CORE: Generalise internal pass phrase prompter

The pass phrase prompter that's part of OSSL_ENCODER and OSSL_DECODER
is really a passphrase callback bridge between the diverse forms of
prompters that exist within OpenSSL: pem_password_cb, ui_method and
OSSL_PASSPHRASE_CALLBACK.

This can be generalised, to be re-used by other parts of OpenSSL, and
to thereby allow the users to specify whatever form of pass phrase
callback they need, while being able to pass that on to other APIs
that are called internally, in the form that those APIs demand.

Additionally, we throw in the possibility to cache pass phrases during
a "session" (we leave it to each API to define what a "session" is).
This is useful for any API that implements discovery and therefore may
need to get the same password more than once, such as OSSL_DECODER and
OSSL_STORE.

Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/12512)

10 files changed, 348 insertions, 311 deletions

diff --git a/crypto/build.info b/crypto/build.info
index 07e3dd526f..9e10145d3c 100644
--- a/crypto/build.info
+++ b/crypto/build.info
@@ -71,7 +71,7 @@ $UTIL_COMMON=\
         cryptlib.c params.c params_from_text.c bsearch.c ex_data.c o_str.c \
         ctype.c threads_pthread.c threads_win.c threads_none.c initthread.c \
         context.c sparse_array.c asn1_dsa.c packet.c param_build.c $CPUIDASM \
-        param_build_set.c der_writer.c
+        param_build_set.c der_writer.c passphrase.c
 $UTIL_DEFINE=$CPUIDDEF
 
 SOURCE[../libcrypto]=$UTIL_COMMON \
diff --git a/crypto/encode_decode/build.info b/crypto/encode_decode/build.info
index 4686c4a19d..e2cd846673 100644
--- a/crypto/encode_decode/build.info
+++ b/crypto/encode_decode/build.info
@@ -1,8 +1,5 @@
-SOURCE[../../libcrypto]=endecode_pass.c
-
 SOURCE[../../libcrypto]=encoder_meth.c encoder_lib.c encoder_pkey.c
-SOURCE[../../libcrypto]=decoder_meth.c decoder_lib.c \
-        decoder_pkey.c
+SOURCE[../../libcrypto]=decoder_meth.c decoder_lib.c decoder_pkey.c
 
 SOURCE[../../libcrypto]=encoder_err.c
 SOURCE[../../libcrypto]=decoder_err.c
diff --git a/crypto/encode_decode/decoder_lib.c b/crypto/encode_decode/decoder_lib.c
index cd6215e309..5d18ef1eff 100644
--- a/crypto/encode_decode/decoder_lib.c
+++ b/crypto/encode_decode/decoder_lib.c
@@ -11,6 +11,7 @@
 #include <openssl/bio.h>
 #include <openssl/params.h>
 #include <openssl/provider.h>
+#include "internal/passphrase.h"
 #include "encoder_local.h"
 #include "e_os.h"
 
@@ -35,13 +36,14 @@ int OSSL_DECODER_from_bio(OSSL_DECODER_CTX *ctx, BIO *in)
     data.ctx = ctx;
     data.bio = in;
 
+    /* Enable passphrase caching */
+    (void)ossl_pw_enable_passphrase_caching(&ctx->pwdata);
+
     ok = decoder_process(NULL, &data);
 
     /* Clear any internally cached passphrase */
-    if (!ctx->flag_user_passphrase) {
-        OSSL_DECODER_CTX_set_passphrase(ctx, NULL, 0);
-        ctx->flag_user_passphrase = 0;
-    }
+    (void)ossl_pw_clear_passphrase_cache(&ctx->pwdata);
+
     return ok;
 }
 
@@ -472,7 +474,8 @@ static int decoder_process(const OSSL_PARAM params[], void *arg)
         new_data.current_deser_inst_index = i;
         ok = new_deser->decode(new_deser_inst->deserctx, (OSSL_CORE_BIO *)bio,
                                decoder_process, &new_data,
-                               ctx->passphrase_cb, new_data.ctx);
+                               ossl_pw_passphrase_callback_dec,
+                               &new_data.ctx->pwdata);
         if (ok)
             break;
     }
diff --git a/crypto/encode_decode/decoder_meth.c b/crypto/encode_decode/decoder_meth.c
index 2259c6348a..409bb1aa54 100644
--- a/crypto/encode_decode/decoder_meth.c
+++ b/crypto/encode_decode/decoder_meth.c
@@ -492,7 +492,6 @@ OSSL_DECODER_CTX *OSSL_DECODER_CTX_new(void)
         return NULL;
     }
 
