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6cb64f8497
freebsd/sys/kern/kern_prot.c
Gleb Smirnoff c8358c6e0d Call crextend() before copying old credentials to the new credentials 
and replace crcopysafe by crcopy as crcopysafe is is not intended to be
safe in a threaded environment, it drops PROC_LOCK() in while() that
can lead to unexpected results, such as overwrite kernel memory.

In my POV crcopysafe() needs special attention. For now I do not see
any problems with this function, but who knows.

Submitted by:	dchagin
Found by:	trinity
Security:	SA-16:04.linux
2016-01-14 10:16:25 +00:00

2246 lines
52 KiB
C
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/*-
* Copyright (c) 1982, 1986, 1989, 1990, 1991, 1993
* The Regents of the University of California.
* (c) UNIX System Laboratories, Inc.
* Copyright (c) 2000-2001 Robert N. M. Watson.
* All rights reserved.
*
* 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.
* 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
*/
/*
* System calls related to processes and protection
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_compat.h"
#include "opt_inet.h"
#include "opt_inet6.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/acct.h>
#include <sys/kdb.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/loginclass.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/refcount.h>
#include <sys/sx.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/sysproto.h>
#include <sys/jail.h>
#include <sys/pioctl.h>
#include <sys/racct.h>
#include <sys/resourcevar.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/syscallsubr.h>
#include <sys/sysctl.h>
#ifdef REGRESSION
FEATURE(regression,
"Kernel support for interfaces necessary for regression testing (SECURITY RISK!)");
#endif
#if defined(INET) || defined(INET6)
#include <netinet/in.h>
#include <netinet/in_pcb.h>
#endif
#include <security/audit/audit.h>
#include <security/mac/mac_framework.h>
static MALLOC_DEFINE(M_CRED, "cred", "credentials");
SYSCTL_NODE(_security, OID_AUTO, bsd, CTLFLAG_RW, 0, "BSD security policy");
static void crsetgroups_locked(struct ucred *cr, int ngrp,
gid_t *groups);
#ifndef _SYS_SYSPROTO_H_
struct getpid_args {
int dummy;
};
#endif
/* ARGSUSED */
int
sys_getpid(struct thread *td, struct getpid_args *uap)
{
struct proc *p = td->td_proc;
td->td_retval[0] = p->p_pid;
#if defined(COMPAT_43)
td->td_retval[1] = kern_getppid(td);
#endif
return (0);
}
#ifndef _SYS_SYSPROTO_H_
struct getppid_args {
int dummy;
};
#endif
/* ARGSUSED */
int
sys_getppid(struct thread *td, struct getppid_args *uap)
{
td->td_retval[0] = kern_getppid(td);
return (0);
}
int
kern_getppid(struct thread *td)
{
struct proc *p = td->td_proc;
struct proc *pp;
int ppid;
PROC_LOCK(p);
if (!(p->p_flag & P_TRACED)) {
ppid = p->p_pptr->p_pid;
PROC_UNLOCK(p);
} else {
PROC_UNLOCK(p);
sx_slock(&proctree_lock);
pp = proc_realparent(p);
ppid = pp->p_pid;
sx_sunlock(&proctree_lock);
}
return (ppid);
}
/*
* Get process group ID; note that POSIX getpgrp takes no parameter.
*/
#ifndef _SYS_SYSPROTO_H_
struct getpgrp_args {
int dummy;
};
#endif
int
sys_getpgrp(struct thread *td, struct getpgrp_args *uap)
{
struct proc *p = td->td_proc;
PROC_LOCK(p);
td->td_retval[0] = p->p_pgrp->pg_id;
PROC_UNLOCK(p);
return (0);
}
/* Get an arbitary pid's process group id */
#ifndef _SYS_SYSPROTO_H_
struct getpgid_args {
pid_t pid;
};
#endif
int
sys_getpgid(struct thread *td, struct getpgid_args *uap)
{
struct proc *p;
int error;
if (uap->pid == 0) {
p = td->td_proc;
PROC_LOCK(p);
} else {
p = pfind(uap->pid);
if (p == NULL)
return (ESRCH);
error = p_cansee(td, p);
if (error) {
PROC_UNLOCK(p);
return (error);
}
}
td->td_retval[0] = p->p_pgrp->pg_id;
PROC_UNLOCK(p);
return (0);
}
/*
* Get an arbitary pid's session id.
*/
#ifndef _SYS_SYSPROTO_H_
struct getsid_args {
pid_t pid;
};
#endif
int
sys_getsid(struct thread *td, struct getsid_args *uap)
{
struct proc *p;
int error;
if (uap->pid == 0) {
p = td->td_proc;
PROC_LOCK(p);
} else {
p = pfind(uap->pid);
if (p == NULL)
return (ESRCH);
error = p_cansee(td, p);
if (error) {
PROC_UNLOCK(p);
return (error);
}
}
td->td_retval[0] = p->p_session->s_sid;
PROC_UNLOCK(p);
return (0);
}
#ifndef _SYS_SYSPROTO_H_
struct getuid_args {
int dummy;
};
#endif
/* ARGSUSED */
int
sys_getuid(struct thread *td, struct getuid_args *uap)
{
td->td_retval[0] = td->td_ucred->cr_ruid;
#if defined(COMPAT_43)
td->td_retval[1] = td->td_ucred->cr_uid;
#endif
return (0);
}
#ifndef _SYS_SYSPROTO_H_
struct geteuid_args {
int dummy;
};
#endif
/* ARGSUSED */
int
sys_geteuid(struct thread *td, struct geteuid_args *uap)
{
td->td_retval[0] = td->td_ucred->cr_uid;
return (0);
}
#ifndef _SYS_SYSPROTO_H_
struct getgid_args {
int dummy;
};
#endif
/* ARGSUSED */
int
sys_getgid(struct thread *td, struct getgid_args *uap)
{
td->td_retval[0] = td->td_ucred->cr_rgid;
#if defined(COMPAT_43)
td->td_retval[1] = td->td_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
sys_getegid(struct thread *td, struct getegid_args *uap)
{
td->td_retval[0] = td->td_ucred->cr_groups[0];
return (0);
}
#ifndef _SYS_SYSPROTO_H_
struct getgroups_args {
u_int gidsetsize;
gid_t *gidset;
};
#endif
int
sys_getgroups(struct thread *td, register struct getgroups_args *uap)
{
struct ucred *cred;
u_int ngrp;
int error;
cred = td->td_ucred;
ngrp = cred->cr_ngroups;
if (uap->gidsetsize == 0) {
error = 0;
goto out;
}
if (uap->gidsetsize < ngrp)
return (EINVAL);
error = copyout(cred->cr_groups, uap->gidset, ngrp * sizeof(gid_t));
out:
td->td_retval[0] = ngrp;
return (error);
}
#ifndef _SYS_SYSPROTO_H_
struct setsid_args {
int dummy;
};
#endif
/* ARGSUSED */
int
sys_setsid(register struct thread *td, struct setsid_args *uap)
{
struct pgrp *pgrp;
int error;
struct proc *p = td->td_proc;
struct pgrp *newpgrp;
struct session *newsess;
error = 0;
pgrp = NULL;
newpgrp = malloc(sizeof(struct pgrp), M_PGRP, M_WAITOK | M_ZERO);
newsess = malloc(sizeof(struct session), M_SESSION, M_WAITOK | M_ZERO);
sx_xlock(&proctree_lock);
if (p->p_pgid == p->p_pid || (pgrp = pgfind(p->p_pid)) != NULL) {
if (pgrp != NULL)
PGRP_UNLOCK(pgrp);
error = EPERM;
} else {
(void)enterpgrp(p, p->p_pid, newpgrp, newsess);
td->td_retval[0] = p->p_pid;
newpgrp = NULL;
newsess = NULL;
}
sx_xunlock(&proctree_lock);
if (newpgrp != NULL)
free(newpgrp, M_PGRP);
if (newsess != NULL)
free(newsess, M_SESSION);
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
/* ARGSUSED */
int
sys_setpgid(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;
struct pgrp *newpgrp;
if (uap->pgid < 0)
return (EINVAL);
error = 0;
newpgrp = malloc(sizeof(struct pgrp), M_PGRP, M_WAITOK | M_ZERO);
sx_xlock(&proctree_lock);
if (uap->pid != 0 && uap->pid != curp->p_pid) {
if ((targp = pfind(uap->pid)) == NULL) {
error = ESRCH;
goto done;
}
if (!inferior(targp)) {
PROC_UNLOCK(targp);
error = ESRCH;
goto done;
}
if ((error = p_cansee(td, targp))) {
PROC_UNLOCK(targp);
goto done;
}
if (targp->p_pgrp == NULL ||
targp->p_session != curp->p_session) {
PROC_UNLOCK(targp);
error = EPERM;
goto done;
}
if (targp->p_flag & P_EXEC) {
PROC_UNLOCK(targp);
error = EACCES;
goto done;
}
PROC_UNLOCK(targp);
} else
targp = curp;
if (SESS_LEADER(targp)) {
error = EPERM;
goto done;
}
if (uap->pgid == 0)
uap->pgid = targp->p_pid;
if ((pgrp = pgfind(uap->pgid)) == NULL) {
if (uap->pgid == targp->p_pid) {
error = enterpgrp(targp, uap->pgid, newpgrp,
NULL);
if (error == 0)
newpgrp = NULL;
} else
error = EPERM;
} else {
if (pgrp == targp->p_pgrp) {
PGRP_UNLOCK(pgrp);
goto done;
}
if (pgrp->pg_id != targp->p_pid &&
pgrp->pg_session != curp->p_session) {
PGRP_UNLOCK(pgrp);
error = EPERM;
goto done;
}
PGRP_UNLOCK(pgrp);
error = enterthispgrp(targp, pgrp);
}
done:
sx_xunlock(&proctree_lock);
KASSERT((error == 0) || (newpgrp != NULL),
("setpgid failed and newpgrp is NULL"));
if (newpgrp != NULL)
free(newpgrp, M_PGRP);
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
/* ARGSUSED */
int
sys_setuid(struct thread *td, struct setuid_args *uap)
{
struct proc *p = td->td_proc;
struct ucred *newcred, *oldcred;
uid_t uid;
struct uidinfo *uip;
int error;
uid = uap->uid;
AUDIT_ARG_UID(uid);
newcred = crget();
uip = uifind(uid);
PROC_LOCK(p);
/*
* Copy credentials so other references do not see our changes.
*/
oldcred = crcopysafe(p, newcred);
#ifdef MAC
error = mac_cred_check_setuid(oldcred, uid);
if (error)
goto fail;
#endif
/*
* See if we have "permission" by POSIX 1003.1 rules.
*
* Note that setuid(geteuid()) is a special case of
* "appropriate privileges" in appendix B.4.2.2. We need
* to use this clause to be compatible with traditional BSD
* semantics. Basically, it means that "setuid(xx)" sets all
* three id's (assuming you have privs).
*
* Notes on the logic. We do things in three steps.
* 1: We determine if the euid is going to change, and do EPERM
* right away. We unconditionally change the euid later if this
* test is satisfied, simplifying that part of the logic.
* 2: We determine if the real and/or saved uids are going to
* change. Determined by compile options.
* 3: Change euid last. (after tests in #2 for "appropriate privs")
*/
if (uid != oldcred->cr_ruid && /* allow setuid(getuid()) */
#ifdef _POSIX_SAVED_IDS
uid != oldcred->cr_svuid && /* allow setuid(saved gid) */
#endif
#ifdef POSIX_APPENDIX_B_4_2_2 /* Use BSD-compat clause from B.4.2.2 */
uid != oldcred->cr_uid && /* allow setuid(geteuid()) */
#endif
(error = priv_check_cred(oldcred, PRIV_CRED_SETUID, 0)) != 0)
goto fail;
#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
/* We are using privs. */
priv_check_cred(oldcred, PRIV_CRED_SETUID, 0) == 0)
#endif
{
/*
* Set the real uid and transfer proc count to new user.
*/
if (uid != oldcred->cr_ruid) {
change_ruid(newcred, uip);
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.
*/
if (uid != oldcred->cr_uid) {
change_euid(newcred, uip);
setsugid(p);
}
proc_set_cred(p, newcred);
PROC_UNLOCK(p);
#ifdef RACCT
racct_proc_ucred_changed(p, oldcred, newcred);
#endif
uifree(uip);
crfree(oldcred);
return (0);
fail:
PROC_UNLOCK(p);
uifree(uip);
crfree(newcred);
return (error);
}
#ifndef _SYS_SYSPROTO_H_
struct seteuid_args {
uid_t euid;
};
#endif
/* ARGSUSED */
int
sys_seteuid(struct thread *td, struct seteuid_args *uap)
{
struct proc *p = td->td_proc;
struct ucred *newcred, *oldcred;
uid_t euid;
struct uidinfo *euip;
int error;
euid = uap->euid;
AUDIT_ARG_EUID(euid);
newcred = crget();
euip = uifind(euid);
PROC_LOCK(p);
/*
* Copy credentials so other references do not see our changes.
