Merge branch 'prerelease'

README

@@ -18,6 +18,7 @@ an iPhone data vault and password manager (http://getstrip.com).
 - Good security practices (CBC mode, key derivation)
 - Zero-configuration and application level cryptography
 - Algorithms provided by the peer reviewed OpenSSL crypto library.
+- Configurable crypto providers
 
 [Compiling]
 

src/crypto.h

@@ -44,7 +44,7 @@
 #define FILE_HEADER_SZ 16
 
 #ifndef CIPHER_VERSION
-#define CIPHER_VERSION "2.2.0"
+#define CIPHER_VERSION "2.2.1"
 #endif
 
 #ifndef CIPHER

src/crypto_impl.c

@@ -66,7 +66,8 @@ typedef struct {
 
 static unsigned int default_flags = DEFAULT_CIPHER_FLAGS;
 static unsigned char hmac_salt_mask = HMAC_SALT_MASK;
-
+static unsigned int sqlcipher_activate_count = 0;
+static sqlite3_mutex* sqlcipher_provider_mutex = NULL;
 static sqlcipher_provider *default_provider = NULL;
 
 struct codec_ctx {
@@ -81,13 +82,15 @@ struct codec_ctx {
 };
 
 int sqlcipher_register_provider(sqlcipher_provider *p) {
+  sqlite3_mutex_enter(sqlcipher_provider_mutex);
   if(default_provider != NULL && default_provider != p) {
     /* only free the current registerd provider if it has been initialized
        and it isn't a pointer to the same provider passed to the function
        (i.e. protect against a caller calling register twice for the same provider) */
     sqlcipher_free(default_provider, sizeof(sqlcipher_provider));
   }
   default_provider = p;   
+  sqlite3_mutex_leave(sqlcipher_provider_mutex);
   return SQLITE_OK;
 }
 
@@ -99,35 +102,57 @@ sqlcipher_provider* sqlcipher_get_provider() {
 }
 
 void sqlcipher_activate() {
-  sqlcipher_provider *p;
-  sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
-  p = sqlcipher_malloc(sizeof(sqlcipher_provider));
-  {
+  sqlite3_mutex_enter(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER));
+
+  if(sqlcipher_provider_mutex == NULL) {
+    /* allocate a new mutex to guard access to the provider */
+    sqlcipher_provider_mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
+  }
+
+  /* check to see if there is a provider registered at this point
+     if there no provider registered at this point, register the 
+     default provider */
+  if(sqlcipher_get_provider() == NULL) {
+    sqlcipher_provider *p = sqlcipher_malloc(sizeof(sqlcipher_provider)); 
 #if defined (SQLCIPHER_CRYPTO_CC)
-  extern int sqlcipher_cc_setup(sqlcipher_provider *p);
-  sqlcipher_cc_setup(p);
+    extern int sqlcipher_cc_setup(sqlcipher_provider *p);
+    sqlcipher_cc_setup(p);
 #elif defined (SQLCIPHER_CRYPTO_LIBTOMCRYPT)
-  extern int sqlcipher_ltc_setup(sqlcipher_provider *p);
-  sqlcipher_ltc_setup(p);
+    extern int sqlcipher_ltc_setup(sqlcipher_provider *p);
+    sqlcipher_ltc_setup(p);
 #elif defined (SQLCIPHER_CRYPTO_OPENSSL)
-  extern int sqlcipher_openssl_setup(sqlcipher_provider *p);
-  sqlcipher_openssl_setup(p);
+    extern int sqlcipher_openssl_setup(sqlcipher_provider *p);
+    sqlcipher_openssl_setup(p);
 #else
 #error "NO DEFAULT SQLCIPHER CRYPTO PROVIDER DEFINED"
 #endif
+    sqlcipher_register_provider(p);
   }
-  sqlcipher_register_provider(p);
 
-  sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
+  sqlcipher_activate_count++; /* increment activation count */
+
+  sqlite3_mutex_leave(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER));
 }
 
 void sqlcipher_deactivate() {
-  sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
-  if(default_provider != NULL) {
-    sqlcipher_free(default_provider, sizeof(sqlcipher_provider));
-    default_provider = NULL;
+  sqlite3_mutex_enter(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER));
+  sqlcipher_activate_count--;
+  /* if no connections are using sqlcipher, cleanup globals */
+  if(sqlcipher_activate_count < 1) {
+    sqlite3_mutex_enter(sqlcipher_provider_mutex);
+    if(default_provider != NULL) {
+      sqlcipher_free(default_provider, sizeof(sqlcipher_provider));
+      default_provider = NULL;
+    }
+    sqlite3_mutex_leave(sqlcipher_provider_mutex);
+
+    /* last connection closed, free provider mutex*/
+    sqlite3_mutex_free(sqlcipher_provider_mutex); 
+    sqlcipher_provider_mutex = NULL;
+
+    sqlcipher_activate_count = 0; /* reset activation count */
   }
-  sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
+  sqlite3_mutex_leave(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER));
 }
 
