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dfs_cache.c
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// SPDX-License-Identifier: GPL-2.0
/*
* DFS referral cache routines
*
* Copyright (c) 2018-2019 Paulo Alcantara <[email protected]>
*/
#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 <linux/uuid.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 "dns_resolve.h"
#include "dfs_cache.h"
#define CACHE_HTABLE_SIZE 32
#define CACHE_MAX_ENTRIES 64
#define CACHE_MIN_TTL 120 /* 2 minutes */
#define IS_DFS_INTERLINK(v) (((v) & DFSREF_REFERRAL_SERVER) && !((v) & 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 hdr_flags; /* RESP_GET_DFS_REFERRAL.ReferralHeaderFlags */
int ttl; /* DFS_REREFERRAL_V3.TimeToLive */
int srvtype; /* DFS_REREFERRAL_V3.ServerType */
int ref_flags; /* DFS_REREFERRAL_V3.ReferralEntryFlags */
struct timespec64 etime;
int path_consumed; /* RESP_GET_DFS_REFERRAL.PathConsumed */
int numtgts;
struct list_head tlist;
struct cache_dfs_tgt *tgthint;
};
/* List of referral server sessions per dfs mount */
struct mount_group {
struct list_head list;
uuid_t id;
struct cifs_ses *sessions[CACHE_MAX_ENTRIES];
int num_sessions;
spinlock_t lock;
struct list_head refresh_list;
struct kref refcount;
};
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_cp;
/*
* 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(mount_group_list);
static DEFINE_MUTEX(mount_group_list_lock);
static void refresh_cache_worker(struct work_struct *work);
static DECLARE_DELAYED_WORK(refresh_task, refresh_cache_worker);
static void __mount_group_release(struct mount_group *mg)
{
int i;
for (i = 0; i < mg->num_sessions; i++)
cifs_put_smb_ses(mg->sessions[i]);
kfree(mg);
}
static void mount_group_release(struct kref *kref)
{
struct mount_group *mg = container_of(kref, struct mount_group, refcount);
mutex_lock(&mount_group_list_lock);
list_del(&mg->list);
mutex_unlock(&mount_group_list_lock);
__mount_group_release(mg);
}
static struct mount_group *find_mount_group_locked(const uuid_t *id)
{
struct mount_group *mg;
list_for_each_entry(mg, &mount_group_list, list) {
if (uuid_equal(&mg->id, id))
return mg;
}
return ERR_PTR(-ENOENT);
}
static struct mount_group *__get_mount_group_locked(const uuid_t *id)
{
struct mount_group *mg;
mg = find_mount_group_locked(id);
if (!IS_ERR(mg))
return mg;
mg = kmalloc(sizeof(*mg), GFP_KERNEL);
if (!mg)
return ERR_PTR(-ENOMEM);
kref_init(&mg->refcount);
uuid_copy(&mg->id, id);
mg->num_sessions = 0;
spin_lock_init(&mg->lock);
list_add(&mg->list, &mount_group_list);
return mg;
}
static struct mount_group *get_mount_group(const uuid_t *id)
{
struct mount_group *mg;
mutex_lock(&mount_group_list_lock);
mg = __get_mount_group_locked(id);
if (!IS_ERR(mg))
kref_get(&mg->refcount);
mutex_unlock(&mount_group_list_lock);
return mg;
}
static void free_mount_group_list(void)
{
struct mount_group *mg, *tmp_mg;
list_for_each_entry_safe(mg, tmp_mg, &mount_group_list, list) {
list_del_init(&mg->list);
__mount_group_release(mg);
}
}
/**
* dfs_cache_canonical_path - get a canonical DFS path
*
* @path: DFS path
* @cp: codepage
* @remap: mapping type
*
* Return canonical path if success, otherwise error.
