selftests/exec: add file type errno tests

Make sure execve() returns the expected errno values for non-regular
files.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Marc Zyngier <maz@kernel.org>
Link: http://lkml.kernel.org/r/20200813231723.2725102-3-keescook@chromium.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

tools/testing/selftests/exec/.gitignore

@@ -10,3 +10,4 @@ execveat.denatured
 /recursion-depth
 xxxxxxxx*
 pipe
+S_I*.test

tools/testing/selftests/exec/Makefile

@@ -3,15 +3,16 @@ CFLAGS = -Wall
 CFLAGS += -Wno-nonnull
 CFLAGS += -D_GNU_SOURCE
 
-TEST_PROGS := binfmt_script
+TEST_PROGS := binfmt_script non-regular
 TEST_GEN_PROGS := execveat
 TEST_GEN_FILES := execveat.symlink execveat.denatured script subdir pipe
 # Makefile is a run-time dependency, since it's accessed by the execveat test
 TEST_FILES := Makefile
 
 TEST_GEN_PROGS += recursion-depth
 
-EXTRA_CLEAN := $(OUTPUT)/subdir.moved $(OUTPUT)/execveat.moved $(OUTPUT)/xxxxx*
+EXTRA_CLEAN := $(OUTPUT)/subdir.moved $(OUTPUT)/execveat.moved $(OUTPUT)/xxxxx*	\
+	       $(OUTPUT)/S_I*.test
 
 include ../lib.mk
 

tools/testing/selftests/exec/non-regular.c

@@ -0,0 +1,196 @@
+// SPDX-License-Identifier: GPL-2.0+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/sysmacros.h>
+#include <sys/types.h>
+
+#include "../kselftest_harness.h"
+
+/* Remove a file, ignoring the result if it didn't exist. */
+void rm(struct __test_metadata *_metadata, const char *pathname,
+	int is_dir)
+{
+	int rc;
+
+	if (is_dir)
+		rc = rmdir(pathname);
+	else
+		rc = unlink(pathname);
+
+	if (rc < 0) {
+		ASSERT_EQ(errno, ENOENT) {
+			TH_LOG("Not ENOENT: %s", pathname);
+		}
+	} else {
+		ASSERT_EQ(rc, 0) {
+			TH_LOG("Failed to remove: %s", pathname);
+		}
+	}
+}
+
+FIXTURE(file) {
+	char *pathname;
+	int is_dir;
+};
+
+FIXTURE_VARIANT(file)
+{
+	const char *name;
+	int expected;
+	int is_dir;
+	void (*setup)(struct __test_metadata *_metadata,
+		      FIXTURE_DATA(file) *self,
+		      const FIXTURE_VARIANT(file) *variant);
+	int major, minor, mode; /* for mknod() */
+};
+
+void setup_link(struct __test_metadata *_metadata,
+		FIXTURE_DATA(file) *self,
+		const FIXTURE_VARIANT(file) *variant)
+{
+	const char * const paths[] = {
+		"/bin/true",
+		"/usr/bin/true",
+	};
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(paths); i++) {
+		if (access(paths[i], X_OK) == 0) {
+			ASSERT_EQ(symlink(paths[i], self->pathname), 0);
+			return;
+		}
+	}
+	ASSERT_EQ(1, 0) {
+		TH_LOG("Could not find viable 'true' binary");
+	}
+}
+
+FIXTURE_VARIANT_ADD(file, S_IFLNK)
+{
+	.name = "S_IFLNK",
+	.expected = ELOOP,
+	.setup = setup_link,
+};
+
+void setup_dir(struct __test_metadata *_metadata,
+	       FIXTURE_DATA(file) *self,
+	       const FIXTURE_VARIANT(file) *variant)
+{
+	ASSERT_EQ(mkdir(self->pathname, 0755), 0);
+}
+
+FIXTURE_VARIANT_ADD(file, S_IFDIR)
+{
+	.name = "S_IFDIR",
+	.is_dir = 1,
+	.expected = EACCES,
+	.setup = setup_dir,
+};
+
+void setup_node(struct __test_metadata *_metadata,
+		FIXTURE_DATA(file) *self,
+		const FIXTURE_VARIANT(file) *variant)
+{
+	dev_t dev;
+	int rc;
+
+	dev = makedev(variant->major, variant->minor);
+	rc = mknod(self->pathname, 0755 | variant->mode, dev);
+	ASSERT_EQ(rc, 0) {
+		if (errno == EPERM)
+			SKIP(return, "Please run as root; cannot mknod(%s)",
+				variant->name);
+	}
+}
+
+FIXTURE_VARIANT_ADD(file, S_IFBLK)
+{
+	.name = "S_IFBLK",
+	.expected = EACCES,
+	.setup = setup_node,
+	/* /dev/loop0 */
+	.major = 7,
+	.minor = 0,
+	.mode = S_IFBLK,
+};
+
+FIXTURE_VARIANT_ADD(file, S_IFCHR)
+{
+	.name = "S_IFCHR",
+	.expected = EACCES,
+	.setup = setup_node,
+	/* /dev/zero */
+	.major = 1,
+	.minor = 5,
+	.mode = S_IFCHR,
+};
+
+void setup_fifo(struct __test_metadata *_metadata,
+		FIXTURE_DATA(file) *self,
+		const FIXTURE_VARIANT(file) *variant)
+{
+	ASSERT_EQ(mkfifo(self->pathname, 0755), 0);
+}
+
+FIXTURE_VARIANT_ADD(file, S_IFIFO)
+{
+	.name = "S_IFIFO",
+	.expected = EACCES,
+	.setup = setup_fifo,
+};
+
+FIXTURE_SETUP(file)
+{
+	ASSERT_GT(asprintf(&self->pathname, "%s.test", variant->name), 6);
+	self->is_dir = variant->is_dir;
+
+	rm(_metadata, self->pathname, variant->is_dir);
+	variant->setup(_metadata, self, variant);
+}
+
+FIXTURE_TEARDOWN(file)
+{
+	rm(_metadata, self->pathname, self->is_dir);
+}
+
+TEST_F(file, exec_errno)
+{
+	char * const argv[2] = { (char * const)self->pathname, NULL };
+
+	EXPECT_LT(execv(argv[0], argv), 0);
+	EXPECT_EQ(errno, variant->expected);
+}
+
+/* S_IFSOCK */
+FIXTURE(sock)
+{
+	int fd;
+};
+
+FIXTURE_SETUP(sock)
+{
+	self->fd = socket(AF_INET, SOCK_STREAM, 0);
+	ASSERT_GE(self->fd, 0);
+}
+
+FIXTURE_TEARDOWN(sock)
+{
+	if (self->fd >= 0)
+		ASSERT_EQ(close(self->fd), 0);
+}
+
+TEST_F(sock, exec_errno)
+{
+	char * const argv[2] = { " magic socket ", NULL };
+	char * const envp[1] = { NULL };
+
+	EXPECT_LT(fexecve(self->fd, argv, envp), 0);
+	EXPECT_EQ(errno, EACCES);
+}
+
+TEST_HARNESS_MAIN