Add interface to the scrypt KDF by means of PKEY_METHOD

Add an interface that allows accessing the scrypt KDF as a PKEY_METHOD.
This fixes #4021 (at least for the scrypt portion of the issue).

Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Stephen Henson <steve@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4026)

3 files changed, 269 insertions, 1 deletions

diff --git a/crypto/kdf/build.info b/crypto/kdf/build.info
index cbe2080ed7..c166399d0c 100644
--- a/crypto/kdf/build.info
+++ b/crypto/kdf/build.info
@@ -1,3 +1,3 @@
 LIBS=../../libcrypto
 SOURCE[../../libcrypto]=\
-        tls1_prf.c kdf_err.c hkdf.c
+        tls1_prf.c kdf_err.c hkdf.c scrypt.c
diff --git a/crypto/kdf/kdf_err.c b/crypto/kdf/kdf_err.c
index 8d2727217d..c7b84b0f51 100644
--- a/crypto/kdf/kdf_err.c
+++ b/crypto/kdf/kdf_err.c
@@ -16,6 +16,11 @@
 static const ERR_STRING_DATA KDF_str_functs[] = {
     {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"},
+    {ERR_PACK(ERR_LIB_KDF, KDF_F_PKEY_SCRYPT_CTRL_STR, 0),
+     "pkey_scrypt_ctrl_str"},
+    {ERR_PACK(ERR_LIB_KDF, KDF_F_PKEY_SCRYPT_CTRL_UINT64, 0),
+     "pkey_scrypt_ctrl_uint64"},
+    {ERR_PACK(ERR_LIB_KDF, KDF_F_PKEY_SCRYPT_DERIVE, 0), "pkey_scrypt_derive"},
     {ERR_PACK(ERR_LIB_KDF, KDF_F_PKEY_TLS1_PRF_CTRL_STR, 0),
      "pkey_tls1_prf_ctrl_str"},
     {ERR_PACK(ERR_LIB_KDF, KDF_F_PKEY_TLS1_PRF_DERIVE, 0),
@@ -25,14 +30,19 @@ 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_MISSING_ITERATION_COUNT),
+    "missing iteration count"},
     {ERR_PACK(ERR_LIB_KDF, 0, KDF_R_MISSING_KEY), "missing key"},
     {ERR_PACK(ERR_LIB_KDF, 0, KDF_R_MISSING_MESSAGE_DIGEST),
     "missing message digest"},
     {ERR_PACK(ERR_LIB_KDF, 0, KDF_R_MISSING_PARAMETER), "missing parameter"},
+    {ERR_PACK(ERR_LIB_KDF, 0, KDF_R_MISSING_PASS), "missing pass"},
+    {ERR_PACK(ERR_LIB_KDF, 0, KDF_R_MISSING_SALT), "missing salt"},
     {ERR_PACK(ERR_LIB_KDF, 0, KDF_R_MISSING_SECRET), "missing secret"},
     {ERR_PACK(ERR_LIB_KDF, 0, KDF_R_MISSING_SEED), "missing seed"},
     {ERR_PACK(ERR_LIB_KDF, 0, KDF_R_UNKNOWN_PARAMETER_TYPE),
     "unknown parameter type"},
+    {ERR_PACK(ERR_LIB_KDF, 0, KDF_R_VALUE_ERROR), "value error"},
     {ERR_PACK(ERR_LIB_KDF, 0, KDF_R_VALUE_MISSING), "value missing"},
     {0, NULL}
 };
diff --git a/crypto/kdf/scrypt.c b/crypto/kdf/scrypt.c
new file mode 100644
index 0000000000..c7aa823e49
--- /dev/null
+++ b/crypto/kdf/scrypt.c
@@ -0,0 +1,258 @@
+/*
+ * Copyright 2017 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the OpenSSL license (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <openssl/hmac.h>
+#include <openssl/kdf.h>
+#include <openssl/evp.h>
+#include "internal/cryptlib.h"
+#include "internal/evp_int.h"
+
+static int atou64(const char *nptr, uint64_t *result);
+
+typedef struct {
+    unsigned char *pass;
+    size_t pass_len;
+    unsigned char *salt;
+    size_t salt_len;
+    uint64_t N, r, p;
+    uint64_t maxmem_bytes;
+} SCRYPT_PKEY_CTX;
