path: root/fs/nfsd/export.c

// SPDX-License-Identifier: GPL-2.0
/*
 * NFS exporting and validation.
 *
 * We maintain a list of clients, each of which has a list of
 * exports. To export an fs to a given client, you first have
 * to create the client entry with NFSCTL_ADDCLIENT, which
 * creates a client control block and adds it to the hash
 * table. Then, you call NFSCTL_EXPORT for each fs.
 *
 *
 * Copyright (C) 1995, 1996 Olaf Kirch, <okir@monad.swb.de>
 */

#include <linux/slab.h>
#include <linux/namei.h>
#include <linux/module.h>
#include <linux/exportfs.h>
#include <linux/sunrpc/svc_xprt.h>

#include "nfsd.h"
#include "nfsfh.h"
#include "netns.h"
#include "pnfs.h"
#include "filecache.h"
#include "trace.h"

#define NFSDDBG_FACILITY	NFSDDBG_EXPORT

/*
 * We have two caches.
 * One maps client+vfsmnt+dentry to export options - the export map
 * The other maps client+filehandle-fragment to export options. - the expkey map
 *
 * The export options are actually stored in the first map, and the
 * second map contains a reference to the entry in the first map.
 */

#define	EXPKEY_HASHBITS		8
#define	EXPKEY_HASHMAX		(1 << EXPKEY_HASHBITS)
#define	EXPKEY_HASHMASK		(EXPKEY_HASHMAX -1)

static void expkey_put(struct kref *ref)
{
	struct svc_expkey *key = container_of(ref, struct svc_expkey, h.ref);

	if (test_bit(CACHE_VALID, &key->h.flags) &&
	    !test_bit(CACHE_NEGATIVE, &key->h.flags))
		path_put(&key->ek_path);
	auth_domain_put(key->ek_client);
	kfree_rcu(key, ek_rcu);
}

static int expkey_upcall(struct cache_detail *cd, struct cache_head *h)
{
	return sunrpc_cache_pipe_upcall(cd, h);
}

static void expkey_request(struct cache_detail *cd,
			   struct cache_head *h,
			   char **bpp, int *blen)
{
	/* client fsidtype \xfsid */
	struct svc_expkey *ek = container_of(h, struct svc_expkey, h);
	char type[5];

	qword_add(bpp, blen, ek->ek_client->name);
	snprintf(type, 5, "%d", ek->ek_fsidtype);
	qword_add(bpp, blen, type);
	qword_addhex(bpp, blen, (char*)ek->ek_fsid, key_len(ek->ek_fsidtype));
	(*bpp)[-1] = '\n';
}

static struct svc_expkey *svc_expkey_update(struct cache_detail *cd, struct svc_expkey *new,
					    struct svc_expkey *old);
static struct svc_expkey *svc_expkey_lookup(struct cache_detail *cd, struct svc_expkey *);

static int expkey_parse(struct cache_detail *cd, char *mesg, int mlen)
{
	/* client fsidtype fsid expiry [path] */
	char *buf;
	int len;
	struct auth_domain *dom = NULL;
	int err;
	u8 fsidtype;
	struct svc_expkey key;
	struct svc_expkey *ek = NULL;

	if (mesg[mlen - 1] != '\n')
		return -EINVAL;
	mesg[mlen-1] = 0;

	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
	err = -ENOMEM;
	if (!buf)
		goto out;

	err = -EINVAL;
	if (qword_get(&mesg, buf, PAGE_SIZE) <= 0)
		goto out;

	err = -ENOENT;
	dom = auth_domain_find(buf);
	if (!dom)
		goto out;
	dprintk("found domain %s\n", buf);

	err = -EINVAL;
	if (qword_get(&mesg, buf, PAGE_SIZE) <= 0)
		goto out;
	if (kstrtou8(buf, 10, &fsidtype))
		goto out;
	dprintk("found fsidtype %u\n", fsidtype);
	if (key_len(fsidtype)==0) /* invalid type */
		goto out;
	if ((len=qword_get(&mesg, buf, PAGE_SIZE)) <= 0)
		goto out;
	dprintk("found fsid length %d\n", len);
	if (len != key_len(fsidtype))
		goto out;

	/* OK, we seem to have a valid key */
	key.h.flags = 0;
	err = get_expiry(&mesg, &key.h.expiry_time);
	if (err)
		goto out;

	key.ek_client = dom;
	key.ek_fsidtype = fsidtype;
	memcpy(key.ek_fsid, buf, len);

	ek = svc_expkey_lookup(cd, &key);
	err = -ENOMEM;
	if (!ek)
		goto out;

	/* now we want a pathname, or empty meaning NEGATIVE  */
	err = -EINVAL;
	len = qword_get(&mesg, buf, PAGE_SIZE);
	if (len < 0)
		goto out;
	dprintk("Path seems to be <%s>\n", buf);
	err = 0;
	if (len == 0) {
		set_bit(CACHE_NEGATIVE, &key.h.flags);
		ek = svc_expkey_update(cd, &key, ek);
		if (ek)
			trace_nfsd_expkey_update(ek, NULL);
		else
			err = -ENOMEM;
	} else {
		err = kern_path(buf, 0, &key.ek_path);
		if (err)
			goto out;

		dprintk("Found the path %s\n", buf);

		ek = svc_expkey_update(cd, &key, ek);
		if (ek)
			trace_nfsd_expkey_update(ek, buf);
		else
			err = -ENOMEM;
		path_put(&key.ek_path);
	}
	cache_flush();
 out:
	if (ek)
		cache_put(&ek->h, cd);
	if (dom)
		auth_domain_put(dom);
	kfree(buf);
	return err;
}

static int expkey_show(struct seq_file *m,
		       struct cache_detail *cd,
		       struct cache_head *h)
{
	struct svc_expkey *ek ;
	int i;

	if (h ==NULL) {
		seq_puts(m, "#domain fsidtype fsid [path]\n");
		return 0;
	}
	ek = container_of(h, struct svc_expkey, h);
	seq_printf(m, "%s %d 0x", ek->ek_client->name,
		   ek->ek_fsidtype);
	for (i=0; i < key_len(ek->ek_fsidtype)/4; i++)
		seq_printf(m, "%08x", ek->ek_fsid[i]);
	if (test_bit(CACHE_VALID, &h->flags) && 
	    !test_bit(CACHE_NEGATIVE, &h->flags)) {
		seq_printf(m, " ");
		seq_path(m, &ek->ek_path, "\\ \t\n");
	}
	seq_printf(m, "\n");
	return 0;
}

static inline int expkey_match (struct cache_head *a, struct cache_head *b)
{
	struct svc_expkey *orig = container_of(a, struct svc_expkey, h);
	struct svc_expkey *new = container_of(b, struct svc_expkey, h);

	if (orig->ek_fsidtype != new->ek_fsidtype ||
	    orig->ek_client != new->ek_client ||
	    memcmp(orig->ek_fsid, new->ek_fsid, key_len(orig->ek_fsidtype)) != 0)
		return 0;
	return 1;
}

static inline void expkey_init(struct cache_head *cnew,
				   struct cache_head *citem)
{
	struct svc_expkey *new = container_of(cnew, struct svc_expkey, h);
	struct svc_expkey *item = container_of(citem, struct svc_expkey, h);

	kref_get(&item->ek_client->ref);
	new->ek_client = item->ek_client;
	new->ek_fsidtype = item->ek_fsidtype;

	memcpy(new->ek_fsid, item->ek_fsid, sizeof(new->ek_fsid));
}

static inline void expkey_update(struct cache_head *cnew,
				   struct cache_head *citem)
{
	struct svc_expkey *new = container_of(cnew, struct svc_expkey, h);
	struct svc_expkey *item = container_of(citem, struct svc_expkey, h);

	new->ek_path = item->ek_path;
	path_get(&item->ek_path);
}

static struct cache_head *expkey_alloc(void)
{
	struct svc_expkey *i = kmalloc(sizeof(*i), GFP_KERNEL);
	if (i)
		return &i->h;
	else
		return NULL;
}

static void expkey_flush(void)
{
	/*
	 * Take the nfsd_mutex here to ensure that the file cache is not
	 * destroyed while we're in the middle of flushing.
	 */
	mutex_lock(&nfsd_mutex);
	nfsd_file_cache_purge(current->nsproxy->net_ns);
	mutex_unlock(&nfsd_mutex);
}

static const struct cache_detail svc_expkey_cache_template = {
	.owner		= THIS_MODULE,
	.hash_size	= EXPKEY_HASHMAX,
	.name		= "nfsd.fh",
	.cache_put	= expkey_put,
	.cache_upcall	= expkey_upcall,
	.cache_request	= expkey_request,
	.cache_parse	= expkey_parse,
	.cache_show	= expkey_show,
	.match		= expkey_match,
	.init		= expkey_init,
	.update       	= expkey_update,
	.alloc		= expkey_alloc,
	.flush		= expkey_flush,
};

static int
svc_expkey_hash(struct svc_expkey *item)
{
	int hash = item->ek_fsidtype;
	char * cp = (char*)item->ek_fsid;
	int len = key_len(item->ek_fsidtype);

	hash ^= hash_mem(cp, len, EXPKEY_HASHBITS);
	hash ^= hash_ptr(item->ek_client, EXPKEY_HASHBITS);
	hash &= EXPKEY_HASHMASK;
	return hash;
}

static struct svc_expkey *
svc_expkey_lookup(struct cache_detail *cd, struct svc_expkey *item)
{
	struct cache_head *ch;
	int hash = svc_expkey_hash(item);

	ch = sunrpc_cache_lookup_rcu(cd, &item->h, hash);
	if (ch)
		return container_of(ch, struct svc_expkey, h);
	else
		return NULL;
}

static struct svc_expkey *
svc_expkey_update(struct cache_detail *cd, struct svc_expkey *new,
		  struct svc_expkey *old)
{
	struct cache_head *ch;
	int hash = svc_expkey_hash(new);

	ch = sunrpc_cache_update(cd, &new->h, &old->h, hash);
	if (ch)
		return container_of(ch, struct svc_expkey, h);
	else
		return NULL;
}


#define	EXPORT_HASHBITS		8
#define	EXPORT_HASHMAX		(1<< EXPORT_HASHBITS)

static void nfsd4_fslocs_free(struct nfsd4_fs_locations *fsloc)
{
	struct nfsd4_fs_location *locations = fsloc->locations;
	int i;

	if (!locations)
		return;

	for (i = 0; i < fsloc->locations_count; i++) {
		kfree(locations[i].path);
		kfree(locations[i].hosts);
	}

	kfree(locations);
	fsloc->locations = NULL;
}

static int export_stats_init(struct export_stats *stats)
{
	stats->start_time = ktime_get_seconds();
	return percpu_counter_init_many(stats->counter, 0, GFP_KERNEL,
					EXP_STATS_COUNTERS_NUM);