/* * 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: head/sys/kern/kern_prot.c 87280 2001-12-03 19:10:21Z rwatson $ */ /* * System calls related to processes and protection */ #include "opt_compat.h" #include "opt_global.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include static MALLOC_DEFINE(M_CRED, "cred", "credentials"); SYSCTL_NODE(_kern, OID_AUTO, security, CTLFLAG_RW, 0, "Kernel security policy"); SYSCTL_NODE(_kern_security, OID_AUTO, bsd, CTLFLAG_RW, 0, "BSD security policy"); #ifndef _SYS_SYSPROTO_H_ struct getpid_args { int dummy; }; #endif /* * MPSAFE */ /* ARGSUSED */ int getpid(td, uap) struct thread *td; struct getpid_args *uap; { struct proc *p = td->td_proc; int s; s = mtx_lock_giant(kern_giant_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 mtx_unlock_giant(s); return (0); } #ifndef _SYS_SYSPROTO_H_ struct getppid_args { int dummy; }; #endif /* * MPSAFE */ /* ARGSUSED */ int getppid(td, uap) struct thread *td; struct getppid_args *uap; { struct proc *p = td->td_proc; int s; s = mtx_lock_giant(kern_giant_proc); PROC_LOCK(p); td->td_retval[0] = p->p_pptr->p_pid; PROC_UNLOCK(p); mtx_unlock_giant(s); 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(td, uap) struct thread *td; struct getpgrp_args *uap; { struct proc *p = td->td_proc; mtx_lock(&Giant); td->td_retval[0] = p->p_pgrp->pg_id; mtx_unlock(&Giant); return (0); } /* Get an arbitary pid's process group id */ #ifndef _SYS_SYSPROTO_H_ struct getpgid_args { pid_t pid; }; #endif /* * MPSAFE */ int getpgid(td, uap) struct thread *td; struct getpgid_args *uap; { struct proc *p = td->td_proc; struct proc *pt; int error, s; s = mtx_lock_giant(kern_giant_proc); error = 0; if (uap->pid == 0) td->td_retval[0] = p->p_pgrp->pg_id; else if ((pt = pfind(uap->pid)) == NULL) error = ESRCH; else { error = p_cansee(p, pt); if (error == 0) td->td_retval[0] = pt->p_pgrp->pg_id; PROC_UNLOCK(pt); } mtx_unlock_giant(s); return (error); } /* * Get an arbitary pid's session id. */ #ifndef _SYS_SYSPROTO_H_ struct getsid_args { pid_t pid; }; #endif /* * MPSAFE */ int getsid(td, uap) struct thread *td; struct getsid_args *uap; { struct proc *p = td->td_proc; struct proc *pt; int error; mtx_lock(&Giant); error = 0; if (uap->pid == 0) td->td_retval[0] = p->p_session->s_sid; else if ((pt = pfind(uap->pid)) == NULL) error = ESRCH; else { error = p_cansee(p, pt); if (error == 0) td->td_retval[0] = pt->p_session->s_sid; PROC_UNLOCK(pt); } mtx_unlock(&Giant); return (error); } #ifndef _SYS_SYSPROTO_H_ struct getuid_args { int dummy; }; #endif /* * MPSAFE */ /* ARGSUSED */ int getuid(td, uap) struct thread *td; struct getuid_args *uap; { struct proc *p = td->td_proc; mtx_lock(&Giant); td->td_retval[0] = p->p_ucred->cr_ruid; #if defined(COMPAT_43) || defined(COMPAT_SUNOS) td->td_retval[1] = p->p_ucred->cr_uid; #endif mtx_unlock(&Giant); return (0); } #ifndef _SYS_SYSPROTO_H_ struct geteuid_args { int dummy; }; #endif /* * MPSAFE */ /* ARGSUSED */ int geteuid(td, uap) struct thread *td; struct geteuid_args *uap; { mtx_lock(&Giant); td->td_retval[0] = td->td_proc->p_ucred->cr_uid; mtx_unlock(&Giant); return (0); } #ifndef _SYS_SYSPROTO_H_ struct getgid_args { int dummy; }; #endif /* * MPSAFE */ /* ARGSUSED */ int getgid(td, uap) struct thread *td; struct getgid_args *uap; { struct proc *p = td->td_proc; mtx_lock(&Giant); td->td_retval[0] = p->p_ucred->cr_rgid; #if defined(COMPAT_43) || defined(COMPAT_SUNOS) td->td_retval[1] = p->p_ucred->cr_groups[0]; #endif