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2025-04-11selftests/landlock: Add PID tests for audit recordsMickaël Salaün
Add audit.thread tests to check that the PID tied to a domain is not a thread ID but the thread group ID. These new tests would not pass without the previous TGID fix. Extend matches_log_domain_allocated() to check against the PID that created the domain. Test coverage for security/landlock is 93.6% of 1524 lines according to gcc/gcov-14. Cc: Christian Brauner <brauner@kernel.org> Cc: Günther Noack <gnoack@google.com> Cc: Paul Moore <paul@paul-moore.com> Link: https://lore.kernel.org/r/20250410171725.1265860-3-mic@digikod.net Signed-off-by: Mickaël Salaün <mic@digikod.net>
2025-03-26selftests/landlock: Add audit tests for filesystemMickaël Salaün
Test all filesystem blockers, including events with several records, and record with several blockers: - fs.execute - fs.write_file - fs.read_file - fs_read_dir - fs.remove_dir - fs.remove_file - fs.make_char - fs.make_dir - fs.make_reg - fs.make_sock - fs.make_fifo - fs.make_block - fs.make_sym - fs.refer - fs.truncate - fs.ioctl_dev - fs.change_topology Cc: Günther Noack <gnoack@google.com> Cc: Paul Moore <paul@paul-moore.com> Link: https://lore.kernel.org/r/20250320190717.2287696-27-mic@digikod.net Signed-off-by: Mickaël Salaün <mic@digikod.net>
2025-01-31Merge tag 'AT_EXECVE_CHECK-v6.14-rc1-fix1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux Pull AT_EXECVE_CHECK selftest fix from Kees Cook: "Fixes the AT_EXECVE_CHECK selftests which didn't run on old versions of glibc" * tag 'AT_EXECVE_CHECK-v6.14-rc1-fix1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: selftests: Handle old glibc without execveat(2)
2025-01-27selftests: Handle old glibc without execveat(2)Mickaël Salaün
Add an execveat(2) wrapper because glibc < 2.34 does not have one. This fixes the check-exec tests and samples. Cc: Günther Noack <gnoack@google.com> Cc: Jeff Xu <jeffxu@chromium.org> Cc: Kees Cook <kees@kernel.org> Cc: Mimi Zohar <zohar@linux.ibm.com> Cc: Paul Moore <paul@paul-moore.com> Cc: Roberto Sassu <roberto.sassu@huawei.com> Cc: Serge Hallyn <serge@hallyn.com> Cc: Stefan Berger <stefanb@linux.ibm.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Reported-by: Nathan Chancellor <nathan@kernel.org> Closes: https://lore.kernel.org/r/20250114205645.GA2825031@ax162 Signed-off-by: Mickaël Salaün <mic@digikod.net> Reviewed-by: Günther Noack <gnoack3000@gmail.com> Link: https://lore.kernel.org/r/20250115144753.311152-1-mic@digikod.net Signed-off-by: Kees Cook <kees@kernel.org>
2025-01-22Merge tag 'AT_EXECVE_CHECK-v6.14-rc1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux Pull AT_EXECVE_CHECK from Kees Cook: - Implement AT_EXECVE_CHECK flag to execveat(2) (Mickaël Salaün) - Implement EXEC_RESTRICT_FILE and EXEC_DENY_INTERACTIVE securebits (Mickaël Salaün) - Add selftests and samples for AT_EXECVE_CHECK (Mickaël Salaün) * tag 'AT_EXECVE_CHECK-v6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: ima: instantiate the bprm_creds_for_exec() hook samples/check-exec: Add an enlighten "inc" interpreter and 28 tests selftests: ktap_helpers: Fix uninitialized variable samples/check-exec: Add set-exec selftests/landlock: Add tests for execveat + AT_EXECVE_CHECK selftests/exec: Add 32 tests for AT_EXECVE_CHECK and exec securebits security: Add EXEC_RESTRICT_FILE and EXEC_DENY_INTERACTIVE securebits exec: Add a new AT_EXECVE_CHECK flag to execveat(2)
2025-01-17selftests/landlock: Add layout1.umount_sandboxer testsMickaël Salaün
Check that a domain is not tied to the executable file that created it. For instance, that could happen if a Landlock domain took a reference to a struct path. Move global path names to common.h and replace copy_binary() with a more generic copy_file() helper. Test coverage for security/landlock is 92.7% of 1133 lines according to gcc/gcov-14. Cc: Günther Noack <gnoack@google.com> Link: https://lore.kernel.org/r/20250108154338.1129069-23-mic@digikod.net [mic: Update date and add test coverage] Signed-off-by: Mickaël Salaün <mic@digikod.net>
2025-01-17selftests/landlock: Fix error messageMickaël Salaün
The global variable errno may not be set in test_execute(). Do not use it in related error message. Cc: Günther Noack <gnoack@google.com> Fixes: e1199815b47b ("selftests/landlock: Add user space tests") Link: https://lore.kernel.org/r/20250108154338.1129069-21-mic@digikod.net Signed-off-by: Mickaël Salaün <mic@digikod.net>
2025-01-17selftests/landlock: Add test to check partial access in a mount treeMickaël Salaün
Add layout1.refer_part_mount_tree_is_allowed to test the masked logical issue regarding collect_domain_accesses() calls followed by the is_access_to_paths_allowed() check in current_check_refer_path(). See previous commit. This test should work without the previous fix as well, but it enables us to make sure future changes will not have impact regarding this behavior. Cc: Günther Noack <gnoack@google.com> Link: https://lore.kernel.org/r/20250108154338.1129069-13-mic@digikod.net Signed-off-by: Mickaël Salaün <mic@digikod.net>
2024-12-18selftests/landlock: Add tests for execveat + AT_EXECVE_CHECKMickaël Salaün
Extend layout1.execute with the new AT_EXECVE_CHECK flag. The semantic with AT_EXECVE_CHECK is the same as with a simple execve(2), LANDLOCK_ACCESS_FS_EXECUTE is enforced the same way. Cc: Günther Noack <gnoack@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Paul Moore <paul@paul-moore.com> Signed-off-by: Mickaël Salaün <mic@digikod.net> Link: https://lore.kernel.org/r/20241212174223.389435-5-mic@digikod.net Signed-off-by: Kees Cook <kees@kernel.org>
2024-09-16selftests/landlock: Test UNIX sockets with any address formatsTahera Fahimi
Expand abstract UNIX socket restriction tests by examining different scenarios for UNIX sockets with pathname or unnamed address formats connection with scoped domain. The various_address_sockets tests ensure that UNIX sockets bound to a filesystem pathname and unnamed sockets created by socketpair can still connect to a socket outside of their scoped domain, meaning that even if the domain is scoped with LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET, the socket can connect to a socket outside the scoped domain. Signed-off-by: Tahera Fahimi <fahimitahera@gmail.com> Link: https://lore.kernel.org/r/a9e8016aaa5846252623b158c8f1ce0d666944f4.1725494372.git.fahimitahera@gmail.com [mic: Remove useless clang-format tags, fix unlink/rmdir calls, drop capabilities, rename variables, remove useless mknod/unlink calls, clean up fixture, test write/read on sockets, test sendto() on datagram sockets, close sockets as soon as possible] Co-developed-by: Mickaël Salaün <mic@digikod.net> Signed-off-by: Mickaël Salaün <mic@digikod.net>
2024-05-31selftests/landlock: Add layout1.refer_mount_rootMickaël Salaün
Add tests to check error codes when linking or renaming a mount root directory. This previously triggered a kernel warning, but it is fixed with the previous commit. Cc: Günther Noack <gnoack@google.com> Cc: Paul Moore <paul@paul-moore.com> Link: https://lore.kernel.org/r/20240516181935.1645983-3-mic@digikod.net Signed-off-by: Mickaël Salaün <mic@digikod.net>
2024-05-13selftests/landlock: Exhaustive test for the IOCTL allow-listGünther Noack
This test checks all IOCTL commands implemented in do_vfs_ioctl(). Test coverage for security/landlock is 90.9% of 722 lines according to gcc/gcov-13. Suggested-by: Mickaël Salaün <mic@digikod.net> Signed-off-by: Günther Noack <gnoack@google.com> Link: https://lore.kernel.org/r/20240419161122.2023765-8-gnoack@google.com [mic: Add test coverage] Signed-off-by: Mickaël Salaün <mic@digikod.net>
2024-05-13selftests/landlock: Check IOCTL restrictions for named UNIX domain socketsGünther Noack
The LANDLOCK_ACCESS_FS_IOCTL_DEV right should have no effect on the use of named UNIX domain sockets. Suggested-by: Mickaël Salaün <mic@digikod.net> Signed-off-by: Günther Noack <gnoack@google.com> Link: https://lore.kernel.org/r/20240419161122.2023765-7-gnoack@google.com [mic: Add missing stddef.h for offsetof()] Signed-off-by: Mickaël Salaün <mic@digikod.net>
2024-05-13selftests/landlock: Test IOCTLs on named pipesGünther Noack
Named pipes should behave like pipes created with pipe(2), so we don't want to restrict IOCTLs on them. Suggested-by: Mickaël Salaün <mic@digikod.net> Signed-off-by: Günther Noack <gnoack@google.com> Link: https://lore.kernel.org/r/20240419161122.2023765-6-gnoack@google.com Signed-off-by: Mickaël Salaün <mic@digikod.net>
2024-05-13selftests/landlock: Test ioctl(2) and ftruncate(2) with open(O_PATH)Günther Noack
ioctl(2) and ftruncate(2) operations on files opened with O_PATH should always return EBADF, independent of the LANDLOCK_ACCESS_FS_TRUNCATE and LANDLOCK_ACCESS_FS_IOCTL_DEV access rights in that file hierarchy. Suggested-by: Mickaël Salaün <mic@digikod.net> Signed-off-by: Günther Noack <gnoack@google.com> Link: https://lore.kernel.org/r/20240419161122.2023765-5-gnoack@google.com Signed-off-by: Mickaël Salaün <mic@digikod.net>
2024-05-13selftests/landlock: Test IOCTL with memfdsGünther Noack
Because the LANDLOCK_ACCESS_FS_IOCTL_DEV right is associated with the opened file during open(2), IOCTLs are supposed to work with files which are opened by means other than open(2). Signed-off-by: Günther Noack <gnoack@google.com> Link: https://lore.kernel.org/r/20240419161122.2023765-4-gnoack@google.com Signed-off-by: Mickaël Salaün <mic@digikod.net>
2024-05-13selftests/landlock: Test IOCTL supportGünther Noack
Exercises Landlock's IOCTL feature in different combinations of handling and permitting the LANDLOCK_ACCESS_FS_IOCTL_DEV right, and in different combinations of using files and directories. Signed-off-by: Günther Noack <gnoack@google.com> Link: https://lore.kernel.org/r/20240419161122.2023765-3-gnoack@google.com Signed-off-by: Mickaël Salaün <mic@digikod.net>
2024-05-13landlock: Add IOCTL access right for character and block devicesGünther Noack
