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Links November 2024

Interesting news about NVidia using RISC-V CPUs in all their GPUs [1]. Hopefully they will develop some fast RISC-V cores.

Interesting blog post about using an 8K TV as a monitor, I’m very tempted to do this [2].

Interesting post about how the Windows kernel development work can’t compete with Linux kernel development [3].

Paul T wrote an insightful article about the ideal of reducing complexity of computer systems and the question of from who’s perspective complexity will be reduced [4].

Interesting lecture at the seL4 symposium about the PANCAKE language for verified systems programming [5]. The idea that “if you are verifying your code types don’t help much” is interesting.

Interesting lecture from the seL4 summit about real world security, starts with the big picture and ends with seL4 specifics [6].

Interesting lecture from the seL4 summit about Cog’s work building a commercial virtualised phome [7]. He talks about not building a “brick of a smartphone that’s obsolete 6 months after release”, is he referring to the Librem5?

Informative document about how Qualcom prevents OSs from accessing EL2 on Snapdragon devices with a link to a work-around for devices shipped with Windows (not Android), this means that only Windows can use the hypervisor features of those CPUs [8].

Linus tech tips did a walk through of an Intel fab, I learned a few things about CPU manufacture [9].

Interesting information on the amount of engineering that can go into a single component. There’s lots of parts that are grossly overpriced (Dell and HP have plenty of examples in their catalogues) but generally aerospace doesn’t have much overpricing [10].

Interesting lecture about TEE on RISC-V with the seL4 kernel [11].

Ian Jackson wrote an informative blog post about the repeating issue of software licenses that aren’t free enough with Rust being the current iteration of this issue [12].

The quackery of Master Bates to allegedly remove the need for glasses is still going around [13].

Solving Spam and Phishing for Corporations

Centralisation and Corporations

An advantage of a medium to large company is that it permits specialisation. For example I’m currently working in the IT department of a medium sized company and because we have standardised hardware (Dell Latitude and Precision laptops, Dell Precision Tower workstations, and Dell PowerEdge servers) and I am involved in fixing all Linux compatibility issues on that I can fix most problems in a small fraction of the time that I would take to fix on a random computer. There is scope for a lot of debate about the extent to which companies should standardise and centralise things. But for computer problems which can escalate quickly from minor to serious if not approached in the correct manner it’s clear that a good deal of centralisation is appropriate.

For people doing technical computer work such as programming there’s a large portion of the employees who are computer hobbyists who like to fiddle with computers. But if the support system is run well even they will appreciate having computers just work most of the time and for a large portion of the failures having someone immediately recognise the problem, like the issues with NVidia drivers that I have documented so that first line support can implement workarounds without the need for a lengthy investigation.

A big problem with email in the modern Internet is the prevalence of Phishing scams. The current corporate approach to this is to send out test Phishing email to people and then force computer security training on everyone who clicks on them. One problem with this is that attackers only need to fool one person on one occasion and when you have hundreds of people doing something on rare occasions that’s not part of their core work they will periodically get it wrong. When every test Phishing run finds several people who need extra training it seems obvious to me that this isn’t a solution that’s working well. I will concede that the majority of people who click on the test Phishing email would probably realise their mistake if asked to enter the password for the corporate email system, but I think it’s still clear that this isn’t a great solution.

Let’s imagine for the sake of discussion that everyone in a company was 100% accurate at identifying Phishing email and other scam email, if that was the case would the problem be solved? I believe that even in that hypothetical case it would not be a solved problem due to the wasted time and concentration. People can spend minutes determining if a single email is legitimate. On many occasions I have had relatives and clients forward me email because they are unsure if it’s valid, it’s great that they seek expert advice when they are unsure about things but it would be better if they didn’t have to go to that effort. What we ideally want to do is centralise the anti-Phishing and anti-spam work to a small group of people who are actually good at it and who can recognise patterns by seeing larger quantities of spam. When a spam or Phishing message is sent to 600 people in a company you don’t want 600 people to individually consider it, you want one person to recognise it and delete/block all 600. If 600 people each spend one minute considering the matter then that’s 10 work hours wasted!

The Rationale for Human Filtering

For personal email human filtering usually isn’t viable because people want privacy. But corporate email isn’t private, it’s expected that the company can read it under certain circumstances (in most jurisdictions) and having email open in public areas of the office where colleagues might see it is expected. You can visit gmail.com on your lunch break to read personal email but every company policy (and common sense) says to not have actually private correspondence on company systems.

