Messages in this thread | | | From | Kees Cook <> | Date | Thu, 3 Aug 2017 15:40:35 -0700 | Subject | Re: [PATCH] x86/boot/KASLR: Extend movable_node option for KASLR |
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On Thu, Aug 3, 2017 at 5:17 AM, Dou Liyang <douly.fnst@cn.fujitsu.com> wrote: > movable_node is a boot-time switch to make hot-pluggable memory > NUMA nodes to be movable. This option is based on an assumption > that any node which the kernel resides in is defined as > un-hotpluggable. Linux can allocates memory near the kernel image > to try the best to keep the kernel away from hotpluggable memory > in the same NUMA node. So other nodes can be movable. > > But, KASLR doesn't know which node is un-hotpluggable, the all > hotpluggable memory ranges is recorded in ACPI SRAT table, SRAT > is not parsed. So, KASLR may randomize the kernel in a movable > node which will be immovable. > > Extend movable_node option to restrict kernel to be randomized in > immovable nodes by adding a parameter. this parameter sets up > the boundaries between the movable nodes and immovable nodes. > > Reported-by: Chao Fan <fanc.fnst@cn.fujitsu.com> > Signed-off-by: Dou Liyang <douly.fnst@cn.fujitsu.com>
This seems reasonable to me. Thanks for the fix!
Reviewed-by: Kees Cook <keescook@chromium.org>
> --- > Documentation/admin-guide/kernel-parameters.txt | 11 +++++++++-- > arch/x86/boot/compressed/kaslr.c | 19 ++++++++++++++++--- > 2 files changed, 25 insertions(+), 5 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index d9c171c..44c7e33 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -2305,7 +2305,8 @@ > mousedev.yres= [MOUSE] Vertical screen resolution, used for devices > reporting absolute coordinates, such as tablets > > - movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter > + movablecore=nn[KMG] > + [KNL,X86,IA-64,PPC] This parameter > is similar to kernelcore except it specifies the > amount of memory used for migratable allocations. > If both kernelcore and movablecore is specified, > @@ -2315,12 +2316,18 @@ > that the amount of memory usable for all allocations > is not too small. > > - movable_node [KNL] Boot-time switch to make hotplugable memory > + movable_node [KNL] Boot-time switch to make hot-pluggable memory > NUMA nodes to be movable. This means that the memory > of such nodes will be usable only for movable > allocations which rules out almost all kernel > allocations. Use with caution! > > + movable_node=nn[KMG] > + [KNL] Extend movable_node to work well with KASLR. This > + parameter is the boundaries between the movable nodes > + and immovable nodes, the memory which exceeds it will > + be regarded as hot-pluggable. > + > MTD_Partition= [MTD] > Format: <name>,<region-number>,<size>,<offset> > > diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c > index 91f27ab..7e2351b 100644 > --- a/arch/x86/boot/compressed/kaslr.c > +++ b/arch/x86/boot/compressed/kaslr.c > @@ -89,7 +89,10 @@ struct mem_vector { > static bool memmap_too_large; > > > -/* Store memory limit specified by "mem=nn[KMG]" or "memmap=nn[KMG]" */ > +/* > + * Store memory limit specified by the following situations: > + * "mem=nn[KMG]" or "memmap=nn[KMG]" or "movable_node=nn[KMG]" > + */ > unsigned long long mem_limit = ULLONG_MAX; > > > @@ -212,7 +215,8 @@ static int handle_mem_memmap(void) > char *param, *val; > u64 mem_size; > > - if (!strstr(args, "memmap=") && !strstr(args, "mem=")) > + if (!strstr(args, "memmap=") && !strstr(args, "mem=") && > + !strstr(args, "movable_node=")) > return 0; > > tmp_cmdline = malloc(len + 1); > @@ -247,7 +251,16 @@ static int handle_mem_memmap(void) > free(tmp_cmdline); > return -EINVAL; > } > - mem_limit = mem_size; > + mem_limit = mem_limit > mem_size ? mem_size : mem_limit; > + } else if (!strcmp(param, "movable_node")) { > + char *p = val; > + > + mem_size = memparse(p, &p); > + if (mem_size == 0) { > + free(tmp_cmdline); > + return -EINVAL; > + } > + mem_limit = mem_limit > mem_size ? mem_size : mem_limit; > } > } > > -- > 2.5.5 > > >
-- Kees Cook Pixel Security
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