common/encrypt: create named variables for UAPI constants

Use named variables rather than hard-coded numbers + comments.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>

diff --git a/common/encrypt b/common/encrypt
index 90f931fce830fa644f12200f5d124588a1bc1e49..b967c65a26f6598d8561fecb4a3abe6c49964868 100644 (file)
--- a/common/encrypt
+++ b/common/encrypt
@@ -664,16 +664,26 @@ _do_verify_ciphertext_for_encryption_policy()
        done
 }
 
+# fscrypt UAPI constants (see <linux/fscrypt.h>)
+
+FSCRYPT_MODE_AES_256_XTS=1
+FSCRYPT_MODE_AES_256_CTS=4
+FSCRYPT_MODE_AES_128_CBC=5
+FSCRYPT_MODE_AES_128_CTS=6
+FSCRYPT_MODE_ADIANTUM=9
+
+FSCRYPT_POLICY_FLAG_DIRECT_KEY=0x04
+
 _fscrypt_mode_name_to_num()
 {
        local name=$1
 
        case "$name" in
-       AES-256-XTS)            echo 1 ;; # FS_ENCRYPTION_MODE_AES_256_XTS
-       AES-256-CTS-CBC)        echo 4 ;; # FS_ENCRYPTION_MODE_AES_256_CTS
-       AES-128-CBC-ESSIV)      echo 5 ;; # FS_ENCRYPTION_MODE_AES_128_CBC
-       AES-128-CTS-CBC)        echo 6 ;; # FS_ENCRYPTION_MODE_AES_128_CTS
-       Adiantum)               echo 9 ;; # FS_ENCRYPTION_MODE_ADIANTUM
+       AES-256-XTS)            echo $FSCRYPT_MODE_AES_256_XTS ;;
+       AES-256-CTS-CBC)        echo $FSCRYPT_MODE_AES_256_CTS ;;
+       AES-128-CBC-ESSIV)      echo $FSCRYPT_MODE_AES_128_CBC ;;
+       AES-128-CTS-CBC)        echo $FSCRYPT_MODE_AES_128_CTS ;;
+       Adiantum)               echo $FSCRYPT_MODE_ADIANTUM ;;
        *)                      _fail "Unknown fscrypt mode: $name" ;;
        esac
 }
@@ -705,7 +715,7 @@ _verify_ciphertext_for_encryption_policy()
                             $filenames_encryption_mode ]; then
                                _fail "For direct key mode, contents and filenames modes must match"
                        fi
-                       (( policy_flags |= 0x04 )) # FS_POLICY_FLAG_DIRECT_KEY
+                       (( policy_flags |= FSCRYPT_POLICY_FLAG_DIRECT_KEY ))
                        ;;
                *)
                        _fail "Unknown option '$opt' passed to ${FUNCNAME[0]}"
@@ -721,11 +731,11 @@ _verify_ciphertext_for_encryption_policy()
        if (( policy_version > 1 )); then
                set_encpolicy_args+=" -v 2"
                crypt_util_args+=" --kdf=HKDF-SHA512"
-               if (( policy_flags & 0x04 )); then
+               if (( policy_flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY )); then
                        crypt_util_args+=" --mode-num=$contents_mode_num"
                fi
        else
-               if (( policy_flags & 0x04 )); then
+               if (( policy_flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY )); then
                        crypt_util_args+=" --kdf=none"
                else
                        crypt_util_args+=" --kdf=AES-128-ECB"