ext4 crypto: fix to check feature status before get policy

PATCH In review Chao Yu 3 participants 4 messages Aug 4, 2019 – Sep 2, 2019

Subsystems (3)

Documentation ext4 file system fscrypt: file system level encryption support

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Chao Yu

author

2019-08-04 09:56 UTC #0 lore raw

PATCH 1/1 ext4 crypto: fix to check feature status before get policy

From: Chao Yu <[email protected]>

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 <[email protected]>

---
 fs/ext4/ioctl.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

fs/ext4/ioctl.c +4 -2

index 442f7ef873fc..bf87835c1237 100644
@@ -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;

Signature · 1 line

2.22.0

Chao Yu

2019-08-31 10:32 UTC #1 lore raw

Hi,

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

Thanks,

Quoted 31 lines · Chao Yu

From: Chao Yu <[email protected]>
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 <[email protected]>
---
 fs/ext4/ioctl.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
fs/ext4/ioctl.c +4 -2
index 442f7ef873fc..bf87835c1237 100644
@@ -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

maintainer

2019-08-31 15:02 UTC #2 lore raw

Quoted 30 lines · Chao Yu

Hi,
Is this change not necessary? A month has passed...
Thanks,
Quoted 23 lines · Chao Yu
From: Chao Yu <[email protected]>
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 <[email protected]>
---
 fs/ext4/ioctl.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
fs/ext4/ioctl.c +2 -1
index 442f7ef873fc..bf87835c1237 100644
@@ -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))

Quoted 8 lines

fs/ext4/ioctl.c long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) · line 1122
Quoted 8 lines
fs/ext4/ioctl.c +2 -1
+			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:

Quoted 1 line

From 0642ea2409f3bfa105570e12854b8e2628db6835 Mon Sep 17 00:00:00 2001

From: Chao Yu <[email protected]>
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 <[email protected]>

[EB - removed unneeded braces, updated the documentation, and
added more explanation to commit message]

Signed-off-by Eric Biggers <[email protected]>

---
 Documentation/filesystems/fscrypt.rst | 3 ++-
 fs/ext4/ioctl.c                       | 2 ++
 2 files changed, 4 insertions(+), 1 deletion(-)

Documentation/filesystems/fscrypt.rst +2 -1

index 4289c29d7c5a..8a0700af9596 100644
@@ -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

fs/ext4/ioctl.c +2 -0

index fe5a4b13f939..5703d607f5af 100644
@@ -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:

Signature · 1 line

2.23.0

Chao Yu

2019-09-02 01:07 UTC #3 lore raw

Quoted 60 lines · Eric Biggers

Quoted 30 lines · Chao Yu
Hi,
Is this change not necessary? A month has passed...
Thanks,
Quoted 23 lines · Chao Yu
From: Chao Yu <[email protected]>
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 <[email protected]>
---
 fs/ext4/ioctl.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
fs/ext4/ioctl.c +2 -1
index 442f7ef873fc..bf87835c1237 100644
@@ -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))
Quoted 8 lines
fs/ext4/ioctl.c long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) · line 1122
Quoted 8 lines
fs/ext4/ioctl.c +2 -1
+			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:
Quoted 1 line
Quoted 1 line
From 0642ea2409f3bfa105570e12854b8e2628db6835 Mon Sep 17 00:00:00 2001
From: Chao Yu <[email protected]>
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.

Quoted 6 lines

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 <[email protected]>
[EB - removed unneeded braces, updated the documentation, and
added more explanation to commit message]

The patch looks better now, thanks for the help.

Thanks,

Quoted 34 lines

Signed-off-by Eric Biggers <[email protected]>

---
 Documentation/filesystems/fscrypt.rst | 3 ++-
 fs/ext4/ioctl.c                       | 2 ++
 2 files changed, 4 insertions(+), 1 deletion(-)

Documentation/filesystems/fscrypt.rst +2 -1

index 4289c29d7c5a..8a0700af9596 100644
@@ -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

fs/ext4/ioctl.c +2 -0

index fe5a4b13f939..5703d607f5af 100644
@@ -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: