The point behind strscpy() was to once and for all avoid all the
problems with 'strncpy()' and later broken "fixed" versions like
strlcpy() that just made things worse.
So strscpy not only guarantees NUL-termination (unlike strncpy), it also
doesn't do unnecessary padding at the destination. But at the same time
also avoids byte-at-a-time reads and writes by _allowing_ some extra NUL
writes - within the size, of course - so that the whole copy can be done
with word operations.
It is also stable in the face of a mutable source string: it explicitly
does not read the source buffer multiple times (so an implementation
using "strnlen()+memcpy()" would be wrong), and does not read the source
buffer past the size (like the mis-design that is strlcpy does).
Finally, the return value is designed to be simple and unambiguous: if
the string cannot be copied fully, it returns an actual negative error,
making error handling clearer and simpler (and the caller already knows
the size of the buffer). Otherwise it returns the string length of the
result.
However, there was one final stability issue that can be important to
callers: the stability of the destination buffer.
In particular, the same way we shouldn't read the source buffer more
than once, we should avoid doing multiple writes to the destination
buffer: first writing a potentially non-terminated string, and then
terminating it with NUL at the end does not result in a stable result
buffer.
Yes, it gives the right result in the end, but if the rule for the
destination buffer was that it is _always_ NUL-terminated even when
accessed concurrently with updates, the final byte of the buffer needs
to always _stay_ as a NUL byte.
[ Note that "final byte is NUL" here is literally about the final byte
in the destination array, not the terminating NUL at the end of the
string itself. There is no attempt to try to make concurrent reads and
writes give any kind of consistent string length or contents, but we
do want to guarantee that there is always at least that final
terminating NUL character at the end of the destination array if it
existed before ]
This is relevant in the kernel for the tsk->comm[] array, for example.
Even without locking (for either readers or writers), we want to know
that while the buffer contents may be garbled, it is always a valid C
string and always has a NUL character at 'comm[TASK_COMM_LEN-1]' (and
never has any "out of thin air" data).
So avoid any "copy possibly non-terminated string, and terminate later"
behavior, and write the destination buffer only once.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
asm/unaligned.h is always an include of asm-generic/unaligned.h;
might as well move that thing to linux/unaligned.h and include
that - there's nothing arch-specific in that header.
auto-generated by the following:
for i in `git grep -l -w asm/unaligned.h`; do
sed -i -e "s/asm\/unaligned.h/linux\/unaligned.h/" $i
done
for i in `git grep -l -w asm-generic/unaligned.h`; do
sed -i -e "s/asm-generic\/unaligned.h/linux\/unaligned.h/" $i
done
git mv include/asm-generic/unaligned.h include/linux/unaligned.h
git mv tools/include/asm-generic/unaligned.h tools/include/linux/unaligned.h
sed -i -e "/unaligned.h/d" include/asm-generic/Kbuild
sed -i -e "s/__ASM_GENERIC/__LINUX/" include/linux/unaligned.h tools/include/linux/unaligned.h
Using sizeof(dst) for the "size" argument in strscpy() is the
overwhelmingly common case. Instead of requiring this everywhere, allow a
2-argument version to be used that will use the sizeof() internally. There
are other functions in the kernel with optional arguments[1], so this
isn't unprecedented, and improves readability. Update and relocate the
kern-doc for strscpy() too, and drop __HAVE_ARCH_STRSCPY as it is unused.
Adjust ARCH=um build to notice the changed export name, as it doesn't
do full header includes for the string helpers.
This could additionally let us save a few hundred lines of code:
1177 files changed, 2455 insertions(+), 3026 deletions(-)
with a treewide cleanup using Coccinelle:
@needless_arg@
expression DST, SRC;
@@
strscpy(DST, SRC
-, sizeof(DST)
)
Link: https://elixir.bootlin.com/linux/v6.7/source/include/linux/pci.h#L1517 [1]
Reviewed-by: Justin Stitt <justinstitt@google.com>
Cc: Andy Shevchenko <andy@kernel.org>
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
This diff uses an open source tool include-what-you-use (IWYU) to modify
the include list, changing indirect includes to direct includes. IWYU is
implemented using the IWYUScripts github repository which is a tool that
is currently undergoing development. These changes seek to improve build
times.
This change to lib/string.c resulted in a preprocessed size of
lib/string.i from 26371 lines to 5321 lines (-80%) for the x86
defconfig.
Link: https://github.com/ClangBuiltLinux/IWYUScripts
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Tanzir Hasan <tanzirh@google.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20231226-libstringheader-v6-2-80aa08c7652c@google.com
Signed-off-by: Kees Cook <keescook@chromium.org>
With all the users of strlcpy() removed[1] from the kernel, remove the
API, self-tests, and other references. Leave mentions in Documentation
(about its deprecation), and in checkpatch.pl (to help migrate host-only
tools/ usage). Long live strscpy().
Link: https://github.com/KSPP/linux/issues/89 [1]
Cc: Azeem Shaikh <azeemshaikh38@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Joe Perches <joe@perches.com>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc: linux-hardening@vger.kernel.org
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
lib/string.c is built with -ffreestanding, which prevents the compiler
from replacing certain functions with calls to their library versions.
