seccomp

(This is only valid for Linux).

Kore uses seccomp to filter which system calls its processes can make.

As an application developer you can extend the allow-list to better suit your application its needs.

Adding your own seccomp rules

If you wish to extend the allow-list, you can use the KORE_SECCOMP_FILTER macro. In the example below we allow ioctl(2) and shmat(2) are allowed.

#include <kore/seccomp.h>

KORE_SECCOMP_FILTER("app",
    KORE_SYSCALL_ALLOW(ioctl),
    KORE_SYSCALL_ALLOW(shmat)
);

In another example, we allow write() to stdout but no other file descriptor.

#include <kore/seccomp.h>

KORE_SECCOMP_FILTER("app",
    KORE_SYSCALL_ALLOW_ARG(write, 0, STDOUT_FILENO),
    KORE_SYSCALL_DENY(write, EPERM)
);

Kore provides a few handy macros that can be used in a KORE_SECCOMP_FILTER:

• KORE_SYSCALL_DENY(name, errno)
• KORE_SYSCALL_DENY_ARG(name, argidx, val, errno)
• KORE_SYSCALL_DENY_MASK(name, argidx, val, errno)

• KORE_SYSCALL_DENY_WITH_FLAG(name, argidx, val, errno)

• KORE_SYSCALL_ALLOW(name)

• KORE_SYSCALL_ALLOW_LOG(name)
• KORE_SYSCALL_ALLOW_ARG(name, argidx, val)
• KORE_SYSCALL_ALLOW_MASK(name, argidx, val)
• KORE_SYSCALL_ALLOW_WITH_FLAG(name, argidx, val)