CVE-2024-42318

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> landlock: Don&amp;#39;t lose track of restrictions on cred_transfer<br /> <br /> When a process&amp;#39; cred struct is replaced, this _almost_ always invokes<br /> the cred_prepare LSM hook; but in one special case (when<br /> KEYCTL_SESSION_TO_PARENT updates the parent&amp;#39;s credentials), the<br /> cred_transfer LSM hook is used instead. Landlock only implements the<br /> cred_prepare hook, not cred_transfer, so KEYCTL_SESSION_TO_PARENT causes<br /> all information on Landlock restrictions to be lost.<br /> <br /> This basically means that a process with the ability to use the fork()<br /> and keyctl() syscalls can get rid of all Landlock restrictions on<br /> itself.<br /> <br /> Fix it by adding a cred_transfer hook that does the same thing as the<br /> existing cred_prepare hook. (Implemented by having hook_cred_prepare()<br /> call hook_cred_transfer() so that the two functions are less likely to<br /> accidentally diverge in the future.)