On the other hand, this also prevents Clang and GCC from instrumenting
calls to memcpy() when building with KASAN, KCSAN or KMSAN:
- KASAN normally replaces memcpy() with __asan_memcpy() with the
additional cc-param,asan-kernel-mem-intrinsic-prefix=1;
- KCSAN and KMSAN replace memcpy() with __tsan_memcpy() and
__msan_memcpy() by default.
To let the tools catch memory accesses from strlcpy/strlcat, replace
the calls to memcpy() with __builtin_memcpy(), which KASAN, KCSAN and
KMSAN are able to replace even in -ffreestanding mode.
This preserves the behavior in normal builds (__builtin_memcpy() ends up
being replaced with memcpy()), and does not introduce new instrumentation
in unwanted places, as strlcpy/strlcat are already instrumented.
Suggested-by: Marco Elver <elver@google.com>
Signed-off-by: Alexander Potapenko <glider@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Link: https://lore.kernel.org/all/20230224085942.1791837-1-elver@google.com/
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230530083911.1104336-1-glider@google.com
Use strchr() instead of open coding it as it's done elsewhere in
the same file. Either we will have similar to what it was or possibly
better performance in case architecture implements its own strchr().
Memory wise on x86_64 bloat-o-meter shows the following
Function old new delta
strsep 111 102 -9
Total: Before=2763, After=2754, chg -0.33%
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230127155135.27153-1-andriy.shevchenko@linux.intel.com
While there were varying degrees of kern-doc for various str*()-family
functions, many needed updating and clarification, or to just be
entirely written. Update (and relocate) existing kern-doc and add missing
functions, sadly shaking my head at how many times I have written "Do
not use this function". Include the results in the core kernel API doc.
Cc: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: Andy Shevchenko <andy@kernel.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-hardening@vger.kernel.org
Tested-by: Akira Yokosawa <akiyks@gmail.com>
Link: https://lore.kernel.org/lkml/9b0cf584-01b3-3013-b800-1ef59fe82476@gmail.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Use strchr(), which makes them a lot shorter, and more obviously symmetric
in their treatment of accept/reject. It also saves a little bit of .text;
bloat-o-meter for an arm build says
Function old new delta
strcspn 92 76 -16
strspn 108 76 -32
While here, also remove a stray empty line before EXPORT_SYMBOL().
Link: https://lkml.kernel.org/r/20220328224119.3003834-2-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Andy Shevchenko <andy@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The core functions of string.c are those that may be implemented by
per-architecture functions, or overloaded by FORTIFY_SOURCE. As a
result, it needs to be built with __NO_FORTIFY. Without this, macros
will collide with function declarations. This was accidentally working
due to -ffreestanding (on some architectures). Make this deterministic
by explicitly setting __NO_FORTIFY and move all the helper functions
into string_helpers.c so that they gain the fortification coverage they
had been missing.
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Andy Lavr <andy.lavr@gmail.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
This just does the "if the architecture does efficient unaligned
handling, start the memcmp using 'unsigned long' accesses", since
Nikolay Borisov found a load that cares.
This is basically the minimal patch, and limited to architectures that
are known to not have slow unaligned handling. We've had the stupid
byte-at-a-time version forever, and nobody has ever even noticed before,
so let's keep the fix minimal.
A potential further improvement would be to align one of the sources in
order to at least minimize unaligned cases, but the only real case of
bigger memcmp() users seems to be the FIDEDUPERANGE ioctl(). As David
Sterba says, the dedupe ioctl is typically called on ranges spanning
many pages so the common case will all be page-aligned anyway.
All the relevant architectures select HAVE_EFFICIENT_UNALIGNED_ACCESS,
so I'm not going to worry about the combination of a very rare use-case
and a rare architecture until somebody actually hits it. Particularly
since Nikolay also tested the more complex patch with extra alignment
handling code, and it only added overhead.
Link: https://lore.kernel.org/lkml/20210721135926.602840-1-nborisov@suse.com/
Reported-by: Nikolay Borisov <nborisov@suse.com>
Cc: David Sterba <dsterba@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Generic version doesn't trucate second argument to char.
Older brother memchr() does as do s390, sparc and i386 assembly versions.
Fortunately, no code passes c >= 256.
Link: https://lkml.kernel.org/r/YLv4cCf0t5UPdyK+@localhost.localdomain
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
A few architecture specific string.h functions used to be implemented in
terms of preprocessor defines to the corresponding compiler builtins.
Since this is no longer the case, remove unused #undefs.
Only memcmp is still defined in terms of builtins for a few arches.
Link: https://github.com/ClangBuiltLinux/linux/issues/428
Link: https://lkml.kernel.org/r/20201120041113.89382-1-ndesaulniers@google.com
Fixes: 5f074f3e19 ("lib/string.c: implement a basic bcmp")
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Yury Norov <yury.norov@gmail.com>
Cc: Alexandru Ardelean <alexandru.ardelean@analog.com>
Cc: Nathan Chancellor <natechancellor@gmail.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
LLVM implemented a recent "libcall optimization" that lowers calls to
`sprintf(dest, "%s", str)` where the return value is used to
`stpcpy(dest, str) - dest`.
