December 2024 - openSUSE Kernel - openSUSE Mailing Lists

Disabling /dev/fb0 on TW
by Thomas Zimmermann 06 Jan '25

06 Jan '25

tl;dr: Disable fbdev userspace interfaces on TW Hi, the upcoming Linux kernel v6.6 will contain the option to disable fbdev userspace interfaces in the kernel configuration. [1] I intent to enable this and thereby switch off /dev/fb0 et al. The tracker bug is boo#1212947. [2] * Why? The old fbdev subsystem is an endless source of bugs. For example, we recently had an out-of-bounds access in the fbdev emulation, where userspace could write beyond the end of the framebuffer memory. [3] Fbdev is under-maintained. I've been doing improvements in recent kernel releases, but only where it benefits the DRM subsystem. Disabling fbdev userspace interfaces will also help weeding out any programs that still contain hard dependencies on them. * What changes? Enabling the new kernel option disables all fbdev userspace interfaces. These are * the device files, such as /dev/fb0 * the sys files under /sys/class/graphics/fb[0-9]+ * /proc/fb * What are the effects on userspace programs? Userspace applications run on the desktop via Wayland or X. There will be no change to them. Xorg and Wayland compositors run on DRM interfaces. A few programs run on SDL, which has no dependency on fbdev either. Any fbdev support in these mid-layer components should be disabled as well. There's one known affected program: TW's text-mode installer can use the tool fbiterm to display CJK symbols during installation. This comes from a time when some low-end systems where not able to boot graphics installation. fbiterm has been unmaintained for >15 years and is ready for retirement. But there's no good drop-in replacement. I propose to simply remove fbiterm and let the graphics installer handle CJK. * What about the framebuffer console? The kernel-provided framebuffer console does not change. The kernel will still show the regular console. Userspace interfaces in /sys/class/graphics/fbcon are still available. For questions and discussion, please comment here or in boo#1212947. Best regards Thomas [1] https://elixir.bootlin.com/linux/v6.6-rc1/source/drivers/video/fbdev/core/K… [2] https://bugzilla.opensuse.org/show_bug.cgi?id=1212947 [3] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?… -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Frankenstrasse 146, 90461 Nuernberg, Germany GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman HRB 36809 (AG Nuernberg)

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No lockdown on Secure Boot with kernel:Stable?
by Andrei Borzenkov 17 Dec '24

17 Dec '24

On the very same system Tumbleweed kernel boots with lockdown enabled while kernel-default from kernel:Stable (currently 6.12.4) boots with lockdown disabled. I do not see any difference in options, LOCK_DOWN_IN_EFI_SECURE_BOOT is set in both cases. Is it intentional? What option controls it if not LOCK_DOWN_IN_EFI_SECURE_BOOT?

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Request For Insights On Kernel Security Hardening Practices In openSUSE
by Yinhao Hu 13 Dec '24

13 Dec '24

Dear All, We are academic researchers from Huazhong University of Science and Technology, China. To foster a healthier Linux kernel community and enhance the overall security of Linux distributions, we are conducting a study on kernel security hardening deployments across various Linux distributions. In our research, we analyzed kernel config files and the /proc filesystem by installing and running multiple distribution ISO images. This allowed us to enumerate the default deployment of kernel defense mechanisms at runtime. So far, we have cataloged over 50 kernel security hardening features and documented inconsistencies in their deployment across different distributions. The results of our analysis are accessible via the following link: https://docs.google.com/spreadsheets/d/17QRr04pqK1K4-VoHXW2-9KgPd4uV8Q4I-NN…. Given openSUSE's reputation for exceptional performance and rich features, we conducted a detailed investigation into its kernel security hardening strategies. To further deepen our understanding, we would greatly appreciate your input on the following questions: 1. Effectiveness of Kernel Security Hardening 1.1 Do you consider deploying kernel security hardening features to be an effective strategy for ensuring operating system security? 2. Configuration Strategy for Default Kernel Security Hardening Options 2.1 What are the primary criteria for selecting kernel security hardening options in your distribution? 2.2 How are configurable security hardening features (e.g., unprivileged_bpf_disabled) typically set (e.g., 0, 1, or 2), and what are the main considerations involved? 2.3 How do you balance the trade-off between side-effects (e.g., performance overhead) and the enhanced security introduced by kernel security hardening? 2.4 Does the tolerance for performance overhead vary across different application scenarios? 2.5 Are there other negative factors, such as compatibility issues, that are considered when enabling security hardening features? 3. Customized Configurations 3.1 Do you provide different kernel security hardening configurations tailored to specific user groups? 4. Best Practices and Recommendations 4.1 Are there any best practices or recommendations you can share regarding kernel security hardening? 4.2 Are there relevant documents or materials available for reference? The purpose of these questions is to gain a deeper understanding of your security protection strategies. Your insights would be immensely valuable to our study. Thank you for taking the time to review our questions. We look forward to your response. Best regards, Yinhao Hu, PhD candidate huyinhaodd(a)gmail.com Huazhong University of Science and Technology

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