/*
* Generic HDLC support routines for Linux
* Point-to-point protocol support
*
* Copyright (C) 1999 - 2008 Krzysztof Halasa <khc@pm.waw.pl>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of version 2 of the GNU General Public License
* as published by the Free Software Foundation.
*/
#include <linux/errno.h>
#include <linux/hdlc.h>
#include <linux/if_arp.h>
#include <linux/inetdevice.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pkt_sched.h>
#include <linux/poll.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#define DEBUG_CP 0 /* also bytes# to dump */
#define DEBUG_STATE 0
#define DEBUG_HARD_HEADER 0
#define HDLC_ADDR_ALLSTATIONS 0xFF
#define HDLC_CTRL_UI 0x03
#define PID_LCP 0xC021
#define PID_IP 0x0021
#define PID_IPCP 0x8021
#define PID_IPV6 0x0057
#define PID_IPV6CP 0x8057
enum {IDX_LCP = 0, IDX_IPCP, IDX_IPV6CP, IDX_COUNT};
enum {CP_CONF_REQ = 1, CP_CONF_ACK, CP_CONF_NAK, CP_CONF_REJ, CP_TERM_REQ,
CP_TERM_ACK, CP_CODE_REJ, LCP_PROTO_REJ, LCP_ECHO_REQ, LCP_ECHO_REPLY,
LCP_DISC_REQ, CP_CODES};
#if DEBUG_CP
static const char *const code_names[CP_CODES] = {
"0", "ConfReq", "ConfAck", "ConfNak", "ConfRej", "TermReq",
"TermAck", "CodeRej", "ProtoRej", "EchoReq", "EchoReply", "Discard"
};
static char debug_buffer[64 + 3 * DEBUG_CP];
#endif
enum {LCP_OPTION_MRU = 1, LCP_OPTION_ACCM, LCP_OPTION_MAGIC = 5};
struct hdlc_header {
u8 address;
u8 control;
__be16 protocol;
};
struct cp_header {
u8 code;
u8 id;
__be16 len;
};
struct proto {
struct net_device *dev;
struct timer_list timer;
unsigned long timeout;
u16 pid; /* protocol ID */
u8 state;
u8 cr_id; /* ID of last Configuration-Request */
u8 restart_counter;
};
struct ppp {
struct proto protos[IDX_COUNT];
spinlock_t lock;
unsigned long last_pong;
unsigned int req_timeout, cr_retries, term_retries;
unsigned int keepalive_interval, keepalive_timeout;
u8 seq; /* local sequence number for requests */
u8 echo_id; /* ID of last Echo-Request (LCP) */
};
enum {CLOSED = 0, STOPPED, STOPPING, REQ_SENT, ACK_RECV, ACK_SENT, OPENED,
STATES, STATE_MASK = 0xF};
enum {START = 0, STOP, TO_GOOD, TO_BAD, RCR_GOOD, RCR_BAD, RCA, RCN, RTR, RTA,
RUC, RXJ_GOOD, RXJ_BAD, EVENTS};
enum {INV = 0x10, IRC = 0x20, ZRC = 0x40, SCR = 0x80, SCA = 0x100,
SCN = 0x200, STR = 0x400, STA = 0x800, SCJ = 0x1000};
#if DEBUG_STATE
static const char *const state_names[STATES] = {
"Closed", "Stopped", "Stopping", "ReqSent", "AckRecv", "AckSent",
"Opened"
};
static const char *const event_names[EVENTS] = {
"Start", "Stop", "TO+", "TO-", "RCR+", "RCR-", "RCA", "RCN",
"RTR", "RTA", "RUC", "RXJ+", "RXJ-"
};
#endif
static struct sk_buff_head tx_queue; /* used when holding the spin lock */
static int ppp_ioctl(struct net_device *dev, struct ifreq *ifr);
static inline struct ppp* get_ppp(struct net_device *dev)
{
return (struct ppp *)dev_to_hdlc(dev)->state;
}
static inline struct proto* get_proto(struct net_device *dev, u16 pid)
{
struct ppp *ppp = get_ppp(dev);
switch (pid) {
case PID_LCP:
return &ppp->protos[IDX_LCP];
case PID_IPCP:
return &ppp->protos[IDX_IPCP];
case PID_IPV6CP:
return &ppp->protos[IDX_IPV6CP];
default:
return NULL;
}
}
static inline const char* proto_name(u16 pid)
{
switch (pid) {
case PID_LCP:
return "LCP";
case PID_IPCP:
return "IPCP";
case PID_IPV6CP:
return "IPV6CP";
default:
return NULL;
}
}
static __be16 ppp_type_trans(struct sk_buff *skb, struct net_device *dev)
{
struct hdlc_header *data = (struct hdlc_header*)skb->data;
if (skb->len < sizeof(struct hdlc_header))
return htons(ETH_P_HDLC);
if (data->address != HDLC_ADDR_ALLSTATIONS ||
data->control != HDLC_CTRL_UI)
return htons(ETH_P_HDLC);
switch (data->protocol) {
case cpu_to_be16(PID_IP):
skb_pull(skb, sizeof(struct hdlc_header));
return htons(ETH_P_IP);
case cpu_to_be16(PID_IPV6):
skb_pull(skb, sizeof(struct hdlc_header));
return htons(ETH_P_IPV6);
default:
return htons(ETH_P_HDLC);
}
}
static int ppp_hard_header(struct sk_buff *skb, struct net_device *dev,
u16 type, const void *daddr, const void *saddr,
unsigned int len)
{
struct hdlc_header *data;
#if DEBUG_HARD_HEADER
printk(KERN_DEBUG "%s: ppp_hard_header() called\n", dev->name);
#endif
skb_push(skb, sizeof(struct hdlc_header));
data = (struct hdlc_header*)skb->data;
data->address = HDLC_ADDR_ALLSTATIONS;
data->control = HDLC_CTRL_UI;
switch (type) {
case ETH_P_IP:
data->protocol = htons(PID_IP);
break;
case ETH_P_IPV6:
data->protocol = htons(PID_IPV6);
break;
case PID_LCP:
case PID_IPCP:
case PID_IPV6CP:
data->protocol = htons(type);
break;
default: /* unknown protocol */
data->protocol = 0;
}
return sizeof(struct hdlc_header);
}
static void ppp_tx_flush(void)
{
struct sk_buff *skb;
while ((skb = skb_dequeue(&tx_queue)) != NULL)
dev_queue_xmit(skb);
}
static void ppp_tx_cp(struct net_device *dev, u16 pid, u8 code,
u8 id, unsigned int len, const void *data)
{
struct sk_buff *skb;
struct cp_header *cp;
unsigned int magic_len = 0;
static u32 magic;
#if DEBUG_CP
int i;
char *ptr;
#endif
if (pid == PID_LCP && (code == LCP_ECHO_REQ || code == LCP_ECHO_REPLY))
magic_len = sizeof(magic);
skb = dev_alloc_skb(sizeof(struct hdlc_header) +
sizeof(struct cp_header) + magic_len + len);
if (!skb) {
netdev_warn(dev, "out of memory in ppp_tx_cp()\n");
return;
}
skb_reserve(skb, sizeof(struct hdlc_header));
cp = (struct cp_header *)skb_put(skb, sizeof(struct cp_header));
cp->code = code;
cp->id = id;
cp->len = htons(sizeof(struct cp_header) + magic_len + len);
if (magic_len)
memcpy(skb_put(skb, magic_len), &magic, magic_len);
if (len)
memcpy(skb_put(skb, len), data, len);
#if DEBUG_CP
BUG_ON(code >= CP_CODES);
ptr = debug_buffer;
*ptr = '\x0';
for (i = 0; i < min_t(unsigned int, magic_len + len, DEBUG_CP); i++) {
sprintf(ptr, " %02X", skb->data[sizeof(struct cp_header) + i]);
