[f2fs-dev] [PATCH] fscrypt: reserve flags for hardware-wrapped keys feature

[f2fs-dev] [PATCH] fscrypt: reserve flags for hardware-wrapped keys feature

[Eric Biggers]

From: Eric Biggers <ebiggers@google.com>

Reserve flags for the hardware-wrapped keys feature which is being
worked on [1].  FSCRYPT_POLICY_FLAG_HW_WRAPPED_KEY will denote that the
encryption policy needs a hardware-wrapped key to be unlocked.
FSCRYPT_ADD_KEY_FLAG_HW_WRAPPED will denote that the key being added is
a hardware-wrapped key.

This reservation is tentative, and these codepoints may be reused if the
feature is not upstreamed.

[1] https://android-review.googlesource.com/c/kernel/common/+/1200864

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 Documentation/filesystems/fscrypt.rst | 5 +++--
 fs/crypto/keyring.c                   | 5 ++++-
 fs/crypto/policy.c                    | 4 +++-
 include/uapi/linux/fscrypt.h          | 9 ++++++---
 4 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/Documentation/filesystems/fscrypt.rst b/Documentation/filesystems/fscrypt.rst
index 9c53336d06a438..4c443d7b1fc6b5 100644
--- a/Documentation/filesystems/fscrypt.rst
+++ b/Documentation/filesystems/fscrypt.rst
@@ -639,7 +639,8 @@ follows::
             struct fscrypt_key_specifier key_spec;
             __u32 raw_size;
             __u32 key_id;
-            __u32 __reserved[8];
+            __u32 flags;
+            __u32 __reserved[7];
             __u8 raw[];
     };
 
@@ -658,7 +659,7 @@ follows::
 
     struct fscrypt_provisioning_key_payload {
             __u32 type;
-            __u32 __reserved;
+            __u32 flags;
             __u8 raw[];
     };
 
diff --git a/fs/crypto/keyring.c b/fs/crypto/keyring.c
index 098ff2e0f0bb41..fc27f5d08d7dbe 100644
--- a/fs/crypto/keyring.c
+++ b/fs/crypto/keyring.c
@@ -477,7 +477,7 @@ static int fscrypt_provisioning_key_preparse(struct key_preparsed_payload *prep)
 	    payload->type != FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER)
 		return -EINVAL;
 
-	if (payload->__reserved)
+	if (payload->flags)
 		return -EINVAL;
 
 	prep->payload.data[0] = kmemdup(payload, prep->datalen, GFP_KERNEL);
@@ -606,6 +606,9 @@ int fscrypt_ioctl_add_key(struct file *filp, void __user *_uarg)
 	if (!valid_key_spec(&arg.key_spec))
 		return -EINVAL;
 
+	if (arg.flags)
+		return -EINVAL;
+
 	if (memchr_inv(arg.__reserved, 0, sizeof(arg.__reserved)))
 		return -EINVAL;
 
diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
index f1cff83c151acf..36a2bb077b6910 100644
--- a/fs/crypto/policy.c
+++ b/fs/crypto/policy.c
@@ -139,7 +139,9 @@ static bool fscrypt_supported_v2_policy(const struct fscrypt_policy_v2 *policy,
 		return false;
 	}
 
-	if (policy->flags & ~FSCRYPT_POLICY_FLAGS_VALID) {
+	if (policy->flags & ~(FSCRYPT_POLICY_FLAGS_PAD_MASK |
+			      FSCRYPT_POLICY_FLAG_DIRECT_KEY |
+			      FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64)) {
 		fscrypt_warn(inode, "Unsupported encryption flags (0x%02x)",
 			     policy->flags);
 		return false;
diff --git a/include/uapi/linux/fscrypt.h b/include/uapi/linux/fscrypt.h
index 0d8a6f47711c32..fad624a4c5feda 100644
--- a/include/uapi/linux/fscrypt.h
+++ b/include/uapi/linux/fscrypt.h
@@ -19,7 +19,8 @@
 #define FSCRYPT_POLICY_FLAGS_PAD_MASK		0x03
 #define FSCRYPT_POLICY_FLAG_DIRECT_KEY		0x04
 #define FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64	0x08
-#define FSCRYPT_POLICY_FLAGS_VALID		0x0F
+#define FSCRYPT_POLICY_FLAG_HW_WRAPPED_KEY	0x10
+#define FSCRYPT_POLICY_FLAGS_VALID		0x1F
 
