[PATCH v4 7/7] selftests: test uaccess logging

[Peter Collingbourne]

Add a kselftest for the uaccess logging feature.

Link: https://linux-review.googlesource.com/id/I39e1707fb8aef53747c42bd55b46ecaa67205199
Signed-off-by: Peter Collingbourne <pcc@xxxxxxxxxx>
---
 tools/testing/selftests/Makefile              |   1 +
 .../testing/selftests/uaccess_buffer/Makefile |   4 +
 .../uaccess_buffer/uaccess_buffer_test.c      | 126 ++++++++++++++++++
 3 files changed, 131 insertions(+)
 create mode 100644 tools/testing/selftests/uaccess_buffer/Makefile
 create mode 100644 tools/testing/selftests/uaccess_buffer/uaccess_buffer_test.c

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index c852eb40c4f7..291b62430557 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -71,6 +71,7 @@ TARGETS += timers
 endif
 TARGETS += tmpfs
 TARGETS += tpm2
+TARGETS += uaccess_buffer
 TARGETS += user
 TARGETS += vDSO
 TARGETS += vm
diff --git a/tools/testing/selftests/uaccess_buffer/Makefile b/tools/testing/selftests/uaccess_buffer/Makefile
new file mode 100644
index 000000000000..e6e5fb43ce29
--- /dev/null
+++ b/tools/testing/selftests/uaccess_buffer/Makefile
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
+TEST_GEN_PROGS := uaccess_buffer_test
+
+include ../lib.mk
diff --git a/tools/testing/selftests/uaccess_buffer/uaccess_buffer_test.c b/tools/testing/selftests/uaccess_buffer/uaccess_buffer_test.c
new file mode 100644
index 000000000000..051062e4fbf9
--- /dev/null
+++ b/tools/testing/selftests/uaccess_buffer/uaccess_buffer_test.c
@@ -0,0 +1,126 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "../kselftest_harness.h"
+
+#include <linux/uaccess-buffer.h>
+#include <sys/prctl.h>
+#include <sys/utsname.h>
+
+FIXTURE(uaccess_buffer)
+{
+	uint64_t addr;
+};
+
+FIXTURE_SETUP(uaccess_buffer)
+{
+	ASSERT_EQ(0, prctl(PR_SET_UACCESS_DESCRIPTOR_ADDR_ADDR, &self->addr, 0,
+			   0, 0));
+}
+
+FIXTURE_TEARDOWN(uaccess_buffer)
+{
+	ASSERT_EQ(0, prctl(PR_SET_UACCESS_DESCRIPTOR_ADDR_ADDR, 0, 0, 0, 0));
+}
+
+TEST_F(uaccess_buffer, uname)
+{
+	struct uaccess_descriptor desc;
+	struct uaccess_buffer_entry entries[64];
+	struct utsname un;
+
+	desc.addr = (uint64_t)(unsigned long)entries;
+	desc.size = 64;
+	self->addr = (uint64_t)(unsigned long)&desc;
+	ASSERT_EQ(0, uname(&un));
+	ASSERT_EQ(0, self->addr);
+
+	if (desc.size == 63) {
+		ASSERT_EQ((uint64_t)(unsigned long)(entries + 1), desc.addr);
+
+		ASSERT_EQ((uint64_t)(unsigned long)&un, entries[0].addr);
+		ASSERT_EQ(sizeof(struct utsname), entries[0].size);
+		ASSERT_EQ(UACCESS_BUFFER_FLAG_WRITE, entries[0].flags);
+	} else {
+		/* See override_architecture in kernel/sys.c */
+		ASSERT_EQ(62, desc.size);
+		ASSERT_EQ((uint64_t)(unsigned long)(entries + 2), desc.addr);
+
+		ASSERT_EQ((uint64_t)(unsigned long)&un, entries[0].addr);
+		ASSERT_EQ(sizeof(struct utsname), entries[0].size);
+		ASSERT_EQ(UACCESS_BUFFER_FLAG_WRITE, entries[0].flags);
+
+		ASSERT_EQ((uint64_t)(unsigned long)&un.machine,
+			  entries[1].addr);
+		ASSERT_EQ(UACCESS_BUFFER_FLAG_WRITE, entries[1].flags);
+	}
+}
+
+static bool handled;
+
+static void usr1_handler(int signo)
+{
+	handled = true;
+}
+
+TEST_F(uaccess_buffer, blocked_signals)
+{
+	struct uaccess_descriptor desc;
+	struct shared_buf {
+		bool ready;
+		bool killed;
+	} volatile *shared = mmap(NULL, getpagesize(), PROT_READ | PROT_WRITE,
+				  MAP_ANON | MAP_SHARED, -1, 0);
+	struct sigaction act = {}, oldact;
+	int pid;
+
+	handled = false;
+	act.sa_handler = usr1_handler;
+	sigaction(SIGUSR1, &act, &oldact);
+
+	pid = fork();
+	if (pid == 0) {
+		/*
+		 * Busy loop to synchronize instead of issuing syscalls because
+		 * we need to test the behavior in the case where no syscall is
+		 * issued by the parent process.
+		 */
+		while (!shared->ready)
+			;
+		kill(getppid(), SIGUSR1);
+		shared->killed = true;
+		_exit(0);
+	} else {
+		int i;
+
+		desc.addr = 0;
+		desc.size = 0;
+		self->addr = (uint64_t)(unsigned long)&desc;
+
+		shared->ready = true;
+		while (!shared->killed)
+			;
+
+		/*
+		 * The kernel should have IPI'd us by now, but let's wait a bit
+		 * longer just in case.
+		 */
+		for (i = 0; i != 1000000; ++i)
+			;
+
+		ASSERT_FALSE(handled);
+
+		/*
+		 * Returning from the waitpid syscall should trigger the signal
+		 * handler. The signal itself may also interrupt waitpid, so
+		 * make sure to handle EINTR.
+		 */
+		while (waitpid(pid, NULL, 0) == -1)
+			ASSERT_EQ(EINTR, errno);
+		ASSERT_TRUE(handled);
+	}
+
+	munmap((void *)shared, getpagesize());
+	sigaction(SIGUSR1, &oldact, NULL);
+}
+
+TEST_HARNESS_MAIN
-- 
2.34.1.173.g76aa8bc2d0-goog