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kern_ktrace.c revision 1.22 
      1 /*	$NetBSD: kern_ktrace.c,v 1.22 1996/02/04 02:15:39 christos Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1989, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  *
     35  *	@(#)kern_ktrace.c	8.2 (Berkeley) 9/23/93
     36  */
     37 
     38 #ifdef KTRACE
     39 
     40 #include <sys/param.h>
     41 #include <sys/systm.h>
     42 #include <sys/proc.h>
     43 #include <sys/file.h>
     44 #include <sys/namei.h>
     45 #include <sys/vnode.h>
     46 #include <sys/ktrace.h>
     47 #include <sys/malloc.h>
     48 #include <sys/syslog.h>
     49 
     50 #include <sys/mount.h>
     51 #include <sys/syscallargs.h>
     52 
     53 #include <kern/kern_extern.h>
     54 
     55 struct ktr_header *ktrgetheader __P((int));
     56 int ktrops __P((struct proc *, struct proc *, int, int, struct vnode *));
     57 int ktrsetchildren __P((struct proc *, struct proc *, int, int,
     58 			struct vnode *));
     59 void ktrwrite __P((struct vnode *, struct ktr_header *));
     60 int ktrcanset __P((struct proc *, struct proc *));
     61 
     62 struct ktr_header *
     63 ktrgetheader(type)
     64 	int type;
     65 {
     66 	register struct ktr_header *kth;
     67 	struct proc *p = curproc;	/* XXX */
     68 
     69 	MALLOC(kth, struct ktr_header *, sizeof (struct ktr_header),
     70 		M_TEMP, M_WAITOK);
     71 	kth->ktr_type = type;
     72 	microtime(&kth->ktr_time);
     73 	kth->ktr_pid = p->p_pid;
     74 	bcopy(p->p_comm, kth->ktr_comm, MAXCOMLEN);
     75 	return (kth);
     76 }
     77 
     78 void
     79 ktrsyscall(vp, code, argsize, args)
     80 	struct vnode *vp;
     81 	register_t code;
     82 	size_t argsize;
     83 	register_t args[];
     84 {
     85 	struct	ktr_header *kth;
     86 	struct	ktr_syscall *ktp;
     87 	register len = sizeof(struct ktr_syscall) + argsize;
     88 	struct proc *p = curproc;	/* XXX */
     89 	register_t *argp;
     90 	int i;
     91 
     92 	p->p_traceflag |= KTRFAC_ACTIVE;
     93 	kth = ktrgetheader(KTR_SYSCALL);
     94 	MALLOC(ktp, struct ktr_syscall *, len, M_TEMP, M_WAITOK);
     95 	ktp->ktr_code = code;
     96 	ktp->ktr_argsize = argsize;
     97 	argp = (register_t *)((char *)ktp + sizeof(struct ktr_syscall));
     98 	for (i = 0; i < (argsize / sizeof *argp); i++)
     99 		*argp++ = args[i];
    100 	kth->ktr_buf = (caddr_t)ktp;
    101 	kth->ktr_len = len;
    102 	ktrwrite(vp, kth);
    103 	FREE(ktp, M_TEMP);
    104 	FREE(kth, M_TEMP);
    105 	p->p_traceflag &= ~KTRFAC_ACTIVE;
    106 }
    107 
    108 void
    109 ktrsysret(vp, code, error, retval)
    110 	struct vnode *vp;
    111 	register_t code;
    112 	int error;
    113 	register_t retval;
    114 {
    115 	struct ktr_header *kth;
    116 	struct ktr_sysret ktp;
    117 	struct proc *p = curproc;	/* XXX */
    118 
    119 	p->p_traceflag |= KTRFAC_ACTIVE;
    120 	kth = ktrgetheader(KTR_SYSRET);
    121 	ktp.ktr_code = code;
    122 	ktp.ktr_error = error;
    123 	ktp.ktr_retval = retval;		/* what about val2 ? */
    124 
    125 	kth->ktr_buf = (caddr_t)&ktp;
    126 	kth->ktr_len = sizeof(struct ktr_sysret);
    127 
    128 	ktrwrite(vp, kth);
    129 	FREE(kth, M_TEMP);
    130 	p->p_traceflag &= ~KTRFAC_ACTIVE;
    131 }
    132 
    133 void
    134 ktrnamei(vp, path)
    135 	struct vnode *vp;
    136 	char *path;
    137 {
    138 	struct ktr_header *kth;
    139 	struct proc *p = curproc;	/* XXX */
    140 
    141 	p->p_traceflag |= KTRFAC_ACTIVE;
    142 	kth = ktrgetheader(KTR_NAMEI);
    143 	kth->ktr_len = strlen(path);
    144 	kth->ktr_buf = path;
    145 
    146 	ktrwrite(vp, kth);
    147 	FREE(kth, M_TEMP);
    148 	p->p_traceflag &= ~KTRFAC_ACTIVE;
    149 }
    150 
    151 void
    152 ktremul(vp, emul)
    153 	struct vnode *vp;
