arm: omap-common: secure ROM signature verify API

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>
Reviewed-by: Tom Rini <trini@konsulko.com>

diff --git a/arch/arm/cpu/armv7/omap-common/sec-common.c b/arch/arm/cpu/armv7/omap-common/sec-common.c
index 4ec736f5dbd1d897d4ef15434f6a30f67e0863fb..246a2393dab6d4791f9ee2976f26cb2fa2203196 100644 (file)
--- a/arch/arm/cpu/armv7/omap-common/sec-common.c
+++ b/arch/arm/cpu/armv7/omap-common/sec-common.c
@@ -17,6 +17,11 @@
 #include <asm/arch/sys_proto.h>
 #include <asm/omap_common.h>
 #include <asm/omap_sec_common.h>
+#include <asm/spl.h>
+#include <spl.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);
 
@@ -49,3 +54,86 @@ 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 (!IS_ALIGNED(cert_addr, 4)) {
+               printf("Image is not 4-byte aligned!\n");
+               result = 1;
+               goto auth_exit;
+       }
+
+       /* Image size also should be multiple of 4 */
+       if (!IS_ALIGNED(cert_size, 4)) {
+               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();
+       }
+
+       /*
+        * Output notification of successful authentication as well the name of
+        * the signing certificate used to re-assure the user that the secure
+        * code is being processed as expected. However suppress any such log
+        * output in case of building for SPL and booting via YMODEM. This is
+        * done to avoid disturbing the YMODEM serial protocol transactions.
+        */
+       if (!(IS_ENABLED(CONFIG_SPL_BUILD) &&
+             IS_ENABLED(CONFIG_SPL_YMODEM_SUPPORT) &&
+             spl_boot_device() == BOOT_DEVICE_UART))
+               printf("Authentication passed: %s\n", (char *)sig_addr);
+
+       return result;
+}

diff --git a/arch/arm/include/asm/omap_sec_common.h b/arch/arm/include/asm/omap_sec_common.h
index 1f50f83ac5e4fb453ffeb7cc07791b2be8cd4319..842f2af8d121af42d306a14613507fbac156b41f 100644 (file)
--- a/arch/arm/include/asm/omap_sec_common.h
+++ b/arch/arm/include/asm/omap_sec_common.h
@@ -18,4 +18,13 @@
  */
 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);
+
 #endif /* _OMAP_SEC_COMMON_H_ */