18 ms·

I find interesting that GNOME Screensaver's security depends on it to not crash. Meanwhile, in KDE the lock screen is managed by KDE Session Management Server

I find interesting that GNOME Screensaver's security depends on it to not crash. Meanwhile, in KDE the lock screen is managed by KDE Session Management Server which ensures that lock screen cannot be bypassed by simply crashing its process. The way it works is follows: ksmserver draws a black rectangle over everything and spawns kscreenlocker. If kscreenlocker crashes, the black rectangle is still here, and ksmserver will spawn kscreenlocker again but this time with software rendering (just in case it crashed due to graphics driver issue). If kscreenlocker crashes four times then KDE Session Management Server gives up, stops respawning kscreenlocker and simply draws the following text on the screen. The screen locker is broken and unlocking is not possible anymore. In order to unlock switch to a virtual terminal (e.g. Ctrl+Alt+F2), log in and execute the command: loginctl unlock-session %1 Afterwards switch back to the running session (Ctrl+Alt+F%2). If ksmserver itself crashes then the entire session closes. I'm not sure why GNOME screensaver cannot do something like this. Lock screen crashing seems like something inevitable (especially considering buggy graphic card drivers and so on), and it makes sense to prepare for it so that crashes won't bypass the screen locker.

dr_cypher 6y ago
jwz has a lot to say about complex graphical toolkits/desktop environments and their complex locking mechanisms. It's an interesting series of posts. If you are not running xscreensaver on Linux, then it is safe to assume that your screen does not lock. Once is happenstance. Twice is coincidence. Three times is enemy action. Four times is Official GNOME Policy. https://www.jwz.org/xscreensaver/toolkits.html https://www.jwz.org/xscreensaver/toolkits.html
- GlitchMr 6y ago
  I would recommend not linking to jwz's website. Use web archive or something if you have to. jwz dislikes Hacker News and intentionally shows an NSFW image when Referer header shows Hacker News.
  - smnrchrds 6y ago
    Can he at least update the text? HN was full of entrepreneurs and wantrepreneurs years ago. It is mostly big- and mid tech employees now, tech bureaucrats if you will.
    - nefitty 6y ago
      Not to belabor the meta discussion, but your comment sparked a question. If it is how you say, and using a politico-economic lens, I wonder if there has been any discernible shift in commenter attitudes as the demographics have changed. Specifically, if the shift was from entrepreneurs -> skilled wage workers, as you’ve asserted. The interests of the petit bourgeoisie (entrepreneurs, et al), the professional management class and that of skilled workers sometimes overlap. I think those overlaps would probably translate to some overarching strains of belief, for example, the tendency toward libertarian viewpoints on HN. Sorry for the tangent, just had to get that out of my head!
      - toyg 6y ago
        This is OT, but I can't resist. I've been around HN since 2011, and tone has definitely shifted in the last 5-6 years. I used to stumble on HN posts that infuriated me relatively often, it was part of the deal (i.e. understanding how the self-appointed entrepreneurial classes actually rationalize certain things). That doesn't really happen anymore. > those overlaps would probably translate to some overarching strains of belief, for example, the tendency toward libertarian viewpoints The opposite is actually true, in my experience. Hardcore libertarian views on HN have been largely quashed into irrelevance, they only survive in lore. New commenters who join and expect HN to be a nest of hyper-capitalists are quickly downvoted into oblivion. Which is not a terrible thing in the great scheme of things, from the personal perspective of somebody who would likely dislike their point of view; but it has definitely taken something away from the HN experience, and possibly pushed some people towards worse (more radicalized) forums.
        smnrchrds 6y ago
