fscrypt: use FSCRYPT_ prefix for uapi constants

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_V1 or inconsistent
names like FS_ENCRYPTION_POLICY_V1.

For source compatibility with existing userspace programs, keep the old
names defined as aliases to the new names.

Finally, as long as new names are being defined anyway, I skipped
defining new names for the fscrypt mode numbers that aren't actually
used: INVALID (0), AES_256_GCM (2), AES_256_CBC (3), SPECK128_256_XTS
(7), and SPECK128_256_CTS (8).

Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Eric Biggers <ebiggers@google.com>

1 files changed, 42 insertions, 23 deletions

diff --git a/include/uapi/linux/fscrypt.h b/include/uapi/linux/fscrypt.h
index 26f6d2c19afd..674b0452ef57 100644
--- a/include/uapi/linux/fscrypt.h
+++ b/include/uapi/linux/fscrypt.h
@@ -10,35 +10,30 @@
 
 #include <linux/types.h>
 
-#define FS_KEY_DESCRIPTOR_SIZE  8
+#define FSCRYPT_KEY_DESCRIPTOR_SIZE     8
 
 /* Encryption policy flags */
-#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_FLAG_DIRECT_KEY       0x04    /* use master key directly */
-#define FS_POLICY_FLAGS_VALID           0x07
+#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_FLAG_DIRECT_KEY          0x04    /* use master key directly */
+#define FSCRYPT_POLICY_FLAGS_VALID              0x07
 
 /* 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 FS_ENCRYPTION_MODE_SPECK128_256_XTS     7 /* Removed, do not use. */
-#define FS_ENCRYPTION_MODE_SPECK128_256_CTS     8 /* Removed, do not use. */
-#define FS_ENCRYPTION_MODE_ADIANTUM             9
+#define FSCRYPT_MODE_AES_256_XTS                1
+#define FSCRYPT_MODE_AES_256_CTS                4
+#define FSCRYPT_MODE_AES_128_CBC                5
+#define FSCRYPT_MODE_AES_128_CTS                6
+#define FSCRYPT_MODE_ADIANTUM                   9
 
 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)
@@ -46,16 +41,40 @@ 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_KEY_DESCRIPTOR_SIZE          FSCRYPT_KEY_DESCRIPTOR_SIZE
+#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_FLAG_DIRECT_KEY       FSCRYPT_POLICY_FLAG_DIRECT_KEY
+#define FS_POLICY_FLAGS_VALID           FSCRYPT_POLICY_FLAGS_VALID
+#define FS_ENCRYPTION_MODE_INVALID      0       /* never used */
+#define FS_ENCRYPTION_MODE_AES_256_XTS  FSCRYPT_MODE_AES_256_XTS
+#define FS_ENCRYPTION_MODE_AES_256_GCM  2       /* never used */
+#define FS_ENCRYPTION_MODE_AES_256_CBC  3       /* never used */
+#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_ENCRYPTION_MODE_SPECK128_256_XTS     7       /* removed */
+#define FS_ENCRYPTION_MODE_SPECK128_256_CTS     8       /* removed */
+#define FS_ENCRYPTION_MODE_ADIANTUM     FSCRYPT_MODE_ADIANTUM
+#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 */