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Message-ID: <20241115133329.3ylyq5ufoqovbdv2@pali>
Date: Fri, 15 Nov 2024 14:33:29 +0100
From: Pali Rohár <pali@...nel.org>
To: Björn JACKE <bjacke@...Net.DE>
Cc: Steve French <sfrench@...ba.org>, Paulo Alcantara <pc@...guebit.com>,
Ronnie Sahlberg <ronniesahlberg@...il.com>,
linux-cifs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/5] cifs: Add new mount option -o nounicode to disable
SMB1 UNICODE mode
Hello Björn, I know about iocharset=iso8859-1 mount option, but change
here is something different. As I wrote in the commit message it allows
to easily test that "non-unicode flag of SMB" code path implementation
in cifs.ko that works correctly. For example, thanks to this change I
was able to find few bugs (including parsing of symlinks) in that code
path and fixes for them are in this patch series.
On Friday 15 November 2024 14:26:19 Björn JACKE wrote:
> you can simply use iocharset=iso8859-1 mount option if you want to get legacy
> charsets on the client side to work. I don't think that it's a good idea to
> mess with the ancient non-unicode flag of SMB.
>
> Björn
>
> On 2024-10-28 at 12:03 +0100 Pali Rohár sent off:
> > SMB1 protocol supports non-UNICODE (8-bit OEM character set) and
> > UNICODE (UTF-16) modes.
> >
> > Linux SMB1 client implements both of them but currently does not allow to
> > choose non-UNICODE mode when SMB1 server announce UNICODE mode support.
> >
> > This change adds a new mount option -o nounicode to disable UNICODE mode
> > and force usage of non-UNICODE (8-bit OEM character set) mode.
> >
> > This allows to test non-UNICODE implementation of Linux SMB1 client against
> > any SMB1 server, including modern and recent Windows SMB1 server.
> >
> > Signed-off-by: Pali Rohár <pali@...nel.org>
> > ---
> > fs/smb/client/cifsfs.c | 4 ++++
> > fs/smb/client/cifsglob.h | 2 ++
> > fs/smb/client/cifssmb.c | 5 ++++-
> > fs/smb/client/connect.c | 32 +++++++++++++++++++++++++++++---
> > fs/smb/client/fs_context.c | 11 +++++++++++
> > fs/smb/client/fs_context.h | 2 ++
> > fs/smb/client/sess.c | 1 +
> > fs/smb/client/smb1ops.c | 1 +
> > 8 files changed, 54 insertions(+), 4 deletions(-)
> >
> > diff --git a/fs/smb/client/cifsfs.c b/fs/smb/client/cifsfs.c
> > index 1decf91d3f61..447ed7831f2c 100644
> > --- a/fs/smb/client/cifsfs.c
> > +++ b/fs/smb/client/cifsfs.c
> > @@ -611,6 +611,10 @@ cifs_show_options(struct seq_file *s, struct dentry *root)
> > cifs_sb->ctx->dir_mode);
> > if (cifs_sb->ctx->iocharset)
> > seq_printf(s, ",iocharset=%s", cifs_sb->ctx->iocharset);
> > + if (tcon->ses->unicode == 0)
> > + seq_puts(s, ",nounicode");
> > + else if (tcon->ses->unicode == 1)
> > + seq_puts(s, ",unicode");
> > if (tcon->seal)
> > seq_puts(s, ",seal");
> > else if (tcon->ses->server->ignore_signature)
> > diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h
> > index dcee43889358..2f77b558abe8 100644
> > --- a/fs/smb/client/cifsglob.h
> > +++ b/fs/smb/client/cifsglob.h
> > @@ -651,6 +651,7 @@ struct smb_version_values {
> > unsigned int cap_unix;
> > unsigned int cap_nt_find;
> > unsigned int cap_large_files;
> > + unsigned int cap_unicode;
> > __u16 signing_enabled;
> > __u16 signing_required;
> > size_t create_lease_size;
> > @@ -1124,6 +1125,7 @@ struct cifs_ses {
> > bool sign; /* is signing required? */
> > bool domainAuto:1;
> > bool expired_pwd; /* track if access denied or expired pwd so can know if need to update */
> > + int unicode;
> > unsigned int flags;
> > __u16 session_flags;
