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kern_ktrace.c revision 1.5.4.2 
      1 /*
      2  * Copyright (c) 1989 The Regents of the University of California.
      3  * All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  * 3. All advertising materials mentioning features or use of this software
     14  *    must display the following acknowledgement:
     15  *	This product includes software developed by the University of
     16  *	California, Berkeley and its contributors.
     17  * 4. Neither the name of the University nor the names of its contributors
     18  *    may be used to endorse or promote products derived from this software
     19  *    without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  * SUCH DAMAGE.
     32  *
     33  *	from: @(#)kern_ktrace.c	7.15 (Berkeley) 6/21/91
     34  *	$Id: kern_ktrace.c,v 1.5.4.2 1993/11/14 20:31:54 mycroft Exp $
     35  */
     36 
     37 #include <sys/param.h>
     38 #include <sys/systm.h>
     39 #include <sys/proc.h>
     40 #include <sys/file.h>
     41 #include <sys/namei.h>
     42 #include <sys/vnode.h>
     43 #include <sys/ktrace.h>
     44 #include <sys/malloc.h>
     45 #include <sys/syslog.h>
     46 
     47 void ktrwrite __P((struct vnode *vp, struct ktr_header *kth));
     48 
     49 struct ktr_header *
     50 ktrgetheader(type)
     51 	int type;
     52 {
     53 	register struct ktr_header *kth;
     54 	struct proc *p = curproc;	/* XXX */
     55 
     56 	MALLOC(kth, struct ktr_header *, sizeof (struct ktr_header),
     57 		M_TEMP, M_WAITOK);
     58 	kth->ktr_type = type;
     59 	microtime(&kth->ktr_time);
     60 	kth->ktr_pid = p->p_pid;
     61 	bcopy(p->p_comm, kth->ktr_comm, MAXCOMLEN);
     62 	return (kth);
     63 }
     64 
     65 void
     66 ktrsyscall(vp, code, narg, args)
     67 	struct vnode *vp;
     68 	int code, narg, args[];
     69 {
     70 	struct	ktr_header *kth = ktrgetheader(KTR_SYSCALL);
     71 	struct	ktr_syscall *ktp;
     72 	register len = sizeof(struct ktr_syscall) + (narg * sizeof(int));
     73 	int 	*argp, i;
     74 
     75 	MALLOC(ktp, struct ktr_syscall *, len, M_TEMP, M_WAITOK);
     76 	ktp->ktr_code = code;
     77 	ktp->ktr_narg = narg;
     78 	argp = (int *)((char *)ktp + sizeof(struct ktr_syscall));
     79 	for (i = 0; i < narg; i++)
     80 		*argp++ = args[i];
     81 	kth->ktr_buf = (caddr_t)ktp;
     82 	kth->ktr_len = len;
     83 	ktrwrite(vp, kth);
     84 	FREE(ktp, M_TEMP);
     85 	FREE(kth, M_TEMP);
     86 }
     87 
     88 void
     89 ktrsysret(vp, code, error, retval)
     90 	struct vnode *vp;
     91 	int code, error, retval;
     92 {
     93 	struct ktr_header *kth = ktrgetheader(KTR_SYSRET);
     94 	struct ktr_sysret ktp;
     95 
     96 	ktp.ktr_code = code;
     97 	ktp.ktr_error = error;
     98 	ktp.ktr_retval = retval;		/* what about val2 ? */
     99 
    100 	kth->ktr_buf = (caddr_t)&ktp;
