kernel/linux.git/security/landlock/setup.h, branch v6.6.131

landlock: Add the errata interface

2025-04-25T08:45:57+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: Support filesystem access-control

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

Using Landlock objects and ruleset, it is possible to tag inodes according to a process's domain. To enable an unprivileged process to express a file hierarchy, it first needs to open a directory (or a file) and pass this file descriptor to the kernel through landlock_add_rule(2). When checking if a file access request is allowed, we walk from the requested dentry to the real root, following the different mount layers. The access to each "tagged" inodes are collected according to their rule layer level, and ANDed to create access to the requested file hierarchy. This makes possible to identify a lot of files without tagging every inodes nor modifying the filesystem, while still following the view and understanding the user has from the filesystem. Add a new ARCH_EPHEMERAL_INODES for UML because it currently does not keep the same struct inodes for the same inodes whereas these inodes are in use. This commit adds a minimal set of supported filesystem access-control which doesn't enable to restrict all file-related actions. This is the result of multiple discussions to minimize the code of Landlock to ease review. Thanks to the Landlock design, extending this access-control without breaking user space will not be a problem. Moreover, seccomp filters can be used to restrict the use of syscall families which may not be currently handled by Landlock. Cc: Al Viro Cc: Anton Ivanov Cc: James Morris Cc: Jann Horn Cc: Jeff Dike Cc: Kees Cook Cc: Richard Weinberger Cc: Serge E. Hallyn Signed-off-by: Mickaël Salaün Link: https://lore.kernel.org/r/20210422154123.13086-8-mic@digikod.net Signed-off-by: James Morris

landlock: Set up the security framework and manage credentials

2021-04-22T19:22:10+00:00

Process's credentials point to a Landlock domain, which is underneath implemented with a ruleset. In the following commits, this domain is used to check and enforce the ptrace and filesystem security policies. A domain is inherited from a parent to its child the same way a thread inherits a seccomp policy. Cc: James Morris Signed-off-by: Mickaël Salaün Reviewed-by: Jann Horn Acked-by: Serge Hallyn Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/20210422154123.13086-4-mic@digikod.net Signed-off-by: James Morris