linux-toradex.git/include/linux/uaccess.h, branch v6.4-rc1

mm: Introduce untagged_addr_remote()

2023-03-16T20:08:39+00:00

untagged_addr() removes tags/metadata from the address and brings it to
the canonical form. The helper is implemented on arm64 and sparc. Both of
them do untagging based on global rules.

However, Linear Address Masking (LAM) on x86 introduces per-process
settings for untagging. As a result, untagged_addr() is now only
suitable for untagging addresses for the current proccess.

The new helper untagged_addr_remote() has to be used when the address
targets remote process. It requires the mmap lock for target mm to be
taken.

Signed-off-by: Kirill A. Shutemov 
Signed-off-by: Dave Hansen 
Acked-by: Peter Zijlstra (Intel) 
Tested-by: Alexander Potapenko 
Link: https://lore.kernel.org/all/20230312112612.31869-6-kirill.shutemov%40linux.intel.com

uaccess: Add minimum bounds check on kernel buffer size

2023-02-08T23:26:58+00:00

While there is logic about the difference between ksize and usize,
copy_struct_from_user() didn't check the size of the destination buffer
(when it was known) against ksize. Add this check so there is an upper
bounds check on the possible memset() call, otherwise lower bounds
checks made by callers will trigger bounds warnings under -Warray-bounds.
Seen under GCC 13:

In function 'copy_struct_from_user',
    inlined from 'iommufd_fops_ioctl' at
../drivers/iommu/iommufd/main.c:333:8:
../include/linux/fortify-string.h:59:33: warning: '__builtin_memset' offset [57, 4294967294] is out of the bounds [0, 56] of object 'buf' with type 'union ucmd_buffer' [-Warray-bounds=]
   59 | #define __underlying_memset     __builtin_memset
      |                                 ^
../include/linux/fortify-string.h:453:9: note: in expansion of macro '__underlying_memset'
  453 |         __underlying_memset(p, c, __fortify_size); \
      |         ^~~~~~~~~~~~~~~~~~~
../include/linux/fortify-string.h:461:25: note: in expansion of macro '__fortify_memset_chk'
  461 | #define memset(p, c, s) __fortify_memset_chk(p, c, s, \
      |                         ^~~~~~~~~~~~~~~~~~~~
../include/linux/uaccess.h:334:17: note: in expansion of macro 'memset'
  334 |                 memset(dst + size, 0, rest);
      |                 ^~~~~~
../drivers/iommu/iommufd/main.c: In function 'iommufd_fops_ioctl':
../drivers/iommu/iommufd/main.c:311:27: note: 'buf' declared here
  311 |         union ucmd_buffer buf;
      |                           ^~~

Cc: Christian Brauner 
Cc: Rasmus Villemoes 
Cc: Arnd Bergmann 
Cc: Dinh Nguyen 
Cc: Catalin Marinas 
Cc: Andrew Morton 
Cc: Geert Uytterhoeven 
Cc: Alexander Potapenko 
Acked-by: Aleksa Sarai 
Signed-off-by: Kees Cook 
Link: https://lore.kernel.org/lkml/20230203193523.never.667-kees@kernel.org/

instrumented.h: allow instrumenting both sides of copy_from_user()

2022-10-03T21:03:18+00:00

Introduce instrument_copy_from_user_before() and
instrument_copy_from_user_after() hooks to be invoked before and after the
call to copy_from_user().

KASAN and KCSAN will be only using instrument_copy_from_user_before(), but
for KMSAN we'll need to insert code after copy_from_user().

Link: https://lkml.kernel.org/r/20220915150417.722975-4-glider@google.com
Signed-off-by: Alexander Potapenko 
Reviewed-by: Marco Elver 
Cc: Alexander Viro 
Cc: Alexei Starovoitov 
Cc: Andrey Konovalov 
Cc: Andrey Konovalov 
Cc: Andy Lutomirski 
Cc: Arnd Bergmann 
Cc: Borislav Petkov 
Cc: Christoph Hellwig 
Cc: Christoph Lameter 
Cc: David Rientjes 
Cc: Dmitry Vyukov 
Cc: Eric Biggers 
Cc: Eric Biggers 
Cc: Eric Dumazet 
Cc: Greg Kroah-Hartman 
Cc: Herbert Xu 
Cc: Ilya Leoshkevich 
Cc: Ingo Molnar 
Cc: Jens Axboe 
Cc: Joonsoo Kim 
Cc: Kees Cook 
Cc: Mark Rutland 
Cc: Matthew Wilcox 
Cc: Michael S. Tsirkin 
Cc: Pekka Enberg 
Cc: Peter Zijlstra 
Cc: Petr Mladek 
Cc: Stephen Rothwell 
Cc: Steven Rostedt 
Cc: Thomas Gleixner 
Cc: Vasily Gorbik 
Cc: Vegard Nossum 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton

No need of likely/unlikely on calls of check_copy_size()

2022-06-07T20:18:08+00:00

it's inline and unlikely() inside of it (including the implicit one
in WARN_ON_ONCE()) suffice to convince the compiler that getting
false from check_copy_size() is unlikely.

Spotted-by: Jens Axboe 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Christian Brauner (Microsoft) 
Signed-off-by: Al Viro

mm: Add fault_in_subpage_writeable() to probe at sub-page granularity

2022-04-25T09:25:43+00:00

On hardware with features like arm64 MTE or SPARC ADI, an access fault
can be triggered at sub-page granularity. Depending on how the
fault_in_writeable() function is used, the caller can get into a
live-lock by continuously retrying the fault-in on an address different
from the one where the uaccess failed.

In the majority of cases progress is ensured by the following
conditions:

1. copy_to_user_nofault() guarantees at least one byte access if the
   user address is not faulting.

