CVE-2024-42318

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

landlock: Don't lose track of restrictions on cred_transfer

When a process' cred struct is replaced, this _almost_ always invokes

the cred_prepare LSM hook; but in one special case (when

KEYCTL_SESSION_TO_PARENT updates the parent's credentials), the

cred_transfer LSM hook is used instead. Landlock only implements the

cred_prepare hook, not cred_transfer, so KEYCTL_SESSION_TO_PARENT causes

all information on Landlock restrictions to be lost.

This basically means that a process with the ability to use the fork()

and keyctl() syscalls can get rid of all Landlock restrictions on

itself.

Fix it by adding a cred_transfer hook that does the same thing as the

existing cred_prepare hook. (Implemented by having hook_cred_prepare()

call hook_cred_transfer() so that the two functions are less likely to

accidentally diverge in the future.)

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References