tpm : openssl-tpm-engine: parse an encrypted TPM key password from env (#15)

when openssl-tpm-engine lib is used on an unattended device, there is no
way to input TPM key password. So add this feature to support parse an
encrypted(AES algorithm) TPM key password from env.
The default decrypting AES password and salt is set in bb file.
When we create a TPM key(TSS format), generate a 8 bytes random data
as its password, and then we need to encrypt the password with the same
AES password and salt in bb file.
At last, we set a env as below:
export TPM_KEY_ENC_PW=xxxxxxxx
"xxxxxxxx" is the encrypted TPM key password for libtpm.so.

Signed-off-by: Meng Li <Meng.Li@windriver.com>

2 files changed, 285 insertions, 7 deletions

diff --git a/meta-tpm/recipes-tpm/openssl-tpm-engine/files/0005-tpm-openssl-tpm-engine-parse-an-encrypted-TPM-key-pa.patch b/meta-tpm/recipes-tpm/openssl-tpm-engine/files/0005-tpm-openssl-tpm-engine-parse-an-encrypted-TPM-key-pa.patch
new file mode 100644
index 0000000..0301308
--- /dev/null
+++ b/meta-tpm/recipes-tpm/openssl-tpm-engine/files/0005-tpm-openssl-tpm-engine-parse-an-encrypted-TPM-key-pa.patch
@@ -0,0 +1,274 @@
+From 889639aed890d03a47d9c575280cc785ecc28380 Mon Sep 17 00:00:00 2001
+From: Limeng <Meng.Li@windriver.com>
+Date: Tue, 22 Aug 2017 13:02:51 +0800
+Subject: [PATCH] tpm : openssl-tpm-engine: parse an encrypted TPM key password
+ from env
+
+when openssl-tpm-engine lib is used on an unattended device, there is no
+way to input TPM key password. So add this feature to support parse an
+encrypted(AES algorithm) TPM key password from env.
+The default decrypting AES password and salt is set in bb file.
+When we create a TPM key(TSS format), generate a 8 bytes random data
+as its password, and then we need to encrypt the password with the same
+AES password and salt in bb file.
+At last, we set a env as below:
+export TPM_KEY_ENC_PW=xxxxxxxx
+"xxxxxxxx" is the encrypted TPM key password for libtpm.so.
+
+Signed-off-by: Meng Li <Meng.Li@windriver.com>
+---
+ e_tpm.c     | 110 ++++++++++++++++++++++++++++++++++++++++++++++--------------
+ e_tpm.h     |   4 +--
+ e_tpm_err.c |   4 +--
+ 3 files changed, 89 insertions(+), 29 deletions(-)
+
+diff --git a/e_tpm.c b/e_tpm.c
+index 11bf74b..ee86a3a 100644
+--- a/e_tpm.c
++++ b/e_tpm.c
+@@ -275,7 +275,7 @@ static int tpm_decode_base64(unsigned char *indata,
+        return 0;
+ }
+ 
+-static int tpm_decrypt_srk_pw(unsigned char *indata, int in_len,
++static int tpm_decrypt_pw(unsigned char *indata, int in_len,
+                                unsigned char *outdata,
+                                int *out_len)
+ {
+@@ -288,35 +288,35 @@ static int tpm_decrypt_srk_pw(unsigned char *indata, int in_len,
+        const EVP_MD *dgst = NULL;
+        EVP_CIPHER_CTX *ctx = NULL;
+ 
+-       if (sizeof(SRK_DEC_SALT) - 1 > PKCS5_SALT_LEN) {
+-               TSSerr(TPM_F_TPM_DECRYPT_SRK_PW, TPM_R_DECRYPT_SRK_PW_FAILED);
++       if (sizeof(DEC_SALT) - 1 > PKCS5_SALT_LEN) {
++               TSSerr(TPM_F_TPM_DECRYPT_PW, TPM_R_DECRYPT_PW_FAILED);
+                return 1;
+        }
+ 
+-       aes_pw = malloc(sizeof(SRK_DEC_PW) - 1);
++       aes_pw = malloc(sizeof(DEC_PW) - 1);
