// SPDX-License-Identifier: GPL-2.0 /* * DFS referral cache routines * * Copyright (c) 2018-2019 Paulo Alcantara */ #include #include #include #include #include #include #include #include "cifsglob.h" #include "smb2pdu.h" #include "smb2proto.h" #include "cifsproto.h" #include "cifs_debug.h" #include "cifs_unicode.h" #include "smb2glob.h" #include "dns_resolve.h" #include "dfs_cache.h" #define CACHE_HTABLE_SIZE 32 #define CACHE_MAX_ENTRIES 64 #define CACHE_MIN_TTL 120 /* 2 minutes */ #define IS_DFS_INTERLINK(v) (((v) & DFSREF_REFERRAL_SERVER) && !((v) & DFSREF_STORAGE_SERVER)) struct cache_dfs_tgt { char *name; int path_consumed; struct list_head list; }; struct cache_entry { struct hlist_node hlist; const char *path; int hdr_flags; /* RESP_GET_DFS_REFERRAL.ReferralHeaderFlags */ int ttl; /* DFS_REREFERRAL_V3.TimeToLive */ int srvtype; /* DFS_REREFERRAL_V3.ServerType */ int ref_flags; /* DFS_REREFERRAL_V3.ReferralEntryFlags */ struct timespec64 etime; int path_consumed; /* RESP_GET_DFS_REFERRAL.PathConsumed */ int numtgts; struct list_head tlist; struct cache_dfs_tgt *tgthint; }; static struct kmem_cache *cache_slab __read_mostly; static struct workqueue_struct *dfscache_wq __read_mostly; static int cache_ttl; static DEFINE_SPINLOCK(cache_ttl_lock); static struct nls_table *cache_cp; /* * Number of entries in the cache */ static atomic_t cache_count; static struct hlist_head cache_htable[CACHE_HTABLE_SIZE]; static DECLARE_RWSEM(htable_rw_lock); static void refresh_cache_worker(struct work_struct *work); static DECLARE_DELAYED_WORK(refresh_task, refresh_cache_worker); /** * dfs_cache_canonical_path - get a canonical DFS path * * @path: DFS path * @cp: codepage * @remap: mapping type * * Return canonical path if success, otherwise error. */ char *dfs_cache_canonical_path(const char *path, const struct nls_table *cp, int remap) { char *tmp; int plen = 0; char *npath; if (!path || strlen(path) < 3 || (*path != '\\' && *path != '/')) return ERR_PTR(-EINVAL); if (unlikely(strcmp(cp->charset, cache_cp->charset))) { tmp = (char *)cifs_strndup_to_utf16(path, strlen(path), &plen, cp, remap); if (!tmp) { cifs_dbg(VFS, "%s: failed to convert path to utf16\n", __func__); return ERR_PTR(-EINVAL); } npath = cifs_strndup_from_utf16(tmp, plen, true, cache_cp); kfree(tmp); if (!npath) { cifs_dbg(VFS, "%s: failed to convert path from utf16\n", __func__); return ERR_PTR(-EINVAL); } } else { npath = kstrdup(path, GFP_KERNEL); if (!npath) return ERR_PTR(-ENOMEM); } convert_delimiter(npath, '\\'); return npath; } static inline bool cache_entry_expired(const struct cache_entry *ce) { struct timespec64 ts; ktime_get_coarse_real_ts64(&ts); return timespec64_compare(&ts, &ce->etime) >= 0; } static inline void free_tgts(struct cache_entry *ce) { struct cache_dfs_tgt *t, *n; list_for_each_entry_safe(t, n, &ce->tlist, list) { list_del(&t->list); kfree(t->name); kfree(t); } } static inline void flush_cache_ent(struct cache_entry *ce) { hlist_del_init(&ce->hlist); kfree(ce->path); free_tgts(ce); atomic_dec(&cache_count); kmem_cache_free(cache_slab, ce); } static void flush_cache_ents(void) { int i; for (i = 0; i < CACHE_HTABLE_SIZE; i++) { struct hlist_head *l = &cache_htable[i]; struct hlist_node *n; struct cache_entry *ce; hlist_for_each_entry_safe(ce, n, l, hlist) { if (!hlist_unhashed(&ce->hlist)) flush_cache_ent(ce); } } } /* * dfs cache /proc file */ static int dfscache_proc_show(struct seq_file *m, void *v) { int i; struct cache_entry *ce; struct cache_dfs_tgt *t; seq_puts(m, "DFS cache\n---------\n"); down_read(&htable_rw_lock); for (i = 0; i < CACHE_HTABLE_SIZE; i++) { struct hlist_head *l = &cache_htable[i]; hlist_for_each_entry(ce, l, hlist) { if (hlist_unhashed(&ce->hlist)) continue; seq_printf(m, "cache entry: path=%s,type=%s,ttl=%d,etime=%ld,hdr_flags=0x%x,ref_flags=0x%x,interlink=%s,path_consumed=%d,expired=%s\n", ce->path, ce->srvtype == DFS_TYPE_ROOT ? "root" : "link", ce->ttl, ce->etime.tv_nsec, ce->hdr_flags, ce->ref_flags, IS_DFS_INTERLINK(ce->hdr_flags) ? "yes" : "no", ce->path_consumed, cache_entry_expired(ce) ? "yes" : "no"); list_for_each_entry(t, &ce->tlist, list) { seq_printf(m, " %s%s\n", t->name, READ_ONCE(ce->tgthint) == t ? " (target hint)" : ""); } } } up_read(&htable_rw_lock); return 0; } static ssize_t dfscache_proc_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos) { char c; int rc; rc = get_user(c, buffer); if (rc) return rc; if (c != '0') return -EINVAL; cifs_dbg(FYI, "clearing dfs cache\n"); down_write(&htable_rw_lock); flush_cache_ents(); up_write(&htable_rw_lock); return count; } static int dfscache_proc_open(struct inode *inode, struct file *file) { return single_open(file, dfscache_proc_show, NULL); } const struct proc_ops dfscache_proc_ops = { .proc_open = dfscache_proc_open, .proc_read = seq_read, .proc_lseek = seq_lseek, .proc_release = single_release, .proc_write = dfscache_proc_write, }; #ifdef CONFIG_CIFS_DEBUG2 static inline void dump_tgts(const struct cache_entry *ce) { struct cache_dfs_tgt *t; cifs_dbg(FYI, "target list:\n"); list_for_each_entry(t, &ce->tlist, list) { cifs_dbg(FYI, " %s%s\n", t->name, READ_ONCE(ce->tgthint) == t ? " (target hint)" : ""); } } static inline void dump_ce(const struct cache_entry *ce) { cifs_dbg(FYI, "cache entry: path=%s,type=%s,ttl=%d,etime=%ld,hdr_flags=0x%x,ref_flags=0x%x,interlink=%s,path_consumed=%d,expired=%s\n", ce->path, ce->srvtype == DFS_TYPE_ROOT ? "root" : "link", ce->ttl, ce->etime.tv_nsec, ce->hdr_flags, ce->ref_flags, IS_DFS_INTERLINK(ce->hdr_flags) ? "yes" : "no", ce->path_consumed, cache_entry_expired(ce) ? "yes" : "no"); dump_tgts(ce); } static inline void dump_refs(const struct dfs_info3_param *refs, int numrefs) { int i; cifs_dbg(FYI, "DFS referrals returned by the server:\n"); for (i = 0; i < numrefs; i++) { const struct dfs_info3_param *ref = &refs[i]; cifs_dbg(FYI, "\n" "flags: 0x%x\n" "path_consumed: %d\n" "server_type: 0x%x\n" "ref_flag: 0x%x\n" "path_name: %s\n" "node_name: %s\n" "ttl: %d (%dm)\n", ref->flags, ref->path_consumed, ref->server_type, ref->ref_flag, ref->path_name, ref->node_name, ref->ttl, ref->ttl / 60); } } #else #define dump_tgts(e) #define dump_ce(e) #define dump_refs(r, n) #endif /** * dfs_cache_init - Initialize DFS referral cache. * * Return zero if initialized successfully, otherwise non-zero. */ int dfs_cache_init(void) { int rc; int i; dfscache_wq = alloc_workqueue("cifs-dfscache", WQ_FREEZABLE | WQ_UNBOUND, 1); if (!dfscache_wq) return -ENOMEM; cache_slab = kmem_cache_create("cifs_dfs_cache", sizeof(struct cache_entry), 0, SLAB_HWCACHE_ALIGN, NULL); if (!cache_slab) { rc = -ENOMEM; goto out_destroy_wq; } for (i = 0; i < CACHE_HTABLE_SIZE; i++) INIT_HLIST_HEAD(&cache_htable[i]); atomic_set(&cache_count, 0); cache_cp = load_nls("utf8"); if (!cache_cp) cache_cp = load_nls_default(); cifs_dbg(FYI, "%s: initialized DFS referral cache\n", __func__); return 0; out_destroy_wq: destroy_workqueue(dfscache_wq); return rc; } static int cache_entry_hash(const void *data, int size, unsigned int *hash) { int i, clen; const unsigned char *s = data; wchar_t c; unsigned int h = 0; for (i = 0; i < size; i += clen) { clen = cache_cp->char2uni(&s[i], size - i, &c); if (unlikely(clen < 0)) { cifs_dbg(VFS, "%s: can't convert char\n", __func__); return clen; } c = cifs_toupper(c); h = jhash(&c, sizeof(c), h); } *hash = h % CACHE_HTABLE_SIZE; return 0; } /* Return target hint of a DFS cache entry */ static inline char *get_tgt_name(const struct cache_entry *ce) { struct cache_dfs_tgt *t = READ_ONCE(ce->tgthint); return t ? t->name : ERR_PTR(-ENOENT); } /* Return expire time out of a new entry's TTL */ static inline struct timespec64 get_expire_time(int ttl) { struct timespec64 ts = { .tv_sec = ttl, .tv_nsec = 0, }; struct timespec64 now; ktime_get_coarse_real_ts64(&now); return timespec64_add(now, ts); } /* Allocate a new DFS target */ static struct cache_dfs_tgt *alloc_target(const char *name, int path_consumed) { struct cache_dfs_tgt *t; t = kmalloc(sizeof(*t), GFP_ATOMIC); if (!t) return ERR_PTR(-ENOMEM); t->name = kstrdup(name, GFP_ATOMIC); if (!t->name) { kfree(t); return ERR_PTR(-ENOMEM); } t->path_consumed = path_consumed; INIT_LIST_HEAD(&t->list); return t; } /* * Copy DFS referral information to a cache entry and conditionally update * target hint. */ static int copy_ref_data(const struct dfs_info3_param *refs, int numrefs, struct cache_entry *ce, const char *tgthint) { struct cache_dfs_tgt *target; int i; ce->ttl = max_t(int, refs[0].ttl, CACHE_MIN_TTL); ce->etime = get_expire_time(ce->ttl); ce->srvtype = refs[0].server_type; ce->hdr_flags = refs[0].flags; ce->ref_flags = refs[0].ref_flag; ce->path_consumed = refs[0].path_consumed; for (i = 0; i < numrefs; i++) { struct cache_dfs_tgt *t; t = alloc_target(refs[i].node_name, refs[i].path_consumed); if (IS_ERR(t)) { free_tgts(ce); return PTR_ERR(t); } if (tgthint && !strcasecmp(t->name, tgthint)) { list_add(&t->list, &ce->tlist); tgthint = NULL; } else { list_add_tail(&t->list, &ce->tlist); } ce->numtgts++; } target = list_first_entry_or_null(&ce->tlist, struct cache_dfs_tgt, list); WRITE_ONCE(ce->tgthint, target); return 0; } /* Allocate a new cache entry */ static struct cache_entry *alloc_cache_entry(struct dfs_info3_param *refs, int numrefs) { struct cache_entry *ce; int rc; ce = kmem_cache_zalloc(cache_slab, GFP_KERNEL); if (!ce) return ERR_PTR(-ENOMEM); ce->path = refs[0].path_name; refs[0].path_name = NULL; INIT_HLIST_NODE(&ce->hlist); INIT_LIST_HEAD(&ce->tlist); rc = copy_ref_data(refs, numrefs, ce, NULL); if (rc) { kfree(ce->path); kmem_cache_free(cache_slab, ce); ce = ERR_PTR(rc); } return ce; } static void remove_oldest_entry_locked(void) { int i; struct cache_entry *ce; struct cache_entry *to_del = NULL; WARN_ON(!rwsem_is_locked(&htable_rw_lock)); for (i = 0; i < CACHE_HTABLE_SIZE; i++) { struct hlist_head *l = &cache_htable[i]; hlist_for_each_entry(ce, l, hlist) { if (hlist_unhashed(&ce->hlist)) continue; if (!to_del || timespec64_compare(&ce->etime, &to_del->etime) < 0) to_del = ce; } } if (!to_del) { cifs_dbg(FYI, "%s: no entry to remove\n", __func__); return; } cifs_dbg(FYI, "%s: removing entry\n", __func__); dump_ce(to_del); flush_cache_ent(to_del); } /* Add a new DFS cache entry */ static struct cache_entry *add_cache_entry_locked(struct dfs_info3_param *refs, int numrefs) { int rc; struct cache_entry *ce; unsigned int hash; WARN_ON(!rwsem_is_locked(&htable_rw_lock)); if (atomic_read(&cache_count) >= CACHE_MAX_ENTRIES) { cifs_dbg(FYI, "%s: reached max cache size (%d)\n", __func__, CACHE_MAX_ENTRIES); remove_oldest_entry_locked(); } rc = cache_entry_hash(refs[0].path_name, strlen(refs[0].path_name), &hash); if (rc) return ERR_PTR(rc); ce = alloc_cache_entry(refs, numrefs); if (IS_ERR(ce)) return ce; spin_lock(&cache_ttl_lock); if (!cache_ttl) { cache_ttl = ce->ttl; queue_delayed_work(dfscache_wq, &refresh_task, cache_ttl * HZ); } else { cache_ttl = min_t(int, cache_ttl, ce->ttl); mod_delayed_work(dfscache_wq, &refresh_task, cache_ttl * HZ); } spin_unlock(&cache_ttl_lock); hlist_add_head(&ce->hlist, &cache_htable[hash]); dump_ce(ce); atomic_inc(&cache_count); return ce; } /* Check if two DFS paths are equal. @s1 and @s2 are expected to be in @cache_cp's charset */ static bool dfs_path_equal(const char *s1, int len1, const char *s2, int len2) { int i, l1, l2; wchar_t c1, c2; if (len1 != len2) return false; for (i = 0; i < len1; i += l1) { l1 = cache_cp->char2uni(&s1[i], len1 - i, &c1); l2 = cache_cp->char2uni(&s2[i], len2 - i, &c2); if (unlikely(l1 < 0 && l2 < 0)) { if (s1[i] != s2[i]) return false; l1 = 1; continue; } if (l1 != l2) return false; if (cifs_toupper(c1) != cifs_toupper(c2)) return false; } return true; } static struct cache_entry *__lookup_cache_entry(const char *path, unsigned int hash, int len) { struct cache_entry *ce; hlist_for_each_entry(ce, &cache_htable[hash], hlist) { if (dfs_path_equal(ce->path, strlen(ce->path), path, len)) { dump_ce(ce); return ce; } } return ERR_PTR(-ENOENT); } /* * Find a DFS cache entry in hash table and optionally check prefix path against normalized @path. * * Use whole path components in the match. Must be called with htable_rw_lock held. * * Return cached entry if successful. * Return ERR_PTR(-ENOENT) if the entry is not found. * Return error ptr otherwise. */ static struct cache_entry *lookup_cache_entry(const char *path) { struct cache_entry *ce; int cnt = 0; const char *s = path, *e; char sep = *s; unsigned int hash; int rc; while ((s = strchr(s, sep)) && ++cnt < 3) s++; if (cnt < 3) { rc = cache_entry_hash(path, strlen(path), &hash); if (rc) return ERR_PTR(rc); return __lookup_cache_entry(path, hash, strlen(path)); } /* * Handle paths that have more than two path components and are a complete prefix of the DFS * referral request path (@path). * * See MS-DFSC 3.2.5.5 "Receiving a Root Referral Request or Link Referral Request". */ e = path + strlen(path) - 1; while (e > s) { int len; /* skip separators */ while (e > s && *e == sep) e--; if (e == s) break; len = e + 1 - path; rc = cache_entry_hash(path, len, &hash); if (rc) return ERR_PTR(rc); ce = __lookup_cache_entry(path, hash, len); if (!IS_ERR(ce)) return ce; /* backward until separator */ while (e > s && *e != sep) e--; } return ERR_PTR(-ENOENT); } /** * dfs_cache_destroy - destroy DFS referral cache */ void dfs_cache_destroy(void) { cancel_delayed_work_sync(&refresh_task); unload_nls(cache_cp); flush_cache_ents(); kmem_cache_destroy(cache_slab); destroy_workqueue(dfscache_wq); cifs_dbg(FYI, "%s: destroyed DFS referral cache\n", __func__); } /* Update a cache entry with the new referral in @refs */ static int update_cache_entry_locked(struct cache_entry *ce, const struct dfs_info3_param *refs, int numrefs) { struct cache_dfs_tgt *target; char *th = NULL; int rc; WARN_ON(!rwsem_is_locked(&htable_rw_lock)); target = READ_ONCE(ce->tgthint); if (target) { th = kstrdup(target->name, GFP_ATOMIC); if (!th) return -ENOMEM; } free_tgts(ce); ce->numtgts = 0; rc = copy_ref_data(refs, numrefs, ce, th); kfree(th); return rc; } static int get_dfs_referral(const unsigned int xid, struct cifs_ses *ses, const char *path, struct dfs_info3_param **refs, int *numrefs) { int rc; int i; *refs = NULL; *numrefs = 0; if (!ses || !ses->server || !ses->server->ops->get_dfs_refer) return -EOPNOTSUPP; if (unlikely(!cache_cp)) return -EINVAL; cifs_dbg(FYI, "%s: ipc=%s