        What I miss about the old HN is learning about all the cool new programming tools, libraries, frameworks, etc and participating in the discussions about them. These days, you rarely see posts about programming tools, unless it is one of the big ones like React, Qt, or TypeScript. I used to stumble upon so many great tools on HN, but that has become a rare experience these days. Is there still somewhere on the web, perhaps on Reddit or another platform, where you can find such posts and discussions?
- smnrchrds 6y ago
  Never directly link to jwz from HN. https://web.archive.org/web/20210117212403/https://www.jwz.org/xscreensaver/toolkits.html https://web.archive.org/web/20210117212403/https://www.jwz.o...
  - deleted 6y ago
    [deleted]
  - deleted 6y ago
    [deleted]
  - vlovich123 6y ago
    Why?
    - notRobot 6y ago
      Because you won't be able to actually view anything on the website.
    - thesh4d0w 6y ago
      Cause he redirects based on referrer to https://cdn.jwz.org/images/2016/hn.png https://cdn.jwz.org/images/2016/hn.png
      - Naracion 6y ago
        I did not get redirected--would that be because I'm using Brave? Or because I'm on mobile?
        smnrchrds 6y ago
        The former. Brave has explained their referer policy here: https://brave.com/privacy-updates-5/ https://brave.com/privacy-updates-5/ > When navigating to a new site, never send a referer header. JWZ wouldn't know you are visiting from HN if you use Brave.
        6y ago
- charlesdaniels 6y ago
  Anecdotally, I use xidle[0] and xlock[1], and have found both to be very reliable. xidle supports locking the screen by sending it SIGUSR1, which is really useful since you can trigger it from a process that doesn't have DISPLAY set. The trick on laptops is to block on sending the signal in the script you use to suspend, so that when the laptop resumes the display is already locked. 0 - https://github.com/steinex/xidle-linux https://github.com/steinex/xidle-linux 1 - http://sillycycle.com/xlockmore.html http://sillycycle.com/xlockmore.html
  - johnmaguire2013 6y ago
    I use physlock[0] which locks all of the ttys. I've had no issues. [1] https://github.com/muennich/physlock https://github.com/muennich/physlock
- xanax 6y ago
  I don't think that's the right link mate. I got redirected.
awestroke 6y ago
That does sound much more sane.
inetknght 6y ago
I actually had this happen around Christmas (using Manjaro). I had no idea what the message really meant or what caused it. The instructions were at least clear enough to get back into the running session, which is far better than, say, most of GNOME's crap.
- Blikkentrekker 6y ago
  Our internal research found that clear error messages confused our users, so we removed it. I have no idea what KDE is or does, sorry.
  - inetknght 6y ago
    > Our internal research found that clear error messages confused our users and removed it. I can't tell if this is sarcasm or if you're serious. If you're serious, please tell me what product you've butchered so I can avoid it like the plague. Clear error messages only confuse people who shouldn't be using the product in the first place. More importantly: a clear error message at the cost of a few confused users is far more important than an unclear error message that costs even more users hours or days of trouble. I would far rather have a message that tells me that the software broke because the desktop manager found a crash loop and point me to the crash loop logs even if some other poor unfortunate soul has no idea what a crash log is or can't figure out how to access or understand the crash log.
    - Minor49er 6y ago
      I've had similar discussions at a previous job with their platform (it was a marketing dashboard). Management wanted developers to suppress error messages because users wouldn't know what to do with them. However, users always contact the help desk when things go wrong. User feedback became much harder for us to understand, so issues would take much longer to resolve. Instead of saying "I did ABC and I saw a message that said 'XYZ'", they would say "I did ABC and it broke"
    - genpfault 6y ago
