linux/fs/nfs/nfsroot.c

/*
 *  Copyright (C) 1995, 1996  Gero Kuhlmann <gero@gkminix.han.de>
 *
 *  Allow an NFS filesystem to be mounted as root. The way this works is:
 *     (1) Use the IP autoconfig mechanism to set local IP addresses and routes.
 *     (2) Construct the device string and the options string using DHCP
 *         option 17 and/or kernel command line options.
 *     (3) When mount_root() sets up the root file system, pass these strings
 *         to the NFS client's regular mount interface via sys_mount().
 *
 *
 *	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 Thümmler	:	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.
 *	Olaf Kirch	:	Adapted to new NFS code.
 *	Jakub Jelinek	:	Free used code segment.
 *	Marko Kohtala	:	Fixed some bugs.
 *	Martin Mares	:	Debug message cleanup
 *	Martin Mares	:	Changed to use the new generic IP layer autoconfig
 *				code. BOOTP and RARP moved there.
 *	Martin Mares	:	Default path now contains host name instead of
 *				host IP address (but host name defaults to IP
 *				address anyway).
 *	Martin Mares	:	Use root_server_addr appropriately during setup.
 *	Martin Mares	:	Rewrote parameter parsing, now hopefully giving
 *				correct overriding.
 *	Trond Myklebust :	Add in preliminary support for NFSv3 and TCP.
 *				Fix bug in root_nfs_addr(). nfs_data.namlen
 *				is NOT for the length of the hostname.
 *	Hua Qin		:	Support for mounting root file system via
 *				NFS over TCP.
 *	Fabian Frederick:	Option parser rebuilt (using parser lib)
 *	Chuck Lever	:	Use super.c's text-based mount option parsing
 */

#include <linux/types.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/time.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/xprtsock.h>
#include <linux/nfs.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_mount.h>
#include <linux/in.h>
#include <linux/major.h>
#include <linux/utsname.h>
#include <linux/inet.h>
#include <linux/root_dev.h>
#include <net/ipconfig.h>
#include <linux/parser.h>

#include "internal.h"

/* Define this to allow debugging output */
#undef NFSROOT_DEBUG
#define NFSDBG_FACILITY NFSDBG_ROOT

/* Default port to use if server is not running a portmapper */
#define NFS_MNT_PORT	627

/* Default path we try to mount. "%s" gets replaced by our IP address */
#define NFS_ROOT		"/tftpboot/%s"

/* Parameters passed from the kernel command line */
static char nfs_root_parms[256] __initdata = "";

/* Text-based mount options passed to super.c */
static char nfs_root_options[256] __initdata = "";

/* Address of NFS server */
static __be32 servaddr __initdata = 0;

/* Name of directory to mount */
static char nfs_export_path[NFS_MAXPATHLEN + 1] __initdata = "";

/* server:export path string passed to super.c */
static char nfs_root_device[NFS_MAXPATHLEN + 1] __initdata = "";

/* NFS-related data */
static struct nfs_mount_data nfs_data __initdata = { 0, };/* NFS mount info */
static int nfs_port __initdata = 0;		/* Port to connect to for NFS */
static int mount_port __initdata = 0;		/* Mount daemon port number */


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

			     Parsing of options

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

enum {
	/* Options that take integer arguments */
	Opt_port, Opt_rsize, Opt_wsize, Opt_timeo, Opt_retrans, Opt_acregmin,
	Opt_acregmax, Opt_acdirmin, Opt_acdirmax,
	/* Options that take no arguments */
	Opt_soft, Opt_hard, Opt_intr,
	Opt_nointr, Opt_posix, Opt_noposix, Opt_cto, Opt_nocto, Opt_ac, 
	Opt_noac, Opt_lock, Opt_nolock, Opt_v2, Opt_v3, Opt_udp, Opt_tcp,
	Opt_acl, Opt_noacl,
	/* Error token */
	Opt_err
};

