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 "fs_context.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 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;
};
struct vol_info {
char *fullpath;
spinlock_t ctx_lock;
struct smb3_fs_context ctx;
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->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->ref_flags, ce->hdr_flags,
IS_INTERLINK_SET(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,
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,
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_INTERLINK_SET(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_MEM_RECLAIM, 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_nlsc = 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 inline unsigned int cache_entry_hash(const void *data, int size)
{
unsigned int h;
h = jhash(data, size, 0);
return h & (CACHE_HTABLE_SIZE - 1);
}
/* Check whether second path component of @path is SYSVOL or NETLOGON */
static inline bool is_sysvol_or_netlogon(const char *path)
{
const char *s;
char sep = path[0];
s = strchr(path + 1, sep) + 1;
return !strncasecmp(s, "sysvol", strlen("sysvol")) ||
!strncasecmp(s, "netlogon", strlen("netlogon"));
}
/* Return target hint of a DFS cache entry */
static inline char *get_tgt_name(const struct cache_entry *ce)
{
struct cache_dfs_tgt *t = 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 = kstrndup(name, strlen(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)
{
int i;
ce->ttl = refs[0].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++;
}
ce->tgthint = list_first_entry_or_null(&ce->tlist,
struct cache_dfs_tgt, list);
return 0;
}
/* Allocate a new cache entry */
static struct cache_entry *alloc_cache_entry(const char *path,
const 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 = kstrndup(path, strlen(path), GFP_KERNEL);
if (!ce->path) {
kmem_cache_free(cache_slab, ce);
return ERR_PTR(-ENOMEM);
}
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;
}
/* Must be called with htable_rw_lock held */
static void remove_oldest_entry(void)
{
int i;
struct cache_entry *ce;
struct cache_entry *to_del = NULL;
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 int add_cache_entry(const char *path, unsigned int hash,
struct dfs_info3_param *refs, int numrefs)
{
struct cache_entry *ce;
ce = alloc_cache_entry(path, refs, numrefs);
if (IS_ERR(ce))
return PTR_ERR(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);
down_write(&htable_rw_lock);
hlist_add_head(&ce->hlist, &cache_htable[hash]);
dump_ce(ce);
up_write(&htable_rw_lock);
return 0;
}
static struct cache_entry *__lookup_cache_entry(const char *path)
{
struct cache_entry *ce;
unsigned int h;
bool found = false;
h = cache_entry_hash(path, strlen(path));
hlist_for_each_entry(ce, &cache_htable[h], hlist) {
if (!strcasecmp(path, ce->path)) {
found = true;
dump_ce(ce);
break;
}
}
if (!found)
ce = ERR_PTR(-ENOENT);
return ce;
}
/*
* Find a DFS cache entry in hash table and optionally check prefix path against
* @path.
* Use whole path components in the match.
* Must be called with htable_rw_lock held.
*
* Return ERR_PTR(-ENOENT) if the entry is not found.
*/
static struct cache_entry *lookup_cache_entry(const char *path, unsigned int *hash)
{
struct cache_entry *ce = ERR_PTR(-ENOENT);
unsigned int h;
int cnt = 0;
char *npath;
char *s, *e;
char sep;
npath = kstrndup(path, strlen(path), GFP_KERNEL);
if (!npath)
return ERR_PTR(-ENOMEM);
s = npath;
sep = *npath;
while ((s = strchr(s, sep)) && ++cnt < 3)
s++;
if (cnt < 3) {
h = cache_entry_hash(path, strlen(path));
ce = __lookup_cache_entry(path);
goto out;
}
/*
* 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".
*/
h = cache_entry_hash(npath, strlen(npath));
e = npath + strlen(npath) - 1;
while (e > s) {
char tmp;
/* skip separators */
while (e > s && *e == sep)
e--;
if (e == s)
goto out;
tmp = *(e+1);
*(e+1) = 0;
ce = __lookup_cache_entry(npath);
if (!IS_ERR(ce)) {
h = cache_entry_hash(npath, strlen(npath));
break;
}
*(e+1) = tmp;
/* backward until separator */
while (e > s && *e != sep)
e--;
}
out:
if (hash)
*hash = h;
kfree(npath);
return ce;
}
static void __vol_release(struct vol_info *vi)
{
kfree(vi->fullpath);
kfree(vi->mntdata);
smb3_cleanup_fs_context_contents(&vi->ctx);
kfree(vi);
}
static void vol_release(struct kref *kref)
{
struct vol_info *vi = container_of(kref, struct vol_info, refcnt);
spin_lock(&vol_list_lock);
list_del(&vi->list);
spin_unlock(&vol_list_lock);
__vol_release(vi);
}
static inline void free_vol_list(void)
{
struct vol_info *vi, *nvi;
list_for_each_entry_safe(vi, nvi, &vol_list, list) {
list_del_init(&vi->list);
__vol_release(vi);
}
}
/**
* dfs_cache_destroy - destroy DFS referral cache
*/
void dfs_cache_destroy(void)
{
cancel_delayed_work_sync(&refresh_task);
unload_nls(cache_nlsc);
free_vol_list();
flush_cache_ents();
kmem_cache_destroy(cache_slab);
destroy_workqueue(dfscache_wq);
cifs_dbg(FYI, "%s: destroyed DFS referral cache\n", __func__);
}
/* Must be called with htable_rw_lock held */
static int __update_cache_entry(const char *path,
const struct dfs_info3_param *refs,
int numrefs)
{
int rc;
struct cache_entry *ce;
char *s, *th = NULL;
ce = lookup_cache_entry(path, NULL);
if (IS_ERR(ce))
return PTR_ERR(ce);
if (ce->tgthint) {
s = ce->tgthint->name;
th = kstrndup(s, strlen(s), 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 struct nls_table *nls_codepage, int remap,
const char *path, struct dfs_info3_param **refs,
int *numrefs)
{
cifs_dbg(FYI, "%s: get an DFS referral for %s\n", __func__, path);
if (!ses || !ses->server || !ses->server->ops->get_dfs_refer)
return -EOPNOTSUPP;
if (unlikely(!nls_codepage))
return -EINVAL;
*refs = NULL;
*numrefs = 0;
return ses->server->ops->get_dfs_refer(xid, ses, path, refs, numrefs,
nls_codepage, remap);
}
/* Update an expired cache entry by getting a new DFS referral from server */
static int update_cache_entry(const char *path,
const struct dfs_info3_param *refs,
int numrefs)
{
int rc;
down_write(&htable_rw_lock);
rc = __update_cache_entry(path, refs, numrefs);
up_write(&htable_rw_lock);
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_dfs_mount() and expand_dfs_referral() are supposed to
* handle them properly.
*/
static int __dfs_cache_find(const unsigned int xid, struct cifs_ses *ses,
const struct nls_table *nls_codepage, int remap,
const char *path, bool noreq)
{
int rc;
unsigned int hash;
struct cache_entry *ce;
struct dfs_info3_param *refs = NULL;
int numrefs = 0;
bool newent = false;
cifs_dbg(FYI, "%s: search path: %s\n", __func__, path);
down_read(&htable_rw_lock);
ce = lookup_cache_entry(path, &hash);
/*
* If @noreq is set, no requests will be sent to the server. Just return
* the cache entry.
*/
if (noreq) {
up_read(&htable_rw_lock);
return PTR_ERR_OR_ZERO(ce);
}
if (!IS_ERR(ce)) {
if (!cache_entry_expired(ce)) {
dump_ce(ce);
up_read(&htable_rw_lock);
return 0;
}
} else {
newent = true;
}
up_read(&htable_rw_lock);
/*
* No entry was found.
*
* Request a new DFS referral in order to create a new cache entry, or
* updating an existing one.
*/
rc = get_dfs_referral(xid, ses, nls_codepage, remap, path,
&refs, &numrefs);
if (rc)
return rc;
dump_refs(refs, numrefs);
if (!newent) {
rc = update_cache_entry(path, refs, numrefs);
goto out_free_refs;
}
if (atomic_read(&cache_count) >= CACHE_MAX_ENTRIES) {
cifs_dbg(FYI, "%s: reached max cache size (%d)\n",
__func__, CACHE_MAX_ENTRIES);
down_write(&htable_rw_lock);
remove_oldest_entry();
up_write(&htable_rw_lock);
}
rc = add_cache_entry(path, hash, refs, numrefs);
if (!rc)
atomic_inc(&cache_count);
out_free_refs:
free_dfs_info_array(refs, numrefs);
return rc;
}
/*
* 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 = kstrndup(path, strlen(path), GFP_ATOMIC);
if (!ref->path_name)
return -ENOMEM;
ref->node_name = kstrndup(target, strlen(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 = kstrndup(t->name, strlen(t->name), GFP_ATOMIC);
if (!it->it_name) {
kfree(it);
rc = -ENOMEM;
goto err_free_it;
}
it->it_path_consumed = t->path_consumed;
if (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) {
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
* @nls_codepage: charset conversion
* @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 *nls_codepage, int remap,
const char *path, struct dfs_info3_param *ref,
struct dfs_cache_tgt_list *tgt_list)
{
int rc;
char *npath;
struct cache_entry *ce;
rc = get_normalized_path(path, &npath);
if (rc)
return rc;
rc = __dfs_cache_find(xid, ses, nls_codepage, remap, npath, false);
if (rc)
goto out_free_path;
down_read(&htable_rw_lock);
ce = lookup_cache_entry(npath, NULL);
if (IS_ERR(ce)) {
up_read(&htable_rw_lock);
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:
free_normalized_path(path, 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: 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,
struct dfs_cache_tgt_list *tgt_list)
{
int rc;
char *npath;
struct cache_entry *ce;
rc = get_normalized_path(path, &npath);
if (rc)
return rc;
cifs_dbg(FYI, "%s: path: %s\n", __func__, npath);
down_read(&htable_rw_lock);
ce = lookup_cache_entry(npath, NULL);
if (IS_ERR(ce)) {
rc = PTR_ERR(ce);
goto out_unlock;
}
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);
out_unlock:
up_read(&htable_rw_lock);
free_normalized_path(path, npath);
return rc;
}
/**
* dfs_cache_update_tgthint - update target hint of 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.
*
* @xid: syscall id
* @ses: smb session
* @nls_codepage: charset conversion
* @remap: type of character remapping for paths
* @path: path to lookup in DFS referral cache.
* @it: DFS target iterator
*
* Return zero if the target hint was updated successfully, otherwise non-zero.
*/
int dfs_cache_update_tgthint(const unsigned int xid, struct cifs_ses *ses,
const struct nls_table *nls_codepage, int remap,
const char *path,
const struct dfs_cache_tgt_iterator *it)
{
int rc;
char *npath;
struct cache_entry *ce;
struct cache_dfs_tgt *t;
rc = get_normalized_path(path, &npath);
if (rc)
return rc;
cifs_dbg(FYI, "%s: update target hint - path: %s\n", __func__, npath);
rc = __dfs_cache_find(xid, ses, nls_codepage, remap, npath, false);
if (rc)
goto out_free_path;
down_write(&htable_rw_lock);
ce = lookup_cache_entry(npath, NULL);
if (IS_ERR(ce)) {
rc = PTR_ERR(ce);
goto out_unlock;
}
t = ce->tgthint;
if (likely(!strcasecmp(it->it_name, t->name)))
goto out_unlock;
list_for_each_entry(t, &ce->tlist, list) {
if (!strcasecmp(t->name, it->it_name)) {
ce->tgthint = t;
cifs_dbg(FYI, "%s: new target hint: %s\n", __func__,
it->it_name);
break;
}
}
out_unlock:
up_write(&htable_rw_lock);
out_free_path:
free_normalized_path(path, npath);
return rc;
}
/**
* dfs_cache_noreq_update_tgthint - update target hint of 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: path to lookup in DFS referral cache.
* @it: target iterator which contains the target hint to update the cache
* entry with.
*
* Return zero if the target hint was updated successfully, otherwise non-zero.
*/
int dfs_cache_noreq_update_tgthint(const char *path,
const struct dfs_cache_tgt_iterator *it)
{
int rc;
char *npath;
struct cache_entry *ce;
struct cache_dfs_tgt *t;
if (!it)
return -EINVAL;
rc = get_normalized_path(path, &npath);
if (rc)
return rc;
cifs_dbg(FYI, "%s: path: %s\n", __func__, npath);
down_write(&htable_rw_lock);
ce = lookup_cache_entry(npath, NULL);
if (IS_ERR(ce)) {
rc = PTR_ERR(ce);
goto out_unlock;
}
rc = 0;
t = ce->tgthint;
if (unlikely(!strcasecmp(it->it_name, t->name)))
goto out_unlock;
list_for_each_entry(t, &ce->tlist, list) {
if (!strcasecmp(t->name, it->it_name)) {
ce->tgthint = t;
cifs_dbg(FYI, "%s: new target hint: %s\n", __func__,
it->it_name);
break;
}
}
out_unlock:
up_write(&htable_rw_lock);
free_normalized_path(path, npath);
return rc;
}
/**
* dfs_cache_get_tgt_referral - returns a DFS referral (@ref) from a given
* target iterator (@it).
*
* @path: path to lookup in DFS referral cache.
* @it: DFS target iterator.
* @ref: DFS referral pointer to set up the gathered information.
*
* Return zero if the DFS referral was set up correctly, otherwise non-zero.
*/
int dfs_cache_get_tgt_referral(const char *path,
const struct dfs_cache_tgt_iterator *it,
struct dfs_info3_param *ref)
{
int rc;
char *npath;
struct cache_entry *ce;
if (!it || !ref)
return -EINVAL;
rc = get_normalized_path(path, &npath);
if (rc)
return rc;
cifs_dbg(FYI, "%s: path: %s\n", __func__, npath);
down_read(&htable_rw_lock);
ce = lookup_cache_entry(npath, NULL);
if (IS_ERR(ce)) {
rc = PTR_ERR(ce);
goto out_unlock;
}
cifs_dbg(FYI, "%s: target name: %s\n", __func__, it->it_name);
rc = setup_referral(path, ce, ref, it->it_name);
out_unlock:
up_read(&htable_rw_lock);
free_normalized_path(path, npath);
return rc;
}
/**
* dfs_cache_add_vol - add a cifs context during mount() that will be handled by
* DFS cache refresh worker.
*
* @mntdata: mount data.
* @ctx: cifs context.
* @fullpath: origin full path.
*
* Return zero if context was set up correctly, otherwise non-zero.
*/
int dfs_cache_add_vol(char *mntdata, struct smb3_fs_context *ctx, const char *fullpath)
{
int rc;
struct vol_info *vi;
if (!ctx || !fullpath || !mntdata)
return -EINVAL;
cifs_dbg(FYI, "%s: fullpath: %s\n", __func__, fullpath);
vi = kzalloc(sizeof(*vi), GFP_KERNEL);
if (!vi)
return -ENOMEM;
vi->fullpath = kstrndup(fullpath, strlen(fullpath), GFP_KERNEL);
if (!vi->fullpath) {
rc = -ENOMEM;
goto err_free_vi;
}
rc = smb3_fs_context_dup(&vi->ctx, ctx);
if (rc)
goto err_free_fullpath;
vi->mntdata = mntdata;
spin_lock_init(&vi->ctx_lock);
kref_init(&vi->refcnt);
spin_lock(&vol_list_lock);
list_add_tail(&vi->list, &vol_list);
spin_unlock(&vol_list_lock);
return 0;
err_free_fullpath:
kfree(vi->fullpath);
err_free_vi:
kfree(vi);
return rc;
}
/* Must be called with vol_list_lock held */
static struct vol_info *find_vol(const char *fullpath)
{
struct vol_info *vi;
list_for_each_entry(vi, &vol_list, list) {
cifs_dbg(FYI, "%s: vi->fullpath: %s\n", __func__, vi->fullpath);
if (!strcasecmp(vi->fullpath, fullpath))
return vi;
}
return ERR_PTR(-ENOENT);
}
/**
* dfs_cache_update_vol - update vol info in DFS cache after failover
*
* @fullpath: fullpath to look up in volume list.
* @server: TCP ses pointer.
*
* Return zero if volume was updated, otherwise non-zero.
*/
int dfs_cache_update_vol(const char *fullpath, struct TCP_Server_Info *server)
{
struct vol_info *vi;
if (!fullpath || !server)
return -EINVAL;
cifs_dbg(FYI, "%s: fullpath: %s\n", __func__, fullpath);
spin_lock(&vol_list_lock);
vi = find_vol(fullpath);
if (IS_ERR(vi)) {
spin_unlock(&vol_list_lock);
return PTR_ERR(vi);
}
kref_get(&vi->refcnt);
spin_unlock(&vol_list_lock);
cifs_dbg(FYI, "%s: updating volume info\n", __func__);
spin_lock(&vi->ctx_lock);
memcpy(&vi->ctx.dstaddr, &server->dstaddr,
sizeof(vi->ctx.dstaddr));
spin_unlock(&vi->ctx_lock);
kref_put(&vi->refcnt, vol_release);
return 0;
}
/**
* dfs_cache_del_vol - remove volume info in DFS cache during umount()
*
* @fullpath: fullpath to look up in volume list.
*/
void dfs_cache_del_vol(const char *fullpath)
{
struct vol_info *vi;
if (!fullpath || !*fullpath)
return;
cifs_dbg(FYI, "%s: fullpath: %s\n", __func__, fullpath);
spin_lock(&vol_list_lock);
vi = find_vol(fullpath);
spin_unlock(&vol_list_lock);
if (!IS_ERR(vi))
kref_put(&vi->refcnt, vol_release);
}
/**
* dfs_cache_get_tgt_share - parse a DFS target
*
* @path: DFS full path
* @it: DFS target iterator.
* @share: tree name.
* @prefix: prefix path.
*
* Return zero if target was parsed correctly, otherwise non-zero.
