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"
22 #include "dns_resolve.h"
24 #include "dfs_cache.h"
26 #define CACHE_HTABLE_SIZE 32
27 #define CACHE_MAX_ENTRIES 64
28 #define CACHE_MIN_TTL 120 /* 2 minutes */
30 #define IS_DFS_INTERLINK(v) (((v) & DFSREF_REFERRAL_SERVER) && !((v) & 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 __mount_group_release(struct mount_group *mg)
90 for (i = 0; i < mg->num_sessions; i++)
91 cifs_put_smb_ses(mg->sessions[i]);
95 static void mount_group_release(struct kref *kref)
97 struct mount_group *mg = container_of(kref, struct mount_group, refcount);
99 mutex_lock(&mount_group_list_lock);
101 mutex_unlock(&mount_group_list_lock);
102 __mount_group_release(mg);
105 static struct mount_group *find_mount_group_locked(const uuid_t *id)
107 struct mount_group *mg;
109 list_for_each_entry(mg, &mount_group_list, list) {
110 if (uuid_equal(&mg->id, id))
113 return ERR_PTR(-ENOENT);
116 static struct mount_group *__get_mount_group_locked(const uuid_t *id)
118 struct mount_group *mg;
120 mg = find_mount_group_locked(id);
124 mg = kmalloc(sizeof(*mg), GFP_KERNEL);
126 return ERR_PTR(-ENOMEM);
127 kref_init(&mg->refcount);
128 uuid_copy(&mg->id, id);
129 mg->num_sessions = 0;
130 spin_lock_init(&mg->lock);
131 list_add(&mg->list, &mount_group_list);
135 static struct mount_group *get_mount_group(const uuid_t *id)
137 struct mount_group *mg;
139 mutex_lock(&mount_group_list_lock);
140 mg = __get_mount_group_locked(id);
142 kref_get(&mg->refcount);
143 mutex_unlock(&mount_group_list_lock);
148 static void free_mount_group_list(void)
150 struct mount_group *mg, *tmp_mg;
152 list_for_each_entry_safe(mg, tmp_mg, &mount_group_list, list) {
153 list_del_init(&mg->list);
154 __mount_group_release(mg);
159 * dfs_cache_canonical_path - get a canonical DFS path
163 * @remap: mapping type
165 * Return canonical path if success, otherwise error.
167 char *dfs_cache_canonical_path(const char *path, const struct nls_table *cp, int remap)
173 if (!path || strlen(path) < 3 || (*path != '\\' && *path != '/'))
174 return ERR_PTR(-EINVAL);
176 if (unlikely(strcmp(cp->charset, cache_cp->charset))) {
177 tmp = (char *)cifs_strndup_to_utf16(path, strlen(path), &plen, cp, remap);
179 cifs_dbg(VFS, "%s: failed to convert path to utf16\n", __func__);
180 return ERR_PTR(-EINVAL);
183 npath = cifs_strndup_from_utf16(tmp, plen, true, cache_cp);
187 cifs_dbg(VFS, "%s: failed to convert path from utf16\n", __func__);
188 return ERR_PTR(-EINVAL);
191 npath = kstrdup(path, GFP_KERNEL);
193 return ERR_PTR(-ENOMEM);
195 convert_delimiter(npath, '\\');
199 static inline bool cache_entry_expired(const struct cache_entry *ce)
201 struct timespec64 ts;
203 ktime_get_coarse_real_ts64(&ts);
204 return timespec64_compare(&ts, &ce->etime) >= 0;
207 static inline void free_tgts(struct cache_entry *ce)
209 struct cache_dfs_tgt *t, *n;
211 list_for_each_entry_safe(t, n, &ce->tlist, list) {
218 static inline void flush_cache_ent(struct cache_entry *ce)
220 hlist_del_init(&ce->hlist);
223 atomic_dec(&cache_count);
224 kmem_cache_free(cache_slab, ce);
227 static void flush_cache_ents(void)
231 for (i = 0; i < CACHE_HTABLE_SIZE; i++) {
232 struct hlist_head *l = &cache_htable[i];
233 struct hlist_node *n;
234 struct cache_entry *ce;
236 hlist_for_each_entry_safe(ce, n, l, hlist) {
237 if (!hlist_unhashed(&ce->hlist))
244 * dfs cache /proc file
246 static int dfscache_proc_show(struct seq_file *m, void *v)
249 struct cache_entry *ce;
250 struct cache_dfs_tgt *t;
252 seq_puts(m, "DFS cache\n---------\n");
254 down_read(&htable_rw_lock);
255 for (i = 0; i < CACHE_HTABLE_SIZE; i++) {
256 struct hlist_head *l = &cache_htable[i];
258 hlist_for_each_entry(ce, l, hlist) {
