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0ef5652e27
freebsd-nq/sys/kern/kern_prot.c
Robert Watson 0ef5652e27 o Introduce new kern.security sysctl tree for kernel security policy 
MIB entries.
o Relocate kern.suser_permitted to kern.security.suser_permitted.
o Introduce new kern.security.unprivileged_procdebug_permitted, which
  (when set to 0) prevents processes without privilege from performing
  a variety of inter-process debugging activities.  The default is 1,
  to provide current behavior.

  This feature allows "hardened" systems to disable access to debugging
  facilities, which have been associated with a number of past security
  vulnerabilities.  Previously, while procfs could be unmounted, other
  in-kernel facilities (such as ptrace()) were still available.  This
  setting should not be modified on normal development systems, as it
  will result in frustration.  Some utilities respond poorly to
  failing to get the debugging access they require, and error response
  by these utilities may be improved in the future in the name of
  beautification.

  Note that there are currently some odd interactions with some
  facilities, which will need to be resolved before this should be used
  in production, including odd interactions with truss and ktrace.
  Note also that currently, tracing is permitted on the current process
  regardless of this flag, for compatibility with previous
  authorization code in various facilities, but that will probably
  change (and resolve the odd interactions).

Obtained from:	TrustedBSD Project
2001-07-31 15:48:21 +00:00

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/*
* 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.
*
* 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 - MP SAFE
*/
/* ARGSUSED */
int
getpid(p, uap)
struct proc *p;
struct getpid_args *uap;
{
p->p_retval[0] = p->p_pid;
#if defined(COMPAT_43) || defined(COMPAT_SUNOS)
PROC_LOCK(p);
p->p_retval[1] = p->p_pptr->p_pid;
PROC_UNLOCK(p);
#endif
return (0);
}
/*
* getppid - MP SAFE
*/
#ifndef _SYS_SYSPROTO_H_
struct getppid_args {
int dummy;
};
#endif
/* ARGSUSED */
int
getppid(p, uap)
struct proc *p;
struct getppid_args *uap;
{
PROC_LOCK(p);
p->p_retval[0] = p->p_pptr->p_pid;
PROC_UNLOCK(p);
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
int
getpgrp(p, uap)
struct proc *p;
struct getpgrp_args *uap;
{
p->p_retval[0] = p->p_pgrp->pg_id;
return (0);
}
/* Get an arbitary pid's process group id */
#ifndef _SYS_SYSPROTO_H_
struct getpgid_args {
pid_t pid;
};
#endif
int
getpgid(p, uap)
struct proc *p;
struct getpgid_args *uap;
{
struct proc *pt;
int error;
if (uap->pid == 0)
p->p_retval[0] = p->p_pgrp->pg_id;
else {
if ((pt = pfind(uap->pid)) == NULL)
return ESRCH;
if ((error = p_cansee(p, pt))) {
PROC_UNLOCK(pt);
return (error);
}
p->p_retval[0] = pt->p_pgrp->pg_id;
PROC_UNLOCK(pt);
}
return 0;
}
/*
* Get an arbitary pid's session id.