 /* constant time memset using volitile to avoid having the memset
@@ -235,7 +260,11 @@ static int sqlcipher_cipher_ctx_init(cipher_ctx **iCtx) {
 
   ctx->provider = (sqlcipher_provider *) sqlcipher_malloc(sizeof(sqlcipher_provider));
   if(ctx->provider == NULL) return SQLITE_NOMEM;
+
+  /* make a copy of the provider to be used for the duration of the context */
+  sqlite3_mutex_enter(sqlcipher_provider_mutex);
   memcpy(ctx->provider, default_provider, sizeof(sqlcipher_provider));
+  sqlite3_mutex_leave(sqlcipher_provider_mutex);
 
   if((rc = ctx->provider->ctx_init(&ctx->provider_ctx)) != SQLITE_OK) return rc;
   ctx->key = (unsigned char *) sqlcipher_malloc(CIPHER_MAX_KEY_SZ);

src/crypto_openssl.c

@@ -45,10 +45,16 @@ typedef struct {
 
 static unsigned int openssl_external_init = 0;
 static unsigned int openssl_init_count = 0;
-
+static sqlite3_mutex* openssl_rand_mutex = NULL;
 
 static int sqlcipher_openssl_add_random(void *ctx, void *buffer, int length) {
+#ifndef SQLCIPHER_OPENSSL_NO_MUTEX_RAND
+  sqlite3_mutex_enter(openssl_rand_mutex);
+#endif
   RAND_add(buffer, length, 0);
+#ifndef SQLCIPHER_OPENSSL_NO_MUTEX_RAND
+  sqlite3_mutex_leave(openssl_rand_mutex);
+#endif
   return SQLITE_OK;
 }
 
@@ -59,40 +65,57 @@ static int sqlcipher_openssl_add_random(void *ctx, void *buffer, int length) {
    sqlcipher_openssl_deactivate() will free the EVP structures. 
 */
 static int sqlcipher_openssl_activate(void *ctx) {
-  /* we'll initialize openssl and increment the internal init counter
+  /* initialize openssl and increment the internal init counter
      but only if it hasn't been initalized outside of SQLCipher by this program 
      e.g. on startup */
+  sqlite3_mutex_enter(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER));
+
   if(openssl_init_count == 0 && EVP_get_cipherbyname(CIPHER) != NULL) {
+    /* if openssl has not yet been initialized by this library, but 
+       a call to get_cipherbyname works, then the openssl library
+       has been initialized externally already. */
     openssl_external_init = 1;
   }
 
-  if(openssl_external_init == 0) {
-    if(openssl_init_count == 0)  {
-      OpenSSL_add_all_algorithms();
-    }
-    openssl_init_count++; 
+  if(openssl_init_count == 0 && openssl_external_init == 0)  {
+    /* if the library was not externally initialized, then should be now */
+    OpenSSL_add_all_algorithms();
   } 
+
+#ifndef SQLCIPHER_OPENSSL_NO_MUTEX_RAND
+  if(openssl_rand_mutex == NULL) {
+    /* allocate a mutex to guard against concurrent calls to RAND_bytes() */
+    openssl_rand_mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
+  }
+#endif
+
+  openssl_init_count++; 
+  sqlite3_mutex_leave(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER));
   return SQLITE_OK;
 }
 
 /* deactivate SQLCipher, most imporantly decremeting the activation count and
    freeing the EVP structures on the final deactivation to ensure that 
    OpenSSL memory is cleaned up */
 static int sqlcipher_openssl_deactivate(void *ctx) {
-  sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
-  /* If it is initialized externally, then the init counter should never be greater than zero.
-     This should prevent SQLCipher from "cleaning up" openssl 
-     when something else in the program might be using it. */
-  if(openssl_external_init == 0) {
-    openssl_init_count--;
-    /* if the counter reaches zero after it's decremented release EVP memory
+  sqlite3_mutex_enter(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER));
+  openssl_init_count--;
+
+  if(openssl_init_count == 0) {
+    if(openssl_external_init == 0) {
+    /* if OpenSSL hasn't be initialized externally, and the counter reaches zero 
+       after it's decremented, release EVP memory
        Note: this code will only be reached if OpensSSL_add_all_algorithms()
-       is called by SQLCipher internally. */
-    if(openssl_init_count == 0) {
+       is called by SQLCipher internally. This should prevent SQLCipher from 
+       "cleaning up" openssl when it was initialized externally by the program */
       EVP_cleanup();
     }
+#ifndef SQLCIPHER_OPENSSL_NO_MUTEX_RAND
+    sqlite3_mutex_free(openssl_rand_mutex);
+    openssl_rand_mutex = NULL;
+#endif
   }
-  sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
+  sqlite3_mutex_leave(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER));
   return SQLITE_OK;
 }
 
@@ -102,7 +125,21 @@ static const char* sqlcipher_openssl_get_provider_name(void *ctx) {
 
 /* generate a defined number of random bytes */
 static int sqlcipher_openssl_random (void *ctx, void *buffer, int length) {
-  return (RAND_bytes((unsigned char *)buffer, length) == 1) ? SQLITE_OK : SQLITE_ERROR;
+  int rc = 0;
+  /* concurrent calls to RAND_bytes can cause a crash under some openssl versions when a 
+     naive application doesn't use CRYPTO_set_locking_callback and
+     CRYPTO_THREADID_set_callback to ensure openssl thread safety. 
+     This is simple workaround to prevent this common crash
+     but a more proper solution is that applications setup platform-appropriate
+     thread saftey in openssl externally */
+#ifndef SQLCIPHER_OPENSSL_NO_MUTEX_RAND
+  sqlite3_mutex_enter(openssl_rand_mutex);
+#endif
+  rc = RAND_bytes((unsigned char *)buffer, length);
+#ifndef SQLCIPHER_OPENSSL_NO_MUTEX_RAND
+  sqlite3_mutex_leave(openssl_rand_mutex);
+#endif
+  return (rc == 1) ? SQLITE_OK : SQLITE_ERROR;
 }
 
 static int sqlcipher_openssl_hmac(void *ctx, unsigned char *hmac_key, int key_sz, unsigned char *in, int in_sz, unsigned char *in2, int in2_sz, unsigned char *out) {

test/crypto.test

@@ -1418,7 +1418,7 @@ do_test verify-pragma-cipher-version {
     execsql {
         PRAGMA cipher_version;
     }
-} {2.2.0}
+} {2.2.1}
 db close
 file delete -force test.db