linux-toradex.git/mm/maccess.c, branch v5.12

uaccess: add force_uaccess_{begin,end} helpers

2020-08-12T17:57:59+00:00

Add helpers to wrap the get_fs/set_fs magic for undoing any damange done
by set_fs(KERNEL_DS).  There is no real functional benefit, but this
documents the intent of these calls better, and will allow stubbing the
functions out easily for kernels builds that do not allow address space
overrides in the future.

[hch@lst.de: drop two incorrect hunks, fix a commit log typo]
  Link: http://lkml.kernel.org/r/20200714105505.935079-6-hch@lst.de

Signed-off-by: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Acked-by: Linus Torvalds 
Acked-by: Mark Rutland 
Acked-by: Greentime Hu 
Acked-by: Geert Uytterhoeven 
Cc: Nick Hu 
Cc: Vincent Chen 
Cc: Paul Walmsley 
Cc: Palmer Dabbelt 
Link: http://lkml.kernel.org/r/20200710135706.537715-6-hch@lst.de
Signed-off-by: Linus Torvalds

maccess: rename probe_user_{read,write} to copy_{from,to}_user_nofault

2020-06-17T17:57:41+00:00

Better describe what these functions do.

Suggested-by: Linus Torvalds 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Linus Torvalds

maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault

2020-06-17T17:57:41+00:00

Better describe what these functions do.

Suggested-by: Linus Torvalds 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Linus Torvalds

maccess: return -ERANGE when probe_kernel_read() fails

2020-06-09T16:39:16+00:00

Allow the callers to distinguish a real unmapped address vs a range
that can't be probed.

Suggested-by: Masami Hiramatsu 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Reviewed-by: Masami Hiramatsu 
Cc: Alexei Starovoitov 
Cc: Daniel Borkmann 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20200521152301.2587579-24-hch@lst.de
Signed-off-by: Linus Torvalds

maccess: allow architectures to provide kernel probing directly

2020-06-09T16:39:15+00:00

Provide alternative versions of probe_kernel_read, probe_kernel_write
and strncpy_from_kernel_unsafe that don't need set_fs magic, but instead
use arch hooks that are modelled after unsafe_{get,put}_user to access
kernel memory in an exception safe way.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Cc: Alexei Starovoitov 
Cc: Daniel Borkmann 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: Masami Hiramatsu 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20200521152301.2587579-19-hch@lst.de
Signed-off-by: Linus Torvalds

maccess: move user access routines together

2020-06-09T16:39:15+00:00

Move kernel access vs user access routines together to ease upcoming
ifdefs.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Cc: Alexei Starovoitov 
Cc: Daniel Borkmann 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: Masami Hiramatsu 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20200521152301.2587579-18-hch@lst.de
Signed-off-by: Linus Torvalds

maccess: always use strict semantics for probe_kernel_read

2020-06-09T16:39:15+00:00

Except for historical confusion in the kprobes/uprobes and bpf tracers,
which has been fixed now, there is no good reason to ever allow user
memory accesses from probe_kernel_read.  Switch probe_kernel_read to only
read from kernel memory.

[akpm@linux-foundation.org: update it for "mm, dump_page(): do not crash with invalid mapping pointer"]

Signed-off-by: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Cc: Alexei Starovoitov 
Cc: Daniel Borkmann 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: Masami Hiramatsu 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20200521152301.2587579-17-hch@lst.de
Signed-off-by: Linus Torvalds

maccess: remove strncpy_from_unsafe

2020-06-09T16:39:15+00:00

All users are gone now.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Cc: Alexei Starovoitov 
Cc: Daniel Borkmann 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: Masami Hiramatsu 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20200521152301.2587579-16-hch@lst.de
Signed-off-by: Linus Torvalds

maccess: unify the probe kernel arch hooks

2020-06-09T16:39:15+00:00

Currently architectures have to override every routine that probes
kernel memory, which includes a pure read and strcpy, both in strict
and not strict variants.  Just provide a single arch hooks instead to
make sure all architectures cover all the cases.

[akpm@linux-foundation.org: fix !CONFIG_X86_64 build]

Signed-off-by: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Cc: Alexei Starovoitov 
Cc: Daniel Borkmann 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: Masami Hiramatsu 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20200521152301.2587579-11-hch@lst.de
Signed-off-by: Linus Torvalds

maccess: remove probe_read_common and probe_write_common

2020-06-09T16:39:15+00:00

Each of the helpers has just two callers, which also different in
dealing with kernel or userspace pointers.  Just open code the logic
in the callers.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Cc: Alexei Starovoitov 
Cc: Daniel Borkmann 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: Masami Hiramatsu 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20200521152301.2587579-10-hch@lst.de
Signed-off-by: Linus Torvalds