259 if (hlist_unhashed(&ce->hlist))
263 "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",
264 ce->path, ce->srvtype == DFS_TYPE_ROOT ? "root" : "link",
265 ce->ttl, ce->etime.tv_nsec, ce->hdr_flags, ce->ref_flags,
266 IS_DFS_INTERLINK(ce->hdr_flags) ? "yes" : "no",
267 ce->path_consumed, cache_entry_expired(ce) ? "yes" : "no");
269 list_for_each_entry(t, &ce->tlist, list) {
270 seq_printf(m, " %s%s\n",
272 READ_ONCE(ce->tgthint) == t ? " (target hint)" : "");
276 up_read(&htable_rw_lock);
281 static ssize_t dfscache_proc_write(struct file *file, const char __user *buffer,
282 size_t count, loff_t *ppos)
287 rc = get_user(c, buffer);
294 cifs_dbg(FYI, "clearing dfs cache\n");
296 down_write(&htable_rw_lock);
298 up_write(&htable_rw_lock);
303 static int dfscache_proc_open(struct inode *inode, struct file *file)
305 return single_open(file, dfscache_proc_show, NULL);
308 const struct proc_ops dfscache_proc_ops = {
309 .proc_open = dfscache_proc_open,
310 .proc_read = seq_read,
311 .proc_lseek = seq_lseek,
312 .proc_release = single_release,
313 .proc_write = dfscache_proc_write,
316 #ifdef CONFIG_CIFS_DEBUG2
317 static inline void dump_tgts(const struct cache_entry *ce)
319 struct cache_dfs_tgt *t;
321 cifs_dbg(FYI, "target list:\n");
322 list_for_each_entry(t, &ce->tlist, list) {
323 cifs_dbg(FYI, " %s%s\n", t->name,
324 READ_ONCE(ce->tgthint) == t ? " (target hint)" : "");
328 static inline void dump_ce(const struct cache_entry *ce)
330 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",
332 ce->srvtype == DFS_TYPE_ROOT ? "root" : "link", ce->ttl,
334 ce->hdr_flags, ce->ref_flags,
335 IS_DFS_INTERLINK(ce->hdr_flags) ? "yes" : "no",
337 cache_entry_expired(ce) ? "yes" : "no");
341 static inline void dump_refs(const struct dfs_info3_param *refs, int numrefs)
345 cifs_dbg(FYI, "DFS referrals returned by the server:\n");
346 for (i = 0; i < numrefs; i++) {
347 const struct dfs_info3_param *ref = &refs[i];
352 "path_consumed: %d\n"
353 "server_type: 0x%x\n"
358 ref->flags, ref->path_consumed, ref->server_type,
359 ref->ref_flag, ref->path_name, ref->node_name,
360 ref->ttl, ref->ttl / 60);
366 #define dump_refs(r, n)
370 * dfs_cache_init - Initialize DFS referral cache.
372 * Return zero if initialized successfully, otherwise non-zero.
374 int dfs_cache_init(void)
379 dfscache_wq = alloc_workqueue("cifs-dfscache", WQ_FREEZABLE | WQ_UNBOUND, 1);
383 cache_slab = kmem_cache_create("cifs_dfs_cache",
384 sizeof(struct cache_entry), 0,
385 SLAB_HWCACHE_ALIGN, NULL);
391 for (i = 0; i < CACHE_HTABLE_SIZE; i++)
392 INIT_HLIST_HEAD(&cache_htable[i]);
394 atomic_set(&cache_count, 0);
395 cache_cp = load_nls("utf8");
397 cache_cp = load_nls_default();
399 cifs_dbg(FYI, "%s: initialized DFS referral cache\n", __func__);
403 destroy_workqueue(dfscache_wq);
407 static int cache_entry_hash(const void *data, int size, unsigned int *hash)
410 const unsigned char *s = data;
414 for (i = 0; i < size; i += clen) {
415 clen = cache_cp->char2uni(&s[i], size - i, &c);
416 if (unlikely(clen < 0)) {
417 cifs_dbg(VFS, "%s: can't convert char\n", __func__);
421 h = jhash(&c, sizeof(c), h);
423 *hash = h % CACHE_HTABLE_SIZE;
427 /* Return target hint of a DFS cache entry */
428 static inline char *get_tgt_name(const struct cache_entry *ce)
430 struct cache_dfs_tgt *t = READ_ONCE(ce->tgthint);
432 return t ? t->name : ERR_PTR(-ENOENT);
435 /* Return expire time out of a new entry's TTL */
436 static inline struct timespec64 get_expire_time(int ttl)
438 struct timespec64 ts = {
442 struct timespec64 now;
444 ktime_get_coarse_real_ts64(&now);
445 return timespec64_add(now, ts);
448 /* Allocate a new DFS target */
449 static struct cache_dfs_tgt *alloc_target(const char *name, int path_consumed)
451 struct cache_dfs_tgt *t;
453 t = kmalloc(sizeof(*t), GFP_ATOMIC);
455 return ERR_PTR(-ENOMEM);
456 t->name = kstrdup(name, GFP_ATOMIC);
459 return ERR_PTR(-ENOMEM);
461 t->path_consumed = path_consumed;
462 INIT_LIST_HEAD(&t->list);
467 * Copy DFS referral information to a cache entry and conditionally update
470 static int copy_ref_data(const struct dfs_info3_param *refs, int numrefs,
471 struct cache_entry *ce, const char *tgthint)
473 struct cache_dfs_tgt *target;
476 ce->ttl = max_t(int, refs[0].ttl, CACHE_MIN_TTL);
477 ce->etime = get_expire_time(ce->ttl);
478 ce->srvtype = refs[0].server_type;
479 ce->hdr_flags = refs[0].flags;
480 ce->ref_flags = refs[0].ref_flag;
481 ce->path_consumed = refs[0].path_consumed;
483 for (i = 0; i < numrefs; i++) {
484 struct cache_dfs_tgt *t;
486 t = alloc_target(refs[i].node_name, refs[i].path_consumed);
491 if (tgthint && !strcasecmp(t->name, tgthint)) {
492 list_add(&t->list, &ce->tlist);
495 list_add_tail(&t->list, &ce->tlist);
500 target = list_first_entry_or_null(&ce->tlist, struct cache_dfs_tgt,
502 WRITE_ONCE(ce->tgthint, target);
507 /* Allocate a new cache entry */
508 static struct cache_entry *alloc_cache_entry(struct dfs_info3_param *refs, int numrefs)
510 struct cache_entry *ce;
513 ce = kmem_cache_zalloc(cache_slab, GFP_KERNEL);
515 return ERR_PTR(-ENOMEM);
517 ce->path = refs[0].path_name;
518 refs[0].path_name = NULL;
520 INIT_HLIST_NODE(&ce->hlist);
521 INIT_LIST_HEAD(&ce->tlist);
523 rc = copy_ref_data(refs, numrefs, ce, NULL);
526 kmem_cache_free(cache_slab, ce);
532 static void remove_oldest_entry_locked(void)
535 struct cache_entry *ce;
536 struct cache_entry *to_del = NULL;
538 WARN_ON(!rwsem_is_locked(&htable_rw_lock));
540 for (i = 0; i < CACHE_HTABLE_SIZE; i++) {
541 struct hlist_head *l = &cache_htable[i];
543 hlist_for_each_entry(ce, l, hlist) {
544 if (hlist_unhashed(&ce->hlist))
546 if (!to_del || timespec64_compare(&ce->etime,
553 cifs_dbg(FYI, "%s: no entry to remove\n", __func__);
557 cifs_dbg(FYI, "%s: removing entry\n", __func__);
559 flush_cache_ent(to_del);
562 /* Add a new DFS cache entry */
563 static struct cache_entry *add_cache_entry_locked(struct dfs_info3_param *refs,
567 struct cache_entry *ce;
570 WARN_ON(!rwsem_is_locked(&htable_rw_lock));
572 if (atomic_read(&cache_count) >= CACHE_MAX_ENTRIES) {
573 cifs_dbg(FYI, "%s: reached max cache size (%d)\n", __func__, CACHE_MAX_ENTRIES);
574 remove_oldest_entry_locked();
577 rc = cache_entry_hash(refs[0].path_name, strlen(refs[0].path_name), &hash);
581 ce = alloc_cache_entry(refs, numrefs);
585 spin_lock(&cache_ttl_lock);
588 queue_delayed_work(dfscache_wq, &refresh_task, cache_ttl * HZ);
590 cache_ttl = min_t(int, cache_ttl, ce->ttl);
591 mod_delayed_work(dfscache_wq, &refresh_task, cache_ttl * HZ);
593 spin_unlock(&cache_ttl_lock);
595 hlist_add_head(&ce->hlist, &cache_htable[hash]);
598 atomic_inc(&cache_count);
603 /* Check if two DFS paths are equal. @s1 and @s2 are expected to be in @cache_cp's charset */
604 static bool dfs_path_equal(const char *s1, int len1, const char *s2, int len2)
612 for (i = 0; i < len1; i += l1) {
613 l1 = cache_cp->char2uni(&s1[i], len1 - i, &c1);
614 l2 = cache_cp->char2uni(&s2[i], len2 - i, &c2);
615 if (unlikely(l1 < 0 && l2 < 0)) {
623 if (cifs_toupper(c1) != cifs_toupper(c2))
629 static struct cache_entry *__lookup_cache_entry(const char *path, unsigned int hash, int len)
631 struct cache_entry *ce;
633 hlist_for_each_entry(ce, &cache_htable[hash], hlist) {
634 if (dfs_path_equal(ce->path, strlen(ce->path), path, len)) {
639 return ERR_PTR(-ENOENT);
643 * Find a DFS cache entry in hash table and optionally check prefix path against normalized @path.