This generally avoids the machinery involved in parsing format strings.
`stpcpy` is just like `strcpy` except it returns the pointer to the new
tail of `dest`. This optimization was introduced into clang-12.
Implement this so that we don't observe linkage failures due to missing
symbol definitions for `stpcpy`.
Similar to last year's fire drill with: commit 5f074f3e19
("lib/string.c: implement a basic bcmp")
The kernel is somewhere between a "freestanding" environment (no full
libc) and "hosted" environment (many symbols from libc exist with the
same type, function signature, and semantics).
As Peter Anvin notes, there's not really a great way to inform the
compiler that you're targeting a freestanding environment but would like
to opt-in to some libcall optimizations (see pr/47280 below), rather
than opt-out.
Arvind notes, -fno-builtin-* behaves slightly differently between GCC
and Clang, and Clang is missing many __builtin_* definitions, which I
consider a bug in Clang and am working on fixing.
Masahiro summarizes the subtle distinction between compilers justly:
To prevent transformation from foo() into bar(), there are two ways in
Clang to do that; -fno-builtin-foo, and -fno-builtin-bar. There is
only one in GCC; -fno-buitin-foo.
(Any difference in that behavior in Clang is likely a bug from a missing
__builtin_* definition.)
Masahiro also notes:
We want to disable optimization from foo() to bar(),
but we may still benefit from the optimization from
foo() into something else. If GCC implements the same transform, we
would run into a problem because it is not -fno-builtin-bar, but
-fno-builtin-foo that disables that optimization.
In this regard, -fno-builtin-foo would be more future-proof than
-fno-built-bar, but -fno-builtin-foo is still potentially overkill. We
may want to prevent calls from foo() being optimized into calls to
bar(), but we still may want other optimization on calls to foo().
It seems that compilers today don't quite provide the fine grain control
over which libcall optimizations pseudo-freestanding environments would
prefer.
Finally, Kees notes that this interface is unsafe, so we should not
encourage its use. As such, I've removed the declaration from any
header, but it still needs to be exported to avoid linkage errors in
modules.
Reported-by: Sami Tolvanen <samitolvanen@google.com>
Suggested-by: Andy Lavr <andy.lavr@gmail.com>
Suggested-by: Arvind Sankar <nivedita@alum.mit.edu>
Suggested-by: Joe Perches <joe@perches.com>
Suggested-by: Kees Cook <keescook@chromium.org>
Suggested-by: Masahiro Yamada <masahiroy@kernel.org>
Suggested-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20200914161643.938408-1-ndesaulniers@google.com
Link: https://bugs.llvm.org/show_bug.cgi?id=47162
Link: https://bugs.llvm.org/show_bug.cgi?id=47280
Link: https://github.com/ClangBuiltLinux/linux/issues/1126
Link: https://man7.org/linux/man-pages/man3/stpcpy.3.html
Link: https://pubs.opengroup.org/onlinepubs/9699919799/functions/stpcpy.html
Link: https://reviews.llvm.org/D85963
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There were a few attempts at changing behavior of the match_string()
helpers (i.e. 'match_string()' & 'sysfs_match_string()'), to change &
extend the behavior according to the doc-string.
But the simplest approach is to just fix the doc-strings. The current
behavior is fine as-is, and some bugs were introduced trying to fix it.
As for extending the behavior, new helpers can always be introduced if
needed.
The match_string() helpers behave more like 'strncmp()' in the sense
that they go up to n elements or until the first NULL element in the
array of strings.
This change updates the doc-strings with this info.
Link: http://lkml.kernel.org/r/20200213072722.8249-1-alexandru.ardelean@analog.com
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: "Tobin C . Harding" <tobin@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "lib: rework bitmap_parse", v5.
Similarl to the recently revisited bitmap_parselist(), bitmap_parse() is
ineffective and overcomplicated. This series reworks it, aligns its
interface with bitmap_parselist() and makes it simpler to use.
The series also adds a test for the function and fixes usage of it in
cpumask_parse() according to the new design - drops the calculating of
length of an input string.
bitmap_parse() takes the array of numbers to be put into the map in the BE
order which is reversed to the natural LE order for bitmaps. For example,
to construct bitmap containing a bit on the position 42, we have to put a
line '400,0'. Current implementation reads chunk one by one from the
beginning ('400' before '0') and makes bitmap shift after each successful
parse. It makes the complexity of the whole process as O(n^2). We can do
it in reverse direction ('0' before '400') and avoid shifting, but it
requires reverse parsing helpers.
This patch (of 7):
New function works like strchrnul() with a length limited string.
Link: http://lkml.kernel.org/r/20200102043031.30357-2-yury.norov@gmail.com
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Amritha Nambiar <amritha.nambiar@intel.com>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: "Tobin C . Harding" <tobin@kernel.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Cc: Vineet Gupta <vineet.gupta1@synopsys.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
With the use of the barrier implied by barrier_data(), there is no need
for memzero_explicit() to be extern. Making it inline saves the overhead
of a function call, and allows the code to be reused in arch/*/purgatory
without having to duplicate the implementation.
Tested-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H . Peter Anvin <hpa@zytor.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephan Mueller <smueller@chronox.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-crypto@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Fixes: 906a4bb97f ("crypto: sha256 - Use get/put_unaligned_be32 to get input, memzero_explicit")
Link: https://lkml.kernel.org/r/20191007220000.GA408752@rani.riverdale.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>
core-api should show all the various string functions including the newly
added stracpy and stracpy_pad.
Miscellanea:
o Update the Returns: value for strscpy
o fix a defect with %NUL)
[joe@perches.com: correct return of -E2BIG descriptions]
Link: http://lkml.kernel.org/r/29f998b4c1a9d69fbeae70500ba0daa4b340c546.1563889130.git.joe@perches.com
Link: http://lkml.kernel.org/r/224a6ebf39955f4107c0c376d66155d970e46733.1563841972.git.joe@perches.com
Signed-off-by: Joe Perches <joe@perches.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Stephen Kitt <steve@sk2.org>
Cc: Nitin Gote <nitin.r.gote@intel.com>
Cc: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "lib/string: search for NUL with strchr/strnchr".
I noticed an inconsistency where strchr and strnchr do not behave the
same with respect to the trailing NUL. strchr is standardised and the
kernel function conforms, and the kernel relies on the behavior. So,
naturally strchr stays as-is and strnchr is what I change.
While writing a few tests to verify that my new strnchr loop was sane, I
noticed that the tests for memset16/32/64 had a problem. Since it's all
about the lib/string.c file I made a short series of it all...
This patch (of 3):
strchr considers the terminating NUL to be part of the string, and NUL
can thus be searched for with that function. For consistency, do the
same with strnchr.
Link: http://lkml.kernel.org/r/20190506124634.6807-2-peda@axentia.se
Signed-off-by: Peter Rosin <peda@axentia.se>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We have a function to copy strings safely and we have a function to copy
strings and zero the tail of the destination (if source string is
shorter than destination buffer) but we do not have a function to do
both at once. This means developers must write this themselves if they
desire this functionality. This is a chore, and also leaves us open to
off by one errors unnecessarily.
Add a function that calls strscpy() then memset()s the tail to zero if
the source string is shorter than the destination buffer.
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Tobin C. Harding <tobin@kernel.org>
Signed-off-by: Shuah Khan <shuah@kernel.org>
A recent optimization in Clang (r355672) lowers comparisons of the
return value of memcmp against zero to comparisons of the return value
of bcmp against zero. This helps some platforms that implement bcmp
more efficiently than memcmp. glibc simply aliases bcmp to memcmp, but
an optimized implementation is in the works.
This results in linkage failures for all targets with Clang due to the
undefined symbol. For now, just implement bcmp as a tailcail to memcmp
to unbreak the build. This routine can be further optimized in the
future.
Other ideas discussed:
* A weak alias was discussed, but breaks for architectures that define
their own implementations of memcmp since aliases to declarations are
not permitted (only definitions). Arch-specific memcmp
implementations typically declare memcmp in C headers, but implement
them in assembly.
* -ffreestanding also is used sporadically throughout the kernel.
* -fno-builtin-bcmp doesn't work when doing LTO.
Link: https://bugs.llvm.org/show_bug.cgi?id=41035
Link: https://code.woboq.org/userspace/glibc/string/memcmp.c.html#bcmp
Link: 8e16d73346
Link: https://github.com/ClangBuiltLinux/linux/issues/416
Link: http://lkml.kernel.org/r/20190313211335.165605-1-ndesaulniers@google.com
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Reported-by: Nathan Chancellor <natechancellor@gmail.com>
Reported-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Suggested-by: James Y Knight <jyknight@google.com>
Suggested-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Suggested-by: Nathan Chancellor <natechancellor@gmail.com>
Suggested-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kbuild robot reports that since commit ce76d938dd ("lib: Add memcat_p():
paste 2 pointer arrays together") the ia64/hp/sim/boot fails to link:
> LD arch/ia64/hp/sim/boot/bootloader
> lib/string.o: In function `__memcat_p':
> string.c:(.text+0x1f22): undefined reference to `__kmalloc'
> string.c:(.text+0x1ff2): undefined reference to `__kmalloc'
> make[1]: *** [arch/ia64/hp/sim/boot/Makefile:37: arch/ia64/hp/sim/boot/bootloader] Error 1
The reason is, the above commit, via __memcat_p(), adds a call to
__kmalloc to string.o, which happens to be used in the bootloader, but
there's no kmalloc or slab or anything.
Since the linker would only pull in objects that contain referenced
symbols, moving __memcat_p() to a different compilation unit solves the
problem.
Fixes: ce76d938dd ("lib: Add memcat_p(): paste 2 pointer arrays together")
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Reported-by: kbuild test robot <lkp@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This adds a helper to paste 2 pointer arrays together, useful for merging
various types of attribute arrays. There are a few places in the kernel
tree where this is open coded, and I just added one more in the STM class.
