1 /* 2 * Copyright (c) 1994, Sean Eric Fagan 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 Sean Eric Fagan. 16 * 4. The name of the author may not be used to endorse or promote products 17 * derived from this software without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include <sys/param.h> 36 #include <sys/systm.h> 37 #include <sys/lock.h> 38 #include <sys/mutex.h> 39 #include <sys/syscallsubr.h> 40 #include <sys/sysproto.h> 41 #include <sys/proc.h> 42 #include <sys/vnode.h> 43 #include <sys/ptrace.h> 44 #include <sys/sx.h> 45 #include <sys/user.h> 46 47 #include <machine/reg.h> 48 49 #include <vm/vm.h> 50 #include <vm/pmap.h> 51 #include <vm/vm_extern.h> 52 #include <vm/vm_map.h> 53 #include <vm/vm_kern.h> 54 #include <vm/vm_object.h> 55 #include <vm/vm_page.h> 56 57 /* 58 * Functions implemented using PROC_ACTION(): 59 * 60 * proc_read_regs(proc, regs) 61 * Get the current user-visible register set from the process 62 * and copy it into the regs structure (<machine/reg.h>). 63 * The process is stopped at the time read_regs is called. 64 * 65 * proc_write_regs(proc, regs) 66 * Update the current register set from the passed in regs 67 * structure. Take care to avoid clobbering special CPU 68 * registers or privileged bits in the PSL. 69 * Depending on the architecture this may have fix-up work to do, 70 * especially if the IAR or PCW are modified. 71 * The process is stopped at the time write_regs is called. 72 * 73 * proc_read_fpregs, proc_write_fpregs 74 * deal with the floating point register set, otherwise as above. 75 * 76 * proc_read_dbregs, proc_write_dbregs 77 * deal with the processor debug register set, otherwise as above. 78 * 79 * proc_sstep(proc) 80 * Arrange for the process to trap after executing a single instruction. 81 */ 82 83 #define PROC_ACTION(action) do { \ 84 int error; \ 85 \ 86 PROC_LOCK_ASSERT(td->td_proc, MA_OWNED); \ 87 if ((td->td_proc->p_sflag & PS_INMEM) == 0) \ 88 error = EIO; \ 89 else \ 90 error = (action); \ 91 return (error); \ 92 } while(0) 93 94 int 95 proc_read_regs(struct thread *td, struct reg *regs) 96 { 97 98 PROC_ACTION(fill_regs(td, regs)); 99 } 100 101 int 102 proc_write_regs(struct thread *td, struct reg *regs) 103 { 104 105 PROC_ACTION(set_regs(td, regs)); 106 } 107 108 int 109 proc_read_dbregs(struct thread *td, struct dbreg *dbregs) 110 { 111 112 PROC_ACTION(fill_dbregs(td, dbregs)); 113 } 114 115 int 116 proc_write_dbregs(struct thread *td, struct dbreg *dbregs) 117 { 118 119 PROC_ACTION(set_dbregs(td, dbregs)); 120 } 121 122 /* 123 * Ptrace doesn't support fpregs at all, and there are no security holes 124 * or translations for fpregs, so we can just copy them. 125 */ 126 int 127 proc_read_fpregs(struct thread *td, struct fpreg *fpregs) 128 { 129 130 PROC_ACTION(fill_fpregs(td, fpregs)); 131 } 132 133 int 134 proc_write_fpregs(struct thread *td, struct fpreg *fpregs) 135 { 136 137 PROC_ACTION(set_fpregs(td, fpregs)); 138 } 139 140 int 141 proc_sstep(struct thread *td) 142 { 143 144 PROC_ACTION(ptrace_single_step(td)); 145 } 146 147 int 148 proc_rwmem(struct proc *p, struct uio *uio) 149 { 150 struct vmspace *vm; 151 vm_map_t map; 152 vm_object_t