-    ctx->passphrase_cb = ossl_decoder_passphrase_in_cb;
     return ctx;
 }
 
@@ -545,8 +544,7 @@ void OSSL_DECODER_CTX_free(OSSL_DECODER_CTX *ctx)
             ctx->cleanup(ctx->construct_data);
         sk_OSSL_DECODER_INSTANCE_pop_free(ctx->decoder_insts,
                                           OSSL_DECODER_INSTANCE_free);
-        OSSL_DECODER_CTX_set_passphrase_ui(ctx, NULL, NULL);
-        OSSL_DECODER_CTX_set_passphrase(ctx, NULL, 0);
+        ossl_pw_clear_passphrase_data(&ctx->pwdata);
         OPENSSL_free(ctx);
     }
 }
diff --git a/crypto/encode_decode/decoder_pkey.c b/crypto/encode_decode/decoder_pkey.c
index db75041d17..92c0d5a6ea 100644
--- a/crypto/encode_decode/decoder_pkey.c
+++ b/crypto/encode_decode/decoder_pkey.c
@@ -20,79 +20,20 @@ int OSSL_DECODER_CTX_set_passphrase(OSSL_DECODER_CTX *ctx,
                                     const unsigned char *kstr,
                                     size_t klen)
 {
-    if (!ossl_assert(ctx != NULL)) {
-        ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_PASSED_NULL_PARAMETER);
-        return 0;
-    }
-
-    OPENSSL_clear_free(ctx->cached_passphrase, ctx->cached_passphrase_len);
-    ctx->cached_passphrase = NULL;
-    ctx->cached_passphrase_len = 0;
-    if (kstr != NULL) {
-        if (klen == 0) {
-            ctx->cached_passphrase = OPENSSL_zalloc(1);
-            ctx->cached_passphrase_len = 0;
-        } else {
-            ctx->cached_passphrase = OPENSSL_memdup(kstr, klen);
-            ctx->cached_passphrase_len = klen;
-        }
-        if (ctx->cached_passphrase == NULL) {
-            ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_MALLOC_FAILURE);
-            return 0;
-        }
-    }
-    ctx->flag_user_passphrase = 1;
-    return 1;
-}
-
-static void decoder_ctx_reset_passphrase_ui(OSSL_DECODER_CTX *ctx)
-{
-    UI_destroy_method(ctx->allocated_ui_method);
-    ctx->allocated_ui_method = NULL;
-    ctx->ui_method = NULL;
-    ctx->ui_data = NULL;
+    return ossl_pw_set_passphrase(&ctx->pwdata, kstr, klen);
 }
 
 int OSSL_DECODER_CTX_set_passphrase_ui(OSSL_DECODER_CTX *ctx,
                                        const UI_METHOD *ui_method,
                                        void *ui_data)
 {
-    if (!ossl_assert(ctx != NULL)) {
-        ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_PASSED_NULL_PARAMETER);
-        return 0;
-    }
-
-    decoder_ctx_reset_passphrase_ui(ctx);
-    ctx->ui_method = ui_method;
-    ctx->ui_data = ui_data;
-    return 1;
+    return ossl_pw_set_ui_method(&ctx->pwdata, ui_method, ui_data);
 }
 
 int OSSL_DECODER_CTX_set_pem_password_cb(OSSL_DECODER_CTX *ctx,
                                          pem_password_cb *cb, void *cbarg)
 {
-    UI_METHOD *ui_method = NULL;
-
-    if (!ossl_assert(ctx != NULL)) {
-        ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_PASSED_NULL_PARAMETER);
-        return 0;
-    }
-
-    /*
-     * If |cb| is NULL, it means the caller wants to reset previous
-     * password callback info.  Otherwise, we only set the new data
-     * if a new UI_METHOD could be created for this sort of callback.
-     */
-    if (cb == NULL
-        || (ui_method = UI_UTIL_wrap_read_pem_callback(cb, 0)) != NULL) {
-        decoder_ctx_reset_passphrase_ui(ctx);
-        ctx->ui_method = ctx->allocated_ui_method = ui_method;
-        ctx->ui_data = cbarg;
-        ctx->passphrase_cb = ossl_decoder_passphrase_in_cb;
-        return 1;
-    }
-
-    return 0;
+    return ossl_pw_set_pem_password_cb(&ctx->pwdata, cb, cbarg);
 }
 
 /*
diff --git a/crypto/encode_decode/encoder_local.h b/crypto/encode_decode/encoder_local.h
index 34931d4e43..749b2688e4 100644
--- a/crypto/encode_decode/encoder_local.h
+++ b/crypto/encode_decode/encoder_local.h
@@ -13,6 +13,7 @@
 #include <openssl/encoder.h>
 #include <openssl/decoder.h>
 #include "internal/cryptlib.h"
+#include "internal/passphrase.h"
 #include "internal/refcount.h"
 
 struct ossl_serdes_base_st {
@@ -64,13 +65,7 @@ struct ossl_encoder_ctx_st {
     int (*do_output)(OSSL_ENCODER_CTX *ctx, BIO *out);
 
     /* For any function that needs a passphrase reader */
-    const UI_METHOD *ui_method;
-    void *ui_data;
-    /*
-     * if caller used OSSL_ENCODER_CTX_set_passphrase_cb(), we need
-     * intermediary storage.
-     */
-    UI_METHOD *allocated_ui_method;
+    struct ossl_passphrase_data_st pwdata;
 };
 
 struct ossl_decoder_instance_st {
@@ -103,38 +98,5 @@ struct ossl_decoder_ctx_st {
     void *construct_data;
 
     /* For any function that needs a passphrase reader */
-    OSSL_PASSPHRASE_CALLBACK *passphrase_cb;
-    const UI_METHOD *ui_method;
-    void *ui_data;
-    /*
-     * if caller used OSSL_ENCODER_CTX_set_pem_password_cb(), we need
-     * intermediary storage.
-     */
-    UI_METHOD *allocated_ui_method;
-    /*
-     * Because the same input may pass through more than one decoder,
-     * we cache any passphrase passed to us.  The desrializing processor
-     * must clear this at the end of a run.
-     */
-    unsigned char *cached_passphrase;
-    size_t cached_passphrase_len;
-
-    /*
-     * Flag section.  Keep these together
-     */
-
-    /*
-     * The passphrase was passed to us by the user.  In that case, it
-     * should only be freed when freeing this context.
-     */
-    unsigned int flag_user_passphrase:1;
+    struct ossl_passphrase_data_st pwdata;
 };
-
-/* Passphrase callbacks, found in serdes_pass.c */
-
-/*
- * Encoders typically want to get an outgoing passphrase, while
- * decoders typically want to get en incoming passphrase.
- */
-OSSL_PASSPHRASE_CALLBACK ossl_encoder_passphrase_out_cb;
-OSSL_PASSPHRASE_CALLBACK ossl_decoder_passphrase_in_cb;
diff --git a/crypto/encode_decode/encoder_meth.c b/crypto/encode_decode/encoder_meth.c
index ef3c24433e..81bc5c47b9 100644
--- a/crypto/encode_decode/encoder_meth.c
+++ b/crypto/encode_decode/encoder_meth.c
@@ -517,7 +517,7 @@ void OSSL_ENCODER_CTX_free(OSSL_ENCODER_CTX *ctx)
         if (ctx->encoder != NULL && ctx->encoder->freectx != NULL)
             ctx->encoder->freectx(ctx->serctx);
         OSSL_ENCODER_free(ctx->encoder);
-        UI_destroy_method(ctx->allocated_ui_method);
+        ossl_pw_clear_passphrase_data(&ctx->pwdata);
         OPENSSL_free(ctx);
     }
 }
diff --git a/crypto/encode_decode/encoder_pkey.c b/crypto/encode_decode/encoder_pkey.c
index dc776c023e..6664f589b4 100644
--- a/crypto/encode_decode/encoder_pkey.c
+++ b/crypto/encode_decode/encoder_pkey.c
@@ -48,45 +48,17 @@ int OSSL_ENCODER_CTX_set_passphrase(OSSL_ENCODER_CTX *ctx,
     return OSSL_ENCODER_CTX_set_params(ctx, params);
 }
 
-static void encoder_ctx_reset_passphrase_ui(OSSL_ENCODER_CTX *ctx)
-{
-    UI_destroy_method(ctx->allocated_ui_method);
-    ctx->allocated_ui_method = NULL;
-    ctx->ui_method = NULL;
-    ctx->ui_data = NULL;
-}
-
 int OSSL_ENCODER_CTX_set_passphrase_ui(OSSL_ENCODER_CTX *ctx,
                                        const UI_METHOD *ui_method,
                                        void *ui_data)
 {
-    if (!ossl_assert(ctx != NULL)) {
-        ERR_raise(ERR_LIB_OSSL_ENCODER, ERR_R_PASSED_NULL_PARAMETER);
-        return 0;
-    }
-
-    encoder_ctx_reset_passphrase_ui(ctx);
-    ctx->ui_method = ui_method;
-    ctx->ui_data = ui_data;
-    return 1;
+    return ossl_pw_set_ui_method(&ctx->pwdata, ui_method, ui_data);
 }
 
 int OSSL_ENCODER_CTX_set_passphrase_cb(OSSL_ENCODER_CTX *ctx,
                                        pem_password_cb *cb, void *cbarg)
 {
-    if (!ossl_assert(ctx != NULL)) {
-        ERR_raise(ERR_LIB_OSSL_ENCODER, ERR_R_PASSED_NULL_PARAMETER);
-        return 0;
-    }
-
-    encoder_ctx_reset_passphrase_ui(ctx);
-    if (cb == NULL)
-        return 1;
-    ctx->ui_method =
-        ctx->allocated_ui_method = UI_UTIL_wrap_read_pem_callback(cb, 1);
-    ctx->ui_data = cbarg;
-
-    return ctx->ui_method != NULL;
+    return ossl_pw_set_pem_password_cb(&ctx->pwdata, cb, cbarg);
 }
 
 /*
@@ -125,7 +97,8 @@ static int encoder_write_cb(const OSSL_PARAM params[], void *arg)
     BIO *out = write_data->out;
 
     return ctx->encoder->encode_data(ctx->serctx, params, (OSSL_CORE_BIO *)out,
-                                     ossl_encoder_passphrase_out_cb, ctx);
+                                     ossl_pw_passphrase_callback_enc,
+                                     &ctx->pwdata);
 }
 
 /*
@@ -164,7 +137,8 @@ static int encoder_EVP_PKEY_to_bio(OSSL_ENCODER_CTX *ctx, BIO *out)
 
     return ctx->encoder->encode_object(ctx->serctx, keydata,
                                        (OSSL_CORE_BIO *)out,
-                                       ossl_encoder_passphrase_out_cb, ctx);
+                                       ossl_pw_passphrase_callback_enc,
+                                       &ctx->pwdata);
 }
 
