1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1990 The Regents of the University of California. 5 * 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. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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 #include "opt_capsicum.h" 34 #include "opt_kstack_pages.h" 35 #include "opt_ktrace.h" 36 37 #include <sys/param.h> 38 #include <sys/capsicum.h> 39 #include <sys/systm.h> 40 #include <sys/ktrace.h> 41 #include <sys/lock.h> 42 #include <sys/malloc.h> 43 #include <sys/mutex.h> 44 #include <sys/priv.h> 45 #include <sys/proc.h> 46 #include <sys/smp.h> 47 #include <sys/sysproto.h> 48 49 #include <vm/vm.h> 50 #include <vm/pmap.h> 51 #include <vm/vm_map.h> 52 #include <vm/vm_extern.h> 53 54 #include <machine/atomic.h> 55 #include <machine/cpu.h> 56 #include <machine/pcb.h> 57 #include <machine/pcb_ext.h> 58 #include <machine/proc.h> 59 #include <machine/sysarch.h> 60 61 #include <security/audit/audit.h> 62 63 #include <vm/vm_kern.h> /* for kernel_map */ 64 65 #define MAX_LD 8192 66 #define LD_PER_PAGE 512 67 #define NEW_MAX_LD(num) rounddown2(num + LD_PER_PAGE, LD_PER_PAGE) 68 #define SIZE_FROM_LARGEST_LD(num) (NEW_MAX_LD(num) << 3) 69 #define NULL_LDT_BASE ((caddr_t)NULL) 70 71 #ifdef SMP 72 static void set_user_ldt_rv(void *arg); 73 #endif 74 static int i386_set_ldt_data(struct thread *, int start, int num, 75 union descriptor *descs); 76 static int i386_ldt_grow(struct thread *td, int len); 77 78 void 79 fill_based_sd(struct segment_descriptor *sdp, uint32_t base) 80 { 81 82 sdp->sd_lobase = base & 0xffffff; 83 sdp->sd_hibase = (base >> 24) & 0xff; 84 sdp->sd_lolimit = 0xffff; /* 4GB limit, wraps around */ 85 sdp->sd_hilimit = 0xf; 86 sdp->sd_type = SDT_MEMRWA; 87 sdp->sd_dpl = SEL_UPL; 88 sdp->sd_p = 1; 89 sdp->sd_xx = 0; 90 sdp->sd_def32 = 1; 91 sdp->sd_gran = 1; 92 } 93 94 /* 95 * Construct special descriptors for "base" selectors. Store them in 96 * the PCB for later use by cpu_switch(). Store them in the GDT for 97 * more immediate use. The GDT entries are part of the current 98 * context. Callers must load related segment registers to complete 99 * setting up the current context. 100 */ 101 void 102 set_fsbase(struct thread *td, uint32_t base) 103 { 104 struct segment_descriptor sd; 105 106 fill_based_sd(&sd, base); 107 critical_enter(); 108 td->td_pcb->pcb_fsd = sd; 109 if (td == curthread) 110 PCPU_GET(fsgs_gdt)[0] = sd; 111 critical_exit(); 112 } 113 114 void 115 set_gsbase(struct thread *td, uint32_t base) 116 { 117 struct segment_descriptor sd; 118 119 fill_based_sd(&sd, base); 120 critical_enter(); 121 td->td_pcb->pcb_gsd = sd; 122 if (td == curthread) 123 PCPU_GET(fsgs_gdt)[1] = sd; 124 critical_exit(); 125 } 126 127 #ifndef _SYS_SYSPROTO_H_ 128 struct sysarch_args { 129 int op; 130 char *parms; 131 }; 132 #endif 133 134 int 135 sysarch(struct thread *td, struct sysarch_args *uap) 136 { 137 int error; 138 union descriptor *lp; 139 union { 140 struct i386_ldt_args largs; 141 struct i386_ioperm_args iargs; 142 struct i386_get_xfpustate xfpu; 143 } kargs; 144 uint32_t base; 145 struct segment_descriptor *sdp; 146 147 AUDIT_ARG_CMD(uap->op); 148 149 #ifdef CAPABILITY_MODE 150 /* 151 * When adding new operations, add a new case statement here to 152 * explicitly indicate whether or not the operation is safe to 153 * perform in capability mode. 154 */ 155 if (IN_CAPABILITY_MODE(td)) { 156 switch (uap->op) { 157 case I386_GET_LDT: 158 case I386_SET_LDT: 159 case I386_GET_IOPERM: 160 case I386_GET_FSBASE: 161 case I386_SET_FSBASE: 162 case I386_GET_GSBASE: 163 case I386_SET_GSBASE: 164 case I386_GET_XFPUSTATE: 165 break; 166 167 case I386_SET_IOPERM: 168 default: 169 #ifdef KTRACE 170 if (KTRPOINT(td, KTR_CAPFAIL)) 171 ktrcapfail(CAPFAIL_SYSCALL, NULL, NULL); 172 #endif 173 return (ECAPMODE); 174 } 175 } 176 #endif 177 178 switch (uap->op) { 179 case I386_GET_IOPERM: 180 case I386_SET_IOPERM: 181 if ((error = copyin(uap->parms, &kargs.iargs, 182 sizeof(struct i386_ioperm_args))) != 0) 183 return (error); 184 break; 185 case I386_GET_LDT: 186 case I386_SET_LDT: 187 if ((error = copyin(uap->parms, &kargs.largs, 188 sizeof(struct i386_ldt_args))) != 0) 189 return (error); 190 break; 191 case I386_GET_XFPUSTATE: 192 if ((error = copyin(uap->parms, &kargs.xfpu, 193 sizeof(struct i386_get_xfpustate))) != 0) 194 return (error); 195 break; 196 default: 197 break; 198 } 199 200 switch (uap->op) { 201 case I386_GET_LDT: 202 error = i386_get_ldt(td, &kargs.largs); 203 break; 204 case I386_SET_LDT: 205 if (kargs.largs.descs != NULL) { 206 if (kargs.largs.num > MAX_LD) 207 return (EINVAL); 208 lp = malloc(kargs.largs.num * sizeof(union descriptor), 209 M_TEMP, M_WAITOK); 210 error = copyin(kargs.largs.descs, lp, 211 kargs.largs.num * sizeof(union descriptor)); 212 if (error == 0) 213 error = i386_set_ldt(td, &kargs.largs, lp); 214 free(lp, M_TEMP); 215 } else { 216 error = i386_set_ldt(td, &kargs.largs, NULL); 217 } 218 break; 219 case I386_GET_IOPERM: 220 error = i386_get_ioperm(td, &kargs.iargs); 221 if (error == 0) 222 error = copyout(&kargs.iargs, uap->parms, 223 sizeof(struct i386_ioperm_args)); 224 break; 225 case I386_SET_IOPERM: 226 error = i386_set_ioperm(td, &kargs.iargs); 227 break; 228 case I386_VM86: 229 error = vm86_sysarch(td, uap->parms); 230 break; 231 case I386_GET_FSBASE: 232 sdp = &td->td_pcb->pcb_fsd; 233 base = sdp->sd_hibase << 24 | sdp->sd_lobase; 234 error = copyout(&base, uap->parms, sizeof(base)); 235 break; 236 case I386_SET_FSBASE: 237 error = copyin(uap->parms, &base, sizeof(base)); 238 if (error == 0) { 239 /* 240 * Construct the special descriptor for fsbase 241 * and arrange for doreti to load its selector 242 * soon enough. 243 */ 244 set_fsbase(td, base); 245 td->td_frame->tf_fs = GSEL(GUFS_SEL, SEL_UPL); 246 } 247 break; 248 case I386_GET_GSBASE: 249 sdp = &td->td_pcb->pcb_gsd; 250 base = sdp->sd_hibase << 24 | sdp->sd_lobase; 251 error = copyout(&base, uap->parms, sizeof(base)); 252 break; 253 case I386_SET_GSBASE: 254 error = copyin(uap->parms, &base, sizeof(base)); 255 if (error == 0) { 256 /* 257 * Construct the special descriptor for gsbase. 258 * The selector is loaded immediately, since we 259 * normally only reload %gs on context switches. 260 */ 261 set_gsbase(td, base); 262 load_gs(GSEL(GUGS_SEL, SEL_UPL)); 263 } 264 break; 265 case I386_GET_XFPUSTATE: 266 if (kargs.xfpu.len > cpu_max_ext_state_size - 267 sizeof(union savefpu)) 268 return (EINVAL); 269 npxgetregs(td); 270 error = copyout((char *)(get_pcb_user_save_td(td) + 1), 271 kargs.xfpu.addr, kargs.xfpu.len); 272 break; 273 default: 274 error = EINVAL; 275 break; 276 } 277 return (error); 278 } 279 280 int 281 i386_extend_pcb(struct thread *td) 282 { 283 int i, offset; 284 u_long *addr; 285 struct pcb_ext *ext; 286 struct soft_segment_descriptor ssd = { 287 0, /* segment base address (overwritten) */ 288 ctob(IOPAGES + 1) - 1, /* length */ 289 SDT_SYS386TSS, /* segment type */ 290 0, /* priority level */ 291 1, /* descriptor present */ 292 0, 0, 293 0, /* default 32 size */ 294 0 /* granularity */ 295 }; 296 297 ext = pmap_trm_alloc(ctob(IOPAGES + 1), M_WAITOK | M_ZERO); 298 /* -16 is so we can convert a trapframe into vm86trapframe inplace */ 299 ext->ext_tss.tss_ss0 = GSEL(GDATA_SEL, SEL_KPL); 300 /* 301 * The last byte of the i/o map must be followed by an 0xff byte. 302 * We arbitrarily allocate 16 bytes here, to keep the starting 303 * address on a doubleword boundary. 304 */ 305 offset = PAGE_SIZE - 16; 306 ext->ext_tss.tss_ioopt = 307 (offset - ((unsigned)&ext->ext_tss - (unsigned)ext)) << 16; 308 ext->ext_iomap = (caddr_t)ext + offset; 309 ext->ext_vm86.vm86_intmap = (caddr_t)ext + offset - 32; 310 311 addr = (u_long *)ext->ext_vm86.vm86_intmap; 312 for (i = 0; i < (ctob(IOPAGES) + 32 + 16) / sizeof(u_long); i++) 313 *addr++ = ~0; 314 315 ssd.ssd_base = (unsigned)&ext->ext_tss; 316 ssd.ssd_limit -= ((unsigned)&ext->ext_tss - (unsigned)ext); 317 ssdtosd(&ssd, &ext->ext_tssd); 318 319 KASSERT(td == curthread, ("giving TSS to !curthread")); 320 KASSERT(td->td_pcb->pcb_ext == 0, ("already have a TSS!")); 321 322 /* Switch to the new TSS. */ 323 critical_enter(); 324 ext->ext_tss.tss_esp0 = PCPU_GET(trampstk); 325 td->td_pcb->pcb_ext = ext; 326 PCPU_SET(private_tss, 1); 327 *PCPU_GET(tss_gdt) = ext->ext_tssd; 328 ltr(GSEL(GPROC0_SEL, SEL_KPL)); 329 critical_exit(); 330 331 return 0; 332 } 333 334 int 335 i386_set_ioperm(struct thread *td, struct i386_ioperm_args *uap) 336 { 337 char *iomap; 338 u_int i; 339 int error; 340 341 if ((error = priv_check(td, PRIV_IO)) != 0) 342 return (error); 343 if ((error = securelevel_gt(td->td_ucred, 0)) != 0) 344 return (error); 345 /* 346 * XXX 347 * While this is restricted to root, we should probably figure out 348 * whether any other driver is using this i/o address, as so not to 349 * cause confusion. This probably requires a global 'usage registry'. 350 */ 351 352 if (td->td_pcb->pcb_ext == 0) 353 if ((error = i386_extend_pcb(td)) != 0) 354 return (error); 355 iomap = (char *)td->td_pcb->pcb_ext->ext_iomap; 356 357 if (uap->start > uap->start + uap->length || 358 uap->start + uap->length > IOPAGES * PAGE_SIZE * NBBY) 359 return (EINVAL); 360 361 for (i = uap->start; i < uap->start + uap->length; i++) { 362 if (uap->enable) 363 iomap[i >> 3] &= ~(1 << (i & 7)); 364 else 365 iomap[i >> 3] |= (1 << (i & 7)); 366 } 367 return (error); 368 } 369 370 int 371 i386_get_ioperm(struct thread *td, struct i386_ioperm_args *uap) 372 { 373 int i, state; 374 char *iomap; 375 376 if (uap->start >= IOPAGES * PAGE_SIZE * NBBY) 377 return (EINVAL); 378 379 if (td->td_pcb->pcb_ext == 0) { 380 uap->length = 0; 381 goto done; 382 } 383 384 iomap = (char *)td->td_pcb->pcb_ext->ext_iomap; 385 386 i = uap->start; 387 state = (iomap[i >> 3] >> (i & 7)) & 1; 388 uap->enable = !state; 389 uap->length = 1; 390 391 for (i = uap->start + 1; i < IOPAGES * PAGE_SIZE * NBBY; i++) { 392 if (state != ((iomap[i >> 3] >> (i & 7)) & 1)) 393 break; 394 uap->length++; 395 } 396 397 done: 398 return (0); 399 } 400 401 /* 402 * Update the GDT entry pointing to the LDT to point to the LDT of the 403 * current process. Manage dt_lock holding/unholding autonomously. 404 */ 405 static void 406 set_user_ldt_locked(struct mdproc *mdp) 407 { 408 struct proc_ldt *pldt; 409 int gdt_idx; 410 411 mtx_assert(&dt_lock, MA_OWNED); 412 413 pldt = mdp->md_ldt; 414 gdt_idx = GUSERLDT_SEL; 415 gdt_idx += PCPU_GET(cpuid) * NGDT; /* always 0 on UP */ 416 gdt[gdt_idx].sd = pldt->ldt_sd; 417 lldt(GSEL(GUSERLDT_SEL, SEL_KPL)); 418 PCPU_SET(currentldt, GSEL(GUSERLDT_SEL, SEL_KPL)); 419 } 420 421 void 422 set_user_ldt(struct mdproc *mdp) 423 { 424 425 mtx_lock_spin(&dt_lock); 426 set_user_ldt_locked(mdp); 427 mtx_unlock_spin(&dt_lock); 428 } 429 430 #ifdef SMP 431 static void 432 set_user_ldt_rv(void *arg) 433 { 434 struct proc *p; 435 436 p = curproc; 437 if (arg == p->p_vmspace) 438 set_user_ldt(&p->p_md); 439 } 440 #endif 441 442 /* 443 * dt_lock must be held. Returns with dt_lock held. 444 */ 445 struct proc_ldt * 446 user_ldt_alloc(struct mdproc *mdp, int len) 447 { 448 struct proc_ldt *pldt, *new_ldt; 449 450 mtx_assert(&dt_lock, MA_OWNED); 451 mtx_unlock_spin(&dt_lock); 452 new_ldt = malloc(sizeof(struct proc_ldt), M_SUBPROC, M_WAITOK); 453 454 new_ldt->ldt_len = len = NEW_MAX_LD(len); 455 new_ldt->ldt_base = pmap_trm_alloc(len * sizeof(union descriptor), 456 M_WAITOK | M_ZERO); 457 new_ldt->ldt_refcnt = 1; 458 new_ldt->ldt_active = 0; 459 460 mtx_lock_spin(&dt_lock); 461 gdt_segs[GUSERLDT_SEL].ssd_base = (unsigned)new_ldt->ldt_base; 462 gdt_segs[GUSERLDT_SEL].ssd_limit = len * sizeof(union descriptor) - 1; 463 ssdtosd(&gdt_segs[GUSERLDT_SEL], &new_ldt->ldt_sd); 464 465 if ((pldt = mdp->md_ldt) != NULL) { 466 if (len > pldt->ldt_len) 467 len = pldt->ldt_len; 468 bcopy(pldt->ldt_base, new_ldt->ldt_base, 469 len * sizeof(union descriptor)); 470 } else 471 bcopy(ldt, new_ldt->ldt_base, sizeof(union descriptor) * NLDT); 472 473 return (new_ldt); 474 } 475 476 /* 477 * Must be called with dt_lock held. Returns with dt_lock unheld. 478 */ 479 void 480 user_ldt_free(struct thread *td) 481 { 482 struct mdproc *mdp; 483 struct proc_ldt *pldt; 484 485 mtx_assert(&dt_lock, MA_OWNED); 486 mdp = &td->td_proc->p_md; 487 if ((pldt = mdp->md_ldt) == NULL) { 488 mtx_unlock_spin(&dt_lock); 489 return; 490 } 491 492 if (td == curthread) { 493 lldt(_default_ldt); 494 PCPU_SET(currentldt, _default_ldt); 495 } 496 497 mdp->md_ldt = NULL; 498 user_ldt_deref(pldt); 499 } 500 501 void 502 user_ldt_deref(struct proc_ldt *pldt) 503 { 504 505 mtx_assert(&dt_lock, MA_OWNED); 506 if (--pldt->ldt_refcnt == 0) { 507 mtx_unlock_spin(&dt_lock); 508 pmap_trm_free(pldt->ldt_base, pldt->ldt_len * 509 sizeof(union descriptor)); 510 free(pldt, M_SUBPROC); 511 } else 512 mtx_unlock_spin(&dt_lock); 513 } 514 515 /* 516 * Note for the authors of compat layers (linux, etc): copyout() in 517 * the function below is not a problem since it presents data in 518 * arch-specific format (i.e. i386-specific in this case), not in 519 * the OS-specific one. 520 */ 521 int 522 i386_get_ldt(struct thread *td, struct i386_ldt_args *uap) 523 { 524 struct proc_ldt *pldt; 525 char *data; 526 u_int nldt, num; 527 int error; 528 529 #ifdef DEBUG 530 printf("i386_get_ldt: start=%u num=%u descs=%p\n", 531 uap->start, uap->num, (void *)uap->descs); 532 #endif 533 534 num = min(uap->num, MAX_LD); 535 data = malloc(num * sizeof(union descriptor), M_TEMP, M_WAITOK); 536 mtx_lock_spin(&dt_lock); 537 pldt = td->td_proc->p_md.md_ldt; 538 nldt = pldt != NULL ? pldt->ldt_len : NLDT; 539 if (uap->start >= nldt) { 540 num = 0; 541 } else { 542 num = min(num, nldt - uap->start); 543 bcopy(pldt != NULL ? 544 &((union descriptor *)(pldt->ldt_base))[uap->start] : 545 &ldt[uap->start], data, num * sizeof(union descriptor)); 546 } 547 mtx_unlock_spin(&dt_lock); 548 error = copyout(data, uap->descs, num * sizeof(union descriptor)); 549 if (error == 0) 550 td->td_retval[0] = num; 551 free(data, M_TEMP); 552 return (error); 553 } 554 555 int 556 i386_set_ldt(struct thread *td, struct i386_ldt_args *uap, 557 union descriptor *descs) 558 { 559 struct mdproc *mdp; 560 struct proc_ldt *pldt; 561 union descriptor *dp; 562 u_int largest_ld, i; 563 int error; 564 565 #ifdef DEBUG 566 printf("i386_set_ldt: start=%u num=%u descs=%p\n", 567 uap->start, uap->num, (void *)uap->descs); 568 #endif 569 error = 0; 570 mdp = &td->td_proc->p_md; 571 572 if (descs == NULL) { 573 /* Free descriptors */ 574 if (uap->start == 0 && uap->num == 0) { 575 /* 576 * Treat this as a special case, so userland needn't 577 * know magic number NLDT. 578 */ 579 uap->start = NLDT; 580 uap->num = MAX_LD - NLDT; 581 } 582 mtx_lock_spin(&dt_lock); 583 if ((pldt = mdp->md_ldt) == NULL || 584 uap->start >= pldt->ldt_len) { 585 mtx_unlock_spin(&dt_lock); 586 return (0); 587 } 588 largest_ld = uap->start + uap->num; 589 if (largest_ld > pldt->ldt_len) 590 largest_ld = pldt->ldt_len; 591 for (i = uap->start; i < largest_ld; i++) 592 atomic_store_rel_64(&((uint64_t *)(pldt->ldt_base))[i], 593 0); 594 mtx_unlock_spin(&dt_lock); 595 return (0); 596 } 597 598 if (uap->start != LDT_AUTO_ALLOC || uap->num != 1) { 599 /* verify range of descriptors to modify */ 600 largest_ld = uap->start + uap->num; 601 if (uap->start >= MAX_LD || largest_ld > MAX_LD) 602 return (EINVAL); 603 } 604 605 /* Check descriptors for access violations */ 606 for (i = 0; i < uap->num; i++) { 607 dp = &descs[i]; 608 609 switch (dp->sd.sd_type) { 610 case SDT_SYSNULL: /* system null */ 611 dp->sd.sd_p = 0; 612 break; 613 case SDT_SYS286TSS: /* system 286 TSS available */ 614 case SDT_SYSLDT: /* system local descriptor table */ 615 case SDT_SYS286BSY: /* system 286 TSS busy */ 616 case SDT_SYSTASKGT: /* system task gate */ 617 case SDT_SYS286IGT: /* system 286 interrupt gate */ 618 case SDT_SYS286TGT: /* system 286 trap gate */ 619 case SDT_SYSNULL2: /* undefined by Intel */ 620 case SDT_SYS386TSS: /* system 386 TSS available */ 621 case SDT_SYSNULL3: /* undefined by Intel */ 622 case