The naming is inspired by memset_p() and memcat(), and partial credit for
it goes to Andy Shevchenko.
This patch adds the function wrapped in a type-enforcing macro and a test
module.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
strscpy() performs the word-at-a-time optimistic reads. So it may may
access the memory past the end of the object, which is perfectly fine
since strscpy() doesn't use that (past-the-end) data and makes sure the
optimistic read won't cross a page boundary.
Use new read_word_at_a_time() to shut up the KASAN.
Note that this potentially could hide some bugs. In example bellow,
stscpy() will copy more than we should (1-3 extra uninitialized bytes):
char dst[8];
char *src;
src = kmalloc(5, GFP_KERNEL);
memset(src, 0xff, 5);
strscpy(dst, src, 8);
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Extract the string test code into its own source file, to allow
compiling it either to a loadable module, or built into the kernel.
Fixes: 03270c13c5 ("lib/string.c: add testcases for memset16/32/64")
Link: http://lkml.kernel.org/r/1505397744-3387-1-git-send-email-geert@linux-m68k.org
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.
By default all files without license information are under the default
license of the kernel, which is GPL version 2.
Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.
How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,
Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.
The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.
The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.
Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).
All documentation files were explicitly excluded.
The following heuristics were used to determine which SPDX license
identifiers to apply.
- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.
For non */uapi/* files that summary was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139
and resulted in the first patch in this series.
If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930
and resulted in the second patch in this series.
- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:
SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1
and that resulted in the third patch in this series.
- when the two scanners agreed on the detected license(s), that became
the concluded license(s).
- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.
- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).
- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.
- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.
In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.
Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.
Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.
In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.
Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct
This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.
These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This is mostly to keep the number of static checker warnings down so we
can spot new bugs instead of them being drowned in noise. This function
doesn't return normal kernel error codes but instead the return value is
used to display exactly which memory failed. I chose -1 as hopefully
that's a helpful thing to print.
Link: http://lkml.kernel.org/r/20170817115420.uikisjvfmtrqkzjn@mwanda
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Kees Cook <keescook@chromium.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc: Daniel Micay <danielmicay@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[akpm@linux-foundation.org: minor tweaks]
Link: http://lkml.kernel.org/r/20170720184539.31609-3-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "James E.J. Bottomley" <jejb@linux.vnet.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: David Miller <davem@davemloft.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Multibyte memset variations", v4.
A relatively common idiom we're missing is a function to fill an area of
memory with a pattern which is larger than a single byte. I first
noticed this with a zram patch which wanted to fill a page with an
'unsigned long' value. There turn out to be quite a few places in the
kernel which can benefit from using an optimised function rather than a
loop; sometimes text size, sometimes speed, and sometimes both. The
optimised PowerPC version (not included here) improves performance by
about 30% on POWER8 on just the raw memset_l().
Most of the extra lines of code come from the three testcases I added.
This patch (of 8):
memset16(), memset32() and memset64() are like memset(), but allow the
caller to fill the destination with a value larger than a single byte.
memset_l() and memset_p() allow the caller to use unsigned long and
pointer values respectively.
Link: http://lkml.kernel.org/r/20170720184539.31609-2-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "James E.J. Bottomley" <jejb@linux.vnet.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: David Miller <davem@davemloft.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This adds support for compiling with a rough equivalent to the glibc
_FORTIFY_SOURCE=1 feature, providing compile-time and runtime buffer
overflow checks for string.h functions when the compiler determines the
size of the source or destination buffer at compile-time. Unlike glibc,
it covers buffer reads in addition to writes.
GNU C __builtin_*_chk intrinsics are avoided because they would force a
much more complex implementation. They aren't designed to detect read
overflows and offer no real benefit when using an implementation based
on inline checks. Inline checks don't add up to much code size and
allow full use of the regular string intrinsics while avoiding the need
for a bunch of _chk functions and per-arch assembly to avoid wrapper
overhead.
This detects various overflows at compile-time in various drivers and
some non-x86 core kernel code. There will likely be issues caught in
regular use at runtime too.
Future improvements left out of initial implementation for simplicity,
as it's all quite optional and can be done incrementally:
* Some of the fortified string functions (strncpy, strcat), don't yet
place a limit on reads from the source based on __builtin_object_size of
the source buffer.
* Extending coverage to more string functions like strlcat.
* It should be possible to optionally use __builtin_object_size(x, 1) for
some functions (C strings) to detect intra-object overflows (like
glibc's _FORTIFY_SOURCE=2), but for now this takes the conservative
approach to avoid likely compatibility issues.
* The compile-time checks should be made available via a separate config
option which can be enabled by default (or always enabled) once enough
time has passed to get the issues it catches fixed.
