2 files changed, 101 insertions, 19 deletions

diff --git a/Documentation/security/keys-ecryptfs.txt b/Documentation/security/keys-ecryptfs.txt
new file mode 100644
index 00000000000..c3bbeba6356
--- /dev/null
+++ b/Documentation/security/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
diff --git a/Documentation/security/keys-trusted-encrypted.txt b/Documentation/security/keys-trusted-encrypted.txt
index 8fb79bc1ac4..5f50ccabfc8 100644
--- a/Documentation/security/keys-trusted-encrypted.txt
+++ b/Documentation/security/keys-trusted-encrypted.txt
@@ -53,12 +53,19 @@ they are only as secure as the user key encrypting them.  The master user key
 should therefore be loaded in as secure a way as possible, preferably early in
 boot.
 
+The decrypted portion of encrypted keys can contain either a simple symmetric
+key or a more complex structure. The format of the more complex structure is
+application specific, which is identified by 'format'.
+
 Usage:
-  keyctl add encrypted name "new key-type:master-key-name keylen" ring
-  keyctl add encrypted name "load hex_blob" ring
-  keyctl update keyid "update key-type:master-key-name"
+    keyctl add encrypted name "new [format] key-type:master-key-name keylen"
+        ring
+    keyctl add encrypted name "load hex_blob" ring
+    keyctl update keyid "update key-type:master-key-name"
+
+format:= 'default | ecryptfs'
+key-type:= 'trusted' | 'user'
 
-where 'key-type' is either 'trusted' or 'user'.
 
 Examples of trusted and encrypted key usage:
 
@@ -114,15 +121,25 @@ Reseal a trusted key under new pcr values:
     7ef6a24defe4846104209bf0c3eced7fa1a672ed5b125fc9d8cd88b476a658a4434644ef
     df8ae9a178e9f83ba9f08d10fa47e4226b98b0702f06b3b8
 
-Create and save an encrypted key "evm" using the above trusted key "kmk":
+The initial consumer of trusted keys is EVM, which at boot time needs a high
+quality symmetric key for HMAC protection of file metadata.  The use of a
+trusted key provides strong guarantees that the EVM key has not been
+compromised by a user level problem, and when sealed to specific boot PCR
+values, protects against boot and offline attacks.  Create and save an
+encrypted key "evm" using the above trusted key "kmk":
 
+option 1: omitting 'format'
     $ keyctl add encrypted evm "new trusted:kmk 32" @u
     159771175
 
+option 2: explicitly defining 'format' as 'default'
+    $ keyctl add encrypted evm "new default trusted:kmk 32" @u
+    159771175
+
     $ keyctl print 159771175
-    trusted:kmk 32 2375725ad57798846a9bbd240de8906f006e66c03af53b1b382dbbc55
-    be2a44616e4959430436dc4f2a7a9659aa60bb4652aeb2120f149ed197c564e024717c64
-    5972dcb82ab2dde83376d82b2e3c09ffc
+    default trusted:kmk 32 2375725ad57798846a9bbd240de8906f006e66c03af53b1b3
+    82dbbc55be2a44616e4959430436dc4f2a7a9659aa60bb4652aeb2120f149ed197c564e0
+    24717c64 5972dcb82ab2dde83376d82b2e3c09ffc
 
     $ keyctl pipe 159771175 > evm.blob
 
@@ -132,14 +149,11 @@ Load an encrypted key "evm" from saved blob:
     831684262
 
     $ keyctl print 831684262
-    trusted:kmk 32 2375725ad57798846a9bbd240de8906f006e66c03af53b1b382dbbc55
-    be2a44616e4959430436dc4f2a7a9659aa60bb4652aeb2120f149ed197c564e024717c64
-    5972dcb82ab2dde83376d82b2e3c09ffc
-
-
-The initial consumer of trusted keys is EVM, which at boot time needs a high
-quality symmetric key for HMAC protection of file metadata.  The use of a
-trusted key provides strong guarantees that the EVM key has not been
-compromised by a user level problem, and when sealed to specific boot PCR
-values, protects against boot and offline attacks.  Other uses for trusted and
-encrypted keys, such as for disk and file encryption are anticipated.
+    default trusted:kmk 32 2375725ad57798846a9bbd240de8906f006e66c03af53b1b3
+    82dbbc55be2a44616e4959430436dc4f2a7a9659aa60bb4652aeb2120f149ed197c564e0
+    24717c64 5972dcb82ab2dde83376d82b2e3c09ffc
+
+Other uses for trusted and encrypted keys, such as for disk and file encryption
+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'.