    101 	kth->ktr_len = sizeof(struct ktr_sysret);
    102 
    103 	ktrwrite(vp, kth);
    104 	FREE(kth, M_TEMP);
    105 }
    106 
    107 void
    108 ktrnamei(vp, path)
    109 	struct vnode *vp;
    110 	char *path;
    111 {
    112 	struct ktr_header *kth = ktrgetheader(KTR_NAMEI);
    113 
    114 	kth->ktr_len = strlen(path);
    115 	kth->ktr_buf = path;
    116 
    117 	ktrwrite(vp, kth);
    118 	FREE(kth, M_TEMP);
    119 }
    120 
    121 void
    122 ktrgenio(vp, fd, rw, iov, len, error)
    123 	struct vnode *vp;
    124 	int fd;
    125 	enum uio_rw rw;
    126 	register struct iovec *iov;
    127 	int len, error;
    128 {
    129 	struct ktr_header *kth = ktrgetheader(KTR_GENIO);
    130 	register struct ktr_genio *ktp;
    131 	register caddr_t cp;
    132 	register int resid = len, cnt;
    133 
    134 	if (error)
    135 		return;
    136 	MALLOC(ktp, struct ktr_genio *, sizeof(struct ktr_genio) + len,
    137 		M_TEMP, M_WAITOK);
    138 	ktp->ktr_fd = fd;
    139 	ktp->ktr_rw = rw;
    140 	cp = (caddr_t)((char *)ktp + sizeof (struct ktr_genio));
    141 	while (resid > 0) {
    142 		if ((cnt = iov->iov_len) > resid)
    143 			cnt = resid;
    144 		if (copyin(iov->iov_base, cp, (unsigned)cnt))
    145 			goto done;
    146 		cp += cnt;
    147 		resid -= cnt;
    148 		iov++;
    149 	}
    150 	kth->ktr_buf = (caddr_t)ktp;
    151 	kth->ktr_len = sizeof (struct ktr_genio) + len;
    152 
    153 	ktrwrite(vp, kth);
    154 done:
    155 	FREE(kth, M_TEMP);
    156 	FREE(ktp, M_TEMP);
    157 }
    158 
    159 void
    160 ktrpsig(vp, sig, action, mask, code)
    161 	struct	vnode *vp;
    162 	sig_t	action;
    163 	int sig, mask, code;
    164 {
    165 	struct ktr_header *kth = ktrgetheader(KTR_PSIG);
    166 	struct ktr_psig	kp;
    167 
    168 	kp.signo = (char)sig;
    169 	kp.action = action;
    170 	kp.mask = mask;
    171 	kp.code = code;
    172 	kth->ktr_buf = (caddr_t)&kp;
    173 	kth->ktr_len = sizeof (struct ktr_psig);
    174 
    175 	ktrwrite(vp, kth);
    176 	FREE(kth, M_TEMP);
    177 }
    178 
    179 /* Interface and common routines */
    180 
    181 /*
    182  * ktrace system call
    183  */
    184 
    185 struct ktrace_args {
    186 	char	*fname;
    187 	int	ops;
    188 	int	facs;
    189 	int	pid;
    190 };
    191 
    192 /* ARGSUSED */
    193 int
    194 ktrace(curp, uap, retval)
    195 	struct proc *curp;
    196 	register struct ktrace_args *uap;
    197 	int *retval;
    198 {
    199 	register struct vnode *vp = NULL;
    200 	register struct proc *p;
    201 	struct pgrp *pg;
    202 	int facs = uap->facs & ~KTRFAC_ROOT;
    203 	int ops = KTROP(uap->ops);
    204 	int descend = uap->ops & KTRFLAG_DESCEND;
    205 	int ret = 0;
    206 	int error = 0;
    207 	struct nameidata nd;
    208 
    209 	if (ops != KTROP_CLEAR) {
    210 		/*
    211 		 * an operation which requires a file argument.