static const match_table_t tokens __initconst = {
	{Opt_port, "port=%u"},
	{Opt_rsize, "rsize=%u"},
	{Opt_wsize, "wsize=%u"},
	{Opt_timeo, "timeo=%u"},
	{Opt_retrans, "retrans=%u"},
	{Opt_acregmin, "acregmin=%u"},
	{Opt_acregmax, "acregmax=%u"},
	{Opt_acdirmin, "acdirmin=%u"},
	{Opt_acdirmax, "acdirmax=%u"},
	{Opt_soft, "soft"},
	{Opt_hard, "hard"},
	{Opt_intr, "intr"},
	{Opt_nointr, "nointr"},
	{Opt_posix, "posix"},
	{Opt_noposix, "noposix"},
	{Opt_cto, "cto"},
	{Opt_nocto, "nocto"},
	{Opt_ac, "ac"},
	{Opt_noac, "noac"},
	{Opt_lock, "lock"},
	{Opt_nolock, "nolock"},
	{Opt_v2, "nfsvers=2"},
	{Opt_v2, "v2"},
	{Opt_v3, "nfsvers=3"},
	{Opt_v3, "v3"},
	{Opt_udp, "proto=udp"},
	{Opt_udp, "udp"},
	{Opt_tcp, "proto=tcp"},
	{Opt_tcp, "tcp"},
	{Opt_acl, "acl"},
	{Opt_noacl, "noacl"},
	{Opt_err, NULL}
	
};

/*
 *  Parse option string.
 */

static int __init root_nfs_parse(char *name, char *buf)
{

	char *p;
	substring_t args[MAX_OPT_ARGS];
	int option;

	if (!name)
		return 1;

	/* Set the NFS remote path */
	p = strsep(&name, ",");
	if (p[0] != '\0' && strcmp(p, "default") != 0)
		strlcpy(buf, p, NFS_MAXPATHLEN);

	while ((p = strsep (&name, ",")) != NULL) {
		int token; 
		if (!*p)
			continue;
		token = match_token(p, tokens, args);

		/* %u tokens only. Beware if you add new tokens! */
		if (token < Opt_soft && match_int(&args[0], &option))
			return 0;
		switch (token) {
			case Opt_port:
				nfs_port = option;
				break;
			case Opt_rsize:
				nfs_data.rsize = option;
				break;
			case Opt_wsize:
				nfs_data.wsize = option;
				break;
			case Opt_timeo:
				nfs_data.timeo = option;
				break;
			case Opt_retrans:
				nfs_data.retrans = option;
				break;
			case Opt_acregmin:
				nfs_data.acregmin = option;
				break;
			case Opt_acregmax:
				nfs_data.acregmax = option;
				break;
			case Opt_acdirmin:
				nfs_data.acdirmin = option;
				break;
			case Opt_acdirmax:
				nfs_data.acdirmax = option;
				break;
			case Opt_soft:
				nfs_data.flags |= NFS_MOUNT_SOFT;
				break;
			case Opt_hard:
				nfs_data.flags &= ~NFS_MOUNT_SOFT;
				break;
			case Opt_intr:
			case Opt_nointr:
				break;
			case Opt_posix:
				nfs_data.flags |= NFS_MOUNT_POSIX;
				break;
			case Opt_noposix:
				nfs_data.flags &= ~NFS_MOUNT_POSIX;
				break;
			case Opt_cto:
				nfs_data.flags &= ~NFS_MOUNT_NOCTO;
				break;
			case Opt_nocto:
				nfs_data.flags |= NFS_MOUNT_NOCTO;
				break;
			case Opt_ac:
				nfs_data.flags &= ~NFS_MOUNT_NOAC;
				break;
			case Opt_noac:
				nfs_data.flags |= NFS_MOUNT_NOAC;
				break;
			case Opt_lock:
				nfs_data.flags &= ~NFS_MOUNT_NONLM;
				break;
			case Opt_nolock:
				nfs_data.flags |= NFS_MOUNT_NONLM;
				break;
			case Opt_v2:
				nfs_data.flags &= ~NFS_MOUNT_VER3;
				break;
			case Opt_v3:
				nfs_data.flags |= NFS_MOUNT_VER3;
				break;
			case Opt_udp:
				nfs_data.flags &= ~NFS_MOUNT_TCP;
				break;
			case Opt_tcp:
				nfs_data.flags |= NFS_MOUNT_TCP;
				break;
			case Opt_acl:
				nfs_data.flags &= ~NFS_MOUNT_NOACL;
				break;
			case Opt_noacl:
				nfs_data.flags |= NFS_MOUNT_NOACL;
				break;
			default:
				printk(KERN_WARNING "Root-NFS: unknown "
					"option: %s\n", p);
				return 0;
		}
	}

	return 1;
}

/*
 *  Prepare the NFS data structure and parse all options.
 */
static int __init root_nfs_name(char *name)
{
	static char buf[NFS_MAXPATHLEN] __initdata;
	char *cp;

