freebsd-skq/sys/kern/kern_prot.c

893 lines
20 KiB
C

/*
* 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
* $Id: kern_prot.c,v 1.41 1998/11/09 15:07:42 truckman Exp $
*/
/*
* System calls related to processes and protection
*/
#include "opt_compat.h"
#include <sys/param.h>
#include <sys/acct.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/unistd.h>
#include <sys/pioctl.h>
static MALLOC_DEFINE(M_CRED, "cred", "credentials");
#ifndef _SYS_SYSPROTO_H_
struct getpid_args {
int dummy;
};
#endif
/* 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)
p->p_retval[1] = p->p_pptr->p_pid;
#endif
return (0);
}
#ifndef _SYS_SYSPROTO_H_
struct getppid_args {
int dummy;
};
#endif
/* ARGSUSED */
int
getppid(p, uap)
struct proc *p;
struct getppid_args *uap;
{
p->p_retval[0] = p->p_pptr->p_pid;
return (0);
}
/* Get process group ID; note that POSIX getpgrp takes no parameter */
#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;
{
if (uap->pid == 0)
goto found;
if ((p == pfind(uap->pid)) == 0)
return ESRCH;
found:
p->p_retval[0] = p->p_pgrp->pg_id;
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;
{
if (uap->pid == 0)
goto found;
if ((p == pfind(uap->pid)) == 0)
return ESRCH;
found:
p->p_retval[0] = p->p_session->s_sid;
return 0;
}
#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_cred->p_ruid;
#if defined(COMPAT_43) || defined(COMPAT_SUNOS)
p->p_retval[1] = p->p_ucred->cr_uid;
#endif
return (0);
}
#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);
}
#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_cred->p_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;
{
register struct pcred *pc = p->p_cred;
register u_int ngrp;
int error;
if ((ngrp = uap->gidsetsize) == 0) {
p->p_retval[0] = pc->pc_ucred->cr_ngroups;
return (0);
}
if (ngrp < pc->pc_ucred->cr_ngroups)
return (EINVAL);
ngrp = pc->pc_ucred->cr_ngroups;
if ((error = copyout((caddr_t)pc->pc_ucred->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 */
if (uap->pgid < 0)
return (EINVAL);
if (uap->pid != 0 && uap->pid != curp->p_pid) {
if ((targp = pfind(uap->pid)) == 0 || !inferior(targp))
return (ESRCH);
if (targp->p_pgrp == NULL || targp->p_session != curp->p_session)
return (EPERM);
if (targp->p_flag & P_EXEC)
return (EACCES);
} else
targp = curp;
if (SESS_LEADER(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)
return (EPERM);
return (enterpgrp(targp, uap->pgid, 0));
}
/*
* Use the clause in B.4.2.2 that allows setuid/setgid to be 4.2/4.3BSD
* compatable. 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;
{
register struct pcred *pc = p->p_cred;
register uid_t uid;
int error;
/*
* 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 compatable 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")
*/
uid = uap->uid;
if (uid != pc->p_ruid && /* allow setuid(getuid()) */
#ifdef _POSIX_SAVED_IDS
uid != pc->p_svuid && /* allow setuid(saved gid) */
#endif
#ifdef POSIX_APPENDIX_B_4_2_2 /* Use BSD-compat clause from B.4.2.2 */
uid != pc->pc_ucred->cr_uid && /* allow setuid(geteuid()) */
#endif
(error = suser(pc->pc_ucred, &p->p_acflag)))
return (error);
#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 == pc->pc_ucred->cr_uid ||
#endif
suser(pc->pc_ucred, &p->p_acflag) == 0) /* we are using privs */
#endif
{
/*
* Transfer proc count to new user.
*/
if (uid != pc->p_ruid) {
(void)chgproccnt(pc->p_ruid, -1);
(void)chgproccnt(uid, 1);
}
/*
* Set real uid
*/
if (uid != pc->p_ruid) {
pc->p_ruid = 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 (pc->p_svuid != uid) {
pc->p_svuid = uid;
setsugid(p);
}
}
/*
* In all permitted cases, we are changing the euid.
* Copy credentials so other references do not see our changes.
*/
if (pc->pc_ucred->cr_uid != uid) {
pc->pc_ucred = crcopy(pc->pc_ucred);
pc->pc_ucred->cr_uid = uid;
setsugid(p);
}
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;
{
register struct pcred *pc = p->p_cred;
register uid_t euid;
int error;
euid = uap->euid;
if (euid != pc->p_ruid && /* allow seteuid(getuid()) */
euid != pc->p_svuid && /* allow seteuid(saved uid) */
(error = suser(pc->pc_ucred, &p->p_acflag)))
return (error);
/*
* Everything's okay, do it. Copy credentials so other references do
* not see our changes.
*/
if (pc->pc_ucred->cr_uid != euid) {
pc->pc_ucred = crcopy(pc->pc_ucred);
pc->pc_ucred->cr_uid = euid;
setsugid(p);
}
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;
{
register struct pcred *pc = p->p_cred;
register gid_t gid;
int error;
/*
* 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 compatable 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.
*/
gid = uap->gid;
if (gid != pc->p_rgid && /* allow setgid(getgid()) */
#ifdef _POSIX_SAVED_IDS
gid != pc->p_svgid && /* allow setgid(saved gid) */
#endif
#ifdef POSIX_APPENDIX_B_4_2_2 /* Use BSD-compat clause from B.4.2.2 */
gid != pc->pc_ucred->cr_groups[0] && /* allow setgid(getegid()) */
#endif
(error = suser(pc->pc_ucred, &p->p_acflag)))
return (error);
#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 == pc->pc_ucred->cr_groups[0] ||
#endif
suser(pc->pc_ucred, &p->p_acflag) == 0) /* we are using privs */
#endif
{
/*
* Set real gid
*/
if (pc->p_rgid != gid) {
pc->p_rgid = 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 (pc->p_svgid != gid) {
pc->p_svgid = gid;
setsugid(p);
}
}
/*
* In all cases permitted cases, we are changing the egid.
* Copy credentials so other references do not see our changes.
*/
if (pc->pc_ucred->cr_groups[0] != gid) {
pc->pc_ucred = crcopy(pc->pc_ucred);
pc->pc_ucred->cr_groups[0] = gid;
setsugid(p);
}
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;
{
register struct pcred *pc = p->p_cred;
register gid_t egid;
int error;
egid = uap->egid;
if (egid != pc->p_rgid && /* allow setegid(getgid()) */
egid != pc->p_svgid && /* allow setegid(saved gid) */
(error = suser(pc->pc_ucred, &p->p_acflag)))
return (error);
if (pc->pc_ucred->cr_groups[0] != egid) {
pc->pc_ucred = crcopy(pc->pc_ucred);
pc->pc_ucred->cr_groups[0] = egid;
setsugid(p);
}
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;
{
register struct pcred *pc = p->p_cred;
register u_int ngrp;
int error;
if ((error = suser(pc->pc_ucred, &p->p_acflag)))
return (error);
ngrp = uap->gidsetsize;
if (ngrp > NGROUPS)
return (EINVAL);
/*
* XXX A little bit lazy here. We could test if anything has
* changed before crcopy() and setting P_SUGID.
*/
pc->pc_ucred = crcopy(pc->pc_ucred);
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.
