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7d8f809f00
freebsd/sys/kern/kern_prot.c
Robert Watson 87fce2bb96 o When performing a securelevel check as part of securelevel_ge() or 
securelevel_gt(), determine first if a local securelevel exists --
  if so, perform the check based on imax(local, global).  Otherwise,
  simply use the global value.
o Note: even though local securelevels might lag below the global one,
  if the global value is updated to higher than local values, maximum
  will still be used, making the global dominant even if there is local
  lag.

Obtained from:	TrustedBSD Project
2001-09-26 20:41:48 +00:00

1836 lines
39 KiB
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/*
* Copyright (c) 1982, 1986, 1989, 1990, 1991, 1993
* The Regents of the University of California. All rights reserved.
* Copyright (c) 2000, 2001 Robert N. M. Watson. 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.
*
* 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_global.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/acct.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/sysproto.h>
#include <sys/malloc.h>
#include <sys/pioctl.h>
#include <sys/resourcevar.h>
#include <sys/sysctl.h>
#include <sys/jail.h>
static MALLOC_DEFINE(M_CRED, "cred", "credentials");
SYSCTL_NODE(_kern, OID_AUTO, security, CTLFLAG_RW, 0,
"Kernel security policy");
#ifndef _SYS_SYSPROTO_H_
struct getpid_args {
int dummy;
};
#endif
/*
* getpid
*/
/*
* MPSAFE
*/
/* ARGSUSED */
int
getpid(td, uap)
struct thread *td;
struct getpid_args *uap;
{
struct proc *p = td->td_proc;
mtx_lock(&Giant);
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);
return (0);
}
/*
* getppid
*/
#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;
mtx_lock(&Giant);
PROC_LOCK(p);
td->td_retval[0] = p->p_pptr->p_pid;
PROC_UNLOCK(p);
mtx_unlock(&Giant);
return (0);
}
/*
* Get process group ID; note that POSIX getpgrp takes no parameter
*
* MP SAFE
*/
#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 = 0;
mtx_lock(&Giant);
if (uap->pid == 0)
td->td_retval[0] = p->p_pgrp->pg_id;
else {
if ((pt = pfind(uap->pid)) == NULL) {
error = ESRCH;
goto done2;
}
if ((error = p_cansee(p, pt))) {
PROC_UNLOCK(pt);
goto done2;
}
td->td_retval[0] = pt->p_pgrp->pg_id;
PROC_UNLOCK(pt);
}
done2:
mtx_unlock(&Giant);
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 = 0;
mtx_lock(&Giant);
if (uap->pid == 0) {
td->td_retval[0] = p->p_session->s_sid;
} else {
if ((pt = pfind(uap->pid)) == NULL) {
error = ESRCH;
goto done2;
}
if ((error = p_cansee(p, pt))) {
PROC_UNLOCK(pt);
goto done2;
}
td->td_retval[0] = pt->p_session->s_sid;
PROC_UNLOCK(pt);
}
done2:
mtx_unlock(&Giant);
return (error);
}
/*
* getuid() - MP SAFE
*/
#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);
}
/*
* geteuid() - MP SAFE
*/
#ifndef _SYS_SYSPROTO_H_
struct geteuid_args {
int dummy;
};
#endif
/* 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);
}
/*
* getgid() - MP SAFE
*/
#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 = 0;
mtx_lock(&Giant);
cred = p->p_ucred;
if ((ngrp = uap->gidsetsize) == 0) {
td->td_retval[0] = cred->cr_ngroups;
error = 0;
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);
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:
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 = 0;
uid = uap->uid;
oldcred = p->p_ucred;
mtx_lock(&Giant);
/*
* 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 uid's 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)))
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 = 0;
euid = uap->euid;
mtx_lock(&Giant);
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))) {
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 = 0;
gid = uap->gid;
mtx_lock(&Giant);
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))) {
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 = 0;
egid = uap->egid;
mtx_lock(&Giant);
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))) {
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;
mtx_lock(&Giant);
ngrp = uap->gidsetsize;
oldcred = p->p_ucred;
if ((error = suser_xxx(oldcred, NULL, PRISON_ROOT)))
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 ruid, euid;
int error = 0;
ruid = uap->ruid;
euid = uap->euid;
mtx_lock(&Giant);
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 rgid, egid;
int error = 0;
rgid = uap->rgid;
egid = uap->egid;
mtx_lock(&Giant);
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 ruid, euid, suid;
int error;
ruid = uap->ruid;
euid = uap->euid;
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 rgid, egid, sgid;
int error;
rgid = uap->rgid;
egid = uap->egid;
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
/* 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 = 0;
mtx_lock(&Giant);
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, 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)
cred = proc->p_ucred;
if (cred->cr_uid != 0)
return (EPERM);
if (jailed(cred) && !(flag & PRISON_ROOT))
return (EPERM);
return (0);
}
/*
* Test (local, globale) securelevel values against passed required
* securelevel. _gt implements (level > securelevel), and _ge implements
* (level >= securelevel). Returns 0 oer EPERM.
*
* 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)
{
if (cr == NULL) {
printf("securelevel_gt: cr is NULL\n");
if (level > securelevel)
return (0);
else
return (EPERM);
} else if (cr->cr_prison == NULL) {
if (level > securelevel)
return (0);
else
return (EPERM);
} else {
if (level > imax(cr->cr_prison->pr_securelevel, securelevel))
return (0);
else
return (EPERM);
}
}
int
securelevel_ge(struct ucred *cr, int level)
{
if (cr == NULL) {
printf("securelevel_ge: cr is NULL\n");
if (level >= securelevel)
return (0);
else
return (EPERM);
} if (cr->cr_prison == NULL) {
if (level >= securelevel)
return (0);
else
return (EPERM);
} else {
if (level >= imax(cr->cr_prison->pr_securelevel, securelevel))
return (0);
else
return (EPERM);
}
}
/*-
* 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 be immutable credentials
* u1 and u2 must be valid for the lifetime of 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 (!ps_showallprocs && 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_xxx(0, p1, CAP_SYS_NICE, PRISON_ROOT))
return (0);
#endif
return (EPERM);
}
/*
* The kern_unprivileged_procdebug_permitted 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?
*/
static int kern_unprivileged_procdebug_permitted = 1;
SYSCTL_INT(_kern_security, OID_AUTO, unprivileged_procdebug_permitted,
CTLFLAG_RW, &kern_unprivileged_procdebug_permitted, 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 error;
if ((error = prison_check(p1->p_ucred, p2->p_ucred)))
return (error);
/*
* Not owned by you, has done setuid (unless you're root).
* XXX add a CAP_SYS_PTRACE here?
*/
if (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 ||
p2->p_flag & P_SUGID || !kern_unprivileged_procdebug_permitted) {
if ((error = suser_xxx(0, p1, PRISON_ROOT)) != 0)
return (error);
}
/* can't trace init when securelevel > 0 */
if (p2->p_pid == 1) {
error = securelevel_gt(p1->p_ucred, 0);
if (error)
return (error);
}
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.
*/
void
crhold(cr)
struct ucred *cr;
{
mtx_lock(&cr->cr_mtx);
cr->cr_ref++;
mtx_unlock(&(cr)->cr_mtx);
}
/*
* 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);
}
}
/*
* Copy cred structure to a new one and free the old one.
*/
struct ucred *
crcopy(cr)
struct ucred *cr;
{
struct ucred *newcr;
mtx_lock(&cr->cr_mtx);
if (cr->cr_ref == 1) {
mtx_unlock(&cr->cr_mtx);
return (cr);
}
mtx_unlock(&cr->cr_mtx);
newcr = crdup(cr);
crfree(cr);
return (newcr);
}
/*
* Dup cred struct to a new held one.
*/
struct ucred *
crdup(cr)
struct ucred *cr;
{
struct ucred *newcr;
MALLOC(newcr, struct ucred *, sizeof(*cr), M_CRED, M_WAITOK);
*newcr = *cr;
mtx_init(&newcr->cr_mtx, "ucred", MTX_DEF);
uihold(newcr->cr_uidinfo);
uihold(newcr->cr_ruidinfo);
if (jailed(newcr))
prison_hold(newcr->cr_prison);
newcr->cr_ref = 1;
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)))
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;
}
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