Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_ktrace.c
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1 /* 2 * Copyright (c) 1989, 1993 3 * The Regents of the University of California. 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 * @(#)kern_ktrace.c 8.2 (Berkeley) 9/23/93 34 * $FreeBSD$ 35 */ 36 37 #include "opt_ktrace.h" 38 39 #include <sys/param.h> 40 #include <sys/systm.h> 41 #include <sys/sysproto.h> 42 #include <sys/kernel.h> 43 #include <sys/proc.h> 44 #include <sys/fcntl.h> 45 #include <sys/lock.h> 46 #include <sys/namei.h> 47 #include <sys/vnode.h> 48 #include <sys/ktrace.h> 49 #include <sys/malloc.h> 50 #include <sys/syslog.h> 51 #include <sys/sysent.h> 52 53 #include <vm/vm_zone.h> 54 static MALLOC_DEFINE(M_KTRACE, "KTRACE", "KTRACE"); 55 56 #ifdef KTRACE 57 static struct ktr_header *ktrgetheader __P((int type)); 58 static void ktrwrite __P((struct vnode *, struct ktr_header *, struct uio *)); 59 static int ktrcanset __P((struct proc *,struct proc *)); 60 static int ktrsetchildren __P((struct proc *,struct proc *,int,int,struct vnode *)); 61 static int ktrops __P((struct proc *,struct proc *,int,int,struct vnode *)); 62 63 64 static struct ktr_header * 65 ktrgetheader(type) 66 int type; 67 { 68 register struct ktr_header *kth; 69 struct proc *p = curproc; /* XXX */ 70 71 MALLOC(kth, struct ktr_header *, sizeof (struct ktr_header), 72 M_KTRACE, M_WAITOK); 73 kth->ktr_type = type; 74 microtime(&kth->ktr_time); 75 kth->ktr_pid = p->p_pid; 76 bcopy(p->p_comm, kth->ktr_comm, MAXCOMLEN + 1); 77 return (kth); 78 } 79 80 void 81 ktrsyscall(vp, code, narg, args) 82 struct vnode *vp; 83 int code, narg; 84 register_t args[]; 85 { 86 struct ktr_header *kth; 87 struct ktr_syscall *ktp; 88 register int len = offsetof(struct ktr_syscall, ktr_args) + 89 (narg * sizeof(register_t)); 90 struct proc *p = curproc; /* XXX */ 91 register_t *argp; 92 int i; 93 94 p->p_traceflag |= KTRFAC_ACTIVE; 95 kth = ktrgetheader(KTR_SYSCALL); 96 MALLOC(ktp, struct ktr_syscall *, len, M_KTRACE, M_WAITOK); 97 ktp->ktr_code = code; 98 ktp->ktr_narg = narg; 99 argp = &ktp->ktr_args[0]; 100 for (i = 0; i < narg; i++) 101 *argp++ = args[i]; 102 kth->ktr_buf = (caddr_t)ktp; 103 kth->ktr_len = len; 104 ktrwrite(vp, kth, NULL); 105 FREE(ktp, M_KTRACE); 106 FREE(kth, M_KTRACE); 107 p->p_traceflag &= ~KTRFAC_ACTIVE; 108 } 109 110 void 111 ktrsysret(vp, code, error, retval) 112 struct vnode *vp; 113 int code, error; 114 register_t retval; 115 { 116 struct ktr_header *kth; 117 struct ktr_sysret ktp; 118 struct proc *p = curproc; /* XXX */ 119 120 p->p_traceflag |= KTRFAC_ACTIVE; 121 kth = ktrgetheader(KTR_SYSRET); 122 ktp.ktr_code = code; 123 ktp.ktr_error = error; 124 ktp.ktr_retval = retval; /* what about val2 ? */ 125 126 kth->ktr_buf = (caddr_t)&ktp; 127 kth->ktr_len = sizeof(struct ktr_sysret); 128 129 ktrwrite(vp, kth, NULL); 130 FREE(kth, M_KTRACE); 131 p->p_traceflag &= ~KTRFAC_ACTIVE; 132 } 133 134 void 135 ktrnamei(vp, path) 136 struct vnode *vp; 137 char *path; 138 { 139 struct ktr_header *kth; 140 struct proc *p = curproc; /* XXX */ 141 142 /* 143 * don't let vp get ripped out from under us 144 */ 145 if (vp) 146 VREF(vp); 147 p->p_traceflag |= KTRFAC_ACTIVE; 148 kth = ktrgetheader(KTR_NAMEI); 149 kth->ktr_len = strlen(path); 150 kth->ktr_buf = path; 151 152 ktrwrite(vp, kth, NULL); 