Introduces the LANDLOCK_ACCESS_FS_IOCTL_DEV right and increments the Landlock ABI version to 5. This access right applies to device-custom IOCTL commands when they are invoked on block or character device files. Like the truncate right, this right is associated with a file descriptor at the time of open(2), and gets respected even when the file descriptor is used outside of the thread which it was originally opened in. Therefore, a newly enabled Landlock policy does not apply to file descriptors which are already open. If the LANDLOCK_ACCESS_FS_IOCTL_DEV right is handled, only a small number of safe IOCTL commands will be permitted on newly opened device files. These include FIOCLEX, FIONCLEX, FIONBIO and FIOASYNC, as well as other IOCTL commands for regular files which are implemented in fs/ioctl.c. Noteworthy scenarios which require special attention: TTY devices are often passed into a process from the parent process, and so a newly enabled Landlock policy does not retroactively apply to them automatically. In the past, TTY devices have often supported IOCTL commands like TIOCSTI and some TIOCLINUX subcommands, which were letting callers control the TTY input buffer (and simulate keypresses). This should be restricted to CAP_SYS_ADMIN programs on modern kernels though. Known limitations: The LANDLOCK_ACCESS_FS_IOCTL_DEV access right is a coarse-grained control over IOCTL commands. Landlock users may use path-based restrictions in combination with their knowledge about the file system layout to control what IOCTLs can be done. Cc: Paul Moore <paul@paul-moore.com> Cc: Christian Brauner <brauner@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Günther Noack <gnoack@google.com> Link: https://lore.kernel.org/r/20240419161122.2023765-2-gnoack@google.com Signed-off-by: Mickaël Salaün <mic@digikod.net>
2024-05-11selftests/harness: Fix vfork() side effectsMickaël Salaün
Setting the time namespace with CLONE_NEWTIME returns -EUSERS if the calling thread shares memory with another thread (because of the shared vDSO), which is the case when it is created with vfork(). Fix pidfd_setns_test by replacing test harness's vfork() call with a clone3() call with CLONE_VFORK, and an explicit sharing of the _metadata and self objects. Replace _metadata->teardown_parent with a new FIXTURE_TEARDOWN_PARENT() helper that can replace FIXTURE_TEARDOWN(). This is a cleaner approach and it enables to selectively share the fixture data between the child process running tests and the parent process running the fixture teardown. This also avoids updating several tests to not rely on the self object's copy-on-write property (e.g. storing the returned value of a fork() call). Cc: Christian Brauner <brauner@kernel.org> Cc: David S. Miller <davem@davemloft.net> Cc: Günther Noack <gnoack@google.com> Cc: Jakub Kicinski <kuba@kernel.org> Cc: Mark Brown <broonie@kernel.org> Cc: Shuah Khan <shuah@kernel.org> Cc: Will Drewry <wad@chromium.org> Reported-by: kernel test robot <oliver.sang@intel.com> Closes: https://lore.kernel.org/oe-lkp/202403291015.1fcfa957-oliver.sang@intel.com Fixes: 0710a1a73fb4 ("selftests/harness: Merge TEST_F_FORK() into TEST_F()") Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20240511171445.904356-10-mic@digikod.net Signed-off-by: Mickaël Salaün <mic@digikod.net>
2024-05-11selftests/landlock: Do not allocate memory in fixture dataMickaël Salaün
Do not allocate self->dir_path in the test process because this would not be visible in the FIXTURE_TEARDOWN() process when relying on fork()/clone3() instead of vfork(). This change is required for a following commit removing vfork() call to not break the layout3_fs.* test cases. Cc: Günther Noack <gnoack@google.com> Cc: Shuah Khan <skhan@linuxfoundation.org> Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20240511171445.904356-6-mic@digikod.net Signed-off-by: Mickaël Salaün <mic@digikod.net>
2024-05-11selftests/landlock: Fix FS tests when run on a private mount pointMickaël Salaün
According to the test environment, the mount point of the test's working directory may be shared or not, which changes the visibility of the nested "tmp" mount point for the test's parent process calling umount("tmp"). This was spotted while running tests in containers [1], where mount points are private. Cc: Günther Noack <gnoack@google.com> Cc: Shuah Khan <skhan@linuxfoundation.org> Link: https://github.com/landlock-lsm/landlock-test-tools/pull/4 [1] Fixes: 41cca0542d7c ("selftests/harness: Fix TEST_F()'s vfork handling") Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20240511171445.904356-3-mic@digikod.net Signed-off-by: Mickaël Salaün <mic@digikod.net>
2024-03-06selftests/harness: Fix TEST_F()'s vfork handlingMickaël Salaün