Kees said:
"This is great to have. While it was out-of-tree code, it would have
blocked at least CVE-2016-3858 from being exploitable (improper size
argument to strlcpy()). I've sent a number of fixes for
out-of-bounds-reads that this detected upstream already"
[arnd@arndb.de: x86: fix fortified memcpy]
Link: http://lkml.kernel.org/r/20170627150047.660360-1-arnd@arndb.de
[keescook@chromium.org: avoid panic() in favor of BUG()]
Link: http://lkml.kernel.org/r/20170626235122.GA25261@beast
[keescook@chromium.org: move from -mm, add ARCH_HAS_FORTIFY_SOURCE, tweak Kconfig help]
Link: http://lkml.kernel.org/r/20170526095404.20439-1-danielmicay@gmail.com
Link: http://lkml.kernel.org/r/1497903987-21002-8-git-send-email-keescook@chromium.org
Signed-off-by: Daniel Micay <danielmicay@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Daniel Axtens <dja@axtens.net>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Here is the big USB patchset for 4.12-rc1.
Lots of good stuff here, after many many many attempts, the kernel
finally has a working typeC interface, many thanks to the Heikki and
Guenter and others who have taken the time to get this merged. It
wasn't an easy path for them at all.
There's also a staging driver that uses this new api, which is why it's
coming in through this tree.
Along with that, there's the usual huge number of changes for gadget
drivers, xhci, and other stuff. Johan also finally refactored pretty
much every driver that was looking at USB endpoints to do it in a common
way, which will help prevent any "badly-formed" devices from causing
problems in drivers. That too wasn't a simple task.
All of these have been in linux-next for a while with no reported
issues.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'usb-4.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb
Pull USB updates from Greg KH:
"Here is the big USB patchset for 4.12-rc1.
Lots of good stuff here, after many many many attempts, the kernel
finally has a working typeC interface, many thanks to Heikki and
Guenter and others who have taken the time to get this merged. It
wasn't an easy path for them at all.
There's also a staging driver that uses this new api, which is why
it's coming in through this tree.
Along with that, there's the usual huge number of changes for gadget
drivers, xhci, and other stuff. Johan also finally refactored pretty
much every driver that was looking at USB endpoints to do it in a
common way, which will help prevent any "badly-formed" devices from
causing problems in drivers. That too wasn't a simple task.
All of these have been in linux-next for a while with no reported
issues"
* tag 'usb-4.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (263 commits)
staging: typec: Fairchild FUSB302 Type-c chip driver
staging: typec: Type-C Port Controller Interface driver (tcpci)
staging: typec: USB Type-C Port Manager (tcpm)
usb: host: xhci: remove #ifdef around PM functions
usb: musb: don't mark of_dev_auxdata as initdata
usb: misc: legousbtower: Fix buffers on stack
USB: Revert "cdc-wdm: fix "out-of-sync" due to missing notifications"
usb: Make sure usb/phy/of gets built-in
USB: storage: e-mail update in drivers/usb/storage/unusual_devs.h
usb: host: xhci: print correct command ring address
usb: host: xhci: delete sp_dma_buffers for scratchpad
usb: host: xhci: using correct specification chapter reference for DCBAAP
xhci: switch to pci_alloc_irq_vectors
usb: host: xhci-plat: set resume_quirk() for R-Car controllers
usb: host: xhci-plat: add resume_quirk()
usb: host: xhci-plat: enable clk in resume timing
usb: host: plat: Enable xHCI plat runtime PM
USB: serial: ftdi_sio: add device ID for Microsemi/Arrow SF2PLUS Dev Kit
USB: serial: constify static arrays
usb: fix some references for /proc/bus/usb
...
Make a simple helper for matching strings with sysfs
attribute files. In most parts the same as match_string(),
except sysfs_match_string() uses sysfs_streq() instead of
strcmp() for matching. This is more convenient when used
with sysfs attributes.
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Create the kstrtobool_from_user() helper and move strtobool() logic into
the new kstrtobool() (matching all the other kstrto* functions).
Provides an inline wrapper for existing strtobool() callers.
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Joe Perches <joe@perches.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Amitkumar Karwar <akarwar@marvell.com>
Cc: Nishant Sarmukadam <nishants@marvell.com>
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: Steve French <sfrench@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Occasionally we have to search for an occurrence of a string in an array
of strings. Make a simple helper for that purpose.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: David Airlie <airlied@linux.ie>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
8-byte constant is too big for long and compiler complains about this.
lib/string.c:907:20: warning: constant 0x0101010101010101 is so big it is long
Append ULL suffix to explicitly show its type.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It's possible that the destination can be shadowed in userspace
(as, for example, the perf buffers are now). So we should take
care not to leak data that could be inspected by userspace.
Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com>
The strscpy() API is intended to be used instead of strlcpy(),
and instead of most uses of strncpy().
- Unlike strlcpy(), it doesn't read from memory beyond (src + size).
- Unlike strlcpy() or strncpy(), the API provides an easy way to check
for destination buffer overflow: an -E2BIG error return value.
- The provided implementation is robust in the face of the source
buffer being asynchronously changed during the copy, unlike the
current implementation of strlcpy().
- Unlike strncpy(), the destination buffer will be NUL-terminated
if the string in the source buffer is too long.
- Also unlike strncpy(), the destination buffer will not be updated
beyond the NUL termination, avoiding strncpy's behavior of zeroing
the entire tail end of the destination buffer. (A memset() after
the strscpy() can be used if this behavior is desired.)
