af_packet v4 John Fastabend presented a new version of a patch set that was first published in January regarding the af_packet protocol family, which is currently used by tcpdump to extract packets from network interfaces. The goal of this change is to allow zero-copy transfers between user-space applications and the NIC (network interface card) transmit and receive ring buffers. Such optimizations are useful for telecommunications companies, which may use it for deep packet inspection or running exotic protocols in user space. Another use case is running a high-performance intrusion detection system that needs to watch large traffic streams in realtime to catch certain types of attacks. Fastabend presented his work during the Netdev network-performance workshop, but also brought the patch set up for discussion during Netconf. There, he said he could achieve line-rate extraction (and injection) of packets, with packet rates as high as 30Mpps. This performance gain is possible because user-space pages are directly DMA-mapped to the NIC, which is also a security concern. The other downside of this approach is that a complete pair of ring buffers needs to be dedicated for this purpose; whereas before packets were copied to user space, now they are memory-mapped, so the user-space side needs to process those packets quickly otherwise they are simply dropped. Furthermore, it's an "all or nothing" approach; while NIC-level classifiers could be used to steer part of the traffic to a specific queue, once traffic hits that queue, it is only accessible through the af_packet interface and not the rest of the regular stack. If done correctly, however, this could actually improve the way user-space stacks access those packets, providing projects like DPDK a safer way to share pages with the NIC, because it is well defined and kernel-controlled. According to Jesper Dangaard Brouer (during review of this article):

This proposal will be a safer way to share raw packet data between user space and kernel space than what DPDK is doing, [by providing] a cleaner separation as we keep driver code in the kernel where it belongs.

During the Netdev network-performance workshop, Fastabend asked if there was a better data structure to use for such a purpose. The goal here is to provide a consistent interface to user space regardless of the driver or hardware used to extract packets from the wire. af_packet currently defines its own packet format that abstracts away the NIC-specific details, but there are other possible formats. For example, someone in the audience proposed the virtio packet format. Alexei Starovoitov rejected this idea because af_packet is a kernel-specific facility while virtio has its own separate specification with its own requirements. The next step for af_packet is the posting of the new "v4" patch set, although Miller warned that this wouldn't get merged until proper XDP support lands in the Intel drivers. The concern, of course, is that the kernel would have multiple incomplete bypass solutions available at once. Hopefully, Fastabend will present the (by then) merged patch set at the next Netdev conference in November.

XDP updates Higher up in the networking stack sits XDP. The af_packet feature differs from XDP in that it does not perform any sort of analysis or mangling of packets; its objective is purely to get the data into and out of the kernel as fast as possible, completely bypassing the regular kernel networking stack. XDP also sits before the networking stack except that, according to Brouer, it is "focused on cooperating with the existing network stack infrastructure, and on use-cases where the packet doesn't necessarily need to leave kernel space (like routing and bridging, or skipping complex code-paths)." XDP has evolved quite a bit since we last covered it in LWN. It seems that most of the controversy surrounding the introduction of XDP in the Linux kernel has died down in public discussions, under the leadership of David Miller, who heralded XDP as the right solution for a long-term architecture in the kernel. He presented XDP as a fast, flexible, and safe solution. Indeed, one of the controversies surrounding XDP was the question of the inherent security challenges with introducing user-provided programs directly into the Linux kernel to mangle packets at such a low level. Miller argued that whatever protections are expected for user-space programs also apply to XDP programs, comparing the virtual memory protections to the eBPF (extended BPF) verifier applied to XDP programs. Those programs are actually eBPF that have an interesting set of restrictions:

• they have a limited size
• they cannot jump backward (and thus cannot loop), so they execute in predictable time
• they do only static allocation, so they are also limited in memory

XDP is not a one-size-fits-all solution: netfilter, the TC traffic shaper, and other normal Linux utilities still have their place. There is, however, a clear use case for a solution like XDP in the kernel. For example, Facebook and Cloudflare have both started testing XDP and, in Facebook's case, deploying XDP in production. Martin Kafai Lau, from Facebook, presented the tool set the company is using to construct a DDoS-resilience solution and a level-4 load balancer (L4LB), which got a ten-times performance improvement over the previous IPVS-based solution. Facebook rolled out its own user-space solution called "Droplet" to detect hostile traffic and deploy blocking rules in the form of eBPF programs loaded in XDP. Lau demonstrated the way Facebook deploys a three-part chained eBPF program: the first part allows debugging and dumping of packets, the second is Droplet itself, which drops undesirable traffic, and the last segment is the load balancer, which mangles the packets to tweak their destination according to internal rules. Droplet can drop DDoS attacks at line rate while keeping the architecture flexible, which were two key design requirements. Gilberto Bertin, from Cloudflare, presented a similar approach: Cloudflare has a tool that processes sFlow data generated from iptables in order to generate cBPF (classic BPF) mitigation rules that are then deployed on edge routers. Those rules are created with a tool called bpfgen, part of Cloudflare's BSD-licensed bpftools suite. For example, it could create a cBPF bytecode blob that would match DNS queries to any example.com domain with something like:

    bpfgen dns *.example.com

Originally, Cloudflare would deploy those rules to plain iptables firewalls with the xt_bpf module, but this led to performance issues. It then deployed a proprietary user-space solution based on Solarflare hardware, but this has the performance limitations of user-space applications getting packets back onto the wire involves the cost of re-injecting packets back into the kernel. This is why Cloudflare is experimenting with XDP, which was partly developed in response to the company's problems, to deploy those BPF programs. A concern that Bertin identified was the lack of visibility into dropped packets. Cloudflare currently samples some of the dropped traffic to analyze attacks; this is not currently possible with XDP unless you pass the packets down the stack, which is expensive. Miller agreed that the lack of monitoring for XDP programs is a large issue that needs to be resolved, and suggested creating a way to mark packets for extraction to allow analysis. Cloudflare is currently in a testing phase with XDP and it is unclear if its whole XDP tool chain will be publicly available. While those two companies are starting to use XDP as-is, there is more work needed to complete the XDP project. As mentioned above and in our previous coverage, massive statistics extraction is still limited in the Linux kernel and introspection is difficult. Furthermore, while the existing actions (XDP_DROP and XDP_TX, see the documentation for more information) are well implemented and used, another action may be introduced, called XDP_REDIRECT, which would allow redirecting packets to different network interfaces. Such an action could also be used to accelerate bridges as packets could be "switched" based on the MAC address table. XDP also requires network driver support, which is currently limited. For example, the Intel drivers still do not support XDP, although that should come pretty soon. Miller, in his Netdev keynote, focused on XDP and presented it as the standard solution that is safe, fast, and usable. He identified the next steps of XDP development to be the addition of debugging mechanisms, better sampling tools for statistics and analysis, and user-space consistency. Miller foresees a future for XDP similar to the popularization of the Arduino chips: a simple set of tools that anyone, not just developers, can use. He gave the example of an Arduino tutorial that he followed where he could just look up a part number and get easy-to-use instructions on how to program it. Similar components should be available for XDP. For this purpose, the conference saw the creation of a new mailing list called xdp-newbies where people can learn how to create XDP build environments and how to write XDP programs.

In-kernel layer-7 proxying The third approach that struck me as innovative is the idea of doing layer-7 (application) proxying directly in the kernel. This comes from the idea that, traditionally, we build firewalls to segregate traffic and apply controls, but as most services move to HTTP, those policies become ineffective. Thomas Graf, presented this idea during Netconf using a Star Wars allegory: what if the Death Star were a server with an API? You would have endpoints like /dock or /comms that would allow you to dock a ship or communicate with the Death Star. Those API endpoints should obviously be public, but then there is this /exhaust-port endpoint that should never be publicly available. In order for a firewall to protect such a system, it must be able to inspect traffic at a higher level than the traditional address-port pairs. Graf presented a design where the kernel would create an in-kernel socket that would negotiate TCP connections on behalf of user space and then be able to apply arbitrary eBPF rules in the kernel. In this scenario, instead of doing the traditional transfer from Netfilter's TPROXY to user space, the kernel directly decapsulates the HTTP traffic and passes it to BPF rules that can make decisions without doing expensive context switches or memory copies in the case of simply wanting to refuse traffic (e.g. issue an HTTP 403 error). This, of course, requires the inclusion of kTLS to process HTTPS connections. HTTP2 support may also prove problematic, as it multiplexes connections and is harder to decapsulate. This design was described as a "pure pre-accept() hook". Starovoitov also compared the design to the kernel connection multiplexer (KCM). Tom Herbert, KCM's author, agreed that it could be extended to support this, but would require some extensions in user space to provide an interface between regular socket-based applications and the KCM layer. In any case, if the application does TLS (and lots of them do), kTLS gets tricky because it breaks the end-to-end nature of TLS, in effect becoming a man in the middle between the client and the application. Eric Dumazet argued that HA-Proxy already does things like this: it uses splice() to avoid copying too much data around, but it still does a context switch to hand over processing to user space, something that could be fixed in the general case. Another similar project that was presented at Netdev is the Tempesta firewall and reverse-proxy. The speaker, Alex Krizhanovsky, explained the Tempesta developers have taken one person month to port the mbed TLS stack to the Linux kernel to allow an in-kernel TLS handshake. Tempesta also implements rate limiting, cookies, and JavaScript challenges to mitigate DDoS attacks. The argument behind the project is that "it's easier to move TLS to the kernel than it is to move the TCP/IP stack to user space". Graf explained that he is familiar with Krizhanovsky's work and he is hoping to collaborate. In effect, the design Graf is working on would serve as a foundation for Krizhanovsky's in-kernel HTTP server (kHTTP). In a private email, Graf explained that:

The main differences in the implementation are currently that we foresee to use BPF for protocol parsing to avoid having to implement every single application protocol natively in the kernel. Tempesta likely sees this less of an issue as they are probably only targeting HTTP/1.1 and HTTP/2 and to some [extent] JavaScript.

Neither project is really ready for production yet. There didn't seem to be any significant pushback from key network developers against the idea, which surprised some people, so it is likely we will see more and more layer-7 intelligence move into the kernel sooner rather than later.

Conclusion All of this work aims at replacing a rag-tag bunch of proprietary solutions that recently came up to bypass the Linux kernel TCP/IP stack and improve performance for firewalls, proxies, and other key edge network elements. The idea is that, unless the kernel improves its performance, or at least provides a way to bypass its more complex code paths, people will work around it. With this set of solutions in place, engineers will now be able to use standard APIs to hook high-performance systems into the Linux kernel.

The author would like to thank the Netdev and Netconf organizers for travel assistance, Thomas Graf for a review of the in-kernel proxying section of this article, and Jesper Dangaard Brouer for review of the af_packet and XDP sections. Note: this article first appeared in the Linux Weekly News.

Star plots are helpful for small-to-moderate-sized multivariate data sets. Their primary weakness is that their effectiveness is limited to data sets with less than a few hundred points. After that, they tend to be overwhelming.

On CVE-2016-4484, a (security)? bug in the cryptsetup initramfs integration On November 4, I was made aware of a security vulnerability in the integration of cryptsetup into initramfs. The vulnerability was discovered by security researchers Hector Marco and Ismael Ripoll of CyberSecurity UPV Research Group and got CVE-2016-4484 assigned. In this post I'll try to reflect a bit on

• the nature of the vulnerability
• the way it was published and discussed by technology news press

What CVE-2016-4484 is all about Basically, the vulnerability is about two separate but related issues:

1. Initramfs rescue shell considered harmful The main topic that Hector Marco and Ismael Ripoll address in their publication is that Debian exits into a rescue shell in case of failure during initramfs, and that this can be triggered by entering a wrong password ~93 times in a row. Indeed the Debian initramfs implementation as provided by initramfs-tools exits into a rescue shell (usually a busybox shell) after a defined amount of failed attempts to make the root filesystem available. The loop in question is in local_device_setup() at the local initramfs script In general, this behaviour is considered as a feature: if the root device hasn't shown up after 30 rounds, the rescue shell is spawned to provide the local user/admin a way to debug and fix things herself. Hector Marco and Ismael Ripoll argue that in special environments, e.g. on public computers with password protected BIOS/UEFI and bootloader, this opens an attack vector and needs to be regarded as a security vulnerability:

It is common to assume that once the attacker has physical access to the computer, the game is over. The attackers can do whatever they want. And although this was true 30 years ago, today it is not. There are many "levels" of physical access. [...] In order to protect the computer in these scenarios: the BIOS/UEFI has one or two passwords to protect the booting or the configuration menu; the GRUB also has the possibility to use multiple passwords to protect unauthorized operations. And in the case of an encrypted system, the initrd shall block the maximum number of password trials and prevent the access to the computer in that case.

While Hector and Ismael have a valid point in that the rescue shell might open an additional attack vector in special setups, this is not true for the vast majority of Debian systems out there: in most cases a local attacker can alter the boot order, replace or add boot devices, modify boot options in the (GNU GRUB) bootloader menu or modify/replace arbitrary hardware parts. The required scenario to make the initramfs rescue shell an additional attack vector is indeed very special: locked down hardware, password protected BIOS and bootloader but still local keyboard (or serial console) access are required at least. Hector and Ismael argue that the default should be changed for enhanced security:

[...] But then Linux is used in more hostile environments, this helpful (but naive) recovery services shall not be the default option.