*/
#ifndef _SYS_SYSPROTO_H_
struct getsid_args {
pid_t pid;
};
#endif
int
getsid(p, uap)
struct proc *p;
struct getsid_args *uap;
{
struct proc *pt;
int error;
if (uap->pid == 0)
p->p_retval[0] = p->p_session->s_sid;
else {
if ((pt = pfind(uap->pid)) == NULL)
return ESRCH;
if ((error = p_cansee(p, pt))) {
PROC_UNLOCK(pt);
return (error);
}
p->p_retval[0] = pt->p_session->s_sid;
PROC_UNLOCK(pt);
}
return 0;
}
/*
* getuid() - MP SAFE
*/
#ifndef _SYS_SYSPROTO_H_
struct getuid_args {
int dummy;
};
#endif
/* ARGSUSED */
int
getuid(p, uap)
struct proc *p;
struct getuid_args *uap;
{
p->p_retval[0] = p->p_ucred->cr_ruid;
#if defined(COMPAT_43) || defined(COMPAT_SUNOS)
p->p_retval[1] = p->p_ucred->cr_uid;
#endif
return (0);
}
/*
* geteuid() - MP SAFE
*/
#ifndef _SYS_SYSPROTO_H_
struct geteuid_args {
int dummy;
};
#endif
/* ARGSUSED */
int
geteuid(p, uap)
struct proc *p;
struct geteuid_args *uap;
{
p->p_retval[0] = p->p_ucred->cr_uid;
return (0);
}
/*
* getgid() - MP SAFE
*/
#ifndef _SYS_SYSPROTO_H_
struct getgid_args {
int dummy;
};
#endif
/* ARGSUSED */
int
getgid(p, uap)
struct proc *p;
struct getgid_args *uap;
{
p->p_retval[0] = p->p_ucred->cr_rgid;
#if defined(COMPAT_43) || defined(COMPAT_SUNOS)
p->p_retval[1] = p->p_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
/* ARGSUSED */
int
getegid(p, uap)
struct proc *p;
struct getegid_args *uap;
{
p->p_retval[0] = p->p_ucred->cr_groups[0];
return (0);
}
#ifndef _SYS_SYSPROTO_H_
struct getgroups_args {
u_int gidsetsize;
gid_t *gidset;
};
#endif
int
getgroups(p, uap)
struct proc *p;
register struct getgroups_args *uap;
{
struct ucred *cred = p->p_ucred;
u_int ngrp;
int error;
if ((ngrp = uap->gidsetsize) == 0) {
p->p_retval[0] = cred->cr_ngroups;
return (0);
}
if (ngrp < cred->cr_ngroups)
return (EINVAL);
ngrp = cred->cr_ngroups;
if ((error = copyout((caddr_t)cred->cr_groups,
(caddr_t)uap->gidset, ngrp * sizeof(gid_t))))
return (error);
p->p_retval[0] = ngrp;
return (0);
}
#ifndef _SYS_SYSPROTO_H_
struct setsid_args {
int dummy;
};
#endif
/* ARGSUSED */
int
setsid(p, uap)
register struct proc *p;
struct setsid_args *uap;
{
if (p->p_pgid == p->p_pid || pgfind(p->p_pid)) {
return (EPERM);
} else {
(void)enterpgrp(p, p->p_pid, 1);
p->p_retval[0] = p->p_pid;
return (0);
}
}
/*
* 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
/* ARGSUSED */
int
setpgid(curp, uap)
struct proc *curp;
register struct setpgid_args *uap;
{
register struct proc *targp; /* target process */
register struct pgrp *pgrp; /* target pgrp */
int error;
if (uap->pgid < 0)
return (EINVAL);
if (uap->pid != 0 && uap->pid != curp->p_pid) {
if ((targp = pfind(uap->pid)) == NULL || !inferior(targp)) {
if (targp)
PROC_UNLOCK(targp);
return (ESRCH);
}
if ((error = p_cansee(curproc, targp))) {
PROC_UNLOCK(targp);
return (error);
}
if (targp->p_pgrp == NULL ||
targp->p_session != curp->p_session) {
PROC_UNLOCK(targp);
return (EPERM);
}
if (targp->p_flag & P_EXEC) {
PROC_UNLOCK(targp);
return (EACCES);
}
} else {
targp = curp;
PROC_LOCK(curp); /* XXX: not needed */
}
if (SESS_LEADER(targp)) {
PROC_UNLOCK(targp);
return (EPERM);
}
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);
return (EPERM);
}
/* XXX: We should probably hold the lock across enterpgrp. */
PROC_UNLOCK(targp);
return (enterpgrp(targp, uap->pgid, 0));
}
/*
* 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
/* ARGSUSED */
int
setuid(p, uap)
struct proc *p;
struct setuid_args *uap;
{
struct ucred *newcred, *oldcred;
uid_t uid;
int error;
uid = uap->uid;
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 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)))
return (error);
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);
return (0);
}
#ifndef _SYS_SYSPROTO_H_
struct seteuid_args {
uid_t euid;
};
#endif
/* ARGSUSED */
int
seteuid(p, uap)
struct proc *p;
struct seteuid_args *uap;
{
struct ucred *newcred, *oldcred;
uid_t euid;
int error;
euid = uap->euid;
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)))
return (error);
/*
* 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);
return (0);
}
#ifndef _SYS_SYSPROTO_H_
struct setgid_args {
gid_t gid;
};
#endif
/* ARGSUSED */
int
setgid(p, uap)
struct proc *p;
struct setgid_args *uap;
{
struct ucred *newcred, *oldcred;
gid_t gid;
int error;
gid = uap->gid;
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)))
return (error);
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);
return (0);
}
#ifndef _SYS_SYSPROTO_H_
struct setegid_args {
gid_t egid;
};
#endif
/* ARGSUSED */
int
setegid(p, uap)
struct proc *p;
struct setegid_args *uap;
{
struct ucred *newcred, *oldcred;
gid_t egid;
int error;
egid = uap->egid;
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)))
return (error);
newcred = crdup(oldcred);
if (oldcred->cr_groups[0] != egid) {
change_egid(newcred, egid);
setsugid(p);
}
p->p_ucred = newcred;
crfree(oldcred);
return (0);
}
#ifndef _SYS_SYSPROTO_H_
struct setgroups_args {
u_int gidsetsize;
gid_t *gidset;
};
#endif
/* ARGSUSED */
int
setgroups(p, uap)
struct proc *p;
struct setgroups_args *uap;
{
struct ucred *newcred, *oldcred;
u_int ngrp;
int error;
ngrp = uap->gidsetsize;
oldcred = p->p_ucred;
if ((error = suser_xxx(oldcred, NULL, PRISON_ROOT)))
return (error);
if (ngrp > NGROUPS)
return (EINVAL);
/*
* 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);
return (error);
}
newcred->cr_ngroups = ngrp;
}
setsugid(p);
p->p_ucred = newcred;
crfree(oldcred);
return (0);
}
#ifndef _SYS_SYSPROTO_H_
struct setreuid_args {
uid_t ruid;
uid_t euid;
};
#endif
/* ARGSUSED */
int
setreuid(p, uap)
register struct proc *p;
struct setreuid_args *uap;
{
struct ucred *newcred, *oldcred;
uid_t ruid, euid;
int error;
ruid = uap->ruid;
euid = uap->euid;
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)
return (error);
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);
return (0);
}
#ifndef _SYS_SYSPROTO_H_
struct setregid_args {
gid_t rgid;
gid_t egid;
};
#endif
/* ARGSUSED */
int
setregid(p, uap)
register struct proc *p;
struct setregid_args *uap;
{
struct ucred *newcred, *oldcred;
gid_t rgid, egid;
int error;
rgid = uap->rgid;
egid = uap->egid;
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)
return (error);
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);
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
/* ARGSUSED */
int
setresuid(p, uap)
register struct proc *p;
struct setresuid_args *uap;
{
struct ucred *newcred, *oldcred;
uid_t ruid, euid, suid;
int error;
ruid = uap->ruid;
euid = uap->euid;
suid = uap->suid;
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)
return (error);
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);
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
/* ARGSUSED */
int
setresgid(p, uap)
register struct proc *p;
struct setresgid_args *uap;
{
struct ucred *newcred, *oldcred;
gid_t rgid, egid, sgid;
int error;
rgid = uap->rgid;
egid = uap->egid;
sgid = uap->sgid;
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)
return (error);
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);
return (0);
}
#ifndef _SYS_SYSPROTO_H_
struct getresuid_args {
uid_t *ruid;
uid_t *euid;
uid_t *suid;
};
#endif
/* ARGSUSED */
int
getresuid(p, uap)
register struct proc *p;
struct getresuid_args *uap;
{
struct ucred *cred = p->p_ucred;
int error1 = 0, error2 = 0, error3 = 0;
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));
return error1 ? error1 : (error2 ? error2 : error3);
}
#ifndef _SYS_SYSPROTO_H_
struct getresgid_args {
gid_t *rgid;
gid_t *egid;
gid_t *sgid;
};
#endif
/* ARGSUSED */
int
getresgid(p, uap)
register struct proc *p;
struct getresgid_args *uap;
{
struct ucred *cred = p->p_ucred;
int error1 = 0, error2 = 0, error3 = 0;
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));
return error1 ? error1 : (error2 ? error2 : error3);
}
#ifndef _SYS_SYSPROTO_H_
struct issetugid_args {
int dummy;
};
#endif
/* ARGSUSED */
int
issetugid(p, uap)
register struct proc *p;
struct issetugid_args *uap;
{
/*
* 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.
