From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Andr=C3=A9=20Fabian=20Silva=20Delgado?= Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- net/llc/llc_input.c | 226 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 226 insertions(+) create mode 100644 net/llc/llc_input.c (limited to 'net/llc/llc_input.c') diff --git a/net/llc/llc_input.c b/net/llc/llc_input.c new file mode 100644 index 000000000..dd3e83328 --- /dev/null +++ b/net/llc/llc_input.c @@ -0,0 +1,226 @@ +/* + * llc_input.c - Minimal input path for LLC + * + * Copyright (c) 1997 by Procom Technology, Inc. + * 2001-2003 by Arnaldo Carvalho de Melo + * + * This program can be redistributed or modified under the terms of the + * GNU General Public License as published by the Free Software Foundation. + * This program is distributed without any warranty or implied warranty + * of merchantability or fitness for a particular purpose. + * + * See the GNU General Public License for more details. + */ +#include +#include +#include +#include +#include +#include +#include + +#if 0 +#define dprintk(args...) printk(KERN_DEBUG args) +#else +#define dprintk(args...) +#endif + +/* + * Packet handler for the station, registerable because in the minimal + * LLC core that is taking shape only the very minimal subset of LLC that + * is needed for things like IPX, Appletalk, etc will stay, with all the + * rest in the llc1 and llc2 modules. + */ +static void (*llc_station_handler)(struct sk_buff *skb); + +/* + * Packet handlers for LLC_DEST_SAP and LLC_DEST_CONN. + */ +static void (*llc_type_handlers[2])(struct llc_sap *sap, + struct sk_buff *skb); + +void llc_add_pack(int type, void (*handler)(struct llc_sap *sap, + struct sk_buff *skb)) +{ + smp_wmb(); /* ensure initialisation is complete before it's called */ + if (type == LLC_DEST_SAP || type == LLC_DEST_CONN) + llc_type_handlers[type - 1] = handler; +} + +void llc_remove_pack(int type) +{ + if (type == LLC_DEST_SAP || type == LLC_DEST_CONN) + llc_type_handlers[type - 1] = NULL; + synchronize_net(); +} + +void llc_set_station_handler(void (*handler)(struct sk_buff *skb)) +{ + /* Ensure initialisation is complete before it's called */ + if (handler) + smp_wmb(); + + llc_station_handler = handler; + + if (!handler) + synchronize_net(); +} + +/** + * llc_pdu_type - returns which LLC component must handle for PDU + * @skb: input skb + * + * This function returns which LLC component must handle this PDU. + */ +static __inline__ int llc_pdu_type(struct sk_buff *skb) +{ + int type = LLC_DEST_CONN; /* I-PDU or S-PDU type */ + struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb); + + if ((pdu->ctrl_1 & LLC_PDU_TYPE_MASK) != LLC_PDU_TYPE_U) + goto out; + switch (LLC_U_PDU_CMD(pdu)) { + case LLC_1_PDU_CMD_XID: + case LLC_1_PDU_CMD_UI: + case LLC_1_PDU_CMD_TEST: + type = LLC_DEST_SAP; + break; + case LLC_2_PDU_CMD_SABME: + case LLC_2_PDU_CMD_DISC: + case LLC_2_PDU_RSP_UA: + case LLC_2_PDU_RSP_DM: + case LLC_2_PDU_RSP_FRMR: + break; + default: + type = LLC_DEST_INVALID; + break; + } +out: + return type; +} + +/** + * llc_fixup_skb - initializes skb pointers + * @skb: This argument points to incoming skb + * + * Initializes internal skb pointer to start of network layer by deriving + * length of LLC header; finds length of LLC control field in LLC header + * by looking at the two lowest-order bits of the first control field + * byte; field is either 3 or 4 bytes long. + */ +static inline int llc_fixup_skb(struct sk_buff *skb) +{ + u8 llc_len = 2; + struct llc_pdu_un *pdu; + + if (unlikely(!pskb_may_pull(skb, sizeof(*pdu)))) + return 0; + + pdu = (struct llc_pdu_un *)skb->data; + if ((pdu->ctrl_1 & LLC_PDU_TYPE_MASK) == LLC_PDU_TYPE_U) + llc_len = 1; + llc_len += 2; + + if (unlikely(!pskb_may_pull(skb, llc_len))) + return 0; + + skb->transport_header += llc_len; + skb_pull(skb, llc_len); + if (skb->protocol == htons(ETH_P_802_2)) { + __be16 pdulen = eth_hdr(skb)->h_proto; + s32 data_size = ntohs(pdulen) - llc_len; + + if (data_size < 0 || + !pskb_may_pull(skb, data_size)) + return 0; + if (unlikely(pskb_trim_rcsum(skb, data_size))) + return 0; + } + return 1; +} + +/** + * llc_rcv - 802.2 entry point from net lower layers + * @skb: received pdu + * @dev: device that receive pdu + * @pt: packet type + * + * When the system receives a 802.2 frame this function is called. It + * checks SAP and connection of received pdu and passes frame to + * llc_{station,sap,conn}_rcv for sending to proper state machine. If + * the frame is related to a busy connection (a connection is sending + * data now), it queues this frame in the connection's backlog. + */ +int llc_rcv(struct sk_buff *skb, struct net_device *dev, + struct packet_type *pt, struct net_device *orig_dev) +{ + struct llc_sap *sap; + struct llc_pdu_sn *pdu; + int dest; + int (*rcv)(struct sk_buff *, struct net_device *, + struct packet_type *, struct net_device *); + void (*sta_handler)(struct sk_buff *skb); + void (*sap_handler)(struct llc_sap *sap, struct sk_buff *skb); + + if (!net_eq(dev_net(dev), &init_net)) + goto drop; + + /* + * When the interface is in promisc. mode, drop all the crap that it + * receives, do not try to analyse it. + */ + if (unlikely(skb->pkt_type == PACKET_OTHERHOST)) { + dprintk("%s: PACKET_OTHERHOST\n", __func__); + goto drop; + } + skb = skb_share_check(skb, GFP_ATOMIC); + if (unlikely(!skb)) + goto out; + if (unlikely(!llc_fixup_skb(skb))) + goto drop; + pdu = llc_pdu_sn_hdr(skb); + if (unlikely(!pdu->dsap)) /* NULL DSAP, refer to station */ + goto handle_station; + sap = llc_sap_find(pdu->dsap); + if (unlikely(!sap)) {/* unknown SAP */ + dprintk("%s: llc_sap_find(%02X) failed!\n", __func__, + pdu->dsap); + goto drop; + } + /* + * First the upper layer protocols that don't need the full + * LLC functionality + */ + rcv = rcu_dereference(sap->rcv_func); + dest = llc_pdu_type(skb); + sap_handler = dest ? ACCESS_ONCE(llc_type_handlers[dest - 1]) : NULL; + if (unlikely(!sap_handler)) { + if (rcv) + rcv(skb, dev, pt, orig_dev); + else + kfree_skb(skb); + } else { + if (rcv) { + struct sk_buff *cskb = skb_clone(skb, GFP_ATOMIC); + if (cskb) + rcv(cskb, dev, pt, orig_dev); + } + sap_handler(sap, skb); + } + llc_sap_put(sap); +out: + return 0; +drop: + kfree_skb(skb); + goto out; +handle_station: + sta_handler = ACCESS_ONCE(llc_station_handler); + if (!sta_handler) + goto drop; + sta_handler(skb); + goto out; +} + +EXPORT_SYMBOL(llc_add_pack); +EXPORT_SYMBOL(llc_remove_pack); +EXPORT_SYMBOL(llc_set_station_handler); -- cgit v1.2.3