*/
char *dfs_cache_canonical_path(const char *path, const struct nls_table *cp, int remap)
{
char *tmp;
int plen = 0;
char *npath;
if (!path || strlen(path) < 3 || (*path != '\\' && *path != '/'))
return ERR_PTR(-EINVAL);
if (unlikely(strcmp(cp->charset, cache_cp->charset))) {
tmp = (char *)cifs_strndup_to_utf16(path, strlen(path), &plen, cp, remap);
if (!tmp) {
cifs_dbg(VFS, "%s: failed to convert path to utf16\n", __func__);
return ERR_PTR(-EINVAL);
}
npath = cifs_strndup_from_utf16(tmp, plen, true, cache_cp);
kfree(tmp);
if (!npath) {
cifs_dbg(VFS, "%s: failed to convert path from utf16\n", __func__);
return ERR_PTR(-EINVAL);
}
} else {
npath = kstrdup(path, GFP_KERNEL);
if (!npath)
return ERR_PTR(-ENOMEM);
}
convert_delimiter(npath, '\\');
return 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->list);
kfree(t->name);
kfree(t);
}
}
static inline void flush_cache_ent(struct cache_entry *ce)
{
hlist_del_init(&ce->hlist);
kfree(ce->path);
free_tgts(ce);
atomic_dec(&cache_count);
kmem_cache_free(cache_slab, ce);
}
static void flush_cache_ents(void)
{
int i;
for (i = 0; i < CACHE_HTABLE_SIZE; i++) {
struct hlist_head *l = &cache_htable[i];
struct hlist_node *n;
struct cache_entry *ce;
hlist_for_each_entry_safe(ce, n, l, hlist) {
if (!hlist_unhashed(&ce->hlist))
flush_cache_ent(ce);
}
}
}
/*
* dfs cache /proc file
*/
static int dfscache_proc_show(struct seq_file *m, void *v)
{
int i;
struct cache_entry *ce;
struct cache_dfs_tgt *t;
seq_puts(m, "DFS cache\n---------\n");
down_read(&htable_rw_lock);
for (i = 0; i < CACHE_HTABLE_SIZE; i++) {
struct hlist_head *l = &cache_htable[i];
hlist_for_each_entry(ce, l, hlist) {
if (hlist_unhashed(&ce->hlist))
continue;
seq_printf(m,
"cache entry: path=%s,type=%s,ttl=%d,etime=%ld,hdr_flags=0x%x,ref_flags=0x%x,interlink=%s,path_consumed=%d,expired=%s\n",
ce->path, ce->srvtype == DFS_TYPE_ROOT ? "root" : "link",
ce->ttl, ce->etime.tv_nsec, ce->hdr_flags, ce->ref_flags,
IS_DFS_INTERLINK(ce->hdr_flags) ? "yes" : "no",
ce->path_consumed, cache_entry_expired(ce) ? "yes" : "no");
list_for_each_entry(t, &ce->tlist, list) {
seq_printf(m, " %s%s\n",
t->name,
READ_ONCE(ce->tgthint) == t ? " (target hint)" : "");
}
}
}
up_read(&htable_rw_lock);
return 0;
}
static ssize_t dfscache_proc_write(struct file *file, const char __user *buffer,
size_t count, loff_t *ppos)
{
char c;
int rc;
rc = get_user(c, buffer);
if (rc)
return rc;
if (c != '0')
return -EINVAL;
cifs_dbg(FYI, "clearing dfs cache\n");
down_write(&htable_rw_lock);
flush_cache_ents();
up_write(&htable_rw_lock);
return count;
}
static int dfscache_proc_open(struct inode *inode, struct file *file)
{
return single_open(file, dfscache_proc_show, NULL);
}
const struct proc_ops dfscache_proc_ops = {
.proc_open = dfscache_proc_open,
.proc_read = seq_read,
.proc_lseek = seq_lseek,
.proc_release = single_release,
.proc_write = dfscache_proc_write,
};
#ifdef CONFIG_CIFS_DEBUG2
static inline void dump_tgts(const struct cache_entry *ce)
{
struct cache_dfs_tgt *t;
cifs_dbg(FYI, "target list:\n");
list_for_each_entry(t, &ce->tlist, list) {
cifs_dbg(FYI, " %s%s\n", t->name,
READ_ONCE(ce->tgthint) == t ? " (target hint)" : "");