> > __u8 smb3signingkey[SMB3_SIGN_KEY_SIZE];
> > diff --git a/fs/smb/client/cifssmb.c b/fs/smb/client/cifssmb.c
> > index c6f15dbe860a..6218b59b9da7 100644
> > --- a/fs/smb/client/cifssmb.c
> > +++ b/fs/smb/client/cifssmb.c
> > @@ -423,7 +423,10 @@ CIFSSMBNegotiate(const unsigned int xid,
> > return rc;
> >
> > pSMB->hdr.Mid = get_next_mid(server);
> > - pSMB->hdr.Flags2 |= (SMBFLG2_UNICODE | SMBFLG2_ERR_STATUS);
> > + pSMB->hdr.Flags2 |= SMBFLG2_ERR_STATUS;
> > +
> > + if (ses->unicode != 0)
> > + pSMB->hdr.Flags2 |= SMBFLG2_UNICODE;
> >
> > if (should_set_ext_sec_flag(ses->sectype)) {
> > cifs_dbg(FYI, "Requesting extended security\n");
> > diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c
> > index 612816ec71f5..3d9d736b6e58 100644
> > --- a/fs/smb/client/connect.c
> > +++ b/fs/smb/client/connect.c
> > @@ -2338,6 +2338,7 @@ cifs_get_smb_ses(struct TCP_Server_Info *server, struct smb3_fs_context *ctx)
> > ses->cred_uid = ctx->cred_uid;
> > ses->linux_uid = ctx->linux_uid;
> >
> > + ses->unicode = ctx->unicode;
> > ses->sectype = ctx->sectype;
> > ses->sign = ctx->sign;
> > ses->local_nls = load_nls(ctx->local_nls->charset);
> > @@ -3928,7 +3929,7 @@ cifs_setup_session(const unsigned int xid, struct cifs_ses *ses,
> > struct TCP_Server_Info *server,
> > struct nls_table *nls_info)
> > {
> > - int rc = -ENOSYS;
> > + int rc = 0;
> > struct TCP_Server_Info *pserver = SERVER_IS_CHAN(server) ? server->primary_server : server;
> > struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *)&pserver->dstaddr;
> > struct sockaddr_in *addr = (struct sockaddr_in *)&pserver->dstaddr;
> > @@ -3980,6 +3981,26 @@ cifs_setup_session(const unsigned int xid, struct cifs_ses *ses,
> > if (!linuxExtEnabled)
> > ses->capabilities &= (~server->vals->cap_unix);
> >
> > + /*
> > + * Check if the server supports specified encoding mode.
> > + * Zero value in vals->cap_unicode indidcates that chosen
> > + * protocol dialect does not support non-UNICODE mode.
> > + */
> > + if (ses->unicode == 1 && server->vals->cap_unicode != 0 &&
> > + !(server->capabilities & server->vals->cap_unicode)) {
> > + cifs_dbg(VFS, "Server does not support mounting in UNICODE mode\n");
> > + rc = -EOPNOTSUPP;
> > + } else if (ses->unicode == 0 && server->vals->cap_unicode == 0) {
> > + cifs_dbg(VFS, "Server does not support mounting in non-UNICODE mode\n");
> > + rc = -EOPNOTSUPP;
> > + } else if (ses->unicode == 0) {
> > + /*
> > + * When UNICODE mode was explicitly disabled then
> > + * do not announce client UNICODE capability.
> > + */
> > + ses->capabilities &= (~server->vals->cap_unicode);
> > + }
> > +
> > if (ses->auth_key.response) {
> > cifs_dbg(FYI, "Free previous auth_key.response = %p\n",
> > ses->auth_key.response);
> > @@ -3992,8 +4013,12 @@ cifs_setup_session(const unsigned int xid, struct cifs_ses *ses,
> > cifs_dbg(FYI, "Security Mode: 0x%x Capabilities: 0x%x TimeAdjust: %d\n",
> > server->sec_mode, server->capabilities, server->timeAdj);
> >
> > - if (server->ops->sess_setup)
> > - rc = server->ops->sess_setup(xid, ses, server, nls_info);
> > + if (!rc) {
> > + if (server->ops->sess_setup)
> > + rc = server->ops->sess_setup(xid, ses, server, nls_info);
> > + else
> > + rc = -ENOSYS;
> > + }
> >
> > if (rc) {
> > cifs_server_dbg(VFS, "Send error in SessSetup = %d\n", rc);
> > @@ -4063,6 +4088,7 @@ cifs_construct_tcon(struct cifs_sb_info *cifs_sb, kuid_t fsuid)
> > ctx->seal = master_tcon->seal;
> > ctx->witness = master_tcon->use_witness;
> > ctx->dfs_root_ses = master_tcon->ses->dfs_root_ses;
> > + ctx->unicode = master_tcon->ses->unicode;
> >
> > rc = cifs_set_vol_auth(ctx, master_tcon->ses);
> > if (rc) {
> > diff --git a/fs/smb/client/fs_context.c b/fs/smb/client/fs_context.c
> > index 7dd46cfc9fb3..d970b66e529c 100644
> > --- a/fs/smb/client/fs_context.c
> > +++ b/fs/smb/client/fs_context.c
> > @@ -127,6 +127,7 @@ const struct fs_parameter_spec smb3_fs_parameters[] = {
> > fsparam_flag("rootfs", Opt_rootfs),
> > fsparam_flag("compress", Opt_compress),
> > fsparam_flag("witness", Opt_witness),
> > + fsparam_flag_no("unicode", Opt_unicode),
> >
> > /* Mount options which take uid or gid */
> > fsparam_uid("backupuid", Opt_backupuid),
> > @@ -930,6 +931,10 @@ static int smb3_verify_reconfigure_ctx(struct fs_context *fc,
> > cifs_errorf(fc, "can not change iocharset during remount\n");
> > return -EINVAL;
> > }
> > + if (new_ctx->unicode != old_ctx->unicode) {
> > + cifs_errorf(fc, "can not change unicode during remount\n");
> > + return -EINVAL;
> > + }
> >
> > return 0;
> > }
> > @@ -1520,6 +1525,10 @@ static int smb3_fs_context_parse_param(struct fs_context *fc,
> > ctx->witness = true;
> > pr_warn_once("Witness protocol support is experimental\n");
> > break;
> > + case Opt_unicode:
> > + ctx->unicode = !result.negated;
> > + cifs_dbg(FYI, "unicode set to %d\n", ctx->unicode);
> > + break;
> > case Opt_rootfs:
> > #ifndef CONFIG_CIFS_ROOT
> > cifs_dbg(VFS, "rootfs support requires CONFIG_CIFS_ROOT config option\n");
> > @@ -1816,6 +1825,8 @@ int smb3_init_fs_context(struct fs_context *fc)
> > ctx->symlink_type = CIFS_SYMLINK_TYPE_DEFAULT;
> > ctx->nonativesocket = 0;
> >
> > + ctx->unicode = -1; /* autodetect, but prefer UNICODE mode */
> > +
> > /*
> > * short int override_uid = -1;
> > * short int override_gid = -1;
> > diff --git a/fs/smb/client/fs_context.h b/fs/smb/client/fs_context.h
> > index 18d39d457145..1514e05e6629 100644
> > --- a/fs/smb/client/fs_context.h
> > +++ b/fs/smb/client/fs_context.h
> > @@ -127,6 +127,7 @@ enum cifs_param {
> > Opt_multichannel,
> > Opt_compress,
> > Opt_witness,
> > + Opt_unicode,
> >
> > /* Mount options which take numeric value */
> > Opt_backupuid,
> > @@ -296,6 +297,7 @@ struct smb3_fs_context {
> > bool compress; /* enable SMB2 messages (READ/WRITE) de/compression */
> > bool rootfs:1; /* if it's a SMB root file system */
> > bool witness:1; /* use witness protocol */
> > + int unicode;
> > char *leaf_fullpath;
> > struct cifs_ses *dfs_root_ses;
> > bool dfs_automount:1; /* set for dfs automount only */
> > diff --git a/fs/smb/client/sess.c b/fs/smb/client/sess.c
> > index c88e9657f47a..6a92db287843 100644
> > --- a/fs/smb/client/sess.c
> > +++ b/fs/smb/client/sess.c
> > @@ -529,6 +529,7 @@ cifs_ses_add_channel(struct cifs_ses *ses,
> > ctx->password = ses->password;
> > ctx->sectype = ses->sectype;
> > ctx->sign = ses->sign;
> > + ctx->unicode = ses->unicode;
> >
> > /* UNC and paths */
> > /* XXX: Use ses->server->hostname? */
> > diff --git a/fs/smb/client/smb1ops.c b/fs/smb/client/smb1ops.c
> > index abca214f923c..b0fb4a5c586d 100644
> > --- a/fs/smb/client/smb1ops.c
> > +++ b/fs/smb/client/smb1ops.c
> > @@ -1189,6 +1189,7 @@ struct smb_version_values smb1_values = {
> > .cap_unix = CAP_UNIX,
> > .cap_nt_find = CAP_NT_SMBS | CAP_NT_FIND,
> > .cap_large_files = CAP_LARGE_FILES,
> > + .cap_unicode = CAP_UNICODE,
> > .signing_enabled = SECMODE_SIGN_ENABLED,
> > .signing_required = SECMODE_SIGN_REQUIRED,
> > };
> > --
> > 2.20.1
> >
> >
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