mutex-GENERIC",
"nlk_cb_mutex-17",
"nlk_cb_mutex-SCSITRANSPORT",
"nlk_cb_mutex-ECRYPTFS",
"nlk_cb_mutex-RDMA",
"nlk_cb_mutex-CRYPTO",
"nlk_cb_mutex-SMC",
"nlk_cb_mutex-23",
"nlk_cb_mutex-24",
"nlk_cb_mutex-25",
"nlk_cb_mutex-26",
"nlk_cb_mutex-27",
"nlk_cb_mutex-28",
"nlk_cb_mutex-29",
"nlk_cb_mutex-30",
"nlk_cb_mutex-31",
"nlk_cb_mutex-MAX_LINKS"
};
static int netlink_dump(struct sock *sk);
/* nl_table locking explained:
* Lookup and traversal are protected with an RCU read-side lock. Insertion
* and removal are protected with per bucket lock while using RCU list
* modification primitives and may run in parallel to RCU protected lookups.
* Destruction of the Netlink socket may only occur *after* nl_table_lock has
* been acquired * either during or after the socket has been removed from
* the list and after an RCU grace period.
*/
DEFINE_RWLOCK(nl_table_lock);
EXPORT_SYMBOL_GPL(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 BLOCKING_NOTIFIER_HEAD(netlink_chain);
static const struct rhashtable_params netlink_rhashtable_params;
static inline u32 netlink_group_mask(u32 group)
{
return group ? 1 << (group - 1) : 0;
}
static struct sk_buff *netlink_to_full_skb(const struct sk_buff *skb,
gfp_t gfp_mask)
{
unsigned int len = skb_end_offset(skb);
struct sk_buff *new;
new = alloc_skb(len, gfp_mask);
if (new == NULL)
return NULL;
NETLINK_CB(new).portid = NETLINK_CB(skb).portid;
NETLINK_CB(new).dst_group = NETLINK_CB(skb).dst_group;
NETLINK_CB(new).creds = NETLINK_CB(skb).creds;
skb_put_data(new, skb->data, len);
return new;
}
static unsigned int netlink_tap_net_id;
struct netlink_tap_net {
struct list_head netlink_tap_all;
struct mutex netlink_tap_lock;
};
int netlink_add_tap(struct netlink_tap *nt)
{
struct net *net = dev_net(nt->dev);
struct netlink_tap_net *nn = net_generic(net, netlink_tap_net_id);
if (unlikely(nt->dev->type != ARPHRD_NETLINK))
return -EINVAL;
mutex_lock(&nn->netlink_tap_lock);
list_add_rcu(&nt->list, &nn->netlink_tap_all);
mutex_unlock(&nn->netlink_tap_lock);
__module_get(nt->module);
return 0;
}
EXPORT_SYMBOL_GPL(netlink_add_tap);
static int __netlink_remove_tap(struct netlink_tap *nt)
{
struct net *net = dev_net(nt->dev);
struct netlink_tap_net *nn = net_generic(net, netlink_tap_net_id);
bool found = false;
struct netlink_tap *tmp;
mutex_lock(&nn->netlink_tap_lock);
list_for_each_entry(tmp, &nn->netlink_tap_all, list) {
if (nt == tmp) {
list_del_rcu(&nt->list);
found = true;
goto out;
}
}
pr_warn("__netlink_remove_tap: %p not found\n", nt);
out:
mutex_unlock(&nn->netlink_tap_lock);
if (found)
module_put(nt->module);
return found ? 0 : -ENODEV;
}
int netlink_remove_tap(struct netlink_tap *nt)
{
int ret;
ret = __netlink_remove_tap(nt);
synchronize_net();
return ret;
}
EXPORT_SYMBOL_GPL(netlink_remove_tap);
static __net_init int netlink_tap_init_net(struct net *net)
{
struct netlink_tap_net *nn = net_generic(net, netlink_tap_net_id);
INIT_LIST_HEAD(&nn->netlink_tap_all);
mutex_init(&nn->netlink_tap_lock);
return 0;
}
static struct pernet_operations netlink_tap_net_ops = {
.init = netlink_tap_init_net,
.id = &netlink_tap_net_id,
.size = sizeof(struct netlink_tap_net),
};
static bool netlink_filter_tap(const struct sk_buff *skb)
{
struct sock *sk = skb->sk;
/* We take the more conservative approach and
* whitelist socket protocols that may pass.
