linux/fs/cifs/dfs_cache.c
Paulo Alcantara 5ff2836ed3 cifs: introduce helper for finding referral server to improve DFS target resolution
Some servers seem to mistakenly report different values for
capabilities and share flags, so we can't always rely on those values
to decide whether the resolved target can handle any new DFS
referrals.

Add a new helper is_referral_server() to check if all resolved targets
can handle new DFS referrals by directly looking at the
GET_DFS_REFERRAL.ReferralHeaderFlags value as specified in MS-DFSC
2.2.4 RESP_GET_DFS_REFERRAL in addition to is_tcon_dfs().

Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Cc: stable@vger.kernel.org # 5.11
Signed-off-by: Steve French <stfrench@microsoft.com>
2021-02-25 12:19:15 -06:00

1612 lines
35 KiB
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);
}