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Code Issues Releases Activity
21bb5468b7
freebsd/sys/kern/kern_ktrace.c
Robert Watson b1fc0ec1a7 o Merge contents of struct pcred into struct ucred. Specifically, add the 
real uid, saved uid, real gid, and saved gid to ucred, as well as the
  pcred->pc_uidinfo, which was associated with the real uid, only rename
  it to cr_ruidinfo so as not to conflict with cr_uidinfo, which
  corresponds to the effective uid.
o Remove p_cred from struct proc; add p_ucred to struct proc, replacing
  original macro that pointed.
  p->p_ucred to p->p_cred->pc_ucred.
o Universally update code so that it makes use of ucred instead of pcred,
  p->p_ucred instead of p->p_pcred, cr_ruidinfo instead of p_uidinfo,
  cr_{r,sv}{u,g}id instead of p_*, etc.
o Remove pcred0 and its initialization from init_main.c; initialize
  cr_ruidinfo there.
o Restruction many credential modification chunks to always crdup while
  we figure out locking and optimizations; generally speaking, this
  means moving to a structure like this:
        newcred = crdup(oldcred);
        ...
        p->p_ucred = newcred;
        crfree(oldcred);
  It's not race-free, but better than nothing.  There are also races
  in sys_process.c, all inter-process authorization, fork, exec, and
  exit.
o Remove sigio->sio_ruid since sigio->sio_ucred now contains the ruid;
  remove comments indicating that the old arrangement was a problem.
o Restructure exec1() a little to use newcred/oldcred arrangement, and
  use improved uid management primitives.
o Clean up exit1() so as to do less work in credential cleanup due to
  pcred removal.
o Clean up fork1() so as to do less work in credential cleanup and
  allocation.
o Clean up ktrcanset() to take into account changes, and move to using
  suser_xxx() instead of performing a direct uid==0 comparision.
o Improve commenting in various kern_prot.c credential modification
  calls to better document current behavior.  In a couple of places,
  current behavior is a little questionable and we need to check
  POSIX.1 to make sure it's "right".  More commenting work still
  remains to be done.
o Update credential management calls, such as crfree(), to take into
  account new ruidinfo reference.
o Modify or add the following uid and gid helper routines:
      change_euid()
      change_egid()
      change_ruid()
      change_rgid()
      change_svuid()
      change_svgid()
  In each case, the call now acts on a credential not a process, and as
  such no longer requires more complicated process locking/etc.  They
  now assume the caller will do any necessary allocation of an
  exclusive credential reference.  Each is commented to document its
  reference requirements.
o CANSIGIO() is simplified to require only credentials, not processes
  and pcreds.
o Remove lots of (p_pcred==NULL) checks.
o Add an XXX to authorization code in nfs_lock.c, since it's
  questionable, and needs to be considered carefully.
o Simplify posix4 authorization code to require only credentials, not
  processes and pcreds.  Note that this authorization, as well as
  CANSIGIO(), needs to be updated to use the p_cansignal() and
  p_cansched() centralized authorization routines, as they currently
  do not take into account some desirable restrictions that are handled
  by the centralized routines, as well as being inconsistent with other
  similar authorization instances.
o Update libkvm to take these changes into account.

Obtained from:	TrustedBSD Project
Reviewed by:	green, bde, jhb, freebsd-arch, freebsd-audit
2001-05-25 16:59:11 +00:00

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/*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)kern_ktrace.c 8.2 (Berkeley) 9/23/93
* $FreeBSD$
*/
#include "opt_ktrace.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/sysproto.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/fcntl.h>
#include <sys/namei.h>
#include <sys/vnode.h>
#include <sys/ktrace.h>
#include <sys/malloc.h>
#include <sys/sx.h>
#include <sys/syslog.h>
#include <sys/jail.h>
static MALLOC_DEFINE(M_KTRACE, "KTRACE", "KTRACE");
#ifdef KTRACE
static struct ktr_header *ktrgetheader __P((int type));
static void ktrwrite __P((struct vnode *, struct ktr_header *, struct uio *));
static int ktrcanset __P((struct proc *,struct proc *));
static int ktrsetchildren __P((struct proc *,struct proc *,int,int,struct vnode *));
static int ktrops __P((struct proc *,struct proc *,int,int,struct vnode *));
static struct ktr_header *
ktrgetheader(type)
int type;
{
register struct ktr_header *kth;
struct proc *p = curproc; /* XXX */
MALLOC(kth, struct ktr_header *, sizeof (struct ktr_header),
M_KTRACE, M_WAITOK);
kth->ktr_type = type;
microtime(&kth->ktr_time);
kth->ktr_pid = p->p_pid;
bcopy(p->p_comm, kth->ktr_comm, MAXCOMLEN + 1);
return (kth);
}
void
ktrsyscall(vp, code, narg, args)
struct vnode *vp;
int code, narg;
register_t args[];
{
struct ktr_header *kth;
struct ktr_syscall *ktp;
register int len = offsetof(struct ktr_syscall, ktr_args) +
(narg * sizeof(register_t));
struct proc *p = curproc; /* XXX */
register_t *argp;
int i;
p->p_traceflag |= KTRFAC_ACTIVE;
kth = ktrgetheader(KTR_SYSCALL);
MALLOC(ktp, struct ktr_syscall *, len, M_KTRACE, M_WAITOK);
ktp->ktr_code = code;
ktp->ktr_narg = narg;
argp = &ktp->ktr_args[0];
for (i = 0; i < narg; i++)
*argp++ = args[i];
kth->ktr_buffer = (caddr_t)ktp;
kth->ktr_len = len;
ktrwrite(vp, kth, NULL);
FREE(ktp, M_KTRACE);
FREE(kth, M_KTRACE);
p->p_traceflag &= ~KTRFAC_ACTIVE;
}
void
ktrsysret(vp, code, error, retval)
struct vnode *vp;
int code, error;
register_t retval;
{
struct ktr_header *kth;
struct ktr_sysret ktp;
struct proc *p = curproc; /* XXX */
p->p_traceflag |= KTRFAC_ACTIVE;
kth = ktrgetheader(KTR_SYSRET);
ktp.ktr_code = code;
ktp.ktr_error = error;
ktp.ktr_retval = retval; /* what about val2 ? */
kth->ktr_buffer = (caddr_t)&ktp;
kth->ktr_len = sizeof(struct ktr_sysret);
ktrwrite(vp, kth, NULL);
FREE(kth, M_KTRACE);
p->p_traceflag &= ~KTRFAC_ACTIVE;
}
void
ktrnamei(vp, path)
struct vnode *vp;
char *path;
{
struct ktr_header *kth;
struct proc *p = curproc; /* XXX */
p->p_traceflag |= KTRFAC_ACTIVE;
kth = ktrgetheader(KTR_NAMEI);
kth->ktr_len = strlen(path);