For the reasons explained about, I tend to disagree to Hectors and Ismaels opinion here. And after discussing this topic with several people I find my opinion reconfirmed: the Debian Security Team disputes the security impact of the issue and others agree. But leaving the disputable opinion on a sane default aside, I don't think that the cryptsetup package is the right place to change the default, if at all. If you want added security by a locked down initramfs (i.e. no rescue shell spawned), then at least the bootloader (GNU GRUB) needs to be locked down by default as well. To make it clear: if one wants to lock down the boot process, bootloader and initramfs should be locked down together. And the right place to do this would be the configurable behaviour of grub-mkconfig. Here, one can set a password for GRUB and the boot parameter 'panic=1' which disables the spawning of a rescue shell in initramfs. But as mentioned, I don't agree that this would be sane defaults. The vast majority of Debian systems out there don't have any security added by locked down bootloader and initramfs and the benefit of a rescue shell for debugging purposes clearly outrivals the minor security impact in my opinion. For the few setups which require the added security of a locked down bootloader and initramfs, we already have the relevant options documented in the Securing Debian Manual:

• 4.3 Change the BIOS (again)
• 4.4 Set a LILO or GRUB password
• 4.5 Disable root prompt on the initramfs
• 4.6 Remove root prompt on the kernel

After discussing the topic with initramfs-tools maintainers today, Guilhem and me (the cryptsetup maintainers) finally decided to not change any defaults and just add a 'sleep 60' after the maximum allowed attempts were reached. 2. tries=n option ignored, local brute-force slightly cheaper Apart from the issue of a rescue shell being spawned, Hector and Ismael also discovered a programming bug in the cryptsetup initramfs integration. This bug in the cryptroot initramfs local-top script allowed endless retries of passphrase input, ignoring the tries=n option of crypttab (and the default of 3). As a result, theoretically unlimited attempts to unlock encrypted disks were possible when processed during initramfs stage. The attack vector here was that local brute-force attacks are a bit cheaper. Instead of having to reboot after max tries were reached, one could go on trying passwords. Even though efficient brute-force attacks are mitigated by the PBKDF2 implementation in cryptsetup, this clearly is a real bug. The reason for the bug was twofold:

• First, the condition in setup_mapping() responsible for making the function fail when the maximum amount of allowed attempts is reached, was never met:

  setup_mapping()
   
    [...]
    # Try to get a satisfactory password $crypttries times
    count=0                              
  
    while [ $crypttries -le 0 ]   [ $count -lt $crypttries ]; do
        export CRYPTTAB_TRIED="$count"
        count=$(( $count + 1 ))
        [...]
    done
    if [ $crypttries -gt 0 ] && [ $count -gt $crypttries ]; then
        message "cryptsetup: maximum number of tries exceeded for $crypttarget"
        return 1
    fi
    [...]
   
  

  As one can see, the while loop stops when $count -lt $crypttries. Thus the second condition $count -gt $crypttries is never met. This can easily be fixed by decreasing $count by one in case of a successful unlock attempt along with changing the second condition to $count -ge $crypttries:

  setup_mapping()
   
    [...]
    while [ $crypttries -le 0 ]   [ $count -lt $crypttries ]; do
        [...]
        # decrease $count by 1, apparently last try was successful.
        count=$(( $count - 1 ))
        [...]
    done
    if [ $crypttries -gt 0 ] && [ $count -ge $crypttries ]; then
        [...]
    fi
    [...]
   
  

  Christian Lamparter already spotted this bug back in October 2011 and provided a (incomplete) patch, but back then I even managed to merge the patch in an improper way, making it even more useless: The patch by Christian forgot to decrease $count by one in case of a successful unlock attempt, resulting in warnings about maximum tries exceeded even for successful attemps in some circumstances. But instead of adding the decrease myself and keeping the (almost correct) condition $count -eq $crypttries for detection of exceeded maximum tries, I changed back the condition to the wrong original $count -gt $crypttries that again was never met. Apparently I didn't test the fix properly back then. I definitely should do better in future!
• Second, back in December 2013, I added a cryptroot initramfs local-block script as suggested by Goswin von Brederlow in order to fix bug #678692. The purpose of the cryptroot initramfs local-block script is to invoke the cryptroot initramfs local-top script again and again in a loop. This is required to support complex block device stacks. In fact, the numberless options of stacked block devices are one of the biggest and most inglorious reasons that the cryptsetup initramfs integration scripts became so complex over the years. After all we need to support setups like rootfs on top of LVM with two separate encrypted PVs or rootfs on top of LVM on top of dm-crypt on top of MD raid. The problem with the local-block script is that exiting the setup_mapping() function merely triggers a new invocation of the very same function. The guys who discovered the bug suggested a simple and good solution to this bug: When maximum attempts are detected (by second condition from above), the script sleeps for 60 seconds. This mitigates the brute-force attack options for local attackers - even rebooting after max attempts should be faster.

About disclosure, wording and clickbaiting I'm happy that Hector and Ismael brought up the topic and made their argument about the security impacts of an initramfs rescue shell, even though I have to admit that I was rather astonished about the fact that they got a CVE assigned. Nevertheless I'm very happy that they informed the Security Teams of Debian and Ubuntu prior to publishing their findings, which put me in the loop in turn. Also Hector and Ismael were open and responsive when it came to discussing their proposed fixes. But unfortunately the way they advertised their finding was not very helpful. They announced a speech about this topic at the DeepSec 2016 in Vienna with the headline Abusing LUKS to Hack the System. Honestly, this headline is missleading - if not wrong - in several ways:

• First, the whole issue is not about LUKS, neither is it about cryptsetup itself. It's about Debians integration of cryptsetup into the initramfs, which is a compeletely different story.
• Second, the term hack the system suggests that an exploit to break into the system is revealed. This is not true. The device encryption is not endangered at all.
• Third - as shown above - very special prerequisites need to be met in order to make the mere existance of a LUKS encrypted device the relevant fact to be able to spawn a rescue shell during initramfs.

Unfortunately, the way this issue was published lead to even worse articles in the tech news press. Topics like Major security hole found in Cryptsetup script for LUKS disk encryption or Linux Flaw allows Root Shell During Boot-Up for LUKS Disk-Encrypted Systems suggest that a major security vulnerabilty was revealed and that it compromised the protection that cryptsetup respective LUKS offer. If these articles/news did anything at all, then it was causing damage to the cryptsetup project, which is not affected by the whole issue at all. After the cat was out of the bag, Marco and Ismael aggreed that the way the news picked up the issue was suboptimal, but I cannot fight the feeling that the over-exaggeration was partly intended and that clickbaiting is taking place here. That's a bit sad.

Links

• Hector Marco & Ismael Ripoll: CVE-2016-4484: Cryptsetup Initrd root Shell
• Public announcement by Hector Marco of CVE-2014-4484 on oss-security
• Discussion about CVE-2016-4484 on dm-crypt@saout.de

buildscript  
    dependencies  
        classpath 'com.android.tools.build:gradle:2.2.+'
        classpath 'com.android.tools.build:transform-api:1.5.+'
        classpath 'org.javassist:javassist:3.21.+'
        classpath 'commons-io:commons-io:2.4'
     
 

Context This section adds some context to the example. Feel free to skip it. Dashkiosk is an application to manage dashboards on many displays. It provides an Android application you can install on one of those cheap Android sticks. Under the table, the application is an embedded webview backed by the Crosswalk Project web runtime which brings an up-to-date web engine, even for older versions of Android¹. Recently, a security vulnerability has been spotted in how invalid certificates were handled. When a certificate cannot be verified, the webview defers the decision to the host application by calling the onReceivedSslError() method:

Notify the host application that an SSL error occurred while loading a resource. The host application must call either callback.onReceiveValue(true) or callback.onReceiveValue(false). Note that the decision may be retained for use in response to future SSL errors. The default behavior is to pop up a dialog.

The default behavior is specific to Crosswalk webview: the Android builtin one just cancels the load. Unfortunately, the fix applied by Crosswalk is different and, as a side effect, the onReceivedSslError() method is not invoked anymore². Dashkiosk comes with an option to ignore TLS errors³. The mentioned security fix breaks this feature. The following example will demonstrate how to patch Crosswalk to recover the previous behavior⁴.