      Given the "I have no idea what KDE is or does, sorry." I suspect it's a reference to the 'ole "I have no idea what XFCE is or does sorry."[1][2] [1]: https://trac.transmissionbt.com/ticket/3685#comment:4 https://trac.transmissionbt.com/ticket/3685#comment:4 [2]: https://web.archive.org/web/20130429182829/http://www.linuxuser.co.uk/opinion/a-linux-conspiracy-theory https://web.archive.org/web/20130429182829/http://www.linuxu...
deleted 6y ago
[deleted]
noisy_boy 6y ago
> I'm not sure why GNOME screensaver cannot do something like this. Lock screen crashing seems like something inevitable (especially considering buggy graphic card drivers and so on), and it makes sense to prepare for it so that crashes won't bypass the screen locker. That is an option Linux Mint is considering[0] among other options. [0]: https://github.com/linuxmint/cinnamon-screensaver/issues/354#issuecomment-762748215 https://github.com/linuxmint/cinnamon-screensaver/issues/354...
wrsh07 6y ago
This is a good lesson in "failing open" vs "failing closed"
anticensor 6y ago
Interestingly, there is a race condition in GNOME lock screen which sometimes blocks sleep until unlocking.
cycloptic 6y ago
>I'm not sure why GNOME screensaver cannot do something like this. This actually is fixed in upstream GNOME because the screensaver is now built into the shell. The problem here is exclusively with cinnamon-screensaver and other components derived from gnome-screensaver, which is unmaintained and upstream GNOME considers it obsolete.
- fao_ 6y ago
  [counter-factual information produced by a misreading of what was stated in the github comments - deleted :)]
Const-me 6y ago
In Windows it’s also good. The way it works is follows. The OS support multiple desktops. Similar to files or registry keys, desktops have security descriptors attached (a data structure keeping who’s the owner, and optionally listing users/groups with their respective permissions on the object being controlled). To do anything on a desktop, like create windows, paint stuff, or interact with windows on that desktop, user doing that is required to pass an access check against the security descriptor of the desktop. If failed, these GUI-related functions gonna return “access denied” status code instead of doing anything. The login screen is simply rendered on a separate desktop. That desktop has restrictive security descriptor, most users don’t have permissions to interact with them. UAC prompts are also displayed on another desktop, that’s how it’s impossible to automate them from within a program who triggered the UAC prompt. BTW, about crashing GPU drivers, on modern Windows the condition is recoverable. The symptoms are black screen for a second, then the OS resets the hardware, restarts the driver, and resumes rendering of the desktop. Observed quite a few times working on advanced GPU stuff, especially compute shaders.
- Sohcahtoa82 6y ago
  > BTW, about crashing GPU drivers, on modern Windows the condition is recoverable. The symptoms are black screen for a second, then the OS resets the hardware, restarts the driver, and resumes rendering of the desktop. Observed quite a few times working on advanced GPU stuff, especially compute shaders. When I mine cryptocurrency while playing games, I appear to sometimes run out of GPU memory (Both Task Manager and MSI Afterburner let me monitor usage) and I have experienced this reset. It's surprisingly graceful, even when a game is running, though NVIDIA Broadcast often doesn't like it and needs to be restarted, and I will sometimes see lingering graphical glitches in the game until I restart, but it's not game breaking. You can also trigger a GPU reset manually with CTRL-WIN-SHIFT-B.
dheera 6y ago
The Gnome screensaver lock is only a fluffy fake security mechanism. It's not real security. I've had many instances where my CPU was bogged down and after hitting the keyboard I could use the computer for a good several seconds before the lock screen popped up asking for a password.
brnt 6y ago
I have no idea why GNOME is the default DE for the big distros (Redhat et al, Ubuntu). Technically it's evidently inferior, it had substandard ergonomics and features like accesibility services. I really dont get it.
cuillevel3 6y ago
This bug is not about the Gnome screensaver. This is about Cinnamon, which forked from Gnome 3 in 2013.

