Add internal functions to fetch PEM data from an opened BIO

store_attach_pem_bio() creates a STORE_CTX with the 'file' scheme
loader backend in PEM reading mode on an already opened BIO.
store_detach_pem_bio() detaches the STORE_CTX from the BIO and
destroys it (without destroying the BIO).

These two functions can be used in place of STORE_open() and
STORE_close(), and are present as internal support for other OpenSSL
functions.

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2745)

4 files changed, 80 insertions, 0 deletions

diff --git a/crypto/store/loader_file.c b/crypto/store/loader_file.c
index 8c8b81eb74..2b0f213df0 100644
--- a/crypto/store/loader_file.c
+++ b/crypto/store/loader_file.c
@@ -25,6 +25,7 @@
 #include "internal/asn1_int.h"
 #include "internal/o_dir.h"
 #include "internal/cryptlib.h"
+#include "internal/store_int.h"
 #include "store_locl.h"
 
 #include "e_os.h"
@@ -800,6 +801,23 @@ static int file_ctrl(OSSL_STORE_LOADER_CTX *ctx, int cmd, va_list args)
     return ret;
 }
 
+/* Internal function to decode an already opened PEM file */
+OSSL_STORE_LOADER_CTX *ossl_store_file_attach_pem_bio_int(BIO *bp)
+{
+    OSSL_STORE_LOADER_CTX *ctx = OPENSSL_zalloc(sizeof(*ctx));
+
+    if (ctx == NULL) {
+        OSSL_STOREerr(OSSL_STORE_F_OSSL_STORE_FILE_ATTACH_PEM_BIO_INT,
+                      ERR_R_MALLOC_FAILURE);
+        return NULL;
+    }
+
+    ctx->_.file.file = bp;
+    ctx->type = is_pem;
+
+    return ctx;
+}
+
 static OSSL_STORE_INFO *file_load_try_decode(OSSL_STORE_LOADER_CTX *ctx,
                                              const char *pem_name,
                                              const char *pem_header,
@@ -1158,6 +1176,12 @@ static int file_close(OSSL_STORE_LOADER_CTX *ctx)
     return 1;
 }
 
+int ossl_store_file_detach_pem_bio_int(OSSL_STORE_LOADER_CTX *ctx)
+{
+    OSSL_STORE_LOADER_CTX_free(ctx);
+    return 1;
+}
+
 static OSSL_STORE_LOADER file_loader =
     {
         "file",
diff --git a/crypto/store/store_err.c b/crypto/store/store_err.c
index 8f1a9be195..aad643b163 100644
--- a/crypto/store/store_err.c
+++ b/crypto/store/store_err.c
@@ -23,6 +23,10 @@ static const ERR_STRING_DATA OSSL_STORE_str_functs[] = {
     {ERR_PACK(ERR_LIB_OSSL_STORE, OSSL_STORE_F_FILE_NAME_TO_URI, 0),
      "file_name_to_uri"},
     {ERR_PACK(ERR_LIB_OSSL_STORE, OSSL_STORE_F_FILE_OPEN, 0), "file_open"},
+    {ERR_PACK(ERR_LIB_OSSL_STORE, OSSL_STORE_F_OSSL_STORE_ATTACH_PEM_BIO, 0),
+     "ossl_store_attach_pem_bio"},
+    {ERR_PACK(ERR_LIB_OSSL_STORE, OSSL_STORE_F_OSSL_STORE_FILE_ATTACH_PEM_BIO_INT, 0),
+     "ossl_store_file_attach_pem_bio_int"},
     {ERR_PACK(ERR_LIB_OSSL_STORE, OSSL_STORE_F_OSSL_STORE_GET0_LOADER_INT, 0),
      "ossl_store_get0_loader_int"},
     {ERR_PACK(ERR_LIB_OSSL_STORE, OSSL_STORE_F_OSSL_STORE_INFO_GET1_CERT, 0),
diff --git a/crypto/store/store_lib.c b/crypto/store/store_lib.c
index 2c8ce86a27..d5bb8b88ce 100644
--- a/crypto/store/store_lib.c
+++ b/crypto/store/store_lib.c
@@ -14,6 +14,7 @@
 #include <openssl/err.h>
 #include <openssl/store.h>
 #include "internal/thread_once.h"
+#include "internal/store_int.h"
 #include "store_locl.h"
 
 struct ossl_store_ctx_st {
@@ -407,3 +408,46 @@ char *ossl_store_info_get0_EMBEDDED_pem_name(OSSL_STORE_INFO *info)
         return info->_.embedded.pem_name;
     return NULL;
 }
+
+OSSL_STORE_CTX *ossl_store_attach_pem_bio(BIO *bp, const UI_METHOD *ui_method,
+                                          void *ui_data)
+{
+    OSSL_STORE_CTX *ctx = NULL;
+    const OSSL_STORE_LOADER *loader = NULL;
+    OSSL_STORE_LOADER_CTX *loader_ctx = NULL;
+
+    if ((loader = ossl_store_get0_loader_int("file")) == NULL
+        || ((loader_ctx = ossl_store_file_attach_pem_bio_int(bp)) == NULL))
+        goto done;
+    if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL) {
+        OSSL_STOREerr(OSSL_STORE_F_OSSL_STORE_ATTACH_PEM_BIO,
+                     ERR_R_MALLOC_FAILURE);
+        goto done;
+    }
+
+    ctx->loader = loader;
+    ctx->loader_ctx = loader_ctx;
+    loader_ctx = NULL;
+    ctx->ui_method = ui_method;
+    ctx->ui_data = ui_data;
+    ctx->post_process = NULL;
+    ctx->post_process_data = NULL;
+
+ done:
+    if (loader_ctx != NULL)
+        /*
+         * We ignore a returned error because we will return NULL anyway in
+         * this case, so if something goes wrong when closing, that'll simply
+         * just add another entry on the error stack.
+         */
+        (void)loader->close(loader_ctx);
+    return ctx;
+}
+
+int ossl_store_detach_pem_bio(OSSL_STORE_CTX *ctx)
+{
+    int loader_ret = ossl_store_file_detach_pem_bio_int(ctx->loader_ctx);
+
+    OPENSSL_free(ctx);
+    return loader_ret;
+}
diff --git a/crypto/store/store_locl.h b/crypto/store/store_locl.h
index a954c577c4..789d332810 100644
--- a/crypto/store/store_locl.h
+++ b/crypto/store/store_locl.h
@@ -92,3 +92,11 @@ void ossl_store_destroy_loaders_int(void);
 
 int ossl_store_init_once(void);
 int ossl_store_file_loader_init(void);
+
+/*-
+ *  'file' scheme stuff
+ *  -------------------
+ */
+
+OSSL_STORE_LOADER_CTX *ossl_store_file_attach_pem_bio_int(BIO *bp);
+int ossl_store_file_detach_pem_bio_int(OSSL_STORE_LOADER_CTX *ctx);