elf: execve statically linked programs instead of crashing [BZ #28648]

Programs without dynamic dependencies and without a program
interpreter are now run via execve.

Previously, the dynamic linker either crashed while attempting to
read a non-existing dynamic segment (looking for DT_AUDIT/DT_DEPAUDIT
data), or the self-relocated in the static PIE executable crashed
because the outer dynamic linker had already applied RELRO protection.

<dl-execve.h> is needed because execve is not available in the
dynamic loader on Hurd.

Reviewed-by: H.J. Lu <hjl.tools@gmail.com>

1 files changed, 62 insertions, 0 deletions

diff --git a/elf/tst-rtld-run-static.c b/elf/tst-rtld-run-static.c
new file mode 100644
index 0000000000..7281093504
--- /dev/null
+++ b/elf/tst-rtld-run-static.c
@@ -0,0 +1,62 @@
+/* Test running statically linked programs using ld.so.
+   Copyright (C) 2021 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 <support/check.h>
+#include <support/support.h>
+#include <support/capture_subprocess.h>
+#include <string.h>
+#include <stdlib.h>
+
+static int
+do_test (void)
+{
+  char *ldconfig_path = xasprintf ("%s/elf/ldconfig", support_objdir_root);
+
+  {
+    char *argv[] = { (char *) "ld.so", ldconfig_path, (char *) "--help", NULL };
+    struct support_capture_subprocess cap
+      = support_capture_subprogram (support_objdir_elf_ldso, argv);
+    support_capture_subprocess_check (&cap, "no --argv0", 0, sc_allow_stdout);
+    puts ("info: output without --argv0:");
+    puts (cap.out.buffer);
+    TEST_VERIFY (strstr (cap.out.buffer, "Usage: ldconfig [OPTION...]\n")
+                 == cap.out.buffer);
+    support_capture_subprocess_free (&cap);
+  }
+
+  {
+    char *argv[] =
+      {
+        (char *) "ld.so", (char *) "--argv0", (char *) "ldconfig-argv0",
+        ldconfig_path, (char *) "--help", NULL
+      };
+    struct support_capture_subprocess cap
+      = support_capture_subprogram (support_objdir_elf_ldso, argv);
+    support_capture_subprocess_check (&cap, "with --argv0", 0, sc_allow_stdout);
+    puts ("info: output with --argv0:");
+    puts (cap.out.buffer);
+    TEST_VERIFY (strstr (cap.out.buffer, "Usage: ldconfig-argv0 [OPTION...]\n")
+                 == cap.out.buffer);
+    support_capture_subprocess_free (&cap);
+  }
+
+  free (ldconfig_path);
+  return 0;
+}
+
+#include <support/test-driver.c>