[RFC PATCH 19/20] cifs: Remove usage of load_nls_default() calls

From: Pali Rohár
Date: Sun Aug 08 2021 - 12:25:42 EST


cifs functions will use UTF-8 encoding when nls_table is set to NULL. So
there is no need to load "dummy" NLS table for some operations.

On few places in dfs_cache replace utf8 nls by utf8_to_utf32() function
which converts UTF-8 sequence to unicode code points (stored as type
unicode_t). This should fix handling of (UTF-16) CIFS paths with UTF-16
surrogare pairs, which utf8 nls module cannot handle.

Signed-off-by: Pali Rohár <pali@xxxxxxxxxx>
---
fs/cifs/cifssmb.c | 8 ++------
fs/cifs/dfs_cache.c | 24 ++++++++----------------
fs/cifs/smb2pdu.c | 17 ++++-------------
3 files changed, 14 insertions(+), 35 deletions(-)

diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 65d1a65bfc37..8a2eb380c97d 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -119,7 +119,6 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
int rc;
struct cifs_ses *ses;
struct TCP_Server_Info *server;
- struct nls_table *nls_codepage;
int retries;

/*
@@ -186,8 +185,6 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
if (!ses->need_reconnect && !tcon->need_reconnect)
return 0;

- nls_codepage = load_nls_default();
-
/*
* need to prevent multiple threads trying to simultaneously
* reconnect the same SMB session
@@ -207,7 +204,7 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)

rc = cifs_negotiate_protocol(0, ses);
if (rc == 0 && ses->need_reconnect)
- rc = cifs_setup_session(0, ses, nls_codepage);
+ rc = cifs_setup_session(0, ses, NULL);

/* do we need to reconnect tcon? */
if (rc || !tcon->need_reconnect) {
@@ -216,7 +213,7 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
}

cifs_mark_open_files_invalid(tcon);
- rc = cifs_tree_connect(0, tcon, nls_codepage);
+ rc = cifs_tree_connect(0, tcon, NULL);
mutex_unlock(&ses->session_mutex);
cifs_dbg(FYI, "reconnect tcon rc = %d\n", rc);

@@ -252,7 +249,6 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
rc = -EAGAIN;
}

- unload_nls(nls_codepage);
return rc;
}

diff --git a/fs/cifs/dfs_cache.c b/fs/cifs/dfs_cache.c
index 283745592844..3ba748e59e64 100644
--- a/fs/cifs/dfs_cache.c
+++ b/fs/cifs/dfs_cache.c
@@ -66,8 +66,6 @@ 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
*/
@@ -194,14 +192,14 @@ char *dfs_cache_canonical_path(const char *path, const struct nls_table *cp, int
if (!path || strlen(path) < 3 || (*path != '\\' && *path != '/'))
return ERR_PTR(-EINVAL);

- if (unlikely(strcmp(cp->charset, cache_cp->charset))) {
+ if (unlikely(cp)) {
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);
+ npath = cifs_strndup_from_utf16(tmp, plen, true, NULL);
kfree(tmp);

if (!npath) {
@@ -413,9 +411,6 @@ int dfs_cache_init(void)
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;
@@ -429,11 +424,11 @@ static int cache_entry_hash(const void *data, int size, unsigned int *hash)
{
int i, clen;
const unsigned char *s = data;
- wchar_t c;
+ unicode_t c;
unsigned int h = 0;

for (i = 0; i < size; i += clen) {
- clen = cache_cp->char2uni(&s[i], size - i, &c);
+ clen = utf8_to_utf32(&s[i], size - i, &c);
if (unlikely(clen < 0)) {
cifs_dbg(VFS, "%s: can't convert char\n", __func__);
return clen;
@@ -622,14 +617,14 @@ static int add_cache_entry_locked(struct dfs_info3_param *refs, int numrefs)
static bool dfs_path_equal(const char *s1, int len1, const char *s2, int len2)
{
int i, l1, l2;
- wchar_t c1, c2;
+ unicode_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);
+ l1 = utf8_to_utf32(&s1[i], len1 - i, &c1);
+ l2 = utf8_to_utf32(&s2[i], len2 - i, &c2);
if (unlikely(l1 < 0 && l2 < 0)) {
if (s1[i] != s2[i])
return false;
@@ -719,7 +714,6 @@ static struct cache_entry *lookup_cache_entry(const char *path)
void dfs_cache_destroy(void)
{
cancel_delayed_work_sync(&refresh_task);
- unload_nls(cache_cp);
free_mount_group_list();
flush_cache_ents();
kmem_cache_destroy(cache_slab);
@@ -767,10 +761,8 @@ static int get_dfs_referral(const unsigned int xid, struct cifs_ses *ses, const

if (!ses || !ses->server || !ses->server->ops->get_dfs_refer)
return -EOPNOTSUPP;
- if (unlikely(!cache_cp))
- return -EINVAL;

