PBKDF2 updates to conform to SP800-132

The existing code used PKCS5 specifications.
SP800-132 adds the following additional constraints for:
  - the range of the key length.
  - the minimum iteration count (1000 recommended).
  - salt length (at least 128 bits).
These additional constraints may cause errors (in scrypt, and
some PKCS5 related test vectors). To disable the new
constraints use the new ctrl string "pkcs5".
For backwards compatability, the checks are only enabled by
default for fips mode.

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/8868)

2 files changed, 84 insertions, 18 deletions

diff --git a/crypto/kdf/kdf_err.c b/crypto/kdf/kdf_err.c
index 49028ab32f..98dc271efc 100644
--- a/crypto/kdf/kdf_err.c
+++ b/crypto/kdf/kdf_err.c
@@ -19,6 +19,7 @@ static const ERR_STRING_DATA KDF_str_functs[] = {
     {ERR_PACK(ERR_LIB_KDF, KDF_F_KDF_HKDF_NEW, 0), "kdf_hkdf_new"},
     {ERR_PACK(ERR_LIB_KDF, KDF_F_KDF_HKDF_SIZE, 0), "kdf_hkdf_size"},
     {ERR_PACK(ERR_LIB_KDF, KDF_F_KDF_MD2CTRL, 0), "kdf_md2ctrl"},
+    {ERR_PACK(ERR_LIB_KDF, KDF_F_KDF_PBKDF2_CTRL, 0), "kdf_pbkdf2_ctrl"},
     {ERR_PACK(ERR_LIB_KDF, KDF_F_KDF_PBKDF2_CTRL_STR, 0),
      "kdf_pbkdf2_ctrl_str"},
     {ERR_PACK(ERR_LIB_KDF, KDF_F_KDF_PBKDF2_DERIVE, 0), "kdf_pbkdf2_derive"},
@@ -41,6 +42,7 @@ static const ERR_STRING_DATA KDF_str_functs[] = {
     {ERR_PACK(ERR_LIB_KDF, KDF_F_KDF_TLS1_PRF_DERIVE, 0),
      "kdf_tls1_prf_derive"},
     {ERR_PACK(ERR_LIB_KDF, KDF_F_KDF_TLS1_PRF_NEW, 0), "kdf_tls1_prf_new"},
+    {ERR_PACK(ERR_LIB_KDF, KDF_F_PBKDF2_DERIVE, 0), "pbkdf2_derive"},
     {ERR_PACK(ERR_LIB_KDF, KDF_F_PBKDF2_SET_MEMBUF, 0), "pbkdf2_set_membuf"},
     {ERR_PACK(ERR_LIB_KDF, KDF_F_PKEY_HKDF_CTRL_STR, 0), "pkey_hkdf_ctrl_str"},
     {ERR_PACK(ERR_LIB_KDF, KDF_F_PKEY_HKDF_DERIVE, 0), "pkey_hkdf_derive"},
@@ -71,7 +73,11 @@ static const ERR_STRING_DATA KDF_str_functs[] = {
 
 static const ERR_STRING_DATA KDF_str_reasons[] = {
     {ERR_PACK(ERR_LIB_KDF, 0, KDF_R_INVALID_DIGEST), "invalid digest"},
+    {ERR_PACK(ERR_LIB_KDF, 0, KDF_R_INVALID_ITERATION_COUNT),
+    "invalid iteration count"},
+    {ERR_PACK(ERR_LIB_KDF, 0, KDF_R_INVALID_KEY_LEN), "invalid key len"},
     {ERR_PACK(ERR_LIB_KDF, 0, KDF_R_INVALID_MAC_TYPE), "invalid mac type"},
+    {ERR_PACK(ERR_LIB_KDF, 0, KDF_R_INVALID_SALT_LEN), "invalid salt len"},
     {ERR_PACK(ERR_LIB_KDF, 0, KDF_R_MISSING_ITERATION_COUNT),
     "missing iteration count"},
     {ERR_PACK(ERR_LIB_KDF, 0, KDF_R_MISSING_KEY), "missing key"},
diff --git a/crypto/kdf/pbkdf2.c b/crypto/kdf/pbkdf2.c
index 7009dfdeb3..d41689773c 100644
--- a/crypto/kdf/pbkdf2.c
+++ b/crypto/kdf/pbkdf2.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2018 The OpenSSL Project Authors. All Rights Reserved.
+ * Copyright 2018-2019 The OpenSSL Project Authors. All Rights Reserved.
  *
  * Licensed under the Apache License 2.0 (the "License").  You may not use
  * this file except in compliance with the License.  You can obtain a copy
@@ -17,12 +17,27 @@
 #include "internal/evp_int.h"
 #include "kdf_local.h"
 
