CIFS: Add SMB2 support for is_path_accessible

that needs for a successful mount through SMB2 protocol.

Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <smfrench@gmail.com>

fs/cifs/cifs_unicode.c

@@ -330,3 +330,64 @@ cifsConvertToUTF16(__le16 *target, const char *source, int srclen,
 ctoUTF16_out:
 	return i;
 }
+
+#ifdef CONFIG_CIFS_SMB2
+/*
+ * cifs_local_to_utf16_bytes - how long will a string be after conversion?
+ * @from - pointer to input string
+ * @maxbytes - don't go past this many bytes of input string
+ * @codepage - source codepage
+ *
+ * Walk a string and return the number of bytes that the string will
+ * be after being converted to the given charset, not including any null
+ * termination required. Don't walk past maxbytes in the source buffer.
+ */
+
+static int
+cifs_local_to_utf16_bytes(const char *from, int len,
+			  const struct nls_table *codepage)
+{
+	int charlen;
+	int i;
+	wchar_t wchar_to;
+
+	for (i = 0; len && *from; i++, from += charlen, len -= charlen) {
+		charlen = codepage->char2uni(from, len, &wchar_to);
+		/* Failed conversion defaults to a question mark */
+		if (charlen < 1)
+			charlen = 1;
+	}
+	return 2 * i; /* UTF16 characters are two bytes */
+}
+
+/*
+ * cifs_strndup_to_utf16 - copy a string to wire format from the local codepage
+ * @src - source string
+ * @maxlen - don't walk past this many bytes in the source string
+ * @utf16_len - the length of the allocated string in bytes (including null)
+ * @cp - source codepage
+ * @remap - map special chars
+ *
+ * Take a string convert it from the local codepage to UTF16 and
+ * put it in a new buffer. Returns a pointer to the new string or NULL on
+ * error.
+ */
+__le16 *
+cifs_strndup_to_utf16(const char *src, const int maxlen, int *utf16_len,
+		      const struct nls_table *cp, int remap)
+{
+	int len;
+	__le16 *dst;
+
+	len = cifs_local_to_utf16_bytes(src, maxlen, cp);
+	len += 2; /* NULL */
+	dst = kmalloc(len, GFP_KERNEL);
+	if (!dst) {
+		*utf16_len = 0;
+		return NULL;
+	}
+	cifsConvertToUTF16(dst, src, strlen(src), cp, remap);
+	*utf16_len = len;
+	return dst;
+}
+#endif /* CONFIG_CIFS_SMB2 */

fs/cifs/cifs_unicode.h

@@ -84,6 +84,11 @@ char *cifs_strndup_from_utf16(const char *src, const int maxlen,
 			      const struct nls_table *codepage);
 extern int cifsConvertToUTF16(__le16 *target, const char *source, int maxlen,
 			      const struct nls_table *cp, int mapChars);
+#ifdef CONFIG_CIFS_SMB2
+extern __le16 *cifs_strndup_to_utf16(const char *src, const int maxlen,
+				     int *utf16_len, const struct nls_table *cp,
+				     int remap);
+#endif /* CONFIG_CIFS_SMB2 */
 #endif
 
 /*

fs/cifs/smb2misc.c

@@ -230,6 +230,11 @@ smb2_get_data_area_len(int *off, int *len, struct smb2_hdr *hdr)
 		    ((struct smb2_sess_setup_rsp *)hdr)->SecurityBufferLength);
 		break;
 	case SMB2_CREATE:
+		*off = le32_to_cpu(
+		    ((struct smb2_create_rsp *)hdr)->CreateContextsOffset);
+		*len = le32_to_cpu(
+		    ((struct smb2_create_rsp *)hdr)->CreateContextsLength);
+		break;
 	case SMB2_READ:
 	case SMB2_QUERY_INFO:
 	case SMB2_QUERY_DIRECTORY:
@@ -315,3 +320,23 @@ smb2_calc_size(struct smb2_hdr *hdr)
 	cFYI(1, "SMB2 len %d", len);
 	return len;
 }
+
+/* Note: caller must free return buffer */
+__le16 *
+cifs_convert_path_to_utf16(const char *from, struct cifs_sb_info *cifs_sb)
+{
+	int len;
+	const char *start_of_path;
+	__le16 *to;
+
+	/* Windows doesn't allow paths beginning with \ */
+	if (from[0] == '\\')
+		start_of_path = from + 1;
+	else
+		start_of_path = from;
+	to = cifs_strndup_to_utf16(start_of_path, PATH_MAX, &len,
+				   cifs_sb->local_nls,
+				   cifs_sb->mnt_cifs_flags &
+					CIFS_MOUNT_MAP_SPECIAL_CHR);
+	return to;
+}

fs/cifs/smb2ops.c

@@ -157,6 +157,30 @@ smb2_negotiate(const unsigned int xid, struct cifs_ses *ses)
 	return rc;
 }
 
