diff --git a/lib/libc/sys/cap_enter.2 b/lib/libc/sys/cap_enter.2 index 7051a96266b9..428e0b0bcd09 100644 --- a/lib/libc/sys/cap_enter.2 +++ b/lib/libc/sys/cap_enter.2 @@ -1,164 +1,164 @@ .\" .\" Copyright (c) 2008-2009 Robert N. M. Watson .\" All rights reserved. .\" .\" This software was developed at the University of Cambridge Computer .\" Laboratory with support from a grant from Google, Inc. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" $FreeBSD$ .\" .Dd May 5, 2020 .Dt CAP_ENTER 2 .Os .Sh NAME .Nm cap_enter , .Nm cap_getmode .Nd Capability mode system calls .Sh LIBRARY .Lb libc .Sh SYNOPSIS .In sys/capsicum.h .Ft int .Fn cap_enter "void" .Ft int .Fn cap_getmode "u_int *modep" .Sh DESCRIPTION .Fn cap_enter places the current process into capability mode, a mode of execution in which processes may only issue system calls operating on file descriptors or reading limited global system state. Access to global name spaces, such as file system or IPC name spaces, is prevented. If the process is already in a capability mode sandbox, the system call is a no-op. Future process descendants created with .Xr fork 2 or .Xr pdfork 2 will be placed in capability mode from inception. .Pp When combined with .Xr cap_rights_limit 2 , .Xr cap_ioctls_limit 2 , .Xr cap_fcntls_limit 2 , .Fn cap_enter may be used to create kernel-enforced sandboxes in which appropriately-crafted applications or application components may be run. .Pp .Fn cap_getmode returns a flag indicating whether or not the process is in a capability mode sandbox. .Sh RUN-TIME SETTINGS If the .Dv kern.trap_enotcap sysctl MIB is set to a non-zero value, then for any process executing in a capability mode sandbox, any syscall which results in either an .Er ENOTCAPABLE or .Er ECAPMODE error also generates the synchronous .Dv SIGTRAP signal to the thread on the syscall return. On signal delivery, the .Va si_errno member of the .Fa siginfo signal handler parameter is set to the syscall error value, and the .Va si_code member is set to .Dv TRAP_CAP . .Pp See also the .Dv PROC_TRAPCAP_CTL and .Dv PROC_TRAPCAP_STATUS operations of the .Xr procctl 2 function for similar per-process functionality. -.Sh CAVEAT -Creating effective process sandboxes is a tricky process that involves -identifying the least possible rights required by the process and then -passing those rights into the process in a safe manner. -Consumers of -.Fn cap_enter -should also be aware of other inherited rights, such as access to VM -resources, memory contents, and other process properties that should be -considered. -It is advisable to use -.Xr fexecve 2 -to create a runtime environment inside the sandbox that has as few implicitly -acquired rights as possible. .Sh RETURN VALUES .Rv -std cap_enter cap_getmode .Pp When the process is in capability mode, .Fn cap_getmode sets the flag to a non-zero value. A zero value means the process is not in capability mode. .Sh ERRORS The .Fn cap_enter and .Fn cap_getmode system calls will fail if: .Bl -tag -width Er .It Bq Er ENOSYS The kernel is compiled without: .Pp .Cd "options CAPABILITY_MODE" .El .Pp The .Fn cap_getmode system call may also return the following error: .Bl -tag -width Er .It Bq Er EFAULT Pointer .Fa modep points outside the process's allocated address space. .El .Sh SEE ALSO .Xr cap_fcntls_limit 2 , .Xr cap_ioctls_limit 2 , .Xr cap_rights_limit 2 , .Xr fexecve 2 , .Xr procctl 2 , .Xr cap_sandboxed 3 , .Xr capsicum 4 , .Xr sysctl 9 .Sh HISTORY The .Fn cap_getmode system call first appeared in .Fx 8.3 . Support for capabilities and capabilities mode was developed as part of the .Tn TrustedBSD Project. .Sh AUTHORS These functions and the capability facility were created by .An "Robert N. M. Watson" at the University of Cambridge Computer Laboratory with support from a grant from Google, Inc. +.Sh CAVEATS +Creating effective process sandboxes is a tricky process that involves +identifying the least possible rights required by the process and then +passing those rights into the process in a safe manner. +Consumers of +.Fn cap_enter +should also be aware of other inherited rights, such as access to VM +resources, memory contents, and other process properties that should be +considered. +It is advisable to use +.Xr fexecve 2 +to create a runtime environment inside the sandbox that has as few implicitly +acquired rights as possible.