The amount of time spent by reception staff in sorting out such email would be less than that taken by individuals. When someone sends a spam to everyone in the company instead of 500 people each spending a couple of minutes working out whether it’s legit you have one person who’s good at recognising spam (because it’s their job) who clicks on a “remove mail from this sender from all mailboxes” button and 500 messages are deleted and the sender is blocked.

Delaying email would be a concern. It’s standard practice for CEOs (and C*Os at larger companies) to have a PA receive their email and forward the ones that need their attention. So human vetting of email can work without unreasonable delays. If we had someone checking all email for the entire company probably email to the senior people would never get noticeably delayed and while people like me would get their mail delayed on occasion people doing technical work generally don’t have notifications turned on for email because it’s a distraction and a fast response isn’t needed. There are a few senders where fast response is required, which is mostly corporations sending a “click this link within 10 minutes to confirm your password change” email. Setting up rules for all such senders that are relevant to work wouldn’t be difficult to do.

How to Solve This

Spam and Phishing became serious problems over 20 years ago and we have had 20 years of evolution of email filtering which still hasn’t solved the problem. The vast majority of email addresses in use are run by major managed service providers and they haven’t managed to filter out spam/phishing mail effectively so I think we should assume that it’s not going to be solved by filtering. There is talk about what “AI” technology might do for filtering spam/phishing but that same technology can product better crafted hostile email to avoid filters.

An additional complication for corporate email filtering is that some criteria that are used to filter personal email don’t apply to corporate mail. If someone sends email to me personally about millions of dollars then it’s obviously not legit. If someone sends email to a company then it could be legit. Companies routinely have people emailing potential clients about how their products can save millions of dollars and make purchases over a million dollars. This is not a problem that’s impossible to solve, it’s just an extra difficulty that reduces the efficiency of filters.

It seems to me that the best solution to the problem involves having all mail filtered by a human. A company could configure their mail server to not accept direct external mail for any employee’s address. Then people could email files to colleagues etc without any restriction but spam and phishing wouldn’t be a problem. The issue is how to manage inbound mail. One possibility is to have addresses of the form it+russell.coker@example.com (for me as an employee in the IT department) and you would have a team of people who would read those mailboxes and forward mail to the right people if it seemed legit. Having addresses like it+russell.coker means that all mail to the IT department would be received into folders of the same account and they could be filtered by someone with suitable security level and not require any special configuration of the mail server. So the person who read the is mailbox would have a folder named russell.coker receiving mail addressed to me. The system could be configured to automate the processing of mail from known good addresses (and even domains), so they could just put in a rule saying that when Dell sends DMARC authenticated mail to is+$USER it gets immediately directed to $USER. This is the sort of thing that can be automated in the email client (mail filtering is becoming a common feature in MUAs).

For a FOSS implementation of such things the server side of it (including extracting account data from a directory to determine which department a user is in) would be about a day’s work and then an option would be to modify a webmail program to have extra functionality for approving senders and sending change requests to the server to automatically direct future mail from the same sender. As an aside I have previously worked on a project that had a modified version of the Horde webmail system to do this sort of thing for challenge-response email and adding certain automated messages to the allow-list.

The Change

One of the first things to do is configuring the system to add every recipient of an outbound message to the allow list for receiving a reply. Having a script go through the sent-mail folders of all accounts and adding the recipients to the allow lists would be easy and catch the common cases.

But even with processing the sent mail folders going from a working system without such things to a system like this will take some time for the initial work of adding addresses to the allow lists, particularly for domain wide additions of all the sites that send password confirmation messages. You would need rules to direct inbound mail to the old addresses to the new style and then address a huge amount of mail that needs to be categorised. If you have 600 employees and the average amount of time taken on the first day is 10 minutes per user then that’s 100 hours of work, 12 work days. If you had everyone from the IT department, reception, and executive assistants working on it that would be viable. After about a week there wouldn’t be much work involved in maintaining it. Then after that it would be a net win for the company.

