1. 08 Oct, 2019 1 commit
  2. 26 Sep, 2019 2 commits
  3. 17 Jul, 2019 1 commit
  4. 08 Apr, 2019 1 commit
    • Tobin C. Harding's avatar
      lib/string: Add strscpy_pad() function · 458a3bf8
      Tobin C. Harding authored
      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: default avatarKees Cook <keescook@chromium.org>
      Signed-off-by: default avatarTobin C. Harding <tobin@kernel.org>
      Signed-off-by: default avatarShuah Khan <shuah@kernel.org>
      458a3bf8
  5. 06 Apr, 2019 1 commit
  6. 16 Oct, 2018 1 commit
    • Alexander Shishkin's avatar
      lib: Fix ia64 bootloader linkage · 93048c09
      Alexander Shishkin authored
      kbuild robot reports that since commit ce76d938 ("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: ce76d938 ("lib: Add memcat_p(): paste 2 pointer arrays together")
      Signed-off-by: default avatarAlexander Shishkin <alexander.shishkin@linux.intel.com>
      Reported-by: default avatarkbuild 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: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      93048c09
  7. 11 Oct, 2018 1 commit
  8. 01 Feb, 2018 1 commit
    • Andrey Ryabinin's avatar
      lib/strscpy: Shut up KASAN false-positives in strscpy() · 1a3241ff
      Andrey Ryabinin authored
      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: default avatarAndrey Ryabinin <aryabinin@virtuozzo.com>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      1a3241ff
  9. 18 Nov, 2017 1 commit
  10. 02 Nov, 2017 1 commit
    • Greg Kroah-Hartman's avatar
      License cleanup: add SPDX GPL-2.0 license identifier to files with no license · b2441318
      Greg Kroah-Hartman authored
      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: default avatarKate Stewart <kstewart@linuxfoundation.org>
      Reviewed-by: default avatarPhilippe Ombredanne <pombredanne@nexb.com>
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      b2441318
  11. 09 Sep, 2017 3 commits
    • Dan Carpenter's avatar
      lib/string.c: check for kmalloc() failure · da436528
      Dan Carpenter authored
      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@mwandaSigned-off-by: default avatarDan 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: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      da436528
    • Matthew Wilcox's avatar
      lib/string.c: add testcases for memset16/32/64 · 03270c13
      Matthew Wilcox authored
      [akpm@linux-foundation.org: minor tweaks]
      Link: http://lkml.kernel.org/r/20170720184539.31609-3-willy@infradead.orgSigned-off-by: default avatarMatthew 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: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      03270c13
    • Matthew Wilcox's avatar
      lib/string.c: add multibyte memset functions · 3b3c4bab
      Matthew Wilcox authored
      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.orgSigned-off-by: default avatarMatthew 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: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      3b3c4bab
  12. 12 Jul, 2017 1 commit
    • Daniel Micay's avatar
      include/linux/string.h: add the option of fortified string.h functions · 6974f0c4
      Daniel Micay authored
      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.orgSigned-off-by: default avatarDaniel Micay <danielmicay@gmail.com>
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
      Acked-by: default avatarKees 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: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      6974f0c4
  13. 02 Apr, 2017 1 commit
    • mchehab@s-opensource.com's avatar
      kernel-api.rst: fix a series of errors when parsing C files · 0e056eb5
      mchehab@s-opensource.com authored
      ./lib/string.c:134: WARNING: Inline emphasis start-string without end-string.
      ./mm/filemap.c:522: WARNING: Inline interpreted text or phrase reference start-string without end-string.
      ./mm/filemap.c:1283: ERROR: Unexpected indentation.
      ./mm/filemap.c:3003: WARNING: Inline interpreted text or phrase reference start-string without end-string.
      ./mm/vmalloc.c:1544: WARNING: Inline emphasis start-string without end-string.
      ./mm/page_alloc.c:4245: ERROR: Unexpected indentation.
      ./ipc/util.c:676: ERROR: Unexpected indentation.
      ./drivers/pci/irq.c:35: WARNING: Block quote ends without a blank line; unexpected unindent.
      ./security/security.c:109: ERROR: Unexpected indentation.
      ./security/security.c:110: WARNING: Definition list ends without a blank line; unexpected unindent.
      ./block/genhd.c:275: WARNING: Inline strong start-string without end-string.
      ./block/genhd.c:283: WARNING: Inline strong start-string without end-string.
      ./include/linux/clk.h:134: WARNING: Inline emphasis start-string without end-string.
      ./include/linux/clk.h:134: WARNING: Inline emphasis start-string without end-string.
      ./ipc/util.c:477: ERROR: Unknown target name: "s".
      Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@s-opensource.com>
      Acked-by: default avatarBjorn Helgaas <bhelgaas@google.com>
      Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
      0e056eb5
  14. 23 Mar, 2017 1 commit
  15. 17 Mar, 2016 2 commits
    • Kees Cook's avatar
      lib: move strtobool() to kstrtobool() · ef951599
      Kees Cook authored
      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: default avatarKees 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: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      ef951599
    • Andy Shevchenko's avatar
      lib/string: introduce match_string() helper · 56b06081
      Andy Shevchenko authored
      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: default avatarAndy 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: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      56b06081
  16. 11 Nov, 2015 1 commit
  17. 06 Oct, 2015 1 commit
  18. 10 Sep, 2015 1 commit
    • Chris Metcalf's avatar
      string: provide strscpy() · 30035e45
      Chris Metcalf authored
      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: default avatarChris Metcalf <cmetcalf@ezchip.com>
      30035e45
  19. 26 Jun, 2015 1 commit
    • Rasmus Villemoes's avatar
      lib/string.c: introduce strreplace() · 94df2904
      Rasmus Villemoes authored
      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: default avatarRasmus 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: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      94df2904
  20. 04 May, 2015 1 commit
    • Daniel Borkmann's avatar
      lib: make memzero_explicit more robust against dead store elimination · 7829fb09
      Daniel Borkmann authored
      In commit 0b053c95 ("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=15495Reported-by: default avatarStephan Mueller <smueller@chronox.de>
      Tested-by: default avatarStephan Mueller <smueller@chronox.de>
      Signed-off-by: default avatarDaniel 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: default avatarHerbert Xu <herbert@gondor.apana.org.au>
      7829fb09
  21. 19 Mar, 2015 1 commit
    • mancha security's avatar
      lib: memzero_explicit: use barrier instead of OPTIMIZER_HIDE_VAR · 0b053c95
      mancha security authored
      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: d4c5efdb ("random: add and use memzero_explicit() for clearing data")
      Cc: Theodore Ts'o <tytso@mit.edu>
      Signed-off-by: default avatarmancha security <mancha1@zoho.com>
      Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      Acked-by: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
      Acked-by: default avatarStephan Mueller <smueller@chronox.de>
      Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
      0b053c95
  22. 14 Feb, 2015 1 commit
  23. 13 Feb, 2015 1 commit
  24. 08 Jan, 2015 1 commit
  25. 17 Oct, 2014 1 commit
    • Daniel Borkmann's avatar
      random: add and use memzero_explicit() for clearing data · d4c5efdb
      Daniel Borkmann authored
      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: default avatarDaniel Borkmann <dborkman@redhat.com>
      Acked-by: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
      Cc: Alexey Dobriyan <adobriyan@gmail.com>
      Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
      Cc: stable@vger.kernel.org
      d4c5efdb
  26. 14 Oct, 2014 2 commits
  27. 13 Sep, 2014 1 commit
    • Linus Torvalds's avatar
      Make ARCH_HAS_FAST_MULTIPLIER a real config variable · 72d93104
      Linus Torvalds authored
      It used to be an ad-hoc hack defined by the x86 version of
      <asm/bitops.h> that enabled a couple of library routines to know whether
      an integer multiply is faster than repeated shifts and additions.
      
