4 files changed, 135 insertions, 3 deletions

diff --git a/Documentation/digsig.txt b/Documentation/digsig.txt
new file mode 100644
index 000000000000..3f682889068b
--- /dev/null
+++ b/Documentation/digsig.txt
@@ -0,0 +1,96 @@
+Digital Signature Verification API
+
+CONTENTS
+
+1. Introduction
+2. API
+3. User-space utilities
+
+
+1. Introduction
+
+Digital signature verification API provides a method to verify digital signature.
+Currently digital signatures are used by the IMA/EVM integrity protection subsystem.
+
+Digital signature verification is implemented using cut-down kernel port of
+GnuPG multi-precision integers (MPI) library. The kernel port provides
+memory allocation errors handling, has been refactored according to kernel
+coding style, and checkpatch.pl reported errors and warnings have been fixed.
+
+Public key and signature consist of header and MPIs.
+
+struct pubkey_hdr {
+        uint8_t         version;        /* key format version */
+        time_t          timestamp;      /* key made, always 0 for now */
+        uint8_t         algo;
+        uint8_t         nmpi;
+        char            mpi[0];
+} __packed;
+
+struct signature_hdr {
+        uint8_t         version;        /* signature format version */
+        time_t          timestamp;      /* signature made */
+        uint8_t         algo;
+        uint8_t         hash;
+        uint8_t         keyid[8];
+        uint8_t         nmpi;
+        char            mpi[0];
+} __packed;
+
+keyid equals to SHA1[12-19] over the total key content.
+Signature header is used as an input to generate a signature.
+Such approach insures that key or signature header could not be changed.
+It protects timestamp from been changed and can be used for rollback
+protection.
+
+2. API
+
+API currently includes only 1 function:
+
+        digsig_verify() - digital signature verification with public key
+
+
+/**
+ * digsig_verify() - digital signature verification with public key
+ * @keyring:    keyring to search key in
+ * @sig:        digital signature
+ * @sigen:      length of the signature
+ * @data:       data
+ * @datalen:    length of the data
+ * @return:     0 on success, -EINVAL otherwise
+ *
+ * Verifies data integrity against digital signature.
+ * Currently only RSA is supported.
+ * Normally hash of the content is used as a data for this function.
+ *
+ */
+int digsig_verify(struct key *keyring, const char *sig, int siglen,
+                                                const char *data, int datalen);
+
+3. User-space utilities
+
+The signing and key management utilities evm-utils provide functionality
+to generate signatures, to load keys into the kernel keyring.
+Keys can be in PEM or converted to the kernel format.
+When the key is added to the kernel keyring, the keyid defines the name
+of the key: 5D2B05FC633EE3E8 in the example bellow.
+
+Here is example output of the keyctl utility.
+
+$ keyctl show
+Session Keyring
+       -3 --alswrv      0     0  keyring: _ses
+603976250 --alswrv      0    -1   \_ keyring: _uid.0
+817777377 --alswrv      0     0       \_ user: kmk
+891974900 --alswrv      0     0       \_ encrypted: evm-key
+170323636 --alswrv      0     0       \_ keyring: _module
+548221616 --alswrv      0     0       \_ keyring: _ima
+128198054 --alswrv      0     0       \_ keyring: _evm
+
+$ keyctl list 128198054
+1 key in keyring:
+620789745: --alswrv     0     0 user: 5D2B05FC633EE3E8
+
+
+Dmitry Kasatkin
+06.10.2011
diff --git a/Documentation/security/00-INDEX b/Documentation/security/00-INDEX
index 19bc49439cac..99b85d39751c 100644
--- a/Documentation/security/00-INDEX
+++ b/Documentation/security/00-INDEX
@@ -1,5 +1,7 @@
 00-INDEX
         - this file.
+LSM.txt
+        - description of the Linux Security Module framework.
 SELinux.txt
         - how to get started with the SELinux security enhancement.
 Smack.txt
diff --git a/Documentation/security/LSM.txt b/Documentation/security/LSM.txt
new file mode 100644
index 000000000000..c335a763a2ed
--- /dev/null
+++ b/Documentation/security/LSM.txt
@@ -0,0 +1,34 @@
+Linux Security Module framework
+-------------------------------
+
+The Linux Security Module (LSM) framework provides a mechanism for
+various security checks to be hooked by new kernel extensions. The name
+"module" is a bit of a misnomer since these extensions are not actually
+loadable kernel modules. Instead, they are selectable at build-time via
+CONFIG_DEFAULT_SECURITY and can be overridden at boot-time via the
+"security=..." kernel command line argument, in the case where multiple
+LSMs were built into a given kernel.
+
+The primary users of the LSM interface are Mandatory Access Control
+(MAC) extensions which provide a comprehensive security policy. Examples
+include SELinux, Smack, Tomoyo, and AppArmor. In addition to the larger
+MAC extensions, other extensions can be built using the LSM to provide
+specific changes to system operation when these tweaks are not available
+in the core functionality of Linux itself.
+
+Without a specific LSM built into the kernel, the default LSM will be the
+Linux capabilities system. Most LSMs choose to extend the capabilities
+system, building their checks on top of the defined capability hooks.
+For more details on capabilities, see capabilities(7) in the Linux
+man-pages project.
+
+Based on http://kerneltrap.org/Linux/Documenting_Security_Module_Intent,
+a new LSM is accepted into the kernel when its intent (a description of
+what it tries to protect against and in what cases one would expect to
+use it) has been appropriately documented in Documentation/security/.
+This allows an LSM's code to be easily compared to its goals, and so
+that end users and distros can make a more informed decision about which
+LSMs suit their requirements.
+
+For extensive documentation on the available LSM hook interfaces, please
+see include/linux/security.h.
diff --git a/Documentation/security/credentials.txt b/Documentation/security/credentials.txt
index fc0366cbd7ce..86257052e31a 100644
--- a/Documentation/security/credentials.txt
+++ b/Documentation/security/credentials.txt
@@ -221,10 +221,10 @@ The Linux kernel supports the following types of credentials:
  (5) LSM
 
      The Linux Security Module allows extra controls to be placed over the
-     operations that a task may do.  Currently Linux supports two main
-     alternate LSM options: SELinux and Smack.
+     operations that a task may do.  Currently Linux supports several LSM
+     options.
 
-     Both work by labelling the objects in a system and then applying sets of
+     Some work by labelling the objects in a system and then applying sets of
      rules (policies) that say what operations a task with one label may do to
      an object with another label.