    154 	char *emul;
    155 {
    156 	struct ktr_header *kth;
    157 	struct proc *p = curproc;       /* XXX */
    158 
    159 	p->p_traceflag |= KTRFAC_ACTIVE;
    160 	kth = ktrgetheader(KTR_EMUL);
    161 	kth->ktr_len = strlen(emul);
    162 	kth->ktr_buf = emul;
    163 
    164 	ktrwrite(vp, kth);
    165 	FREE(kth, M_TEMP);
    166 	p->p_traceflag &= ~KTRFAC_ACTIVE;
    167 }
    168 
    169 void
    170 ktrgenio(vp, fd, rw, iov, len, error)
    171 	struct vnode *vp;
    172 	int fd;
    173 	enum uio_rw rw;
    174 	register struct iovec *iov;
    175 	int len, error;
    176 {
    177 	struct ktr_header *kth;
    178 	register struct ktr_genio *ktp;
    179 	register caddr_t cp;
    180 	register int resid = len, cnt;
    181 	struct proc *p = curproc;	/* XXX */
    182 
    183 	if (error)
    184 		return;
    185 	p->p_traceflag |= KTRFAC_ACTIVE;
    186 	kth = ktrgetheader(KTR_GENIO);
    187 	MALLOC(ktp, struct ktr_genio *, sizeof(struct ktr_genio) + len,
    188 		M_TEMP, M_WAITOK);
    189 	ktp->ktr_fd = fd;
    190 	ktp->ktr_rw = rw;
    191 	cp = (caddr_t)((char *)ktp + sizeof (struct ktr_genio));
    192 	while (resid > 0) {
    193 		if ((cnt = iov->iov_len) > resid)
    194 			cnt = resid;
    195 		if (copyin(iov->iov_base, cp, (unsigned)cnt))
    196 			goto done;
    197 		cp += cnt;
    198 		resid -= cnt;
    199 		iov++;
    200 	}
    201 	kth->ktr_buf = (caddr_t)ktp;
    202 	kth->ktr_len = sizeof (struct ktr_genio) + len;
    203 
    204 	ktrwrite(vp, kth);
    205 done:
    206 	FREE(kth, M_TEMP);
    207 	FREE(ktp, M_TEMP);
    208 	p->p_traceflag &= ~KTRFAC_ACTIVE;
    209 }
    210 
    211 void
    212 ktrpsig(vp, sig, action, mask, code)
    213 	struct vnode *vp;
    214 	int sig;
    215 	sig_t action;
    216 	int mask, code;
    217 {
    218 	struct ktr_header *kth;
    219 	struct ktr_psig	kp;
    220 	struct proc *p = curproc;	/* XXX */
    221 
    222 	p->p_traceflag |= KTRFAC_ACTIVE;
    223 	kth = ktrgetheader(KTR_PSIG);
    224 	kp.signo = (char)sig;
    225 	kp.action = action;
    226 	kp.mask = mask;
    227 	kp.code = code;
    228 	kth->ktr_buf = (caddr_t)&kp;
    229 	kth->ktr_len = sizeof (struct ktr_psig);
    230 
    231 	ktrwrite(vp, kth);
    232 	FREE(kth, M_TEMP);
    233 	p->p_traceflag &= ~KTRFAC_ACTIVE;
    234 }
    235 
    236 void
    237 ktrcsw(vp, out, user)
    238 	struct vnode *vp;
    239 	int out, user;
    240 {
    241 	struct ktr_header *kth;
    242 	struct	ktr_csw kc;
    243 	struct proc *p = curproc;	/* XXX */
    244 
    245 	p->p_traceflag |= KTRFAC_ACTIVE;
    246 	kth = ktrgetheader(KTR_CSW);
    247 	kc.out = out;
    248 	kc.user = user;
    249 	kth->ktr_buf = (caddr_t)&kc;
    250 	kth->ktr_len = sizeof (struct ktr_csw);
    251 
    252 	ktrwrite(vp, kth);
    253 	FREE(kth, M_TEMP);
    254 	p->p_traceflag &= ~KTRFAC_ACTIVE;
    255 }
    256 
    257 /* Interface and common routines */
    258 
    259 /*
    260  * ktrace system call
    261  */
    262 /* ARGSUSED */
    263 int
    264 sys_ktrace(curp, v, retval)
    265 	struct proc *curp;
    266 	void *v;
    267 	register_t *retval;
    268 {
    269 	register struct sys_ktrace_args /* {
    270 		syscallarg(char *) fname;
    271 		syscallarg(int) ops;
    272 		syscallarg(int) facs;
    273 		syscallarg(int) pid;
    274 	} */ *uap = v;
    275 	register struct vnode *vp = NULL;
    276 	register struct proc *p;
    277 	struct pgrp *pg;
    278 	int facs = SCARG(uap, facs) & ~((unsigned) KTRFAC_ROOT);
    279 	int ops = KTROP(SCARG(uap, ops));
    280 	int descend = SCARG(uap, ops) & KTRFLAG_DESCEND;
    281 	int ret = 0;
    282 	int error = 0;
    283 	struct nameidata nd;
    284 
    285 	curp->p_traceflag |= KTRFAC_ACTIVE;
    286 	if (ops != KTROP_CLEAR) {
    287 		/*
    288 		 * an operation which requires a file argument.
