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, 129 insertions, 0 deletions

diff --git a/elf/tst-audit25a.c b/elf/tst-audit25a.c
new file mode 100644
index 0000000000..49173e8625
--- /dev/null
+++ b/elf/tst-audit25a.c
@@ -0,0 +1,129 @@
+/* Check LD_AUDIT and LD_BIND_NOW.
+   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 <array_length.h>
+#include <errno.h>
+#include <getopt.h>
+#include <limits.h>
+#include <inttypes.h>
+#include <string.h>
+#include <stdlib.h>
+#include <support/capture_subprocess.h>
+#include <support/check.h>
+#include <support/xstdio.h>
+#include <support/support.h>
+#include <sys/auxv.h>
+
+static int restart;
+#define CMDLINE_OPTIONS \
+  { "restart", no_argument, &restart, 1 },
+
+void tst_audit25mod1_func1 (void);
+void tst_audit25mod1_func2 (void);
+void tst_audit25mod2_func1 (void);
+void tst_audit25mod2_func2 (void);
+
+static int
+handle_restart (void)
+{
+  tst_audit25mod1_func1 ();
+  tst_audit25mod1_func2 ();
+  tst_audit25mod2_func1 ();
+  tst_audit25mod2_func2 ();
+
+  return 0;
+}
+
+static inline bool
+startswith (const char *str, const char *pre)
+{
+  size_t lenpre = strlen (pre);
+  size_t lenstr = strlen (str);
+  return lenstr < lenpre ? false : memcmp (pre, str, lenpre) == 0;
+}
+
+static int
+do_test (int argc, char *argv[])
+{
+  /* We must have either:
+     - One or four parameters left if called initially:
+       + path to ld.so         optional
+       + "--library-path"      optional
+       + the library path      optional
+       + the application name  */
+
+  if (restart)
+    return handle_restart ();
+
+  setenv ("LD_AUDIT", "tst-auditmod25.so", 0);
+
+  char *spargv[9];
+  int i = 0;
+  for (; i < argc - 1; i++)
+    spargv[i] = argv[i + 1];
+  spargv[i++] = (char *) "--direct";
+  spargv[i++] = (char *) "--restart";
+  spargv[i] = NULL;
+  TEST_VERIFY_EXIT (i < array_length (spargv));
+
+  {
+    struct support_capture_subprocess result
+      = support_capture_subprogram (spargv[0], spargv);
+    support_capture_subprocess_check (&result, "tst-audit25a", 0,
+				      sc_allow_stderr);
+
+    /* tst-audit25a is build with -Wl,-z,lazy and tst-audit25mod1 with
+       -Wl,-z,now; so only tst_audit25mod3_func1 should be expected to
+       have LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT.  */
+    TEST_COMPARE_STRING (result.err.buffer,
+			 "la_symbind: tst_audit25mod3_func1 1\n"
+			 "la_symbind: tst_audit25mod1_func1 0\n"
+			 "la_symbind: tst_audit25mod1_func2 0\n"
+			 "la_symbind: tst_audit25mod2_func1 0\n"
+			 "la_symbind: tst_audit25mod4_func1 0\n"
+			 "la_symbind: tst_audit25mod2_func2 0\n");
+
+    support_capture_subprocess_free (&result);
+  }
+
+  {
+    setenv ("LD_BIND_NOW", "1", 0);
+    struct support_capture_subprocess result
+      = support_capture_subprogram (spargv[0], spargv);
+    support_capture_subprocess_check (&result, "tst-audit25a", 0,
+				      sc_allow_stderr);
+
+    /* With LD_BIND_NOW all symbols are expected to have
+       LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT.  Also the resolution
+       order is done in breadth-first order.  */
+    TEST_COMPARE_STRING (result.err.buffer,
+			 "la_symbind: tst_audit25mod4_func1 1\n"
+			 "la_symbind: tst_audit25mod3_func1 1\n"
+			 "la_symbind: tst_audit25mod1_func1 1\n"
+			 "la_symbind: tst_audit25mod2_func1 1\n"
+			 "la_symbind: tst_audit25mod1_func2 1\n"
+			 "la_symbind: tst_audit25mod2_func2 1\n");
+
+    support_capture_subprocess_free (&result);
+  }
+
+  return 0;
+}
+
+#define TEST_FUNCTION_ARGV do_test
+#include <support/test-driver.c>