Commit 9d49640a authored by Aurelien Aptel's avatar Aurelien Aptel Committed by Steve French
Browse files

CIFS: implement get_dfs_refer for SMB2+ 

in SMB2+ the get_dfs_refer operation uses a FSCTL. The request can be
made on any Tree Connection according to the specs. Since Samba only
accepted it on an IPC connection until recently, try that first.

https://lists.samba.org/archive/samba-technical/2017-February/118859.html



3.2.4.20.3 Application Requests DFS Referral Information:
> The client MUST search for an existing Session and TreeConnect to any
> share on the server identified by ServerName for the user identified by
> UserCredentials. If no Session and TreeConnect are found, the client
> MUST establish a new Session and TreeConnect to IPC$ on the target
> server as described in section 3.2.4.2 using the supplied ServerName and
> UserCredentials.

Signed-off-by: default avatarAurelien Aptel <aaptel@suse.com>
Reviewed-by: default avatarPavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: default avatarSteve French <smfrench@gmail.com>
parent f0712928

fs/cifs/smb2ops.c

+101 −0
Original line number Diff line number Diff line
@@ -1104,6 +1104,103 @@ smb2_new_lease_key(struct cifs_fid *fid) 
	generate_random_uuid(fid->lease_key);

}



static int

smb2_get_dfs_refer(const unsigned int xid, struct cifs_ses *ses,

		   const char *search_name,

		   struct dfs_info3_param **target_nodes,

		   unsigned int *num_of_nodes,

		   const struct nls_table *nls_codepage, int remap)

{

	int rc;

	__le16 *utf16_path = NULL;

	int utf16_path_len = 0;

	struct cifs_tcon *tcon;

	struct fsctl_get_dfs_referral_req *dfs_req = NULL;

	struct get_dfs_referral_rsp *dfs_rsp = NULL;

	u32 dfs_req_size = 0, dfs_rsp_size = 0;



	cifs_dbg(FYI, "smb2_get_dfs_refer path <%s>\n", search_name);



	/*

	 * Use any tcon from the current session. Here, the first one.

	 */

	spin_lock(&cifs_tcp_ses_lock);

	tcon = list_first_entry_or_null(&ses->tcon_list, struct cifs_tcon,

					tcon_list);

	if (tcon)

		tcon->tc_count++;

	spin_unlock(&cifs_tcp_ses_lock);



	if (!tcon) {

		cifs_dbg(VFS, "session %p has no tcon available for a dfs referral request\n",

			 ses);

		rc = -ENOTCONN;

		goto out;

	}



	utf16_path = cifs_strndup_to_utf16(search_name, PATH_MAX,

					   &utf16_path_len,

					   nls_codepage, remap);

	if (!utf16_path) {

		rc = -ENOMEM;

		goto out;

	}



	dfs_req_size = sizeof(*dfs_req) + utf16_path_len;

	dfs_req = kzalloc(dfs_req_size, GFP_KERNEL);

	if (!dfs_req) {

		rc = -ENOMEM;

		goto out;

	}



	/* Highest DFS referral version understood */

	dfs_req->MaxReferralLevel = DFS_VERSION;



	/* Path to resolve in an UTF-16 null-terminated string */

	memcpy(dfs_req->RequestFileName, utf16_path, utf16_path_len);



	do {

		/* try first with IPC */

		rc = SMB2_ioctl(xid, tcon, NO_FILE_ID, NO_FILE_ID,

				FSCTL_DFS_GET_REFERRALS,

				true /* is_fsctl */, true /* use_ipc */,

				(char *)dfs_req, dfs_req_size,

				(char **)&dfs_rsp, &dfs_rsp_size);

		if (rc == -ENOTCONN) {

			/* try with normal tcon */

			rc = SMB2_ioctl(xid, tcon, NO_FILE_ID, NO_FILE_ID,

					FSCTL_DFS_GET_REFERRALS,

					true /* is_fsctl */, false /*use_ipc*/,

					(char *)dfs_req, dfs_req_size,

					(char **)&dfs_rsp, &dfs_rsp_size);

		}

	} while (rc == -EAGAIN);



	if (rc) {

		cifs_dbg(VFS, "ioctl error in smb2_get_dfs_refer rc=%d\n", rc);

		goto out;

	}



	rc = parse_dfs_referrals(dfs_rsp, dfs_rsp_size,

				 num_of_nodes, target_nodes,

				 nls_codepage, remap, search_name,

				 true /* is_unicode */);

	if (rc) {

		cifs_dbg(VFS, "parse error in smb2_get_dfs_refer rc=%d\n", rc);

		goto out;

	}



 out:

	if (tcon) {

		spin_lock(&cifs_tcp_ses_lock);

		tcon->tc_count--;

		spin_unlock(&cifs_tcp_ses_lock);

	}

	kfree(utf16_path);

	kfree(dfs_req);

	kfree(dfs_rsp);

	return rc;

}

#define SMB2_SYMLINK_STRUCT_SIZE \

	(sizeof(struct smb2_err_rsp) - 1 + sizeof(struct smb2_symlink_err_rsp))
@@ -2283,6 +2380,7 @@ struct smb_version_operations smb20_operations = { 
	.clone_range = smb2_clone_range,

	.wp_retry_size = smb2_wp_retry_size,

	.dir_needs_close = smb2_dir_needs_close,

	.get_dfs_refer = smb2_get_dfs_refer,

};



struct smb_version_operations smb21_operations = {
@@ -2364,6 +2462,7 @@ struct smb_version_operations smb21_operations = { 
	.wp_retry_size = smb2_wp_retry_size,

	.dir_needs_close = smb2_dir_needs_close,

	.enum_snapshots = smb3_enum_snapshots,

	.get_dfs_refer = smb2_get_dfs_refer,

};



struct smb_version_operations smb30_operations = {
@@ -2455,6 +2554,7 @@ struct smb_version_operations smb30_operations = { 
	.free_transform_rq = smb3_free_transform_rq,

	.is_transform_hdr = smb3_is_transform_hdr,

	.receive_transform = smb3_receive_transform,

	.get_dfs_refer = smb2_get_dfs_refer,

};



#ifdef CONFIG_CIFS_SMB311
@@ -2547,6 +2647,7 @@ struct smb_version_operations smb311_operations = { 
	.free_transform_rq = smb3_free_transform_rq,

	.is_transform_hdr = smb3_is_transform_hdr,

	.receive_transform = smb3_receive_transform,

	.get_dfs_refer = smb2_get_dfs_refer,

};

#endif /* CIFS_SMB311 */

fs/cifs/smb2pdu.h

+8 −0
Original line number Diff line number Diff line
@@ -695,6 +695,14 @@ struct fsctl_get_integrity_information_rsp { 
/* Integrity flags for above */

#define FSCTL_INTEGRITY_FLAG_CHECKSUM_ENFORCEMENT_OFF	0x00000001



/* See MS-DFSC 2.2.2 */

struct fsctl_get_dfs_referral_req {

	__le16 MaxReferralLevel;

	__u8 RequestFileName[];

} __packed;



/* DFS response is struct get_dfs_refer_rsp */



/* See MS-SMB2 2.2.31.3 */

struct network_resiliency_req {

	__le32 Timeout;

CRA Git | Maintained and supported by SUSTech CRA and CCSE