kernel-hardening - Re: [PATCH v1] kdump, vmcoreinfo: report memory sections virtual addresses

server OS

Message-ID: <20160829101137.GA29344@x1.redhat.com>
Date: Mon, 29 Aug 2016 18:11:37 +0800
From: Baoquan He <bhe@...hat.com>
To: Thomas Garnier <thgarnie@...gle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>,
        Eric Biederman <ebiederm@...ssion.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Xunlei Pang <xlpang@...hat.com>,
        HATAYAMA Daisuke <d.hatayama@...fujitsu.com>, keescook@...omium.org,
        kernel-hardening@...ts.openwall.com, surovegin@...gle.com,
        x86@...nel.org, kexec@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] kdump, vmcoreinfo: report memory sections virtual
 addresses

Hi Thomas,

I used below code and it works. Since using VMCOREINFO_NUMBER can reuse
the existing struct number_table to import the data. It makes change
easier. But the place could be next to KERNEL_IMAGE_SIZE, or as your
patch did, both is fine.

---
 kernel/kexec_core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 5616755..81bde86 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -1469,6 +1469,9 @@ static int __init crash_save_vmcoreinfo_init(void)
 	VMCOREINFO_NUMBER(PAGE_BUDDY_MAPCOUNT_VALUE);
 #ifdef CONFIG_X86
 	VMCOREINFO_NUMBER(KERNEL_IMAGE_SIZE);
+	VMCOREINFO_NUMBER(PAGE_OFFSET);
+	VMCOREINFO_NUMBER(VMALLOC_START);
+	VMCOREINFO_NUMBER(VMEMMAP_START);
 #endif
 #ifdef CONFIG_HUGETLB_PAGE
 	VMCOREINFO_NUMBER(HUGETLB_PAGE_DTOR);
-- 
2.5.5

On 08/18/16 at 07:47am, Thomas Garnier wrote:
> KASLR memory randomization can randomize the base of the physical memory
> mapping (PAGE_OFFSET), vmalloc (VMALLOC_START) and vmemmap
> (VMEMMAP_START). Adding these variables on VMCOREINFO so tools can
> easily identify the base of each memory section.
> 
> Signed-off-by: Thomas Garnier <thgarnie@...gle.com>
> ---
> Based on next-20160817
> ---
>  arch/x86/kernel/machine_kexec_64.c | 3 +++
>  include/linux/kexec.h              | 6 ++++++
>  2 files changed, 9 insertions(+)
> 
> diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
> index fc3389f..b1f15a2 100644
> --- a/arch/x86/kernel/machine_kexec_64.c
> +++ b/arch/x86/kernel/machine_kexec_64.c
> @@ -338,6 +338,9 @@ void arch_crash_save_vmcoreinfo(void)
>  	vmcoreinfo_append_str("KERNELOFFSET=%lx\n",
>  			      kaslr_offset());
>  	VMCOREINFO_PHYS_BASE(phys_base);
> +	VMCOREINFO_PAGE_OFFSET(PAGE_OFFSET);
> +	VMCOREINFO_VMALLOC_START(VMALLOC_START);
> +	VMCOREINFO_VMEMMAP_START(VMEMMAP_START);
>  }
>  
>  /* arch-dependent functionality related to kexec file-based syscall */
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index d3ae429..cd3874c 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -261,6 +261,12 @@ phys_addr_t paddr_vmcoreinfo_note(void);
>  	vmcoreinfo_append_str("CONFIG_%s=y\n", #name)
>  #define VMCOREINFO_PHYS_BASE(value) \
>  	vmcoreinfo_append_str("PHYS_BASE=%lx\n", (unsigned long)value)
> +#define VMCOREINFO_PAGE_OFFSET(value) \
> +	vmcoreinfo_append_str("PAGE_OFFSET=%lx\n", (unsigned long)value)
> +#define VMCOREINFO_VMALLOC_START(value) \
> +	vmcoreinfo_append_str("VMALLOC_START=%lx\n", (unsigned long)value)
> +#define VMCOREINFO_VMEMMAP_START(value) \
> +	vmcoreinfo_append_str("VMEMMAP_START=%lx\n", (unsigned long)value)
>  
>  extern struct kimage *kexec_image;
>  extern struct kimage *kexec_crash_image;
> -- 
> 2.8.0.rc3.226.g39d4020
> 
> 
> _______________________________________________
> kexec mailing list
> kexec@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec
