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NetBSD/sys/kern/kern_systrace.c

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/* $NetBSD: kern_systrace.c,v 1.24 2003/02/16 20:24:47 provos Exp $ */
/*
* Copyright 2002 Niels Provos <provos@citi.umich.edu>
* All rights reserved.
*
* 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 Niels Provos.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_systrace.c,v 1.24 2003/02/16 20:24:47 provos Exp $");
#include "opt_systrace.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/tree.h>
#include <sys/malloc.h>
#include <sys/syscall.h>
#include <sys/vnode.h>
#include <sys/errno.h>
#include <sys/conf.h>
#include <sys/device.h>
#include <sys/proc.h>
#include <sys/file.h>
#include <sys/filedesc.h>
#include <sys/filio.h>
#include <sys/signalvar.h>
#include <sys/lock.h>
#include <sys/pool.h>
#include <sys/mount.h>
#include <sys/poll.h>
#include <sys/ptrace.h>
#include <sys/systrace.h>
#include <compat/common/compat_util.h>
#ifdef __NetBSD__
#define SYSTRACE_LOCK(fst, p) lockmgr(&fst->lock, LK_EXCLUSIVE, NULL)
#define SYSTRACE_UNLOCK(fst, p) lockmgr(&fst->lock, LK_RELEASE, NULL)
#else
#define SYSTRACE_LOCK(fst, p) lockmgr(&fst->lock, LK_EXCLUSIVE, NULL, p)
#define SYSTRACE_UNLOCK(fst, p) lockmgr(&fst->lock, LK_RELEASE, NULL, p)
#endif
#ifndef M_XDATA
#define M_XDATA M_FILE /* XXX */
#endif
#ifdef __NetBSD__
dev_type_open(systraceopen);
#else
cdev_decl(systrace);
#endif
#ifdef __NetBSD__
int systracef_read(struct file *, off_t *, struct uio *, struct ucred *,
int);
int systracef_write(struct file *, off_t *, struct uio *, struct ucred *,
int);
int systracef_fcntl(struct file *, u_int, caddr_t, struct proc *);
int systracef_poll(struct file *, int, struct proc *);
#else
int systracef_read(struct file *, off_t *, struct uio *, struct ucred *);
int systracef_write(struct file *, off_t *, struct uio *, struct ucred *);
int systracef_select(struct file *, int, struct proc *);
#endif
int systracef_kqfilter(struct file *, struct knote *);
int systracef_ioctl(struct file *, u_long, caddr_t, struct proc *);
int systracef_stat(struct file *, struct stat *, struct proc *);
int systracef_close(struct file *, struct proc *);
struct str_policy {
TAILQ_ENTRY(str_policy) next;
int nr;
const struct emul *emul; /* Is only valid for this emulation */
int refcount;
int nsysent;
u_char *sysent;
};
#define STR_PROC_ONQUEUE 0x01
#define STR_PROC_WAITANSWER 0x02
#define STR_PROC_SYSCALLRES 0x04
#define STR_PROC_REPORT 0x08 /* Report emulation */
#define STR_PROC_NEEDSEQNR 0x10 /* Answer must quote seqnr */
#define STR_PROC_SETEUID 0x20 /* Elevate privileges */
#define STR_PROC_SETEGID 0x40
struct str_process {
TAILQ_ENTRY(str_process) next;
TAILQ_ENTRY(str_process) msg_next;
struct proc *proc;
const struct emul *oldemul;
uid_t olduid;
gid_t oldgid;
pid_t pid;
struct fsystrace *parent;
struct str_policy *policy;
struct systrace_replace *replace;
int flags;
short answer;
short error;
u_int16_t seqnr; /* expected reply sequence number */
uid_t seteuid;
uid_t saveuid;
gid_t setegid;
gid_t savegid;
struct str_message msg;
};
uid_t systrace_seteuid(struct proc *, uid_t);
gid_t systrace_setegid(struct proc *, gid_t);
void systrace_lock(void);
void systrace_unlock(void);
/* Needs to be called with fst locked */
int systrace_attach(struct fsystrace *, pid_t);
int systrace_detach(struct str_process *);
int systrace_answer(struct str_process *, struct systrace_answer *);
int systrace_io(struct str_process *, struct systrace_io *);
int systrace_policy(struct fsystrace *, struct systrace_policy *);
int systrace_preprepl(struct str_process *, struct systrace_replace *);
int systrace_replace(struct str_process *, size_t, register_t []);
int systrace_getcwd(struct fsystrace *, struct str_process *);
int systrace_processready(struct str_process *);
struct proc *systrace_find(struct str_process *);
struct str_process *systrace_findpid(struct fsystrace *fst, pid_t pid);
void systrace_wakeup(struct fsystrace *);
void systrace_closepolicy(struct fsystrace *, struct str_policy *);
int systrace_insert_process(struct fsystrace *, struct proc *);
struct str_policy *systrace_newpolicy(struct fsystrace *, int);