+static int
+smb2_is_path_accessible(const unsigned int xid, struct cifs_tcon *tcon,
+			struct cifs_sb_info *cifs_sb, const char *full_path)
+{
+	int rc;
+	__u64 persistent_fid, volatile_fid;
+	__le16 *utf16_path;
+
+	utf16_path = cifs_convert_path_to_utf16(full_path, cifs_sb);
+	if (!utf16_path)
+		return -ENOMEM;
+
+	rc = SMB2_open(xid, tcon, utf16_path, &persistent_fid, &volatile_fid,
+		       FILE_READ_ATTRIBUTES, FILE_OPEN, 0, 0);
+	if (rc) {
+		kfree(utf16_path);
+		return rc;
+	}
+
+	rc = SMB2_close(xid, tcon, persistent_fid, volatile_fid);
+	kfree(utf16_path);
+	return rc;
+}
+
 struct smb_version_operations smb21_operations = {
 	.setup_request = smb2_setup_request,
 	.check_receive = smb2_check_receive,
@@ -174,6 +198,7 @@ struct smb_version_operations smb21_operations = {
 	.logoff = SMB2_logoff,
 	.tree_connect = SMB2_tcon,
 	.tree_disconnect = SMB2_tdis,
+	.is_path_accessible = smb2_is_path_accessible,
 };
 
 struct smb_version_values smb21_values = {

fs/cifs/smb2pdu.c

@@ -829,3 +829,135 @@ SMB2_tdis(const unsigned int xid, struct cifs_tcon *tcon)
 
 	return rc;
 }
+
+int
+SMB2_open(const unsigned int xid, struct cifs_tcon *tcon, __le16 *path,
+	  u64 *persistent_fid, u64 *volatile_fid, __u32 desired_access,
+	  __u32 create_disposition, __u32 file_attributes, __u32 create_options)
+{
+	struct smb2_create_req *req;
+	struct smb2_create_rsp *rsp;
+	struct TCP_Server_Info *server;
+	struct cifs_ses *ses = tcon->ses;
+	struct kvec iov[2];
+	int resp_buftype;
+	int uni_path_len;
+	int rc = 0;
+	int num_iovecs = 2;
+
+	cFYI(1, "create/open");
+
+	if (ses && (ses->server))
+		server = ses->server;
+	else
+		return -EIO;
+
+	rc = small_smb2_init(SMB2_CREATE, tcon, (void **) &req);
+	if (rc)
+		return rc;
+
+	if (enable_oplocks)
+		req->RequestedOplockLevel = SMB2_OPLOCK_LEVEL_BATCH;
+	else
+		req->RequestedOplockLevel = SMB2_OPLOCK_LEVEL_NONE;
+	req->ImpersonationLevel = IL_IMPERSONATION;
+	req->DesiredAccess = cpu_to_le32(desired_access);
+	/* File attributes ignored on open (used in create though) */
+	req->FileAttributes = cpu_to_le32(file_attributes);
+	req->ShareAccess = FILE_SHARE_ALL_LE;
+	req->CreateDisposition = cpu_to_le32(create_disposition);
+	req->CreateOptions = cpu_to_le32(create_options);
+	uni_path_len = (2 * UniStrnlen((wchar_t *)path, PATH_MAX)) + 2;
+	req->NameOffset = cpu_to_le16(sizeof(struct smb2_create_req)
+			- 1 /* pad */ - 4 /* do not count rfc1001 len field */);
+
+	iov[0].iov_base = (char *)req;
+	/* 4 for rfc1002 length field */
+	iov[0].iov_len = get_rfc1002_length(req) + 4;
+
+	/* MUST set path len (NameLength) to 0 opening root of share */
+	if (uni_path_len >= 4) {
+		req->NameLength = cpu_to_le16(uni_path_len - 2);
+		/* -1 since last byte is buf[0] which is sent below (path) */
+		iov[0].iov_len--;
+		iov[1].iov_len = uni_path_len;
+		iov[1].iov_base = path;
+		/*
+		 * -1 since last byte is buf[0] which was counted in
+		 * smb2_buf_len.
+		 */
+		inc_rfc1001_len(req, uni_path_len - 1);
+	} else {
+		num_iovecs = 1;
+		req->NameLength = 0;
+	}
+
+	rc = SendReceive2(xid, ses, iov, num_iovecs, &resp_buftype, 0);
+	rsp = (struct smb2_create_rsp *)iov[0].iov_base;
+
+	if (rc != 0) {
+		cifs_stats_fail_inc(tcon, SMB2_CREATE_HE);
+		goto creat_exit;
+	}
+
+	if (rsp == NULL) {
+		rc = -EIO;
+		goto creat_exit;
+	}
+	*persistent_fid = rsp->PersistentFileId;
+	*volatile_fid = rsp->VolatileFileId;
+creat_exit:
+	free_rsp_buf(resp_buftype, rsp);
+	return rc;
+}
+
+int
+SMB2_close(const unsigned int xid, struct cifs_tcon *tcon,
+	   u64 persistent_fid, u64 volatile_fid)
+{
+	struct smb2_close_req *req;
+	struct smb2_close_rsp *rsp;
+	struct TCP_Server_Info *server;
+	struct cifs_ses *ses = tcon->ses;
+	struct kvec iov[1];
+	int resp_buftype;
+	int rc = 0;
+
+	cFYI(1, "Close");
+
+	if (ses && (ses->server))
+		server = ses->server;
+	else
+		return -EIO;
+
+	rc = small_smb2_init(SMB2_CLOSE, tcon, (void **) &req);
+	if (rc)
+		return rc;
+
+	req->PersistentFileId = persistent_fid;
+	req->VolatileFileId = volatile_fid;
+
+	iov[0].iov_base = (char *)req;
+	/* 4 for rfc1002 length field */
+	iov[0].iov_len = get_rfc1002_length(req) + 4;
+
+	rc = SendReceive2(xid, ses, iov, 1, &resp_buftype, 0);
+	rsp = (struct smb2_close_rsp *)iov[0].iov_base;
+
+	if (rc != 0) {
+		if (tcon)
+			cifs_stats_fail_inc(tcon, SMB2_CLOSE_HE);
+		goto close_exit;
+	}
+
+	if (rsp == NULL) {
+		rc = -EIO;
+		goto close_exit;
+	}
+
+	/* BB FIXME - decode close response, update inode for caching */
+
+close_exit:
+	free_rsp_buf(resp_buftype, rsp);
+	return rc;
+}