Always run fixture setup in the grandchild process, and by default also run the teardown in the same process. However, this change makes it possible to run the teardown in a parent process when _metadata->teardown_parent is set to true (e.g. in fixture setup). Fix TEST_SIGNAL() by forwarding grandchild's signal to its parent. Fix seccomp tests by running the test setup in the parent of the test thread, as expected by the related test code. Fix Landlock tests by waiting for the grandchild before processing _metadata. Use of exit(3) in tests should be OK because the environment in which the vfork(2) call happen is already dedicated to the running test (with flushed stdio, setpgrp() call), see __run_test() and the call to fork(2) just before running the setup/test/teardown. Even if the test configures its own exit handlers, they will not be run by the parent because it never calls exit(3), and the test function either ends with a call to _exit(2) or a signal. Cc: Günther Noack <gnoack@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Will Drewry <wad@chromium.org> Fixes: 0710a1a73fb4 ("selftests/harness: Merge TEST_F_FORK() into TEST_F()") Reviewed-by: Kees Cook <keescook@chromium.org> Tested-by: Kees Cook <keescook@chromium.org> Signed-off-by: Mickaël Salaün <mic@digikod.net> Reported-by: Mark Brown <broonie@kernel.org> Tested-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20240305201029.1331333-1-mic@digikod.net Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-03-01selftests: kselftest_harness: save full exit code in metadataJakub Kicinski
Instead of tracking passed = 0/1 rename the field to exit_code and invert the values so that they match the KSFT_* exit codes. This will allow us to fold SKIP / XFAIL into the same value. Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2024-01-25selftests/landlock: Fix fs_test build with old libcHu Yadi
One issue comes up while building selftest/landlock/fs_test on my side (gcc 7.3/glibc-2.28/kernel-4.19). gcc -Wall -O2 -isystem fs_test.c -lcap -o selftests/landlock/fs_test fs_test.c:4575:9: error: initializer element is not constant .mnt = mnt_tmp, ^~~~~~~ Signed-off-by: Hu Yadi <hu.yadi@h3c.com> Suggested-by: Jiao <jiaoxupo@h3c.com> Reviewed-by: Berlin <berlin@h3c.com> Link: https://lore.kernel.org/r/20240124022908.42100-1-hu.yadi@h3c.com Fixes: 04f9070e99a4 ("selftests/landlock: Add tests for pseudo filesystems") [mic: Factor out mount's data string and make mnt_tmp static] Signed-off-by: Mickaël Salaün <mic@digikod.net>
2024-01-03selftests/landlock: Rename "permitted" to "allowed" in ftruncate testsGünther Noack
Suggested-by: Mickaël Salaün <mic@digikod.net> Signed-off-by: Günther Noack <gnoack@google.com> Link: https://lore.kernel.org/r/20231208155121.1943775-3-gnoack@google.com Signed-off-by: Mickaël Salaün <mic@digikod.net>
2023-12-22selftests/landlock: Add tests to check unhandled rule's access rightsMickaël Salaün
Add two tests to make sure that we cannot add a rule to a ruleset if the rule's access rights that are not handled by the ruleset: * fs: layout1.rule_with_unhandled_access * net: mini.rule_with_unhandled_access Cc: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> Reviewed-by: Günther Noack <gnoack@google.com> Link: https://lore.kernel.org/r/20231130093616.67340-3-mic@digikod.net Signed-off-by: Mickaël Salaün <mic@digikod.net>
2023-12-22selftests/landlock: Add tests to check unknown rule's access rightsMickaël Salaün
Add two tests to make sure that we cannot add a rule with access rights that are unknown: * fs: layout0.rule_with_unknown_access * net: mini.rule_with_unknown_access Rename unknown_access_rights tests to ruleset_with_unknown_access . Cc: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> Reviewed-by: Günther Noack <gnoack@google.com> Link: https://lore.kernel.org/r/20231130093616.67340-2-mic@digikod.net Signed-off-by: Mickaël Salaün <mic@digikod.net>
2023-10-27selftests/landlock: Add tests for FS topology changes with network rulesMickaël Salaün
Add 2 tests to the layout1 fixture: * topology_changes_with_net_only: Checks that FS topology changes are not denied by network-only restrictions. * topology_changes_with_net_and_fs: Make sure that FS topology changes are still denied with FS and network restrictions. This specifically test commit d7220364039f ("landlock: Allow FS topology changes for domains without such rule type"). Cc: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> Link: https://lore.kernel.org/r/20231027154615.815134-1-mic@digikod.net Signed-off-by: Mickaël Salaün <mic@digikod.net>
2023-10-26selftests/landlock: Share enforce_ruleset() helperKonstantin Meskhidze
Move enforce_ruleset() helper function to common.h so that it can be used both by filesystem tests and network ones. Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> Link: https://lore.kernel.org/r/20231026014751.414649-10-konstantin.meskhidze@huawei.com Signed-off-by: Mickaël Salaün <mic@digikod.net>
2023-08-30selftests/landlock: Fix a resource leakDing Xiang
The opened file should be closed before return, otherwise resource leak will occur. Signed-off-by: Ding Xiang <dingxiang@cmss.chinamobile.com> Link: https://lore.kernel.org/r/20230830101148.3738-1-dingxiang@cmss.chinamobile.com Fixes: 3de64b656b3c ("selftests/landlock: Add supports_filesystem() helper") Signed-off-by: Mickaël Salaün <mic@digikod.net>
2023-06-12selftests/landlock: Add hostfs testsMickaël Salaün
Add tests for the hostfs filesystems to make sure it has a consistent inode management, which is required for Landlock's file hierarchy identification. This adds 5 new tests for layout3_fs with the hostfs variant. Add hostfs to the new (architecture-specific) config.um file. The hostfs filesystem, only available for an User-Mode Linux kernel, is special because we cannot explicitly mount it. The layout3_fs.hostfs variant tests are skipped if the current test directory is not backed by this filesystem. The layout3_fs.hostfs.tag_inode_dir_child and layout3_fs.hostfs.tag_inode_file tests pass thanks to a previous commit fixing hostfs inode management. Without this fix, the deny-by-default policy would apply and all access requests would be denied. Link: https://lore.kernel.org/r/20230612191430.339153-7-mic@digikod.net Signed-off-by: Mickaël Salaün <mic@digikod.net>
2023-06-12selftests/landlock: Add tests for pseudo filesystemsMickaël Salaün
Add generic and read-only tests for 6 pseudo filesystems to make sure they have a consistent inode management, which is required for Landlock's file hierarchy identification: - tmpfs - ramfs - cgroup2 - proc - sysfs Update related kernel configuration to support these new filesystems, remove useless CONFIG_SECURITY_PATH, and sort all entries. If these filesystems are not supported by the kernel running tests, the related tests are skipped. Expanding variants, this adds 25 new tests for layout3_fs: - tag_inode_dir_parent - tag_inode_dir_mnt - tag_inode_dir_child - tag_inode_dir_file - release_inodes Test coverage for security/landlock with kernel debug code: - 94.7% of 835 lines according to gcc/gcov-12 - 93.0% of 852 lines according to gcc/gcov-13 Test coverage for security/landlock without kernel debug code: - 95.5% of 624 lines according to gcc/gcov-12 - 93.1% of 641 lines according to gcc/gcov-13 Link: https://lore.kernel.org/r/20230612191430.339153-6-mic@digikod.net Signed-off-by: Mickaël Salaün <mic@digikod.net>
2023-06-12selftests/landlock: Make mounts configurableMickaël Salaün
Add a new struct mnt_opt to define a mount point with the mount_opt() helper. This doesn't change tests but prepare for the next commit. Link: https://lore.kernel.org/r/20230612191430.339153-5-mic@digikod.net Signed-off-by: Mickaël Salaün <mic@digikod.net>
2023-06-12selftests/landlock: Add supports_filesystem() helperMickaël Salaün
Replace supports_overlayfs() with supports_filesystem() to be able to check several filesystems. This will be useful in a following commit. Only check for overlay filesystem once in the setup step, and then rely on self->skip_test. Cc: Guenter Roeck <groeck@chromium.org> Cc: Jeff Xu <jeffxu@google.com> Link: https://lore.kernel.org/r/20230612191430.339153-4-mic@digikod.net Signed-off-by: Mickaël Salaün <mic@digikod.net>
2023-06-12selftests/landlock: Don't create useless file layoutsMickaël Salaün
Add and use a layout0 test fixture to not populate the tmpfs filesystem if it is not required for tests: unknown_access_rights, proc_nsfs, unpriv and max_layers. This doesn't change these tests but it speeds up their setup and makes them less prone to error. This prepare the ground for a next commit. Link: https://lore.kernel.org/r/20230612191430.339153-3-mic@digikod.net Signed-off-by: Mickaël Salaün <mic@digikod.net>
2023-01-13selftests/landlock: Skip overlayfs tests when not supportedJeff Xu
overlayfs may be disabled in the kernel configuration, causing related tests to fail. Check that overlayfs is supported at runtime, so we can skip layout2_overlay.* accordingly. Signed-off-by: Jeff Xu <jeffxu@google.com> Reviewed-by: Guenter Roeck <groeck@chromium.org> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20230113053229.1281774-2-jeffxu@google.com [mic: Reword comments and constify variables] Signed-off-by: Mickaël Salaün <mic@digikod.net>
2022-10-19selftests/landlock: Test ftruncate on FDs created by memfd_create(2)Günther Noack
All file descriptors that are truncatable need to have the Landlock access rights set correctly on the file's Landlock security blob. This is also the case for files that are opened by other means than open(2). Test coverage for security/landlock is 94.7% of 838 lines according to gcc/gcov-11. Signed-off-by: Günther Noack <gnoack3000@gmail.com> Link: https://lore.kernel.org/r/20221018182216.301684-10-gnoack3000@gmail.com [mic: Add test coverage in commit message] Signed-off-by: Mickaël Salaün <mic@digikod.net>
2022-10-19selftests/landlock: Test FD passing from restricted to unrestricted processesGünther Noack
A file descriptor created in a restricted process carries Landlock restrictions with it which will apply even if the same opened file is used from an unrestricted process. This change extracts suitable FD-passing helpers from base_test.c and moves them to common.h. We use the fixture variants from the ftruncate fixture to exercise the same scenarios as in the open_and_ftruncate test, but doing the Landlock restriction and open() in a different process than the ftruncate() call. Signed-off-by: Günther Noack <gnoack3000@gmail.com> Link: https://lore.kernel.org/r/20221018182216.301684-9-gnoack3000@gmail.com Signed-off-by: Mickaël Salaün <mic@digikod.net>
2022-10-19selftests/landlock: Test open() and ftruncate() in multiple scenariosGünther Noack
