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: releng/5.1/sys/kern/kern_ktrace.c 114026 2003-04-25 19:59:35Z jhb $ 35 */ 36 37 #include "opt_ktrace.h" 38 #include "opt_mac.h" 39 40 #include <sys/param.h> 41 #include <sys/systm.h> 42 #include <sys/fcntl.h> 43 #include <sys/jail.h> 44 #include <sys/kernel.h> 45 #include <sys/kthread.h> 46 #include <sys/lock.h> 47 #include <sys/mutex.h> 48 #include <sys/mac.h> 49 #include <sys/malloc.h> 50 #include <sys/namei.h> 51 #include <sys/proc.h> 52 #include <sys/unistd.h> 53 #include <sys/vnode.h> 54 #include <sys/ktrace.h> 55 #include <sys/sema.h> 56 #include <sys/sx.h> 57 #include <sys/sysctl.h> 58 #include <sys/syslog.h> 59 #include <sys/sysproto.h> 60 61 static MALLOC_DEFINE(M_KTRACE, "KTRACE", "KTRACE"); 62 63 #ifdef KTRACE 64 65 #ifndef KTRACE_REQUEST_POOL 66 #define KTRACE_REQUEST_POOL 100 67 #endif 68 69 struct ktr_request { 70 struct ktr_header ktr_header; 71 struct ucred *ktr_cred; 72 struct vnode *ktr_vp; 73 union { 74 struct ktr_syscall ktr_syscall; 75 struct ktr_sysret ktr_sysret; 76 struct ktr_genio ktr_genio; 77 struct ktr_psig ktr_psig; 78 struct ktr_csw ktr_csw; 79 } ktr_data; 80 STAILQ_ENTRY(ktr_request) ktr_list; 81 }; 82 83 static int data_lengths[] = { 84 0, /* none */ 85 offsetof(struct ktr_syscall, ktr_args), /* KTR_SYSCALL */ 86 sizeof(struct ktr_sysret), /* KTR_SYSRET */ 87 0, /* KTR_NAMEI */ 88 sizeof(struct ktr_genio), /* KTR_GENIO */ 89 sizeof(struct ktr_psig), /* KTR_PSIG */ 90 sizeof(struct ktr_csw), /* KTR_CSW */ 91 0 /* KTR_USER */ 92 }; 93 94 static STAILQ_HEAD(, ktr_request) ktr_todo; 95 static STAILQ_HEAD(, ktr_request) ktr_free; 96 97 SYSCTL_NODE(_kern, OID_AUTO, ktrace, CTLFLAG_RD, 0, "KTRACE options"); 98 99 static uint ktr_requestpool = KTRACE_REQUEST_POOL; 100 TUNABLE_INT("kern.ktrace.request_pool", &ktr_requestpool); 101 102 static uint ktr_geniosize = PAGE_SIZE; 103 TUNABLE_INT("kern.ktrace.genio_size", &ktr_geniosize); 104 SYSCTL_UINT(_kern_ktrace, OID_AUTO, genio_size, CTLFLAG_RW, &ktr_geniosize, 105 0, "Maximum size of genio event payload"); 106 107 static int print_message = 1; 108 struct mtx ktrace_mtx; 109 static struct sema ktrace_sema; 110 111 static void ktrace_init(void *dummy); 112 static int sysctl_kern_ktrace_request_pool(SYSCTL_HANDLER_ARGS); 113 static uint ktrace_resize_pool(uint newsize); 114 static struct ktr_request *ktr_getrequest(int type); 115 static void ktr_submitrequest(struct ktr_request *req); 116 static void ktr_freerequest(struct ktr_request *req); 117 static void ktr_loop(void *dummy); 118 static void ktr_writerequest(struct ktr_request *req); 119 static int ktrcanset(struct thread *,struct proc *); 120 static int ktrsetchildren(struct thread *,struct proc *,int,int,struct vnode *); 121 static int ktrops(struct thread *,struct proc *,int,int,struct vnode *); 122 123 static void 124 ktrace_init(void *dummy) 125 { 126 struct ktr_request *req; 127 int i; 128 129 mtx_init(&ktrace_mtx, "ktrace", NULL, MTX_DEF | MTX_QUIET); 130 sema_init(&ktrace_sema, 0, "ktrace"); 131 STAILQ_INIT(&ktr_todo); 132 STAILQ_INIT(&ktr_free); 133 for (i = 0; i < ktr_requestpool; i++) { 134 req = malloc(sizeof(struct ktr_request), M_KTRACE, M_WAITOK); 135 STAILQ_INSERT_HEAD(&ktr_free, req, ktr_list); 136 } 137 kthread_create(ktr_loop, NULL, NULL, RFHIGHPID, 0, "ktrace"); 138 } 139 SYSINIT(ktrace_init, SI_SUB_KTRACE, SI_ORDER_ANY, ktrace_init, NULL); 140 141 static int 142 sysctl_kern_ktrace_request_pool(SYSCTL_HANDLER_ARGS) 143 { 144 struct thread *td; 145 uint newsize, oldsize, wantsize; 146 int error; 147 148 /* Handle easy read-only case first to avoid warnings from GCC. */ 149 if (!req->newptr) { 150 mtx_lock(&ktrace_mtx); 151 oldsize = ktr_requestpool; 152 mtx_unlock(&ktrace_mtx); 153 return (SYSCTL_OUT(req, &oldsize, sizeof(uint))); 154 } 155 156 error = SYSCTL_IN(req, &wantsize, sizeof(uint)); 157 if (error) 158 return (error); 159 td = curthread; 160 td->td_inktrace = 1; 161 mtx_lock(&ktrace_mtx); 162 oldsize = ktr_requestpool; 163 newsize = ktrace_resize_pool(wantsize); 164 mtx_unlock(&ktrace_mtx); 165 td->td_inktrace = 0; 166 error = SYSCTL_OUT(req, &oldsize, sizeof(uint)); 167 if (error) 168 return (error); 169 if (newsize != wantsize) 170 return (ENOSPC); 171 return (0); 172 } 173 SYSCTL_PROC(_kern_ktrace, OID_AUTO, request_pool, CTLTYPE_UINT|CTLFLAG_RW, 174 &ktr_requestpool, 0, sysctl_kern_ktrace_request_pool, "IU", ""); 175 176 static uint 177 ktrace_resize_pool(uint newsize) 178 { 179 struct ktr_request *req; 180 181 mtx_assert(&ktrace_mtx, MA_OWNED); 182 print_message = 1; 183 if (newsize == ktr_requestpool) 184 return (newsize); 185 if (newsize < ktr_requestpool) 186 /* Shrink pool down to newsize if possible. */ 187 while (ktr_requestpool > newsize) { 188 req = STAILQ_FIRST(&ktr_free); 189 if (req == NULL) 190 return (ktr_requestpool); 191 STAILQ_REMOVE_HEAD(&ktr_free, ktr_list); 192 ktr_requestpool--; 193 mtx_unlock(&ktrace_mtx); 194 free(req, M_KTRACE); 195 mtx_lock(&ktrace_mtx); 196 } 197 else 198 /* Grow pool up to newsize. */ 199 while (ktr_requestpool < newsize) { 200 mtx_unlock(&ktrace_mtx); 201 req = malloc(sizeof(struct ktr_request), M_KTRACE, 202 M_WAITOK); 203 mtx_lock(&ktrace_mtx); 204 STAILQ_INSERT_HEAD(&ktr_free, req, ktr_list); 205 ktr_requestpool++; 206 } 207 return (ktr_requestpool); 208 } 209 210 static struct ktr_request * 211 ktr_getrequest(int type) 212 { 213 struct ktr_request *req; 214 struct thread *td = curthread; 215 struct proc *p = td->td_proc; 216 int pm; 217 218 td->td_inktrace = 1; 219 mtx_lock(&ktrace_mtx); 220 if (!KTRCHECK(td, type)) { 221 mtx_unlock(&ktrace_mtx); 222 td->td_inktrace = 0; 223 return (NULL); 224 } 225 req = STAILQ_FIRST(&ktr_free); 226 if (req != NULL) { 227 STAILQ_REMOVE_HEAD(&ktr_free, ktr_list); 228 req->ktr_header.ktr_type = type; 229 if (p->p_traceflag & KTRFAC_DROP) { 230 req->ktr_header.ktr_type |= KTR_DROP; 231 p->p_traceflag &= ~KTRFAC_DROP; 232 } 233 KASSERT(p->p_tracevp != NULL, ("ktrace: no trace vnode")); 234 KASSERT(p->p_tracecred != NULL, ("ktrace: no trace cred")); 235 req->ktr_vp = p->p_tracevp; 236 VREF(p->p_tracevp); 237 req->ktr_cred = crhold(p->p_tracecred); 238 mtx_unlock(&ktrace_mtx); 239 microtime(&req->ktr_header.ktr_time); 240 req->ktr_header.ktr_pid = p->p_pid; 241 bcopy(p->p_comm, req->ktr_header.ktr_comm, MAXCOMLEN + 1); 242 req->ktr_header.ktr_buffer = NULL; 243 req->ktr_header.ktr_len = 0; 244 } else { 245 p->p_traceflag |= KTRFAC_DROP; 246 pm = print_message; 247 print_message = 0; 248 mtx_unlock(&ktrace_mtx); 249 if (pm) 250 printf("Out of ktrace request objects.\n"); 251 td->td_inktrace = 0; 252 } 253 return (req); 254 } 255 256 static void 257 ktr_submitrequest(struct ktr_request *req) 258 { 259 260 mtx_lock(&ktrace_mtx); 261 STAILQ_INSERT_TAIL(&ktr_todo, req, ktr_list); 262 sema_post(&ktrace_sema); 263 mtx_unlock(&ktrace_mtx); 264 curthread->td_inktrace = 0; 265 } 266 267 static void 268 ktr_freerequest(struct ktr_request *req) 269 { 270 271 crfree(req->ktr_cred); 272 if (req->ktr_vp != NULL) { 273 mtx_lock(&Giant); 274 vrele(req->ktr_vp); 275 mtx_unlock(&Giant); 276 } 277 if (req->ktr_header.ktr_buffer != NULL) 278 free(req->ktr_header.ktr_buffer, M_KTRACE); 279 mtx_lock(&ktrace_mtx); 280 STAILQ_INSERT_HEAD(&ktr_free, req, ktr_list); 281 mtx_unlock(&ktrace_mtx); 282 } 283 284 static void 285 ktr_loop(void *dummy) 286 { 287 struct ktr_request *req; 288 struct thread *td; 289 struct ucred *cred; 290 291 /* Only cache these values once. */ 292 td = curthread; 293 cred = td->td_ucred; 294 for (;;) { 295 sema_wait(&ktrace_sema); 296 mtx_lock(&ktrace_mtx); 297 req = STAILQ_FIRST(&ktr_todo); 298 STAILQ_REMOVE_HEAD(&ktr_todo, ktr_list); 299 KASSERT(req != NULL, ("got a NULL request")); 300 mtx_unlock(&ktrace_mtx); 301 /* 302 * It is not enough just to pass the cached cred 303 * to the VOP's in ktr_writerequest(). Some VFS 304 * operations use curthread->td_ucred, so we need 305 * to modify our thread's credentials as well. 306 * Evil. 307 */ 308 td->td_ucred = req->ktr_cred; 309 ktr_writerequest(req); 310 td->td_ucred = cred; 311 ktr_freerequest(req); 312 } 313 } 314 315 /* 316 * MPSAFE 317 */ 318 void 319 ktrsyscall(code, narg, args) 320 int code, narg; 321 register_t args[]; 322 { 323 struct ktr_request *req; 324 struct ktr_syscall *ktp; 325 size_t buflen; 326 char *buf = NULL; 327 328 buflen = sizeof(register_t) * narg; 329 if (buflen > 0) { 330 buf = malloc(buflen, M_KTRACE, M_WAITOK); 331 bcopy(args, buf, buflen); 332 } 333 req = ktr_getrequest(KTR_SYSCALL); 334 if (req == NULL) { 335 if (buf != NULL) 336 free(buf, M_KTRACE); 337 return; 338 } 339 ktp = &req->ktr_data.ktr_syscall; 340 ktp->ktr_code = code; 341 ktp->ktr_narg = narg; 342 if (buflen > 0) { 343 req->ktr_header.ktr_len = buflen; 344 req->ktr_header.ktr_buffer = buf; 345 } 346 ktr_submitrequest(req); 347 } 348 349 /* 350 * MPSAFE 351 */ 352 void 353 ktrsysret(code, error, retval) 354 int code, error; 355 register_t retval; 356 { 357 struct ktr_request *req; 358 struct ktr_sysret *ktp; 359 360 req = ktr_getrequest(KTR_SYSRET); 361 if (req == NULL) 362 return; 363 ktp = &req->ktr_data.ktr_sysret; 364 ktp->ktr_code = code; 365 ktp->ktr_error = error; 366 ktp->ktr_retval = retval; /* what about val2 ? */ 367 ktr_submitrequest(req); 368 } 369 370 void 371 ktrnamei(path) 372 char *path; 373 { 374 struct ktr_request *req; 375 int namelen; 376 char *buf = NULL; 377 378 namelen = strlen(path); 379 if (namelen > 0) { 380 buf = malloc(namelen, M_KTRACE, M_WAITOK); 381 bcopy(path, buf, namelen); 382 } 383 req = ktr_getrequest(KTR_NAMEI); 384 if (req == NULL) { 385 if (buf != NULL) 386 free(buf, M_KTRACE); 387 return; 388 } 389 if (namelen > 0) { 390 req->ktr_header.ktr_len = namelen; 391 req->ktr_header.ktr_buffer = buf; 392 } 393 ktr_submitrequest(req); 394 } 395 396 /* 397 * Since the uio may not stay valid, we can not hand off this request to 398 * the thread and need to process it synchronously. However, we wish to 399 * keep the relative order of records in a trace file correct, so we 400 * do put this request on the queue (if it isn't empty) and then block. 401 * The ktrace thread waks us back up when it is time for this event to 402 * be posted and blocks until we have completed writing out the event 403 * and woken it back up. 404 */ 405 void 406 ktrgenio(fd, rw, uio, error) 407 int fd; 408 enum uio_rw rw; 409 struct uio *uio; 410 int error; 411 { 412 struct ktr_request *req; 413 struct ktr_genio *ktg; 414 int datalen; 415 char *buf; 416 417 if (error) 418 return; 419 uio->uio_offset = 0; 420 uio->uio_rw = UIO_WRITE; 421 datalen = imin(uio->uio_resid, ktr_geniosize); 422 buf = malloc(datalen, M_KTRACE, M_WAITOK); 423 if (uiomove(buf, datalen, uio)) { 424 free(buf, M_KTRACE); 425 return; 426 } 427 req = ktr_getrequest(KTR_GENIO); 428 if (req == NULL) { 429 free(buf, M_KTRACE); 430 return; 431 } 432 ktg = &req->ktr_data.ktr_genio; 433 ktg->ktr_fd = fd; 434 ktg->ktr_rw = rw; 435 req->ktr_header.ktr_len = datalen; 436 req->ktr_header.ktr_buffer = buf; 437 ktr_submitrequest(req); 438 } 439 440 void 441 ktrpsig(sig, action, mask, code) 442 int sig; 443 sig_t action; 444 sigset_t *mask; 445 int code; 446 { 447 struct ktr_request *req; 448 struct ktr_psig *kp; 449 450 req = ktr_getrequest(KTR_PSIG); 451 if (req == NULL) 452 return; 453 kp = &req->ktr_data.ktr_psig; 454 kp->signo = (char)sig; 455 kp->action = action; 456 kp->mask = *mask; 457 kp->code = code; 458 ktr_submitrequest(req); 459 } 460 461 void 462 ktrcsw(out, user) 463 int out, user; 464 { 465 struct ktr_request *req; 466 struct ktr_csw *kc; 467 468 req = ktr_getrequest(KTR_CSW); 469 if (req == NULL) 470 return; 471 kc = &req->ktr_data.ktr_csw; 472 kc->out = out; 473 kc->user = user; 474 ktr_submitrequest(req); 475 } 476 #endif /* KTRACE */ 477 478 /* Interface and common routines */ 479 480 /* 481 * ktrace system call 482 * 483 * MPSAFE 484 */ 485 #ifndef _SYS_SYSPROTO_H_ 486 struct ktrace_args { 487 char *fname; 488 int ops; 489 int facs; 490 int pid; 491 }; 492 #endif 493 /* ARGSUSED */ 494 int 495 ktrace(td, uap) 496 struct thread *td; 497 register struct ktrace_args *uap; 498 { 499 #ifdef KTRACE 500 register struct vnode *vp = NULL; 501 register struct proc *p; 502 struct pgrp *pg; 503 int facs = uap->facs & ~KTRFAC_ROOT; 504 int ops = KTROP(uap->ops); 505 int descend = uap->ops & KTRFLAG_DESCEND; 506 int ret = 0; 507 int flags, error = 0; 508 struct nameidata nd; 509 struct ucred *cred; 510 511 /* 512 * Need something to (un)trace. 