Add mseal01 test

This is a smoke test that verifies if mseal() protects specific VMA
portions of a process. According to documentation, the syscall should
protect memory from the following actions:

- unmapping, moving to another location, and shrinking the size, via
  munmap() and mremap()
- moving or expanding a different VMA into the current location, via
  mremap()
- modifying a VMA via mmap(MAP_FIXED)
- mprotect() and pkey_mprotect()
- destructive madvice() behaviors (e.g. MADV_DONTNEED) for anonymous
  memory, when users don’t have write permission to the memory

Any of the described actions is recognized via EPERM errno.

Reviewed-by: Cyril Hrubis <[email protected]>
Signed-off-by: Andrea Cervesato <[email protected]>

runtest/syscalls

@@ -881,6 +881,8 @@ mremap04 mremap04
 mremap05 mremap05
 mremap06 mremap06
 
+mseal01 mseal01
+
 msgctl01 msgctl01
 msgctl02 msgctl02
 msgctl03 msgctl03

testcases/kernel/syscalls/mseal/.gitignore

@@ -0,0 +1 @@
+mseal01

testcases/kernel/syscalls/mseal/Makefile

@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Copyright (C) 2023 SUSE LLC Andrea Cervesato <[email protected]>
+
+top_srcdir		?= ../../../..
+
+include $(top_srcdir)/include/mk/testcases.mk
+include $(top_srcdir)/include/mk/generic_leaf_target.mk

testcases/kernel/syscalls/mseal/mseal01.c

@@ -0,0 +1,156 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2024 SUSE LLC Andrea Cervesato <[email protected]>
+ */
+
+/*\
+ * [Description]
+ *
+ * This is a smoke test that verifies if mseal() protects specific VMA portions
+ * of a process. According to documentation, the syscall should protect memory
+ * from the following actions:
+ *
+ * - unmapping, moving to another location, and shrinking the size, via munmap()
+ *   and mremap()
+ * - moving or expanding a different VMA into the current location, via mremap()
+ * - modifying a VMA via mmap(MAP_FIXED)
+ * - mprotect() and pkey_mprotect()
+ * - destructive madvice() behaviors (e.g. MADV_DONTNEED) for anonymous memory,
+ *   when users don’t have write permission to the memory
+ *
+ * Any of the described actions is recognized via EPERM errno.
+ */
+
+#define _GNU_SOURCE
+
+#include "tst_test.h"
+#include "lapi/syscalls.h"
+
+#define MEMPAGES 8
+#define MEMSEAL 2
+
+static void *mem_addr;
+static int mem_size;
+static int mem_offset;
+static int mem_alignment;
+
+static inline int sys_mseal(void *start, size_t len)
+{
+	return tst_syscall(__NR_mseal, start, len, 0);
+}
+
+static void test_mprotect(void)
+{
+	TST_EXP_FAIL(mprotect(mem_addr, mem_size, PROT_NONE), EPERM);
+}
+
+static void test_pkey_mprotect(void)
+{
+	int ret;
+	int pkey;
+
+	pkey = tst_syscall(__NR_pkey_alloc, 0, 0);
+	if (pkey == -1) {
+		if (errno == EINVAL)
+			tst_brk(TCONF, "pku is not supported on this CPU");
+
+		tst_brk(TBROK | TERRNO, "pkey_alloc() error");
+	}
+
+	TST_EXP_FAIL(tst_syscall(__NR_pkey_mprotect,
+		mem_addr, mem_size,
+		PROT_NONE,
+		pkey),
+		EPERM);
+
+	ret = tst_syscall(__NR_pkey_free, pkey);
+	if (ret == -1)
+		tst_brk(TBROK | TERRNO, "pkey_free() error");
+}
+
+static void test_madvise(void)
+{
+	TST_EXP_FAIL(madvise(mem_addr, mem_size, MADV_DONTNEED), EPERM);
+}
+
+static void test_munmap(void)
+{
+	TST_EXP_FAIL(munmap(mem_addr, mem_size), EPERM);
+}
+
+static void test_mremap_resize(void)
+{
+	void *new_addr;
+	size_t new_size = 2 * mem_alignment;
+
+	new_addr = SAFE_MMAP(NULL, mem_size,
+		PROT_READ,
+		MAP_ANONYMOUS | MAP_PRIVATE,
+		-1, 0);
+
+	TST_EXP_FAIL_PTR_VOID(mremap(mem_addr, mem_size, new_size,
+		MREMAP_MAYMOVE | MREMAP_FIXED,
+		new_addr),
+		EPERM);
+
+	SAFE_MUNMAP(new_addr, new_size);
+}
+
+static void test_mmap_change_prot(void)
+{
+	TST_EXP_FAIL_PTR_VOID(mmap(mem_addr, mem_size,
+		PROT_READ,
+		MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED,
+		-1, 0), EPERM);
+}
+
+static struct tcase {
+	void (*func_test)(void);
+	int prot;
+	char *message;
+} tcases[] = {
+	{test_mprotect, PROT_READ | PROT_WRITE, "mprotect() availability"},
+	{test_pkey_mprotect, PROT_READ | PROT_WRITE, "pkey_mprotect() availability"},
+	{test_madvise, PROT_READ, "madvise() availability"},
+	{test_munmap, PROT_READ | PROT_WRITE, "munmap() availability from child"},
+	{test_mremap_resize, PROT_READ | PROT_WRITE, "mremap() address move/resize"},
+	{test_mmap_change_prot, PROT_READ | PROT_WRITE, "mmap() protection change"},
+};
+
+static void run(unsigned int n)
+{
+	/* the reason why we spawn a child is that mseal() will
+	 * protect VMA until process will call _exit()
+	 */
+	if (!SAFE_FORK()) {
+		struct tcase *tc = &tcases[n];
+
+		mem_addr = SAFE_MMAP(NULL, mem_size,
+			tc->prot,
+			MAP_ANONYMOUS | MAP_PRIVATE,
+			-1, 0);
+
+		tst_res(TINFO, "Testing %s", tc->message);
+
+		TST_EXP_PASS(sys_mseal(mem_addr + mem_offset, mem_alignment));
+
+		tc->func_test();
+		_exit(0);
+	}
+}
+
+static void setup(void)
+{
+	mem_alignment = getpagesize();
+	mem_size = mem_alignment * MEMPAGES;
+	mem_offset = mem_alignment * MEMSEAL;
+}
+
+static struct tst_test test = {
+	.test = run,
+	.tcnt = ARRAY_SIZE(tcases),
+	.setup = setup,
+	.min_kver = "6.10",
+	.forks_child = 1,
+};
+