+        if (aes_pw == NULL) {
+-               TSSerr(TPM_F_TPM_DECRYPT_SRK_PW, TPM_R_DECRYPT_SRK_PW_FAILED);
++               TSSerr(TPM_F_TPM_DECRYPT_PW, TPM_R_DECRYPT_PW_FAILED);
+                return 1;
+        }
+ 
+        memset(aes_salt, 0x00, sizeof(aes_salt));
+-       memcpy(aes_pw, SRK_DEC_PW, sizeof(SRK_DEC_PW) - 1);
+-       memcpy(aes_salt, SRK_DEC_SALT, sizeof(SRK_DEC_SALT) - 1);
++       memcpy(aes_pw, DEC_PW, sizeof(DEC_PW) - 1);
++       memcpy(aes_salt, DEC_SALT, sizeof(DEC_SALT) - 1);
+ 
+        cipher = EVP_get_cipherbyname("aes-128-cbc");
+        if (cipher == NULL) {
+-               TSSerr(TPM_F_TPM_DECRYPT_SRK_PW, TPM_R_DECRYPT_SRK_PW_FAILED);
++               TSSerr(TPM_F_TPM_DECRYPT_PW, TPM_R_DECRYPT_PW_FAILED);
+                free(aes_pw);
+                return 1;
+        }
+        dgst = EVP_sha256();
+ 
+-       EVP_BytesToKey(cipher, dgst, aes_salt, (unsigned char *)aes_pw, sizeof(SRK_DEC_PW) - 1, 1, key, iv);
++       EVP_BytesToKey(cipher, dgst, aes_salt, (unsigned char *)aes_pw, sizeof(DEC_PW) - 1, 1, key, iv);
+ 
+        ctx = EVP_CIPHER_CTX_new();
+        /* Don't set key or IV right away; we want to check lengths */
+        if (!EVP_CipherInit_ex(ctx, cipher, NULL, NULL, NULL, 0)) {
+-               TSSerr(TPM_F_TPM_DECRYPT_SRK_PW, TPM_R_DECRYPT_SRK_PW_FAILED);
++               TSSerr(TPM_F_TPM_DECRYPT_PW, TPM_R_DECRYPT_PW_FAILED);
+                free(aes_pw);
+                return 1;
+        }
+@@ -325,14 +325,14 @@ static int tpm_decrypt_srk_pw(unsigned char *indata, int in_len,
+        OPENSSL_assert(EVP_CIPHER_CTX_iv_length(ctx) == 16);
+ 
+        if (!EVP_CipherInit_ex(ctx, NULL, NULL, key, iv, 0)) {
+-               TSSerr(TPM_F_TPM_DECRYPT_SRK_PW, TPM_R_DECRYPT_SRK_PW_FAILED);
++               TSSerr(TPM_F_TPM_DECRYPT_PW, TPM_R_DECRYPT_PW_FAILED);
+                free(aes_pw);
+                return 1;
+        }
+ 
+        if (!EVP_CipherUpdate(ctx, dec_data, &dec_data_len, indata, in_len)) {
+                /* Error */
+-               TSSerr(TPM_F_TPM_DECRYPT_SRK_PW, TPM_R_DECRYPT_SRK_PW_FAILED);
++               TSSerr(TPM_F_TPM_DECRYPT_PW, TPM_R_DECRYPT_PW_FAILED);
+                free(aes_pw);
+                EVP_CIPHER_CTX_free(ctx);
+                return 1;
+@@ -340,7 +340,7 @@ static int tpm_decrypt_srk_pw(unsigned char *indata, int in_len,
+ 
+        if (!EVP_CipherFinal_ex(ctx, dec_data + dec_data_len, &dec_data_lenfinal)) {
+                /* Error */
+-               TSSerr(TPM_F_TPM_DECRYPT_SRK_PW, TPM_R_DECRYPT_SRK_PW_FAILED);
++               TSSerr(TPM_F_TPM_DECRYPT_PW, TPM_R_DECRYPT_PW_FAILED);
+                free(aes_pw);
+                EVP_CIPHER_CTX_free(ctx);
+                return 1;
+@@ -448,8 +448,7 @@ int tpm_load_srk(UI_METHOD *ui, void *cb_data)
+                        return 0;
+                }
+ 
+-               if (tpm_decrypt_srk_pw(out_buf, out_len,
+-                                                       auth, &authlen)) {
++               if (tpm_decrypt_pw(out_buf, out_len, auth, &authlen)) {
+                        Tspi_Context_CloseObject(hContext, hSRK);
+                        free(auth);
+                        free(out_buf);
+@@ -460,7 +459,7 @@ int tpm_load_srk(UI_METHOD *ui, void *cb_data)
+                free(out_buf);
+        }
+ #ifdef TPM_SRK_PLAIN_PW
+-       else if (NULL != (srkPasswd = getenv("TPM_SRK_PW")) {
++       else if (NULL != (srkPasswd = getenv("TPM_SRK_PW"))) {
+                if (0 == strcmp(srkPasswd, "#WELLKNOWN#")) {
+                        memset(auth, 0, TPM_WELL_KNOWN_KEY_LEN);
+                        secretMode = TSS_SECRET_MODE_SHA1;
+@@ -807,6 +806,9 @@ static EVP_PKEY *tpm_engine_load_key(ENGINE *e, const char *key_id,
+        if (authusage) {
+                TSS_HPOLICY hPolicy;
+                BYTE *auth;
++               char *tpmKeyPasswd = NULL;
++               int authlen = 0;
++               TSS_FLAG secretMode = secret_mode;
+ 
+                if ((auth = calloc(1, 128)) == NULL) {
+                        Tspi_Context_CloseObject(hContext, hKey);
+@@ -814,13 +816,71 @@ static EVP_PKEY *tpm_engine_load_key(ENGINE *e, const char *key_id,
+                        return NULL;
+                }
+ 
+-               if (!tpm_engine_get_auth(ui, (char *)auth, 128,
+-                                        "TPM Key Password: ",
+-                                        cb_data)) {
+-                       Tspi_Context_CloseObject(hContext, hKey);
+-                       free(auth);
+-                       TSSerr(TPM_F_TPM_ENGINE_LOAD_KEY, TPM_R_REQUEST_FAILED);
+-                       return NULL;
++               tpmKeyPasswd = getenv("TPM_KEY_ENC_PW");
++               if (NULL != tpmKeyPasswd) {
++                       int in_len = strlen(tpmKeyPasswd);
++                       int out_len;
++                       unsigned char *out_buf;
++
++                       if (!in_len || in_len % 4) {
++                               Tspi_Context_CloseObject(hContext, hKey);
++                               free(auth);
++                               TSSerr(TPM_F_TPM_ENGINE_LOAD_KEY, TPM_R_REQUEST_FAILED);
++                               return NULL;
++                       }
++                       out_len = in_len * 3 / 4;
++                       out_buf = malloc(out_len);
++                       if (NULL == out_buf) {
++                               Tspi_Context_CloseObject(hContext, hKey);
++                               free(auth);
++                               TSSerr(TPM_F_TPM_ENGINE_LOAD_KEY, ERR_R_MALLOC_FAILURE);
++                               return NULL;
++                       }
++
++                       if (tpm_decode_base64(tpmKeyPasswd, strlen(tpmKeyPasswd),
++                                               out_buf, &out_len)) {
++                               Tspi_Context_CloseObject(hContext, hKey);
++                               free(auth);
++                               free(out_buf);
++                               TSSerr(TPM_F_TPM_ENGINE_LOAD_KEY, TPM_R_REQUEST_FAILED);
++                               return NULL;
++                       }
++
++                       if (tpm_decrypt_pw(out_buf, out_len, auth, &authlen)) {
++                               Tspi_Context_CloseObject(hContext, hKey);
++                               free(auth);
