fscrypto: move ioctl processing more fully into common code

Multiple bugs were recently fixed in the "set encryption policy" ioctl.
To make it clear that fscrypt_process_policy() and fscrypt_get_policy()
implement ioctls and therefore their implementations must take standard
security and correctness precautions, rename them to
fscrypt_ioctl_set_policy() and fscrypt_ioctl_get_policy().  Make the
latter take in a struct file * to make it consistent with the former.

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

2 files changed, 7 insertions, 31 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 282a51b07c57..bd8bc3be93a5 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2338,8 +2338,8 @@ static inline void ext4_fname_free_filename(struct ext4_filename *fname) { }
 #define fscrypt_pullback_bio_page	fscrypt_notsupp_pullback_bio_page
 #define fscrypt_restore_control_page	fscrypt_notsupp_restore_control_page
 #define fscrypt_zeroout_range		fscrypt_notsupp_zeroout_range
-#define fscrypt_process_policy		fscrypt_notsupp_process_policy
-#define fscrypt_get_policy		fscrypt_notsupp_get_policy
+#define fscrypt_ioctl_set_policy	fscrypt_notsupp_ioctl_set_policy
+#define fscrypt_ioctl_get_policy	fscrypt_notsupp_ioctl_get_policy
 #define fscrypt_has_permitted_context	fscrypt_notsupp_has_permitted_context
 #define fscrypt_inherit_context		fscrypt_notsupp_inherit_context
 #define fscrypt_get_encryption_info	fscrypt_notsupp_get_encryption_info
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index bf5ae8ebbc97..70083863ce51 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -765,22 +765,12 @@ resizefs_out:
 	}
 	case EXT4_IOC_PRECACHE_EXTENTS:
 		return ext4_ext_precache(inode);
-	case EXT4_IOC_SET_ENCRYPTION_POLICY: {
-#ifdef CONFIG_EXT4_FS_ENCRYPTION
-		struct fscrypt_policy policy;
 
+	case EXT4_IOC_SET_ENCRYPTION_POLICY:
 		if (!ext4_has_feature_encrypt(sb))
 			return -EOPNOTSUPP;
+		return fscrypt_ioctl_set_policy(filp, (const void __user *)arg);
 
-		if (copy_from_user(&policy,
-				   (struct fscrypt_policy __user *)arg,
-				   sizeof(policy)))
-			return -EFAULT;
-		return fscrypt_process_policy(filp, &policy);
-#else
-		return -EOPNOTSUPP;
-#endif
-	}
 	case EXT4_IOC_GET_ENCRYPTION_PWSALT: {
 		int err, err2;
 		struct ext4_sb_info *sbi = EXT4_SB(sb);
@@ -817,23 +807,9 @@ resizefs_out:
 			return -EFAULT;
 		return 0;
 	}
-	case EXT4_IOC_GET_ENCRYPTION_POLICY: {
-#ifdef CONFIG_EXT4_FS_ENCRYPTION
-		struct fscrypt_policy policy;
-		int err = 0;
-
-		if (!ext4_encrypted_inode(inode))
-			return -ENOENT;
-		err = fscrypt_get_policy(inode, &policy);
-		if (err)
-			return err;
-		if (copy_to_user((void __user *)arg, &policy, sizeof(policy)))
-			return -EFAULT;
-		return 0;
-#else
-		return -EOPNOTSUPP;
-#endif
-	}
+	case EXT4_IOC_GET_ENCRYPTION_POLICY:
+		return fscrypt_ioctl_get_policy(filp, (void __user *)arg);
+
 	case EXT4_IOC_FSGETXATTR:
 	{
 		struct fsxattr fa;