ipconfig.c

linux 内核源代码

/*
 *  $Id: ipconfig.c,v 1.46 2002/02/01 22:01:04 davem Exp $
 *
 *  Automatic Configuration of IP -- use DHCP, BOOTP, RARP, or
 *  user-supplied information to configure own IP address and routes.
 *
 *  Copyright (C) 1996-1998 Martin Mares <[e-mail]>
 *
 *  Derived from network configuration code in fs/nfs/nfsroot.c,
 *  originally Copyright (C) 1995, 1996 Gero Kuhlmann and me.
 *
 *  BOOTP rewritten to construct and analyse packets itself instead
 *  of misusing the IP layer. num_bugs_causing_wrong_arp_replies--;
 *					     -- MJ, December 1998
 *
 *  Fixed ip_auto_config_setup calling at startup in the new "Linker Magic"
 *  initialization scheme.
 *	- Arnaldo Carvalho de Melo <[e-mail]>, 08/11/1999
 *
 *  DHCP support added.  To users this looks like a whole separate
 *  protocol, but we know it's just a bag on the side of BOOTP.
 *		-- Chip Salzenberg <[e-mail]>, May 2000
 *
 *  Ported DHCP support from 2.2.16 to 2.4.0-test4
 *              -- Eric Biederman <[e-mail]>, 30 Aug 2000
 *
 *  Merged changes from 2.2.19 into 2.4.3
 *              -- Eric Biederman <[e-mail]>, 22 April Aug 2001
 *
 *  Multiple Nameservers in /proc/net/pnp
 *              --  Josef Siemes <[e-mail]>, Aug 2002
 */

#include <linux/types.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/jiffies.h>
#include <linux/random.h>
#include <linux/init.h>
#include <linux/utsname.h>
#include <linux/in.h>
#include <linux/if.h>
#include <linux/inet.h>
#include <linux/inetdevice.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <linux/socket.h>
#include <linux/route.h>
#include <linux/udp.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/major.h>
#include <linux/root_dev.h>
#include <linux/delay.h>
#include <linux/nfs_fs.h>
#include <net/net_namespace.h>
#include <net/arp.h>
#include <net/ip.h>
#include <net/ipconfig.h>
#include <net/route.h>

#include <asm/uaccess.h>
#include <net/checksum.h>
#include <asm/processor.h>

/* Define this to allow debugging output */
#undef IPCONFIG_DEBUG

#ifdef IPCONFIG_DEBUG
#define DBG(x) printk x
#else
#define DBG(x) do { } while(0)
#endif

#if defined(CONFIG_IP_PNP_DHCP)
#define IPCONFIG_DHCP
#endif
#if defined(CONFIG_IP_PNP_BOOTP) || defined(CONFIG_IP_PNP_DHCP)
#define IPCONFIG_BOOTP
#endif
#if defined(CONFIG_IP_PNP_RARP)
#define IPCONFIG_RARP
#endif
#if defined(IPCONFIG_BOOTP) || defined(IPCONFIG_RARP)
#define IPCONFIG_DYNAMIC
#endif

/* Define the friendly delay before and after opening net devices */
#define CONF_PRE_OPEN		500	/* Before opening: 1/2 second */
#define CONF_POST_OPEN		1	/* After opening: 1 second */

/* Define the timeout for waiting for a DHCP/BOOTP/RARP reply */
#define CONF_OPEN_RETRIES 	2	/* (Re)open devices twice */
#define CONF_SEND_RETRIES 	6	/* Send six requests per open */
#define CONF_INTER_TIMEOUT	(HZ/2)	/* Inter-device timeout: 1/2 second */
#define CONF_BASE_TIMEOUT	(HZ*2)	/* Initial timeout: 2 seconds */
#define CONF_TIMEOUT_RANDOM	(HZ)	/* Maximum amount of randomization */
#define CONF_TIMEOUT_MULT	*7/4	/* Rate of timeout growth */
#define CONF_TIMEOUT_MAX	(HZ*30)	/* Maximum allowed timeout */
#define CONF_NAMESERVERS_MAX   3       /* Maximum number of nameservers
					   - '3' from resolv.h */

#define NONE __constant_htonl(INADDR_NONE)

