diff mbox series

[RFC,v2,1/4] firmware: qcom_scm: Add support for programming inline crypto keys

Message ID 20200304064942.371978-2-ebiggers@kernel.org (mailing list archive)
State Superseded
Headers show
Series Inline crypto support on DragonBoard 845c | expand

Commit Message

Eric Biggers March 4, 2020, 6:49 a.m. UTC 
From: Eric Biggers <ebiggers@google.com>

Add support for the Inline Crypto Engine (ICE) key programming interface
that's needed for the ufs-qcom driver to use inline encryption on
Snapdragon SoCs.  This interface consists of two SCM calls: one to
program a key into a keyslot, and one to invalidate a keyslot.

Although the UFS specification defines a standard way to do this, on
these SoCs the Linux kernel isn't permitted to access the needed crypto
configuration registers directly; these SCM calls must be used instead.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 drivers/firmware/qcom_scm.c | 96 +++++++++++++++++++++++++++++++++++++
 drivers/firmware/qcom_scm.h |  4 ++
 include/linux/qcom_scm.h    | 19 ++++++++
 3 files changed, 119 insertions(+)

Comments

Stephen Boyd March 4, 2020, 5:04 p.m. UTC | #1 
Quoting Eric Biggers (2020-03-03 22:49:39)
> diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
> index 059bb0fbae9e..7fb9f606250f 100644
> --- a/drivers/firmware/qcom_scm.c
> +++ b/drivers/firmware/qcom_scm.c
> @@ -926,6 +927,101 @@ int qcom_scm_ocmem_unlock(enum qcom_scm_ocmem_client id, u32 offset, u32 size)
[...]
> +
> +/**
> + * qcom_scm_ice_set_key() - Set an inline encryption key
> + * @index: the keyslot into which to set the key
> + * @key: the key to program
> + * @key_size: the size of the key in bytes
> + * @cipher: the encryption algorithm the key is for
> + * @data_unit_size: the encryption data unit size, i.e. the size of each
> + *                 individual plaintext and ciphertext.  Given in 512-byte
> + *                 units, e.g. 1 = 512 bytes, 8 = 4096 bytes, etc.
> + *
> + * Program a key into a keyslot of Qualcomm ICE (Inline Crypto Engine), where it
> + * can then be used to encrypt/decrypt UFS I/O requests inline.
> + *
> + * The UFSHCI standard defines a standard way to do this, but it doesn't work on
> + * these SoCs; only this SCM call does.
> + *
> + * Return: 0 on success; -errno on failure.
> + */
> +int qcom_scm_ice_set_key(u32 index, const u8 *key, int key_size,
> +                        enum qcom_scm_ice_cipher cipher, int data_unit_size)

Why not make key_size and data_unit_size unsigned?

> +{
> +       struct qcom_scm_desc desc = {
> +               .svc = QCOM_SCM_SVC_ES,
> +               .cmd = QCOM_SCM_ES_CONFIG_SET_ICE_KEY,
> +               .arginfo = QCOM_SCM_ARGS(5, QCOM_SCM_VAL, QCOM_SCM_RW,
> +                                        QCOM_SCM_VAL, QCOM_SCM_VAL,
> +                                        QCOM_SCM_VAL),
> +               .args[0] = index,
> +               .args[2] = key_size,
> +               .args[3] = cipher,
> +               .args[4] = data_unit_size,
> +               .owner = ARM_SMCCC_OWNER_SIP,
> +       };
> +       u8 *keybuf;
> +       dma_addr_t key_phys;
> +       int ret;
> +
> +       keybuf = kmemdup(key, key_size, GFP_KERNEL);

Is this to make the key physically contiguous? Probably worth a comment
to help others understand why this is here.

> +       if (!keybuf)
> +               return -ENOMEM;
> +
> +       key_phys = dma_map_single(__scm->dev, keybuf, key_size, DMA_TO_DEVICE);
> +       if (dma_mapping_error(__scm->dev, key_phys)) {
> +               ret = -ENOMEM;
> +               goto out;
> +       }
> +       desc.args[1] = key_phys;
> +
> +       ret = qcom_scm_call(__scm->dev, &desc, NULL);
> +
> +       dma_unmap_single(__scm->dev, key_phys, key_size, DMA_TO_DEVICE);
> +out:
> +       kzfree(keybuf);

And this is because we want to clear key contents out of the slab? What
about if the dma_map_single() bounces to a bounce buffer? I think that
isn't going to happen because __scm->dev is just some firmware device
that doesn't require bounce buffers but it's worth another comment to
clarify this.

