mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-02 10:46:50 +07:00
9e08f57d68
x86: arch_mmap_rnd() uses hard-coded values, 8 for 32-bit and 28 for 64-bit, to generate the random offset for the mmap base address. This value represents a compromise between increased ASLR effectiveness and avoiding address-space fragmentation. Replace it with a Kconfig option, which is sensibly bounded, so that platform developers may choose where to place this compromise. Keep default values as new minimums. Signed-off-by: Daniel Cashman <dcashman@google.com> Cc: Russell King <linux@arm.linux.org.uk> Acked-by: Kees Cook <keescook@chromium.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Don Zickus <dzickus@redhat.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Heinrich Schuchardt <xypron.glpk@gmx.de> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: David Rientjes <rientjes@google.com> Cc: Mark Salyzyn <salyzyn@android.com> Cc: Jeff Vander Stoep <jeffv@google.com> Cc: Nick Kralevich <nnk@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hector Marco-Gisbert <hecmargi@upv.es> Cc: Borislav Petkov <bp@suse.de> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
136 lines
3.3 KiB
C
136 lines
3.3 KiB
C
/*
|
|
* Flexible mmap layout support
|
|
*
|
|
* Based on code by Ingo Molnar and Andi Kleen, copyrighted
|
|
* as follows:
|
|
*
|
|
* Copyright 2003-2009 Red Hat Inc.
|
|
* All Rights Reserved.
|
|
* Copyright 2005 Andi Kleen, SUSE Labs.
|
|
* Copyright 2007 Jiri Kosina, SUSE Labs.
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
|
|
*/
|
|
|
|
#include <linux/personality.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/random.h>
|
|
#include <linux/limits.h>
|
|
#include <linux/sched.h>
|
|
#include <asm/elf.h>
|
|
|
|
struct va_alignment __read_mostly va_align = {
|
|
.flags = -1,
|
|
};
|
|
|
|
static unsigned long stack_maxrandom_size(void)
|
|
{
|
|
unsigned long max = 0;
|
|
if ((current->flags & PF_RANDOMIZE) &&
|
|
!(current->personality & ADDR_NO_RANDOMIZE)) {
|
|
max = ((-1UL) & STACK_RND_MASK) << PAGE_SHIFT;
|
|
}
|
|
|
|
return max;
|
|
}
|
|
|
|
/*
|
|
* Top of mmap area (just below the process stack).
|
|
*
|
|
* Leave an at least ~128 MB hole with possible stack randomization.
|
|
*/
|
|
#define MIN_GAP (128*1024*1024UL + stack_maxrandom_size())
|
|
#define MAX_GAP (TASK_SIZE/6*5)
|
|
|
|
static int mmap_is_legacy(void)
|
|
{
|
|
if (current->personality & ADDR_COMPAT_LAYOUT)
|
|
return 1;
|
|
|
|
if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
|
|
return 1;
|
|
|
|
return sysctl_legacy_va_layout;
|
|
}
|
|
|
|
unsigned long arch_mmap_rnd(void)
|
|
{
|
|
unsigned long rnd;
|
|
|
|
if (mmap_is_ia32())
|
|
#ifdef CONFIG_COMPAT
|
|
rnd = (unsigned long)get_random_int() & ((1 << mmap_rnd_compat_bits) - 1);
|
|
#else
|
|
rnd = (unsigned long)get_random_int() & ((1 << mmap_rnd_bits) - 1);
|
|
#endif
|
|
else
|
|
rnd = (unsigned long)get_random_int() & ((1 << mmap_rnd_bits) - 1);
|
|
|
|
return rnd << PAGE_SHIFT;
|
|
}
|
|
|
|
static unsigned long mmap_base(unsigned long rnd)
|
|
{
|
|
unsigned long gap = rlimit(RLIMIT_STACK);
|
|
|
|
if (gap < MIN_GAP)
|
|
gap = MIN_GAP;
|
|
else if (gap > MAX_GAP)
|
|
gap = MAX_GAP;
|
|
|
|
return PAGE_ALIGN(TASK_SIZE - gap - rnd);
|
|
}
|
|
|
|
/*
|
|
* Bottom-up (legacy) layout on X86_32 did not support randomization, X86_64
|
|
* does, but not when emulating X86_32
|
|
*/
|
|
static unsigned long mmap_legacy_base(unsigned long rnd)
|
|
{
|
|
if (mmap_is_ia32())
|
|
return TASK_UNMAPPED_BASE;
|
|
else
|
|
return TASK_UNMAPPED_BASE + rnd;
|
|
}
|
|
|
|
/*
|
|
* This function, called very early during the creation of a new
|
|
* process VM image, sets up which VM layout function to use:
|
|
*/
|
|
void arch_pick_mmap_layout(struct mm_struct *mm)
|
|
{
|
|
unsigned long random_factor = 0UL;
|
|
|
|
if (current->flags & PF_RANDOMIZE)
|
|
random_factor = arch_mmap_rnd();
|
|
|
|
mm->mmap_legacy_base = mmap_legacy_base(random_factor);
|
|
|
|
if (mmap_is_legacy()) {
|
|
mm->mmap_base = mm->mmap_legacy_base;
|
|
mm->get_unmapped_area = arch_get_unmapped_area;
|
|
} else {
|
|
mm->mmap_base = mmap_base(random_factor);
|
|
mm->get_unmapped_area = arch_get_unmapped_area_topdown;
|
|
}
|
|
}
|
|
|
|
const char *arch_vma_name(struct vm_area_struct *vma)
|
|
{
|
|
if (vma->vm_flags & VM_MPX)
|
|
return "[mpx]";
|
|
return NULL;
|
|
}
|