Add CRYPTO_alloc_ex_data()

This allows allocation of items at indexes that were created after the
CRYPTO_EX_DATA variable was initialized, using the exact same method
that was used then.

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/8225)

5 files changed, 106 insertions, 16 deletions

diff --git a/crypto/ex_data.c b/crypto/ex_data.c
index 33f43bf..a728bfb 100644
--- a/crypto/ex_data.c
+++ b/crypto/ex_data.c
@@ -363,6 +363,36 @@ void CRYPTO_free_ex_data(int class_index, void *obj, CRYPTO_EX_DATA *ad)
 }
 
 /*
+ * Allocate a given CRYPTO_EX_DATA item using the class specific allocation
+ * function
+ */
+int CRYPTO_alloc_ex_data(int class_index, void *obj, CRYPTO_EX_DATA *ad,
+                         int idx)
+{
+    EX_CALLBACK *f;
+    EX_CALLBACKS *ip;
+    void *curval;
+
+    curval = CRYPTO_get_ex_data(ad, idx);
+
+    /* Already there, no need to allocate */
+    if (curval != NULL)
+        return 1;
+
+    ip = get_and_lock(class_index);
+    f = sk_EX_CALLBACK_value(ip->meth, idx);
+    CRYPTO_THREAD_unlock(ex_data_lock);
+
+    /*
+     * This should end up calling CRYPTO_set_ex_data(), which allocates
+     * everything necessary to support placing the new data in the right spot.
+     */
+    f->new_func(obj, curval, ad, idx, f->argl, f->argp);
+
+    return 1;
+}
+
+/*
  * For a given CRYPTO_EX_DATA variable, set the value corresponding to a
  * particular index in the class used by this variable
  */
diff --git a/doc/man3/CRYPTO_get_ex_new_index.pod b/doc/man3/CRYPTO_get_ex_new_index.pod
index a2b39d9..44bab62 100644
--- a/doc/man3/CRYPTO_get_ex_new_index.pod
+++ b/doc/man3/CRYPTO_get_ex_new_index.pod
@@ -3,8 +3,9 @@
 =head1 NAME
 
 CRYPTO_EX_new, CRYPTO_EX_free, CRYPTO_EX_dup,
-CRYPTO_free_ex_index, CRYPTO_get_ex_new_index, CRYPTO_set_ex_data,
-CRYPTO_get_ex_data, CRYPTO_free_ex_data, CRYPTO_new_ex_data
+CRYPTO_free_ex_index, CRYPTO_get_ex_new_index,
+CRYPTO_alloc_ex_data, CRYPTO_set_ex_data, CRYPTO_get_ex_data,
+CRYPTO_free_ex_data, CRYPTO_new_ex_data
 - functions supporting application-specific data
 
 =head1 SYNOPSIS
@@ -26,6 +27,9 @@ CRYPTO_get_ex_data, CRYPTO_free_ex_data, CRYPTO_new_ex_data
 
  int CRYPTO_new_ex_data(int class_index, void *obj, CRYPTO_EX_DATA *ad)
 
+ int CRYPTO_alloc_ex_data(int class_index, void *obj, CRYPTO_EX_DATA *ad,
+                          int idx);
+
  int CRYPTO_set_ex_data(CRYPTO_EX_DATA *r, int idx, void *arg);
 
  void *CRYPTO_get_ex_data(CRYPTO_EX_DATA *r, int idx);
@@ -114,7 +118,8 @@ new_func() is called for every defined index. There is no requirement
 that the entire parent, or containing, structure has been set up.
 The new_func() is typically used only to allocate memory to store the
 exdata, and perhaps an "initialized" flag within that memory.
-The exdata value should be set by calling CRYPTO_set_ex_data().
+The exdata value may be allocated later on with CRYPTO_alloc_ex_data(),
+or may be set by calling CRYPTO_set_ex_data().
 
 When a structure is free'd (such as SSL_CTX_free()) then the
 free_func() is called for every defined index.  Again, the state of the
@@ -147,14 +152,18 @@ will fail.
 
 CRYPTO_get_ex_new_index() returns a new index or -1 on failure.
 
-CRYPTO_free_ex_index() and
-CRYPTO_set_ex_data() return 1 on success or 0 on failure.
+CRYPTO_free_ex_index(), CRYPTO_alloc_ex_data() and CRYPTO_set_ex_data()
+return 1 on success or 0 on failure. 
 
 CRYPTO_get_ex_data() returns the application data or NULL on failure;
 note that NULL may be a valid value.
 
 dup_func() should return 0 for failure and 1 for success.
 
+=head1 HISTORY
+
+CRYPTO_alloc_ex_data() was added in OpenSSL 3.0.0.
+
 =head1 COPYRIGHT
 
 Copyright 2015-2018 The OpenSSL Project Authors. All Rights Reserved.
diff --git a/include/openssl/crypto.h b/include/openssl/crypto.h
index cbde3d5..96ab9df 100644
--- a/include/openssl/crypto.h
+++ b/include/openssl/crypto.h
@@ -187,6 +187,10 @@ int CRYPTO_dup_ex_data(int class_index, CRYPTO_EX_DATA *to,
 
 void CRYPTO_free_ex_data(int class_index, void *obj, CRYPTO_EX_DATA *ad);
 
+/* Allocate a single item in the CRYPTO_EX_DATA variable */
+int CRYPTO_alloc_ex_data(int class_index, void *obj, CRYPTO_EX_DATA *ad,
+                         int idx);
+
 /*
  * Get/set data in a CRYPTO_EX_DATA variable corresponding to a particular
  * index (relative to the class type involved)
diff --git a/test/exdatatest.c b/test/exdatatest.c
index db4e0ff..3ce6d33 100644
--- a/test/exdatatest.c
+++ b/test/exdatatest.c
@@ -18,6 +18,7 @@ static long saved_argl;
 static void *saved_argp;
 static int saved_idx;
 static int saved_idx2;
+static int saved_idx3;
 static int gbl_result;
 
 /*
@@ -71,12 +72,13 @@ static void exnew2(void *parent, void *ptr, CRYPTO_EX_DATA *ad,
           int idx, long argl, void *argp)
 {
     MYOBJ_EX_DATA *ex_data = OPENSSL_zalloc(sizeof(*ex_data));
-    if (!TEST_int_eq(idx, saved_idx2)
+
+    if (!TEST_true(idx == saved_idx2 || idx == saved_idx3)
         || !TEST_long_eq(argl, saved_argl)
         || !TEST_ptr_eq(argp, saved_argp)
         || !TEST_ptr_null(ptr)
         || !TEST_ptr(ex_data)
-        || !TEST_true(CRYPTO_set_ex_data(ad, saved_idx2, ex_data))) {
+        || !TEST_true(CRYPTO_set_ex_data(ad, idx, ex_data))) {
         gbl_result = 0;
         OPENSSL_free(ex_data);
     } else {
@@ -88,13 +90,14 @@ static int exdup2(CRYPTO_EX_DATA *to, const CRYPTO_EX_DATA *from,
           void *from_d, int idx, long argl, void *argp)
 {
     MYOBJ_EX_DATA **update_ex_data = (MYOBJ_EX_DATA**)from_d;
-    MYOBJ_EX_DATA *ex_data = CRYPTO_get_ex_data(to, saved_idx2);
-    if (!TEST_int_eq(idx, saved_idx2)
+    MYOBJ_EX_DATA *ex_data = NULL;
+
+    if (!TEST_true(idx == saved_idx2 || idx == saved_idx3)
         || !TEST_long_eq(argl, saved_argl)
         || !TEST_ptr_eq(argp, saved_argp)
         || !TEST_ptr(from_d)
         || !TEST_ptr(*update_ex_data)
-        || !TEST_ptr(ex_data)
+        || !TEST_ptr(ex_data = CRYPTO_get_ex_data(to, idx))
         || !TEST_true(ex_data->new)) {
         gbl_result = 0;
     } else {
@@ -111,14 +114,14 @@ static int exdup2(CRYPTO_EX_DATA *to, const CRYPTO_EX_DATA *from,
 static void exfree2(void *parent, void *ptr, CRYPTO_EX_DATA *ad,
             int idx, long argl, void *argp)
 {
-    MYOBJ_EX_DATA *ex_data = CRYPTO_get_ex_data(ad, saved_idx2);
-    OPENSSL_free(ex_data);
-    if (!TEST_int_eq(idx, saved_idx2)
+    MYOBJ_EX_DATA *ex_data = CRYPTO_get_ex_data(ad, idx);
+
+    if (!TEST_true(idx == saved_idx2 || idx == saved_idx3)
         || !TEST_long_eq(argl, saved_argl)
         || !TEST_ptr_eq(argp, saved_argp)
-        || !TEST_ptr(ex_data)
-        || !TEST_true(CRYPTO_set_ex_data(ad, saved_idx2, NULL)))
+        || !TEST_true(CRYPTO_set_ex_data(ad, idx, NULL)))
         gbl_result = 0;
+    OPENSSL_free(ex_data);
 }
 
