+++ /dev/null
-// 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 */
-
-#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;
-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,
- 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_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 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 TCP_Server_Info *server = ses->server;
- 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;
- 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);
-}
-
-/* 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);
-}
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