*/
p->p_retval[0] = (p->p_flag & P_SUGID) ? 1 : 0;
return (0);
}
int
__setugid(p, uap)
struct proc *p;
struct __setugid_args *uap;
{
#ifdef REGRESSION
switch (uap->flag) {
case 0:
p->p_flag &= ~P_SUGID;
return (0);
case 1:
p->p_flag |= P_SUGID;
return (0);
default:
return (EINVAL);
}
#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);
}
static int suser_permitted = 1;
SYSCTL_INT(_kern_security, OID_AUTO, suser_permitted, CTLFLAG_RW,
&suser_permitted, 0, "processes with uid 0 have privilege");
/*
* Test whether the specified credentials imply "super-user"
* privilege; if so, and we have accounting info, set the flag
* indicating use of super-powers.
* Returns 0 or error.
*/
int
suser(p)
struct proc *p;
{
return suser_xxx(0, p, 0);
}
int
suser_xxx(cred, proc, flag)
struct ucred *cred;
struct proc *proc;
int flag;
{
if (!suser_permitted)
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);
}
/*
* u_cansee(u1, u2): determine if u1 "can see" the subject specified by u2
* Arguments: imutable credentials u1, u2
* Returns: 0 for permitted, an errno value otherwise
* Locks: none
* References: 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
u_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);
}
int
p_cansee(struct proc *p1, struct proc *p2)
{
/* Wrap u_cansee() for all functionality. */
return (u_cansee(p1->p_ucred, p2->p_ucred));
}
/*
* Can process p1 send the signal signum to process p2?
*/
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 uid semantics depend on the status of the P_SUGID
* bit on the target process. If the bit is set, then more
* restricted signal sets are permitted.
*/
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:
break;
default:
/* Not permitted, try privilege. */
error = suser_xxx(NULL, p1, PRISON_ROOT);
if (error)
return (error);
}
}
/*
* Generally, the object 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);
}
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))
return (0);
#ifdef CAPABILITIES
if (!cap_check_xxx(0, p1, CAP_SYS_NICE, PRISON_ROOT))
return (0);
#endif
return (EPERM);
}
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");
int
p_candebug(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);
/* not owned by you, has done setuid (unless you're root) */
/* 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)))
return (error);
/* can't trace init when securelevel > 0 */
if (securelevel > 0 && p2->p_pid == 1)
return (EPERM);
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
/* ARGSUSED */
int
getlogin(p, uap)
struct proc *p;
struct getlogin_args *uap;
{
if (uap->namelen > MAXLOGNAME)
uap->namelen = MAXLOGNAME;
return (copyout((caddr_t) p->p_pgrp->pg_session->s_login,
(caddr_t) uap->namebuf, uap->namelen));
}
/*
* Set login name.
*/
#ifndef _SYS_SYSPROTO_H_
struct setlogin_args {
char *namebuf;
};
#endif
/* ARGSUSED */
int
setlogin(p, uap)
struct proc *p;
struct setlogin_args *uap;
{
int error;
char logintmp[MAXLOGNAME];
if ((error = suser_xxx(0, p, PRISON_ROOT)))
return (error);
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));
return (error);
}
void
setsugid(p)
struct proc *p;
{
p->p_flag |= P_SUGID;
if (!(p->p_pfsflags & PF_ISUGID))
p->p_stops = 0;
}
/*
* change_euid(): 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_egid(): 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_ruid(): 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_rgid(): 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_svuid(): 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_svgid(): 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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