net/wan/hdlc_cisco.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Generic HDLC support routines for Linux
0004  * Cisco HDLC support
0005  *
0006  * Copyright (C) 2000 - 2006 Krzysztof Halasa <khc@pm.waw.pl>
0007  */
0008
0009 #include <linux/errno.h>
0010 #include <linux/hdlc.h>
0011 #include <linux/if_arp.h>
0012 #include <linux/inetdevice.h>
0013 #include <linux/init.h>
0014 #include <linux/kernel.h>
0015 #include <linux/module.h>
0016 #include <linux/pkt_sched.h>
0017 #include <linux/poll.h>
0018 #include <linux/rtnetlink.h>
0019 #include <linux/skbuff.h>
0020
0021 #undef DEBUG_HARD_HEADER
0022
0023 #define CISCO_MULTICAST     0x8F    /* Cisco multicast address */
0024 #define CISCO_UNICAST       0x0F    /* Cisco unicast address */
0025 #define CISCO_KEEPALIVE     0x8035  /* Cisco keepalive protocol */
0026 #define CISCO_SYS_INFO      0x2000  /* Cisco interface/system info */
0027 #define CISCO_ADDR_REQ      0   /* Cisco address request */
0028 #define CISCO_ADDR_REPLY    1   /* Cisco address reply */
0029 #define CISCO_KEEPALIVE_REQ 2   /* Cisco keepalive request */
0030
0031 struct hdlc_header {
0032     u8 address;
0033     u8 control;
0034     __be16 protocol;
0035 } __packed;
0036
0037 struct cisco_packet {
0038     __be32 type;        /* code */
0039     __be32 par1;
0040     __be32 par2;
0041     __be16 rel;     /* reliability */
0042     __be32 time;
0043 } __packed;
0044 #define CISCO_PACKET_LEN    18
0045 #define CISCO_BIG_PACKET_LEN    20
0046
0047 struct cisco_state {
0048     cisco_proto settings;
0049
0050     struct timer_list timer;
0051     struct net_device *dev;
0052     spinlock_t lock;
0053     unsigned long last_poll;
0054     int up;
0055     u32 txseq; /* TX sequence number, 0 = none */
0056     u32 rxseq; /* RX sequence number */
0057 };
0058
0059 static int cisco_ioctl(struct net_device *dev, struct if_settings *ifs);
0060
0061 static inline struct cisco_state *state(hdlc_device *hdlc)
0062 {
0063     return (struct cisco_state *)hdlc->state;
0064 }
0065
0066 static int cisco_hard_header(struct sk_buff *skb, struct net_device *dev,
0067                  u16 type, const void *daddr, const void *saddr,
0068                  unsigned int len)
0069 {
0070     struct hdlc_header *data;
0071 #ifdef DEBUG_HARD_HEADER
0072     netdev_dbg(dev, "%s called\n", __func__);
0073 #endif
0074
0075     skb_push(skb, sizeof(struct hdlc_header));
0076     data = (struct hdlc_header *)skb->data;
0077     if (type == CISCO_KEEPALIVE)
0078         data->address = CISCO_MULTICAST;
0079     else
0080         data->address = CISCO_UNICAST;
0081     data->control = 0;
0082     data->protocol = htons(type);
0083
0084     return sizeof(struct hdlc_header);
0085 }
0086
0087 static void cisco_keepalive_send(struct net_device *dev, u32 type,
0088                  __be32 par1, __be32 par2)
0089 {
0090     struct sk_buff *skb;
0091     struct cisco_packet *data;
0092
0093     skb = dev_alloc_skb(sizeof(struct hdlc_header) +
0094                 sizeof(struct cisco_packet));
0095     if (!skb)
0096         return;
0097
0098     skb_reserve(skb, 4);
0099     cisco_hard_header(skb, dev, CISCO_KEEPALIVE, NULL, NULL, 0);
0100     data = (struct cisco_packet *)(skb->data + 4);
0101
0102     data->type = htonl(type);
0103     data->par1 = par1;
0104     data->par2 = par2;
0105     data->rel = cpu_to_be16(0xFFFF);
0106     /* we will need do_div here if 1000 % HZ != 0 */
0107     data->time = htonl((jiffies - INITIAL_JIFFIES) * (1000 / HZ));
0108
0109     skb_put(skb, sizeof(struct cisco_packet));
0110     skb->priority = TC_PRIO_CONTROL;
0111     skb->dev = dev;
0112     skb->protocol = htons(ETH_P_HDLC);
0113     skb_reset_network_header(skb);
0114
0115     dev_queue_xmit(skb);
0116 }
0117
0118 static __be16 cisco_type_trans(struct sk_buff *skb, struct net_device *dev)
0119 {
0120     struct hdlc_header *data = (struct hdlc_header *)skb->data;
0121
0122     if (skb->len < sizeof(struct hdlc_header))
0123         return cpu_to_be16(ETH_P_HDLC);
0124
0125     if (data->address != CISCO_MULTICAST &&
0126         data->address != CISCO_UNICAST)
0127         return cpu_to_be16(ETH_P_HDLC);
0128
0129     switch (data->protocol) {
0130     case cpu_to_be16(ETH_P_IP):
0131     case cpu_to_be16(ETH_P_IPX):
0132     case cpu_to_be16(ETH_P_IPV6):