153 if (vp) 154 vrele(vp); 155 FREE(kth, M_KTRACE); 156 p->p_traceflag &= ~KTRFAC_ACTIVE; 157 } 158 159 void 160 ktrgenio(vp, fd, rw, uio, error) 161 struct vnode *vp; 162 int fd; 163 enum uio_rw rw; 164 struct uio *uio; 165 int error; 166 { 167 struct ktr_header *kth; 168 struct ktr_genio ktg; 169 struct proc *p = curproc; /* XXX */ 170 171 if (error) 172 return; 173 /* 174 * don't let p_tracep get ripped out from under us 175 */ 176 if (vp) 177 VREF(vp); 178 p->p_traceflag |= KTRFAC_ACTIVE; 179 kth = ktrgetheader(KTR_GENIO); 180 ktg.ktr_fd = fd; 181 ktg.ktr_rw = rw; 182 kth->ktr_buf = (caddr_t)&ktg; 183 kth->ktr_len = sizeof(struct ktr_genio); 184 uio->uio_offset = 0; 185 uio->uio_rw = UIO_WRITE; 186 187 ktrwrite(vp, kth, uio); 188 if (vp) 189 vrele(vp); 190 FREE(kth, M_KTRACE); 191 p->p_traceflag &= ~KTRFAC_ACTIVE; 192 } 193 194 void 195 ktrpsig(vp, sig, action, mask, code) 196 struct vnode *vp; 197 int sig; 198 sig_t action; 199 sigset_t *mask; 200 int code; 201 { 202 struct ktr_header *kth; 203 struct ktr_psig kp; 204 struct proc *p = curproc; /* XXX */ 205 206 /* 207 * don't let vp get ripped out from under us 208 */ 209 if (vp) 210 VREF(vp); 211 p->p_traceflag |= KTRFAC_ACTIVE; 212 kth = ktrgetheader(KTR_PSIG); 213 kp.signo = (char)sig; 214 kp.action = action; 215 kp.mask = *mask; 216 kp.code = code; 217 kth->ktr_buf = (caddr_t)&kp; 218 kth->ktr_len = sizeof (struct ktr_psig); 219 220 ktrwrite(vp, kth, NULL); 221 if (vp) 222 vrele(vp); 223 FREE(kth, M_KTRACE); 224 p->p_traceflag &= ~KTRFAC_ACTIVE; 225 } 226 227 void 228 ktrcsw(vp, out, user) 229 struct vnode *vp; 230 int out, user; 231 { 232 struct ktr_header *kth; 233 struct ktr_csw kc; 234 struct proc *p = curproc; /* XXX */ 235 236 /* 237 * don't let vp get ripped out from under us 238 */ 239 if (vp) 240 VREF(vp); 241 p->p_traceflag |= KTRFAC_ACTIVE; 242 kth = ktrgetheader(KTR_CSW); 243 kc.out = out; 244 kc.user = user; 245 kth->ktr_buf = (caddr_t)&kc; 246 kth->ktr_len = sizeof (struct ktr_csw); 247 248 ktrwrite(vp, kth, NULL); 249 if (vp) 250 vrele(vp); 251 FREE(kth, M_KTRACE); 252 p->p_traceflag &= ~KTRFAC_ACTIVE; 253 } 254 #endif 255 256 /* Interface and common routines */ 257 258 /* 259 * ktrace system call 260 */ 261 #ifndef _SYS_SYSPROTO_H_ 262 struct ktrace_args { 263 char *fname; 264 int ops; 265 int facs; 266 int pid; 267 }; 268 #endif 269 /* ARGSUSED */ 270 int 271 ktrace(curp, uap) 272 struct proc *curp; 273 register struct ktrace_args *uap; 274 { 275 #ifdef KTRACE 276 register struct vnode *vp = NULL; 277 register struct proc *p; 278 struct pgrp *pg; 279 int facs = uap->facs & ~KTRFAC_ROOT; 280 int ops = KTROP(uap->ops); 281 int descend = uap->ops & KTRFLAG_DESCEND; 282 int ret = 0; 283 int error = 0; 284 struct nameidata nd; 285 286 curp->p_traceflag |= KTRFAC_ACTIVE; 287 if (ops != KTROP_CLEAR) { 288 /* 289 * an operation which requires a file argument. 290 */ 291 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_USERSPACE, uap->fname, curp); 292 error = vn_open(&nd, FREAD|FWRITE|O_NOFOLLOW, 0); 293 if (error) { 294 curp->p_traceflag &= ~KTRFAC_ACTIVE; 295 return (error); 296 } 297 NDFREE(&nd, NDF_ONLY_PNBUF); 298 vp = nd.ni_vp; 299 VOP_UNLOCK(vp, 0, curp); 300 if (vp->v_type != VREG) { 301 (void) vn_close(vp, FREAD|FWRITE, curp->p_ucred, curp); 302 curp->p_traceflag &= ~KTRFAC_ACTIVE; 303 return (EACCES); 304 } 305 } 306 /* 307 * Clear all uses of the tracefile. XXX umm, what happens to the 308 * loop if vn_close() blocks? 