int systrace_msg_child(struct fsystrace *, struct str_process *, pid_t);
int systrace_msg_ask(struct fsystrace *, struct str_process *,
int, size_t, register_t []);
int systrace_msg_result(struct fsystrace *, struct str_process *,
int, int, size_t, register_t [], register_t []);
int systrace_msg_emul(struct fsystrace *, struct str_process *);
int systrace_msg_ugid(struct fsystrace *, struct str_process *);
int systrace_make_msg(struct str_process *, int);
static struct fileops systracefops = {
systracef_read,
systracef_write,
systracef_ioctl,
#ifdef __NetBSD__
systracef_fcntl,
systracef_poll,
#else
systracef_select,
systracef_kqfilter,
#endif
systracef_stat,
systracef_close
#ifdef __NetBSD__
, systracef_kqfilter
#endif
};
struct pool systr_proc_pl;
struct pool systr_policy_pl;
int systrace_debug = 0;
struct lock systrace_lck;
#ifdef __NetBSD__
const struct cdevsw systrace_cdevsw = {
systraceopen, noclose, noread, nowrite, noioctl,
nostop, notty, nopoll, nommap, nokqfilter,
};
#endif
#define DPRINTF(y) if (systrace_debug) printf y;
/* ARGSUSED */
int
systracef_read(struct file *fp, off_t *poff, struct uio *uio,
struct ucred *cred
#ifdef __NetBSD__
, int flags
#endif
)
{
struct fsystrace *fst = (struct fsystrace *)fp->f_data;
struct str_process *process;
int error = 0;
if (uio->uio_resid != sizeof(struct str_message))
return (EINVAL);
again:
systrace_lock();
SYSTRACE_LOCK(fst, curlwp);
systrace_unlock();
if ((process = TAILQ_FIRST(&fst->messages)) != NULL) {
error = uiomove((caddr_t)&process->msg,
sizeof(struct str_message), uio);
if (!error) {
TAILQ_REMOVE(&fst->messages, process, msg_next);
CLR(process->flags, STR_PROC_ONQUEUE);
if (SYSTR_MSG_NOPROCESS(process))
pool_put(&systr_proc_pl, process);
}
} else if (TAILQ_FIRST(&fst->processes) == NULL) {
/* EOF situation */
;
} else {
if (fp->f_flag & FNONBLOCK)
error = EAGAIN;
else {
SYSTRACE_UNLOCK(fst, curlwp);
error = tsleep(fst, PWAIT|PCATCH, "systrrd", 0);
if (error)
goto out;
goto again;
}
}
SYSTRACE_UNLOCK(fst, curlwp);
out:
return (error);
}
/* ARGSUSED */
int
systracef_write(struct file *fp, off_t *poff, struct uio *uio,
struct ucred *cred
#ifdef __NetBSD__
, int flags
#endif
)
{
return (EIO);
}
#define POLICY_VALID(x) ((x) == SYSTR_POLICY_PERMIT || \
(x) == SYSTR_POLICY_ASK || \
(x) == SYSTR_POLICY_NEVER)
/* ARGSUSED */
int
systracef_ioctl(struct file *fp, u_long cmd, caddr_t data, struct proc *p)
{
int ret = 0;
struct fsystrace *fst = (struct fsystrace *)fp->f_data;
#ifdef __NetBSD__
struct cwdinfo *cwdp;
#else
struct filedesc *fdp;
#endif
struct str_process *strp = NULL;
pid_t pid = 0;
switch (cmd) {
case FIONBIO:
case FIOASYNC:
return (0);
case STRIOCDETACH:
case STRIOCREPORT:
pid = *(pid_t *)data;
if (!pid)
ret = EINVAL;
break;
case STRIOCANSWER:
pid = ((struct systrace_answer *)data)->stra_pid;
if (!pid)
ret = EINVAL;
break;
case STRIOCIO:
pid = ((struct systrace_io *)data)->strio_pid;
if (!pid)
ret = EINVAL;
break;
case STRIOCGETCWD:
pid = *(pid_t *)data;
if (!pid)
ret = EINVAL;
break;
case STRIOCATTACH:
case STRIOCRESCWD:
case STRIOCPOLICY:
break;
case STRIOCREPLACE:
pid = ((struct systrace_replace *)data)->strr_pid;
if (!pid)
ret = EINVAL;
break;
default:
ret = EINVAL;
break;
}
if (ret)
return (ret);
systrace_lock();
SYSTRACE_LOCK(fst, curlwp);
systrace_unlock();
if (pid) {
strp = systrace_findpid(fst, pid);
if (strp == NULL) {
ret = ESRCH;
goto unlock;
}
}
switch (cmd) {
case STRIOCATTACH:
pid = *(pid_t *)data;
if (!pid)
ret = EINVAL;
else
ret = systrace_attach(fst, pid);
DPRINTF(("%s: attach to %u: %d\n", __func__, pid, ret));
break;
case STRIOCDETACH:
ret = systrace_detach(strp);
break;
case STRIOCREPORT:
SET(strp->flags, STR_PROC_REPORT);
break;
case STRIOCANSWER:
ret = systrace_answer(strp, (struct systrace_answer *)data);
break;
case STRIOCIO:
ret = systrace_io(strp, (struct systrace_io *)data);
break;
case STRIOCPOLICY:
ret = systrace_policy(fst, (struct systrace_policy *)data);
break;
case STRIOCREPLACE:
ret = systrace_preprepl(strp, (struct systrace_replace *)data);
break;
case STRIOCRESCWD:
if (!fst->fd_pid) {
ret = EINVAL;
break;
}
#ifdef __NetBSD__
cwdp = p->p_cwdi;
/* Release cwd from other process */
if (cwdp->cwdi_cdir)
