[v3,5/5] aarch64: Add GCS test with signal handler
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redhat-pt-bot/TryBot-32bit |
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linaro-tcwg-bot/tcwg_glibc_build--master-aarch64 |
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linaro-tcwg-bot/tcwg_glibc_build--master-arm |
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linaro-tcwg-bot/tcwg_glibc_check--master-aarch64 |
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Commit Message
Test that when we return from a function that enabled GCS at runtime
we get SIGSEGV. Also test that ucontext contains GCS block with the
GCS pointer.
---
sysdeps/unix/sysv/linux/aarch64/Makefile | 5 +
.../sysv/linux/aarch64/tst-gcs-noreturn.c | 100 ++++++++++++++++++
2 files changed, 105 insertions(+)
create mode 100644 sysdeps/unix/sysv/linux/aarch64/tst-gcs-noreturn.c
@@ -15,6 +15,7 @@ gcs-tests-dynamic = \
tst-gcs-dlopen-override \
tst-gcs-enforced \
tst-gcs-enforced-abort \
+ tst-gcs-noreturn \
tst-gcs-optional-off \
tst-gcs-optional-on \
tst-gcs-override \
@@ -123,6 +124,10 @@ $(objpfx)tst-gcs-dlopen-optional-on.out: $(objpfx)tst-gcs-mod2.so
$(objpfx)tst-gcs-dlopen-optional-off.out: $(objpfx)tst-gcs-mod2.so
$(objpfx)tst-gcs-dlopen-override.out: $(objpfx)tst-gcs-mod2.so
+LDFLAGS-tst-gcs-noreturn = -Wl,-z gcs=always
+
+tst-gcs-noreturn-ENV = GLIBC_TUNABLES=glibc.cpu.aarch64_gcs=0
+
endif # ifeq ($(have-test-cc-gcs),yes)
endif # ifeq ($(subdir),misc)
new file mode 100644
@@ -0,0 +1,100 @@
+/* AArch64 test for GCS abort when returning to non-GCS address.
+ Copyright (C) 2025 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 "tst-gcs-helper.h"
+
+#include <sys/prctl.h>
+#include <signal.h>
+#include <stdlib.h>
+
+# ifndef PR_SET_SHADOW_STACK_STATUS
+# define PR_SET_SHADOW_STACK_STATUS 75
+# define PR_SHADOW_STACK_ENABLE (1UL << 0)
+# endif
+
+static void
+run_with_gcs (void)
+{
+ int r = prctl(PR_SET_SHADOW_STACK_STATUS, PR_SHADOW_STACK_ENABLE, 0, 0, 0);
+ /* Syscall should succeed. */
+ TEST_VERIFY (r == 0);
+ bool gcs_enabled = __check_gcs_status ();
+ /* Now GCS should be enabled. */
+ TEST_VERIFY (gcs_enabled);
+ printf ("GCS is %s\n", gcs_enabled ? "enabled" : "disabled");
+}
+
+static struct _aarch64_ctx *
+extension (void *p)
+{
+ return p;
+}
+
+#ifndef GCS_MAGIC
+#define GCS_MAGIC 0x47435300
+#endif
+
+static void
+handler (int sig, siginfo_t *si, void *ctx)
+{
+ TEST_VERIFY (sig == SIGSEGV);
+ ucontext_t *uc = ctx;
+ void *p = uc->uc_mcontext.__reserved;
+ if (extension (p)->magic == FPSIMD_MAGIC)
+ p = (char *)p + extension (p)->size;
+ if (extension (p)->magic == GCS_MAGIC)
+ {
+ struct { uint64_t x, gcspr, y, z; } *q = p;
+ printf ("GCS pointer: %016lx\n", q->gcspr);
+ exit (0);
+ }
+ else
+ exit (3);
+}
+
+static int
+do_test (void)
+{
+ /* Check if GCS could possible by enabled. */
+ if (!(getauxval (AT_HWCAP) & HWCAP_GCS))
+ {
+ puts ("kernel or CPU does not support GCS");
+ return EXIT_UNSUPPORTED;
+ }
+ bool gcs_enabled = __check_gcs_status ();
+ /* This test should be rung with GCS initially disabled. */
+ TEST_VERIFY (!gcs_enabled);
+
+ /* We can't use EXPECTED_SIGNAL because of cases when
+ this test runs on a system that does not support GCS
+ which is being detected at runtime. */
+ struct sigaction sigact;
+ sigemptyset (&sigact.sa_mask);
+ sigact.sa_flags = 0;
+ sigact.sa_flags = sigact.sa_flags | SA_SIGINFO;
+ sigact.sa_sigaction = handler;
+ sigaction (SIGSEGV, &sigact, NULL);
+
+ run_with_gcs ();
+ /* If we reached this point, then something went wrong.
+ Returning from a function that enabled GCS should result in
+ SIGSEGV that we catch with the handler set up above. */
+ return 2;
+}
+
+#include <support/test-driver.c>