The Benefits

If the average employee spends one minute a day dealing with spam and phishing email then with 600 employees that’s 10 hours of wasted time per day. Effectively wasting one employee’s work! I’m sure that’s the low end of the range, 5 minutes average per day doesn’t seem unreasonable especially when people are unsure about phishing email and send it to Slack so multiple employees spend time analysing it. So you could have 5 employees being wasted by hostile email and avoiding that would take a fraction of the time of a few people adding up to less than an hour of total work per day.

Then there’s the training time for phishing mail. Instead of having every employee spend half an hour doing email security training every few months (that’s 300 hours or 7.5 working weeks every time you do it) you just train the few experts.

In addition to saving time there are significant security benefits to having experts deal with possibly hostile email. Someone who deals with a lot of phishing email is much less likely to be tricked.

Will They Do It?

They probably won’t do it any time soon. I don’t think it’s expensive enough for companies yet. Maybe government agencies already have equivalent measures in place, but for regular corporations it’s probably regarded as too difficult to change anything and the costs aren’t obvious. I have been unsuccessful in suggesting that managers spend slightly more on computer hardware to save significant amounts of worker time for 30 years.

Modern Sleep

Julius wrote an insightful blog post about the “modern sleep” issue with Windows [1]. Basically Microsoft decided that the right way to run laptops is to never entirely sleep, which uses more battery but gives better options for waking up and doing things. I agree with Microsoft in concept and this is something that is a problem that can be solved. A phone can run for 24+ hours without ever fully sleeping, a laptop has a more power hungry CPU and peripherals but also has a much larger battery so it should be able to do the same. Some of the reviews for Snapdragon Windows laptops claim up to 22 hours of actual work without charging! So having suspend not really stop the system should be fine.

The ability of a phone to never fully sleep is a change in quality of the usage experience, it means that you can access it and immediately have it respond and it means that all manner of services can be checked for new updates which may require a notification to the user. The XMPP protocol (AKA Jabber) was invented in 1999 which was before laptops were common and Instant Message systems were common long before then. But using Jabber or another IM system on a desktop was a very different experience to using it on a laptop and using it on a phone is different again. The “modern sleep” allows laptops to act like phones in regard to such messaging services. Currently I have Matrix IM clients running on my Android phone and Linux laptop, if I get a notification that takes much typing for a response then I get out my laptop to respond. If I had an ARM based laptop that never fully shut down I would have much less need for Matrix on a phone.

Making “modern sleep” popular will lead to more development of OS software to work with it. For Linux this will hopefully mean that regular Linux distributions (as opposed to Android which while running a Linux kernel is very different to Debian etc) get better support for such things and therefore become more usable on phones. Debian on a Librem 5 or PinePhonePro isn’t very usable due to battery life issues.

A laptop with an LTE card can be used for full mobile phone functionality. With “modern sleep” this is a viable option. I am tempted to make a laptop with LTE card and bluetooth headset a replacement for my phone. Some people will say “what if someone tries to call you when it’s not convenient to have your laptop with you”, my response is “what if people learn to not expect me to answer the phone at any time as they managed that in the 90s”. Seriously SMS or Matrix me if you want an instant response and if you want a long chat schedule it via SMS or Matrix.

Dell has some useful advice about how to use their laptops (and probably most laptops from recent times) in this regard [2]. You can’t close the lid before unplugging the power cable you have to unplug first and then close. You shouldn’t put a laptop in a sealed bag for travel either. This is a terrible situation, you can put a tablet in a bag and don’t need to take any special precautions when unplugging and laptops should work the same. The end result of what Microsoft, Dell, Intel, and others are doing will be good but they are making some silly design choices along the way! I blame Intel mostly for selling laptop CPUs with TDPs >40W!

For an amusing take on this Linus Tech Tips has a video about being forced to use MacBooks by Microsoft’s implementation of Modern Sleep [3].

I’ll try out some ARM laptops in the near future and blog about how well they work on Debian.

More About the Yoga Gen3

Two months ago I bought a Thinkpad X1 Yoga Gen3 [1]. I’m still very happy with it, the screen is a great improvement over the FullHD screen on my previous Thinkpad. I have yet to discover what’s the best resolution to have on a laptop if price isn’t an issue, but it’s at least 1440p for a 14″ display, that’s 210DPI. The latest Thinkpad X1 Yoga is the 7th gen and has up to 3840*2400 resolution on the internal display for 323DPI. Apple apparently uses the term “Retina Display” to mean something in the range of 250DPI to 300DPI, so my current laptop is below “Retina” while the most expensive new Thinkpads are above it.