0133         skb_pull(skb, sizeof(struct hdlc_header));
0134         return data->protocol;
0135     default:
0136         return cpu_to_be16(ETH_P_HDLC);
0137     }
0138 }
0139
0140 static int cisco_rx(struct sk_buff *skb)
0141 {
0142     struct net_device *dev = skb->dev;
0143     hdlc_device *hdlc = dev_to_hdlc(dev);
0144     struct cisco_state *st = state(hdlc);
0145     struct hdlc_header *data = (struct hdlc_header *)skb->data;
0146     struct cisco_packet *cisco_data;
0147     struct in_device *in_dev;
0148     __be32 addr, mask;
0149     u32 ack;
0150
0151     if (skb->len < sizeof(struct hdlc_header))
0152         goto rx_error;
0153
0154     if (data->address != CISCO_MULTICAST &&
0155         data->address != CISCO_UNICAST)
0156         goto rx_error;
0157
0158     switch (ntohs(data->protocol)) {
0159     case CISCO_SYS_INFO:
0160         /* Packet is not needed, drop it. */
0161         dev_kfree_skb_any(skb);
0162         return NET_RX_SUCCESS;
0163
0164     case CISCO_KEEPALIVE:
0165         if ((skb->len != sizeof(struct hdlc_header) +
0166              CISCO_PACKET_LEN) &&
0167             (skb->len != sizeof(struct hdlc_header) +
0168              CISCO_BIG_PACKET_LEN)) {
0169             netdev_info(dev, "Invalid length of Cisco control packet (%d bytes)\n",
0170                     skb->len);
0171             goto rx_error;
0172         }
0173
0174         cisco_data = (struct cisco_packet *)(skb->data + sizeof
0175                             (struct hdlc_header));
0176
0177         switch (ntohl(cisco_data->type)) {
0178         case CISCO_ADDR_REQ: /* Stolen from syncppp.c :-) */
0179             rcu_read_lock();
0180             in_dev = __in_dev_get_rcu(dev);
0181             addr = 0;
0182             mask = ~cpu_to_be32(0); /* is the mask correct? */
0183
0184             if (in_dev != NULL) {
0185                 const struct in_ifaddr *ifa;
0186
0187                 in_dev_for_each_ifa_rcu(ifa, in_dev) {
0188                     if (strcmp(dev->name,
0189                            ifa->ifa_label) == 0) {
0190                         addr = ifa->ifa_local;
0191                         mask = ifa->ifa_mask;
0192                         break;
0193                     }
0194                 }
0195
0196                 cisco_keepalive_send(dev, CISCO_ADDR_REPLY,
0197                              addr, mask);
0198             }
0199             rcu_read_unlock();
0200             dev_kfree_skb_any(skb);
0201             return NET_RX_SUCCESS;
0202
0203         case CISCO_ADDR_REPLY:
0204             netdev_info(dev, "Unexpected Cisco IP address reply\n");
0205             goto rx_error;
0206
0207         case CISCO_KEEPALIVE_REQ:
0208             spin_lock(&st->lock);
0209             st->rxseq = ntohl(cisco_data->par1);
0210             ack = ntohl(cisco_data->par2);
0211             if (ack && (ack == st->txseq ||
0212                     /* our current REQ may be in transit */
0213                     ack == st->txseq - 1)) {
0214                 st->last_poll = jiffies;
0215                 if (!st->up) {
0216                     u32 sec, min, hrs, days;
0217
0218                     sec = ntohl(cisco_data->time) / 1000;
0219                     min = sec / 60; sec -= min * 60;
0220                     hrs = min / 60; min -= hrs * 60;
0221                     days = hrs / 24; hrs -= days * 24;
0222                     netdev_info(dev, "Link up (peer uptime %ud%uh%um%us)\n",
0223                             days, hrs, min, sec);
0224                     netif_dormant_off(dev);
0225                     st->up = 1;
0226                 }
0227             }
0228             spin_unlock(&st->lock);
0229
0230             dev_kfree_skb_any(skb);
0231             return NET_RX_SUCCESS;
0232         } /* switch (keepalive type) */
0233     } /* switch (protocol) */
0234
0235     netdev_info(dev, "Unsupported protocol %x\n", ntohs(data->protocol));
0236     dev_kfree_skb_any(skb);
0237     return NET_RX_DROP;
0238
0239 rx_error:
0240     dev->stats.rx_errors++; /* Mark error */
0241     dev_kfree_skb_any(skb);
0242     return NET_RX_DROP;
0243 }
0244
0245 static void cisco_timer(struct timer_list *t)
0246 {
0247     struct cisco_state *st = from_timer(st, t, timer);
0248     struct net_device *dev = st->dev;