> +       return ret;
> +}
> +EXPORT_SYMBOL(qcom_scm_ice_set_key);
> +
>  /**
>   * qcom_scm_hdcp_available() - Check if secure environment supports HDCP.
>   *
Eric Biggers March 4, 2020, 9:10 p.m. UTC | #2 
On Wed, Mar 04, 2020 at 09:04:49AM -0800, Stephen Boyd wrote:
> Quoting Eric Biggers (2020-03-03 22:49:39)
> > diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
> > index 059bb0fbae9e..7fb9f606250f 100644
> > --- a/drivers/firmware/qcom_scm.c
> > +++ b/drivers/firmware/qcom_scm.c
> > @@ -926,6 +927,101 @@ int qcom_scm_ocmem_unlock(enum qcom_scm_ocmem_client id, u32 offset, u32 size)
> [...]
> > +
> > +/**
> > + * qcom_scm_ice_set_key() - Set an inline encryption key
> > + * @index: the keyslot into which to set the key
> > + * @key: the key to program
> > + * @key_size: the size of the key in bytes
> > + * @cipher: the encryption algorithm the key is for
> > + * @data_unit_size: the encryption data unit size, i.e. the size of each
> > + *                 individual plaintext and ciphertext.  Given in 512-byte
> > + *                 units, e.g. 1 = 512 bytes, 8 = 4096 bytes, etc.
> > + *
> > + * Program a key into a keyslot of Qualcomm ICE (Inline Crypto Engine), where it
> > + * can then be used to encrypt/decrypt UFS I/O requests inline.
> > + *
> > + * The UFSHCI standard defines a standard way to do this, but it doesn't work on
> > + * these SoCs; only this SCM call does.
> > + *
> > + * Return: 0 on success; -errno on failure.
> > + */
> > +int qcom_scm_ice_set_key(u32 index, const u8 *key, int key_size,
> > +                        enum qcom_scm_ice_cipher cipher, int data_unit_size)
> 
> Why not make key_size and data_unit_size unsigned?

No reason other than that 'int' is fewer characters and is a good default when
no other particular type is warranted.  But I can change them to 'unsigned int'
if people prefer to make it clearer that they can't be negative.

> 
> > +{
> > +       struct qcom_scm_desc desc = {
> > +               .svc = QCOM_SCM_SVC_ES,
> > +               .cmd = QCOM_SCM_ES_CONFIG_SET_ICE_KEY,
> > +               .arginfo = QCOM_SCM_ARGS(5, QCOM_SCM_VAL, QCOM_SCM_RW,
> > +                                        QCOM_SCM_VAL, QCOM_SCM_VAL,
> > +                                        QCOM_SCM_VAL),
> > +               .args[0] = index,
> > +               .args[2] = key_size,
> > +               .args[3] = cipher,
> > +               .args[4] = data_unit_size,
> > +               .owner = ARM_SMCCC_OWNER_SIP,
> > +       };
> > +       u8 *keybuf;
> > +       dma_addr_t key_phys;
> > +       int ret;
> > +
> > +       keybuf = kmemdup(key, key_size, GFP_KERNEL);
> 
> Is this to make the key physically contiguous? Probably worth a comment
> to help others understand why this is here.

Yes, dma_map_single() requires physically contiguous memory.  I'll add a
comment.

> 
> > +       if (!keybuf)
> > +               return -ENOMEM;
> > +
> > +       key_phys = dma_map_single(__scm->dev, keybuf, key_size, DMA_TO_DEVICE);
> > +       if (dma_mapping_error(__scm->dev, key_phys)) {
> > +               ret = -ENOMEM;
> > +               goto out;
> > +       }
> > +       desc.args[1] = key_phys;
> > +
> > +       ret = qcom_scm_call(__scm->dev, &desc, NULL);
> > +
> > +       dma_unmap_single(__scm->dev, key_phys, key_size, DMA_TO_DEVICE);
> > +out:
> > +       kzfree(keybuf);
> 
> And this is because we want to clear key contents out of the slab? What
> about if the dma_map_single() bounces to a bounce buffer? I think that
> isn't going to happen because __scm->dev is just some firmware device
> that doesn't require bounce buffers but it's worth another comment to
> clarify this.

Yes, in crypto-related code we always try to wipe keys after use.  I don't think
a bounce buffer would actually be used here, though it would be preferable to
wipe the DMA memory too so that we don't rely on that.  But I didn't see how to
do that; I'm not a DMA API expert.  Maybe dma_alloc_coherent()?  This isn't
really performance-critical.

- Eric
diff mbox series

Patch

diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
index 059bb0fbae9e..7fb9f606250f 100644
--- a/drivers/firmware/qcom_scm.c
+++ b/drivers/firmware/qcom_scm.c
@@ -9,6 +9,7 @@ 
 #include <linux/dma-direct.h>
 #include <linux/dma-mapping.h>
 #include <linux/module.h>
+#include <linux/slab.h>
 #include <linux/types.h>
 #include <linux/qcom_scm.h>
 #include <linux/of.h>
@@ -926,6 +927,101 @@  int qcom_scm_ocmem_unlock(enum qcom_scm_ocmem_client id, u32 offset, u32 size)
 }
 EXPORT_SYMBOL(qcom_scm_ocmem_unlock);
 
+/**
+ * qcom_scm_ice_available() - Is the ICE key programming interface available?
+ *
+ * Return: true iff the SCM calls wrapped by qcom_scm_ice_invalidate_key() and
+ *	   qcom_scm_ice_set_key() are available.
+ */
+bool qcom_scm_ice_available(void)
+{
+	return __qcom_scm_is_call_available(__scm->dev, QCOM_SCM_SVC_ES,
+					    QCOM_SCM_ES_INVALIDATE_ICE_KEY) &&
+		__qcom_scm_is_call_available(__scm->dev, QCOM_SCM_SVC_ES,
+					     QCOM_SCM_ES_CONFIG_SET_ICE_KEY);
+}
+EXPORT_SYMBOL(qcom_scm_ice_available);
+
+/**
+ * qcom_scm_ice_invalidate_key() - Invalidate an inline encryption key
+ * @index: the keyslot to invalidate
+ *
+ * The UFSHCI standard defines a standard way to do this, but it doesn't work on
+ * these SoCs; only this SCM call does.
+ *
+ * Return: 0 on success; -errno on failure.
+ */
+int qcom_scm_ice_invalidate_key(u32 index)
+{
+	struct qcom_scm_desc desc = {
+		.svc = QCOM_SCM_SVC_ES,
+		.cmd = QCOM_SCM_ES_INVALIDATE_ICE_KEY,
+		.arginfo = QCOM_SCM_ARGS(1),
+		.args[0] = index,
+		.owner = ARM_SMCCC_OWNER_SIP,
+	};
+
+	return qcom_scm_call(__scm->dev, &desc, NULL);
+}
+EXPORT_SYMBOL(qcom_scm_ice_invalidate_key);
+
+/**
+ * qcom_scm_ice_set_key() - Set an inline encryption key
+ * @index: the keyslot into which to set the key
+ * @key: the key to program
+ * @key_size: the size of the key in bytes
+ * @cipher: the encryption algorithm the key is for
+ * @data_unit_size: the encryption data unit size, i.e. the size of each
+ *		    individual plaintext and ciphertext.  Given in 512-byte
+ *		    units, e.g. 1 = 512 bytes, 8 = 4096 bytes, etc.
+ *
+ * Program a key into a keyslot of Qualcomm ICE (Inline Crypto Engine), where it
+ * can then be used to encrypt/decrypt UFS I/O requests inline.
+ *
+ * The UFSHCI standard defines a standard way to do this, but it doesn't work on
+ * these SoCs; only this SCM call does.
+ *
+ * Return: 0 on success; -errno on failure.
+ */
+int qcom_scm_ice_set_key(u32 index, const u8 *key, int key_size,
+			 enum qcom_scm_ice_cipher cipher, int data_unit_size)
+{
+	struct qcom_scm_desc desc = {
+		.svc = QCOM_SCM_SVC_ES,
+		.cmd = QCOM_SCM_ES_CONFIG_SET_ICE_KEY,
+		.arginfo = QCOM_SCM_ARGS(5, QCOM_SCM_VAL, QCOM_SCM_RW,
+					 QCOM_SCM_VAL, QCOM_SCM_VAL,
+					 QCOM_SCM_VAL),
+		.args[0] = index,
+		.args[2] = key_size,
+		.args[3] = cipher,
+		.args[4] = data_unit_size,
+		.owner = ARM_SMCCC_OWNER_SIP,
+	};
+	u8 *keybuf;
+	dma_addr_t key_phys;
+	int ret;
+
+	keybuf = kmemdup(key, key_size, GFP_KERNEL);
+	if (!keybuf)
+		return -ENOMEM;
+
+	key_phys = dma_map_single(__scm->dev, keybuf, key_size, DMA_TO_DEVICE);
+	if (dma_mapping_error(__scm->dev, key_phys)) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	desc.args[1] = key_phys;
+
+	ret = qcom_scm_call(__scm->dev, &desc, NULL);
+
+	dma_unmap_single(__scm->dev, key_phys, key_size, DMA_TO_DEVICE);
+out:
+	kzfree(keybuf);
+	return ret;
+}
+EXPORT_SYMBOL(qcom_scm_ice_set_key);
+
 /**
  * qcom_scm_hdcp_available() - Check if secure environment supports HDCP.
  *
diff --git a/drivers/firmware/qcom_scm.h b/drivers/firmware/qcom_scm.h
index d9ed670da222..38ea614d29fe 100644
--- a/drivers/firmware/qcom_scm.h
+++ b/drivers/firmware/qcom_scm.h
@@ -103,6 +103,10 @@  extern int scm_legacy_call(struct device *dev, const struct qcom_scm_desc *desc,
 #define QCOM_SCM_OCMEM_LOCK_CMD		0x01
 #define QCOM_SCM_OCMEM_UNLOCK_CMD	0x02
 
