9:34 p.m.
ACK
On 11/11/16 at 11:29am, Dave Young wrote:
>
> Backport upstream kexec-tools commit for correct kaslr page_offset value
> commit 9f62cbddddfc93d78d9aafbddf3e1208cb242f7b
> Author: Thomas Garnier <thgarnie(a)google.com>
> Date: Tue Sep 13 15:10:05 2016 +0800
>
> kexec/arch/i386: Add support for KASLR memory randomization
>
> Multiple changes were made on KASLR (right now in linux-next). One of
> them is randomizing the virtual address of the physical mapping, vmalloc
> and vmemmap memory sections. It breaks kdump ability to read physical
> memory.
>
> This change identifies if KASLR memories randomization is used by
> checking if the page_offset_base variable exists. It search for the
> correct PAGE_OFFSET value by looking at the loaded memory section and
> find the lowest aligned on PUD (the randomization level).
>
> Related commits on linux-next:
> - 0483e1fa6e09d4948272680f691dccb1edb9677f: Base for randomization
> - 021182e52fe01c1f7b126f97fd6ba048dc4234fd: Enable for PAGE_OFFSET
>
> Signed-off-by: Thomas Garnier <thgarnie(a)google.com>
> Signed-off-by: Simon Horman <horms(a)verge.net.au>
>
> Signed-off-by: Dave Young <dyoung(a)redhat.com>
> ---
> ...i386-Add-support-for-KASLR-memory-randomi.patch | 97 ++++++++++++++++++++++
> kexec-tools.spec | 2 +
> 2 files changed, 99 insertions(+)
> create mode 100644
kexec-tools-2.0.13-kexec-arch-i386-Add-support-for-KASLR-memory-randomi.patch
>
> diff --git
a/kexec-tools-2.0.13-kexec-arch-i386-Add-support-for-KASLR-memory-randomi.patch
b/kexec-tools-2.0.13-kexec-arch-i386-Add-support-for-KASLR-memory-randomi.patch
> new file mode 100644
> index 0000000..a5474cb
> --- /dev/null
> +++ b/kexec-tools-2.0.13-kexec-arch-i386-Add-support-for-KASLR-memory-randomi.patch
> @@ -0,0 +1,97 @@
> +From 9f62cbddddfc93d78d9aafbddf3e1208cb242f7b Mon Sep 17 00:00:00 2001
> +From: Thomas Garnier <thgarnie(a)google.com>
> +Date: Tue, 13 Sep 2016 15:10:05 +0800
> +Subject: [PATCH] kexec/arch/i386: Add support for KASLR memory randomization
> +
> +Multiple changes were made on KASLR (right now in linux-next). One of
> +them is randomizing the virtual address of the physical mapping, vmalloc
> +and vmemmap memory sections. It breaks kdump ability to read physical
> +memory.
> +
> +This change identifies if KASLR memories randomization is used by
> +checking if the page_offset_base variable exists. It search for the
> +correct PAGE_OFFSET value by looking at the loaded memory section and
> +find the lowest aligned on PUD (the randomization level).