backing_object, object = NULL; 153 vm_offset_t pageno = 0; /* page number */ 154 vm_prot_t reqprot; 155 vm_offset_t kva; 156 int error, writing; 157 158 GIANT_REQUIRED; 159 160 /* 161 * if the vmspace is in the midst of being deallocated or the 162 * process is exiting, don't try to grab anything. The page table 163 * usage in that process can be messed up. 164 */ 165 vm = p->p_vmspace; 166 if ((p->p_flag & P_WEXIT)) 167 return (EFAULT); 168 if (vm->vm_refcnt < 1) 169 return (EFAULT); 170 ++vm->vm_refcnt; 171 /* 172 * The map we want... 173 */ 174 map = &vm->vm_map; 175 176 writing = uio->uio_rw == UIO_WRITE; 177 reqprot = writing ? (VM_PROT_WRITE | VM_PROT_OVERRIDE_WRITE) : 178 VM_PROT_READ; 179 180 kva = kmem_alloc_nofault(kernel_map, PAGE_SIZE); 181 182 /* 183 * Only map in one page at a time. We don't have to, but it 184 * makes things easier. This way is trivial - right? 185 */ 186 do { 187 vm_map_t tmap; 188 vm_offset_t uva; 189 int page_offset; /* offset into page */ 190 vm_map_entry_t out_entry; 191 vm_prot_t out_prot; 192 boolean_t wired; 193 vm_pindex_t pindex; 194 u_int len; 195 vm_page_t m; 196 197 object = NULL; 198 199 uva = (vm_offset_t)uio->uio_offset; 200 201 /* 202 * Get the page number of this segment. 203 */ 204 pageno = trunc_page(uva); 205 page_offset = uva - pageno; 206 207 /* 208 * How many bytes to copy 209 */ 210 len = min(PAGE_SIZE - page_offset, uio->uio_resid); 211 212 /* 213 * Fault the page on behalf of the process 214 */ 215 error = vm_fault(map, pageno, reqprot, VM_FAULT_NORMAL); 216 if (error) { 217 error = EFAULT; 218 break; 219 } 220 221 /* 222 * Now we need to get the page. out_entry, out_prot, wired, 223 * and single_use aren't used. One would think the vm code 224 * would be a *bit* nicer... We use tmap because 225 * vm_map_lookup() can change the map argument. 226 */ 227 tmap = map; 228 error = vm_map_lookup(&tmap, pageno, reqprot, &out_entry, 229 &object, &pindex, &out_prot, &wired); 230 if (error) { 231 error = EFAULT; 232 break; 233 } 234 VM_OBJECT_LOCK(object); 235 while ((m = vm_page_lookup(object, pindex)) == NULL && 236 !writing && 237 (backing_object = object->backing_object) != NULL) { 238 /* 239 * Allow fallback to backing objects if we are reading. 240 */ 241 VM_OBJECT_LOCK(backing_object); 242 pindex += OFF_TO_IDX(object->backing_object_offset); 243 VM_OBJECT_UNLOCK(object); 244 object = backing_object; 245 } 246 VM_OBJECT_UNLOCK(object); 247 if (m == NULL) { 248 vm_map_lookup_done(tmap, out_entry); 249 error = EFAULT; 250 break; 251 } 252 253 /* 254 * Hold the page in memory. 255 */ 256 vm_page_lock_queues(); 257 vm_page_hold(m); 258 vm_page_unlock_queues(); 259 260 /* 261 * We're done with tmap now. 262 */ 263 vm_map_lookup_done(tmap, out_entry); 264 265 pmap_qenter(kva, &m, 1); 266 267 /* 268 * Now do the i/o move. 269 */ 270 error = uiomove((caddr_t)(kva + page_offset), len, uio); 271 272 pmap_qremove(kva, 1); 273 274 /* 275 * Release the page. 276 */ 277 vm_page_lock_queues(); 278 vm_page_unhold(m); 279 vm_page_unlock_queues(); 280 281 } while (error == 0 && uio->uio_resid > 0); 282 283 kmem_free(kernel_map, kva, PAGE_SIZE); 284 vmspace_free(vm); 285 return (error); 286 } 287 288 /* 289 * Process debugging system call. 290 */ 291 #ifndef _SYS_SYSPROTO_H_ 292 struct ptrace_args { 293 int req; 294 pid_t pid; 295 caddr_t addr; 296 int data; 297 }; 298 #endif 299 300 /* 301 * MPSAFE 302 */ 303 int 304 ptrace(struct thread *td, struct ptrace_args *uap) 305 { 306 /* 307 * XXX this obfuscation is to reduce stack usage, but the register 308 * structs may be too large to put on the stack anyway. 