Add cros_debug option to crossystem

host/lib/crossystem.c

 /* Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include <stdio.h>
 #include <string.h>
 
 #include "host_common.h"
 
@@ skipping 36 matching lines @@
 /* Recovery caused by OS kernel failed signature check */
 #define BINF0_RECOVERY_BAD_OS          7
 /* Recovery initiated by OS */
 #define BINF0_RECOVERY_OS_INITIATED    8
 /* OS-initiated S3 diagnostic path (debug mode boot) */
 #define BINF0_S3_DIAGNOSTIC_PATH       9
 /* S3 resume failed */
 #define BINF0_S3_RESUME_FAILED        10
 /* Recovery caused by TPM error */
 #define BINF0_RECOVERY_TPM_ERROR      11
+/* Firmware types from BINF.3 */
+#define BINF3_RECOVERY   0
+#define BINF3_NORMAL     1
+#define BINF3_DEVELOPER  2
 
 /* Base name for ACPI files */
 #define ACPI_BASE_PATH "/sys/devices/platform/chromeos_acpi"
 /* Paths for frequently used ACPI files */
 #define ACPI_BINF_PATH ACPI_BASE_PATH "/BINF"
 #define ACPI_CHNV_PATH ACPI_BASE_PATH "/CHNV"
 #define ACPI_CHSW_PATH ACPI_BASE_PATH "/CHSW"
 #define ACPI_FMAP_PATH ACPI_BASE_PATH "/FMAP"
 #define ACPI_GPIO_PATH ACPI_BASE_PATH "/GPIO"
 #define ACPI_VBNV_PATH ACPI_BASE_PATH "/VBNV"
 
 /* Base name for GPIO files */
 #define GPIO_BASE_PATH "/sys/class/gpio"
 #define GPIO_EXPORT_PATH GPIO_BASE_PATH "/export"
 
-/* Base name for NVRAM file */
+/* Filename for NVRAM file */
 #define NVRAM_PATH "/dev/nvram"
 
+/* Filename for kernel command line */
+#define KERNEL_CMDLINE_PATH "/proc/cmdline"
+
 
 /* Copy up to dest_size-1 characters from src to dest, ensuring null
    termination (which strncpy() doesn't do).  Returns the destination
    string. */
 char* StrCopy(char* dest, const char* src, int dest_size) {
   strncpy(dest, src, dest_size);
   dest[dest_size - 1] = '\0';
   return dest;
 }
 
@@ skipping 322 matching lines @@
 }
 
 
 /* Read the active main firmware type into the destination buffer.
  * Passed the destination and its size.  Returns the destination, or
  * NULL if error. */
 const char* VbReadMainFwType(char* dest, int size) {
 
   /* Try reading type from BINF.3 */
   switch(ReadFileInt(ACPI_BINF_PATH ".3")) {
-    case 0:
+    case BINF3_RECOVERY:
       return StrCopy(dest, "recovery", size);
-    case 1:
+    case BINF3_NORMAL:
       return StrCopy(dest, "normal", size);
-    case 2:
+    case BINF3_DEVELOPER:
       return StrCopy(dest, "developer", size);
     default:
       break;  /* Fall through to legacy handling */
   }
 
   /* Fall back to BINF.0 for legacy systems like Mario. */
   switch(ReadFileInt(ACPI_BINF_PATH ".0")) {
     case -1:
       /* Both BINF.0 and BINF.3 are missing, so this isn't Chrome OS
        * firmware. */
@@ skipping 11 matching lines @@
     case BINF0_RECOVERY_TPM_ERROR:
       /* Assorted flavors of recovery boot reason. */
       return StrCopy(dest, "recovery", size);
     default:
       /* Other values don't map cleanly to firmware type. */
       return NULL;
   }
 }
 
 
+/* Determine whether OS-level debugging should be allowed.  Passed the
+ * destination and its size.  Returns 1 if yes, 0 if no, -1 if error. */
+int VbGetCrosDebug(void) {
+  FILE* f = NULL;
+  char buf[4096] = "";
+  int binf3;
+  char *t, *saveptr;
+
+  /* Try reading firmware type from BINF.3. */
+  binf3 = ReadFileInt(ACPI_BINF_PATH ".3");
+  if (BINF3_RECOVERY == binf3)
+    return 0;  /* Recovery mode never allows debug. */
+  else if (BINF3_DEVELOPER == binf3)
+    return 1;  /* Developer firmware always allows debug. */
+
+  /* Normal new firmware, older ChromeOS firmware, or non-Chrome firmware.
+   * For all these cases, check /proc/cmdline for cros_debug. */
+  f = fopen(KERNEL_CMDLINE_PATH, "rt");
+  if (f) {
+    if (NULL == fgets(buf, sizeof(buf), f))
+      *buf = 0;
+    fclose(f);
+  }
+  for (t = strtok_r(buf, " ", &saveptr); t; t=strtok_r(NULL, " ", &saveptr)) {
+    if (0 == strcmp(t, "cros_debug"))
+      return 1;
+  }
+
+  /* Normal new firmware or older Chrome OS firmware allows debug if the
+   * dev switch is on. */
+  if (1 == ReadFileBit(ACPI_CHSW_PATH, CHSW_DEV_BOOT))
+    return 1;
+
+  /* All other cases disallow debug. */
+  return 0;
+}
+
 
 /* Read a system property integer.
  *
  * Returns the property value, or -1 if error. */
 int VbGetSystemPropertyInt(const char* name) {
   int value = -1;
 
   /* Switch positions */
   if (!strcasecmp(name,"devsw_cur")) {
     value = ReadGpio(GPIO_SIGNAL_TYPE_DEV);
@@ skipping 42 matching lines @@
   } else if (!strcasecmp(name,"fwb_tries")) {
     value = VbGetNvStorage(VBNV_TRY_B_COUNT);
     if (-1 == value)
       value = VbGetCmosRebootField(CMOSRF_TRY_B);
   }
   /* Other parameters */
   else if (!strcasecmp(name,"recovery_reason")) {
     return VbGetRecoveryReason();
   } else if (!strcasecmp(name,"fmap_base")) {
     value = ReadFileInt(ACPI_FMAP_PATH);
+  } else if (!strcasecmp(name,"cros_debug")) {
+    value = VbGetCrosDebug();
   }
 
   return value;
 }
 
 
 /* Read a system property string into a destination buffer of the specified
  * size.
  *
  * Returns the passed buffer, or NULL if error. */
@@ skipping 74 matching lines @@
 
 
 /* Set a system property string.
  *
  * Returns 0 if success, -1 if error. */
 int VbSetSystemPropertyString(const char* name, const char* value) {
 
   /* TODO: support setting */
   return -1;
 }