*/
int dfs_cache_get_tgt_share(char *path, const struct dfs_cache_tgt_iterator *it,
char **share, char **prefix)
{
char *s, sep, *p;
size_t len;
size_t plen1, plen2;
if (!it || !path || !share || !prefix || strlen(path) < it->it_path_consumed)
return -EINVAL;
*share = NULL;
*prefix = NULL;
sep = it->it_name[0];
if (sep != '\\' && sep != '/')
return -EINVAL;
s = strchr(it->it_name + 1, sep);
if (!s)
return -EINVAL;
/* point to prefix in target node */
s = strchrnul(s + 1, sep);
/* extract target share */
*share = kstrndup(it->it_name, s - it->it_name, GFP_KERNEL);
if (!*share)
return -ENOMEM;
/* skip separator */
if (*s)
s++;
/* point to prefix in DFS path */
p = path + it->it_path_consumed;
if (*p == sep)
p++;
/* merge prefix paths from DFS path and target node */
plen1 = it->it_name + strlen(it->it_name) - s;
plen2 = path + strlen(path) - p;
if (plen1 || plen2) {
len = plen1 + plen2 + 2;
*prefix = kmalloc(len, GFP_KERNEL);
if (!*prefix) {
kfree(*share);
*share = NULL;
return -ENOMEM;
}
if (plen1)
scnprintf(*prefix, len, "%.*s%c%.*s", (int)plen1, s, sep, (int)plen2, p);
else
strscpy(*prefix, p, len);
}
return 0;
}
/* Get all tcons that are within a DFS namespace and can be refreshed */
static void get_tcons(struct TCP_Server_Info *server, struct list_head *head)
{
struct cifs_ses *ses;
struct cifs_tcon *tcon;
INIT_LIST_HEAD(head);
spin_lock(&cifs_tcp_ses_lock);
list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {
if (!tcon->need_reconnect && !tcon->need_reopen_files &&
tcon->dfs_path) {
tcon->tc_count++;
list_add_tail(&tcon->ulist, head);
}
}
if (ses->tcon_ipc && !ses->tcon_ipc->need_reconnect &&
ses->tcon_ipc->dfs_path) {
list_add_tail(&ses->tcon_ipc->ulist, head);
}
}
spin_unlock(&cifs_tcp_ses_lock);
}
static bool is_dfs_link(const char *path)
{
char *s;
s = strchr(path + 1, '\\');
if (!s)
return false;
return !!strchr(s + 1, '\\');
}
static char *get_dfs_root(const char *path)
{
char *s, *npath;
s = strchr(path + 1, '\\');
if (!s)
return ERR_PTR(-EINVAL);
s = strchr(s + 1, '\\');
if (!s)
return ERR_PTR(-EINVAL);
npath = kstrndup(path, s - path, GFP_KERNEL);
if (!npath)
return ERR_PTR(-ENOMEM);
return npath;
}
static inline void put_tcp_server(struct TCP_Server_Info *server)
{
cifs_put_tcp_session(server, 0);
}
static struct TCP_Server_Info *get_tcp_server(struct smb3_fs_context *ctx)
{
struct TCP_Server_Info *server;
server = cifs_find_tcp_session(ctx);
if (IS_ERR_OR_NULL(server))
return NULL;
spin_lock(&GlobalMid_Lock);
if (server->tcpStatus != CifsGood) {
spin_unlock(&GlobalMid_Lock);
put_tcp_server(server);
return NULL;
}
spin_unlock(&GlobalMid_Lock);
return server;
}
/* Find root SMB session out of a DFS link path */
static struct cifs_ses *find_root_ses(struct vol_info *vi,
struct cifs_tcon *tcon,
const char *path)
{
char *rpath;
int rc;
struct cache_entry *ce;
struct dfs_info3_param ref = {0};
char *mdata = NULL, *devname = NULL;
struct TCP_Server_Info *server;
struct cifs_ses *ses;
struct smb3_fs_context ctx = {NULL};
rpath = get_dfs_root(path);
if (IS_ERR(rpath))
return ERR_CAST(rpath);
down_read(&htable_rw_lock);
ce = lookup_cache_entry(rpath, NULL);
if (IS_ERR(ce)) {
up_read(&htable_rw_lock);
ses = ERR_CAST(ce);
goto out;
}
