property: lock the lib ctx when updating the property definition cache

Although the store being used is adequately and properly locked, the library
context is not.  Due to the mechanisms used for fetching, it is possible for
multiple stores to live within the same library context for short periods.
This fix prevents threading issues resulting from such coincidences.

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/14773)

3 files changed, 33 insertions, 5 deletions

diff --git a/crypto/context.c b/crypto/context.c
index 852f9dd7ce..6c088e6628 100644
--- a/crypto/context.c
+++ b/crypto/context.c
@@ -11,6 +11,7 @@
 #include <openssl/conf.h>
 #include "internal/thread_once.h"
 #include "internal/property.h"
+#include "internal/core.h"
 
 struct ossl_lib_ctx_onfree_list_st {
     ossl_lib_ctx_onfree_fn *fn;
@@ -39,6 +40,21 @@ struct ossl_lib_ctx_st {
     struct ossl_lib_ctx_onfree_list_st *onfreelist;
 };
 
+int ossl_lib_ctx_write_lock(OSSL_LIB_CTX *ctx)
+{
+    return CRYPTO_THREAD_write_lock(ossl_lib_ctx_get_concrete(ctx)->lock);
+}
+
+int ossl_lib_ctx_read_lock(OSSL_LIB_CTX *ctx)
+{
+    return CRYPTO_THREAD_read_lock(ossl_lib_ctx_get_concrete(ctx)->lock);
+}
+
+int ossl_lib_ctx_unlock(OSSL_LIB_CTX *ctx)
+{
+    return CRYPTO_THREAD_unlock(ossl_lib_ctx_get_concrete(ctx)->lock);
+}
+
 static int context_init(OSSL_LIB_CTX *ctx)
 {
     size_t i;
diff --git a/crypto/property/defn_cache.c b/crypto/property/defn_cache.c
index b3aefe8f8e..13b2d60770 100644
--- a/crypto/property/defn_cache.c
+++ b/crypto/property/defn_cache.c
@@ -13,6 +13,7 @@
 #include <openssl/lhash.h>
 #include "internal/propertyerr.h"
 #include "internal/property.h"
+#include "internal/core.h"
 #include "property_local.h"
 
 /*
@@ -74,11 +75,12 @@ OSSL_PROPERTY_LIST *ossl_prop_defn_get(OSSL_LIB_CTX *ctx, const char *prop)
     property_defns = ossl_lib_ctx_get_data(ctx,
                                            OSSL_LIB_CTX_PROPERTY_DEFN_INDEX,
                                            &property_defns_method);
-    if (property_defns == NULL)
+    if (property_defns == NULL || !ossl_lib_ctx_read_lock(ctx))
         return NULL;
 
     elem.prop = prop;
     r = lh_PROPERTY_DEFN_ELEM_retrieve(property_defns, &elem);
+    ossl_lib_ctx_unlock(ctx);
     return r != NULL ? r->defn : NULL;
 }
 
@@ -88,6 +90,7 @@ int ossl_prop_defn_set(OSSL_LIB_CTX *ctx, const char *prop,
     PROPERTY_DEFN_ELEM elem, *old, *p = NULL;
     size_t len;
     LHASH_OF(PROPERTY_DEFN_ELEM) *property_defns;
+    int res = 1;
 
     property_defns = ossl_lib_ctx_get_data(ctx,
                                            OSSL_LIB_CTX_PROPERTY_DEFN_INDEX,
@@ -98,10 +101,12 @@ int ossl_prop_defn_set(OSSL_LIB_CTX *ctx, const char *prop,
     if (prop == NULL)
         return 1;
 
+    if (!ossl_lib_ctx_write_lock(ctx))
+        return 0;
     if (pl == NULL) {
         elem.prop = prop;
         lh_PROPERTY_DEFN_ELEM_delete(property_defns, &elem);
-        return 1;
+        goto end;
     }
     len = strlen(prop);
     p = OPENSSL_malloc(sizeof(*p) + len);
@@ -112,11 +117,14 @@ int ossl_prop_defn_set(OSSL_LIB_CTX *ctx, const char *prop,
         old = lh_PROPERTY_DEFN_ELEM_insert(property_defns, p);
         if (old != NULL) {
             property_defn_free(old);
-            return 1;
+            goto end;
         }
         if (!lh_PROPERTY_DEFN_ELEM_error(property_defns))
-            return 1;
+            goto end;
     }
     OPENSSL_free(p);
-    return 0;
+    res = 0;
+ end:
+    ossl_lib_ctx_unlock(ctx);
+    return res;
 }
diff --git a/include/internal/core.h b/include/internal/core.h
index c3c2b74a63..6e66bbeb9a 100644
--- a/include/internal/core.h
+++ b/include/internal/core.h
@@ -60,4 +60,8 @@ void ossl_algorithm_do_all(OSSL_LIB_CTX *libctx, int operation_id,
                                        int no_store, void *data, int *result),
                            void *data);
 
+__owur int ossl_lib_ctx_write_lock(OSSL_LIB_CTX *ctx);
+__owur int ossl_lib_ctx_read_lock(OSSL_LIB_CTX *ctx);
+int ossl_lib_ctx_unlock(OSSL_LIB_CTX *ctx);
+
 #endif