Simple method replacement Let s replace the shouldDenyRequest() method from the org.xwalk.core.internal.SslUtil class with this version:

// In SslUtil class
public static boolean shouldDenyRequest(int error)  
    return false;
 

Transform registration Gradle Transform API enables the manipulation of compiled class files before they are converted to DEX files. To declare a transform and register it, include the following code in your build.gradle:

import com.android.build.api.transform.Context
import com.android.build.api.transform.QualifiedContent
import com.android.build.api.transform.Transform
import com.android.build.api.transform.TransformException
import com.android.build.api.transform.TransformInput
import com.android.build.api.transform.TransformOutputProvider
import org.gradle.api.logging.Logger
class PatchXWalkTransform extends Transform  
    Logger logger = null;
    public PatchXWalkTransform(Logger logger)  
        this.logger = logger
     
    @Override
    String getName()  
        return "PatchXWalk"
     
    @Override
    Set<QualifiedContent.ContentType> getInputTypes()  
        return Collections.singleton(QualifiedContent.DefaultContentType.CLASSES)
     
    @Override
    Set<QualifiedContent.Scope> getScopes()  
        return Collections.singleton(QualifiedContent.Scope.EXTERNAL_LIBRARIES)
     
    @Override
    boolean isIncremental()  
        return true
     
    @Override
    void transform(Context context,
                   Collection<TransformInput> inputs,
                   Collection<TransformInput> referencedInputs,
                   TransformOutputProvider outputProvider,
                   boolean isIncremental) throws IOException, TransformException, InterruptedException  
        // We should do something here
     
 
// Register the transform
android.registerTransform(new PatchXWalkTransform(logger))

The getInputTypes() method should return the set of types of data consumed by the transform. In our case, we want to transform classes. Another possibility is to transform resources. The getScopes() method should return a set of scopes for the transform. In our case, we are only interested by the external libraries. It s also possible to transform our own classes. The isIncremental() method returns true because we support incremental builds. The transform() method is expected to take all the provided inputs and copy them (with or without modifications) to the location supplied by the output provider. We didn t implement this method yet. This causes the removal of all external dependencies from the application.

Noop transform To keep all external dependencies unmodified, we must copy them:

@Override
void transform(Context context,
               Collection<TransformInput> inputs,
               Collection<TransformInput> referencedInputs,
               TransformOutputProvider outputProvider,
               boolean isIncremental) throws IOException, TransformException, InterruptedException  
    inputs.each  
        it.jarInputs.each  
            def jarName = it.name
            def src = it.getFile()
            def dest = outputProvider.getContentLocation(jarName, 
                                                         it.contentTypes, it.scopes,
                                                         Format.JAR);
            def status = it.getStatus()
            if (status == Status.REMOVED)   //  
                logger.info("Remove $ src ")
                FileUtils.delete(dest)
              else if (!isIncremental   status != Status.NOTCHANGED)   //  
                logger.info("Copy $ src ")
                FileUtils.copyFile(src, dest)
             
         
     
 

We also need two additional imports:

import com.android.build.api.transform.Status
import org.apache.commons.io.FileUtils

Since we are handling external dependencies, we only have to manage JAR files. Therefore, we only iterate on jarInputs and not on directoryInputs. There are two cases when handling incremental build: either the file has been removed ( ) or it has been modified ( ). In all other cases, we can safely assume the file is already correctly copied.

JAR patching When the external dependency is the Crosswalk JAR file, we also need to modify it. Here is the first part of the code (replacing ):

if ("$ src " ==~ ".*/org.xwalk/xwalk_core.*/classes.jar")  
    def pool = new ClassPool()
    pool.insertClassPath("$ src ")
    def ctc = pool.get('org.xwalk.core.internal.SslUtil') //  
    def ctm = ctc.getDeclaredMethod('shouldDenyRequest')
    ctc.removeMethod(ctm) //  
    ctc.addMethod(CtNewMethod.make("""
public static boolean shouldDenyRequest(int error)  
    return false;
 
""", ctc)) //  
    def sslUtilBytecode = ctc.toBytecode() //  
    // Write back the JAR file
    //  
  else  
    logger.info("Copy $ src ")
    FileUtils.copyFile(src, dest)
 

We also need the following additional imports to use Javassist:

import javassist.ClassPath
import javassist.ClassPool
import javassist.CtNewMethod

Once we have located the JAR file we want to modify, we add it to our classpath and retrieve the class we are interested in ( ). We locate the appropriate method and delete it ( ). Then, we add our custom method using the same name ( ). The whole operation is done in memory. We retrieve the bytecode of the modified class in . The remaining step is to rebuild the JAR file:

def input = new JarFile(src)
def output = new JarOutputStream(new FileOutputStream(dest))
//  
input.entries().each  
    if (!it.getName().equals("org/xwalk/core/internal/SslUtil.class"))  
        def s = input.getInputStream(it)
        output.putNextEntry(new JarEntry(it.getName()))
        IOUtils.copy(s, output)
        s.close()
     
 
//  
output.putNextEntry(new JarEntry("org/xwalk/core/internal/SslUtil.class"))
output.write(sslUtilBytecode)
output.close()

We need the following additional imports:

import java.util.jar.JarEntry
import java.util.jar.JarFile
import java.util.jar.JarOutputStream
import org.apache.commons.io.IOUtils

There are two steps. In , all classes are copied to the new JAR, except the SslUtil class. In , the modified bytecode for SslUtil is added to the JAR. That s all! You can view the complete example on GitHub.

More complex method replacement In the above example, the new method doesn t use any external dependency. Let s suppose we also want to replace the sslErrorFromNetErrorCode() method from the same class with the following one:

import org.chromium.net.NetError;
import android.net.http.SslCertificate;
import android.net.http.SslError;
// In SslUtil class
public static SslError sslErrorFromNetErrorCode(int error,
                                                SslCertificate cert,
                                                String url)  
    switch(error)  
        case NetError.ERR_CERT_COMMON_NAME_INVALID:
            return new SslError(SslError.SSL_IDMISMATCH, cert, url);
        case NetError.ERR_CERT_DATE_INVALID:
            return new SslError(SslError.SSL_DATE_INVALID, cert, url);
        case NetError.ERR_CERT_AUTHORITY_INVALID:
            return new SslError(SslError.SSL_UNTRUSTED, cert, url);
        default:
            break;
     
    return new SslError(SslError.SSL_INVALID, cert, url);
 

The major difference with the previous example is that we need to import some additional classes.