	/* Set some default values */
	memset(&nfs_data, 0, sizeof(nfs_data));
	nfs_port          = -1;
	nfs_data.version  = NFS_MOUNT_VERSION;
	nfs_data.flags    = NFS_MOUNT_NONLM;	/* No lockd in nfs root yet */
	nfs_data.rsize    = NFS_DEF_FILE_IO_SIZE;
	nfs_data.wsize    = NFS_DEF_FILE_IO_SIZE;
	nfs_data.acregmin = NFS_DEF_ACREGMIN;
	nfs_data.acregmax = NFS_DEF_ACREGMAX;
	nfs_data.acdirmin = NFS_DEF_ACDIRMIN;
	nfs_data.acdirmax = NFS_DEF_ACDIRMAX;
	strcpy(buf, NFS_ROOT);

	/* Process options received from the remote server */
	root_nfs_parse(root_server_path, buf);

	/* Override them by options set on kernel command-line */
	root_nfs_parse(name, buf);

	cp = utsname()->nodename;
	if (strlen(buf) + strlen(cp) > NFS_MAXPATHLEN) {
		printk(KERN_ERR "Root-NFS: Pathname for remote directory too long.\n");
		return -1;
	}
	sprintf(nfs_export_path, buf, cp);

	return 1;
}


/*
 *  Get NFS server address.
 */
static int __init root_nfs_addr(void)
{
	if ((servaddr = root_server_addr) == htonl(INADDR_NONE)) {
		printk(KERN_ERR "Root-NFS: No NFS server available, giving up.\n");
		return -1;
	}

	snprintf(nfs_data.hostname, sizeof(nfs_data.hostname),
		 "%pI4", &servaddr);
	return 0;
}

/*
 *  Tell the user what's going on.
 */
#ifdef NFSROOT_DEBUG
static void __init root_nfs_print(void)
{
	printk(KERN_NOTICE "Root-NFS: Mounting %s on server %s as root\n",
		nfs_export_path, nfs_data.hostname);
	printk(KERN_NOTICE "Root-NFS:     rsize = %d, wsize = %d, timeo = %d, retrans = %d\n",
		nfs_data.rsize, nfs_data.wsize, nfs_data.timeo, nfs_data.retrans);
	printk(KERN_NOTICE "Root-NFS:     acreg (min,max) = (%d,%d), acdir (min,max) = (%d,%d)\n",
		nfs_data.acregmin, nfs_data.acregmax,
		nfs_data.acdirmin, nfs_data.acdirmax);
	printk(KERN_NOTICE "Root-NFS:     nfsd port = %d, mountd port = %d, flags = %08x\n",
		nfs_port, mount_port, nfs_data.flags);
}
#endif


static int __init root_nfs_init(void)
{
#ifdef NFSROOT_DEBUG
	nfs_debug |= NFSDBG_ROOT;
#endif

	/*
	 * Decode the root directory path name and NFS options from
	 * the kernel command line. This has to go here in order to
	 * be able to use the client IP address for the remote root
	 * directory (necessary for pure RARP booting).
	 */
	if (root_nfs_name(nfs_root_parms) < 0 ||
	    root_nfs_addr() < 0)
		return -1;

#ifdef NFSROOT_DEBUG
	root_nfs_print();
#endif

	return 0;
}

/*
 *  Parse NFS server and directory information passed on the kernel
 *  command line.
 *
 *  nfsroot=[<server-ip>:]<root-dir>[,<nfs-options>]
 *
 *  If there is a "%s" token in the <root-dir> string, it is replaced
 *  by the ASCII-representation of the client's IP address.
 */
static int __init nfs_root_setup(char *line)
{
	ROOT_DEV = Root_NFS;

	if (line[0] == '/' || line[0] == ',' || (line[0] >= '0' && line[0] <= '9')) {
		strlcpy(nfs_root_parms, line, sizeof(nfs_root_parms));
	} else {
		size_t n = strlen(line) + sizeof(NFS_ROOT) - 1;
		if (n >= sizeof(nfs_root_parms))
			line[sizeof(nfs_root_parms) - sizeof(NFS_ROOT) - 2] = '\0';
		sprintf(nfs_root_parms, NFS_ROOT, line);
	}

	/*
	 * Extract the IP address of the NFS server containing our
	 * root file system, if one was specified.
	 *
	 * Note: root_nfs_parse_addr() removes the server-ip from
	 *	 nfs_root_parms, if it exists.
	 */
	root_server_addr = root_nfs_parse_addr(nfs_root_parms);

	return 1;
}

__setup("nfsroot=", nfs_root_setup);

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

	       Routines to actually mount the root directory

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

/*
 *  Construct sockaddr_in from address and port number.
 */
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;
}

