[v4,07/11] PM: hibernate: Add kernel-based encryption

diff --git a/Documentation/power/userland-swsusp.rst b/Documentation/power/userland-swsusp.rst
index 1cf62d80a9ca10..f759915a78ce98 100644
--- a/Documentation/power/userland-swsusp.rst
+++ b/Documentation/power/userland-swsusp.rst
@@ -115,6 +115,14 @@  SNAPSHOT_S2RAM
 	to resume the system from RAM if there's enough battery power or restore
 	its state on the basis of the saved suspend image otherwise)
 
+SNAPSHOT_ENABLE_ENCRYPTION
+	Enables encryption of the hibernate image within the kernel. Upon suspend
+	(ie when the snapshot device was opened for reading), returns a blob
+	representing the random encryption key the kernel created to encrypt the
+	hibernate image with. Upon resume (ie when the snapshot device was opened
+	for writing), receives a blob from usermode containing the key material
+	previously returned during hibernate.
+
 The device's read() operation can be used to transfer the snapshot image from
 the kernel.  It has the following limitations:
 
diff --git a/include/uapi/linux/suspend_ioctls.h b/include/uapi/linux/suspend_ioctls.h
index bcce04e21c0dce..b73026ef824bb9 100644
--- a/include/uapi/linux/suspend_ioctls.h
+++ b/include/uapi/linux/suspend_ioctls.h
@@ -13,6 +13,18 @@  struct resume_swap_area {
 	__u32 dev;
 } __attribute__((packed));
 
+#define USWSUSP_KEY_NONCE_SIZE 16
+
+/*
+ * This structure is used to pass the kernel's hibernate encryption key in
+ * either direction.
+ */
+struct uswsusp_key_blob {
+	__u32 blob_len;
+	__u8 blob[512];
+	__u8 nonce[USWSUSP_KEY_NONCE_SIZE];
+} __attribute__((packed));
+
 #define SNAPSHOT_IOC_MAGIC	'3'
 #define SNAPSHOT_FREEZE			_IO(SNAPSHOT_IOC_MAGIC, 1)
 #define SNAPSHOT_UNFREEZE		_IO(SNAPSHOT_IOC_MAGIC, 2)
@@ -29,6 +41,7 @@  struct resume_swap_area {
 #define SNAPSHOT_PREF_IMAGE_SIZE	_IO(SNAPSHOT_IOC_MAGIC, 18)
 #define SNAPSHOT_AVAIL_SWAP_SIZE	_IOR(SNAPSHOT_IOC_MAGIC, 19, __kernel_loff_t)
 #define SNAPSHOT_ALLOC_SWAP_PAGE	_IOR(SNAPSHOT_IOC_MAGIC, 20, __kernel_loff_t)
-#define SNAPSHOT_IOC_MAXNR	20
+#define SNAPSHOT_ENABLE_ENCRYPTION	_IOWR(SNAPSHOT_IOC_MAGIC, 21, struct uswsusp_key_blob)
+#define SNAPSHOT_IOC_MAXNR	21
 
 #endif /* _LINUX_SUSPEND_IOCTLS_H */
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index 60a1d3051cc79a..cd574af0b43379 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -92,6 +92,19 @@  config HIBERNATION_SNAPSHOT_DEV
 
 	  If in doubt, say Y.
 
+config ENCRYPTED_HIBERNATION
+	bool "Encryption support for userspace snapshots"
+	depends on HIBERNATION_SNAPSHOT_DEV
+	depends on CRYPTO_AEAD2=y
+	default n
+	help
+	  Enable support for kernel-based encryption of hibernation snapshots
+	  created by uswsusp tools.
+
+	  Say N if userspace handles the image encryption.
+
+	  If in doubt, say N.
+
 config PM_STD_PARTITION
 	string "Default resume partition"
 	depends on HIBERNATION
diff --git a/kernel/power/Makefile b/kernel/power/Makefile
index 874ad834dc8daf..7be08f2e0e3b68 100644
--- a/kernel/power/Makefile
+++ b/kernel/power/Makefile
@@ -16,6 +16,7 @@  obj-$(CONFIG_SUSPEND)		+= suspend.o
 obj-$(CONFIG_PM_TEST_SUSPEND)	+= suspend_test.o
 obj-$(CONFIG_HIBERNATION)	+= hibernate.o snapshot.o swap.o
 obj-$(CONFIG_HIBERNATION_SNAPSHOT_DEV) += user.o
+obj-$(CONFIG_ENCRYPTED_HIBERNATION) += snapenc.o
 obj-$(CONFIG_PM_AUTOSLEEP)	+= autosleep.o
 obj-$(CONFIG_PM_WAKELOCKS)	+= wakelock.o
 
