1 // SPDX-License-Identifier: GPL-2.0
3 * DFS referral cache routines
5 * Copyright (c) 2018-2019 Paulo Alcantara <palcantara@suse.de>
8 #include <linux/jhash.h>
9 #include <linux/ktime.h>
10 #include <linux/slab.h>
11 #include <linux/proc_fs.h>
12 #include <linux/nls.h>
13 #include <linux/workqueue.h>
14 #include <linux/uuid.h>
17 #include "smb2proto.h"
18 #include "cifsproto.h"
19 #include "cifs_debug.h"
20 #include "cifs_unicode.h"
23 #include "dfs_cache.h"
25 #define CACHE_HTABLE_SIZE 32
26 #define CACHE_MAX_ENTRIES 64
27 #define CACHE_MIN_TTL 120 /* 2 minutes */
29 #define IS_INTERLINK_SET(v) ((v) & (DFSREF_REFERRAL_SERVER | \
30 DFSREF_STORAGE_SERVER))
32 struct cache_dfs_tgt {
35 struct list_head list;
39 struct hlist_node hlist;
41 int hdr_flags; /* RESP_GET_DFS_REFERRAL.ReferralHeaderFlags */
42 int ttl; /* DFS_REREFERRAL_V3.TimeToLive */
43 int srvtype; /* DFS_REREFERRAL_V3.ServerType */
44 int ref_flags; /* DFS_REREFERRAL_V3.ReferralEntryFlags */
45 struct timespec64 etime;
46 int path_consumed; /* RESP_GET_DFS_REFERRAL.PathConsumed */
48 struct list_head tlist;
49 struct cache_dfs_tgt *tgthint;
52 /* List of referral server sessions per dfs mount */
54 struct list_head list;
56 struct cifs_ses *sessions[CACHE_MAX_ENTRIES];
59 struct list_head refresh_list;
63 static struct kmem_cache *cache_slab __read_mostly;
64 static struct workqueue_struct *dfscache_wq __read_mostly;
67 static DEFINE_SPINLOCK(cache_ttl_lock);
69 static struct nls_table *cache_cp;
72 * Number of entries in the cache
74 static atomic_t cache_count;
76 static struct hlist_head cache_htable[CACHE_HTABLE_SIZE];
77 static DECLARE_RWSEM(htable_rw_lock);
79 static LIST_HEAD(mount_group_list);
80 static DEFINE_MUTEX(mount_group_list_lock);
82 static void refresh_cache_worker(struct work_struct *work);
84 static DECLARE_DELAYED_WORK(refresh_task, refresh_cache_worker);
86 static void get_ipc_unc(const char *ref_path, char *ipc, size_t ipclen)
91 extract_unc_hostname(ref_path, &host, &len);
92 scnprintf(ipc, ipclen, "\\\\%.*s\\IPC$", (int)len, host);
95 static struct cifs_ses *find_ipc_from_server_path(struct cifs_ses **ses, const char *path)
97 char unc[SERVER_NAME_LENGTH + sizeof("//x/IPC$")] = {0};
99 get_ipc_unc(path, unc, sizeof(unc));
100 for (; *ses; ses++) {
101 if (!strcasecmp(unc, (*ses)->tcon_ipc->treeName))
104 return ERR_PTR(-ENOENT);
107 static void __mount_group_release(struct mount_group *mg)
111 for (i = 0; i < mg->num_sessions; i++)
112 cifs_put_smb_ses(mg->sessions[i]);
116 static void mount_group_release(struct kref *kref)
118 struct mount_group *mg = container_of(kref, struct mount_group, refcount);
120 mutex_lock(&mount_group_list_lock);
122 mutex_unlock(&mount_group_list_lock);
123 __mount_group_release(mg);
126 static struct mount_group *find_mount_group_locked(const uuid_t *id)
128 struct mount_group *mg;
130 list_for_each_entry(mg, &mount_group_list, list) {
131 if (uuid_equal(&mg->id, id))
134 return ERR_PTR(-ENOENT);
137 static struct mount_group *__get_mount_group_locked(const uuid_t *id)
139 struct mount_group *mg;
141 mg = find_mount_group_locked(id);
145 mg = kmalloc(sizeof(*mg), GFP_KERNEL);
147 return ERR_PTR(-ENOMEM);
148 kref_init(&mg->refcount);
149 uuid_copy(&mg->id, id);
150 mg->num_sessions = 0;
151 spin_lock_init(&mg->lock);
152 list_add(&mg->list, &mount_group_list);
156 static struct mount_group *get_mount_group(const uuid_t *id)
158 struct mount_group *mg;
160 mutex_lock(&mount_group_list_lock);
161 mg = __get_mount_group_locked(id);
163 kref_get(&mg->refcount);
164 mutex_unlock(&mount_group_list_lock);
169 static void free_mount_group_list(void)
171 struct mount_group *mg, *tmp_mg;
173 list_for_each_entry_safe(mg, tmp_mg, &mount_group_list, list) {
174 list_del_init(&mg->list);
175 __mount_group_release(mg);
180 * dfs_cache_canonical_path - get a canonical DFS path
184 * @remap: mapping type
186 * Return canonical path if success, otherwise error.
