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 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)kern_ktrace.c 8.2 (Berkeley) 9/23/93 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD: releng/5.3/sys/kern/kern_ktrace.c 136588 2004-10-16 08:43:07Z cvs2svn $"); 34 35 #include "opt_ktrace.h" 36 #include "opt_mac.h" 37 38 #include <sys/param.h> 39 #include <sys/systm.h> 40 #include <sys/fcntl.h> 41 #include <sys/kernel.h> 42 #include <sys/kthread.h> 43 #include <sys/lock.h> 44 #include <sys/mutex.h> 45 #include <sys/mac.h> 46 #include <sys/malloc.h> 47 #include <sys/namei.h> 48 #include <sys/proc.h> 49 #include <sys/unistd.h> 50 #include <sys/vnode.h> 51 #include <sys/ktrace.h> 52 #include <sys/sx.h> 53 #include <sys/sysctl.h> 54 #include <sys/syslog.h> 55 #include <sys/sysproto.h> 56 57 static MALLOC_DEFINE(M_KTRACE, "KTRACE", "KTRACE"); 58 59 #ifdef KTRACE 60 61 #ifndef KTRACE_REQUEST_POOL 62 #define KTRACE_REQUEST_POOL 100 63 #endif 64 65 struct ktr_request { 66 struct ktr_header ktr_header; 67 struct ucred *ktr_cred; 68 struct vnode *ktr_vp; 69 union { 70 struct ktr_syscall ktr_syscall; 71 struct ktr_sysret ktr_sysret; 72 struct ktr_genio ktr_genio; 73 struct ktr_psig ktr_psig; 74 struct ktr_csw ktr_csw; 75 } ktr_data; 76 STAILQ_ENTRY(ktr_request) ktr_list; 77 }; 78 79 static int data_lengths[] = { 80 0, /* none */ 81 offsetof(struct ktr_syscall, ktr_args), /* KTR_SYSCALL */ 82 sizeof(struct ktr_sysret), /* KTR_SYSRET */ 83 0, /* KTR_NAMEI */ 84 sizeof(struct ktr_genio), /* KTR_GENIO */ 85 sizeof(struct ktr_psig), /* KTR_PSIG */ 86 sizeof(struct ktr_csw), /* KTR_CSW */ 87 0 /* KTR_USER */ 88 }; 89 90 static STAILQ_HEAD(, ktr_request) ktr_todo; 91 static STAILQ_HEAD(, ktr_request) ktr_free; 92 93 SYSCTL_NODE(_kern, OID_AUTO, ktrace, CTLFLAG_RD, 0, "KTRACE options"); 94 95 static u_int ktr_requestpool = KTRACE_REQUEST_POOL; 96 TUNABLE_INT("kern.ktrace.request_pool", &ktr_requestpool); 97 98 static u_int ktr_geniosize = PAGE_SIZE; 99 TUNABLE_INT("kern.ktrace.genio_size", &ktr_geniosize); 100 SYSCTL_UINT(_kern_ktrace, OID_AUTO, genio_size, CTLFLAG_RW, &ktr_geniosize, 101 0, "Maximum size of genio event payload"); 102 103 static int print_message = 1; 104 struct mtx ktrace_mtx; 105 static struct cv ktrace_cv; 106 107 static void ktrace_init(void *dummy); 108 static int sysctl_kern_ktrace_request_pool(SYSCTL_HANDLER_ARGS); 109 static u_int ktrace_resize_pool(u_int newsize); 110 static struct ktr_request *ktr_getrequest(int type); 111 static void ktr_submitrequest(struct ktr_request *req); 112 static void ktr_freerequest(struct ktr_request *req); 113 static void ktr_loop(void *dummy); 114 static void ktr_writerequest(struct ktr_request *req); 115 static int ktrcanset(struct thread *,struct proc *); 116 static int ktrsetchildren(struct