From: Xiongwei Song <sxwjean@xxxxxxxxx>
Hello,
This patchset are to use generic code for randomization of virtual address
of x86. Since the basic code logic of x86 is same as generic code, so no
need to implement these functions on x86.
Patch 1~3 are prepared to change the generic code to apply to x86.
Patch 4 is to switch to generic arch_pick_mmap_layout() with
ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT enabled. Also provided basically
test and the result was put in commit message too.
Patch 5~6 are used to handle the legacy things.
Test programs(to verify if the entropy of return value of mmap is kept
after applying the patchset):
- C code for mmap test:
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
int main(int argc, char *argv[])
{
unsigned long *addr;
addr = mmap(NULL, 4096, PROT_READ, MAP_SHARED|MAP_ANONYMOUS, -1, 0);
if (addr == MAP_FAILED) {
printf("NULL\n");
} else {
printf("%lx\n", (unsigned long)addr);
munmap(addr, 4096);
}
return 0;
}
- Shell script for collecting output of C progarm above and give a
statistics:
#!/bin/bash
declare -a COUNT
if [ "$1" == "" ]; then
echo "Please give a test number!"
exit 1
fi
number=$1
for ((i=0; i<$number; i++))
do
addr=$(mmaptest)
addr=$(((16#$addr&0xf000000000)>>36))
COUNT[$addr]=$((COUNT[$addr]+1))
done
echo " Virtual Address Range | hit times "
echo "----------------------------------------"
for ((i=0; i<16; i++))
do
j=`echo "obase=16; $i" | bc`
echo "0x7f${j,,}000000000 - 0x7f${j,,}ffffff000 | ${COUNT[i]}"
done
Run 10 thousands times C progam, collect the output with shell script, get
the test results below:
Before the patchset:
Virtual Address Range | hit times
----------------------------------------
0x7f0000000000 - 0x7f0ffffff000 | 655
0x7f1000000000 - 0x7f1ffffff000 | 617
0x7f2000000000 - 0x7f2ffffff000 | 636
0x7f3000000000 - 0x7f3ffffff000 | 625
0x7f4000000000 - 0x7f4ffffff000 | 651
0x7f5000000000 - 0x7f5ffffff000 | 591
0x7f6000000000 - 0x7f6ffffff000 | 623
0x7f7000000000 - 0x7f7ffffff000 | 627
0x7f8000000000 - 0x7f8ffffff000 | 638
0x7f9000000000 - 0x7f9ffffff000 | 586
0x7fa000000000 - 0x7faffffff000 | 637
0x7fb000000000 - 0x7fbffffff000 | 607
0x7fc000000000 - 0x7fcffffff000 | 618
0x7fd000000000 - 0x7fdffffff000 | 656
0x7fe000000000 - 0x7feffffff000 | 614
0x7ff000000000 - 0x7ffffffff000 | 619
After the patchset:
Virtual Address Range | hit times
----------------------------------------
0x7f0000000000 - 0x7f0ffffff000 | 661
0x7f1000000000 - 0x7f1ffffff000 | 645
0x7f2000000000 - 0x7f2ffffff000 | 609
0x7f3000000000 - 0x7f3ffffff000 | 594
0x7f4000000000 - 0x7f4ffffff000 | 616
0x7f5000000000 - 0x7f5ffffff000 | 622
0x7f6000000000 - 0x7f6ffffff000 | 617
0x7f7000000000 - 0x7f7ffffff000 | 582
0x7f8000000000 - 0x7f8ffffff000 | 618
0x7f9000000000 - 0x7f9ffffff000 | 629
0x7fa000000000 - 0x7faffffff000 | 635
0x7fb000000000 - 0x7fbffffff000 | 625
0x7fc000000000 - 0x7fcffffff000 | 614
0x7fd000000000 - 0x7fdffffff000 | 610
0x7fe000000000 - 0x7feffffff000 | 648
0x7ff000000000 - 0x7ffffffff000 | 675
v1 -> v2:
- Spilt the patch 2 of v1 as Kees suggested.
- Drop patch 1 of v1, which renamed TIF_ADDR32 to TIF_32BIT, which is
unreasonable for x86. Because in x86, 64bit process can call 32bit
syscall. Thanks Peterz for pointing this out.
v1:
- https://lkml.org/lkml/2021/9/21/482
- https://lkml.org/lkml/2021/9/21/484
- https://lkml.org/lkml/2021/9/27/688
Please review.
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx>
Cc: Lai Jiangshan <laijs@xxxxxxxxxxxxxxxxx>
Cc: Huang Rui <ray.huang@xxxxxxx>
Cc: Yazen Ghannam <yazen.ghannam@xxxxxxx>
Cc: Kim Phillips <kim.phillips@xxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Balbir Singh <sblbir@xxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: sxwjean@xxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Xiongwei Song (6):
mm/util: Assign a meaningful value to mmap_legacy_base
mm/util: Allow to pass a specific task size when getting mmapping base
mm/util: Support CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES
x86/mm: Randomize VA with generit arch_pick_mmap_layout()
x86/mm: Discard the defination of HAVE_ARCH_PICK_MMAP_LAYOUT
x86/elf: Discard ARCH_HAS_ELF_RANDOMIZE selection
arch/x86/Kconfig | 2 +-
arch/x86/include/asm/compat.h | 5 ++
arch/x86/include/asm/processor.h | 5 +-
arch/x86/mm/mmap.c | 112 -------------------------------
mm/util.c | 35 +++++++---
5 files changed, 37 insertions(+), 122 deletions(-)
--
2.30.2