    289 		 */
    290 		NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, SCARG(uap, fname),
    291 		    curp);
    292 		if ((error = vn_open(&nd, FREAD|FWRITE, 0)) != 0) {
    293 			curp->p_traceflag &= ~KTRFAC_ACTIVE;
    294 			return (error);
    295 		}
    296 		vp = nd.ni_vp;
    297 		VOP_UNLOCK(vp);
    298 		if (vp->v_type != VREG) {
    299 			(void) vn_close(vp, FREAD|FWRITE, curp->p_ucred, curp);
    300 			curp->p_traceflag &= ~KTRFAC_ACTIVE;
    301 			return (EACCES);
    302 		}
    303 	}
    304 	/*
    305 	 * Clear all uses of the tracefile
    306 	 */
    307 	if (ops == KTROP_CLEARFILE) {
    308 		for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
    309 			if (p->p_tracep == vp) {
    310 				if (ktrcanset(curp, p)) {
    311 					p->p_tracep = NULL;
    312 					p->p_traceflag = 0;
    313 					(void) vn_close(vp, FREAD|FWRITE,
    314 						p->p_ucred, p);
    315 				} else
    316 					error = EPERM;
    317 			}
    318 		}
    319 		goto done;
    320 	}
    321 	/*
    322 	 * need something to (un)trace (XXX - why is this here?)
    323 	 */
    324 	if (!facs) {
    325 		error = EINVAL;
    326 		goto done;
    327 	}
    328 	/*
    329 	 * do it
    330 	 */
    331 	if (SCARG(uap, pid) < 0) {
    332 		/*
    333 		 * by process group
    334 		 */
    335 		pg = pgfind(-SCARG(uap, pid));
    336 		if (pg == NULL) {
    337 			error = ESRCH;
    338 			goto done;
    339 		}
    340 		for (p = pg->pg_members.lh_first; p != 0; p = p->p_pglist.le_next)
    341 			if (descend)
    342 				ret |= ktrsetchildren(curp, p, ops, facs, vp);
    343 			else
    344 				ret |= ktrops(curp, p, ops, facs, vp);
    345 
    346 	} else {
    347 		/*
    348 		 * by pid
    349 		 */
    350 		p = pfind(SCARG(uap, pid));
    351 		if (p == NULL) {
    352 			error = ESRCH;
    353 			goto done;
    354 		}
    355 		if (descend)
    356 			ret |= ktrsetchildren(curp, p, ops, facs, vp);
    357 		else
    358 			ret |= ktrops(curp, p, ops, facs, vp);
    359 	}
    360 	if (!ret)
    361 		error = EPERM;
    362 done:
    363 	if (vp != NULL)
    364 		(void) vn_close(vp, FWRITE, curp->p_ucred, curp);
    365 	curp->p_traceflag &= ~KTRFAC_ACTIVE;
    366 	return (error);
    367 }
    368 
    369 int
    370 ktrops(curp, p, ops, facs, vp)
    371 	struct proc *p, *curp;
    372 	int ops, facs;
    373 	struct vnode *vp;
    374 {
    375 
    376 	if (!ktrcanset(curp, p))
    377 		return (0);
    378 	if (ops == KTROP_SET) {
    379 		if (p->p_tracep != vp) {
    380 			/*
    381 			 * if trace file already in use, relinquish
    382 			 */
    383 			if (p->p_tracep != NULL)
    384 				vrele(p->p_tracep);
    385 			VREF(vp);
    386 			p->p_tracep = vp;
    387 		}
    388 		p->p_traceflag |= facs;
    389 		if (curp->p_ucred->cr_uid == 0)
    390 			p->p_traceflag |= KTRFAC_ROOT;
    391 	} else {
    392 		/* KTROP_CLEAR */
    393 		if (((p->p_traceflag &= ~facs) & KTRFAC_MASK) == 0) {
    394 			/* no more tracing */
    395 			p->p_traceflag = 0;
    396 			if (p->p_tracep != NULL) {
    397 				vrele(p->p_tracep);
    398 				p->p_tracep = NULL;
    399 			}
    400 		}
    401 	}
    402 
    403 	/*
    404 	 * Emit an emulation record, every time there is a ktrace
    405 	 * change/attach request.