*/
switch (sk->sk_protocol) {
case NETLINK_ROUTE:
case NETLINK_USERSOCK:
case NETLINK_SOCK_DIAG:
case NETLINK_NFLOG:
case NETLINK_XFRM:
case NETLINK_FIB_LOOKUP:
case NETLINK_NETFILTER:
case NETLINK_GENERIC:
return true;
}
return false;
}
static int __netlink_deliver_tap_skb(struct sk_buff *skb,
struct net_device *dev)
{
struct sk_buff *nskb;
struct sock *sk = skb->sk;
int ret = -ENOMEM;
if (!net_eq(dev_net(dev), sock_net(sk)))
return 0;
dev_hold(dev);
if (is_vmalloc_addr(skb->head))
nskb = netlink_to_full_skb(skb, GFP_ATOMIC);
else
nskb = skb_clone(skb, GFP_ATOMIC);
if (nskb) {
nskb->dev = dev;
nskb->protocol = htons((u16) sk->sk_protocol);
nskb->pkt_type = netlink_is_kernel(sk) ?
PACKET_KERNEL : PACKET_USER;
skb_reset_network_header(nskb);
ret = dev_queue_xmit(nskb);
if (unlikely(ret > 0))
ret = net_xmit_errno(ret);
}
dev_put(dev);
return ret;
}
static void __netlink_deliver_tap(struct sk_buff *skb, struct netlink_tap_net *nn)
{
int ret;
struct netlink_tap *tmp;
if (!netlink_filter_tap(skb))
return;
list_for_each_entry_rcu(tmp, &nn->netlink_tap_all, list) {
ret = __netlink_deliver_tap_skb(skb, tmp->dev);
if (unlikely(ret))
break;
}
}
static void netlink_deliver_tap(struct net *net, struct sk_buff *skb)
{
struct netlink_tap_net *nn = net_generic(net, netlink_tap_net_id);
rcu_read_lock();
if (unlikely(!list_empty(&nn->netlink_tap_all)))
__netlink_deliver_tap(skb, nn);
rcu_read_unlock();
}
static void netlink_deliver_tap_kernel(struct sock *dst, struct sock *src,
struct sk_buff *skb)
{
if (!(netlink_is_kernel(dst) && netlink_is_kernel(src)))
netlink_deliver_tap(sock_net(dst), skb);
}
static void netlink_overrun(struct sock *sk)
{
struct netlink_sock *nlk = nlk_sk(sk);
if (!(nlk->flags & NETLINK_F_RECV_NO_ENOBUFS)) {
if (!test_and_set_bit(NETLINK_S_CONGESTED,
&nlk_sk(sk)->state)) {
sk->sk_err = ENOBUFS;
sk->sk_error_report(sk);
}
}
atomic_inc(&sk->sk_drops);
}
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(NETLINK_S_CONGESTED, &nlk->state);
if (!test_bit(NETLINK_S_CONGESTED, &nlk->state))
wake_up_interruptible(&nlk->wait);
}
static void netlink_skb_destructor(struct sk_buff *skb)
{
if (is_vmalloc_addr(skb->head)) {
if (!skb->cloned ||
!atomic_dec_return(&(skb_shinfo(skb)->dataref)))
vfree(skb->head);
skb->head = NULL;
}
if (skb->sk != NULL)
sock_rfree(skb);
}
static void netlink_skb_set_owner_r(struct sk_buff *skb, struct sock *sk)
{
WARN_ON(skb->sk != NULL);
skb->sk = sk;
skb->destructor = netlink_skb_destructor;
atomic_add(skb->truesize, &sk->sk_rmem_alloc);
sk_mem_charge(sk, skb->truesize);
}
static void netlink_sock_destruct(struct sock *sk)
{
struct netlink_sock *nlk = nlk_sk(sk);
if (nlk->cb_running) {
if (nlk->cb.done)
nlk->cb.done(&nlk->cb);
module_put(nlk->cb.module);
kfree_skb(nlk->cb.skb);
}
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(refcount_read(&sk->sk_wmem_alloc));
WARN_ON(nlk_sk(sk)->groups);
}
static void netlink_sock_destruct_work(struct work_struct *work)
{
struct netlink_sock *nlk = container_of(work, struct netlink_sock,
work);
sk_free(&nlk->sk);
}
/* 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);
}
struct netlink_compare_arg
{
possible_net_t pnet;
u32 portid;
};
/* Doing sizeof directly may yield 4 extra bytes on 64-bit. */
#define netlink_compare_arg_len \
(offsetof(struct netlink_compare_arg, portid) + sizeof(u32))
static inline int netlink_compare(struct rhashtable_compare_arg *arg,
const void *ptr)
{
const struct netlink_compare_arg *x = arg->key;
const struct netlink_sock *nlk = ptr;
return nlk->portid != x->portid ||
!net_eq(sock_net(&nlk->sk), read_pnet(&x->pnet));
}
static void netlink_compare_arg_init(struct netlink_compare_arg *arg,
struct net *net, u32 portid)
{
memset(arg, 0, sizeof(*arg));
write_pnet(&arg->pnet, net);
arg->portid = portid;
}
static struct sock *__netlink_lookup(struct netlink_table *table, u32 portid,
struct net *net)
{
struct netlink_compare_arg arg;
netlink_compare_arg_init(&arg, net, portid);
return rhashtable_lookup_fast(&table->hash, &arg,
netlink_rhashtable_params);
}
static int __netlink_insert(struct netlink_table *table, struct sock *sk)
{
struct netlink_compare_arg arg;
netlink_compare_arg_init(&arg, sock_net(sk), nlk_sk(sk)->portid);
return rhashtable_lookup_insert_key(&table->hash, &arg,
&nlk_sk(sk)->node,
netlink_rhashtable_params);
}
static struct sock *netlink_lookup(struct net *net, int protocol, u32 portid)
{
struct netlink_table *table = &nl_table[protocol];
struct sock *sk;
rcu_read_lock();
sk = __netlink_lookup(table, portid, net);
if (sk)
sock_hold(sk);
rcu_read_unlock();
return sk;
}
static const struct proto_ops netlink_ops;
static void
netlink_update_listeners(struct sock *sk)
{
struct netlink_table *tbl = &nl_table[sk->sk_protocol];
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, &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, u32 portid)
{
struct netlink_table *table = &nl_table[sk->sk_protocol];
int err;
lock_sock(sk);
err = nlk_sk(sk)->portid == portid ? 0 : -EBUSY;
if (nlk_sk(sk)->bound)
goto err;
nlk_sk(sk)->portid = portid;
sock_hold(sk);
err = __netlink_insert(table, sk);
if (err) {
/* In case the hashtable backend returns with -EBUSY
* from here, it must not escape to the caller.
*/
if (unlikely(err == -EBUSY))
err = -EOVERFLOW;
if (err == -EEXIST)
err = -EADDRINUSE;
sock_put(sk);
goto err;
}
/* We need to ensure that the socket is hashed and visible. */
smp_wmb();
nlk_sk(sk)->bound = portid;
err:
release_sock(sk);
return err;
}
static void netlink_remove(struct sock *sk)
{
struct netlink_table *table;
table = &nl_table[sk->sk_protocol];
if (!rhashtable_remove_fast(&table->hash, &nlk_sk(sk)->node,
netlink_rhashtable_params)) {
WARN_ON(refcount_read(&sk->sk_refcnt) == 1);
__sock_put(sk);
}
netlink_table_grab();
if (nlk_sk(sk)->subscriptions) {
__sk_del_bind_node(sk);
netlink_update_listeners(sk);
}
if (sk->sk_protocol == NETLINK_GENERIC)
atomic_inc(&genl_sk_destructing_cnt);
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,
int kern)
{
struct sock *sk;
struct netlink_sock *nlk;
sock->ops = &netlink_ops;
sk = sk_alloc(net, PF_NETLINK, GFP_KERNEL, &netlink_proto, kern);
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);
lockdep_set_class_and_name(nlk->cb_mutex,
nlk_cb_mutex_keys + protocol,
nlk_cb_mutex_key_strings[protocol]);
}
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;
int (*bind)(struct net *net, int group);
void (*unbind)(struct net *net, 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;
protocol = array_index_nospec(protocol, MAX_LINKS);
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;
unbind = nl_table[protocol].unbind;
netlink_unlock_table();
if (err < 0)
goto out;
err = __netlink_create(net, sock, cb_mutex, protocol, kern);
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;
nlk->netlink_unbind = unbind;
out:
return err;
out_module:
module_put(module);
goto out;
}
static void deferred_put_nlk_sk(struct rcu_head *head)
{
struct netlink_sock *nlk = container_of(head, struct netlink_sock, rcu);
struct sock *sk = &nlk->sk;
kfree(nlk->groups);
nlk->groups = NULL;
if (!refcount_dec_and_test(&sk->sk_refcnt))
return;
if (nlk->cb_running && nlk->cb.done) {
INIT_WORK(&nlk->work, netlink_sock_destruct_work);
schedule_work(&nlk->work);
return;
}
sk_free(sk);
}
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.
*/
/* must not acquire netlink_table_lock in any way again before unbind
* and notifying genetlink is done as otherwise it might deadlock
*/
if (nlk->netlink_unbind) {
int i;
for (i = 0; i < nlk->ngroups; i++)
if (test_bit(i, nlk->groups))
nlk->netlink_unbind(sock_net(sk), i + 1);
}
if (sk->sk_protocol == NETLINK_GENERIC &&
atomic_dec_return(&genl_sk_destructing_cnt) == 0)
wake_up(&genl_sk_destructing_waitq);
sock->sk = NULL;
wake_up_interruptible_all(&nlk->wait);
skb_queue_purge(&sk->sk_write_queue);
if (nlk->portid && nlk->bound) {
struct netlink_notify n = {
.net = sock_net(sk),
.protocol = sk->sk_protocol,
.portid = nlk->portid,
};
blocking_notifier_call_chain(&netlink_chain,
NETLINK_URELEASE, &n);
}
module_put(nlk->module);
if (netlink_is_kernel(sk)) {
netlink_table_grab();
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].unbind = NULL;
nl_table[sk->sk_protocol].flags = 0;
nl_table[sk->sk_protocol].registered = 0;
}
netlink_table_ungrab();
}
local_bh_disable();
sock_prot_inuse_add(sock_net(sk), &netlink_proto, -1);
local_bh_enable();
call_rcu(&nlk->rcu, deferred_put_nlk_sk);
return 0;
}
static int netlink_autobind(struct socket *sock)
{
struct sock *sk = sock->sk;
struct net *net = sock_net(sk);
struct netlink_table *table = &nl_table[sk->sk_protocol];
s32 portid = task_tgid_vnr(current);
int err;
s32 rover = -4096;
bool ok;
retry:
cond_resched();
rcu_read_lock();
ok = !__netlink_lookup(table, portid, net);
rcu_read_unlock();
if (!ok) {
/* Bind collision, search negative portid values. */
if (rover == -4096)
/* rover will be in range [S32_MIN, -4097] */
rover = S32_MIN + prandom_u32_max(-4096 - S32_MIN);
else if (rover >= -4096)
rover = -4097;
portid = rover--;
goto retry;
}
err = netlink_insert(sk, portid);
if (err == -EADDRINUSE)
goto retry;
/* If 2 threads race to autobind, that is fine. */
if (err == -EBUSY)
err = 0;
return err;
}
/**
* __netlink_ns_capable - General netlink message capability test
* @nsp: NETLINK_CB of the socket buffer holding a netlink command from userspace.
* @user_ns: The user namespace of the capability to use
* @cap: The capability to use
*
* Test to see if the opener of the socket we received the message
* from had when the netlink socket was created and the sender of the
* message has has the capability @cap in the user namespace @user_ns.
*/
bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
struct user_namespace *user_ns, int cap)
{
return ((nsp->flags & NETLINK_SKB_DST) ||
file_ns_capable(nsp->sk->sk_socket->file, user_ns, cap)) &&
ns_capable(user_ns, cap);
}
EXPORT_SYMBOL(__netlink_ns_capable);
/**
* netlink_ns_capable - General netlink message capability test
* @skb: socket buffer holding a netlink command from userspace
* @user_ns: The user namespace of the capability to use
* @cap: The capability to use
*
* Test to see if the opener of the socket we received the message
* from had when the netlink socket was created and the sender of the
* message has has the capability @cap in the user namespace @user_ns.
*/
bool netlink_ns_capable(const struct sk_buff *skb,
struct user_namespace *user_ns, int cap)
{
return __netlink_ns_capable(&NETLINK_CB(skb), user_ns, cap);
}
EXPORT_SYMBOL(netlink_ns_capable);
/**
* netlink_capable - Netlink global message capability test
* @skb: socket buffer holding a netlink command from userspace
* @cap: The capability to use
*
* Test to see if the opener of the socket we received the message
* from had when the netlink socket was created and the sender of the
* message has has the capability @cap in all user namespaces.
*/
bool netlink_capable(const struct sk_buff *skb, int cap)
{
return netlink_ns_capable(skb, &init_user_ns, cap);
}
EXPORT_SYMBOL(netlink_capable);
/**
* netlink_net_capable - Netlink network namespace message capability test
* @skb: socket buffer holding a netlink command from userspace
* @cap: The capability to use
*
* Test to see if the opener of the socket we received the message
* from had when the netlink socket was created and the sender of the
* message has has the capability @cap over the network namespace of
* the socket we received the message from.
*/
bool netlink_net_capable(const struct sk_buff *skb, int cap)
{
return netlink_ns_capable(skb, sock_net(skb->sk)->user_ns, cap);
}
EXPORT_SYMBOL(netlink_net_capable);
static inline int netlink_allowed(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 void netlink_undo_bind(int group, long unsigned int groups,
struct sock *sk)
{
struct netlink_sock *nlk = nlk_sk(sk);
int undo;
if (!nlk->netlink_unbind)
return;
for (undo = 0; undo < group; undo++)
if (test_bit(undo, &groups))
nlk->netlink_unbind(sock_net(sk), undo + 1);
}
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 = 0;
unsigned long groups;
bool bound;
if (addr_len < sizeof(struct sockaddr_nl))
return -EINVAL;
if (nladdr->nl_family != AF_NETLINK)
return -EINVAL;
groups = nladdr->nl_groups;
/* Only superuser is allowed to listen multicasts */
if (groups) {
if (!netlink_allowed(sock, NL_CFG_F_NONROOT_RECV))
return -EPERM;
err = netlink_realloc_groups(sk);
if (err)
return err;
}