![Eric Dumazet](/assets/img/avatar_default.png)
A recent commit removed locking from netlink_diag_dump() but forgot
one error case.
=====================================
[ BUG: bad unlock balance detected! ]
4.9.0-rc3+ #336 Not tainted
-------------------------------------
syz-executor/4018 is trying to release lock ([ 36.220068] nl_table_lock
) at:
[<ffffffff82dc8683>] netlink_diag_dump+0x1a3/0x250 net/netlink/diag.c:182
but there are no more locks to release!
other info that might help us debug this:
3 locks held by syz-executor/4018:
#0: [ 36.220068] (
sock_diag_mutex[ 36.220068] ){+.+.+.}
, at: [ 36.220068] [<ffffffff82c3873b>] sock_diag_rcv+0x1b/0x40
#1: [ 36.220068] (
sock_diag_table_mutex[ 36.220068] ){+.+.+.}
, at: [ 36.220068] [<ffffffff82c38e00>] sock_diag_rcv_msg+0x140/0x3a0
#2: [ 36.220068] (
nlk->cb_mutex[ 36.220068] ){+.+.+.}
, at: [ 36.220068] [<ffffffff82db6600>] netlink_dump+0x50/0xac0
stack backtrace:
CPU: 1 PID: 4018 Comm: syz-executor Not tainted 4.9.0-rc3+ #336
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
ffff8800645df688 ffffffff81b46934 ffffffff84eb3e78 ffff88006ad85800
ffffffff82dc8683 ffffffff84eb3e78 ffff8800645df6b8 ffffffff812043ca
dffffc0000000000 ffff88006ad85ff8 ffff88006ad85fd0 00000000ffffffff
Call Trace:
[< inline >] __dump_stack lib/dump_stack.c:15
[<ffffffff81b46934>] dump_stack+0xb3/0x10f lib/dump_stack.c:51
[<ffffffff812043ca>] print_unlock_imbalance_bug+0x17a/0x1a0
kernel/locking/lockdep.c:3388
[< inline >] __lock_release kernel/locking/lockdep.c:3512
[<ffffffff8120cfd8>] lock_release+0x8e8/0xc60 kernel/locking/lockdep.c:3765
[< inline >] __raw_read_unlock ./include/linux/rwlock_api_smp.h:225
[<ffffffff83fc001a>] _raw_read_unlock+0x1a/0x30 kernel/locking/spinlock.c:255
[<ffffffff82dc8683>] netlink_diag_dump+0x1a3/0x250 net/netlink/diag.c:182
[<ffffffff82db6947>] netlink_dump+0x397/0xac0 net/netlink/af_netlink.c:2110
Fixes: ad20207432
("netlink: Use rhashtable walk interface in diag dump")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Tested-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
239 lines
4.7 KiB
C
239 lines
4.7 KiB
C
#include <linux/module.h>
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#include <net/sock.h>
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#include <linux/netlink.h>
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#include <linux/sock_diag.h>
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#include <linux/netlink_diag.h>
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#include <linux/rhashtable.h>
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#include "af_netlink.h"
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static int sk_diag_dump_groups(struct sock *sk, struct sk_buff *nlskb)
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{
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struct netlink_sock *nlk = nlk_sk(sk);
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if (nlk->groups == NULL)
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return 0;
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return nla_put(nlskb, NETLINK_DIAG_GROUPS, NLGRPSZ(nlk->ngroups),
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nlk->groups);
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}
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static int sk_diag_fill(struct sock *sk, struct sk_buff *skb,
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struct netlink_diag_req *req,
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u32 portid, u32 seq, u32 flags, int sk_ino)
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{
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struct nlmsghdr *nlh;
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struct netlink_diag_msg *rep;
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struct netlink_sock *nlk = nlk_sk(sk);
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nlh = nlmsg_put(skb, portid, seq, SOCK_DIAG_BY_FAMILY, sizeof(*rep),
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flags);
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if (!nlh)
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return -EMSGSIZE;
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rep = nlmsg_data(nlh);
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rep->ndiag_family = AF_NETLINK;
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rep->ndiag_type = sk->sk_type;
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rep->ndiag_protocol = sk->sk_protocol;
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rep->ndiag_state = sk->sk_state;
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rep->ndiag_ino = sk_ino;
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rep->ndiag_portid = nlk->portid;
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rep->ndiag_dst_portid = nlk->dst_portid;
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rep->ndiag_dst_group = nlk->dst_group;
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sock_diag_save_cookie(sk, rep->ndiag_cookie);
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if ((req->ndiag_show & NDIAG_SHOW_GROUPS) &&
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sk_diag_dump_groups(sk, skb))
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goto out_nlmsg_trim;
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if ((req->ndiag_show & NDIAG_SHOW_MEMINFO) &&
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sock_diag_put_meminfo(sk, skb, NETLINK_DIAG_MEMINFO))
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goto out_nlmsg_trim;
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nlmsg_end(skb, nlh);
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return 0;
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out_nlmsg_trim:
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nlmsg_cancel(skb, nlh);
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return -EMSGSIZE;
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}
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static int __netlink_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
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int protocol, int s_num)
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{
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struct rhashtable_iter *hti = (void *)cb->args[2];
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struct netlink_table *tbl = &nl_table[protocol];
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struct net *net = sock_net(skb->sk);
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struct netlink_diag_req *req;
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struct netlink_sock *nlsk;
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struct sock *sk;
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int num = 2;
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int ret = 0;
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req = nlmsg_data(cb->nlh);
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if (s_num > 1)
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goto mc_list;
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num--;
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if (!hti) {
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hti = kmalloc(sizeof(*hti), GFP_KERNEL);
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if (!hti)
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return -ENOMEM;
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cb->args[2] = (long)hti;
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}
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if (!s_num)
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rhashtable_walk_enter(&tbl->hash, hti);
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ret = rhashtable_walk_start(hti);
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if (ret == -EAGAIN)
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ret = 0;
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if (ret)
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goto stop;
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while ((nlsk = rhashtable_walk_next(hti))) {
