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.TH landlock_create_ruleset 2 2023-03-30 "Linux man-pages 6.04"
.SH NAME
landlock_create_ruleset \- create a new Landlock ruleset
.SH LIBRARY
Standard C library
.RI ( libc ", " \-lc )
.SH SYNOPSIS
.nf
.BR "#include <linux/landlock.h>" "  /* Definition of " LANDLOCK_* " constants */"
.BR "#include <sys/syscall.h>" "     /* Definition of " SYS_* " constants */"
.PP
.B int syscall(SYS_landlock_create_ruleset,
.BI "            const struct landlock_ruleset_attr *" attr ,
.BI "            size_t " size " , uint32_t " flags );
.fi
.SH DESCRIPTION
A Landlock ruleset identifies a set of rules (i.e., actions on objects).
This
.BR landlock_create_ruleset ()
system call enables creating a new file descriptor identifying a ruleset.
This file descriptor can then be used by
.BR landlock_add_rule (2)
and
.BR landlock_restrict_self (2).
See
.BR landlock (7)
for a global overview.
.PP
.I attr
specifies the properties of the new ruleset.
It points to the following structure:
.IP
.in +4n
.EX
struct landlock_ruleset_attr {
    __u64 handled_access_fs;
};
.EE
.in
.IP
.I 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
.B Filesystem actions
in
.BR landlock (7)).
This enables simply restricting ambient rights
(e.g., global filesystem access) and is needed for compatibility reasons.
.PP
.I size
must be specified as
.I sizeof(struct landlock_ruleset_attr)
for compatibility reasons.
.PP
.I flags
must be 0 if
.I attr
is used.
Otherwise,
.I flags
can be set to:
.TP
.B LANDLOCK_CREATE_RULESET_VERSION
If
.I attr
is NULL and
.I 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.
.SH RETURN VALUE
On success,
.BR landlock_create_ruleset ()
returns a new Landlock ruleset file descriptor,
or a Landlock ABI version,
according to
.IR flags .
.SH ERRORS
.BR landlock_create_ruleset ()
can fail for the following reasons:
.TP
.B EOPNOTSUPP
Landlock is supported by the kernel but disabled at boot time.
.TP
.B EINVAL
Unknown
.IR flags ,
or unknown access, or too small
.IR size .
.TP
.B E2BIG
.I size
is too big.
.TP
.B EFAULT
.I attr
was not a valid address.
.TP
.B ENOMSG
Empty accesses (i.e.,
.I attr\->handled_access_fs
is 0).
.SH STANDARDS
Linux.
.SH HISTORY
Linux 5.13.
.SH EXAMPLES
See
.BR landlock (7).
.SH SEE ALSO
.BR landlock_add_rule (2),
.BR landlock_restrict_self (2),
.BR landlock (7)