From: Sargun Dhillon <sargun@sargun.me>
To: linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org
Cc: Aleksa Sarai <cyphar@cyphar.com>, Christoph Hellwig <hch@lst.de>,
Christian Brauner <brauner@kernel.org>
Subject: [PATCH 1/3] selftests/mount_setattr: Add a test to test locking mount attrs
Date: Thu, 10 Aug 2023 02:00:42 -0700 [thread overview]
Message-ID: <20230810090044.1252084-1-sargun@sargun.me> (raw)
Certain mount attributes are meant to be locked when sharing mounts with
another mount namespace. This validates that behaviour holds as expected.
- Locked attributes are not changeable
- Non-locked attributes can be changed, and changed back
Test output:
sudo ./mount_setattr_test -t mount_attr_lock
make: Nothing to be done for 'all'.
TAP version 13
1..1
# Starting 1 tests from 1 test cases.
# RUN mount_setattr.mount_attr_lock ...
# OK mount_setattr.mount_attr_lock
ok 1 mount_setattr.mount_attr_lock
# PASSED: 1 / 1 tests passed.
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
Signed-off-by: Sargun Dhillon <sargun@sargun.me>
---
.../mount_setattr/mount_setattr_test.c | 54 +++++++++++++++++++
1 file changed, 54 insertions(+)
diff --git a/tools/testing/selftests/mount_setattr/mount_setattr_test.c b/tools/testing/selftests/mount_setattr/mount_setattr_test.c
index c6a8c732b802..2aaa4aae41f5 100644
--- a/tools/testing/selftests/mount_setattr/mount_setattr_test.c
+++ b/tools/testing/selftests/mount_setattr/mount_setattr_test.c
@@ -400,6 +400,11 @@ FIXTURE_SETUP(mount_setattr)
ASSERT_EQ(mount("testing", "/tmp/B/BB", "tmpfs", MS_NOATIME | MS_NODEV,
"size=100000,mode=700"), 0);
+ ASSERT_EQ(mkdir("/tmp/C", 0777), 0);
+
+ ASSERT_EQ(mount("testing", "/tmp/C", "tmpfs", MS_NOATIME,
+ "size=100000,mode=700"), 0);
+
ASSERT_EQ(mount("testing", "/mnt", "tmpfs", MS_NOATIME | MS_NODEV,
"size=100000,mode=700"), 0);
@@ -1497,4 +1502,53 @@ TEST_F(mount_setattr, mount_attr_nosymfollow)
ASSERT_EQ(close(fd), 0);
}
+TEST_F(mount_setattr, mount_attr_lock)
+{
+ struct mount_attr attr = {
+ .attr_set = MOUNT_ATTR_RDONLY|MOUNT_ATTR_NOSUID|MOUNT_ATTR_NODEV,
+ };
+
+ ASSERT_EQ(sys_mount_setattr(-1, "/tmp/C", 0, &attr, sizeof(attr)), 0);
+ ASSERT_EQ(prepare_unpriv_mountns(), 0);
+
+ attr.attr_set = 0;
+ attr.attr_clr = MOUNT_ATTR_RDONLY;
+ ASSERT_EQ(sys_mount_setattr(-1, "/tmp/C", 0, &attr, sizeof(attr)), -1);
+ ASSERT_EQ(errno, EPERM);
+
+ attr.attr_clr = MOUNT_ATTR_NOSUID;
+ ASSERT_EQ(sys_mount_setattr(-1, "/tmp/C", 0, &attr, sizeof(attr)), -1);
+ ASSERT_EQ(errno, EPERM);
+
+ attr.attr_clr = MOUNT_ATTR_NODEV;
+ ASSERT_EQ(sys_mount_setattr(-1, "/tmp/C", 0, &attr, sizeof(attr)), -1);
+ ASSERT_EQ(errno, EPERM);
+
+ /* Do not allow changing any atime flags after locking */
+ attr.attr_set = MOUNT_ATTR_RELATIME;
+ attr.attr_clr = MOUNT_ATTR__ATIME;
+ ASSERT_EQ(sys_mount_setattr(-1, "/tmp/C", 0, &attr, sizeof(attr)), -1);
+ ASSERT_EQ(errno, EPERM);
+
+ attr.attr_set = MOUNT_ATTR_STRICTATIME;
+ ASSERT_EQ(sys_mount_setattr(-1, "/tmp/C", 0, &attr, sizeof(attr)), -1);
+ ASSERT_EQ(errno, EPERM);
+
+ attr.attr_set = MOUNT_ATTR_NODIRATIME;
+ ASSERT_EQ(sys_mount_setattr(-1, "/tmp/C", 0, &attr, sizeof(attr)), -1);
+ ASSERT_EQ(errno, EPERM);
+
+ /*
+ * "re-setting" the atime setting to the same value should work.
+ * Also, to make sure this isn't a no-op, try making things less permissive
+ */
+ attr.attr_set = MOUNT_ATTR_NOATIME | MOUNT_ATTR_NOEXEC;
+ ASSERT_EQ(sys_mount_setattr(-1, "/tmp/C", 0, &attr, sizeof(attr)), 0);
+
+ /* We should still be allowed to clear the attribute we set */
+ attr.attr_set = 0;
+ attr.attr_clr = MOUNT_ATTR_NOEXEC;
+ ASSERT_EQ(sys_mount_setattr(-1, "/tmp/C", 0, &attr, sizeof(attr)), 0);
+}
+
TEST_HARNESS_MAIN
--
2.39.3
next reply other threads:[~2023-08-10 9:00 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-10 9:00 Sargun Dhillon [this message]
2023-08-10 9:00 ` [PATCH 2/3] fs: Allow user to lock mount attributes with mount_setattr Sargun Dhillon
2023-08-14 4:40 ` Aleksa Sarai
2023-08-14 6:18 ` Aleksa Sarai
2023-08-14 18:15 ` Sargun Dhillon
2023-08-14 23:58 ` Aleksa Sarai
2023-08-15 9:30 ` Christian Brauner
2023-08-15 13:46 ` Sargun Dhillon
2023-08-16 7:32 ` Christian Brauner
2023-08-16 8:56 ` Aleksa Sarai
2023-08-16 10:36 ` Christian Brauner
2023-08-25 17:02 ` Sargun Dhillon
2023-08-10 9:00 ` [PATCH 3/3] selftests/mount_setattr: Add tests for mount locking API Sargun Dhillon
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