309 */ 310 if (ops == KTROP_CLEARFILE) { 311 LIST_FOREACH(p, &allproc, p_list) { 312 if (p->p_tracep == vp) { 313 if (ktrcanset(curp, p) && p->p_tracep == vp) { 314 p->p_tracep = NULL; 315 p->p_traceflag = 0; 316 (void) vn_close(vp, FREAD|FWRITE, 317 p->p_ucred, p); 318 } else { 319 error = EPERM; 320 } 321 } 322 } 323 goto done; 324 } 325 /* 326 * need something to (un)trace (XXX - why is this here?) 327 */ 328 if (!facs) { 329 error = EINVAL; 330 goto done; 331 } 332 /* 333 * do it 334 */ 335 if (uap->pid < 0) { 336 /* 337 * by process group 338 */ 339 pg = pgfind(-uap->pid); 340 if (pg == NULL) { 341 error = ESRCH; 342 goto done; 343 } 344 LIST_FOREACH(p, &pg->pg_members, p_pglist) 345 if (descend) 346 ret |= ktrsetchildren(curp, p, ops, facs, vp); 347 else 348 ret |= ktrops(curp, p, ops, facs, vp); 349 350 } else { 351 /* 352 * by pid 353 */ 354 p = pfind(uap->pid); 355 if (p == NULL) { 356 error = ESRCH; 357 goto done; 358 } 359 if (descend) 360 ret |= ktrsetchildren(curp, p, ops, facs, vp); 361 else 362 ret |= ktrops(curp, p, ops, facs, vp); 363 } 364 if (!ret) 365 error = EPERM; 366 done: 367 if (vp != NULL) 368 (void) vn_close(vp, FWRITE, curp->p_ucred, curp); 369 curp->p_traceflag &= ~KTRFAC_ACTIVE; 370 return (error); 371 #else 372 return ENOSYS; 373 #endif 374 } 375 376 /* 377 * utrace system call 378 */ 379 /* ARGSUSED */ 380 int 381 utrace(curp, uap) 382 struct proc *curp; 383 register struct utrace_args *uap; 384 { 385 #ifdef KTRACE 386 struct ktr_header *kth; 387 struct proc *p = curproc; /* XXX */ 388 struct vnode *vp; 389 register caddr_t cp; 390 391 if (!KTRPOINT(p, KTR_USER)) 392 return (0); 393 if (SCARG(uap, len) > KTR_USER_MAXLEN) 394 return (EINVAL); 395 p->p_traceflag |= KTRFAC_ACTIVE; 396 /* 397 * don't let p_tracep get ripped out from under us while we are 398 * writing. 399 */ 400 if ((vp = p->p_tracep) != NULL) 401 VREF(vp); 402 kth = ktrgetheader(KTR_USER); 403 MALLOC(cp, caddr_t, uap->len, M_KTRACE, M_WAITOK); 404 if (!copyin(uap->addr, cp, uap->len)) { 405 kth->ktr_buf = cp; 406 kth->ktr_len = uap->len; 407 ktrwrite(vp, kth, NULL); 408 } 409 if (vp) 410 vrele(vp); 411 FREE(kth, M_KTRACE); 412 FREE(cp, M_KTRACE); 413 p->p_traceflag &= ~KTRFAC_ACTIVE; 414 415 return (0); 416 #else 417 return (ENOSYS); 418 #endif 419 } 420 421 #ifdef KTRACE 422 static int 423 ktrops(curp, p, ops, facs, vp) 424 struct proc *p, *curp; 425 int ops, facs; 426 struct vnode *vp; 427 { 428 429 if (!ktrcanset(curp, p)) 430 return (0); 431 if (ops == KTROP_SET) { 432 if (p->p_tracep != vp) { 433 struct vnode *vtmp; 434 435 /* 436 * if trace file already in use, relinquish 437 */ 438 VREF(vp); 439 while ((vtmp = p->p_tracep) != NULL) { 440 p->p_tracep = NULL; 441 vrele(vtmp); 442 } 443 p->p_tracep = vp; 444 } 445 p->p_traceflag |= facs; 446 if (curp->p_ucred->cr_uid == 0) 447 p->p_traceflag |= KTRFAC_ROOT; 448 } else { 449 /* KTROP_CLEAR */ 450 if (((p->p_traceflag &= ~facs) & KTRFAC_MASK) == 0) { 451 struct vnode *vtmp; 452 453 /* no more tracing */ 454 p->p_traceflag = 0; 455 if ((vtmp = p->p_tracep) != NULL) { 456 p->p_tracep = NULL; 457 vrele(vtmp); 458 } 459 } 460 } 461 462 return (1); 463 } 464 465 static int 466 ktrsetchildren(curp, top, ops, facs, vp) 467 struct proc *curp, *top; 468 int ops, facs; 469 struct vnode *vp; 470 { 471 register struct proc *p; 472 register int ret = 0; 473 474 p = top; 475 for (;;) { 476 ret |= ktrops(curp, p, ops, facs, vp); 477 /* 478 * If this process has children, descend to them next, 479 * otherwise do any siblings, and if done with this level, 480 * follow back up the tree (but not past top). 