I did some tests on external displays and found that this Thinkpad along with a Dell Latitude of the same form factor and about the same age can only handle one 4K display on a Thunderbolt dock and one on HDMI. On Reddit u/Carlioso1234 pointed out this specs page which says it supports a maximum of 3 displays including the built in TFT [2]. The Thunderbolt/USB-C connection has a maximum resolution of 5120*2880 and the HDMI port has a maximum of 4K. The latest Yoga can support four displays total which means 2*5K over Thunderbolt and one 4K over HDMI. It would be nice if someone made a 8000*2880 ultrawide display that looked like 2*5K displays when connected via Thunderbolt. It would also be nice if someone made a 32″ 5K display, currently they all seem to be 27″ and I’ve found that even for 4K resolution 32″ is better than 27″.

With the typical configuration of Linux and the BIOS the Yoga Gen3 will have it’s touch screen stop working after suspend. I have confirmed this for stylus use but as the finger-touch functionality is broken I couldn’t confirm that. On r/thinkpad u/p9k told me how to fix this problem [3]. I had to set the BIOS to Win 10 Sleep aka Hybrid sleep and then put the following in /etc/systemd/system/thinkpad-wakeup-config.service :

# https://www.reddit.com/r/thinkpad/comments/1blpy20/comment/kw7se2l/?context=3

[Unit]
Description=Workarounds for sleep wakeup source for Thinkpad X1 Yoga 3
After=sysinit.target
After=systemd-modules-load.service

[Service]
Type=oneshot
ExecStart=/bin/sh -c "echo 'enabled' > /sys/devices/platform/i8042/serio0/power/wakeup"
ExecStart=/bin/sh -c "echo 'enabled' > /sys/devices/platform/i8042/serio1/power/wakeup"
ExecStart=/bin/sh -c "echo 'LID' > /proc/acpi/wakeup"

[Install]
WantedBy=multi-user.target

Now it works fine, for stylus at least. I still get kernel error messages like the following which don’t seem to cause problems:

wacom 0003:056A:5146.0005: wacom_idleprox_timeout: tool appears to be hung in-prox. forcing it out.

When it wasn’t working I got the above but also kernel error messages like:

wacom 0003:056A:5146.0005: wacom_wac_queue_insert: kfifo has filled, starting to drop events

This change affected the way suspend etc operate. Now when I connect the laptop to power it will leave suspend mode. I’ve configured KDE to suspend when the lid is closed and there’s no monitor connected.

Moving Between Devices

I previously wrote about the possibility of transferring work between devices as an alternative to “convergence” (using a phone or tablet as a desktop) [1]. This idea has been implemented in some commercial products already.

MrWhosTheBoss made a good YouTube video reviewing recent Huawei products [2]. At 2:50 in that video he shows how you can link a phone and tablet, control one from the other, drag and drop of running apps and files between phone and tablet, mirror the screen between devices, etc. He describes playing a video on one device and having it appear on the other, I hope that it actually launches a new instance of the player app as the Google Chromecast failed in the market due to remote display being laggy. At 7:30 in that video he starts talking about the features that are available when you have multiple Huawei devices, starting with the ability to move a Bluetooth pairing for earphones to a different device.

At 16:25 he shows what Huawei is doing to get apps going including allowing apk files to be downloaded and creating what they call “Quick Apps” which are instances of a web browser configured to just use one web site and make it look like a discrete app, we need something like this for FOSS phone distributions – does anyone know of a browser that’s good for it?

Another thing that we need is to have an easy way of transferring open web pages between systems. Chrome allows sending pages between systems but it’s proprietary, limited to Chrome only, and also takes an unreasonable amount of time. KDEConnect allows sharing clipboard contents which can be used to send URLs that can then be pasted into a browser, but the process of copy URL, send via KDEConnect, and paste into other device is unreasonably slow. The design of Chrome with a “Send to your devices” menu option from the tab bar is OK. But ideally we need a “Send to device” for all tabs of a window as well, we need it to run from free software and support using your own server not someone else’s server (AKA “the cloud”). Some of the KDEConnect functionality but using a server rather than direct connection over the same Wifi network (or LAN if bridged to Wifi) would be good.