referral=%s\n", __func__, ses->tcon_ipc->tree_name, path); rc = ses->server->ops->get_dfs_refer(xid, ses, path, refs, numrefs, cache_cp, NO_MAP_UNI_RSVD); if (!rc) { struct dfs_info3_param *ref = *refs; for (i = 0; i < *numrefs; i++) convert_delimiter(ref[i].path_name, '\\'); } return rc; } /* * Find, create or update a DFS cache entry. * * If the entry wasn't found, it will create a new one. Or if it was found but * expired, then it will update the entry accordingly. * * For interlinks, cifs_mount() and expand_dfs_referral() are supposed to * handle them properly. * * On success, return entry with acquired lock for reading, otherwise error ptr. */ static struct cache_entry *cache_refresh_path(const unsigned int xid, struct cifs_ses *ses, const char *path, bool force_refresh) { struct dfs_info3_param *refs = NULL; struct cache_entry *ce; int numrefs = 0; int rc; cifs_dbg(FYI, "%s: search path: %s\n", __func__, path); down_read(&htable_rw_lock); ce = lookup_cache_entry(path); if (!IS_ERR(ce)) { if (!force_refresh && !cache_entry_expired(ce)) return ce; } else if (PTR_ERR(ce) != -ENOENT) { up_read(&htable_rw_lock); return ce; } /* * Unlock shared access as we don't want to hold any locks while getting * a new referral. The @ses used for performing the I/O could be * reconnecting and it acquires @htable_rw_lock to look up the dfs cache * in order to failover -- if necessary. */ up_read(&htable_rw_lock); /* * Either the entry was not found, or it is expired, or it is a forced * refresh. * Request a new DFS referral in order to create or update a cache entry. */ rc = get_dfs_referral(xid, ses, path, &refs, &numrefs); if (rc) { ce = ERR_PTR(rc); goto out; } dump_refs(refs, numrefs); down_write(&htable_rw_lock); /* Re-check as another task might have it added or refreshed already */ ce = lookup_cache_entry(path); if (!IS_ERR(ce)) { if (force_refresh || cache_entry_expired(ce)) { rc = update_cache_entry_locked(ce, refs, numrefs); if (rc) ce = ERR_PTR(rc); } } else if (PTR_ERR(ce) == -ENOENT) { ce = add_cache_entry_locked(refs, numrefs); } if (IS_ERR(ce)) { up_write(&htable_rw_lock); goto out; } downgrade_write(&htable_rw_lock); out: free_dfs_info_array(refs, numrefs); return ce; } /* * Set up a DFS referral from a given cache entry. * * Must be called with htable_rw_lock held. */ static int setup_referral(const char *path, struct cache_entry *ce, struct dfs_info3_param *ref, const char *target) { int rc; cifs_dbg(FYI, "%s: set up new ref\n", __func__); memset(ref, 0, sizeof(*ref)); ref->path_name = kstrdup(path, GFP_ATOMIC); if (!ref->path_name) return -ENOMEM; ref->node_name = kstrdup(target, GFP_ATOMIC); if (!ref->node_name) { rc = -ENOMEM; goto err_free_path; } ref->path_consumed = ce->path_consumed; ref->ttl = ce->ttl; ref->server_type = ce->srvtype; ref->ref_flag = ce->ref_flags; ref->flags = ce->hdr_flags; return 0; err_free_path: kfree(ref->path_name); ref->path_name = NULL; return rc; } /* Return target list of a DFS cache entry */ static int get_targets(struct cache_entry *ce, struct dfs_cache_tgt_list *tl) { int rc; struct list_head *head = &tl->tl_list; struct cache_dfs_tgt *t; struct dfs_cache_tgt_iterator *it, *nit; memset(tl, 0, sizeof(*tl)); INIT_LIST_HEAD(head); list_for_each_entry(t, &ce->tlist, list) { it = kzalloc(sizeof(*it), GFP_ATOMIC); if (!it) { rc = -ENOMEM; goto err_free_it; } it->it_name = kstrdup(t->name, GFP_ATOMIC); if (!it->it_name) { kfree(it); rc = -ENOMEM; goto err_free_it; } it->it_path_consumed = t->path_consumed; if (READ_ONCE(ce->tgthint) == t) list_add(&it->it_list, head); else