}
}
static inline void dump_ce(const struct cache_entry *ce)
{
cifs_dbg(FYI, "cache entry: path=%s,type=%s,ttl=%d,etime=%ld,hdr_flags=0x%x,ref_flags=0x%x,interlink=%s,path_consumed=%d,expired=%s\n",
ce->path,
ce->srvtype == DFS_TYPE_ROOT ? "root" : "link", ce->ttl,
ce->etime.tv_nsec,
ce->hdr_flags, ce->ref_flags,
IS_DFS_INTERLINK(ce->hdr_flags) ? "yes" : "no",
ce->path_consumed,
cache_entry_expired(ce) ? "yes" : "no");
dump_tgts(ce);
}
static inline void dump_refs(const struct dfs_info3_param *refs, int numrefs)
{
int i;
cifs_dbg(FYI, "DFS referrals returned by the server:\n");
for (i = 0; i < numrefs; i++) {
const struct dfs_info3_param *ref = &refs[i];
cifs_dbg(FYI,
"\n"
"flags: 0x%x\n"
"path_consumed: %d\n"
"server_type: 0x%x\n"
"ref_flag: 0x%x\n"
"path_name: %s\n"
"node_name: %s\n"
"ttl: %d (%dm)\n",
ref->flags, ref->path_consumed, ref->server_type,
ref->ref_flag, ref->path_name, ref->node_name,
ref->ttl, ref->ttl / 60);
}
}
#else
#define dump_tgts(e)
#define dump_ce(e)
#define dump_refs(r, n)
#endif
/**
* dfs_cache_init - Initialize DFS referral cache.
*
* Return zero if initialized successfully, otherwise non-zero.
*/
int dfs_cache_init(void)
{
int rc;
int i;
dfscache_wq = alloc_workqueue("cifs-dfscache", WQ_FREEZABLE | WQ_UNBOUND, 1);
if (!dfscache_wq)
return -ENOMEM;
cache_slab = kmem_cache_create("cifs_dfs_cache",
sizeof(struct cache_entry), 0,
SLAB_HWCACHE_ALIGN, NULL);
if (!cache_slab) {
rc = -ENOMEM;
goto out_destroy_wq;
}
for (i = 0; i < CACHE_HTABLE_SIZE; i++)
INIT_HLIST_HEAD(&cache_htable[i]);
atomic_set(&cache_count, 0);
cache_cp = load_nls("utf8");
if (!cache_cp)
cache_cp = load_nls_default();
cifs_dbg(FYI, "%s: initialized DFS referral cache\n", __func__);
return 0;
out_destroy_wq:
destroy_workqueue(dfscache_wq);
return rc;
}
static int cache_entry_hash(const void *data, int size, unsigned int *hash)
{
int i, clen;
const unsigned char *s = data;
wchar_t c;
unsigned int h = 0;
for (i = 0; i < size; i += clen) {
clen = cache_cp->char2uni(&s[i], size - i, &c);
if (unlikely(clen < 0)) {
cifs_dbg(VFS, "%s: can't convert char\n", __func__);
return clen;
}
c = cifs_toupper(c);
h = jhash(&c, sizeof(c), h);
}
*hash = h % CACHE_HTABLE_SIZE;
return 0;
}
/* Return target hint of a DFS cache entry */
static inline char *get_tgt_name(const struct cache_entry *ce)
{
struct cache_dfs_tgt *t = READ_ONCE(ce->tgthint);
return t ? t->name : ERR_PTR(-ENOENT);
}
/* Return expire time out of a new entry's TTL */
static inline struct timespec64 get_expire_time(int ttl)
{
struct timespec64 ts = {
.tv_sec = ttl,
.tv_nsec = 0,
};
struct timespec64 now;
ktime_get_coarse_real_ts64(&now);
return timespec64_add(now, ts);
}
/* Allocate a new DFS target */
static struct cache_dfs_tgt *alloc_target(const char *name, int path_consumed)
{
struct cache_dfs_tgt *t;
t = kmalloc(sizeof(*t), GFP_ATOMIC);
if (!t)
return ERR_PTR(-ENOMEM);
t->name = kstrdup(name, GFP_ATOMIC);
if (!t->name) {
kfree(t);
return ERR_PTR(-ENOMEM);
}
t->path_consumed = path_consumed;
INIT_LIST_HEAD(&t->list);
return t;
}
/*
* Copy DFS referral information to a cache entry and conditionally update
* target hint.
