---

yaml
---
r: 260912
b: refs/heads/master
c: 79a73d1
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: f8f8527103a264b5e4ab2ce5c1743b28f3219d90
+refs/heads/master: 79a73d188726b473ca3bf483244bc96096831905

trunk/Documentation/keys-ecryptfs.txt

@@ -0,0 +1,68 @@
+		Encrypted keys for the eCryptfs filesystem
+
+ECryptfs is a stacked filesystem which transparently encrypts and decrypts each
+file using a randomly generated File Encryption Key (FEK).
+
+Each FEK is in turn encrypted with a File Encryption Key Encryption Key (FEFEK)
+either in kernel space or in user space with a daemon called 'ecryptfsd'.  In
+the former case the operation is performed directly by the kernel CryptoAPI
+using a key, the FEFEK, derived from a user prompted passphrase;  in the latter
+the FEK is encrypted by 'ecryptfsd' with the help of external libraries in order
+to support other mechanisms like public key cryptography, PKCS#11 and TPM based
+operations.
+
+The data structure defined by eCryptfs to contain information required for the
+FEK decryption is called authentication token and, currently, can be stored in a
+kernel key of the 'user' type, inserted in the user's session specific keyring
+by the userspace utility 'mount.ecryptfs' shipped with the package
+'ecryptfs-utils'.
+
+The 'encrypted' key type has been extended with the introduction of the new
+format 'ecryptfs' in order to be used in conjunction with the eCryptfs
+filesystem.  Encrypted keys of the newly introduced format store an
+authentication token in its payload with a FEFEK randomly generated by the
+kernel and protected by the parent master key.
+
+In order to avoid known-plaintext attacks, the datablob obtained through
+commands 'keyctl print' or 'keyctl pipe' does not contain the overall
+authentication token, which content is well known, but only the FEFEK in
+encrypted form.
+
+The eCryptfs filesystem may really benefit from using encrypted keys in that the
+required key can be securely generated by an Administrator and provided at boot
+time after the unsealing of a 'trusted' key in order to perform the mount in a
+controlled environment.  Another advantage is that the key is not exposed to
+threats of malicious software, because it is available in clear form only at
+kernel level.
+
+Usage:
+   keyctl add encrypted name "new ecryptfs key-type:master-key-name keylen" ring
+   keyctl add encrypted name "load hex_blob" ring
+   keyctl update keyid "update key-type:master-key-name"
+
+name:= '<16 hexadecimal characters>'
+key-type:= 'trusted' | 'user'
+keylen:= 64
+
+
+Example of encrypted key usage with the eCryptfs filesystem:
+
+Create an encrypted key "1000100010001000" of length 64 bytes with format
+'ecryptfs' and save it using a previously loaded user key "test":
+
+    $ keyctl add encrypted 1000100010001000 "new ecryptfs user:test 64" @u
+    19184530
+
+    $ keyctl print 19184530
+    ecryptfs user:test 64 490045d4bfe48c99f0d465fbbbb79e7500da954178e2de0697
+    dd85091f5450a0511219e9f7cd70dcd498038181466f78ac8d4c19504fcc72402bfc41c2
+    f253a41b7507ccaa4b2b03fff19a69d1cc0b16e71746473f023a95488b6edfd86f7fdd40
+    9d292e4bacded1258880122dd553a661
+
+    $ keyctl pipe 19184530 > ecryptfs.blob
+
+Mount an eCryptfs filesystem using the created encrypted key "1000100010001000"
+into the '/secret' directory:
+
+    $ mount -i -t ecryptfs -oecryptfs_sig=1000100010001000,\
+      ecryptfs_cipher=aes,ecryptfs_key_bytes=32 /secret /secret

trunk/Documentation/security/keys-trusted-encrypted.txt

@@ -63,7 +63,7 @@ Usage:
     keyctl add encrypted name "load hex_blob" ring
     keyctl update keyid "update key-type:master-key-name"
 
-format:= 'default'
+format:= 'default | ecryptfs'
 key-type:= 'trusted' | 'user'
 
 
@@ -154,4 +154,6 @@ Load an encrypted key "evm" from saved blob:
     24717c64 5972dcb82ab2dde83376d82b2e3c09ffc
 
 Other uses for trusted and encrypted keys, such as for disk and file encryption
-are anticipated.
+are anticipated.  In particular the new format 'ecryptfs' has been defined in
+in order to use encrypted keys to mount an eCryptfs filesystem.  More details
+about the usage can be found in the file 'Documentation/keys-ecryptfs.txt'.