list_add_tail(&it->it_list, head); } tl->tl_numtgts = ce->numtgts; return 0; err_free_it: list_for_each_entry_safe(it, nit, head, it_list) { list_del(&it->it_list); kfree(it->it_name); kfree(it); } return rc; } /** * dfs_cache_find - find a DFS cache entry * * If it doesn't find the cache entry, then it will get a DFS referral * for @path and create a new entry. * * In case the cache entry exists but expired, it will get a DFS referral * for @path and then update the respective cache entry. * * These parameters are passed down to the get_dfs_refer() call if it * needs to be issued: * @xid: syscall xid * @ses: smb session to issue the request on * @cp: codepage * @remap: path character remapping type * @path: path to lookup in DFS referral cache. * * @ref: when non-NULL, store single DFS referral result in it. * @tgt_list: when non-NULL, store complete DFS target list in it. * * Return zero if the target was found, otherwise non-zero. */ int dfs_cache_find(const unsigned int xid, struct cifs_ses *ses, const struct nls_table *cp, int remap, const char *path, struct dfs_info3_param *ref, struct dfs_cache_tgt_list *tgt_list) { int rc; const char *npath; struct cache_entry *ce; npath = dfs_cache_canonical_path(path, cp, remap); if (IS_ERR(npath)) return PTR_ERR(npath); ce = cache_refresh_path(xid, ses, npath, false); if (IS_ERR(ce)) { rc = PTR_ERR(ce); goto out_free_path; } if (ref) rc = setup_referral(path, ce, ref, get_tgt_name(ce)); else rc = 0; if (!rc && tgt_list) rc = get_targets(ce, tgt_list); up_read(&htable_rw_lock); out_free_path: kfree(npath); return rc; } /** * dfs_cache_noreq_find - find a DFS cache entry without sending any requests to * the currently connected server. * * NOTE: This function will neither update a cache entry in case it was * expired, nor create a new cache entry if @path hasn't been found. It heavily * relies on an existing cache entry. * * @path: canonical DFS path to lookup in the DFS referral cache. * @ref: when non-NULL, store single DFS referral result in it. * @tgt_list: when non-NULL, store complete DFS target list in it. * * Return 0 if successful. * Return -ENOENT if the entry was not found. * Return non-zero for other errors. */ int dfs_cache_noreq_find(const char *path, struct dfs_info3_param *ref, struct dfs_cache_tgt_list *tgt_list) { int rc; struct cache_entry *ce; cifs_dbg(FYI, "%s: path: %s\n", __func__, path); down_read(&htable_rw_lock); ce = lookup_cache_entry(path); 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); 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: canonical DFS 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. */ void dfs_cache_noreq_update_tgthint(const char *path, const struct dfs_cache_tgt_iterator *it) { struct cache_dfs_tgt *t; struct cache_entry *ce; if (!path || !it) return; cifs_dbg(FYI, "%s: path: %s\n", __func__, path); down_read(&htable_rw_lock); ce = lookup_cache_entry(path); if (IS_ERR(ce)) goto out_unlock; t = READ_ONCE(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)) { WRITE_ONCE(ce->tgthint, t); cifs_dbg(FYI, "%s: new target hint: %s\n", __func__, it->it_name); break; } } out_unlock: up_read(&htable_rw_lock); } /** * dfs_cache_get_tgt_referral - returns a DFS referral (@ref) from a given * target iterator (@it). * * @path: canonical DFS 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; struct cache_entry *ce; if (!it || !ref) return -EINVAL; cifs_dbg(FYI, "%s: path: %s\n", __func__, path); down_read(&htable_rw_lock); ce = lookup_cache_entry(path); 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); return rc; } /* Extract share from DFS target and return a pointer to prefix path or NULL */ static const char *parse_target_share(const char *target, char **share) { const char *s, *seps = "/\\"; size_t len; s = strpbrk(target + 1, seps); if (!s) return ERR_PTR(-EINVAL); len = strcspn(s + 1, seps); if (!len) return ERR_PTR(-EINVAL); s += len; len = s - target + 1; *share = kstrndup(target, len, GFP_KERNEL); if (!