mtx_unlock(&Giant); 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(td, uap) struct thread *td; struct getegid_args *uap; { struct proc *p = td->td_proc; mtx_lock(&Giant); td->td_retval[0] = p->p_ucred->cr_groups[0]; mtx_unlock(&Giant); return (0); } #ifndef _SYS_SYSPROTO_H_ struct getgroups_args { u_int gidsetsize; gid_t *gidset; }; #endif /* * MPSAFE */ int getgroups(td, uap) struct thread *td; register struct getgroups_args *uap; { struct ucred *cred; struct proc *p = td->td_proc; u_int ngrp; int error; mtx_lock(&Giant); error = 0; cred = p->p_ucred; if ((ngrp = uap->gidsetsize) == 0) { td->td_retval[0] = cred->cr_ngroups; goto done2; } if (ngrp < cred->cr_ngroups) { error = EINVAL; goto done2; } ngrp = cred->cr_ngroups; if ((error = copyout((caddr_t)cred->cr_groups, (caddr_t)uap->gidset, ngrp * sizeof(gid_t)))) goto done2; td->td_retval[0] = ngrp; done2: mtx_unlock(&Giant); return (error); } #ifndef _SYS_SYSPROTO_H_ struct setsid_args { int dummy; }; #endif /* * MPSAFE */ /* ARGSUSED */ int setsid(td, uap) register struct thread *td; struct setsid_args *uap; { int error; struct proc *p = td->td_proc; mtx_lock(&Giant); if (p->p_pgid == p->p_pid || pgfind(p->p_pid)) error = EPERM; else { (void)enterpgrp(p, p->p_pid, 1); td->td_retval[0] = p->p_pid; error = 0; } mtx_unlock(&Giant); 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(td, uap) 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; if (uap->pgid < 0) return (EINVAL); mtx_lock(&Giant); sx_slock(&proctree_lock); if (uap->pid != 0 && uap->pid != curp->p_pid) { if ((targp = pfind(uap->pid)) == NULL || !inferior(targp)) { if (targp) PROC_UNLOCK(targp); error = ESRCH; goto done2; } if ((error = p_cansee(curproc, targp))) { PROC_UNLOCK(targp); goto done2; } if (targp->p_pgrp == NULL || targp->p_session != curp->p_session) { PROC_UNLOCK(targp); error = EPERM; goto done2; } if (targp->p_flag & P_EXEC) { PROC_UNLOCK(targp); error = EACCES; goto done2; } } else { targp = curp; PROC_LOCK(curp); /* XXX: not needed */ } if (SESS_LEADER(targp)) { PROC_UNLOCK(targp); error = EPERM; goto done2; } if (uap->pgid == 0) uap->pgid = targp->p_pid; else if (uap->pgid != targp->p_pid) { if ((pgrp = pgfind(uap->pgid)) == 0 || pgrp->pg_session != curp->p_session) { PROC_UNLOCK(targp); error = EPERM; goto done2; } } /* XXX: We should probably hold the lock across enterpgrp. */ PROC_UNLOCK(targp); error = enterpgrp(targp, uap->pgid, 0); done2: sx_sunlock(&proctree_lock); mtx_unlock(&Giant); 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(td, uap) struct thread *td; struct setuid_args *uap; { struct proc *p = td->td_proc; struct ucred *newcred, *oldcred; uid_t uid; int error; uid = uap->uid; mtx_lock(&Giant); error = 0; 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_xxx(oldcred, NULL, PRISON_ROOT)) != 0) goto done2; newcred = crdup(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_xxx(oldcred, NULL, 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, uid); 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. * Copy credentials so other references do not see our changes. */ if (uid != oldcred->cr_uid) { change_euid(newcred, uid); setsugid(p); } p->p_ucred = newcred; crfree(oldcred); done2: mtx_unlock(&Giant); return (error); } #ifndef _SYS_SYSPROTO_H_ struct seteuid_args { uid_t euid; }; #endif /* * MPSAFE */ /* ARGSUSED */ int seteuid(td, uap) struct thread *td; struct seteuid_args *uap; { struct proc *p = td->td_proc; struct ucred *newcred, *oldcred; uid_t euid; int error; euid = uap->euid; mtx_lock(&Giant); error = 0; oldcred = p->p_ucred; if (euid != oldcred->cr_ruid && /* allow seteuid(getuid()) */ euid != oldcred->cr_svuid && /* allow seteuid(saved uid) */ (error = suser_xxx(oldcred, NULL, PRISON_ROOT)) != 0) goto done2; /* * Everything's okay, do it. Copy credentials so other references do * not see our changes. */ newcred = crdup(oldcred); if (oldcred->cr_uid != euid) { change_euid(newcred, euid); setsugid(p); } p->p_ucred = newcred; crfree(oldcred); done2: mtx_unlock(&Giant); return (error); } #ifndef _SYS_SYSPROTO_H_ struct setgid_args { gid_t gid; }; #endif /* * MPSAFE */ /* ARGSUSED */ int setgid(td, uap) 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; mtx_lock(&Giant); error = 0; 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_xxx(oldcred, NULL, PRISON_ROOT)) != 0) goto done2; newcred = crdup(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_xxx(oldcred, NULL, 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; crfree(oldcred); done2: mtx_unlock(&Giant); return (error); } #ifndef _SYS_SYSPROTO_H_ struct setegid_args { gid_t egid; }; #endif /* * MPSAFE */ /* ARGSUSED */ int setegid(td, uap) 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; mtx_lock(&Giant); error = 0; oldcred = p->p_ucred; if (egid != oldcred->cr_rgid && /* allow setegid(getgid()) */ egid != oldcred->cr_svgid && /* allow setegid(saved gid) */ (error = suser_xxx(oldcred, NULL, PRISON_ROOT)) != 0) goto done2; newcred = crdup(oldcred); if (oldcred->cr_groups[0] != egid) { change_egid(newcred, egid); setsugid(p); } p->p_ucred = newcred; crfree(oldcred); done2: mtx_unlock(&Giant); return (error); } #ifndef _SYS_SYSPROTO_H_ struct setgroups_args { u_int gidsetsize; gid_t *gidset; }; #endif /* * MPSAFE */ /* ARGSUSED */ int setgroups(td, uap) struct thread *td; struct setgroups_args *uap; { struct proc *p = td->td_proc; struct ucred *newcred, *oldcred; u_int ngrp; int error; ngrp = uap->gidsetsize; mtx_lock(&Giant); oldcred = p->p_ucred; if ((error = suser_xxx(oldcred, NULL, PRISON_ROOT)) != 0) goto done2; if (ngrp > NGROUPS) { error = EINVAL; goto done2; } /* * XXX A little bit lazy here. We could test if anything has * changed before crcopy() and setting P_SUGID. */ newcred = crdup(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 { if ((error = copyin((caddr_t)uap->gidset, (caddr_t)newcred->cr_groups, ngrp * sizeof(gid_t)))) { crfree(newcred); goto done2; } newcred->cr_ngroups = ngrp; } setsugid(p); p->p_ucred = newcred; crfree(oldcred); done2: mtx_unlock(&Giant); return (error); } #ifndef _SYS_SYSPROTO_H_ struct setreuid_args { uid_t ruid; uid_t euid; }; #endif /* * MPSAFE */ /* ARGSUSED */ int setreuid(td, uap) register struct thread *td; struct setreuid_args *uap; { struct proc *p = td->td_proc; struct ucred *newcred, *oldcred; uid_t euid, ruid; int error; euid = uap->euid; ruid = uap->ruid; mtx_lock(&Giant); error = 0; 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_xxx(oldcred, NULL, PRISON_ROOT)) != 0) goto done2; newcred = crdup(oldcred); if (euid != (uid_t)-1 && oldcred->cr_uid != euid) { change_euid(newcred, euid); setsugid(p); } if (ruid != (uid_t)-1 && oldcred->cr_ruid != ruid) { change_ruid(newcred, ruid); 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; crfree(oldcred); done2: mtx_unlock(&Giant); return (error); } #ifndef _SYS_SYSPROTO_H_ struct setregid_args { gid_t rgid; gid_t egid; }; #endif /* * MPSAFE */ /* ARGSUSED */ int setregid(td, uap) 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; mtx_lock(&Giant); error = 0; 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_xxx(oldcred, NULL, PRISON_ROOT)) != 0) goto done2; newcred = crdup(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; crfree(oldcred); done2: mtx_unlock(&Giant); return (error); } /* * 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(td, uap) register struct thread *td; struct setresuid_args *uap; { struct proc *p = td->td_proc; struct ucred *newcred, *oldcred; uid_t euid, ruid, suid; int error; euid = uap->euid; ruid = uap->ruid; suid = uap->suid; mtx_lock(&Giant); 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_xxx(oldcred, NULL, PRISON_ROOT)) != 0) goto done2; newcred = crdup(oldcred); if (euid != (uid_t)-1 && oldcred->cr_uid != euid) { change_euid(newcred, euid); setsugid(p); } if (ruid != (uid_t)-1 && oldcred->cr_ruid != ruid) { change_ruid(newcred, ruid); setsugid(p); } if (suid != (uid_t)-1 && oldcred->cr_svuid != suid) { change_svuid(newcred, suid); setsugid(p); } p->p_ucred = newcred; crfree(oldcred); error = 0; done2: mtx_unlock(&Giant); return (error); } /* * 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(td, uap) 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; mtx_lock(&Giant); 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_xxx(oldcred, NULL, PRISON_ROOT)) != 0) { goto done2; } newcred = crdup(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; crfree(oldcred); error = 0; done2: mtx_unlock(&Giant); return (error); } #ifndef _SYS_SYSPROTO_H_ struct getresuid_args { uid_t *ruid; uid_t *euid; uid_t *suid; }; #endif /* * MPSAFE */ /* ARGSUSED */ int getresuid(td, uap) register struct thread *td; struct getresuid_args *uap; { struct ucred *cred; struct proc *p = td->td_proc; int error1 = 0, error2 = 0, error3 = 0; mtx_lock(&Giant); cred = p->p_ucred; if (uap->ruid) error1 = copyout((caddr_t)&cred->cr_ruid, (caddr_t)uap->ruid, sizeof(cred->cr_ruid)); if (uap->euid) error2 = copyout((caddr_t)&cred->cr_uid, (caddr_t)uap->euid, sizeof(cred->cr_uid)); if (uap->suid) error3 = copyout((caddr_t)&cred->cr_svuid, (caddr_t)uap->suid, sizeof(cred->cr_svuid)); mtx_unlock(&Giant); 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(td, uap) register struct thread *td; struct getresgid_args *uap; { struct ucred *cred; struct proc *p = td->td_proc; int error1 = 0, error2 = 0, error3 = 0; mtx_lock(&Giant); cred = p->p_ucred; if (uap->rgid) error1 = copyout((caddr_t)&cred->cr_rgid, (caddr_t)uap->rgid, sizeof(cred->cr_rgid)); if (uap->egid) error2 = copyout((caddr_t)&cred->cr_groups[0], (caddr_t)uap->egid, sizeof(cred->cr_groups[0])); if (uap->sgid) error3 = copyout((caddr_t)&cred->cr_svgid, (caddr_t)uap->sgid, sizeof(cred->cr_svgid)); mtx_unlock(&Giant); return (error1 ? error1 : error2 ? error2 : error3); } #ifndef _SYS_SYSPROTO_H_ struct issetugid_args { int dummy; }; #endif /* * NOT MPSAFE? */ /* ARGSUSED */ int issetugid(td, uap) 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. */ td->td_retval[0] = (p->p_flag & P_SUGID) ? 1 : 0; return (0); } /* * MPSAFE */ int __setugid(td, uap) struct thread *td; struct __setugid_args *uap; { #ifdef REGRESSION int error; mtx_lock(&Giant); error = 0; switch (uap->flag) { case 0: td->td_proc->p_flag &= ~P_SUGID; break; case 1: td->td_proc->p_flag |= P_SUGID; break; default: error = EINVAL; break; } mtx_unlock(&Giant); return (error); #else /* !REGRESSION */ return (ENOSYS); #endif /* REGRESSION */ } /* * Check if gid is a member of the group set. */ int groupmember(gid, cred) 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 kern.