- The implementation should be reasonably performant on all
platforms since it uses the asm/word-at-a-time.h API rather than
simple byte copy. Kernel-to-kernel string copy is not considered
to be performance critical in any case.
Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com>
Strings are sometimes sanitized by replacing a certain character (often
'/') by another (often '!'). In a few places, this is done the same way
Schlemiel the Painter would do it. Others are slightly smarter but still
do multiple strchr() calls. Introduce strreplace() to do this using a
single function call and a single pass over the string.
One would expect the return value to be one of three things: void, s, or
the number of replacements made. I chose the fourth, returning a pointer
to the end of the string. This is more likely to be useful (for example
allowing the caller to avoid a strlen call).
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Neil Brown <neilb@suse.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In commit 0b053c9518 ("lib: memzero_explicit: use barrier instead
of OPTIMIZER_HIDE_VAR"), we made memzero_explicit() more robust in
case LTO would decide to inline memzero_explicit() and eventually
find out it could be elimiated as dead store.
While using barrier() works well for the case of gcc, recent efforts
from LLVMLinux people suggest to use llvm as an alternative to gcc,
and there, Stephan found in a simple stand-alone user space example
that llvm could nevertheless optimize and thus elimitate the memset().
A similar issue has been observed in the referenced llvm bug report,
which is regarded as not-a-bug.
Based on some experiments, icc is a bit special on its own, while it
doesn't seem to eliminate the memset(), it could do so with an own
implementation, and then result in similar findings as with llvm.
The fix in this patch now works for all three compilers (also tested
with more aggressive optimization levels). Arguably, in the current
kernel tree it's more of a theoretical issue, but imho, it's better
to be pedantic about it.
It's clearly visible with gcc/llvm though, with the below code: if we
would have used barrier() only here, llvm would have omitted clearing,
not so with barrier_data() variant:
static inline void memzero_explicit(void *s, size_t count)
{
memset(s, 0, count);
barrier_data(s);
}
int main(void)
{
char buff[20];
memzero_explicit(buff, sizeof(buff));
return 0;
}
$ gcc -O2 test.c
$ gdb a.out
(gdb) disassemble main
Dump of assembler code for function main:
0x0000000000400400 <+0>: lea -0x28(%rsp),%rax
0x0000000000400405 <+5>: movq $0x0,-0x28(%rsp)
0x000000000040040e <+14>: movq $0x0,-0x20(%rsp)
0x0000000000400417 <+23>: movl $0x0,-0x18(%rsp)
0x000000000040041f <+31>: xor %eax,%eax
0x0000000000400421 <+33>: retq
End of assembler dump.
$ clang -O2 test.c
$ gdb a.out
(gdb) disassemble main
Dump of assembler code for function main:
0x00000000004004f0 <+0>: xorps %xmm0,%xmm0
0x00000000004004f3 <+3>: movaps %xmm0,-0x18(%rsp)
0x00000000004004f8 <+8>: movl $0x0,-0x8(%rsp)
0x0000000000400500 <+16>: lea -0x18(%rsp),%rax
0x0000000000400505 <+21>: xor %eax,%eax
0x0000000000400507 <+23>: retq
End of assembler dump.
As gcc, clang, but also icc defines __GNUC__, it's sufficient to define
this in compiler-gcc.h only to be picked up. For a fallback or otherwise
unsupported compiler, we define it as a barrier. Similarly, for ecc which
does not support gcc inline asm.
Reference: https://llvm.org/bugs/show_bug.cgi?id=15495
Reported-by: Stephan Mueller <smueller@chronox.de>
Tested-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Stephan Mueller <smueller@chronox.de>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: mancha security <mancha1@zoho.com>
Cc: Mark Charlebois <charlebm@gmail.com>
Cc: Behan Webster <behanw@converseincode.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
OPTIMIZER_HIDE_VAR(), as defined when using gcc, is insufficient to
ensure protection from dead store optimization.
For the random driver and crypto drivers, calls are emitted ...
$ gdb vmlinux
(gdb) disassemble memzero_explicit
Dump of assembler code for function memzero_explicit:
0xffffffff813a18b0 <+0>: push %rbp
0xffffffff813a18b1 <+1>: mov %rsi,%rdx
0xffffffff813a18b4 <+4>: xor %esi,%esi
0xffffffff813a18b6 <+6>: mov %rsp,%rbp
0xffffffff813a18b9 <+9>: callq 0xffffffff813a7120 <memset>
0xffffffff813a18be <+14>: pop %rbp
0xffffffff813a18bf <+15>: retq
End of assembler dump.
(gdb) disassemble extract_entropy
[...]
0xffffffff814a5009 <+313>: mov %r12,%rdi
0xffffffff814a500c <+316>: mov $0xa,%esi
0xffffffff814a5011 <+321>: callq 0xffffffff813a18b0 <memzero_explicit>
0xffffffff814a5016 <+326>: mov -0x48(%rbp),%rax
[...]
... but in case in future we might use facilities such as LTO, then
OPTIMIZER_HIDE_VAR() is not sufficient to protect gcc from a possible
eviction of the memset(). We have to use a compiler barrier instead.