This test uses multiple fixture variants to exercise a broader set of scnenarios. Signed-off-by: Günther Noack <gnoack3000@gmail.com> Link: https://lore.kernel.org/r/20221018182216.301684-7-gnoack3000@gmail.com Signed-off-by: Mickaël Salaün <mic@digikod.net>
2022-10-19selftests/landlock: Test file truncation supportGünther Noack
These tests exercise the following truncation operations: * truncate() (truncate by path) * ftruncate() (truncate by file descriptor) * open with the O_TRUNC flag * special case: creat(), which is open with O_CREAT|O_WRONLY|O_TRUNC. in the following scenarios: * Files with read, write and truncate rights. * Files with read and truncate rights. * Files with the truncate right. * Files without the truncate right. In particular, the following scenarios are enforced with the test: * open() with O_TRUNC requires the truncate right, if it truncates a file. open() already checks security_path_truncate() in this case, and it required no additional check in the Landlock LSM's file_open hook. * creat() requires the truncate right when called with an existing filename. * creat() does *not* require the truncate right when it's creating a new file. * ftruncate() requires that the file was opened by a thread that had the truncate right for the file at the time of open(). (The rights are carried along with the opened file.) Signed-off-by: Günther Noack <gnoack3000@gmail.com> Link: https://lore.kernel.org/r/20221018182216.301684-6-gnoack3000@gmail.com Signed-off-by: Mickaël Salaün <mic@digikod.net>
2022-10-19landlock: Support file truncationGünther Noack
Introduce the LANDLOCK_ACCESS_FS_TRUNCATE flag for file truncation. This flag hooks into the path_truncate, file_truncate and file_alloc_security LSM hooks and covers file truncation using truncate(2), ftruncate(2), open(2) with O_TRUNC, as well as creat(). This change also increments the Landlock ABI version, updates corresponding selftests, and updates code documentation to document the flag. In security/security.c, allocate security blobs at pointer-aligned offsets. This fixes the problem where one LSM's security blob can shift another LSM's security blob to an unaligned address (reported by Nathan Chancellor). The following operations are restricted: open(2): requires the LANDLOCK_ACCESS_FS_TRUNCATE right if a file gets implicitly truncated as part of the open() (e.g. using O_TRUNC). Notable special cases: * open(..., O_RDONLY|O_TRUNC) can truncate files as well in Linux * open() with O_TRUNC does *not* need the TRUNCATE right when it creates a new file. truncate(2) (on a path): requires the LANDLOCK_ACCESS_FS_TRUNCATE right. ftruncate(2) (on a file): requires that the file had the TRUNCATE right when it was previously opened. File descriptors acquired by other means than open(2) (e.g. memfd_create(2)) continue to support truncation with ftruncate(2). Cc: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Günther Noack <gnoack3000@gmail.com> Acked-by: Paul Moore <paul@paul-moore.com> (LSM) Link: https://lore.kernel.org/r/20221018182216.301684-5-gnoack3000@gmail.com Signed-off-by: Mickaël Salaün <mic@digikod.net>
2022-09-02landlock: Fix file reparenting without explicit LANDLOCK_ACCESS_FS_REFERMickaël Salaün
This change fixes a mis-handling of the LANDLOCK_ACCESS_FS_REFER right when multiple rulesets/domains are stacked. The expected behaviour was that an additional ruleset can only restrict the set of permitted operations, but in this particular case, it was potentially possible to re-gain the LANDLOCK_ACCESS_FS_REFER right. With the introduction of LANDLOCK_ACCESS_FS_REFER, we added the first globally denied-by-default access right. Indeed, this lifted an initial Landlock limitation to rename and link files, which was initially always denied when the source or the destination were different directories. This led to an inconsistent backward compatibility behavior which was only taken into account if no domain layer were using the new LANDLOCK_ACCESS_FS_REFER right. However, when restricting a thread with a new ruleset handling LANDLOCK_ACCESS_FS_REFER, all inherited parent rulesets/layers not explicitly handling LANDLOCK_ACCESS_FS_REFER would behave as if they were handling this access right and with all their rules allowing it. This means that renaming and linking files could became allowed by these parent layers, but all the other required accesses must also be granted: all layers must allow file removal or creation, and renaming and linking operations cannot lead to privilege escalation according to the Landlock policy. See detailed explanation in commit b91c3e4ea756 ("landlock: Add support for file reparenting with LANDLOCK_ACCESS_FS_REFER"). To say it another way, this bug may lift the renaming and linking limitations of the initial Landlock version, and a same ruleset can enforce different restrictions depending on previous or next enforced ruleset (i.e. inconsistent behavior). The LANDLOCK_ACCESS_FS_REFER right cannot give access to data not already allowed, but this doesn't follow the contract of the first Landlock ABI. This fix puts back the limitation for sandboxes that didn't opt-in for this additional right. For instance, if a first ruleset allows LANDLOCK_ACCESS_FS_MAKE_REG