 /*
diff --git a/crypto/encode_decode/endecode_pass.c b/crypto/encode_decode/endecode_pass.c
deleted file mode 100644
index 113f5eeb84..0000000000
--- a/crypto/encode_decode/endecode_pass.c
+++ /dev/null
@@ -1,162 +0,0 @@
-/*
- * Copyright 2020 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
- * in the file LICENSE in the source distribution or at
- * https://www.openssl.org/source/license.html
- */
-
-#include <openssl/err.h>
-#include <openssl/ui.h>
-#include <openssl/core_names.h>
-#include "internal/cryptlib.h"
-#include "encoder_local.h"
-
-/* Passphrase callbacks for any who need it */
-
-/*
- * First, define the generic passphrase function that supports both
- * outgoing (with passphrase verify) and incoming (without passphrase
- * verify) passphrase reading.
- */
-static int do_passphrase(char *pass, size_t pass_size, size_t *pass_len,
-                         const OSSL_PARAM params[], void *arg, int verify,
-                         const UI_METHOD *ui_method, void *ui_data, int errlib)
-{
-    const OSSL_PARAM *p;
-    const char *prompt_info = NULL;
-    char *prompt = NULL, *vpass = NULL;
-    int prompt_idx = -1, verify_idx = -1;
-    UI *ui = NULL;
-    int ret = 0;
-
-    if (!ossl_assert(pass != NULL && pass_size != 0 && pass_len != NULL)) {
-        ERR_raise(errlib, ERR_R_PASSED_NULL_PARAMETER);
-        return 0;
-    }
-
-    if ((p = OSSL_PARAM_locate_const(params,
-                                     OSSL_PASSPHRASE_PARAM_INFO)) != NULL) {
-        if (p->data_type != OSSL_PARAM_UTF8_STRING)
-            return 0;
-        prompt_info = p->data;
-    }
-
-    if ((ui = UI_new()) == NULL) {
-        ERR_raise(errlib, ERR_R_MALLOC_FAILURE);
-        return 0;
-    }
-
-    if (ui_method != NULL) {
-        UI_set_method(ui, ui_method);
-        if (ui_data != NULL)
-            UI_add_user_data(ui, ui_data);
-    }
-
-    /* Get an application constructed prompt */
-    prompt = UI_construct_prompt(ui, "pass phrase", prompt_info);
-    if (prompt == NULL) {
-        ERR_raise(errlib, ERR_R_MALLOC_FAILURE);
-        goto end;
-    }
-
-    prompt_idx = UI_add_input_string(ui, prompt,
-                                     UI_INPUT_FLAG_DEFAULT_PWD,
-                                     pass, 0, pass_size - 1) - 1;
-    if (prompt_idx < 0) {
-        ERR_raise(errlib, ERR_R_UI_LIB);
-        goto end;
-    }
-
-    if (verify) {
-        /* Get a buffer for verification prompt */
-        vpass = OPENSSL_zalloc(pass_size);
-        if (vpass == NULL) {
-            ERR_raise(errlib, ERR_R_MALLOC_FAILURE);
-            goto end;
-        }
-        verify_idx = UI_add_verify_string(ui, prompt,
-                                          UI_INPUT_FLAG_DEFAULT_PWD,
-                                          vpass, 0, pass_size - 1,
-                                          pass) - 1;
-        if (verify_idx < 0) {
-            ERR_raise(errlib, ERR_R_UI_LIB);
-            goto end;
-        }
-    }
-
-    switch (UI_process(ui)) {
-    case -2:
-        ERR_raise(errlib, ERR_R_INTERRUPTED_OR_CANCELLED);
-        break;
-    case -1:
-        ERR_raise(errlib, ERR_R_UI_LIB);
-        break;
-    default:
-        *pass_len = (size_t)UI_get_result_length(ui, prompt_idx);
-        ret = 1;
-        break;
-    }
-
- end:
-    OPENSSL_free(vpass);
-    OPENSSL_free(prompt);
-    UI_free(ui);
-    return ret;
-}
-
-/*
- * Encoders typically want to get an outgoing passphrase, while
- * decoders typically want to get en incoming passphrase.
- */
-int ossl_encoder_passphrase_out_cb(char *pass, size_t pass_size,
-                                   size_t *pass_len,
-                                   const OSSL_PARAM params[], void *arg)
-{
-    OSSL_ENCODER_CTX *ctx = arg;
-
-    if (!ossl_assert(ctx != NULL)) {
-        ERR_raise(ERR_LIB_OSSL_ENCODER, ERR_R_PASSED_NULL_PARAMETER);
-        return 0;
-    }
-
-    return do_passphrase(pass, pass_size, pass_len, params, arg, 1,
-                         ctx->ui_method, ctx->ui_data,
