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From: "Chang S. Bae" <chang.seok.bae@intel.com>
To: bp@suse.de, tglx@linutronix.de, mingo@kernel.org,
	luto@kernel.org, x86@kernel.org
Cc: len.brown@intel.com, dave.hansen@intel.com, hjl.tools@gmail.com,
	Dave.Martin@arm.com, jannh@google.com, mpe@ellerman.id.au,
	carlos@redhat.com, tony.luck@intel.com, ravi.v.shankar@intel.com,
	libc-alpha@sourceware.org, linux-arch@vger.kernel.org,
	linux-api@vger.kernel.org, linux-kernel@vger.kernel.org,
	chang.seok.bae@intel.com, linux-kselftest@vger.kernel.org
Subject: [PATCH v6 6/6] selftest/x86/signal: Include test cases for validating sigaltstack
Date: Sat, 27 Feb 2021 08:59:11 -0800	[thread overview]
Message-ID: <20210227165911.32757-7-chang.seok.bae@intel.com> (raw)
In-Reply-To: <20210227165911.32757-1-chang.seok.bae@intel.com>

The test measures the kernel's signal delivery with different (enough vs.
insufficient) stack sizes.

Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Reviewed-by: Len Brown <len.brown@intel.com>
Cc: x86@kernel.org
Cc: linux-kselftest@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
Changes from v3:
* Revised test messages again (Borislav Petkov)

Changes from v2:
* Revised test messages (Borislav Petkov)
---
 tools/testing/selftests/x86/Makefile      |   2 +-
 tools/testing/selftests/x86/sigaltstack.c | 128 ++++++++++++++++++++++
 2 files changed, 129 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/x86/sigaltstack.c

