crypto: Make unloading of crypto safer

Facts:
crypto nif-lib registers callback functions that openssl uses
for memory management and thread synchronization. The callback
functions can only be set once, openssl does not allow changing the
callback functions.

Problem:
If openssl is dynamicly linked to crypto, you might get s scenario
where the crypto lib is unloaded while leaving openssl loaded
with its old pointers to the unloaded crypto code intact.
If crypto is then reloaded (by init:restart() for example), the crypto
nif-lib might get relocated at a different address. crypto calls
openssl which in turn calls the old invalid callback functions...kaboom.

Solution:
Break apart the callback functions into a separate dynamic lib that
crypto loads with dlopen. When crypto is unloaded the callback lib is
left in place to be reused if/when crypto is loaded again.

1 files changed, 2 insertions, 2 deletions

diff --git a/erts/emulator/beam/sys.h b/erts/emulator/beam/sys.h
index 0e6bec352e..743da4ca3a 100644
--- a/erts/emulator/beam/sys.h
+++ b/erts/emulator/beam/sys.h
@@ -618,7 +618,7 @@ typedef struct {
 #define ERTS_SYS_DDLL_ERROR_INIT {NULL}
 extern void erts_sys_ddll_free_error(ErtsSysDdllError*);
 extern void erl_sys_ddll_init(void); /* to initialize mutexes etc */
-extern int erts_sys_ddll_open2(char *path, void **handle, ErtsSysDdllError*);
+extern int erts_sys_ddll_open2(const char *path, void **handle, ErtsSysDdllError*);
 #define erts_sys_ddll_open(P,H) erts_sys_ddll_open2(P,H,NULL)
 extern int erts_sys_ddll_open_noext(char *path, void **handle, ErtsSysDdllError*);
 extern int erts_sys_ddll_load_driver_init(void *handle, void **function);
@@ -627,7 +627,7 @@ extern int erts_sys_ddll_close2(void *handle, ErtsSysDdllError*);
 #define erts_sys_ddll_close(H) erts_sys_ddll_close2(H,NULL)
 extern void *erts_sys_ddll_call_init(void *function);
 extern void *erts_sys_ddll_call_nif_init(void *function);
-extern int erts_sys_ddll_sym2(void *handle, char *name, void **function, ErtsSysDdllError*);
+extern int erts_sys_ddll_sym2(void *handle, const char *name, void **function, ErtsSysDdllError*);
 #define erts_sys_ddll_sym(H,N,F) erts_sys_ddll_sym2(H,N,F,NULL)
 extern char *erts_sys_ddll_error(int code);