2. The fault_in_writeable() loop is resumed from the first address that
   could not be accessed by copy_to_user_nofault().

If the loop iteration is restarted from an earlier (initial) point, the
loop is repeated with the same conditions and it would live-lock.

Introduce an arch-specific probe_subpage_writeable() and call it from
the newly added fault_in_subpage_writeable() function. The arch code
with sub-page faults will have to implement the specific probing
functionality.

Note that no other fault_in_subpage_*() functions are added since they
have no callers currently susceptible to a live-lock.

Signed-off-by: Catalin Marinas 
Cc: Andrew Morton 
Link: https://lore.kernel.org/r/20220423100751.1870771-2-catalin.marinas@arm.com
Signed-off-by: Catalin Marinas

Merge tag 'asm-generic-5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic

2022-03-24T01:03:08+00:00

Pull asm-generic updates from Arnd Bergmann:
 "There are three sets of updates for 5.18 in the asm-generic tree:

   - The set_fs()/get_fs() infrastructure gets removed for good.

     This was already gone from all major architectures, but now we can
     finally remove it everywhere, which loses some particularly tricky
     and error-prone code. There is a small merge conflict against a
     parisc cleanup, the solution is to use their new version.

   - The nds32 architecture ends its tenure in the Linux kernel.

     The hardware is still used and the code is in reasonable shape, but
     the mainline port is not actively maintained any more, as all
     remaining users are thought to run vendor kernels that would never
     be updated to a future release.

   - A series from Masahiro Yamada cleans up some of the uapi header
     files to pass the compile-time checks"

* tag 'asm-generic-5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic: (27 commits)
  nds32: Remove the architecture
  uaccess: remove CONFIG_SET_FS
  ia64: remove CONFIG_SET_FS support
  sh: remove CONFIG_SET_FS support
  sparc64: remove CONFIG_SET_FS support
  lib/test_lockup: fix kernel pointer check for separate address spaces
  uaccess: generalize access_ok()
  uaccess: fix type mismatch warnings from access_ok()
  arm64: simplify access_ok()
  m68k: fix access_ok for coldfire
  MIPS: use simpler access_ok()
  MIPS: Handle address errors for accesses above CPU max virtual user address
  uaccess: add generic __{get,put}_kernel_nofault
  nios2: drop access_ok() check from __put_user()
  x86: use more conventional access_ok() definition
  x86: remove __range_not_ok()
  sparc64: add __{get,put}_kernel_nofault()
  nds32: fix access_ok() checks in get/put_user
  uaccess: fix nios2 and microblaze get_user_8()
  sparc64: fix building assembly files
  ...

mm: remove usercopy_warn()

2022-03-22T22:57:11+00:00

Users of usercopy_warn() were removed by commit 53944f171a89 ("mm:
remove HARDENED_USERCOPY_FALLBACK")

Remove it.

Link: https://lkml.kernel.org/r/5f26643fc70b05f8455b60b99c30c17d635fa640.1644231910.git.christophe.leroy@csgroup.eu
Signed-off-by: Christophe Leroy 
Reviewed-by: Miaohe Lin 
Reviewed-by: Stephen Kitt 
Reviewed-by: Muchun Song 
Cc: Kees Cook 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

uaccess: remove CONFIG_SET_FS

2022-02-25T08:36:06+00:00

There are no remaining callers of set_fs(), so CONFIG_SET_FS
can be removed globally, along with the thread_info field and
any references to it.

This turns access_ok() into a cheaper check against TASK_SIZE_MAX.

As CONFIG_SET_FS is now gone, drop all remaining references to
set_fs()/get_fs(), mm_segment_t, user_addr_max() and uaccess_kernel().

Acked-by: Sam Ravnborg  # for sparc32 changes
Acked-by: "Eric W. Biederman" 
Tested-by: Sergey Matyukevich  # for arc changes
Acked-by: Stafford Horne  # [openrisc, asm-generic]
Acked-by: Dinh Nguyen 
Signed-off-by: Arnd Bergmann

uaccess: generalize access_ok()

2022-02-25T08:36:05+00:00

There are many different ways that access_ok() is defined across
architectures, but in the end, they all just compare against the
user_addr_max() value or they accept anything.

Provide one definition that works for most architectures, checking
against TASK_SIZE_MAX for user processes or skipping the check inside
of uaccess_kernel() sections.

For architectures without CONFIG_SET_FS(), this should be the fastest
check, as it comes down to a single comparison of a pointer against a
compile-time constant, while the architecture specific versions tend to
do something more complex for historic reasons or get something wrong.

Type checking for __user annotations is handled inconsistently across
architectures, but this is easily simplified as well by using an inline
function that takes a 'const void __user *' argument. A handful of
callers need an extra __user annotation for this.

Some architectures had trick to use 33-bit or 65-bit arithmetic on the
addresses to calculate the overflow, however this simpler version uses
fewer registers, which means it can produce better object code in the
end despite needing a second (statically predicted) branch.

Reviewed-by: Christoph Hellwig 
Acked-by: Mark Rutland  [arm64, asm-generic]
Acked-by: Geert Uytterhoeven 
Acked-by: Stafford Horne 
Acked-by: Dinh Nguyen 
Signed-off-by: Arnd Bergmann

uaccess: add generic __{get,put}_kernel_nofault

2022-02-25T08:36:05+00:00

Nine architectures are still missing __{get,put}_kernel_nofault:
alpha, ia64, microblaze, nds32, nios2, openrisc, sh, sparc32, xtensa.

Add a generic version that lets everything use the normal
copy_{from,to}_kernel_nofault() code based on these, removing the last
use of get_fs()/set_fs() from architecture-independent code.

Reviewed-by: Christoph Hellwig 
Acked-by: Geert Uytterhoeven 
Signed-off-by: Arnd Bergmann