645 * Use whole path components in the match. Must be called with htable_rw_lock held.
647 * Return cached entry if successful.
648 * Return ERR_PTR(-ENOENT) if the entry is not found.
649 * Return error ptr otherwise.
651 static struct cache_entry *lookup_cache_entry(const char *path)
653 struct cache_entry *ce;
655 const char *s = path, *e;
660 while ((s = strchr(s, sep)) && ++cnt < 3)
664 rc = cache_entry_hash(path, strlen(path), &hash);
667 return __lookup_cache_entry(path, hash, strlen(path));
670 * Handle paths that have more than two path components and are a complete prefix of the DFS
671 * referral request path (@path).
673 * See MS-DFSC 3.2.5.5 "Receiving a Root Referral Request or Link Referral Request".
675 e = path + strlen(path) - 1;
679 /* skip separators */
680 while (e > s && *e == sep)
686 rc = cache_entry_hash(path, len, &hash);
689 ce = __lookup_cache_entry(path, hash, len);
693 /* backward until separator */
694 while (e > s && *e != sep)
697 return ERR_PTR(-ENOENT);
701 * dfs_cache_destroy - destroy DFS referral cache
703 void dfs_cache_destroy(void)
705 cancel_delayed_work_sync(&refresh_task);
706 unload_nls(cache_cp);
707 free_mount_group_list();
709 kmem_cache_destroy(cache_slab);
710 destroy_workqueue(dfscache_wq);
712 cifs_dbg(FYI, "%s: destroyed DFS referral cache\n", __func__);
715 /* Update a cache entry with the new referral in @refs */
716 static int update_cache_entry_locked(struct cache_entry *ce, const struct dfs_info3_param *refs,
719 struct cache_dfs_tgt *target;
723 WARN_ON(!rwsem_is_locked(&htable_rw_lock));
725 target = READ_ONCE(ce->tgthint);
727 th = kstrdup(target->name, GFP_ATOMIC);
735 rc = copy_ref_data(refs, numrefs, ce, th);
742 static int get_dfs_referral(const unsigned int xid, struct cifs_ses *ses, const char *path,
743 struct dfs_info3_param **refs, int *numrefs)
751 if (!ses || !ses->server || !ses->server->ops->get_dfs_refer)
753 if (unlikely(!cache_cp))
756 cifs_dbg(FYI, "%s: ipc=%s referral=%s\n", __func__, ses->tcon_ipc->tree_name, path);
757 rc = ses->server->ops->get_dfs_refer(xid, ses, path, refs, numrefs, cache_cp,
760 struct dfs_info3_param *ref = *refs;
762 for (i = 0; i < *numrefs; i++)
763 convert_delimiter(ref[i].path_name, '\\');
769 * Find, create or update a DFS cache entry.
771 * If the entry wasn't found, it will create a new one. Or if it was found but
772 * expired, then it will update the entry accordingly.
774 * For interlinks, cifs_mount() and expand_dfs_referral() are supposed to
775 * handle them properly.
777 * On success, return entry with acquired lock for reading, otherwise error ptr.
779 static struct cache_entry *cache_refresh_path(const unsigned int xid,
780 struct cifs_ses *ses,
784 struct dfs_info3_param *refs = NULL;
785 struct cache_entry *ce;
789 cifs_dbg(FYI, "%s: search path: %s\n", __func__, path);
791 down_read(&htable_rw_lock);
793 ce = lookup_cache_entry(path);
795 if (!force_refresh && !cache_entry_expired(ce))
797 } else if (PTR_ERR(ce) != -ENOENT) {
798 up_read(&htable_rw_lock);
803 * Unlock shared access as we don't want to hold any locks while getting
804 * a new referral. The @ses used for performing the I/O could be
805 * reconnecting and it acquires @htable_rw_lock to look up the dfs cache
806 * in order to failover -- if necessary.
808 up_read(&htable_rw_lock);
811 * Either the entry was not found, or it is expired, or it is a forced
813 * Request a new DFS referral in order to create or update a cache entry.
815 rc = get_dfs_referral(xid, ses, path, &refs, &numrefs);
821 dump_refs(refs, numrefs);
823 down_write(&htable_rw_lock);
824 /* Re-check as another task might have it added or refreshed already */
825 ce = lookup_cache_entry(path);
827 if (force_refresh || cache_entry_expired(ce)) {
828 rc = update_cache_entry_locked(ce, refs, numrefs);
832 } else if (PTR_ERR(ce) == -ENOENT) {
833 ce = add_cache_entry_locked(refs, numrefs);
837 up_write(&htable_rw_lock);
841 downgrade_write(&htable_rw_lock);
843 free_dfs_info_array(refs, numrefs);
848 * Set up a DFS referral from a given cache entry.
850 * Must be called with htable_rw_lock held.
852 static int setup_referral(const char *path, struct cache_entry *ce,
853 struct dfs_info3_param *ref, const char *target)
857 cifs_dbg(FYI, "%s: set up new ref\n", __func__);
859 memset(ref, 0, sizeof(*ref));
861 ref->path_name = kstrdup(path, GFP_ATOMIC);
865 ref->node_name = kstrdup(target, GFP_ATOMIC);
866 if (!ref->node_name) {
871 ref->path_consumed = ce->path_consumed;
873 ref->server_type = ce->srvtype;
874 ref->ref_flag = ce->ref_flags;
875 ref->flags = ce->hdr_flags;
880 kfree(ref->path_name);
881 ref->path_name = NULL;
885 /* Return target list of a DFS cache entry */
886 static int get_targets(struct cache_entry *ce, struct dfs_cache_tgt_list *tl)
889 struct list_head *head = &tl->tl_list;
890 struct cache_dfs_tgt *t;
891 struct dfs_cache_tgt_iterator *it, *nit;
893 memset(tl, 0, sizeof(*tl));
894 INIT_LIST_HEAD(head);
896 list_for_each_entry(t, &ce->tlist, list) {
897 it = kzalloc(sizeof(*it), GFP_ATOMIC);
903 it->it_name = kstrdup(t->name, GFP_ATOMIC);
909 it->it_path_consumed = t->path_consumed;
911 if (READ_ONCE(ce->tgthint) == t)
912 list_add(&it->it_list, head);
914 list_add_tail(&it->it_list, head);
917 tl->tl_numtgts = ce->numtgts;
922 list_for_each_entry_safe(it, nit, head, it_list) {
923 list_del(&it->it_list);
931 * dfs_cache_find - find a DFS cache entry
933 * If it doesn't find the cache entry, then it will get a DFS referral
934 * for @path and create a new entry.
936 * In case the cache entry exists but expired, it will get a DFS referral
937 * for @path and then update the respective cache entry.
939 * These parameters are passed down to the get_dfs_refer() call if it
940 * needs to be issued:
942 * @ses: smb session to issue the request on
944 * @remap: path character remapping type
945 * @path: path to lookup in DFS referral cache.
947 * @ref: when non-NULL, store single DFS referral result in it.
948 * @tgt_list: when non-NULL, store complete DFS target list in it.
950 * Return zero if the target was found, otherwise non-zero.
952 int dfs_cache_find(const unsigned int xid, struct cifs_ses *ses, const struct nls_table *cp,
953 int remap, const char *path, struct dfs_info3_param *ref,
954 struct dfs_cache_tgt_list *tgt_list)
958 struct cache_entry *ce;
960 npath = dfs_cache_canonical_path(path, cp, remap);
962 return PTR_ERR(npath);
964 ce = cache_refresh_path(xid, ses, npath, false);
971 rc = setup_referral(path, ce, ref, get_tgt_name(ce));
975 rc = get_targets(ce, tgt_list);
977 up_read(&htable_rw_lock);
985 * dfs_cache_noreq_find - find a DFS cache entry without sending any requests to
986 * the currently connected server.
988 * NOTE: This function will neither update a cache entry in case it was
989 * expired, nor create a new cache entry if @path hasn't been found. It heavily
990 * relies on an existing cache entry.
992 * @path: canonical DFS path to lookup in the DFS referral cache.
993 * @ref: when non-NULL, store single DFS referral result in it.
994 * @tgt_list: when non-NULL, store complete DFS target list in it.
996 * Return 0 if successful.
997 * Return -ENOENT if the entry was not found.
998 * Return non-zero for other errors.
1000 int dfs_cache_noreq_find(const char *path, struct dfs_info3_param *ref,
1001 struct dfs_cache_tgt_list *tgt_list)
1004 struct cache_entry *ce;
1006 cifs_dbg(FYI, "%s: path: %s\n", __func__, path);
1008 down_read(&htable_rw_lock);
1010 ce = lookup_cache_entry(path);
1017 rc = setup_referral(path, ce, ref, get_tgt_name(ce));
1020 if (!rc && tgt_list)
1021 rc = get_targets(ce, tgt_list);
1024 up_read(&htable_rw_lock);
1029 * dfs_cache_update_tgthint - update target hint of a DFS cache entry
1031 * If it doesn't find the cache entry, then it will get a DFS referral for @path
1032 * and create a new entry.
1034 * In case the cache entry exists but expired, it will get a DFS referral
1035 * for @path and then update the respective cache entry.
1040 * @remap: type of character remapping for paths
1041 * @path: path to lookup in DFS referral cache
1042 * @it: DFS target iterator
1044 * Return zero if the target hint was updated successfully, otherwise non-zero.