diff --git a/tools/testing/selftests/x86/Makefile b/tools/testing/selftests/x86/Makefile
index 333980375bc7..65bba2ae86ee 100644
--- a/tools/testing/selftests/x86/Makefile
+++ b/tools/testing/selftests/x86/Makefile
@@ -13,7 +13,7 @@ CAN_BUILD_WITH_NOPIE := $(shell ./check_cc.sh $(CC) trivial_program.c -no-pie)
 TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs syscall_nt test_mremap_vdso \
 			check_initial_reg_state sigreturn iopl ioperm \
 			test_vsyscall mov_ss_trap \
-			syscall_arg_fault fsgsbase_restore
+			syscall_arg_fault fsgsbase_restore sigaltstack
 TARGETS_C_32BIT_ONLY := entry_from_vm86 test_syscall_vdso unwind_vdso \
 			test_FCMOV test_FCOMI test_FISTTP \
 			vdso_restorer
diff --git a/tools/testing/selftests/x86/sigaltstack.c b/tools/testing/selftests/x86/sigaltstack.c
new file mode 100644
index 000000000000..f689af75e979
--- /dev/null
+++ b/tools/testing/selftests/x86/sigaltstack.c
@@ -0,0 +1,128 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#define _GNU_SOURCE
+#include <signal.h>
+#include <stdio.h>
+#include <stdbool.h>
+#include <string.h>
+#include <err.h>
+#include <errno.h>
+#include <limits.h>
+#include <sys/mman.h>
+#include <sys/auxv.h>
+#include <sys/prctl.h>
+#include <sys/resource.h>
+#include <setjmp.h>
+
+/* sigaltstack()-enforced minimum stack */
+#define ENFORCED_MINSIGSTKSZ	2048
+
+#ifndef AT_MINSIGSTKSZ
+#  define AT_MINSIGSTKSZ	51
+#endif
+
+static int nerrs;
+
+static bool sigalrm_expected;
+
+static unsigned long at_minstack_size;
+
+static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
+		       int flags)
+{
+	struct sigaction sa;
+
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_sigaction = handler;
+	sa.sa_flags = SA_SIGINFO | flags;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(sig, &sa, 0))
+		err(1, "sigaction");
+}
+
+static void clearhandler(int sig)
+{
+	struct sigaction sa;
+
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_handler = SIG_DFL;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(sig, &sa, 0))
+		err(1, "sigaction");
+}
+
+static int setup_altstack(void *start, unsigned long size)
+{
+	stack_t ss;
+
+	memset(&ss, 0, sizeof(ss));
+	ss.ss_size = size;
+	ss.ss_sp = start;
+
+	return sigaltstack(&ss, NULL);
+}
+
+static jmp_buf jmpbuf;
+
+static void sigsegv(int sig, siginfo_t *info, void *ctx_void)
+{
+	if (sigalrm_expected) {
+		printf("[FAIL]\tWrong signal delivered: SIGSEGV (expected SIGALRM).");
+		nerrs++;
+	} else {
+		printf("[OK]\tSIGSEGV signal delivered.\n");
+	}
+
+	siglongjmp(jmpbuf, 1);
+}
+
+static void sigalrm(int sig, siginfo_t *info, void *ctx_void)
+{
+	if (!sigalrm_expected) {
+		printf("[FAIL]\tWrong signal delivered: SIGALRM (expected SIGSEGV).");
+		nerrs++;
+	} else {
+		printf("[OK]\tSIGALRM signal delivered.\n");
+	}
+}
+
+static void test_sigaltstack(void *altstack, unsigned long size)
+{
+	if (setup_altstack(altstack, size))
+		err(1, "sigaltstack()");
+
+	sigalrm_expected = (size > at_minstack_size) ? true : false;
+
+	sethandler(SIGSEGV, sigsegv, 0);
+	sethandler(SIGALRM, sigalrm, SA_ONSTACK);
+
+	if (!sigsetjmp(jmpbuf, 1)) {
+		printf("[RUN]\tTest an alternate signal stack of %ssufficient size.\n",
+		       sigalrm_expected ? "" : "in");
+		printf("\tRaise SIGALRM. %s is expected to be delivered.\n",
+		       sigalrm_expected ? "It" : "SIGSEGV");
+		raise(SIGALRM);
+	}
+
+	clearhandler(SIGALRM);
+	clearhandler(SIGSEGV);
+}
+
+int main(void)
+{
+	void *altstack;
+
+	at_minstack_size = getauxval(AT_MINSIGSTKSZ);
+
+	altstack = mmap(NULL, at_minstack_size + SIGSTKSZ, PROT_READ | PROT_WRITE,
+			MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
+	if (altstack == MAP_FAILED)
+		err(1, "mmap()");
+
+	if ((ENFORCED_MINSIGSTKSZ + 1) < at_minstack_size)
+		test_sigaltstack(altstack, ENFORCED_MINSIGSTKSZ + 1);
+
+	test_sigaltstack(altstack, at_minstack_size + SIGSTKSZ);
+
+	return nerrs == 0 ? 0 : 1;
+}
-- 
2.17.1


      parent reply	other threads:[~2021-02-27 17:30 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-27 16:59 [PATCH v6 0/6] x86: Improve Minimum Alternate Stack Size Chang S. Bae
2021-02-27 16:59 ` [PATCH v6 1/6] uapi: Define the aux vector AT_MINSIGSTKSZ Chang S. Bae
2021-03-01 19:09   ` Borislav Petkov
2021-03-10 16:31     ` Bae, Chang Seok
2021-02-27 16:59 ` [PATCH v6 2/6] x86/signal: Introduce helpers to get the maximum signal frame size Chang S. Bae
2021-02-27 16:59 ` [PATCH v6 3/6] x86/elf: Support a new ELF aux vector AT_MINSIGSTKSZ Chang S. Bae
2021-03-05 10:43   ` Borislav Petkov
2021-03-10 16:34     ` Bae, Chang Seok
2021-03-10 17:43       ` Borislav Petkov
2021-03-10 18:01         ` Bae, Chang Seok
2021-02-27 16:59 ` [PATCH v6 4/6] selftest/sigaltstack: Use the AT_MINSIGSTKSZ aux vector if available Chang S. Bae
2021-02-27 16:59 ` [PATCH v6 5/6] x86/signal: Detect and prevent an alternate signal stack overflow Chang S. Bae
2021-02-27 16:59 ` Chang S. Bae [this message]

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