+
+/* Custom uint64_t parser since we do not have strtoull */
+static int atou64(const char *nptr, uint64_t *result)
+{
+    uint64_t value = 0;
+
+    while (*nptr) {
+        unsigned int digit;
+        uint64_t new_value;
+
+        if ((*nptr < '0') || (*nptr > '9')) {
+            return 0;
+        }
+        digit = (unsigned int)(*nptr - '0');
+        new_value = (value * 10) + digit;
+        if ((new_value < digit) || ((new_value - digit) / 10 != value)) {
+            /* Overflow */
+            return 0;
+        }
+        value = new_value;
+        nptr++;
+    }
+    *result = value;
+    return 1;
+}
+
+static int pkey_scrypt_init(EVP_PKEY_CTX *ctx)
+{
+    SCRYPT_PKEY_CTX *kctx;
+
+    kctx = OPENSSL_zalloc(sizeof(*kctx));
+    if (kctx == NULL)
+        return 0;
+
+    /* Default values are the most conservative recommendation given in the
+     * original paper of C. Percival. Derivation uses roughly 1 GiB of memory
+     * for this parameter choice (approx. 128 * r * (N + p) bytes).
+     */
+    kctx->N = 1 << 20;
+    kctx->r = 8;
+    kctx->p = 1;
+    kctx->maxmem_bytes = 1025 * 1024 * 1024;
+
+    ctx->data = kctx;
+
+    return 1;
+}
+
+static void pkey_scrypt_cleanup(EVP_PKEY_CTX *ctx)
+{
+    SCRYPT_PKEY_CTX *kctx = ctx->data;
+
+    OPENSSL_clear_free(kctx->salt, kctx->salt_len);
+    OPENSSL_clear_free(kctx->pass, kctx->pass_len);
+    OPENSSL_free(kctx);
+}
+
+static int pkey_scrypt_set_membuf(unsigned char **buffer, size_t *buflen,
+                                  const unsigned char *new_buffer,
+                                  const int new_buflen)
+{
+    if (new_buffer == NULL)
+        return 1;
+
+    if (new_buflen < 0)
+        return 0;
+
+    if (*buffer != NULL)
+        OPENSSL_clear_free(*buffer, *buflen);
+
+    if (new_buflen > 0) {
+        *buffer = OPENSSL_memdup(new_buffer, new_buflen);
+    } else {
+        *buffer = OPENSSL_malloc(1);
+    }
+    if (*buffer == NULL)
+        return 0;
+
+    *buflen = new_buflen;
+    return 1;
+}
+
+static int is_power_of_two(uint64_t value)
+{
+    return (value != 0) && ((value & (value - 1)) == 0);
+}
+
+static int pkey_scrypt_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
+{
+    SCRYPT_PKEY_CTX *kctx = ctx->data;
+    uint64_t u64_value;
+
+    switch (type) {
+    case EVP_PKEY_CTRL_PASS:
+        return pkey_scrypt_set_membuf(&kctx->pass, &kctx->pass_len, p2, p1);
+
+    case EVP_PKEY_CTRL_SCRYPT_SALT:
+        return pkey_scrypt_set_membuf(&kctx->salt, &kctx->salt_len, p2, p1);
+
+    case EVP_PKEY_CTRL_SCRYPT_N:
+        u64_value = *((uint64_t *)p2);
+        if ((u64_value <= 1) || !is_power_of_two(u64_value))
+            return 0;
+        kctx->N = u64_value;
+        return 1;
+
+    case EVP_PKEY_CTRL_SCRYPT_R:
+        u64_value = *((uint64_t *)p2);
+        if (u64_value < 1)
+            return 0;
+        kctx->r = u64_value;
+        return 1;
+
+    case EVP_PKEY_CTRL_SCRYPT_P:
