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Add support for recent kmem_cache_create_usercopy

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SLAB_USERCOPY flag was used to indicate PAX
not to kill copies from kernel to userland.

With recent grsecurity patchset and
CONFIG_GRKERNSEC_HIDESYM that enables
CONFIG_PAX_USERCOPY zfs would panic.

Handle newer API while keeping old one functional.

Tested-by: RageLtMan <rageltman@sempervictus>
Reviewed-by: spendergrsec <spender@grsecurity.net>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Kevin Tanguy <kevin.tanguy@ovh.net>
Closes #595
This commit is contained in:
Kevin Tanguy 2017-01-17 21:05:14 +01:00 committed by Brian Behlendorf
parent 120faefed9
commit 0194e4a03c
2 changed files with 48 additions and 2 deletions
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37
config/spl-build.m4
View File

@ -50,6 +50,7 @@ AC_DEFUN([SPL_AC_CONFIG_KERNEL], [
SPL_AC_MUTEX_OWNER SPL_AC_MUTEX_OWNER
SPL_AC_INODE_LOCK SPL_AC_INODE_LOCK
SPL_AC_GROUP_INFO_GID SPL_AC_GROUP_INFO_GID
SPL_AC_KMEM_CACHE_CREATE_USERCOPY
]) ])
AC_DEFUN([SPL_AC_MODULE_SYMVERS], [ AC_DEFUN([SPL_AC_MODULE_SYMVERS], [
@ -1597,3 +1598,39 @@ AC_DEFUN([SPL_AC_GROUP_INFO_GID], [
]) ])
EXTRA_KCFLAGS="$tmp_flags" EXTRA_KCFLAGS="$tmp_flags"
]) ])
dnl #
dnl # grsecurity API change,
dnl # kmem_cache_create() with SLAB_USERCOPY flag replaced by
dnl # kmem_cache_create_usercopy().
dnl #
AC_DEFUN([SPL_AC_KMEM_CACHE_CREATE_USERCOPY], [
AC_MSG_CHECKING([whether kmem_cache_create_usercopy() exists])
tmp_flags="$EXTRA_KCFLAGS"
EXTRA_KCFLAGS="-Werror"
SPL_LINUX_TRY_COMPILE([
#include <linux/slab.h>
static void ctor(void *foo)
{
// fake ctor
}
],[
struct kmem_cache *skc_linux_cache;
const char *name = "test";
size_t size = 4096;
size_t align = 8;
unsigned long flags = 0;
size_t useroffset = 0;
size_t usersize = size - useroffset;
skc_linux_cache = kmem_cache_create_usercopy(
name, size, align, flags, useroffset, usersize, ctor);
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_KMEM_CACHE_CREATE_USERCOPY, 1,
[kmem_cache_create_usercopy() exists])
],[
AC_MSG_RESULT(no)
])
EXTRA_KCFLAGS="$tmp_flags"
])

13
module/spl/spl-kmem-cache.c
View File

@ -1001,8 +1001,17 @@ spl_kmem_cache_create(char *name, size_t size, size_t align,
slabflags |= SLAB_USERCOPY; slabflags |= SLAB_USERCOPY;
#endif #endif
skc->skc_linux_cache = kmem_cache_create( #if defined(HAVE_KMEM_CACHE_CREATE_USERCOPY)
skc->skc_name, size, align, slabflags, NULL); /*
* Newer grsec patchset uses kmem_cache_create_usercopy()
* instead of SLAB_USERCOPY flag
*/
skc->skc_linux_cache = kmem_cache_create_usercopy(
skc->skc_name, size, align, slabflags, 0, size, NULL);
#else
skc->skc_linux_cache = kmem_cache_create(
skc->skc_name, size, align, slabflags, NULL);
#endif
if (skc->skc_linux_cache == NULL) { if (skc->skc_linux_cache == NULL) {
rc = ENOMEM; rc = ENOMEM;
goto out; goto out;