@@ -487,13 +487,31 @@ keys, when hardware support is available. This works in the following way:
blk-crypto-fallback doesn't support hardware-wrapped keys. Therefore,
hardware-wrapped keys can only be used with actual inline encryption hardware.
-Currently, the kernel only works with hardware-wrapped keys in
-ephemerally-wrapped form. No generic kernel interfaces are provided for
-generating or importing hardware-wrapped keys in the first place, or converting
-them to ephemerally-wrapped form. In Android, SoC vendors are required to
-support these operations in their KeyMint implementation (a hardware abstraction
-layer in userspace); for details, see the `Android documentation
-<https://source.android.com/security/encryption/hw-wrapped-keys>`_.
+All the above deals with hardware-wrapped keys in ephemerally-wrapped form only.
+To get such keys in the first place, new block device ioctls have also been
+added to provide a generic interface to creating and preparing such keys:
+
+- ``BLKCRYPTOCREATEKEY`` creates a key in long-term wrapped form, either by
+ importing a raw key or by having the hardware generate the key. It takes in a
+ pointer to a ``struct blk_crypto_create_key_arg``. The caller must set
+ ``raw_key_ptr`` and ``raw_key_size`` to the pointer and size (in bytes) of the
+ raw key to import, or leave them 0 to have the hardware to generate the key.
+ The ioctl will write the resulting long-term wrapped key to the buffer pointed
+ to by ``longterm_wrapped_key_ptr``, which is of maximum size
+ ``longterm_wrapped_key_size``. It will also update
+ ``longterm_wrapped_key_size`` to be the actual size of the key. The ioctl
+ will return 0 on success, or will return -1 and set errno on failure.
+
+- ``BLKCRYPTOPREPAREKEY`` converts a key from long-term wrapped form to
+ ephemerally-wrapped form. It takes in a pointer to a
+ ``struct blk_crypto_prepare_key_arg``. The caller must set
+ ``longterm_wrapped_key_ptr`` and ``longterm_wrapped_key_size`` to the pointer
+ and size (in bytes) of the long-term wrapped key to convert. The ioctl will
+ write the resulting ephemerally-wrapped key to the buffer pointed to by
+ ``ephemerally_wrapped_key_ptr``, which is of maximum size
+ ``ephemerally_wrapped_key_size``. It will also update
+ ``ephemerally_wrapped_key_size`` to be the actual size of the key. The ioctl
+ will return 0 on success, or will return -1 and set errno on failure.
Testability
-----------
@@ -61,6 +61,9 @@ static inline bool blk_crypto_rq_is_encrypted(struct request *rq)
return rq->crypt_ctx;
}
+int blk_crypto_ioctl(struct block_device *bdev, unsigned int cmd,
+ void __user *argp);
+
#else /* CONFIG_BLK_INLINE_ENCRYPTION */
static inline bool bio_crypt_rq_ctx_compatible(struct request *rq,
@@ -94,6 +97,12 @@ static inline bool blk_crypto_rq_is_encrypted(struct request *rq)
return false;
}
+static inline int blk_crypto_ioctl(struct block_device *bdev, unsigned int cmd,
+ void __user *argp)
+{
+ return -ENOTTY;
+}
+
#endif /* CONFIG_BLK_INLINE_ENCRYPTION */
void __bio_crypt_advance(struct bio *bio, unsigned int bytes);
@@ -506,6 +506,59 @@ int blk_crypto_derive_sw_secret(struct blk_crypto_profile *profile,
return err;
}
+int blk_crypto_import_key(struct blk_crypto_profile *profile,
+ const u8 *raw_key, size_t raw_key_size,
+ u8 longterm_wrapped_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE])
+{
+ int ret = -EOPNOTSUPP;
+
+ if (profile &&
+ (profile->key_types_supported & BLK_CRYPTO_KEY_TYPE_HW_WRAPPED) &&
+ profile->ll_ops.import_key) {
+ blk_crypto_hw_enter(profile);
+ ret = profile->ll_ops.import_key(profile, raw_key, raw_key_size,
+ longterm_wrapped_key);
+ blk_crypto_hw_exit(profile);
+ }
+ return ret;
+}
+
+int blk_crypto_generate_key(struct blk_crypto_profile *profile,
+ u8 longterm_wrapped_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE])
+{
+ int ret = -EOPNOTSUPP;
+
+ if (profile &&
+ (profile->key_types_supported & BLK_CRYPTO_KEY_TYPE_HW_WRAPPED) &&
+ profile->ll_ops.generate_key) {
+ blk_crypto_hw_enter(profile);
+ ret = profile->ll_ops.generate_key(profile,
+ longterm_wrapped_key);
+ blk_crypto_hw_exit(profile);
+ }
+ return ret;
+}
+
+int blk_crypto_prepare_key(struct blk_crypto_profile *profile,
+ const u8 *longterm_wrapped_key,
+ size_t longterm_wrapped_key_size,
+ u8 ephemerally_wrapped_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE])
+{
+ int ret = -EOPNOTSUPP;
+
+ if (profile &&