ptr += strlen(ptr);
}
printk(KERN_DEBUG "%s: TX %s [%s id 0x%X]%s\n", dev->name,
proto_name(pid), code_names[code], id, debug_buffer);
#endif
ppp_hard_header(skb, dev, pid, NULL, NULL, 0);
skb->priority = TC_PRIO_CONTROL;
skb->dev = dev;
skb_reset_network_header(skb);
skb_queue_tail(&tx_queue, skb);
}
/* State transition table (compare STD-51)
Events Actions
TO+ = Timeout with counter > 0 irc = Initialize-Restart-Count
TO- = Timeout with counter expired zrc = Zero-Restart-Count
RCR+ = Receive-Configure-Request (Good) scr = Send-Configure-Request
RCR- = Receive-Configure-Request (Bad)
RCA = Receive-Configure-Ack sca = Send-Configure-Ack
RCN = Receive-Configure-Nak/Rej scn = Send-Configure-Nak/Rej
RTR = Receive-Terminate-Request str = Send-Terminate-Request
RTA = Receive-Terminate-Ack sta = Send-Terminate-Ack
RUC = Receive-Unknown-Code scj = Send-Code-Reject
RXJ+ = Receive-Code-Reject (permitted)
or Receive-Protocol-Reject
RXJ- = Receive-Code-Reject (catastrophic)
or Receive-Protocol-Reject
*/
static int cp_table[EVENTS][STATES] = {
/* CLOSED STOPPED STOPPING REQ_SENT ACK_RECV ACK_SENT OPENED
0 1 2 3 4 5 6 */
{IRC|SCR|3, INV , INV , INV , INV , INV , INV }, /* START */
{ INV , 0 , 0 , 0 , 0 , 0 , 0 }, /* STOP */
{ INV , INV ,STR|2, SCR|3 ,SCR|3, SCR|5 , INV }, /* TO+ */
{ INV , INV , 1 , 1 , 1 , 1 , INV }, /* TO- */
{ STA|0 ,IRC|SCR|SCA|5, 2 , SCA|5 ,SCA|6, SCA|5 ,SCR|SCA|5}, /* RCR+ */
{ STA|0 ,IRC|SCR|SCN|3, 2 , SCN|3 ,SCN|4, SCN|3 ,SCR|SCN|3}, /* RCR- */
{ STA|0 , STA|1 , 2 , IRC|4 ,SCR|3, 6 , SCR|3 }, /* RCA */
{ STA|0 , STA|1 , 2 ,IRC|SCR|3,SCR|3,IRC|SCR|5, SCR|3 }, /* RCN */
{ STA|0 , STA|1 ,STA|2, STA|3 ,STA|3, STA|3 ,ZRC|STA|2}, /* RTR */
{ 0 , 1 , 1 , 3 , 3 , 5 , SCR|3 }, /* RTA */
{ SCJ|0 , SCJ|1 ,SCJ|2, SCJ|3 ,SCJ|4, SCJ|5 , SCJ|6 }, /* RUC */
{ 0 , 1 , 2 , 3 , 3 , 5 , 6 }, /* RXJ+ */
{ 0 , 1 , 1 , 1 , 1 , 1 ,IRC|STR|2}, /* RXJ- */
};
/* SCA: RCR+ must supply id, len and data
SCN: RCR- must supply code, id, len and data
STA: RTR must supply id
SCJ: RUC must supply CP packet len and data */
static void ppp_cp_event(struct net_device *dev, u16 pid, u16 event, u8 code,
u8 id, unsigned int len, const void *data)
{
int old_state, action;
struct ppp *ppp = get_ppp(dev);
struct proto *proto = get_proto(dev, pid);
old_state = proto->state;
BUG_ON(old_state >= STATES);
BUG_ON(event >= EVENTS);
#if DEBUG_STATE
printk(KERN_DEBUG "%s: %s ppp_cp_event(%s) %s ...\n", dev->name,
proto_name(pid), event_names[event], state_names[proto->state]);
#endif
action = cp_table[event][old_state];
proto->state = action & STATE_MASK;
if (action & (SCR | STR)) /* set Configure-Req/Terminate-Req timer */
mod_timer(&proto->timer, proto->timeout =
jiffies + ppp->req_timeout * HZ);
if (action & ZRC)
proto->restart_counter = 0;
if (action & IRC)
proto->restart_counter = (proto->state == STOPPING) ?
ppp->term_retries : ppp->cr_retries;
if (action & SCR) /* send Configure-Request */
ppp_tx_cp(dev, pid, CP_CONF_REQ, proto->cr_id = ++ppp->seq,
0, NULL);
if (action & SCA) /* send Configure-Ack */
ppp_tx_cp(dev, pid, CP_CONF_ACK, id, len, data);
if (action & SCN) /* send Configure-Nak/Reject */
ppp_tx_cp(dev, pid, code, id, len, data);
if (action & STR) /* send Terminate-Request */
ppp_tx_cp(dev, pid, CP_TERM_REQ, ++ppp->seq, 0, NULL);
if (action & STA) /* send Terminate-Ack */
ppp_tx_cp(dev, pid, CP_TERM_ACK, id, 0, NULL);
if (action & SCJ) /* send Code-Reject */
ppp_tx_cp(dev, pid, CP_CODE_REJ, ++ppp->seq, len, data);
if (old_state != OPENED && proto->state == OPENED) {
netdev_info(dev, "%s up\n", proto_name(pid));
if (pid == PID_LCP) {
netif_dormant_off(dev);
ppp_cp_event(dev, PID_IPCP, START, 0, 0, 0, NULL);
ppp_cp_event(dev, PID_IPV6CP, START, 0, 0, 0, NULL);
ppp->last_pong = jiffies;
mod_timer(&proto->timer, proto->timeout =
jiffies + ppp->keepalive_interval * HZ);
}
}
if (old_state == OPENED && proto->state != OPENED) {
netdev_info(dev, "%s down\n", proto_name(pid));
if (pid == PID_LCP) {
netif_dormant_on(dev);
ppp_cp_event(dev, PID_IPCP, STOP, 0, 0, 0, NULL);
ppp_cp_event(dev, PID_IPV6CP, STOP, 0, 0, 0, NULL);
}
}
if (old_state != CLOSED && proto->state == CLOSED)
del_timer(&proto->timer);
#if DEBUG_STATE
printk(KERN_DEBUG "%s: %s ppp_cp_event(%s) ... %s\n", dev->name,
proto_name(pid), event_names[event], state_names[proto->state]);
#endif
}
static void ppp_cp_parse_cr(struct net_device *dev, u16 pid, u8 id,
unsigned int req_len, const u8 *data)
{
static u8 const valid_accm[6] = { LCP_OPTION_ACCM, 6, 0, 0, 0, 0 };
const u8 *opt;
u8 *out;
unsigned int len = req_len, nak_len = 0, rej_len = 0;
if (!(out = kmalloc(len, GFP_ATOMIC))) {
dev->stats.rx_dropped++;
return; /* out of memory, ignore CR packet */
}
for (opt = data; len; len -= opt[1], opt += opt[1]) {
if (len < 2 || len < opt[1]) {
dev->stats.rx_errors++;
kfree(out);
return; /* bad packet, drop silently */
}
if (pid == PID_LCP)
switch (opt[0]) {
case LCP_OPTION_MRU:
continue; /* MRU always OK and > 1500 bytes? */
case LCP_OPTION_ACCM: /* async control character map */
if (!memcmp(opt, valid_accm,
sizeof(valid_accm)))
continue;
if (!rej_len) { /* NAK it */
memcpy(out + nak_len, valid_accm,
sizeof(valid_accm));
nak_len += sizeof(valid_accm);
continue;
}
break;
case LCP_OPTION_MAGIC:
if (opt[1] != 6 || (!opt[2] && !opt[3] &&
!opt[4] && !opt[5]))
break; /* reject invalid magic number */
continue;
}
/* reject this option */
memcpy(out + rej_len, opt, opt[1]);
rej_len += opt[1];
}
if (rej_len)
ppp_cp_event(dev, pid, RCR_BAD, CP_CONF_REJ, id, rej_len, out);
else if (nak_len)
ppp_cp_event(dev, pid, RCR_BAD, CP_CONF_NAK, id, nak_len, out);
else
ppp_cp_event(dev, pid, RCR_GOOD, CP_CONF_ACK, id, req_len, data);
kfree(out);
}
static int ppp_rx(struct sk_buff *skb)
{
struct hdlc_header *hdr = (struct hdlc_header*)skb->data;
struct net_device *dev = skb->dev;
struct ppp *ppp = get_ppp(dev);
struct proto *proto;
struct cp_header *cp;
unsigned long flags;
unsigned int len;
u16 pid;
#if DEBUG_CP
int i;
char *ptr;
#endif
spin_lock_irqsave(&ppp->lock, flags);
/* Check HDLC header */
if (skb->len < sizeof(struct hdlc_header))
goto rx_error;
cp = (struct cp_header*)skb_pull(skb, sizeof(struct hdlc_header));
if (hdr->address != HDLC_ADDR_ALLSTATIONS ||
hdr->control != HDLC_CTRL_UI)
goto rx_error;
pid = ntohs(hdr->protocol);
proto = get_proto(dev, pid);
if (!proto) {
if (ppp->protos[IDX_LCP].state == OPENED)
ppp_tx_cp(dev, PID_LCP, LCP_PROTO_REJ,
++ppp->seq, skb->len + 2, &hdr->protocol);
goto rx_error;
}
len = ntohs(cp->len);
if (len < sizeof(struct cp_header) /* no complete CP header? */ ||
skb->len < len /* truncated packet? */)
goto rx_error;
skb_pull(skb, sizeof(struct cp_header));
len -= sizeof(struct cp_header);
/* HDLC and CP headers stripped from skb */
#if DEBUG_CP
if (cp->code < CP_CODES)
sprintf(debug_buffer, "[%s id 0x%X]", code_names[cp->code],
cp->id);
else
sprintf(debug_buffer, "[code %u id 0x%X]", cp->code, cp->id);
ptr = debug_buffer + strlen(debug_buffer);
for (i = 0; i < min_t(unsigned int, len, DEBUG_CP); i++) {
sprintf(ptr, " %02X", skb->data[i]);
ptr += strlen(ptr);
}
printk(KERN_DEBUG "%s: RX %s %s\n", dev->name, proto_name(pid),
debug_buffer);
#endif
/* LCP only */
if (pid == PID_LCP)
switch (cp->code) {
case LCP_PROTO_REJ:
pid = ntohs(*(__be16*)skb->data);
if (pid == PID_LCP || pid == PID_IPCP ||
pid == PID_IPV6CP)
ppp_cp_event(dev, pid, RXJ_BAD, 0, 0,
0, NULL);
goto out;
case LCP_ECHO_REQ: /* send Echo-Reply */
if (len >= 4 && proto->state == OPENED)
ppp_tx_cp(dev, PID_LCP, LCP_ECHO_REPLY,
cp->id, len - 4, skb->data + 4);
goto out;
case LCP_ECHO_REPLY:
if (cp->id == ppp->echo_id)
ppp->last_pong = jiffies;
goto out;
case LCP_DISC_REQ: /* discard */
goto out;
}
/* LCP, IPCP and IPV6CP */
switch (cp->code) {
case CP_CONF_REQ:
ppp_cp_parse_cr(dev, pid, cp->id, len, skb->data);
break;
case CP_CONF_ACK:
if (cp->id == proto->cr_id)
ppp_cp_event(dev, pid, RCA, 0, 0, 0, NULL);
break;
case CP_CONF_REJ:
case CP_CONF_NAK:
if (cp->id == proto->cr_id)
ppp_cp_event(dev, pid, RCN, 0, 0, 0, NULL);
break;
case CP_TERM_REQ:
ppp_cp_event(dev, pid, RTR, 0, cp->id, 0, NULL);
break;
case CP_TERM_ACK:
ppp_cp_event(dev, pid, RTA, 0, 0, 0, NULL);
break;
case CP_CODE_REJ:
ppp_cp_event(dev, pid, RXJ_BAD, 0, 0, 0, NULL);
break;
default:
len += sizeof(struct cp_header);
if (len > dev->mtu)
len = dev->mtu;
ppp_cp_event(dev, pid, RUC, 0, 0, len, cp);
break;
}
goto out;
rx_error:
dev->stats.rx_errors++;
out:
spin_unlock_irqrestore(&ppp->lock, flags);
dev_kfree_skb_any(skb);
ppp_tx_flush();
return NET_RX_DROP;
}
static void ppp_timer(unsigned long arg)
{
struct proto *proto = (struct proto *)arg;
struct ppp *ppp = get_ppp(proto->dev);
unsigned long flags;
spin_lock_irqsave(&ppp->lock, flags);
switch (proto->state) {
case STOPPING:
case REQ_SENT:
case ACK_RECV:
case ACK_SENT:
if (proto->restart_counter) {
ppp_cp_event(proto->dev, proto->pid, TO_GOOD, 0, 0,
0, NULL);
proto->restart_counter--;
} else
ppp_cp_event(proto->dev, proto->pid, TO_BAD, 0, 0,
0, NULL);
break;
case OPENED:
if (proto->pid != PID_LCP)
break;
if (time_after(jiffies, ppp->last_pong +
ppp->keepalive_timeout * HZ)) {
netdev_info(proto->dev, "Link down\n");
ppp_cp_event(proto->dev, PID_LCP, STOP, 0, 0, 0, NULL);
ppp_cp_event(proto->dev, PID_LCP, START, 0, 0, 0, NULL);
} else { /* send keep-alive packet */
ppp->echo_id = ++ppp->seq;
ppp_tx_cp(proto->dev, PID_LCP, LCP_ECHO_REQ,
ppp->echo_id, 0, NULL);
proto->timer.expires = jiffies +
ppp->keepalive_interval * HZ;
add_timer(&proto->timer);
}
break;
}
spin_unlock_irqrestore(&ppp->lock, flags);
ppp_tx_flush();
}
static void ppp_start(struct net_device *dev)
{
struct ppp *ppp = get_ppp(dev);
int i;
for (i = 0; i < IDX_COUNT; i++) {
struct proto *proto = &ppp->protos[i];
proto->dev = dev;
init_timer(&proto->timer);
proto->timer.function = ppp_timer;
proto->timer.data = (unsigned long)proto;
proto->state = CLOSED;
}
ppp->protos[IDX_LCP].pid = PID_LCP;
ppp->protos[IDX_IPCP].pid = PID_IPCP;
ppp->protos[IDX_IPV6CP].pid = PID_IPV6CP;
ppp_cp_event(dev, PID_LCP, START, 0, 0, 0, NULL);
}
static void ppp_stop(struct net_device *dev)
{
ppp_cp_event(dev, PID_LCP, STOP, 0, 0, 0, NULL);
}
static void ppp_close(struct net_device *dev)
{
ppp_tx_flush();
}
static struct hdlc_proto proto = {
.start = ppp_start,
.stop = ppp_stop,
.close = ppp_close,
.type_trans = ppp_type_trans,
.ioctl = ppp_ioctl,
.netif_rx = ppp_rx,
.module = THIS_MODULE,
};
static const struct header_ops ppp_header_ops = {
.create = ppp_hard_header,
};
static int ppp_ioctl(struct net_device *dev, struct ifreq *ifr)
{
hdlc_device *hdlc = dev_to_hdlc(dev);
struct ppp *ppp;
int result;
switch (ifr->ifr_settings.type) {
case IF_GET_PROTO:
if (dev_to_hdlc(dev)->proto != &proto)
return -EINVAL;
ifr->ifr_settings.type = IF_PROTO_PPP;
return 0; /* return protocol only, no settable parameters */
case IF_PROTO_PPP:
if (!capable(CAP_NET_ADMIN))
return -EPERM;
if (dev->flags & IFF_UP)
return -EBUSY;
/* no settable parameters */
result = hdlc->attach(dev, ENCODING_NRZ,PARITY_CRC16_PR1_CCITT);
if (result)
return result;
result = attach_hdlc_protocol(dev, &proto, sizeof(struct ppp));
if (result)
return result;
ppp = get_ppp(dev);
spin_lock_init(&ppp->lock);
ppp->req_timeout = 2;
ppp->cr_retries = 10;
ppp->term_retries = 2;
ppp->keepalive_interval = 10;
ppp->keepalive_timeout = 60;
dev->hard_header_len = sizeof(struct hdlc_header);
dev->header_ops = &ppp_header_ops;
dev->type = ARPHRD_PPP;
netif_dormant_on(dev);
return 0;
}
return -EINVAL;
}
static int __init mod_init(void)
{
skb_queue_head_init(&tx_queue);
register_hdlc_protocol(&proto);
return 0;
}
static void __exit mod_exit(void)
{
unregister_hdlc_protocol(&proto);
}
module_init(mod_init);
module_exit(mod_exit);
MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
MODULE_DESCRIPTION("PPP protocol support for generic HDLC");
MODULE_LICENSE("GPL v2");