513 */ 514 if (ops != KTROP_CLEARFILE && facs == 0) 515 return (EINVAL); 516 517 td->td_inktrace = 1; 518 if (ops != KTROP_CLEAR) { 519 /* 520 * an operation which requires a file argument. 521 */ 522 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_USERSPACE, uap->fname, td); 523 flags = FREAD | FWRITE | O_NOFOLLOW; 524 mtx_lock(&Giant); 525 error = vn_open(&nd, &flags, 0); 526 if (error) { 527 mtx_unlock(&Giant); 528 td->td_inktrace = 0; 529 return (error); 530 } 531 NDFREE(&nd, NDF_ONLY_PNBUF); 532 vp = nd.ni_vp; 533 VOP_UNLOCK(vp, 0, td); 534 if (vp->v_type != VREG) { 535 (void) vn_close(vp, FREAD|FWRITE, td->td_ucred, td); 536 mtx_unlock(&Giant); 537 td->td_inktrace = 0; 538 return (EACCES); 539 } 540 mtx_unlock(&Giant); 541 } 542 /* 543 * Clear all uses of the tracefile. 544 */ 545 if (ops == KTROP_CLEARFILE) { 546 sx_slock(&allproc_lock); 547 LIST_FOREACH(p, &allproc, p_list) { 548 PROC_LOCK(p); 549 if (p->p_tracevp == vp) { 550 if (ktrcanset(td, p)) { 551 mtx_lock(&ktrace_mtx); 552 cred = p->p_tracecred; 553 p->p_tracecred = NULL; 554 p->p_tracevp = NULL; 555 p->p_traceflag = 0; 556 mtx_unlock(&ktrace_mtx); 557 PROC_UNLOCK(p); 558 mtx_lock(&Giant); 559 (void) vn_close(vp, FREAD|FWRITE, 560 cred, td); 561 mtx_unlock(&Giant); 562 crfree(cred); 563 } else { 564 PROC_UNLOCK(p); 565 error = EPERM; 566 } 567 } else 568 PROC_UNLOCK(p); 569 } 570 sx_sunlock(&allproc_lock); 571 goto done; 572 } 573 /* 574 * do it 575 */ 576 sx_slock(&proctree_lock); 577 if (uap->pid < 0) { 578 /* 579 * by process group 580 */ 581 pg = pgfind(-uap->pid); 582 if (pg == NULL) { 583 sx_sunlock(&proctree_lock); 584 error = ESRCH; 585 goto done; 586 } 587 /* 588 * ktrops() may call vrele(). Lock pg_members 589 * by the proctree_lock rather than pg_mtx. 590 */ 591 PGRP_UNLOCK(pg); 592 LIST_FOREACH(p, &pg->pg_members, p_pglist) 593 if (descend) 594 ret |= ktrsetchildren(td, p, ops, facs, vp); 595 else 596 ret |= ktrops(td, p, ops, facs, vp); 597 } else { 598 /* 599 * by pid 600 */ 601 p = pfind(uap->pid); 602 if (p == NULL) { 603 sx_sunlock(&proctree_lock); 604 error = ESRCH; 605 goto done; 606 } 607 /* 608 * The slock of the proctree lock will keep this process 609 * from going away, so unlocking the proc here is ok. 610 */ 611 PROC_UNLOCK(p); 612 if (descend) 613 ret |= ktrsetchildren(td, p, ops, facs, vp); 614 else 615 ret |= ktrops(td, p, ops, facs, vp); 616 } 617 sx_sunlock(&proctree_lock); 618 if (!ret) 619 error = EPERM; 620 done: 621 if (vp != NULL) { 622 mtx_lock(&Giant); 623 (void) vn_close(vp, FWRITE, td->td_ucred, td); 624 mtx_unlock(&Giant); 625 } 626 td->td_inktrace = 0; 627 return (error); 628 #else /* !KTRACE */ 629 return (ENOSYS); 630 #endif /* KTRACE */ 631 } 632 633 /* 634 * utrace system call 635 * 636 * MPSAFE 637 */ 638 /* ARGSUSED */ 639 int 640 utrace(td, uap) 641 struct thread *td; 642 register struct utrace_args *uap; 643 { 644 645 #ifdef KTRACE 646 struct ktr_request *req; 647 void *cp; 648 int error; 649 650 if (!KTRPOINT(td, KTR_USER)) 651 return (0); 652 if (uap->len > KTR_USER_MAXLEN) 653 return (EINVAL); 654 cp = malloc(uap->len, M_KTRACE, M_WAITOK); 655 error = copyin(uap->addr, cp, uap->len); 656 if (error) { 657 free(cp, M_KTRACE); 658 return (error); 659 } 660 req = ktr_getrequest(KTR_USER); 661 if (req == NULL) { 662 free(cp, M_KTRACE); 663 return (0); 664 } 665 req->ktr_header.ktr_buffer = cp; 666 req->ktr_header.ktr_len = uap->len; 667 ktr_submitrequest(req); 668 return (0); 669 #else /* !KTRACE */ 670 return (ENOSYS); 671 #endif /* KTRACE */ 672 } 673 674 #ifdef KTRACE 675 static int 676 ktrops(td, p, ops, facs, vp) 677 struct thread *td; 678 struct proc *p; 679 int ops, facs; 680 struct vnode *vp; 681 { 682 struct vnode *tracevp = NULL; 683 struct ucred *tracecred = NULL; 684 685 PROC_LOCK(p); 686 if (!ktrcanset(td, p)) { 687 PROC_UNLOCK(p); 688 return (0); 689 } 690 mtx_lock(&ktrace_mtx); 691 if (ops == KTROP_SET) { 692 if (p->p_tracevp != vp) { 693 /* 694 * if trace file already in use, relinquish below 695 */ 696 tracevp = p->p_tracevp; 697 VREF(vp); 698 p->p_tracevp = vp; 699 } 700 if (p->p_tracecred != td->td_ucred) { 701 tracecred = p->p_tracecred; 702 p->p_tracecred = crhold(td->td_ucred); 703 } 704 p->p_traceflag |= facs; 705 if (td->td_ucred->cr_uid == 0) 706 p->p_traceflag |= KTRFAC_ROOT; 707 } else { 708 /* KTROP_CLEAR */ 709 if (((p->p_traceflag &= ~facs) & KTRFAC_MASK) == 0) { 710 /* no more tracing */ 711 p->p_traceflag = 0; 712 tracevp = p->p_tracevp; 713 p->p_tracevp = NULL; 714 tracecred = p->p_tracecred; 715 p->p_tracecred = NULL; 716 } 717 } 718 mtx_unlock(&ktrace_mtx); 719 PROC_UNLOCK(p); 720 if (tracevp != NULL) { 721 mtx_lock(&Giant); 722 vrele(tracevp); 723 mtx_unlock(&Giant); 724 } 725 if (tracecred != NULL) 726 crfree(tracecred); 727 728 return (1); 729 } 730 731 static int 732 ktrsetchildren(td, top, ops, facs, vp) 733 struct thread *td; 734 struct proc *top; 735 int ops, facs; 736 struct vnode *vp; 737 { 738 register struct proc *p; 739 register int ret = 0; 740 741 p = top; 742 sx_assert(&proctree_lock, SX_LOCKED); 743 for (;;) { 744 ret |= ktrops(td, p, ops, facs, vp); 745 /* 746 * If this process has children, descend to them next, 747 * otherwise do any siblings, and if done with this level, 748 * follow back up the tree (but not past top). 749 */ 750 if (!LIST_EMPTY(&p->p_children)) 751 p = LIST_FIRST(&p->p_children); 752 else for (;;) { 753 if (p == top) 754 return (ret); 755 if (LIST_NEXT(p, p_sibling)) { 756 p = LIST_NEXT(p, p_sibling); 757 break; 758 } 759 p = p->p_pptr; 760 } 761 } 762 /*NOTREACHED*/ 763 } 764 765 static void 766 ktr_writerequest(struct ktr_request *req) 767 { 768 struct ktr_header *kth; 769 struct vnode *vp; 770 struct proc *p; 771 struct thread *td; 772 struct ucred *cred; 773 struct uio auio; 774 struct iovec aiov[3]; 775 struct mount *mp; 776 int datalen, buflen, vrele_count; 777 int error; 778 779 vp = req->ktr_vp; 780 /* 781 * If vp is NULL, the vp has been cleared out from under this 782 * request, so just drop it. 783 */ 784 if (vp == NULL) 785 return; 786 kth = &req->ktr_header; 787 datalen = data_lengths[(ushort)kth->ktr_type & ~KTR_DROP]; 788 buflen = kth->ktr_len; 789 cred = req->ktr_cred; 790 td = curthread; 791 auio.uio_iov = &aiov[0]; 792 auio.uio_offset = 0; 793 auio.uio_segflg = UIO_SYSSPACE; 794 auio.uio_rw = UIO_WRITE; 795 aiov[0].iov_base = (caddr_t)kth; 796 aiov[0].iov_len = sizeof(struct ktr_header); 797 auio.uio_resid = sizeof(struct ktr_header); 798 auio.uio_iovcnt = 1; 799 auio.uio_td = td; 800 if (datalen != 0) { 801 aiov[1].iov_base = (caddr_t)&req->ktr_data; 802 aiov[1].iov_len = datalen; 803 auio.uio_resid += datalen; 804 auio.uio_iovcnt++; 805 kth->ktr_len += datalen; 806 } 807 if (buflen != 0) { 808 KASSERT(kth->ktr_buffer != NULL, ("ktrace: nothing to write")); 809 aiov[auio.uio_iovcnt].iov_base = kth->ktr_buffer; 810 aiov[auio.uio_iovcnt].iov_len = buflen; 811 auio.uio_resid += buflen; 812 auio.uio_iovcnt++; 813 } 814 mtx_lock(&Giant); 815 vn_start_write(vp, &mp, V_WAIT); 816 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td); 817 (void)VOP_LEASE(vp, td, cred, LEASE_WRITE); 818 #ifdef MAC 819 error = mac_check_vnode_write(cred, NOCRED, vp); 820 if (error == 0) 821 #endif 822 error = VOP_WRITE(vp, &auio, IO_UNIT | IO_APPEND, cred); 823 VOP_UNLOCK(vp, 0, td); 824 vn_finished_write(mp); 825 mtx_unlock(&Giant); 826 if (!error) 827 return; 828 /* 829 * If error encountered, give up tracing on this vnode. We defer 830 * all the vrele()'s on the vnode until after we are finished walking 831 * the various lists to avoid needlessly holding locks. 832 */ 833 log(LOG_NOTICE, "ktrace write failed, errno %d, tracing stopped\n", 834 error); 835 vrele_count = 0; 836 /* 837 * First, clear this vnode from being used by any processes in the 838 * system. 839 * XXX - If one process gets an EPERM writing to the vnode, should 840 * we really do this? Other processes might have suitable 841 * credentials for the operation. 842 */ 843 cred = NULL; 844 sx_slock(&allproc_lock); 845 LIST_FOREACH(p, &allproc, p_list) { 846 PROC_LOCK(p); 847 if (p->p_tracevp == vp) { 848 mtx_lock(&ktrace_mtx); 849 p->p_tracevp = NULL; 850 p->p_traceflag = 0; 851 cred = p->p_tracecred; 852 p->p_tracecred = NULL; 853 mtx_unlock(&ktrace_mtx); 854 vrele_count++; 855 } 856 PROC_UNLOCK(p); 857 if (cred != NULL) { 858 crfree(cred); 859 cred = NULL; 860 } 861 } 862 sx_sunlock(&allproc_lock); 863 /* 864 * Second, clear this vnode from any pending requests. 865 */ 866 mtx_lock(&ktrace_mtx); 867 STAILQ_FOREACH(req, &ktr_todo, ktr_list) { 868 if (req->ktr_vp == vp) { 869 req->ktr_vp = NULL; 870 vrele_count++; 871 } 872 } 873 mtx_unlock(&ktrace_mtx); 874 mtx_lock(&Giant); 875 while (vrele_count-- > 0) 876 vrele(vp); 877 mtx_unlock(&Giant); 878 } 879 880 /* 881 * Return true if caller has permission to set the ktracing state 882 * of target. Essentially, the target can't possess any 883 * more permissions than the caller. KTRFAC_ROOT signifies that 884 * root previously set the tracing status on the target process, and 885 * so, only root may further change it. 886 */ 887 static int 888 ktrcanset(td, targetp) 889 struct thread *td; 890 struct proc *targetp; 891 { 892 893 PROC_LOCK_ASSERT(targetp, MA_OWNED); 894 if (targetp->p_traceflag & KTRFAC_ROOT && 895 suser_cred(td->td_ucred, PRISON_ROOT)) 896 return (0); 897 898 if (p_candebug(td, targetp) != 0) 899 return (0); 900 901 return (1); 902 } 903 904 #endif /* KTRACE */
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