    212 		 */
    213 		nd.ni_segflg = UIO_USERSPACE;
    214 		nd.ni_dirp = uap->fname;
    215 		if (error = vn_open(&nd, curp, FREAD|FWRITE, 0))
    216 			return (error);
    217 		vp = nd.ni_vp;
    218 		VOP_UNLOCK(vp);
    219 		if (vp->v_type != VREG) {
    220 			(void) vn_close(vp, FREAD|FWRITE, curp->p_ucred, curp);
    221 			return (EACCES);
    222 		}
    223 	}
    224 	/*
    225 	 * Clear all uses of the tracefile
    226 	 */
    227 	if (ops == KTROP_CLEARFILE) {
    228 		for (p = (struct proc *)allproc; p != NULL; p = p->p_nxt) {
    229 			if (p->p_tracep == vp) {
    230 				if (ktrcanset(curp, p)) {
    231 					p->p_tracep = NULL;
    232 					p->p_traceflag = 0;
    233 					(void) vn_close(vp, FREAD|FWRITE,
    234 						p->p_ucred, p);
    235 				} else
    236 					error = EPERM;
    237 			}
    238 		}
    239 		goto done;
    240 	}
    241 	/*
    242 	 * need something to (un)trace (XXX - why is this here?)
    243 	 */
    244 	if (!facs) {
    245 		error = EINVAL;
    246 		goto done;
    247 	}
    248 	/*
    249 	 * do it
    250 	 */
    251 	if (uap->pid < 0) {
    252 		/*
    253 		 * by process group
    254 		 */
    255 		pg = pgfind(-uap->pid);
    256 		if (pg == NULL) {
    257 			error = ESRCH;
    258 			goto done;
    259 		}
    260 		for (p = pg->pg_mem; p != NULL; p = p->p_pgrpnxt)
    261 			if (descend)
    262 				ret |= ktrsetchildren(curp, p, ops, facs, vp);
    263 			else
    264 				ret |= ktrops(curp, p, ops, facs, vp);
    265 
    266 	} else {
    267 		/*
    268 		 * by pid
    269 		 */
    270 		p = pfind(uap->pid);
    271 		if (p == NULL) {
    272 			error = ESRCH;
    273 			goto done;
    274 		}
    275 		if (descend)
    276 			ret |= ktrsetchildren(curp, p, ops, facs, vp);
    277 		else
    278 			ret |= ktrops(curp, p, ops, facs, vp);
    279 	}
    280 	if (!ret)
    281 		error = EPERM;
    282 done:
    283 	if (vp != NULL)
    284 		(void) vn_close(vp, FWRITE, curp->p_ucred, curp);
    285 	return (error);
    286 }
    287 
    288 int
    289 ktrops(curp, p, ops, facs, vp)
    290 	struct proc *curp, *p;
    291 	int ops, facs;
    292 	struct vnode *vp;
    293 {
    294 
    295 	if (!ktrcanset(curp, p))
    296 		return (0);
    297 	if (ops == KTROP_SET) {
    298 		if (p->p_tracep != vp) {
    299 			/*
    300 			 * if trace file already in use, relinquish
    301 			 */
    302 			if (p->p_tracep != NULL)
    303 				vrele(p->p_tracep);
    304 			VREF(vp);
    305 			p->p_tracep = vp;
    306 		}
    307 		p->p_traceflag |= facs;
    308 		if (curp->p_ucred->cr_uid == 0)
    309 			p->p_traceflag |= KTRFAC_ROOT;
    310 	} else {
    311 		/* KTROP_CLEAR */
    312 		if (((p->p_traceflag &= ~facs) & KTRFAC_MASK) == 0) {
    313 			/* no more tracing */
    314 			p->p_traceflag = 0;
    315 			if (p->p_tracep != NULL) {
    316 				vrele(p->p_tracep);
    317 				p->p_tracep = NULL;
    318 			}
    319 		}
    320 	}
    321 
    322 	return (1);
    323 }
    324 
    325 int
    326 ktrsetchildren(curp, top, ops, facs, vp)
    327 	struct proc *curp, *top;
    328 	int ops, facs;
    329 	struct vnode *vp;
    330 {
    331 	register struct proc *p;
    332 	register int ret = 0;
    333 
    334 	p = top;
    335 	for (;;) {
    336 		ret |= ktrops(curp, p, ops, facs, vp);
    337 		/*
    338 		 * If this process has children, descend to them next,
    339 		 * otherwise do any siblings, and if done with this level,
    340 		 * follow back up the tree (but not past top).
