Re: [PATCH v2] cifs: fix charset issue in reconnection

[Winston Wen <wentao@uniontech.com>]

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On Wed, 19 Jul 2023 12:31:17 +0800
Winston Wen <wentao@uniontech.com> wrote:

> On Tue, 18 Jul 2023 10:42:27 -0500
> Steve French <smfrench@gmail.com> wrote:
> 
> > I get compile warning:
> > 
> > /home/smfrench/cifs-2.6/fs/smb/client/connect.c: In function
> > ‘cifs_get_smb_ses’:
> > /home/smfrench/cifs-2.6/fs/smb/client/connect.c:2293:49: warning:
> > passing argument 1 of ‘load_nls’ discards ‘const’ qualifier from
> > pointer target type [-Wdiscarded-qualifiers]
> 
> 
> >  2293 |         ses->local_nls = load_nls(ctx->local_nls->charset);
> 
> Hi Steve,
> 
> Sorry about the mistake I made. I updated the patch with a very small
> change:
> 
> 	ses->local_nls = load_nls((char *)ctx->local_nls->charset);
> 
> It works, but I'm not sure whether it's clean enough. 
> 
> Perhaps I should make a change to load_nls() to take a const char *
> instead of char *? If this make sense, I'll do it soon.
> 
> Find the updated patch as attachment.
> 

Sorry I picked the wrong version, updated.


-- 
Thanks,
Winston

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From f63be0e643f59a2dee119c3cf996f02b79b5e73c Mon Sep 17 00:00:00 2001
From: Winston Wen <wentao@uniontech.com>
Date: Mon, 17 Jul 2023 08:51:50 +0800
Subject: [PATCH] cifs: fix charset issue in reconnection

We need to specify charset, like "iocharset=utf-8", in mount options for
Chinese path if the nls_default don't support it, such as iso8859-1, the
default value for CONFIG_NLS_DEFAULT.

But now in reconnection the nls_default is used, instead of the one we
specified and used in mount, and this can lead to mount failure.

Signed-off-by: Winston Wen <wentao@uniontech.com>
Reviewed-by: Paulo Alcantara <pc@manguebit.com>
---
 fs/smb/client/cifsglob.h | 1 +
 fs/smb/client/cifssmb.c  | 3 +--
 fs/smb/client/connect.c  | 5 +++++
 fs/smb/client/misc.c     | 1 +
 fs/smb/client/smb2pdu.c  | 3 +--
 5 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h
index c9a87d0123ce..31cadf9b2a98 100644
--- a/fs/smb/client/cifsglob.h
+++ b/fs/smb/client/cifsglob.h
@@ -1062,6 +1062,7 @@ struct cifs_ses {
 	unsigned long chans_need_reconnect;
 	/* ========= end: protected by chan_lock ======== */
 	struct cifs_ses *dfs_root_ses;
+	struct nls_table *local_nls;
 };
 
 static inline bool
diff --git a/fs/smb/client/cifssmb.c b/fs/smb/client/cifssmb.c
index 9dee267f1893..25503f1a4fd2 100644
--- a/fs/smb/client/cifssmb.c
+++ b/fs/smb/client/cifssmb.c
@@ -129,7 +129,7 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 	}
 	spin_unlock(&server->srv_lock);
 
-	nls_codepage = load_nls_default();
+	nls_codepage = ses->local_nls;
 
 	/*
 	 * need to prevent multiple threads trying to simultaneously
@@ -200,7 +200,6 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 		rc = -EAGAIN;
 	}
 
-	unload_nls(nls_codepage);
 	return rc;
 }
 
diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c
index 5dd09c6d762e..7efae6f6f3b0 100644
--- a/fs/smb/client/connect.c
+++ b/fs/smb/client/connect.c
@@ -1842,6 +1842,10 @@ static int match_session(struct cifs_ses *ses, struct smb3_fs_context *ctx)
 			    CIFS_MAX_PASSWORD_LEN))
 			return 0;
 	}
+
+	if (strcmp(ctx->local_nls->charset, ses->local_nls->charset))
+		return 0;
+
 	return 1;
 }
 
@@ -2286,6 +2290,7 @@ cifs_get_smb_ses(struct TCP_Server_Info *server, struct smb3_fs_context *ctx)
 
 	ses->sectype = ctx->sectype;
 	ses->sign = ctx->sign;
+	ses->local_nls = load_nls((char *)ctx->local_nls->charset);
 
 	/* add server as first channel */
 	spin_lock(&ses->chan_lock);
diff --git a/fs/smb/client/misc.c b/fs/smb/client/misc.c
index 70dbfe6584f9..d7e85d9a2655 100644
--- a/fs/smb/client/misc.c
+++ b/fs/smb/client/misc.c
@@ -95,6 +95,7 @@ sesInfoFree(struct cifs_ses *buf_to_free)
 		return;
 	}
 
+	unload_nls(buf_to_free->local_nls);
 	atomic_dec(&sesInfoAllocCount);
 	kfree(buf_to_free->serverOS);
 	kfree(buf_to_free->serverDomain);
diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
index e04766fe6f80..a457f07f820d 100644
--- a/fs/smb/client/smb2pdu.c
+++ b/fs/smb/client/smb2pdu.c
@@ -242,7 +242,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 	}
 	spin_unlock(&server->srv_lock);
 
-	nls_codepage = load_nls_default();
+	nls_codepage = ses->local_nls;
 
 	/*
 	 * need to prevent multiple threads trying to simultaneously
@@ -324,7 +324,6 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 		rc = -EAGAIN;
 	}
 failed:
-	unload_nls(nls_codepage);
 	return rc;
 }
 
-- 
2.40.1