Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1043 insertions, 0 deletions

diff --git a/security/keys/encrypted-keys/encrypted.c b/security/keys/encrypted-keys/encrypted.c
new file mode 100644
index 0000000000..1e313982af
--- /dev/null
+++ b/security/keys/encrypted-keys/encrypted.c
@@ -0,0 +1,1043 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2010 IBM Corporation
+ * Copyright (C) 2010 Politecnico di Torino, Italy
+ *                    TORSEC group -- https://security.polito.it
+ *
+ * Authors:
+ * Mimi Zohar <zohar@us.ibm.com>
+ * Roberto Sassu <roberto.sassu@polito.it>
+ *
+ * See Documentation/security/keys/trusted-encrypted.rst
+ */
+
+#include <linux/uaccess.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/parser.h>
+#include <linux/string.h>
+#include <linux/err.h>
+#include <keys/user-type.h>
+#include <keys/trusted-type.h>
+#include <keys/encrypted-type.h>
+#include <linux/key-type.h>
+#include <linux/random.h>
+#include <linux/rcupdate.h>
+#include <linux/scatterlist.h>
+#include <linux/ctype.h>
+#include <crypto/aes.h>
+#include <crypto/algapi.h>
+#include <crypto/hash.h>
+#include <crypto/sha2.h>
+#include <crypto/skcipher.h>
+
+#include "encrypted.h"
+#include "ecryptfs_format.h"
+
+static const char KEY_TRUSTED_PREFIX[] = "trusted:";
+static const char KEY_USER_PREFIX[] = "user:";
+static const char hash_alg[] = "sha256";
+static const char hmac_alg[] = "hmac(sha256)";
+static const char blkcipher_alg[] = "cbc(aes)";
+static const char key_format_default[] = "default";
+static const char key_format_ecryptfs[] = "ecryptfs";
+static const char key_format_enc32[] = "enc32";
+static unsigned int ivsize;
+static int blksize;
+
+#define KEY_TRUSTED_PREFIX_LEN (sizeof (KEY_TRUSTED_PREFIX) - 1)
+#define KEY_USER_PREFIX_LEN (sizeof (KEY_USER_PREFIX) - 1)
+#define KEY_ECRYPTFS_DESC_LEN 16
+#define HASH_SIZE SHA256_DIGEST_SIZE
+#define MAX_DATA_SIZE 4096
+#define MIN_DATA_SIZE  20
+#define KEY_ENC32_PAYLOAD_LEN 32
+
+static struct crypto_shash *hash_tfm;
+
+enum {
+	Opt_new, Opt_load, Opt_update, Opt_err
+};
+
+enum {
+	Opt_default, Opt_ecryptfs, Opt_enc32, Opt_error
+};
+
+static const match_table_t key_format_tokens = {
+	{Opt_default, "default"},
+	{Opt_ecryptfs, "ecryptfs"},
+	{Opt_enc32, "enc32"},
+	{Opt_error, NULL}
+};
+
+static const match_table_t key_tokens = {
+	{Opt_new, "new"},
+	{Opt_load, "load"},
+	{Opt_update, "update"},
+	{Opt_err, NULL}
+};
+
+static bool user_decrypted_data = IS_ENABLED(CONFIG_USER_DECRYPTED_DATA);
+module_param(user_decrypted_data, bool, 0);
+MODULE_PARM_DESC(user_decrypted_data,
+	"Allow instantiation of encrypted keys using provided decrypted data");
+
+static int aes_get_sizes(void)
+{
+	struct crypto_skcipher *tfm;
+
+	tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
+	if (IS_ERR(tfm)) {
+		pr_err("encrypted_key: failed to alloc_cipher (%ld)\n",
+		       PTR_ERR(tfm));
+		return PTR_ERR(tfm);
+	}
+	ivsize = crypto_skcipher_ivsize(tfm);
+	blksize = crypto_skcipher_blocksize(tfm);
+	crypto_free_skcipher(tfm);
+	return 0;
+}
+
+/*
+ * valid_ecryptfs_desc - verify the description of a new/loaded encrypted key
+ *
+ * The description of a encrypted key with format 'ecryptfs' must contain
+ * exactly 16 hexadecimal characters.