*share) return ERR_PTR(-ENOMEM); s = target + len; return s + strspn(s, seps); } /** * 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 sep; char *target_share; char *ppath = NULL; const char *target_ppath, *dfsref_ppath; size_t target_pplen, dfsref_pplen; size_t len, c; if (!it || !path || !share || !prefix || strlen(path) < it->it_path_consumed) return -EINVAL; sep = it->it_name[0]; if (sep != '\\' && sep != '/') return -EINVAL; target_ppath = parse_target_share(it->it_name, &target_share); if (IS_ERR(target_ppath)) return PTR_ERR(target_ppath); /* point to prefix in DFS referral path */ dfsref_ppath = path + it->it_path_consumed; dfsref_ppath += strspn(dfsref_ppath, "/\\"); target_pplen = strlen(target_ppath); dfsref_pplen = strlen(dfsref_ppath); /* merge prefix paths from DFS referral path and target node */ if (target_pplen || dfsref_pplen) { len = target_pplen + dfsref_pplen + 2; ppath = kzalloc(len, GFP_KERNEL); if (!ppath) { kfree(target_share); return -ENOMEM; } c = strscpy(ppath, target_ppath, len); if (c && dfsref_pplen) ppath[c] = sep; strlcat(ppath, dfsref_ppath, len); } *share = target_share; *prefix = ppath; return 0; } static bool target_share_equal(struct TCP_Server_Info *server, const char *s1, const char *s2) { char unc[sizeof("\\\\") + SERVER_NAME_LENGTH] = {0}; const char *host; size_t hostlen; struct sockaddr_storage ss; bool match; int rc; if (strcasecmp(s1, s2)) return false; /* * Resolve share's hostname and check if server address matches. Otherwise just ignore it * as we could not have upcall to resolve hostname or failed to convert ip address. */ extract_unc_hostname(s1, &host, &hostlen); scnprintf(unc, sizeof(unc), "\\\\%.*s", (int)hostlen, host); rc = dns_resolve_server_name_to_ip(unc, (struct sockaddr *)&ss, NULL); if (rc < 0) { cifs_dbg(FYI, "%s: could not resolve %.*s. assuming server address matches.\n", __func__, (int)hostlen, host); return true; } cifs_server_lock(server); match = cifs_match_ipaddr((struct sockaddr *)&server->dstaddr, (struct sockaddr *)&ss); cifs_server_unlock(server); return match; } /* * Mark dfs tcon for reconnecting when the currently connected tcon does not match any of the new * target shares in @refs. */ static void mark_for_reconnect_if_needed(struct TCP_Server_Info *server, struct dfs_cache_tgt_list *old_tl, struct dfs_cache_tgt_list *new_tl) { struct dfs_cache_tgt_iterator *oit, *nit; for (oit = dfs_cache_get_tgt_iterator(old_tl); oit; oit = dfs_cache_get_next_tgt(old_tl, oit)) { for (nit = dfs_cache_get_tgt_iterator(new_tl); nit; nit = dfs_cache_get_next_tgt(new_tl, nit)) { if (target_share_equal(server, dfs_cache_get_tgt_name(oit), dfs_cache_get_tgt_name(nit))) return; } } cifs_dbg(FYI, "%s: no cached or matched targets. mark dfs share for reconnect.