linux.git/arch/um/include/shared, branch v6.8

um: Remove unused register save/restore functions

2024-01-05T15:28:57+00:00

These functions were only used when calling PTRACE_ARCH_PRCTL, but this
code has been removed.

Signed-off-by: Benjamin Berg 
Signed-off-by: Richard Weinberger

um: Rely on PTRACE_SETREGSET to set FS/GS base registers

2024-01-05T15:28:56+00:00

These registers are saved/restored together with the other general
registers using ptrace. In arch_set_tls we then just need to set the
register and it will be synced back normally.

Most of this logic was introduced in commit f355559cf7845 ("[PATCH] uml:
x86_64 thread fixes"). However, at least today we can rely on ptrace to
restore the base registers for us. As such, only the part of the patch
that tracks the FS register for use as thread local storage is actually
needed.

Signed-off-by: Benjamin Berg 
Signed-off-by: Richard Weinberger

um: Drop support for hosts without SYSEMU_SINGLESTEP support

2024-01-04T22:29:11+00:00

These features have existed since Linux 2.6.14 and can be considered
widely available at this point. Also drop the backward compatibility
code for PTRACE_SETOPTIONS.

Signed-off-by: Benjamin Berg 

----

v2:
 * Continue to define PTRACE_SYSEMU_SINGLESTEP as glibc only added it in
   version 2.27.
Signed-off-by: Richard Weinberger

um: Fix naming clash between UML and scheduler

2024-01-04T20:22:27+00:00

__cant_sleep was already used and exported by the scheduler.
The name had to be changed to a UML specific one.

Signed-off-by: Anton Ivanov 
Reviewed-by: Peter Lafreniere 
Signed-off-by: Richard Weinberger

um: fix 3 instances of -Wmissing-prototypes

2023-08-26T20:45:05+00:00

Fixes the following build errors observed from W=1 builds:
  arch/um/drivers/xterm_kern.c:35:5: warning: no previous prototype for
  function 'xterm_fd' [-Wmissing-prototypes]
  35 | int xterm_fd(int socket, int *pid_out)
     |     ^
  arch/um/drivers/xterm_kern.c:35:1: note: declare 'static' if the
  function is not intended to be used outside of this translation unit
  35 | int xterm_fd(int socket, int *pid_out)
     | ^
     | static
  arch/um/drivers/chan_kern.c:183:6: warning: no previous prototype for
  function 'free_irqs' [-Wmissing-prototypes]
  183 | void free_irqs(void)
      |      ^
  arch/um/drivers/chan_kern.c:183:1: note: declare 'static' if the
  function is not intended to be used outside of this translation unit
  183 | void free_irqs(void)
      | ^
      | static
  arch/um/drivers/slirp_kern.c:18:6: warning: no previous prototype for
  function 'slirp_init' [-Wmissing-prototypes]
  18 | void slirp_init(struct net_device *dev, void *data)
     |      ^
  arch/um/drivers/slirp_kern.c:18:1: note: declare 'static' if the
  function is not intended to be used outside of this translation unit
  18 | void slirp_init(struct net_device *dev, void *data)
     | ^
     | static

Reported-by: kernel test robot 
Closes: https://lore.kernel.org/oe-kbuild-all/202308081050.sZEw4cQ5-lkp@intel.com/
Signed-off-by: Nick Desaulniers 
Signed-off-by: Richard Weinberger

um: Remove strlcpy usage

2023-08-19T20:24:39+00:00

strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with strscpy().
No return values were used, so direct replacement is safe.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89

Signed-off-by: Azeem Shaikh 
[rw: Massaged subject]
Signed-off-by: Richard Weinberger

uml: Replace strlcpy with strscpy

2023-06-20T20:35:37+00:00

strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with strscpy().
No return values were used, so direct replacement is safe.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89

Signed-off-by: Azeem Shaikh 
Signed-off-by: Kees Cook 
Link: https://lore.kernel.org/r/20230614003604.1021205-1-azeemshaikh38@gmail.com

um: make stub data pages size tweakable

2023-04-20T21:08:43+00:00

There's a lot of code here that hard-codes that the
data is a single page, and right now that seems to
be sufficient, but to make it easier to change this
in the future, add a new STUB_DATA_PAGES constant
and use it throughout the code.

Signed-off-by: Johannes Berg 
Signed-off-by: Richard Weinberger

Merge tag 'for-linus-5.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml

2022-08-05T21:03:11+00:00

Pull UML updates from Richard Weinberger:

 - KASAN support for x86_64

 - noreboot command line option, just like qemu's -no-reboot

 - Various fixes and cleanups

* tag 'for-linus-5.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml:
  um: include sys/types.h for size_t
  um: Replace to_phys() and to_virt() with less generic function names
  um: Add missing apply_returns()
  um: add "noreboot" command line option for PANIC_TIMEOUT=-1 setups
  um: include linux/stddef.h for __always_inline
  UML: add support for KASAN under x86_64
  mm: Add PAGE_ALIGN_DOWN macro
  um: random: Don't initialise hwrng struct with zero
  um: remove unused mm_copy_segments
  um: remove unused variable
  um: Remove straying parenthesis
  um: x86: print RIP with symbol
  arch: um: Fix build for statically linked UML w/ constructors
  x86/um: Kconfig: Fix indentation
  um/drivers: Kconfig: Fix indentation
  um: Kconfig: Fix indentation

um: seed rng using host OS rng

2022-07-18T13:04:04+00:00

UML generally does not provide access to special CPU instructions like
RDRAND, and execution tends to be rather deterministic, with no real
hardware interrupts, making good randomness really very hard, if not
all together impossible. Not only is this a security eyebrow raiser, but
it's also quite annoying when trying to do various pieces of UML-based
automation that takes a long time to boot, if ever.

Fix this by trivially calling getrandom() in the host and using that
seed as "bootloader randomness", which initializes the rng immediately
at UML boot.

The old behavior can be restored the same way as on any other arch, by
way of CONFIG_TRUST_BOOTLOADER_RANDOMNESS=n or
random.trust_bootloader=0. So seen from that perspective, this just
makes UML act like other archs, which is positive in its own right.

Additionally, wire up arch_get_random_{int,long}() in the same way, so
that reseeds can also make use of the host RNG, controllable by
CONFIG_TRUST_CPU_RANDOMNESS and random.trust_cpu, per usual.

Cc: stable@vger.kernel.org
Acked-by: Johannes Berg 
Acked-By: Anton Ivanov 
Signed-off-by: Jason A. Donenfeld