rc = setup_referral(path, ce, &ref, get_tgt_name(ce));
if (rc) {
up_read(&htable_rw_lock);
ses = ERR_PTR(rc);
goto out;
}
up_read(&htable_rw_lock);
mdata = cifs_compose_mount_options(vi->mntdata, rpath, &ref,
&devname);
free_dfs_info_param(&ref);
if (IS_ERR(mdata)) {
ses = ERR_CAST(mdata);
mdata = NULL;
goto out;
}
rc = cifs_setup_volume_info(&ctx, NULL, devname);
if (rc) {
ses = ERR_PTR(rc);
goto out;
}
server = get_tcp_server(&ctx);
if (!server) {
ses = ERR_PTR(-EHOSTDOWN);
goto out;
}
ses = cifs_get_smb_ses(server, &ctx);
out:
smb3_cleanup_fs_context_contents(&ctx);
kfree(mdata);
kfree(rpath);
kfree(devname);
return ses;
}
/* Refresh DFS cache entry from a given tcon */
static int refresh_tcon(struct vol_info *vi, struct cifs_tcon *tcon)
{
int rc = 0;
unsigned int xid;
char *path, *npath;
struct cache_entry *ce;
struct cifs_ses *root_ses = NULL, *ses;
struct dfs_info3_param *refs = NULL;
int numrefs = 0;
xid = get_xid();
path = tcon->dfs_path + 1;
rc = get_normalized_path(path, &npath);
if (rc)
goto out_free_xid;
down_read(&htable_rw_lock);
ce = lookup_cache_entry(npath, NULL);
if (IS_ERR(ce)) {
rc = PTR_ERR(ce);
up_read(&htable_rw_lock);
goto out_free_path;
}
if (!cache_entry_expired(ce)) {
up_read(&htable_rw_lock);
goto out_free_path;
}
up_read(&htable_rw_lock);
/* If it's a DFS Link, then use root SMB session for refreshing it */
if (is_dfs_link(npath)) {
ses = root_ses = find_root_ses(vi, tcon, npath);
if (IS_ERR(ses)) {
rc = PTR_ERR(ses);
root_ses = NULL;
goto out_free_path;
}
} else {
ses = tcon->ses;
}
rc = get_dfs_referral(xid, ses, cache_nlsc, tcon->remap, npath, &refs,
&numrefs);
if (!rc) {
dump_refs(refs, numrefs);
rc = update_cache_entry(npath, refs, numrefs);
free_dfs_info_array(refs, numrefs);
}
if (root_ses)
cifs_put_smb_ses(root_ses);
out_free_path:
free_normalized_path(path, npath);
out_free_xid:
free_xid(xid);
return rc;
}
/*
* Worker that will refresh DFS cache based on lowest TTL value from a DFS
* referral.
*/
static void refresh_cache_worker(struct work_struct *work)
{
struct vol_info *vi, *nvi;
struct TCP_Server_Info *server;
LIST_HEAD(vols);
LIST_HEAD(tcons);
struct cifs_tcon *tcon, *ntcon;
int rc;
/*
* Find SMB volumes that are eligible (server->tcpStatus == CifsGood)
* for refreshing.
*/
spin_lock(&vol_list_lock);
list_for_each_entry(vi, &vol_list, list) {
server = get_tcp_server(&vi->ctx);
if (!server)
continue;
kref_get(&vi->refcnt);
list_add_tail(&vi->rlist, &vols);
put_tcp_server(server);
}
spin_unlock(&vol_list_lock);
/* Walk through all TCONs and refresh any expired cache entry */
list_for_each_entry_safe(vi, nvi, &vols, rlist) {
spin_lock(&vi->ctx_lock);
server = get_tcp_server(&vi->ctx);
spin_unlock(&vi->ctx_lock);
if (!server)
goto next_vol;
get_tcons(server, &tcons);
rc = 0;
list_for_each_entry_safe(tcon, ntcon, &tcons, ulist) {
/*
* Skip tcp server if any of its tcons failed to refresh
* (possibily due to reconnects).
*/
if (!rc)
rc = refresh_tcon(vi, tcon);
list_del_init(&tcon->ulist);
cifs_put_tcon(tcon);
}
put_tcp_server(server);
next_vol:
list_del_init(&vi->rlist);
kref_put(&vi->refcnt, vol_release);
}
spin_lock(&cache_ttl_lock);
queue_delayed_work(dfscache_wq, &refresh_task, cache_ttl * HZ);
spin_unlock(&cache_ttl_lock);
}