- rc = ses->server->ops->get_dfs_refer(xid, ses, path, refs, numrefs, cache_cp,
+ rc = ses->server->ops->get_dfs_refer(xid, ses, path, refs, numrefs, NULL,
NO_MAP_UNI_RSVD);
if (!rc) {
struct dfs_info3_param *ref = *refs;
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 781d14e5f2af..b44f91dd2782 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -145,7 +145,6 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
struct TCP_Server_Info *server)
{
int rc;
- struct nls_table *nls_codepage;
struct cifs_ses *ses;
int retries;

@@ -233,8 +232,6 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
if (!tcon->ses->need_reconnect && !tcon->need_reconnect)
return 0;

- nls_codepage = load_nls_default();
-
/*
* need to prevent multiple threads trying to simultaneously reconnect
* the same SMB session
@@ -262,7 +259,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,

rc = cifs_negotiate_protocol(0, tcon->ses);
if (!rc && tcon->ses->need_reconnect) {
- rc = cifs_setup_session(0, tcon->ses, nls_codepage);
+ rc = cifs_setup_session(0, tcon->ses, NULL);
if ((rc == -EACCES) && !tcon->retry) {
rc = -EHOSTDOWN;
ses->binding = false;
@@ -286,7 +283,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
if (tcon->use_persistent)
tcon->need_reopen_files = true;

- rc = cifs_tree_connect(0, tcon, nls_codepage);
+ rc = cifs_tree_connect(0, tcon, NULL);
mutex_unlock(&tcon->ses->session_mutex);

cifs_dbg(FYI, "reconnect tcon rc = %d\n", rc);
@@ -322,7 +319,6 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
rc = -EAGAIN;
}
failed:
- unload_nls(nls_codepage);
return rc;
}

@@ -481,12 +477,10 @@ build_encrypt_ctxt(struct smb2_encryption_neg_context *pneg_ctxt)
static unsigned int
build_netname_ctxt(struct smb2_netname_neg_context *pneg_ctxt, char *hostname)
{
- struct nls_table *cp = load_nls_default();
-
pneg_ctxt->ContextType = SMB2_NETNAME_NEGOTIATE_CONTEXT_ID;

/* copy up to max of first 100 bytes of server name to NetName field */
- pneg_ctxt->DataLength = cpu_to_le16(2 * cifs_strtoUTF16(pneg_ctxt->NetName, hostname, 100, cp));
+ pneg_ctxt->DataLength = cpu_to_le16(2 * cifs_strtoUTF16(pneg_ctxt->NetName, hostname, 100, NULL));
/* context size is DataLength + minimal smb2_neg_context */
return DIV_ROUND_UP(le16_to_cpu(pneg_ctxt->DataLength) +
sizeof(struct smb2_neg_context), 8) * 8;
@@ -2498,7 +2492,6 @@ alloc_path_with_tree_prefix(__le16 **out_path, int *out_size, int *out_len,
const char *treename, const __le16 *path)
{
int treename_len, path_len;
- struct nls_table *cp;
const __le16 sep[] = {cpu_to_le16('\\'), cpu_to_le16(0x0000)};

/*
@@ -2529,11 +2522,9 @@ alloc_path_with_tree_prefix(__le16 **out_path, int *out_size, int *out_len,
if (!*out_path)
return -ENOMEM;

- cp = load_nls_default();
- cifs_strtoUTF16(*out_path, treename, treename_len, cp);
+ cifs_strtoUTF16(*out_path, treename, treename_len, NULL);
UniStrcat(*out_path, sep);
UniStrcat(*out_path, path);
- unload_nls(cp);

return 0;
}
--
2.20.1