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Message-ID: <20220822114701.26975-4-xiujianfeng@huawei.com>
Date: Mon, 22 Aug 2022 19:46:59 +0800
From: Xiu Jianfeng <xiujianfeng@...wei.com>
To: <mic@...ikod.net>, <paul@...l-moore.com>, <jmorris@...ei.org>,
<serge@...lyn.com>, <shuah@...nel.org>, <corbet@....net>
CC: <linux-security-module@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <linux-kselftest@...r.kernel.org>,
<linux-doc@...r.kernel.org>
Subject: [PATCH -next 3/5] landlock/selftests: add selftests for chmod and chown
Add the following simple testcases:
1. chmod/fchmod: remove S_IWUSR and restore S_IWUSR with or without
restriction.
2. chown/fchown: set original uid and gid with or without restriction,
because chown needs CAP_CHOWN and testcase framework don't have this
capability, setting original uid and gid is ok to cover landlock
function.
Signed-off-by: Xiu Jianfeng <xiujianfeng@...wei.com>
---
tools/testing/selftests/landlock/fs_test.c | 228 +++++++++++++++++++++
1 file changed, 228 insertions(+)
diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c
index 5b55b93b5570..f47b4ccd2b26 100644
--- a/tools/testing/selftests/landlock/fs_test.c
+++ b/tools/testing/selftests/landlock/fs_test.c
@@ -59,6 +59,9 @@ static const char file2_s2d3[] = TMP_DIR "/s2d1/s2d2/s2d3/f2";
static const char dir_s3d1[] = TMP_DIR "/s3d1";
static const char file1_s3d1[] = TMP_DIR "/s3d1/f1";
+static const char file2_s3d1[] = TMP_DIR "/s3d1/f2";
+static const char file3_s3d1[] = TMP_DIR "/s3d1/f3";
+
/* dir_s3d2 is a mount point. */
static const char dir_s3d2[] = TMP_DIR "/s3d1/s3d2";
static const char dir_s3d3[] = TMP_DIR "/s3d1/s3d2/s3d3";
@@ -211,6 +214,8 @@ static void create_layout1(struct __test_metadata *const _metadata)
create_file(_metadata, file2_s2d3);
create_file(_metadata, file1_s3d1);
+ create_file(_metadata, file2_s3d1);
+ create_file(_metadata, file3_s3d1);
create_directory(_metadata, dir_s3d2);
set_cap(_metadata, CAP_SYS_ADMIN);
ASSERT_EQ(0, mount("tmp", dir_s3d2, "tmpfs", 0, "size=4m,mode=700"));
@@ -234,6 +239,8 @@ static void remove_layout1(struct __test_metadata *const _metadata)
EXPECT_EQ(0, remove_path(file1_s2d1));
EXPECT_EQ(0, remove_path(file1_s3d1));
+ EXPECT_EQ(0, remove_path(file2_s3d1));
+ EXPECT_EQ(0, remove_path(file3_s3d1));
EXPECT_EQ(0, remove_path(dir_s3d3));
set_cap(_metadata, CAP_SYS_ADMIN);
umount(dir_s3d2);
@@ -3272,6 +3279,227 @@ TEST_F_FORK(layout1, truncate)
EXPECT_EQ(0, test_creat(file_in_dir_w));
}
+static int test_chmod(const char *path)
+{
+ int ret;
+ struct stat st;
+ mode_t mode;
+
+ ret = stat(path, &st);
+ if (ret < 0)
+ return errno;
+ /* save original mode in order to restore */
+ mode = st.st_mode & 0777;
+ /* remove S_IWUSR */
+ ret = chmod(path, mode & ~0200);
+ if (ret < 0)
+ return errno;
+ ret = stat(path, &st);
+ if (ret < 0)
+ return errno;
+ /* check if still has S_IWUSR */
+ if (st.st_mode & 0200)
+ return -EFAULT;
+ /* restore the original mode */
+ ret = chmod(path, mode);
+ if (ret < 0)
+ return errno;
+ return 0;
+}
+
+static int test_fchmod(const char *path)
+{
+ int ret, fd;
+ struct stat st;
+ mode_t mode;
+
+ ret = stat(path, &st);
+ if (ret < 0)
+ return errno;
+ /* save original mode in order to restore */
+ mode = st.st_mode & 0777;
+
+ fd = openat(AT_FDCWD, path, O_RDWR | O_CLOEXEC);
+ if (fd < 0)
+ return errno;
+ /* remove S_IWUSR */
+ ret = fchmod(fd, mode & ~0200);
+ if (ret < 0)
+ goto err;
+ ret = stat(path, &st);
+ if (ret < 0)
+ goto err;
+ /* check if still has S_IWUSR */
+ if (st.st_mode & 0200) {
+ ret = -1;
+ errno = -EFAULT;
+ goto err;
+ }
+ /* restore the original mode */
+ ret = fchmod(fd, mode);
+err:
+ if (close(fd) < 0)
+ return errno;
+ return ret ? errno : 0;
+}
+
+static int test_chown(const char *path)
+{
+ int ret;
+ struct stat st;
+
+ ret = stat(path, &st);
+ if (ret < 0)
+ return errno;
+ /*
+ * chown needs CAP_CHOWN to modify uid and/or gid, however
+ * there is no such capability when the testcases framework
+ * setup, so just chown to original uid/gid, which can also
+ * cover the function in landlock.
