When @size is 0, the desired behavior is to allow unlimited bytes to be
parsed. Currently, this relies on some intentional arithmetic overflow
where --size gives us SIZE_MAX when size is 0.

Explicitly spell out the desired behavior without relying on intentional
overflow/underflow.

Signed-off-by: Justin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20240808-b4-string_helpers_caa133-v1-1-686a455167c4@google.com
Signed-off-by: Kees Cook <kees@kernel.org>

The new flags parameter allows controlling
 - Whether or not the units suffix is separated by a space, for
   compatibility with sort -h
 - Whether or not to append a B suffix - we're not always printing
   bytes.

Co-developed-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Kent Overstreet <kent.overstreet@linux.dev>
Link: https://lore.kernel.org/r/20240229205345.93902-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Kees Cook <keescook@chromium.org>

Improve the reporting of buffer overflows under CONFIG_FORTIFY_SOURCE to
help accelerate debugging efforts. The calculations are all just sitting
in registers anyway, so pass them along to the function to be reported.

For example, before:

  detected buffer overflow in memcpy

and after:

  memcpy: detected buffer overflow: 4096 byte read of buffer size 1

Link: https://lore.kernel.org/r/20230407192717.636137-10-keescook@chromium.org
Signed-off-by: Kees Cook <keescook@chromium.org>

The standard C string APIs were not designed to have a failure mode;
they were expected to always succeed without memory safety issues.
Normally, CONFIG_FORTIFY_SOURCE will use fortify_panic() to stop
processing, as truncating a read or write may provide an even worse
system state. However, this creates a problem for testing under things
like KUnit, which needs a way to survive failures.

When building with CONFIG_KUNIT, provide a failure path for all users
of fortify_panic, and track whether the failure was a read overflow or
a write overflow, for KUnit tests to examine. Inspired by similar logic
in the slab tests.

Signed-off-by: Kees Cook <keescook@chromium.org>

In preparation for KUnit testing and further improvements in fortify
failure reporting, split out the report and encode the function and access
failure (read or write overflow) into a single u8 argument. This mainly
ends up saving a tiny bit of space in the data segment. For a defconfig
with FORTIFY_SOURCE enabled:

$ size gcc/vmlinux.before gcc/vmlinux.after
   text  	  data     bss     dec    	    hex filename
26132309        9760658 2195460 38088427        2452eeb gcc/vmlinux.before
26132386        9748382 2195460 38076228        244ff44 gcc/vmlinux.after

Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: Kees Cook <keescook@chromium.org>

In preparation for making strscpy_pad()'s 3rd argument optional, redefine
it as a macro. This also has the benefit of allowing greater FORITFY
introspection, as it couldn't see into the strscpy() nor the memset()
within strscpy_pad().

Cc: Andy Shevchenko <andy@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc:  <linux-hardening@vger.kernel.org>
Reviewed-by: Justin Stitt <justinstitt@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>

printbuf now needs to know the number of characters that would have been
written if the buffer was too small, like snprintf(); this changes
string_get_size() to return the the return value of snprintf().

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Duplicate a NULL-terminated string and replace all occurrences of
the old character with a new one. In other words, provide functionality
of kstrdup() + strreplace().

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230804143910.15504-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

It's more useful to return the pointer to the string itself
with strreplace(), so it may be used like

	attr->name = strreplace(name, '/', '_');

While at it, amend the kernel documentation.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230605170553.7835-3-andriy.shevchenko@linux.intel.com

Add new helper function to allow for splitting specified user string
into a sequence of integers. Internally it makes use of get_options() so
the returned sequence contains the integers extracted plus an additional
element that begins the sequence and specifies the integers count.

Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Cezary Rojewski <cezary.rojewski@intel.com>
Link: https://lore.kernel.org/r/20220904102840.862395-2-cezary.rojewski@intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>