kernel/linux.git/security/landlock/syscalls.c, branch v6.12.80

landlock: Add the errata interface

2025-04-20T08:15:55+00:00

commit 15383a0d63dbcd63dc7e8d9ec1bf3a0f7ebf64ac upstream. Some fixes may require user space to check if they are applied on the running kernel before using a specific feature. For instance, this applies when a restriction was previously too restrictive and is now getting relaxed (e.g. for compatibility reasons). However, non-visible changes for legitimate use (e.g. security fixes) do not require an erratum. Because fixes are backported down to a specific Landlock ABI, we need a way to avoid cherry-pick conflicts. The solution is to only update a file related to the lower ABI impacted by this issue. All the ABI files are then used to create a bitmask of fixes. The new errata interface is similar to the one used to get the supported Landlock ABI version, but it returns a bitmask instead because the order of fixes may not match the order of versions, and not all fixes may apply to all versions. The actual errata will come with dedicated commits. The description is not actually used in the code but serves as documentation. Create the landlock_abi_version symbol and use its value to check errata consistency. Update test_base's create_ruleset_checks_ordering tests and add errata tests. This commit is backportable down to the first version of Landlock. Fixes: 3532b0b4352c ("landlock: Enable user space to infer supported features") Cc: Günther Noack Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20250318161443.279194-3-mic@digikod.net Signed-off-by: Mickaël Salaün Signed-off-by: Greg Kroah-Hartman

landlock: Refactor filesystem access mask management

2024-11-09T18:52:10+00:00

Replace get_raw_handled_fs_accesses() with a generic landlock_union_access_masks(), and replace get_fs_domain() with a generic landlock_get_applicable_domain(). These helpers will also be useful for other types of access. Cc: Mikhail Ivanov Reviewed-by: Günther Noack Link: https://lore.kernel.org/r/20241109110856.222842-2-mic@digikod.net [mic: Slightly improve doc as suggested by Günther] Signed-off-by: Mickaël Salaün

Merge tag 'landlock-6.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux

2024-09-24T17:40:11+00:00

Pull landlock updates from Mickaël Salaün: "We can now scope a Landlock domain thanks to a new "scoped" field that can deny interactions with resources outside of this domain. The LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET flag denies connections to an abstract UNIX socket created outside of the current scoped domain, and the LANDLOCK_SCOPE_SIGNAL flag denies sending a signal to processes outside of the current scoped domain. These restrictions also apply to nested domains according to their scope. The related changes will also be useful to support other kind of IPC isolations" * tag 'landlock-6.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux: landlock: Document LANDLOCK_SCOPE_SIGNAL samples/landlock: Add support for signal scoping selftests/landlock: Test signal created by out-of-bound message selftests/landlock: Test signal scoping for threads selftests/landlock: Test signal scoping landlock: Add signal scoping landlock: Document LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET samples/landlock: Add support for abstract UNIX socket scoping selftests/landlock: Test inherited restriction of abstract UNIX socket selftests/landlock: Test connected and unconnected datagram UNIX socket selftests/landlock: Test UNIX sockets with any address formats selftests/landlock: Test abstract UNIX socket scoping selftests/landlock: Test handling of unknown scope landlock: Add abstract UNIX socket scoping

landlock: Add abstract UNIX socket scoping

2024-09-16T21:50:45+00:00

Introduce a new "scoped" member to landlock_ruleset_attr that can specify LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET to restrict connection to abstract UNIX sockets from a process outside of the socket's domain. Two hooks are implemented to enforce these restrictions: unix_stream_connect and unix_may_send. Closes: https://github.com/landlock-lsm/linux/issues/7 Signed-off-by: Tahera Fahimi Link: https://lore.kernel.org/r/5f7ad85243b78427242275b93481cfc7c127764b.1725494372.git.fahimitahera@gmail.com [mic: Fix commit message formatting, improve documentation, simplify hook_unix_may_send(), and cosmetic fixes including rename of LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET] Co-developed-by: Mickaël Salaün Signed-off-by: Mickaël Salaün

introduce fd_file(), convert all accessors to it.

2024-08-13T02:00:43+00:00

For any changes of struct fd representation we need to turn existing accesses to fields into calls of wrappers. Accesses to struct fd::flags are very few (3 in linux/file.h, 1 in net/socket.c, 3 in fs/overlayfs/file.c and 3 more in explicit initializers). Those can be dealt with in the commit converting to new layout; accesses to struct fd::file are too many for that. This commit converts (almost) all of f.file to fd_file(f). It's not entirely mechanical ('file' is used as a member name more than just in struct fd) and it does not even attempt to distinguish the uses in pointer context from those in boolean context; the latter will be eventually turned into a separate helper (fd_empty()). NOTE: mass conversion to fd_empty(), tempting as it might be, is a bad idea; better do that piecewise in commit that convert from fdget...() to CLASS(...). [conflicts in fs/fhandle.c, kernel/bpf/syscall.c, mm/memcontrol.c caught by git; fs/stat.c one got caught by git grep] [fs/xattr.c conflict] Reviewed-by: Christian Brauner Signed-off-by: Al Viro

