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![Eric W. Biederman](/assets/img/avatar_default.png)
It is possible by passing a netlink socket to a more privileged executable and then to fool that executable into writing to the socket data that happens to be valid netlink message to do something that privileged executable did not intend to do. To keep this from happening replace bare capable and ns_capable calls with netlink_capable, netlink_net_calls and netlink_ns_capable calls. Which act the same as the previous calls except they verify that the opener of the socket had the desired permissions as well. Reported-by: Andy Lutomirski <luto@amacapital.net> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: David S. Miller <davem@davemloft.net>
264 lines
6.3 KiB
C
264 lines
6.3 KiB
C
#include <linux/module.h>
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#include <linux/sock_diag.h>
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#include <linux/net.h>
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#include <linux/netdevice.h>
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#include <linux/packet_diag.h>
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#include <linux/percpu.h>
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#include <net/net_namespace.h>
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#include <net/sock.h>
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#include "internal.h"
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static int pdiag_put_info(const struct packet_sock *po, struct sk_buff *nlskb)
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{
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struct packet_diag_info pinfo;
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pinfo.pdi_index = po->ifindex;
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pinfo.pdi_version = po->tp_version;
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pinfo.pdi_reserve = po->tp_reserve;
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pinfo.pdi_copy_thresh = po->copy_thresh;
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pinfo.pdi_tstamp = po->tp_tstamp;
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pinfo.pdi_flags = 0;
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if (po->running)
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pinfo.pdi_flags |= PDI_RUNNING;
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if (po->auxdata)
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pinfo.pdi_flags |= PDI_AUXDATA;
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if (po->origdev)
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pinfo.pdi_flags |= PDI_ORIGDEV;
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if (po->has_vnet_hdr)
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pinfo.pdi_flags |= PDI_VNETHDR;
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if (po->tp_loss)
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pinfo.pdi_flags |= PDI_LOSS;
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return nla_put(nlskb, PACKET_DIAG_INFO, sizeof(pinfo), &pinfo);
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}
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static int pdiag_put_mclist(const struct packet_sock *po, struct sk_buff *nlskb)
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{
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struct nlattr *mca;
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struct packet_mclist *ml;
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mca = nla_nest_start(nlskb, PACKET_DIAG_MCLIST);
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if (!mca)
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return -EMSGSIZE;
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rtnl_lock();
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for (ml = po->mclist; ml; ml = ml->next) {
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struct packet_diag_mclist *dml;
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dml = nla_reserve_nohdr(nlskb, sizeof(*dml));
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if (!dml) {
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rtnl_unlock();
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nla_nest_cancel(nlskb, mca);
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return -EMSGSIZE;
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}
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dml->pdmc_index = ml->ifindex;
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dml->pdmc_type = ml->type;
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dml->pdmc_alen = ml->alen;
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dml->pdmc_count = ml->count;
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BUILD_BUG_ON(sizeof(dml->pdmc_addr) != sizeof(ml->addr));
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memcpy(dml->pdmc_addr, ml->addr, sizeof(ml->addr));
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}
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rtnl_unlock();
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nla_nest_end(nlskb, mca);
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return 0;
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}
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static int pdiag_put_ring(struct packet_ring_buffer *ring, int ver, int nl_type,
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struct sk_buff *nlskb)
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{
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struct packet_diag_ring pdr;
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if (!ring->pg_vec || ((ver > TPACKET_V2) &&
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(nl_type == PACKET_DIAG_TX_RING)))
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return 0;
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pdr.pdr_block_size = ring->pg_vec_pages << PAGE_SHIFT;
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pdr.pdr_block_nr = ring->pg_vec_len;
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pdr.pdr_frame_size = ring->frame_size;
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pdr.pdr_frame_nr = ring->frame_max + 1;
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if (ver > TPACKET_V2) {
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pdr.pdr_retire_tmo = ring->prb_bdqc.retire_blk_tov;
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pdr.pdr_sizeof_priv = ring->prb_bdqc.blk_sizeof_priv;
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pdr.pdr_features = ring->prb_bdqc.feature_req_word;
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} else {
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pdr.pdr_retire_tmo = 0;
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pdr.pdr_sizeof_priv = 0;
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pdr.pdr_features = 0;
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}
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return nla_put(nlskb, nl_type, sizeof(pdr), &pdr);
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}
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static int pdiag_put_rings_cfg(struct packet_sock *po, struct sk_buff *skb)
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{
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int ret;
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mutex_lock(&po->pg_vec_lock);
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ret = pdiag_put_ring(&po->rx_ring, po->tp_version,
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PACKET_DIAG_RX_RING, skb);
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if (!ret)
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ret = pdiag_put_ring(&po->tx_ring, po->tp_version,
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PACKET_DIAG_TX_RING, skb);
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mutex_unlock(&po->pg_vec_lock);
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return ret;
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}
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static int pdiag_put_fanout(struct packet_sock *po, struct sk_buff *nlskb)
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{
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int ret = 0;
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mutex_lock(&fanout_mutex);
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if (po->fanout) {
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u32 val;
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val = (u32)po->fanout->id | ((u32)po->fanout->type << 16);
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ret = nla_put_u32(nlskb, PACKET_DIAG_FANOUT, val);
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}
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mutex_unlock(&fanout_mutex);
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return ret;
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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 packet_diag_req *req,
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bool may_report_filterinfo,
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struct user_namespace *user_ns,
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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 packet_diag_msg *rp;
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struct packet_sock *po = pkt_sk(sk);
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nlh = nlmsg_put(skb, portid, seq, SOCK_DIAG_BY_FAMILY, sizeof(*rp), flags);
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if (!nlh)
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return -EMSGSIZE;
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rp = nlmsg_data(nlh);
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rp->pdiag_family = AF_PACKET;
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rp->pdiag_type = sk->sk_type;
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rp->pdiag_num = ntohs(po->num);
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rp->pdiag_ino = sk_ino;
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sock_diag_save_cookie(sk, rp->pdiag_cookie);
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if ((req->pdiag_show & PACKET_SHOW_INFO) &&
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pdiag_put_info(po, skb))
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goto out_nlmsg_trim;
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if ((req->pdiag_show & PACKET_SHOW_INFO) &&
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nla_put_u32(skb, PACKET_DIAG_UID,
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from_kuid_munged(user_ns, sock_i_uid(sk))))
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goto out_nlmsg_trim;
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if ((req->pdiag_show & PACKET_SHOW_MCLIST) &&
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pdiag_put_mclist(po, skb))
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goto out_nlmsg_trim;
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if ((req->pdiag_show & PACKET_SHOW_RING_CFG) &&
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pdiag_put_rings_cfg(po, skb))
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goto out_nlmsg_trim;
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if ((req->pdiag_show & PACKET_SHOW_FANOUT) &&
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pdiag_put_fanout(po, skb))
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goto out_nlmsg_trim;
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if ((req->pdiag_show & PACKET_SHOW_MEMINFO) &&
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sock_diag_put_meminfo(sk, skb, PACKET_DIAG_MEMINFO))
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goto out_nlmsg_trim;
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if ((req->pdiag_show & PACKET_SHOW_FILTER) &&
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sock_diag_put_filterinfo(may_report_filterinfo, sk, skb,
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PACKET_DIAG_FILTER))
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goto out_nlmsg_trim;
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return nlmsg_end(skb, nlh);
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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 packet_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
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{
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int num = 0, s_num = cb->args[0];
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struct packet_diag_req *req;
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struct net *net;
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struct sock *sk;
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bool may_report_filterinfo;
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net = sock_net(skb->sk);
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req = nlmsg_data(cb->nlh);
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may_report_filterinfo = netlink_net_capable(cb->skb, CAP_NET_ADMIN);
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mutex_lock(&net->packet.sklist_lock);
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sk_for_each(sk, &net->packet.sklist) {
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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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goto next;
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if (sk_diag_fill(sk, skb, req,
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may_report_filterinfo,
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sk_user_ns(NETLINK_CB(cb->skb).sk),
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NETLINK_CB(cb->skb).portid,
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cb->nlh->nlmsg_seq, NLM_F_MULTI,
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sock_i_ino(sk)) < 0)
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goto done;
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next:
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num++;
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}
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done:
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mutex_unlock(&net->packet.sklist_lock);
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cb->args[0] = num;
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return skb->len;
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}
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static int packet_diag_handler_dump(struct sk_buff *skb, struct nlmsghdr *h)
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{
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int hdrlen = sizeof(struct packet_diag_req);
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struct net *net = sock_net(skb->sk);
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struct packet_diag_req *req;
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if (nlmsg_len(h) < hdrlen)
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return -EINVAL;
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req = nlmsg_data(h);
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/* Make it possible to support protocol filtering later */
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if (req->sdiag_protocol)
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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 = packet_diag_dump,
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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 packet_diag_handler = {
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.family = AF_PACKET,
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.dump = packet_diag_handler_dump,
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};
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static int __init packet_diag_init(void)
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{
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return sock_diag_register(&packet_diag_handler);
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}
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static void __exit packet_diag_exit(void)
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{
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sock_diag_unregister(&packet_diag_handler);
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}
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module_init(packet_diag_init);
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module_exit(packet_diag_exit);
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG, 17 /* AF_PACKET */);
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