+#define QCOM_SCM_SVC_ES			0x10	/* Enterprise Security */
+#define QCOM_SCM_ES_INVALIDATE_ICE_KEY	0x03
+#define QCOM_SCM_ES_CONFIG_SET_ICE_KEY	0x04
+
 #define QCOM_SCM_SVC_HDCP		0x11
 #define QCOM_SCM_HDCP_INVOKE		0x01
 
diff --git a/include/linux/qcom_scm.h b/include/linux/qcom_scm.h
index 3d6a24697761..8ca90f192aeb 100644
--- a/include/linux/qcom_scm.h
+++ b/include/linux/qcom_scm.h
@@ -44,6 +44,13 @@  enum qcom_scm_sec_dev_id {
 	QCOM_SCM_ICE_DEV_ID     = 20,
 };
 
+enum qcom_scm_ice_cipher {
+	QCOM_SCM_ICE_CIPHER_AES_128_XTS = 0,
+	QCOM_SCM_ICE_CIPHER_AES_128_CBC = 1,
+	QCOM_SCM_ICE_CIPHER_AES_256_XTS = 3,
+	QCOM_SCM_ICE_CIPHER_AES_256_CBC = 4,
+};
+
 #define QCOM_SCM_VMID_HLOS       0x3
 #define QCOM_SCM_VMID_MSS_MSA    0xF
 #define QCOM_SCM_VMID_WLAN       0x18
@@ -88,6 +95,12 @@  extern int qcom_scm_ocmem_lock(enum qcom_scm_ocmem_client id, u32 offset,
 extern int qcom_scm_ocmem_unlock(enum qcom_scm_ocmem_client id, u32 offset,
 				 u32 size);
 
+extern bool qcom_scm_ice_available(void);
+extern int qcom_scm_ice_invalidate_key(u32 index);
+extern int qcom_scm_ice_set_key(u32 index, const u8 *key, int key_size,
+				enum qcom_scm_ice_cipher cipher,
+				int data_unit_size);
+
 extern bool qcom_scm_hdcp_available(void);
 extern int qcom_scm_hdcp_req(struct qcom_scm_hdcp_req *req, u32 req_cnt,
 			     u32 *resp);
@@ -138,6 +151,12 @@  static inline int qcom_scm_ocmem_lock(enum qcom_scm_ocmem_client id, u32 offset,
 static inline int qcom_scm_ocmem_unlock(enum qcom_scm_ocmem_client id,
 		u32 offset, u32 size) { return -ENODEV; }
 
+static inline bool qcom_scm_ice_available(void) { return false; }
+static inline int qcom_scm_ice_invalidate_key(u32 index) { return -ENODEV; }
+static inline int qcom_scm_ice_set_key(u32 index, const u8 *key, int key_size,
+				       enum qcom_scm_ice_cipher cipher,
+				       int data_unit_size) { return -ENODEV; }
+
 static inline bool qcom_scm_hdcp_available(void) { return false; }
 static inline int qcom_scm_hdcp_req(struct qcom_scm_hdcp_req *req, u32 req_cnt,
 		u32 *resp) { return -ENODEV; }