Add initial support for Capsicum's Capability Mode to the FreeBSD kernel,
compiled conditionally on options CAPABILITIES: Add a new credential flag, CRED_FLAG_CAPMODE, which indicates that a subject (typically a process) is in capability mode. Add two new system calls, cap_enter(2) and cap_getmode(2), which allow setting and querying (but never clearing) the flag. Export the capability mode flag via process information sysctls. Sponsored by: Google, Inc. Reviewed by: anderson Discussed with: benl, kris, pjd Obtained from: Capsicum Project MFC after: 3 months
This commit is contained in:
Robert Watson
parent
25122f5c5f
commit
96fcc75fdf
@ -952,8 +952,8 @@
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513 AUE_LPATHCONF NOPROTO { int lpathconf(char *path, int name); }
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514 AUE_CAP_NEW UNIMPL cap_new
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515 AUE_CAP_GETRIGHTS UNIMPL cap_getrights
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516 AUE_CAP_ENTER UNIMPL cap_enter
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517 AUE_CAP_GETMODE UNIMPL cap_getmode
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516 AUE_CAP_ENTER NOPROTO { int cap_enter(void); }
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517 AUE_CAP_GETMODE NOPROTO { int cap_getmode(u_int *modep); }
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518 AUE_PDFORK UNIMPL pdfork
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519 AUE_PDKILL UNIMPL pdkill
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520 AUE_PDGETPID UNIMPL pdgetpid
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@ -1157,6 +1157,9 @@ options MAC_SEEOTHERUIDS
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options MAC_STUB
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options MAC_TEST
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# Support for Capsicum
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options CAPABILIITES
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#####################################################################
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# CLOCK OPTIONS
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@ -63,6 +63,7 @@ SYSCTL_DEBUG opt_sysctl.h
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ADAPTIVE_LOCKMGRS
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ALQ
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AUDIT opt_global.h
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CAPABILITIES opt_capabilities.h
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CODA_COMPAT_5 opt_coda.h
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COMPAT_43 opt_compat.h
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COMPAT_43TTY opt_compat.h
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@ -725,7 +725,9 @@ fill_kinfo_proc_only(struct proc *p, struct kinfo_proc *kp)
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kp->ki_uid = cred->cr_uid;
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kp->ki_ruid = cred->cr_ruid;
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kp->ki_svuid = cred->cr_svuid;
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kp->ki_cr_flags = cred->cr_flags;
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kp->ki_cr_flags = 0;
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if (cred->cr_flags & CRED_FLAG_CAPMODE)
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kp->ki_cr_flags |= KI_CRF_CAPABILITY_MODE;
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/* XXX bde doesn't like KI_NGROUPS */
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if (cred->cr_ngroups > KI_NGROUPS) {
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kp->ki_ngroups = KI_NGROUPS;
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123
sys/kern/sys_capability.c
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123
sys/kern/sys_capability.c
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@ -0,0 +1,123 @@
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/*-
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* Copyright (c) 2008-2011 Robert N. M. Watson
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* Copyright (c) 2010-2011 Jonathan Anderson
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* All rights reserved.
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*
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* This software was developed at the University of Cambridge Computer
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* Laboratory with support from a grant from Google, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* FreeBSD kernel capability facility.
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*
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* Currently, this file implements only capability mode; capabilities
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* (rights-refined file descriptors) will follow.
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*
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*/
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#include "opt_capabilities.h"
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/capability.h>
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#include <sys/file.h>
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#include <sys/filedesc.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/proc.h>
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#include <sys/sysproto.h>
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#include <sys/sysctl.h>
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#include <sys/systm.h>
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#include <sys/ucred.h>
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#include <security/audit/audit.h>
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#include <vm/uma.h>
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#include <vm/vm.h>
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#ifdef CAPABILITIES
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/*
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* We don't currently have any MIB entries for sysctls, but we do expose
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* security.capabilities so that it's easy to tell if options CAPABILITIES is
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* compiled into the kernel.
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*/
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SYSCTL_NODE(_security, OID_AUTO, capabilities, CTLFLAG_RW, 0, "Capsicum");
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/*
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* System call to enter capability mode for the process.
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*/
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int
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cap_enter(struct thread *td, struct cap_enter_args *uap)
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{
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struct ucred *newcred, *oldcred;
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struct proc *p;
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if (IN_CAPABILITY_MODE(td))
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return (0);
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newcred = crget();
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p = td->td_proc;
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PROC_LOCK(p);
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oldcred = p->p_ucred;
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crcopy(newcred, oldcred);
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newcred->cr_flags |= CRED_FLAG_CAPMODE;
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p->p_ucred = newcred;
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PROC_UNLOCK(p);
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crfree(oldcred);
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return (0);
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}
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/*
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* System call to query whether the process is in capability mode.
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*/
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int
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cap_getmode(struct thread *td, struct cap_getmode_args *uap)
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{
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u_int i;
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i = (IN_CAPABILITY_MODE(td)) ? 1 : 0;
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return (copyout(&i, uap->modep, sizeof(i)));
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}
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#else /* !CAPABILITIES */
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int
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cap_enter(struct thread *td, struct cap_enter_args *uap)
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{
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return (ENOSYS);
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}
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int
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cap_getmode(struct thread *td, struct cap_getmode_args *uap)
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{
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return (ENOSYS);
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}
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#endif /* CAPABILITIES */
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@ -916,8 +916,8 @@
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513 AUE_LPATHCONF STD { int lpathconf(char *path, int name); }
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514 AUE_CAP_NEW UNIMPL cap_new
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515 AUE_CAP_GETRIGHTS UNIMPL cap_getrights
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516 AUE_CAP_ENTER UNIMPL cap_enter
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517 AUE_CAP_GETMODE UNIMPL cap_getmode
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516 AUE_CAP_ENTER STD { int cap_enter(void); }
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517 AUE_CAP_GETMODE STD { int cap_getmode(u_int *modep); }
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518 AUE_PDFORK UNIMPL pdfork
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519 AUE_PDKILL UNIMPL pdkill
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520 AUE_PDGETPID UNIMPL pdgetpid
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@ -69,6 +69,11 @@ struct ucred {
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#define XU_NGROUPS 16
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/*
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* Flags for cr_flags.
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*/
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#define CRED_FLAG_CAPMODE 0x00000001 /* In capability mode. */
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/*
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* This is the external representation of struct ucred.
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*/
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@ -101,9 +101,11 @@
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#define KI_NGROUPS 16 /* number of groups in ki_groups */
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#define LOGNAMELEN 17 /* size of returned ki_login */
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/* Flags for the process credential. */
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#define KI_CRF_CAPABILITY_MODE 0x00000001
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/*
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* Steal a bit from ki_cr_flags (cr_flags is never used) to indicate
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* that the cred had more than KI_NGROUPS groups.
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* Steal a bit from ki_cr_flags to indicate that the cred had more than
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* KI_NGROUPS groups.
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*/
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#define KI_CRF_GRP_OVERFLOW 0x80000000
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