481 */ 482 if (!LIST_EMPTY(&p->p_children)) 483 p = LIST_FIRST(&p->p_children); 484 else for (;;) { 485 if (p == top) 486 return (ret); 487 if (LIST_NEXT(p, p_sibling)) { 488 p = LIST_NEXT(p, p_sibling); 489 break; 490 } 491 p = p->p_pptr; 492 } 493 } 494 /*NOTREACHED*/ 495 } 496 497 static void 498 ktrwrite(vp, kth, uio) 499 struct vnode *vp; 500 register struct ktr_header *kth; 501 struct uio *uio; 502 { 503 struct uio auio; 504 struct iovec aiov[2]; 505 register struct proc *p = curproc; /* XXX */ 506 int error; 507 508 if (vp == NULL) 509 return; 510 auio.uio_iov = &aiov[0]; 511 auio.uio_offset = 0; 512 auio.uio_segflg = UIO_SYSSPACE; 513 auio.uio_rw = UIO_WRITE; 514 aiov[0].iov_base = (caddr_t)kth; 515 aiov[0].iov_len = sizeof(struct ktr_header); 516 auio.uio_resid = sizeof(struct ktr_header); 517 auio.uio_iovcnt = 1; 518 auio.uio_procp = curproc; 519 if (kth->ktr_len > 0) { 520 auio.uio_iovcnt++; 521 aiov[1].iov_base = kth->ktr_buf; 522 aiov[1].iov_len = kth->ktr_len; 523 auio.uio_resid += kth->ktr_len; 524 if (uio != NULL) 525 kth->ktr_len += uio->uio_resid; 526 } 527 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p); 528 (void)VOP_LEASE(vp, p, p->p_ucred, LEASE_WRITE); 529 error = VOP_WRITE(vp, &auio, IO_UNIT | IO_APPEND, p->p_ucred); 530 if (error == 0 && uio != NULL) { 531 (void)VOP_LEASE(vp, p, p->p_ucred, LEASE_WRITE); 532 error = VOP_WRITE(vp, uio, IO_UNIT | IO_APPEND, p->p_ucred); 533 } 534 VOP_UNLOCK(vp, 0, p); 535 if (!error) 536 return; 537 /* 538 * If error encountered, give up tracing on this vnode. XXX what 539 * happens to the loop if vrele() blocks? 540 */ 541 log(LOG_NOTICE, "ktrace write failed, errno %d, tracing stopped\n", 542 error); 543 LIST_FOREACH(p, &allproc, p_list) { 544 if (p->p_tracep == vp) { 545 p->p_tracep = NULL; 546 p->p_traceflag = 0; 547 vrele(vp); 548 } 549 } 550 } 551 552 /* 553 * Return true if caller has permission to set the ktracing state 554 * of target. Essentially, the target can't possess any 555 * more permissions than the caller. KTRFAC_ROOT signifies that 556 * root previously set the tracing status on the target process, and 557 * so, only root may further change it. 558 * 559 * TODO: check groups. use caller effective gid. 560 */ 561 static int 562 ktrcanset(callp, targetp) 563 struct proc *callp, *targetp; 564 { 565 register struct pcred *caller = callp->p_cred; 566 register struct pcred *target = targetp->p_cred; 567 568 if (!PRISON_CHECK(callp, targetp)) 569 return (0); 570 if ((caller->pc_ucred->cr_uid == target->p_ruid && 571 target->p_ruid == target->p_svuid && 572 caller->p_rgid == target->p_rgid && /* XXX */ 573 target->p_rgid == target->p_svgid && 574 (targetp->p_traceflag & KTRFAC_ROOT) == 0 && 575 (targetp->p_flag & P_SUGID) == 0) || 576 caller->pc_ucred->cr_uid == 0) 577 return (1); 578 579 return (0); 580 } 581 582 #endif /* KTRACE */
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