*/
pc->pc_ucred->cr_ngroups = 1;
} else {
if ((error = copyin((caddr_t)uap->gidset,
(caddr_t)pc->pc_ucred->cr_groups, ngrp * sizeof(gid_t))))
return (error);
pc->pc_ucred->cr_ngroups = ngrp;
}
setsugid(p);
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;
{
register struct pcred *pc = p->p_cred;
register uid_t ruid, euid;
int error;
ruid = uap->ruid;
euid = uap->euid;
if ((ruid != (uid_t)-1 && ruid != pc->p_ruid && ruid != pc->p_svuid ||
euid != (uid_t)-1 && euid != pc->pc_ucred->cr_uid &&
euid != pc->p_ruid && euid != pc->p_svuid) &&
(error = suser(pc->pc_ucred, &p->p_acflag)))
return (error);
if (euid != (uid_t)-1 && pc->pc_ucred->cr_uid != euid) {
pc->pc_ucred = crcopy(pc->pc_ucred);
pc->pc_ucred->cr_uid = euid;
setsugid(p);
}
if (ruid != (uid_t)-1 && pc->p_ruid != ruid) {
(void)chgproccnt(pc->p_ruid, -1);
(void)chgproccnt(ruid, 1);
pc->p_ruid = ruid;
setsugid(p);
}
if ((ruid != (uid_t)-1 || pc->pc_ucred->cr_uid != pc->p_ruid) &&
pc->p_svuid != pc->pc_ucred->cr_uid) {
pc->p_svuid = pc->pc_ucred->cr_uid;
setsugid(p);
}
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;
{
register struct pcred *pc = p->p_cred;
register gid_t rgid, egid;
int error;
rgid = uap->rgid;
egid = uap->egid;
if ((rgid != (gid_t)-1 && rgid != pc->p_rgid && rgid != pc->p_svgid ||
egid != (gid_t)-1 && egid != pc->pc_ucred->cr_groups[0] &&
egid != pc->p_rgid && egid != pc->p_svgid) &&
(error = suser(pc->pc_ucred, &p->p_acflag)))
return (error);
if (egid != (gid_t)-1 && pc->pc_ucred->cr_groups[0] != egid) {
pc->pc_ucred = crcopy(pc->pc_ucred);
pc->pc_ucred->cr_groups[0] = egid;
setsugid(p);
}
if (rgid != (gid_t)-1 && pc->p_rgid != rgid) {
pc->p_rgid = rgid;
setsugid(p);
}
if ((rgid != (gid_t)-1 || pc->pc_ucred->cr_groups[0] != pc->p_rgid) &&
pc->p_svgid != pc->pc_ucred->cr_groups[0]) {
pc->p_svgid = pc->pc_ucred->cr_groups[0];
setsugid(p);
}
return (0);
}
#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.
*/
if (p->p_flag & P_SUGID)
return (1);
return (0);
}
/*
* Check if gid is a member of the group set.
*/
int
groupmember(gid, cred)
gid_t gid;
register 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);
}
/*
* 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(cred, acflag)
struct ucred *cred;
u_short *acflag;
{
if (cred->cr_uid == 0) {
if (acflag)
*acflag |= ASU;
return (0);
}
return (EPERM);
}
/*
* Allocate a zeroed cred structure.
*/
struct ucred *
crget()
{
register struct ucred *cr;
MALLOC(cr, struct ucred *, sizeof(*cr), M_CRED, M_WAITOK);
bzero((caddr_t)cr, sizeof(*cr));
cr->cr_ref = 1;
return (cr);
}
/*
* Free a cred structure.
* Throws away space when ref count gets to 0.
*/
void
crfree(cr)
struct ucred *cr;
{
if (--cr->cr_ref == 0)
FREE((caddr_t)cr, M_CRED);
}
/*
* Copy cred structure to a new one and free the old one.
*/
struct ucred *
crcopy(cr)
struct ucred *cr;
{
struct ucred *newcr;
if (cr->cr_ref == 1)
return (cr);
newcr = crget();
*newcr = *cr;
crfree(cr);
newcr->cr_ref = 1;
return (newcr);
}
/*
* Dup cred struct to a new held one.
*/
struct ucred *
crdup(cr)
struct ucred *cr;
{
struct ucred *newcr;
newcr = crget();
*newcr = *cr;
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(p->p_ucred, &p->p_acflag)))
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;
}