1046 int dfs_cache_update_tgthint(const unsigned int xid, struct cifs_ses *ses,
1047 const struct nls_table *cp, int remap, const char *path,
1048 const struct dfs_cache_tgt_iterator *it)
1052 struct cache_entry *ce;
1053 struct cache_dfs_tgt *t;
1055 npath = dfs_cache_canonical_path(path, cp, remap);
1057 return PTR_ERR(npath);
1059 cifs_dbg(FYI, "%s: update target hint - path: %s\n", __func__, npath);
1061 ce = cache_refresh_path(xid, ses, npath, false);
1067 t = READ_ONCE(ce->tgthint);
1069 if (likely(!strcasecmp(it->it_name, t->name)))
1072 list_for_each_entry(t, &ce->tlist, list) {
1073 if (!strcasecmp(t->name, it->it_name)) {
1074 WRITE_ONCE(ce->tgthint, t);
1075 cifs_dbg(FYI, "%s: new target hint: %s\n", __func__,
1082 up_read(&htable_rw_lock);
1089 * dfs_cache_noreq_update_tgthint - update target hint of a DFS cache entry
1090 * without sending any requests to the currently connected server.
1092 * NOTE: This function will neither update a cache entry in case it was
1093 * expired, nor create a new cache entry if @path hasn't been found. It heavily
1094 * relies on an existing cache entry.
1096 * @path: canonical DFS path to lookup in DFS referral cache.
1097 * @it: target iterator which contains the target hint to update the cache
1100 * Return zero if the target hint was updated successfully, otherwise non-zero.
1102 void dfs_cache_noreq_update_tgthint(const char *path, const struct dfs_cache_tgt_iterator *it)
1104 struct cache_dfs_tgt *t;
1105 struct cache_entry *ce;
1110 cifs_dbg(FYI, "%s: path: %s\n", __func__, path);
1112 down_read(&htable_rw_lock);
1114 ce = lookup_cache_entry(path);
1118 t = READ_ONCE(ce->tgthint);
1120 if (unlikely(!strcasecmp(it->it_name, t->name)))
1123 list_for_each_entry(t, &ce->tlist, list) {
1124 if (!strcasecmp(t->name, it->it_name)) {
1125 WRITE_ONCE(ce->tgthint, t);
1126 cifs_dbg(FYI, "%s: new target hint: %s\n", __func__,
1133 up_read(&htable_rw_lock);
1137 * dfs_cache_get_tgt_referral - returns a DFS referral (@ref) from a given
1138 * target iterator (@it).
1140 * @path: canonical DFS path to lookup in DFS referral cache.
1141 * @it: DFS target iterator.
1142 * @ref: DFS referral pointer to set up the gathered information.
1144 * Return zero if the DFS referral was set up correctly, otherwise non-zero.
1146 int dfs_cache_get_tgt_referral(const char *path, const struct dfs_cache_tgt_iterator *it,
1147 struct dfs_info3_param *ref)
1150 struct cache_entry *ce;
1155 cifs_dbg(FYI, "%s: path: %s\n", __func__, path);
1157 down_read(&htable_rw_lock);
1159 ce = lookup_cache_entry(path);
1165 cifs_dbg(FYI, "%s: target name: %s\n", __func__, it->it_name);
1167 rc = setup_referral(path, ce, ref, it->it_name);
1170 up_read(&htable_rw_lock);
1175 * dfs_cache_add_refsrv_session - add SMB session of referral server
1177 * @mount_id: mount group uuid to lookup.
1178 * @ses: reference counted SMB session of referral server.
1180 void dfs_cache_add_refsrv_session(const uuid_t *mount_id, struct cifs_ses *ses)
1182 struct mount_group *mg;
1184 if (WARN_ON_ONCE(!mount_id || uuid_is_null(mount_id) || !ses))
1187 mg = get_mount_group(mount_id);
1188 if (WARN_ON_ONCE(IS_ERR(mg)))
1191 spin_lock(&mg->lock);
1192 if (mg->num_sessions < ARRAY_SIZE(mg->sessions))
1193 mg->sessions[mg->num_sessions++] = ses;
1194 spin_unlock(&mg->lock);
1195 kref_put(&mg->refcount, mount_group_release);
1199 * dfs_cache_put_refsrv_sessions - put all referral server sessions
1201 * Put all SMB sessions from the given mount group id.
1203 * @mount_id: mount group uuid to lookup.