on /dst and LANDLOCK_ACCESS_FS_REMOVE_FILE on /src, renaming /src/file to /dst/file is denied. However, without this fix, stacking a new ruleset which allows LANDLOCK_ACCESS_FS_REFER on / would now permit the sandboxed thread to rename /src/file to /dst/file . This change fixes the (absolute) rule access rights, which now always forbid LANDLOCK_ACCESS_FS_REFER except when it is explicitly allowed when creating a rule. Making all domain handle LANDLOCK_ACCESS_FS_REFER was an initial approach but there is two downsides: * it makes the code more complex because we still want to check that a rule allowing LANDLOCK_ACCESS_FS_REFER is legitimate according to the ruleset's handled access rights (i.e. ABI v1 != ABI v2); * it would not allow to identify if the user created a ruleset explicitly handling LANDLOCK_ACCESS_FS_REFER or not, which will be an issue to audit Landlock. Instead, this change adds an ACCESS_INITIALLY_DENIED list of denied-by-default rights, which (only) contains LANDLOCK_ACCESS_FS_REFER. All domains are treated as if they are also handling this list, but without modifying their fs_access_masks field. A side effect is that the errno code returned by rename(2) or link(2) *may* be changed from EXDEV to EACCES according to the enforced restrictions. Indeed, we now have the mechanic to identify if an access is denied because of a required right (e.g. LANDLOCK_ACCESS_FS_MAKE_REG, LANDLOCK_ACCESS_FS_REMOVE_FILE) or if it is denied because of missing LANDLOCK_ACCESS_FS_REFER rights. This may result in different errno codes than for the initial Landlock version, but this approach is more consistent and better for rename/link compatibility reasons, and it wasn't possible before (hence no backport to ABI v1). The layout1.rename_file test reflects this change. Add 4 layout1.refer_denied_by_default* test suites to check that the behavior of a ruleset not handling LANDLOCK_ACCESS_FS_REFER (ABI v1) is unchanged even if another layer handles LANDLOCK_ACCESS_FS_REFER (i.e. ABI v1 precedence). Make sure rule's absolute access rights are correct by testing with and without a matching path. Add test_rename() and test_exchange() helpers. Extend layout1.inval tests to check that a denied-by-default access right is not necessarily part of a domain's handled access rights. Test coverage for security/landlock is 95.3% of 599 lines according to gcc/gcov-11. Fixes: b91c3e4ea756 ("landlock: Add support for file reparenting with LANDLOCK_ACCESS_FS_REFER") Reviewed-by: Paul Moore <paul@paul-moore.com> Reviewed-by: Günther Noack <gnoack3000@gmail.com> Link: https://lore.kernel.org/r/20220831203840.1370732-1-mic@digikod.net Cc: stable@vger.kernel.org [mic: Constify and slightly simplify test helpers] Signed-off-by: Mickaël Salaün <mic@digikod.net>
2022-05-23selftests/landlock: Add 11 new test suites dedicated to file reparentingMickaël Salaün
These test suites try to check all edge cases for directory and file renaming or linking involving a new parent directory, with and without LANDLOCK_ACCESS_FS_REFER and other access rights. layout1: * reparent_refer: Tests simple FS_REFER usage. * reparent_link: Tests a mix of FS_MAKE_REG and FS_REFER with links. * reparent_rename: Tests a mix of FS_MAKE_REG and FS_REFER with renames and RENAME_EXCHANGE. * reparent_exdev_layers_rename1/2: Tests renames with two layers. * reparent_exdev_layers_exchange1/2/3: Tests exchanges with two layers. * reparent_remove: Tests file and directory removal with rename. * reparent_dom_superset: Tests access partial ordering. layout1_bind: * reparent_cross_mount: Tests FS_REFER propagation across mount points. Test coverage for security/landlock is 95.4% of 604 lines according to gcc/gcov-11. Cc: Paul Moore <paul@paul-moore.com> Signed-off-by: Mickaël Salaün <mic@digikod.net> Link: https://lore.kernel.org/r/20220506161102.525323-9-mic@digikod.net
2022-05-23landlock: Add support for file reparenting with LANDLOCK_ACCESS_FS_REFERMickaël Salaün
Add a new LANDLOCK_ACCESS_FS_REFER access right to enable policy writers to allow sandboxed processes to link and rename files from and to a specific set of file hierarchies. This access right should be composed with LANDLOCK_ACCESS_FS_MAKE_* for the destination of a link or rename, and with LANDLOCK_ACCESS_FS_REMOVE_* for a source of a rename. This lift a Landlock limitation that always denied changing the parent of an inode. Renaming or linking to the same directory is still always allowed, whatever LANDLOCK_ACCESS_FS_REFER is used or not, because it is not considered a threat to user data. However, creating multiple links or renaming to a different parent directory may lead to privilege escalations if not handled properly. Indeed, we must be sure that the source doesn't gain more privileges by being accessible from the destination. This is handled by making sure that the source hierarchy (including the referenced file or directory itself) restricts at least as much the destination hierarchy. If it is not the case, an EXDEV error is returned, making it potentially possible for user space to copy the file hierarchy instead of moving or linking it. Instead of creating different access rights for the source and the destination, we choose to make it simple and consistent for users. Indeed, considering the previous constraint, it would be weird to require such destination access right to be also granted to the source (to make it a superset). Moreover, RENAME_EXCHANGE would also add to the confusion because of paths being both a source and a destination. See the provided documentation for additional details. New tests are provided with a following commit. Reviewed-by: Paul Moore <paul@paul-moore.com> Signed-off-by: Mickaël Salaün <mic@digikod.net> Link: https://lore.kernel.org/r/20220506161102.525323-8-mic@digikod.net
2022-05-23landlock: Fix same-layer rule unionsMickaël Salaün
The original behavior was to check if the full set of requested accesses was allowed by at least a rule of every relevant layer. This didn't take into account requests for multiple accesses and same-layer rules allowing the union of these accesses in a complementary way. As a result, multiple accesses requested on a file hierarchy matching rules that, together, allowed these accesses, but without a unique rule allowing all of them, was illegitimately denied. This case should be rare in practice and it can only be triggered by the path_rename or file_open hook implementations. For instance, if, for the same layer, a rule allows execution beneath /a/b and another rule allows read beneath /a, requesting access to read and execute at the same time for /a/b should be allowed for this layer. This was an inconsistency because the union of same-layer rule accesses was already allowed if requested once at a time anyway. This fix changes the way allowed accesses are gathered over a path walk. To take into account all these rule accesses, we store in a matrix all layer granting the set of requested accesses, according to the handled accesses. To avoid heap allocation, we use an array on the stack which is 2*13 bytes. A following commit bringing the LANDLOCK_ACCESS_FS_REFER access right will increase this size to reach 112 bytes (2*14*4) in case of link or rename actions. Add a new layout1.layer_rule_unions test to check that accesses from different rules pertaining to the same layer are ORed in a file hierarchy. Also test that it is not the case for rules from different layers. Reviewed-by: Paul Moore <paul@paul-moore.com> Link: https://lore.kernel.org/r/20220506161102.525323-5-mic@digikod.net Cc: stable@vger.kernel.org Signed-off-by: Mickaël Salaün <mic@digikod.net>
2022-05-23landlock: Reduce the maximum number of layers to 16Mickaël Salaün
The maximum number of nested Landlock domains is currently 64. Because of the following fix and to help reduce the stack size, let's reduce it to 16. This seems large enough for a lot of use cases (e.g. sandboxed init service, spawning a sandboxed SSH service, in nested sandboxed containers). Reducing the number of nested domains may also help to discover misuse of Landlock (e.g. creating a domain per rule). Add and use a dedicated layer_mask_t typedef to fit with the number of layers. This might be useful when changing it and to keep it consistent with the maximum number of layers. Reviewed-by: Paul Moore <paul@paul-moore.com> Link: https://lore.kernel.org/r/20220506161102.525323-3-mic@digikod.net Cc: stable@vger.kernel.org Signed-off-by: Mickaël Salaün <mic@digikod.net>
2022-05-23selftests/landlock: Add tests for O_PATHMickaël Salaün
The O_PATH flag is currently not handled by Landlock. Let's make sure this behavior will remain consistent with the same ruleset over time. Cc: Shuah Khan <shuah@kernel.org> Link: https://lore.kernel.org/r/20220506160820.524344-8-mic@digikod.net Cc: stable@vger.kernel.org Signed-off-by: Mickaël Salaün <mic@digikod.net>
2022-05-23selftests/landlock: Fully test file rename with "remove" accessMickaël Salaün
These tests were missing to check the check_access_path() call with all combinations of maybe_remove(old_dentry) and maybe_remove(new_dentry). Extend layout1.link with a new complementary test and check that REMOVE_FILE is not required to link a file. Cc: Shuah Khan <shuah@kernel.org> Link: https://lore.kernel.org/r/20220506160820.524344-7-mic@digikod.net Cc: stable@vger.kernel.org Signed-off-by: Mickaël Salaün <mic@digikod.net>
2022-05-23selftests/landlock: Extend access right tests to directoriesMickaël Salaün
Make sure that all filesystem access rights can be tied to directories. Rename layout1.file_access_rights to layout1.file_and_dir_access_rights to reflect this change. Cc: Shuah Khan <shuah@kernel.org> Link: https://lore.kernel.org/r/20220506160820.524344-6-mic@digikod.net Cc: stable@vger.kernel.org Signed-off-by: Mickaël Salaün <mic@digikod.net>
2022-05-23selftests/landlock: Add tests for unknown access rightsMickaël Salaün
Make sure that trying to use unknown access rights returns an error. Cc: Shuah Khan <shuah@kernel.org> Link: https://lore.kernel.org/r/20220506160820.524344-5-mic@digikod.net Cc: stable@vger.kernel.org Signed-off-by: Mickaël Salaün <mic@digikod.net>
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