elf/rtld: Count skipped environment variables for enable_secure

When using the glibc.rtld.enable_secure tunable we need to keep track of
the count of environment variables we skip due to __libc_enable_secure
being set and adjust the auxv section of the stack.  This fixes an
assertion when running ld.so directly with glibc.rtld.enable_secure set.
Add a testcase that ensures the assert is not hit.

elf/rtld.c:1324   assert (auxv == sp + 1);

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

1 files changed, 33 insertions, 0 deletions

diff --git a/elf/tst-tunables-enable_secure-env.c b/elf/tst-tunables-enable_secure-env.c
new file mode 100644
index 0000000000..24e846f299
--- /dev/null
+++ b/elf/tst-tunables-enable_secure-env.c
@@ -0,0 +1,33 @@
+/* Check enable_secure tunable handles removed ENV variables without
+   assertions.
+   Copyright (C) 2024 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/capture_subprocess.h>
+#include <support/check.h>
+
+static int
+do_test (int argc, char *argv[])
+{
+  /* Ensure that no assertions are hit when a dynamically linked application
+     runs.  This test requires that GLIBC_TUNABLES=glibc.rtld.enable_secure=1
+     is set. */
+  return 0;
+}
+
+#define TEST_FUNCTION_ARGV do_test
+#include <support/test-driver.c>