/*
 *  Query server portmapper for the port of a daemon program.
 */
static int __init root_nfs_getport(int program, int version, int proto)
{
	struct sockaddr_in sin;

	printk(KERN_NOTICE "Looking up port of RPC %d/%d on %pI4\n",
		program, version, &servaddr);
	set_sockaddr(&sin, servaddr, 0);
	return rpcb_getport_sync(&sin, program, version, proto);
}


/*
 *  Use portmapper to find mountd and nfsd port numbers if not overriden
 *  by the user. Use defaults if portmapper is not available.
 *  XXX: Is there any nfs server with no portmapper?
 */
static int __init root_nfs_ports(void)
{
	int port;
	int nfsd_ver, mountd_ver;
	int nfsd_port, mountd_port;
	int proto;

	if (nfs_data.flags & NFS_MOUNT_VER3) {
		nfsd_ver = NFS3_VERSION;
		mountd_ver = NFS_MNT3_VERSION;
		nfsd_port = NFS_PORT;
		mountd_port = NFS_MNT_PORT;
	} else {
		nfsd_ver = NFS2_VERSION;
		mountd_ver = NFS_MNT_VERSION;
		nfsd_port = NFS_PORT;
		mountd_port = NFS_MNT_PORT;
	}

	proto = (nfs_data.flags & NFS_MOUNT_TCP) ? IPPROTO_TCP : IPPROTO_UDP;

	if (nfs_port < 0) {
		if ((port = root_nfs_getport(NFS_PROGRAM, nfsd_ver, proto)) < 0) {
			printk(KERN_ERR "Root-NFS: Unable to get nfsd port "
					"number from server, using default\n");
			port = nfsd_port;
		}
		nfs_port = port;
		dprintk("Root-NFS: Portmapper on server returned %d "
			"as nfsd port\n", port);
	}

	if ((port = root_nfs_getport(NFS_MNT_PROGRAM, mountd_ver, proto)) < 0) {
		printk(KERN_ERR "Root-NFS: Unable to get mountd port "
				"number from server, using default\n");
		port = mountd_port;
	}
	mount_port = port;
	dprintk("Root-NFS: mountd port is %d\n", port);

	return 0;
}


/*
 *  Get a file handle from the server for the directory which is to be
 *  mounted.
 */
static int __init root_nfs_get_handle(void)
{
	struct sockaddr_in sin;
	unsigned int auth_flav_len = 0;
	struct nfs_mount_request request = {
		.sap		= (struct sockaddr *)&sin,
		.salen		= sizeof(sin),
		.dirpath	= nfs_export_path,
		.version	= (nfs_data.flags & NFS_MOUNT_VER3) ?
					NFS_MNT3_VERSION : NFS_MNT_VERSION,
		.protocol	= (nfs_data.flags & NFS_MOUNT_TCP) ?
					XPRT_TRANSPORT_TCP : XPRT_TRANSPORT_UDP,
		.auth_flav_len	= &auth_flav_len,
	};
	int status = -ENOMEM;

	request.fh = nfs_alloc_fhandle();
	if (!request.fh)
		goto out;
	set_sockaddr(&sin, servaddr, htons(mount_port));
	status = nfs_mount(&request);
	if (status < 0)
		printk(KERN_ERR "Root-NFS: Server returned error %d "
				"while mounting %s\n", status, nfs_export_path);
	else {
		nfs_data.root.size = request.fh->size;
		memcpy(&nfs_data.root.data, request.fh->data, request.fh->size);
	}
	nfs_free_fhandle(request.fh);
out:
	return status;
}

/*
 *  Get the NFS port numbers and file handle, and return the prepared 'data'
 *  argument for mount() if everything went OK. Return NULL otherwise.
 */
void * __init old_nfs_root_data(void)
{
	if (root_nfs_init() < 0
	 || root_nfs_ports() < 0
	 || root_nfs_get_handle() < 0)
		return NULL;
	set_sockaddr((struct sockaddr_in *) &nfs_data.addr, servaddr, htons(nfs_port));
	return (void*)&nfs_data;
}

static int __init root_nfs_copy(char *dest, const char *src,
				     const size_t destlen)
{
	if (strlcpy(dest, src, destlen) > destlen)
		return -1;
	return 0;
}

static int __init root_nfs_cat(char *dest, const char *src,
				  const size_t destlen)
{
	if (strlcat(dest, src, destlen) > destlen)
		return -1;
	return 0;
}

/*
 * Parse out root export path and mount options from
 * passed-in string @incoming.
 *
 * Copy the export path into @exppath.
 */
static int __init root_nfs_parse_options(char *incoming, char *exppath,
					 const size_t exppathlen)
{
	char *p;

