Modularization and Modernization of cifs.ko for Enhanced SMB Protocol Support by hcarvalho

Creator:
Enzo Matsumiya ematsumiya@suse.de @ SUSE Samba team
Members:
Henrique Carvalho henrique.carvalho@suse.com @ SUSE Samba team

Description

Split cifs.ko in 2 separate modules; one for SMB 1.0 and 2.0.x, and another for SMB 2.1, 3.0, and 3.1.1.

Goals

Primary

Start phasing out/deprecation of older SMB versions

Secondary

• Clean up of the code (with focus on the newer versions)
• Update cifs-utils
• Update documentation
• Improve backport workflow (see below)

Technical details

Ideas for the implementation.

• fs/smb/client/{old,new}.c to generate the respective modules
  • Maybe don't create separate folders? (re-evaluate as things progresses!)
• Remove server->{ops,vals} if possible
• Clean up fs_context.* -- merge duplicate options into one, handle them in userspace utils
• Reduce code in smb2pdu.c -- tons of functions with very similar init/setup -> send/recv -> handle/free flow
• Restructure multichannel
  • Treat initial connection as "channel 0" regardless of multichannel enabled/negotiated status, proceed with extra channels accordingly
  • Extra channel just point to "channel 0" as the primary server, no need to allocate an extra TCPServerInfo for each one
• Authentication mechanisms
  • Modernize algorithms (references: himmelblau, IAKERB/Local KDC, SCRAM, oauth2 (Azure), etc.

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Officially Become a Kernel Hacker! by m.crivellari

Description

My studies as well my spare time are dedicated to the Linux Kernel. Currently I'm focusing on interrupts on x86_64, but my interests are not restricted to one specific topic, for now.

I also "played" a little bit with kernel modules (ie lantern, a toy packet analyzer) and I've added a new syscall in order read from a task A, the memory of a task B.

Maybe this will be a good chance to...

Goals

• create my first kernel patch

Resources

• https://www.kernel.org/doc/html/latest/process/submitting-patches.html
• https://git-send-email.io/ (mentioned also in the kernel doc)
• https://javiercarrascocruz.github.io/kernel-contributor-1

Achivements

• found while working on a bug, this is the 1st patch: cifs: avoid deadlocks while updating iface [✅ has been merged]

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Modernize ocfs2 by goldwynr

Ocfs2 has gone into a stage of neglect and disrepair. Modernize the code to generate enough interest.

Goals: * Change the mount sequence to use fscontext * Move from using bufferhead to bio/folios * Use iomap * Run it through xfstests

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early stage kdump support by mbrugger

Project Description

When we experience a early boot crash, we are not able to analyze the kernel dump, as user-space wasn't able to load the crash system. The idea is to make the crash system compiled into the host kernel (think of initramfs) so that we can create a kernel dump really early in the boot process.

Goal for the Hackweeks

1. Investigate if this is possible and the implications it would have (done in HW21)
2. Hack up a PoC (done in HW22 and HW23)
3. Prepare RFC series (giving it's only one week, we are entering wishful thinking territory here).

update HW23

• I was able to include the crash kernel into the kernel Image.
• I'll need to find a way to load that from init/main.c:start_kernel() probably after kcsan_init()
• I workaround for a smoke test was to hack kexec_file_load() systemcall which has two problems:
  1. My initramfs in the porduction kernel does not have a new enough kexec version, that's not a blocker but where the week ended
  2. As the crash kernel is part of init.data it will be already stale once I can call kexec_file_load() from user-space.

The solution is probably to rewrite the POC so that the invocation can be done from init.text (that's my theory) but I'm not sure if I can reuse the kexec infrastructure in the kernel from there, which I rely on heavily.

update HW24

• Day1
  • rebased on v6.12 with no problems others then me breaking the config
  • setting up a new compilation and qemu/virtme env
  • getting desperate as nothing works that used to work
• Day 2
  • getting to call the invocation of loading the early kernel from __init after kcsan_init()

• Day 3

  • fix problem of memdup not being able to alloc so much memory... use 64K page sizes for now
  • code refactoring
  • I'm now able to load the crash kernel
  • When using virtme I can boot into the crash kernel, also it doesn't boot completely (major milestone!), crash in elfcorehdr_read_notes()

• Day 4

  • crash systems crashes (no pun intended) in copy_old_mempage() link; will need to understand elfcorehdr...
  • call path vmcore_init() -> parse_crash_elf_headers() -> elfcorehdr_read() -> read_from_oldmem() -> copy_oldmem_page() -> copy_to_iter()

• Day 5

  • hacking arch/arm64/kernel/crash_dump.c:copy_old_mempage() to see if crash system really starts. It does.
  • fun fact: retested with more reserved memory and with UEFI FW, host kernel crashes in init but directly starts the crash kernel, so it works (somehow) \o/

• TODOs

  • fix elfcorehdr so that we actually can make use of all this...
  • test where in the boot __init() chain we can/should call kexec_early_dump()

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Kill DMA and DMA32 memory zones by ptesarik

Description

Provide a better allocator for DMA-capable buffers, making the DMA and DMA32 zones obsolete.

Goals

Make a PoC kernel which can boot a x86 VM and a Raspberry Pi (because early RPi4 boards have some of the weirdest DMA constraints).

Resources

• LPC2024 talk:
• video:

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