0249
0250     spin_lock(&st->lock);
0251     if (st->up &&
0252         time_after(jiffies, st->last_poll + st->settings.timeout * HZ)) {
0253         st->up = 0;
0254         netdev_info(dev, "Link down\n");
0255         netif_dormant_on(dev);
0256     }
0257
0258     cisco_keepalive_send(dev, CISCO_KEEPALIVE_REQ, htonl(++st->txseq),
0259                  htonl(st->rxseq));
0260     spin_unlock(&st->lock);
0261
0262     st->timer.expires = jiffies + st->settings.interval * HZ;
0263     add_timer(&st->timer);
0264 }
0265
0266 static void cisco_start(struct net_device *dev)
0267 {
0268     hdlc_device *hdlc = dev_to_hdlc(dev);
0269     struct cisco_state *st = state(hdlc);
0270     unsigned long flags;
0271
0272     spin_lock_irqsave(&st->lock, flags);
0273     st->up = st->txseq = st->rxseq = 0;
0274     spin_unlock_irqrestore(&st->lock, flags);
0275
0276     st->dev = dev;
0277     timer_setup(&st->timer, cisco_timer, 0);
0278     st->timer.expires = jiffies + HZ; /* First poll after 1 s */
0279     add_timer(&st->timer);
0280 }
0281
0282 static void cisco_stop(struct net_device *dev)
0283 {
0284     hdlc_device *hdlc = dev_to_hdlc(dev);
0285     struct cisco_state *st = state(hdlc);
0286     unsigned long flags;
0287
0288     del_timer_sync(&st->timer);
0289
0290     spin_lock_irqsave(&st->lock, flags);
0291     netif_dormant_on(dev);
0292     st->up = st->txseq = 0;
0293     spin_unlock_irqrestore(&st->lock, flags);
0294 }
0295
0296 static struct hdlc_proto proto = {
0297     .start      = cisco_start,
0298     .stop       = cisco_stop,
0299     .type_trans = cisco_type_trans,
0300     .ioctl      = cisco_ioctl,
0301     .netif_rx   = cisco_rx,
0302     .module     = THIS_MODULE,
0303 };
0304
0305 static const struct header_ops cisco_header_ops = {
0306     .create = cisco_hard_header,
0307 };
0308
0309 static int cisco_ioctl(struct net_device *dev, struct if_settings *ifs)
0310 {
0311     cisco_proto __user *cisco_s = ifs->ifs_ifsu.cisco;
0312     const size_t size = sizeof(cisco_proto);
0313     cisco_proto new_settings;
0314     hdlc_device *hdlc = dev_to_hdlc(dev);
0315     int result;
0316
0317     switch (ifs->type) {
0318     case IF_GET_PROTO:
0319         if (dev_to_hdlc(dev)->proto != &proto)
0320             return -EINVAL;
0321         ifs->type = IF_PROTO_CISCO;
0322         if (ifs->size < size) {
0323             ifs->size = size; /* data size wanted */
0324             return -ENOBUFS;
0325         }
0326         if (copy_to_user(cisco_s, &state(hdlc)->settings, size))
0327             return -EFAULT;
0328         return 0;
0329
0330     case IF_PROTO_CISCO:
0331         if (!capable(CAP_NET_ADMIN))
0332             return -EPERM;
0333
0334         if (dev->flags & IFF_UP)
0335             return -EBUSY;
0336
0337         if (copy_from_user(&new_settings, cisco_s, size))
0338             return -EFAULT;
0339
0340         if (new_settings.interval < 1 ||
0341             new_settings.timeout < 2)
0342             return -EINVAL;
0343
0344         result = hdlc->attach(dev, ENCODING_NRZ,
0345                       PARITY_CRC16_PR1_CCITT);
0346         if (result)
0347             return result;
0348
0349         result = attach_hdlc_protocol(dev, &proto,
0350                           sizeof(struct cisco_state));
0351         if (result)
0352             return result;
0353
0354         memcpy(&state(hdlc)->settings, &new_settings, size);
0355         spin_lock_init(&state(hdlc)->lock);
0356         dev->header_ops = &cisco_header_ops;
0357         dev->hard_header_len = sizeof(struct hdlc_header);
0358         dev->type = ARPHRD_CISCO;
0359         call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE, dev);
0360         netif_dormant_on(dev);
0361         return 0;
0362     }
0363
0364     return -EINVAL;
0365 }
0366
0367 static int __init hdlc_cisco_init(void)
0368 {
0369     register_hdlc_protocol(&proto);
0370     return 0;
0371 }
0372
0373 static void __exit hdlc_cisco_exit(void)
0374 {
0375     unregister_hdlc_protocol(&proto);
0376 }
0377
0378 module_init(hdlc_cisco_init);
0379 module_exit(hdlc_cisco_exit);
0380
0381 MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
0382 MODULE_DESCRIPTION("Cisco HDLC protocol support for generic HDLC");
0383 MODULE_LICENSE("GPL v2");