On 07/05/17 at 03:08pm, Kees Cook wrote: > On Wed, Jul 5, 2017 at 1:06 AM, Baoquan He <b...@redhat.com> wrote: > > Kernel text may be located in non-mirror regions (movable zone) when both > > address range mirroring feature and KASLR are enabled. > > > > The address range mirroring feature arranges such mirror region into > > normal zone and other region into movable zone in order to locate > > kernel code and data in mirror region. The physical memory region > > whose descriptors in EFI memory map has EFI_MEMORY_MORE_RELIABLE > > attribute (bit: 16) are mirrored. > > > > If efi is detected, iterate efi memory map and pick the mirror region to > > process for adding candidate of randomization slot. If efi is disabled > > or no mirror region found, still process e820 memory map. > > > > Signed-off-by: Baoquan He <b...@redhat.com> > > --- > > arch/x86/boot/compressed/kaslr.c | 52 > > +++++++++++++++++++++++++++++++++++++++- > > 1 file changed, 51 insertions(+), 1 deletion(-) > > > > diff --git a/arch/x86/boot/compressed/kaslr.c > > b/arch/x86/boot/compressed/kaslr.c > > index 85c360eec4a6..94f08fd375ae 100644 > > --- a/arch/x86/boot/compressed/kaslr.c > > +++ b/arch/x86/boot/compressed/kaslr.c > > @@ -37,7 +37,9 @@ > > #include <linux/uts.h> > > #include <linux/utsname.h> > > #include <linux/ctype.h> > > +#include <linux/efi.h> > > #include <generated/utsrelease.h> > > +#include <asm/efi.h> > > > > /* Macros used by the included decompressor code below. */ > > #define STATIC > > @@ -558,6 +560,48 @@ static void process_mem_region(struct mem_vector > > *entry, > > } > > } > > > > +/* Marks if efi mirror regions have been found and handled. */ > > +static bool efi_mirror_found; > > + > > +static void process_efi_entry(unsigned long minimum, unsigned long > > image_size) > > Since this walks all entries (not a single entry), please name it > process_efi_entries() (or some other more clear name).
Thanks for your reviewing, Kees! Ok, will change. Since the e820 function was named as process_e820_entry, I just did similarly. It makes sense to change as you suggested, and the process_e820_entry too as you commented in v2 thread. Thanks Baoquan > > +{ > > + struct efi_info *e = &boot_params->efi_info; > > + struct mem_vector region; > > + efi_memory_desc_t *md; > > + unsigned long pmap; > > + char *signature; > > + u32 nr_desc; > > + int i; > > + > > + > > + signature = (char *)&boot_params->efi_info.efi_loader_signature; > > + if (strncmp(signature, EFI32_LOADER_SIGNATURE, 4) && > > + strncmp(signature, EFI64_LOADER_SIGNATURE, 4)) > > + return; > > + > > +#ifdef CONFIG_X86_32 > > + /* Can't handle data above 4GB at this time */ > > + if (e->efi_memmap_hi) { > > + warn("Memory map is above 4GB, EFI should be disabled.\n"); > > + return; > > + } > > + pmap = e->efi_memmap; > > +#else > > + pmap = (e->efi_memmap | ((__u64)e->efi_memmap_hi << 32)); > > +#endif > > + > > + nr_desc = e->efi_memmap_size / e->efi_memdesc_size; > > + for (i = 0; i < nr_desc; i++) { > > + md = (efi_memory_desc_t *)(pmap + (i * > > e->efi_memdesc_size)); > > + if (md->attribute & EFI_MEMORY_MORE_RELIABLE) { > > + region.start = md->phys_addr; > > + region.size = md->num_pages << EFI_PAGE_SHIFT; > > + process_mem_region(®ion, minimum, image_size); > > + efi_mirror_found = true; > > + } > > + } > > +} > > + > > static void process_e820_entry(unsigned long minimum, unsigned long > > image_size) > > { > > int i; > > @@ -592,6 +636,12 @@ static unsigned long find_random_phys_addr(unsigned > > long minimum, > > /* Make sure minimum is aligned. */ > > minimum = ALIGN(minimum, CONFIG_PHYSICAL_ALIGN); > > > > +#ifdef CONFIG_EFI > > + process_efi_entry(minimum, image_size); > > + if (efi_mirror_found) > > + return slots_fetch_random(); > > +#endif > > + > > process_e820_entry(minimum, image_size); > > return slots_fetch_random(); > > } > > @@ -651,7 +701,7 @@ void choose_random_location(unsigned long input, > > */ > > min_addr = min(*output, 512UL << 20); > > > > - /* Walk e820 and find a random address. */ > > + /* Walk available memory entries to find a random address. */ > > random_addr = find_random_phys_addr(min_addr, output_size); > > if (!random_addr) { > > warn("Physical KASLR disabled: no suitable memory region!"); > > -- > > 2.5.5 > > > > > > -- > Kees Cook > Pixel Security