path: root/fs/cifs/dfs_cache.c

// SPDX-License-Identifier: GPL-2.0
/*
 * DFS referral cache routines
 *
 * Copyright (c) 2018-2019 Paulo Alcantara <palcantara@suse.de>
 */

#include <linux/jhash.h>
#include <linux/ktime.h>
#include <linux/slab.h>
#include <linux/proc_fs.h>
#include <linux/nls.h>
#include <linux/workqueue.h>
#include "cifsglob.h"
#include "smb2pdu.h"
#include "smb2proto.h"
#include "cifsproto.h"
#include "cifs_debug.h"
#include "cifs_unicode.h"
#include "smb2glob.h"

#include "dfs_cache.h"

#define CACHE_HTABLE_SIZE 32
#define CACHE_MAX_ENTRIES 64

#define IS_INTERLINK_SET(v) ((v) & (DFSREF_REFERRAL_SERVER | \
				    DFSREF_STORAGE_SERVER))

struct cache_dfs_tgt {
	char *name;
	int path_consumed;
	struct list_head list;
};

struct cache_entry {
	struct hlist_node hlist;
	const char *path;
	int ttl;
	int srvtype;
	int flags;
	struct timespec64 etime;
	int path_consumed;
	int numtgts;
	struct list_head tlist;
	struct cache_dfs_tgt *tgthint;
};

struct vol_info {
	char *fullpath;
	spinlock_t smb_vol_lock;
	struct smb_vol smb_vol;
	char *mntdata;
	struct list_head list;
	struct list_head rlist;
	struct kref refcnt;
};

static struct kmem_cache *cache_slab __read_mostly;
static struct workqueue_struct *dfscache_wq __read_mostly;

static int cache_ttl;
static DEFINE_SPINLOCK(cache_ttl_lock);

static struct nls_table *cache_nlsc;

/*
 * Number of entries in the cache
 */
static atomic_t cache_count;

static struct hlist_head cache_htable[CACHE_HTABLE_SIZE];
static DECLARE_RWSEM(htable_rw_lock);

static LIST_HEAD(vol_list);
static DEFINE_SPINLOCK(vol_list_lock);

static void refresh_cache_worker(struct work_struct *work);

static DECLARE_DELAYED_WORK(refresh_task, refresh_cache_worker);

static int get_normalized_path(const char *path, char **npath)
{
	if (!path || strlen(path) < 3 || (*path != '\\' && *path != '/'))
		return -EINVAL;

	if (*path == '\\') {
		*npath = (char *)path;
	} else {
		*npath = kstrndup(path, strlen(path), GFP_KERNEL);
		if (!*npath)
			return -ENOMEM;
		convert_delimiter(*npath, '\\');
	}
	return 0;
}

static inline void free_normalized_path(const char *path, char *npath)
{
	if (path != npath)
		kfree(npath);
}

static inline bool cache_entry_expired(const struct cache_entry *ce)
{
	struct timespec64 ts;

	ktime_get_coarse_real_ts64(&ts);
	return timespec64_compare(&ts, &ce->etime) >= 0;
}

static inline void free_tgts(struct cache_entry *ce)
{
	struct cache_dfs_tgt *t, *n;

	list_for_each_entry_safe(t, n, &ce->tlist, list) {
		list_del(&t-&