linux-stable.git/mm/maccess.c, branch linux-4.9.y

uaccess: Add non-pagefault user-space write function

2020-09-12T09:47:35+00:00

[ Upstream commit 1d1585ca0f48fe7ed95c3571f3e4a82b2b5045dc ]

Commit 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions")
missed to add probe write function, therefore factor out a probe_write_common()
helper with most logic of probe_kernel_write() except setting KERNEL_DS, and
add a new probe_user_write() helper so it can be used from BPF side.

Again, on some archs, the user address space and kernel address space can
co-exist and be overlapping, so in such case, setting KERNEL_DS would mean
that the given address is treated as being in kernel address space.

Signed-off-by: Daniel Borkmann 
Signed-off-by: Alexei Starovoitov 
Acked-by: Andrii Nakryiko 
Cc: Masami Hiramatsu 
Link: https://lore.kernel.org/bpf/9df2542e68141bfa3addde631441ee45503856a8.1572649915.git.daniel@iogearbox.net
Signed-off-by: Sasha Levin

uaccess: Add non-pagefault user-space read functions

2020-09-12T09:47:35+00:00

[ Upstream commit 3d7081822f7f9eab867d9bcc8fd635208ec438e0 ]

Add probe_user_read(), strncpy_from_unsafe_user() and
strnlen_unsafe_user() which allows caller to access user-space
in IRQ context.

Current probe_kernel_read() and strncpy_from_unsafe() are
not available for user-space memory, because it sets
KERNEL_DS while accessing data. On some arch, user address
space and kernel address space can be co-exist, but others
can not. In that case, setting KERNEL_DS means given
address is treated as a kernel address space.
Also strnlen_user() is only available from user context since
it can sleep if pagefault is enabled.

To access user-space memory without pagefault, we need
these new functions which sets USER_DS while accessing
the data.

Link: http://lkml.kernel.org/r/155789869802.26965.4940338412595759063.stgit@devnote2

Acked-by: Ingo Molnar 
Signed-off-by: Masami Hiramatsu 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Sasha Levin

x86: remove more uaccess_32.h complexity

2016-05-23T00:21:27+00:00

I'm looking at trying to possibly merge the 32-bit and 64-bit versions
of the x86 uaccess.h implementation, but first this needs to be cleaned
up.

For example, the 32-bit version of "__copy_from_user_inatomic()" is
mostly the special cases for the constant size, and it's actually almost
never relevant.  Most users aren't actually using a constant size
anyway, and the few cases that do small constant copies are better off
just using __get_user() instead.

So get rid of the unnecessary complexity.

Signed-off-by: Linus Torvalds

mm/maccess.c: actually return -EFAULT from strncpy_from_unsafe

2015-11-06T03:34:48+00:00

As far as I can tell, strncpy_from_unsafe never returns -EFAULT.  ret is
the result of a __copy_from_user_inatomic(), which is 0 for success and
positive (in this case necessarily 1) for access error - it is never
negative.  So we were always returning the length of the, possibly
truncated, destination string.

Signed-off-by: Rasmus Villemoes 
Acked-by: Alexei Starovoitov 
Cc: Masami Hiramatsu 
Cc: Namhyung Kim 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

uaccess: reimplement probe_kernel_address() using probe_kernel_read()

2015-11-06T03:34:48+00:00

probe_kernel_address() is basically the same as the (later added)
probe_kernel_read().

The return value on EFAULT is a bit different: probe_kernel_address()
returns number-of-bytes-not-copied whereas probe_kernel_read() returns
-EFAULT.  All callers have been checked, none cared.

probe_kernel_read() can be overridden by the architecture whereas
probe_kernel_address() cannot.  parisc, blackfin and um do this, to insert
additional checking.  Hence this patch possibly fixes obscure bugs,
although there are only two probe_kernel_address() callsites outside
arch/.

My first attempt involved removing probe_kernel_address() entirely and
converting all callsites to use probe_kernel_read() directly, but that got
tiresome.

This patch shrinks mm/slab_common.o by 218 bytes.  For a single
probe_kernel_address() callsite.

Cc: Steven Miao 
Cc: Jeff Dike 
Cc: Richard Weinberger 
Cc: "James E.J. Bottomley" 
Cc: Helge Deller 
Cc: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

lib: move strncpy_from_unsafe() into mm/maccess.c

2015-08-31T19:36:10+00:00

To fix build errors:
kernel/built-in.o: In function `bpf_trace_printk':
bpf_trace.c:(.text+0x11a254): undefined reference to `strncpy_from_unsafe'
kernel/built-in.o: In function `fetch_memory_string':
trace_kprobe.c:(.text+0x11acf8): undefined reference to `strncpy_from_unsafe'

move strncpy_from_unsafe() next to probe_kernel_read/write()
which use the same memory access style.

Reported-by: Fengguang Wu 
Reported-by: Guenter Roeck 
Fixes: 1a6877b9c0c2 ("lib: introduce strncpy_from_unsafe()")
Signed-off-by: Alexei Starovoitov 
Signed-off-by: David S. Miller

mm: Map most files to use export.h instead of module.h

2011-10-31T13:20:12+00:00

The files changed within are only using the EXPORT_SYMBOL
macro variants.  They are not using core modular infrastructure
and hence don't need module.h but only the export.h header.

Signed-off-by: Paul Gortmaker

maccess,probe_kernel: Make write/read src const void *

2011-05-25T23:56:23+00:00

The functions probe_kernel_write() and probe_kernel_read() do not modify
the src pointer. Allow const pointers to be passed in without the need
of a typecast.

Acked-by: Mike Frysinger 
Acked-by: Heiko Carstens 
Acked-by: Martin Schwidefsky 
Signed-off-by: Steven Rostedt 
Link: http://lkml.kernel.org/r/1305824936.1465.4.camel@gandalf.stny.rr.com

MN10300: Save frame pointer in thread_info struct rather than global var

2010-10-27T16:29:01+00:00

Save the current exception frame pointer in the thread_info struct rather than
in a global variable as the latter makes SMP tricky, especially when preemption
is also enabled.

This also replaces __frame with current_frame() and rearranges header file
inclusions to make it all compile.

Signed-off-by: David Howells 
Acked-by: Akira Takeuchi

maccess,probe_kernel: Allow arch specific override probe_kernel_(read|write)

2010-01-07T17:58:36+00:00

Some archs such as blackfin, would like to have an arch specific
probe_kernel_read() and probe_kernel_write() implementation which can
fall back to the generic implementation if no special operations are
needed.

CC: Thomas Gleixner 
CC: Ingo Molnar 
Signed-off-by: Jason Wessel 
Signed-off-by: Mike Frysinger