thread *,struct proc *,int,int,struct vnode *); 117 static int ktrops(struct thread *,struct proc *,int,int,struct vnode *); 118 119 static void 120 ktrace_init(void *dummy) 121 { 122 struct ktr_request *req; 123 int i; 124 125 mtx_init(&ktrace_mtx, "ktrace", NULL, MTX_DEF | MTX_QUIET); 126 cv_init(&ktrace_cv, "ktrace"); 127 STAILQ_INIT(&ktr_todo); 128 STAILQ_INIT(&ktr_free); 129 for (i = 0; i < ktr_requestpool; i++) { 130 req = malloc(sizeof(struct ktr_request), M_KTRACE, M_WAITOK); 131 STAILQ_INSERT_HEAD(&ktr_free, req, ktr_list); 132 } 133 kthread_create(ktr_loop, NULL, NULL, RFHIGHPID, 0, "ktrace"); 134 } 135 SYSINIT(ktrace_init, SI_SUB_KTRACE, SI_ORDER_ANY, ktrace_init, NULL); 136 137 static int 138 sysctl_kern_ktrace_request_pool(SYSCTL_HANDLER_ARGS) 139 { 140 struct thread *td; 141 u_int newsize, oldsize, wantsize; 142 int error; 143 144 /* Handle easy read-only case first to avoid warnings from GCC. */ 145 if (!req->newptr) { 146 mtx_lock(&ktrace_mtx); 147 oldsize = ktr_requestpool; 148 mtx_unlock(&ktrace_mtx); 149 return (SYSCTL_OUT(req, &oldsize, sizeof(u_int))); 150 } 151 152 error = SYSCTL_IN(req, &wantsize, sizeof(u_int)); 153 if (error) 154 return (error); 155 td = curthread; 156 td->td_pflags |= TDP_INKTRACE; 157 mtx_lock(&ktrace_mtx); 158 oldsize = ktr_requestpool; 159 newsize = ktrace_resize_pool(wantsize); 160 mtx_unlock(&ktrace_mtx); 161 td->td_pflags &= ~TDP_INKTRACE; 162 error = SYSCTL_OUT(req, &oldsize, sizeof(u_int)); 163 if (error) 164 return (error); 165 if (wantsize > oldsize && newsize < wantsize) 166 return (ENOSPC); 167 return (0); 168 } 169 SYSCTL_PROC(_kern_ktrace, OID_AUTO, request_pool, CTLTYPE_UINT|CTLFLAG_RW, 170 &ktr_requestpool, 0, sysctl_kern_ktrace_request_pool, "IU", ""); 171 172 static u_int 173 ktrace_resize_pool(u_int newsize) 174 { 175 struct ktr_request *req; 176 int bound; 177 178 mtx_assert(&ktrace_mtx, MA_OWNED); 179 print_message = 1; 180 bound = newsize - ktr_requestpool; 181 if (bound == 0) 182 return (ktr_requestpool); 183 if (bound < 0) 184 /* Shrink pool down to newsize if possible. */ 185 while (bound++ < 0) { 186 req = STAILQ_FIRST(&ktr_free); 187 if (req == NULL) 188 return (ktr_requestpool); 189 STAILQ_REMOVE_HEAD(&ktr_free, ktr_list); 190 ktr_requestpool--; 191 mtx_unlock(&ktrace_mtx); 192 free(req, M_KTRACE); 193 mtx_lock(&ktrace_mtx); 194 } 195 else 196 /* Grow pool up to newsize. */ 197 while (bound-- > 0) { 198 mtx_unlock(&ktrace_mtx); 199 req = malloc(sizeof(struct ktr_request), M_KTRACE, 200 M_WAITOK); 201 mtx_lock(&ktrace_mtx); 202 STAILQ_INSERT_HEAD(&ktr_free, req, ktr_list); 203 ktr_requestpool++; 204 } 205 return (ktr_requestpool); 206 } 207 208 static struct ktr_request * 209 ktr_getrequest(int type) 210 { 211 struct ktr_request *req; 212 struct thread *td = curthread; 