diff --git a/kernel/power/snapenc.c b/kernel/power/snapenc.c
new file mode 100644
index 00000000000000..f215df16dad4d3
--- /dev/null
+++ b/kernel/power/snapenc.c
@@ -0,0 +1,493 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+/* This file provides encryption support for system snapshots. */
+
+#include <linux/crypto.h>
+#include <crypto/aead.h>
+#include <crypto/gcm.h>
+#include <linux/random.h>
+#include <linux/mm.h>
+#include <linux/uaccess.h>
+
+#include "power.h"
+#include "user.h"
+
+/* Encrypt more data from the snapshot into the staging area. */
+static int snapshot_encrypt_refill(struct snapshot_data *data)
+{
+
+	struct aead_request *req = data->aead_req;
+	u8 nonce[GCM_AES_IV_SIZE];
+	DECLARE_CRYPTO_WAIT(wait);
+	size_t total = 0;
+	int pg_idx;
+	int res;
+
+	/*
+	 * The first buffer is the associated data, set to the offset to prevent
+	 * attacks that rearrange chunks.
+	 */
+	sg_set_buf(&data->sg[0], &data->crypt_total, sizeof(data->crypt_total));
+
+	/* Load the crypt buffer with snapshot pages. */
+	for (pg_idx = 0; pg_idx < CHUNK_SIZE; pg_idx++) {
+		void *buf = data->crypt_pages[pg_idx];
+
+		res = snapshot_read_next(&data->handle);
+		if (res < 0)
+			return res;
+		if (res == 0)
+			break;
+
+		WARN_ON(res != PAGE_SIZE);
+
+		/*
+		 * Copy the page into the staging area. A future optimization
+		 * could potentially skip this copy for lowmem pages.
+		 */
+		memcpy(buf, data_of(data->handle), PAGE_SIZE);
+		sg_set_buf(&data->sg[1 + pg_idx], buf, PAGE_SIZE);
+		total += PAGE_SIZE;
+	}
+
+	sg_set_buf(&data->sg[1 + pg_idx], &data->auth_tag, SNAPSHOT_AUTH_TAG_SIZE);
+	aead_request_set_callback(req, 0, crypto_req_done, &wait);
+	/*
+	 * Use incrementing nonces for each chunk, since a 64 bit value won't
+	 * roll into re-use for any given hibernate image.
+	 */
+	memcpy(&nonce[0], &data->nonce_low, sizeof(data->nonce_low));
+	memcpy(&nonce[sizeof(data->nonce_low)],
+	       &data->nonce_high,
+	       sizeof(nonce) - sizeof(data->nonce_low));
+
+	data->nonce_low += 1;
+	/* Total does not include AAD or the auth tag. */
+	aead_request_set_crypt(req, data->sg, data->sg, total, nonce);
+	res = crypto_wait_req(crypto_aead_encrypt(req), &wait);
+	if (res)
+		return res;
+
+	data->crypt_size = total;
+	data->crypt_total += total;
+	return 0;
+}
+
+/* Decrypt data from the staging area and push it to the snapshot. */
+static int snapshot_decrypt_drain(struct snapshot_data *data)
+{
+	struct aead_request *req = data->aead_req;
+	u8 nonce[GCM_AES_IV_SIZE];
+	DECLARE_CRYPTO_WAIT(wait);
+	int page_count;
+	size_t total;
+	int pg_idx;
+	int res;
+
+	/* Set up the associated data. */
+	sg_set_buf(&data->sg[0], &data->crypt_total, sizeof(data->crypt_total));
+
+	/*
+	 * Get the number of full pages, which could be short at the end. There
+	 * should also be a tag at the end, so the offset won't be an even page.
+	 */
+	page_count = data->crypt_offset >> PAGE_SHIFT;
+	total = page_count << PAGE_SHIFT;
+	if ((total == 0) || (total == data->crypt_offset))
+		return -EINVAL;
+
+	/*
+	 * Load the sg list with the crypt buffer. Inline decrypt back into the
+	 * staging buffer. A future optimization could decrypt directly into
+	 * lowmem pages.
+	 */
+	for (pg_idx = 0; pg_idx < page_count; pg_idx++)