-                         ERR_LIB_OSSL_ENCODER);
-}
-
-int ossl_decoder_passphrase_in_cb(char *pass, size_t pass_size,
-                                  size_t *pass_len,
-                                  const OSSL_PARAM params[], void *arg)
-{
-    OSSL_DECODER_CTX *ctx = arg;
-
-    if (!ossl_assert(ctx != NULL)) {
-        ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_PASSED_NULL_PARAMETER);
-        return 0;
-    }
-
-    if (ctx->cached_passphrase != NULL) {
-        size_t len = ctx->cached_passphrase_len;
-
-        if (len > pass_size)
-            len = pass_size;
-        memcpy(pass, ctx->cached_passphrase, len);
-        *pass_len = len;
-        return 1;
-    } else {
-        if ((ctx->cached_passphrase = OPENSSL_zalloc(pass_size)) == NULL) {
-            ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_MALLOC_FAILURE);
-            return 0;
-        }
-    }
-    if (do_passphrase(pass, pass_size, pass_len, params, arg, 0,
-                      ctx->ui_method, ctx->ui_data,
-                      ERR_LIB_OSSL_DECODER)) {
-        memcpy(ctx->cached_passphrase, pass, *pass_len);
-        ctx->cached_passphrase_len = *pass_len;
-        return 1;
-    }
-    return 0;
-}
diff --git a/crypto/passphrase.c b/crypto/passphrase.c
new file mode 100644
index 0000000000..ac352697db
--- /dev/null
+++ b/crypto/passphrase.c
@@ -0,0 +1,324 @@
+/*
+ * Copyright 2020 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
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+#include <openssl/err.h>
+#include <openssl/ui.h>
+#include <openssl/core_names.h>
+#include "internal/cryptlib.h"
+#include "internal/passphrase.h"
+
+void ossl_pw_clear_passphrase_data(struct ossl_passphrase_data_st *data)
+{
+    if (data != NULL) {
+        if (data->type == is_expl_passphrase)
+            OPENSSL_clear_free(data->_.expl_passphrase.passphrase_copy,
+                               data->_.expl_passphrase.passphrase_len);
+        ossl_pw_clear_passphrase_cache(data);
+        memset(data, 0, sizeof(*data));
+    }
+}
+
+void ossl_pw_clear_passphrase_cache(struct ossl_passphrase_data_st *data)
+{
+    OPENSSL_clear_free(data->cached_passphrase, data->cached_passphrase_len);
+    data->cached_passphrase = NULL;
+}
+
+int ossl_pw_set_passphrase(struct ossl_passphrase_data_st *data,
+                           const unsigned char *passphrase,
+                           size_t passphrase_len)
+{
+    if (!ossl_assert(data != NULL && passphrase != NULL)) {
+        ERR_raise(ERR_LIB_CRYPTO, ERR_R_PASSED_NULL_PARAMETER);
+        return 0;
+    }
+    ossl_pw_clear_passphrase_data(data);
+    data->type = is_expl_passphrase;
+    data->_.expl_passphrase.passphrase_copy =
+        OPENSSL_memdup(passphrase, passphrase_len);
+    if (data->_.expl_passphrase.passphrase_copy == NULL) {
+        ERR_raise(ERR_LIB_CRYPTO, ERR_R_MALLOC_FAILURE);
+        return 0;
+    }
+    data->_.expl_passphrase.passphrase_len = passphrase_len;
+    return 1;
+}
+
+int ossl_pw_set_pem_password_cb(struct ossl_passphrase_data_st *data,
+                                pem_password_cb *cb, void *cbarg)
+{
+    if (!ossl_assert(data != NULL && cb != NULL)) {
+        ERR_raise(ERR_LIB_CRYPTO, ERR_R_PASSED_NULL_PARAMETER);
+        return 0;
+    }
+    ossl_pw_clear_passphrase_data(data);
+    data->type = is_pem_password;
+    data->_.pem_password.password_cb = cb;
+    data->_.pem_password.password_cbarg = cbarg;
+    return 1;
+}
+
+int ossl_pw_set_ossl_passphrase_cb(struct ossl_passphrase_data_st *data,
+                                   OSSL_PASSPHRASE_CALLBACK *cb, void *cbarg)
+{
+    if (!ossl_assert(data != NULL && cb != NULL)) {
+        ERR_raise(ERR_LIB_CRYPTO, ERR_R_PASSED_NULL_PARAMETER);
+        return 0;
+    }
+    ossl_pw_clear_passphrase_data(data);
+    data->type = is_ossl_passphrase;
+    data->_.ossl_passphrase.passphrase_cb = cb;
+    data->_.ossl_passphrase.passphrase_cbarg = cbarg;
+    return 1;
+}
+