+/* Constants specified in SP800-132 */
+#define KDF_PBKDF2_MIN_KEY_LEN_BITS  112
+#define KDF_PBKDF2_MAX_KEY_LEN_DIGEST_RATIO 0xFFFFFFFF
+#define KDF_PBKDF2_MIN_ITERATIONS 1000
+#define KDF_PBKDF2_MIN_SALT_LEN   (128 / 8)
+/*
+ * For backwards compatibility reasons,
+ * Extra checks are done by default in fips mode only.
+ */
+#ifdef FIPS_MODE
+# define KDF_PBKDF2_DEFAULT_CHECKS 1
+#else
+# define KDF_PBKDF2_DEFAULT_CHECKS 0
+#endif /* FIPS_MODE */
+
 static void kdf_pbkdf2_reset(EVP_KDF_IMPL *impl);
 static void kdf_pbkdf2_init(EVP_KDF_IMPL *impl);
-static int pkcs5_pbkdf2_alg(const char *pass, size_t passlen,
-                            const unsigned char *salt, int saltlen, int iter,
-                            const EVP_MD *digest, unsigned char *key,
-                            size_t keylen);
+static int  pbkdf2_derive(const char *pass, size_t passlen,
+                          const unsigned char *salt, int saltlen, int iter,
+                          const EVP_MD *digest, unsigned char *key,
+                          size_t keylen, int extra_checks);
 
 struct evp_kdf_impl_st {
     unsigned char *pass;
@@ -31,6 +46,7 @@ struct evp_kdf_impl_st {
     size_t salt_len;
     int iter;
     const EVP_MD *md;
+    int lower_bound_checks;
 };
 
 static EVP_KDF_IMPL *kdf_pbkdf2_new(void)
@@ -64,6 +80,7 @@ static void kdf_pbkdf2_init(EVP_KDF_IMPL *impl)
 {
     impl->iter = PKCS5_DEFAULT_ITER;
     impl->md = EVP_sha1();
+    impl->lower_bound_checks = KDF_PBKDF2_DEFAULT_CHECKS;
 }
 
 static int pbkdf2_set_membuf(unsigned char **buffer, size_t *buflen,
@@ -91,12 +108,16 @@ static int pbkdf2_set_membuf(unsigned char **buffer, size_t *buflen,
 
 static int kdf_pbkdf2_ctrl(EVP_KDF_IMPL *impl, int cmd, va_list args)
 {
-    int iter;
+    int iter, pkcs5, min_iter;
     const unsigned char *p;
     size_t len;
     const EVP_MD *md;
 
     switch (cmd) {
+    case EVP_KDF_CTRL_SET_PBKDF2_PKCS5_MODE:
+        pkcs5 = va_arg(args, int);
+        impl->lower_bound_checks = (pkcs5 == 0) ? 1 : 0;
+        return 1;
     case EVP_KDF_CTRL_SET_PASS:
         p = va_arg(args, const unsigned char *);
         len = va_arg(args, size_t);
@@ -105,20 +126,28 @@ static int kdf_pbkdf2_ctrl(EVP_KDF_IMPL *impl, int cmd, va_list args)
     case EVP_KDF_CTRL_SET_SALT:
         p = va_arg(args, const unsigned char *);
         len = va_arg(args, size_t);
+        if (impl->lower_bound_checks != 0 && len < KDF_PBKDF2_MIN_SALT_LEN) {
+            KDFerr(KDF_F_KDF_PBKDF2_CTRL, KDF_R_INVALID_SALT_LEN);
+            return 0;
+        }
         return pbkdf2_set_membuf(&impl->salt, &impl->salt_len, p, len);
 
     case EVP_KDF_CTRL_SET_ITER:
         iter = va_arg(args, int);
-        if (iter < 1)
+        min_iter = impl->lower_bound_checks != 0 ? KDF_PBKDF2_MIN_ITERATIONS : 1;
+        if (iter < min_iter) {
+            KDFerr(KDF_F_KDF_PBKDF2_CTRL, KDF_R_INVALID_ITERATION_COUNT);
             return 0;
-
+        }
         impl->iter = iter;
         return 1;
 
     case EVP_KDF_CTRL_SET_MD:
         md = va_arg(args, const EVP_MD *);
-        if (md == NULL)
+        if (md == NULL) {
+            KDFerr(KDF_F_KDF_PBKDF2_CTRL, KDF_R_VALUE_MISSING);
             return 0;
+        }
 
         impl->md = md;
         return 1;
@@ -159,6 +188,9 @@ static int kdf_pbkdf2_ctrl_str(EVP_KDF_IMPL *impl, const char *type,
     if (strcmp(type, "digest") == 0)
         return kdf_md2ctrl(impl, kdf_pbkdf2_ctrl, EVP_KDF_CTRL_SET_MD, value);
 
+    if (strcmp(type, "pkcs5") == 0)
+        return kdf_str2ctrl(impl, kdf_pbkdf2_ctrl,
+                            EVP_KDF_CTRL_SET_PBKDF2_PKCS5_MODE, value);
     return -2;
 }
 
@@ -175,9 +207,9 @@ static int kdf_pbkdf2_derive(EVP_KDF_IMPL *impl, unsigned char *key,
         return 0;
     }
 
-    return pkcs5_pbkdf2_alg((char *)impl->pass, impl->pass_len,
-                            impl->salt, impl->salt_len, impl->iter,
-                            impl->md, key, keylen);
+    return pbkdf2_derive((char *)impl->pass, impl->pass_len,
+                         impl->salt, impl->salt_len, impl->iter,
+                         impl->md, key, keylen, impl->lower_bound_checks);
 }
 
 const EVP_KDF pbkdf2_kdf_meth = {
@@ -195,12 +227,16 @@ const EVP_KDF pbkdf2_kdf_meth = {
  * This is an implementation of PKCS#5 v2.0 password based encryption key
  * derivation function PBKDF2. SHA1 version verified against test vectors
  * posted by Peter Gutmann to the PKCS-TNG mailing list.
+ *
+ * The constraints specified by SP800-132 have been added i.e.
+ *  - Check the range of the key length.
+ *  - Minimum iteration count of 1000.
+ *  - Randomly-generated portion of the salt shall be at least 128 bits.
  */
-
-static int pkcs5_pbkdf2_alg(const char *pass, size_t passlen,
-                            const unsigned char *salt, int saltlen, int iter,
-                            const EVP_MD *digest, unsigned char *key,
-                            size_t keylen)
+static int pbkdf2_derive(const char *pass, size_t passlen,
+                         const unsigned char *salt, int saltlen, int iter,
+                         const EVP_MD *digest, unsigned char *key,
+                         size_t keylen, int lower_bound_checks)
 {
     int ret = 0;
     unsigned char digtmp[EVP_MAX_MD_SIZE], *p, itmp[4];
@@ -209,8 +245,32 @@ static int pkcs5_pbkdf2_alg(const char *pass, size_t passlen,
     HMAC_CTX *hctx_tpl = NULL, *hctx = NULL;
 
     mdlen = EVP_MD_size(digest);
-    if (mdlen < 0)
+    if (mdlen <= 0)
+        return 0;
+
+    /*
+     * This check should always be done because keylen / mdlen >= (2^32 - 1)
+     * results in an overflow of the loop counter 'i'.
+     */
+    if ((keylen / mdlen) >= KDF_PBKDF2_MAX_KEY_LEN_DIGEST_RATIO) {
+        KDFerr(KDF_F_PBKDF2_DERIVE, KDF_R_INVALID_KEY_LEN);
         return 0;
+    }
+
+    if (lower_bound_checks) {
+         if ((keylen * 8) < KDF_PBKDF2_MIN_KEY_LEN_BITS) {
+             KDFerr(KDF_F_PBKDF2_DERIVE, KDF_R_INVALID_KEY_LEN);
+             return 0;
+         }
+         if (saltlen < KDF_PBKDF2_MIN_SALT_LEN) {
+             KDFerr(KDF_F_PBKDF2_DERIVE, KDF_R_INVALID_SALT_LEN);
+            return 0;
+         }
+         if (iter < KDF_PBKDF2_MIN_ITERATIONS) {
+             KDFerr(KDF_F_PBKDF2_DERIVE, KDF_R_INVALID_ITERATION_COUNT);
+             return 0;
+         }
+    }
 
     hctx_tpl = HMAC_CTX_new();
     if (hctx_tpl == NULL)