elf: Issue la_symbind for bind-now (BZ #23734)

The audit symbind callback is not called for binaries built with
-Wl,-z,now or when LD_BIND_NOW=1 is used, nor the PLT tracking callbacks
(plt_enter and plt_exit) since this would change the expected
program semantics (where no PLT is expected) and would have performance
implications (such as for BZ#15533).

LAV_CURRENT is also bumped to indicate the audit ABI change (where
la_symbind flags are set by the loader to indicate no possible PLT
trace).

To handle powerpc64 ELFv1 function descriptor, _dl_audit_symbind
requires to know whether bind-now is used so the symbol value is
updated to function text segment instead of the OPD (for lazy binding
this is done by PPC64_LOAD_FUNCPTR on _dl_runtime_resolve).

Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu,
powerpc64-linux-gnu.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>

1 files changed, 114 insertions, 0 deletions

diff --git a/elf/tst-auditmod24a.c b/elf/tst-auditmod24a.c
new file mode 100644
index 0000000..d8e88f3
--- /dev/null
+++ b/elf/tst-auditmod24a.c
@@ -0,0 +1,114 @@
+/* Audit modules for tst-audit24a.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <link.h>
+#include <inttypes.h>
+#include <stdlib.h>
+#include <string.h>
+#include <tst-auditmod24.h>
+
+#define AUDIT24_COOKIE     0x1
+#define AUDIT24MOD1_COOKIE 0x2
+#define AUDIT24MOD2_COOKIE 0x3
+
+#ifndef TEST_NAME
+# define TEST_NAME "tst-audit24a"
+#endif
+#ifndef TEST_MOD
+# define TEST_MOD TEST_NAME
+#endif
+#ifndef TEST_FUNC
+# define TEST_FUNC "tst_audit24a"
+#endif
+
+unsigned int
+la_version (unsigned int version)
+{
+  return LAV_CURRENT;
+}
+
+unsigned int
+la_objopen (struct link_map *map, Lmid_t lmid, uintptr_t *cookie)
+{
+  const char *p = strrchr (map->l_name, '/');
+  const char *l_name = p == NULL ? TEST_NAME : p + 1;
+
+  uintptr_t ck = -1;
+  if (strcmp (l_name, TEST_MOD "mod1.so") == 0)
+    ck = AUDIT24MOD1_COOKIE;
+  else if (strcmp (l_name, TEST_MOD "mod2.so") == 0)
+    ck = AUDIT24MOD2_COOKIE;
+  else if (strcmp (l_name, TEST_NAME) == 0)
+    ck = AUDIT24_COOKIE;
+
+  *cookie = ck;
+  return ck == -1 ? 0 : LA_FLG_BINDFROM | LA_FLG_BINDTO;
+}
+
+static int
+tst_func1 (void)
+{
+  return 1;
+}
+
+static int
+tst_func2 (void)
+{
+  return 10;
+}
+
+#if __ELF_NATIVE_CLASS == 64
+uintptr_t
+la_symbind64 (Elf64_Sym *sym, unsigned int ndx,
+	      uintptr_t *refcook, uintptr_t *defcook,
+	      unsigned int *flags, const char *symname)
+#else
+uintptr_t
+la_symbind32 (Elf32_Sym *sym, unsigned int ndx,
+	      uintptr_t *refcook, uintptr_t *defcook,
+	      unsigned int *flags, const char *symname)
+#endif
+{
+  if (*refcook == AUDIT24_COOKIE)
+    {
+      if (*defcook == AUDIT24MOD1_COOKIE)
+	{
+	  /* Check if bind-now symbols are advertised to not call the PLT
+	     hooks.  */
+	  test_symbind_flags (*flags);
+
+	  if (strcmp (symname, TEST_FUNC "mod1_func1") == 0)
+	    return (uintptr_t) tst_func1;
+	  else if (strcmp (symname, TEST_FUNC "mod1_func2") == 0)
+	    return sym->st_value;
+	  abort ();
+	}
+      if (*defcook == AUDIT24MOD2_COOKIE
+	  && (strcmp (symname, TEST_FUNC "mod2_func1") == 0))
+	{
+	  test_symbind_flags (*flags);
+
+	  return (uintptr_t) tst_func2;
+	}
+
+      /* malloc functions.  */
+      return sym->st_value;
+    }
+
+  abort ();
+}