++                               free(out_buf);
++                               TSSerr(TPM_F_TPM_ENGINE_LOAD_KEY, TPM_R_REQUEST_FAILED);
++                               return 0;
++                       }
++                       secretMode = TSS_SECRET_MODE_PLAIN;
++                       free(out_buf);
++               }
++#ifdef TPM_KEY_PLAIN_PW
++               else if (NULL != (tpmKeyPasswd = getenv("TPM_KEY_PW"))) {
++                       if (0 == strcmp(tpmKeyPasswd, "#WELLKNOWN#")) {
++                               memset(auth, 0, TPM_WELL_KNOWN_KEY_LEN);
++                               secretMode = TSS_SECRET_MODE_SHA1;
++                               authlen = TPM_WELL_KNOWN_KEY_LEN;
++                       } else {
++                               int authbuflen = 128;
++                               memset(auth, 0, authbuflen);
++                               strncpy(auth, tpmKeyPasswd, authbuflen-1);
++                               secretMode = TSS_SECRET_MODE_PLAIN;
++                               authlen = strlen(auth);
++                       }
++               }
++#endif
++               else {
++                       if (!tpm_engine_get_auth(ui, (char *)auth, 128,
++                               "TPM Key Password: ", cb_data)) {
++                               Tspi_Context_CloseObject(hContext, hKey);
++                               free(auth);
++                               TSSerr(TPM_F_TPM_ENGINE_LOAD_KEY, TPM_R_REQUEST_FAILED);
++                               return NULL;
++                       }
++                       secretMode = secret_mode;
++                       authlen = strlen(auth);
+                }
+ 
+                if ((result = Tspi_Context_CreateObject(hContext,
+@@ -842,8 +902,8 @@ static EVP_PKEY *tpm_engine_load_key(ENGINE *e, const char *key_id,
+                }
+ 
+                if ((result = Tspi_Policy_SetSecret(hPolicy,
+-                                                     TSS_SECRET_MODE_PLAIN,
+-                                                     strlen((char *)auth), auth))) {
++                                                       secretMode,
++                                                       authlen, auth))) {
+                        Tspi_Context_CloseObject(hContext, hKey);
+                        Tspi_Context_CloseObject(hContext, hPolicy);
+                        free(auth);
+diff --git a/e_tpm.h b/e_tpm.h
+index 56ff202..7faf744 100644
+--- a/e_tpm.h
++++ b/e_tpm.h
+@@ -67,7 +67,7 @@ void ERR_TSS_error(int function, int reason, char *file, int line);
+ #define TPM_F_TPM_ENGINE_GET_AUTH              117
+ #define TPM_F_TPM_CREATE_SRK_POLICY            118
+ #define TPM_F_TPM_DECODE_BASE64                        119
+-#define TPM_F_TPM_DECRYPT_SRK_PW               120
++#define TPM_F_TPM_DECRYPT_PW                   120
+ 
+ /* Reason codes. */
+ #define TPM_R_ALREADY_LOADED                   100
+@@ -99,7 +99,7 @@ void ERR_TSS_error(int function, int reason, char *file, int line);
+ #define TPM_R_UI_METHOD_FAILED                 126
+ #define TPM_R_UNKNOWN_SECRET_MODE              127
+ #define TPM_R_DECODE_BASE64_FAILED             128
