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CIFS: Allow to switch on encryption with seal mount option
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This allows users to inforce encryption for SMB3 shares if a server
supports it.

Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
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Pavel Shilovsky authored and Steve French committed Feb 1, 2017
1 parent c42a6ab commit ae6f8dd
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Showing 2 changed files with 43 additions and 31 deletions.
41 changes: 28 additions & 13 deletions fs/cifs/connect.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2630,12 +2630,18 @@ cifs_get_smb_ses(struct TCP_Server_Info *server, struct smb_vol *volume_info)
return ERR_PTR(rc);
}

static int match_tcon(struct cifs_tcon *tcon, const char *unc)
static int match_tcon(struct cifs_tcon *tcon, struct smb_vol *volume_info)
{
if (tcon->tidStatus == CifsExiting)
return 0;
if (strncmp(tcon->treeName, unc, MAX_TREE_SIZE))
if (strncmp(tcon->treeName, volume_info->UNC, MAX_TREE_SIZE))
return 0;
if (tcon->seal != volume_info->seal)
return 0;
#ifdef CONFIG_CIFS_SMB2
if (tcon->snapshot_time != volume_info->snapshot_time)
return 0;
#endif /* CONFIG_CIFS_SMB2 */
return 1;
}

Expand All @@ -2648,14 +2654,8 @@ cifs_find_tcon(struct cifs_ses *ses, struct smb_vol *volume_info)
spin_lock(&cifs_tcp_ses_lock);
list_for_each(tmp, &ses->tcon_list) {
tcon = list_entry(tmp, struct cifs_tcon, tcon_list);
if (!match_tcon(tcon, volume_info->UNC))
continue;

#ifdef CONFIG_CIFS_SMB2
if (tcon->snapshot_time != volume_info->snapshot_time)
if (!match_tcon(tcon, volume_info))
continue;
#endif /* CONFIG_CIFS_SMB2 */

++tcon->tc_count;
spin_unlock(&cifs_tcp_ses_lock);
return tcon;
Expand Down Expand Up @@ -2701,8 +2701,6 @@ cifs_get_tcon(struct cifs_ses *ses, struct smb_vol *volume_info)
cifs_dbg(FYI, "Found match on UNC path\n");
/* existing tcon already has a reference */
cifs_put_smb_ses(ses);
if (tcon->seal != volume_info->seal)
cifs_dbg(VFS, "transport encryption setting conflicts with existing tid\n");
return tcon;
}

Expand Down Expand Up @@ -2758,7 +2756,6 @@ cifs_get_tcon(struct cifs_ses *ses, struct smb_vol *volume_info)
tcon->Flags &= ~SMB_SHARE_IS_IN_DFS;
cifs_dbg(FYI, "DFS disabled (%d)\n", tcon->Flags);
}
tcon->seal = volume_info->seal;
tcon->use_persistent = false;
/* check if SMB2 or later, CIFS does not support persistent handles */
if (volume_info->persistent) {
Expand Down Expand Up @@ -2795,6 +2792,24 @@ cifs_get_tcon(struct cifs_ses *ses, struct smb_vol *volume_info)
tcon->use_resilient = true;
}

if (volume_info->seal) {
if (ses->server->vals->protocol_id == 0) {
cifs_dbg(VFS,
"SMB3 or later required for encryption\n");
rc = -EOPNOTSUPP;
goto out_fail;
#ifdef CONFIG_CIFS_SMB2
} else if (tcon->ses->server->capabilities &
SMB2_GLOBAL_CAP_ENCRYPTION)
tcon->seal = true;
else {
cifs_dbg(VFS, "Encryption is not supported on share\n");
rc = -EOPNOTSUPP;
goto out_fail;
#endif /* CONFIG_CIFS_SMB2 */
}
}

/*
* We can have only one retry value for a connection to a share so for
* resources mounted more than once to the same server share the last
Expand Down Expand Up @@ -2926,7 +2941,7 @@ cifs_match_super(struct super_block *sb, void *data)

if (!match_server(tcp_srv, volume_info) ||
!match_session(ses, volume_info) ||
!match_tcon(tcon, volume_info->UNC) ||
!match_tcon(tcon, volume_info) ||
!match_prepath(sb, mnt_data)) {
rc = 0;
goto out;
Expand Down
33 changes: 15 additions & 18 deletions fs/cifs/smb2pdu.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -79,9 +79,14 @@ static const int smb2_req_struct_sizes[NUMBER_OF_SMB2_COMMANDS] = {

static int encryption_required(const struct cifs_tcon *tcon)
{
if (!tcon)
return 0;
if ((tcon->ses->session_flags & SMB2_SESSION_FLAG_ENCRYPT_DATA) ||
(tcon->share_flags & SHI1005_FLAGS_ENCRYPT_DATA))
return 1;
if (tcon->seal &&
(tcon->ses->server->capabilities & SMB2_GLOBAL_CAP_ENCRYPTION))
return 1;
return 0;
}

Expand Down Expand Up @@ -835,8 +840,6 @@ SMB2_auth_kerberos(struct SMB2_sess_data *sess_data)
ses->Suid = rsp->hdr.sync_hdr.SessionId;

ses->session_flags = le16_to_cpu(rsp->SessionFlags);
if (ses->session_flags & SMB2_SESSION_FLAG_ENCRYPT_DATA)
cifs_dbg(VFS, "SMB3 encryption not supported yet\n");

rc = SMB2_sess_establish_session(sess_data);
out_put_spnego_key:
Expand Down Expand Up @@ -933,8 +936,6 @@ SMB2_sess_auth_rawntlmssp_negotiate(struct SMB2_sess_data *sess_data)

ses->Suid = rsp->hdr.sync_hdr.SessionId;
ses->session_flags = le16_to_cpu(rsp->SessionFlags);
if (ses->session_flags & SMB2_SESSION_FLAG_ENCRYPT_DATA)
cifs_dbg(VFS, "SMB3 encryption not supported yet\n");

out:
kfree(ntlmssp_blob);
Expand Down Expand Up @@ -993,8 +994,6 @@ SMB2_sess_auth_rawntlmssp_authenticate(struct SMB2_sess_data *sess_data)

ses->Suid = rsp->hdr.sync_hdr.SessionId;
ses->session_flags = le16_to_cpu(rsp->SessionFlags);
if (ses->session_flags & SMB2_SESSION_FLAG_ENCRYPT_DATA)
cifs_dbg(VFS, "SMB3 encryption not supported yet\n");

rc = SMB2_sess_establish_session(sess_data);
out:
Expand Down Expand Up @@ -1145,12 +1144,6 @@ SMB2_tcon(const unsigned int xid, struct cifs_ses *ses, const char *tree,
if (tcon && tcon->bad_network_name)
return -ENOENT;

if ((tcon && tcon->seal) &&
((ses->server->capabilities & SMB2_GLOBAL_CAP_ENCRYPTION) == 0)) {
cifs_dbg(VFS, "encryption requested but no server support");
return -EOPNOTSUPP;
}

unc_path = kmalloc(MAX_SHARENAME_LENGTH * 2, GFP_KERNEL);
if (unc_path == NULL)
return -ENOMEM;
Expand All @@ -1168,15 +1161,16 @@ SMB2_tcon(const unsigned int xid, struct cifs_ses *ses, const char *tree,
return rc;
}

if (ses->session_flags & SMB2_SESSION_FLAG_ENCRYPT_DATA)
flags |= CIFS_TRANSFORM_REQ;

if (tcon == NULL) {
if ((ses->session_flags & SMB2_SESSION_FLAG_ENCRYPT_DATA))
flags |= CIFS_TRANSFORM_REQ;

/* since no tcon, smb2_init can not do this, so do here */
req->hdr.sync_hdr.SessionId = ses->Suid;
/* if (ses->server->sec_mode & SECMODE_SIGN_REQUIRED)
req->hdr.Flags |= SMB2_FLAGS_SIGNED; */
}
} else if (encryption_required(tcon))
flags |= CIFS_TRANSFORM_REQ;

iov[0].iov_base = (char *)req;
/* 4 for rfc1002 length field and 1 for pad */
Expand Down Expand Up @@ -1233,9 +1227,12 @@ SMB2_tcon(const unsigned int xid, struct cifs_ses *ses, const char *tree,
if ((rsp->Capabilities & SMB2_SHARE_CAP_DFS) &&
((tcon->share_flags & SHI1005_FLAGS_DFS) == 0))
cifs_dbg(VFS, "DFS capability contradicts DFS flag\n");

if (tcon->seal &&
!(tcon->ses->server->capabilities & SMB2_GLOBAL_CAP_ENCRYPTION))
cifs_dbg(VFS, "Encryption is requested but not supported\n");

init_copy_chunk_defaults(tcon);
if (tcon->share_flags & SHI1005_FLAGS_ENCRYPT_DATA)
cifs_dbg(VFS, "Encrypted shares not supported");
if (tcon->ses->server->ops->validate_negotiate)
rc = tcon->ses->server->ops->validate_negotiate(xid, tcon);
tcon_exit:
Expand Down

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