tools/testing/selftests/mm/memfd_secret.c

Source file repositories/reference/linux-study-clean/tools/testing/selftests/mm/memfd_secret.c

File Facts

System
Linux kernel
Corpus path
tools/testing/selftests/mm/memfd_secret.c
Extension
.c
Size
7064 bytes
Lines
347
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

WIFSIGNALED(status)) {
		pass("%s is blocked as expected\n", name);
		return;
	}

	fail("%s: unexpected memory access\n", name);
}

static void test_remote_access(int fd, const char *name,
			       void (*func)(int fd, int pipefd[2]))
{
	int pipefd[2];
	pid_t pid;
	char *mem;

	if (pipe(pipefd)) {
		fail("pipe failed: %s\n", strerror(errno));
		return;
	}

	pid = fork();
	if (pid < 0) {
		fail("fork failed: %s\n", strerror(errno));
		return;
	}

	if (pid == 0) {
		func(fd, pipefd);
		return;
	}

	mem = mmap(NULL, page_size, prot, mode, fd, 0);
	if (mem == MAP_FAILED) {
		fail("Unable to mmap secret memory\n");
		return;
	}

	memset(mem, PATTERN, page_size);

	if (write(pipefd[1], &mem, sizeof(mem)) < 0) {
		fail("pipe write: %s\n", strerror(errno));
		return;
	}

	check_child_status(pid, name);
}

static void test_process_vm_read(int fd)
{
	test_remote_access(fd, "process_vm_read", try_process_vm_read);
}

static void test_ptrace(int fd)
{
	test_remote_access(fd, "ptrace", try_ptrace);
}

static int set_cap_limits(rlim_t max)
{
	struct rlimit new;
	cap_t cap = cap_init();

	new.rlim_cur = max;
	new.rlim_max = max;
	if (setrlimit(RLIMIT_MEMLOCK, &new)) {
		perror("setrlimit() returns error");
		return -1;
	}

	/* drop capabilities including CAP_IPC_LOCK */
	if (cap_set_proc(cap)) {
		perror("cap_set_proc() returns error");
		return -2;
	}

	return 0;
}

static void prepare(void)
{
	struct rlimit rlim;

	page_size = sysconf(_SC_PAGE_SIZE);
	if (!page_size)
		ksft_exit_fail_msg("Failed to get page size %s\n",
				   strerror(errno));

	if (getrlimit(RLIMIT_MEMLOCK, &rlim))
		ksft_exit_fail_msg("Unable to detect mlock limit: %s\n",
				   strerror(errno));

Annotation

Implementation Notes