+-#define TPM_R_DECRYPT_SRK_PW_FAILED            129
++#define TPM_R_DECRYPT_PW_FAILED                        129
+ 
+ /* structure pointed to by the RSA object's app_data pointer */
+ struct rsa_app_data
+diff --git a/e_tpm_err.c b/e_tpm_err.c
+index 439e267..f8ce624 100644
+--- a/e_tpm_err.c
++++ b/e_tpm_err.c
+@@ -236,7 +236,7 @@ static ERR_STRING_DATA TPM_str_functs[] = {
+        {ERR_PACK(0, TPM_F_TPM_FILL_RSA_OBJECT, 0), "TPM_FILL_RSA_OBJECT"},
+        {ERR_PACK(0, TPM_F_TPM_ENGINE_GET_AUTH, 0), "TPM_ENGINE_GET_AUTH"},
+        {ERR_PACK(0, TPM_F_TPM_DECODE_BASE64, 0), "TPM_DECODE_BASE64"},
+-       {ERR_PACK(0, TPM_F_TPM_DECRYPT_SRK_PW, 0), "TPM_DECRYPT_SRK_PW"},
++       {ERR_PACK(0, TPM_F_TPM_DECRYPT_PW, 0), "TPM_DECRYPT_SRK_PW"},
+        {0, NULL}
+ };
+ 
+@@ -268,7 +268,7 @@ static ERR_STRING_DATA TPM_str_reasons[] = {
+        {TPM_R_ID_INVALID, "engine id doesn't match"},
+        {TPM_R_UI_METHOD_FAILED, "ui function failed"},
+        {TPM_R_DECODE_BASE64_FAILED, "decode base64 failed"},
+-       {TPM_R_DECRYPT_SRK_PW_FAILED, "decrypt srk password failed"},
++       {TPM_R_DECRYPT_PW_FAILED, "decrypt password failed"},
+        {0, NULL}
+ };
+ 
+-- 
+2.9.3
+
diff --git a/meta-tpm/recipes-tpm/openssl-tpm-engine/openssl-tpm-engine_git.bb b/meta-tpm/recipes-tpm/openssl-tpm-engine/openssl-tpm-engine_git.bb
index 853590d..54766a5 100644
--- a/meta-tpm/recipes-tpm/openssl-tpm-engine/openssl-tpm-engine_git.bb
+++ b/meta-tpm/recipes-tpm/openssl-tpm-engine/openssl-tpm-engine_git.bb
@@ -16,6 +16,7 @@ SRC_URI = "\
     file://0003-Fix-not-building-libtpm.la.patch \
     file://0003-tpm-openssl-tpm-engine-parse-an-encrypted-tpm-SRK-pa.patch \
     file://0004-tpm-openssl-tpm-engine-change-variable-c-type-from-c.patch \
+    file://0005-tpm-openssl-tpm-engine-parse-an-encrypted-TPM-key-pa.patch \
 "
 SRCREV = "bbc2b1af809f20686e0d3553a62f0175742c0d60"
 
@@ -29,19 +30,22 @@ inherit autotools-brokensep
 # srk_dec_pw = "incendia"
 # srk_dec_pw = "\x69\x6e\x63\x65\x6e\x64\x69\x61"
 # srk_dec_pw = "\x1""nc""\x3""nd""\x1""a"
-#
+
+# The definitions below are used to decrypt the passwords of both srk and loaded key.
+dec_pw ?= "\\"\\\x1\\"\\"nc\\"\\"\\\x3\\"\\"nd\\"\\"\\\x1\\"\\"a\\""
+dec_salt ?= "\\"r\\"\\"\\\x00\\\x00\\"\\"t\\""
+CFLAGS_append += "-DDEC_PW=${dec_pw} -DDEC_SALT=${dec_salt}"
 # Due to the limit of escape character, the hybrid must be written in
 # above style. The actual values defined below in C code style are:
-# srk_dec_pw[] = { 0x01, 'n', 'c', 0x03, 'n', 'd', 0x01, 'a' };
-# srk_dec_salt[] = { 'r', 0x00, 0x00, 't' };
-srk_dec_pw ?= "\\"\\\x1\\"\\"nc\\"\\"\\\x3\\"\\"nd\\"\\"\\\x1\\"\\"a\\""
-srk_dec_salt ?= "\\"r\\"\\"\\\x00\\\x00\\"\\"t\\""
-
-CFLAGS_append += "-DSRK_DEC_PW=${srk_dec_pw} -DSRK_DEC_SALT=${srk_dec_salt}"
+# dec_pw[] = {0x01, 'n', 'c', 0x03, 'n', 'd', 0x01, 'a'};
+# dec_salt[] = {'r', 0x00, 0x00, 't'};
 
 # Uncomment below line if using the plain srk password for development
 #CFLAGS_append += "-DTPM_SRK_PLAIN_PW"
 
+# Uncomment below line if using the plain tpm key password for development
+#CFLAGS_append += "-DTPM_KEY_PLAIN_PW"
+
 do_configure_prepend() {
     cd "${S}"
     cp LICENSE COPYING