/*
 * Public IP configuration
 */

/* This is used by platforms which might be able to set the ipconfig
 * variables using firmware environment vars.  If this is set, it will
 * ignore such firmware variables.
 */
int ic_set_manually __initdata = 0;		/* IPconfig parameters set manually */

static int ic_enable __initdata = 0;		/* IP config enabled? */

/* Protocol choice */
int ic_proto_enabled __initdata = 0
#ifdef IPCONFIG_BOOTP
			| IC_BOOTP
#endif
#ifdef CONFIG_IP_PNP_DHCP
			| IC_USE_DHCP
#endif
#ifdef IPCONFIG_RARP
			| IC_RARP
#endif
			;

static int ic_host_name_set __initdata = 0;	/* Host name set by us? */

__be32 ic_myaddr = NONE;		/* My IP address */
static __be32 ic_netmask = NONE;	/* Netmask for local subnet */
__be32 ic_gateway = NONE;	/* Gateway IP address */

__be32 ic_servaddr = NONE;	/* Boot server IP address */

__be32 root_server_addr = NONE;	/* Address of NFS server */
u8 root_server_path[256] = { 0, };	/* Path to mount as root */

/* Persistent data: */

static int ic_proto_used;			/* Protocol used, if any */
static __be32 ic_nameservers[CONF_NAMESERVERS_MAX]; /* DNS Server IP addresses */
static u8 ic_domain[64];		/* DNS (not NIS) domain name */

/*
 * Private state.
 */

/* Name of user-selected boot device */
static char user_dev_name[IFNAMSIZ] __initdata = { 0, };

/* Protocols supported by available interfaces */
static int ic_proto_have_if __initdata = 0;

#ifdef IPCONFIG_DYNAMIC
static DEFINE_SPINLOCK(ic_recv_lock);
static volatile int ic_got_reply __initdata = 0;    /* Proto(s) that replied */
#endif
#ifdef IPCONFIG_DHCP
static int ic_dhcp_msgtype __initdata = 0;	/* DHCP msg type received */
#endif


/*
 *	Network devices
 */

struct ic_device {
	struct ic_device *next;
	struct net_device *dev;
	unsigned short flags;
	short able;
	__be32 xid;
};

static struct ic_device *ic_first_dev __initdata = NULL;/* List of open device */
static struct net_device *ic_dev __initdata = NULL;	/* Selected device */

static int __init ic_open_devs(void)
{
	struct ic_device *d, **last;
	struct net_device *dev;
	unsigned short oflags;

	last = &ic_first_dev;
	rtnl_lock();

	/* bring loopback device up first */
	for_each_netdev(&init_net, dev) {
		if (!(dev->flags & IFF_LOOPBACK))
			continue;
		if (dev_change_flags(dev, dev->flags | IFF_UP) < 0)
			printk(KERN_ERR "IP-Config: Failed to open %s\n", dev->name);
	}

	for_each_netdev(&init_net, dev) {
		if (dev->flags & IFF_LOOPBACK)
			continue;
		if (user_dev_name[0] ? !strcmp(dev->name, user_dev_name) :
		    (!(dev->flags & IFF_LOOPBACK) &&
		     (dev->flags & (IFF_POINTOPOINT|IFF_BROADCAST)) &&
		     strncmp(dev->name, "dummy", 5))) {
			int able = 0;
			if (dev->mtu >= 364)
				able |= IC_BOOTP;
			else
				printk(KERN_WARNING "DHCP/BOOTP: Ignoring device %s, MTU %d too small", dev->name, dev->mtu);
			if (!(dev->flags & IFF_NOARP))
				able |= IC_RARP;
			able &= ic_proto_enabled;
			if (ic_proto_enabled && !able)
				continue;
			oflags = dev->flags;
			if (dev_change_flags(dev, oflags | IFF_UP) < 0) {
				printk(KERN_ERR "IP-Config: Failed to open %s\n", dev->name);
				continue;
			}
			if (!(d = kmalloc(sizeof(struct ic_device), GFP_KERNEL))) {
				rtnl_unlock();
				return -1;
			}
			d->dev = dev;
			*last = d;
			last = &d->next;
			d->flags = oflags;
			d->able = able;
			if (able & IC_BOOTP)
				get_random_bytes(&d->xid, sizeof(__be32));
			else
				d->xid = 0;
			ic_proto_have_if |= able;
			DBG(("IP-Config: %s UP (able=%d, xid=%08x)\n",
				dev->name, able, d->xid));
		}
	}
	rtnl_unlock();

