linux.git/arch/um/kernel, branch v6.17

um: Stop tracking stub's PID via userspace_pid[]

2025-07-13T17:42:49+00:00

The PID of the stub process can be obtained from current_mm_id().
There is no need to track it via userspace_pid[]. Stop doing that
to simplify the code.

Signed-off-by: Tiwei Bie 
Link: https://patch.msgid.link/20250711065021.2535362-4-tiwei.bie@linux.dev
Signed-off-by: Johannes Berg

um: Make mm_list and mm_list_lock static

2025-07-11T06:49:18+00:00

They are only used within mmu.c. Make them static.

Signed-off-by: Tiwei Bie 
Link: https://patch.msgid.link/20250708090403.1067440-3-tiwei.bie@linux.dev
Signed-off-by: Johannes Berg

um: Re-evaluate thread flags repeatedly

2025-07-11T06:49:02+00:00

The thread flags may change during their processing.
For example a task_work can queue a new signal to be sent.
This signal should be delivered before returning to usespace again.

Evaluate the flags repeatedly similar to other architectures.

Signed-off-by: Thomas Weißschuh 
Reviewed-by: Nam Cao 
Link: https://patch.msgid.link/20250704-uml-thread_flags-v1-1-0e293fd8d627@linutronix.de
Signed-off-by: Johannes Berg

um: simplify syscall header files

2025-07-11T06:49:02+00:00

Since Thomas's recent commit 2af10530639b ("um/x86: Add
system call table to header file") , we now have two
extern declarations of the syscall table, one internal
and one external, and they don't even match on 32-bit.
Clean this up and remove all the extra code.

Reviewed-by: Thomas Weißschuh 
Link: https://patch.msgid.link/20250704141243.a68366f6acc3.If8587a4aafdb90644fc6d0b2f5e31a2d1887915f@changeid
Signed-off-by: Johannes Berg

um/ptrace: Implement HAVE_SYSCALL_TRACEPOINTS

2025-07-11T06:49:02+00:00

Implement syscall tracepoints through the generic tracing infrastructure.

Signed-off-by: Thomas Weißschuh 
Reviewed-by: Nam Cao 
Link: https://patch.msgid.link/20250703-uml-have_syscall_tracepoints-v1-2-23c1d3808578@linutronix.de
Signed-off-by: Johannes Berg

Merge tag 'kbuild-v6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2025-06-07T17:05:35+00:00

Pull Kbuild updates from Masahiro Yamada:

 - Add support for the EXPORT_SYMBOL_GPL_FOR_MODULES() macro, which
   exports a symbol only to specified modules

 - Improve ABI handling in gendwarfksyms

 - Forcibly link lib-y objects to vmlinux even if CONFIG_MODULES=n

 - Add checkers for redundant or missing  inclusion

 - Deprecate the extra-y syntax

 - Fix a genksyms bug when including enum constants from *.symref files

* tag 'kbuild-v6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (28 commits)
  genksyms: Fix enum consts from a reference affecting new values
  arch: use always-$(KBUILD_BUILTIN) for vmlinux.lds
  kbuild: set y instead of 1 to KBUILD_{BUILTIN,MODULES}
  efi/libstub: use 'targets' instead of extra-y in Makefile
  module: make __mod_device_table__* symbols static
  scripts/misc-check: check unnecessary #include  when W=1
  scripts/misc-check: check missing #include  when W=1
  scripts/misc-check: add double-quotes to satisfy shellcheck
  kbuild: move W=1 check for scripts/misc-check to top-level Makefile
  scripts/tags.sh: allow to use alternative ctags implementation
  kconfig: introduce menu type enum
  docs: symbol-namespaces: fix reST warning with literal block
  kbuild: link lib-y objects to vmlinux forcibly even when CONFIG_MODULES=n
  tinyconfig: enable CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
  docs/core-api/symbol-namespaces: drop table of contents and section numbering
  modpost: check forbidden MODULE_IMPORT_NS("module:") at compile time
  kbuild: move kbuild syntax processing to scripts/Makefile.build
  Makefile: remove dependency on archscripts for header installation
  Documentation/kbuild: Add new gendwarfksyms kABI rules
  Documentation/kbuild: Drop section numbers
  ...

arch: use always-$(KBUILD_BUILTIN) for vmlinux.lds

2025-06-07T05:38:07+00:00

The extra-y syntax is deprecated. Instead, use always-$(KBUILD_BUILTIN),
which behaves equivalently.

Signed-off-by: Masahiro Yamada 
Acked-by: Johannes Berg 
Reviewed-by: Nicolas Schier

Merge tag 'uml-for-linux-6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux

2025-06-05T18:45:33+00:00

Pull UML updates from Johannes Berg:
 "The only really new thing is the long-standing seccomp work
  (originally from 2021!). Wven if it still isn't enabled by default due
  to security concerns it can still be used e.g. for tests.

   - remove obsolete network transports

   - remove PCI IO port support

   - start adding seccomp-based process handling instead of ptrace"

* tag 'uml-for-linux-6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux: (29 commits)
  um: remove "extern" from implementation of sigchld_handler
  um: fix unused variable warning
  um: fix SECCOMP 32bit xstate register restore
  um: pass FD for memory operations when needed
  um: Add SECCOMP support detection and initialization
  um: Implement kernel side of SECCOMP based process handling
  um: Track userspace children dying in SECCOMP mode
  um: Add helper functions to get/set state for SECCOMP
  um: Add stub side of SECCOMP/futex based process handling
  um: Move faultinfo extraction into userspace routine
  um: vector: Use mac_pton() for MAC address parsing
  um: vector: Clean up and modernize log messages
  um: chan_kern: use raw spinlock for irqs_to_free_lock
  MAINTAINERS: remove obsolete file entry in TUN/TAP DRIVER
  um: Fix tgkill compile error on old host OSes
  um: stop using PCI port I/O
  um: Remove legacy network transport infrastructure
  um: vector: Eliminate the dependency on uml_net
  um: Remove obsolete legacy network transports
  um/asm: Replace "REP; NOP" with PAUSE mnemonic
  ...

um: remove "extern" from implementation of sigchld_handler

2025-06-05T09:12:13+00:00

There is no need to mark the function as extern in the implementation.

Reported-by: kernel test robot 
Closes: https://lore.kernel.org/oe-kbuild-all/202506051226.X8r7X5aa-lkp@intel.com/
Fixes: 8420e08fe3a5 ("um: Track userspace children dying in SECCOMP mode")
Signed-off-by: Benjamin Berg 
Link: https://patch.msgid.link/20250605050325.1077208-2-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg

um: pass FD for memory operations when needed

2025-06-02T14:20:10+00:00

Instead of always sharing the FDs with the userspace process, only hand
over the FDs needed for mmap when required. The idea is that userspace
might be able to force the stub into executing an mmap syscall, however,
it will not be able to manipulate the control flow sufficiently to have
access to an FD that would allow mapping arbitrary memory.

Security wise, we need to be sure that only the expected syscalls are
executed after the kernel sends FDs through the socket. This is
currently not the case, as userspace can trivially jump to the
rt_sigreturn syscall instruction to execute any syscall that the stub is
permitted to do. With this, it can trick the kernel to send the FD,
which in turn allows userspace to freely map any physical memory.

As such, this is currently *not* secure. However, in principle the
approach should be fine with a more strict SECCOMP filter and a careful
review of the stub control flow (as userspace can prepare a stack). With
some care, it is likely possible to extend the security model to SMP if
desired.

Signed-off-by: Benjamin Berg 
Link: https://patch.msgid.link/20250602130052.545733-8-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg