When copying FDs, the copy size should not include the control
message header (cmsghdr). Fix it.

Fixes: 5cde6096a4dd ("um: generalize os_rcv_fd")
Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

When register_virtio_device() fails in virtio_uml_probe(),
the code sets vu_dev->registered = 1 even though
the device was not successfully registered.
This can lead to use-after-free or other issues.

Fixes: 04e5b1fb0183 ("um: virtio: Remove device on disconnect")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

On one of my machines UML failed to start after enabling
SELinux.
UML failed to start because SELinux's execmod rule denies
executable pages on a modified file mapping.

Historically UML marks it's stack rwx.
AFAICT, these days this is no longer needed, so let's remove
PROT_EXEC.

Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Pull uml updates from Johannes Berg:
 "Mostly cleanups, except:

   - dynamic addition of vfio passthrough devices

   - implementation of HAVE_SYSCALL_TRACEPOINTS"

* tag 'uml-for-linux-6.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux:
  um: Replace __ASSEMBLY__ with __ASSEMBLER__ in the usermode headers
  um: Stop tracking stub's PID via userspace_pid[]
  um: Remove the pid parameter of handle_trap()
  um: Use err consistently in userspace()
  um: vfio: Support adding devices via mconsole
  um: rtc: Avoid shadowing err in uml_rtc_start()
  um: Avoid redefining ARCH_HAS_CACHE_LINE_SIZE
  um: Make mm_list and mm_list_lock static
  um: Make unscheduled_userspace_iterations static
  um: Re-evaluate thread flags repeatedly
  um: simplify syscall header files
  um/ptrace: Implement HAVE_SYSCALL_TRACEPOINTS
  um/x86: Add system call table to header file
  um: virt-pci: Switch to msi_create_parent_irq_domain()
  um: virtio_pcidev: Rename UM_PCI_STAT_WAITING

Pull asm/param cleanup from Al Viro:
 "This massages asm/param.h to simpler and more uniform shape:

   - all arch/*/include/uapi/asm/param.h are either generated includes
     of <asm-generic/param.h> or a #define or two followed by such
     include

   - no arch/*/include/asm/param.h anywhere, generated or not

   - include <asm/param.h> resolves to arch/*/include/uapi/asm/param.h
     of the architecture in question (or that of host in case of uml)

   - include/asm-generic/param.h pulls uapi/asm-generic/param.h and
     deals with USER_HZ, CLOCKS_PER_SEC and with HZ redefinition after
     that"

* tag 'pull-headers_param' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  loongarch, um, xtensa: get rid of generated arch/$ARCH/include/asm/param.h
  alpha: regularize the situation with asm/param.h
  xtensa: get rid uapi/asm/param.h

While the GCC and Clang compilers already define __ASSEMBLER__
automatically when compiling assembly code, __ASSEMBLY__ is a
macro that only gets defined by the Makefiles in the kernel.
This can be very confusing when switching between userspace
and kernelspace coding, so let's standardize on the __ASSEMBLER__
macro that is provided by the compilers now.

This is a completely mechanical patch (done with a simple "sed -i"
statement).

Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: linux-um@lists.infradead.org
Signed-off-by: Thomas Huth <thuth@redhat.com>
Link: https://patch.msgid.link/20250314071013.1575167-36-thuth@redhat.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

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 <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20250711065021.2535362-4-tiwei.bie@linux.dev
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

It's no longer used. Remove it.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20250711065021.2535362-3-tiwei.bie@linux.dev
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Avoid declaring a new variable 'ret' inside the 'if (using_seccomp)'
block, as the existing 'err' variable declared at the top of the
function already serves the same purpose.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20250711065021.2535362-2-tiwei.bie@linux.dev
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

It can be used when we want to pass through PCI devices to UML
while it's up and running. PCI devices can be passed through to
UML using the same syntax as the command line option:

(mconsole) config vfio_uml.device=<domain:bus:slot.function>

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20250709010021.1076902-1-tiwei.bie@linux.dev
Signed-off-by: Johannes Berg <johannes.berg@intel.com>