Messages in this thread | | | Subject | Re: [PATCH v2 0/6] Use generic code for randomization of virtual address of x86 | From | Xiongwei Song <> | Date | Fri, 15 Oct 2021 21:47:15 +0800 |
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Hi Experts,
Gentle reminder. Any comments would be appreciated. Thank you so much.
Regards, Xiongwei
> On Oct 11, 2021, at 10:31 PM, sxwjean@me.com wrote: > > From: Xiongwei Song <sxwjean@gmail.com> > > 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@linutronix.de> > Cc: Ingo Molnar <mingo@redhat.com> > Cc: Borislav Petkov <bp@alien8.de> > Cc: Kees Cook <keescook@chromium.org> > Cc: "H. Peter Anvin" <hpa@zytor.com> > Cc: Dave Hansen <dave.hansen@linux.intel.com> > Cc: Andy Lutomirski <luto@kernel.org> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Arnd Bergmann <arnd@arndb.de> > Cc: Al Viro <viro@zeniv.linux.org.uk> > Cc: Gabriel Krisman Bertazi <krisman@collabora.com> > Cc: Lai Jiangshan <laijs@linux.alibaba.com> > Cc: Huang Rui <ray.huang@amd.com> > Cc: Yazen Ghannam <yazen.ghannam@amd.com> > Cc: Kim Phillips <kim.phillips@amd.com> > Cc: Oleg Nesterov <oleg@redhat.com> > Cc: Balbir Singh <sblbir@amazon.com> > Cc: "David S. Miller" <davem@davemloft.net> > Cc: sxwjean@me.com > Cc: linux-kernel@vger.kernel.org > > 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 >
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