Minimal test example when we assume memzero_explicit() would *not* be
a call, but would have been *inlined* instead:
static inline void memzero_explicit(void *s, size_t count)
{
memset(s, 0, count);
<foo>
}
int main(void)
{
char buff[20];
snprintf(buff, sizeof(buff) - 1, "test");
printf("%s", buff);
memzero_explicit(buff, sizeof(buff));
return 0;
}
With <foo> := OPTIMIZER_HIDE_VAR():
(gdb) disassemble main
Dump of assembler code for function main:
[...]
0x0000000000400464 <+36>: callq 0x400410 <printf@plt>
0x0000000000400469 <+41>: xor %eax,%eax
0x000000000040046b <+43>: add $0x28,%rsp
0x000000000040046f <+47>: retq
End of assembler dump.
With <foo> := barrier():
(gdb) disassemble main
Dump of assembler code for function main:
[...]
0x0000000000400464 <+36>: callq 0x400410 <printf@plt>
0x0000000000400469 <+41>: movq $0x0,(%rsp)
0x0000000000400471 <+49>: movq $0x0,0x8(%rsp)
0x000000000040047a <+58>: movl $0x0,0x10(%rsp)
0x0000000000400482 <+66>: xor %eax,%eax
0x0000000000400484 <+68>: add $0x28,%rsp
0x0000000000400488 <+72>: retq
End of assembler dump.
As can be seen, movq, movq, movl are being emitted inlined
via memset().
Reference: http://thread.gmane.org/gmane.linux.kernel.cryptoapi/13764/
Fixes: d4c5efdb97 ("random: add and use memzero_explicit() for clearing data")
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: mancha security <mancha1@zoho.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Pull crypto update from Herbert Xu:
"Here is the crypto update for 3.20:
- Added 192/256-bit key support to aesni GCM.
- Added MIPS OCTEON MD5 support.
- Fixed hwrng starvation and race conditions.
- Added note that memzero_explicit is not a subsitute for memset.
- Added user-space interface for crypto_rng.
- Misc fixes"
* git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: (71 commits)
crypto: tcrypt - do not allocate iv on stack for aead speed tests
crypto: testmgr - limit IV copy length in aead tests
crypto: tcrypt - fix buflen reminder calculation
crypto: testmgr - mark rfc4106(gcm(aes)) as fips_allowed
crypto: caam - fix resource clean-up on error path for caam_jr_init
crypto: caam - pair irq map and dispose in the same function
crypto: ccp - terminate ccp_support array with empty element
crypto: caam - remove unused local variable
crypto: caam - remove dead code
crypto: caam - don't emit ICV check failures to dmesg
hwrng: virtio - drop extra empty line
crypto: replace scatterwalk_sg_next with sg_next
crypto: atmel - Free memory in error path
crypto: doc - remove colons in comments
crypto: seqiv - Ensure that IV size is at least 8 bytes
crypto: cts - Weed out non-CBC algorithms
MAINTAINERS: add linux-crypto to hw random
crypto: cts - Remove bogus use of seqiv
crypto: qat - don't need qat_auth_state struct
crypto: algif_rng - fix sparse non static symbol warning
...
Instead of potentially passing over the string twice in case c is not
found, just keep track of the last occurrence. According to
bloat-o-meter, this also cuts the generated code by a third (54 vs 36
bytes). Oh, and we get rid of those 7-space indented lines.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that all in-tree users of strnicmp have been converted to
strncasecmp, the wrapper can be removed.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: David Howells <dhowells@redhat.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Lets improve the comment to add a note on when to use memzero_explicit()
for those not digging through the git logs. We don't want people to
pollute places with memzero_explicit() where it's not really necessary.
Reference: https://lkml.org/lkml/2015/1/4/190
Suggested-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
optimized away by GCC. This is important when we are wiping
cryptographically sensitive material.
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Merge tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random
Pull /dev/random updates from Ted Ts'o:
"This adds a memzero_explicit() call which is guaranteed not to be
optimized away by GCC. This is important when we are wiping
cryptographically sensitive material"
* tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random:
crypto: memzero_explicit - make sure to clear out sensitive data
random: add and use memzero_explicit() for clearing data
zatimend has reported that in his environment (3.16/gcc4.8.3/corei7)
memset() calls which clear out sensitive data in extract_{buf,entropy,
entropy_user}() in random driver are being optimized away by gcc.
Add a helper memzero_explicit() (similarly as explicit_bzero() variants)
that can be used in such cases where a variable with sensitive data is
being cleared out in the end. Other use cases might also be in crypto
code. [ I have put this into lib/string.c though, as it's always built-in
and doesn't need any dependencies then. ]
Fixes kernel bugzilla: 82041
Reported-by: zatimend@hotmail.co.uk
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
The previous patch made strnicmp into a wrapper for strncasecmp.
This patch makes all in-tree users of strnicmp call strncasecmp
directly, while still making sure that the strnicmp symbol can be used
by out-of-tree modules. It should be considered a temporary hack until
all in-tree callers have been converted.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