+        u64_value = *((uint64_t *)p2);
+        if (u64_value < 1)
+            return 0;
+        kctx->p = u64_value;
+        return 1;
+
+    case EVP_PKEY_CTRL_SCRYPT_MAXMEM_BYTES:
+        u64_value = *((uint64_t *)p2);
+        if (u64_value < 1)
+            return 0;
+        kctx->maxmem_bytes = u64_value;
+        return 1;
+
+    default:
+        return -2;
+
+    }
+}
+
+static int pkey_scrypt_ctrl_uint64(EVP_PKEY_CTX *ctx, int type,
+                                   const char *value)
+{
+    uint64_t int_value;
+
+    if (!atou64(value, &int_value)) {
+        KDFerr(KDF_F_PKEY_SCRYPT_CTRL_UINT64, KDF_R_VALUE_ERROR);
+        return 0;
+    }
+    return pkey_scrypt_ctrl(ctx, type, 0, &int_value);
+}
+
+static int pkey_scrypt_ctrl_str(EVP_PKEY_CTX *ctx, const char *type,
+                                const char *value)
+{
+    if (value == NULL) {
+        KDFerr(KDF_F_PKEY_SCRYPT_CTRL_STR, KDF_R_VALUE_MISSING);
+        return 0;
+    }
+
+    if (strcmp(type, "pass") == 0)
+        return EVP_PKEY_CTX_str2ctrl(ctx, EVP_PKEY_CTRL_PASS, value);
+
+    if (strcmp(type, "hexpass") == 0)
+        return EVP_PKEY_CTX_hex2ctrl(ctx, EVP_PKEY_CTRL_PASS, value);
+
+    if (strcmp(type, "salt") == 0)
+        return EVP_PKEY_CTX_str2ctrl(ctx, EVP_PKEY_CTRL_SCRYPT_SALT, value);
+
+    if (strcmp(type, "hexsalt") == 0)
+        return EVP_PKEY_CTX_hex2ctrl(ctx, EVP_PKEY_CTRL_SCRYPT_SALT, value);
+
+    if (strcmp(type, "N") == 0)
+        return pkey_scrypt_ctrl_uint64(ctx, EVP_PKEY_CTRL_SCRYPT_N, value);
+
+    if (strcmp(type, "r") == 0)
+        return pkey_scrypt_ctrl_uint64(ctx, EVP_PKEY_CTRL_SCRYPT_R, value);
+
+    if (strcmp(type, "p") == 0)
+        return pkey_scrypt_ctrl_uint64(ctx, EVP_PKEY_CTRL_SCRYPT_P, value);
+
+    if (strcmp(type, "maxmem_bytes") == 0)
+        return pkey_scrypt_ctrl_uint64(ctx, EVP_PKEY_CTRL_SCRYPT_MAXMEM_BYTES,
+                                       value);
+
+    KDFerr(KDF_F_PKEY_SCRYPT_CTRL_STR, KDF_R_UNKNOWN_PARAMETER_TYPE);
+    return -2;
+}
+
+static int pkey_scrypt_derive(EVP_PKEY_CTX *ctx, unsigned char *key,
+                              size_t *keylen)
+{
+    SCRYPT_PKEY_CTX *kctx = ctx->data;
+
+    if (kctx->pass == NULL) {
+        KDFerr(KDF_F_PKEY_SCRYPT_DERIVE, KDF_R_MISSING_PASS);
+        return 0;
+    }
+
+    if (kctx->salt == NULL) {
+        KDFerr(KDF_F_PKEY_SCRYPT_DERIVE, KDF_R_MISSING_SALT);
+        return 0;
+    }
+
+    return EVP_PBE_scrypt((char *)kctx->pass, kctx->pass_len, kctx->salt,
+                          kctx->salt_len, kctx->N, kctx->r, kctx->p,
+                          kctx->maxmem_bytes, key, *keylen);
+}
+
+const EVP_PKEY_METHOD scrypt_pkey_meth = {
+    EVP_PKEY_SCRYPT,
+    0,
+    pkey_scrypt_init,
+    0,
+    pkey_scrypt_cleanup,
+
+    0, 0,
+    0, 0,
+
+    0,
+    0,
+
+    0,
+    0,
+
+    0, 0,
+
+    0, 0, 0, 0,
+
+    0, 0,
+
+    0, 0,
+
+    0,
+    pkey_scrypt_derive,
+    pkey_scrypt_ctrl,
+    pkey_scrypt_ctrl_str
+};