1205 void dfs_cache_put_refsrv_sessions(const uuid_t *mount_id)
1207 struct mount_group *mg;
1209 if (!mount_id || uuid_is_null(mount_id))
1212 mutex_lock(&mount_group_list_lock);
1213 mg = find_mount_group_locked(mount_id);
1215 mutex_unlock(&mount_group_list_lock);
1218 mutex_unlock(&mount_group_list_lock);
1219 kref_put(&mg->refcount, mount_group_release);
1222 /* Extract share from DFS target and return a pointer to prefix path or NULL */
1223 static const char *parse_target_share(const char *target, char **share)
1225 const char *s, *seps = "/\\";
1228 s = strpbrk(target + 1, seps);
1230 return ERR_PTR(-EINVAL);
1232 len = strcspn(s + 1, seps);
1234 return ERR_PTR(-EINVAL);
1237 len = s - target + 1;
1238 *share = kstrndup(target, len, GFP_KERNEL);
1240 return ERR_PTR(-ENOMEM);
1243 return s + strspn(s, seps);
1247 * dfs_cache_get_tgt_share - parse a DFS target
1249 * @path: DFS full path
1250 * @it: DFS target iterator.
1251 * @share: tree name.
1252 * @prefix: prefix path.
1254 * Return zero if target was parsed correctly, otherwise non-zero.
1256 int dfs_cache_get_tgt_share(char *path, const struct dfs_cache_tgt_iterator *it, char **share,
1262 const char *target_ppath, *dfsref_ppath;
1263 size_t target_pplen, dfsref_pplen;
1266 if (!it || !path || !share || !prefix || strlen(path) < it->it_path_consumed)
1269 sep = it->it_name[0];
1270 if (sep != '\\' && sep != '/')
1273 target_ppath = parse_target_share(it->it_name, &target_share);
1274 if (IS_ERR(target_ppath))
1275 return PTR_ERR(target_ppath);
1277 /* point to prefix in DFS referral path */
1278 dfsref_ppath = path + it->it_path_consumed;
1279 dfsref_ppath += strspn(dfsref_ppath, "/\\");
1281 target_pplen = strlen(target_ppath);
1282 dfsref_pplen = strlen(dfsref_ppath);
1284 /* merge prefix paths from DFS referral path and target node */
1285 if (target_pplen || dfsref_pplen) {
1286 len = target_pplen + dfsref_pplen + 2;
1287 ppath = kzalloc(len, GFP_KERNEL);
1289 kfree(target_share);
1292 c = strscpy(ppath, target_ppath, len);
1293 if (c && dfsref_pplen)
1295 strlcat(ppath, dfsref_ppath, len);
1297 *share = target_share;
1302 static bool target_share_equal(struct TCP_Server_Info *server, const char *s1, const char *s2)
1304 char unc[sizeof("\\\\") + SERVER_NAME_LENGTH] = {0};
1307 struct sockaddr_storage ss;
1311 if (strcasecmp(s1, s2))
1315 * Resolve share's hostname and check if server address matches. Otherwise just ignore it
1316 * as we could not have upcall to resolve hostname or failed to convert ip address.
1318 extract_unc_hostname(s1, &host, &hostlen);
1319 scnprintf(unc, sizeof(unc), "\\\\%.*s", (int)hostlen, host);
1321 rc = dns_resolve_server_name_to_ip(unc, (struct sockaddr *)&ss, NULL);
1323 cifs_dbg(FYI, "%s: could not resolve %.*s. assuming server address matches.\n",
1324 __func__, (int)hostlen, host);
1328 cifs_server_lock(server);
1329 match = cifs_match_ipaddr((struct sockaddr *)&server->dstaddr, (struct sockaddr *)&ss);
1330 cifs_server_unlock(server);
1336 * Mark dfs tcon for reconnecting when the currently connected tcon does not match any of the new
1337 * target shares in @refs.
1339 static void mark_for_reconnect_if_needed(struct TCP_Server_Info *server,
1340 struct dfs_cache_tgt_list *old_tl,
1341 struct dfs_cache_tgt_list *new_tl)
1343 struct dfs_cache_tgt_iterator *oit, *nit;
1345 for (oit = dfs_cache_get_tgt_iterator(old_tl); oit;
1346 oit = dfs_cache_get_next_tgt(old_tl, oit)) {
1347 for (nit = dfs_cache_get_tgt_iterator(new_tl); nit;
1348 nit = dfs_cache_get_next_tgt(new_tl, nit)) {
1349 if (target_share_equal(server,
1350 dfs_cache_get_tgt_name(oit),
1351 dfs_cache_get_tgt_name(nit)))
1356 cifs_dbg(FYI, "%s: no cached or matched targets. mark dfs share for reconnect.\n", __func__);
1357 cifs_signal_cifsd_for_reconnect(server, true);
1360 /* Refresh dfs referral of tcon and mark it for reconnect if needed */
1361 static int __refresh_tcon(const char *path, struct cifs_tcon *tcon, bool force_refresh)
