/*
 * linux/fs/nfsd/nfsfh.c
 *
 * NFS server file handle treatment.
 *
 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
 * Portions Copyright (C) 1999 G. Allen Morris III <gam3@acm.org>
 * Extensive rewrite by Neil Brown <neilb@cse.unsw.edu.au> Southern-Spring 1999
 * ... and again Southern-Winter 2001 to support export_operations
 */

#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/smp_lock.h>
#include <linux/fs.h>
#include <linux/unistd.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/dcache.h>
#include <asm/pgtable.h>

#include <linux/sunrpc/svc.h>
#include <linux/nfsd/nfsd.h>

#define NFSDDBG_FACILITY		NFSDDBG_FH
#define NFSD_PARANOIA 1
/* #define NFSD_DEBUG_VERBOSE 1 */


static int nfsd_nr_verified;
static int nfsd_nr_put;

extern struct export_operations export_op_default;

#define	CALL(ops,fun) ((ops->fun)?(ops->fun):export_op_default.fun)

/*
 * our acceptability function.
 * if NOSUBTREECHECK, accept anything
 * if not, require that we can walk up to exp->ex_dentry
 * doing some checks on the 'x' bits
 */
int nfsd_acceptable(void *expv, struct dentry *dentry)
{
	struct svc_export *exp = expv;
	int rv;
	struct dentry *tdentry;
	struct dentry *parent;

	if (exp->ex_flags & NFSEXP_NOSUBTREECHECK)
		return 1;

	tdentry = dget(dentry);
	while (tdentry != exp->ex_dentry && ! IS_ROOT(tdentry)) {
		/* make sure parents give x permission to user */
		int err;
		read_lock(&dparent_lock);
		parent = dget(tdentry->d_parent);
		read_unlock(&dparent_lock);
		err = permission(parent->d_inode, S_IXOTH);
		if (err < 0) {
			dput(parent);
			break;
		}
		dput(tdentry);
		tdentry = parent;
	}
	if (tdentry != exp->ex_dentry)
		dprintk("nfsd_acceptable failed at %p %s\n", tdentry, tdentry->d_name.name);
	rv = (tdentry == exp->ex_dentry);
	dput(tdentry);
	return rv;
}


/*
 * Perform sanity checks on the dentry in a client's file handle.
 *
 * Note that the file handle dentry may need to be freed even after
 * an error return.
 *
 * This is only called at the start of an nfsproc call, so fhp points to
 * a svc_fh which is all 0 except for the over-the-wire file handle.
 */
u32
fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access)
{
	struct knfsd_fh	*fh = &fhp->fh_handle;
	struct svc_export *exp;
	struct dentry	*dentry;
	struct inode	*inode;
	u32		error = 0;

	dprintk("nfsd: fh_verify(%s)\n", SVCFH_fmt(fhp));

	/* keep this filehandle for possible reference  when encoding attributes */
	rqstp->rq_reffh = fh;

	if (!fhp->fh_dentry) {
		dev_t xdev = 0;
		ino_t xino = 0;
		__u32 *datap=NULL;
		__u32 tfh[3];		/* filehandle fragment for oldstyle filehandles */
		int fileid_type;
		int data_left = fh->fh_size/4;
		int nfsdev;
		int fsid = 0;

		error = nfserr_stale;
		if (rqstp->rq_vers == 3)
			error = nfserr_badhandle;

		if (fh->fh_version == 1) {
			datap = fh->fh_auth;
			if (--data_left<0) goto out;
			switch (fh->fh_auth_type) {
			case 0: break;
			default: goto out;
			}

			switch (fh->fh_fsid_type) {
			case 0:
				if ((data_left-=2)<0) goto out;
				nfsdev = ntohl(*datap++);
				xdev = MKDEV(nfsdev>>16, nfsdev&0xFFFF);
				xino = *datap++;
				break;
			case 1:
				if ((data_left-=1)<0) goto out;
				fsid = *datap++;
				break;
			default:
				goto out;
			}
		} else {
			if (fh->fh_size != NFS_FHSIZE)
				goto out;
			/* assume old filehandle format */
			xdev = u32_to_dev_t(fh->ofh_xdev);
			xino = u32_to_ino_t(fh->ofh_xino);
		}

		/*
		 * Look up the export entry.
		 */
		error = nfserr_stale; 
		if (fh->fh_version == 1 && fh->fh_fsid_type == 1)
			exp = exp_get_fsid(rqstp->rq_client, fsid);
		else
			exp = exp_get(rqstp->rq_client, xdev, xino);

		if (!exp) {
			/* export entry revoked */
			goto out;
		}

		/* Check if the request originated from a secure port. */
		error = nfserr_perm;
		if (!rqstp->rq_secure && EX_SECURE(exp)) {
			printk(KERN_WARNING
			       "nfsd: request from insecure port (%08x:%d)!\n",
			       ntohl(rqstp->rq_addr.sin_addr.s_addr),
			       ntohs(rqstp->rq_addr.sin_port));
			goto out;
		}

		/* Set user creds if we haven't done so already. */
		nfsd_setuser(rqstp, exp);

		/*
		 * Look up the dentry using the NFS file handle.
		 */
		error = nfserr_stale;
		if (rqstp->rq_vers == 3)
			error = nfserr_badhandle;

		if (fh->fh_version != 1) {
			tfh[0] = fh->ofh_ino;
			tfh[1] = fh->ofh_generation;
			tfh[2] = fh->ofh_dirino;
			datap = tfh;
			data_left = 3;
			if (fh->ofh_dirino == 0)
				fileid_type = 1;
			else
				fileid_type = 2;
		} else
			fileid_type = fh->fh_fileid_type;
		
		if (fileid_type == 0)
			dentry = dget(exp->ex_dentry);
		else {
			struct export_operations *nop = exp->ex_mnt->mnt_sb->s_export_op;
				dentry = CALL(nop,decode_fh)(exp->ex_mnt->mnt_sb,
							     datap, data_left,
							     fileid_type,
							     nfsd_acceptable, exp);
		}
		if (dentry == NULL)
			goto out;
		if (IS_ERR(dentry)) {
			if (PTR_ERR(dentry) != -EINVAL)
				error = nfserrno(PTR_ERR(dentry));
			goto out;
		}
#ifdef NFSD_PARANOIA
		if (S_ISDIR(dentry->d_inode->i_mode) &&
		    (dentry->d_flags & DCACHE_DISCONNECTED)) {
			printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %s/%s\n",
			       dentry->d_parent->d_name.name, dentry->d_name.name);
		}
#endif

		fhp->fh_dentry = dentry;
		fhp->fh_export = exp;
		nfsd_nr_verified++;
	} else {
		/* just rechecking permissions
		 * (e.g. nfsproc_create calls fh_verify, then nfsd_create does as well)
		 */
		dprintk("nfsd: fh_verify - just checking\n");
		dentry = fhp->fh_dentry;
		exp = fhp->fh_export;
	}

	inode = dentry->d_inode;

	/* Type check. The correct error return for type mismatches
	 * does not seem to be generally agreed upon. SunOS seems to
	 * use EISDIR if file isn't S_IFREG; a comment in the NFSv3
	 * spec says this is incorrect (implementation notes for the
	 * write call).
	 */

	/* Type can be negative when creating hardlinks - not to a dir */
	if (type > 0 && (inode->i_mode & S_IFMT) != type) {
		error = (type == S_IFDIR)? nfserr_notdir : nfserr_isdir;
		goto out;
	}
	if (type < 0 && (inode->i_mode & S_IFMT) == -type) {
		error = (type == -S_IFDIR)? nfserr_notdir : nfserr_isdir;
		goto out;
	}

	/* Finally, check access permissions. */
	error = nfsd_permission(exp, dentry, access);

#ifdef NFSD_PARANOIA_EXTREME
	if (error) {
		printk("fh_verify: %s/%s permission failure, acc=%x, error=%d\n",
		       dentry->d_parent->d_name.name, dentry->d_name.name, access, (error >> 24));
	}
#endif
out:
	if (error == nfserr_stale)
		nfsdstats.fh_stale++;
	return error;
}


/*
 * Compose a file handle for an NFS reply.
 *
 * Note that when first composed, the dentry may not yet have
 * an inode.  In this case a call to fh_update should be made
 * before the fh goes out on the wire ...
 */
inline int _fh_update(struct dentry *dentry, struct svc_export *exp,
		      __u32 *datap, int *maxsize)
{
	struct export_operations *nop = exp->ex_mnt->mnt_sb->s_export_op;
	
	if (dentry == exp->ex_dentry) {
		*maxsize = 0;
		return 0;
	}

	return CALL(nop,encode_fh)(dentry, datap, maxsize,
			  !(exp->ex_flags&NFSEXP_NOSUBTREECHECK));
}

/*
 * for composing old style file handles
 */
inline void _fh_update_old(struct dentry *dentry, struct svc_export *exp,
			   struct knfsd_fh *fh)
{
	fh->ofh_ino = ino_t_to_u32(dentry->d_inode->i_ino);
	fh->ofh_generation = dentry->d_inode->i_generation;
	if (S_ISDIR(dentry->d_inode->i_mode) ||
	    (exp->ex_flags & NFSEXP_NOSUBTREECHECK))
		fh->ofh_dirino = 0;
}

int
fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry, struct svc_fh *ref_fh)
{
	/* ref_fh is a reference file handle.
	 * if it is non-null, then we should compose a filehandle which is
	 * of the same version, where possible.
	 * Currently, that means that if ref_fh->fh_handle.fh_version == 0xca
	 * Then create a 32byte filehandle using nfs_fhbase_old
	 *
	 */
	
	struct inode * inode = dentry->d_inode;
	struct dentry *parent = dentry->d_parent;
	__u32 *datap;

	dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %s/%s, ino=%ld)\n",
		MAJOR(exp->ex_dev), MINOR(exp->ex_dev), (long) exp->ex_ino,
		parent->d_name.name, dentry->d_name.name,
		(inode ? inode->i_ino : 0));

	if (fhp->fh_locked || fhp->fh_dentry) {
		printk(KERN_ERR "fh_compose: fh %s/%s not initialized!\n",
			parent->d_name.name, dentry->d_name.name);
	}
	if (fhp->fh_maxsize < NFS_FHSIZE)
		printk(KERN_ERR "fh_compose: called with maxsize %d! %s/%s\n",
		       fhp->fh_maxsize, parent->d_name.name, dentry->d_name.name);

	fhp->fh_dentry = dentry; /* our internal copy */
	fhp->fh_export = exp;

	if (ref_fh &&
	    ref_fh->fh_handle.fh_version == 0xca) {
		/* old style filehandle please */
		memset(&fhp->fh_handle.fh_base, 0, NFS_FHSIZE);
		fhp->fh_handle.fh_size = NFS_FHSIZE;
		fhp->fh_handle.ofh_dcookie = 0xfeebbaca;
		fhp->fh_handle.ofh_dev =  htonl((MAJOR(exp->ex_dev)<<16)| MINOR(exp->ex_dev));
		fhp->fh_handle.ofh_xdev = fhp->fh_handle.ofh_dev;
		fhp->fh_handle.ofh_xino = ino_t_to_u32(exp->ex_ino);
		fhp->fh_handle.ofh_dirino = ino_t_to_u32(parent_ino(dentry));
		if (inode)
			_fh_update_old(dentry, exp, &fhp->fh_handle);
	} else {
		fhp->fh_handle.fh_version = 1;
		fhp->fh_handle.fh_auth_type = 0;
		datap = fhp->fh_handle.fh_auth+0;
		if ((exp->ex_flags & NFSEXP_FSID) &&
		    (!ref_fh || ref_fh->fh_handle.fh_fsid_type == 1)) {
			fhp->fh_handle.fh_fsid_type = 1;
			/* fsid_type 1 == 4 bytes filesystem id */
			*datap++ = exp->ex_fsid;
			fhp->fh_handle.fh_size = 2*4;
		} else {
			fhp->fh_handle.fh_fsid_type = 0;
			/* fsid_type 0 == 2byte major, 2byte minor, 4byte inode */
			*datap++ = htonl((MAJOR(exp->ex_dev)<<16)| MINOR(exp->ex_dev));
			*datap++ = ino_t_to_u32(exp->ex_ino);
			fhp->fh_handle.fh_size = 3*4;
		}
		if (inode) {
			int size = fhp->fh_maxsize/4 - 3;
			fhp->fh_handle.fh_fileid_type =
				_fh_update(dentry, exp, datap, &size);
			fhp->fh_handle.fh_size += size*4;
		}
		if (fhp->fh_handle.fh_fileid_type == 255)
			return nfserr_opnotsupp;
	}

	nfsd_nr_verified++;
	return 0;
}

/*
 * Update file handle information after changing a dentry.
 * This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create
 */
int
fh_update(struct svc_fh *fhp)
{
	struct dentry *dentry;
	__u32 *datap;
	
	if (!fhp->fh_dentry)
		goto out_bad;

	dentry = fhp->fh_dentry;
	if (!dentry->d_inode)
		goto out_negative;
	if (fhp->fh_handle.fh_version != 1) {
		_fh_update_old(dentry, fhp->fh_export, &fhp->fh_handle);
	} else {
		int size;
		if (fhp->fh_handle.fh_fileid_type != 0)
			goto out_uptodate;
		datap = fhp->fh_handle.fh_auth+
			fhp->fh_handle.fh_size/4 -1;
		size = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
		fhp->fh_handle.fh_fileid_type =
			_fh_update(dentry, fhp->fh_export, datap, &size);
		fhp->fh_handle.fh_size += size*4;
		if (fhp->fh_handle.fh_fileid_type == 255)
			return nfserr_opnotsupp;
	}
out:
	return 0;

out_bad:
	printk(KERN_ERR "fh_update: fh not verified!\n");
	goto out;
out_negative:
	printk(KERN_ERR "fh_update: %s/%s still negative!\n",
		dentry->d_parent->d_name.name, dentry->d_name.name);
	goto out;
out_uptodate:
	printk(KERN_ERR "fh_update: %s/%s already up-to-date!\n",
		dentry->d_parent->d_name.name, dentry->d_name.name);
	goto out;
}

/*
 * Release a file handle.
 */
void
fh_put(struct svc_fh *fhp)
{
	struct dentry * dentry = fhp->fh_dentry;
	if (dentry) {
		fh_unlock(fhp);
		fhp->fh_dentry = NULL;
		dput(dentry);
		nfsd_nr_put++;
	}
	return;
}