*/
static int copy_ref_data(const struct dfs_info3_param *refs, int numrefs,
struct cache_entry *ce, const char *tgthint)
{
struct cache_dfs_tgt *target;
int i;
ce->ttl = max_t(int, refs[0].ttl, CACHE_MIN_TTL);
ce->etime = get_expire_time(ce->ttl);
ce->srvtype = refs[0].server_type;
ce->hdr_flags = refs[0].flags;
ce->ref_flags = refs[0].ref_flag;
ce->path_consumed = refs[0].path_consumed;
for (i = 0; i < numrefs; i++) {
struct cache_dfs_tgt *t;
t = alloc_target(refs[i].node_name, refs[i].path_consumed);
if (IS_ERR(t)) {
free_tgts(ce);
return PTR_ERR(t);
}
if (tgthint && !strcasecmp(t->name, tgthint)) {
list_add(&t->list, &ce->tlist);
tgthint = NULL;
} else {
list_add_tail(&t->list, &ce->tlist);
}
ce->numtgts++;
}
target = list_first_entry_or_null(&ce->tlist, struct cache_dfs_tgt,
list);
WRITE_ONCE(ce->tgthint, target);
return 0;
}
/* Allocate a new cache entry */
static struct cache_entry *alloc_cache_entry(struct dfs_info3_param *refs, int numrefs)
{
struct cache_entry *ce;
int rc;
ce = kmem_cache_zalloc(cache_slab, GFP_KERNEL);
if (!ce)
return ERR_PTR(-ENOMEM);
ce->path = refs[0].path_name;
refs[0].path_name = NULL;
INIT_HLIST_NODE(&ce->hlist);
INIT_LIST_HEAD(&ce->tlist);
rc = copy_ref_data(refs, numrefs, ce, NULL);
if (rc) {
kfree(ce->path);
kmem_cache_free(cache_slab, ce);
ce = ERR_PTR(rc);
}
return ce;
}
static void remove_oldest_entry_locked(void)
{
int i;
struct cache_entry *ce;
struct cache_entry *to_del = NULL;
WARN_ON(!rwsem_is_locked(&htable_rw_lock));
for (i = 0; i < CACHE_HTABLE_SIZE; i++) {
struct hlist_head *l = &cache_htable[i];
hlist_for_each_entry(ce, l, hlist) {
if (hlist_unhashed(&ce->hlist))
continue;
if (!to_del || timespec64_compare(&ce->etime,
&to_del->etime) < 0)
to_del = ce;
}
}
if (!to_del) {
cifs_dbg(FYI, "%s: no entry to remove\n", __func__);
return;
}
cifs_dbg(FYI, "%s: removing entry\n", __func__);
dump_ce(to_del);
flush_cache_ent(to_del);
}
/* Add a new DFS cache entry */
static struct cache_entry *add_cache_entry_locked(struct dfs_info3_param *refs,
int numrefs)
{
int rc;
struct cache_entry *ce;
unsigned int hash;
WARN_ON(!rwsem_is_locked(&htable_rw_lock));
if (atomic_read(&cache_count) >= CACHE_MAX_ENTRIES) {
cifs_dbg(FYI, "%s: reached max cache size (%d)\n", __func__, CACHE_MAX_ENTRIES);
remove_oldest_entry_locked();