Android SDK import The classes from the Android SDK are not part of the external dependencies. They need to be imported separately. The full path of the JAR file is:

androidJar = "$ android.getSdkDirectory().getAbsolutePath() /platforms/" +
             "$ android.getCompileSdkVersion() /android.jar"

We need to load it before adding the new method into SslUtil class:

def pool = new ClassPool()
pool.insertClassPath(androidJar)
pool.insertClassPath("$ src ")
def ctc = pool.get('org.xwalk.core.internal.SslUtil')
def ctm = ctc.getDeclaredMethod('sslErrorFromNetErrorCode')
ctc.removeMethod(ctm)
pool.importPackage('android.net.http.SslCertificate');
pool.importPackage('android.net.http.SslError');
//  

External dependency import We must also import org.chromium.net.NetError and therefore, we need to put the appropriate JAR in our classpath. The easiest way is to iterate through all the external dependencies and add them to the classpath.

def pool = new ClassPool()
pool.insertClassPath(androidJar)
inputs.each  
    it.jarInputs.each  
        def jarName = it.name
        def src = it.getFile()
        def status = it.getStatus()
        if (status != Status.REMOVED)  
            pool.insertClassPath("$ src ")
         
     
 
def ctc = pool.get('org.xwalk.core.internal.SslUtil')
def ctm = ctc.getDeclaredMethod('sslErrorFromNetErrorCode')
ctc.removeMethod(ctm)
pool.importPackage('android.net.http.SslCertificate');
pool.importPackage('android.net.http.SslError');
pool.importPackage('org.chromium.net.NetError');
ctc.addMethod(CtNewMethod.make(" "))
// Then, rebuild the JAR...

Happy hacking!

---

1. Before Android 4.4, the webview was severely outdated. Starting from Android 5, the webview is shipped as a separate component with updates. Embedding Crosswalk is still convenient as you know exactly which version you can rely on.
2. I hope to have this fixed in later versions.
3. This may seem harmful and you are right. However, if you have an internal CA, it is currently not possible to provide its own trust store to a webview. Moreover, the system trust store is not used either. You also may want to use TLS for authentication only with client certificates, a feature supported by Dashkiosk.
4. Crosswalk being an opensource project, an alternative would have been to patch Crosswalk source code and recompile it. However, Crosswalk embeds Chromium and recompiling the whole stuff consumes a lot of resources.

Remplacer le disque Apr s avoir remarqu que /dev/sdb a t expuls de mon RAID, j'ai utilis smartmontools pour identifier le num ro de s rie du disque retirer :

smartctl -a /dev/sdb

Cette information en main, j'ai ferm l'ordinateur, retir le disque d fectueux et mis un nouveau disque vide la place.

Initialiser le nouveau disque Apr s avoir d marr avec le nouveau disque vide, j'ai copi la table de partitions avec parted. Premi rement, j'ai examin la table de partitions sur le disque dur non-d fectueux :

$ parted /dev/sda
unit s
print

et cr une nouvelle table de partitions sur le disque de remplacement :

$ parted /dev/sdb
unit s
mktable gpt

Ensuite j'ai utilis la commande mkpart pour mes 4 partitions et je leur ai toutes donn la m me taille que les partitions quivalentes sur /dev/sda. Finalement, j'ai utilis les commandes toggle 1 bios_grub (partition d'amorce) et toggle X raid (o X est le num ro de la partition) pour toutes les partitions RAID, avant de v rifier avec la commande print que les deux tables de partitions sont maintenant identiques.

Resynchroniser/recr er les RAID Pour synchroniser les donn es du bon disque (/dev/sda) vers celui de remplacement (/dev/sdb), j'ai ex cut les commandes suivantes sur mes partitions RAID1 :

mdadm /dev/md0 -a /dev/sdb2
mdadm /dev/md2 -a /dev/sdb4

et j'ai gard un oeil sur le statut de la synchronisation avec :

watch -n 2 cat /proc/mdstat

Pour acc l rer le processus, j'ai utilis le truc suivant :

blockdev --setra 65536 "/dev/md0"
blockdev --setra 65536 "/dev/md2"
echo 300000 > /proc/sys/dev/raid/speed_limit_min
echo 1000000 > /proc/sys/dev/raid/speed_limit_max

Ensuite, j'ai recr ma partition swap RAID0 comme suit :

mdadm /dev/md1 --create --level=0 --raid-devices=2 /dev/sda3 /dev/sdb3
mkswap /dev/md1

Par que la partition swap est toute neuve (il n'est pas possible de restorer une partition RAID0, il faut la re-cr er compl tement), j'ai d faire deux choses:

• remplacer le UUID pour swap dans /etc/fstab, avec le UUID donn par la commande mkswap (ou bien en utilisant la command blkid et en prenant le UUID pour /dev/md1)
• remplacer le UUID de /dev/md1 dans /etc/mdadm/mdadm.conf avec celui retourn pour /dev/md1 par la commande mdadm --detail --scan

S'assurer que l'on peut d marrer avec le disque de remplacement Pour tre certain de bien pouvoir d marrer la machine avec n'importe quel des deux disques, j'ai r install le boot loader grub sur le nouveau disque :

grub-install /dev/sdb

avant de red marrer avec les deux disques connect s. Ceci confirme que ma configuration fonctionne bien. Ensuite, j'ai d marr sans le disque /dev/sda pour m'assurer que tout fonctionnerait bien si ce disque d cidait de mourir et de me laisser seulement avec le nouveau (/dev/sdb). Ce test brise videmment la synchronisation entre les deux disques, donc j'ai d red marrer avec les deux disques connect s et puis r -ajouter /dev/sda tous les RAID1 :

mdadm /dev/md0 -a /dev/sda2
mdadm /dev/md2 -a /dev/sda4

Une fois le tout fini, j'ai red marrer nouveau avec les deux disques pour confirmer que tout fonctionne bien :

cat /proc/mdstat

et j'ai ensuite ex cuter un test SMART complet sur le nouveau disque :

smartctl -t long /dev/sdb

Remplacer le disque Apr s avoir remarqu que /dev/sdb a t expuls de mon RAID, j'ai utilis smartmontools pour identifier le num ro de s rie du disque retirer :

smartctl -a /dev/sdb

Cette information en main, j'ai ferm l'ordinateur, retir le disque d fectueux et mis un nouveau disque vide la place.

Initialiser le nouveau disque Apr s avoir d marr avec le nouveau disque vide, j'ai copi la table de partitions avec parted. Premi rement, j'ai examin la table de partitions sur le disque dur non-d fectueux :

$ parted /dev/sda
unit s
print

et cr une nouvelle table de partitions sur le disque de remplacement :

$ parted /dev/sdb
unit s
mktable gpt

Ensuite j'ai utilis la commande mkpart pour mes 4 partitions et je leur ai toutes donn la m me taille que les partitions quivalentes sur /dev/sda. Finalement, j'ai utilis les commandes toggle 1 bios_grub (partition d'amorce) et toggle X raid (o X est le num ro de la partition) pour toutes les partitions RAID, avant de v rifier avec la commande print que les deux tables de partitions sont maintenant identiques.