kth->ktr_buffer = path;
ktrwrite(vp, kth, NULL);
FREE(kth, M_KTRACE);
p->p_traceflag &= ~KTRFAC_ACTIVE;
}
void
ktrgenio(vp, fd, rw, uio, error)
struct vnode *vp;
int fd;
enum uio_rw rw;
struct uio *uio;
int error;
{
struct ktr_header *kth;
struct ktr_genio ktg;
struct proc *p = curproc; /* XXX */
if (error)
return;
p->p_traceflag |= KTRFAC_ACTIVE;
kth = ktrgetheader(KTR_GENIO);
ktg.ktr_fd = fd;
ktg.ktr_rw = rw;
kth->ktr_buffer = (caddr_t)&ktg;
kth->ktr_len = sizeof(struct ktr_genio);
uio->uio_offset = 0;
uio->uio_rw = UIO_WRITE;
ktrwrite(vp, kth, uio);
FREE(kth, M_KTRACE);
p->p_traceflag &= ~KTRFAC_ACTIVE;
}
void
ktrpsig(vp, sig, action, mask, code)
struct vnode *vp;
int sig;
sig_t action;
sigset_t *mask;
int code;
{
struct ktr_header *kth;
struct ktr_psig kp;
struct proc *p = curproc; /* XXX */
p->p_traceflag |= KTRFAC_ACTIVE;
kth = ktrgetheader(KTR_PSIG);
kp.signo = (char)sig;
kp.action = action;
kp.mask = *mask;
kp.code = code;
kth->ktr_buffer = (caddr_t)&kp;
kth->ktr_len = sizeof (struct ktr_psig);
ktrwrite(vp, kth, NULL);
FREE(kth, M_KTRACE);
p->p_traceflag &= ~KTRFAC_ACTIVE;
}
void
ktrcsw(vp, out, user)
struct vnode *vp;
int out, user;
{
struct ktr_header *kth;
struct ktr_csw kc;
struct proc *p = curproc; /* XXX */
p->p_traceflag |= KTRFAC_ACTIVE;
kth = ktrgetheader(KTR_CSW);
kc.out = out;
kc.user = user;
kth->ktr_buffer = (caddr_t)&kc;
kth->ktr_len = sizeof (struct ktr_csw);
ktrwrite(vp, kth, NULL);
FREE(kth, M_KTRACE);
p->p_traceflag &= ~KTRFAC_ACTIVE;
}
#endif
/* Interface and common routines */
/*
* ktrace system call
*/
#ifndef _SYS_SYSPROTO_H_
struct ktrace_args {
char *fname;
int ops;
int facs;
int pid;
};
#endif
/* ARGSUSED */
int
ktrace(curp, uap)
struct proc *curp;
register struct ktrace_args *uap;
{
#ifdef KTRACE
register struct vnode *vp = NULL;
register struct proc *p;
struct pgrp *pg;
int facs = uap->facs & ~KTRFAC_ROOT;
int ops = KTROP(uap->ops);
int descend = uap->ops & KTRFLAG_DESCEND;
int ret = 0;
int flags, error = 0;
struct nameidata nd;
curp->p_traceflag |= KTRFAC_ACTIVE;
if (ops != KTROP_CLEAR) {
/*
* an operation which requires a file argument.
*/
NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_USERSPACE, uap->fname, curp);
flags = FREAD | FWRITE | O_NOFOLLOW;
error = vn_open(&nd, &flags, 0);
if (error) {
curp->p_traceflag &= ~KTRFAC_ACTIVE;
return (error);
}
NDFREE(&nd, NDF_ONLY_PNBUF);
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) {
sx_slock(&allproc_lock);
LIST_FOREACH(p, &allproc, p_list) {
if (p->p_tracep == vp) {
if (ktrcanset(curp, p)) {
p->p_tracep = NULL;
p->p_traceflag = 0;
(void) vn_close(vp, FREAD|FWRITE,
p->p_ucred, p);
} else
error = EPERM;
}
}
sx_sunlock(&allproc_lock);
goto done;
}
/*
* need something to (un)trace (XXX - why is this here?)
*/
if (!facs) {
error = EINVAL;
goto done;
}
/*
* do it
*/
if (uap->pid < 0) {
/*
* by process group
*/
pg = pgfind(-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(uap->pid);
if (p == NULL) {
error = ESRCH;
goto done;
}
PROC_UNLOCK(p);
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);
#else
return ENOSYS;
#endif
}
/*
* utrace system call
*/
/* ARGSUSED */
int
utrace(curp, uap)
struct proc *curp;
register struct utrace_args *uap;
{
#ifdef KTRACE
struct ktr_header *kth;
struct proc *p = curproc; /* XXX */
register caddr_t cp;
if (!KTRPOINT(p, KTR_USER))
return (0);
if (uap->len > KTR_USER_MAXLEN)
return (EINVAL);
p->p_traceflag |= KTRFAC_ACTIVE;
kth = ktrgetheader(KTR_USER);
MALLOC(cp, caddr_t, uap->len, M_KTRACE, M_WAITOK);
if (!copyin(uap->addr, cp, uap->len)) {
kth->ktr_buffer = cp;
kth->ktr_len = uap->len;
ktrwrite(p->p_tracep, kth, NULL);
}
FREE(kth, M_KTRACE);
FREE(cp, M_KTRACE);
p->p_traceflag &= ~KTRFAC_ACTIVE;
return (0);
#else
return (ENOSYS);
#endif
}
#ifdef KTRACE
static int
ktrops(curp, p, ops, facs, vp)
struct proc *p, *curp;
int ops, facs;
struct vnode *vp;
{
if (!ktrcanset(curp, p))
return (0);
if (ops == KTROP_SET) {
if (p->p_tracep != vp) {
/*
* if trace file already in use, relinquish
*/
if (p->p_tracep != NULL)
vrele(p->p_tracep);
VREF(vp);
p->p_tracep = 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;
if (p->p_tracep != NULL) {
vrele(p->p_tracep);
p->p_tracep = NULL;
}
}
}
return (1);
}
static int
ktrsetchildren(curp, top, ops, facs, vp)
struct proc *curp, *top;
int ops, facs;
struct vnode *vp;
{
register struct proc *p;
register int ret = 0;
p = top;
sx_slock(&proctree_lock);
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) {
sx_sunlock(&proctree_lock);
return (ret);
}
if (LIST_NEXT(p, p_sibling)) {
p = LIST_NEXT(p, p_sibling);
break;
}
p = p->p_pptr;
}
}
/*NOTREACHED*/
}
static void
ktrwrite(vp, kth, uio)
struct vnode *vp;
register struct ktr_header *kth;
struct uio *uio;
{
struct uio auio;
struct iovec aiov[2];
struct proc *p = curproc; /* XXX */
struct mount *mp;
int error;
if (vp == NULL)
return;
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 = curproc;
if (kth->ktr_len > 0) {
auio.uio_iovcnt++;
aiov[1].iov_base = kth->ktr_buffer;
aiov[1].iov_len = kth->ktr_len;
auio.uio_resid += kth->ktr_len;
if (uio != NULL)
kth->ktr_len += uio->uio_resid;
}
vn_start_write(vp, &mp, V_WAIT);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p);
(void)VOP_LEASE(vp, p, p->p_ucred, LEASE_WRITE);
error = VOP_WRITE(vp, &auio, IO_UNIT | IO_APPEND, p->p_ucred);
if (error == 0 && uio != NULL) {
(void)VOP_LEASE(vp, p, p->p_ucred, LEASE_WRITE);
error = VOP_WRITE(vp, uio, IO_UNIT | IO_APPEND, p->p_ucred);
}
VOP_UNLOCK(vp, 0, p);
vn_finished_write(mp);
if (!error)
return;
/*
* If error encountered, give up tracing on this vnode.
*/
log(LOG_NOTICE, "ktrace write failed, errno %d, tracing stopped\n",
error);
sx_slock(&allproc_lock);
LIST_FOREACH(p, &allproc, p_list) {
if (p->p_tracep == vp) {
p->p_tracep = NULL;
p->p_traceflag = 0;
vrele(vp);
}
}
sx_sunlock(&allproc_lock);
}
/*
* 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.
*
* XXX: These checks are stronger than for ptrace()
* XXX: This check should be p_can(... P_CAN_DEBUG ...);
*
* TODO: check groups. use caller effective gid.
*/
static int
ktrcanset(callp, targetp)
struct proc *callp, *targetp;
{
struct ucred *callcr = callp->p_ucred;
struct ucred *targetcr = targetp->p_ucred;
if (prison_check(callcr, targetcr))
return (0);
if ((callcr->cr_uid == targetcr->cr_ruid &&
targetcr->cr_ruid == targetcr->cr_svuid &&
callcr->cr_rgid == targetcr->cr_rgid && /* XXX */
targetcr->cr_rgid == targetcr->cr_svgid &&
(targetp->p_traceflag & KTRFAC_ROOT) == 0) ||
!suser_xxx(callcr, NULL, PRISON_ROOT))
return (1);
return (0);
}
#endif /* KTRACE */
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