1363 struct dfs_cache_tgt_list old_tl = DFS_CACHE_TGT_LIST_INIT(old_tl);
1364 struct dfs_cache_tgt_list new_tl = DFS_CACHE_TGT_LIST_INIT(new_tl);
1365 struct cifs_ses *ses = CIFS_DFS_ROOT_SES(tcon->ses);
1366 struct cifs_tcon *ipc = ses->tcon_ipc;
1367 bool needs_refresh = false;
1368 struct cache_entry *ce;
1374 down_read(&htable_rw_lock);
1375 ce = lookup_cache_entry(path);
1376 needs_refresh = force_refresh || IS_ERR(ce) || cache_entry_expired(ce);
1378 rc = get_targets(ce, &old_tl);
1379 cifs_dbg(FYI, "%s: get_targets: %d\n", __func__, rc);
1381 up_read(&htable_rw_lock);
1383 if (!needs_refresh) {
1388 spin_lock(&ipc->tc_lock);
1389 if (ses->ses_status != SES_GOOD || ipc->status != TID_GOOD) {
1390 spin_unlock(&ipc->tc_lock);
1391 cifs_dbg(FYI, "%s: skip cache refresh due to disconnected ipc\n", __func__);
1394 spin_unlock(&ipc->tc_lock);
1396 ce = cache_refresh_path(xid, ses, path, true);
1398 rc = get_targets(ce, &new_tl);
1399 up_read(&htable_rw_lock);
1400 cifs_dbg(FYI, "%s: get_targets: %d\n", __func__, rc);
1401 mark_for_reconnect_if_needed(tcon->ses->server, &old_tl, &new_tl);
1406 dfs_cache_free_tgts(&old_tl);
1407 dfs_cache_free_tgts(&new_tl);
1411 static int refresh_tcon(struct cifs_tcon *tcon, bool force_refresh)
1413 struct TCP_Server_Info *server = tcon->ses->server;
1415 mutex_lock(&server->refpath_lock);
1416 if (server->leaf_fullpath)
1417 __refresh_tcon(server->leaf_fullpath + 1, tcon, force_refresh);
1418 mutex_unlock(&server->refpath_lock);
1423 * dfs_cache_remount_fs - remount a DFS share
1425 * Reconfigure dfs mount by forcing a new DFS referral and if the currently cached targets do not
1426 * match any of the new targets, mark it for reconnect.
1428 * @cifs_sb: cifs superblock.
1430 * Return zero if remounted, otherwise non-zero.
1432 int dfs_cache_remount_fs(struct cifs_sb_info *cifs_sb)
1434 struct cifs_tcon *tcon;
1435 struct TCP_Server_Info *server;
1437 if (!cifs_sb || !cifs_sb->master_tlink)
1440 tcon = cifs_sb_master_tcon(cifs_sb);
1441 server = tcon->ses->server;
1443 if (!server->origin_fullpath) {
1444 cifs_dbg(FYI, "%s: not a dfs mount\n", __func__);
1448 if (uuid_is_null(&cifs_sb->dfs_mount_id)) {
1449 cifs_dbg(FYI, "%s: no dfs mount group id\n", __func__);
1453 * After reconnecting to a different server, unique ids won't match anymore, so we disable
1454 * serverino. This prevents dentry revalidation to think the dentry are stale (ESTALE).
1456 cifs_autodisable_serverino(cifs_sb);
1458 * Force the use of prefix path to support failover on DFS paths that resolve to targets
1459 * that have different prefix paths.
1461 cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_USE_PREFIX_PATH;
1463 return refresh_tcon(tcon, true);
1467 * Worker that will refresh DFS cache from all active mounts based on lowest TTL value
1468 * from a DFS referral.
1470 static void refresh_cache_worker(struct work_struct *work)
1472 struct TCP_Server_Info *server;
1473 struct cifs_tcon *tcon, *ntcon;
1474 struct list_head tcons;
1475 struct cifs_ses *ses;
1477 INIT_LIST_HEAD(&tcons);
1479 spin_lock(&cifs_tcp_ses_lock);
1480 list_for_each_entry(server, &cifs_tcp_ses_list, tcp_ses_list) {
1481 if (!server->leaf_fullpath)
1484 list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
1485 if (ses->tcon_ipc) {
1487 list_add_tail(&ses->tcon_ipc->ulist, &tcons);
1489 list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {
1492 list_add_tail(&tcon->ulist, &tcons);
1497 spin_unlock(&cifs_tcp_ses_lock);
1499 list_for_each_entry_safe(tcon, ntcon, &tcons, ulist) {
1500 struct TCP_Server_Info *server = tcon->ses->server;
1502 list_del_init(&tcon->ulist);
1504 mutex_lock(&server->refpath_lock);
1505 if (server->leaf_fullpath)
1506 __refresh_tcon(server->leaf_fullpath + 1, tcon, false);
1507 mutex_unlock(&server->refpath_lock);
1510 cifs_put_smb_ses(tcon->ses);
1512 cifs_put_tcon(tcon);
1515 spin_lock(&cache_ttl_lock);
1516 queue_delayed_work(dfscache_wq, &refresh_task, cache_ttl * HZ);
1517 spin_unlock(&cache_ttl_lock);