\n", __func__); cifs_signal_cifsd_for_reconnect(server, true); } /* Refresh dfs referral of tcon and mark it for reconnect if needed */ static int __refresh_tcon(const char *path, struct cifs_tcon *tcon, bool force_refresh) { struct dfs_cache_tgt_list old_tl = DFS_CACHE_TGT_LIST_INIT(old_tl); struct dfs_cache_tgt_list new_tl = DFS_CACHE_TGT_LIST_INIT(new_tl); struct cifs_ses *ses = CIFS_DFS_ROOT_SES(tcon->ses); struct cifs_tcon *ipc = ses->tcon_ipc; bool needs_refresh = false; struct cache_entry *ce; unsigned int xid; int rc = 0; xid = get_xid(); down_read(&htable_rw_lock); ce = lookup_cache_entry(path); needs_refresh = force_refresh || IS_ERR(ce) || cache_entry_expired(ce); if (!IS_ERR(ce)) { rc = get_targets(ce, &old_tl); cifs_dbg(FYI, "%s: get_targets: %d\n", __func__, rc); } up_read(&htable_rw_lock); if (!needs_refresh) { rc = 0; goto out; } spin_lock(&ipc->tc_lock); if (ses->ses_status != SES_GOOD || ipc->status != TID_GOOD) { spin_unlock(&ipc->tc_lock); cifs_dbg(FYI, "%s: skip cache refresh due to disconnected ipc\n", __func__); goto out; } spin_unlock(&ipc->tc_lock); ce = cache_refresh_path(xid, ses, path, true); if (!IS_ERR(ce)) { rc = get_targets(ce, &new_tl); up_read(&htable_rw_lock); cifs_dbg(FYI, "%s: get_targets: %d\n", __func__, rc); mark_for_reconnect_if_needed(tcon->ses->server, &old_tl, &new_tl); } out: free_xid(xid); dfs_cache_free_tgts(&old_tl); dfs_cache_free_tgts(&new_tl); return rc; } static int refresh_tcon(struct cifs_tcon *tcon, bool force_refresh) { struct TCP_Server_Info *server = tcon->ses->server; mutex_lock(&server->refpath_lock); if (server->leaf_fullpath) __refresh_tcon(server->leaf_fullpath + 1, tcon, force_refresh); mutex_unlock(&server->refpath_lock); return 0; } /** * dfs_cache_remount_fs - remount a DFS share * * Reconfigure dfs mount by forcing a new DFS referral and if the currently cached targets do not * match any of the new targets, mark it for reconnect. * * @cifs_sb: cifs superblock. * * Return zero if remounted, otherwise non-zero. */ int dfs_cache_remount_fs(struct cifs_sb_info *cifs_sb) { struct cifs_tcon *tcon; struct TCP_Server_Info *server; if (!cifs_sb || !cifs_sb->master_tlink) return -EINVAL; tcon = cifs_sb_master_tcon(cifs_sb); server = tcon->ses->server; if (!server->origin_fullpath) { cifs_dbg(FYI, "%s: not a dfs mount\n", __func__); return 0; } /* * After reconnecting to a different server, unique ids won't match anymore, so we disable * serverino. This prevents dentry revalidation to think the dentry are stale (ESTALE). */ cifs_autodisable_serverino(cifs_sb); /* * Force the use of prefix path to support failover on DFS paths that resolve to targets * that have different prefix paths. */ cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_USE_PREFIX_PATH; return refresh_tcon(tcon, true); } /* * Worker that will refresh DFS cache from all active mounts based on lowest TTL value * from a DFS referral. */ static void refresh_cache_worker(struct work_struct *work) { struct TCP_Server_Info *server; struct cifs_tcon *tcon, *ntcon; struct list_head tcons; struct cifs_ses *ses; INIT_LIST_HEAD(&tcons); spin_lock(&cifs_tcp_ses_lock); list_for_each_entry(server, &cifs_tcp_ses_list, tcp_ses_list) { if (!server->leaf_fullpath) continue; list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) { if (ses->tcon_ipc) { ses->ses_count++; list_add_tail(&ses->tcon_ipc->ulist, &tcons); } list_for_each_entry(tcon, &ses->tcon_list, tcon_list) { if (!tcon->ipc) { tcon->tc_count++; list_add_tail(&tcon->ulist, &tcons); } } } } spin_unlock(&cifs_tcp_ses_lock); list_for_each_entry_safe(tcon, ntcon, &tcons, ulist) { struct TCP_Server_Info *server = tcon->ses->server; list_del_init(&tcon->ulist); mutex_lock(&server->refpath_lock); if (server->leaf_fullpath) __refresh_tcon(server->leaf_fullpath + 1, tcon, false); mutex_unlock(&server->refpath_lock); if (tcon->ipc) cifs_put_smb_ses(tcon->ses); else cifs_put_tcon(tcon); } spin_lock(&cache_ttl_lock); queue_delayed_work(dfscache_wq, &refresh_task, cache_ttl * HZ); spin_unlock(&cache_ttl_lock); }