+ *
+ */
+static int valid_ecryptfs_desc(const char *ecryptfs_desc)
+{
+	int i;
+
+	if (strlen(ecryptfs_desc) != KEY_ECRYPTFS_DESC_LEN) {
+		pr_err("encrypted_key: key description must be %d hexadecimal "
+		       "characters long\n", KEY_ECRYPTFS_DESC_LEN);
+		return -EINVAL;
+	}
+
+	for (i = 0; i < KEY_ECRYPTFS_DESC_LEN; i++) {
+		if (!isxdigit(ecryptfs_desc[i])) {
+			pr_err("encrypted_key: key description must contain "
+			       "only hexadecimal characters\n");
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * valid_master_desc - verify the 'key-type:desc' of a new/updated master-key
+ *
+ * key-type:= "trusted:" | "user:"
+ * desc:= master-key description
+ *
+ * Verify that 'key-type' is valid and that 'desc' exists. On key update,
+ * only the master key description is permitted to change, not the key-type.
+ * The key-type remains constant.
+ *
+ * On success returns 0, otherwise -EINVAL.
+ */
+static int valid_master_desc(const char *new_desc, const char *orig_desc)
+{
+	int prefix_len;
+
+	if (!strncmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN))
+		prefix_len = KEY_TRUSTED_PREFIX_LEN;
+	else if (!strncmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN))
+		prefix_len = KEY_USER_PREFIX_LEN;
+	else
+		return -EINVAL;
+
+	if (!new_desc[prefix_len])
+		return -EINVAL;
+
+	if (orig_desc && strncmp(new_desc, orig_desc, prefix_len))
+		return -EINVAL;
+
+	return 0;
+}
+
+/*
+ * datablob_parse - parse the keyctl data
+ *
+ * datablob format:
+ * new [<format>] <master-key name> <decrypted data length> [<decrypted data>]
+ * load [<format>] <master-key name> <decrypted data length>
+ *     <encrypted iv + data>
+ * update <new-master-key name>
+ *
+ * Tokenizes a copy of the keyctl data, returning a pointer to each token,
+ * which is null terminated.
+ *
+ * On success returns 0, otherwise -EINVAL.
+ */
+static int datablob_parse(char *datablob, const char **format,
+			  char **master_desc, char **decrypted_datalen,
+			  char **hex_encoded_iv, char **decrypted_data)
+{
+	substring_t args[MAX_OPT_ARGS];
+	int ret = -EINVAL;
+	int key_cmd;
+	int key_format;
+	char *p, *keyword;
+
+	keyword = strsep(&datablob, " \t");
+	if (!keyword) {
+		pr_info("encrypted_key: insufficient parameters specified\n");
+		return ret;
+	}
+	key_cmd = match_token(keyword, key_tokens, args);
+
+	/* Get optional format: default | ecryptfs */
+	p = strsep(&datablob, " \t");
+	if (!p) {
+		pr_err("encrypted_key: insufficient parameters specified\n");
+		return ret;
+	}
+
+	key_format = match_token(p, key_format_tokens, args);
+	switch (key_format) {
+	case Opt_ecryptfs:
+	case Opt_enc32:
+	case Opt_default:
+		*format = p;
+		*master_desc = strsep(&datablob, " \t");
+		break;
+	case Opt_error:
+		*master_desc = p;
+		break;
+	}
+
+	if (!*master_desc) {
+		pr_info("encrypted_key: master key parameter is missing\n");
+		goto out;
+	}
+
+	if (valid_master_desc(*master_desc, NULL) < 0) {
+		pr_info("encrypted_key: master key parameter \'%s\' "
+			"is invalid\n", *master_desc);
+		goto out;
+	}
+
+	if (decrypted_datalen) {
+		*decrypted_datalen = strsep(&datablob, " \t");
+		if (!*decrypted_datalen) {
+			pr_info("encrypted_key: keylen parameter is missing\n");
+			goto out;
+		}
+	}
+
+	switch (key_cmd) {
+	case Opt_new:
+		if (!decrypted_datalen) {
+			pr_info("encrypted_key: keyword \'%s\' not allowed "
+				"when called from .update method\n", keyword);
+			break;
+		}
+		*decrypted_data = strsep(&datablob, " \t");
+		ret = 0;
+		break;
+	case Opt_load:
+		if (!decrypted_datalen) {
+			pr_info("encrypted_key: keyword \'%s\' not allowed "
+				"when called from .update method\n", keyword);
+			break;
+		}
+		*hex_encoded_iv = strsep(&datablob, " \t");
