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Message-Id: <1340988354-26981-14-git-send-email-vincent.sanders@collabora.co.uk>
Date: Fri, 29 Jun 2012 17:45:52 +0100
From: Vincent Sanders <vincent.sanders@...labora.co.uk>
To: netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
"David S. Miller" <davem@...emloft.net>
Cc: Javier Martinez Canillas <javier.martinez@...labora.co.uk>,
Alban Crequy <alban.crequy@...labora.co.uk>
Subject: [PATCH net-next 13/15] netfilter: nfdbus: Add D-bus message parsing
From: Javier Martinez Canillas <javier.martinez@...labora.co.uk>
The netfilter D-Bus module needs to parse D-bus messages sent by
applications to decide whether a peer can receive or not a D-Bus
message. Add D-bus message parsing logic to be able to analyze.
Signed-off-by: Javier Martinez Canillas <javier.martinez@...labora.co.uk>
Signed-off-by: Alban Crequy <alban.crequy@...labora.co.uk>
---
net/netfilter/nfdbus/message.c | 194 ++++++++++++++++++++++++++++++++++++++++
net/netfilter/nfdbus/message.h | 71 +++++++++++++++
2 files changed, 265 insertions(+)
create mode 100644 net/netfilter/nfdbus/message.c
create mode 100644 net/netfilter/nfdbus/message.h
diff --git a/net/netfilter/nfdbus/message.c b/net/netfilter/nfdbus/message.c
new file mode 100644
index 0000000..93c409c
--- /dev/null
+++ b/net/netfilter/nfdbus/message.c
@@ -0,0 +1,194 @@
+/*
+ * message.c Basic D-Bus message parsing
+ *
+ * Copyright (C) 2010-2012 Collabora Ltd
+ * Authors: Alban Crequy <alban.crequy@...labora.co.uk>
+ * Copyright (C) 2002, 2003, 2004, 2005 Red Hat Inc.
+ * Copyright (C) 2002, 2003 CodeFactory AB
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ */
+
+#include <linux/slab.h>
+
+#include "message.h"
+
+int dbus_message_type_from_string(const char *type_str)
+{
+ if (strcmp(type_str, "method_call") == 0)
+ return DBUS_MESSAGE_TYPE_METHOD_CALL;
+ if (strcmp(type_str, "method_return") == 0)
+ return DBUS_MESSAGE_TYPE_METHOD_RETURN;
+ else if (strcmp(type_str, "signal") == 0)
+ return DBUS_MESSAGE_TYPE_SIGNAL;
+ else if (strcmp(type_str, "error") == 0)
+ return DBUS_MESSAGE_TYPE_ERROR;
+ else
+ return DBUS_MESSAGE_TYPE_INVALID;
+}
+
+int dbus_message_parse(unsigned char *message, size_t len,
+ struct dbus_message *dbus_message)
+{
+ unsigned char *cur;
+ int array_header_len;
+
+ dbus_message->message = message;
+
+ if (len < 4 + 4 + 4 + 4 || message[1] == 0 || message[1] > 4)
+ return -EINVAL;
+
+ dbus_message->type = message[1];
+ dbus_message->body_length = *((u32 *)(message + 4));
+ cur = message + 12;
+ array_header_len = *(u32 *)cur;
+ dbus_message->len_offset = 12;
+ cur += 4;
+ while (cur < message + len
+ && cur < message + 12 + 4 + array_header_len) {
+ int header_code;
+ int signature_len;
+ unsigned char *signature;
+ int str_len;
+ unsigned char *str;
+
+ /* D-Bus alignment craziness */
+ if ((cur - message) % 8 != 0)
+ cur += 8 - (cur - message) % 8;
+
+ header_code = *(char *)cur;
+ cur++;
+ signature_len = *(char *)cur;
+ /* All header fields of the current D-Bus spec have a simple
+ * type, either o, s, g, or u */
+ if (signature_len != 1)
+ return -EINVAL;
+ cur++;
+ signature = cur;
+ cur += signature_len + 1;
+ if (signature[0] != 'o' &&
+ signature[0] != 's' &&
+ signature[0] != 'g' &&
+ signature[0] != 'u')
+ return -EINVAL;
+
+ if (signature[0] == 'u') {
+ cur += 4;
+ continue;
+ }
+
+ if (signature[0] != 'g') {
+ str_len = *(u32 *)cur;
+ cur += 4;
+ } else {
+ str_len = *(char *)cur;
+ cur += 1;
+ }
+
+ str = cur;
+ switch (header_code) {
+ case 1:
+ dbus_message->path = str;
+ break;
+ case 2:
+ dbus_message->interface = str;
+ break;
+ case 3:
+ dbus_message->member = str;
+ break;
+ case 6:
+ dbus_message->destination = str;
+ break;
+ case 7:
+ dbus_message->sender = str;
+ break;
+ case 8:
+ dbus_message->body_signature = str;
+ break;
+ }
+ cur += str_len + 1;
+ }
+
+ dbus_message->padding_end = (8 - (cur - message) % 8) % 8;
+
+ /* Jump to body D-Bus alignment craziness */
+ if ((cur - message) % 8 != 0)
+ cur += 8 - (cur - message) % 8;
+ dbus_message->new_header_offset = cur - message;
+
+ if (dbus_message->new_header_offset
+ + dbus_message->body_length != len) {
+ pr_warn("Message truncated? " \
+ "Header %d + Body %d != Length %zd\n",
+ dbus_message->new_header_offset,
+ dbus_message->body_length, len);
+ return -EINVAL;
+ }
+
+ if (dbus_message->body_signature &&
+ dbus_message->body_signature[0] == 's') {
+ int str_len;
+ str_len = *(u32 *)cur;
+ cur += 4;
+ dbus_message->arg0 = cur;
+ cur += str_len + 1;
+ }
+
+ if ((cur - message) % 4 != 0)
+ cur += 4 - (cur - message) % 4;
+
+ if (dbus_message->body_signature &&
+ dbus_message->body_signature[0] == 's' &&
+ dbus_message->body_signature[1] == 's') {
+ int str_len;
+ str_len = *(u32 *)cur;
+ cur += 4;
+ dbus_message->arg1 = cur;
+ cur += str_len + 1;
+ }
+
+ if ((cur - message) % 4 != 0)
+ cur += 4 - (cur - message) % 4;
+
+ if (dbus_message->body_signature &&
+ dbus_message->body_signature[0] == 's' &&
+ dbus_message->body_signature[1] == 's' &&
+ dbus_message->body_signature[2] == 's') {
+ int str_len;
+ str_len = *(u32 *)cur;
+ cur += 4;
+ dbus_message->arg2 = cur;
+ cur += str_len + 1;
+ }
+
+ if ((cur - message) % 4 != 0)
+ cur += 4 - (cur - message) % 4;
+
+ if (dbus_message->type == DBUS_MESSAGE_TYPE_SIGNAL &&
+ dbus_message->sender && dbus_message->path &&
+ dbus_message->interface && dbus_message->member &&
+ dbus_message->arg0 &&
+ strcmp(dbus_message->sender, "org.freedesktop.DBus") == 0 &&
+ strcmp(dbus_message->interface, "org.freedesktop.DBus") == 0 &&
+ strcmp(dbus_message->path, "/org/freedesktop/DBus") == 0) {
+ if (strcmp(dbus_message->member, "NameAcquired") == 0)
+ dbus_message->name_acquired = dbus_message->arg0;
+ else if (strcmp(dbus_message->member, "NameLost") == 0)
+ dbus_message->name_lost = dbus_message->arg0;
+ }
+
+ return 0;
+}
diff --git a/net/netfilter/nfdbus/message.h b/net/netfilter/nfdbus/message.h
new file mode 100644
index 0000000..e3ea4d3
--- /dev/null
+++ b/net/netfilter/nfdbus/message.h
@@ -0,0 +1,71 @@
+/*
+ * message.h Basic D-Bus message parsing
+ *
+ * Copyright (C) 2010 Collabora Ltd
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ */
+
+#ifndef DBUS_MESSAGE_H
+#define DBUS_MESSAGE_H
+
+#include <linux/list.h>
+
+#define DBUS_MAXIMUM_MATCH_RULE_LENGTH 1024
+
+/* Types of message */
+
+#define DBUS_MESSAGE_TYPE_INVALID 0
+#define DBUS_MESSAGE_TYPE_METHOD_CALL 1
+#define DBUS_MESSAGE_TYPE_METHOD_RETURN 2
+#define DBUS_MESSAGE_TYPE_ERROR 3
+#define DBUS_MESSAGE_TYPE_SIGNAL 4
+#define DBUS_NUM_MESSAGE_TYPES 5
+
+/* No need to implement a feature-complete parser. It only implement what is
+ * needed by the bus. */
+struct dbus_message {
+ char *message;
+ size_t len;
+ size_t new_len;
+
+ /* direct pointers to the fields */
+ int type;
+ char *path;
+ char *interface;
+ char *member;
+ char *destination;
+ char *sender;
+ char *body_signature;
+ int body_length;
+ char *arg0;
+ char *arg1;
+ char *arg2;
+ char *name_acquired;
+ char *name_lost;
+
+ /* How to add the 'sender' field in the headers */
+ int new_header_offset;
+ int len_offset;
+ int padding_end;
+};
+
+int dbus_message_type_from_string(const char *type_str);
+
+int dbus_message_parse(unsigned char *message, size_t len,
+ struct dbus_message *dbus_message);
+
+#endif /* DBUS_MESSAGE_H */
--
1.7.10
--
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