> +
> +Related commits on linux-next:
> + - 0483e1fa6e09d4948272680f691dccb1edb9677f: Base for randomization
> + - 021182e52fe01c1f7b126f97fd6ba048dc4234fd: Enable for PAGE_OFFSET
> +
> +Signed-off-by: Thomas Garnier <thgarnie(a)google.com>
> +Signed-off-by: Simon Horman <horms(a)verge.net.au>
> +---
> + kexec/arch/i386/crashdump-x86.c | 29 ++++++++++++++++++++++-------
> + 1 file changed, 22 insertions(+), 7 deletions(-)
> +
> +diff --git a/kexec/arch/i386/crashdump-x86.c b/kexec/arch/i386/crashdump-x86.c
> +index bbc0f35..ab833d4 100644
> +--- a/kexec/arch/i386/crashdump-x86.c
> ++++ b/kexec/arch/i386/crashdump-x86.c
> +@@ -102,11 +102,10 @@ static int get_kernel_paddr(struct kexec_info *UNUSED(info),
> + return -1;
> + }
> +
> +-/* Retrieve kernel _stext symbol virtual address from /proc/kallsyms */
> +-static unsigned long long get_kernel_stext_sym(void)
> ++/* Retrieve kernel symbol virtual address from /proc/kallsyms */
> ++static unsigned long long get_kernel_sym(const char *symbol)
> + {
> + const char *kallsyms = "/proc/kallsyms";
> +- const char *stext = "_stext";
> + char sym[128];
> + char line[128];
> + FILE *fp;
> +@@ -122,13 +121,13 @@ static unsigned long long get_kernel_stext_sym(void)
> + while(fgets(line, sizeof(line), fp) != NULL) {
> + if (sscanf(line, "%Lx %c %s", &vaddr, &type, sym) != 3)
> + continue;
> +- if (strcmp(sym, stext) == 0) {
> +- dbgprintf("kernel symbol %s vaddr = %16llx\n", stext, vaddr);
> ++ if (strcmp(sym, symbol) == 0) {
> ++ dbgprintf("kernel symbol %s vaddr = %16llx\n", symbol, vaddr);
> + return vaddr;
> + }
> + }
> +
> +- fprintf(stderr, "Cannot get kernel %s symbol address\n", stext);
> ++ fprintf(stderr, "Cannot get kernel %s symbol address\n", symbol);
> + return 0;
> + }
> +
> +@@ -151,6 +150,8 @@ static int get_kernel_vaddr_and_size(struct kexec_info
*UNUSED(info),
> + off_t size;
> + uint32_t elf_flags = 0;
> + uint64_t stext_sym;
> ++ const unsigned long long pud_mask = ~((1 << 30) - 1);
> ++ unsigned long long vaddr, lowest_vaddr = 0;
> +
> + if (elf_info->machine != EM_X86_64)
> + return 0;
> +@@ -180,9 +181,23 @@ static int get_kernel_vaddr_and_size(struct kexec_info
*UNUSED(info),
> +
> + end_phdr = &ehdr.e_phdr[ehdr.e_phnum];
> +
> ++ /* Search for the real PAGE_OFFSET when KASLR memory randomization
> ++ * is enabled */
> ++ if (get_kernel_sym("page_offset_base") != 0) {
> ++ for(phdr = ehdr.e_phdr; phdr != end_phdr; phdr++) {
> ++ if (phdr->p_type == PT_LOAD) {
> ++ vaddr = phdr->p_vaddr & pud_mask;
> ++ if (lowest_vaddr == 0 || lowest_vaddr > vaddr)
> ++ lowest_vaddr = vaddr;
> ++ }
> ++ }
> ++ if (lowest_vaddr != 0)
> ++ elf_info->page_offset = lowest_vaddr;
> ++ }
> ++
> + /* Traverse through the Elf headers and find the region where
> + * _stext symbol is located in. That's where kernel is mapped */
> +- stext_sym = get_kernel_stext_sym();
> ++ stext_sym = get_kernel_sym("_stext");
> + for(phdr = ehdr.e_phdr; stext_sym && phdr != end_phdr; phdr++) {
> + if (phdr->p_type == PT_LOAD) {
> + unsigned long long saddr = phdr->p_vaddr;
> +--
> +2.10.1
> +
> diff --git a/kexec-tools.spec b/kexec-tools.spec
> index be98202..bf28938 100644
> --- a/kexec-tools.spec
> +++ b/kexec-tools.spec
> @@ -65,6 +65,7 @@ Obsoletes: diskdumputils netdump kexec-tools-eppic
> #
> # Patches 0 through 100 are meant for x86 kexec-tools enablement
> #
> +Patch1:
kexec-tools-2.0.13-kexec-arch-i386-Add-support-for-KASLR-memory-randomi.patch
>
> #
> # Patches 101 through 200 are meant for x86_64 kexec-tools enablement
> @@ -120,6 +121,7 @@ tar -z -x -v -f %{SOURCE9}
> tar -z -x -v -f %{SOURCE19}
> tar -z -x -v -f %{SOURCE23}
>
> +%patch1 -p1
> %patch500 -p1
> %patch501 -p1
> %patch502 -p1
> --
> 2.10.1
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