+		if (!*hex_encoded_iv) {
+			pr_info("encrypted_key: hex blob is missing\n");
+			break;
+		}
+		ret = 0;
+		break;
+	case Opt_update:
+		if (decrypted_datalen) {
+			pr_info("encrypted_key: keyword \'%s\' not allowed "
+				"when called from .instantiate method\n",
+				keyword);
+			break;
+		}
+		ret = 0;
+		break;
+	case Opt_err:
+		pr_info("encrypted_key: keyword \'%s\' not recognized\n",
+			keyword);
+		break;
+	}
+out:
+	return ret;
+}
+
+/*
+ * datablob_format - format as an ascii string, before copying to userspace
+ */
+static char *datablob_format(struct encrypted_key_payload *epayload,
+			     size_t asciiblob_len)
+{
+	char *ascii_buf, *bufp;
+	u8 *iv = epayload->iv;
+	int len;
+	int i;
+
+	ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL);
+	if (!ascii_buf)
+		goto out;
+
+	ascii_buf[asciiblob_len] = '\0';
+
+	/* copy datablob master_desc and datalen strings */
+	len = sprintf(ascii_buf, "%s %s %s ", epayload->format,
+		      epayload->master_desc, epayload->datalen);
+
+	/* convert the hex encoded iv, encrypted-data and HMAC to ascii */
+	bufp = &ascii_buf[len];
+	for (i = 0; i < (asciiblob_len - len) / 2; i++)
+		bufp = hex_byte_pack(bufp, iv[i]);
+out:
+	return ascii_buf;
+}
+
+/*
+ * request_user_key - request the user key
+ *
+ * Use a user provided key to encrypt/decrypt an encrypted-key.
+ */
+static struct key *request_user_key(const char *master_desc, const u8 **master_key,
+				    size_t *master_keylen)
+{
+	const struct user_key_payload *upayload;
+	struct key *ukey;
+
+	ukey = request_key(&key_type_user, master_desc, NULL);
+	if (IS_ERR(ukey))
+		goto error;
+
+	down_read(&ukey->sem);
+	upayload = user_key_payload_locked(ukey);
+	if (!upayload) {
+		/* key was revoked before we acquired its semaphore */
+		up_read(&ukey->sem);
+		key_put(ukey);
+		ukey = ERR_PTR(-EKEYREVOKED);
+		goto error;
+	}
+	*master_key = upayload->data;
+	*master_keylen = upayload->datalen;
+error:
+	return ukey;
+}
+
+static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen,
+		     const u8 *buf, unsigned int buflen)
+{
+	struct crypto_shash *tfm;
+	int err;
+
+	tfm = crypto_alloc_shash(hmac_alg, 0, 0);
+	if (IS_ERR(tfm)) {
+		pr_err("encrypted_key: can't alloc %s transform: %ld\n",
+		       hmac_alg, PTR_ERR(tfm));
+		return PTR_ERR(tfm);
+	}
+
+	err = crypto_shash_setkey(tfm, key, keylen);
+	if (!err)
+		err = crypto_shash_tfm_digest(tfm, buf, buflen, digest);
+	crypto_free_shash(tfm);
+	return err;
+}
+
+enum derived_key_type { ENC_KEY, AUTH_KEY };
+
+/* Derive authentication/encryption key from trusted key */
+static int get_derived_key(u8 *derived_key, enum derived_key_type key_type,
+			   const u8 *master_key, size_t master_keylen)
+{
+	u8 *derived_buf;
+	unsigned int derived_buf_len;
+	int ret;
+
+	derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen;
+	if (derived_buf_len < HASH_SIZE)
+		derived_buf_len = HASH_SIZE;
+
+	derived_buf = kzalloc(derived_buf_len, GFP_KERNEL);
+	if (!derived_buf)
+		return -ENOMEM;
+
+	if (key_type)
+		strcpy(derived_buf, "AUTH_KEY");
+	else
+		strcpy(derived_buf, "ENC_KEY");
+
+	memcpy(derived_buf + strlen(derived_buf) + 1, master_key,
+	       master_keylen);
+	ret = crypto_shash_tfm_digest(hash_tfm, derived_buf, derived_buf_len,
+				      derived_key);
+	kfree_sensitive(derived_buf);
+	return ret;
+}
+
+static struct skcipher_request *init_skcipher_req(const u8 *key,
+						  unsigned int key_len)
+{
+	struct skcipher_request *req;
+	struct crypto_skcipher *tfm;
+	int ret;
+
+	tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
+	if (IS_ERR(tfm)) {
+		pr_err("encrypted_key: failed to load %s transform (%ld)\n",
+		       blkcipher_alg, PTR_ERR(tfm));
+		return ERR_CAST(tfm);
+	}
+
+	ret = crypto_skcipher_setkey(tfm, key, key_len);
+	if (ret < 0) {
+		pr_err("encrypted_key: failed to setkey (%d)\n", ret);
+		crypto_free_skcipher(tfm);
+		return ERR_PTR(ret);
+	}
+
+	req = skcipher_request_alloc(tfm, GFP_KERNEL);
+	if (!req) {
+		pr_err("encrypted_key: failed to allocate request for %s\n",
+		       blkcipher_alg);
+		crypto_free_skcipher(tfm);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	skcipher_request_set_callback(req, 0, NULL, NULL);
+	return req;
+}
+
+static struct key *request_master_key(struct encrypted_key_payload *epayload,
+				      const u8 **master_key, size_t *master_keylen)
+{
+	struct key *mkey = ERR_PTR(-EINVAL);
+
+	if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX,
+		     KEY_TRUSTED_PREFIX_LEN)) {
+		mkey = request_trusted_key(epayload->master_desc +
+					   KEY_TRUSTED_PREFIX_LEN,
+					   master_key, master_keylen);
+	} else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX,
+			    KEY_USER_PREFIX_LEN)) {
+		mkey = request_user_key(epayload->master_desc +
+					KEY_USER_PREFIX_LEN,
+					master_key, master_keylen);
+	} else
+		goto out;
+
+	if (IS_ERR(mkey)) {
+		int ret = PTR_ERR(mkey);
+
+		if (ret == -ENOTSUPP)
+			pr_info("encrypted_key: key %s not supported",
+				epayload->master_desc);
+		else
+			pr_info("encrypted_key: key %s not found",
+				epayload->master_desc);
+		goto out;
+	}
+
+	dump_master_key(*master_key, *master_keylen);
+out:
+	return mkey;
+}
+
+/* Before returning data to userspace, encrypt decrypted data. */
+static int derived_key_encrypt(struct encrypted_key_payload *epayload,
+			       const u8 *derived_key,
+			       unsigned int derived_keylen)
+{
+	struct scatterlist sg_in[2];
+	struct scatterlist sg_out[1];
+	struct crypto_skcipher *tfm;
+	struct skcipher_request *req;
+	unsigned int encrypted_datalen;
+	u8 iv[AES_BLOCK_SIZE];
+	int ret;
+
+	encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
+
+	req = init_skcipher_req(derived_key, derived_keylen);
+	ret = PTR_ERR(req);
+	if (IS_ERR(req))
+		goto out;
+	dump_decrypted_data(epayload);
+
+	sg_init_table(sg_in, 2);
+	sg_set_buf(&sg_in[0], epayload->decrypted_data,
+		   epayload->decrypted_datalen);
+	sg_set_page(&sg_in[1], ZERO_PAGE(0), AES_BLOCK_SIZE, 0);
+
+	sg_init_table(sg_out, 1);
+	sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen);
+
+	memcpy(iv, epayload->iv, sizeof(iv));
+	skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv);
+	ret = crypto_skcipher_encrypt(req);
+	tfm = crypto_skcipher_reqtfm(req);
+	skcipher_request_free(req);
+	crypto_free_skcipher(tfm);
+	if (ret < 0)
+		pr_err("encrypted_key: failed to encrypt (%d)\n", ret);
+	else
+		dump_encrypted_data(epayload, encrypted_datalen);
+out:
+	return ret;
+}
+
+static int datablob_hmac_append(struct encrypted_key_payload *epayload,
+				const u8 *master_key, size_t master_keylen)
+{
+	u8 derived_key[HASH_SIZE];
+	u8 *digest;
+	int ret;
+
+	ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
+	if (ret < 0)
+		goto out;
+
+	digest = epayload->format + epayload->datablob_len;
+	ret = calc_hmac(digest, derived_key, sizeof derived_key,
+			epayload->format, epayload->datablob_len);
+	if (!ret)
+		dump_hmac(NULL, digest, HASH_SIZE);
+out:
+	memzero_explicit(derived_key, sizeof(derived_key));
+	return ret;
+}
+
+/* verify HMAC before decrypting encrypted key */
+static int datablob_hmac_verify(struct encrypted_key_payload *epayload,
+				const u8 *format, const u8 *master_key,
+				size_t master_keylen)
+{
+	u8 derived_key[HASH_SIZE];
+	u8 digest[HASH_SIZE];
+	int ret;
+	char *p;
+	unsigned short len;
+
+	ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
+	if (ret < 0)
+		goto out;
+
+	len = epayload->datablob_len;
+	if (!format) {