+ (profile->key_types_supported & BLK_CRYPTO_KEY_TYPE_HW_WRAPPED) &&
+ profile->ll_ops.prepare_key) {
+ blk_crypto_hw_enter(profile);
+ ret = profile->ll_ops.prepare_key(profile,
+ longterm_wrapped_key,
+ longterm_wrapped_key_size,
+ ephemerally_wrapped_key);
+ blk_crypto_hw_exit(profile);
+ }
+ return ret;
+}
+
/**
* blk_crypto_intersect_capabilities() - restrict supported crypto capabilities
* by child device
@@ -438,3 +438,116 @@ int blk_crypto_evict_key(struct request_queue *q,
return blk_crypto_fallback_evict_key(key);
}
EXPORT_SYMBOL_GPL(blk_crypto_evict_key);
+
+static int blk_crypto_ioctl_create_key(struct blk_crypto_profile *profile,
+ void __user *argp)
+{
+ struct blk_crypto_create_key_arg arg;
+ u8 raw_key[BLK_CRYPTO_MAX_STANDARD_KEY_SIZE];
+ u8 longterm_wrapped_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE];
+ int ret;
+
+ if (copy_from_user(&arg, argp, sizeof(arg)))
+ return -EFAULT;
+
+ if (memchr_inv(arg.reserved, 0, sizeof(arg.reserved)))
+ return -EINVAL;
+
+ if (arg.raw_key_size) {
+ if (arg.raw_key_size > sizeof(raw_key))
+ return -EINVAL;
+ if (copy_from_user(raw_key, u64_to_user_ptr(arg.raw_key_ptr),
+ arg.raw_key_size)) {
+ ret = -EFAULT;
+ goto out;
+ }
+ ret = blk_crypto_import_key(profile, raw_key, arg.raw_key_size,
+ longterm_wrapped_key);
+ } else {
+ ret = blk_crypto_generate_key(profile, longterm_wrapped_key);
+ }
+ if (ret < 0)
+ goto out;
+ if (ret > arg.longterm_wrapped_key_size) {
+ ret = -ENOBUFS;
+ goto out;
+ }
+ arg.longterm_wrapped_key_size = ret;
+ if (copy_to_user(u64_to_user_ptr(arg.longterm_wrapped_key_ptr),
+ longterm_wrapped_key, arg.longterm_wrapped_key_size) ||
+ copy_to_user(argp, &arg, sizeof(arg))) {
+ ret = -EFAULT;
+ goto out;
+ }
+ ret = 0;
+out:
+ memzero_explicit(raw_key, sizeof(raw_key));
+ memzero_explicit(longterm_wrapped_key, sizeof(longterm_wrapped_key));
+ return ret;
+}
+
+static int blk_crypto_ioctl_prepare_key(struct blk_crypto_profile *profile,
+ void __user *argp)
+{
+ struct blk_crypto_prepare_key_arg arg;
+ u8 longterm_wrapped_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE];
+ u8 ephemerally_wrapped_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE];
+ int ret;
+
+ if (copy_from_user(&arg, argp, sizeof(arg)))
+ return -EFAULT;
+
+ if (memchr_inv(arg.reserved, 0, sizeof(arg.reserved)))
+ return -EINVAL;
+
+ if (arg.longterm_wrapped_key_size > sizeof(longterm_wrapped_key))
+ return -EINVAL;
+ if (copy_from_user(longterm_wrapped_key,
+ u64_to_user_ptr(arg.longterm_wrapped_key_ptr),
+ arg.longterm_wrapped_key_size)) {
+ ret = -EFAULT;
+ goto out;
+ }
+ ret = blk_crypto_prepare_key(profile, longterm_wrapped_key,
+ arg.longterm_wrapped_key_size,
+ ephemerally_wrapped_key);
+ if (ret < 0)
+ goto out;
+ if (ret > arg.ephemerally_wrapped_key_size) {
+ ret = -ENOBUFS;
+ goto out;
+ }
+ arg.ephemerally_wrapped_key_size = ret;
+ if (copy_to_user(u64_to_user_ptr(arg.ephemerally_wrapped_key_ptr),
+ ephemerally_wrapped_key,
+ arg.ephemerally_wrapped_key_size) ||
+ copy_to_user(argp, &arg, sizeof(arg))) {
+ ret = -EFAULT;
+ goto out;
+ }
+ ret = 0;
+out:
+ memzero_explicit(longterm_wrapped_key, sizeof(longterm_wrapped_key));
+ memzero_explicit(ephemerally_wrapped_key,
+ sizeof(ephemerally_wrapped_key));
+ return ret;
+}
+
+int blk_crypto_ioctl(struct block_device *bdev, unsigned int cmd,
+ void __user *argp)
+{
+ struct blk_crypto_profile *profile =
+ bdev_get_queue(bdev)->crypto_profile;
+
+ if (!profile)
+ return -EOPNOTSUPP;
+
+ switch (cmd) {
+ case BLKCRYPTOCREATEKEY:
+ return blk_crypto_ioctl_create_key(profile, argp);
+ case BLKCRYPTOPREPAREKEY:
+ return blk_crypto_ioctl_prepare_key(profile, argp);
+ default:
+ return -ENOTTY;
+ }
+}
@@ -12,6 +12,7 @@
#include <linux/pr.h>
#include <linux/uaccess.h>
#include "blk.h"
+#include "blk-crypto-internal.h"
static int blkpg_do_ioctl(struct block_device *bdev,
struct blkpg_partition __user *upart, int op)
@@ -527,6 +528,9 @@ static int blkdev_common_ioctl(struct block_device *bdev, fmode_t mode,
case BLKTRACESTOP:
case BLKTRACETEARDOWN:
return blk_trace_ioctl(bdev, cmd, argp);
+ case BLKCRYPTOCREATEKEY:
+ case BLKCRYPTOPREPAREKEY:
+ return blk_crypto_ioctl(bdev, cmd, argp);
case IOC_PR_REGISTER:
return blkdev_pr_register(bdev, argp);
case IOC_PR_RESERVE:
@@ -72,6 +72,48 @@ struct blk_crypto_ll_ops {
const u8 *wrapped_key,
unsigned int wrapped_key_size,
u8 sw_secret[BLK_CRYPTO_SW_SECRET_SIZE]);
+
+ /**
+ * @import_key: Create a hardware-wrapped key by importing a raw key.