*/
oldcred = crcopysafe(p, newcred);
#ifdef MAC
error = mac_cred_check_seteuid(oldcred, euid);
if (error)
goto fail;
#endif
if (euid != oldcred->cr_ruid && /* allow seteuid(getuid()) */
euid != oldcred->cr_svuid && /* allow seteuid(saved uid) */
(error = priv_check_cred(oldcred, PRIV_CRED_SETEUID, 0)) != 0)
goto fail;
/*
* Everything's okay, do it.
*/
if (oldcred->cr_uid != euid) {
change_euid(newcred, euip);
setsugid(p);
}
proc_set_cred(p, newcred);
PROC_UNLOCK(p);
uifree(euip);
crfree(oldcred);
return (0);
fail:
PROC_UNLOCK(p);
uifree(euip);
crfree(newcred);
return (error);
}
#ifndef _SYS_SYSPROTO_H_
struct setgid_args {
gid_t gid;
};
#endif
/* ARGSUSED */
int
sys_setgid(struct thread *td, struct setgid_args *uap)
{
struct proc *p = td->td_proc;
struct ucred *newcred, *oldcred;
gid_t gid;
int error;
gid = uap->gid;
AUDIT_ARG_GID(gid);
newcred = crget();
PROC_LOCK(p);
oldcred = crcopysafe(p, newcred);
#ifdef MAC
error = mac_cred_check_setgid(oldcred, gid);
if (error)
goto fail;
#endif
/*
* 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 = priv_check_cred(oldcred, PRIV_CRED_SETGID, 0)) != 0)
goto fail;
#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
/* We are using privs. */
priv_check_cred(oldcred, PRIV_CRED_SETGID, 0) == 0)
#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);
}
proc_set_cred(p, newcred);
PROC_UNLOCK(p);
crfree(oldcred);
return (0);
fail:
PROC_UNLOCK(p);
crfree(newcred);
return (error);
}
#ifndef _SYS_SYSPROTO_H_
struct setegid_args {
gid_t egid;
};
#endif
/* ARGSUSED */
int
sys_setegid(struct thread *td, struct setegid_args *uap)
{
struct proc *p = td->td_proc;
struct ucred *newcred, *oldcred;
gid_t egid;
int error;
egid = uap->egid;
AUDIT_ARG_EGID(egid);
newcred = crget();
PROC_LOCK(p);
oldcred = crcopysafe(p, newcred);
#ifdef MAC
error = mac_cred_check_setegid(oldcred, egid);
if (error)
goto fail;
#endif
if (egid != oldcred->cr_rgid && /* allow setegid(getgid()) */
egid != oldcred->cr_svgid && /* allow setegid(saved gid) */
(error = priv_check_cred(oldcred, PRIV_CRED_SETEGID, 0)) != 0)
goto fail;
if (oldcred->cr_groups[0] != egid) {
change_egid(newcred, egid);
setsugid(p);
}
proc_set_cred(p, newcred);
PROC_UNLOCK(p);
crfree(oldcred);
return (0);
fail:
PROC_UNLOCK(p);
crfree(newcred);
return (error);
}
#ifndef _SYS_SYSPROTO_H_
struct setgroups_args {
u_int gidsetsize;
gid_t *gidset;
};
#endif
/* ARGSUSED */
int
sys_setgroups(struct thread *td, struct setgroups_args *uap)
{
gid_t smallgroups[XU_NGROUPS];
gid_t *groups;
u_int gidsetsize;
int error;
gidsetsize = uap->gidsetsize;
if (gidsetsize > ngroups_max + 1)
return (EINVAL);
if (gidsetsize > XU_NGROUPS)
groups = malloc(gidsetsize * sizeof(gid_t), M_TEMP, M_WAITOK);
else
groups = smallgroups;
error = copyin(uap->gidset, groups, gidsetsize * sizeof(gid_t));
if (error == 0)
error = kern_setgroups(td, gidsetsize, groups);
if (gidsetsize > XU_NGROUPS)
free(groups, M_TEMP);
return (error);
}
int
kern_setgroups(struct thread *td, u_int ngrp, gid_t *groups)
{
struct proc *p = td->td_proc;
struct ucred *newcred, *oldcred;
int error;
MPASS(ngrp <= ngroups_max + 1);
AUDIT_ARG_GROUPSET(groups, ngrp);
newcred = crget();
crextend(newcred, ngrp);
PROC_LOCK(p);
oldcred = crcopysafe(p, newcred);
#ifdef MAC
error = mac_cred_check_setgroups(oldcred, ngrp, groups);
if (error)
goto fail;
#endif
error = priv_check_cred(oldcred, PRIV_CRED_SETGROUPS, 0);
if (error)
goto fail;
if (ngrp == 0) {
/*
* 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 {
crsetgroups_locked(newcred, ngrp, groups);
}
setsugid(p);
proc_set_cred(p, newcred);
PROC_UNLOCK(p);
crfree(oldcred);
return (0);
fail:
PROC_UNLOCK(p);
crfree(newcred);
return (error);
}
#ifndef _SYS_SYSPROTO_H_
struct setreuid_args {
uid_t ruid;
uid_t euid;
};
#endif
/* ARGSUSED */
int
sys_setreuid(register struct thread *td, struct setreuid_args *uap)
{
struct proc *p = td->td_proc;
struct ucred *newcred, *oldcred;
uid_t euid, ruid;
struct uidinfo *euip, *ruip;
int error;
euid = uap->euid;
ruid = uap->ruid;
AUDIT_ARG_EUID(euid);
AUDIT_ARG_RUID(ruid);
newcred = crget();
euip = uifind(euid);
ruip = uifind(ruid);
PROC_LOCK(p);
oldcred = crcopysafe(p, newcred);
#ifdef MAC
error = mac_cred_check_setreuid(oldcred, ruid, euid);
if (error)
goto fail;
#endif
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 = priv_check_cred(oldcred, PRIV_CRED_SETREUID, 0)) != 0)
goto fail;
if (euid != (uid_t)-1 && oldcred->cr_uid != euid) {
change_euid(newcred, euip);
setsugid(p);
}
if (ruid != (uid_t)-1 && oldcred->cr_ruid != ruid) {
change_ruid(newcred, ruip);
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);
}
proc_set_cred(p, newcred);
PROC_UNLOCK(p);
#ifdef RACCT
racct_proc_ucred_changed(p, oldcred, newcred);
#endif
uifree(ruip);
uifree(euip);
crfree(oldcred);
return (0);
fail:
PROC_UNLOCK(p);
uifree(ruip);
uifree(euip);
crfree(newcred);
return (error);
}
#ifndef _SYS_SYSPROTO_H_
struct setregid_args {
gid_t rgid;
gid_t egid;
};
#endif
/* ARGSUSED */
int
sys_setregid(register struct thread *td, struct setregid_args *uap)
{
struct proc *p = td->td_proc;
struct ucred *newcred, *oldcred;
gid_t egid, rgid;
int error;
egid = uap->egid;
rgid = uap->rgid;
AUDIT_ARG_EGID(egid);
AUDIT_ARG_RGID(rgid);
newcred = crget();
PROC_LOCK(p);
oldcred = crcopysafe(p, newcred);
#ifdef MAC
error = mac_cred_check_setregid(oldcred, rgid, egid);
if (error)
goto fail;
#endif
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 = priv_check_cred(oldcred, PRIV_CRED_SETREGID, 0)) != 0)
goto fail;
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);
}
proc_set_cred(p, newcred);
PROC_UNLOCK(p);
crfree(oldcred);
return (0);
fail:
PROC_UNLOCK(p);
crfree(newcred);
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
/* ARGSUSED */
int
sys_setresuid(register struct thread *td, struct setresuid_args *uap)
{
struct proc *p = td->td_proc;
struct ucred *newcred, *oldcred;
uid_t euid, ruid, suid;
struct uidinfo *euip, *ruip;
int error;
euid = uap->euid;
ruid = uap->ruid;
suid = uap->suid;
AUDIT_ARG_EUID(euid);
AUDIT_ARG_RUID(ruid);
AUDIT_ARG_SUID(suid);
newcred = crget();
euip = uifind(euid);
ruip = uifind(ruid);
PROC_LOCK(p);
oldcred = crcopysafe(p, newcred);
#ifdef MAC
error = mac_cred_check_setresuid(oldcred, ruid, euid, suid);
if (error)
goto fail;
#endif
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 = priv_check_cred(oldcred, PRIV_CRED_SETRESUID, 0)) != 0)
goto fail;
if (euid != (uid_t)-1 && oldcred->cr_uid != euid) {
change_euid(newcred, euip);
setsugid(p);
}
if (ruid != (uid_t)-1 && oldcred->cr_ruid != ruid) {
change_ruid(newcred, ruip);
setsugid(p);
}
if (suid != (uid_t)-1 && oldcred->cr_svuid != suid) {
change_svuid(newcred, suid);
setsugid(p);
}
proc_set_cred(p, newcred);
PROC_UNLOCK(p);
#ifdef RACCT
racct_proc_ucred_changed(p, oldcred, newcred);
#endif
uifree(ruip);
uifree(euip);
crfree(oldcred);
return (0);
fail:
PROC_UNLOCK(p);
uifree(ruip);
uifree(euip);
crfree(newcred);
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
/* ARGSUSED */
int
sys_setresgid(register struct thread *td, struct setresgid_args *uap)
{
struct proc *p = td->td_proc;
struct ucred *newcred, *oldcred;
gid_t egid, rgid, sgid;
int error;
egid = uap->egid;
rgid = uap->rgid;
sgid = uap->sgid;
AUDIT_ARG_EGID(egid);
AUDIT_ARG_RGID(rgid);
AUDIT_ARG_SGID(sgid);
newcred = crget();
PROC_LOCK(p);
oldcred = crcopysafe(p, newcred);
#ifdef MAC
error = mac_cred_check_setresgid(oldcred, rgid, egid, sgid);
if (error)
goto fail;
#endif
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 = priv_check_cred(oldcred, PRIV_CRED_SETRESGID, 0)) != 0)
goto fail;
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);
}
proc_set_cred(p, newcred);
PROC_UNLOCK(p);
crfree(oldcred);
return (0);
fail:
PROC_UNLOCK(p);
crfree(newcred);
return (error);
}
#ifndef _SYS_SYSPROTO_H_
struct getresuid_args {
uid_t *ruid;
uid_t *euid;
uid_t *suid;
};
#endif
/* ARGSUSED */
int
sys_getresuid(register struct thread *td, struct getresuid_args *uap)
{
struct ucred *cred;
int error1 = 0, error2 = 0, error3 = 0;
cred = td->td_ucred;
if (uap->ruid)
error1 = copyout(&cred->cr_ruid,
uap->ruid, sizeof(cred->cr_ruid));
if (uap->euid)
error2 = copyout(&cred->cr_uid,
uap->euid, sizeof(cred->cr_uid));
if (uap->suid)
error3 = copyout(&cred->cr_svuid,
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
sys_getresgid(register struct thread *td, struct getresgid_args *uap)
{
struct ucred *cred;
int error1 = 0, error2 = 0, error3 = 0;
cred = td->td_ucred;
if (uap->rgid)
error1 = copyout(&cred->cr_rgid,
uap->rgid, sizeof(cred->cr_rgid));
if (uap->egid)
error2 = copyout(&cred->cr_groups[0],
uap->egid, sizeof(cred->cr_groups[0]));
if (uap->sgid)
error3 = copyout(&cred->cr_svgid,
uap->sgid, sizeof(cred->cr_svgid));
return (error1 ? error1 : error2 ? error2 : error3);
}
#ifndef _SYS_SYSPROTO_H_
struct issetugid_args {
int dummy;
};
#endif
/* ARGSUSED */
int
sys_issetugid(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.
*/
PROC_LOCK(p);
td->td_retval[0] = (p->p_flag & P_SUGID) ? 1 : 0;
PROC_UNLOCK(p);
return (0);
}
int
sys___setugid(struct thread *td, struct __setugid_args *uap)
{
#ifdef REGRESSION
struct proc *p;
p = td->td_proc;
switch (uap->flag) {
case 0:
PROC_LOCK(p);
p->p_flag &= ~P_SUGID;
PROC_UNLOCK(p);
return (0);
case 1:
PROC_LOCK(p);
p->p_flag |= P_SUGID;
PROC_UNLOCK(p);
return (0);
default:
return (EINVAL);
}
#else /* !REGRESSION */
return (ENOSYS);
#endif /* REGRESSION */
}
/*
* Check if gid is a member of the group set.