+		p = epayload->master_desc;
+		len -= strlen(epayload->format) + 1;
+	} else
+		p = epayload->format;
+
+	ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len);
+	if (ret < 0)
+		goto out;
+	ret = crypto_memneq(digest, epayload->format + epayload->datablob_len,
+			    sizeof(digest));
+	if (ret) {
+		ret = -EINVAL;
+		dump_hmac("datablob",
+			  epayload->format + epayload->datablob_len,
+			  HASH_SIZE);
+		dump_hmac("calc", digest, HASH_SIZE);
+	}
+out:
+	memzero_explicit(derived_key, sizeof(derived_key));
+	return ret;
+}
+
+static int derived_key_decrypt(struct encrypted_key_payload *epayload,
+			       const u8 *derived_key,
+			       unsigned int derived_keylen)
+{
+	struct scatterlist sg_in[1];
+	struct scatterlist sg_out[2];
+	struct crypto_skcipher *tfm;
+	struct skcipher_request *req;
+	unsigned int encrypted_datalen;
+	u8 iv[AES_BLOCK_SIZE];
+	u8 *pad;
+	int ret;
+
+	/* Throwaway buffer to hold the unused zero padding at the end */
+	pad = kmalloc(AES_BLOCK_SIZE, GFP_KERNEL);
+	if (!pad)
+		return -ENOMEM;
+
+	encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
+	req = init_skcipher_req(derived_key, derived_keylen);
+	ret = PTR_ERR(req);
+	if (IS_ERR(req))
+		goto out;
+	dump_encrypted_data(epayload, encrypted_datalen);
+
+	sg_init_table(sg_in, 1);
+	sg_init_table(sg_out, 2);
+	sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen);
+	sg_set_buf(&sg_out[0], epayload->decrypted_data,
+		   epayload->decrypted_datalen);
+	sg_set_buf(&sg_out[1], pad, AES_BLOCK_SIZE);
+
+	memcpy(iv, epayload->iv, sizeof(iv));
+	skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv);
+	ret = crypto_skcipher_decrypt(req);
+	tfm = crypto_skcipher_reqtfm(req);
+	skcipher_request_free(req);
+	crypto_free_skcipher(tfm);
+	if (ret < 0)
+		goto out;
+	dump_decrypted_data(epayload);
+out:
+	kfree(pad);
+	return ret;
+}
+
+/* Allocate memory for decrypted key and datablob. */
+static struct encrypted_key_payload *encrypted_key_alloc(struct key *key,
+							 const char *format,
+							 const char *master_desc,
+							 const char *datalen,
+							 const char *decrypted_data)
+{
+	struct encrypted_key_payload *epayload = NULL;
+	unsigned short datablob_len;
+	unsigned short decrypted_datalen;
+	unsigned short payload_datalen;
+	unsigned int encrypted_datalen;
+	unsigned int format_len;
+	long dlen;
+	int i;
+	int ret;
+
+	ret = kstrtol(datalen, 10, &dlen);
+	if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE)
+		return ERR_PTR(-EINVAL);
+
+	format_len = (!format) ? strlen(key_format_default) : strlen(format);
+	decrypted_datalen = dlen;
+	payload_datalen = decrypted_datalen;
+
+	if (decrypted_data) {
+		if (!user_decrypted_data) {
+			pr_err("encrypted key: instantiation of keys using provided decrypted data is disabled since CONFIG_USER_DECRYPTED_DATA is set to false\n");
+			return ERR_PTR(-EINVAL);
+		}
+		if (strlen(decrypted_data) != decrypted_datalen * 2) {
+			pr_err("encrypted key: decrypted data provided does not match decrypted data length provided\n");
+			return ERR_PTR(-EINVAL);
+		}
+		for (i = 0; i < strlen(decrypted_data); i++) {
+			if (!isxdigit(decrypted_data[i])) {
+				pr_err("encrypted key: decrypted data provided must contain only hexadecimal characters\n");
+				return ERR_PTR(-EINVAL);
+			}
+		}
+	}
+
+	if (format) {
+		if (!strcmp(format, key_format_ecryptfs)) {
+			if (dlen != ECRYPTFS_MAX_KEY_BYTES) {
+				pr_err("encrypted_key: keylen for the ecryptfs format must be equal to %d bytes\n",
+					ECRYPTFS_MAX_KEY_BYTES);
+				return ERR_PTR(-EINVAL);
+			}
+			decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES;
+			payload_datalen = sizeof(struct ecryptfs_auth_tok);
+		} else if (!strcmp(format, key_format_enc32)) {