What else do we need?

What is a Workstation?

I recently had someone describe a Mac Mini as a “workstation”, which I strongly disagree with. The Wikipedia page for Workstation [1] says that it’s a type of computer designed for scientific or technical use, for a single user, and would commonly run a multi-user OS.

The Mac Mini runs a multi-user OS and is designed for a single user. The issue is whether it is for “scientific or technical use”. A Mac Mini is a nice little graphical system which could be used for CAD and other engineering work. But I believe that the low capabilities of the system and lack of expansion options make it less of a workstation.

The latest versions of the Mac Mini (to be officially launched next week) have up to 64G of RAM and up to 8T of storage. That is quite decent compute power for a small device. For comparison the HP ML 110 Gen9 workstation I’m currently using was released in 2021 and has 256G of RAM and has 4 * 3.5″ SAS bays so I could easily put a few 4TB NVMe devices and some hard drives larger than 10TB. The HP Z640 workstation I have was released in 2014 and has 128G of RAM and 4*2.5″ SATA drive bays and 2*3.5″ SATA drive bays. Previously I had a Dell PowerEdge T320 which was released in 2012 and had 96G of RAM and 8*3.5″ SAS bays.

In CPU and GPU power the recent Mac Minis will compare well to my latest workstations. But they compare poorly to workstations from as much as 12 years ago for RAM and storage. Which is more important depends on the task, if you have to do calculations on 80G of data with lots of scans through the entire data set then a system with 64G of RAM will perform very poorly and a system with 96G and a CPU less than half as fast will perform better. A Dell PowerEdge T320 from 2012 fully loaded with 192G of RAM will outperform a modern Mac Mini on many tasks due to this and the T420 supported up to 384G.

Another issue is generic expansion options. I expect a workstation to have a number of PCIe slots free for GPUs and other devices. The T320 I used to use had a PCIe power cable for a power hungry GPU and I think all the T320 and T420 models with high power PSUs supported that.

I think that a usable definition of a “workstation” is a system having a feature set that is typical of servers (ECC RAM, lots of storage for RAID, maybe hot-swap storage devices, maybe redundant PSUs, and lots of expansion options) while also being suitable for running on a desktop or under a desk. The Mac Mini is nice for running on a desk but that’s the only workstation criteria it fits. I think that ECC RAM should be a mandatory criteria and any system without it isn’t a workstation. That excludes most Apple hardware. The Mac Mini is more of a thin-client than a workstation.

My main workstation with ECC RAM could run 3 VMs that each have more RAM than the largest Mac Mini that will be sold next week.

If 32G of non-ECC RAM is considered enough for a “workstation” then you could get an Android phone that counts as a workstation – and it will probably cost less than a Mac Mini.

Links October 2024

Dacid Brin wrote an interesting article about AI ecosystems and how humans might work with machines on creative projects [1]. Also he’s right about “influencers” being like funghi.

Cory Doctorow wrote an interesting post about DRM, coalitions, and cheating [2]. It seems that people like me who want “trusted computing” to secure their own computers don’t fit well in any of the coalitions.

The CHERI capability system for using extra hardware to validate jump addresses is an interesting advance in computer science [3]. The lecture is froim the seL4 Summit, this sort of advance in security goes well with a formally proven microkernel. I hope that this becomes a checkbox when ordering a custom RISC-V design.

Bunnie wrote an insightful blog post about how the Mossad might have gone about implementing the exploding pager attack [4]. I guess we will see a lot more of this in future, it seems easy to do.

Interesting blog post about Control Flow Integrity in the V8 engine of Chrome [5].

Interesting blog post about the new mseal() syscall which can be used by CFI among other things [6].

This is the Linux kernel documentation about the Control-flow Enforcement Technology (CET) Shadow Stack [7]. Unfortunately not enabled in Debian/Unstable yet.

ARM added support for Branch Target Identification in version 8.5 of the architecture [8].

The CEO of Automatic has taken his dispute with WPEngine to an epic level, this video catalogues it, I wonder what is wrong with him [9].

NuShell is an interesting development in shell technology which runs on Linux and Windows [10].

Interesting article about making a computer game without coding using ML [11]. I doubt that it would be a good game, but maybe educational for kids.

Krebs has an insightful article about location tracking by phones which is surprisingly accurate [12]. He has provided information on how to opt out of some of it on Android, but we need legislative action!