landlock: Various documentation improvements

2024-07-18T06:27:47+00:00

* Fix some typos, incomplete or confusing phrases. * Split paragraphs where appropriate. * List the same error code multiple times, if it has multiple possible causes. * Bring wording closer to the man page wording, which has undergone more thorough review (esp. for LANDLOCK_ACCESS_FS_WRITE_FILE). * Small semantic clarifications * Call the ephemeral port range "ephemeral" * Clarify reasons for EFAULT in landlock_add_rule() * Clarify @rule_type doc for landlock_add_rule() This is a collection of small fixes which I collected when preparing the corresponding man pages [1]. Cc: Alejandro Colomar Cc: Konstantin Meskhidze Link: https://lore.kernel.org/r/20240715155554.2791018-1-gnoack@google.com [1] Signed-off-by: Günther Noack Link: https://lore.kernel.org/r/20240715160328.2792835-2-gnoack@google.com [mic: Add label to link, fix formatting spotted by make htmldocs, synchronize userspace-api documentation's date] Signed-off-by: Mickaël Salaün

landlock: Add IOCTL access right for character and block devices

2024-05-13T04:58:29+00:00

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 Cc: Christian Brauner Cc: Arnd Bergmann Signed-off-by: Günther Noack Link: https://lore.kernel.org/r/20240419161122.2023765-2-gnoack@google.com Signed-off-by: Mickaël Salaün

landlock: Warn once if a Landlock action is requested while disabled

2024-03-07T10:29:46+00:00

Because sandboxing can be used as an opportunistic security measure, user space may not log unsupported features. Let the system administrator know if an application tries to use Landlock but failed because it isn't enabled at boot time. This may be caused by boot loader configurations with outdated "lsm" kernel's command-line parameter. Cc: stable@vger.kernel.org Fixes: 265885daf3e5 ("landlock: Add syscall implementations") Reviewed-by: Kees Cook Reviewed-by: Günther Noack Link: https://lore.kernel.org/r/20240227110550.3702236-2-mic@digikod.net Signed-off-by: Mickaël Salaün

landlock: Support network rules with TCP bind and connect

2023-10-26T19:07:15+00:00

Add network rules support in the ruleset management helpers and the landlock_create_ruleset() syscall. Extend user space API to support network actions: * Add new network access rights: LANDLOCK_ACCESS_NET_BIND_TCP and LANDLOCK_ACCESS_NET_CONNECT_TCP. * Add a new network rule type: LANDLOCK_RULE_NET_PORT tied to struct landlock_net_port_attr. The allowed_access field contains the network access rights, and the port field contains the port value according to the controlled protocol. This field can take up to a 64-bit value but the maximum value depends on the related protocol (e.g. 16-bit value for TCP). Network port is in host endianness [1]. * Add a new handled_access_net field to struct landlock_ruleset_attr that contains network access rights. * Increment the Landlock ABI version to 4. Implement socket_bind() and socket_connect() LSM hooks, which enable to control TCP socket binding and connection to specific ports. Expand access_masks_t from u16 to u32 to be able to store network access rights alongside filesystem access rights for rulesets' handled access rights. Access rights are not tied to socket file descriptors but checked at bind() or connect() call time against the caller's Landlock domain. For the filesystem, a file descriptor is a direct access to a file/data. However, for network sockets, we cannot identify for which data or peer a newly created socket will give access to. Indeed, we need to wait for a connect or bind request to identify the use case for this socket. Likewise a directory file descriptor may enable to open another file (i.e. a new data item), but this opening is also restricted by the caller's domain, not the file descriptor's access rights [2]. [1] https://lore.kernel.org/r/278ab07f-7583-a4e0-3d37-1bacd091531d@digikod.net [2] https://lore.kernel.org/r/263c1eb3-602f-57fe-8450-3f138581bee7@digikod.net Signed-off-by: Konstantin Meskhidze Link: https://lore.kernel.org/r/20231026014751.414649-9-konstantin.meskhidze@huawei.com [mic: Extend commit message, fix typo in comments, and specify endianness in the documentation] Co-developed-by: Mickaël Salaün Signed-off-by: Mickaël Salaün

landlock: Refactor landlock_add_rule() syscall

2023-10-26T19:07:14+00:00

Change the landlock_add_rule() syscall to support new rule types with next commits. Add the add_rule_path_beneath() helper to support current filesystem rules. Signed-off-by: Konstantin Meskhidze Link: https://lore.kernel.org/r/20231026014751.414649-8-konstantin.meskhidze@huawei.com Signed-off-by: Mickaël Salaün