/* $OpenBSD: kern_ktrace.c,v 1.42 2007/05/16 17:27:30 art Exp $ */
/* $NetBSD: kern_ktrace.c,v 1.23 1996/02/09 18:59:36 christos Exp $ */
/*
* Copyright (c) 1989, 1993
* The Regents of the University of California. 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. 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_ktrace.c 8.2 (Berkeley) 9/23/93
*/
#ifdef KTRACE
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/sched.h>
#include <sys/file.h>
#include <sys/namei.h>
#include <sys/vnode.h>
#include <sys/ktrace.h>
#include <sys/malloc.h>
#include <sys/syslog.h>
#include <sys/sysctl.h>
#include <sys/mount.h>
#include <sys/syscall.h>
#include <sys/syscallargs.h>
#include <uvm/uvm_extern.h>
void ktrinitheader(struct ktr_header *, struct proc *, int);
int ktrops(struct proc *, struct proc *, int, int, struct vnode *);
int ktrsetchildren(struct proc *, struct proc *, int, int,
struct vnode *);
int ktrwrite(struct proc *, struct ktr_header *);
int ktrcanset(struct proc *, struct proc *);
/*
* Change the trace vnode in a correct way (to avoid races).
*/
void
ktrsettracevnode(struct proc *p, struct vnode *newvp)
{
struct vnode *vp;
if (p->p_tracep == newvp) /* avoid work */
return;
if (newvp != NULL)
VREF(newvp);
vp = p->p_tracep;
p->p_tracep = newvp;
if (vp != NULL)
vrele(vp);
}
void
ktrinitheader(struct ktr_header *kth, struct proc *p, int type)
{
bzero(kth, sizeof (struct ktr_header));
kth->ktr_type = type;
microtime(&kth->ktr_time);
kth->ktr_pid = p->p_pid;
bcopy(p->p_comm, kth->ktr_comm, MAXCOMLEN);
}
void
ktrsyscall(struct proc *p, register_t code, size_t argsize, register_t args[])
{
struct ktr_header kth;
struct ktr_syscall *ktp;
size_t len = sizeof(struct ktr_syscall) + argsize;
register_t *argp;
u_int nargs = 0;
int i;
if (code == SYS___sysctl && (p->p_emul->e_flags & EMUL_NATIVE)) {
/*
* The native sysctl encoding stores the mib[]
* array because it is interesting.
*/
if (args[1] > 0)
nargs = min(args[1], CTL_MAXNAME);
len += nargs * sizeof(int);
}
p->p_traceflag |= KTRFAC_ACTIVE;
ktrinitheader(&kth, p, KTR_SYSCALL);
ktp = malloc(len, M_TEMP, M_WAITOK);
ktp->ktr_code = code;
ktp->ktr_argsize = argsize;
argp = (register_t *)((char *)ktp + sizeof(struct ktr_syscall));
for (i = 0; i < (argsize / sizeof *argp); i++)
*argp++ = args[i];
if (code == SYS___sysctl && (p->p_emul->e_flags & EMUL_NATIVE) &&
nargs &&
copyin((void *)args[0], argp, nargs * sizeof(int)))
bzero(argp, nargs * sizeof(int));
kth.ktr_buf = (caddr_t)ktp;
kth.ktr_len = len;
ktrwrite(p, &kth);
free(ktp, M_TEMP);
p->p_traceflag &= ~KTRFAC_ACTIVE;
}
void
ktrsysret(struct proc *p, register_t code, int error, register_t retval)
{
struct ktr_header kth;
struct ktr_sysret ktp;
p->p_traceflag |= KTRFAC_ACTIVE;
ktrinitheader(&kth, p, KTR_SYSRET);
ktp.ktr_code = code;
ktp.ktr_error = error;
ktp.ktr_retval = retval; /* what about val2 ? */
kth.ktr_buf = (caddr_t)&ktp;
kth.ktr_len = sizeof(struct ktr_sysret);
ktrwrite(p, &kth);
p->p_traceflag &= ~KTRFAC_ACTIVE;
}
void
ktrnamei(struct proc *p, char *path)
{
struct ktr_header kth;
p->p_traceflag |= KTRFAC_ACTIVE;
ktrinitheader(&kth, p, KTR_NAMEI);
kth.ktr_len = strlen(path);
kth.ktr_buf = path;
ktrwrite(p, &kth);
p->p_traceflag &= ~KTRFAC_ACTIVE;
}
void
ktremul(struct proc *p, char *emul)
{
struct ktr_header kth;
p->p_traceflag |= KTRFAC_ACTIVE;
ktrinitheader(&kth, p, KTR_EMUL);
kth.ktr_len = strlen(emul);
kth.ktr_buf = emul;
ktrwrite(p, &kth);
p->p_traceflag &= ~KTRFAC_ACTIVE;
}
void
ktrgenio(struct proc *p, int fd, enum uio_rw rw, struct iovec *iov, int len,
int error)
{
struct ktr_header kth;
struct ktr_genio *ktp;
caddr_t cp;
int resid = len, count;
int buflen;
if (error)
return;
p->p_traceflag |= KTRFAC_ACTIVE;
buflen = min(PAGE_SIZE, len + sizeof(struct ktr_genio));
ktrinitheader(&kth, p, KTR_GENIO);
ktp = malloc(buflen, M_TEMP, M_WAITOK);
ktp->ktr_fd = fd;
ktp->ktr_rw = rw;
kth.ktr_buf = (caddr_t)ktp;
cp = (caddr_t)((char *)ktp + sizeof (struct ktr_genio));
buflen -= sizeof(struct ktr_genio);
while (resid > 0) {
/*
* Don't allow this process to hog the cpu when doing
* huge I/O.
