export.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 1,206 行 · 第 1/2 页

	exp = exp_get_by_name(clp, mnt, dentry, reqp);

	while (exp == NULL && !IS_ROOT(dentry)) {
		struct dentry *parent;

		parent = dget_parent(dentry);
		dput(dentry);
		dentry = parent;
		exp = exp_get_by_name(clp, mnt, dentry, reqp);
	}
	dput(dentry);
	return exp;
}

/*
 * Hashtable locking. Write locks are placed only by user processes
 * wanting to modify export information.
 * Write locking only done in this file.  Read locking
 * needed externally.
 */

static DECLARE_RWSEM(hash_sem);

void
exp_readlock(void)
{
	down_read(&hash_sem);
}

static inline void
exp_writelock(void)
{
	down_write(&hash_sem);
}

void
exp_readunlock(void)
{
	up_read(&hash_sem);
}

static inline void
exp_writeunlock(void)
{
	up_write(&hash_sem);
}

static void exp_fsid_unhash(struct svc_export *exp)
{
	struct svc_expkey *ek;

	if ((exp->ex_flags & NFSEXP_FSID) == 0)
		return;

	ek = exp_get_fsid_key(exp->ex_client, exp->ex_fsid);
	if (ek && !IS_ERR(ek)) {
		ek->h.expiry_time = get_seconds()-1;
		expkey_put(&ek->h, &svc_expkey_cache);
	}
	svc_expkey_cache.nextcheck = get_seconds();
}

static int exp_fsid_hash(svc_client *clp, struct svc_export *exp)
{
	u32 fsid[2];
 
	if ((exp->ex_flags & NFSEXP_FSID) == 0)
		return 0;

	mk_fsid_v1(fsid, exp->ex_fsid);
	return exp_set_key(clp, 1, fsid, exp);
}

static int exp_hash(struct auth_domain *clp, struct svc_export *exp)
{
	u32 fsid[2];
	struct inode *inode = exp->ex_dentry->d_inode;
	dev_t dev = inode->i_sb->s_dev;

	if (old_valid_dev(dev)) {
		mk_fsid_v0(fsid, dev, inode->i_ino);
		return exp_set_key(clp, 0, fsid, exp);
	}
	mk_fsid_v3(fsid, dev, inode->i_ino);
	return exp_set_key(clp, 3, fsid, exp);
}

static void exp_unhash(struct svc_export *exp)
{
	struct svc_expkey *ek;
	struct inode *inode = exp->ex_dentry->d_inode;

	ek = exp_get_key(exp->ex_client, inode->i_sb->s_dev, inode->i_ino);
	if (ek && !IS_ERR(ek)) {
		ek->h.expiry_time = get_seconds()-1;
		expkey_put(&ek->h, &svc_expkey_cache);
	}
	svc_expkey_cache.nextcheck = get_seconds();
}
	
/*
 * Export a file system.
 */
int
exp_export(struct nfsctl_export *nxp)
{
	svc_client	*clp;
	struct svc_export	*exp = NULL;
	struct svc_export	new;
	struct svc_expkey	*fsid_key = NULL;
	struct nameidata nd;
	int		err;

	/* Consistency check */
	err = -EINVAL;
	if (!exp_verify_string(nxp->ex_path, NFS_MAXPATHLEN) ||
	    !exp_verify_string(nxp->ex_client, NFSCLNT_IDMAX))
		goto out;

	dprintk("exp_export called for %s:%s (%x/%ld fl %x).\n",
			nxp->ex_client, nxp->ex_path,
			(unsigned)nxp->ex_dev, (long)nxp->ex_ino,
			nxp->ex_flags);

	/* Try to lock the export table for update */
	exp_writelock();

	/* Look up client info */
	if (!(clp = auth_domain_find(nxp->ex_client)))
		goto out_unlock;


	/* Look up the dentry */
	err = path_lookup(nxp->ex_path, 0, &nd);
	if (err)
		goto out_unlock;
	err = -EINVAL;

	exp = exp_get_by_name(clp, nd.mnt, nd.dentry, NULL);

	/* must make sure there won't be an ex_fsid clash */
	if ((nxp->ex_flags & NFSEXP_FSID) &&
	    (fsid_key = exp_get_fsid_key(clp, nxp->ex_dev)) &&
	    !IS_ERR(fsid_key) &&
	    fsid_key->ek_export &&
	    fsid_key->ek_export != exp)
		goto finish;

	if (exp) {
		/* just a flags/id/fsid update */

		exp_fsid_unhash(exp);
		exp->ex_flags    = nxp->ex_flags;
		exp->ex_anon_uid = nxp->ex_anon_uid;
		exp->ex_anon_gid = nxp->ex_anon_gid;
		exp->ex_fsid     = nxp->ex_dev;

		err = exp_fsid_hash(clp, exp);
		goto finish;
	}

	err = check_export(nd.dentry->d_inode, nxp->ex_flags);
	if (err) goto finish;

	err = -ENOMEM;

	dprintk("nfsd: creating export entry %p for client %p\n", exp, clp);

	new.h.expiry_time = NEVER;
	new.h.flags = 0;
	new.ex_client = clp;
	new.ex_mnt = nd.mnt;
	new.ex_dentry = nd.dentry;
	new.ex_flags = nxp->ex_flags;
	new.ex_anon_uid = nxp->ex_anon_uid;
	new.ex_anon_gid = nxp->ex_anon_gid;
	new.ex_fsid = nxp->ex_dev;

	exp = svc_export_lookup(&new, 1);

	if (exp == NULL)
		goto finish;

	err = 0;

	if (exp_hash(clp, exp) ||
	    exp_fsid_hash(clp, exp)) {
		/* failed to create at least one index */
		exp_do_unexport(exp);
		cache_flush();
		err = -ENOMEM;
	}

finish:
	if (exp)
		exp_put(exp);
	if (fsid_key && !IS_ERR(fsid_key))
		expkey_put(&fsid_key->h, &svc_expkey_cache);
	if (clp)
		auth_domain_put(clp);
	path_release(&nd);
out_unlock:
	exp_writeunlock();
out:
	return err;
}

/*
 * Unexport a file system. The export entry has already
 * been removed from the client's list of exported fs's.
 */
static void
exp_do_unexport(svc_export *unexp)
{
	unexp->h.expiry_time = get_seconds()-1;
	svc_export_cache.nextcheck = get_seconds();
	exp_unhash(unexp);
	exp_fsid_unhash(unexp);
}


/*
 * unexport syscall.
 */
int
exp_unexport(struct nfsctl_export *nxp)
{
	struct auth_domain *dom;
	svc_export *exp;
	struct nameidata nd;
	int		err;

	/* Consistency check */
	if (!exp_verify_string(nxp->ex_path, NFS_MAXPATHLEN) ||
	    !exp_verify_string(nxp->ex_client, NFSCLNT_IDMAX))
		return -EINVAL;

	exp_writelock();

	err = -EINVAL;
	dom = auth_domain_find(nxp->ex_client);
	if (!dom) {
		dprintk("nfsd: unexport couldn't find %s\n", nxp->ex_client);
		goto out_unlock;
	}

	err = path_lookup(nxp->ex_path, 0, &nd);
	if (err)
		goto out_domain;

	err = -EINVAL;
	exp = exp_get_by_name(dom, nd.mnt, nd.dentry, NULL);
	path_release(&nd);
	if (!exp)
		goto out_domain;

	exp_do_unexport(exp);
	exp_put(exp);
	err = 0;

out_domain:
	auth_domain_put(dom);
	cache_flush();
out_unlock:
	exp_writeunlock();
	return err;
}

/*
 * Obtain the root fh on behalf of a client.
 * This could be done in user space, but I feel that it adds some safety
 * since its harder to fool a kernel module than a user space program.
 */
int
exp_rootfh(svc_client *clp, char *path, struct knfsd_fh *f, int maxsize)
{
	struct svc_export	*exp;
	struct nameidata	nd;
	struct inode		*inode;
	struct svc_fh		fh;
	int			err;

	err = -EPERM;
	/* NB: we probably ought to check that it's NUL-terminated */
	if (path_lookup(path, 0, &nd)) {
		printk("nfsd: exp_rootfh path not found %s", path);
		return err;
	}
	inode = nd.dentry->d_inode;

	dprintk("nfsd: exp_rootfh(%s [%p] %s:%s/%ld)\n",
		 path, nd.dentry, clp->name,
		 inode->i_sb->s_id, inode->i_ino);
	exp = exp_parent(clp, nd.mnt, nd.dentry, NULL);
	if (!exp) {
		dprintk("nfsd: exp_rootfh export not found.\n");
		goto out;
	}