 typedef struct myobj_st {
@@ -152,6 +155,7 @@ static char *MYOBJ_gethello(MYOBJ *obj)
 static void MYOBJ_sethello2(MYOBJ *obj, char *cp)
 {
     MYOBJ_EX_DATA* ex_data = CRYPTO_get_ex_data(&obj->ex_data, saved_idx2);
+
     if (TEST_ptr(ex_data))
         ex_data->hello = cp;
     else
@@ -161,6 +165,31 @@ static void MYOBJ_sethello2(MYOBJ *obj, char *cp)
 static char *MYOBJ_gethello2(MYOBJ *obj)
 {
     MYOBJ_EX_DATA* ex_data = CRYPTO_get_ex_data(&obj->ex_data, saved_idx2);
+
+    if (TEST_ptr(ex_data))
+        return ex_data->hello;
+
+    obj->st = gbl_result = 0;
+    return NULL;
+}
+
+static void MYOBJ_allochello3(MYOBJ *obj, char *cp)
+{
+    MYOBJ_EX_DATA* ex_data = NULL;
+
+    if (TEST_ptr_null(ex_data = CRYPTO_get_ex_data(&obj->ex_data, saved_idx3))
+        && TEST_true(CRYPTO_alloc_ex_data(CRYPTO_EX_INDEX_APP, obj,
+                                          &obj->ex_data, saved_idx3))
+        && TEST_ptr(ex_data = CRYPTO_get_ex_data(&obj->ex_data, saved_idx3)))
+        ex_data->hello = cp;
+    else
+        obj->st = gbl_result = 0;
+}
+
+static char *MYOBJ_gethello3(MYOBJ *obj)
+{
+    MYOBJ_EX_DATA* ex_data = CRYPTO_get_ex_data(&obj->ex_data, saved_idx3);
+
     if (TEST_ptr(ex_data))
         return ex_data->hello;
 
@@ -207,7 +236,15 @@ static int test_exdata(void)
         return 0;
     if (!TEST_ptr(CRYPTO_get_ex_data(&t1->ex_data, saved_idx2)))
         return 0;
-    if (!TEST_ptr(CRYPTO_get_ex_data(&t2->ex_data, saved_idx2)))
+
+    /*
+     * saved_idx3 differs from other indexes by being created after the exdata
+     * was initialized.
+     */
+    saved_idx3 = CRYPTO_get_ex_new_index(CRYPTO_EX_INDEX_APP,
+                                         saved_argl, saved_argp,
+                                         exnew2, exdup2, exfree2);
+    if (!TEST_ptr_null(CRYPTO_get_ex_data(&t1->ex_data, saved_idx3)))
         return 0;
 
     MYOBJ_sethello(t1, p);
@@ -220,6 +257,11 @@ static int test_exdata(void)
     if (!TEST_ptr_eq(cp, p))
         return 0;
 
+    MYOBJ_allochello3(t1, p);
+    cp = MYOBJ_gethello3(t1);
+    if (!TEST_ptr_eq(cp, p))
+        return 0;
+
     cp = MYOBJ_gethello(t2);
     if (!TEST_ptr_null(cp))
         return 0;
@@ -246,6 +288,10 @@ static int test_exdata(void)
     if (!TEST_ptr_eq(cp, p))
         return 0;
 
+    cp = MYOBJ_gethello3(t3);
+    if (!TEST_ptr_eq(cp, p))
+        return 0;
+
     MYOBJ_free(t1);
     MYOBJ_free(t2);
     MYOBJ_free(t3);
diff --git a/util/libcrypto.num b/util/libcrypto.num
index b262bc7..991d875 100644
--- a/util/libcrypto.num
+++ b/util/libcrypto.num
@@ -4640,3 +4640,4 @@ EVP_KDF_ctrl_str                        4595	3_0_0	EXIST::FUNCTION:
 EVP_KDF_size                            4596	3_0_0	EXIST::FUNCTION:
 EVP_KDF_derive                          4597	3_0_0	EXIST::FUNCTION:
 EC_GROUP_get0_field                     4598	3_0_0	EXIST::FUNCTION:EC
+CRYPTO_alloc_ex_data                    4599	3_0_0	EXIST::FUNCTION: