NetBSD/sys/kern/kern_prot.c

751 lines
18 KiB
C

/* $NetBSD: kern_prot.c,v 1.84 2004/05/04 21:27:28 pk Exp $ */
/*
* 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. 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 8.9 (Berkeley) 2/14/95
*/
/*
* System calls related to processes and protection
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_prot.c,v 1.84 2004/05/04 21:27:28 pk Exp $");
#include "opt_compat_43.h"
#include <sys/param.h>
#include <sys/acct.h>
#include <sys/systm.h>
#include <sys/ucred.h>
#include <sys/proc.h>
#include <sys/timeb.h>
#include <sys/times.h>
#include <sys/pool.h>
#include <sys/syslog.h>
#include <sys/resourcevar.h>
#include <sys/mount.h>
#include <sys/sa.h>
#include <sys/syscallargs.h>
POOL_INIT(cred_pool, sizeof(struct ucred), 0, 0, 0, "credpl",
&pool_allocator_nointr);
int sys_getpid(struct lwp *, void *, register_t *);
int sys_getpid_with_ppid(struct lwp *, void *, register_t *);
int sys_getuid(struct lwp *, void *, register_t *);
int sys_getuid_with_euid(struct lwp *, void *, register_t *);
int sys_getgid(struct lwp *, void *, register_t *);
int sys_getgid_with_egid(struct lwp *, void *, register_t *);
/* ARGSUSED */
int
sys_getpid(struct lwp *l, void *v, register_t *retval)
{
struct proc *p = l->l_proc;
*retval = p->p_pid;
return (0);
}
/* ARGSUSED */
int
sys_getpid_with_ppid(struct lwp *l, void *v, register_t *retval)
{
struct proc *p = l->l_proc;
retval[0] = p->p_pid;
retval[1] = p->p_pptr->p_pid;
return (0);
}
/* ARGSUSED */
int
sys_getppid(struct lwp *l, void *v, register_t *retval)
{
struct proc *p = l->l_proc;
*retval = p->p_pptr->p_pid;
return (0);
}
/* Get process group ID; note that POSIX getpgrp takes no parameter */
int
sys_getpgrp(struct lwp *l, void *v, register_t *retval)
{
struct proc *p = l->l_proc;
*retval = p->p_pgrp->pg_id;
return (0);
}
/*
* Return the process group ID of the session leader (session ID)
* for the specified process.
*/
int
sys_getsid(struct lwp *l, void *v, register_t *retval)
{
struct sys_getsid_args /* {
syscalldarg(pid_t) pid;
} */ *uap = v;
struct proc *p = l->l_proc;
if (SCARG(uap, pid) == 0)
goto found;
if ((p = pfind(SCARG(uap, pid))) == 0)
return (ESRCH);
found:
*retval = p->p_session->s_sid;
return (0);
}
int
sys_getpgid(struct lwp *l, void *v, register_t *retval)
{
struct sys_getpgid_args /* {
syscallarg(pid_t) pid;
} */ *uap = v;
struct proc *p = l->l_proc;
if (SCARG(uap, pid) == 0)
goto found;
if ((p = pfind(SCARG(uap, pid))) == 0)
return (ESRCH);
found:
*retval = p->p_pgid;
return (0);
}
/* ARGSUSED */
int
sys_getuid(struct lwp *l, void *v, register_t *retval)
{
struct proc *p = l->l_proc;
*retval = p->p_cred->p_ruid;
return (0);
}
/* ARGSUSED */
int
sys_getuid_with_euid(struct lwp *l, void *v, register_t *retval)
{
struct proc *p = l->l_proc;
retval[0] = p->p_cred->p_ruid;
retval[1] = p->p_ucred->cr_uid;
return (0);
}
/* ARGSUSED */
int
sys_geteuid(struct lwp *l, void *v, register_t *retval)
{
struct proc *p = l->l_proc;
*retval = p->p_ucred->cr_uid;
return (0);
}
/* ARGSUSED */
int
sys_getgid(struct lwp *l, void *v, register_t *retval)
{
struct proc *p = l->l_proc;
*retval = p->p_cred->p_rgid;
return (0);
}
/* ARGSUSED */
int
sys_getgid_with_egid(struct lwp *l, void *v, register_t *retval)
{
struct proc *p = l->l_proc;
retval[0] = p->p_cred->p_rgid;
retval[1] = p->p_ucred->cr_gid;
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.
