src/security/vboot/misc.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2
   3 #ifndef __VBOOT_MISC_H__
   4 #define __VBOOT_MISC_H__
   5
   6 #include <assert.h>
   7 #include <security/vboot/vboot_common.h>
   8 #include <vb2_api.h>
   9
  10 /*
  11  * Source: security/vboot/common.c
  12  */
  13 struct vb2_context *vboot_get_context(void);
  14
  15 /*
  16  * Returns 1 if firmware slot A is used, 0 if slot B is used.
  17  */
  18 static inline int vboot_is_firmware_slot_a(struct vb2_context *ctx)
  19 {
  20         return !(ctx->flags & VB2_CONTEXT_FW_SLOT_B);
  21 }
  22
  23 /*
  24  * Check if given flag is set in the flags field in GBB header.
  25  */
  26 static inline bool vboot_is_gbb_flag_set(enum vb2_gbb_flag flag)
  27 {
  28         return !!(vb2api_gbb_get_flags(vboot_get_context()) & flag);
  29 }
  30
  31 /*
  32  * Locates firmware as a region device. Returns 0 on success, -1 on failure.
  33  */
  34 int vboot_locate_firmware(struct vb2_context *ctx, struct region_device *fw);
  35
  36 /*
  37  * The stage loading code is compiled and entered from multiple stages. The
  38  * helper functions below attempt to provide more clarity on when certain
  39  * code should be called. They are implemented inline for better compile-time
  40  * code elimination.
  41  */
  42
  43 static inline int verification_should_run(void)
  44 {
  45         if (CONFIG(VBOOT_SEPARATE_VERSTAGE))
  46                 return ENV_SEPARATE_VERSTAGE;
  47         else if (CONFIG(VBOOT_STARTS_IN_ROMSTAGE))
  48                 return ENV_RAMINIT;
  49         else if (CONFIG(VBOOT_STARTS_IN_BOOTBLOCK))
  50                 return ENV_BOOTBLOCK;
  51         else
  52                 dead_code();
  53 }
  54
  55 static inline int verstage_should_load(void)
  56 {
  57         if (CONFIG(VBOOT_SEPARATE_VERSTAGE) && !CONFIG(VBOOT_STARTS_BEFORE_BOOTBLOCK))
  58                 return ENV_BOOTBLOCK;
  59         else
  60                 return 0;
  61 }
  62
  63 static inline int vboot_logic_executed(void)
  64 {
  65         extern int vboot_executed;      /* should not be globally accessible */
  66
  67         /* If we are in the stage that runs verification, or in the stage that
  68            both loads the verstage and is returned to from it afterwards, we
  69            need to check a global to see if verification has run. */
  70         if (verification_should_run() ||
  71             (verstage_should_load() && CONFIG(VBOOT_RETURN_FROM_VERSTAGE)))
  72                 return vboot_executed;
  73
  74         if (CONFIG(VBOOT_STARTS_IN_BOOTBLOCK)) {
  75                 /* All other stages are "after the bootblock" */
  76                 return !ENV_BOOTBLOCK;
  77         } else if (CONFIG(VBOOT_STARTS_IN_ROMSTAGE)) {
  78                 /* Post-RAM stages are "after the romstage" */
  79                 return !ENV_ROMSTAGE_OR_BEFORE;
  80         } else if (CONFIG(VBOOT_STARTS_BEFORE_BOOTBLOCK)) {
  81                 return !ENV_SEPARATE_VERSTAGE;
  82         } else {
  83                 dead_code();
  84         }
  85 }
  86
  87 static inline bool vboot_hwcrypto_allowed(void)
  88 {
  89         /* When not using vboot firmware verification, HW crypto is always allowed. */
  90         if (!CONFIG(VBOOT))
  91                 return 1;
  92
  93         /* Before vboot runs we can't check for HW crypto, so err on the side of caution. */
  94         if (!vboot_logic_executed())
  95                 return 0;
  96
  97         /* Otherwise, vboot can decide. */
  98         return vb2api_hwcrypto_allowed(vboot_get_context());
  99 }
 100
 101 #endif /* __VBOOT_MISC_H__ */