From 3d08cd331c1adcf0d917392f7e527b3f00511748 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Fri, 24 May 2024 06:52:22 +0200 Subject: Merging upstream version 6.8. Signed-off-by: Daniel Baumann --- man/man2/landlock_restrict_self.2 | 116 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 116 insertions(+) create mode 100644 man/man2/landlock_restrict_self.2 (limited to 'man/man2/landlock_restrict_self.2') diff --git a/man/man2/landlock_restrict_self.2 b/man/man2/landlock_restrict_self.2 new file mode 100644 index 0000000..1ac611e --- /dev/null +++ b/man/man2/landlock_restrict_self.2 @@ -0,0 +1,116 @@ +.\" Copyright © 2017-2020 Mickaël Salaün +.\" Copyright © 2019-2020 ANSSI +.\" Copyright © 2021 Microsoft Corporation +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.TH landlock_restrict_self 2 2024-05-02 "Linux man-pages (unreleased)" +.SH NAME +landlock_restrict_self \- enforce a Landlock ruleset +.SH LIBRARY +Standard C library +.RI ( libc ", " \-lc ) +.SH SYNOPSIS +.nf +.BR "#include " " /* Definition of " LANDLOCK_* " constants */" +.BR "#include " " /* Definition of " SYS_* " constants */" +.P +.BI "int syscall(SYS_landlock_restrict_self, int " ruleset_fd , +.BI " uint32_t " flags ); +.SH DESCRIPTION +Once a Landlock ruleset is populated with the desired rules, the +.BR landlock_restrict_self () +system call enables enforcing this ruleset on the calling thread. +See +.BR landlock (7) +for a global overview. +.P +A thread can be restricted with multiple rulesets that are then +composed together to form the thread's Landlock domain. +This can be seen as a stack of rulesets but +it is implemented in a more efficient way. +A domain can only be updated in such a way that +the constraints of each past and future composed rulesets +will restrict the thread and its future children for their entire life. +It is then possible to gradually enforce tailored access control policies +with multiple independent rulesets coming from different sources +(e.g., init system configuration, user session policy, +built-in application policy). +However, most applications should only need one call to +.BR landlock_restrict_self () +and they should avoid arbitrary numbers of such calls because of the +composed rulesets limit. +Instead, developers are encouraged to build a tailored ruleset thanks to +multiple calls to +.BR landlock_add_rule (2). +.P +In order to enforce a ruleset, either the caller must have the +.B CAP_SYS_ADMIN +capability in its user namespace, or the thread must already have the +.I no_new_privs +bit set. +As for +.BR seccomp (2), +this avoids scenarios where unprivileged processes can affect +the behavior of privileged children (e.g., because of set-user-ID binaries). +If that bit was not already set by an ancestor of this thread, +the thread must make the following call: +.IP +.EX +prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0); +.EE +.P +.I ruleset_fd +is a Landlock ruleset file descriptor obtained with +.BR landlock_create_ruleset (2) +and fully populated with a set of calls to +.BR landlock_add_rule (2). +.P +.I flags +must be 0. +.SH RETURN VALUE +On success, +.BR landlock_restrict_self () +returns 0. +.SH ERRORS +.BR landlock_restrict_self () +can fail for the following reasons: +.TP +.B EOPNOTSUPP +Landlock is supported by the kernel but disabled at boot time. +.TP +.B EINVAL +.I flags +is not 0. +.TP +.B EBADF +.I ruleset_fd +is not a file descriptor for the current thread. +.TP +.B EBADFD +.I ruleset_fd +is not a ruleset file descriptor. +.TP +.B EPERM +.I ruleset_fd +has no read access to the underlying ruleset, +or the calling thread is not running with +.IR no_new_privs , +or it doesn't have the +.B CAP_SYS_ADMIN +in its user namespace. +.TP +.B E2BIG +The maximum number of composed rulesets is reached for the calling thread. +This limit is currently 64. +.SH STANDARDS +Linux. +.SH HISTORY +Linux 5.13. +.SH EXAMPLES +See +.BR landlock (7). +.SH SEE ALSO +.BR landlock_create_ruleset (2), +.BR landlock_add_rule (2), +.BR landlock (7) -- cgit v1.2.3