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(_kern_security_bsd, OID_AUTO, suser_enabled, CTLFLAG_RW, &suser_enabled, 0, "processes with uid 0 have privilege"); /* * Test whether the specified credentials imply "super-user" privilege. * Return 0 or EPERM. */ int suser(p) struct proc *p; { return (suser_xxx(0, p, 0)); } /* * version for when the thread pointer is available and not the proc. * (saves having to include proc.h into every file that needs to do the change.) */ int suser_td(td) struct thread *td; { return suser_xxx(0, td->td_proc, 0); } /* * wrapper to use if you have the thread on hand but not the proc. */ int suser_xxx_td(cred, td, flag) struct ucred *cred; struct thread *td; int flag; { return(suser_xxx(cred, td->td_proc, flag)); } int suser_xxx(cred, proc, flag) struct ucred *cred; struct proc *proc; int flag; { if (!suser_enabled) return (EPERM); if (!cred && !proc) { printf("suser_xxx(): THINK!\n"); return (EPERM); } if (cred == NULL) cred = proc->p_ucred; if (cred->cr_uid != 0) return (EPERM); if (jailed(cred) && !(flag & PRISON_ROOT)) return (EPERM); return (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". * * cr is permitted to be NULL for the time being, as there were some * existing securelevel checks that occurred without a process/credential * context. In the future this will be disallowed, so a kernel message * is displayed. */ int securelevel_gt(struct ucred *cr, int level) { int active_securelevel; active_securelevel = securelevel; if (cr == NULL) printf("securelevel_gt: cr is NULL\n"); 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; if (cr == NULL) printf("securelevel_gt: cr is NULL\n"); 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(_kern_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. * 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); if (!see_other_uids && u1->cr_ruid != u2->cr_ruid) { if (suser_xxx(u1, NULL, PRISON_ROOT) != 0) return (ESRCH); } return (0); } /*- * Determine if p1 "can see" the subject specified by p2. * Returns: 0 for permitted, an errno value otherwise * Locks: Sufficient locks to protect p1->p_ucred and p2->p_ucred must * be held. Normally, p1 will be curproc, and a lock must be held * for p2. * References: p1 and p2 must be valid for the lifetime of the call */ int p_cansee(struct proc *p1, struct proc *p2) { /* Wrap cr_cansee() for all functionality. */ return (cr_cansee(p1->p_ucred, p2->p_ucred)); } /*- * Determine whether p1 may deliver the specified signal to p2. * Returns: 0 for permitted, an errno value otherwise * Locks: Sufficient locks to protect various components of p1 and p2 * must be held. Normally, p1 will be curproc, and a lock must * be held for p2. * References: p1 and p2 must be valid for the lifetime of the call */ int p_cansignal(struct proc *p1, struct proc *p2, int signum) { int error; if (p1 == p2) return (0); /* * Jail semantics limit the scope of signalling to p2 in the same * jail as p1, if p1 is in jail. */ if ((error = prison_check(p1->p_ucred, p2->p_ucred))) return (error); /* * UNIX signalling semantics require that processes in the same * session always be able to deliver SIGCONT to one another, * overriding the remaining protections. */ if (signum == SIGCONT && p1->p_session == p2->p_session) return (0); /* * 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 (p2->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, privilege is required. */ error = suser_xxx(NULL, p1, PRISON_ROOT); if (error) return (error); } } /* * Generally, the target credential's ruid or svuid must match the * subject credential's ruid or euid. */ if (p1->p_ucred->cr_ruid != p2->p_ucred->cr_ruid && p1->p_ucred->cr_ruid != p2->p_ucred->cr_svuid && p1->p_ucred->cr_uid != p2->p_ucred->cr_ruid && p1->p_ucred->cr_uid != p2->p_ucred->cr_svuid) { /* Not permitted, try privilege. */ error = suser_xxx(NULL, p1, PRISON_ROOT); if (error) return (error); } return (0); } /*- * Determine whether p1 may reschedule p2. * Returns: 0 for permitted, an errno value otherwise * Locks: Sufficient locks to protect various components of p1 and p2 * must be held. Normally, p1 will be curproc, and a lock must * be held for p2. * References: p1 and p2 must be valid for the lifetime of the call */ int p_cansched(struct proc *p1, struct proc *p2) { int error; if (p1 == p2) return (0); if ((error = prison_check(p1->p_ucred, p2->p_ucred))) return (error); if (p1->p_ucred->cr_ruid == p2->p_ucred->cr_ruid) return (0); if (p1->p_ucred->cr_uid == p2->p_ucred->cr_ruid) return (0); if (suser_xxx(0, p1, PRISON_ROOT) == 0) return (0); #ifdef CAPABILITIES if (!cap_check(NULL, p1, 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(_kern_security_bsd, OID_AUTO, unprivileged_proc_debug, CTLFLAG_RW, &unprivileged_proc_debug, 0, "Unprivileged processes may use process debugging facilities"); /*- * Determine whether p1 may debug p2. * Returns: 0 for permitted, an errno value otherwise * Locks: Sufficient locks to protect various components of p1 and p2 * must be held. Normally, p1 will be curproc, and a lock must * be held for p2. * References: p1 and p2 must be valid for the lifetime of the call */ int p_candebug(struct proc *p1, struct proc *p2) { int credentialchanged, error, grpsubset, i, uidsubset; if (!unprivileged_proc_debug) { error = suser_xxx(NULL, p1, PRISON_ROOT); if (error) return (error); } if (p1 == p2) return (0); if ((error = prison_check(p1->p_ucred, p2->p_ucred))) return (error); /* * Is p2's group set a subset of p1's effective group set? This * includes p2's egid, group access list, rgid, and svgid. */ grpsubset = 1; for (i = 0; i < p2->p_ucred->cr_ngroups; i++) { if (!groupmember(p2->p_ucred->cr_groups[i], p1->p_ucred)) { grpsubset = 0; break; } } grpsubset = grpsubset && groupmember(p2->p_ucred->cr_rgid, p1->p_ucred) && groupmember(p2->p_ucred->cr_svgid, p1->p_ucred); /* * Are the uids present in p2's credential equal to p1's * effective uid? This includes p2's euid, svuid, and ruid. */ uidsubset = (p1->p_ucred->cr_uid == p2->p_ucred->cr_uid && p1->p_ucred->cr_uid == p2->p_ucred->cr_svuid && p1->p_ucred->cr_uid == p2->p_ucred->cr_ruid); /* * Has the credential of the process changed since the last exec()? */ credentialchanged = (p2->p_flag & P_SUGID); /* * If p2's gids aren't a subset, or the uids aren't a subset, * or the credential has changed, require appropriate privilege * for p1 to debug p2. For POSIX.1e capabilities, this will * require CAP_SYS_PTRACE. */ if (!grpsubset || !uidsubset || credentialchanged) { error = suser_xxx(NULL, p1, PRISON_ROOT); if (error) return (error); } /* Can't trace init when securelevel > 0. */ if (p2 == initproc) { error = securelevel_gt(p1->p_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 ((p2->p_flag & P_INEXEC) != 0) return (EAGAIN); return (0); } /* * Allocate a zeroed cred structure. */ struct ucred * crget() { register struct ucred *cr; MALLOC(cr, struct ucred *, sizeof(*cr), M_CRED, M_WAITOK | M_ZERO); cr->cr_ref = 1; mtx_init(&cr->cr_mtx, "ucred", MTX_DEF); return (cr); } /* * Claim another reference to a ucred structure. */ struct ucred * crhold(cr) struct ucred *cr; { mtx_lock(&cr->cr_mtx); cr->cr_ref++; mtx_unlock(&cr->cr_mtx); return (cr); } /* * Free a cred structure. * Throws away space when ref count gets to 0. */ void crfree(cr) struct ucred *cr; { mtx_lock(&cr->cr_mtx); KASSERT(cr->cr_ref > 0, ("bad ucred refcount: %d", cr->cr_ref)); if (--cr->cr_ref == 0) { mtx_destroy(&cr->cr_mtx); /* * Some callers of crget(), such as nfs_statfs(), * allocate a temporary credential, but don't * allocate a uidinfo structure. */ 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); FREE((caddr_t)cr, M_CRED); } else mtx_unlock(&cr->cr_mtx); } /* * Check to see if this ucred is shared. */ int crshared(cr) struct ucred *cr; { int shared; mtx_lock(&cr->cr_mtx); shared = (cr->cr_ref > 1); mtx_unlock(&cr->cr_mtx); return (shared); } /* * Copy a ucred's contents from a template. Does not block. */ void crcopy(dest, src) struct ucred *dest, *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); } /* * Dup cred struct to a new held one. */ struct ucred * crdup(cr) struct ucred *cr; { struct ucred *newcr; newcr = crget(); crcopy(newcr, cr); return (newcr); } /* * Get login name, if available. */ #ifndef _SYS_SYSPROTO_H_ struct getlogin_args { char *namebuf; u_int namelen; }; #endif /* * MPSAFE */ /* ARGSUSED */ int getlogin(td, uap) struct thread *td; struct getlogin_args *uap; { int error; struct proc *p = td->td_proc; mtx_lock(&Giant); if (uap->namelen > MAXLOGNAME) uap->namelen = MAXLOGNAME; error = copyout((caddr_t) p->p_pgrp->pg_session->s_login, (caddr_t) uap->namebuf, uap->namelen); mtx_unlock(&Giant); return(error); } /* * Set login name. */ #ifndef _SYS_SYSPROTO_H_ struct setlogin_args { char *namebuf; }; #endif /* * MPSAFE */ /* ARGSUSED */ int setlogin(td, uap) struct thread *td; struct setlogin_args *uap; { struct proc *p = td->td_proc; int error; char logintmp[MAXLOGNAME]; mtx_lock(&Giant); if ((error = suser_xxx(0, p, PRISON_ROOT)) != 0) goto done2; error = copyinstr((caddr_t) uap->namebuf, (caddr_t) logintmp, sizeof(logintmp), (size_t *)0); if (error == ENAMETOOLONG) error = EINVAL; else if (!error) (void)memcpy(p->p_pgrp->pg_session->s_login, logintmp, sizeof(logintmp)); done2: mtx_unlock(&Giant); return (error); } void setsugid(p) struct proc *p; { 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(newcred, euid) struct ucred *newcred; uid_t euid; { newcred->cr_uid = euid; uifree(newcred->cr_uidinfo); newcred->cr_uidinfo = uifind(euid); } /*- * 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(newcred, 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(newcred, ruid) struct ucred *newcred; uid_t ruid; { (void)chgproccnt(newcred->cr_ruidinfo, -1, 0); newcred->cr_ruid = ruid; uifree(newcred->cr_ruidinfo); newcred->cr_ruidinfo = uifind(ruid); (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(newcred, 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(newcred, 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(newcred, svgid) struct ucred *newcred; gid_t svgid; { newcred->cr_svgid = svgid; }