nfsroot.c

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/*
 *  linux/fs/nfs/nfsroot.c -- version 2.3
 *
 *  Copyright (C) 1995, 1996  Gero Kuhlmann <[e-mail]>
 *
 *  For parts of this file:
 *  Copyright (C) 1996  Martin Mares <[e-mail]>
 *
 *  Allow an NFS filesystem to be mounted as root. The way this works is:
 *     (1) Determine the local IP address via RARP or BOOTP or from the
 *         kernel command line.
 *     (2) Handle RPC negotiation with the system which replied to RARP or
 *         was reported as a boot server by BOOTP or manually.
 *     (3) The actual mounting is done later, when init() is running.
 *
 *
 *	Changes:
 *
 *	Alan Cox	:	Removed get_address name clash with FPU.
 *	Alan Cox	:	Reformatted a bit.
 *	Gero Kuhlmann	:	Code cleanup
 *	Michael Rausch  :	Fixed recognition of an incoming RARP answer.
 *	Martin Mares	: (2.0)	Auto-configuration via BOOTP supported.
 *	Martin Mares	:	Manual selection of interface & BOOTP/RARP.
 *	Martin Mares	:	Using network routes instead of host routes,
 *				allowing the default configuration to be used
 *				for normal operation of the host.
 *	Martin Mares	:	Randomized timer with exponential backoff
 *				installed to minimize network congestion.
 *	Martin Mares	:	Code cleanup.
 *	Martin Mares	: (2.1)	BOOTP and RARP made configuration options.
 *	Martin Mares	:	Server hostname generation fixed.
 *	Gerd Knorr	:	Fixed wired inode handling
 *	Martin Mares	: (2.2)	"0.0.0.0" addresses from command line ignored.
 *	Martin Mares	:	RARP replies not tested for server address.
 *	Gero Kuhlmann	: (2.3) Some bug fixes and code cleanup again (please
 *				send me your new patches _before_ bothering
 *				Linus so that I don' always have to cleanup
 *				_afterwards_ - thanks)
 *	Gero Kuhlmann	:	Last changes of Martin Mares undone.
 *	Gero Kuhlmann	: 	RARP replies are tested for specified server
 *				again. However, it's now possible to have
 *				different RARP and NFS servers.
 *	Gero Kuhlmann	:	"0.0.0.0" addresses from command line are
 *				now mapped to INADDR_NONE.
 *	Gero Kuhlmann	:	Fixed a bug which prevented BOOTP path name
 *				from being used (thanks to Leo Spiekman)
 *	Andy Walker	:	Allow to specify the NFS server in nfs_root
 *				without giving a path name
 *	Swen Th=FCmmler	:	Allow to specify the NFS options in nfs_root
 *				without giving a path name. Fix BOOTP request
 *				for domainname (domainname is NIS domain, not
 *				DNS domain!). Skip dummy devices for BOOTP.
 *	Jacek Zapala	:	Fixed a bug which prevented server-ip address
 *				from nfsroot parameter from being used.
 *
 */


/* Define this to allow debugging output */
#undef NFSROOT_DEBUG
#undef NFSROOT_BOOTP_DEBUG


#include <linux/config.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/random.h>
#include <linux/fcntl.h>

#include <asm/param.h>
#include <linux/utsname.h>
#include <linux/in.h>
#include <linux/if.h>
#include <linux/inet.h>
#include <linux/net.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#ifdef CONFIG_AX25
#include <net/ax25.h>	/* For AX25_P_IP */
#endif
#include <linux/skbuff.h>
#include <linux/socket.h>
#include <linux/route.h>
#include <linux/nfs.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_mount.h>
#include <linux/in.h>
#include <net/route.h>
#include <net/sock.h>

#include <asm/segment.h>

/* Range of privileged ports */
#define STARTPORT	600
#define ENDPORT		1023
#define NPORTS		(ENDPORT - STARTPORT + 1)


/* Define the timeout for waiting for a RARP/BOOTP reply */
#define CONF_BASE_TIMEOUT	(HZ*5)	/* Initial timeout: 5 seconds */
#define CONF_RETRIES	 	10	/* 10 retries */
#define CONF_TIMEOUT_RANDOM	(HZ)	/* Maximum amount of randomization */
#define CONF_TIMEOUT_MULT	*5/4	/* Speed of timeout growth */
#define CONF_TIMEOUT_MAX	(HZ*30)	/* Maximum allowed timeout */


/* List of open devices */
struct open_dev {
	struct device *dev;
	unsigned short old_flags;
	struct open_dev *next;
};

static struct open_dev *open_base = NULL;


