From: Eric Biggers <ebigg...@google.com>

Prefix all filesystem encryption UAPI constants except the ioctl numbers
with "FSCRYPT_" rather than with "FS_".  This namespaces the constants
more appropriately and makes it clear that they are related specifically
to the filesystem encryption feature, and to the 'fscrypt_*' structures.
With some of the old names like "FS_POLICY_FLAGS_VALID", it was not
immediately clear that the constant had anything to do with encryption.

This is also useful because we'll be adding more encryption-related
constants, e.g. for the policy version, and we'd otherwise have to
choose whether to use unclear names like FS_POLICY_VERSION_* or
inconsistent names like FS_ENCRYPTION_POLICY_VERSION_*.

For source compatibility with older userspace programs, keep the old
names defined as aliases to the new ones.  (It's debatable whether we
really need this, though; the filesystem encryption API is new enough
that most if not all programs that are using it have to declare it
themselves anyway.)

Signed-off-by: Eric Biggers <ebigg...@google.com>
---
 Documentation/filesystems/fscrypt.rst | 14 ++++-----
 include/uapi/linux/fscrypt.h          | 59 ++++++++++++++++++++++++-----------
 2 files changed, 47 insertions(+), 26 deletions(-)

diff --git a/Documentation/filesystems/fscrypt.rst 
b/Documentation/filesystems/fscrypt.rst
index 776ddc655f79..f12956f3f1f8 100644
--- a/Documentation/filesystems/fscrypt.rst
+++ b/Documentation/filesystems/fscrypt.rst
@@ -251,14 +251,14 @@ empty directory or verifies that a directory or regular 
file already
 has the specified encryption policy.  It takes in a pointer to a
 :c:type:`struct fscrypt_policy`, defined as follows::
 
-    #define FS_KEY_DESCRIPTOR_SIZE  8
+    #define FSCRYPT_KEY_DESCRIPTOR_SIZE  8
 
     struct fscrypt_policy {
             __u8 version;
             __u8 contents_encryption_mode;
             __u8 filenames_encryption_mode;
             __u8 flags;
-            __u8 master_key_descriptor[FS_KEY_DESCRIPTOR_SIZE];
+            __u8 master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
     };
 
 This structure must be initialized as follows:
@@ -274,7 +274,7 @@ This structure must be initialized as follows:
 
 - ``flags`` must be set to a value from ``<linux/fs.h>`` which
   identifies the amount of NUL-padding to use when encrypting
-  filenames.  If unsure, use FS_POLICY_FLAGS_PAD_32 (0x3).
+  filenames.  If unsure, use FSCRYPT_POLICY_FLAGS_PAD_32 (0x3).
 
 - ``master_key_descriptor`` specifies how to find the master key in
   the keyring; see `Adding keys`_.  It is up to userspace to choose a
@@ -374,11 +374,11 @@ followed by the 16-character lower case hex 
representation of the
 ``master_key_descriptor`` that was set in the encryption policy.  The
 key payload must conform to the following structure::
 
-    #define FS_MAX_KEY_SIZE 64
+    #define FSCRYPT_MAX_KEY_SIZE 64
 
     struct fscrypt_key {
             u32 mode;
-            u8 raw[FS_MAX_KEY_SIZE];
+            u8 raw[FSCRYPT_MAX_KEY_SIZE];
             u32 size;
     };
 
@@ -533,7 +533,7 @@ much confusion if an encryption policy were to be added to 
or removed
 from anything other than an empty directory.)  The struct is defined
 as follows::
 
-    #define FS_KEY_DESCRIPTOR_SIZE  8
+    #define FSCRYPT_KEY_DESCRIPTOR_SIZE  8
     #define FS_KEY_DERIVATION_NONCE_SIZE 16
 
     struct fscrypt_context {
@@ -541,7 +541,7 @@ as follows::
             u8 contents_encryption_mode;
             u8 filenames_encryption_mode;
             u8 flags;
-            u8 master_key_descriptor[FS_KEY_DESCRIPTOR_SIZE];
+            u8 master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
             u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
     };
 
diff --git a/include/uapi/linux/fscrypt.h b/include/uapi/linux/fscrypt.h
index c09209fc42ea..26c381a40279 100644
--- a/include/uapi/linux/fscrypt.h
+++ b/include/uapi/linux/fscrypt.h
@@ -7,30 +7,31 @@
  * File system encryption support
  */
 /* Policy provided via an ioctl on the topmost directory */
-#define FS_KEY_DESCRIPTOR_SIZE 8
+#define FSCRYPT_KEY_DESCRIPTOR_SIZE    8
 
-#define FS_POLICY_FLAGS_PAD_4          0x00
-#define FS_POLICY_FLAGS_PAD_8          0x01
-#define FS_POLICY_FLAGS_PAD_16         0x02
-#define FS_POLICY_FLAGS_PAD_32         0x03
-#define FS_POLICY_FLAGS_PAD_MASK       0x03
-#define FS_POLICY_FLAGS_VALID          0x03
+/* Encryption policy flags */
+#define FSCRYPT_POLICY_FLAGS_PAD_4     0x00
+#define FSCRYPT_POLICY_FLAGS_PAD_8     0x01
+#define FSCRYPT_POLICY_FLAGS_PAD_16    0x02
+#define FSCRYPT_POLICY_FLAGS_PAD_32    0x03
+#define FSCRYPT_POLICY_FLAGS_PAD_MASK  0x03
+#define FSCRYPT_POLICY_FLAGS_VALID     0x03
 
 /* Encryption algorithms */
-#define FS_ENCRYPTION_MODE_INVALID             0
-#define FS_ENCRYPTION_MODE_AES_256_XTS         1
-#define FS_ENCRYPTION_MODE_AES_256_GCM         2
-#define FS_ENCRYPTION_MODE_AES_256_CBC         3
-#define FS_ENCRYPTION_MODE_AES_256_CTS         4
-#define FS_ENCRYPTION_MODE_AES_128_CBC         5
-#define FS_ENCRYPTION_MODE_AES_128_CTS         6
+#define FSCRYPT_MODE_INVALID           0
+#define FSCRYPT_MODE_AES_256_XTS       1
+#define FSCRYPT_MODE_AES_256_GCM       2
+#define FSCRYPT_MODE_AES_256_CBC       3
+#define FSCRYPT_MODE_AES_256_CTS       4
+#define FSCRYPT_MODE_AES_128_CBC       5
+#define FSCRYPT_MODE_AES_128_CTS       6
 
 struct fscrypt_policy {
        __u8 version;
        __u8 contents_encryption_mode;
        __u8 filenames_encryption_mode;
        __u8 flags;
-       __u8 master_key_descriptor[FS_KEY_DESCRIPTOR_SIZE];
+       __u8 master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
 };
 
 #define FS_IOC_SET_ENCRYPTION_POLICY   _IOR('f', 19, struct fscrypt_policy)
@@ -38,16 +39,36 @@ struct fscrypt_policy {
 #define FS_IOC_GET_ENCRYPTION_POLICY   _IOW('f', 21, struct fscrypt_policy)
 
 /* Parameters for passing an encryption key into the kernel keyring */
-#define FS_KEY_DESC_PREFIX             "fscrypt:"
-#define FS_KEY_DESC_PREFIX_SIZE                8
+#define FSCRYPT_KEY_DESC_PREFIX                "fscrypt:"
+#define FSCRYPT_KEY_DESC_PREFIX_SIZE           8
 
 /* Structure that userspace passes to the kernel keyring */
-#define FS_MAX_KEY_SIZE                        64
+#define FSCRYPT_MAX_KEY_SIZE                   64
 
 struct fscrypt_key {
        __u32 mode;
-       __u8 raw[FS_MAX_KEY_SIZE];
+       __u8 raw[FSCRYPT_MAX_KEY_SIZE];
        __u32 size;
 };
+/**********************************************************************/
+
+/* old names; don't add anything new here! */
+#define FS_POLICY_FLAGS_PAD_4          FSCRYPT_POLICY_FLAGS_PAD_4
+#define FS_POLICY_FLAGS_PAD_8          FSCRYPT_POLICY_FLAGS_PAD_8
+#define FS_POLICY_FLAGS_PAD_16         FSCRYPT_POLICY_FLAGS_PAD_16
+#define FS_POLICY_FLAGS_PAD_32         FSCRYPT_POLICY_FLAGS_PAD_32
+#define FS_POLICY_FLAGS_PAD_MASK       FSCRYPT_POLICY_FLAGS_PAD_MASK
+#define FS_POLICY_FLAGS_VALID          FSCRYPT_POLICY_FLAGS_VALID
+#define FS_KEY_DESCRIPTOR_SIZE         FSCRYPT_KEY_DESCRIPTOR_SIZE
+#define FS_ENCRYPTION_MODE_INVALID     FSCRYPT_MODE_INVALID
+#define FS_ENCRYPTION_MODE_AES_256_XTS FSCRYPT_MODE_AES_256_XTS
+#define FS_ENCRYPTION_MODE_AES_256_GCM FSCRYPT_MODE_AES_256_GCM
+#define FS_ENCRYPTION_MODE_AES_256_CBC FSCRYPT_MODE_AES_256_CBC
+#define FS_ENCRYPTION_MODE_AES_256_CTS FSCRYPT_MODE_AES_256_CTS
+#define FS_ENCRYPTION_MODE_AES_128_CBC FSCRYPT_MODE_AES_128_CBC
+#define FS_ENCRYPTION_MODE_AES_128_CTS FSCRYPT_MODE_AES_128_CTS
+#define FS_KEY_DESC_PREFIX             FSCRYPT_KEY_DESC_PREFIX
+#define FS_KEY_DESC_PREFIX_SIZE                FSCRYPT_KEY_DESC_PREFIX_SIZE
+#define FS_MAX_KEY_SIZE                        FSCRYPT_MAX_KEY_SIZE
 
 #endif /* _UAPI_LINUX_FSCRYPT_H */
-- 
2.15.0.rc0.271.g36b669edcc-goog


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