vrele(cwdp->cwdi_cdir);
if (cwdp->cwdi_rdir)
vrele(cwdp->cwdi_rdir);
cwdp->cwdi_cdir = fst->fd_cdir;
cwdp->cwdi_rdir = fst->fd_rdir;
#else
fdp = p->p_fd;
/* Release cwd from other process */
if (fdp->fd_cdir)
vrele(fdp->fd_cdir);
if (fdp->fd_rdir)
vrele(fdp->fd_rdir);
/* This restores the cwd we had before */
fdp->fd_cdir = fst->fd_cdir;
fdp->fd_rdir = fst->fd_rdir;
#endif
/* Note that we are normal again */
fst->fd_pid = 0;
fst->fd_cdir = fst->fd_rdir = NULL;
break;
case STRIOCGETCWD:
ret = systrace_getcwd(fst, strp);
break;
default:
ret = EINVAL;
break;
}
unlock:
SYSTRACE_UNLOCK(fst, curlwp);
return (ret);
}
#ifdef __NetBSD__
/* ARGSUSED */
int
systracef_fcntl(struct file *fp, u_int cmd, caddr_t data, struct proc *p)
{
if (cmd == FNONBLOCK || cmd == FASYNC)
return 0;
return (EOPNOTSUPP);
}
#endif
#ifdef __NetBSD__
int
systracef_poll(struct file *fp, int events, struct proc *p)
{
struct fsystrace *fst = (struct fsystrace *)fp->f_data;
int revents = 0;
if ((events & (POLLIN | POLLRDNORM)) == 0)
return (revents);
systrace_lock();
SYSTRACE_LOCK(fst, p);
systrace_unlock();
if (!TAILQ_EMPTY(&fst->messages))
revents |= events & (POLLIN | POLLRDNORM);
if (revents == 0)
selrecord(p, &fst->si);
SYSTRACE_UNLOCK(fst, p);
return (revents);
}
#else
int
systracef_select(struct file *fp, int which, struct proc *p)
{
struct fsystrace *fst = (struct fsystrace *)fp->f_data;
int ready = 0;
if (which != FREAD)
return (0);
systrace_lock();
SYSTRACE_LOCK(fst, p);
systrace_unlock();
ready = TAILQ_FIRST(&fst->messages) != NULL;
if (!ready)
selrecord(p, &fst->si);
SYSTRACE_UNLOCK(fst, p);
return (ready);
}
#endif /* __NetBSD__ */
/* ARGSUSED */
int
systracef_kqfilter(struct file *fp, struct knote *kn)
{
return (1);
}
/* ARGSUSED */
int
systracef_stat(struct file *fp, struct stat *sb, struct proc *p)
{
return (EOPNOTSUPP);
}
/* ARGSUSED */
int
systracef_close(struct file *fp, struct proc *p)
{
struct fsystrace *fst = (struct fsystrace *)fp->f_data;
struct str_process *strp;
struct str_policy *strpol;
systrace_lock();
SYSTRACE_LOCK(fst, curlwp);
systrace_unlock();
/* Untrace all processes */
for (strp = TAILQ_FIRST(&fst->processes); strp;
strp = TAILQ_FIRST(&fst->processes)) {
struct proc *q = strp->proc;
systrace_detach(strp);
psignal(q, SIGKILL);
}
/* Clean up fork and exit messages */
for (strp = TAILQ_FIRST(&fst->messages); strp;
strp = TAILQ_FIRST(&fst->messages)) {
TAILQ_REMOVE(&fst->messages, strp, msg_next);
pool_put(&systr_proc_pl, strp);
}
/* Clean up all policies */
for (strpol = TAILQ_FIRST(&fst->policies); strpol;
strpol = TAILQ_FIRST(&fst->policies))
systrace_closepolicy(fst, strpol);
/* Release vnodes */
if (fst->fd_cdir)
vrele(fst->fd_cdir);
if (fst->fd_rdir)
vrele(fst->fd_rdir);
SYSTRACE_UNLOCK(fst, curlwp);
FREE(fp->f_data, M_XDATA);
fp->f_data = NULL;
return (0);
}
void
systrace_lock(void)
{
#ifdef __NetBSD__
lockmgr(&systrace_lck, LK_EXCLUSIVE, NULL);
#else
lockmgr(&systrace_lck, LK_EXCLUSIVE, NULL, curlwp);
#endif
}
void
systrace_unlock(void)
{
#ifdef __NetBSD__
lockmgr(&systrace_lck, LK_RELEASE, NULL);
#else
lockmgr(&systrace_lck, LK_RELEASE, NULL, curlwp);
#endif
}
void
systrace_init(void)
{
pool_init(&systr_proc_pl, sizeof(struct str_process), 0, 0, 0,
"strprocpl", NULL);
pool_init(&systr_policy_pl, sizeof(struct str_policy), 0, 0, 0,
"strpolpl", NULL);
lockinit(&systrace_lck, PLOCK, "systrace", 0, 0);
}
int
systraceopen(dev_t dev, int flag, int mode, struct proc *p)
{
struct fsystrace *fst;
struct file *fp;
int error, fd;
/* falloc() will use the descriptor for us. */
if ((error = falloc(p, &fp, &fd)) != 0)
return (error);
MALLOC(fst, struct fsystrace *, sizeof(*fst), M_XDATA, M_WAITOK);
memset(fst, 0, sizeof(struct fsystrace));
lockinit(&fst->lock, PLOCK, "systrace", 0, 0);
TAILQ_INIT(&fst->processes);
TAILQ_INIT(&fst->messages);
TAILQ_INIT(&fst->policies);
if (suser(p->p_ucred, &p->p_acflag) == 0)
fst->issuser = 1;
fst->p_ruid = p->p_cred->p_ruid;
fst->p_rgid = p->p_cred->p_rgid;
fp->f_flag = FREAD | FWRITE;
fp->f_type = DTYPE_MISC;
fp->f_ops = &systracefops;
fp->f_data = (caddr_t) fst;
p->p_dupfd = fd;
FILE_SET_MATURE(fp);
FILE_UNUSE(fp, p);
return (ENXIO);
}
void
systrace_wakeup(struct fsystrace *fst)
{
wakeup((caddr_t)fst);
selwakeup(&fst->si);
}
struct proc *
systrace_find(struct str_process *strp)
{
struct proc *proc;
if ((proc = pfind(strp->pid)) == NULL)
return (NULL);
if (proc != strp->proc)
return (NULL);
if (!ISSET(proc->p_flag, P_SYSTRACE))
return (NULL);
return (proc);
}
void
systrace_sys_exit(struct proc *proc)
{
struct str_process *strp;
struct fsystrace *fst;
systrace_lock();
strp = proc->p_systrace;
if (strp != NULL) {
fst = strp->parent;
SYSTRACE_LOCK(fst, curlwp);
systrace_unlock();
/* Insert Exit message */
systrace_msg_child(fst, strp, -1);
systrace_detach(strp);
SYSTRACE_UNLOCK(fst, curlwp);
} else
systrace_unlock();
CLR(proc->p_flag, P_SYSTRACE);
}
void
systrace_sys_fork(struct proc *oldproc, struct proc *p)
{
struct str_process *oldstrp, *strp;
struct fsystrace *fst;
systrace_lock();
oldstrp = oldproc->p_systrace;
if (oldstrp == NULL) {
systrace_unlock();
return;
}
fst = oldstrp->parent;
SYSTRACE_LOCK(fst, curlwp);
systrace_unlock();
if (systrace_insert_process(fst, p))
goto out;
if ((strp = systrace_findpid(fst, p->p_pid)) == NULL)
panic("systrace_fork");
/* Reference policy */
if ((strp->policy = oldstrp->policy) != NULL)
strp->policy->refcount++;
/* Insert fork message */
systrace_msg_child(fst, oldstrp, p->p_pid);
out:
SYSTRACE_UNLOCK(fst, curlwp);
}
int
systrace_enter(struct proc *p, register_t code, void *v, register_t retval[])
{
const struct sysent *callp;
struct str_process *strp;
struct str_policy *strpolicy;
struct fsystrace *fst;
struct pcred *pc;
int policy, error = 0, report = 0, maycontrol = 0, issuser = 0;
systrace_lock();
strp = p->p_systrace;
if (strp == NULL) {
systrace_unlock();
return (EINVAL);
}
KASSERT(strp->proc == p);
fst = strp->parent;
SYSTRACE_LOCK(fst, p);
systrace_unlock();
/*
* We can not monitor a SUID process unless we are root,
* but we wait until it executes something unprivileged.
* A non-root user may only monitor if the real uid and
* real gid match the monitored process. Changing the
* uid or gid causes P_SUGID to be set.
*/
if (fst->issuser) {
maycontrol = 1;
issuser = 1;
} else if (!(p->p_flag & P_SUGID)) {
maycontrol = fst->p_ruid == p->p_cred->p_ruid &&
fst->p_rgid == p->p_cred->p_rgid;
}
if (!maycontrol) {
policy = SYSTR_POLICY_PERMIT;
} else {
/* Find out current policy */
if ((strpolicy = strp->policy) == NULL)
policy = SYSTR_POLICY_ASK;
else {
if (code >= strpolicy->nsysent)
policy = SYSTR_POLICY_NEVER;
else
policy = strpolicy->sysent[code];
}
}
callp = p->p_emul->e_sysent + code;
switch (policy) {
case SYSTR_POLICY_PERMIT:
break;
case SYSTR_POLICY_ASK:
/* Puts the current process to sleep, return unlocked */
error = systrace_msg_ask(fst, strp, code, callp->sy_argsize, v);
/* lock has been released in systrace_msg_ask() */
fst = NULL;
/* We might have detached by now for some reason */
if (!error && (strp = p->p_systrace) != NULL) {
/* XXX - do I need to lock here? */
if (strp->answer == SYSTR_POLICY_NEVER) {
error = strp->error;
if (strp->replace != NULL) {
free(strp->replace, M_XDATA);
strp->replace = NULL;
}
} else {
if (ISSET(strp->flags, STR_PROC_SYSCALLRES)) {
#ifndef __NetBSD__
CLR(strp->flags, STR_PROC_SYSCALLRES);
#endif
report = 1;
}
/* Replace the arguments if necessary */
if (strp->replace != NULL) {
error = systrace_replace(strp, callp->sy_argsize, v);
}
}
}
break;
default:
if (policy > 0)
error = policy;
else
error = EPERM;
break;
}
if (fst) {
SYSTRACE_UNLOCK(fst, p);
}
systrace_lock();
if ((strp = p->p_systrace) == NULL)
goto out;
if (error) {
strp->oldemul = NULL;
goto out;
}
pc = p->p_cred;
strp->oldemul = p->p_emul;
strp->olduid = pc->p_ruid;
strp->oldgid = pc->p_rgid;
/* Elevate privileges as desired */
if (issuser) {
if (ISSET(strp->flags, STR_PROC_SETEUID))
strp->saveuid = systrace_seteuid(p, strp->seteuid);
if (ISSET(strp->flags, STR_PROC_SETEGID))
strp->savegid = systrace_setegid(p, strp->setegid);
} else
CLR(strp->flags, STR_PROC_SETEUID|STR_PROC_SETEGID);
out:
systrace_unlock();
return (error);
}
void
systrace_exit(struct proc *p, register_t code, void *v, register_t retval[],
int error)
{
const struct sysent *callp;
struct str_process *strp;
struct fsystrace *fst;
struct pcred *pc;
/* Report change in emulation */
systrace_lock();
strp = p->p_systrace;
if (strp == NULL || strp->oldemul == NULL) {
systrace_unlock();
return;
}
DPRINTF(("exit syscall %lu, oldemul %p\n", (u_long)code, strp->oldemul));
/* Return to old privileges */
pc = p->p_cred;
if (ISSET(strp->flags, STR_PROC_SETEUID)) {
if (pc->pc_ucred->cr_uid == strp->seteuid)
systrace_seteuid(p, strp->saveuid);
CLR(strp->flags, STR_PROC_SETEUID);
}
if (ISSET(strp->flags, STR_PROC_SETEGID)) {
if (pc->pc_ucred->cr_gid == strp->setegid)
systrace_setegid(p, strp->savegid);
CLR(strp->flags, STR_PROC_SETEGID);
}
if (p->p_flag & P_SUGID) {
if ((fst = strp->parent) == NULL || !fst->issuser) {
systrace_unlock();
return;
}
}
/* See if we should force a report */
if (ISSET(strp->flags, STR_PROC_REPORT)) {
CLR(strp->flags, STR_PROC_REPORT);
strp->oldemul = NULL;
}
if (p->p_emul != strp->oldemul && strp != NULL) {
fst = strp->parent;
SYSTRACE_LOCK(fst, p);
systrace_unlock();
/* Old policy is without meaning now */
if (strp->policy) {
systrace_closepolicy(fst, strp->policy);
strp->policy = NULL;
}
systrace_msg_emul(fst, strp);
} else
systrace_unlock();
/* Report if effective uid or gid changed */
systrace_lock();
strp = p->p_systrace;
if (strp != NULL && (strp->olduid != p->p_cred->p_ruid ||
strp->oldgid != p->p_cred->p_rgid)) {
fst = strp->parent;
SYSTRACE_LOCK(fst, p);
systrace_unlock();
systrace_msg_ugid(fst, strp);
} else
systrace_unlock();
/* Report result from system call */
systrace_lock();
strp = p->p_systrace;
if (strp != NULL && ISSET(strp->flags, STR_PROC_SYSCALLRES)) {
CLR(strp->flags, STR_PROC_SYSCALLRES);
fst = strp->parent;
SYSTRACE_LOCK(fst, p);
systrace_unlock();
DPRINTF(("will ask syscall %lu, strp %p\n", (u_long)code, strp));
callp = p->p_emul->e_sysent + code;
systrace_msg_result(fst, strp, error, code,
callp->sy_argsize, v, retval);
} else {
DPRINTF(("will not ask syscall %lu, strp %p\n", (u_long)code, strp));
systrace_unlock();
}
}
uid_t
systrace_seteuid(struct proc *p, uid_t euid)
{
struct pcred *pc = p->p_cred;
uid_t oeuid = pc->pc_ucred->cr_uid;
if (pc->pc_ucred->cr_uid == euid)
return (oeuid);
/*
* Copy credentials so other references do not see our changes.
*/
pc->pc_ucred = crcopy(pc->pc_ucred);
pc->pc_ucred->cr_uid = euid;
p_sugid(p);
return (oeuid);
}
gid_t
systrace_setegid(struct proc *p, gid_t egid)
{
struct pcred *pc = p->p_cred;
gid_t oegid = pc->pc_ucred->cr_gid;
if (pc->pc_ucred->cr_gid == egid)
return (oegid);
/*
* Copy credentials so other references do not see our changes.
*/
pc->pc_ucred = crcopy(pc->pc_ucred);
pc->pc_ucred->cr_gid = egid;
p_sugid(p);
return (oegid);
}
/* Called with fst locked */
int
systrace_answer(struct str_process *strp, struct systrace_answer *ans)
{
int error = 0;
DPRINTF(("%s: %u: policy %d\n", __func__,
ans->stra_pid, ans->stra_policy));
if (!POLICY_VALID(ans->stra_policy)) {
error = EINVAL;
goto out;
}
/* Check if answer is in sync with us */
if (ans->stra_seqnr != strp->seqnr) {
error = ESRCH;
goto out;
}
if ((error = systrace_processready(strp)) != 0)
goto out;
strp->answer = ans->stra_policy;
strp->error = ans->stra_error;
if (!strp->error)
strp->error = EPERM;
if (ISSET(ans->stra_flags, SYSTR_FLAGS_RESULT))
SET(strp->flags, STR_PROC_SYSCALLRES);
/* See if we should elevate privileges for this system call */
if (ISSET(ans->stra_flags, SYSTR_FLAGS_SETEUID)) {
SET(strp->flags, STR_PROC_SETEUID);
strp->seteuid = ans->stra_seteuid;
}
if (ISSET(ans->stra_flags, SYSTR_FLAGS_SETEGID)) {
SET(strp->flags, STR_PROC_SETEGID);
strp->setegid = ans->stra_setegid;
}
/* Clearing the flag indicates to the process that it woke up */
CLR(strp->flags, STR_PROC_WAITANSWER);
wakeup(strp);
out:
return (error);
}
int
systrace_policy(struct fsystrace *fst, struct systrace_policy *pol)
{
struct str_policy *strpol;
struct str_process *strp;
switch(pol->strp_op) {
case SYSTR_POLICY_NEW:
DPRINTF(("%s: new, ents %d\n", __func__,
pol->strp_maxents));
if (pol->strp_maxents <= 0 || pol->strp_maxents > 1024)
return (EINVAL);
strpol = systrace_newpolicy(fst, pol->strp_maxents);
if (strpol == NULL)
return (ENOBUFS);
pol->strp_num = strpol->nr;
break;
case SYSTR_POLICY_ASSIGN:
DPRINTF(("%s: %d -> pid %d\n", __func__,
pol->strp_num, pol->strp_pid));
/* Find right policy by number */
TAILQ_FOREACH(strpol, &fst->policies, next)
if (strpol->nr == pol->strp_num)
break;
if (strpol == NULL)
return (EINVAL);
strp = systrace_findpid(fst, pol->strp_pid);
if (strp == NULL)
return (EINVAL);
/* Check that emulation matches */
if (strpol->emul && strpol->emul != strp->proc->p_emul)
return (EINVAL);
if (strp->policy)
systrace_closepolicy(fst, strp->policy);
strp->policy = strpol;
strpol->refcount++;
/* Record emulation for this policy */
if (strpol->emul == NULL)
strpol->emul = strp->proc->p_emul;
break;
case SYSTR_POLICY_MODIFY:
DPRINTF(("%s: %d: code %d -> policy %d\n", __func__,
pol->strp_num, pol->strp_code, pol->strp_policy));
if (!POLICY_VALID(pol->strp_policy))
return (EINVAL);
TAILQ_FOREACH(strpol, &fst->policies, next)
if (strpol->nr == pol->strp_num)
break;
if (strpol == NULL)
return (EINVAL);
if (pol->strp_code < 0 || pol->strp_code >= strpol->nsysent)
return (EINVAL);
strpol->sysent[pol->strp_code] = pol->strp_policy;
break;
default:
return (EINVAL);
}
return (0);
}
int
systrace_processready(struct str_process *strp)
{
if (ISSET(strp->flags, STR_PROC_ONQUEUE))
return (EBUSY);
if (!ISSET(strp->flags, STR_PROC_WAITANSWER))
return (EBUSY);
/* XXX - ignore until systrace knows about lwps. :-(
if (strp->proc->p_stat != LSSLEEP)
return (EBUSY);
*/
return (0);
}
int
systrace_getcwd(struct fsystrace *fst, struct str_process *strp)
{
#ifdef __NetBSD__
struct cwdinfo *mycwdp, *cwdp;
#else
struct filedesc *myfdp, *fdp;
#endif
int error;
DPRINTF(("%s: %d\n", __func__, strp->pid));
error = systrace_processready(strp);
if (error)
return (error);
#ifdef __NetBSD__
mycwdp = curproc->p_cwdi;
cwdp = strp->proc->p_cwdi;
if (mycwdp == NULL || cwdp == NULL)
return (EINVAL);
/* Store our current values */
fst->fd_pid = strp->pid;
fst->fd_cdir = mycwdp->cwdi_cdir;
fst->fd_rdir = mycwdp->cwdi_rdir;
if ((mycwdp->cwdi_cdir = cwdp->cwdi_cdir) != NULL)
VREF(mycwdp->cwdi_cdir);
if ((mycwdp->cwdi_rdir = cwdp->cwdi_rdir) != NULL)
VREF(mycwdp->cwdi_rdir);
#else
myfdp = curlwp->p_fd;
fdp = strp->proc->p_fd;
if (myfdp == NULL || fdp == NULL)
return (EINVAL);
/* Store our current values */
fst->fd_pid = strp->pid;
fst->fd_cdir = myfdp->fd_cdir;
fst->fd_rdir = myfdp->fd_rdir;
if ((myfdp->fd_cdir = fdp->fd_cdir) != NULL)
VREF(myfdp->fd_cdir);
if ((myfdp->fd_rdir = fdp->fd_rdir) != NULL)
VREF(myfdp->fd_rdir);
#endif
return (0);
}
int
systrace_io(struct str_process *strp, struct systrace_io *io)
{
struct proc *p = curproc, *t = strp->proc;
struct uio uio;
struct iovec iov;
int error = 0;
DPRINTF(("%s: %u: %p(%lu)\n", __func__,
io->strio_pid, io->strio_offs, (u_long)io->strio_len));
switch (io->strio_op) {
case SYSTR_READ:
uio.uio_rw = UIO_READ;
break;
case SYSTR_WRITE:
uio.uio_rw = UIO_WRITE;
break;
default:
return (EINVAL);
}
error = systrace_processready(strp);
if (error)
goto out;
iov.iov_base = io->strio_addr;
iov.iov_len = io->strio_len;
uio.uio_iov = &iov;
uio.uio_iovcnt = 1;
uio.uio_offset = (off_t)(long)io->strio_offs;
uio.uio_resid = io->strio_len;
uio.uio_segflg = UIO_USERSPACE;
uio.uio_procp = p;
#ifdef __NetBSD__
error = process_domem(p, t, &uio);
#else
error = procfs_domem(p, t, NULL, &uio);
#endif
io->strio_len -= uio.uio_resid;
out:
return (error);
}
int
systrace_attach(struct fsystrace *fst, pid_t pid)
{
int error = 0;
struct proc *proc, *p = curproc;
if ((proc = pfind(pid)) == NULL) {
error = ESRCH;
goto out;
}
if (ISSET(proc->p_flag, P_INEXEC)) {
error = EAGAIN;
goto out;
}
/*
* You can't attach to a process if:
* (1) it's the process that's doing the attaching,
*/
if (proc->p_pid == p->p_pid) {
error = EINVAL;
goto out;
}
/*
* (2) it's a system process
*/
if (ISSET(proc->p_flag, P_SYSTEM)) {
error = EPERM;
goto out;
}
/*
* (3) it's being traced already
*/
if (ISSET(proc->p_flag, P_SYSTRACE)) {
error = EBUSY;
goto out;
}
/*
* (4) it's not owned by you, or the last exec
* gave us setuid/setgid privs (unless
* you're root), or...
*
* [Note: once P_SUGID gets set in execve(), it stays
* set until the process does another execve(). Hence
* this prevents a setuid process which revokes it's
* special privilidges using setuid() from being
* traced. This is good security.]
