Adds an API that verifies a signature attached to an image (binary blob). This API is basically a entry to a secure ROM service provided by the device and accessed via an SMC call, using a particular calling convention.
Signed-off-by: Daniel Allred d-allred@ti.com Signed-off-by: Andreas Dannenberg dannenberg@ti.com --- arch/arm/cpu/armv7/omap-common/sec-common.c | 76 +++++++++++++++++++++++++++++ arch/arm/include/asm/omap_common.h | 9 ++++ 2 files changed, 85 insertions(+)
diff --git a/arch/arm/cpu/armv7/omap-common/sec-common.c b/arch/arm/cpu/armv7/omap-common/sec-common.c index b9c0a42..dbb9078 100644 --- a/arch/arm/cpu/armv7/omap-common/sec-common.c +++ b/arch/arm/cpu/armv7/omap-common/sec-common.c @@ -16,6 +16,9 @@ #include <asm/arch/sys_proto.h> #include <asm/omap_common.h>
+/* Index for signature verify ROM API */ +#define API_HAL_KM_VERIFYCERTIFICATESIGNATURE_INDEX (0x0000000E) + static uint32_t secure_rom_call_args[5] __aligned(ARCH_DMA_MINALIGN);
u32 secure_rom_call(u32 service, u32 proc_id, u32 flag, ...) @@ -47,3 +50,76 @@ u32 secure_rom_call(u32 service, u32 proc_id, u32 flag, ...)
return omap_smc_sec(service, proc_id, flag, secure_rom_call_args); } + +static u32 find_sig_start(char *image, size_t size) +{ + char *image_end = image + size; + char *sig_start_magic = "CERT_"; + int magic_str_len = strlen(sig_start_magic); + char *ch; + + while (--image_end > image) { + if (*image_end == '_') { + ch = image_end - magic_str_len + 1; + if (!strncmp(ch, sig_start_magic, magic_str_len)) + return (u32)ch; + } + } + return 0; +} + +int secure_boot_verify_image(void **image, size_t *size) +{ + int result = 1; + u32 cert_addr, sig_addr; + size_t cert_size; + + /* Perform cache writeback on input buffer */ + flush_dcache_range( + (u32)*image, + (u32)*image + roundup(*size, ARCH_DMA_MINALIGN)); + + cert_addr = (uint32_t)*image; + sig_addr = find_sig_start((char *)*image, *size); + + if (sig_addr == 0) { + printf("No signature found in image.\n"); + result = 1; + goto auth_exit; + } + + *size = sig_addr - cert_addr; /* Subtract out the signature size */ + cert_size = *size; + + /* Check if image load address is 32-bit aligned */ + if (0 != (0x3 & cert_addr)) { + printf("Image is not 4-byte aligned.\n"); + result = 1; + goto auth_exit; + } + + /* Image size also should be multiple of 4 */ + if (0 != (0x3 & cert_size)) { + printf("Image size is not 4-byte aligned.\n"); + result = 1; + goto auth_exit; + } + + /* Call ROM HAL API to verify certificate signature */ + debug("%s: load_addr = %x, size = %x, sig_addr = %x\n", __func__, + cert_addr, cert_size, sig_addr); + + result = secure_rom_call( + API_HAL_KM_VERIFYCERTIFICATESIGNATURE_INDEX, 0, 0, + 4, cert_addr, cert_size, sig_addr, 0xFFFFFFFF); +auth_exit: + if (result != 0) { + printf("Authentication failed!\n"); + printf("Return Value = %08X\n", result); + hang(); + } + + printf("Authentication passed: %s\n", (char *)sig_addr); + + return result; +} diff --git a/arch/arm/include/asm/omap_common.h b/arch/arm/include/asm/omap_common.h index 293fc72..8887335 100644 --- a/arch/arm/include/asm/omap_common.h +++ b/arch/arm/include/asm/omap_common.h @@ -640,6 +640,15 @@ u32 omap_smc_sec(u32 service, u32 proc_id, u32 flag, u32 *params); */ u32 secure_rom_call(u32 service, u32 proc_id, u32 flag, ...);
+/* + * Invoke a secure ROM API on high-secure (HS) device variants that can be used + * to verify a secure blob by authenticating and optionally decrypting it. The + * exact operation performed depends on how the certificate that was embedded + * into the blob during the signing/encryption step when the secure blob was + * first created. + */ +int secure_boot_verify_image(void **p_image, size_t *p_size); + void enable_edma3_clocks(void); void disable_edma3_clocks(void);