NAME

landlock_create_ruleset - create a new Landlock ruleset

LIBRARY

Standard C library (libc, -lc)

SYNOPSIS

#include <linux/landlock.h>  /* Definition of LANDLOCK_* constants */
#include <sys/syscall.h>     /* Definition of SYS_* constants */

int syscall(SYS_landlock_create_ruleset,
            const struct landlock_ruleset_attr *attr,
            size_t size , uint32_t flags);

DESCRIPTION

A Landlock ruleset identifies a set of rules (i.e., actions on objects). This landlock_create_ruleset() system call enables creating a new file descriptor identifying a ruleset. This file descriptor can then be used by landlock_add_rule(2) and landlock_restrict_self(2). See landlock(7) for a global overview.

attr specifies the properties of the new ruleset. It points to the following structure:

struct landlock_ruleset_attr {
    __u64 handled_access_fs;
};

handled_access_fs is a bitmask of actions that is handled by this ruleset and should then be forbidden if no rule explicitly allows them (see Filesystem actions in landlock(7)). This enables simply restricting ambient rights (e.g., global filesystem access) and is needed for compatibility reasons.

size must be specified as sizeof(struct landlock_ruleset_attr) for compatibility reasons.

flags must be 0 if attr is used. Otherwise, flags can be set to:

LANDLOCK_CREATE_RULESET_VERSION: If attr is NULL and size is 0, then the returned value is the highest supported Landlock ABI version (starting at 1). This version can be used for a best-effort security approach, which is encouraged when user space is not pinned to a specific kernel version. All features documented in these man pages are available with the version 1.

RETURN VALUE

On success, landlock_create_ruleset() returns a new Landlock ruleset file descriptor, or a Landlock ABI version, according to flags.

ERRORS

landlock_create_ruleset() can fail for the following reasons:

EOPNOTSUPP: Landlock is supported by the kernel but disabled at boot time.
EINVAL: Unknown flags, or unknown access, or too small size.
E2BIG: size is too big.
EFAULT: attr was not a valid address.
ENOMSG: Empty accesses (i.e., attr->handled_access_fs is 0).

STANDARDS

Linux.

HISTORY

Linux 5.13.

EXAMPLES

See landlock(7).