188 char *dfs_cache_canonical_path(const char *path, const struct nls_table *cp, int remap)
194 if (!path || strlen(path) < 3 || (*path != '\\' && *path != '/'))
195 return ERR_PTR(-EINVAL);
197 if (unlikely(strcmp(cp->charset, cache_cp->charset))) {
198 tmp = (char *)cifs_strndup_to_utf16(path, strlen(path), &plen, cp, remap);
200 cifs_dbg(VFS, "%s: failed to convert path to utf16\n", __func__);
201 return ERR_PTR(-EINVAL);
204 npath = cifs_strndup_from_utf16(tmp, plen, true, cache_cp);
208 cifs_dbg(VFS, "%s: failed to convert path from utf16\n", __func__);
209 return ERR_PTR(-EINVAL);
212 npath = kstrdup(path, GFP_KERNEL);
214 return ERR_PTR(-ENOMEM);
216 convert_delimiter(npath, '\\');
220 static inline bool cache_entry_expired(const struct cache_entry *ce)
222 struct timespec64 ts;
224 ktime_get_coarse_real_ts64(&ts);
225 return timespec64_compare(&ts, &ce->etime) >= 0;
228 static inline void free_tgts(struct cache_entry *ce)
230 struct cache_dfs_tgt *t, *n;
232 list_for_each_entry_safe(t, n, &ce->tlist, list) {
239 static inline void flush_cache_ent(struct cache_entry *ce)
241 hlist_del_init(&ce->hlist);
244 atomic_dec(&cache_count);
245 kmem_cache_free(cache_slab, ce);
248 static void flush_cache_ents(void)
252 for (i = 0; i < CACHE_HTABLE_SIZE; i++) {
253 struct hlist_head *l = &cache_htable[i];
254 struct hlist_node *n;
255 struct cache_entry *ce;
257 hlist_for_each_entry_safe(ce, n, l, hlist) {
258 if (!hlist_unhashed(&ce->hlist))
265 * dfs cache /proc file
267 static int dfscache_proc_show(struct seq_file *m, void *v)
270 struct cache_entry *ce;
271 struct cache_dfs_tgt *t;
273 seq_puts(m, "DFS cache\n---------\n");
275 down_read(&htable_rw_lock);
276 for (i = 0; i < CACHE_HTABLE_SIZE; i++) {
277 struct hlist_head *l = &cache_htable[i];
279 hlist_for_each_entry(ce, l, hlist) {
280 if (hlist_unhashed(&ce->hlist))
284 "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",
285 ce->path, ce->srvtype == DFS_TYPE_ROOT ? "root" : "link",
286 ce->ttl, ce->etime.tv_nsec, ce->ref_flags, ce->hdr_flags,
287 IS_INTERLINK_SET(ce->hdr_flags) ? "yes" : "no",
288 ce->path_consumed, cache_entry_expired(ce) ? "yes" : "no");
290 list_for_each_entry(t, &ce->tlist, list) {
291 seq_printf(m, " %s%s\n",
293 ce->tgthint == t ? " (target hint)" : "");
297 up_read(&htable_rw_lock);
302 static ssize_t dfscache_proc_write(struct file *file, const char __user *buffer,
303 size_t count, loff_t *ppos)
308 rc = get_user(c, buffer);
315 cifs_dbg(FYI, "clearing dfs cache\n");
317 down_write(&htable_rw_lock);
319 up_write(&htable_rw_lock);
324 static int dfscache_proc_open(struct inode *inode, struct file *file)
326 return single_open(file, dfscache_proc_show, NULL);
329 const struct proc_ops dfscache_proc_ops = {
330 .proc_open = dfscache_proc_open,
331 .proc_read = seq_read,
332 .proc_lseek = seq_lseek,
333 .proc_release = single_release,
334 .proc_write = dfscache_proc_write,
337 #ifdef CONFIG_CIFS_DEBUG2
338 static inline void dump_tgts(const struct cache_entry *ce)
340 struct cache_dfs_tgt *t;
342 cifs_dbg(FYI, "target list:\n");
343 list_for_each_entry(t, &ce->tlist, list) {
344 cifs_dbg(FYI, " %s%s\n", t->name,
345 ce->tgthint == t ? " (target hint)" : "");
349 static inline void dump_ce(const struct cache_entry *ce)
351 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",
353 ce->srvtype == DFS_TYPE_ROOT ? "root" : "link", ce->ttl,
355 ce->hdr_flags, ce->ref_flags,
356 IS_INTERLINK_SET(ce->hdr_flags) ? "yes" : "no",
358 cache_entry_expired(ce) ? "yes" : "no");
362 static inline void dump_refs(const struct dfs_info3_param *refs, int numrefs)
366 cifs_dbg(FYI, "DFS referrals returned by the server:\n");
367 for (i = 0; i < numrefs; i++) {
368 const struct dfs_info3_param *ref = &refs[i];
373 "path_consumed: %d\n"
374 "server_type: 0x%x\n"
379 ref->flags, ref->path_consumed, ref->server_type,
380 ref->ref_flag, ref->path_name, ref->node_name,
381 ref->ttl, ref->ttl / 60);
387 #define dump_refs(r, n)
391 * dfs_cache_init - Initialize DFS referral cache.
393 * Return zero if initialized successfully, otherwise non-zero.
395 int dfs_cache_init(void)
400 dfscache_wq = alloc_workqueue("cifs-dfscache", WQ_FREEZABLE | WQ_UNBOUND, 1);
404 cache_slab = kmem_cache_create("cifs_dfs_cache",
405 sizeof(struct cache_entry), 0,
406 SLAB_HWCACHE_ALIGN, NULL);
412 for (i = 0; i < CACHE_HTABLE_SIZE; i++)
413 INIT_HLIST_HEAD(&cache_htable[i]);
415 atomic_set(&cache_count, 0);
416 cache_cp = load_nls("utf8");
418 cache_cp = load_nls_default();
420 cifs_dbg(FYI, "%s: initialized DFS referral cache\n", __func__);
424 destroy_workqueue(dfscache_wq);
428 static int cache_entry_hash(const void *data, int size, unsigned int *hash)
431 const unsigned char *s = data;
435 for (i = 0; i < size; i += clen) {
436 clen = cache_cp->char2uni(&s[i], size - i, &c);
437 if (unlikely(clen < 0)) {
438 cifs_dbg(VFS, "%s: can't convert char\n", __func__);
442 h = jhash(&c, sizeof(c), h);
444 *hash = h % CACHE_HTABLE_SIZE;
448 /* Return target hint of a DFS cache entry */
449 static inline char *get_tgt_name(const struct cache_entry *ce)
451 struct cache_dfs_tgt *t = ce->tgthint;
453 return t ? t->name : ERR_PTR(-ENOENT);
456 /* Return expire time out of a new entry's TTL */
457 static inline struct timespec64 get_expire_time(int ttl)
459 struct timespec64 ts = {
463 struct timespec64 now;
465 ktime_get_coarse_real_ts64(&now);
466 return timespec64_add(now, ts);
469 /* Allocate a new DFS target */
470 static struct cache_dfs_tgt *alloc_target(const char *name, int path_consumed)
472 struct cache_dfs_tgt *t;
474 t = kmalloc(sizeof(*t), GFP_ATOMIC);
476 return ERR_PTR(-ENOMEM);
477 t->name = kstrdup(name, GFP_ATOMIC);
480 return ERR_PTR(-ENOMEM);
482 t->path_consumed = path_consumed;
483 INIT_LIST_HEAD(&t->list);
488 * Copy DFS referral information to a cache entry and conditionally update
491 static int copy_ref_data(const struct dfs_info3_param *refs, int numrefs,
492 struct cache_entry *ce, const char *tgthint)
496 ce->ttl = max_t(int, refs[0].ttl, CACHE_MIN_TTL);
497 ce->etime = get_expire_time(ce->ttl);
498 ce->srvtype = refs[0].server_type;
499 ce->hdr_flags = refs[0].flags;
500 ce->ref_flags = refs[0].ref_flag;
501 ce->path_consumed = refs[0].path_consumed;
503 for (i = 0; i < numrefs; i++) {
504 struct cache_dfs_tgt *t;
506 t = alloc_target(refs[i].node_name, refs[i].path_consumed);
511 if (tgthint && !strcasecmp(t->name, tgthint)) {
512 list_add(&t->list, &ce->tlist);
515 list_add_tail(&t->list, &ce->tlist);
520 ce->tgthint = list_first_entry_or_null(&ce->tlist,
521 struct cache_dfs_tgt, list);
526 /* Allocate a new cache entry */
527 static struct cache_entry *alloc_cache_entry(struct dfs_info3_param *refs, int numrefs)
529 struct cache_entry *ce;
532 ce = kmem_cache_zalloc(cache_slab, GFP_KERNEL);
534 return ERR_PTR(-ENOMEM);
536 ce->path = refs[0].path_name;
537 refs[0].path_name = NULL;
539 INIT_HLIST_NODE(&ce->hlist);
540 INIT_LIST_HEAD(&ce->tlist);
542 rc = copy_ref_data(refs, numrefs, ce, NULL);
545 kmem_cache_free(cache_slab, ce);
551 static void remove_oldest_entry_locked(void)
554 struct cache_entry *ce;
555 struct cache_entry *to_del = NULL;
557 WARN_ON(!rwsem_is_locked(&htable_rw_lock));
559 for (i = 0; i < CACHE_HTABLE_SIZE; i++) {
560 struct hlist_head *l = &cache_htable[i];
562 hlist_for_each_entry(ce, l, hlist) {
563 if (hlist_unhashed(&ce->hlist))
565 if (!to_del || timespec64_compare(&ce->etime,
572 cifs_dbg(FYI, "%s: no entry to remove\n", __func__);
576 cifs_dbg(FYI, "%s: removing entry\n", __func__);
578 flush_cache_ent(to_del);
581 /* Add a new DFS cache entry */
582 static int add_cache_entry_locked(struct dfs_info3_param *refs, int numrefs)
585 struct cache_entry *ce;
588 WARN_ON(!rwsem_is_locked(&htable_rw_lock));
590 if (atomic_read(&cache_count) >= CACHE_MAX_ENTRIES) {
591 cifs_dbg(FYI, "%s: reached max cache size (%d)\n", __func__, CACHE_MAX_ENTRIES);
592 remove_oldest_entry_locked();
595 rc = cache_entry_hash(refs[0].path_name, strlen(refs[0].path_name), &hash);
599 ce = alloc_cache_entry(refs, numrefs);
603 spin_lock(&cache_ttl_lock);
606 queue_delayed_work(dfscache_wq, &refresh_task, cache_ttl * HZ);
608 cache_ttl = min_t(int, cache_ttl, ce->ttl);
609 mod_delayed_work(dfscache_wq, &refresh_task, cache_ttl * HZ);
611 spin_unlock(&cache_ttl_lock);
613 hlist_add_head(&ce->hlist, &cache_htable[hash]);
616 atomic_inc(&cache_count);
621 /* Check if two DFS paths are equal. @s1 and @s2 are expected to be in @cache_cp's charset */
622 static bool dfs_path_equal(const char *s1, int len1, const char *s2, int len2)
630 for (i = 0; i < len1; i += l1) {
631 l1 = cache_cp->char2uni(&s1[i], len1 - i, &c1);
632 l2 = cache_cp->char2uni(&s2[i], len2 - i, &c2);
633 if (unlikely(l1 < 0 && l2 < 0)) {
641 if (cifs_toupper(c1) != cifs_toupper(c2))
647 static struct cache_entry *__lookup_cache_entry(const char *path, unsigned int hash, int len)
649 struct cache_entry *ce;
651 hlist_for_each_entry(ce, &cache_htable[hash], hlist) {
652 if (dfs_path_equal(ce->path, strlen(ce->path), path, len)) {
657 return ERR_PTR(-EEXIST);
661 * Find a DFS cache entry in hash table and optionally check prefix path against normalized @path.
663 * Use whole path components in the match. Must be called with htable_rw_lock held.
665 * Return ERR_PTR(-EEXIST) if the entry is not found.
667 static struct cache_entry *lookup_cache_entry(const char *path)
669 struct cache_entry *ce;
671 const char *s = path, *e;
676 while ((s = strchr(s, sep)) && ++cnt < 3)
680 rc = cache_entry_hash(path, strlen(path), &hash);
683 return __lookup_cache_entry(path, hash, strlen(path));
686 * Handle paths that have more than two path components and are a complete prefix of the DFS
687 * referral request path (@path).
689 * See MS-DFSC 3.2.5.5 "Receiving a Root Referral Request or Link Referral Request".
691 e = path + strlen(path) - 1;
695 /* skip separators */
696 while (e > s && *e == sep)
702 rc = cache_entry_hash(path, len, &hash);
705 ce = __lookup_cache_entry(path, hash, len);
709 /* backward until separator */
710 while (e > s && *e != sep)
713 return ERR_PTR(-EEXIST);
717 * dfs_cache_destroy - destroy DFS referral cache
719 void dfs_cache_destroy(void)
721 cancel_delayed_work_sync(&refresh_task);
722 unload_nls(cache_cp);
723 free_mount_group_list();
725 kmem_cache_destroy(cache_slab);
726 destroy_workqueue(dfscache_wq);
728 cifs_dbg(FYI, "%s: destroyed DFS referral cache\n", __func__);
731 /* Update a cache entry with the new referral in @refs */
732 static int update_cache_entry_locked(struct cache_entry *ce, const struct dfs_info3_param *refs,
738 WARN_ON(!rwsem_is_locked(&htable_rw_lock));
741 s = ce->tgthint->name;
742 th = kstrdup(s, GFP_ATOMIC);
750 rc = copy_ref_data(refs, numrefs, ce, th);
757 static int get_dfs_referral(const unsigned int xid, struct cifs_ses *ses, const char *path,
758 struct dfs_info3_param **refs, int *numrefs)
763 cifs_dbg(FYI, "%s: get an DFS referral for %s\n", __func__, path);
768 if (!ses || !ses->server || !ses->server->ops->get_dfs_refer)
770 if (unlikely(!cache_cp))
773 rc = ses->server->ops->get_dfs_refer(xid, ses, path, refs, numrefs, cache_cp,
776 struct dfs_info3_param *ref = *refs;
778 for (i = 0; i < *numrefs; i++)
779 convert_delimiter(ref[i].path_name, '\\');
785 * Find, create or update a DFS cache entry.
787 * If the entry wasn't found, it will create a new one. Or if it was found but
788 * expired, then it will update the entry accordingly.
790 * For interlinks, cifs_mount() and expand_dfs_referral() are supposed to
791 * handle them properly.
793 static int cache_refresh_path(const unsigned int xid, struct cifs_ses *ses, const char *path)
796 struct cache_entry *ce;
797 struct dfs_info3_param *refs = NULL;
801 cifs_dbg(FYI, "%s: search path: %s\n", __func__, path);
803 down_write(&htable_rw_lock);
805 ce = lookup_cache_entry(path);
807 if (!cache_entry_expired(ce)) {
809 up_write(&htable_rw_lock);
817 * Either the entry was not found, or it is expired.
818 * Request a new DFS referral in order to create or update a cache entry.
820 rc = get_dfs_referral(xid, ses, path, &refs, &numrefs);
824 dump_refs(refs, numrefs);
827 rc = update_cache_entry_locked(ce, refs, numrefs);
831 rc = add_cache_entry_locked(refs, numrefs);
834 up_write(&htable_rw_lock);
835 free_dfs_info_array(refs, numrefs);
840 * Set up a DFS referral from a given cache entry.
842 * Must be called with htable_rw_lock held.
844 static int setup_referral(const char *path, struct cache_entry *ce,
845 struct dfs_info3_param *ref, const char *target)
849 cifs_dbg(FYI, "%s: set up new ref\n", __func__);
851 memset(ref, 0, sizeof(*ref));
853 ref->path_name = kstrdup(path, GFP_ATOMIC);
857 ref->node_name = kstrdup(target, GFP_ATOMIC);
858 if (!ref->node_name) {
863 ref->path_consumed = ce->path_consumed;
865 ref->server_type = ce->srvtype;
866 ref->ref_flag = ce->ref_flags;
867 ref->flags = ce->hdr_flags;
872 kfree(ref->path_name);
873 ref->path_name = NULL;
877 /* Return target list of a DFS cache entry */
878 static int get_targets(struct cache_entry *ce, struct dfs_cache_tgt_list *tl)
881 struct list_head *head = &tl->tl_list;
882 struct cache_dfs_tgt *t;
883 struct dfs_cache_tgt_iterator *it, *nit;
885 memset(tl, 0, sizeof(*tl));
886 INIT_LIST_HEAD(head);
888 list_for_each_entry(t, &ce->tlist, list) {
889 it = kzalloc(sizeof(*it), GFP_ATOMIC);
895 it->it_name = kstrdup(t->name, GFP_ATOMIC);
901 it->it_path_consumed = t->path_consumed;
903 if (ce->tgthint == t)
904 list_add(&it->it_list, head);
906 list_add_tail(&it->it_list, head);
909 tl->tl_numtgts = ce->numtgts;
914 list_for_each_entry_safe(it, nit, head, it_list) {
922 * dfs_cache_find - find a DFS cache entry
924 * If it doesn't find the cache entry, then it will get a DFS referral
925 * for @path and create a new entry.
927 * In case the cache entry exists but expired, it will get a DFS referral
928 * for @path and then update the respective cache entry.
930 * These parameters are passed down to the get_dfs_refer() call if it
931 * needs to be issued:
933 * @ses: smb session to issue the request on
935 * @remap: path character remapping type
936 * @path: path to lookup in DFS referral cache.
938 * @ref: when non-NULL, store single DFS referral result in it.
939 * @tgt_list: when non-NULL, store complete DFS target list in it.
941 * Return zero if the target was found, otherwise non-zero.
943 int dfs_cache_find(const unsigned int xid, struct cifs_ses *ses, const struct nls_table *cp,
944 int remap, const char *path, struct dfs_info3_param *ref,
945 struct dfs_cache_tgt_list *tgt_list)
949 struct cache_entry *ce;
951 npath = dfs_cache_canonical_path(path, cp, remap);
953 return PTR_ERR(npath);
955 rc = cache_refresh_path(xid, ses, npath);
959 down_read(&htable_rw_lock);
961 ce = lookup_cache_entry(npath);
963 up_read(&htable_rw_lock);
969 rc = setup_referral(path, ce, ref, get_tgt_name(ce));
973 rc = get_targets(ce, tgt_list);
975 up_read(&htable_rw_lock);
983 * dfs_cache_noreq_find - find a DFS cache entry without sending any requests to
984 * the currently connected server.
986 * NOTE: This function will neither update a cache entry in case it was
987 * expired, nor create a new cache entry if @path hasn't been found. It heavily
988 * relies on an existing cache entry.
990 * @path: canonical DFS path to lookup in the DFS referral cache.
991 * @ref: when non-NULL, store single DFS referral result in it.
992 * @tgt_list: when non-NULL, store complete DFS target list in it.
994 * Return 0 if successful.
995 * Return -ENOENT if the entry was not found.
996 * Return non-zero for other errors.
998 int dfs_cache_noreq_find(const char *path, struct dfs_info3_param *ref,
999 struct dfs_cache_tgt_list *tgt_list)
1002 struct cache_entry *ce;
1004 cifs_dbg(FYI, "%s: path: %s\n", __func__, path);
1006 down_read(&htable_rw_lock);
1008 ce = lookup_cache_entry(path);
1015 rc = setup_referral(path, ce, ref, get_tgt_name(ce));
1018 if (!rc && tgt_list)
1019 rc = get_targets(ce, tgt_list);
1022 up_read(&htable_rw_lock);
1027 * dfs_cache_update_tgthint - update target hint of a DFS cache entry
1029 * If it doesn't find the cache entry, then it will get a DFS referral for @path
1030 * and create a new entry.
1032 * In case the cache entry exists but expired, it will get a DFS referral
1033 * for @path and then update the respective cache entry.
1038 * @remap: type of character remapping for paths
1039 * @path: path to lookup in DFS referral cache
1040 * @it: DFS target iterator
1042 * Return zero if the target hint was updated successfully, otherwise non-zero.
1044 int dfs_cache_update_tgthint(const unsigned int xid, struct cifs_ses *ses,
1045 const struct nls_table *cp, int remap, const char *path,
1046 const struct dfs_cache_tgt_iterator *it)
1050 struct cache_entry *ce;
1051 struct cache_dfs_tgt *t;
1053 npath = dfs_cache_canonical_path(path, cp, remap);
1055 return PTR_ERR(npath);
1057 cifs_dbg(FYI, "%s: update target hint - path: %s\n", __func__, npath);
1059 rc = cache_refresh_path(xid, ses, npath);
1063 down_write(&htable_rw_lock);
1065 ce = lookup_cache_entry(npath);
1073 if (likely(!strcasecmp(it->it_name, t->name)))
1076 list_for_each_entry(t, &ce->tlist, list) {
1077 if (!strcasecmp(t->name, it->it_name)) {
1079 cifs_dbg(FYI, "%s: new target hint: %s\n", __func__,
1086 up_write(&htable_rw_lock);
1093 * dfs_cache_noreq_update_tgthint - update target hint of a DFS cache entry
1094 * without sending any requests to the currently connected server.
1096 * NOTE: This function will neither update a cache entry in case it was
1097 * expired, nor create a new cache entry if @path hasn't been found. It heavily
1098 * relies on an existing cache entry.
1100 * @path: canonical DFS path to lookup in DFS referral cache.
1101 * @it: target iterator which contains the target hint to update the cache
1104 * Return zero if the target hint was updated successfully, otherwise non-zero.
1106 int dfs_cache_noreq_update_tgthint(const char *path, const struct dfs_cache_tgt_iterator *it)
1109 struct cache_entry *ce;
1110 struct cache_dfs_tgt *t;
1115 cifs_dbg(FYI, "%s: path: %s\n", __func__, path);
1117 down_write(&htable_rw_lock);
1119 ce = lookup_cache_entry(path);
1128 if (unlikely(!strcasecmp(it->it_name, t->name)))
1131 list_for_each_entry(t, &ce->tlist, list) {
1132 if (!strcasecmp(t->name, it->it_name)) {
1134 cifs_dbg(FYI, "%s: new target hint: %s\n", __func__,
1141 up_write(&htable_rw_lock);
1146 * dfs_cache_get_tgt_referral - returns a DFS referral (@ref) from a given
1147 * target iterator (@it).