+int ossl_pw_set_ui_method(struct ossl_passphrase_data_st *data,
+                          const UI_METHOD *ui_method, void *ui_data)
+{
+    if (!ossl_assert(data != NULL && ui_method != NULL)) {
+        ERR_raise(ERR_LIB_CRYPTO, ERR_R_PASSED_NULL_PARAMETER);
+        return 0;
+    }
+    ossl_pw_clear_passphrase_data(data);
+    data->type = is_ui_method;
+    data->_.ui_method.ui_method = ui_method;
+    data->_.ui_method.ui_method_data = ui_data;
+    return 1;
+}
+
+int ossl_pw_enable_passphrase_caching(struct ossl_passphrase_data_st *data)
+{
+    data->flag_cache_passphrase = 1;
+    return 1;
+}
+
+int ossl_pw_disable_passphrase_caching(struct ossl_passphrase_data_st *data)
+{
+    data->flag_cache_passphrase = 0;
+    return 1;
+}
+
+
+/*-
+ * UI_METHOD processor.  It differs from UI_UTIL_read_pw() like this:
+ *
+ * 1.  It constructs a prompt on its own, based on |prompt_info|.
+ * 2.  It allocates a buffer for verification on its own.
+ * 3.  It raises errors.
+ * 4.  It reports back the length of the prompted pass phrase.
+ */
+static int do_ui_passphrase(char *pass, size_t pass_size, size_t *pass_len,
+                            const char *prompt_info, int verify,
+                            const UI_METHOD *ui_method, void *ui_data)
+{
+    char *prompt = NULL, *vpass = NULL;
+    int prompt_idx = -1, verify_idx = -1;
+    UI *ui = NULL;
+    int ret = 0;
+
+    if (!ossl_assert(pass != NULL && pass_size != 0 && pass_len != NULL)) {
+        ERR_raise(ERR_LIB_CRYPTO, ERR_R_PASSED_NULL_PARAMETER);
+        return 0;
+    }
+
+    if ((ui = UI_new()) == NULL) {
+        ERR_raise(ERR_LIB_CRYPTO, ERR_R_MALLOC_FAILURE);
+        return 0;
+    }
+
+    if (ui_method != NULL) {
+        UI_set_method(ui, ui_method);
+        if (ui_data != NULL)
+            UI_add_user_data(ui, ui_data);
+    }
+
+    /* Get an application constructed prompt */
+    prompt = UI_construct_prompt(ui, "pass phrase", prompt_info);
+    if (prompt == NULL) {
+        ERR_raise(ERR_LIB_CRYPTO, ERR_R_MALLOC_FAILURE);
+        goto end;
+    }
+
+    prompt_idx = UI_add_input_string(ui, prompt,
+                                     UI_INPUT_FLAG_DEFAULT_PWD,
+                                     pass, 0, pass_size - 1) - 1;
+    if (prompt_idx < 0) {
+        ERR_raise(ERR_LIB_CRYPTO, ERR_R_UI_LIB);
+        goto end;
+    }
+
+    if (verify) {
+        /* Get a buffer for verification prompt */
+        vpass = OPENSSL_zalloc(pass_size);
+        if (vpass == NULL) {
+            ERR_raise(ERR_LIB_CRYPTO, ERR_R_MALLOC_FAILURE);
+            goto end;
+        }
+        verify_idx = UI_add_verify_string(ui, prompt,
+                                          UI_INPUT_FLAG_DEFAULT_PWD,
+                                          vpass, 0, pass_size - 1,
+                                          pass) - 1;
+        if (verify_idx < 0) {
+            ERR_raise(ERR_LIB_CRYPTO, ERR_R_UI_LIB);
+            goto end;
+        }
+    }
+
+    switch (UI_process(ui)) {
+    case -2:
+        ERR_raise(ERR_LIB_CRYPTO, ERR_R_INTERRUPTED_OR_CANCELLED);
+        break;
+    case -1:
+        ERR_raise(ERR_LIB_CRYPTO, ERR_R_UI_LIB);
+        break;
+    default:
+        *pass_len = (size_t)UI_get_result_length(ui, prompt_idx);
+        ret = 1;
+        break;
+    }
+
+ end:
+    OPENSSL_free(vpass);
+    OPENSSL_free(prompt);
+    UI_free(ui);
+    return ret;
+}
+
+/* Central pw prompting dispatcher */
+int ossl_pw_get_passphrase(char *pass, size_t pass_size, size_t *pass_len,
+                           const OSSL_PARAM params[], int verify,
+                           struct ossl_passphrase_data_st *data)
+{
+    const char *source = NULL;
+    size_t source_len = 0;
+    const char *prompt_info = NULL;
+    const UI_METHOD *ui_method = NULL;
+    UI_METHOD *allocated_ui_method = NULL;
+    void *ui_data = NULL;
+    const OSSL_PARAM *p = NULL;
+    int ret;
+
+    /* Handle explicit and cached passphrases */
+
+    if (data->type == is_expl_passphrase) {