+		sg_set_buf(&data->sg[1 + pg_idx], data->crypt_pages[pg_idx], PAGE_SIZE);
+
+	/*
+	 * It's possible this is the final decrypt, and there are fewer than
+	 * CHUNK_SIZE pages. If this is the case we would have just written the
+	 * auth tag into the first few bytes of a new page. Copy to the tag if
+	 * so.
+	 */
+	if ((page_count < CHUNK_SIZE) &&
+	    (data->crypt_offset - total) == sizeof(data->auth_tag)) {
+
+		memcpy(data->auth_tag,
+			data->crypt_pages[pg_idx],
+			sizeof(data->auth_tag));
+
+	} else if (data->crypt_offset !=
+		   ((CHUNK_SIZE << PAGE_SHIFT) + SNAPSHOT_AUTH_TAG_SIZE)) {
+
+		return -EINVAL;
+	}
+
+	sg_set_buf(&data->sg[1 + pg_idx], &data->auth_tag, SNAPSHOT_AUTH_TAG_SIZE);
+	aead_request_set_callback(req, 0, crypto_req_done, &wait);
+	memcpy(&nonce[0], &data->nonce_low, sizeof(data->nonce_low));
+	memcpy(&nonce[sizeof(data->nonce_low)],
+	       &data->nonce_high,
+	       sizeof(nonce) - sizeof(data->nonce_low));
+
+	data->nonce_low += 1;
+	aead_request_set_crypt(req, data->sg, data->sg, total + SNAPSHOT_AUTH_TAG_SIZE, nonce);
+	res = crypto_wait_req(crypto_aead_decrypt(req), &wait);
+	if (res)
+		return res;
+
+	data->crypt_size = 0;
+	data->crypt_offset = 0;
+
+	/* Push the decrypted pages further down the stack. */
+	total = 0;
+	for (pg_idx = 0; pg_idx < page_count; pg_idx++) {
+		void *buf = data->crypt_pages[pg_idx];
+
+		res = snapshot_write_next(&data->handle);
+		if (res < 0)
+			return res;
+		if (res == 0)
+			break;
+
+		if (!data_of(data->handle))
+			return -EINVAL;
+
+		WARN_ON(res != PAGE_SIZE);
+
+		/*
+		 * Copy the page into the staging area. A future optimization
+		 * could potentially skip this copy for lowmem pages.
+		 */
+		memcpy(data_of(data->handle), buf, PAGE_SIZE);
+		total += PAGE_SIZE;
+	}
+
+	data->crypt_total += total;
+	return 0;
+}
+
+static ssize_t snapshot_read_next_encrypted(struct snapshot_data *data,
+					    void **buf)
+{
+	size_t tag_off;
+
+	/* Refill the encrypted buffer if it's empty. */
+	if ((data->crypt_size == 0) ||
+	    (data->crypt_offset >=
+	     (data->crypt_size + SNAPSHOT_AUTH_TAG_SIZE))) {
+
+		int rc;
+
+		data->crypt_size = 0;
+		data->crypt_offset = 0;
+		rc = snapshot_encrypt_refill(data);
+		if (rc < 0)
+			return rc;
+	}
+
+	/* Return data pages if the offset is in that region. */
+	if (data->crypt_offset < data->crypt_size) {
+		size_t pg_idx = data->crypt_offset >> PAGE_SHIFT;
+		size_t pg_off = data->crypt_offset & (PAGE_SIZE - 1);
+		*buf = data->crypt_pages[pg_idx] + pg_off;
+		return PAGE_SIZE - pg_off;
+	}
+
+	/* Use offsets just beyond the size to return the tag. */
+	tag_off = data->crypt_offset - data->crypt_size;
+	if (tag_off > SNAPSHOT_AUTH_TAG_SIZE)
+		tag_off = SNAPSHOT_AUTH_TAG_SIZE;
+
+	*buf = data->auth_tag + tag_off;
+	return SNAPSHOT_AUTH_TAG_SIZE - tag_off;
+}
+
+static ssize_t snapshot_write_next_encrypted(struct snapshot_data *data,
+					     void **buf)
+{
+	size_t tag_off;
+
+	/* Return data pages if the offset is in that region. */
+	if (data->crypt_offset < (PAGE_SIZE * CHUNK_SIZE)) {
+		size_t pg_idx = data->crypt_offset >> PAGE_SHIFT;
+		size_t pg_off = data->crypt_offset & (PAGE_SIZE - 1);
+		*buf = data->crypt_pages[pg_idx] + pg_off;
+		return PAGE_SIZE - pg_off;
+	}
+
+	/* Use offsets just beyond the size to return the tag. */
+	tag_off = data->crypt_offset - (PAGE_SIZE * CHUNK_SIZE);
+	if (tag_off > SNAPSHOT_AUTH_TAG_SIZE)
+		tag_off = SNAPSHOT_AUTH_TAG_SIZE;
+
+	*buf = data->auth_tag + tag_off;
+	return SNAPSHOT_AUTH_TAG_SIZE - tag_off;
+}
+
+ssize_t snapshot_read_encrypted(struct snapshot_data *data,
+				char __user *buf, size_t count, loff_t *offp)
+{
+	ssize_t total = 0;
+
+	/* Loop getting buffers of varying sizes and copying to userspace. */
+	while (count) {
+		size_t copy_size;
+		size_t not_done;
+		void *src;
+		ssize_t src_size = snapshot_read_next_encrypted(data, &src);
+
+		if (src_size <= 0) {
+			if (total == 0)
+				return src_size;
+
+			break;
+		}
+
+		copy_size = min(count, (size_t)src_size);
+		not_done = copy_to_user(buf + total, src, copy_size);
+		copy_size -= not_done;
+		total += copy_size;
+		count -= copy_size;
+		data->crypt_offset += copy_size;
+		if (copy_size == 0) {
+			if (total == 0)
+				return -EFAULT;
+
+			break;
+		}
+	}
+
+	*offp += total;
+	return total;
+}
+
+ssize_t snapshot_write_encrypted(struct snapshot_data *data,
+				 const char __user *buf, size_t count,
+				 loff_t *offp)
+{
+	ssize_t total = 0;
+
+	/* Loop getting buffers of varying sizes and copying from. */
+	while (count) {
+		size_t copy_size;
+		size_t not_done;
+		void *dst;
+		ssize_t dst_size = snapshot_write_next_encrypted(data, &dst);
+
+		if (dst_size <= 0) {
+			if (total == 0)
+				return dst_size;
+
+			break;
+		}
+
+		copy_size = min(count, (size_t)dst_size);
+		not_done = copy_from_user(dst, buf + total, copy_size);
+		copy_size -= not_done;
+		total += copy_size;
+		count -= copy_size;
+		data->crypt_offset += copy_size;
+		if (copy_size == 0) {
+			if (total == 0)
+				return -EFAULT;
+
+			break;
+		}
+
+		/* Drain the encrypted buffer if it's full. */
+		if ((data->crypt_offset >=
+		    ((PAGE_SIZE * CHUNK_SIZE) + SNAPSHOT_AUTH_TAG_SIZE))) {
+
+			int rc;
+
+			rc = snapshot_decrypt_drain(data);
+			if (rc < 0)
+				return rc;
+		}
+	}
+
+	*offp += total;
+	return total;
+}
+
+void snapshot_teardown_encryption(struct snapshot_data *data)
+{
+	int i;
+
+	if (data->aead_req) {
+		aead_request_free(data->aead_req);
+		data->aead_req = NULL;
+	}
+
+	if (data->aead_tfm) {
+		crypto_free_aead(data->aead_tfm);
+		data->aead_tfm = NULL;
+	}
+
+	for (i = 0; i < CHUNK_SIZE; i++) {
+		if (data->crypt_pages[i]) {
+			free_page((unsigned long)data->crypt_pages[i]);
+			data->crypt_pages[i] = NULL;
+		}
+	}
+}
+
+static int snapshot_setup_encryption_common(struct snapshot_data *data)
+{
+	int i, rc;
+
+	data->crypt_total = 0;
+	data->crypt_offset = 0;
+	data->crypt_size = 0;
+	memset(data->crypt_pages, 0, sizeof(data->crypt_pages));
+	/* This only works once per hibernate. */
+	if (data->aead_tfm)
+		return -EINVAL;
+
+	/* Set up the encryption transform */
+	data->aead_tfm = crypto_alloc_aead("gcm(aes)", 0, 0);
+	if (IS_ERR(data->aead_tfm)) {
+		rc = PTR_ERR(data->aead_tfm);
+		data->aead_tfm = NULL;
+		return rc;
+	}
+
+	rc = -ENOMEM;
+	data->aead_req = aead_request_alloc(data->aead_tfm, GFP_KERNEL);
+	if (data->aead_req == NULL)
+		goto setup_fail;
+
+	/* Allocate the staging area */
+	for (i = 0; i < CHUNK_SIZE; i++) {
+		data->crypt_pages[i] = (void *)__get_free_page(GFP_ATOMIC);
+		if (data->crypt_pages[i] == NULL)