*/
/* ARGSUSED */
int
sys_getegid(struct lwp *l, void *v, register_t *retval)
{
struct proc *p = l->l_proc;
*retval = p->p_ucred->cr_gid;
return (0);
}
int
sys_getgroups(struct lwp *l, void *v, register_t *retval)
{
struct sys_getgroups_args /* {
syscallarg(int) gidsetsize;
syscallarg(gid_t *) gidset;
} */ *uap = v;
struct proc *p = l->l_proc;
struct pcred *pc = p->p_cred;
u_int ngrp;
int error;
if (SCARG(uap, gidsetsize) == 0) {
*retval = pc->pc_ucred->cr_ngroups;
return (0);
} else if (SCARG(uap, gidsetsize) < 0)
return (EINVAL);
ngrp = SCARG(uap, gidsetsize);
if (ngrp < pc->pc_ucred->cr_ngroups)
return (EINVAL);
ngrp = pc->pc_ucred->cr_ngroups;
error = copyout((caddr_t)pc->pc_ucred->cr_groups,
(caddr_t)SCARG(uap, gidset), ngrp * sizeof(gid_t));
if (error)
return (error);
*retval = ngrp;
return (0);
}
/* ARGSUSED */
int
sys_setsid(struct lwp *l, void *v, register_t *retval)
{
struct proc *p = l->l_proc;
if (p->p_pgid == p->p_pid || pgfind(p->p_pid)) {
return (EPERM);
} else {
(void)enterpgrp(p, p->p_pid, 1);
*retval = p->p_pid;
return (0);
}
}
/*
* set process group (setpgid/old setpgrp)
*
* caller does setpgid(targpid, targpgid)
*
* pgid must be in valid range (EINVAL)
* 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)
*
* Permission checks now in enterpgrp()
*/
/* ARGSUSED */
int
sys_setpgid(struct lwp *l, void *v, register_t *retval)
{
struct sys_setpgid_args /* {
syscallarg(int) pid;
syscallarg(int) pgid;
} */ *uap = v;
struct proc *curp = l->l_proc;
struct proc *targp; /* target process */
if (SCARG(uap, pgid) < 0)
return EINVAL;
/* XXX MP - there is a horrid race here with targp exiting! */
if (SCARG(uap, pid) != 0 && SCARG(uap, pid) != curp->p_pid) {
targp = pfind(SCARG(uap, pid));
if (targp == NULL)
return ESRCH;
} else
targp = curp;
if (SCARG(uap, pgid) == 0)
SCARG(uap, pgid) = targp->p_pid;
return enterpgrp(targp, SCARG(uap, pgid), 0);
}
/*
* Set real, effective and saved uids to the requested values.
* non-root callers can only ever change uids to values that match
* one of the processes current uid values.
* This is further restricted by the flags argument.
*/
int
do_setresuid(struct lwp *l, uid_t r, uid_t e, uid_t sv, u_int flags)
{
int error;
struct proc *p = l->l_proc;
struct pcred *pcred = p->p_cred;
struct ucred *cred = pcred->pc_ucred;
/* Superuser can do anything it wants to.... */
error = suser(cred, &p->p_acflag);
if (error) {
/* Otherwise check new value is one of the allowed
existing values. */
if (r != -1 && !((flags & ID_R_EQ_R) && r == pcred->p_ruid)
&& !((flags & ID_R_EQ_E) && r == cred->cr_uid)
&& !((flags & ID_R_EQ_S) && r == pcred->p_svuid))
return error;
if (e != -1 && !((flags & ID_E_EQ_R) && e == pcred->p_ruid)
&& !((flags & ID_E_EQ_E) && e == cred->cr_uid)
&& !((flags & ID_E_EQ_S) && e == pcred->p_svuid))
return error;
if (sv != -1 && !((flags & ID_S_EQ_R) && sv == pcred->p_ruid)
&& !((flags & ID_S_EQ_E) && sv == cred->cr_uid)
&& !((flags & ID_S_EQ_S) && sv == pcred->p_svuid))
return error;
}
/* If nothing has changed, short circuit the request */
if ((r == -1 || r == pcred->p_ruid)
&& (e == -1 || e == cred->cr_uid)
&& (sv == -1 || sv == pcred->p_svuid))
/* nothing to do */
return 0;
/* The pcred structure is not actually shared... */
if (r != -1 && r != pcred->p_ruid) {
/* Update count of processes for this user */
(void)chgproccnt(pcred->p_ruid, -1);
(void)chgproccnt(r, 1);
pcred->p_ruid = r;
}
if (sv != -1)
pcred->p_svuid = sv;
if (e != -1 && e != cred->cr_uid) {
/* Update a clone of the current credentials */
pcred->pc_ucred = cred = crcopy(cred);
cred->cr_uid = e;
}
/* Mark process as having changed credentials, stops tracing etc */
p_sugid(p);
return 0;
}
/*
* Set real, effective and saved gids to the requested values.
* non-root callers can only ever change gids to values that match
* one of the processes current gid values.
* This is further restricted by the flags argument.
*/
int
do_setresgid(struct lwp *l, gid_t r, gid_t e, gid_t sv, u_int flags)
{
int error;
struct proc *p = l->l_proc;
struct pcred *pcred = p->p_cred;
struct ucred *cred = pcred->pc_ucred;
/* Superuser can do anything it wants to.... */
error = suser(cred, &p->p_acflag);
if (error) {
/* Otherwise check new value is one of the allowed
existing values. */
if (r != -1 && !((flags & ID_R_EQ_R) && r == pcred->p_rgid)
&& !((flags & ID_R_EQ_E) && r == cred->cr_gid)
&& !((flags & ID_R_EQ_S) && r == pcred->p_svgid))
return error;
if (e != -1 && !((flags & ID_E_EQ_R) && e == pcred->p_rgid)
&& !((flags & ID_E_EQ_E) && e == cred->cr_gid)
&& !((flags & ID_E_EQ_S) && e == pcred->p_svgid))
return error;
if (sv != -1 && !((flags & ID_S_EQ_R) && sv == pcred->p_rgid)
&& !((flags & ID_S_EQ_E) && sv == cred->cr_gid)
&& !((flags & ID_S_EQ_S) && sv == pcred->p_svgid))
return error;
}
/* If nothing has changed, short circuit the request */
if ((r == -1 || r == pcred->p_rgid)
&& (e == -1 || e == cred->cr_gid)
&& (sv == -1 || sv == pcred->p_svgid))
/* nothing to do */
return 0;
/* The pcred structure is not actually shared... */
if (r != -1)
pcred->p_rgid = r;
if (sv != -1)
pcred->p_svgid = sv;
if (e != -1 && e != cred->cr_gid) {
/* Update a clone of the current credentials */
pcred->pc_ucred = cred = crcopy(cred);
cred->cr_gid = e;
}
/* Mark process as having changed credentials, stops tracing etc */
p_sugid(p);
return 0;
}
/* ARGSUSED */
int
sys_setuid(struct lwp *l, void *v, register_t *retval)
{
struct sys_setuid_args /* {
syscallarg(uid_t) uid;
} */ *uap = v;
uid_t uid = SCARG(uap, uid);
return do_setresuid(l, uid, uid, uid,
ID_R_EQ_R | ID_E_EQ_R | ID_S_EQ_R);
}
/* ARGSUSED */
int
sys_seteuid(struct lwp *l, void *v, register_t *retval)
{
struct sys_seteuid_args /* {
syscallarg(uid_t) euid;
} */ *uap = v;
return do_setresuid(l, -1, SCARG(uap, euid), -1, ID_E_EQ_R | ID_E_EQ_S);
}
int
sys_setreuid(struct lwp *l, void *v, register_t *retval)
{
struct sys_setreuid_args /* {
syscallarg(uid_t) ruid;
syscallarg(uid_t) euid;
} */ *uap = v;
struct proc *p = l->l_proc;
uid_t ruid, euid, svuid;
ruid = SCARG(uap, ruid);
euid = SCARG(uap, euid);
if (ruid == -1)
ruid = p->p_cred->p_ruid;
if (euid == -1)
euid = p->p_ucred->cr_uid;
/* Saved uid is set to the new euid if the ruid changed */
svuid = (ruid == p->p_cred->p_ruid) ? -1 : euid;
return do_setresuid(l, ruid, euid, svuid,
ID_R_EQ_R | ID_R_EQ_E |
ID_E_EQ_R | ID_E_EQ_E | ID_E_EQ_S |
ID_S_EQ_R | ID_S_EQ_E | ID_S_EQ_S);
}
/* ARGSUSED */
int
sys_setgid(struct lwp *l, void *v, register_t *retval)
{
struct sys_setgid_args /* {
syscallarg(gid_t) gid;
} */ *uap = v;
gid_t gid = SCARG(uap, gid);
return do_setresgid(l, gid, gid, gid,
ID_R_EQ_R | ID_E_EQ_R | ID_S_EQ_R);
}
/* ARGSUSED */
int
sys_setegid(struct lwp *l, void *v, register_t *retval)
{
struct sys_setegid_args /* {
syscallarg(gid_t) egid;
} */ *uap = v;
return do_setresgid(l, -1, SCARG(uap, egid), -1, ID_E_EQ_R | ID_E_EQ_S);
}
int
sys_setregid(struct lwp *l, void *v, register_t *retval)
{
struct sys_setregid_args /* {
syscallarg(gid_t) rgid;
syscallarg(gid_t) egid;
} */ *uap = v;
struct proc *p = l->l_proc;
gid_t rgid, egid, svgid;
rgid = SCARG(uap, rgid);
egid = SCARG(uap, egid);
if (rgid == -1)
rgid = p->p_cred->p_rgid;
if (egid == -1)
egid = p->p_ucred->cr_gid;
/* Saved gid is set to the new egid if the rgid changed */
svgid = rgid == p->p_cred->p_rgid ? -1 : egid;
return do_setresgid(l, rgid, egid, svgid,
ID_R_EQ_R | ID_R_EQ_E |
ID_E_EQ_R | ID_E_EQ_E | ID_E_EQ_S |
ID_S_EQ_R | ID_S_EQ_E | ID_S_EQ_S);
}
int
sys_issetugid(struct lwp *l, void *v, register_t *retval)
{
struct proc *p = l->l_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.
*/
*retval = (p->p_flag & P_SUGID) != 0;
return (0);
}
/* ARGSUSED */
int
sys_setgroups(struct lwp *l, void *v, register_t *retval)
{
struct sys_setgroups_args /* {
syscallarg(int) gidsetsize;
syscallarg(const gid_t *) gidset;
} */ *uap = v;
struct proc *p = l->l_proc;
struct pcred *pc = p->p_cred;
int ngrp;
int error;
gid_t grp[NGROUPS];
size_t grsize;
if ((error = suser(pc->pc_ucred, &p->p_acflag)) != 0)
return (error);
ngrp = SCARG(uap, gidsetsize);
if ((u_int)ngrp > NGROUPS)
return (EINVAL);
grsize = ngrp * sizeof(gid_t);
error = copyin(SCARG(uap, gidset), grp, grsize);
if (error)
return (error);
/*
* Check if this is a no-op.
*/
if (pc->pc_ucred->cr_ngroups == (u_int) ngrp &&
memcmp(grp, pc->pc_ucred->cr_groups, grsize) == 0)
return (0);
pc->pc_ucred = crcopy(pc->pc_ucred);
(void)memcpy(pc->pc_ucred->cr_groups, grp, grsize);
pc->pc_ucred->cr_ngroups = ngrp;
p_sugid(p);
return (0);
}
/*
* Check if gid is a member of the group set.