/* IP configuration */
static struct device *root_dev = NULL;	/* Device selected for booting */
static char user_dev_name[IFNAMSIZ];	/* Name of user-selected boot device */
static struct sockaddr_in myaddr;	/* My IP address */
static struct sockaddr_in server;	/* Server IP address */
static struct sockaddr_in gateway;	/* Gateway IP address */
static struct sockaddr_in netmask;	/* Netmask for local subnet */


/* BOOTP/RARP variables */
static int bootp_flag;			/* User said: Use BOOTP! */
static int rarp_flag;			/* User said: Use RARP! */
static int bootp_dev_count = 0;		/* Number of devices allowing BOOTP */
static int rarp_dev_count = 0;		/* Number of devices allowing RARP */
static struct sockaddr_in rarp_serv;	/* IP address of RARP server */

#if defined(CONFIG_RNFS_BOOTP) || defined(CONFIG_RNFS_RARP)
#define CONFIG_RNFS_DYNAMIC		/* Enable dynamic IP config */
static volatile int pkt_arrived;	/* BOOTP/RARP packet detected */

#define ARRIVED_BOOTP	1
#define ARRIVED_RARP	2
#endif


/* NFS-related data */
static struct nfs_mount_data nfs_data;		/* NFS mount info */
static char nfs_path[NFS_MAXPATHLEN] = "";	/* Name of directory to mount */
static int nfs_port;				/* Port to connect to for NFS */


/* Yes, we use sys_socket, but there's no include file for it */
extern asmlinkage int sys_socket(int family, int type, int protocol);



/***************************************************************************

			Device Handling Subroutines

 ***************************************************************************/

/*
 * Setup and initialize all network devices. If there is a user-preferred
 * interface, ignore all other interfaces.
 */
static int root_dev_open(void)
{
	struct open_dev *openp, **last;
	struct device *dev;
	unsigned short old_flags;

	last = &open_base;
	for (dev = dev_base; dev != NULL; dev = dev->next) {
		if (dev->type < ARPHRD_SLIP &&
		    dev->family == AF_INET &&
		    !(dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT)) &&
		    (0 != strncmp(dev->name, "dummy", 5)) &&
		    (!user_dev_name[0] || !strcmp(dev->name, user_dev_name))) {
			/* First up the interface */
			old_flags = dev->flags;
			dev->flags = IFF_UP | IFF_BROADCAST | IFF_RUNNING;
			if (!(old_flags & IFF_UP) && dev_open(dev)) {
				dev->flags = old_flags;
				continue;
			}
			openp = (struct open_dev *) kmalloc(sizeof(struct open_dev),
						GFP_ATOMIC);
			if (openp == NULL)
				continue;
			openp->dev = dev;
			openp->old_flags = old_flags;
			*last = openp;
			last = &openp->next;
			bootp_dev_count++;
			if (!(dev->flags & IFF_NOARP))
				rarp_dev_count++;
#ifdef NFSROOT_DEBUG
			printk(KERN_NOTICE "Root-NFS: Opened %s\n", dev->name);
#endif
		}
	}
	*last = NULL;

	if (!bootp_dev_count && !rarp_dev_count) {
		printk(KERN_ERR "Root-NFS: Unable to open at least one network device\n");
		return -1;
	}
	return 0;
}


/*
 *  Restore the state of all devices. However, keep the root device open
 *  for the upcoming mount.
 */
static void root_dev_close(void)
{
	struct open_dev *openp;
	struct open_dev *nextp;

	openp = open_base;
	while (openp != NULL) {
		nextp = openp->next;
		openp->next = NULL;
		if (openp->dev != root_dev) {
			if (!(openp->old_flags & IFF_UP))
				dev_close(openp->dev);
			openp->dev->flags = openp->old_flags;
		}
		kfree_s(openp, sizeof(struct open_dev));
		openp = nextp;
	}
}



/***************************************************************************

			      RARP Subroutines

 ***************************************************************************/

#ifdef CONFIG_RNFS_RARP

extern void arp_send(int type, int ptype, unsigned long target_ip,
		     struct device *dev, unsigned long src_ip,
		     unsigned char *dest_hw, unsigned char *src_hw,
		     unsigned char *target_hw);

static int root_rarp_recv(struct sk_buff *skb, struct device *dev,
			  struct packet_type *pt);


static struct packet_type rarp_packet_type = {
	0,			/* Should be: __constant_htons(ETH_P_RARP)
				 * - but this _doesn't_ come out constant! */
	NULL,			/* Listen to all devices */
	root_rarp_recv,
	NULL,
	NULL
};