Resynchroniser/recr er les RAID Pour synchroniser les donn es du bon disque (/dev/sda) vers celui de remplacement (/dev/sdb), j'ai ex cut les commandes suivantes sur mes partitions RAID1 :

mdadm /dev/md0 -a /dev/sdb2
mdadm /dev/md2 -a /dev/sdb4

et j'ai gard un oeil sur le statut de la synchronisation avec :

watch -n 2 cat /proc/mdstat

Pour acc l rer le processus, j'ai utilis le truc suivant :

blockdev --setra 65536 "/dev/md0"
blockdev --setra 65536 "/dev/md2"
echo 300000 > /proc/sys/dev/raid/speed_limit_min
echo 1000000 > /proc/sys/dev/raid/speed_limit_max

Ensuite, j'ai recr ma partition swap RAID0 comme suit :

mdadm /dev/md1 --create --level=0 --raid-devices=2 /dev/sda3 /dev/sdb3
mkswap /dev/md1

Par que la partition swap est toute neuve (il n'est pas possible de restorer une partition RAID0, il faut la re-cr er compl tement), j'ai d faire deux choses:

• remplacer le UUID pour swap dans /etc/fstab, avec le UUID donn par la commande mkswap (ou bien en utilisant la command blkid et en prenant le UUID pour /dev/md1)
• remplacer le UUID de /dev/md1 dans /etc/mdadm/mdadm.conf avec celui retourn pour /dev/md1 par la commande mdadm --detail --scan

S'assurer que l'on peut d marrer avec le disque de remplacement Pour tre certain de bien pouvoir d marrer la machine avec n'importe quel des deux disques, j'ai r install le boot loader grub sur le nouveau disque :

grub-install /dev/sdb

avant de red marrer avec les deux disques connect s. Ceci confirme que ma configuration fonctionne bien. Ensuite, j'ai d marr sans le disque /dev/sda pour m'assurer que tout fonctionnerait bien si ce disque d cidait de mourir et de me laisser seulement avec le nouveau (/dev/sdb). Ce test brise videmment la synchronisation entre les deux disques, donc j'ai d red marrer avec les deux disques connect s et puis r -ajouter /dev/sda tous les RAID1 :

mdadm /dev/md0 -a /dev/sda2
mdadm /dev/md2 -a /dev/sda4

Une fois le tout fini, j'ai red marrer nouveau avec les deux disques pour confirmer que tout fonctionne bien :

cat /proc/mdstat

et j'ai ensuite ex cuter un test SMART complet sur le nouveau disque :

smartctl -t long /dev/sdb

Replace the failed drive After seeing that /dev/sdb had been kicked out of my RAID array, I used smartmontools to identify the serial number of the drive to pull out:

smartctl -a /dev/sdb

Armed with this information, I shutdown the computer, pulled the bad drive out and put the new blank one in.

Initialize the new drive After booting with the new blank drive in, I copied the partition table using parted. First, I took a look at what the partition table looks like on the good drive:

$ parted /dev/sda
unit s
print

and created a new empty one on the replacement drive:

$ parted /dev/sdb
unit s
mktable gpt

then I ran mkpart for all 4 partitions and made them all the same size as the matching ones on /dev/sda. Finally, I ran toggle 1 bios_grub (boot partition) and toggle X raid (where X is the partition number) for all RAID partitions, before verifying using print that the two partition tables were now the same.

Resync/recreate the RAID arrays To sync the data from the good drive (/dev/sda) to the replacement one (/dev/sdb), I ran the following on my RAID1 partitions:

mdadm /dev/md0 -a /dev/sdb2
mdadm /dev/md2 -a /dev/sdb4

and kept an eye on the status of this sync using:

watch -n 2 cat /proc/mdstat

In order to speed up the sync, I used the following trick:

blockdev --setra 65536 "/dev/md0"
blockdev --setra 65536 "/dev/md2"
echo 300000 > /proc/sys/dev/raid/speed_limit_min
echo 1000000 > /proc/sys/dev/raid/speed_limit_max

Then, I recreated my RAID0 swap partition like this:

mdadm /dev/md1 --create --level=0 --raid-devices=2 /dev/sda3 /dev/sdb3
mkswap /dev/md1

Because the swap partition is brand new (you can't restore a RAID0, you need to re-create it), I had to update two things:

• replace the UUID for the swap mount in /etc/fstab, with the one returned by mkswap (or running blkid and looking for /dev/md1)
• replace the UUID for /dev/md1 in /etc/mdadm/mdadm.conf with the one returned for /dev/md1 by mdadm --detail --scan

Ensuring that I can boot with the replacement drive In order to be able to boot from both drives, I reinstalled the grub boot loader onto the replacement drive:

grub-install /dev/sdb

before rebooting with both drives to first make sure that my new config works. Then I booted without /dev/sda to make sure that everything would be fine should that drive fail and leave me with just the new one (/dev/sdb). This test obviously gets the two drives out of sync, so I rebooted with both drives plugged in and then had to re-add /dev/sda to the RAID1 arrays:

mdadm /dev/md0 -a /dev/sda2
mdadm /dev/md2 -a /dev/sda4

Once that finished, I rebooted again with both drives plugged in to confirm that everything is fine:

cat /proc/mdstat

Then I ran a full SMART test over the new replacement drive:

smartctl -t long /dev/sdb

Reinstallation seems to be only option left here, but there are a few checks you can make

1. Call the terminal. Use Ctrl+Alt+F2, you should be able to get your command line.
2. Login as root. This is extreme troubleshooting. You need root
3. Check and see if startx works. (Yay! problem solved if it does!)
4. Try to see if the basic gnome packages are installed type apt-get install with basic gnome packages like gnome-desktop-environment, gdm, gnome, etc.. to see if they are installed. If not, try to install them and then run the startx command.
5. If you can t install them, or if they are already installed, try running the updating the system
   
apt-get update
apt-get upgrade
apt-get dist-upgrade //If OS is at newest version

6. If updating doesn t work and gives Failed to Fetch errors for all the source links, try pinging the network to make sure you have a connection.
   
ping google.com
ping 8.8.8.8

7. If you do have a connection, verify the sources :
   
nano /etc/apt/sources.listdeb http://ftp.us.debian.org/debian jessie main contrib non-free
   #deb-src http://ftp.us.debian.org/debian jessie main contrib non-free
   deb http://security.debian.org/ jessie/updates main contrib non-free
   #deb-src http://security.debian.org/ jessie/updates main contrib non-free
   deb http://ftp.us.debian.org/debian testing main contrib non-free
   #deb-src http://ftp.us.debian.org/debian testing main contrib non-free
   deb http://security.debian.org/ testing/updates main contrib non-free
   #deb-src http://security.debian.org/ testing/updates main contrib non-free
8. If you have no connection, check your routing table with the command netstat -nr . If this routing table is completely empty, then I ve got some bad news for you. Reinstallation is your new friend. Try and see if you can copy your files using command line. cp and ls are basically your new best friends.

Debian Long Term Support (LTS) This is my 5th month working on Debian LTS, started by Raphael Hertzog at Freexian. This is my largest month so far, in which I worked on completing the Xen and NSS packages updates from last month, but also spent a significant amount of time working on phpMyAdmin and libidn.

Updates to NSS and Xen completed This basically consisted on following up on the reviews from other security people. I basically continued building up on Brian's work and tested the package on a test server at Koumbit, which seems to have survived well the upgrade. The details are in this post to the debian-lts mailing list. As for NSS, the package was mostly complete, but I forgot to ship the tests for some reason, so I added them back. I also wrote the release team to see if it was possible to update NSS to the same version in all suites. Unfortunately, this issue is still pending, but I still hope we can find better ways of managing that package in the long term.