dr_cypher 6y ago

jwz has a lot to say about complex graphical toolkits/desktop environments and their complex locking mechanisms. It's an interesting series of posts. If you are not running xscreensaver on Linux, then it is safe to assume that your screen does not lock. Once is happenstance. Twice is coincidence. Three times is enemy action. Four times is Official GNOME Policy. https://www.jwz.org/xscreensaver/toolkits.html https://www.jwz.org/xscreensaver/toolkits.html

GlitchMr 6y ago
I would recommend not linking to jwz's website. Use web archive or something if you have to. jwz dislikes Hacker News and intentionally shows an NSFW image when Referer header shows Hacker News.
- smnrchrds 6y ago
  Can he at least update the text? HN was full of entrepreneurs and wantrepreneurs years ago. It is mostly big- and mid tech employees now, tech bureaucrats if you will.
  - nefitty 6y ago
    Not to belabor the meta discussion, but your comment sparked a question. If it is how you say, and using a politico-economic lens, I wonder if there has been any discernible shift in commenter attitudes as the demographics have changed. Specifically, if the shift was from entrepreneurs -> skilled wage workers, as you’ve asserted. The interests of the petit bourgeoisie (entrepreneurs, et al), the professional management class and that of skilled workers sometimes overlap. I think those overlaps would probably translate to some overarching strains of belief, for example, the tendency toward libertarian viewpoints on HN. Sorry for the tangent, just had to get that out of my head!
    - toyg 6y ago
      This is OT, but I can't resist. I've been around HN since 2011, and tone has definitely shifted in the last 5-6 years. I used to stumble on HN posts that infuriated me relatively often, it was part of the deal (i.e. understanding how the self-appointed entrepreneurial classes actually rationalize certain things). That doesn't really happen anymore. > those overlaps would probably translate to some overarching strains of belief, for example, the tendency toward libertarian viewpoints The opposite is actually true, in my experience. Hardcore libertarian views on HN have been largely quashed into irrelevance, they only survive in lore. New commenters who join and expect HN to be a nest of hyper-capitalists are quickly downvoted into oblivion. Which is not a terrible thing in the great scheme of things, from the personal perspective of somebody who would likely dislike their point of view; but it has definitely taken something away from the HN experience, and possibly pushed some people towards worse (more radicalized) forums.
      - smnrchrds 6y ago
        What I miss about the old HN is learning about all the cool new programming tools, libraries, frameworks, etc and participating in the discussions about them. These days, you rarely see posts about programming tools, unless it is one of the big ones like React, Qt, or TypeScript. I used to stumble upon so many great tools on HN, but that has become a rare experience these days. Is there still somewhere on the web, perhaps on Reddit or another platform, where you can find such posts and discussions?
smnrchrds 6y ago
Never directly link to jwz from HN. https://web.archive.org/web/20210117212403/https://www.jwz.org/xscreensaver/toolkits.html https://web.archive.org/web/20210117212403/https://www.jwz.o...
- deleted 6y ago
  [deleted]
- deleted 6y ago
  [deleted]
- vlovich123 6y ago
  Why?
  - notRobot 6y ago
    Because you won't be able to actually view anything on the website.
  - thesh4d0w 6y ago
    Cause he redirects based on referrer to https://cdn.jwz.org/images/2016/hn.png https://cdn.jwz.org/images/2016/hn.png
    - Naracion 6y ago
      I did not get redirected--would that be because I'm using Brave? Or because I'm on mobile?
      - smnrchrds 6y ago
        The former. Brave has explained their referer policy here: https://brave.com/privacy-updates-5/ https://brave.com/privacy-updates-5/ > When navigating to a new site, never send a referer header. JWZ wouldn't know you are visiting from HN if you use Brave.
        6y ago
charlesdaniels 6y ago
Anecdotally, I use xidle[0] and xlock[1], and have found both to be very reliable. xidle supports locking the screen by sending it SIGUSR1, which is really useful since you can trigger it from a process that doesn't have DISPLAY set. The trick on laptops is to block on sending the signal in the script you use to suspend, so that when the laptop resumes the display is already locked. 0 - https://github.com/steinex/xidle-linux https://github.com/steinex/xidle-linux 1 - http://sillycycle.com/xlockmore.html http://sillycycle.com/xlockmore.html
- johnmaguire2013 6y ago
  I use physlock[0] which locks all of the ttys. I've had no issues. [1] https://github.com/muennich/physlock https://github.com/muennich/physlock
xanax 6y ago
I don't think that's the right link mate. I got redirected.

awestroke 6y ago

That does sound much more sane.

inetknght 6y ago

I actually had this happen around Christmas (using Manjaro). I had no idea what the message really meant or what caused it. The instructions were at least clear enough to get back into the running session, which is far better than, say, most of GNOME's crap.

Blikkentrekker 6y ago
Our internal research found that clear error messages confused our users, so we removed it. I have no idea what KDE is or does, sorry.
- inetknght 6y ago
  > Our internal research found that clear error messages confused our users and removed it. I can't tell if this is sarcasm or if you're serious. If you're serious, please tell me what product you've butchered so I can avoid it like the plague. Clear error messages only confuse people who shouldn't be using the product in the first place. More importantly: a clear error message at the cost of a few confused users is far more important than an unclear error message that costs even more users hours or days of trouble. I would far rather have a message that tells me that the software broke because the desktop manager found a crash loop and point me to the crash loop logs even if some other poor unfortunate soul has no idea what a crash log is or can't figure out how to access or understand the crash log.
  - Minor49er 6y ago
    I've had similar discussions at a previous job with their platform (it was a marketing dashboard). Management wanted developers to suppress error messages because users wouldn't know what to do with them. However, users always contact the help desk when things go wrong. User feedback became much harder for us to understand, so issues would take much longer to resolve. Instead of saying "I did ABC and I saw a message that said 'XYZ'", they would say "I did ABC and it broke"
  - genpfault 6y ago
    Given the "I have no idea what KDE is or does, sorry." I suspect it's a reference to the 'ole "I have no idea what XFCE is or does sorry."[1][2] [1]: https://trac.transmissionbt.com/ticket/3685#comment:4 https://trac.transmissionbt.com/ticket/3685#comment:4 [2]: https://web.archive.org/web/20130429182829/http://www.linuxuser.co.uk/opinion/a-linux-conspiracy-theory https://web.archive.org/web/20130429182829/http://www.linuxu...