 /* Encryption algorithms */
 #define FSCRYPT_MODE_AES_256_XTS		1
@@ -116,7 +117,7 @@ struct fscrypt_key_specifier {
  */
 struct fscrypt_provisioning_key_payload {
 	__u32 type;
-	__u32 __reserved;
+	__u32 flags;
 	__u8 raw[];
 };
 
@@ -125,7 +126,9 @@ struct fscrypt_add_key_arg {
 	struct fscrypt_key_specifier key_spec;
 	__u32 raw_size;
 	__u32 key_id;
-	__u32 __reserved[8];
+#define FSCRYPT_ADD_KEY_FLAG_HW_WRAPPED			0x00000001
+	__u32 flags;
+	__u32 __reserved[7];
 	__u8 raw[];
 };
 

base-commit: 2d8f7f119b0b2ce5e7ff0e8024b0763bf42b99c9
-- 
2.25.0.rc1.283.g88dfdc4193-goog



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Re: [f2fs-dev] [PATCH] fscrypt: reserve flags for hardware-wrapped keys feature

[Christoph Hellwig]

On Thu, Jan 16, 2020 at 11:20:08AM -0800, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> Reserve flags for the hardware-wrapped keys feature which is being
> worked on [1].  FSCRYPT_POLICY_FLAG_HW_WRAPPED_KEY will denote that the
> encryption policy needs a hardware-wrapped key to be unlocked.
> FSCRYPT_ADD_KEY_FLAG_HW_WRAPPED will denote that the key being added is
> a hardware-wrapped key.
> 
> This reservation is tentative, and these codepoints may be reused if the
> feature is not upstreamed.

NAK.  While the feature itself sounds really useful we don't just
reserve format bits for code not upstream.


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Re: [f2fs-dev] [PATCH] fscrypt: reserve flags for hardware-wrapped keys feature

[Theodore Y. Ts'o]

On Fri, Jan 17, 2020 at 12:12:46AM -0800, Christoph Hellwig wrote:
> On Thu, Jan 16, 2020 at 11:20:08AM -0800, Eric Biggers wrote:
> > From: Eric Biggers <ebiggers@google.com>
> > 
> > Reserve flags for the hardware-wrapped keys feature which is being
> > worked on [1].  FSCRYPT_POLICY_FLAG_HW_WRAPPED_KEY will denote that the
> > encryption policy needs a hardware-wrapped key to be unlocked.
> > FSCRYPT_ADD_KEY_FLAG_HW_WRAPPED will denote that the key being added is
> > a hardware-wrapped key.
> > 
> > This reservation is tentative, and these codepoints may be reused if the
> > feature is not upstreamed.
> 
> NAK.  While the feature itself sounds really useful we don't just
> reserve format bits for code not upstream.

I disagree; saving a codepoint to avoid accidental collision of a
feature bit is a good and proper thing to do.

Reviewed-by: Theodore Ts'o <tytso@mit.edu>

							- Ted



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Re: [f2fs-dev] [PATCH] fscrypt: reserve flags for hardware-wrapped keys feature

[Greg KH]

On Fri, Jan 17, 2020 at 11:40:54AM -0500, Theodore Y. Ts'o wrote:
> On Fri, Jan 17, 2020 at 12:12:46AM -0800, Christoph Hellwig wrote:
> > On Thu, Jan 16, 2020 at 11:20:08AM -0800, Eric Biggers wrote:
> > > From: Eric Biggers <ebiggers@google.com>
> > > 
> > > Reserve flags for the hardware-wrapped keys feature which is being
> > > worked on [1].  FSCRYPT_POLICY_FLAG_HW_WRAPPED_KEY will denote that the
> > > encryption policy needs a hardware-wrapped key to be unlocked.
> > > FSCRYPT_ADD_KEY_FLAG_HW_WRAPPED will denote that the key being added is
> > > a hardware-wrapped key.
> > > 
> > > This reservation is tentative, and these codepoints may be reused if the
> > > feature is not upstreamed.
> > 
> > NAK.  While the feature itself sounds really useful we don't just
> > reserve format bits for code not upstream.
> 
> I disagree; saving a codepoint to avoid accidental collision of a
> feature bit is a good and proper thing to do.
> 
> Reviewed-by: Theodore Ts'o <tytso@mit.edu>

What kind of "deadline" do you have for that feature to then be merged?
I'm with Christoph here, we shouldn't be reserving bits for stuff not
in mergable state, what's the rush?

thansk,

greg k-h


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