+			if (decrypted_datalen != KEY_ENC32_PAYLOAD_LEN) {
+				pr_err("encrypted_key: enc32 key payload incorrect length: %d\n",
+						decrypted_datalen);
+				return ERR_PTR(-EINVAL);
+			}
+		}
+	}
+
+	encrypted_datalen = roundup(decrypted_datalen, blksize);
+
+	datablob_len = format_len + 1 + strlen(master_desc) + 1
+	    + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen;
+
+	ret = key_payload_reserve(key, payload_datalen + datablob_len
+				  + HASH_SIZE + 1);
+	if (ret < 0)
+		return ERR_PTR(ret);
+
+	epayload = kzalloc(sizeof(*epayload) + payload_datalen +
+			   datablob_len + HASH_SIZE + 1, GFP_KERNEL);
+	if (!epayload)
+		return ERR_PTR(-ENOMEM);
+
+	epayload->payload_datalen = payload_datalen;
+	epayload->decrypted_datalen = decrypted_datalen;
+	epayload->datablob_len = datablob_len;
+	return epayload;
+}
+
+static int encrypted_key_decrypt(struct encrypted_key_payload *epayload,
+				 const char *format, const char *hex_encoded_iv)
+{
+	struct key *mkey;
+	u8 derived_key[HASH_SIZE];
+	const u8 *master_key;
+	u8 *hmac;
+	const char *hex_encoded_data;
+	unsigned int encrypted_datalen;
+	size_t master_keylen;
+	size_t asciilen;
+	int ret;
+
+	encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
+	asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2;
+	if (strlen(hex_encoded_iv) != asciilen)
+		return -EINVAL;
+
+	hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2;
+	ret = hex2bin(epayload->iv, hex_encoded_iv, ivsize);
+	if (ret < 0)
+		return -EINVAL;
+	ret = hex2bin(epayload->encrypted_data, hex_encoded_data,
+		      encrypted_datalen);
+	if (ret < 0)
+		return -EINVAL;
+
+	hmac = epayload->format + epayload->datablob_len;
+	ret = hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2),
+		      HASH_SIZE);
+	if (ret < 0)
+		return -EINVAL;
+
+	mkey = request_master_key(epayload, &master_key, &master_keylen);
+	if (IS_ERR(mkey))
+		return PTR_ERR(mkey);
+
+	ret = datablob_hmac_verify(epayload, format, master_key, master_keylen);
+	if (ret < 0) {
+		pr_err("encrypted_key: bad hmac (%d)\n", ret);
+		goto out;
+	}
+
+	ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
+	if (ret < 0)
+		goto out;
+
+	ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key);
+	if (ret < 0)
+		pr_err("encrypted_key: failed to decrypt key (%d)\n", ret);
+out:
+	up_read(&mkey->sem);
+	key_put(mkey);
+	memzero_explicit(derived_key, sizeof(derived_key));
+	return ret;
+}
+
+static void __ekey_init(struct encrypted_key_payload *epayload,
+			const char *format, const char *master_desc,
+			const char *datalen)
+{
+	unsigned int format_len;
+
+	format_len = (!format) ? strlen(key_format_default) : strlen(format);
+	epayload->format = epayload->payload_data + epayload->payload_datalen;
+	epayload->master_desc = epayload->format + format_len + 1;
+	epayload->datalen = epayload->master_desc + strlen(master_desc) + 1;
+	epayload->iv = epayload->datalen + strlen(datalen) + 1;
+	epayload->encrypted_data = epayload->iv + ivsize + 1;
+	epayload->decrypted_data = epayload->payload_data;
+
+	if (!format)
+		memcpy(epayload->format, key_format_default, format_len);
+	else {
+		if (!strcmp(format, key_format_ecryptfs))
+			epayload->decrypted_data =
+				ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data);
+
+		memcpy(epayload->format, format, format_len);
+	}
+
+	memcpy(epayload->master_desc, master_desc, strlen(master_desc));
+	memcpy(epayload->datalen, datalen, strlen(datalen));
+}
+
+/*
+ * encrypted_init - initialize an encrypted key
+ *
+ * For a new key, use either a random number or user-provided decrypted data in
+ * case it is provided. A random number is used for the iv in both cases. For
+ * an old key, decrypt the hex encoded data.