    341 		 */
    342 		if (p->p_cptr)
    343 			p = p->p_cptr;
    344 		else if (p == top)
    345 			return (ret);
    346 		else if (p->p_osptr)
    347 			p = p->p_osptr;
    348 		else for (;;) {
    349 			p = p->p_pptr;
    350 			if (p == top)
    351 				return (ret);
    352 			if (p->p_osptr) {
    353 				p = p->p_osptr;
    354 				break;
    355 			}
    356 		}
    357 	}
    358 	/*NOTREACHED*/
    359 }
    360 
    361 void
    362 ktrwrite(vp, kth)
    363 	struct vnode *vp;
    364 	register struct ktr_header *kth;
    365 {
    366 	struct uio auio;
    367 	struct iovec aiov[2];
    368 	register struct proc *p = curproc;	/* XXX */
    369 	int error;
    370 
    371 	if (vp == NULL)
    372 		return;
    373 	auio.uio_iov = &aiov[0];
    374 	auio.uio_offset = 0;
    375 	auio.uio_segflg = UIO_SYSSPACE;
    376 	auio.uio_rw = UIO_WRITE;
    377 	aiov[0].iov_base = (caddr_t)kth;
    378 	aiov[0].iov_len = sizeof(struct ktr_header);
    379 	auio.uio_resid = sizeof(struct ktr_header);
    380 	auio.uio_iovcnt = 1;
    381 	auio.uio_procp = (struct proc *)0;
    382 	if (kth->ktr_len > 0) {
    383 		auio.uio_iovcnt++;
    384 		aiov[1].iov_base = kth->ktr_buf;
    385 		aiov[1].iov_len = kth->ktr_len;
    386 		auio.uio_resid += kth->ktr_len;
    387 	}
    388 	VOP_LOCK(vp);
    389 	error = VOP_WRITE(vp, &auio, IO_UNIT|IO_APPEND, p->p_ucred);
    390 	VOP_UNLOCK(vp);
    391 	if (!error)
    392 		return;
    393 	/*
    394 	 * If error encountered, give up tracing on this vnode.
    395 	 */
    396 	log(LOG_NOTICE, "ktrace write failed, errno %d, tracing stopped\n",
    397 	    error);
    398 	for (p = (struct proc *)allproc; p != NULL; p = p->p_nxt) {
    399 		if (p->p_tracep == vp) {
    400 			p->p_tracep = NULL;
    401 			p->p_traceflag = 0;
    402 			vrele(vp);
    403 		}
    404 	}
    405 }
    406 
    407 /*
    408  * Return true if caller has permission to set the ktracing state
    409  * of target.  Essentially, the target can't possess any
    410  * more permissions than the caller.  KTRFAC_ROOT signifies that
    411  * root previously set the tracing status on the target process, and
    412  * so, only root may further change it.
    413  *
    414  * TODO: check groups.  use caller effective gid.
    415  */
    416 int
    417 ktrcanset(callp, targetp)
    418 	struct proc *callp, *targetp;
    419 {
    420 	register struct pcred *caller = callp->p_cred;
    421 	register struct pcred *target = targetp->p_cred;
    422 
    423 	if ((caller->pc_ucred->cr_uid == target->p_ruid &&
    424 	     target->p_ruid == target->p_svuid &&
    425 	     caller->p_rgid == target->p_rgid &&	/* XXX */
    426 	     target->p_rgid == target->p_svgid &&
    427 	     (targetp->p_traceflag & KTRFAC_ROOT) == 0) ||
    428 	     caller->pc_ucred->cr_uid == 0)
    429 		return (1);
    430 
    431 	return (0);
    432 }
    433