*/
int
groupmember(gid_t gid, struct ucred *cred)
{
int l;
int h;
int m;
if (cred->cr_groups[0] == gid)
return(1);
/*
* If gid was not our primary group, perform a binary search
* of the supplemental groups. This is possible because we
* sort the groups in crsetgroups().
*/
l = 1;
h = cred->cr_ngroups;
while (l < h) {
m = l + ((h - l) / 2);
if (cred->cr_groups[m] < gid)
l = m + 1;
else
h = m;
}
if ((l < cred->cr_ngroups) && (cred->cr_groups[l] == gid))
return (1);
return (0);
}
/*
* Test the active securelevel against a given level. securelevel_gt()
* implements (securelevel > level). securelevel_ge() implements
* (securelevel >= level). Note that the logic is inverted -- these
* functions return EPERM on "success" and 0 on "failure".
*
* Due to care taken when setting the securelevel, we know that no jail will
* be less secure that its parent (or the physical system), so it is sufficient
* to test the current jail only.
*
* XXXRW: Possibly since this has to do with privilege, it should move to
* kern_priv.c.
*/
int
securelevel_gt(struct ucred *cr, int level)
{
return (cr->cr_prison->pr_securelevel > level ? EPERM : 0);
}
int
securelevel_ge(struct ucred *cr, int level)
{
return (cr->cr_prison->pr_securelevel >= level ? EPERM : 0);
}
/*
* 'see_other_uids' determines whether or not visibility of processes
* and sockets with credentials holding different real uids is possible
* using a variety of system MIBs.
* XXX: data declarations should be together near the beginning of the file.
*/
static int see_other_uids = 1;
SYSCTL_INT(_security_bsd, OID_AUTO, see_other_uids, CTLFLAG_RW,
&see_other_uids, 0,
"Unprivileged processes may see subjects/objects with different real uid");
/*-
* Determine if u1 "can see" the subject specified by u2, according to the
* 'see_other_uids' policy.
* Returns: 0 for permitted, ESRCH otherwise
* Locks: none
* References: *u1 and *u2 must not change during the call
* u1 may equal u2, in which case only one reference is required
*/
static int
cr_seeotheruids(struct ucred *u1, struct ucred *u2)
{
if (!see_other_uids && u1->cr_ruid != u2->cr_ruid) {
if (priv_check_cred(u1, PRIV_SEEOTHERUIDS, 0) != 0)
return (ESRCH);
}
return (0);
}
/*
* 'see_other_gids' determines whether or not visibility of processes
* and sockets with credentials holding different real gids is possible
* using a variety of system MIBs.
* XXX: data declarations should be together near the beginning of the file.
*/
static int see_other_gids = 1;
SYSCTL_INT(_security_bsd, OID_AUTO, see_other_gids, CTLFLAG_RW,
&see_other_gids, 0,
"Unprivileged processes may see subjects/objects with different real gid");
/*
* Determine if u1 can "see" the subject specified by u2, according to the
* 'see_other_gids' policy.
* Returns: 0 for permitted, ESRCH otherwise
* Locks: none
* References: *u1 and *u2 must not change during the call
* u1 may equal u2, in which case only one reference is required
*/
static int
cr_seeothergids(struct ucred *u1, struct ucred *u2)
{
int i, match;
if (!see_other_gids) {
match = 0;
for (i = 0; i < u1->cr_ngroups; i++) {
if (groupmember(u1->cr_groups[i], u2))
match = 1;
if (match)
break;
}
if (!match) {
if (priv_check_cred(u1, PRIV_SEEOTHERGIDS, 0) != 0)
return (ESRCH);
}
}
return (0);
}
/*-
* Determine if u1 "can see" the subject specified by u2.
* Returns: 0 for permitted, an errno value otherwise
* Locks: none
* References: *u1 and *u2 must not change during the call
* u1 may equal u2, in which case only one reference is required
*/
int
cr_cansee(struct ucred *u1, struct ucred *u2)
{
int error;
if ((error = prison_check(u1, u2)))
return (error);
#ifdef MAC
if ((error = mac_cred_check_visible(u1, u2)))
return (error);
#endif
if ((error = cr_seeotheruids(u1, u2)))
return (error);
if ((error = cr_seeothergids(u1, u2)))
return (error);
return (0);
}
/*-
* Determine if td "can see" the subject specified by p.
* Returns: 0 for permitted, an errno value otherwise
* Locks: Sufficient locks to protect p->p_ucred must be held. td really
* should be curthread.
* References: td and p must be valid for the lifetime of the call
*/
int
p_cansee(struct thread *td, struct proc *p)
{
/* Wrap cr_cansee() for all functionality. */
KASSERT(td == curthread, ("%s: td not curthread", __func__));
PROC_LOCK_ASSERT(p, MA_OWNED);
return (cr_cansee(td->td_ucred, p->p_ucred));
}
/*
* 'conservative_signals' prevents the delivery of a broad class of
* signals by unprivileged processes to processes that have changed their
* credentials since the last invocation of execve(). This can prevent
* the leakage of cached information or retained privileges as a result
* of a common class of signal-related vulnerabilities. However, this
* may interfere with some applications that expect to be able to
* deliver these signals to peer processes after having given up
* privilege.
*/
static int conservative_signals = 1;
SYSCTL_INT(_security_bsd, OID_AUTO, conservative_signals, CTLFLAG_RW,
&conservative_signals, 0, "Unprivileged processes prevented from "
"sending certain signals to processes whose credentials have changed");
/*-
* Determine whether cred may deliver the specified signal to proc.
* Returns: 0 for permitted, an errno value otherwise.
* Locks: A lock must be held for proc.
* References: cred and proc must be valid for the lifetime of the call.
*/
int
cr_cansignal(struct ucred *cred, struct proc *proc, int signum)
{
int error;
PROC_LOCK_ASSERT(proc, MA_OWNED);
/*
* Jail semantics limit the scope of signalling to proc in the
* same jail as cred, if cred is in jail.
*/
error = prison_check(cred, proc->p_ucred);
if (error)
return (error);
#ifdef MAC
if ((error = mac_proc_check_signal(cred, proc, signum)))
return (error);
#endif
if ((error = cr_seeotheruids(cred, proc->p_ucred)))
return (error);
if ((error = cr_seeothergids(cred, proc->p_ucred)))
return (error);
/*
* 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 (conservative_signals && (proc->p_flag & P_SUGID)) {
switch (signum) {
case 0:
case SIGKILL:
case SIGINT:
case SIGTERM:
case SIGALRM:
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 without privilege. */
error = priv_check_cred(cred, PRIV_SIGNAL_SUGID, 0);
if (error)
return (error);
}
}
/*
* Generally, the target credential's ruid or svuid must match the
* subject credential's ruid or euid.
*/
if (cred->cr_ruid != proc->p_ucred->cr_ruid &&
cred->cr_ruid != proc->p_ucred->cr_svuid &&
cred->cr_uid != proc->p_ucred->cr_ruid &&
cred->cr_uid != proc->p_ucred->cr_svuid) {
error = priv_check_cred(cred, PRIV_SIGNAL_DIFFCRED, 0);
if (error)
return (error);
}
return (0);
}
/*-
* Determine whether td may deliver the specified signal to p.
* Returns: 0 for permitted, an errno value otherwise
* Locks: Sufficient locks to protect various components of td and p
* must be held. td must be curthread, and a lock must be
* held for p.
* References: td and p must be valid for the lifetime of the call
*/
int
p_cansignal(struct thread *td, struct proc *p, int signum)
{
KASSERT(td == curthread, ("%s: td not curthread", __func__));
PROC_LOCK_ASSERT(p, MA_OWNED);
if (td->td_proc == p)
return (0);
/*
* UNIX signalling semantics require that processes in the same
* session always be able to deliver SIGCONT to one another,
* overriding the remaining protections.
*/
/* XXX: This will require an additional lock of some sort. */
if (signum == SIGCONT && td->td_proc->p_session == p->p_session)
return (0);
/*
* Some compat layers use SIGTHR and higher signals for
* communication between different kernel threads of the same
* process, so that they expect that it's always possible to
* deliver them, even for suid applications where cr_cansignal() can
* deny such ability for security consideration. It should be
* pretty safe to do since the only way to create two processes
* with the same p_leader is via rfork(2).
*/
if (td->td_proc->p_leader != NULL && signum >= SIGTHR &&
signum < SIGTHR + 4 && td->td_proc->p_leader == p->p_leader)
return (0);
return (cr_cansignal(td->td_ucred, p, signum));
}
/*-
* Determine whether td may reschedule p.
* Returns: 0 for permitted, an errno value otherwise
* Locks: Sufficient locks to protect various components of td and p
* must be held. td must be curthread, and a lock must
* be held for p.
* References: td and p must be valid for the lifetime of the call
*/
int
p_cansched(struct thread *td, struct proc *p)
{
int error;
KASSERT(td == curthread, ("%s: td not curthread", __func__));
PROC_LOCK_ASSERT(p, MA_OWNED);
if (td->td_proc == p)
return (0);
if ((error = prison_check(td->td_ucred, p->p_ucred)))
return (error);
#ifdef MAC
if ((error = mac_proc_check_sched(td->td_ucred, p)))
return (error);
#endif
if ((error = cr_seeotheruids(td->td_ucred, p->p_ucred)))
return (error);
if ((error = cr_seeothergids(td->td_ucred, p->p_ucred)))
return (error);
if (td->td_ucred->cr_ruid != p->p_ucred->cr_ruid &&
td->td_ucred->cr_uid != p->p_ucred->cr_ruid) {
error = priv_check(td, PRIV_SCHED_DIFFCRED);
if (error)
return (error);
}
return (0);
}
/*
* The 'unprivileged_proc_debug' flag may be used to disable a variety of
* unprivileged inter-process debugging services, including some procfs
* functionality, ptrace(), and ktrace(). In the past, inter-process
* debugging has been involved in a variety of security problems, and sites
* not requiring the service might choose to disable it when hardening
* systems.
*
* XXX: Should modifying and reading this variable require locking?
* XXX: data declarations should be together near the beginning of the file.
*/
static int unprivileged_proc_debug = 1;
SYSCTL_INT(_security_bsd, OID_AUTO, unprivileged_proc_debug, CTLFLAG_RW,
&unprivileged_proc_debug, 0,
"Unprivileged processes may use process debugging facilities");
/*-
* Determine whether td may debug p.
* Returns: 0 for permitted, an errno value otherwise
* Locks: Sufficient locks to protect various components of td and p
* must be held. td must be curthread, and a lock must
* be held for p.
* References: td and p must be valid for the lifetime of the call
*/
int
p_candebug(struct thread *td, struct proc *p)
{
int credentialchanged, error, grpsubset, i, uidsubset;
KASSERT(td == curthread, ("%s: td not curthread", __func__));
PROC_LOCK_ASSERT(p, MA_OWNED);
if (!unprivileged_proc_debug) {
error = priv_check(td, PRIV_DEBUG_UNPRIV);
if (error)
return (error);
}
if (td->td_proc == p)
return (0);
if ((error = prison_check(td->td_ucred, p->p_ucred)))
return (error);
#ifdef MAC
if ((error = mac_proc_check_debug(td->td_ucred, p)))
return (error);
#endif
if ((error = cr_seeotheruids(td->td_ucred, p->p_ucred)))
return (error);
if ((error = cr_seeothergids(td->td_ucred, p->p_ucred)))
return (error);
/*
* Is p's group set a subset of td's effective group set? This
* includes p's egid, group access list, rgid, and svgid.
*/
grpsubset = 1;
for (i = 0; i < p->p_ucred->cr_ngroups; i++) {
if (!groupmember(p->p_ucred->cr_groups[i], td->td_ucred)) {
grpsubset = 0;
break;
}
}
grpsubset = grpsubset &&
groupmember(p->p_ucred->cr_rgid, td->td_ucred) &&
groupmember(p->p_ucred->cr_svgid, td->td_ucred);
/*
* Are the uids present in p's credential equal to td's
* effective uid? This includes p's euid, svuid, and ruid.
*/
uidsubset = (td->td_ucred->cr_uid == p->p_ucred->cr_uid &&
td->td_ucred->cr_uid == p->p_ucred->cr_svuid &&
td->td_ucred->cr_uid == p->p_ucred->cr_ruid);
/*
* Has the credential of the process changed since the last exec()?
*/
credentialchanged = (p->p_flag & P_SUGID);
/*
* If p's gids aren't a subset, or the uids aren't a subset,
* or the credential has changed, require appropriate privilege
* for td to debug p.
*/
if (!grpsubset || !uidsubset) {
error = priv_check(td, PRIV_DEBUG_DIFFCRED);
if (error)
return (error);
}
if (credentialchanged) {
error = priv_check(td, PRIV_DEBUG_SUGID);
if (error)
return (error);
}
/* Can't trace init when securelevel > 0. */
if (p == initproc) {
error = securelevel_gt(td->td_ucred, 0);
if (error)
return (error);
}
/*
* Can't trace a process that's currently exec'ing.
*
* XXX: Note, this is not a security policy decision, it's a
* basic correctness/functionality decision. Therefore, this check
* should be moved to the caller's of p_candebug().
*/
if ((p->p_flag & P_INEXEC) != 0)
return (EBUSY);
/* Denied explicitely */
if ((p->p_flag2 & P2_NOTRACE) != 0) {
error = priv_check(td, PRIV_DEBUG_DENIED);
if (error != 0)
return (error);
}
return (0);
}
/*-
* Determine whether the subject represented by cred can "see" a socket.
* Returns: 0 for permitted, ENOENT otherwise.
*/
int
cr_canseesocket(struct ucred *cred, struct socket *so)
{
int error;
error = prison_check(cred, so->so_cred);
if (error)
return (ENOENT);
#ifdef MAC
error = mac_socket_check_visible(cred, so);
if (error)
return (error);
#endif
if (cr_seeotheruids(cred, so->so_cred))
return (ENOENT);
if (cr_seeothergids(cred, so->so_cred))
return (ENOENT);
return (0);
}
#if defined(INET) || defined(INET6)
/*-
* Determine whether the subject represented by cred can "see" a socket.
* Returns: 0 for permitted, ENOENT otherwise.
*/
int
cr_canseeinpcb(struct ucred *cred, struct inpcb *inp)
{
int error;
error = prison_check(cred, inp->inp_cred);
if (error)
return (ENOENT);
#ifdef MAC
INP_LOCK_ASSERT(inp);
error = mac_inpcb_check_visible(cred, inp);
if (error)
return (error);
#endif
if (cr_seeotheruids(cred, inp->inp_cred))
return (ENOENT);
if (cr_seeothergids(cred, inp->inp_cred))
return (ENOENT);
return (0);
}
#endif
/*-
* Determine whether td can wait for the exit of p.
* Returns: 0 for permitted, an errno value otherwise
* Locks: Sufficient locks to protect various components of td and p
* must be held. td must be curthread, and a lock must
* be held for p.
* References: td and p must be valid for the lifetime of the call
*/
int
p_canwait(struct thread *td, struct proc *p)
{
int error;
KASSERT(td == curthread, ("%s: td not curthread", __func__));
PROC_LOCK_ASSERT(p, MA_OWNED);
if ((error = prison_check(td->td_ucred, p->p_ucred)))
return (error);
#ifdef MAC
if ((error = mac_proc_check_wait(td->td_ucred, p)))
return (error);
#endif
#if 0
/* XXXMAC: This could have odd effects on some shells. */
if ((error = cr_seeotheruids(td->td_ucred, p->p_ucred)))
return (error);
#endif
return (0);
}
/*
* Allocate a zeroed cred structure.
*/
struct ucred *
crget(void)
{
register struct ucred *cr;
cr = malloc(sizeof(*cr), M_CRED, M_WAITOK | M_ZERO);
refcount_init(&cr->cr_ref, 1);
#ifdef AUDIT
audit_cred_init(cr);
#endif
#ifdef MAC
mac_cred_init(cr);
#endif
cr->cr_groups = cr->cr_smallgroups;
cr->cr_agroups =
sizeof(cr->cr_smallgroups) / sizeof(cr->cr_smallgroups[0]);
return (cr);
}
/*
* Claim another reference to a ucred structure.
*/
struct ucred *
crhold(struct ucred *cr)
{
refcount_acquire(&cr->cr_ref);
return (cr);
}
/*
* Free a cred structure. Throws away space when ref count gets to 0.
*/
void
crfree(struct ucred *cr)
{
KASSERT(cr->cr_ref > 0, ("bad ucred refcount: %d", cr->cr_ref));
KASSERT(cr->cr_ref != 0xdeadc0de, ("dangling reference to ucred"));
if (refcount_release(&cr->cr_ref)) {
/*
* 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 (cr->cr_prison != NULL)
prison_free(cr->cr_prison);
if (cr->cr_loginclass != NULL)
loginclass_free(cr->cr_loginclass);
#ifdef AUDIT
audit_cred_destroy(cr);
#endif
#ifdef MAC
mac_cred_destroy(cr);
#endif
if (cr->cr_groups != cr->cr_smallgroups)
free(cr->cr_groups, M_CRED);
free(cr, M_CRED);
}
}
/*
* Copy a ucred's contents from a template. Does not block.
*/
void
crcopy(struct ucred *dest, struct ucred *src)
{
KASSERT(dest->cr_ref == 1, ("crcopy of shared ucred"));
bcopy(&src->cr_startcopy, &dest->cr_startcopy,
(unsigned)((caddr_t)&src->cr_endcopy -
(caddr_t)&src->cr_startcopy));
crsetgroups(dest, src->cr_ngroups, src->cr_groups);
uihold(dest->cr_uidinfo);
uihold(dest->cr_ruidinfo);
prison_hold(dest->cr_prison);
loginclass_hold(dest->cr_loginclass);
#ifdef AUDIT
audit_cred_copy(src, dest);
#endif
#ifdef MAC
mac_cred_copy(src, dest);
#endif
}
/*
* Dup cred struct to a new held one.
*/
struct ucred *
crdup(struct ucred *cr)
{
struct ucred *newcr;
newcr = crget();
crcopy(newcr, cr);
return (newcr);
}
/*
* Fill in a struct xucred based on a struct ucred.
*/
void
cru2x(struct ucred *cr, struct xucred *xcr)
{
int ngroups;
bzero(xcr, sizeof(*xcr));
xcr->cr_version = XUCRED_VERSION;
xcr->cr_uid = cr->cr_uid;
ngroups = MIN(cr->cr_ngroups, XU_NGROUPS);
xcr->cr_ngroups = ngroups;
bcopy(cr->cr_groups, xcr->cr_groups,
ngroups * sizeof(*cr->cr_groups));
}
/*
* Set initial process credentials.
* Callers are responsible for providing the reference for provided credentials.
*/
void
proc_set_cred_init(struct proc *p, struct ucred *newcred)
{
p->p_ucred = newcred;
}
/*
* Change process credentials.