deleted 6y ago

[deleted]

noisy_boy 6y ago

> I'm not sure why GNOME screensaver cannot do something like this. Lock screen crashing seems like something inevitable (especially considering buggy graphic card drivers and so on), and it makes sense to prepare for it so that crashes won't bypass the screen locker. That is an option Linux Mint is considering[0] among other options. [0]: https://github.com/linuxmint/cinnamon-screensaver/issues/354#issuecomment-762748215 https://github.com/linuxmint/cinnamon-screensaver/issues/354...

wrsh07 6y ago

This is a good lesson in "failing open" vs "failing closed"

anticensor 6y ago

Interestingly, there is a race condition in GNOME lock screen which sometimes blocks sleep until unlocking.

cycloptic 6y ago

>I'm not sure why GNOME screensaver cannot do something like this. This actually is fixed in upstream GNOME because the screensaver is now built into the shell. The problem here is exclusively with cinnamon-screensaver and other components derived from gnome-screensaver, which is unmaintained and upstream GNOME considers it obsolete.

fao_ 6y ago
[counter-factual information produced by a misreading of what was stated in the github comments - deleted :)]

Const-me 6y ago

In Windows it’s also good. The way it works is follows. The OS support multiple desktops. Similar to files or registry keys, desktops have security descriptors attached (a data structure keeping who’s the owner, and optionally listing users/groups with their respective permissions on the object being controlled). To do anything on a desktop, like create windows, paint stuff, or interact with windows on that desktop, user doing that is required to pass an access check against the security descriptor of the desktop. If failed, these GUI-related functions gonna return “access denied” status code instead of doing anything. The login screen is simply rendered on a separate desktop. That desktop has restrictive security descriptor, most users don’t have permissions to interact with them. UAC prompts are also displayed on another desktop, that’s how it’s impossible to automate them from within a program who triggered the UAC prompt. BTW, about crashing GPU drivers, on modern Windows the condition is recoverable. The symptoms are black screen for a second, then the OS resets the hardware, restarts the driver, and resumes rendering of the desktop. Observed quite a few times working on advanced GPU stuff, especially compute shaders.

Sohcahtoa82 6y ago
> BTW, about crashing GPU drivers, on modern Windows the condition is recoverable. The symptoms are black screen for a second, then the OS resets the hardware, restarts the driver, and resumes rendering of the desktop. Observed quite a few times working on advanced GPU stuff, especially compute shaders. When I mine cryptocurrency while playing games, I appear to sometimes run out of GPU memory (Both Task Manager and MSI Afterburner let me monitor usage) and I have experienced this reset. It's surprisingly graceful, even when a game is running, though NVIDIA Broadcast often doesn't like it and needs to be restarted, and I will sometimes see lingering graphical glitches in the game until I restart, but it's not game breaking. You can also trigger a GPU reset manually with CTRL-WIN-SHIFT-B.

dheera 6y ago

The Gnome screensaver lock is only a fluffy fake security mechanism. It's not real security. I've had many instances where my CPU was bogged down and after hitting the keyboard I could use the computer for a good several seconds before the lock screen popped up asking for a password.

brnt 6y ago

I have no idea why GNOME is the default DE for the big distros (Redhat et al, Ubuntu). Technically it's evidently inferior, it had substandard ergonomics and features like accesibility services. I really dont get it.

cuillevel3 6y ago

This bug is not about the Gnome screensaver. This is about Cinnamon, which forked from Gnome 3 in 2013.