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if (IS_ERR(nlsk)) {
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ret = PTR_ERR(nlsk);
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if (ret == -EAGAIN) {
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ret = 0;
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continue;
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}
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break;
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}
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sk = (struct sock *)nlsk;
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if (!net_eq(sock_net(sk), net))
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continue;
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if (sk_diag_fill(sk, skb, req,
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NETLINK_CB(cb->skb).portid,
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cb->nlh->nlmsg_seq,
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NLM_F_MULTI,
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sock_i_ino(sk)) < 0) {
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ret = 1;
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break;
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}
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}
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stop:
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rhashtable_walk_stop(hti);
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if (ret)
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goto done;
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rhashtable_walk_exit(hti);
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num++;
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mc_list:
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read_lock(&nl_table_lock);
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sk_for_each_bound(sk, &tbl->mc_list) {
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if (sk_hashed(sk))
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continue;
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if (!net_eq(sock_net(sk), net))
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continue;
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if (num < s_num) {
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num++;
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continue;
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}
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if (sk_diag_fill(sk, skb, req,
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NETLINK_CB(cb->skb).portid,
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cb->nlh->nlmsg_seq,
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NLM_F_MULTI,
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sock_i_ino(sk)) < 0) {
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ret = 1;
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break;
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}
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num++;
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}
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read_unlock(&nl_table_lock);
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done:
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cb->args[0] = num;
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return ret;
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}
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static int netlink_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
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{
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struct netlink_diag_req *req;
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int s_num = cb->args[0];
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int err = 0;
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req = nlmsg_data(cb->nlh);
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if (req->sdiag_protocol == NDIAG_PROTO_ALL) {
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int i;
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for (i = cb->args[1]; i < MAX_LINKS; i++) {
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err = __netlink_diag_dump(skb, cb, i, s_num);
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if (err)
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break;
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s_num = 0;
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}
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cb->args[1] = i;
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} else {
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if (req->sdiag_protocol >= MAX_LINKS)
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return -ENOENT;
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err = __netlink_diag_dump(skb, cb, req->sdiag_protocol, s_num);
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}
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return err < 0 ? err : skb->len;
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}
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static int netlink_diag_dump_done(struct netlink_callback *cb)
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{
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struct rhashtable_iter *hti = (void *)cb->args[2];
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if (cb->args[0] == 1)
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rhashtable_walk_exit(hti);
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kfree(hti);
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return 0;
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}
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static int netlink_diag_handler_dump(struct sk_buff *skb, struct nlmsghdr *h)
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{
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int hdrlen = sizeof(struct netlink_diag_req);
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struct net *net = sock_net(skb->sk);
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if (nlmsg_len(h) < hdrlen)
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return -EINVAL;
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if (h->nlmsg_flags & NLM_F_DUMP) {
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struct netlink_dump_control c = {
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.dump = netlink_diag_dump,
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.done = netlink_diag_dump_done,
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};
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return netlink_dump_start(net->diag_nlsk, skb, h, &c);
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} else
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return -EOPNOTSUPP;
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}
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static const struct sock_diag_handler netlink_diag_handler = {
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.family = AF_NETLINK,
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.dump = netlink_diag_handler_dump,
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};
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static int __init netlink_diag_init(void)
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{
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return sock_diag_register(&netlink_diag_handler);
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}
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static void __exit netlink_diag_exit(void)
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{
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sock_diag_unregister(&netlink_diag_handler);
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}
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module_init(netlink_diag_init);
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module_exit(netlink_diag_exit);
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG, 16 /* AF_NETLINK */);
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