Interesting YouTube video about how to make a 20kW microwave oven and what it can do [13]. Don’t do this at home, or anywhere else!

The Void editor is an interesting project, a fork of VSCode that supports DIRECT connections to LLM systems where you don’t have their server acting as a middle-man and potentially snooping [14].

The CUPS Vulnerability

The Announcement

Late last month there was an announcement of a “severity 9.9 vulnerability” allowing remote code execution that affects “all GNU/Linux systems (plus others)” [1]. For something to affect all Linux systems that would have to be either a kernel issue or a sshd issue. The announcement included complaints about the lack of response of vendors and “And YES: I LOVE hyping the sh1t out of this stuff because apparently sensationalism is the only language that forces these people to fix”.

He seems to have a different experience to me of reporting bugs, I have had plenty of success getting bugs fixed without hyping them. I just report the bug, wait a while, and it gets fixed. I have reported potential security bugs without even bothering to try and prove that they were exploitable (any situation where you can make a program crash is potentially exploitable), I just report it and it gets fixed. I was very dubious about his ability to determine how serious a bug is and to accurately report it so this wasn’t a situation where I was waiting for it to be disclosed to discover if it affected me. I was quite confident that my systems wouldn’t be at any risk.

Analysis

Not All Linux Systems Run CUPS

When it was published my opinion was proven to be correct, it turned out to be a series of CUPS bugs [2]. To describe that as “all GNU/Linux systems (plus others)” seems like a vast overstatement, maybe a good thing to say if you want to be a TikTok influencer but not if you want to be known for computer security work.

For the Debian distribution the cups-browsed package (which seems to be the main exploitable one) is recommended by cups-daemon, as I have my Debian systems configured to not install recommended packages by default that means that it wasn’t installed on any of my systems. Also the vast majority of my systems don’t do printing and therefore don’t have any part of CUPS installed.

CUPS vs NAT

The next issue is that in Australia most home ISPs don’t have IPv6 enabled and CUPS doesn’t do the things needed to allow receiving connections from the outside world via NAT with IPv4. If inbound port 631 is blocked on both TCP and USP as is the default on Australian home Internet or if there is a correctly configured firewall in place then the network is safe from attack. There is a feature called uPnP port forwarding [3] to allow server programs to ask a router to send inbound connections to them, this is apparently usually turned off by default in router configuration. If it is enabled then there are Debian packages of software to manage this, the miniupnpc package has the client (which can request NAT changes on the router) [4]. That package is not installed on any of my systems and for my home network I don’t use a router that runs uPnP.

The only program I knowingly run that uses uPnP is Warzone2100 and as I don’t play network games that doesn’t happen. Also as an aside in version 4.4.2-1 of warzone2100 in Debian and Ubuntu I made it use Bubblewrap to run the game in a container. So a Remote Code Execution bug in Warzone 2100 won’t be an immediate win for an attacker (exploits via X11 or Wayland are another issue).

MAC Systems

Debian has had AppArmor enabled by default since Buster was released in 2019 [5]. There are claims that AppArmor will stop this exploit from doing anything bad.

To check SE Linux access I first use the “semanage fcontext” command to check the context of the binary, cupsd_exec_t means that the daemon runs as cupsd_t. Then I checked what file access is granted with the sesearch program, mostly just access to temporary files, cupsd config files, the faillog, the Kerberos cache files (not used on the Kerberos client systems I run), Samba run files (might be a possibility of exploiting something there), and the security_t used for interfacing with kernel security infrastructure. I then checked the access to the security class and found that it is permitted to check contexts and access-vectors – not access that can be harmful.

The next test was to use sesearch to discover what capabilities are granted, which unfortunately includes the sys_admin capability, that is a capability that allows many sysadmin tasks that could be harmful (I just checked the Fedora source and Fedora 42 has the same access). Whether the sys_admin capability can be used to do bad things with the limited access cupsd_t has to device nodes etc is not clear. But this access is undesirable.

So the SE Linux policy in Debian and Fedora will stop cupsd_t from writing SETUID programs that can be used by random users for root access and stop it from writing to /etc/shadow etc. But the sys_admin capability might allow it to do hostile things and I have already uploaded a changed policy to Debian/Unstable to remove that. The sys_rawio capability also looked concerning but it’s apparently needed to probe for USB printers and as the domain has no access to block devices it is otherwise harmless. Below are the commands I used to discover what the policy allows and the output from them.