	/*
	 * fh must be initialized before calling fh_compose
	 */
	fh_init(&fh, maxsize);
	if (fh_compose(&fh, exp, nd.dentry, NULL))
		err = -EINVAL;
	else
		err = 0;
	memcpy(f, &fh.fh_handle, sizeof(struct knfsd_fh));
	fh_put(&fh);
	exp_put(exp);
out:
	path_release(&nd);
	return err;
}

/*
 * Called when we need the filehandle for the root of the pseudofs,
 * for a given NFSv4 client.   The root is defined to be the
 * export point with fsid==0
 */
int
exp_pseudoroot(struct auth_domain *clp, struct svc_fh *fhp,
	       struct cache_req *creq)
{
	struct svc_expkey *fsid_key;
	int rv;
	u32 fsidv[2];

	mk_fsid_v1(fsidv, 0);

	fsid_key = exp_find_key(clp, 1, fsidv, creq);
	if (IS_ERR(fsid_key) && PTR_ERR(fsid_key) == -EAGAIN)
		return nfserr_dropit;
	if (!fsid_key || IS_ERR(fsid_key))
		return nfserr_perm;

	rv = fh_compose(fhp, fsid_key->ek_export, 
			  fsid_key->ek_export->ex_dentry, NULL);
	expkey_put(&fsid_key->h, &svc_expkey_cache);
	return rv;
}

/* Iterator */

static void *e_start(struct seq_file *m, loff_t *pos)
{
	loff_t n = *pos;
	unsigned hash, export;
	struct cache_head *ch;
	
	exp_readlock();
	read_lock(&svc_export_cache.hash_lock);
	if (!n--)
		return (void *)1;
	hash = n >> 32;
	export = n & ((1LL<<32) - 1);

	
	for (ch=export_table[hash]; ch; ch=ch->next)
		if (!export--)
			return ch;
	n &= ~((1LL<<32) - 1);
	do {
		hash++;
		n += 1LL<<32;
	} while(hash < EXPORT_HASHMAX && export_table[hash]==NULL);
	if (hash >= EXPORT_HASHMAX)
		return NULL;
	*pos = n+1;
	return export_table[hash];
}

static void *e_next(struct seq_file *m, void *p, loff_t *pos)
{
	struct cache_head *ch = p;
	int hash = (*pos >> 32);

	if (p == (void *)1)
		hash = 0;
	else if (ch->next == NULL) {
		hash++;
		*pos += 1LL<<32;
	} else {
		++*pos;
		return ch->next;
	}
	*pos &= ~((1LL<<32) - 1);
	while (hash < EXPORT_HASHMAX && export_table[hash] == NULL) {
		hash++;
		*pos += 1LL<<32;
	}
	if (hash >= EXPORT_HASHMAX)
		return NULL;
	++*pos;
	return export_table[hash];
}

static void e_stop(struct seq_file *m, void *p)
{
	read_unlock(&svc_export_cache.hash_lock);
	exp_readunlock();
}

struct flags {
	int flag;
	char *name[2];
} expflags[] = {
	{ NFSEXP_READONLY, {"ro", "rw"}},
	{ NFSEXP_INSECURE_PORT, {"insecure", ""}},
	{ NFSEXP_ROOTSQUASH, {"root_squash", "no_root_squash"}},
	{ NFSEXP_ALLSQUASH, {"all_squash", ""}},
	{ NFSEXP_ASYNC, {"async", "sync"}},
	{ NFSEXP_GATHERED_WRITES, {"wdelay", "no_wdelay"}},
	{ NFSEXP_NOHIDE, {"nohide", ""}},
	{ NFSEXP_CROSSMOUNT, {"crossmnt", ""}},
	{ NFSEXP_NOSUBTREECHECK, {"no_subtree_check", ""}},
	{ NFSEXP_NOAUTHNLM, {"insecure_locks", ""}},
#ifdef MSNFS
	{ NFSEXP_MSNFS, {"msnfs", ""}},
#endif
	{ 0, {"", ""}}
};

static void exp_flags(struct seq_file *m, int flag, int fsid, uid_t anonu, uid_t anong)
{
	int first = 0;
	struct flags *flg;