* Callers are responsible for providing the reference for passed credentials
* and for freeing old ones.
*
* Process has to be locked except when it does not have credentials (as it
* should not be visible just yet) or when newcred is NULL (as this can be
* only used when the process is about to be freed, at which point it should
* not be visible anymore).
*/
struct ucred *
proc_set_cred(struct proc *p, struct ucred *newcred)
{
struct ucred *oldcred;
MPASS(p->p_ucred != NULL);
if (newcred == NULL)
MPASS(p->p_state == PRS_ZOMBIE);
else
PROC_LOCK_ASSERT(p, MA_OWNED);
oldcred = p->p_ucred;
p->p_ucred = newcred;
if (newcred != NULL)
PROC_UPDATE_COW(p);
return (oldcred);
}
struct ucred *
crcopysafe(struct proc *p, struct ucred *cr)
{
struct ucred *oldcred;
int groups;
PROC_LOCK_ASSERT(p, MA_OWNED);
oldcred = p->p_ucred;
while (cr->cr_agroups < oldcred->cr_agroups) {
groups = oldcred->cr_agroups;
PROC_UNLOCK(p);
crextend(cr, groups);
PROC_LOCK(p);
oldcred = p->p_ucred;
}
crcopy(cr, oldcred);
return (oldcred);
}
/*
* Extend the passed in credential to hold n items.
*/
void
crextend(struct ucred *cr, int n)
{
int cnt;
/* Truncate? */
if (n <= cr->cr_agroups)
return;
/*
* We extend by 2 each time since we're using a power of two
* allocator until we need enough groups to fill a page.
* Once we're allocating multiple pages, only allocate as many
* as we actually need. The case of processes needing a
* non-power of two number of pages seems more likely than
* a real world process that adds thousands of groups one at a
* time.
*/
if ( n < PAGE_SIZE / sizeof(gid_t) ) {
if (cr->cr_agroups == 0)
cnt = MINALLOCSIZE / sizeof(gid_t);
else
cnt = cr->cr_agroups * 2;
while (cnt < n)
cnt *= 2;
} else
cnt = roundup2(n, PAGE_SIZE / sizeof(gid_t));
/* Free the old array. */
if (cr->cr_groups != cr->cr_smallgroups)
free(cr->cr_groups, M_CRED);
cr->cr_groups = malloc(cnt * sizeof(gid_t), M_CRED, M_WAITOK | M_ZERO);
cr->cr_agroups = cnt;
}
/*
* Copy groups in to a credential, preserving any necessary invariants.
* Currently this includes the sorting of all supplemental gids.
* crextend() must have been called before hand to ensure sufficient
* space is available.
*/
static void
crsetgroups_locked(struct ucred *cr, int ngrp, gid_t *groups)
{
int i;
int j;
gid_t g;
KASSERT(cr->cr_agroups >= ngrp, ("cr_ngroups is too small"));
bcopy(groups, cr->cr_groups, ngrp * sizeof(gid_t));
cr->cr_ngroups = ngrp;
/*
* Sort all groups except cr_groups[0] to allow groupmember to
* perform a binary search.
*
* XXX: If large numbers of groups become common this should
* be replaced with shell sort like linux uses or possibly
* heap sort.
*/
for (i = 2; i < ngrp; i++) {
g = cr->cr_groups[i];
for (j = i-1; j >= 1 && g < cr->cr_groups[j]; j--)
cr->cr_groups[j + 1] = cr->cr_groups[j];
cr->cr_groups[j + 1] = g;
}
}
/*
* Copy groups in to a credential after expanding it if required.
* Truncate the list to (ngroups_max + 1) if it is too large.
*/
void
crsetgroups(struct ucred *cr, int ngrp, gid_t *groups)
{
if (ngrp > ngroups_max + 1)
ngrp = ngroups_max + 1;
crextend(cr, ngrp);
crsetgroups_locked(cr, ngrp, groups);
}
/*
* Get login name, if available.
*/
#ifndef _SYS_SYSPROTO_H_
struct getlogin_args {
char *namebuf;
u_int namelen;
};
#endif
/* ARGSUSED */
int
sys_getlogin(struct thread *td, struct getlogin_args *uap)
{
char login[MAXLOGNAME];
struct proc *p = td->td_proc;
size_t len;
if (uap->namelen > MAXLOGNAME)
uap->namelen = MAXLOGNAME;
PROC_LOCK(p);
SESS_LOCK(p->p_session);
len = strlcpy(login, p->p_session->s_login, uap->namelen) + 1;
SESS_UNLOCK(p->p_session);
PROC_UNLOCK(p);
if (len > uap->namelen)
return (ERANGE);
return (copyout(login, uap->namebuf, len));
}
/*
* Set login name.
*/
#ifndef _SYS_SYSPROTO_H_
struct setlogin_args {
char *namebuf;
};
#endif
/* ARGSUSED */
int
sys_setlogin(struct thread *td, struct setlogin_args *uap)
{
struct proc *p = td->td_proc;
int error;
char logintmp[MAXLOGNAME];
CTASSERT(sizeof(p->p_session->s_login) >= sizeof(logintmp));
error = priv_check(td, PRIV_PROC_SETLOGIN);
if (error)
return (error);
error = copyinstr(uap->namebuf, logintmp, sizeof(logintmp), NULL);
if (error != 0) {
if (error == ENAMETOOLONG)
error = EINVAL;
return (error);
}
PROC_LOCK(p);
SESS_LOCK(p->p_session);
strcpy(p->p_session->s_login, logintmp);
SESS_UNLOCK(p->p_session);
PROC_UNLOCK(p);
return (0);
}
void
setsugid(struct proc *p)
{
PROC_LOCK_ASSERT(p, MA_OWNED);
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(struct ucred *newcred, struct uidinfo *euip)
{
newcred->cr_uid = euip->ui_uid;
uihold(euip);
uifree(newcred->cr_uidinfo);
newcred->cr_uidinfo = euip;
}
/*-
* 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(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(struct ucred *newcred, struct uidinfo *ruip)
{
(void)chgproccnt(newcred->cr_ruidinfo, -1, 0);
newcred->cr_ruid = ruip->ui_uid;
uihold(ruip);
uifree(newcred->cr_ruidinfo);
newcred->cr_ruidinfo = ruip;
(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(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(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(struct ucred *newcred, gid_t svgid)
{
newcred->cr_svgid = svgid;
}
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