| Message ID | 1439273796-25359-5-git-send-email-jlee@suse.com (mailing list archive) |
|---|---|
| State | Changes Requested, archived |
| Headers | show |
On Tue, 11 Aug, at 02:16:24PM, Lee, Chun-Yi wrote: > This patch adds the codes for generating random number array as the > HMAC key that will used by later EFI stub codes. > > The original codes in efi_random copied from aslr and add the codes > to accept input entropy and EFI debugging. In later patch will add > the codes to get random number by EFI protocol. The separate codes > can avoid impacting aslr function. Is there some way we can share the code between aslr and the EFI boot stub? People may not review both files when making changes and so bug fixes to one might not appear in the other.
Hi Matt, Thanks for your reviewing and sorry for my delay. On Thu, Aug 20, 2015 at 03:12:21PM +0100, Matt Fleming wrote: > On Tue, 11 Aug, at 02:16:24PM, Lee, Chun-Yi wrote: > > This patch adds the codes for generating random number array as the > > HMAC key that will used by later EFI stub codes. > > > > The original codes in efi_random copied from aslr and add the codes > > to accept input entropy and EFI debugging. In later patch will add > > the codes to get random number by EFI protocol. The separate codes > > can avoid impacting aslr function. > > Is there some way we can share the code between aslr and the EFI boot > stub? People may not review both files when making changes and so bug > fixes to one might not appear in the other. > > -- > Matt Fleming, Intel Open Source Technology Center The origin design is base on get_random_long() from aslr, so I direct copy it to efi_random.c then modified it. There have some reasons I didn't share the code with aslr: - There have some debug_puttstr() for debugging in aslr, but those debugging log do not work in EFI stub, and I want put efi_print for debugging purpose. I don't want affect the code in aslr, so I choice copy get_random_long() to efi_random.c specific for EFI stub. - In subsequent patches add EFI random protocol support to get_random_longh(). In next version, I will try to extract shared code to misc.c to reuse them between aslr and efi_random. Thanks a lot! Joey Lee -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index 0a291cd..377245b 100644 --- a/arch/x86/boot/compressed/Makefile +++ b/arch/x86/boot/compressed/Makefile @@ -49,6 +49,7 @@ vmlinux-objs-$(CONFIG_RANDOMIZE_BASE) += $(obj)/aslr.o $(obj)/eboot.o: KBUILD_CFLAGS += -fshort-wchar -mno-red-zone +vmlinux-objs-$(CONFIG_HIBERNATE_VERIFICATION) += $(obj)/efi_random.o vmlinux-objs-$(CONFIG_EFI_STUB) += $(obj)/eboot.o $(obj)/efi_stub_$(BITS).o \ $(objtree)/drivers/firmware/efi/libstub/lib.a vmlinux-objs-$(CONFIG_EFI_MIXED) += $(obj)/efi_thunk_$(BITS).o diff --git a/arch/x86/boot/compressed/efi_random.c b/arch/x86/boot/compressed/efi_random.c new file mode 100644 index 0000000..a69352e --- /dev/null +++ b/arch/x86/boot/compressed/efi_random.c @@ -0,0 +1,80 @@ +#include "misc.h" + +#include <linux/efi.h> +#include <asm/archrandom.h> + +#define EDX_TSC (1 << 4) +#define ECX_RDRAND (1 << 30) + +static unsigned int cpuid_0x1_ecx, cpuid_0x1_edx; + +static void cpuid_ecx_edx(void) +{ + unsigned int eax, ebx; + + cpuid(0x1, &eax, &ebx, &cpuid_0x1_ecx, &cpuid_0x1_edx); +} + +static unsigned long get_random_long(unsigned long entropy, + struct boot_params *boot_params, + efi_system_table_t *sys_table) +{ +#ifdef CONFIG_X86_64 + const unsigned long mix_const = 0x5d6008cbf3848dd3UL; +#else + const unsigned long mix_const = 0x3f39e593UL; +#endif + unsigned long raw, random; + bool use_i8254 = true; + + if (entropy) + random = entropy; + else + random = get_random_boot(boot_params); + + if (cpuid_0x1_ecx & ECX_RDRAND) { + if (rdrand_long(&raw)) { + random ^= raw; + use_i8254 = false; + } + } + + if (cpuid_0x1_edx & EDX_TSC) { + rdtscll(raw); + + random ^= raw; + use_i8254 = false; + } + + if (use_i8254) + random ^= read_i8254(); + + /* Circular multiply for better bit diffusion */ + asm("mul %3" + : "=a" (random), "=d" (raw) + : "a" (random), "rm" (mix_const)); + random += raw; + + return random; +} + +void efi_get_random_key(efi_system_table_t *sys_table, + struct boot_params *params, u8 key[], unsigned int size) +{ + unsigned long entropy = 0; + unsigned int bfill = size; + + if (key == NULL || !size) + return; + + cpuid_ecx_edx(); + + memset(key, 0, size); + while (bfill > 0) { + unsigned int copy_len = 0; + entropy = get_random_long(entropy, params, sys_table); + copy_len = (bfill < sizeof(entropy)) ? bfill : sizeof(entropy); + memcpy((void *)(key + size - bfill), &entropy, copy_len); + bfill -= copy_len; + } +} diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c index 70acd7e..c8e2237 100644 --- a/arch/x86/boot/compressed/misc.c +++ b/arch/x86/boot/compressed/misc.c @@ -439,7 +439,7 @@ asmlinkage __visible void *decompress_kernel(void *rmode, memptr heap, return output; } -#if CONFIG_RANDOMIZE_BASE +#if CONFIG_HIBERNATE_VERIFICATION || CONFIG_RANDOMIZE_BASE #define I8254_PORT_CONTROL 0x43 #define I8254_PORT_COUNTER0 0x40 #define I8254_CMD_READBACK 0xC0 @@ -489,4 +489,4 @@ unsigned long get_random_boot(struct boot_params *boot_params) return hash; } -#endif /* CONFIG_RANDOMIZE_BASE */ +#endif /* CONFIG_HIBERNATE_VERIFICATION || CONFIG_RANDOMIZE_BASE */ diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h index 60e4893..3508a6e 100644 --- a/arch/x86/boot/compressed/misc.h +++ b/arch/x86/boot/compressed/misc.h @@ -53,7 +53,7 @@ int cmdline_find_option(const char *option, char *buffer, int bufsize); int cmdline_find_option_bool(const char *option); #endif -#if CONFIG_RANDOMIZE_BASE +#if CONFIG_HIBERNATE_VERIFICATION || CONFIG_RANDOMIZE_BASE extern u16 read_i8254(void); extern unsigned long get_random_boot(struct boot_params *boot_params); #endif