/* * Copyright (c) 1982, 1986, 1989, 1990, 1991, 1993 * The Regents of the University of California. All rights reserved. * (c) UNIX System Laboratories, Inc. * All or some portions of this file are derived from material licensed * to the University of California by American Telephone and Telegraph * Co. or Unix System Laboratories, Inc. and are reproduced herein with * the permission of UNIX System Laboratories, Inc. * Copyright (c) 2000-2001 Robert N. M. Watson. All rights reserved. * * 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. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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. * * @(#)kern_prot.c 8.6 (Berkeley) 1/21/94 * $FreeBSD$ */ /* * System calls related to processes and protection */ #include "opt_compat.h" #include "opt_mac.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include static MALLOC_DEFINE(M_CRED, "cred", "credentials"); SYSCTL_DECL(_security); SYSCTL_NODE(_security, OID_AUTO, bsd, CTLFLAG_RW, 0, "BSD security policy"); #ifndef _SYS_SYSPROTO_H_ struct getpid_args { int dummy; }; #endif /* * MPSAFE */ /* ARGSUSED */ int getpid(struct thread *td, struct getpid_args *uap) { struct proc *p = td->td_proc; td->td_retval[0] = p->p_pid; #if defined(COMPAT_43) || defined(COMPAT_SUNOS) PROC_LOCK(p); td->td_retval[1] = p->p_pptr->p_pid; PROC_UNLOCK(p); #endif return (0); } #ifndef _SYS_SYSPROTO_H_ struct getppid_args { int dummy; }; #endif /* * MPSAFE */ /* ARGSUSED */ int getppid(struct thread *td, struct getppid_args *uap) { struct proc *p = td->td_proc; PROC_LOCK(p); td->td_retval[0] = p->p_pptr->p_pid; PROC_UNLOCK(p); return (0); } /* * Get process group ID; note that POSIX getpgrp takes no parameter. */ #ifndef _SYS_SYSPROTO_H_ struct getpgrp_args { int dummy; }; #endif /* * MPSAFE */ int getpgrp(struct thread *td, struct getpgrp_args *uap) { struct proc *p = td->td_proc; PROC_LOCK(p); td->td_retval[0] = p->p_pgrp->pg_id; PROC_UNLOCK(p); return (0); } /* Get an arbitary pid's process group id */ #ifndef _SYS_SYSPROTO_H_ struct getpgid_args { pid_t pid; }; #endif /* * MPSAFE */ int getpgid(struct thread *td, struct getpgid_args *uap) { struct proc *p; int error; if (uap->pid == 0) { p = td->td_proc; PROC_LOCK(p); } else { p = pfind(uap->pid); if (p == NULL) return (ESRCH); error = p_cansee(td, p); if (error) { PROC_UNLOCK(p); return (error); } } td->td_retval[0] = p->p_pgrp->pg_id; PROC_UNLOCK(p); return (0); } /* * Get an arbitary pid's session id. */ #ifndef _SYS_SYSPROTO_H_ struct getsid_args { pid_t pid; }; #endif /* * MPSAFE */ int getsid(struct thread *td, struct getsid_args *uap) { struct proc *p; int error; if (uap->pid == 0) { p = td->td_proc; PROC_LOCK(p); } else { p = pfind(uap->pid); if (p == NULL) return (ESRCH); error = p_cansee(td, p); if (error) { PROC_UNLOCK(p); return (error); } } td->td_retval[0] = p->p_session->s_sid; PROC_UNLOCK(p); return (0); } #ifndef _SYS_SYSPROTO_H_ struct getuid_args { int dummy; }; #endif /* * MPSAFE */ /* ARGSUSED */ int getuid(struct thread *td, struct getuid_args *uap) { td->td_retval[0] = td->td_ucred->cr_ruid; #if defined(COMPAT_43) || defined(COMPAT_SUNOS) td->td_retval[1] = td->td_ucred->cr_uid; #endif return (0); } #ifndef _SYS_SYSPROTO_H_ struct geteuid_args { int dummy; }; #endif /* * MPSAFE */ /* ARGSUSED */ int geteuid(struct thread *td, struct geteuid_args *uap) { td->td_retval[0] = td->td_ucred->cr_uid; return (0); } #ifndef _SYS_SYSPROTO_H_ struct getgid_args { int dummy; }; #endif /* * MPSAFE */ /* ARGSUSED */ int getgid(struct thread *td, struct getgid_args *uap) { td->td_retval[0] = td->td_ucred->cr_rgid; #if defined(COMPAT_43) || defined(COMPAT_SUNOS) td->td_retval[1] = td->td_ucred->cr_groups[0]; #endif return (0); } /* * Get effective group ID. The "egid" is groups[0], and could be obtained * via getgroups. This syscall exists because it is somewhat painful to do * correctly in a library function. */ #ifndef _SYS_SYSPROTO_H_ struct getegid_args { int dummy; }; #endif /* * MPSAFE */ /* ARGSUSED */ int getegid(struct thread *td, struct getegid_args *uap) { td->td_retval[0] = td->td_ucred->cr_groups[0]; return (0); } #ifndef _SYS_SYSPROTO_H_ struct getgroups_args { u_int gidsetsize; gid_t *gidset; }; #endif /* * MPSAFE */ int getgroups(struct thread *td, register struct getgroups_args *uap) { struct ucred *cred; u_int ngrp; int error; cred = td->td_ucred; if ((ngrp = uap->gidsetsize) == 0) { td->td_retval[0] = cred->cr_ngroups; return (0); } if (ngrp < cred->cr_ngroups) return (EINVAL); ngrp = cred->cr_ngroups; error = copyout(cred->cr_groups, uap->gidset, ngrp * sizeof(gid_t)); if (error == 0) td->td_retval[0] = ngrp; return (error); } #ifndef _SYS_SYSPROTO_H_ struct setsid_args { int dummy; }; #endif /* * MPSAFE */ /* ARGSUSED */ int setsid(register struct thread *td, struct setsid_args *uap) { struct pgrp *pgrp; int error; struct proc *p = td->td_proc; struct pgrp *newpgrp; struct session *newsess; error = 0; pgrp = NULL; MALLOC(newpgrp, struct pgrp *, sizeof(struct pgrp), M_PGRP, M_WAITOK | M_ZERO); MALLOC(newsess, struct session *, sizeof(struct session), M_SESSION, M_WAITOK | M_ZERO); sx_xlock(&proctree_lock); if (p->p_pgid == p->p_pid || (pgrp = pgfind(p->p_pid)) != NULL) { if (pgrp != NULL) PGRP_UNLOCK(pgrp); error = EPERM; } else { (void)enterpgrp(p, p->p_pid, newpgrp, newsess); td->td_retval[0] = p->p_pid; newpgrp = NULL; newsess = NULL; } sx_xunlock(&proctree_lock); if (newpgrp != NULL) FREE(newpgrp, M_PGRP); if (newsess != NULL) FREE(newsess, M_SESSION); return (error); } /* * set process group (setpgid/old setpgrp) * * caller does setpgid(targpid, targpgid) * * pid must be caller or child of caller (ESRCH) * if a child * pid must be in same session (EPERM) * pid can't have done an exec (EACCES) * if pgid != pid * there must exist some pid in same session having pgid (EPERM) * pid must not be session leader (EPERM) */ #ifndef _SYS_SYSPROTO_H_ struct setpgid_args { int pid; /* target process id */ int pgid; /* target pgrp id */ }; #endif /* * MPSAFE */ /* ARGSUSED */ int setpgid(struct thread *td, register struct setpgid_args *uap) { struct proc *curp = td->td_proc; register struct proc *targp; /* target process */ register struct pgrp *pgrp; /* target pgrp */ int error; struct pgrp *newpgrp; if (uap->pgid < 0) return (EINVAL); error = 0; MALLOC(newpgrp, struct pgrp *, sizeof(struct pgrp), M_PGRP, M_WAITOK | M_ZERO); sx_xlock(&proctree_lock); if (uap->pid != 0 && uap->pid != curp->p_pid) { if ((targp = pfind(uap->pid)) == NULL) { if (targp) PROC_UNLOCK(targp); error = ESRCH; goto done; } if (!inferior(targp)) { PROC_UNLOCK(targp); error = ESRCH; goto done; } if ((error = p_cansee(curthread, targp))) { PROC_UNLOCK(targp); goto done; } if (targp->p_pgrp == NULL || targp->p_session != curp->p_session) { PROC_UNLOCK(targp); error = EPERM; goto done; } if (targp->p_flag & P_EXEC) { PROC_UNLOCK(targp); error = EACCES; goto done; } PROC_UNLOCK(targp); } else targp = curp; if (SESS_LEADER(targp)) { error = EPERM; goto done; } if (uap->pgid == 0) uap->pgid = targp->p_pid; if (uap->pgid == targp->p_pid) { if (targp->p_pgid == uap->pgid) goto done; error = enterpgrp(targp, uap->pgid, newpgrp, NULL); if (error == 0) newpgrp = NULL; } else { if ((pgrp = pgfind(uap->pgid)) == NULL || pgrp->pg_session != curp->p_session) { if (pgrp != NULL) PGRP_UNLOCK(pgrp); error = EPERM; goto done; } if (pgrp == targp->p_pgrp) { PGRP_UNLOCK(pgrp); goto done; } PGRP_UNLOCK(pgrp); error = enterthispgrp(targp, pgrp); } done: sx_xunlock(&proctree_lock); KASSERT((error == 0) || (newpgrp != NULL), ("setpgid failed and newpgrp is NULL")); if (newpgrp != NULL) FREE(newpgrp, M_PGRP); return (error); } /* * Use the clause in B.4.2.2 that allows setuid/setgid to be 4.2/4.3BSD * compatible. It says that setting the uid/gid to euid/egid is a special * case of "appropriate privilege". Once the rules are expanded out, this * basically means that setuid(nnn) sets all three id's, in all permitted * cases unless _POSIX_SAVED_IDS is enabled. In that case, setuid(getuid()) * does not set the saved id - this is dangerous for traditional BSD * programs. For this reason, we *really* do not want to set * _POSIX_SAVED_IDS and do not want to clear POSIX_APPENDIX_B_4_2_2. */ #define POSIX_APPENDIX_B_4_2_2 #ifndef _SYS_SYSPROTO_H_ struct setuid_args { uid_t uid; }; #endif /* * MPSAFE */ /* ARGSUSED */ int setuid(struct thread *td, struct setuid_args *uap) { struct proc *p = td->td_proc; struct ucred *newcred, *oldcred; uid_t uid; struct uidinfo *uip; int error; uid = uap->uid; newcred = crget(); uip = uifind(uid); PROC_LOCK(p); oldcred = p->p_ucred; /* * See if we have "permission" by POSIX 1003.1 rules. * * Note that setuid(geteuid()) is a special case of * "appropriate privileges" in appendix B.4.2.2. We need * to use this clause to be compatible with traditional BSD * semantics. Basically, it means that "setuid(xx)" sets all * three id's (assuming you have privs). * * Notes on the logic. We do things in three steps. * 1: We determine if the euid is going to change, and do EPERM * right away. We unconditionally change the euid later if this * test is satisfied, simplifying that part of the logic. * 2: We determine if the real and/or saved uids are going to * change. Determined by compile options. * 3: Change euid last. (after tests in #2 for "appropriate privs") */ if (uid != oldcred->cr_ruid && /* allow setuid(getuid()) */ #ifdef _POSIX_SAVED_IDS uid != oldcred->cr_svuid && /* allow setuid(saved gid) */ #endif #ifdef POSIX_APPENDIX_B_4_2_2 /* Use BSD-compat clause from B.4.2.2 */ uid != oldcred->cr_uid && /* allow setuid(geteuid()) */ #endif (error = suser_cred(oldcred, PRISON_ROOT)) != 0) { PROC_UNLOCK(p); uifree(uip); crfree(newcred); return (error); } /* * Copy credentials so other references do not see our changes. */ crcopy(newcred, oldcred); #ifdef _POSIX_SAVED_IDS /* * Do we have "appropriate privileges" (are we root or uid == euid) * If so, we are changing the real uid and/or saved uid. */ if ( #ifdef POSIX_APPENDIX_B_4_2_2 /* Use the clause from B.4.2.2 */ uid == oldcred->cr_uid || #endif suser_cred(oldcred, PRISON_ROOT) == 0) /* we are using privs */ #endif { /* * Set the real uid and transfer proc count to new user. */ if (uid != oldcred->cr_ruid) { change_ruid(newcred, uip); setsugid(p); } /* * Set saved uid * * XXX always set saved uid even if not _POSIX_SAVED_IDS, as * the security of seteuid() depends on it. B.4.2.2 says it * is important that we should do this. */ if (uid != oldcred->cr_svuid) { change_svuid(newcred, uid); setsugid(p); } } /* * In all permitted cases, we are changing the euid. */ if (uid != oldcred->cr_uid) { change_euid(newcred, uip); setsugid(p); } p->p_ucred = newcred; PROC_UNLOCK(p); uifree(uip); crfree(oldcred); return (0); } #ifndef _SYS_SYSPROTO_H_ struct seteuid_args { uid_t euid; }; #endif /* * MPSAFE */ /* ARGSUSED */ int seteuid(struct thread *td, struct seteuid_args *uap) { struct proc *p = td->td_proc; struct ucred *newcred, *oldcred; uid_t euid; struct uidinfo *euip; int error; euid = uap->euid; newcred = crget(); euip = uifind(euid); PROC_LOCK(p); oldcred = p->p_ucred; if (euid != oldcred->cr_ruid && /* allow seteuid(getuid()) */ euid != oldcred->cr_svuid && /* allow seteuid(saved uid) */ (error = suser_cred(oldcred, PRISON_ROOT)) != 0) { PROC_UNLOCK(p); uifree(euip); crfree(newcred); return (error); } /* * Everything's okay, do it. Copy credentials so other references do * not see our changes. */ crcopy(newcred, oldcred); if (oldcred->cr_uid != euid) { change_euid(newcred, euip); setsugid(p); } p->p_ucred = newcred; PROC_UNLOCK(p); uifree(euip); crfree(oldcred); return (0); } #ifndef _SYS_SYSPROTO_H_ struct setgid_args { gid_t gid; }; #endif /* * MPSAFE */ /* ARGSUSED */ int setgid(struct thread *td, struct setgid_args *uap) { struct proc *p = td->td_proc; struct ucred *newcred, *oldcred; gid_t gid; int error; gid = uap->gid; newcred = crget(); PROC_LOCK(p); oldcred = p->p_ucred; /* * See if we have "permission" by POSIX 1003.1 rules. * * Note that setgid(getegid()) is a special case of * "appropriate privileges" in appendix B.4.2.2. We need * to use this clause to be compatible with traditional BSD * semantics. Basically, it means that "setgid(xx)" sets all * three id's (assuming you have privs). * * For notes on the logic here, see setuid() above. */ if (gid != oldcred->cr_rgid && /* allow setgid(getgid()) */ #ifdef _POSIX_SAVED_IDS gid != oldcred->cr_svgid && /* allow setgid(saved gid) */ #endif #ifdef POSIX_APPENDIX_B_4_2_2 /* Use BSD-compat clause from B.4.2.2 */ gid != oldcred->cr_groups[0] && /* allow setgid(getegid()) */ #endif (error = suser_cred(oldcred, PRISON_ROOT)) != 0) { PROC_UNLOCK(p); crfree(newcred); return (error); } crcopy(newcred, oldcred); #ifdef _POSIX_SAVED_IDS /* * Do we have "appropriate privileges" (are we root or gid == egid) * If so, we are changing the real uid and saved gid. */ if ( #ifdef POSIX_APPENDIX_B_4_2_2 /* use the clause from B.4.2.2 */ gid == oldcred->cr_groups[0] || #endif suser_cred(oldcred, PRISON_ROOT) == 0) /* we are using privs */ #endif { /* * Set real gid */ if (oldcred->cr_rgid != gid) { change_rgid(newcred, gid); setsugid(p); } /* * Set saved gid * * XXX always set saved gid even if not _POSIX_SAVED_IDS, as * the security of setegid() depends on it. B.4.2.2 says it * is important that we should do this. */ if (oldcred->cr_svgid != gid) { change_svgid(newcred, gid); setsugid(p); } } /* * In all cases permitted cases, we are changing the egid. * Copy credentials so other references do not see our changes. */ if (oldcred->cr_groups[0] != gid) { change_egid(newcred, gid); setsugid(p); } p->p_ucred = newcred; PROC_UNLOCK(p); crfree(oldcred); return (0); } #ifndef _SYS_SYSPROTO_H_ struct setegid_args { gid_t egid; }; #endif /* * MPSAFE */ /* ARGSUSED */ int setegid(struct thread *td, struct setegid_args *uap) { struct proc *p = td->td_proc; struct ucred *newcred, *oldcred; gid_t egid; int error; egid = uap->egid; newcred = crget(); PROC_LOCK(p); oldcred = p->p_ucred; if (egid != oldcred->cr_rgid && /* allow setegid(getgid()) */ egid != oldcred->cr_svgid && /* allow setegid(saved gid) */ (error = suser_cred(oldcred, PRISON_ROOT)) != 0) { PROC_UNLOCK(p); crfree(newcred); return (error); } crcopy(newcred, oldcred); if (oldcred->cr_groups[0] != egid) { change_egid(newcred, egid); setsugid(p); } p->p_ucred = newcred; PROC_UNLOCK(p); crfree(oldcred); return (0); } #ifndef _SYS_SYSPROTO_H_ struct setgroups_args { u_int gidsetsize; gid_t *gidset; }; #endif /* * MPSAFE */ /* ARGSUSED */ int setgroups(struct thread *td, struct setgroups_args *uap) { struct proc *p = td->td_proc; struct ucred *newcred, *tempcred, *oldcred; u_int ngrp; int error; ngrp = uap->gidsetsize; if (ngrp > NGROUPS) return (EINVAL); tempcred = crget(); error = copyin(uap->gidset, tempcred->cr_groups, ngrp * sizeof(gid_t)); if (error != 0) { crfree(tempcred); return (error); } newcred = crget(); PROC_LOCK(p); oldcred = p->p_ucred; error = suser_cred(oldcred, PRISON_ROOT); if (error) { PROC_UNLOCK(p); crfree(newcred); crfree(tempcred); return (error); } /* * XXX A little bit lazy here. We could test if anything has * changed before crcopy() and setting P_SUGID. */ crcopy(newcred, oldcred); if (ngrp < 1) { /* * setgroups(0, NULL) is a legitimate way of clearing the * groups vector on non-BSD systems (which generally do not * have the egid in the groups[0]). We risk security holes * when running non-BSD software if we do not do the same. */ newcred->cr_ngroups = 1; } else { bcopy(tempcred->cr_groups, newcred->cr_groups, ngrp * sizeof(gid_t)); newcred->cr_ngroups = ngrp; } setsugid(p); p->p_ucred = newcred; PROC_UNLOCK(p); crfree(tempcred); crfree(oldcred); return (0); } #ifndef _SYS_SYSPROTO_H_ struct setreuid_args { uid_t ruid; uid_t euid; }; #endif /* * MPSAFE */ /* ARGSUSED */ int setreuid(register struct thread *td, struct setreuid_args *uap) { struct proc *p = td->td_proc; struct ucred *newcred, *oldcred; uid_t euid, ruid; struct uidinfo *euip, *ruip; int error; euid = uap->euid; ruid = uap->ruid; newcred = crget(); euip = uifind(euid); ruip = uifind(ruid); PROC_LOCK(p); oldcred = p->p_ucred; if (((ruid != (uid_t)-1 && ruid != oldcred->cr_ruid && ruid != oldcred->cr_svuid) || (euid != (uid_t)-1 && euid != oldcred->cr_uid && euid != oldcred->cr_ruid && euid != oldcred->cr_svuid)) && (error = suser_cred(oldcred, PRISON_ROOT)) != 0) { PROC_UNLOCK(p); uifree(ruip); uifree(euip); crfree(newcred); return (error); } crcopy(newcred, oldcred); if (euid != (uid_t)-1 && oldcred->cr_uid != euid) { change_euid(newcred, euip); setsugid(p); } if (ruid != (uid_t)-1 && oldcred->cr_ruid != ruid) { change_ruid(newcred, ruip); setsugid(p); } if ((ruid != (uid_t)-1 || newcred->cr_uid != newcred->cr_ruid) && newcred->cr_svuid != newcred->cr_uid) { change_svuid(newcred, newcred->cr_uid); setsugid(p); } p->p_ucred = newcred; PROC_UNLOCK(p); uifree(ruip); uifree(euip); crfree(oldcred); return (0); } #ifndef _SYS_SYSPROTO_H_ struct setregid_args { gid_t rgid; gid_t egid; }; #endif /* * MPSAFE */ /* ARGSUSED */ int setregid(register struct thread *td, struct setregid_args *uap) { struct proc *p = td->td_proc; struct ucred *newcred, *oldcred; gid_t egid, rgid; int error; egid = uap->egid; rgid = uap->rgid; newcred = crget(); PROC_LOCK(p); oldcred = p->p_ucred; if (((rgid != (gid_t)-1 && rgid != oldcred->cr_rgid && rgid != oldcred->cr_svgid) || (egid != (gid_t)-1 && egid != oldcred->cr_groups[0] && egid != oldcred->cr_rgid && egid != oldcred->cr_svgid)) && (error = suser_cred(oldcred, PRISON_ROOT)) != 0) { PROC_UNLOCK(p); crfree(newcred); return (error); } crcopy(newcred, oldcred); if (egid != (gid_t)-1 && oldcred->cr_groups[0] != egid) { change_egid(newcred, egid); setsugid(p); } if (rgid != (gid_t)-1 && oldcred->cr_rgid != rgid) { change_rgid(newcred, rgid); setsugid(p); } if ((rgid != (gid_t)-1 || newcred->cr_groups[0] != newcred->cr_rgid) && newcred->cr_svgid != newcred->cr_groups[0]) { change_svgid(newcred, newcred->cr_groups[0]); setsugid(p); } p->p_ucred = newcred; PROC_UNLOCK(p); crfree(oldcred); return (0); } /* * setresuid(ruid, euid, suid) is like setreuid except control over the * saved uid is explicit. */ #ifndef _SYS_SYSPROTO_H_ struct setresuid_args { uid_t ruid; uid_t euid; uid_t suid; }; #endif /* * MPSAFE */ /* ARGSUSED */ int setresuid(register struct thread *td, struct setresuid_args *uap) { struct proc *p = td->td_proc; struct ucred *newcred, *oldcred; uid_t euid, ruid, suid; struct uidinfo *euip, *ruip; int error; euid = uap->euid; ruid = uap->ruid; suid = uap->suid; newcred = crget(); euip = uifind(euid); ruip = uifind(ruid); PROC_LOCK(p); oldcred = p->p_ucred; if (((ruid != (uid_t)-1 && ruid != oldcred->cr_ruid && ruid != oldcred->cr_svuid && ruid != oldcred->cr_uid) || (euid != (uid_t)-1 && euid != oldcred->cr_ruid && euid != oldcred->cr_svuid && euid != oldcred->cr_uid) || (suid != (uid_t)-1 && suid != oldcred->cr_ruid && suid != oldcred->cr_svuid && suid != oldcred->cr_uid)) && (error = suser_cred(oldcred, PRISON_ROOT)) != 0) { PROC_UNLOCK(p); uifree(ruip); uifree(euip); crfree(newcred); return (error); } crcopy(newcred, oldcred); if (euid != (uid_t)-1 && oldcred->cr_uid != euid) { change_euid(newcred, euip); setsugid(p); } if (ruid != (uid_t)-1 && oldcred->cr_ruid != ruid) { change_ruid(newcred, ruip); setsugid(p); } if (suid != (uid_t)-1 && oldcred->cr_svuid != suid) { change_svuid(newcred, suid); setsugid(p); } p->p_ucred = newcred; PROC_UNLOCK(p); uifree(ruip); uifree(euip); crfree(oldcred); return (0); } /* * setresgid(rgid, egid, sgid) is like setregid except control over the * saved gid is explicit. */ #ifndef _SYS_SYSPROTO_H_ struct setresgid_args { gid_t rgid; gid_t egid; gid_t sgid; }; #endif /* * MPSAFE */ /* ARGSUSED */ int setresgid(register struct thread *td, struct setresgid_args *uap) { struct proc *p = td->td_proc; struct ucred *newcred, *oldcred; gid_t egid, rgid, sgid; int error; egid = uap->egid; rgid = uap->rgid; sgid = uap->sgid; newcred = crget(); PROC_LOCK(p); oldcred = p->p_ucred; if (((rgid != (gid_t)-1 && rgid != oldcred->cr_rgid && rgid != oldcred->cr_svgid && rgid != oldcred->cr_groups[0]) || (egid != (gid_t)-1 && egid != oldcred->cr_rgid && egid != oldcred->cr_svgid && egid != oldcred->cr_groups[0]) || (sgid != (gid_t)-1 && sgid != oldcred->cr_rgid && sgid != oldcred->cr_svgid && sgid != oldcred->cr_groups[0])) && (error = suser_cred(oldcred, PRISON_ROOT)) != 0) { PROC_UNLOCK(p); crfree(newcred); return (error); } crcopy(newcred, oldcred); if (egid != (gid_t)-1 && oldcred->cr_groups[0] != egid) { change_egid(newcred, egid); setsugid(p); } if (rgid != (gid_t)-1 && oldcred->cr_rgid != rgid) { change_rgid(newcred, rgid); setsugid(p); } if (sgid != (gid_t)-1 && oldcred->cr_svgid != sgid) { change_svgid(newcred, sgid); setsugid(p); } p->p_ucred = newcred; PROC_UNLOCK(p); crfree(oldcred); return (0); } #ifndef _SYS_SYSPROTO_H_ struct getresuid_args { uid_t *ruid; uid_t *euid; uid_t *suid; }; #endif /* * MPSAFE */ /* ARGSUSED */ int getresuid(register struct thread *td, struct getresuid_args *uap) { struct ucred *cred; int error1 = 0, error2 = 0, error3 = 0; cred = td->td_ucred; if (uap->ruid) error1 = copyout(&cred->cr_ruid, uap->ruid, sizeof(cred->cr_ruid)); if (uap->euid) error2 = copyout(&cred->cr_uid, uap->euid, sizeof(cred->cr_uid)); if (uap->suid) error3 = copyout(&cred->cr_svuid, uap->suid, sizeof(cred->cr_svuid)); return (error1 ? error1 : error2 ? error2 : error3); } #ifndef _SYS_SYSPROTO_H_ struct getresgid_args { gid_t *rgid; gid_t *egid; gid_t *sgid; }; #endif /* * MPSAFE */ /* ARGSUSED */ int getresgid(register struct thread *td, struct getresgid_args *uap) { struct ucred *cred; int error1 = 0, error2 = 0, error3 = 0; cred = td->td_ucred; if (uap->rgid) error1 = copyout(&cred->cr_rgid, uap->rgid, sizeof(cred->cr_rgid)); if (uap->egid) error2 = copyout(&cred->cr_groups[0], uap->egid, sizeof(cred->cr_groups[0])); if (uap->sgid) error3 = copyout(&cred->cr_svgid, uap->sgid, sizeof(cred->cr_svgid)); return (error1 ? error1 : error2 ? error2 : error3); } #ifndef _SYS_SYSPROTO_H_ struct issetugid_args { int dummy; }; #endif /* * NOT MPSAFE? */ /* ARGSUSED */ int issetugid(register struct thread *td, struct issetugid_args *uap) { struct proc *p = td->td_proc; /* * Note: OpenBSD sets a P_SUGIDEXEC flag set at execve() time, * we use P_SUGID because we consider changing the owners as * "tainting" as well. * This is significant for procs that start as root and "become" * a user without an exec - programs cannot know *everything* * that libc *might* have put in their data segment. */ PROC_LOCK(p); td->td_retval[0] = (p->p_flag & P_SUGID) ? 1 : 0; PROC_UNLOCK(p); return (0); } /* * MPSAFE */ int __setugid(struct thread *td, struct __setugid_args *uap) { #ifdef REGRESSION struct proc *p; p = td->td_proc; switch (uap->flag) { case 0: mtx_lock(&Giant); PROC_LOCK(p); p->p_flag &= ~P_SUGID; PROC_UNLOCK(p); mtx_unlock(&Giant); return (0); case 1: mtx_lock(&Giant); PROC_LOCK(p); p->p_flag |= P_SUGID; PROC_UNLOCK(p); mtx_unlock(&Giant); return (0); default: return (EINVAL); } #else /* !REGRESSION */ return (ENOSYS); #endif /* REGRESSION */ } /* * Check if gid is a member of the group set. * * MPSAFE (cred must be held) */ int groupmember(gid_t gid, struct ucred *cred) { register gid_t *gp; gid_t *egp; egp = &(cred->cr_groups[cred->cr_ngroups]); for (gp = cred->cr_groups; gp < egp; gp++) if (*gp == gid) return (1); return (0); } /* * `suser_enabled' (which can be set by the security.suser_enabled * sysctl) determines whether the system 'super-user' policy is in effect. * If it is nonzero, an effective uid of 0 connotes special privilege, * overriding many mandatory and discretionary protections. If it is zero, * uid 0 is offered no special privilege in the kernel security policy. * Setting it to zero may seriously impact the functionality of many * existing userland programs, and should not be done without careful * consideration of the consequences. */ int suser_enabled = 1; SYSCTL_INT(_security_bsd, OID_AUTO, suser_enabled, CTLFLAG_RW, &suser_enabled, 0, "processes with uid 0 have privilege"); TUNABLE_INT("security.bsd.suser_enabled", &suser_enabled); /* * Test whether the specified credentials imply "super-user" privilege. * Return 0 or EPERM. The flag argument is currently used only to * specify jail interaction. */ int suser_cred(struct ucred *cred, int flag) { if (!suser_enabled) return (EPERM); if (cred->cr_uid != 0) return (EPERM); if (jailed(cred) && !(flag & PRISON_ROOT)) return (EPERM); return (0); } /* * Shortcut to hide contents of struct td and struct proc from the * caller, promoting binary compatibility. */ int suser(struct thread *td) { return (suser_cred(td->td_ucred, 0)); } /* * Test the active securelevel against a given level. securelevel_gt() * implements (securelevel > level). securelevel_ge() implements * (securelevel >= level). Note that the logic is inverted -- these * functions return EPERM on "success" and 0 on "failure". * * MPSAFE */ int securelevel_gt(struct ucred *cr, int level) { int active_securelevel; active_securelevel = securelevel; KASSERT(cr != NULL, ("securelevel_gt: null cr")); if (cr->cr_prison != NULL) { mtx_lock(&cr->cr_prison->pr_mtx); active_securelevel = imax(cr->cr_prison->pr_securelevel, active_securelevel); mtx_unlock(&cr->cr_prison->pr_mtx); } return (active_securelevel > level ? EPERM : 0); } int securelevel_ge(struct ucred *cr, int level) { int active_securelevel; active_securelevel = securelevel; KASSERT(cr != NULL, ("securelevel_ge: null cr")); if (cr->cr_prison != NULL) { mtx_lock(&cr->cr_prison->pr_mtx); active_securelevel = imax(cr->cr_prison->pr_securelevel, active_securelevel); mtx_unlock(&cr->cr_prison->pr_mtx); } return (active_securelevel >= level ? EPERM : 0); } /* * 'see_other_uids' determines whether or not visibility of processes * and sockets with credentials holding different real uids is possible * using a variety of system MIBs. * XXX: data declarations should be together near the beginning of the file. */ static int see_other_uids = 1; SYSCTL_INT(_security_bsd, OID_AUTO, see_other_uids, CTLFLAG_RW, &see_other_uids, 0, "Unprivileged processes may see subjects/objects with different real uid"); /*- * Determine if u1 "can see" the subject specified by u2, according to the * 'see_other_uids' policy. * Returns: 0 for permitted, ESRCH otherwise * Locks: none * References: *u1 and *u2 must not change during the call * u1 may equal u2, in which case only one reference is required */ static int cr_seeotheruids(struct ucred *u1, struct ucred *u2) { if (!see_other_uids && u1->cr_ruid != u2->cr_ruid) { if (suser_cred(u1, PRISON_ROOT) != 0) return (ESRCH); } return (0); } /*- * Determine if u1 "can see" the subject specified by u2. * Returns: 0 for permitted, an errno value otherwise * Locks: none * References: *u1 and *u2 must not change during the call * u1 may equal u2, in which case only one reference is required */ int cr_cansee(struct ucred *u1, struct ucred *u2) { int error; if ((error = prison_check(u1, u2))) return (error); #ifdef MAC if ((error = mac_check_cred_visible(u1, u2))) return (error); #endif if ((error = cr_seeotheruids(u1, u2))) return (error); return (0); } /*- * Determine if td "can see" the subject specified by p. * Returns: 0 for permitted, an errno value otherwise * Locks: Sufficient locks to protect p->p_ucred must be held. td really * should be curthread. * References: td and p must be valid for the lifetime of the call */ int p_cansee(struct thread *td, struct proc *p) { /* Wrap cr_cansee() for all functionality. */ KASSERT(td == curthread, ("%s: td not curthread", __func__)); PROC_LOCK_ASSERT(p, MA_OWNED); return (cr_cansee(td->td_ucred, p->p_ucred)); } /*- * Determine whether cred may deliver the specified signal to proc. * Returns: 0 for permitted, an errno value otherwise. * Locks: A lock must be held for proc. * References: cred and proc must be valid for the lifetime of the call. */ int cr_cansignal(struct ucred *cred, struct proc *proc, int signum) { int error; PROC_LOCK_ASSERT(proc, MA_OWNED); /* * Jail semantics limit the scope of signalling to proc in the * same jail as cred, if cred is in jail. */ error = prison_check(cred, proc->p_ucred); if (error) return (error); #ifdef MAC if ((error = mac_check_proc_signal(cred, proc, signum))) return (error); #endif error = cr_seeotheruids(cred, proc->p_ucred); if (error) return (error); /* * UNIX signal semantics depend on the status of the P_SUGID * bit on the target process. If the bit is set, then additional * restrictions are placed on the set of available signals. */ if (proc->p_flag & P_SUGID) { switch (signum) { case 0: case SIGKILL: case SIGINT: case SIGTERM: case SIGSTOP: case SIGTTIN: case SIGTTOU: case SIGTSTP: case SIGHUP: case SIGUSR1: case SIGUSR2: /* * Generally, permit job and terminal control * signals. */ break; default: /* Not permitted without privilege. */ error = suser_cred(cred, PRISON_ROOT); if (error) return (error); } } /* * Generally, the target credential's ruid or svuid must match the * subject credential's ruid or euid. */ if (cred->cr_ruid != proc->p_ucred->cr_ruid && cred->cr_ruid != proc->p_ucred->cr_svuid && cred->cr_uid != proc->p_ucred->cr_ruid && cred->cr_uid != proc->p_ucred->cr_svuid) { /* Not permitted without privilege. */ error = suser_cred(cred, PRISON_ROOT); if (error) return (error); } return (0); } /*- * Determine whether td may deliver the specified signal to p. * Returns: 0 for permitted, an errno value otherwise * Locks: Sufficient locks to protect various components of td and p * must be held. td must be curthread, and a lock must be * held for p. * References: td and p must be valid for the lifetime of the call */ int p_cansignal(struct thread *td, struct proc *p, int signum) { KASSERT(td == curthread, ("%s: td not curthread", __func__)); PROC_LOCK_ASSERT(p, MA_OWNED); if (td->td_proc == p) return (0); /* * UNIX signalling semantics require that processes in the same * session always be able to deliver SIGCONT to one another, * overriding the remaining protections. */ /* XXX: This will require an additional lock of some sort. */ if (signum == SIGCONT && td->td_proc->p_session == p->p_session) return (0); return (cr_cansignal(td->td_ucred, p, signum)); } /*- * Determine whether td may reschedule p. * Returns: 0 for permitted, an errno value otherwise * Locks: Sufficient locks to protect various components of td and p * must be held. td must be curthread, and a lock must * be held for p. * References: td and p must be valid for the lifetime of the call */ int p_cansched(struct thread *td, struct proc *p) { int error; KASSERT(td == curthread, ("%s: td not curthread", __func__)); PROC_LOCK_ASSERT(p, MA_OWNED); if (td->td_proc == p) return (0); if ((error = prison_check(td->td_ucred, p->p_ucred))) return (error); #ifdef MAC if ((error = mac_check_proc_sched(td->td_ucred, p))) return (error); #endif if ((error = cr_seeotheruids(td->td_ucred, p->p_ucred))) return (error); if (td->td_ucred->cr_ruid == p->p_ucred->cr_ruid) return (0); if (td->td_ucred->cr_uid == p->p_ucred->cr_ruid) return (0); if (suser_cred(td->td_ucred, PRISON_ROOT) == 0) return (0); #ifdef CAPABILITIES if (!cap_check(NULL, td, CAP_SYS_NICE, PRISON_ROOT)) return (0); #endif return (EPERM); } /* * The 'unprivileged_proc_debug' flag may be used to disable a variety of * unprivileged inter-process debugging services, including some procfs * functionality, ptrace(), and ktrace(). In the past, inter-process * debugging has been involved in a variety of security problems, and sites * not requiring the service might choose to disable it when hardening * systems. * * XXX: Should modifying and reading this variable require locking? * XXX: data declarations should be together near the beginning of the file. */ static int unprivileged_proc_debug = 1; SYSCTL_INT(_security_bsd, OID_AUTO, unprivileged_proc_debug, CTLFLAG_RW, &unprivileged_proc_debug, 0, "Unprivileged processes may use process debugging facilities"); /*- * Determine whether td may debug p. * Returns: 0 for permitted, an errno value otherwise * Locks: Sufficient locks to protect various components of td and p * must be held. td must be curthread, and a lock must * be held for p. * References: td and p must be valid for the lifetime of the call */ int p_candebug(struct thread *td, struct proc *p) { int credentialchanged, error, grpsubset, i, uidsubset; KASSERT(td == curthread, ("%s: td not curthread", __func__)); PROC_LOCK_ASSERT(p, MA_OWNED); if (!unprivileged_proc_debug) { error = suser_cred(td->td_ucred, PRISON_ROOT); if (error) return (error); } if (td->td_proc == p) return (0); if ((error = prison_check(td->td_ucred, p->p_ucred))) return (error); #ifdef MAC if ((error = mac_check_proc_debug(td->td_ucred, p))) return (error); #endif if ((error = cr_seeotheruids(td->td_ucred, p->p_ucred))) return (error); /* * Is p's group set a subset of td's effective group set? This * includes p's egid, group access list, rgid, and svgid. */ grpsubset = 1; for (i = 0; i < p->p_ucred->cr_ngroups; i++) { if (!groupmember(p->p_ucred->cr_groups[i], td->td_ucred)) { grpsubset = 0; break; } } grpsubset = grpsubset && groupmember(p->p_ucred->cr_rgid, td->td_ucred) && groupmember(p->p_ucred->cr_svgid, td->td_ucred); /* * Are the uids present in p's credential equal to td's * effective uid? This includes p's euid, svuid, and ruid. */ uidsubset = (td->td_ucred->cr_uid == p->p_ucred->cr_uid && td->td_ucred->cr_uid == p->p_ucred->cr_svuid && td->td_ucred->cr_uid == p->p_ucred->cr_ruid); /* * Has the credential of the process changed since the last exec()? */ credentialchanged = (p->p_flag & P_SUGID); /* * If p's gids aren't a subset, or the uids aren't a subset, * or the credential has changed, require appropriate privilege * for td to debug p. For POSIX.1e capabilities, this will * require CAP_SYS_PTRACE. */ if (!grpsubset || !uidsubset || credentialchanged) { error = suser_cred(td->td_ucred, PRISON_ROOT); if (error) return (error); } /* Can't trace init when securelevel > 0. */ if (p == initproc) { error = securelevel_gt(td->td_ucred, 0); if (error) return (error); } /* * Can't trace a process that's currently exec'ing. * XXX: Note, this is not a security policy decision, it's a * basic correctness/functionality decision. Therefore, this check * should be moved to the caller's of p_candebug(). */ if ((p->p_flag & P_INEXEC) != 0) return (EAGAIN); return (0); } /*- * Determine whether the subject represented by cred can "see" a socket. * Returns: 0 for permitted, ENOENT otherwise. */ int cr_canseesocket(struct ucred *cred, struct socket *so) { int error; error = prison_check(cred, so->so_cred); if (error) return (ENOENT); #ifdef MAC error = mac_check_socket_visible(cred, so); if (error) return (error); #endif if (cr_seeotheruids(cred, so->so_cred)) return (ENOENT); return (0); } /* * Allocate a zeroed cred structure. */ struct ucred * crget(void) { register struct ucred *cr; MALLOC(cr, struct ucred *, sizeof(*cr), M_CRED, M_WAITOK | M_ZERO); cr->cr_ref = 1; cr->cr_mtxp = mtx_pool_find(cr); #ifdef MAC mac_init_cred(cr); #endif return (cr); } /* * Claim another reference to a ucred structure. */ struct ucred * crhold(struct ucred *cr) { mtx_lock(cr->cr_mtxp); cr->cr_ref++; mtx_unlock(cr->cr_mtxp); return (cr); } /* * Free a cred structure. * Throws away space when ref count gets to 0. */ void crfree(struct ucred *cr) { struct mtx *mtxp = cr->cr_mtxp; mtx_lock(mtxp); KASSERT(cr->cr_ref > 0, ("bad ucred refcount: %d", cr->cr_ref)); if (--cr->cr_ref == 0) { /* * Some callers of crget(), such as nfs_statfs(), * allocate a temporary credential, but don't * allocate a uidinfo structure. */ mtx_unlock(mtxp); mtx_lock(&Giant); if (cr->cr_uidinfo != NULL) uifree(cr->cr_uidinfo); if (cr->cr_ruidinfo != NULL) uifree(cr->cr_ruidinfo); /* * Free a prison, if any. */ if (jailed(cr)) prison_free(cr->cr_prison); #ifdef MAC mac_destroy_cred(cr); #endif FREE(cr, M_CRED); mtx_unlock(&Giant); } else { mtx_unlock(mtxp); } } /* * Check to see if this ucred is shared. */ int crshared(struct ucred *cr) { int shared; mtx_lock(cr->cr_mtxp); shared = (cr->cr_ref > 1); mtx_unlock(cr->cr_mtxp); return (shared); } /* * Copy a ucred's contents from a template. Does not block. */ void crcopy(struct ucred *dest, struct ucred *src) { KASSERT(crshared(dest) == 0, ("crcopy of shared ucred")); bcopy(&src->cr_startcopy, &dest->cr_startcopy, (unsigned)((caddr_t)&src->cr_endcopy - (caddr_t)&src->cr_startcopy)); uihold(dest->cr_uidinfo); uihold(dest->cr_ruidinfo); if (jailed(dest)) prison_hold(dest->cr_prison); #ifdef MAC mac_create_cred(src, dest); #endif } /* * Dup cred struct to a new held one. */ struct ucred * crdup(struct ucred *cr) { struct ucred *newcr; newcr = crget(); crcopy(newcr, cr); return (newcr); } #ifdef DIAGNOSTIC void cred_free_thread(struct thread *td) { struct ucred *cred; cred = td->td_ucred; td->td_ucred = NULL; if (cred != NULL) crfree(cred); } #endif /* * Fill in a struct xucred based on a struct ucred. */ void cru2x(struct ucred *cr, struct xucred *xcr) { bzero(xcr, sizeof(*xcr)); xcr->cr_version = XUCRED_VERSION; xcr->cr_uid = cr->cr_uid; xcr->cr_ngroups = cr->cr_ngroups; bcopy(cr->cr_groups, xcr->cr_groups, sizeof(cr->cr_groups)); } /* * small routine to swap a thread's current ucred for the correct one * taken from the process. */ void cred_update_thread(struct thread *td) { struct proc *p; struct ucred *cred; p = td->td_proc; cred = td->td_ucred; PROC_LOCK(p); td->td_ucred = crhold(p->p_ucred); PROC_UNLOCK(p); if (cred != NULL) crfree(cred); } /* * Get login name, if available. */ #ifndef _SYS_SYSPROTO_H_ struct getlogin_args { char *namebuf; u_int namelen; }; #endif /* * MPSAFE */ /* ARGSUSED */ int getlogin(struct thread *td, struct getlogin_args *uap) { int error; char login[MAXLOGNAME]; struct proc *p = td->td_proc; if (uap->namelen > MAXLOGNAME) uap->namelen = MAXLOGNAME; PROC_LOCK(p); SESS_LOCK(p->p_session); bcopy(p->p_session->s_login, login, uap->namelen); SESS_UNLOCK(p->p_session); PROC_UNLOCK(p); error = copyout(login, uap->namebuf, uap->namelen); return(error); } /* * Set login name. */ #ifndef _SYS_SYSPROTO_H_ struct setlogin_args { char *namebuf; }; #endif /* * MPSAFE */ /* ARGSUSED */ int setlogin(struct thread *td, struct setlogin_args *uap) { struct proc *p = td->td_proc; int error; char logintmp[MAXLOGNAME]; error = suser_cred(td->td_ucred, PRISON_ROOT); if (error) return (error); error = copyinstr(uap->namebuf, logintmp, sizeof(logintmp), NULL); if (error == ENAMETOOLONG) error = EINVAL; else if (!error) { PROC_LOCK(p); SESS_LOCK(p->p_session); (void) memcpy(p->p_session->s_login, logintmp, sizeof(logintmp)); SESS_UNLOCK(p->p_session); PROC_UNLOCK(p); } return (error); } void setsugid(struct proc *p) { PROC_LOCK_ASSERT(p, MA_OWNED); p->p_flag |= P_SUGID; if (!(p->p_pfsflags & PF_ISUGID)) p->p_stops = 0; } /*- * Change a process's effective uid. * Side effects: newcred->cr_uid and newcred->cr_uidinfo will be modified. * References: newcred must be an exclusive credential reference for the * duration of the call. */ void change_euid(struct ucred *newcred, struct uidinfo *euip) { newcred->cr_uid = euip->ui_uid; uihold(euip); uifree(newcred->cr_uidinfo); newcred->cr_uidinfo = euip; } /*- * Change a process's effective gid. * Side effects: newcred->cr_gid will be modified. * References: newcred must be an exclusive credential reference for the * duration of the call. */ void change_egid(struct ucred *newcred, gid_t egid) { newcred->cr_groups[0] = egid; } /*- * Change a process's real uid. * Side effects: newcred->cr_ruid will be updated, newcred->cr_ruidinfo * will be updated, and the old and new cr_ruidinfo proc * counts will be updated. * References: newcred must be an exclusive credential reference for the * duration of the call. */ void change_ruid(struct ucred *newcred, struct uidinfo *ruip) { (void)chgproccnt(newcred->cr_ruidinfo, -1, 0); newcred->cr_ruid = ruip->ui_uid; uihold(ruip); uifree(newcred->cr_ruidinfo); newcred->cr_ruidinfo = ruip; (void)chgproccnt(newcred->cr_ruidinfo, 1, 0); } /*- * Change a process's real gid. * Side effects: newcred->cr_rgid will be updated. * References: newcred must be an exclusive credential reference for the * duration of the call. */ void change_rgid(struct ucred *newcred, gid_t rgid) { newcred->cr_rgid = rgid; } /*- * Change a process's saved uid. * Side effects: newcred->cr_svuid will be updated. * References: newcred must be an exclusive credential reference for the * duration of the call. */ void change_svuid(struct ucred *newcred, uid_t svuid) { newcred->cr_svuid = svuid; } /*- * Change a process's saved gid. * Side effects: newcred->cr_svgid will be updated. * References: newcred must be an exclusive credential reference for the * duration of the call. */ void change_svgid(struct ucred *newcred, gid_t svgid) { newcred->cr_svgid = svgid; }