IDN and phpMyAdmin Most of my time this month was spent working on IDN and phpMyAdmin. Unfortunately, it turns out that someone else had worked on the libidn package. This is partly my fault: I forgot to check in the dsa-needed.txt file for assignment before working on the package. But considering how in flux the workflow currently is with the switch between the main security team and the LTS team for the wheezy maintenance, I don't feel too bad. Still, I prepared a package which was a bit more painful than it should have been because of GNUlib. I didn't even know about GNUlib before, oddly enough, and after that experience, I feel that it should just not exist at all anymore. I have filed a bug to remove that dependency at the very least, but I do not clearly see how such a tool is necessary on Debian at this point in time. But phpMyAdmin, no one had worked on that. And I understand why: even though it's a very popular package, there were quite a few outstanding issues (8!) in Wheezy, with 10-15 patches to be ported. Plus, it's ... well, PHP. And old PHP at that, with parts of it with modern autoloader classes, and other with mixed HTML and PHP content, require (and not require_once) and all sorts of nasty things you still find in the PHP universe. I nevertheless managed to produce a new Debian package for wheezy and test it on Koumbit's test servers. Hopefully, that can land into Wheezy soon.

Long term software support I am a little worried that we are, both in Jessie and Wheezy sitting in between stable releases for phpMyAdmin, something that is a recurring issue for a lot of packages in Debian stable or LTS. Sometimes, it just happens that the version that happens to be in Debian testing when it is released as stable is just not a supported release upstream. It's the case for phpMyAdmin in Jessie (4.3, whereas 4.0 and 4.4 are supported) and Wheezy (3.4, although it's unclear how long that was supported upstream). But even if the next Debian stable (Stretch), would pick a stable release upstream, there is actually no phpMyAdmin release that has a support window as long as Debian stable (roughly 3 years), let alone as long as Debian LTS (5 years). This is a similar problem with NSS: upstream is simply not supporting their product in the long term, or at least not in the terms we are used to in the Debian community (ie. only security fixes or regressions). This is, in my opinion, a real concern for the reliability and sustainability of the computing infrastructure we are creating. While some developers are of the opinion that software older than 18 months is too old, here we are shipping hardware and software in space or we have Solaris, which is supported for 16 years! Now that is a serious commitment and something we can rely on. 18 months is really, really, a tiny short time in the history of our civilization. I know computer programmers and engineers like to think of themselves in elitist terms, that they are changing the world every other year. But the truth is that things have not changed much in the last 4 decades where computing has existed, both in terms of security or functionality. Two quotes from my little quotes collection come to mind here:

Software gets slower faster than hardware gets faster. - Wirth's law The future is already here it's just not very evenly distributed. - William Gibson

Because of course, the response to my claims that computing is not really advancing is "but look! we have supercomputers in our pockets now!" Yes, of course, we do have those fancy phones and they are super-connected, but they are a threat to our fundamental rights and freedom. And those glittering advances always pale in comparison to what could be done if we wouldn't be wasting our time rewriting the same software over and over again on different, often proprietary, platforms, simply because of the megalomaniac fantasies of egoistic programmers. It would be great to build something that lasts, for a while. Software that does not need to be updated every 16 months. You'd think that something as basic as a screensaver release could survive what is basically the range of human infancy. Yet it seems we like to run mindlessly in the minefield of software development, one generation following the other without questioning the underlying assumption of infinite growth that permeates our dying civilization. I have talked about this before of course, but working with the LTS project just unnerves me so bad that I just needed to let out another rant. (For the record, I really have a lot of respect for JWZ and all the work he has done in the free software world. I frequently refer to his "no-bullshit" backup guide and use Xscreensaver daily. But I do think he was wrong in this case: asking Debian to remove Xscreensaver is just too much. The response from the maintainer was exemplary of how to handle such issues in the future. I restarted Xscreensaver after the stable update, and the message is gone, and things are still all fine. Thanks JWZ and Tormod for keeping things rolling.)

Other free software work With that in mind, I obviously didn't stop doing other computing work this month. In fact, I did a lot of work to try to generally fix the internet, that endless and not-quite-gratifying hobby so many of us are destroying our bodies to accomplish.

Build tools I have experimented a bit more with different build tools. I got worried because at some point cowbuilder got orphaned and I figured I could refresh the way I build packages for LTS. I looked into sbuild, but that ended up not bringing much improvements over my current cowbuilder setup (which I really need to document better). I was asked by the new maintainer to open a bug report to make such setups easier by guessing the basepath better, so we'll see how that goes. I did enjoy the simplicity of gitpkg and discovered cowpoke which made it about 2 times faster to build packages because I could use another server to build larger packages. I also found that gitpkg doesn't use -n by default when calling gzip, which makes it harder to reproduce tarballs when they are themselves built reproducibly, which is the case for Github tarballs (really nice of them). So I filed bug #820842 about that. It would be pretty awesome if such buildds would be available for Debian Developers to do their daily tasks. It could simply be a machine that would spin up a chroot with cowbuilder or it could even be a full, temporary VM although that would take way more resources than a simple VM with a cowbuilder setup. In the meantime, I should probably look at whalebuilder as an alternative to cowbuilder. It is a tool that supports building packages within a Docker chroot, which means that packages are built from a clean environment like pbuilder, and using COW optimisations but also without privileges or network access, which is a huge plus especially when you build untrusted packages.

Ikiwiki admonitions I have done some work to implement Moinmoin-like admonitions in Ikiwiki, something I am quite happy about since it's something I was really missing about Moinmoin. Admonitions bring a really nice way to outline certain blocks with varying severity levels and distinct styles. For example:

Admonitions are great!

This was done with a macro, but basically, since Markdown allows more or less arbitrary HTML, this can also be done with the <div> tag. I like that we don't have a new weird markup here. Yet, I still liked the sub-parser feature of MoinMoin, something that can be implemented in Ikiwiki, but it's a little more clunky. Normally, you'd probably do this with the inline macro and subpages, but it's certainly less intuitive that directly inlined content.

Ereader I got a new e-reader! I was hesitant between the Kobo Aura H20 and the Kobo Glo HD, which were the ones available at Bestbuy. So I bought both and figured I would return the other. That was a painful decision! In the end, both machines are pretty nice:

• Aura H2O
  • Pros:
    • waterproof
    • larger screen (makes it easier to see web pages and better for the eyes)
    • naturally drawn to it
  • Cons:
    • heavier
    • larger (fits in outside pocket though)
    • port cover finicky
    • more expensive (180$) - prices may go down in future
• Aura Glo HD
  • Pros
    • smaller (fits in inside pocket of both coats)
    • better resolution in theory (can't notice in practice)
    • cheaper (100$)
    • may be less common on the future (larger models more common? just a guess)
  • Cons
    • no SD card
    • smaller screen
    • power button in the middle

... but in the end, I ended up settling down on the Glo, mostly for the price. Heck, I saved around 100$, so for that amount, I could have gotten two machines so that if one breaks I would still have the other. I have ordered a cover for it on Deal Extreme about two weeks ago, and it still hasn't arrived. I suspect it's going to take a few more months to get there, by which point I may have changed e-reader again. Note that both e-readers needed an update to calibre, so I started working on a calibre backport (#818309) which I will complete soon. So anyways, I looked into better ways of transferring articles from the web to the e-reader, something which I do quite a bit to avoid spending too much time on the computer. Since the bookmark manager I use (Bookie) is pretty much dead, I started looking at other alternatives. And partly inspired by Framasoft's choice of Wallabag for their bookmarking service (Framabag), I started to look into that software, especially since my friend who currently runs the Bookie instance is thinking of switching to Wallabag as well. It seems the simplest way to browse articles remotely through a standard protocol is by implementing OPDS support in Wallabag. OPDS is a standard developed in part by the Internet Archive and it allows for browsing book collections and downloading them. Articles and bookmarks would then be presented as individual books that would be accessible from any OPDS-compatible device. Unfortunately, the Kobo e-readers don't support OPDS out of the box: you need to setup some OPDS-compatible reader like Koreader. And that I found nearly impossible to do: I was able to setup KSM (the "start menu", not to be confused with that KSM), but not Koreader in KSM. Besides, I do not want a separate OS running here on the tablet: I just want to start Koreader every once in a while. KSM just starts another system when you reboot the e-reader, something which is not really convenient on the Kobo. Basically, I just want to add Koreader as a tile in the home screen on the e-reader. I found the documentation on that topic to be sparse and hard to follow. It is often dispersed across multiple forum threads and involves uploading random binaries, often proprietary, to the e-reader. It had been a long time since I was asked to "register my software" frenetically, and I hadn't missed that one bit. So I decided to stay away from this until that solution and its documentation matures a bit.