213 struct proc *p = td->td_proc; 214 int pm; 215 216 td->td_pflags |= TDP_INKTRACE; 217 mtx_lock(&ktrace_mtx); 218 if (!KTRCHECK(td, type)) { 219 mtx_unlock(&ktrace_mtx); 220 td->td_pflags &= ~TDP_INKTRACE; 221 return (NULL); 222 } 223 req = STAILQ_FIRST(&ktr_free); 224 if (req != NULL) { 225 STAILQ_REMOVE_HEAD(&ktr_free, ktr_list); 226 req->ktr_header.ktr_type = type; 227 if (p->p_traceflag & KTRFAC_DROP) { 228 req->ktr_header.ktr_type |= KTR_DROP; 229 p->p_traceflag &= ~KTRFAC_DROP; 230 } 231 KASSERT(p->p_tracevp != NULL, ("ktrace: no trace vnode")); 232 KASSERT(p->p_tracecred != NULL, ("ktrace: no trace cred")); 233 req->ktr_vp = p->p_tracevp; 234 VREF(p->p_tracevp); 235 req->ktr_cred = crhold(p->p_tracecred); 236 mtx_unlock(&ktrace_mtx); 237 microtime(&req->ktr_header.ktr_time); 238 req->ktr_header.ktr_pid = p->p_pid; 239 bcopy(p->p_comm, req->ktr_header.ktr_comm, MAXCOMLEN + 1); 240 req->ktr_header.ktr_buffer = NULL; 241 req->ktr_header.ktr_len = 0; 242 } else { 243 p->p_traceflag |= KTRFAC_DROP; 244 pm = print_message; 245 print_message = 0; 246 mtx_unlock(&ktrace_mtx); 247 if (pm) 248 printf("Out of ktrace request objects.\n"); 249 td->td_pflags &= ~TDP_INKTRACE; 250 } 251 return (req); 252 } 253 254 static void 255 ktr_submitrequest(struct ktr_request *req) 256 { 257 258 mtx_lock(&ktrace_mtx); 259 STAILQ_INSERT_TAIL(&ktr_todo, req, ktr_list); 260 cv_signal(&ktrace_cv); 261 mtx_unlock(&ktrace_mtx); 262 curthread->td_pflags &= ~TDP_INKTRACE; 263 } 264 265 static void 266 ktr_freerequest(struct ktr_request *req) 267 { 268 269 crfree(req->ktr_cred); 270 if (req->ktr_vp != NULL) { 271 mtx_lock(&Giant); 272 vrele(req->ktr_vp); 273 mtx_unlock(&Giant); 274 } 275 if (req->ktr_header.ktr_buffer != NULL) 276 free(req->ktr_header.ktr_buffer, M_KTRACE); 277 mtx_lock(&ktrace_mtx); 278 STAILQ_INSERT_HEAD(&ktr_free, req, ktr_list); 279 mtx_unlock(&ktrace_mtx); 280 } 281 282 static void 283 ktr_loop(void *dummy) 284 { 285 struct ktr_request *req; 286 struct thread *td; 287 struct ucred *cred; 288 289 /* Only cache these values once. */ 290 td = curthread; 291 cred = td->td_ucred; 292 for (;;) { 293 mtx_lock(&ktrace_mtx); 294 while (STAILQ_EMPTY(&ktr_todo)) 295 cv_wait(&ktrace_cv, &ktrace_mtx); 296 req = STAILQ_FIRST(&ktr_todo); 297 STAILQ_REMOVE_HEAD(&ktr_todo, ktr_list); 298 KASSERT(req != NULL, ("got a NULL request")); 299 mtx_unlock(&ktrace_mtx); 300 /* 301 * It is not enough just to pass the cached cred 302 * to the VOP's in ktr_writerequest(). Some VFS 303 * operations use curthread->td_ucred, so we need 304 * to modify our thread's credentials as well. 305 * Evil. 306 */ 307 td->td_ucred = req->ktr_cred; 308 ktr_writerequest(req); 309 td->td_ucred = cred; 310 ktr_freerequest(req); 311 } 312 } 313 314 /* 315 * MPSAFE 316 */ 317 void 318 ktrsyscall(code, narg, args) 319 int code, narg; 320 register_t args[]; 321 { 322 struct ktr_request *req; 323 struct ktr_syscall *ktp; 324 size_t buflen; 325 char *buf = NULL; 326 327 buflen = sizeof(register_t) * narg; 328 if (buflen > 0) { 329 buf = malloc(buflen, M_KTRACE, M_WAITOK); 330 bcopy(args, buf, buflen); 331 } 332 req = ktr_getrequest(KTR_SYSCALL); 333 if (req == NULL) { 334 if (buf != NULL) 335 free(buf, M_KTRACE); 336 return; 337 } 338 ktp = &req->ktr_data.ktr_syscall; 339 ktp->ktr_code = code; 340 ktp->ktr_narg = narg; 341 if (buflen > 0) { 342 req->ktr_header.ktr_len = buflen; 343 req->ktr_header.ktr_buffer = buf; 344 } 345 ktr_submitrequest(req); 346 } 347 348 /* 349 * MPSAFE 350 */ 351 void 352 ktrsysret(code, error, retval) 353 int code, error; 354 register_t retval; 355 { 356 struct ktr_request *req; 357 struct ktr_sysret *ktp; 358 359 req = ktr_getrequest(KTR_SYSRET); 360 if (req == NULL) 361 return; 362 ktp = &req->ktr_data.ktr_sysret; 363 ktp->ktr_code = code; 364 ktp->ktr_error = error; 365 ktp->ktr_retval = retval; /* what about val2 ? */ 366 ktr_submitrequest(req); 367 } 368 369 void 370 ktrnamei(path) 371 char *path; 372 { 373 struct ktr_request *req; 374 int namelen; 375 char *buf = NULL; 376 377 namelen = strlen(path); 378 if (namelen > 0) { 379 buf = malloc(namelen, M_KTRACE, M_WAITOK); 380 bcopy(path, buf, namelen); 381 } 382 req = ktr_getrequest(KTR_NAMEI); 383 if (req == NULL) { 384 if (buf != NULL) 385 free(buf, M_KTRACE); 386 return; 387 } 388 if (namelen > 0) { 389 req->ktr_header.ktr_len = namelen; 390 req->ktr_header.ktr_buffer = buf; 391 } 392 ktr_submitrequest(req); 393 } 394 395 /* 396 * Since the uio may not stay valid, we can not hand off this request to 397 * the thread and need to process it synchronously. However, we wish to 398 * keep the relative order of records in a trace file correct, so we 399 * do put this request on the queue (if it isn't empty) and then block. 400 * The ktrace thread waks us back up when it is time for this event to 401 * be posted and blocks until we have completed writing out the event 402 * and woken it back up. 403 */ 404 void 405 ktrgenio(fd, rw, uio, error) 406 int fd; 407 enum uio_rw rw; 408 struct uio *uio; 409 int error; 410 { 411 struct ktr_request *req; 412 struct ktr_genio *ktg; 413 int datalen; 414 char *buf; 415 416 if (error) { 417 free(uio, M_IOV); 418 return; 419 } 420 uio->uio_offset = 0; 421 uio->uio_rw = UIO_WRITE; 422 datalen = imin(uio->uio_resid, ktr_geniosize); 423 buf = malloc(datalen, M_KTRACE, M_WAITOK); 424 error = uiomove(buf, datalen, uio); 425 free(uio, M_IOV); 426 if (error) { 427 free(buf, M_KTRACE); 428 return; 429 } 430 req = ktr_getrequest(KTR_GENIO); 431 if (req == NULL) { 432 free(buf, M_KTRACE); 433 return; 434 } 435 ktg = &req->ktr_data.ktr_genio; 436 ktg->ktr_fd = fd; 437 ktg->ktr_rw = rw; 438 req->ktr_header.ktr_len = datalen; 439 req->ktr_header.ktr_buffer = buf; 440 ktr_submitrequest(req); 441 } 442 443 void 444 ktrpsig(sig, action, mask, code) 445 int sig; 446 sig_t action; 447 sigset_t *mask; 448 int code; 449 { 450 struct ktr_request *req; 451 struct ktr_psig *kp; 452 453 req = ktr_getrequest(KTR_PSIG); 454 if (req == NULL) 455 return; 456 kp = &req->ktr_data.ktr_psig; 457 kp->signo = (char)sig; 458 kp->action = action; 459 kp->mask = *mask; 460 kp->code = code; 461 ktr_submitrequest(req); 462 } 463 464 void 465 ktrcsw(out, user) 466 int out, user; 467 { 468 struct ktr_request *req; 469 struct ktr_csw *kc; 470 471 req = ktr_getrequest(KTR_CSW); 472 if (req == NULL) 473 return; 474 kc = &req->ktr_data.ktr_csw; 475 kc->out = out; 476 kc->user = user; 477 ktr_submitrequest(req); 478 } 479 #endif /* KTRACE */ 480 481 /* Interface and common routines */ 482 483 /* 484 * ktrace system call 485 * 486 * MPSAFE 487 */ 488 #ifndef _SYS_SYSPROTO_H_ 489 struct ktrace_args { 490 char *fname; 491 int ops; 492 int facs; 493 int pid; 494 }; 495 #endif 496 /* ARGSUSED */ 497 int 498 ktrace(td, uap) 499 struct thread *td; 500 register struct ktrace_args *uap; 501 { 502 #ifdef KTRACE 503 register struct vnode *vp = NULL; 504 register struct proc *p; 505 struct pgrp *pg; 506 int facs = uap->facs & ~KTRFAC_ROOT; 507 int ops = KTROP(uap->ops); 508 int descend = uap->ops & KTRFLAG_DESCEND; 509 int ret = 0; 510 int flags, error = 0; 511 struct nameidata nd; 512 struct ucred *cred; 513 514 /* 515 * Need something to (un)trace. 516 */ 517 if (ops != KTROP_CLEARFILE && facs == 0) 518 return (EINVAL); 519 520 td->td_pflags |= TDP_INKTRACE; 521 if (ops != KTROP_CLEAR) { 522 /* 523 * an operation which requires a file argument. 524 */ 525 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_USERSPACE, uap->fname, td); 526 flags = FREAD | FWRITE | O_NOFOLLOW; 527 mtx_lock(&Giant); 528 error = vn_open(&nd, &flags, 0, -1); 529 if (error) { 530 mtx_unlock(&Giant); 531 td->td_pflags &= ~TDP_INKTRACE; 532 return (error); 533 } 534 NDFREE(&nd, NDF_ONLY_PNBUF); 535 vp = nd.ni_vp; 536 VOP_UNLOCK(vp, 0, td); 537 if (vp->v_type != VREG) { 538 (void) vn_close(vp, FREAD|FWRITE, td->td_ucred, td); 539 mtx_unlock(&Giant); 540 td->td_pflags &= ~TDP_INKTRACE; 541 return (EACCES); 542 } 543 mtx_unlock(&Giant); 544 } 545 /* 546 * Clear all uses of the tracefile. 547 */ 548 if (ops == KTROP_CLEARFILE) { 549 sx_slock(&allproc_lock); 550 LIST_FOREACH(p, &allproc, p_list) { 551 PROC_LOCK(p); 552 if (p->p_tracevp == vp) { 553 if (ktrcanset(td, p)) { 554 mtx_lock(&ktrace_mtx); 555 cred = p->p_tracecred; 556 p->p_tracecred = NULL; 557 p->p_tracevp = NULL; 558 p->p_traceflag = 0; 559 mtx_unlock(&ktrace_mtx); 560 PROC_UNLOCK(p); 561 mtx_lock(&Giant); 562 (void) vn_close(vp, FREAD|FWRITE, 563 cred, td); 564 mtx_unlock(&Giant); 565 crfree(cred); 566 } else { 567 PROC_UNLOCK(p); 568 error = EPERM; 569 } 570 } else 571 PROC_UNLOCK(p); 572 } 573 sx_sunlock(&allproc_lock); 574 goto done; 575 } 576 /* 577 * do it 578 */ 579 sx_slock(&proctree_lock); 580 if (uap->pid < 0) { 581 /* 582 * by process group 583 */ 584 pg = pgfind(-uap->pid); 585 if (pg == NULL) { 586 sx_sunlock(&proctree_lock); 587 error = ESRCH; 588 goto done; 589 } 590 /* 591 * ktrops() may call vrele(). Lock pg_members 592 * by the proctree_lock rather than pg_mtx. 593 */ 594 PGRP_UNLOCK(pg); 595 LIST_FOREACH(p, &pg->pg_members, p_pglist) 596 if (descend) 597 ret |= ktrsetchildren(td, p, ops, facs, vp); 598 else 599 ret |= ktrops(td, p, ops, facs, vp); 600 } else { 601 /* 602 * by pid 603 */ 604 p = pfind(uap->pid); 605 if (p == NULL) { 606 sx_sunlock(&proctree_lock); 607 error = ESRCH; 608 goto done; 609 } 610 /* 611 * The slock of the proctree lock will keep this process 612 * from going away, so unlocking the proc here is ok. 613 */ 614 PROC_UNLOCK(p); 615 if (descend) 616 ret |= ktrsetchildren(td, p, ops, facs, vp); 617 else 618 ret |= ktrops(td, p, ops, facs, vp); 619 } 620 sx_sunlock(&proctree_lock); 621 if (!ret) 622 error = EPERM; 623 done: 624 if (vp != NULL) { 625 mtx_lock(&Giant); 626 (void) vn_close(vp, FWRITE, td->td_ucred, td); 627 mtx_unlock(&Giant); 628 } 629 td->td_pflags &= ~TDP_INKTRACE; 630 return (error); 631 #else /* !KTRACE */ 632 return (ENOSYS); 633 #endif /* KTRACE */ 634 } 635 636 /* 637 * utrace system call 638 * 639 * MPSAFE 640 */ 641 /* ARGSUSED */ 642 int 643 utrace(td, uap) 644 struct thread *td; 645 register struct utrace_args *uap; 646 { 647 648 #ifdef KTRACE 649 struct ktr_request *req; 650 void *cp; 651 int error; 652 653 if (!KTRPOINT(td, KTR_USER)) 654 return (0); 655 if (uap->len > KTR_USER_MAXLEN) 656 return (EINVAL); 657 cp = malloc(uap->len, M_KTRACE, M_WAITOK); 658 error = copyin(uap->addr, cp, uap->len); 659 if (error) { 660 free(cp, M_KTRACE); 661 return (error); 662 } 663 req = ktr_getrequest(KTR_USER); 664 if (req == NULL) { 665 free(cp, M_KTRACE); 666 return (ENOMEM); 667 } 668 req->ktr_header.ktr_buffer = cp; 669 req->ktr_header.ktr_len = uap->len; 670 ktr_submitrequest(req); 671 return (0); 672 #else /* !KTRACE */ 673 return (ENOSYS); 674 #endif /* KTRACE */ 675 } 676 677 #ifdef KTRACE 678 static int 679 ktrops(td, p, ops, facs, vp) 680 struct thread *td; 681 struct proc *p; 682 int ops, facs; 683 struct vnode *vp; 684 { 685 struct vnode *tracevp = NULL; 686 struct ucred *tracecred = NULL; 687 688 PROC_LOCK(p); 689 if (!ktrcanset(td, p)) { 690 PROC_UNLOCK(p); 691 return (0); 692 } 693 mtx_lock(&ktrace_mtx); 694 if (ops == KTROP_SET) { 695 if (p->p_tracevp != vp) { 696 /* 697 * if trace file already in use, relinquish below 698 */ 699 tracevp = p->p_tracevp; 700 VREF(vp); 701 p->p_tracevp = vp; 702 } 703 if (p->p_tracecred != td->td_ucred) { 704 tracecred = p->p_tracecred; 705 p->p_tracecred = crhold(td->td_ucred); 706 } 707 p->p_traceflag |= facs; 708 if (td->td_ucred->cr_uid == 0) 709 p->p_traceflag |= KTRFAC_ROOT; 710 } else { 711 /* KTROP_CLEAR */ 712 if (((p->p_traceflag &= ~facs) & KTRFAC_MASK) == 0) { 713 /* no more tracing */ 714 p->p_traceflag = 0; 715 tracevp = p->p_tracevp; 716 p->p_tracevp = NULL; 717 tracecred = p->p_tracecred; 718 p->p_tracecred = NULL; 719 } 720 } 721 mtx_unlock(&ktrace_mtx); 722 PROC_UNLOCK(p); 723 if (tracevp != NULL) { 724 mtx_lock(&Giant); 725 vrele(tracevp); 726 mtx_unlock(&Giant); 727 } 728 if (tracecred != NULL) 729 crfree(tracecred); 730 731 return (1); 732 } 733 734 static int 735 ktrsetchildren(td, top, ops, facs, vp) 736 struct thread *td; 737 struct proc *top; 738 int ops, facs; 739 struct vnode *vp; 740 { 741 register struct proc *p; 742 register int ret = 0; 743 744 p = top; 745 sx_assert(&proctree_lock, SX_LOCKED); 746 for (;;) { 747 ret |= ktrops(td, p, ops, facs, vp); 748 /* 749 * If this process has children, descend to them next, 750 * otherwise do any siblings, and if done with this level, 751 * follow back up the tree (but not past top). 752 */ 753 if (!LIST_EMPTY(&p->p_children)) 754 p = LIST_FIRST(&p->p_children); 755 else for (;;) { 756 if (p == top) 757 return (ret); 758 if (LIST_NEXT(p, p_sibling)) { 759 p = LIST_NEXT(p, p_sibling); 760 break; 761 } 762 p = p->p_pptr; 763 } 764 } 765 /*NOTREACHED*/ 766 } 767 768 static void 769 ktr_writerequest(struct ktr_request *req) 770 { 771 struct ktr_header *kth; 772 struct vnode *vp; 773 struct proc *p; 774 struct thread *td; 775 struct ucred *cred; 776 struct uio auio; 777 struct iovec aiov[3]; 778 struct mount *mp; 779 int datalen, buflen, vrele_count; 780 int error; 781 782 vp = req->ktr_vp; 783 /* 784 * If vp is NULL, the vp has been cleared out from under this 785 * request, so just drop it. 786 */ 787 if (vp == NULL) 788 return; 789 kth = &req->ktr_header; 790 datalen = data_lengths[(u_short)kth->ktr_type & ~KTR_DROP]; 791 buflen = kth->ktr_len; 792 cred = req->ktr_cred; 793 td = curthread; 794 auio.uio_iov = &aiov[0]; 795 auio.uio_offset = 0; 796 auio.uio_segflg = UIO_SYSSPACE; 797 auio.uio_rw = UIO_WRITE; 798 aiov[0].iov_base = (caddr_t)kth; 799 aiov[0].iov_len = sizeof(struct ktr_header); 800 auio.uio_resid = sizeof(struct ktr_header); 801 auio.uio_iovcnt = 1; 802 auio.uio_td = td; 803 if (datalen != 0) { 804 aiov[1].iov_base = (caddr_t)&req->ktr_data; 805 aiov[1].iov_len = datalen; 806 auio.uio_resid += datalen; 807 auio.uio_iovcnt++; 808 kth->ktr_len += datalen; 809 } 810 if (buflen != 0) { 811 KASSERT(kth->ktr_buffer != NULL, ("ktrace: nothing to write")); 812 aiov[auio.uio_iovcnt].iov_base = kth->ktr_buffer; 813 aiov[auio.uio_iovcnt].iov_len = buflen; 814 auio.uio_resid += buflen; 815 auio.uio_iovcnt++; 816 } 817 mtx_lock(&Giant); 818 vn_start_write(vp, &mp, V_WAIT); 819 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td); 820 (void)VOP_LEASE(vp, td, cred, LEASE_WRITE); 821 #ifdef MAC 822 error = mac_check_vnode_write(cred, NOCRED, vp); 823 if (error == 0) 824 #endif 825 error = VOP_WRITE(vp, &auio, IO_UNIT | IO_APPEND, cred); 826 VOP_UNLOCK(vp, 0, td); 827 vn_finished_write(mp); 828 mtx_unlock(&Giant); 829 if (!error) 830 return; 831 /* 832 * If error encountered, give up tracing on this vnode. We defer 833 * all the vrele()'s on the vnode until after we are finished walking 834 * the various lists to avoid needlessly holding locks. 835 */ 836 log(LOG_NOTICE, "ktrace write failed, errno %d, tracing stopped\n", 837 error); 838 vrele_count = 0; 839 /* 840 * First, clear this vnode from being used by any processes in the 841 * system. 842 * XXX - If one process gets an EPERM writing to the vnode, should 843 * we really do this? Other processes might have suitable 844 * credentials for the operation. 845 */ 846 cred = NULL; 847 sx_slock(&allproc_lock); 848 LIST_FOREACH(p, &allproc, p_list) { 849 PROC_LOCK(p); 850 if (p->p_tracevp == vp) { 851 mtx_lock(&ktrace_mtx); 852 p->p_tracevp = NULL; 853 p->p_traceflag = 0; 854 cred = p->p_tracecred; 855 p->p_tracecred = NULL; 856 mtx_unlock(&ktrace_mtx); 857 vrele_count++; 858 } 859 PROC_UNLOCK(p); 860 if (cred != NULL) { 861 crfree(cred); 862 cred = NULL; 863 } 864 } 865 sx_sunlock(&allproc_lock); 866 /* 867 * Second, clear this vnode from any pending requests. 868 */ 869 mtx_lock(&ktrace_mtx); 870 STAILQ_FOREACH(req, &ktr_todo, ktr_list) { 871 if (req->ktr_vp == vp) { 872 req->ktr_vp = NULL; 873 vrele_count++; 874 } 875 } 876 mtx_unlock(&ktrace_mtx); 877 mtx_lock(&Giant); 878 while (vrele_count-- > 0) 879 vrele(vp); 880 mtx_unlock(&Giant); 881 } 882 883 /* 884 * Return true if caller has permission to set the ktracing state 885 * of target. Essentially, the target can't possess any 886 * more permissions than the caller. KTRFAC_ROOT signifies that 887 * root previously set the tracing status on the target process, and 888 * so, only root may further change it. 889 */ 890 static int 891 ktrcanset(td, targetp) 892 struct thread *td; 893 struct proc *targetp; 894 { 895 896 PROC_LOCK_ASSERT(targetp, MA_OWNED); 897 if (targetp->p_traceflag & KTRFAC_ROOT && 898 suser_cred(td->td_ucred, SUSER_ALLOWJAIL)) 899 return (0); 900 901 if (p_candebug(td, targetp) != 0) 902 return (0); 903 904 return (1); 905 } 906 907 #endif /* KTRACE */
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