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ext4 crypto: fix to check feature status before get policy 

When getting fscrypt policy via EXT4_IOC_GET_ENCRYPTION_POLICY, if
encryption feature is off, it's better to return EOPNOTSUPP instead of
ENODATA, so let's add ext4_has_feature_encrypt() to do the check for
that.

This makes it so that all fscrypt ioctls consistently check for the
encryption feature, and makes ext4 consistent with f2fs in this regard.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
[EB - removed unneeded braces, updated the documentation, and
      added more explanation to commit message]
Signed-off-by: Eric Biggers <ebiggers@google.com>
This commit is contained in:
Chao Yu 2019-08-04 17:56:43 +08:00 committed by Eric Biggers
parent ba13f2c8d7
commit 0642ea2409
2 changed files with 4 additions and 1 deletions
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3
Documentation/filesystems/fscrypt.rst
View File

@ -562,7 +562,8 @@ FS_IOC_GET_ENCRYPTION_POLICY_EX can fail with the following errors:
or this kernel is too old to support FS_IOC_GET_ENCRYPTION_POLICY_EX or this kernel is too old to support FS_IOC_GET_ENCRYPTION_POLICY_EX
(try FS_IOC_GET_ENCRYPTION_POLICY instead) (try FS_IOC_GET_ENCRYPTION_POLICY instead)
- ``EOPNOTSUPP``: the kernel was not configured with encryption - ``EOPNOTSUPP``: the kernel was not configured with encryption
support for this filesystem support for this filesystem, or the filesystem superblock has not
had encryption enabled on it
- ``EOVERFLOW``: the file is encrypted and uses a recognized - ``EOVERFLOW``: the file is encrypted and uses a recognized
encryption policy version, but the policy struct does not fit into encryption policy version, but the policy struct does not fit into
the provided buffer the provided buffer

2
fs/ext4/ioctl.c
View File

@ -1113,6 +1113,8 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
#endif #endif
} }
case EXT4_IOC_GET_ENCRYPTION_POLICY: case EXT4_IOC_GET_ENCRYPTION_POLICY:
if (!ext4_has_feature_encrypt(sb))
return -EOPNOTSUPP;
return fscrypt_ioctl_get_policy(filp, (void __user *)arg); return fscrypt_ioctl_get_policy(filp, (void __user *)arg);
case FS_IOC_GET_ENCRYPTION_POLICY_EX: case FS_IOC_GET_ENCRYPTION_POLICY_EX: