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[v2,0/8] SECCOMP based userspace for UML

Message ID 20250430160413.3250227-1-benjamin@sipsolutions.net
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Series SECCOMP based userspace for UML | expand

Message

Benjamin Berg April 30, 2025, 4:04 p.m. UTC 
From: Benjamin Berg <benjamin.berg@intel.com>

Hi all,

another version of the SECCOMP patchset. I think that this should now be
good enough for general consumption. Compared to the last RFC version
there is an important bugfix that caused a SIGSEGV loop and various
other small bugfixes and cleanups.

The patchset adds a new userspace handling mode to UML that is based on
a SECCOMP filter and trusted code within each userspace process.

The motivation the new SECCOMP mode is that it saves context switches
when handling pagefaults and for syscalls like mmap. The approach may
also permit SMP support in the future and might make it easier to port
UML to further host architectures.

Benjamin

v2:
- Simple rebase dropping the merged patche

v1:
- Remove explicit (and insufficient) kconfig.h includes
- Change commit order to move configuration to the end
- Fix futex wait race condition
- Also handle child dying during stub startup

RFCv2:
- Fix FP handling on i386
- Improved MM list for userspace sigchild handling
- Remove kconfig.h includes
- Minor cleanups

Benjamin Berg (8):
  um: Move faultinfo extraction into userspace routine
  um: Add stub side of SECCOMP/futex based process handling
  um: Add helper functions to get/set state for SECCOMP
  um: Add SECCOMP support detection and initialization
  um: Track userspace children dying in SECCOMP mode
  um: Implement kernel side of SECCOMP based process handling
  um: pass FD for memory operations when needed
  um: Add UML_SECCOMP configuration option

 arch/um/Kconfig                            |  19 +
 arch/um/include/asm/irq.h                  |   5 +-
 arch/um/include/asm/mmu.h                  |   3 +
 arch/um/include/shared/common-offsets.h    |   4 +
 arch/um/include/shared/irq_user.h          |   2 +
 arch/um/include/shared/os.h                |   3 +-
 arch/um/include/shared/skas/mm_id.h        |  13 +
 arch/um/include/shared/skas/skas.h         |   5 +
 arch/um/include/shared/skas/stub-data.h    |  20 +-
 arch/um/kernel/irq.c                       |   6 +
 arch/um/kernel/skas/mmu.c                  |  89 +++-
 arch/um/kernel/skas/stub.c                 | 134 +++++-
 arch/um/kernel/skas/stub_exe.c             | 159 ++++++-
 arch/um/os-Linux/internal.h                |   5 +-
 arch/um/os-Linux/process.c                 |  31 ++
 arch/um/os-Linux/registers.c               |   4 +-
 arch/um/os-Linux/signal.c                  |  19 +-
 arch/um/os-Linux/skas/mem.c                | 103 ++++-
 arch/um/os-Linux/skas/process.c            | 485 +++++++++++++++------
 arch/um/os-Linux/start_up.c                | 150 ++++++-
 arch/x86/um/os-Linux/mcontext.c            | 220 +++++++++-
 arch/x86/um/ptrace.c                       |  76 +++-
 arch/x86/um/shared/sysdep/kernel-offsets.h |   2 +
 arch/x86/um/shared/sysdep/mcontext.h       |   9 +
 arch/x86/um/shared/sysdep/stub-data.h      |  23 +
 arch/x86/um/shared/sysdep/stub.h           |   2 +
 arch/x86/um/shared/sysdep/stub_32.h        |  13 +
 arch/x86/um/shared/sysdep/stub_64.h        |  17 +
 arch/x86/um/tls_32.c                       |  23 +-
 29 files changed, 1439 insertions(+), 205 deletions(-)
 create mode 100644 arch/x86/um/shared/sysdep/stub-data.h