*/
if ((proc->p_cred->p_ruid != p->p_cred->p_ruid ||
ISSET(proc->p_flag, P_SUGID)) &&
(error = suser(p->p_ucred, &p->p_acflag)) != 0)
goto out;
/*
* (5) ...it's init, which controls the security level
* of the entire system, and the system was not
* compiled with permanently insecure mode turned
* on.
*/
if ((proc->p_pid == 1) && (securelevel > -1)) {
error = EPERM;
goto out;
}
error = systrace_insert_process(fst, proc);
#if defined(__NetBSD__) && defined(__HAVE_SYSCALL_INTERN)
/*
* Make sure we're using the version of the syscall handler that
* has systrace hooks.
*/
if (!error)
(*proc->p_emul->e_syscall_intern)(proc);
#endif
out:
return (error);
}
/* Prepare to replace arguments */
int
systrace_preprepl(struct str_process *strp, struct systrace_replace *repl)
{
size_t len;
int i, ret = 0;
ret = systrace_processready(strp);
if (ret)
return (ret);
if (strp->replace != NULL) {
free(strp->replace, M_XDATA);
strp->replace = NULL;
}
if (repl->strr_nrepl < 0 || repl->strr_nrepl > SYSTR_MAXARGS)
return (EINVAL);
for (i = 0, len = 0; i < repl->strr_nrepl; i++) {
len += repl->strr_offlen[i];
if (repl->strr_offlen[i] == 0)
continue;
if (repl->strr_offlen[i] + repl->strr_off[i] > len)
return (EINVAL);
}
/* Make sure that the length adds up */
if (repl->strr_len != len)
return (EINVAL);
/* Check against a maximum length */
if (repl->strr_len > 2048)
return (EINVAL);
strp->replace = (struct systrace_replace *)
malloc(sizeof(struct systrace_replace) + len, M_XDATA, M_WAITOK);
memcpy(strp->replace, repl, sizeof(struct systrace_replace));
ret = copyin(repl->strr_base, strp->replace + 1, len);
if (ret) {
free(strp->replace, M_XDATA);
strp->replace = NULL;
return (ret);
}
/* Adjust the offset */
repl = strp->replace;
repl->strr_base = (caddr_t)(repl + 1);
return (0);
}
/*
* Replace the arguments with arguments from the monitoring process.
*/
int
systrace_replace(struct str_process *strp, size_t argsize, register_t args[])
{
struct proc *p = strp->proc;
struct systrace_replace *repl = strp->replace;
caddr_t sg, kdata, udata, kbase, ubase;
int i, maxarg, ind, ret = 0;
maxarg = argsize/sizeof(register_t);
#ifdef __NetBSD__
sg = stackgap_init(p, 0);
ubase = stackgap_alloc(p, &sg, repl->strr_len);
#else
sg = stackgap_init(p->p_emul);
ubase = stackgap_alloc(&sg, repl->strr_len);
#endif
kbase = repl->strr_base;
for (i = 0; i < maxarg && i < repl->strr_nrepl; i++) {
ind = repl->strr_argind[i];
if (ind < 0 || ind >= maxarg) {
ret = EINVAL;
goto out;
}
if (repl->strr_offlen[i] == 0) {
args[ind] = repl->strr_off[i];
continue;
}
kdata = kbase + repl->strr_off[i];
udata = ubase + repl->strr_off[i];
if (copyout(kdata, udata, repl->strr_offlen[i])) {
ret = EINVAL;
goto out;
}
/* Replace the argument with the new address */
args[ind] = (register_t)(intptr_t)udata;
}
out:
free(repl, M_XDATA);
strp->replace = NULL;
return (ret);
}
struct str_process *
systrace_findpid(struct fsystrace *fst, pid_t pid)
{
struct str_process *strp;
struct proc *proc = NULL;
TAILQ_FOREACH(strp, &fst->processes, next)
if (strp->pid == pid)
break;
if (strp == NULL)
return (NULL);
proc = systrace_find(strp);
return (proc ? strp : NULL);
}
int
systrace_detach(struct str_process *strp)
{
struct proc *proc;
struct fsystrace *fst = NULL;
int error = 0;
DPRINTF(("%s: Trying to detach from %d\n", __func__, strp->pid));
if ((proc = systrace_find(strp)) != NULL) {
CLR(proc->p_flag, P_SYSTRACE);
proc->p_systrace = NULL;
} else
error = ESRCH;
if (ISSET(strp->flags, STR_PROC_WAITANSWER)) {
CLR(strp->flags, STR_PROC_WAITANSWER);
wakeup(strp);
}
fst = strp->parent;
systrace_wakeup(fst);
if (ISSET(strp->flags, STR_PROC_ONQUEUE))
TAILQ_REMOVE(&fst->messages, strp, msg_next);
TAILQ_REMOVE(&fst->processes, strp, next);
fst->nprocesses--;
if (strp->policy)
systrace_closepolicy(fst, strp->policy);
if (strp->replace)
free(strp->replace, M_XDATA);
pool_put(&systr_proc_pl, strp);
return (error);
}
void
systrace_closepolicy(struct fsystrace *fst, struct str_policy *policy)
{
if (--policy->refcount)
return;
fst->npolicies--;
if (policy->nsysent)
free(policy->sysent, M_XDATA);
TAILQ_REMOVE(&fst->policies, policy, next);
pool_put(&systr_policy_pl, policy);
}
int
systrace_insert_process(struct fsystrace *fst, struct proc *proc)
{
struct str_process *strp;
strp = pool_get(&systr_proc_pl, PR_NOWAIT);
if (strp == NULL)
return (ENOBUFS);
memset((caddr_t)strp, 0, sizeof(struct str_process));
strp->pid = proc->p_pid;
strp->proc = proc;
strp->parent = fst;
TAILQ_INSERT_TAIL(&fst->processes, strp, next);
fst->nprocesses++;
proc->p_systrace = strp;
SET(proc->p_flag, P_SYSTRACE);
return (0);
}
struct str_policy *
systrace_newpolicy(struct fsystrace *fst, int maxents)
{
struct str_policy *pol;
int i;
if (fst->npolicies > SYSTR_MAX_POLICIES && !fst->issuser)
return (NULL);
pol = pool_get(&systr_policy_pl, PR_NOWAIT);
if (pol == NULL)
return (NULL);
DPRINTF(("%s: allocating %d -> %lu\n", __func__,
maxents, (u_long)maxents * sizeof(int)));
memset((caddr_t)pol, 0, sizeof(struct str_policy));
pol->sysent = (u_char *)malloc(maxents * sizeof(u_char),
M_XDATA, M_WAITOK);
pol->nsysent = maxents;
for (i = 0; i < maxents; i++)
pol->sysent[i] = SYSTR_POLICY_ASK;
fst->npolicies++;
pol->nr = fst->npolicynr++;
pol->refcount = 1;
TAILQ_INSERT_TAIL(&fst->policies, pol, next);
return (pol);
}
int
systrace_msg_ask(struct fsystrace *fst, struct str_process *strp,
int code, size_t argsize, register_t args[])
{
struct str_msg_ask *msg_ask = &strp->msg.msg_data.msg_ask;
int i;
msg_ask->code = code;
msg_ask->argsize = argsize;
for (i = 0; i < (argsize/sizeof(register_t)) && i < SYSTR_MAXARGS; i++)
msg_ask->args[i] = args[i];
return (systrace_make_msg(strp, SYSTR_MSG_ASK));
}
int
systrace_msg_result(struct fsystrace *fst, struct str_process *strp,
int error, int code, size_t argsize, register_t args[], register_t rval[])
{
struct str_msg_ask *msg_ask = &strp->msg.msg_data.msg_ask;
int i;
msg_ask->code = code;
msg_ask->argsize = argsize;
msg_ask->result = error;
for (i = 0; i < (argsize/sizeof(register_t)) && i < SYSTR_MAXARGS; i++)
msg_ask->args[i] = args[i];
msg_ask->rval[0] = rval[0];
msg_ask->rval[1] = rval[1];
return (systrace_make_msg(strp, SYSTR_MSG_RES));
}
int
systrace_msg_emul(struct fsystrace *fst, struct str_process *strp)
{
struct str_msg_emul *msg_emul = &strp->msg.msg_data.msg_emul;
struct proc *p = strp->proc;
memcpy(msg_emul->emul, p->p_emul->e_name, SYSTR_EMULEN);
return (systrace_make_msg(strp, SYSTR_MSG_EMUL));
}
int
systrace_msg_ugid(struct fsystrace *fst, struct str_process *strp)
{
struct str_msg_ugid *msg_ugid = &strp->msg.msg_data.msg_ugid;
struct proc *p = strp->proc;
msg_ugid->uid = p->p_cred->p_ruid;
msg_ugid->gid = p->p_cred->p_rgid;
return (systrace_make_msg(strp, SYSTR_MSG_UGID));
}
int
systrace_make_msg(struct str_process *strp, int type)
{
struct str_message *msg = &strp->msg;
struct fsystrace *fst = strp->parent;
#ifndef __NetBSD__
struct proc *p = strp->proc;
#endif
int st;
msg->msg_seqnr = ++strp->seqnr;
msg->msg_type = type;
msg->msg_pid = strp->pid;
if (strp->policy)
msg->msg_policy = strp->policy->nr;
else
msg->msg_policy = -1;
SET(strp->flags, STR_PROC_WAITANSWER);
if (ISSET(strp->flags, STR_PROC_ONQUEUE))
goto out;
TAILQ_INSERT_TAIL(&fst->messages, strp, msg_next);
SET(strp->flags, STR_PROC_ONQUEUE);
out:
systrace_wakeup(fst);
/* Release the lock - XXX */
#ifndef __NetBSD__
SYSTRACE_UNLOCK(fst, p);
#else
SYSTRACE_UNLOCK(fst, strp->proc);
#endif
while (1) {
st = tsleep(strp, PWAIT | PCATCH, "systrmsg", 0);
if (st != 0)
return (EINTR);
/* If we detach, then everything is permitted */
if ((strp = curproc->p_systrace) == NULL)
return (0);
if (!ISSET(strp->flags, STR_PROC_WAITANSWER))
break;
}
return (0);
}
int
systrace_msg_child(struct fsystrace *fst, struct str_process *strp, pid_t npid)
{
struct str_process *nstrp;
struct str_message *msg;
struct str_msg_child *msg_child;
nstrp = pool_get(&systr_proc_pl, PR_WAITOK);
memset(nstrp, 0, sizeof(struct str_process));
DPRINTF(("%s: %p: pid %d -> pid %d\n", __func__,
nstrp, strp->pid, npid));
msg = &nstrp->msg;
msg_child = &msg->msg_data.msg_child;
msg->msg_type = SYSTR_MSG_CHILD;
msg->msg_pid = strp->pid;
if (strp->policy)
msg->msg_policy = strp->policy->nr;
else
msg->msg_policy = -1;
msg_child->new_pid = npid;
TAILQ_INSERT_TAIL(&fst->messages, nstrp, msg_next);
systrace_wakeup(fst);
return (0);
}
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