/*
 *  Register the packet type for RARP
 */
static void root_rarp_open(void)
{
	rarp_packet_type.type = htons(ETH_P_RARP);
	dev_add_pack(&rarp_packet_type);
}


/*
 *  Deregister the RARP packet type
 */
static void root_rarp_close(void)
{
	rarp_packet_type.type = htons(ETH_P_RARP);
	dev_remove_pack(&rarp_packet_type);
}


/*
 *  Receive RARP packets.
 */
static int root_rarp_recv(struct sk_buff *skb, struct device *dev, struct packet_type *pt)
{
	struct arphdr *rarp = (struct arphdr *)skb->h.raw;
	unsigned char *rarp_ptr = (unsigned char *) (rarp + 1);
	unsigned long sip, tip;
	unsigned char *sha, *tha;		/* s for "source", t for "target" */

	/* 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)) {
		kfree_skb(skb, FREE_READ);
		return 0;
	}

	/* If it's not a RARP reply, delete it. */
	if (rarp->ar_op != htons(ARPOP_RREPLY)) {
		kfree_skb(skb, FREE_READ);
		return 0;
	}

	/* If it's not ethernet or AX25, delete it. */
	if ((rarp->ar_pro != htons(ETH_P_IP) && dev->type != ARPHRD_AX25) ||
#ifdef CONFIG_AX25
	   (rarp->ar_pro != htons(AX25_P_IP) && dev->type == ARPHRD_AX25) ||
#endif
	    rarp->ar_pln != 4) {
		kfree_skb(skb, FREE_READ);
		return 0;
	}

	/* 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)) {
		kfree_skb(skb, FREE_READ);
		return 0;
	}
	/* Discard packets which are not from specified server. */
	if (rarp_flag && !bootp_flag &&
	    rarp_serv.sin_addr.s_addr != INADDR_NONE &&
	    rarp_serv.sin_addr.s_addr != sip) {
		kfree_skb(skb, FREE_READ);
		return 0;
	}

	/*
	 * The packet is what we were looking for. Setup the global
	 * variables.
	 */
	cli();
	if (pkt_arrived) {
		sti();
		kfree_skb(skb, FREE_READ);
		return 0;
	}
	pkt_arrived = ARRIVED_RARP;
	sti();
	root_dev = dev;

	if (myaddr.sin_addr.s_addr == INADDR_NONE) {
		myaddr.sin_family = dev->family;
		myaddr.sin_addr.s_addr = tip;
	}
	if (server.sin_addr.s_addr == INADDR_NONE) {
		server.sin_family = dev->family;
		server.sin_addr.s_addr = sip;
	}
	kfree_skb(skb, FREE_READ);
	return 0;
}


/*
 *  Send RARP request packet over all devices which allow RARP.
 */
static void root_rarp_send(void)
{
	struct open_dev *openp;
	struct device *dev;
	int num = 0;

	for (openp = open_base; openp != NULL; openp = openp->next) {
		dev = openp->dev;
		if (!(dev->flags & IFF_NOARP)) {
			arp_send(ARPOP_RREQUEST, ETH_P_RARP, 0, dev, 0, NULL,
				 dev->dev_addr, dev->dev_addr);
			num++;
		}
	}
}
#endif



/***************************************************************************

			     BOOTP Subroutines

 ***************************************************************************/

#ifdef CONFIG_RNFS_BOOTP

static struct device *bootp_dev = NULL;	/* Device selected as best BOOTP target */

static int bootp_xmit_fd = -1;		/* Socket descriptor for transmit */
static struct socket *bootp_xmit_sock;	/* The socket itself */
static int bootp_recv_fd = -1;		/* Socket descriptor for receive */
static struct socket *bootp_recv_sock;	/* The socket itself */

struct bootp_pkt {		/* BOOTP packet format */
	u8 op;			/* 1=request, 2=reply */
	u8 htype;		/* HW address type */
	u8 hlen;		/* HW address length */
	u8 hops;		/* Used only by gateways */
	u32 xid;		/* Transaction ID */
	u16 secs;		/* Seconds since we started */
	u16 flags;		/* Just what is says */
	u32 client_ip;		/* Client's IP address if known */
	u32 your_ip;		/* Assigned IP address */
	u32 server_ip;		/* Server's IP address */
	u32 relay_ip;		/* IP address of BOOTP relay */
	u8 hw_addr[16];		/* Client's HW address */
	u8 serv_name[64];	/* Server host name */
	u8 boot_file[128];	/* Name of boot file */
	u8 vendor_area[128];	/* Area for extensions */
};