+ *
+ * This only needs to be implemented if BLK_CRYPTO_KEY_TYPE_HW_WRAPPED
+ * is supported.
+ *
+ * Must return the size (in bytes) of the resulting wrapped key on
+ * success, or -errno on failure.
+ */
+ int (*import_key)(struct blk_crypto_profile *profile,
+ const u8 *raw_key, size_t raw_key_size,
+ u8 longterm_wrapped_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE]);
+
+ /**
+ * @generate_key: Generate a hardware-wrapped key.
+ *
+ * This only needs to be implemented if BLK_CRYPTO_KEY_TYPE_HW_WRAPPED
+ * is supported.
+ *
+ * Must return the size (in bytes) of the resulting wrapped key on
+ * success, or -errno on failure.
+ */
+ int (*generate_key)(struct blk_crypto_profile *profile,
+ u8 longterm_wrapped_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE]);
+
+ /**
+ * @prepare_key: Prepare a hardware-wrapped key to be used.
+ *
+ * This function prepares a hardware-wrapped to be used by converting it
+ * from long-term wrapped form to ephemerally-wrapped form.
+ *
+ * This only needs to be implemented if BLK_CRYPTO_KEY_TYPE_HW_WRAPPED
+ * is supported.
+ *
+ * Must return the size (in bytes) of the resulting wrapped key on
+ * success, or -errno on failure.
+ */
+ int (*prepare_key)(struct blk_crypto_profile *profile,
+ const u8 *longterm_wrapped_key,
+ size_t longterm_wrapped_key_size,
+ u8 ephemerally_wrapped_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE]);
};
/**
@@ -180,6 +222,18 @@ int blk_crypto_derive_sw_secret(struct blk_crypto_profile *profile,
unsigned int wrapped_key_size,
u8 sw_secret[BLK_CRYPTO_SW_SECRET_SIZE]);
+int blk_crypto_import_key(struct blk_crypto_profile *profile,
+ const u8 *raw_key, size_t raw_key_size,
+ u8 longterm_wrapped_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE]);
+
+int blk_crypto_generate_key(struct blk_crypto_profile *profile,
+ u8 longterm_wrapped_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE]);
+
+int blk_crypto_prepare_key(struct blk_crypto_profile *profile,
+ const u8 *longterm_wrapped_key,
+ size_t longterm_wrapped_key_size,
+ u8 ephemerally_wrapped_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE]);
+
void blk_crypto_intersect_capabilities(struct blk_crypto_profile *parent,
const struct blk_crypto_profile *child);
@@ -121,6 +121,22 @@ struct fsxattr {
unsigned char fsx_pad[8];
};
+struct blk_crypto_create_key_arg {
+ __u64 raw_key_ptr;
+ __u64 raw_key_size;
+ __u64 longterm_wrapped_key_ptr;
+ __u64 longterm_wrapped_key_size;
+ __u64 reserved[4];
+};
+
+struct blk_crypto_prepare_key_arg {
+ __u64 longterm_wrapped_key_ptr;
+ __u64 longterm_wrapped_key_size;
+ __u64 ephemerally_wrapped_key_ptr;
+ __u64 ephemerally_wrapped_key_size;
+ __u64 reserved[4];
+};
+
/*
* Flags for the fsx_xflags field
*/
@@ -185,6 +201,9 @@ struct fsxattr {
#define BLKROTATIONAL _IO(0x12,126)
#define BLKZEROOUT _IO(0x12,127)
#define BLKGETDISKSEQ _IOR(0x12,128,__u64)
+#define BLKCRYPTOCREATEKEY _IOWR(0x12, 129, struct blk_crypto_create_key_arg)
+#define BLKCRYPTOPREPAREKEY _IOWR(0x12, 130, struct blk_crypto_prepare_key_arg)
+
/*
* A jump here: 130-136 are reserved for zoned block devices
* (see uapi/linux/blkzoned.h)