mbedtls: add support for pkcs7

PKCS7 signing format is used by OpenPOWER Key Management, which is
using mbedtls as its crypto library.

This patch adds the limited support of pkcs7 parser and verification
to the mbedtls. The limitations are:

* Only signed data is supported.
* CRLs are not currently handled.
* Single signer is supported.

Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Eric Richter <erichte@linux.ibm.com>
Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
diff --git a/include/mbedtls/oid.h b/include/mbedtls/oid.h
index 4ee3f93..e5c4b92 100644
--- a/include/mbedtls/oid.h
+++ b/include/mbedtls/oid.h
@@ -220,6 +220,7 @@
 #define MBEDTLS_OID_PKCS                MBEDTLS_OID_RSA_COMPANY "\x01" /**< pkcs OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) rsadsi(113549) 1 } */
 #define MBEDTLS_OID_PKCS1               MBEDTLS_OID_PKCS "\x01" /**< pkcs-1 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 1 } */
 #define MBEDTLS_OID_PKCS5               MBEDTLS_OID_PKCS "\x05" /**< pkcs-5 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 5 } */
+#define MBEDTLS_OID_PKCS7               MBEDTLS_OID_PKCS "\x07" /**< pkcs-7 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 7 } */
 #define MBEDTLS_OID_PKCS9               MBEDTLS_OID_PKCS "\x09" /**< pkcs-9 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 9 } */
 #define MBEDTLS_OID_PKCS12              MBEDTLS_OID_PKCS "\x0c" /**< pkcs-12 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 12 } */
 
@@ -301,6 +302,16 @@
 #define MBEDTLS_OID_PKCS5_PBE_SHA1_RC2_CBC      MBEDTLS_OID_PKCS5 "\x0b" /**< pbeWithSHA1AndRC2-CBC OBJECT IDENTIFIER ::= {pkcs-5 11} */
 
 /*
+ * PKCS#7 OIDs
+ */
+#define MBEDTLS_OID_PKCS7_DATA                        MBEDTLS_OID_PKCS7 "\x01" /**< Content type is Data OBJECT IDENTIFIER ::= {pkcs-7 1} */
+#define MBEDTLS_OID_PKCS7_SIGNED_DATA                 MBEDTLS_OID_PKCS7 "\x02" /**< Content type is Signed Data OBJECT IDENTIFIER ::= {pkcs-7 2} */
+#define MBEDTLS_OID_PKCS7_ENVELOPED_DATA              MBEDTLS_OID_PKCS7 "\x03" /**< Content type is Enveloped Data OBJECT IDENTIFIER ::= {pkcs-7 3} */
+#define MBEDTLS_OID_PKCS7_SIGNED_AND_ENVELOPED_DATA   MBEDTLS_OID_PKCS7 "\x04" /**< Content type is Signed and Enveloped Data OBJECT IDENTIFIER ::= {pkcs-7 4} */
+#define MBEDTLS_OID_PKCS7_DIGESTED_DATA               MBEDTLS_OID_PKCS7 "\x05" /**< Content type is Digested Data OBJECT IDENTIFIER ::= {pkcs-7 5} */
+#define MBEDTLS_OID_PKCS7_ENCRYPTED_DATA              MBEDTLS_OID_PKCS7 "\x06" /**< Content type is Encrypted Data OBJECT IDENTIFIER ::= {pkcs-7 6} */
+
+/*
  * PKCS#8 OIDs
  */
 #define MBEDTLS_OID_PKCS9_CSR_EXT_REQ           MBEDTLS_OID_PKCS9 "\x0e" /**< extensionRequest OBJECT IDENTIFIER ::= {pkcs-9 14} */