      This just makes it use the real Kconfig system instead, and makes x86
      (which was the only architecture that did this) select the option.
      
      NOTE! Even for x86, this really is kind of wrong.  If we cared, we would
      probably not enable this for builds optimized for netburst (P4), where
      shifts-and-adds are generally faster than multiplies.  This patch does
      *not* change that kind of logic, though, it is purely a syntactic change
      with no code changes.
      
      This was triggered by the fact that we have other places that really
      want to know "do I want to expand multiples by constants by hand or
      not", particularly the hash generation code.
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      72d93104
  28. 04 Jun, 2014 1 commit
  29. 23 May, 2014 1 commit
    • Grant Likely's avatar
      lib: add glibc style strchrnul() variant · 11d200e9
      Grant Likely authored
      The strchrnul() variant helpfully returns a the end of the string
      instead of a NULL if the requested character is not found. This can
      simplify string parsing code since it doesn't need to expicitly check
      for a NULL return. If a valid string pointer is passed in, then a valid
      null terminated string will always come back out.
      Signed-off-by: default avatarGrant Likely <grant.likely@linaro.org>
      11d200e9
  30. 14 Feb, 2014 1 commit
  31. 23 Mar, 2012 1 commit
  32. 07 Mar, 2012 1 commit
  33. 29 Feb, 2012 1 commit
  34. 01 Nov, 2011 2 commits