trunk/security/keys/Makefile

@@ -14,7 +14,7 @@ obj-y := \
 	user_defined.o
 
 obj-$(CONFIG_TRUSTED_KEYS) += trusted.o
-obj-$(CONFIG_ENCRYPTED_KEYS) += encrypted.o
+obj-$(CONFIG_ENCRYPTED_KEYS) += ecryptfs_format.o encrypted.o
 obj-$(CONFIG_KEYS_COMPAT) += compat.o
 obj-$(CONFIG_PROC_FS) += proc.o
 obj-$(CONFIG_SYSCTL) += sysctl.o

trunk/security/keys/ecryptfs_format.c

@@ -0,0 +1,81 @@
+/*
+ * ecryptfs_format.c: helper functions for the encrypted key type
+ *
+ * Copyright (C) 2006 International Business Machines Corp.
+ * Copyright (C) 2010 Politecnico di Torino, Italy
+ *                    TORSEC group -- http://security.polito.it
+ *
+ * Authors:
+ * Michael A. Halcrow <mahalcro@us.ibm.com>
+ * Tyler Hicks <tyhicks@ou.edu>
+ * Roberto Sassu <roberto.sassu@polito.it>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 2 of the License.
+ */
+
+#include <linux/module.h>
+#include "ecryptfs_format.h"
+
+u8 *ecryptfs_get_auth_tok_key(struct ecryptfs_auth_tok *auth_tok)
+{
+	return auth_tok->token.password.session_key_encryption_key;
+}
+EXPORT_SYMBOL(ecryptfs_get_auth_tok_key);
+
+/*
+ * ecryptfs_get_versions()
+ *
+ * Source code taken from the software 'ecryptfs-utils' version 83.
+ *
+ */
+void ecryptfs_get_versions(int *major, int *minor, int *file_version)
+{
+	*major = ECRYPTFS_VERSION_MAJOR;
+	*minor = ECRYPTFS_VERSION_MINOR;
+	if (file_version)
+		*file_version = ECRYPTFS_SUPPORTED_FILE_VERSION;
+}
+EXPORT_SYMBOL(ecryptfs_get_versions);
+
+/*
+ * ecryptfs_fill_auth_tok - fill the ecryptfs_auth_tok structure
+ *
+ * Fill the ecryptfs_auth_tok structure with required ecryptfs data.
+ * The source code is inspired to the original function generate_payload()
+ * shipped with the software 'ecryptfs-utils' version 83.
+ *
+ */
+int ecryptfs_fill_auth_tok(struct ecryptfs_auth_tok *auth_tok,
+			   const char *key_desc)
+{
+	int major, minor;
+
+	ecryptfs_get_versions(&major, &minor, NULL);
+	auth_tok->version = (((uint16_t)(major << 8) & 0xFF00)
+			     | ((uint16_t)minor & 0x00FF));
+	auth_tok->token_type = ECRYPTFS_PASSWORD;
+	strncpy((char *)auth_tok->token.password.signature, key_desc,
+		ECRYPTFS_PASSWORD_SIG_SIZE);
+	auth_tok->token.password.session_key_encryption_key_bytes =
+		ECRYPTFS_MAX_KEY_BYTES;
+	/*
+	 * Removed auth_tok->token.password.salt and
+	 * auth_tok->token.password.session_key_encryption_key
+	 * initialization from the original code
+	 */
+	/* TODO: Make the hash parameterizable via policy */
+	auth_tok->token.password.flags |=
+		ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET;
+	/* The kernel code will encrypt the session key. */
+	auth_tok->session_key.encrypted_key[0] = 0;
+	auth_tok->session_key.encrypted_key_size = 0;
+	/* Default; subject to change by kernel eCryptfs */
+	auth_tok->token.password.hash_algo = PGP_DIGEST_ALGO_SHA512;
+	auth_tok->token.password.flags &= ~(ECRYPTFS_PERSISTENT_PASSWORD);
+	return 0;
+}
+EXPORT_SYMBOL(ecryptfs_fill_auth_tok);
+
+MODULE_LICENSE("GPL");

trunk/security/keys/ecryptfs_format.h

@@ -0,0 +1,30 @@
+/*
+ * ecryptfs_format.h: helper functions for the encrypted key type
+ *
+ * Copyright (C) 2006 International Business Machines Corp.
+ * Copyright (C) 2010 Politecnico di Torino, Italy
+ *                    TORSEC group -- http://security.polito.it
+ *
+ * Authors:
+ * Michael A. Halcrow <mahalcro@us.ibm.com>
+ * Tyler Hicks <tyhicks@ou.edu>
+ * Roberto Sassu <roberto.sassu@polito.it>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 2 of the License.
+ */
+
+#ifndef __KEYS_ECRYPTFS_H
+#define __KEYS_ECRYPTFS_H
+
+#include <linux/ecryptfs.h>
+
+#define PGP_DIGEST_ALGO_SHA512   10
+
+u8 *ecryptfs_get_auth_tok_key(struct ecryptfs_auth_tok *auth_tok);
+void ecryptfs_get_versions(int *major, int *minor, int *file_version);
+int ecryptfs_fill_auth_tok(struct ecryptfs_auth_tok *auth_tok,
+			   const char *key_desc);
+
+#endif /* __KEYS_ECRYPTFS_H */

trunk/security/keys/encrypted.c

@@ -29,23 +29,27 @@
 #include <linux/rcupdate.h>
 #include <linux/scatterlist.h>
 #include <linux/crypto.h>
+#include <linux/ctype.h>
 #include <crypto/hash.h>
 #include <crypto/sha.h>
 #include <crypto/aes.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 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
@@ -63,11 +67,12 @@ enum {
 };
 
 enum {
-	Opt_error = -1, Opt_default
+	Opt_error = -1, Opt_default, Opt_ecryptfs
 };
 
 static const match_table_t key_format_tokens = {
 	{Opt_default, "default"},
+	{Opt_ecryptfs, "ecryptfs"},
 	{Opt_error, NULL}
 };
 
@@ -94,6 +99,34 @@ static int aes_get_sizes(void)
 	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
  *
@@ -158,7 +191,7 @@ static int datablob_parse(char *datablob, const char **format,
 	}
 	key_cmd = match_token(keyword, key_tokens, args);
 
-	/* Get optional format: default */
+	/* Get optional format: default | ecryptfs */
 	p = strsep(&datablob, " \t");
 	if (!p) {
 		pr_err("encrypted_key: insufficient parameters specified\n");
@@ -167,6 +200,7 @@ static int datablob_parse(char *datablob, const char **format,
 
 	key_format = match_token(p, key_format_tokens, args);
 	switch (key_format) {
+	case Opt_ecryptfs:
 	case Opt_default:
 		*format = p;
 		*master_desc = strsep(&datablob, " \t");
@@ -601,6 +635,17 @@ static struct encrypted_key_payload *encrypted_key_alloc(struct key *key,
 	format_len = (!format) ? strlen(key_format_default) : strlen(format);
 	decrypted_datalen = dlen;
 	payload_datalen = decrypted_datalen;
+	if (format && !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);
+	}
+
 	encrypted_datalen = roundup(decrypted_datalen, blksize);
 
 	datablob_len = format_len + 1 + strlen(master_desc) + 1
@@ -686,8 +731,14 @@ static void __ekey_init(struct encrypted_key_payload *epayload,
 
 	if (!format)
 		memcpy(epayload->format, key_format_default, format_len);
-	else
+	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));
 }
@@ -699,11 +750,21 @@ static void __ekey_init(struct encrypted_key_payload *epayload,
  * itself.  For an old key, decrypt the hex encoded data.
  */
 static int encrypted_init(struct encrypted_key_payload *epayload,
-			  const char *format, const char *master_desc,
-			  const char *datalen, const char *hex_encoded_iv)
+			  const char *key_desc, const char *format,
+			  const char *master_desc, const char *datalen,
+			  const char *hex_encoded_iv)
 {
 	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) {
 		get_random_bytes(epayload->iv, ivsize);
@@ -753,8 +814,8 @@ static int encrypted_instantiate(struct key *key, const void *data,
 		ret = PTR_ERR(epayload);
 		goto out;
 	}
-	ret = encrypted_init(epayload, format, master_desc, decrypted_datalen,
-			     hex_encoded_iv);
+	ret = encrypted_init(epayload, key->description, format, master_desc,
+			     decrypted_datalen, hex_encoded_iv);
 	if (ret < 0) {
 		kfree(epayload);
 		goto out;