    406 	 */
    407 	if (KTRPOINT(p, KTR_EMUL))
    408 		ktremul(p->p_tracep, p->p_emul->e_name);
    409 
    410 	return (1);
    411 }
    412 
    413 int
    414 ktrsetchildren(curp, top, ops, facs, vp)
    415 	struct proc *curp, *top;
    416 	int ops, facs;
    417 	struct vnode *vp;
    418 {
    419 	register struct proc *p;
    420 	register int ret = 0;
    421 
    422 	p = top;
    423 	for (;;) {
    424 		ret |= ktrops(curp, p, ops, facs, vp);
    425 		/*
    426 		 * If this process has children, descend to them next,
    427 		 * otherwise do any siblings, and if done with this level,
    428 		 * follow back up the tree (but not past top).
    429 		 */
    430 		if (p->p_children.lh_first)
    431 			p = p->p_children.lh_first;
    432 		else for (;;) {
    433 			if (p == top)
    434 				return (ret);
    435 			if (p->p_sibling.le_next) {
    436 				p = p->p_sibling.le_next;
    437 				break;
    438 			}
    439 			p = p->p_pptr;
    440 		}
    441 	}
    442 	/*NOTREACHED*/
    443 }
    444 
    445 void
    446 ktrwrite(vp, kth)
    447 	struct vnode *vp;
    448 	register struct ktr_header *kth;
    449 {
    450 	struct uio auio;
    451 	struct iovec aiov[2];
    452 	register struct proc *p = curproc;	/* XXX */
    453 	int error;
    454 
    455 	if (vp == NULL)
    456 		return;
    457 	auio.uio_iov = &aiov[0];
    458 	auio.uio_offset = 0;
    459 	auio.uio_segflg = UIO_SYSSPACE;
    460 	auio.uio_rw = UIO_WRITE;
    461 	aiov[0].iov_base = (caddr_t)kth;
    462 	aiov[0].iov_len = sizeof(struct ktr_header);
    463 	auio.uio_resid = sizeof(struct ktr_header);
    464 	auio.uio_iovcnt = 1;
    465 	auio.uio_procp = (struct proc *)0;
    466 	if (kth->ktr_len > 0) {
    467 		auio.uio_iovcnt++;
    468 		aiov[1].iov_base = kth->ktr_buf;
    469 		aiov[1].iov_len = kth->ktr_len;
    470 		auio.uio_resid += kth->ktr_len;
    471 	}
    472 	VOP_LOCK(vp);
    473 	error = VOP_WRITE(vp, &auio, IO_UNIT|IO_APPEND, p->p_ucred);
    474 	VOP_UNLOCK(vp);
    475 	if (!error)
    476 		return;
    477 	/*
    478 	 * If error encountered, give up tracing on this vnode.
    479 	 */
    480 	log(LOG_NOTICE, "ktrace write failed, errno %d, tracing stopped\n",
    481 	    error);
    482 	for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
    483 		if (p->p_tracep == vp) {
    484 			p->p_tracep = NULL;
    485 			p->p_traceflag = 0;
    486 			vrele(vp);
    487 		}
    488 	}
    489 }
    490 
    491 /*
    492  * Return true if caller has permission to set the ktracing state
    493  * of target.  Essentially, the target can't possess any
    494  * more permissions than the caller.  KTRFAC_ROOT signifies that
    495  * root previously set the tracing status on the target process, and
    496  * so, only root may further change it.
    497  *
    498  * TODO: check groups.  use caller effective gid.
    499  */
    500 int
    501 ktrcanset(callp, targetp)
    502 	struct proc *callp, *targetp;
    503 {
    504 	register struct pcred *caller = callp->p_cred;
    505 	register struct pcred *target = targetp->p_cred;
    506 
    507 	if ((caller->pc_ucred->cr_uid == target->p_ruid &&
    508 	     target->p_ruid == target->p_svuid &&
    509 	     caller->p_rgid == target->p_rgid &&	/* XXX */
    510 	     target->p_rgid == target->p_svgid &&
    511 	     (targetp->p_traceflag & KTRFAC_ROOT) == 0) ||
    512 	     caller->pc_ucred->cr_uid == 0)
    513 		return (1);
    514 
    515 	return (0);
    516 }
    517 
    518 #endif
    519