+			goto setup_fail;
+	}
+
+	sg_init_table(data->sg, CHUNK_SIZE + 2);
+
+	/*
+	 * The associated data will be the offset so that blocks can't be
+	 * rearranged.
+	 */
+	aead_request_set_ad(data->aead_req, sizeof(data->crypt_total));
+	rc = crypto_aead_setauthsize(data->aead_tfm, SNAPSHOT_AUTH_TAG_SIZE);
+	if (rc)
+		goto setup_fail;
+
+	return 0;
+
+setup_fail:
+	snapshot_teardown_encryption(data);
+	return rc;
+}
+
+int snapshot_get_encryption_key(struct snapshot_data *data,
+				struct uswsusp_key_blob __user *key)
+{
+	u8 aead_key[SNAPSHOT_ENCRYPTION_KEY_SIZE];
+	u8 nonce[USWSUSP_KEY_NONCE_SIZE];
+	int rc;
+
+	/* Don't pull a random key from a world that can be reset. */
+	if (data->ready)
+		return -EPIPE;
+
+	rc = snapshot_setup_encryption_common(data);
+	if (rc)
+		return rc;
+
+	/* Build a random starting nonce. */
+	get_random_bytes(nonce, sizeof(nonce));
+	memcpy(&data->nonce_low, &nonce[0], sizeof(data->nonce_low));
+	memcpy(&data->nonce_high, &nonce[8], sizeof(data->nonce_high));
+	/* Build a random key */
+	get_random_bytes(aead_key, sizeof(aead_key));
+	rc = crypto_aead_setkey(data->aead_tfm, aead_key, sizeof(aead_key));
+	if (rc)
+		goto fail;
+
+	/* Hand the key back to user mode (to be changed!) */
+	rc = put_user(sizeof(struct uswsusp_key_blob), &key->blob_len);
+	if (rc)
+		goto fail;
+
+	rc = copy_to_user(&key->blob, &aead_key, sizeof(aead_key));
+	if (rc)
+		goto fail;
+
+	rc = copy_to_user(&key->nonce, &nonce, sizeof(nonce));
+	if (rc)
+		goto fail;
+
+	return 0;
+
+fail:
+	snapshot_teardown_encryption(data);
+	return rc;
+}
+
+int snapshot_set_encryption_key(struct snapshot_data *data,
+				struct uswsusp_key_blob __user *key)
+{
+	struct uswsusp_key_blob blob;
+	int rc;
+
+	/* It's too late if data's been pushed in. */
+	if (data->handle.cur)
+		return -EPIPE;
+
+	rc = snapshot_setup_encryption_common(data);
+	if (rc)
+		return rc;
+
+	/* Load the key from user mode. */
+	rc = copy_from_user(&blob, key, sizeof(struct uswsusp_key_blob));
+	if (rc)
+		goto crypto_setup_fail;
+
+	if (blob.blob_len != sizeof(struct uswsusp_key_blob)) {
+		rc = -EINVAL;
+		goto crypto_setup_fail;
+	}
+
+	rc = crypto_aead_setkey(data->aead_tfm,
+				blob.blob,
+				SNAPSHOT_ENCRYPTION_KEY_SIZE);
+
+	if (rc)
+		goto crypto_setup_fail;
+
+	/* Load the starting nonce. */
+	memcpy(&data->nonce_low, &blob.nonce[0], sizeof(data->nonce_low));
+	memcpy(&data->nonce_high, &blob.nonce[8], sizeof(data->nonce_high));
+	return 0;
+
+crypto_setup_fail:
+	snapshot_teardown_encryption(data);
+	return rc;
+}
+
+loff_t snapshot_get_encrypted_image_size(loff_t raw_size)
+{
+	loff_t pages = raw_size >> PAGE_SHIFT;
+	loff_t chunks = (pages + (CHUNK_SIZE - 1)) / CHUNK_SIZE;
+	/*
+	 * The encrypted size is the normal size, plus a stitched in
+	 * authentication tag for every chunk of pages.
+	 */
+	return raw_size + (chunks * SNAPSHOT_AUTH_TAG_SIZE);
+}
+
+int snapshot_finalize_decrypted_image(struct snapshot_data *data)
+{
+	int rc;
+
+	if (data->crypt_offset != 0) {
+		rc = snapshot_decrypt_drain(data);
+		if (rc)
+			return rc;
+	}
+
+	return 0;
+}
diff --git a/kernel/power/user.c b/kernel/power/user.c
index 3a4e70366f354c..bba5cdbd2c0239 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -25,19 +25,10 @@ 
 #include <linux/uaccess.h>
 