+ */
+static int encrypted_init(struct encrypted_key_payload *epayload,
+			  const char *key_desc, const char *format,
+			  const char *master_desc, const char *datalen,
+			  const char *hex_encoded_iv, const char *decrypted_data)
+{
+	int ret = 0;
+
+	if (format && !strcmp(format, key_format_ecryptfs)) {
+		ret = valid_ecryptfs_desc(key_desc);
+		if (ret < 0)
+			return ret;
+
+		ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data,
+				       key_desc);
+	}
+
+	__ekey_init(epayload, format, master_desc, datalen);
+	if (hex_encoded_iv) {
+		ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv);
+	} else if (decrypted_data) {
+		get_random_bytes(epayload->iv, ivsize);
+		ret = hex2bin(epayload->decrypted_data, decrypted_data,
+			      epayload->decrypted_datalen);
+	} else {
+		get_random_bytes(epayload->iv, ivsize);
+		get_random_bytes(epayload->decrypted_data, epayload->decrypted_datalen);
+	}
+	return ret;
+}
+
+/*
+ * encrypted_instantiate - instantiate an encrypted key
+ *
+ * Instantiates the key:
+ * - by decrypting an existing encrypted datablob, or
+ * - by creating a new encrypted key based on a kernel random number, or
+ * - using provided decrypted data.
+ *
+ * On success, return 0. Otherwise return errno.
+ */
+static int encrypted_instantiate(struct key *key,
+				 struct key_preparsed_payload *prep)
+{
+	struct encrypted_key_payload *epayload = NULL;
+	char *datablob = NULL;
+	const char *format = NULL;
+	char *master_desc = NULL;
+	char *decrypted_datalen = NULL;
+	char *hex_encoded_iv = NULL;
+	char *decrypted_data = NULL;
+	size_t datalen = prep->datalen;
+	int ret;
+
+	if (datalen <= 0 || datalen > 32767 || !prep->data)
+		return -EINVAL;
+
+	datablob = kmalloc(datalen + 1, GFP_KERNEL);
+	if (!datablob)
+		return -ENOMEM;
+	datablob[datalen] = 0;
+	memcpy(datablob, prep->data, datalen);
+	ret = datablob_parse(datablob, &format, &master_desc,
+			     &decrypted_datalen, &hex_encoded_iv, &decrypted_data);
+	if (ret < 0)
+		goto out;
+
+	epayload = encrypted_key_alloc(key, format, master_desc,
+				       decrypted_datalen, decrypted_data);
+	if (IS_ERR(epayload)) {
+		ret = PTR_ERR(epayload);
+		goto out;
+	}
+	ret = encrypted_init(epayload, key->description, format, master_desc,
+			     decrypted_datalen, hex_encoded_iv, decrypted_data);
+	if (ret < 0) {
+		kfree_sensitive(epayload);
+		goto out;
+	}
+
+	rcu_assign_keypointer(key, epayload);
+out:
+	kfree_sensitive(datablob);
+	return ret;
+}
+
+static void encrypted_rcu_free(struct rcu_head *rcu)
+{
+	struct encrypted_key_payload *epayload;
+
+	epayload = container_of(rcu, struct encrypted_key_payload, rcu);
+	kfree_sensitive(epayload);
+}
+
+/*
+ * encrypted_update - update the master key description
+ *
+ * Change the master key description for an existing encrypted key.
+ * The next read will return an encrypted datablob using the new
+ * master key description.
+ *
+ * On success, return 0. Otherwise return errno.