	*last = NULL;

	if (!ic_first_dev) {
		if (user_dev_name[0])
			printk(KERN_ERR "IP-Config: Device `%s' not found.\n", user_dev_name);
		else
			printk(KERN_ERR "IP-Config: No network devices available.\n");
		return -1;
	}
	return 0;
}

static void __init ic_close_devs(void)
{
	struct ic_device *d, *next;
	struct net_device *dev;

	rtnl_lock();
	next = ic_first_dev;
	while ((d = next)) {
		next = d->next;
		dev = d->dev;
		if (dev != ic_dev) {
			DBG(("IP-Config: Downing %s\n", dev->name));
			dev_change_flags(dev, d->flags);
		}
		kfree(d);
	}
	rtnl_unlock();
}

/*
 *	Interface to various network functions.
 */

static inline void
set_sockaddr(struct sockaddr_in *sin, __be32 addr, __be16 port)
{
	sin->sin_family = AF_INET;
	sin->sin_addr.s_addr = addr;
	sin->sin_port = port;
}

static int __init ic_dev_ioctl(unsigned int cmd, struct ifreq *arg)
{
	int res;

	mm_segment_t oldfs = get_fs();
	set_fs(get_ds());
	res = devinet_ioctl(cmd, (struct ifreq __user *) arg);
	set_fs(oldfs);
	return res;
}

static int __init ic_route_ioctl(unsigned int cmd, struct rtentry *arg)
{
	int res;

	mm_segment_t oldfs = get_fs();
	set_fs(get_ds());
	res = ip_rt_ioctl(cmd, (void __user *) arg);
	set_fs(oldfs);
	return res;
}

/*
 *	Set up interface addresses and routes.
 */

static int __init ic_setup_if(void)
{
	struct ifreq ir;
	struct sockaddr_in *sin = (void *) &ir.ifr_ifru.ifru_addr;
	int err;

	memset(&ir, 0, sizeof(ir));
	strcpy(ir.ifr_ifrn.ifrn_name, ic_dev->name);
	set_sockaddr(sin, ic_myaddr, 0);
	if ((err = ic_dev_ioctl(SIOCSIFADDR, &ir)) < 0) {
		printk(KERN_ERR "IP-Config: Unable to set interface address (%d).\n", err);
		return -1;
	}
	set_sockaddr(sin, ic_netmask, 0);
	if ((err = ic_dev_ioctl(SIOCSIFNETMASK, &ir)) < 0) {
		printk(KERN_ERR "IP-Config: Unable to set interface netmask (%d).\n", err);
		return -1;
	}
	set_sockaddr(sin, ic_myaddr | ~ic_netmask, 0);
	if ((err = ic_dev_ioctl(SIOCSIFBRDADDR, &ir)) < 0) {
		printk(KERN_ERR "IP-Config: Unable to set interface broadcast address (%d).\n", err);
		return -1;
	}
	return 0;
}

static int __init ic_setup_routes(void)
{
	/* No need to setup device routes, only the default route... */

	if (ic_gateway != NONE) {
		struct rtentry rm;
		int err;

		memset(&rm, 0, sizeof(rm));
		if ((ic_gateway ^ ic_myaddr) & ic_netmask) {
			printk(KERN_ERR "IP-Config: Gateway not on directly connected network.\n");
			return -1;
		}
		set_sockaddr((struct sockaddr_in *) &rm.rt_dst, 0, 0);
		set_sockaddr((struct sockaddr_in *) &rm.rt_genmask, 0, 0);
		set_sockaddr((struct sockaddr_in *) &rm.rt_gateway, ic_gateway, 0);
		rm.rt_flags = RTF_UP | RTF_GATEWAY;
		if ((err = ic_route_ioctl(SIOCADDRT, &rm)) < 0) {
			printk(KERN_ERR "IP-Config: Cannot add default route (%d).\n", err);
			return -1;
		}
	}

	return 0;
}

/*
 *	Fill in default values for all missing parameters.
 */

static int __init ic_defaults(void)
{
	/*
	 *	At this point we have no userspace running so need not
	 *	claim locks on system_utsname
	 */