1149 * @path: canonical DFS path to lookup in DFS referral cache.
1150 * @it: DFS target iterator.
1151 * @ref: DFS referral pointer to set up the gathered information.
1153 * Return zero if the DFS referral was set up correctly, otherwise non-zero.
1155 int dfs_cache_get_tgt_referral(const char *path, const struct dfs_cache_tgt_iterator *it,
1156 struct dfs_info3_param *ref)
1159 struct cache_entry *ce;
1164 cifs_dbg(FYI, "%s: path: %s\n", __func__, path);
1166 down_read(&htable_rw_lock);
1168 ce = lookup_cache_entry(path);
1174 cifs_dbg(FYI, "%s: target name: %s\n", __func__, it->it_name);
1176 rc = setup_referral(path, ce, ref, it->it_name);
1179 up_read(&htable_rw_lock);
1184 * dfs_cache_add_refsrv_session - add SMB session of referral server
1186 * @mount_id: mount group uuid to lookup.
1187 * @ses: reference counted SMB session of referral server.
1189 void dfs_cache_add_refsrv_session(const uuid_t *mount_id, struct cifs_ses *ses)
1191 struct mount_group *mg;
1193 if (WARN_ON_ONCE(!mount_id || uuid_is_null(mount_id) || !ses))
1196 mg = get_mount_group(mount_id);
1197 if (WARN_ON_ONCE(IS_ERR(mg)))
1200 spin_lock(&mg->lock);
1201 if (mg->num_sessions < ARRAY_SIZE(mg->sessions))
1202 mg->sessions[mg->num_sessions++] = ses;
1203 spin_unlock(&mg->lock);
1204 kref_put(&mg->refcount, mount_group_release);
1208 * dfs_cache_put_refsrv_sessions - put all referral server sessions
1210 * Put all SMB sessions from the given mount group id.
1212 * @mount_id: mount group uuid to lookup.
1214 void dfs_cache_put_refsrv_sessions(const uuid_t *mount_id)
1216 struct mount_group *mg;
1218 if (!mount_id || uuid_is_null(mount_id))
1221 mutex_lock(&mount_group_list_lock);
1222 mg = find_mount_group_locked(mount_id);
1224 mutex_unlock(&mount_group_list_lock);
1227 mutex_unlock(&mount_group_list_lock);
1228 kref_put(&mg->refcount, mount_group_release);
1232 * dfs_cache_get_tgt_share - parse a DFS target
1234 * @path: DFS full path
1235 * @it: DFS target iterator.
1236 * @share: tree name.
1237 * @prefix: prefix path.
1239 * Return zero if target was parsed correctly, otherwise non-zero.
1241 int dfs_cache_get_tgt_share(char *path, const struct dfs_cache_tgt_iterator *it, char **share,
1246 size_t plen1, plen2;
1248 if (!it || !path || !share || !prefix || strlen(path) < it->it_path_consumed)
1254 sep = it->it_name[0];
1255 if (sep != '\\' && sep != '/')
1258 s = strchr(it->it_name + 1, sep);
1262 /* point to prefix in target node */
1263 s = strchrnul(s + 1, sep);
1265 /* extract target share */
1266 *share = kstrndup(it->it_name, s - it->it_name, GFP_KERNEL);
1270 /* skip separator */
1273 /* point to prefix in DFS path */
1274 p = path + it->it_path_consumed;
1278 /* merge prefix paths from DFS path and target node */
1279 plen1 = it->it_name + strlen(it->it_name) - s;
1280 plen2 = path + strlen(path) - p;
1281 if (plen1 || plen2) {
1282 len = plen1 + plen2 + 2;
1283 *prefix = kmalloc(len, GFP_KERNEL);
1290 scnprintf(*prefix, len, "%.*s%c%.*s", (int)plen1, s, sep, (int)plen2, p);
1292 strscpy(*prefix, p, len);
1298 * Refresh all active dfs mounts regardless of whether they are in cache or not.
