kernel/linux.git/security/landlock/syscalls.c, branch v5.15.209

landlock: Add the errata interface

2025-05-02T05:44:20+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: Warn once if a Landlock action is requested while disabled

2024-04-10T14:18:39+00:00

[ Upstream commit 782191c74875cc33b50263e21d76080b1411884d ] 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 This may be caused by boot loader configurations with outdated "lsm" kernel's command-line parameter.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 Signed-off-by: Sasha Levin

landlock: Change landlock_restrict_self(2) check ordering

2022-06-09T08:23:24+00:00

commit eba39ca4b155c54adf471a69e91799cc1727873f upstream. According to the Landlock goal to be a security feature available to unprivileges processes, it makes more sense to first check for no_new_privs before checking anything else (i.e. syscall arguments). Merge inval_fd_enforce and unpriv_enforce_without_no_new_privs tests into the new restrict_self_checks_ordering. This is similar to the previous commit checking other syscalls. Link: https://lore.kernel.org/r/20220506160820.524344-10-mic@digikod.net Cc: stable@vger.kernel.org Signed-off-by: Mickaël Salaün Signed-off-by: Greg Kroah-Hartman

landlock: Change landlock_add_rule(2) argument check ordering

2022-06-09T08:23:23+00:00

commit 589172e5636c4d16c40b90e87543d43defe2d968 upstream. This makes more sense to first check the ruleset FD and then the rule attribute. It will be useful to factor out code for other rule types. Add inval_add_rule_arguments tests, extension of empty_path_beneath_attr tests, to also check error ordering for landlock_add_rule(2). Link: https://lore.kernel.org/r/20220506160820.524344-9-mic@digikod.net Cc: stable@vger.kernel.org Signed-off-by: Mickaël Salaün Signed-off-by: Greg Kroah-Hartman

landlock: Fix landlock_add_rule(2) documentation

2022-06-09T08:23:23+00:00

commit a13e248ff90e81e9322406c0e618cf2168702f4e upstream. It is not mandatory to pass a file descriptor obtained with the O_PATH flag. Also, replace rule's accesses with ruleset's accesses. Link: https://lore.kernel.org/r/20220506160820.524344-2-mic@digikod.net Cc: stable@vger.kernel.org Signed-off-by: Mickaël Salaün Signed-off-by: Greg Kroah-Hartman

landlock: Format with clang-format

2022-06-09T08:23:22+00:00

commit 06a1c40a09a8dded4bf0e7e3ccbda6bddcccd7c8 upstream. Let's follow a consistent and documented coding style. Everything may not be to our liking but it is better than tacit knowledge. Moreover, this will help maintain style consistency between different developers. This contains only whitespace changes. Automatically formatted with: clang-format-14 -i security/landlock/*.[ch] include/uapi/linux/landlock.h Link: https://lore.kernel.org/r/20220506160513.523257-3-mic@digikod.net Cc: stable@vger.kernel.org Signed-off-by: Mickaël Salaün Signed-off-by: Greg Kroah-Hartman

landlock: Use square brackets around "landlock-ruleset"

2022-04-08T12:22:59+00:00

commit aea0b9f2486da8497f35c7114b764bf55e17c7ea upstream. Make the name of the anon inode fd "[landlock-ruleset]" instead of "landlock-ruleset". This is minor but most anon inode fds already carry square brackets around their name: [eventfd] [eventpoll] [fanotify] [fscontext] [io_uring] [pidfd] [signalfd] [timerfd] [userfaultfd] For the sake of consistency lets do the same for the landlock-ruleset anon inode fd that comes with landlock. We did the same in 1cdc415f1083 ("uapi, fsopen: use square brackets around "fscontext" [ver #2]") for the new mount api. Cc: linux-security-module@vger.kernel.org Signed-off-by: Christian Brauner Link: https://lore.kernel.org/r/20211011133704.1704369-1-brauner@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Mickaël Salaün Signed-off-by: Greg Kroah-Hartman

landlock: Enable user space to infer supported features

2021-04-22T19:22:11+00:00

Add a new flag LANDLOCK_CREATE_RULESET_VERSION to landlock_create_ruleset(2). This enables to retreive a Landlock ABI version that is useful to efficiently follow a best-effort security approach. Indeed, it would be a missed opportunity to abort the whole sandbox building, because some features are unavailable, instead of protecting users as much as possible with the subset of features provided by the running kernel. This new flag enables user space to identify the minimum set of Landlock features supported by the running kernel without relying on a filesystem interface (e.g. /proc/version, which might be inaccessible) nor testing multiple syscall argument combinations (i.e. syscall bisection). New Landlock features will be documented and tied to a minimum version number (greater than 1). The current version will be incremented for each new kernel release supporting new Landlock features. User space libraries can leverage this information to seamlessly restrict processes as much as possible while being compatible with newer APIs. This is a much more lighter approach than the previous landlock_get_features(2): the complexity is pushed to user space libraries. This flag meets similar needs as securityfs versions: selinux/policyvers, apparmor/features/*/version* and tomoyo/version. Supporting this flag now will be convenient for backward compatibility. Cc: Arnd Bergmann Cc: James Morris Cc: Jann Horn Cc: Kees Cook Cc: Serge E. Hallyn Signed-off-by: Mickaël Salaün Link: https://lore.kernel.org/r/20210422154123.13086-14-mic@digikod.net Signed-off-by: James Morris

landlock: Add syscall implementations

2021-04-22T19:22:11+00:00

These 3 system calls are designed to be used by unprivileged processes to sandbox themselves: * landlock_create_ruleset(2): Creates a ruleset and returns its file descriptor. * landlock_add_rule(2): Adds a rule (e.g. file hierarchy access) to a ruleset, identified by the dedicated file descriptor. * landlock_restrict_self(2): Enforces a ruleset on the calling thread and its future children (similar to seccomp). This syscall has the same usage restrictions as seccomp(2): the caller must have the no_new_privs attribute set or have CAP_SYS_ADMIN in the current user namespace. All these syscalls have a "flags" argument (not currently used) to enable extensibility. Here are the motivations for these new syscalls: * A sandboxed process may not have access to file systems, including /dev, /sys or /proc, but it should still be able to add more restrictions to itself. * Neither prctl(2) nor seccomp(2) (which was used in a previous version) fit well with the current definition of a Landlock security policy. All passed structs (attributes) are checked at build time to ensure that they don't contain holes and that they are aligned the same way for each architecture. See the user and kernel documentation for more details (provided by a following commit): * Documentation/userspace-api/landlock.rst * Documentation/security/landlock.rst Cc: Arnd Bergmann Cc: James Morris Cc: Jann Horn Cc: Kees Cook Signed-off-by: Mickaël Salaün Acked-by: Serge Hallyn Link: https://lore.kernel.org/r/20210422154123.13086-9-mic@digikod.net Signed-off-by: James Morris