+        source = data->_.expl_passphrase.passphrase_copy;
+        source_len = data->_.expl_passphrase.passphrase_len;
+    } else if (data->flag_cache_passphrase && data->cached_passphrase != NULL) {
+        source = data->cached_passphrase;
+        source_len = data->cached_passphrase_len;
+    }
+
+    if (source != NULL) {
+        if (source_len > pass_size)
+            source_len = pass_size;
+        memcpy(pass, source, source_len);
+        *pass_len = source_len;
+        return 1;
+    }
+
+    /* Handle the is_ossl_passphrase case...  that's pretty direct */
+
+    if (data->type == is_ossl_passphrase) {
+        OSSL_PASSPHRASE_CALLBACK *cb = data->_.ossl_passphrase.passphrase_cb;
+        void *cbarg = data->_.ossl_passphrase.passphrase_cbarg;
+
+        ret = cb(pass, pass_size, pass_len, params, cbarg);
+        goto do_cache;
+    }
+
+    /* Handle the is_pem_password and is_ui_method cases */
+
+    if ((p = OSSL_PARAM_locate_const(params,
+                                     OSSL_PASSPHRASE_PARAM_INFO)) != NULL) {
+        if (p->data_type != OSSL_PARAM_UTF8_STRING) {
+            ERR_raise_data(ERR_LIB_CRYPTO, ERR_R_PASSED_INVALID_ARGUMENT,
+                           "Prompt info data type incorrect");
+            return 0;
+        }
+        prompt_info = p->data;
+    }
+
+    if (data->type == is_pem_password) {
+        /* We use a UI wrapper for PEM */
+        pem_password_cb *cb = data->_.pem_password.password_cb;
+
+        ui_method = allocated_ui_method =
+            UI_UTIL_wrap_read_pem_callback(cb, verify);
+        ui_data = data->_.pem_password.password_cbarg;
+
+        if (ui_method == NULL) {
+            ERR_raise(ERR_LIB_CRYPTO, ERR_R_MALLOC_FAILURE);
+            return 0;
+        }
+    } else if (data->type == is_ui_method) {
+        ui_method = data->_.ui_method.ui_method;
+        ui_data = data->_.ui_method.ui_method_data;
+    }
+
+    if (ui_method == NULL) {
+        ERR_raise(ERR_LIB_CRYPTO, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+
+    ret = do_ui_passphrase(pass, pass_size, pass_len, prompt_info, verify,
+                           ui_method, ui_data);
+
+    UI_destroy_method(allocated_ui_method);
+
+ do_cache:
+    if (ret && data->flag_cache_passphrase) {
+        if (*pass_len > data->cached_passphrase_len) {
+            void *new_cache =
+                OPENSSL_clear_realloc(data->cached_passphrase,
+                                      data->cached_passphrase_len,
+                                      *pass_len + 1);
+
+            if (new_cache == NULL) {
+                OPENSSL_cleanse(pass, *pass_len);
+                ERR_raise(ERR_LIB_CRYPTO, ERR_R_MALLOC_FAILURE);
+                return 0;
+            }
+            data->cached_passphrase = new_cache;
+        }
+        memcpy(data->cached_passphrase, pass, *pass_len);
+        data->cached_passphrase[*pass_len] = '\0';
+        data->cached_passphrase_len = *pass_len;
+    }
+
+    return ret;
+}
+
+int ossl_pw_pem_password(char *buf, int size, int rwflag, void *userdata)
+{
+    size_t password_len = 0;
+    OSSL_PARAM params[] = {
+        OSSL_PARAM_utf8_string(OSSL_PASSPHRASE_PARAM_INFO, NULL, 0),
+        OSSL_PARAM_END
+    };
+
+    params[0].data = "PEM";
+    if (ossl_pw_get_passphrase(buf, (size_t)size, &password_len, params,
+                               rwflag, userdata))
+        return (int)password_len;
+    return -1;
+}
+
+int ossl_pw_passphrase_callback_enc(char *pass, size_t pass_size,
+                                    size_t *pass_len,
+                                    const OSSL_PARAM params[], void *arg)
+{
+    return ossl_pw_get_passphrase(pass, pass_size, pass_len, params, 1, arg);
+}
+
+int ossl_pw_passphrase_callback_dec(char *pass, size_t pass_size,
+                                    size_t *pass_len,
+                                    const OSSL_PARAM params[], void *arg)
+{
+    return ossl_pw_get_passphrase(pass, pass_size, pass_len, params, 0, arg);
+}