ext4 crypto: fix to check feature status before get policy
diff mbox series

Message ID 20190804095643.7393-1-chao@kernel.org
State Accepted, archived
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  • ext4 crypto: fix to check feature status before get policy
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Commit Message

Chao Yu Aug. 4, 2019, 9:56 a.m. UTC
From: Chao Yu <yuchao0@huawei.com>

When getting fscrypto 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.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
---
 fs/ext4/ioctl.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

Comments

Chao Yu Aug. 31, 2019, 10:32 a.m. UTC | #1
Hi,

Is this change not necessary? A month has passed...

Thanks,

On 2019/8/4 17:56, Chao Yu wrote:
> From: Chao Yu <yuchao0@huawei.com>
> 
> When getting fscrypto 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.
> 
> Signed-off-by: Chao Yu <yuchao0@huawei.com>
> ---
>  fs/ext4/ioctl.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
> index 442f7ef873fc..bf87835c1237 100644
> --- a/fs/ext4/ioctl.c
> +++ b/fs/ext4/ioctl.c
> @@ -1112,9 +1112,11 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>  		return -EOPNOTSUPP;
>  #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);
> -
> +	}
>  	case EXT4_IOC_FSGETXATTR:
>  	{
>  		struct fsxattr fa;
>
Eric Biggers Aug. 31, 2019, 3:02 p.m. UTC | #2
On Sat, Aug 31, 2019 at 06:32:28PM +0800, Chao Yu wrote:
> Hi,
> 
> Is this change not necessary? A month has passed...
> 
> Thanks,
> 
> On 2019/8/4 17:56, Chao Yu wrote:
> > From: Chao Yu <yuchao0@huawei.com>
> > 
> > When getting fscrypto 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.
> > 
> > Signed-off-by: Chao Yu <yuchao0@huawei.com>
> > ---
> >  fs/ext4/ioctl.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> > 
> > diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
> > index 442f7ef873fc..bf87835c1237 100644
> > --- a/fs/ext4/ioctl.c
> > +++ b/fs/ext4/ioctl.c
> > @@ -1112,9 +1112,11 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> >  		return -EOPNOTSUPP;
> >  #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);
> > -
> > +	}
> >  	case EXT4_IOC_FSGETXATTR:
> >  	{
> >  		struct fsxattr fa;
> > 

Sorry, I was preoccupied with all the other fscrypt changes, and was thinking of
waiting until 5.5 for this to avoid a potential extra merge conflict or a
potentially breaking change.  Looking at this again though, the new ioctl
FS_IOC_GET_ENCRYPTION_POLICY_EX *does* do the feature check, which doesn't match
the documentation, which implies the check isn't done.  Also, f2fs does the
check in FS_IOC_GET_ENCRYPTION_POLICY, so the filesystems are inconsistent.

So, it makes some sense to apply this now.  So I've gone ahead and applied the
following to fscrypt.git#master, edited a bit from your original patch:

From 0642ea2409f3bfa105570e12854b8e2628db6835 Mon Sep 17 00:00:00 2001
From: Chao Yu <yuchao0@huawei.com>
Date: Sun, 4 Aug 2019 17:56:43 +0800
Subject: [PATCH] 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>
---
 Documentation/filesystems/fscrypt.rst | 3 ++-
 fs/ext4/ioctl.c                       | 2 ++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/Documentation/filesystems/fscrypt.rst b/Documentation/filesystems/fscrypt.rst
index 4289c29d7c5a..8a0700af9596 100644
--- a/Documentation/filesystems/fscrypt.rst
+++ b/Documentation/filesystems/fscrypt.rst
@@ -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
   (try FS_IOC_GET_ENCRYPTION_POLICY instead)
 - ``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
   encryption policy version, but the policy struct does not fit into
   the provided buffer
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index fe5a4b13f939..5703d607f5af 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -1113,6 +1113,8 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 #endif
 	}
 	case EXT4_IOC_GET_ENCRYPTION_POLICY:
+		if (!ext4_has_feature_encrypt(sb))
+			return -EOPNOTSUPP;
 		return fscrypt_ioctl_get_policy(filp, (void __user *)arg);
 
 	case FS_IOC_GET_ENCRYPTION_POLICY_EX:
Chao Yu Sept. 2, 2019, 1:07 a.m. UTC | #3
On 2019/8/31 23:02, Eric Biggers wrote:
> On Sat, Aug 31, 2019 at 06:32:28PM +0800, Chao Yu wrote:
>> Hi,
>>
>> Is this change not necessary? A month has passed...
>>
>> Thanks,
>>
>> On 2019/8/4 17:56, Chao Yu wrote:
>>> From: Chao Yu <yuchao0@huawei.com>
>>>
>>> When getting fscrypto 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.
>>>
>>> Signed-off-by: Chao Yu <yuchao0@huawei.com>
>>> ---
>>>  fs/ext4/ioctl.c | 6 ++++--
>>>  1 file changed, 4 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
>>> index 442f7ef873fc..bf87835c1237 100644
>>> --- a/fs/ext4/ioctl.c
>>> +++ b/fs/ext4/ioctl.c
>>> @@ -1112,9 +1112,11 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>>>  		return -EOPNOTSUPP;
>>>  #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);
>>> -
>>> +	}
>>>  	case EXT4_IOC_FSGETXATTR:
>>>  	{
>>>  		struct fsxattr fa;
>>>
> 
> Sorry, I was preoccupied with all the other fscrypt changes, and was thinking of
> waiting until 5.5 for this to avoid a potential extra merge conflict or a
> potentially breaking change.  Looking at this again though, the new ioctl
> FS_IOC_GET_ENCRYPTION_POLICY_EX *does* do the feature check, which doesn't match
> the documentation, which implies the check isn't done.  Also, f2fs does the
> check in FS_IOC_GET_ENCRYPTION_POLICY, so the filesystems are inconsistent.
> 
> So, it makes some sense to apply this now.  So I've gone ahead and applied the
> following to fscrypt.git#master, edited a bit from your original patch:
> 
>>From 0642ea2409f3bfa105570e12854b8e2628db6835 Mon Sep 17 00:00:00 2001
> From: Chao Yu <yuchao0@huawei.com>
> Date: Sun, 4 Aug 2019 17:56:43 +0800
> Subject: [PATCH] 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]

The patch looks better now, thanks for the help.

Thanks,

> Signed-off-by: Eric Biggers <ebiggers@google.com>
> ---
>  Documentation/filesystems/fscrypt.rst | 3 ++-
>  fs/ext4/ioctl.c                       | 2 ++
>  2 files changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/filesystems/fscrypt.rst b/Documentation/filesystems/fscrypt.rst
> index 4289c29d7c5a..8a0700af9596 100644
> --- a/Documentation/filesystems/fscrypt.rst
> +++ b/Documentation/filesystems/fscrypt.rst
> @@ -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
>    (try FS_IOC_GET_ENCRYPTION_POLICY instead)
>  - ``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
>    encryption policy version, but the policy struct does not fit into
>    the provided buffer
> diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
> index fe5a4b13f939..5703d607f5af 100644
> --- a/fs/ext4/ioctl.c
> +++ b/fs/ext4/ioctl.c
> @@ -1113,6 +1113,8 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>  #endif
>  	}
>  	case EXT4_IOC_GET_ENCRYPTION_POLICY:
> +		if (!ext4_has_feature_encrypt(sb))
> +			return -EOPNOTSUPP;
>  		return fscrypt_ioctl_get_policy(filp, (void __user *)arg);
>  
>  	case FS_IOC_GET_ENCRYPTION_POLICY_EX:
>

Patch
diff mbox series

diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 442f7ef873fc..bf87835c1237 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -1112,9 +1112,11 @@  long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 		return -EOPNOTSUPP;
 #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);
-
+	}
 	case EXT4_IOC_FSGETXATTR:
 	{
 		struct fsxattr fa;