Streaming re-established I have worked a bit on my home radio stream. I simply turned the Liquidsoap stream back online, and did a few tweaks to the documentation that I had built back then. All that experimenting led me to do two NMUs. One was for gmpc-plugins to fix a FTBFS (bug #807735) and to properly kill the shout streamer when completing the playback (bug #820908). The other was to fix the ezstream manpage (bug #573928), a patch that had been sitting there for 5 years! This was to try to find an easy way to stream random audio (say from a microphone) to the Icecast server, something which is surprisingly difficult, consider how basic that functionality is. I was surprised to see that Darkice just completely fails to start (bug #821040) and I had to fallback to the simplest ices2 software to stream the audio. I am still having issues with Liquidsoap: it's really unstable! As a server, I would expect it to keep running for days if not years. Unfortunately, there's always something that makes it crash. I had assertion failed (bug #821112) and I keep seeing it crash after 2-3 days fairly reliably, a bug I reported 3 years ago and that is still not fixed (bug #727307). Switching back the stream to Vorbis (because I was having problems with the commandline mp3 players and ogg123 is much more lightweight) created another set of problems too, this time with the phone. It seems that Android cannot stream Vorbis at all, something that is even worse in Cyanogenmod... I also had to tweak my MPD config to make the Android client be able to load the larger playlists (see dmix buffer is full).

Android apps So I have also done quite a bit of work again on my phone. I finally was told how to access from Termux from adb shell which is pretty cool because now I can start a screen on my phone and then, when I'm tired of tapping to type, I can just reconnect to it when I plug in a USB cable on my laptop. I sent a pull request to fix the documentation regarding that. I also tried to see how my SMS and Signal situation could be improved. Right now, I have two different apps to do SMS on my phone: I use both Signal and the VoIP.ms SMS client, because I do not have a contract or SIM card in my phone. Both work well independently, but it's somewhat annoying to have to switch between the two. (In fact, I feel that Signal itself has an issue with how it depends on the network to send encrypted messages: I often have to "ping" people in clear text (and therefore in the other app) so that they connect to their data plan to fetch my "secure" signal messages...) Anyways, I figured it would be nice if at least there would be a SMS fallback in Signal that would allow me to send regular text messages from signal through Voip.MS. That was dismissed really fast. Moxie even closed the conversation completely, something I had never experienced before, and doesn't feel exactly pleasant. The Voip.MS side was of course not impressed and basically shrugged it off because Signal was not receptive. I also tried to clear up the Libresignal confusion: there are 3 different projects named "Libresignal", and I am not sure I figured out the right thing, even though the issue is now closed and there's a FAQ that is supposed to make all that clear. Nevertheless, I opened two distinct feature requests to try to steer the conversation into a more productive direction: GCM-less calls and GCM support. But I'm not sure neither will go anywhere. In the meantime, I am using the official signal client, which I downloaded using gplaycli and which I keep up to date with Aptoide. Even though the reliability of that site is definitely questionable, it seems that once you have a trusted version, it is safe to upgrade, regardless of the source because there is a trust path between you and the developer. I also filed a few issues with varying levels of success/response from the community:

• Green address feature requests: pin change and pin confirmation
• AntennaPod icons are reversed, but apparently, I'm the one that's backwards, go figure
• Asked for NYC support in the excellent Transportr app, it seems that's not going to happen until I find the space to run the Android dev environment...

Random background radiation And then there's of course the monthly background noise of all the projects I happened to not only stumble on, but also file bugs or patches against:

• neomutt credits improvements: Neomutt is an amazing effort to converge all the Mutt third party patches in a common tree
• request to improve acme comparison: acme is an interesting go client for Let's Encrypt
• a small set of issues and patches for borg, mostly documentation:
  • borg diff with files
  • mention jessie-backports in install docs
  • mention openbsd and OpenSUSE in install docs
• finally filed a bug report in debian about symlink support in ncdu
• internationalization SNAFUs:
  • gitweb should default to utf8 instead of latin1
  • Apache's AddCharset config should state more clearly which documentation to read
• classic "my printer is not working" never ending story: printing fails by default with "cannot open printer description file"
• small fixes to the tuptime project, which i mentionned before
• last nit-picking: znc homepage errors

• Submitted a number of pull requests to the Ansible sever configuration tool:
  • Add the ability to specify the --allow-unauthenticated to APT. (#2023)
  • Ignore EPIPE when flushing standard input and output to avoid unnecessary and ugly tracebacks. (#14774)
  • Add an option for ansible-playbook to exit with an error if no plays were matched. (#14742)
• Various improvements to django-slack, a library to easily post messages to the Slack group-messaging utility from projects using the Django web development framework:
  • Merged a patch from Joshua Blum to update the logging integration documentation. (#39)
  • Fixed an issue when rendering various exceptions would in themselves raise an exception. (#40)
  • Improved and merged a patch from Patrick Cloke to actually allow settings to be overriden using the @override_settings decorator. (#37)
• Updated local-debian-mirror, a package that attempts to make it easy to maintain a partial local mirror of the Debian archive:
  • Added an option to exclude DEP-11 files. (ee03b21)
  • Added an option to exclude Translation-* files. (28bbf34)
  • Corrected the phrasing of the debconf prompt to not ask a direct question to appease Lintian. (13fccc7b)
• Updated django-keyerror a library to post exceptions to the KeyError.com error tracking service to support pushing tracebacks from the Celery queue processor using the task_failure signal. (#1)
• Submitted a number of pull requests for django-zebra, a collection of utilities that make it easier to integrate the Stripe payment processor and the Django web development framework:
  • Add the ability to test an incoming Stripe webhook. (#44)
  • Prefer @require_POST over an explicit check in the view. (#43)
  • Move away from the deprecated django.conf.urls.patterns method. (#45)
• Updated django-template-tests, a tool to perform simple static analysis on Django templates prior to production to improve the robustness of dynamic test generation. (e98f9fc)
• Fixed django-force-logout a library to allow administrators to log user's out of Django projects to not require a custom JSON serialiser. (c0e5d64)
• Corrected the documentation for travis.debian.net my hosted script to easily test and build Debian packages on the Travis CI continuous integration platform to reflect the actual default mirror. (4c862f0)
• Blogged about generating dynamic Python tests using metaclasses.