fscrypt: make "#define fscrypt_policy" user-only

The fscrypt UAPI header defines fscrypt_policy to fscrypt_policy_v1,
for source compatibility with old userspace programs.

Internally, the kernel doesn't want that compatibility definition.
Instead, fscrypt_private.h #undefs it and re-defines it to a union.

That works for now.  However, in order to add
fscrypt_operations::get_dummy_policy(), we'll need to forward declare
'union fscrypt_policy' in include/linux/fscrypt.h.  That would cause
build errors because "fscrypt_policy" is used in ioctl numbers.

To avoid this, modify the UAPI header to make the fscrypt_policy
compatibility definition conditional on !__KERNEL__, and make the ioctls
use fscrypt_policy_v1 instead of fscrypt_policy.

Note that this doesn't change the actual ioctl numbers.

Acked-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20200917041136.178600-11-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>

diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
index 355f6d937751701a2308f438bc523dc5dcbba10e..ac3352086ee44e2f7768429318005d8e4cdcf32f 100644 (file)
--- a/fs/crypto/fscrypt_private.h
+++ b/fs/crypto/fscrypt_private.h
@@ -97,7 +97,6 @@ static inline const u8 *fscrypt_context_nonce(const union fscrypt_context *ctx)
        return NULL;
 }
 
-#undef fscrypt_policy
 union fscrypt_policy {
        u8 version;
        struct fscrypt_policy_v1 v1;

diff --git a/include/uapi/linux/fscrypt.h b/include/uapi/linux/fscrypt.h
index 7875709ccfebff2a5903f73e753a015015729c5d..e5de60336938121f0584e0b43e9fc01fcb3d356c 100644 (file)
--- a/include/uapi/linux/fscrypt.h
+++ b/include/uapi/linux/fscrypt.h
@@ -45,7 +45,6 @@ struct fscrypt_policy_v1 {
        __u8 flags;
        __u8 master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
 };
-#define fscrypt_policy fscrypt_policy_v1
 
 /*
  * Process-subscribed "logon" key description prefix and payload format.
@@ -156,9 +155,9 @@ struct fscrypt_get_key_status_arg {
        __u32 __out_reserved[13];
 };
 
-#define FS_IOC_SET_ENCRYPTION_POLICY           _IOR('f', 19, struct fscrypt_policy)
+#define FS_IOC_SET_ENCRYPTION_POLICY           _IOR('f', 19, struct fscrypt_policy_v1)
 #define FS_IOC_GET_ENCRYPTION_PWSALT           _IOW('f', 20, __u8[16])
-#define FS_IOC_GET_ENCRYPTION_POLICY           _IOW('f', 21, struct fscrypt_policy)
+#define FS_IOC_GET_ENCRYPTION_POLICY           _IOW('f', 21, struct fscrypt_policy_v1)
 #define FS_IOC_GET_ENCRYPTION_POLICY_EX                _IOWR('f', 22, __u8[9]) /* size + version */
 #define FS_IOC_ADD_ENCRYPTION_KEY              _IOWR('f', 23, struct fscrypt_add_key_arg)
 #define FS_IOC_REMOVE_ENCRYPTION_KEY           _IOWR('f', 24, struct fscrypt_remove_key_arg)
@@ -170,6 +169,7 @@ struct fscrypt_get_key_status_arg {
 
 /* old names; don't add anything new here! */
 #ifndef __KERNEL__
+#define fscrypt_policy                 fscrypt_policy_v1
 #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