	for (flg = expflags; flg->flag; flg++) {
		int state = (flg->flag & flag)?0:1;
		if (*flg->name[state])
			seq_printf(m, "%s%s", first++?",":"", flg->name[state]);
	}
	if (flag & NFSEXP_FSID)
		seq_printf(m, "%sfsid=%d", first++?",":"", fsid);
	if (anonu != (uid_t)-2 && anonu != (0x10000-2))
		seq_printf(m, "%sanonuid=%d", first++?",":"", anonu);
	if (anong != (gid_t)-2 && anong != (0x10000-2))
		seq_printf(m, "%sanongid=%d", first++?",":"", anong);
}

static int e_show(struct seq_file *m, void *p)
{
	struct cache_head *cp = p;
	struct svc_export *exp = container_of(cp, struct svc_export, h);
	svc_client *clp;

	if (p == (void *)1) {
		seq_puts(m, "# Version 1.1\n");
		seq_puts(m, "# Path Client(Flags) # IPs\n");
		return 0;
	}

	clp = exp->ex_client;
	cache_get(&exp->h);
	if (cache_check(&svc_export_cache, &exp->h, NULL))
		return 0;
	if (cache_put(&exp->h, &svc_export_cache)) BUG();
	return svc_export_show(m, &svc_export_cache, cp);
}

struct seq_operations nfs_exports_op = {
	.start	= e_start,
	.next	= e_next,
	.stop	= e_stop,
	.show	= e_show,
};

/*
 * Add or modify a client.
 * Change requests may involve the list of host addresses. The list of
 * exports and possibly existing uid maps are left untouched.
 */
int
exp_addclient(struct nfsctl_client *ncp)
{
	struct auth_domain	*dom;
	int			i, err;

	/* First, consistency check. */
	err = -EINVAL;
	if (! exp_verify_string(ncp->cl_ident, NFSCLNT_IDMAX))
		goto out;
	if (ncp->cl_naddr > NFSCLNT_ADDRMAX)
		goto out;

	/* Lock the hashtable */
	exp_writelock();

	dom = unix_domain_find(ncp->cl_ident);

	err = -ENOMEM;
	if (!dom)
		goto out_unlock;

	/* Insert client into hashtable. */
	for (i = 0; i < ncp->cl_naddr; i++)
		auth_unix_add_addr(ncp->cl_addrlist[i], dom);

	auth_unix_forget_old(dom);
	auth_domain_put(dom);

	err = 0;

out_unlock:
	exp_writeunlock();
out:
	return err;
}

/*
 * Delete a client given an identifier.
 */
int
exp_delclient(struct nfsctl_client *ncp)
{
	int		err;
	struct auth_domain *dom;

	err = -EINVAL;
	if (!exp_verify_string(ncp->cl_ident, NFSCLNT_IDMAX))
		goto out;

	/* Lock the hashtable */
	exp_writelock();

	dom = auth_domain_find(ncp->cl_ident);
	/* just make sure that no addresses work 
	 * and that it will expire soon 
	 */
	if (dom) {
		err = auth_unix_forget_old(dom);
		dom->h.expiry_time = get_seconds();
		auth_domain_put(dom);
	}

	exp_writeunlock();
out:
	return err;
}

/*
 * Verify that string is non-empty and does not exceed max length.
 */
static int
exp_verify_string(char *cp, int max)
{
	int	i;

	for (i = 0; i < max; i++)
		if (!cp[i])
			return i;
	cp[i] = 0;
	printk(KERN_NOTICE "nfsd: couldn't validate string %s\n", cp);
	return 0;
}

/*
 * Initialize the exports module.
 */
void
nfsd_export_init(void)
{
	dprintk("nfsd: initializing export module.\n");

	cache_register(&svc_export_cache);
	cache_register(&svc_expkey_cache);

}

/*
 * Flush exports table - called when last nfsd thread is killed
 */
void
nfsd_export_flush(void)
{
	exp_writelock();
	cache_purge(&svc_expkey_cache);
	cache_purge(&svc_export_cache);
	exp_writeunlock();
}

/*
 * Shutdown the exports module.
 */
void
nfsd_export_shutdown(void)
{

	dprintk("nfsd: shutting down export module.\n");

	exp_writelock();

	if (cache_unregister(&svc_expkey_cache))
		printk(KERN_ERR "nfsd: failed to unregister expkey cache\n");
	if (cache_unregister(&svc_export_cache))
		printk(KERN_ERR "nfsd: failed to unregister export cache\n");
	svcauth_unix_purge();

	exp_writeunlock();
	dprintk("nfsd: export shutdown complete.\n");
}