+ */
+static int encrypted_update(struct key *key, struct key_preparsed_payload *prep)
+{
+	struct encrypted_key_payload *epayload = key->payload.data[0];
+	struct encrypted_key_payload *new_epayload;
+	char *buf;
+	char *new_master_desc = NULL;
+	const char *format = NULL;
+	size_t datalen = prep->datalen;
+	int ret = 0;
+
+	if (key_is_negative(key))
+		return -ENOKEY;
+	if (datalen <= 0 || datalen > 32767 || !prep->data)
+		return -EINVAL;
+
+	buf = kmalloc(datalen + 1, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	buf[datalen] = 0;
+	memcpy(buf, prep->data, datalen);
+	ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL, NULL);
+	if (ret < 0)
+		goto out;
+
+	ret = valid_master_desc(new_master_desc, epayload->master_desc);
+	if (ret < 0)
+		goto out;
+
+	new_epayload = encrypted_key_alloc(key, epayload->format,
+					   new_master_desc, epayload->datalen, NULL);
+	if (IS_ERR(new_epayload)) {
+		ret = PTR_ERR(new_epayload);
+		goto out;
+	}
+
+	__ekey_init(new_epayload, epayload->format, new_master_desc,
+		    epayload->datalen);
+
+	memcpy(new_epayload->iv, epayload->iv, ivsize);
+	memcpy(new_epayload->payload_data, epayload->payload_data,
+	       epayload->payload_datalen);
+
+	rcu_assign_keypointer(key, new_epayload);
+	call_rcu(&epayload->rcu, encrypted_rcu_free);
+out:
+	kfree_sensitive(buf);
+	return ret;
+}
+
+/*
+ * encrypted_read - format and copy out the encrypted data
+ *
+ * The resulting datablob format is:
+ * <master-key name> <decrypted data length> <encrypted iv> <encrypted data>
+ *
+ * On success, return to userspace the encrypted key datablob size.
+ */
+static long encrypted_read(const struct key *key, char *buffer,
+			   size_t buflen)
+{
+	struct encrypted_key_payload *epayload;
+	struct key *mkey;
+	const u8 *master_key;
+	size_t master_keylen;
+	char derived_key[HASH_SIZE];
+	char *ascii_buf;
+	size_t asciiblob_len;
+	int ret;
+
+	epayload = dereference_key_locked(key);
+
+	/* returns the hex encoded iv, encrypted-data, and hmac as ascii */
+	asciiblob_len = epayload->datablob_len + ivsize + 1
+	    + roundup(epayload->decrypted_datalen, blksize)
+	    + (HASH_SIZE * 2);
+
+	if (!buffer || buflen < asciiblob_len)
+		return asciiblob_len;
+
+	mkey = request_master_key(epayload, &master_key, &master_keylen);
+	if (IS_ERR(mkey))
+		return PTR_ERR(mkey);
+
+	ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
+	if (ret < 0)
+		goto out;
+
+	ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key);
+	if (ret < 0)
+		goto out;
+
+	ret = datablob_hmac_append(epayload, master_key, master_keylen);
+	if (ret < 0)
+		goto out;
+
+	ascii_buf = datablob_format(epayload, asciiblob_len);
+	if (!ascii_buf) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	up_read(&mkey->sem);
+	key_put(mkey);
+	memzero_explicit(derived_key, sizeof(derived_key));
+
+	memcpy(buffer, ascii_buf, asciiblob_len);
+	kfree_sensitive(ascii_buf);
+
+	return asciiblob_len;
+out:
+	up_read(&mkey->sem);
+	key_put(mkey);
+	memzero_explicit(derived_key, sizeof(derived_key));
+	return ret;
+}
+
+/*
+ * encrypted_destroy - clear and free the key's payload
+ */
+static void encrypted_destroy(struct key *key)
+{
+	kfree_sensitive(key->payload.data[0]);
+}
+
+struct key_type key_type_encrypted = {
+	.name = "encrypted",
+	.instantiate = encrypted_instantiate,
+	.update = encrypted_update,
+	.destroy = encrypted_destroy,
+	.describe = user_describe,
+	.read = encrypted_read,
+};
+EXPORT_SYMBOL_GPL(key_type_encrypted);
+
+static int __init init_encrypted(void)
+{
+	int ret;
+
+	hash_tfm = crypto_alloc_shash(hash_alg, 0, 0);
+	if (IS_ERR(hash_tfm)) {
+		pr_err("encrypted_key: can't allocate %s transform: %ld\n",
+		       hash_alg, PTR_ERR(hash_tfm));
+		return PTR_ERR(hash_tfm);
+	}
+
+	ret = aes_get_sizes();
+	if (ret < 0)
+		goto out;
+	ret = register_key_type(&key_type_encrypted);
+	if (ret < 0)
+		goto out;
+	return 0;
+out:
+	crypto_free_shash(hash_tfm);
+	return ret;
+
+}
+
+static void __exit cleanup_encrypted(void)
+{
+	crypto_free_shash(hash_tfm);
+	unregister_key_type(&key_type_encrypted);
+}
+
+late_initcall(init_encrypted);
+module_exit(cleanup_encrypted);
+
+MODULE_LICENSE("GPL");