}
rc = cache_entry_hash(refs[0].path_name, strlen(refs[0].path_name), &hash);
if (rc)
return ERR_PTR(rc);
ce = alloc_cache_entry(refs, numrefs);
if (IS_ERR(ce))
return ce;
spin_lock(&cache_ttl_lock);
if (!cache_ttl) {
cache_ttl = ce->ttl;
queue_delayed_work(dfscache_wq, &refresh_task, cache_ttl * HZ);
} else {
cache_ttl = min_t(int, cache_ttl, ce->ttl);
mod_delayed_work(dfscache_wq, &refresh_task, cache_ttl * HZ);
}
spin_unlock(&cache_ttl_lock);
hlist_add_head(&ce->hlist, &cache_htable[hash]);
dump_ce(ce);
atomic_inc(&cache_count);
return ce;
}
/* Check if two DFS paths are equal. @s1 and @s2 are expected to be in @cache_cp's charset */
static bool dfs_path_equal(const char *s1, int len1, const char *s2, int len2)
{
int i, l1, l2;
wchar_t c1, c2;
if (len1 != len2)
return false;
for (i = 0; i < len1; i += l1) {
l1 = cache_cp->char2uni(&s1[i], len1 - i, &c1);
l2 = cache_cp->char2uni(&s2[i], len2 - i, &c2);
if (unlikely(l1 < 0 && l2 < 0)) {
if (s1[i] != s2[i])
return false;
l1 = 1;
continue;
}
if (l1 != l2)
return false;
if (cifs_toupper(c1) != cifs_toupper(c2))
return false;
}
return true;
}
static struct cache_entry *__lookup_cache_entry(const char *path, unsigned int hash, int len)
{
struct cache_entry *ce;
hlist_for_each_entry(ce, &cache_htable[hash], hlist) {
if (dfs_path_equal(ce->path, strlen(ce->path), path, len)) {
dump_ce(ce);
return ce;
}
}
return ERR_PTR(-ENOENT);
}
/*
* Find a DFS cache entry in hash table and optionally check prefix path against normalized @path.
*
* Use whole path components in the match. Must be called with htable_rw_lock held.
*
* Return cached entry if successful.
* Return ERR_PTR(-ENOENT) if the entry is not found.
* Return error ptr otherwise.
*/
static struct cache_entry *lookup_cache_entry(const char *path)
{
struct cache_entry *ce;
int cnt = 0;
const char *s = path, *e;
char sep = *s;
unsigned int hash;
int rc;
while ((s = strchr(s, sep)) && ++cnt < 3)
s++;
if (cnt < 3) {
rc = cache_entry_hash(path, strlen(path), &hash);
if (rc)
return ERR_PTR(rc);
return __lookup_cache_entry(path, hash, strlen(path));
}
/*
* Handle paths that have more than two path components and are a complete prefix of the DFS
* referral request path (@path).
*
* See MS-DFSC 3.2.5.5 "Receiving a Root Referral Request or Link Referral Request".
*/
e = path + strlen(path) - 1;
while (e > s) {
int len;
/* skip separators */
while (e > s && *e == sep)
e--;
if (e == s)
break;
len = e + 1 - path;
rc = cache_entry_hash(path, len, &hash);
if (rc)
return ERR_PTR(rc);
ce = __lookup_cache_entry(path, hash, len);
if (!IS_ERR(ce))
return ce;
/* backward until separator */
while (e > s && *e != sep)
e--;
}
return ERR_PTR(-ENOENT);
}
/**
* dfs_cache_destroy - destroy DFS referral cache
*/
void dfs_cache_destroy(void)
{
cancel_delayed_work_sync(&refresh_task);
unload_nls(cache_cp);
free_mount_group_list();
flush_cache_ents();
kmem_cache_destroy(cache_slab);
destroy_workqueue(dfscache_wq);
cifs_dbg(FYI, "%s: destroyed DFS referral cache\n", __func__);
}
/* Update a cache entry with the new referral in @refs */
static int update_cache_entry_locked(struct cache_entry *ce, const struct dfs_info3_param *refs,
int numrefs)
{
struct cache_dfs_tgt *target;
char *th = NULL;
int rc;
WARN_ON(!rwsem_is_locked(&htable_rw_lock));
target = READ_ONCE(ce->tgthint);
if (target) {
th = kstrdup(target->name, GFP_ATOMIC);
if (!th)
return -ENOMEM;
}
free_tgts(ce);
ce->numtgts = 0;
rc = copy_ref_data(refs, numrefs, ce, th);
kfree(th);
return rc;
}
static int get_dfs_referral(const unsigned int xid, struct cifs_ses *ses, const char *path,
struct dfs_info3_param **refs, int *numrefs)
{
int rc;
int i;
*refs = NULL;
*numrefs = 0;
if (!ses || !ses->server || !ses->server->ops->get_dfs_refer)
return -EOPNOTSUPP;
if (unlikely(!cache_cp))
return -EINVAL;
cifs_dbg(FYI, "%s: ipc=%s referral=%s\n", __func__, ses->tcon_ipc->tree_name, path);
rc = ses->server->ops->get_dfs_refer(xid, ses, path, refs, numrefs, cache_cp,
NO_MAP_UNI_RSVD);
if (!rc) {
struct dfs_info3_param *ref = *refs;
for (i = 0; i < *numrefs; i++)
convert_delimiter(ref[i].path_name, '\\');
}
return rc;
}
/*
* Find, create or update a DFS cache entry.
*
* If the entry wasn't found, it will create a new one. Or if it was found but
* expired, then it will update the entry accordingly.
*
* For interlinks, cifs_mount() and expand_dfs_referral() are supposed to
* handle them properly.
*
* On success, return entry with acquired lock for reading, otherwise error ptr.
*/
static struct cache_entry *cache_refresh_path(const unsigned int xid,
struct cifs_ses *ses,
const char *path,
bool force_refresh)
{
struct dfs_info3_param *refs = NULL;
struct cache_entry *ce;
int numrefs = 0;
int rc;
cifs_dbg(FYI, "%s: search path: %s\n", __func__, path);
down_read(&htable_rw_lock);
ce = lookup_cache_entry(path);
if (!IS_ERR(ce)) {
if (!force_refresh && !cache_entry_expired(ce))
return ce;
} else if (PTR_ERR(ce) != -ENOENT) {
up_read(&htable_rw_lock);
return ce;
}
/*
* Unlock shared access as we don't want to hold any locks while getting
* a new referral. The @ses used for performing the I/O could be
* reconnecting and it acquires @htable_rw_lock to look up the dfs cache
* in order to failover -- if necessary.
*/
up_read(&htable_rw_lock);
/*
* Either the entry was not found, or it is expired, or it is a forced
* refresh.
* Request a new DFS referral in order to create or update a cache entry.
*/
rc = get_dfs_referral(xid, ses, path, &refs, &numrefs);
if (rc) {
ce = ERR_PTR(rc);
goto out;
}
dump_refs(refs, numrefs);
down_write(&htable_rw_lock);
/* Re-check as another task might have it added or refreshed already */
ce = lookup_cache_entry(path);
if (!IS_ERR(ce)) {
if (force_refresh || cache_entry_expired(ce)) {
rc = update_cache_entry_locked(ce, refs, numrefs);
if (rc)
ce = ERR_PTR(rc);
}
} else if (PTR_ERR(ce) == -ENOENT) {
ce = add_cache_entry_locked(refs, numrefs);
}
if (IS_ERR(ce)) {
up_write(&htable_rw_lock);
goto out;
}
downgrade_write(&htable_rw_lock);
out:
free_dfs_info_array(refs, numrefs);
return ce;
}
/*
* Set up a DFS referral from a given cache entry.
*
* Must be called with htable_rw_lock held.