*/
if (curcpu()->ci_schedstate.spc_schedflags & SPCF_SHOULDYIELD)
preempt(NULL);
count = min(iov->iov_len, buflen);
if (count > resid)
count = resid;
if (copyin(iov->iov_base, cp, count))
break;
kth.ktr_len = count + sizeof(struct ktr_genio);
if (ktrwrite(p, &kth) != 0)
break;
iov->iov_len -= count;
iov->iov_base = (caddr_t)iov->iov_base + count;
if (iov->iov_len == 0)
iov++;
resid -= count;
}
free(ktp, M_TEMP);
p->p_traceflag &= ~KTRFAC_ACTIVE;
}
void
ktrpsig(struct proc *p, int sig, sig_t action, int mask, int code,
siginfo_t *si)
{
struct ktr_header kth;
struct ktr_psig kp;
p->p_traceflag |= KTRFAC_ACTIVE;
ktrinitheader(&kth, p, KTR_PSIG);
kp.signo = (char)sig;
kp.action = action;
kp.mask = mask;
kp.code = code;
kp.si = *si;
kth.ktr_buf = (caddr_t)&kp;
kth.ktr_len = sizeof(struct ktr_psig);
ktrwrite(p, &kth);
p->p_traceflag &= ~KTRFAC_ACTIVE;
}
void
ktrcsw(struct proc *p, int out, int user)
{
struct ktr_header kth;
struct ktr_csw kc;
p->p_traceflag |= KTRFAC_ACTIVE;
ktrinitheader(&kth, p, KTR_CSW);
kc.out = out;
kc.user = user;
kth.ktr_buf = (caddr_t)&kc;
kth.ktr_len = sizeof(struct ktr_csw);
ktrwrite(p, &kth);
p->p_traceflag &= ~KTRFAC_ACTIVE;
}
/* Interface and common routines */
/*
* ktrace system call
*/
/* ARGSUSED */
int
sys_ktrace(struct proc *curp, void *v, register_t *retval)
{
struct sys_ktrace_args /* {
syscallarg(const char *) fname;
syscallarg(int) ops;
syscallarg(int) facs;
syscallarg(pid_t) pid;
} */ *uap = v;
struct vnode *vp = NULL;
struct proc *p = NULL;
struct pgrp *pg;
int facs = SCARG(uap, facs) & ~((unsigned) KTRFAC_ROOT);
int ops = KTROP(SCARG(uap, ops));
int descend = SCARG(uap, ops) & KTRFLAG_DESCEND;
int ret = 0;
int error = 0;
struct nameidata nd;
curp->p_traceflag |= KTRFAC_ACTIVE;
if (ops != KTROP_CLEAR) {
/*
* an operation which requires a file argument.
*/
NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, SCARG(uap, fname),
curp);
if ((error = vn_open(&nd, FREAD|FWRITE|O_NOFOLLOW, 0)) != 0) {
curp->p_traceflag &= ~KTRFAC_ACTIVE;
return (error);
}
vp = nd.ni_vp;
VOP_UNLOCK(vp, 0, curp);
if (vp->v_type != VREG) {
(void) vn_close(vp, FREAD|FWRITE, curp->p_ucred, curp);
curp->p_traceflag &= ~KTRFAC_ACTIVE;
return (EACCES);
}
}
/*
* Clear all uses of the tracefile
*/
if (ops == KTROP_CLEARFILE) {
for (p = LIST_FIRST(&allproc); p; p = LIST_NEXT(p, p_list)) {
if (p->p_tracep == vp) {
if (ktrcanset(curp, p)) {
p->p_traceflag = 0;
ktrsettracevnode(p, NULL);
} else
error = EPERM;
}
}
goto done;
}
/*
* need something to (un)trace (XXX - why is this here?)
*/
if (!facs) {
error = EINVAL;
goto done;
}
/*
* do it
*/
if (SCARG(uap, pid) < 0) {
/*
* by process group
*/
pg = pgfind(-SCARG(uap, pid));
if (pg == NULL) {
error = ESRCH;
goto done;
}
LIST_FOREACH(p, &pg->pg_members, p_pglist)
if (descend)
ret |= ktrsetchildren(curp, p, ops, facs, vp);
else
ret |= ktrops(curp, p, ops, facs, vp);
} else {
/*
* by pid
*/
p = pfind(SCARG(uap, pid));
if (p == NULL) {
error = ESRCH;
goto done;
}
if (descend)
ret |= ktrsetchildren(curp, p, ops, facs, vp);
else
ret |= ktrops(curp, p, ops, facs, vp);
}
if (!ret)
error = EPERM;
done:
if (vp != NULL)
(void) vn_close(vp, FWRITE, curp->p_ucred, curp);
curp->p_traceflag &= ~KTRFAC_ACTIVE;
return (error);
}
int
ktrops(struct proc *curp, struct proc *p, int ops, int facs, struct vnode *vp)
{
if (!ktrcanset(curp, p))
return (0);
if (ops == KTROP_SET) {
ktrsettracevnode(p, vp);
p->p_traceflag |= facs;
if (curp->p_ucred->cr_uid == 0)
p->p_traceflag |= KTRFAC_ROOT;
} else {
/* KTROP_CLEAR */
if (((p->p_traceflag &= ~facs) & KTRFAC_MASK) == 0) {
/* no more tracing */
p->p_traceflag = 0;
ktrsettracevnode(p, NULL);
}
}
/*
* Emit an emulation record, every time there is a ktrace
* change/attach request.
*/
if (KTRPOINT(p, KTR_EMUL))
ktremul(p, p->p_emul->e_name);
return (1);
}
int
ktrsetchildren(struct proc *curp, struct proc *top, int ops, int facs,
struct vnode *vp)
{
struct proc *p;
int ret = 0;
p = top;
for (;;) {
ret |= ktrops(curp, p, ops, facs, vp);
/*
* If this process has children, descend to them next,
* otherwise do any siblings, and if done with this level,
* follow back up the tree (but not past top).
*/
if (!LIST_EMPTY(&p->p_children))
p = LIST_FIRST(&p->p_children);
else for (;;) {
if (p == top)
return (ret);
if (LIST_NEXT(p, p_sibling) != NULL) {
p = LIST_NEXT(p, p_sibling);
break;
}
p = p->p_pptr;
}
}
/*NOTREACHED*/
}
int
ktrwrite(struct proc *p, struct ktr_header *kth)
{
struct uio auio;
struct iovec aiov[2];
int error;
struct vnode *vp = p->p_tracep;
if (vp == NULL)
return 0;
auio.uio_iov = &aiov[0];
auio.uio_offset = 0;
auio.uio_segflg = UIO_SYSSPACE;
auio.uio_rw = UIO_WRITE;
aiov[0].iov_base = (caddr_t)kth;
aiov[0].iov_len = sizeof(struct ktr_header);
auio.uio_resid = sizeof(struct ktr_header);
auio.uio_iovcnt = 1;
auio.uio_procp = p;
if (kth->ktr_len > 0) {
auio.uio_iovcnt++;
aiov[1].iov_base = kth->ktr_buf;
aiov[1].iov_len = kth->ktr_len;
auio.uio_resid += kth->ktr_len;
}
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p);
error = VOP_WRITE(vp, &auio, IO_UNIT|IO_APPEND, p->p_ucred);
VOP_UNLOCK(vp, 0, p);
if (!error)
return 0;
/*
* If error encountered, give up tracing on this vnode.
*/
log(LOG_NOTICE, "ktrace write failed, errno %d, tracing stopped\n",
error);
for (p = LIST_FIRST(&allproc); p != NULL; p = LIST_NEXT(p, p_list)) {
if (p->p_tracep == vp) {
p->p_traceflag = 0;
ktrsettracevnode(p, NULL);
}
}
return error;
}
/*
* Return true if caller has permission to set the ktracing state
* of target. Essentially, the target can't possess any
* more permissions than the caller. KTRFAC_ROOT signifies that
* root previously set the tracing status on the target process, and
* so, only root may further change it.
*
* TODO: check groups. use caller effective gid.
*/
int
ktrcanset(struct proc *callp, struct proc *targetp)
{
struct pcred *caller = callp->p_cred;
struct pcred *target = targetp->p_cred;
if ((caller->pc_ucred->cr_uid == target->p_ruid &&
target->p_ruid == target->p_svuid &&
caller->p_rgid == target->p_rgid && /* XXX */
target->p_rgid == target->p_svgid &&
(targetp->p_traceflag & KTRFAC_ROOT) == 0 &&
!ISSET(targetp->p_flag, P_SUGID)) ||
caller->pc_ucred->cr_uid == 0)
return (1);
return (0);
}
#endif