diff options
Diffstat (limited to 'fs/smb/client/dfs_cache.c')
| -rw-r--r-- | fs/smb/client/dfs_cache.c | 1305 |
1 files changed, 1305 insertions, 0 deletions
diff --git a/fs/smb/client/dfs_cache.c b/fs/smb/client/dfs_cache.c new file mode 100644 index 0000000000..508d831fab --- /dev/null +++ b/fs/smb/client/dfs_cache.c @@ -0,0 +1,1305 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * DFS referral cache routines + * + * Copyright (c) 2018-2019 Paulo Alcantara <palcantara@suse.de> + */ + +#include <linux/jhash.h> +#include <linux/ktime.h> +#include <linux/slab.h> +#include <linux/proc_fs.h> +#include <linux/nls.h> +#include <linux/workqueue.h> +#include <linux/uuid.h> +#include "cifsglob.h" +#include "smb2pdu.h" +#include "smb2proto.h" +#include "cifsproto.h" +#include "cifs_debug.h" +#include "cifs_unicode.h" +#include "smb2glob.h" +#include "dns_resolve.h" +#include "dfs.h" + +#include "dfs_cache.h" + +#define CACHE_HTABLE_SIZE 32 +#define CACHE_MAX_ENTRIES 64 +#define CACHE_MIN_TTL 120 /* 2 minutes */ +#define CACHE_DEFAULT_TTL 300 /* 5 minutes */ + +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; +struct workqueue_struct *dfscache_wq; + +atomic_t dfs_cache_ttl; + +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); + +/** + * 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, + 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, + 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_UNBOUND|WQ_FREEZABLE|WQ_MEM_RECLAIM, + 0); + 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); + atomic_set(&dfs_cache_ttl, CACHE_DEFAULT_TTL); + 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; + int ttl; + + 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; + + ttl = min_t(int, atomic_read(&dfs_cache_ttl), ce->ttl); + atomic_set(&dfs_cache_ttl, ttl); + + 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) +{ + 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, + const char *path, + 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))) { + dfs_cache_noreq_update_tgthint(path, 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); +} + +static bool is_ses_good(struct cifs_ses *ses) +{ + struct TCP_Server_Info *server = ses->server; + struct cifs_tcon *tcon = ses->tcon_ipc; + bool ret; + + spin_lock(&ses->ses_lock); + spin_lock(&ses->chan_lock); + ret = !cifs_chan_needs_reconnect(ses, server) && + ses->ses_status == SES_GOOD && + !tcon->need_reconnect; + spin_unlock(&ses->chan_lock); + spin_unlock(&ses->ses_lock); + return ret; +} + +/* Refresh dfs referral of tcon and mark it for reconnect if needed */ +static int __refresh_tcon(const char *path, struct cifs_ses *ses, bool force_refresh) +{ + struct TCP_Server_Info *server = ses->server; + DFS_CACHE_TGT_LIST(old_tl); + DFS_CACHE_TGT_LIST(new_tl); + 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; + } + + ses = CIFS_DFS_ROOT_SES(ses); + if (!is_ses_good(ses)) { + cifs_dbg(FYI, "%s: skip cache refresh due to disconnected ipc\n", + __func__); + goto out; + } + + 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(server, path, &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; + struct cifs_ses *ses = tcon->ses; + + mutex_lock(&server->refpath_lock); + if (server->leaf_fullpath) + __refresh_tcon(server->leaf_fullpath + 1, ses, 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; + + if (!cifs_sb || !cifs_sb->master_tlink) + return -EINVAL; + + tcon = cifs_sb_master_tcon(cifs_sb); + + spin_lock(&tcon->tc_lock); + if (!tcon->origin_fullpath) { + spin_unlock(&tcon->tc_lock); + cifs_dbg(FYI, "%s: not a dfs mount\n", __func__); + return 0; + } + spin_unlock(&tcon->tc_lock); + + /* + * 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); +} + +/* Refresh all DFS referrals related to DFS tcon */ +void dfs_cache_refresh(struct work_struct *work) +{ + struct TCP_Server_Info *server; + struct dfs_root_ses *rses; + struct cifs_tcon *tcon; + struct cifs_ses *ses; + + tcon = container_of(work, struct cifs_tcon, dfs_cache_work.work); + ses = tcon->ses; + server = ses->server; + + mutex_lock(&server->refpath_lock); + if (server->leaf_fullpath) + __refresh_tcon(server->leaf_fullpath + 1, ses, false); + mutex_unlock(&server->refpath_lock); + + list_for_each_entry(rses, &tcon->dfs_ses_list, list) { + ses = rses->ses; + server = ses->server; + mutex_lock(&server->refpath_lock); + if (server->leaf_fullpath) + __refresh_tcon(server->leaf_fullpath + 1, ses, false); + mutex_unlock(&server->refpath_lock); + } + + queue_delayed_work(dfscache_wq, &tcon->dfs_cache_work, + atomic_read(&dfs_cache_ttl) * HZ); +} |