# semanage fcontext -l|grep bin/cups-browsed
/usr/bin/cups-browsed                              regular file       system_u:object_r:cupsd_exec_t:s0 
# sesearch -A -s cupsd_t -c file -p write
allow cupsd_t cupsd_interface_t:file { append create execute execute_no_trans getattr ioctl link lock map open read rename setattr unlink write };
allow cupsd_t cupsd_lock_t:file { append create getattr ioctl link lock open read rename setattr unlink write };
allow cupsd_t cupsd_log_t:file { append create getattr ioctl link lock open read rename setattr unlink write };
allow cupsd_t cupsd_runtime_t:file { append create getattr ioctl link lock open read rename setattr unlink write };
allow cupsd_t cupsd_rw_etc_t:file { append create getattr ioctl link lock open read rename setattr unlink write };
allow cupsd_t cupsd_t:file { append create getattr ioctl link lock open read rename setattr unlink write };
allow cupsd_t cupsd_tmp_t:file { append create getattr ioctl link lock open read rename setattr unlink write };
allow cupsd_t faillog_t:file { append getattr ioctl lock open read write };
allow cupsd_t init_tmpfs_t:file { append getattr ioctl lock read write };
allow cupsd_t krb5_host_rcache_t:file { append create getattr ioctl link lock open read rename setattr unlink write }; [ allow_kerberos ]:True
allow cupsd_t print_spool_t:file { append create getattr ioctl link lock open read relabelfrom relabelto rename setattr unlink write };
allow cupsd_t samba_var_t:file { append getattr ioctl lock open read write };
allow cupsd_t security_t:file { append getattr ioctl lock open read write };
allow cupsd_t security_t:file { append getattr ioctl lock open read write }; [ allow_kerberos ]:True
allow cupsd_t usbfs_t:file { append getattr ioctl lock open read write };
# sesearch -A -s cupsd_t -c security
allow cupsd_t security_t:security check_context; [ allow_kerberos ]:True
allow cupsd_t security_t:security { check_context compute_av };
# sesearch -A -s cupsd_t -c capability
allow cupsd_t cupsd_t:capability net_bind_service; [ allow_ypbind ]:True
allow cupsd_t cupsd_t:capability { audit_write chown dac_override dac_read_search fowner fsetid ipc_lock kill net_bind_service setgid setuid sys_admin sys_rawio sys_resource sys_tty_config };
# sesearch -A -s cupsd_t -c capability2
allow cupsd_t cupsd_t:capability2 { block_suspend wake_alarm };
# sesearch -A -s cupsd_t -c blk_file

Conclusion

This is an example of how not to handle security issues. Some degree of promotion is acceptable but this is very excessive and will result in people not taking security announcements seriously in future. I wonder if this is even a good career move by the researcher in question, will enough people believe that they actually did something good in this that it outweighs the number of people who think it’s misleading at best?

MG4 Review

In the past I haven’t had a high opinion of MG cars, decades ago they were small and expensive and didn’t seem to offer anything I wanted. As there’s a conveniently located MG dealer I decided to try out an MG electric car and see if they are any good. I brought two friends along who are also interested in new technology.

I went to the MG dealer without any preconceptions or much prior knowledge of the MG electric cars apart from having vaguely noticed that they were significantly cheaper than Teslas. I told the salesperson that I didn’t have a model in mind and I just wanted to see what MG offers, so they offered me a test driver of a “MG4 64 EXCITE”. The MG web site isn’t very good and doesn’t give an indication of what this model costs, my recollection is that it’s something like $40,000, the base model is advertised at $30,990. I’m not particularly interested in paying for extras above the base model and the only really desirable feature that the “Excite 64” offers over the “Excite 51” is the extra range (the numbers 51 and 64 represent the battery capacity in KWh). The base model has a claimed range of 350KM which is more than I drive in a typical week, generally there are only about 4 days a year when I need to drive more than 300KM in a day and on those rare days I can spend a bit of time at a charging station without much inconvenience.