+ */
+ ret = chown(path, st.st_uid, st.st_gid);
+ if (ret < 0)
+ return errno;
+ return 0;
+}
+
+static int test_fchown(const char *path)
+{
+ int ret, fd;
+ struct stat st;
+
+ ret = stat(path, &st);
+ if (ret < 0)
+ return errno;
+ fd = openat(AT_FDCWD, path, O_RDWR | O_CLOEXEC);
+ if (fd < 0)
+ return errno;
+ /*
+ * fchown needs CAP_CHOWN to modify uid and/or gid, however
+ * there is no such capability when the testcases framework
+ * setup, so just fchown to original uid/gid, which can also
+ * cover the function in landlock.
+ */
+ ret = fchown(fd, st.st_uid, st.st_gid);
+ if (close(fd) < 0)
+ return errno;
+ return ret ? errno : 0;
+}
+
+TEST_F_FORK(layout1, unhandled_chmod)
+{
+ const struct rule rules[] = {
+ {
+ .path = file2_s3d1,
+ .access = LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_WRITE_FILE,
+ },
+ {
+ .path = file3_s3d1,
+ .access = LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_WRITE_FILE,
+ },
+ {},
+ };
+ const int ruleset_fd =
+ create_ruleset(_metadata, ACCESS_RW, rules);
+
+ ASSERT_LE(0, ruleset_fd);
+ enforce_ruleset(_metadata, ruleset_fd);
+ ASSERT_EQ(0, close(ruleset_fd));
+
+ ASSERT_EQ(0, test_chmod(file2_s3d1));
+ ASSERT_EQ(0, test_fchmod(file2_s3d1));
+ ASSERT_EQ(0, test_chmod(file3_s3d1));
+ ASSERT_EQ(0, test_chmod(dir_s3d1));
+}
+
+TEST_F_FORK(layout1, chmod)
+{
+ const struct rule rules[] = {
+ {
+ .path = file2_s3d1,
+ .access = LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_WRITE_FILE |
+ LANDLOCK_ACCESS_FS_CHMOD,
+ },
+ {
+ .path = file3_s3d1,
+ .access = LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_WRITE_FILE,
+ },
+ {},
+ };
+ const int ruleset_fd =
+ create_ruleset(_metadata, ACCESS_RW | LANDLOCK_ACCESS_FS_CHMOD, rules);
+
+ ASSERT_LE(0, ruleset_fd);
+ enforce_ruleset(_metadata, ruleset_fd);
+ ASSERT_EQ(0, close(ruleset_fd));
+
+ ASSERT_EQ(0, test_chmod(file2_s3d1));
+ ASSERT_EQ(0, test_fchmod(file2_s3d1));
+ ASSERT_EQ(EACCES, test_chmod(file3_s3d1));
+ ASSERT_EQ(EACCES, test_chmod(dir_s3d1));
+}
+
+TEST_F_FORK(layout1, no_chown)
+{
+ const struct rule rules[] = {
+ {
+ .path = file2_s3d1,
+ .access = LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_WRITE_FILE,
+ },
+ {
+ .path = file3_s3d1,
+ .access = LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_WRITE_FILE,
+ },
+ {},
+ };
+ const int ruleset_fd =
+ create_ruleset(_metadata, ACCESS_RW, rules);
+
+ ASSERT_LE(0, ruleset_fd);
+ enforce_ruleset(_metadata, ruleset_fd);
+ ASSERT_EQ(0, close(ruleset_fd));
+
+ ASSERT_EQ(0, test_chown(file2_s3d1));
+ ASSERT_EQ(0, test_fchown(file2_s3d1));
+ ASSERT_EQ(0, test_chown(file3_s3d1));
+ ASSERT_EQ(0, test_chown(dir_s3d1));
+}
+
+TEST_F_FORK(layout1, chown)
+{
+ const struct rule rules[] = {
+ {
+ .path = file2_s3d1,
+ .access = LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_WRITE_FILE |
+ LANDLOCK_ACCESS_FS_CHOWN,
+ },
+ {
+ .path = file3_s3d1,
+ .access = LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_WRITE_FILE,
+ },
+ {},
+ };
+ const int ruleset_fd =
+ create_ruleset(_metadata, ACCESS_RW | LANDLOCK_ACCESS_FS_CHOWN, rules);
+
+ ASSERT_LE(0, ruleset_fd);
+ enforce_ruleset(_metadata, ruleset_fd);
+ ASSERT_EQ(0, close(ruleset_fd));
+
+ ASSERT_EQ(0, test_chown(file2_s3d1));
+ ASSERT_EQ(0, test_fchown(file2_s3d1));
+ ASSERT_EQ(EACCES, test_chown(file3_s3d1));
+ ASSERT_EQ(EACCES, test_chown(dir_s3d1));
+}
+
/* clang-format off */
FIXTURE(layout1_bind) {};
/* clang-format on */
--
2.17.1
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