arch/arm/mach-omap2/sec-common.c

   1 /*
   2  *
   3  * Common security related functions for OMAP devices
   4  *
   5  * (C) Copyright 2016
   6  * Texas Instruments, <www.ti.com>
   7  *
   8  * Daniel Allred <d-allred@ti.com>
   9  * Andreas Dannenberg <dannenberg@ti.com>
  10  *
  11  * SPDX-License-Identifier: GPL-2.0+
  12  */
  13
  14 #include <common.h>
  15 #include <stdarg.h>
  16
  17 #include <asm/arch/sys_proto.h>
  18 #include <asm/omap_common.h>
  19 #include <asm/omap_sec_common.h>
  20 #include <asm/spl.h>
  21 #include <spl.h>
  22
  23 /* Index for signature verify ROM API */
  24 #ifdef CONFIG_AM33XX
  25 #define API_HAL_KM_VERIFYCERTIFICATESIGNATURE_INDEX     (0x0000000C)
  26 #else
  27 #define API_HAL_KM_VERIFYCERTIFICATESIGNATURE_INDEX     (0x0000000E)
  28 #endif
  29
  30 static uint32_t secure_rom_call_args[5] __aligned(ARCH_DMA_MINALIGN);
  31
  32 u32 secure_rom_call(u32 service, u32 proc_id, u32 flag, ...)
  33 {
  34         int i;
  35         u32 num_args;
  36         va_list ap;
  37
  38         va_start(ap, flag);
  39
  40         num_args = va_arg(ap, u32);
  41
  42         if (num_args > 4)
  43                 return 1;
  44
  45         /* Copy args to aligned args structure */
  46         for (i = 0; i < num_args; i++)
  47                 secure_rom_call_args[i + 1] = va_arg(ap, u32);
  48
  49         secure_rom_call_args[0] = num_args;
  50
  51         va_end(ap);
  52
  53         /* if data cache is enabled, flush the aligned args structure */
  54         flush_dcache_range(
  55                 (unsigned int)&secure_rom_call_args[0],
  56                 (unsigned int)&secure_rom_call_args[0] +
  57                 roundup(sizeof(secure_rom_call_args), ARCH_DMA_MINALIGN));
  58
  59         return omap_smc_sec(service, proc_id, flag, secure_rom_call_args);
  60 }
  61
  62 static u32 find_sig_start(char *image, size_t size)
  63 {
  64         char *image_end = image + size;
  65         char *sig_start_magic = "CERT_";
  66         int magic_str_len = strlen(sig_start_magic);
  67         char *ch;
  68
  69         while (--image_end > image) {
  70                 if (*image_end == '_') {
  71                         ch = image_end - magic_str_len + 1;
  72                         if (!strncmp(ch, sig_start_magic, magic_str_len))
  73                                 return (u32)ch;
  74                 }
  75         }
  76         return 0;
  77 }
  78
  79 int secure_boot_verify_image(void **image, size_t *size)
  80 {
  81         int result = 1;
  82         u32 cert_addr, sig_addr;
  83         size_t cert_size;
  84
  85         /* Perform cache writeback on input buffer */
  86         flush_dcache_range(
  87                 (u32)*image,
  88                 (u32)*image + roundup(*size, ARCH_DMA_MINALIGN));
  89
  90         cert_addr = (uint32_t)*image;
  91         sig_addr = find_sig_start((char *)*image, *size);
  92
  93         if (sig_addr == 0) {
  94                 printf("No signature found in image!\n");
  95                 result = 1;
  96                 goto auth_exit;
  97         }
  98
  99         *size = sig_addr - cert_addr;   /* Subtract out the signature size */
 100         cert_size = *size;
 101
 102         /* Check if image load address is 32-bit aligned */
 103         if (!IS_ALIGNED(cert_addr, 4)) {
 104                 printf("Image is not 4-byte aligned!\n");
 105                 result = 1;
 106                 goto auth_exit;
 107         }
 108
 109         /* Image size also should be multiple of 4 */
 110         if (!IS_ALIGNED(cert_size, 4)) {
 111                 printf("Image size is not 4-byte aligned!\n");
 112                 result = 1;
 113                 goto auth_exit;
 114         }
 115
 116         /* Call ROM HAL API to verify certificate signature */
 117         debug("%s: load_addr = %x, size = %x, sig_addr = %x\n", __func__,
 118               cert_addr, cert_size, sig_addr);
 119
 120         result = secure_rom_call(
 121                 API_HAL_KM_VERIFYCERTIFICATESIGNATURE_INDEX, 0, 0,
 122                 4, cert_addr, cert_size, sig_addr, 0xFFFFFFFF);
 123 auth_exit:
 124         if (result != 0) {
 125                 printf("Authentication failed!\n");
 126                 printf("Return Value = %08X\n", result);
 127                 hang();
 128         }
 129
 130         /*
 131          * Output notification of successful authentication as well the name of
 132          * the signing certificate used to re-assure the user that the secure
 133          * code is being processed as expected. However suppress any such log
 134          * output in case of building for SPL and booting via YMODEM. This is
 135          * done to avoid disturbing the YMODEM serial protocol transactions.
 136          */
 137         if (!(IS_ENABLED(CONFIG_SPL_BUILD) &&
 138               IS_ENABLED(CONFIG_SPL_YMODEM_SUPPORT) &&
 139               spl_boot_device() == BOOT_DEVICE_UART))
 140                 printf("Authentication passed: %s\n", (char *)sig_addr);
 141
 142         return result;
 143 }