The experience of driving an MG4 is not much different from other EVs I’ve driven, the difference between that and the Genesis GV60 (which was advertised at $117,000) [1] isn’t significant. The Genesis has some nice camera features giving views from all directions and showing a view of the side on the dash when you put your turn indicator on. Also some models of Genesis (not the one I test drove) have cameras instead of side mirrors. The MG4 lacks most of those cameras but has a very effective reversing camera which estimates the distance to an “obstacle” behind you in cm. Some of the MG electric cars have a sunroof or moonroof (sunroof that just opens to transparent glass not open to the air), the one I tested didn’t have them and I didn’t feel I was missing much. While a moonroof is a nice feature I probably won’t want to pay as much extra as they will demand for it.

The dash of the MG4 doesn’t have any simulation of the old fashioned dash unlike the Genesis GV60 which had a display in the same location as is traditionally used which displays analogue instruments (except when the turn indicators are on). The MG4 has two tablets, a big one in the middle of the front for controlling heating/cooling and probably other things like the radio and a small one visible through the steering wheel which has the instruments. I didn’t have to think about the instruments, they just did the job which is great.

For second hand cars I looked at AutoTrader which seems to be the only Australian site for second hand cars that allows specifying electric as a search criteria [2]. For the EVs advertised on that site the cheapest are around $13,000 for cars about 10 years old and $21,000 for a 5yo LEAF. If you could only afford to spend $21,000 on a car then a 5yo LEAF would definitely be better than nothing, but when comparing a 5yo car for $21,000 and a new car for $31,000 the new car is the obvious choice if you can afford it. There was an Australian company importing used LEAFs and other EVs and selling them over the web for low prices, if they were still around and still selling LEAFs for $15,000 then that would make LEAF vs MG3 a difficult decision for me. But with the current prices for second hand LEAFs the decision is easy.

When I enrolled for the test drive the dealer took my email address and sent me an automated message with details about the test drive and an email address to ask for more information. The email address they used bounced all mail, even from my gmail account. They had a contact form on their web site but that also doesn’t get a response. MG really should periodically test their dealer’s email addresses, they are probably losing sales because of this.

On the same day I visited a Hyundai dealer to see what they had to offer. A salesman there said that the cheapest Hyundai was $60,000 and suggested that I go elsewhere if I am prepared to buy a lesser car to save money. I don’t need to get negged by a car dealer and I really don’t think there’s much scope for a car to be significantly better than the MG3 while also not competing with the Genesis cars. Genesis is a Hyundai brand and their cars are very nice, but the prices are well outside the range I’m prepared to pay.

Next I have to try the BYD. From what I’ve heard they are mostly selling somewhat expensive cars in Australia (a colleague recently got one which was about $60,000 which he is extremely happy with) but hopefully they have some of the cheaper ones available too. I don’t want to flex on my neighbors, I just want a reliable and moderately comfortable car that doesn’t cost too much.

Links September 2024

CNA Insider has an insightful documentary series about Chinese illegal immigrants to the US [1]. They should migrate to Australia, easier to get in and a better place to live.

Linus tech tips has an informative video about using Windows on Snapdragon ARM64 laptops. [2]. Maybe I should get one for running Linux. They are quite expensive on ebay now which is presumably a good sign about their quality.

A web site for comparing monospace fonts so you can find the one that best suits yuor coding [3]. Roboto works well for me.

Noema has an interesting article about nationhood comparing the attitudes towards European colonisation in Africa and Russian colonisation in Ukraine [4].

Insightful lecture by Grace Hopper (then Captain) about the future of computers [5]. The second part is linked from the first part. Published by the NSA.

Tony Hoare gave an insightful lecture titled “The Billion Dollar Mistake” about his work on designing the Algol language in 1965 [6]. The lecture was recorded in about 2005. But it still has a lot of relevance to computer science.

Jascha Sohl-Dickstein wrote an interesting blog post about Goodhart’s law, Machine Learning models, and how to try and mitigate problems in society [7].

Cory Doctorow wrote an insightful article on the Marshmallow test and long term thinking [8]. The rich fail this test badly.

Insightful interview with Justice Breyer about interpreting the US constitution and the problems with “textualism” and “originalism” [9].

Cory Doctorow wrote an informative article about Google’s practices of deleting Gmail accounts for no apparent reason and denying people access to their data [10]. We need more laws like the Digital Markets Act in the EU and we need them to apply to eBay/PayPal and AWS/Amazon.