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Today's Topics:
1. [PATCH] dnsproxy: Enable fallback nameservers when default
service changes (Patrik Flykt)
2. Try to run connman/bluez as no-root (Zheng, Wu)
----------------------------------------------------------------------
Message: 1
Date: Fri, 1 Apr 2016 12:29:57 +0300
From: Patrik Flykt <[email protected]>
To: [email protected], [email protected]
Subject: [PATCH] dnsproxy: Enable fallback nameservers when default
service changes
Message-ID:
<[email protected]>
Enable fallback nameservers if there are no service specific ones. The
fallback nameservers will be enabled when the default service changes or
the last service specific nameservers are removed.
Reported by Viliam Lejcik.
---
Please test,
Patrik
src/dnsproxy.c | 36 ++++++++++++++++++++++++++++++++++++
1 file changed, 36 insertions(+)
diff --git a/src/dnsproxy.c b/src/dnsproxy.c
index 206008f..f3ebcf0 100644
--- a/src/dnsproxy.c
+++ b/src/dnsproxy.c
@@ -2525,6 +2525,25 @@ static int server_create_socket(struct server_data *data)
return 0;
}
+static void enable_fallback(bool enable)
+{
+ GSList *list;
+
+ for (list = server_list; list; list = list->next) {
+ struct server_data *data = list->data;
+
+ if (data->index != -1)
+ continue;
+
+ if (enable)
+ DBG("Enabling fallback DNS server %s", data->server);
+ else
+ DBG("Disabling fallback DNS server %s", data->server);
+
+ data->enabled = enable;
+ }
+}
+
static struct server_data *create_server(int index,
const char *domain, const char *server,
int protocol)
@@ -2611,6 +2630,8 @@ static struct server_data *create_server(int index,
data->index)) {
data->enabled = true;
DBG("Adding DNS server %s", data->server);
+
+ enable_fallback(false);
}
server_list = g_slist_append(server_list, data);
@@ -2772,12 +2793,22 @@ static void remove_server(int index, const char *domain,
const char *server, int protocol)
{
struct server_data *data;
+ GSList *list;
data = find_server(index, server, protocol);
if (!data)
return;
destroy_server(data);
+
+ for (list = server_list; list; list = list->next) {
+ struct server_data *data = list->data;
+
+ if (data->index != -1 && data->enabled == true)
+ return;
+ }
+
+ enable_fallback(true);
}
int __connman_dnsproxy_remove(int index, const char *domain,
@@ -2830,6 +2861,7 @@ static void dnsproxy_offline_mode(bool enabled)
static void dnsproxy_default_changed(struct connman_service *service)
{
+ bool server_enabled = false;
GSList *list;
int index;
@@ -2854,12 +2886,16 @@ static void dnsproxy_default_changed(struct
connman_service *service)
if (data->index == index) {
DBG("Enabling DNS server %s", data->server);
data->enabled = true;
+ server_enabled = true;
} else {
DBG("Disabling DNS server %s", data->server);
data->enabled = false;
}
}
+ if (!server_enabled)
+ enable_fallback(true);
+
cache_refresh();
}
--
2.8.0.rc3
------------------------------
Message: 2
Date: Fri, 1 Apr 2016 10:27:48 +0000
From: "Zheng, Wu" <[email protected]>
To: Patrik Flykt <[email protected]>
Cc: "[email protected]" <[email protected]>, "Barbieri, Gustavo"
<[email protected]>, "Von Dentz, Luiz"
<[email protected]>, "Jia, Pei P" <[email protected]>,
"Hedberg, Johan" <[email protected]>
Subject: Try to run connman/bluez as no-root
Message-ID:
<2cf57a644018a745b8fe029c7223e16e12f7b...@shsmsx104.ccr.corp.intel.com>
Content-Type: text/plain; charset="us-ascii"
Hi Patrick,
We want to run connman/bluez as no-root.
Firstly, we can talk about for connman.
1. We use local patch to run connman/bluez as no-root. However, it exists
risk(maybe, some cases can't be touch).
If upstream can support onnman/bluez as no-root, it will reduce the risk very
much.
We have talked the topic in https://github.com/otcshare/meta-iot-os/pull/159
2. Gustavo have an solution for it.
Thanks.
"Connman/bluez/ofono can do privileged operations at the beginning and then
drop to a different user OR spawn a child process that keeps the privileges and
the main, unprivileged process, would talk via pipe to request operations that
are executed in runtime.
a. create 2xpipe() [send, receive]
b. fork()
c. parent is comman, it will drop privileges. When needed it will
write(child_write_fd...) and then read(master_read_fd... to wait for completion.
d. child is privileged, but it can drop all caps that are not needed and then
enter a blocking while (read(child_read_fd, ...). It will execute command as
instructed and reply with results.
We don't need to do it for all capabilities at the beginning, we can start with
only /proc and /sys writes, so we'd define some set of helpers that you could
easily change existing code, like:
int sysfs_write(const char *path, const char *mode, const char *data)
{
size_t payload_len = strlen(path) + strlen(mode) + strlen(data) + 3;
int cmd = SYSFS_WRITE;
int r, ret;
r = safe_write(child_write_fd, &cmd, sizeof(cmd));
if (r < 0) die("failed to communicate with privilege process");
r = safe_write(child_write_fd, &payload_len, sizeof(payload_len));
if (r < 0) die("failed to communicate with privilege process");
r = safe_write(child_write_fd, path, strlen(path) + 1);
if (r < 0) die("failed to communicate with privilege process");
r = safe_write(child_write_fd, mode, strlen(mode) + 1);
if (r < 0) die("failed to communicate with privilege process");
r = safe_write(child_write_fd, data, strlen(data) + 1);
if (r < 0) die("failed to communicate with privilege process");
r = read_safe(master_read_fd, &ret, sizeof(ret));
if (r < 0) die("failed to communicate with privilege process");
return ret;
}
Then
http://git.kernel.org/cgit/network/connman/connman.git/tree/src/bridge.c#n41
could be changed without major work, it would replace internal
fopen()/fprintf()/fclose() with that wrapper.
Ideally we'd move all operations that require privilege to that daemon, so the
main process where the computation is done, can't do mistakes even if hacked
since the interface to the write commands above would be limited to only write
some files, we could even use the SECCOMP to disable other syscalls.
"
Do you have some ideas for running connman as no-root?
Thanks.
Best Regards
Zheng Wu
------------------------------
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