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7b3ba18703
LLC reads the mac header with eth_hdr without verifying that the skb
has an Ethernet header.
Syzbot was able to enter llc_rcv on a tun device. Tun can insert
packets without mac len and with user configurable skb->protocol
(passing a tun_pi header when not configuring IFF_NO_PI).
BUG: KMSAN: uninit-value in llc_station_ac_send_test_r net/llc/llc_station.c:81 [inline]
BUG: KMSAN: uninit-value in llc_station_rcv+0x6fb/0x1290 net/llc/llc_station.c:111
llc_station_ac_send_test_r net/llc/llc_station.c:81 [inline]
llc_station_rcv+0x6fb/0x1290 net/llc/llc_station.c:111
llc_rcv+0xc5d/0x14a0 net/llc/llc_input.c:218
__netif_receive_skb_one_core net/core/dev.c:5523 [inline]
__netif_receive_skb+0x1a6/0x5a0 net/core/dev.c:5637
netif_receive_skb_internal net/core/dev.c:5723 [inline]
netif_receive_skb+0x58/0x660 net/core/dev.c:5782
tun_rx_batched+0x3ee/0x980 drivers/net/tun.c:1555
tun_get_user+0x54c5/0x69c0 drivers/net/tun.c:2002
Add a mac_len test before all three eth_hdr(skb) calls under net/llc.
There are further uses in include/net/llc_pdu.h. All these are
protected by a test skb->protocol == ETH_P_802_2. Which does not
protect against this tun scenario.
But the mac_len test added in this patch in llc_fixup_skb will
indirectly protect those too. That is called from llc_rcv before any
other LLC code.
It is tempting to just add a blanket mac_len check in llc_rcv, but
not sure whether that could break valid LLC paths that do not assume
an Ethernet header. 802.2 LLC may be used on top of non-802.3
protocols in principle. The below referenced commit shows that used
to, on top of Token Ring.
At least one of the three eth_hdr uses goes back to before the start
of git history. But the one that syzbot exercises is introduced in
this commit. That commit is old enough (2008), that effectively all
stable kernels should receive this.
Fixes: f83f1768f8 ("[LLC]: skb allocation size for responses")
Reported-by: syzbot+a8c7be6dee0de1b669cc@syzkaller.appspotmail.com
Signed-off-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20231025234251.3796495-1-willemdebruijn.kernel@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
217 lines
6 KiB
C
217 lines
6 KiB
C
/*
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* llc_s_ac.c - actions performed during sap state transition.
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*
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* Description :
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* Functions in this module are implementation of sap component actions.
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* Details of actions can be found in IEEE-802.2 standard document.
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* All functions have one sap and one event as input argument. All of
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* them return 0 On success and 1 otherwise.
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*
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* Copyright (c) 1997 by Procom Technology, Inc.
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* 2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
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*
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* This program can be redistributed or modified under the terms of the
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* GNU General Public License as published by the Free Software Foundation.
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* This program is distributed without any warranty or implied warranty
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* of merchantability or fitness for a particular purpose.
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*
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* See the GNU General Public License for more details.
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*/
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#include <linux/netdevice.h>
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#include <net/llc.h>
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#include <net/llc_pdu.h>
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#include <net/llc_s_ac.h>
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#include <net/llc_s_ev.h>
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#include <net/llc_sap.h>
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/**
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* llc_sap_action_unitdata_ind - forward UI PDU to network layer
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* @sap: SAP
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* @skb: the event to forward
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*
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* Received a UI PDU from MAC layer; forward to network layer as a
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* UNITDATA INDICATION; verify our event is the kind we expect
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*/
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int llc_sap_action_unitdata_ind(struct llc_sap *sap, struct sk_buff *skb)
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{
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llc_sap_rtn_pdu(sap, skb);
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return 0;
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}
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/**
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* llc_sap_action_send_ui - sends UI PDU resp to UNITDATA REQ to MAC layer
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* @sap: SAP
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* @skb: the event to send
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*
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* Sends a UI PDU to the MAC layer in response to a UNITDATA REQUEST
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* primitive from the network layer. Verifies event is a primitive type of
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* event. Verify the primitive is a UNITDATA REQUEST.
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*/
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int llc_sap_action_send_ui(struct llc_sap *sap, struct sk_buff *skb)
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{
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struct llc_sap_state_ev *ev = llc_sap_ev(skb);
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int rc;
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llc_pdu_header_init(skb, LLC_PDU_TYPE_U, ev->saddr.lsap,
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ev->daddr.lsap, LLC_PDU_CMD);
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llc_pdu_init_as_ui_cmd(skb);
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rc = llc_mac_hdr_init(skb, ev->saddr.mac, ev->daddr.mac);
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if (likely(!rc)) {
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skb_get(skb);
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rc = dev_queue_xmit(skb);
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}
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return rc;
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}
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/**
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* llc_sap_action_send_xid_c - send XID PDU as response to XID REQ
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* @sap: SAP
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* @skb: the event to send
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*
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* Send a XID command PDU to MAC layer in response to a XID REQUEST
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* primitive from the network layer. Verify event is a primitive type
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* event. Verify the primitive is a XID REQUEST.
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*/
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int llc_sap_action_send_xid_c(struct llc_sap *sap, struct sk_buff *skb)
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{
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struct llc_sap_state_ev *ev = llc_sap_ev(skb);
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int rc;
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llc_pdu_header_init(skb, LLC_PDU_TYPE_U_XID, ev->saddr.lsap,
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ev->daddr.lsap, LLC_PDU_CMD);
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llc_pdu_init_as_xid_cmd(skb, LLC_XID_NULL_CLASS_2, 0);
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rc = llc_mac_hdr_init(skb, ev->saddr.mac, ev->daddr.mac);
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if (likely(!rc)) {
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skb_get(skb);
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rc = dev_queue_xmit(skb);
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}
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return rc;
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}
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/**
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* llc_sap_action_send_xid_r - send XID PDU resp to MAC for received XID
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* @sap: SAP
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* @skb: the event to send
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*
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* Send XID response PDU to MAC in response to an earlier received XID
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* command PDU. Verify event is a PDU type event
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*/
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int llc_sap_action_send_xid_r(struct llc_sap *sap, struct sk_buff *skb)
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{
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u8 mac_da[ETH_ALEN], mac_sa[ETH_ALEN], dsap;
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int rc = 1;
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struct sk_buff *nskb;
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llc_pdu_decode_sa(skb, mac_da);
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llc_pdu_decode_da(skb, mac_sa);
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llc_pdu_decode_ssap(skb, &dsap);
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nskb = llc_alloc_frame(NULL, skb->dev, LLC_PDU_TYPE_U,
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sizeof(struct llc_xid_info));
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if (!nskb)
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goto out;
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llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, sap->laddr.lsap, dsap,
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LLC_PDU_RSP);
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llc_pdu_init_as_xid_rsp(nskb, LLC_XID_NULL_CLASS_2, 0);
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rc = llc_mac_hdr_init(nskb, mac_sa, mac_da);
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if (likely(!rc))
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rc = dev_queue_xmit(nskb);
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out:
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return rc;
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}
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/**
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* llc_sap_action_send_test_c - send TEST PDU to MAC in resp to TEST REQ
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* @sap: SAP
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* @skb: the event to send
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*
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* Send a TEST command PDU to the MAC layer in response to a TEST REQUEST
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* primitive from the network layer. Verify event is a primitive type
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* event; verify the primitive is a TEST REQUEST.
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*/
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int llc_sap_action_send_test_c(struct llc_sap *sap, struct sk_buff *skb)
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{
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struct llc_sap_state_ev *ev = llc_sap_ev(skb);
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int rc;
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llc_pdu_header_init(skb, LLC_PDU_TYPE_U, ev->saddr.lsap,
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ev->daddr.lsap, LLC_PDU_CMD);
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llc_pdu_init_as_test_cmd(skb);
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rc = llc_mac_hdr_init(skb, ev->saddr.mac, ev->daddr.mac);
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if (likely(!rc)) {
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skb_get(skb);
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rc = dev_queue_xmit(skb);
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}
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return rc;
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}
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int llc_sap_action_send_test_r(struct llc_sap *sap, struct sk_buff *skb)
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{
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u8 mac_da[ETH_ALEN], mac_sa[ETH_ALEN], dsap;
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struct sk_buff *nskb;
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int rc = 1;
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u32 data_size;
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if (skb->mac_len < ETH_HLEN)
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return 1;
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llc_pdu_decode_sa(skb, mac_da);
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llc_pdu_decode_da(skb, mac_sa);
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llc_pdu_decode_ssap(skb, &dsap);
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/* The test request command is type U (llc_len = 3) */
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data_size = ntohs(eth_hdr(skb)->h_proto) - 3;
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nskb = llc_alloc_frame(NULL, skb->dev, LLC_PDU_TYPE_U, data_size);
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if (!nskb)
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goto out;
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llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, sap->laddr.lsap, dsap,
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LLC_PDU_RSP);
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llc_pdu_init_as_test_rsp(nskb, skb);
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rc = llc_mac_hdr_init(nskb, mac_sa, mac_da);
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if (likely(!rc))
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rc = dev_queue_xmit(nskb);
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out:
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return rc;
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}
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/**
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* llc_sap_action_report_status - report data link status to layer mgmt
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* @sap: SAP
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* @skb: the event to send
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*
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* Report data link status to layer management. Verify our event is the
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* kind we expect.
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*/
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int llc_sap_action_report_status(struct llc_sap *sap, struct sk_buff *skb)
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{
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return 0;
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}
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/**
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* llc_sap_action_xid_ind - send XID PDU resp to net layer via XID IND
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* @sap: SAP
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* @skb: the event to send
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*
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* Send a XID response PDU to the network layer via a XID INDICATION
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* primitive.
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*/
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int llc_sap_action_xid_ind(struct llc_sap *sap, struct sk_buff *skb)
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{
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llc_sap_rtn_pdu(sap, skb);
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return 0;
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}
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/**
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* llc_sap_action_test_ind - send TEST PDU to net layer via TEST IND
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* @sap: SAP
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* @skb: the event to send
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*
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* Send a TEST response PDU to the network layer via a TEST INDICATION
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* primitive. Verify our event is a PDU type event.
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*/
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int llc_sap_action_test_ind(struct llc_sap *sap, struct sk_buff *skb)
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{
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llc_sap_rtn_pdu(sap, skb);
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return 0;
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}
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