*/
int
groupmember(gid_t gid, const struct ucred *cred)
{
const gid_t *gp;
const 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(const 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(void)
{
struct ucred *cr;
cr = pool_get(&cred_pool, PR_WAITOK);
memset(cr, 0, sizeof(*cr));
simple_lock_init(&cr->cr_lock);
cr->cr_ref = 1;
return (cr);
}
/*
* Free a cred structure.
* Throws away space when ref count gets to 0.
*/
void
crfree(struct ucred *cr)
{
int n;
simple_lock(&cr->cr_lock);
n = --cr->cr_ref;
simple_unlock(&cr->cr_lock);
if (n == 0)
pool_put(&cred_pool, cr);
}
/*
* Compare cred structures and return 0 if they match
*/
int
crcmp(const struct ucred *cr1, const struct uucred *cr2)
{
return cr1->cr_uid != cr2->cr_uid ||
cr1->cr_gid != cr2->cr_gid ||
cr1->cr_ngroups != (uint32_t)cr2->cr_ngroups ||
memcmp(cr1->cr_groups, cr2->cr_groups, cr1->cr_ngroups);
}
/*
* Copy cred structure to a new one and free the old one.
*/
struct ucred *
crcopy(struct ucred *cr)
{
struct ucred *newcr;
if (cr->cr_ref == 1)
return (cr);
newcr = crget();
memcpy(&newcr->cr_startcopy, &cr->cr_startcopy,
sizeof(struct ucred) - offsetof(struct ucred, cr_startcopy));
crfree(cr);
return (newcr);
}
/*
* Dup cred struct to a new held one.
*/
struct ucred *
crdup(const struct ucred *cr)
{
struct ucred *newcr;
newcr = crget();
memcpy(&newcr->cr_startcopy, &cr->cr_startcopy,
sizeof(struct ucred) - offsetof(struct ucred, cr_startcopy));
return (newcr);
}
/*
* convert from userland credentials to kernel one
*/
void
crcvt(struct ucred *uc, const struct uucred *uuc)
{
uc->cr_ref = 0;
uc->cr_uid = uuc->cr_uid;
uc->cr_gid = uuc->cr_gid;
uc->cr_ngroups = uuc->cr_ngroups;
(void)memcpy(uc->cr_groups, uuc->cr_groups, sizeof(uuc->cr_groups));
}
/*
* Get login name, if available.
*/
/* ARGSUSED */
int
sys___getlogin(struct lwp *l, void *v, register_t *retval)
{
struct sys___getlogin_args /* {
syscallarg(char *) namebuf;
syscallarg(size_t) namelen;
} */ *uap = v;
struct proc *p = l->l_proc;
if (SCARG(uap, namelen) > sizeof(p->p_pgrp->pg_session->s_login))
SCARG(uap, namelen) = sizeof(p->p_pgrp->pg_session->s_login);
return (copyout((caddr_t) p->p_pgrp->pg_session->s_login,
(caddr_t) SCARG(uap, namebuf), SCARG(uap, namelen)));
}
/*
* Set login name.
*/
/* ARGSUSED */
int
sys___setlogin(struct lwp *l, void *v, register_t *retval)
{
struct sys___setlogin_args /* {
syscallarg(const char *) namebuf;
} */ *uap = v;
struct proc *p = l->l_proc;
struct session *s = p->p_pgrp->pg_session;
char newname[sizeof s->s_login + 1];
int error;
if ((error = suser(p->p_ucred, &p->p_acflag)) != 0)
return (error);
error = copyinstr(SCARG(uap, namebuf), &newname, sizeof newname, NULL);
if (error != 0)
return (error == ENAMETOOLONG ? EINVAL : error);
if (s->s_flags & S_LOGIN_SET && p->p_pid != s->s_sid &&
strncmp(newname, s->s_login, sizeof s->s_login) != 0)
log(LOG_WARNING, "%s (pid %d) changing logname from "
"%.*s to %s\n", p->p_comm, p->p_pid,
(int)sizeof s->s_login, s->s_login, newname);
s->s_flags |= S_LOGIN_SET;
strncpy(s->s_login, newname, sizeof s->s_login);
return (0);
}