309 */ 310 union { 311 struct ptrace_io_desc piod; 312 struct dbreg dbreg; 313 struct fpreg fpreg; 314 struct reg reg; 315 } r; 316 void *addr; 317 int error = 0; 318 319 addr = &r; 320 switch (uap->req) { 321 case PT_GETREGS: 322 case PT_GETFPREGS: 323 case PT_GETDBREGS: 324 break; 325 case PT_SETREGS: 326 error = copyin(uap->addr, &r.reg, sizeof r.reg); 327 break; 328 case PT_SETFPREGS: 329 error = copyin(uap->addr, &r.fpreg, sizeof r.fpreg); 330 break; 331 case PT_SETDBREGS: 332 error = copyin(uap->addr, &r.dbreg, sizeof r.dbreg); 333 break; 334 case PT_IO: 335 error = copyin(uap->addr, &r.piod, sizeof r.piod); 336 break; 337 default: 338 addr = uap->addr; 339 break; 340 } 341 if (error) 342 return (error); 343 344 error = kern_ptrace(td, uap->req, uap->pid, addr, uap->data); 345 if (error) 346 return (error); 347 348 switch (uap->req) { 349 case PT_IO: 350 (void)copyout(&r.piod, uap->addr, sizeof r.piod); 351 break; 352 case PT_GETREGS: 353 error = copyout(&r.reg, uap->addr, sizeof r.reg); 354 break; 355 case PT_GETFPREGS: 356 error = copyout(&r.fpreg, uap->addr, sizeof r.fpreg); 357 break; 358 case PT_GETDBREGS: 359 error = copyout(&r.dbreg, uap->addr, sizeof r.dbreg); 360 break; 361 } 362 363 return (error); 364 } 365 366 int 367 kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data) 368 { 369 struct iovec iov; 370 struct uio uio; 371 struct proc *curp, *p, *pp; 372 struct thread *td2; 373 struct ptrace_io_desc *piod; 374 int error, write, tmp; 375 int proctree_locked = 0; 376 377 curp = td->td_proc; 378 379 /* Lock proctree before locking the process. */ 380 switch (req) { 381 case PT_TRACE_ME: 382 case PT_ATTACH: 383 case PT_STEP: 384 case PT_CONTINUE: 385 case PT_DETACH: 386 sx_xlock(&proctree_lock); 387 proctree_locked = 1; 388 break; 389 default: 390 break; 391 } 392 393 write = 0; 394 if (req == PT_TRACE_ME) { 395 p = td->td_proc; 396 PROC_LOCK(p); 397 } else { 398 if ((p = pfind(pid)) == NULL) { 399 if (proctree_locked) 400 sx_xunlock(&proctree_lock); 401 return (ESRCH); 402 } 403 } 404 if ((error = p_cansee(td, p)) != 0) 405 goto fail; 406 407 if ((error = p_candebug(td, p)) != 0) 408 goto fail; 409 410 /* 411 * System processes can't be debugged. 412 */ 413 if ((p->p_flag & P_SYSTEM) != 0) { 414 error = EINVAL; 415 goto fail; 416 } 417 418 /* 419 * Permissions check 420 */ 421 switch (req) { 422 case PT_TRACE_ME: 423 /* Always legal. */ 424 break; 425 426 case PT_ATTACH: 427 /* Self */ 428 if (p->p_pid == td->td_proc->p_pid) { 429 error = EINVAL; 430 goto fail; 431 } 432 433 /* Already traced */ 434 if (p->p_flag & P_TRACED) { 435 error = EBUSY; 436 goto fail; 437 } 438 439 /* Can't trace an ancestor if you're being traced. */ 440 if (curp->p_flag & P_TRACED) { 441 for (pp = curp->p_pptr; pp != NULL; pp = pp->p_pptr) { 442 if (pp == p) { 443 error = EINVAL; 444 goto fail; 445 } 446 } 447 } 448 449 450 /* OK */ 451 break; 452 453 default: 454 /* not being traced... */ 455 if ((p->p_flag & P_TRACED) == 0) { 456 error = EPERM; 457 goto fail; 458 } 459 460 /* not being traced by YOU */ 461 if (p->p_pptr != td->td_proc) { 462 error = EBUSY; 463 goto fail; 464 } 465 466 /* not currently stopped */ 467 if (!P_SHOULDSTOP(p) || (p->p_flag & P_WAITED) == 0) { 468 error = EBUSY; 469 goto fail; 470 } 471 472 /* OK */ 473 break; 474 } 475 476 td2 = FIRST_THREAD_IN_PROC(p); 477 #ifdef FIX_SSTEP 478 /* 479 * Single step fixup ala procfs 480 */ 481 FIX_SSTEP(td2); /* XXXKSE */ 482 #endif 483 484 /* 485 * Actually do the requests 486 */ 487 488 td->td_retval[0] = 0; 489 490 switch (req) { 491 case PT_TRACE_ME: 492 /* set my trace flag and "owner" so it can read/write me */ 493 p->p_flag |= P_TRACED; 494 p->p_oppid = p->p_pptr->p_pid; 495 PROC_UNLOCK(p); 496 sx_xunlock(&proctree_lock); 497 return (0); 498 499 case PT_ATTACH: 500 /* security check done above */ 501 p->p_flag |= P_TRACED; 502 p->p_oppid = p->p_pptr->p_pid; 503 if (p->p_pptr != td->td_proc) 504 proc_reparent(p, td->td_proc); 505 data = SIGSTOP; 506 goto sendsig; /* in PT_CONTINUE below */ 507 508 case PT_STEP: 509 case PT_CONTINUE: 510 case PT_DETACH: 511 /* Zero means do not send any signal */ 512 if (data < 0 || data > _SIG_MAXSIG) { 513 error = EINVAL; 514 goto fail; 515 } 516 517 _PHOLD(p); 518 519 if (req == PT_STEP) { 520 error = ptrace_single_step(td2); 521 if (error) { 522 _PRELE(p); 523 goto fail; 524 } 525 } 526 527 if (addr != (void *)1) { 528 error = ptrace_set_pc(td2, (u_long)(uintfptr_t)addr); 529 if (error) { 530 _PRELE(p); 531 goto fail; 532 } 533 } 534 _PRELE(p); 535 536 if (req == PT_DETACH) { 537 /* reset process parent */ 538 if (p->p_oppid != p->p_pptr->p_pid) { 539 struct proc *pp; 540 541 PROC_UNLOCK(p); 542 pp = pfind(p->p_oppid); 543 if (pp == NULL) 544 pp = initproc; 545 else 546 PROC_UNLOCK(pp); 547 PROC_LOCK(p); 548 proc_reparent(p, pp); 549 } 550 p->p_flag &= ~(P_TRACED | P_WAITED); 551 p->p_oppid = 0; 552 553 /* should we send SIGCHLD? */ 554 } 555 556 sendsig: 557 if (proctree_locked) 558 sx_xunlock(&proctree_lock); 559 /* deliver or queue signal */ 560 if (P_SHOULDSTOP(p)) { 561 p->p_xstat = data; 562 p->p_flag &= ~(P_STOPPED_TRACE|P_STOPPED_SIG); 563 mtx_lock_spin(&sched_lock); 564 thread_unsuspend(p); 565 setrunnable(td2); /* XXXKSE */ 566 /* Need foreach kse in proc, ... make_kse_queued(). */ 567 mtx_unlock_spin(&sched_lock); 568 } else if (data) 569 psignal(p, data); 570 PROC_UNLOCK(p); 571 572 return (0); 573 574 case PT_WRITE_I: 575 case PT_WRITE_D: 576 write = 1; 577 /* FALLTHROUGH */ 578 case PT_READ_I: 579 case PT_READ_D: 580 PROC_UNLOCK(p); 581 tmp = 0; 582 /* write = 0 set above */ 583 iov.iov_base = write ? (caddr_t)&data : (caddr_t)&tmp; 584 iov.iov_len = sizeof(int); 585 uio.uio_iov = &iov; 586 uio.uio_iovcnt = 1; 587 uio.uio_offset = (off_t)(uintptr_t)addr; 588 uio.uio_resid = sizeof(int); 589 uio.uio_segflg = UIO_SYSSPACE; /* i.e.: the uap */ 590 uio.uio_rw = write ? UIO_WRITE : UIO_READ; 591 uio.uio_td = td; 592 mtx_lock(&Giant); 593 error = proc_rwmem(p, &uio); 594 mtx_unlock(&Giant); 595 if (uio.uio_resid != 0) { 596 /* 597 * XXX proc_rwmem() doesn't currently return ENOSPC, 598 * so I think write() can bogusly return 0. 599 * XXX what happens for short writes? We don't want 600 * to write partial data. 601 * XXX proc_rwmem() returns EPERM for other invalid 602 * addresses. Convert this to EINVAL. Does this 603 * clobber returns of EPERM for other reasons? 604 */ 605 if (error == 0 || error == ENOSPC || error == EPERM) 606 error = EINVAL; /* EOF */ 607 } 608 if (!write) 609 td->td_retval[0] = tmp; 610 return (error); 611 612 case PT_IO: 613 PROC_UNLOCK(p); 614 piod = addr; 615 iov.iov_base = piod->piod_addr; 616 iov.iov_len = piod->piod_len; 617 uio.uio_iov = &iov; 618 uio.uio_iovcnt = 1; 619 uio.uio_offset = (off_t)(uintptr_t)piod->piod_offs; 620 uio.uio_resid = piod->piod_len; 621 uio.uio_segflg = UIO_USERSPACE; 622 uio.uio_td = td; 623 switch (piod->piod_op) { 624 case PIOD_READ_D: 625 case PIOD_READ_I: 626 uio.uio_rw = UIO_READ; 627 break; 628 case PIOD_WRITE_D: 629 case PIOD_WRITE_I: 630 uio.uio_rw = UIO_WRITE; 631 break; 632 default: 633 return (EINVAL); 634 } 635 mtx_lock(&Giant); 636 error = proc_rwmem(p, &uio); 637 mtx_unlock(&Giant); 638 piod->piod_len -= uio.uio_resid; 639 return (error); 640 641 case PT_KILL: 642 data = SIGKILL; 643 goto sendsig; /* in PT_CONTINUE above */ 644 645 case PT_SETREGS: 646 _PHOLD(p); 647 error = proc_write_regs(td2, addr); 648 _PRELE(p); 649 PROC_UNLOCK(p); 650 return (error); 651 652 case PT_GETREGS: 653 _PHOLD(p); 654 error = proc_read_regs(td2, addr); 655 _PRELE(p); 656 PROC_UNLOCK(p); 657 return (error); 658 659 case PT_SETFPREGS: 660 _PHOLD(p); 661 error = proc_write_fpregs(td2, addr); 662 _PRELE(p); 663 PROC_UNLOCK(p); 664 return (error); 665 666 case PT_GETFPREGS: 667 _PHOLD(p); 668 error = proc_read_fpregs(td2, addr); 669 _PRELE(p); 670 PROC_UNLOCK(p); 671 return (error); 672 673 case PT_SETDBREGS: 674 _PHOLD(p); 675 error = proc_write_dbregs(td2, addr); 676 _PRELE(p); 677 PROC_UNLOCK(p); 678 return (error); 679 680 case PT_GETDBREGS: 681 _PHOLD(p); 682 error = proc_read_dbregs(td2, addr); 683 _PRELE(p); 684 PROC_UNLOCK(p); 685 return (error); 686 687 default: 688 #ifdef __HAVE_PTRACE_MACHDEP 689 if (req >= PT_FIRSTMACH) { 690 _PHOLD(p); 691 error = cpu_ptrace(td2, req, addr, data); 692 _PRELE(p); 693 PROC_UNLOCK(p); 694 return (error); 695 } 696 #endif 697 break; 698 } 699 700 /* Unknown request. */ 701 error = EINVAL; 702 703 fail: 704 PROC_UNLOCK(p); 705 if (proctree_locked) 706 sx_xunlock(&proctree_lock); 707 return (error); 708 } 709 710 /* 711 * Stop a process because of a debugging event; 712 * stay stopped until p->p_step is cleared 713 * (cleared by PIOCCONT in procfs). 714 */ 715 void 716 stopevent(struct proc *p, unsigned int event, unsigned int val) 717 { 718 719 PROC_LOCK_ASSERT(p, MA_OWNED); 720 p->p_step = 1; 721 do { 722 p->p_xstat = val; 723 p->p_stype = event; /* Which event caused the stop? */ 724 wakeup(&p->p_stype); /* Wake up any PIOCWAIT'ing procs */ 725 msleep(&p->p_step, &p->p_mtx, PWAIT, "stopevent", 0); 726 } while (p->p_step); 727 } 728