Attachment 13661 Details for Bug 18684 – 1-line patch plus comments originally written by Carlos O'Donell

[patch] 1-line patch plus comments originally written by Carlos O'Donell

18684-RTLD_GLOBAL.patch (text/plain), 2.68 KB, created by Eric Wheeler on 2021-09-10 23:28:37 UTC

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Creator: Eric Wheeler

Created: 2021-09-10 23:28:37 UTC

Size: 2.68 KB

patch

obsolete

>diff --git a/dlfcn/dlmopen.c b/dlfcn/dlmopen.c
>index 38dca7a..ba468d2 100644
>--- a/dlfcn/dlmopen.c
>+++ b/dlfcn/dlmopen.c
>@@ -61,11 +61,6 @@ dlmopen_doit (void *a)
>       if (args->file == NULL)
> # endif
> 	GLRO(dl_signal_error) (EINVAL, NULL, NULL, N_("invalid namespace"));
>-
>-      /* It makes no sense to use RTLD_GLOBAL when loading a DSO into
>-	 a namespace other than the base namespace.  */
>-      if (__glibc_unlikely (args->mode & RTLD_GLOBAL))
>-	GLRO(dl_signal_error) (EINVAL, NULL, NULL, N_("invalid mode"));
>     }
> 
>   args->new = GLRO(dl_open) (args->file ?: "", args->mode | __RTLD_DLOPEN,
>diff --git a/elf/dl-open.c b/elf/dl-open.c
>index 027c1e0..175ef16 100644
>--- a/elf/dl-open.c
>+++ b/elf/dl-open.c
>@@ -72,6 +72,31 @@ add_to_global (struct link_map *new)
>     if (new->l_searchlist.r_list[cnt]->l_global == 0)
>       ++to_add;
> 
>+  struct link_namespaces *ns = &GL(dl_ns)[new->l_ns];
>+
>+  if (__glibc_unlikely (new->l_ns != LM_ID_BASE
>+			&& ns->_ns_main_searchlist == NULL))
>+    {
>+      /* An initial object was loaded with dlmopen into a distinct namespace
>+	 that has no global searchlist (RTLD_GLOBAL) and RTLD_GLOBAL was used.
>+	 Or that object then dlopened another object into the global
>+	 searchlist.  We find ourselves with no global searchlist initialized.
>+	 We have two choices, either we forbid this scenario and return an
>+	 error or treat the first RTLD_GLOBAL DSOs searchlist as the global
>+	 searchlist of the namespace.  We do the latter since it's the most
>+	 sensible course of action since you may dlmopen other libraries which
>+	 have no idea they have been isolated.  Thus RTLD_GLOBAL dlopen calls
>+	 within the new namespace are restricted to the new namespace and may
>+	 reference the symbols of the initial RTLD_GLOBAL dlmopen'd
>+	 libraries.  */
>+      ns->_ns_main_searchlist = &new->l_searchlist;
>+      /* Treat this list like it is read-only.  A value of zero forces a copy
>+	 later if we need to extend this list.  The list itself is already
>+	 being used as the primary scope for the first loaded RTLD_GLOBAL
>+	 object into the new namespace, thus we don't want to free it.  */
>+      ns->_ns_global_scope_alloc = 0;
>+    }
>+
>   /* The symbols of the new objects and its dependencies are to be
>      introduced into the global scope that will be used to resolve
>      references from other dynamically-loaded objects.
>@@ -86,7 +111,6 @@ add_to_global (struct link_map *new)
>      in an realloc() call.  Therefore we allocate a completely new
>      array the first time we have to add something to the locale scope.  */
> 
>-  struct link_namespaces *ns = &GL(dl_ns)[new->l_ns];
>   if (ns->_ns_global_scope_alloc == 0)
>     {
>       /* This is the first dynamic object given global scope.  */

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Attachments on bug 18684: 13661