	if (!ic_host_name_set)
		sprintf(init_utsname()->nodename, "%u.%u.%u.%u", NIPQUAD(ic_myaddr));

	if (root_server_addr == NONE)
		root_server_addr = ic_servaddr;

	if (ic_netmask == NONE) {
		if (IN_CLASSA(ntohl(ic_myaddr)))
			ic_netmask = htonl(IN_CLASSA_NET);
		else if (IN_CLASSB(ntohl(ic_myaddr)))
			ic_netmask = htonl(IN_CLASSB_NET);
		else if (IN_CLASSC(ntohl(ic_myaddr)))
			ic_netmask = htonl(IN_CLASSC_NET);
		else {
			printk(KERN_ERR "IP-Config: Unable to guess netmask for address %u.%u.%u.%u\n",
				NIPQUAD(ic_myaddr));
			return -1;
		}
		printk("IP-Config: Guessing netmask %u.%u.%u.%u\n", NIPQUAD(ic_netmask));
	}

	return 0;
}

/*
 *	RARP support.
 */

#ifdef IPCONFIG_RARP

static int ic_rarp_recv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev);

static struct packet_type rarp_packet_type __initdata = {
	.type =	__constant_htons(ETH_P_RARP),
	.func =	ic_rarp_recv,
};

static inline void ic_rarp_init(void)
{
	dev_add_pack(&rarp_packet_type);
}

static inline void ic_rarp_cleanup(void)
{
	dev_remove_pack(&rarp_packet_type);
}

/*
 *  Process received RARP packet.
 */
static int __init
ic_rarp_recv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
{
	struct arphdr *rarp;
	unsigned char *rarp_ptr;
	__be32 sip, tip;
	unsigned char *sha, *tha;		/* s for "source", t for "target" */
	struct ic_device *d;

	if (dev->nd_net != &init_net)
		goto drop;

	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
		return NET_RX_DROP;

	if (!pskb_may_pull(skb, sizeof(struct arphdr)))
		goto drop;

	/* Basic sanity checks can be done without the lock.  */
	rarp = (struct arphdr *)skb_transport_header(skb);

	/* If this test doesn't pass, it's not IP, or we should
	 * ignore it anyway.
	 */
	if (rarp->ar_hln != dev->addr_len || dev->type != ntohs(rarp->ar_hrd))
		goto drop;

	/* If it's not a RARP reply, delete it. */
	if (rarp->ar_op != htons(ARPOP_RREPLY))
		goto drop;

	/* If it's not Ethernet, delete it. */
	if (rarp->ar_pro != htons(ETH_P_IP))
		goto drop;

	if (!pskb_may_pull(skb,
			   sizeof(struct arphdr) +
			   (2 * dev->addr_len) +
			   (2 * 4)))
		goto drop;

	/* OK, it is all there and looks valid, process... */
	rarp = (struct arphdr *)skb_transport_header(skb);
	rarp_ptr = (unsigned char *) (rarp + 1);

	/* One reply at a time, please. */
	spin_lock(&ic_recv_lock);

	/* If we already have a reply, just drop the packet */
	if (ic_got_reply)
		goto drop_unlock;

	/* Find the ic_device that the packet arrived on */
	d = ic_first_dev;
	while (d && d->dev != dev)
		d = d->next;
	if (!d)
		goto drop_unlock;	/* should never happen */

	/* Extract variable-width fields */
	sha = rarp_ptr;
	rarp_ptr += dev->addr_len;
	memcpy(&sip, rarp_ptr, 4);
	rarp_ptr += 4;
	tha = rarp_ptr;
	rarp_ptr += dev->addr_len;
	memcpy(&tip, rarp_ptr, 4);

	/* Discard packets which are not meant for us. */
	if (memcmp(tha, dev->dev_addr, dev->addr_len))
		goto drop_unlock;

	/* Discard packets which are not from specified server. */
	if (ic_servaddr != NONE && ic_servaddr != sip)
		goto drop_unlock;

	/* We have a winner! */
	ic_dev = dev;
	if (ic_myaddr == NONE)
		ic_myaddr = tip;
	ic_servaddr = sip;
	ic_got_reply = IC_RARP;