*/
static int setup_referral(const char *path, struct cache_entry *ce,
struct dfs_info3_param *ref, const char *target)
{
int rc;
cifs_dbg(FYI, "%s: set up new ref\n", __func__);
memset(ref, 0, sizeof(*ref));
ref->path_name = kstrdup(path, GFP_ATOMIC);
if (!ref->path_name)
return -ENOMEM;
ref->node_name = kstrdup(target, GFP_ATOMIC);
if (!ref->node_name) {
rc = -ENOMEM;
goto err_free_path;
}
ref->path_consumed = ce->path_consumed;
ref->ttl = ce->ttl;
ref->server_type = ce->srvtype;
ref->ref_flag = ce->ref_flags;
ref->flags = ce->hdr_flags;
return 0;
err_free_path:
kfree(ref->path_name);
ref->path_name = NULL;
return rc;
}
/* Return target list of a DFS cache entry */
static int get_targets(struct cache_entry *ce, struct dfs_cache_tgt_list *tl)
{
int rc;
struct list_head *head = &tl->tl_list;
struct cache_dfs_tgt *t;
struct dfs_cache_tgt_iterator *it, *nit;
memset(tl, 0, sizeof(*tl));
INIT_LIST_HEAD(head);
list_for_each_entry(t, &ce->tlist, list) {
it = kzalloc(sizeof(*it), GFP_ATOMIC);
if (!it) {
rc = -ENOMEM;
goto err_free_it;
}
it->it_name = kstrdup(t->name, GFP_ATOMIC);
if (!it->it_name) {
kfree(it);
rc = -ENOMEM;
goto err_free_it;
}
it->it_path_consumed = t->path_consumed;
if (READ_ONCE(ce->tgthint) == t)
list_add(&it->it_list, head);
else
list_add_tail(&it->it_list, head);
}
tl->tl_numtgts = ce->numtgts;
return 0;
err_free_it:
list_for_each_entry_safe(it, nit, head, it_list) {
list_del(&it->it_list);
kfree(it->it_name);
kfree(it);
}
return rc;
}
/**
* dfs_cache_find - find a DFS cache entry
*
* If it doesn't find the cache entry, then it will get a DFS referral
* for @path and create a new entry.
*
* In case the cache entry exists but expired, it will get a DFS referral
* for @path and then update the respective cache entry.
*
* These parameters are passed down to the get_dfs_refer() call if it
* needs to be issued:
* @xid: syscall xid
* @ses: smb session to issue the request on
* @cp: codepage
* @remap: path character remapping type
* @path: path to lookup in DFS referral cache.
*
* @ref: when non-NULL, store single DFS referral result in it.
* @tgt_list: when non-NULL, store complete DFS target list in it.
*
* Return zero if the target was found, otherwise non-zero.
*/
int dfs_cache_find(const unsigned int xid, struct cifs_ses *ses, const struct nls_table *cp,
int remap, const char *path, struct dfs_info3_param *ref,
struct dfs_cache_tgt_list *tgt_list)
{
int rc;
const char *npath;
struct cache_entry *ce;
npath = dfs_cache_canonical_path(path, cp, remap);
if (IS_ERR(npath))
return PTR_ERR(npath);
ce = cache_refresh_path(xid, ses, npath, false);
if (IS_ERR(ce)) {
rc = PTR_ERR(ce);
goto out_free_path;
}
if (ref)
rc = setup_referral(path, ce, ref, get_tgt_name(ce));
else
rc = 0;
if (!rc && tgt_list)
rc = get_targets(ce, tgt_list);
up_read(&htable_rw_lock);
out_free_path:
kfree(npath);
return rc;
}
/**
* dfs_cache_noreq_find - find a DFS cache entry without sending any requests to
* the currently connected server.
*
* NOTE: This function will neither update a cache entry in case it was
* expired, nor create a new cache entry if @path hasn't been found. It heavily
* relies on an existing cache entry.
*
* @path: canonical DFS path to lookup in the DFS referral cache.
* @ref: when non-NULL, store single DFS referral result in it.
* @tgt_list: when non-NULL, store complete DFS target list in it.
*
* Return 0 if successful.
* Return -ENOENT if the entry was not found.
* Return non-zero for other errors.
*/
int dfs_cache_noreq_find(const char *path, struct dfs_info3_param *ref,