 #include "power.h"
+#include "user.h"
 
 static bool need_wait;
-
-static struct snapshot_data {
-	struct snapshot_handle handle;
-	int swap;
-	int mode;
-	bool frozen;
-	bool ready;
-	bool platform_support;
-	bool free_bitmaps;
-	dev_t dev;
-} snapshot_state;
+struct snapshot_data snapshot_state;
 
 int is_hibernate_resume_dev(dev_t dev)
 {
@@ -122,6 +113,7 @@  static int snapshot_release(struct inode *inode, struct file *filp)
 	} else if (data->free_bitmaps) {
 		free_basic_memory_bitmaps();
 	}
+	snapshot_teardown_encryption(data);
 	pm_notifier_call_chain(data->mode == O_RDONLY ?
 			PM_POST_HIBERNATION : PM_POST_RESTORE);
 	hibernate_release();
@@ -146,6 +138,12 @@  static ssize_t snapshot_read(struct file *filp, char __user *buf,
 		res = -ENODATA;
 		goto Unlock;
 	}
+
+	if (snapshot_encryption_enabled(data)) {
+		res = snapshot_read_encrypted(data, buf, count, offp);
+		goto Unlock;
+	}
+
 	if (!pg_offp) { /* on page boundary? */
 		res = snapshot_read_next(&data->handle);
 		if (res <= 0)
@@ -182,6 +180,11 @@  static ssize_t snapshot_write(struct file *filp, const char __user *buf,
 
 	data = filp->private_data;
 
+	if (snapshot_encryption_enabled(data)) {
+		res = snapshot_write_encrypted(data, buf, count, offp);
+		goto unlock;
+	}
+
 	if (!pg_offp) {
 		res = snapshot_write_next(&data->handle);
 		if (res <= 0)
@@ -317,6 +320,12 @@  static long snapshot_ioctl(struct file *filp, unsigned int cmd,
 		break;
 
 	case SNAPSHOT_ATOMIC_RESTORE:
+		if (snapshot_encryption_enabled(data)) {
+			error = snapshot_finalize_decrypted_image(data);
+			if (error)
+				break;
+		}
+
 		snapshot_write_finalize(&data->handle);
 		if (data->mode != O_WRONLY || !data->frozen ||
 		    !snapshot_image_loaded(&data->handle)) {
@@ -352,6 +361,8 @@  static long snapshot_ioctl(struct file *filp, unsigned int cmd,
 		}
 		size = snapshot_get_image_size();
 		size <<= PAGE_SHIFT;
+		if (snapshot_encryption_enabled(data))
+			size = snapshot_get_encrypted_image_size(size);
 		error = put_user(size, (loff_t __user *)arg);
 		break;
 
@@ -409,6 +420,13 @@  static long snapshot_ioctl(struct file *filp, unsigned int cmd,
 		error = snapshot_set_swap_area(data, (void __user *)arg);
 		break;
 
+	case SNAPSHOT_ENABLE_ENCRYPTION:
+		if (data->mode == O_RDONLY)
+			error = snapshot_get_encryption_key(data, (void __user *)arg);
+		else
+			error = snapshot_set_encryption_key(data, (void __user *)arg);
+		break;
+
 	default:
 		error = -ENOTTY;
 
diff --git a/kernel/power/user.h b/kernel/power/user.h
new file mode 100644
index 00000000000000..ac429782abff85
--- /dev/null
+++ b/kernel/power/user.h
@@ -0,0 +1,103 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#include <linux/crypto.h>
+#include <crypto/aead.h>
+#include <crypto/aes.h>
+
+#define SNAPSHOT_ENCRYPTION_KEY_SIZE AES_KEYSIZE_128
+#define SNAPSHOT_AUTH_TAG_SIZE 16
+
+/* Define the number of pages in a single AEAD encryption chunk. */
+#define CHUNK_SIZE 16
+
+struct snapshot_data {
+	struct snapshot_handle handle;
+	int swap;
+	int mode;
+	bool frozen;
+	bool ready;
+	bool platform_support;
+	bool free_bitmaps;
+	dev_t dev;
+
+#if defined(CONFIG_ENCRYPTED_HIBERNATION)
+	struct crypto_aead *aead_tfm;
+	struct aead_request *aead_req;
+	void *crypt_pages[CHUNK_SIZE];
+	u8 auth_tag[SNAPSHOT_AUTH_TAG_SIZE];
+	struct scatterlist sg[CHUNK_SIZE + 2]; /* Add room for AD and auth tag. */
+	size_t crypt_offset;
+	size_t crypt_size;
+	uint64_t crypt_total;
+	uint64_t nonce_low;
+	uint64_t nonce_high;
+#endif
+
+};
+
+extern struct snapshot_data snapshot_state;
+
+/* kernel/power/swapenc.c routines */
+#if defined(CONFIG_ENCRYPTED_HIBERNATION)
+
+ssize_t snapshot_read_encrypted(struct snapshot_data *data,
+				char __user *buf, size_t count, loff_t *offp);
+
+ssize_t snapshot_write_encrypted(struct snapshot_data *data,
+				 const char __user *buf, size_t count,
+				 loff_t *offp);
+
+void snapshot_teardown_encryption(struct snapshot_data *data);
+int snapshot_get_encryption_key(struct snapshot_data *data,
+				struct uswsusp_key_blob __user *key);
+
+int snapshot_set_encryption_key(struct snapshot_data *data,
+				struct uswsusp_key_blob __user *key);
+
+loff_t snapshot_get_encrypted_image_size(loff_t raw_size);
+
+int snapshot_finalize_decrypted_image(struct snapshot_data *data);
+
+#define snapshot_encryption_enabled(data) (!!(data)->aead_tfm)
+
+#else
+
+ssize_t snapshot_read_encrypted(struct snapshot_data *data,
+				char __user *buf, size_t count, loff_t *offp)
+{
+	return -ENOTTY;
+}
+
+ssize_t snapshot_write_encrypted(struct snapshot_data *data,
+				 const char __user *buf, size_t count,
+				 loff_t *offp)
+{
+	return -ENOTTY;
+}
+
+static void snapshot_teardown_encryption(struct snapshot_data *data) {}
+static int snapshot_get_encryption_key(struct snapshot_data *data,
+				       struct uswsusp_key_blob __user *key)
+{
+	return -ENOTTY;
+}
+
+static int snapshot_set_encryption_key(struct snapshot_data *data,
+				       struct uswsusp_key_blob __user *key)
+{
+	return -ENOTTY;
+}
+
+static loff_t snapshot_get_encrypted_image_size(loff_t raw_size)
+{
+	return raw_size;
+}
+
+static int snapshot_finalize_decrypted_image(struct snapshot_data *data)
+{
+	return -ENOTTY;
+}
+
+#define snapshot_encryption_enabled(data) (0)
+
+#endif