1299 * (cache can be cleared)
1301 static void refresh_mounts(struct cifs_ses **sessions)
1303 struct TCP_Server_Info *server;
1304 struct cifs_ses *ses;
1305 struct cifs_tcon *tcon, *ntcon;
1306 struct list_head tcons;
1309 INIT_LIST_HEAD(&tcons);
1311 spin_lock(&cifs_tcp_ses_lock);
1312 list_for_each_entry(server, &cifs_tcp_ses_list, tcp_ses_list) {
1313 list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
1314 list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {
1315 if (tcon->dfs_path) {
1317 list_add_tail(&tcon->ulist, &tcons);
1322 spin_unlock(&cifs_tcp_ses_lock);
1324 list_for_each_entry_safe(tcon, ntcon, &tcons, ulist) {
1325 const char *path = tcon->dfs_path + 1;
1326 struct cache_entry *ce;
1327 struct dfs_info3_param *refs = NULL;
1329 bool needs_refresh = false;
1332 list_del_init(&tcon->ulist);
1334 ses = find_ipc_from_server_path(sessions, path);
1338 down_read(&htable_rw_lock);
1339 ce = lookup_cache_entry(path);
1340 needs_refresh = IS_ERR(ce) || cache_entry_expired(ce);
1341 up_read(&htable_rw_lock);
1347 rc = get_dfs_referral(xid, ses, path, &refs, &numrefs);
1350 /* Create or update a cache entry with the new referral */
1352 down_write(&htable_rw_lock);
1353 ce = lookup_cache_entry(path);
1355 add_cache_entry_locked(refs, numrefs);
1356 else if (cache_entry_expired(ce))
1357 update_cache_entry_locked(ce, refs, numrefs);
1358 up_write(&htable_rw_lock);
1362 free_dfs_info_array(refs, numrefs);
1363 cifs_put_tcon(tcon);
1367 static void refresh_cache(struct cifs_ses **sessions)
1370 struct cifs_ses *ses;
1372 char *ref_paths[CACHE_MAX_ENTRIES];
1374 struct cache_entry *ce;
1377 * Refresh all cached entries. Get all new referrals outside critical section to avoid
1378 * starvation while performing SMB2 IOCTL on broken or slow connections.
1380 * The cache entries may cover more paths than the active mounts
1381 * (e.g. domain-based DFS referrals or multi tier DFS setups).
1383 down_read(&htable_rw_lock);
1384 for (i = 0; i < CACHE_HTABLE_SIZE; i++) {
1385 struct hlist_head *l = &cache_htable[i];
1387 hlist_for_each_entry(ce, l, hlist) {
1388 if (count == ARRAY_SIZE(ref_paths))
1390 if (hlist_unhashed(&ce->hlist) || !cache_entry_expired(ce) ||
1391 IS_ERR(find_ipc_from_server_path(sessions, ce->path)))
1393 ref_paths[count++] = kstrdup(ce->path, GFP_ATOMIC);
1398 up_read(&htable_rw_lock);
1400 for (i = 0; i < count; i++) {
1401 char *path = ref_paths[i];
1402 struct dfs_info3_param *refs = NULL;
1409 ses = find_ipc_from_server_path(sessions, path);
1414 rc = get_dfs_referral(xid, ses, path, &refs, &numrefs);
1418 down_write(&htable_rw_lock);
1419 ce = lookup_cache_entry(path);
1421 * We need to re-check it because other tasks might have it deleted or
1424 if (!IS_ERR(ce) && cache_entry_expired(ce))
1425 update_cache_entry_locked(ce, refs, numrefs);
1426 up_write(&htable_rw_lock);
1431 free_dfs_info_array(refs, numrefs);
1436 * Worker that will refresh DFS cache and active mounts based on lowest TTL value from a DFS
1439 static void refresh_cache_worker(struct work_struct *work)
1441 struct list_head mglist;
1442 struct mount_group *mg, *tmp_mg;
1443 struct cifs_ses *sessions[CACHE_MAX_ENTRIES + 1] = {NULL};
1444 int max_sessions = ARRAY_SIZE(sessions) - 1;
1447 INIT_LIST_HEAD(&mglist);
1449 /* Get refereces of mount groups */
1450 mutex_lock(&mount_group_list_lock);
1451 list_for_each_entry(mg, &mount_group_list, list) {
1452 kref_get(&mg->refcount);
1453 list_add(&mg->refresh_list, &mglist);
1455 mutex_unlock(&mount_group_list_lock);
1457 /* Fill in local array with an NULL-terminated list of all referral server sessions */
1458 list_for_each_entry(mg, &mglist, refresh_list) {
1459 if (i >= max_sessions)
1462 spin_lock(&mg->lock);
1463 if (i + mg->num_sessions > max_sessions)
1464 count = max_sessions - i;
1466 count = mg->num_sessions;
1467 memcpy(&sessions[i], mg->sessions, count * sizeof(mg->sessions[0]));
1468 spin_unlock(&mg->lock);
1473 /* Refresh all active mounts and cached entries */
1474 refresh_mounts(sessions);
1475 refresh_cache(sessions);
1478 list_for_each_entry_safe(mg, tmp_mg, &mglist, refresh_list) {
1479 list_del_init(&mg->refresh_list);
1480 kref_put(&mg->refcount, mount_group_release);
1483 spin_lock(&cache_ttl_lock);
1484 queue_delayed_work(dfscache_wq, &refresh_task, cache_ttl * HZ);
1485 spin_unlock(&cache_ttl_lock);