#define BOOTP_REQUEST 1
#define BOOTP_REPLY 2

static struct bootp_pkt *xmit_bootp;	/* Packet being transmitted */
static struct bootp_pkt *recv_bootp;	/* Packet being received */

static int bootp_have_route = 0;	/* BOOTP route installed */


/*
 *  Free BOOTP packet buffers
 */
static void root_free_bootp(void)
{
	if (xmit_bootp) {
		kfree_s(xmit_bootp, sizeof(struct bootp_pkt));
		xmit_bootp = NULL;
	}
	if (recv_bootp) {
		kfree_s(recv_bootp, sizeof(struct bootp_pkt));
		recv_bootp = NULL;
	}
}


/*
 *  Allocate memory for BOOTP packet buffers
 */
static inline int root_alloc_bootp(void)
{
	if (!(xmit_bootp = kmalloc(sizeof(struct bootp_pkt), GFP_KERNEL)) ||
	    !(recv_bootp = kmalloc(sizeof(struct bootp_pkt), GFP_KERNEL))) {
		printk("BOOTP: Out of memory!");
		return -1;
	}
	return 0;
}


/*
 *  Create default route for BOOTP sending
 */
static int root_add_bootp_route(void)
{
	struct rtentry route;

	memset(&route, 0, sizeof(route));
	route.rt_dev = bootp_dev->name;
	route.rt_mss = bootp_dev->mtu;
	route.rt_flags = RTF_UP;
	((struct sockaddr_in *) &(route.rt_dst)) -> sin_addr.s_addr = 0;
	((struct sockaddr_in *) &(route.rt_dst)) -> sin_family = AF_INET;
	((struct sockaddr_in *) &(route.rt_genmask)) -> sin_addr.s_addr = 0;
	((struct sockaddr_in *) &(route.rt_genmask)) -> sin_family = AF_INET;
	if (ip_rt_new(&route)) {
		printk(KERN_ERR "BOOTP: Adding of route failed!\n");
		return -1;
	}
	bootp_have_route = 1;
	return 0;
}


/*
 *  Delete default route for BOOTP sending
 */
static int root_del_bootp_route(void)
{
	struct rtentry route;

	if (!bootp_have_route)
		return 0;
	memset(&route, 0, sizeof(route));
	((struct sockaddr_in *) &(route.rt_dst)) -> sin_addr.s_addr = 0;
	((struct sockaddr_in *) &(route.rt_genmask)) -> sin_addr.s_addr = 0;
	if (ip_rt_kill(&route)) {
		printk(KERN_ERR "BOOTP: Deleting of route failed!\n");
		return -1;
	}
	bootp_have_route = 0;
	return 0;
}


/*
 *  Open UDP socket.
 */
static int root_open_udp_sock(int *fd, struct socket **sock)
{
	struct file *file;
	struct inode *inode;

	*fd = sys_socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
	if (*fd >= 0) {
		file = current->files->fd[*fd];
		inode = file->f_inode;
		*sock = &inode->u.socket_i;
		return 0;
	}

	printk(KERN_ERR "BOOTP: Cannot open UDP socket!\n");
	return -1;
}


/*
 *  Connect UDP socket.
 */
static int root_connect_udp_sock(struct socket *sock, u32 addr, u16 port)
{
	struct sockaddr_in sa;
	int result;

	sa.sin_family = AF_INET;
	sa.sin_addr.s_addr = htonl(addr);
	sa.sin_port = htons(port);
	result = sock->ops->connect(sock, (struct sockaddr *) &sa, sizeof(sa), 0);
	if (result < 0) {
		printk(KERN_ERR "BOOTP: connect() failed\n");
		return -1;
	}
	return 0;
}


/*
 *  Bind UDP socket.
 */
static int root_bind_udp_sock(struct socket *sock, u32 addr, u16 port)
{
	struct sockaddr_in sa;
	int result;

	sa.sin_family = AF_INET;
	sa.sin_addr.s_addr = htonl(addr);
	sa.sin_port = htons(port);
	result = sock->ops->bind(sock, (struct sockaddr *) &sa, sizeof(sa));
	if (result < 0) {
		printk(KERN_ERR "BOOTP: bind() failed\n");
		return -1;
	}
	return 0;
}


/*
 *  Send UDP packet.
 */
static inline int root_send_udp(struct socket *sock, void *buf, int size)
{
	u32 oldfs;
	int result;
	struct msghdr msg;
	struct iovec iov;