	/*
	 * Set the NFS remote path
	 */
	p = strsep(&incoming, ",");
	if (*p != '\0' && strcmp(p, "default") != 0)
		if (root_nfs_copy(exppath, p, exppathlen))
			return -1;

	/*
	 * @incoming now points to the rest of the string; if it
	 * contains something, append it to our root options buffer
	 */
	if (incoming != NULL && *incoming != '\0')
		if (root_nfs_cat(nfs_root_options, incoming,
						sizeof(nfs_root_options)))
			return -1;

	/*
	 * Possibly prepare for more options to be appended
	 */
	if (nfs_root_options[0] != '\0' &&
	    nfs_root_options[strlen(nfs_root_options)] != ',')
		if (root_nfs_cat(nfs_root_options, ",",
						sizeof(nfs_root_options)))
			return -1;

	return 0;
}

/*
 *  Decode the export directory path name and NFS options from
 *  the kernel command line.  This has to be done late in order to
 *  use a dynamically acquired client IP address for the remote
 *  root directory path.
 *
 *  Returns zero if successful; otherwise -1 is returned.
 */
static int __init root_nfs_data(char *cmdline)
{
	char addr_option[sizeof("nolock,addr=") + INET_ADDRSTRLEN + 1];
	int len, retval = -1;
	char *tmp = NULL;
	const size_t tmplen = sizeof(nfs_export_path);

	tmp = kzalloc(tmplen, GFP_KERNEL);
	if (tmp == NULL)
		goto out_nomem;
	strcpy(tmp, NFS_ROOT);

	if (root_server_path[0] != '\0') {
		dprintk("Root-NFS: DHCPv4 option 17: %s\n",
			root_server_path);
		if (root_nfs_parse_options(root_server_path, tmp, tmplen))
			goto out_optionstoolong;
	}

	if (cmdline[0] != '\0') {
		dprintk("Root-NFS: nfsroot=%s\n", cmdline);
		if (root_nfs_parse_options(cmdline, tmp, tmplen))
			goto out_optionstoolong;
	}

	/*
	 * Append mandatory options for nfsroot so they override
	 * what has come before
	 */
	snprintf(addr_option, sizeof(addr_option), "nolock,addr=%pI4",
			&servaddr);
	if (root_nfs_cat(nfs_root_options, addr_option,
						sizeof(nfs_root_options)))
		goto out_optionstoolong;

	/*
	 * Set up nfs_root_device.  For NFS mounts, this looks like
	 *
	 *	server:/path
	 *
	 * At this point, utsname()->nodename contains our local
	 * IP address or hostname, set by ipconfig.  If "%s" exists
	 * in tmp, substitute the nodename, then shovel the whole
	 * mess into nfs_root_device.
	 */
	len = snprintf(nfs_export_path, sizeof(nfs_export_path),
				tmp, utsname()->nodename);
	if (len > (int)sizeof(nfs_export_path))
		goto out_devnametoolong;
	len = snprintf(nfs_root_device, sizeof(nfs_root_device),
				"%pI4:%s", &servaddr, nfs_export_path);
	if (len > (int)sizeof(nfs_root_device))
		goto out_devnametoolong;

	retval = 0;

out:
	kfree(tmp);
	return retval;
out_nomem:
	printk(KERN_ERR "Root-NFS: could not allocate memory\n");
	goto out;
out_optionstoolong:
	printk(KERN_ERR "Root-NFS: mount options string too long\n");
	goto out;
out_devnametoolong:
	printk(KERN_ERR "Root-NFS: root device name too long.\n");
	goto out;
}

/**
 * nfs_root_data - Return prepared 'data' for NFSROOT mount
 * @root_device: OUT: address of string containing NFSROOT device
 * @root_data: OUT: address of string containing NFSROOT mount options
 *
 * Returns zero and sets @root_device and @root_data if successful,
 * otherwise -1 is returned.
 */
int __init nfs_root_data(char **root_device, char **root_data)
{
#ifdef NFSROOT_DEBUG
	nfs_debug |= NFSDBG_ROOT | NFSDBG_MOUNT;
#endif	/* NFSROOT_DEBUG */

	servaddr = root_server_addr;
	if (servaddr == htonl(INADDR_NONE)) {
		printk(KERN_ERR "Root-NFS: no NFS server address\n");
		return -1;
	}

	if (root_nfs_data(nfs_root_parms) < 0)
		return -1;

	*root_device = nfs_root_device;
	*root_data = nfs_root_options;
	return 0;
}