SDT_SYS386BSY: /* system 386 TSS busy */ 623 case SDT_SYSNULL4: /* undefined by Intel */ 624 case SDT_SYS386IGT: /* system 386 interrupt gate */ 625 case SDT_SYS386TGT: /* system 386 trap gate */ 626 case SDT_SYS286CGT: /* system 286 call gate */ 627 case SDT_SYS386CGT: /* system 386 call gate */ 628 return (EACCES); 629 630 /* memory segment types */ 631 case SDT_MEMEC: /* memory execute only conforming */ 632 case SDT_MEMEAC: /* memory execute only accessed conforming */ 633 case SDT_MEMERC: /* memory execute read conforming */ 634 case SDT_MEMERAC: /* memory execute read accessed conforming */ 635 /* Must be "present" if executable and conforming. */ 636 if (dp->sd.sd_p == 0) 637 return (EACCES); 638 break; 639 case SDT_MEMRO: /* memory read only */ 640 case SDT_MEMROA: /* memory read only accessed */ 641 case SDT_MEMRW: /* memory read write */ 642 case SDT_MEMRWA: /* memory read write accessed */ 643 case SDT_MEMROD: /* memory read only expand dwn limit */ 644 case SDT_MEMRODA: /* memory read only expand dwn lim accessed */ 645 case SDT_MEMRWD: /* memory read write expand dwn limit */ 646 case SDT_MEMRWDA: /* memory read write expand dwn lim acessed */ 647 case SDT_MEME: /* memory execute only */ 648 case SDT_MEMEA: /* memory execute only accessed */ 649 case SDT_MEMER: /* memory execute read */ 650 case SDT_MEMERA: /* memory execute read accessed */ 651 break; 652 default: 653 return (EINVAL); 654 } 655 656 /* Only user (ring-3) descriptors may be present. */ 657 if (dp->sd.sd_p != 0 && dp->sd.sd_dpl != SEL_UPL) 658 return (EACCES); 659 } 660 661 if (uap->start == LDT_AUTO_ALLOC && uap->num == 1) { 662 /* Allocate a free slot */ 663 mtx_lock_spin(&dt_lock); 664 if ((pldt = mdp->md_ldt) == NULL) { 665 if ((error = i386_ldt_grow(td, NLDT + 1))) { 666 mtx_unlock_spin(&dt_lock); 667 return (error); 668 } 669 pldt = mdp->md_ldt; 670 } 671 again: 672 /* 673 * start scanning a bit up to leave room for NVidia and 674 * Wine, which still user the "Blat" method of allocation. 675 */ 676 dp = &((union descriptor *)(pldt->ldt_base))[NLDT]; 677 for (i = NLDT; i < pldt->ldt_len; ++i) { 678 if (dp->sd.sd_type == SDT_SYSNULL) 679 break; 680 dp++; 681 } 682 if (i >= pldt->ldt_len) { 683 if ((error = i386_ldt_grow(td, pldt->ldt_len+1))) { 684 mtx_unlock_spin(&dt_lock); 685 return (error); 686 } 687 goto again; 688 } 689 uap->start = i; 690 error = i386_set_ldt_data(td, i, 1, descs); 691 mtx_unlock_spin(&dt_lock); 692 } else { 693 largest_ld = uap->start + uap->num; 694 mtx_lock_spin(&dt_lock); 695 if (!(error = i386_ldt_grow(td, largest_ld))) { 696 error = i386_set_ldt_data(td, uap->start, uap->num, 697 descs); 698 } 699 mtx_unlock_spin(&dt_lock); 700 } 701 if (error == 0) 702 td->td_retval[0] = uap->start; 703 return (error); 704 } 705 706 static int 707 i386_set_ldt_data(struct thread *td, int start, int num, 708 union descriptor *descs) 709 { 710 struct mdproc *mdp; 711 struct proc_ldt *pldt; 712 uint64_t *dst, *src; 713 int i; 714 715 mtx_assert(&dt_lock, MA_OWNED); 716 717 mdp = &td->td_proc->p_md; 718 pldt = mdp->md_ldt; 719 dst = (uint64_t *)(pldt->ldt_base); 720 src = (uint64_t *)descs; 721 722 /* 723 * Atomic(9) is used only to get 64bit atomic store with 724 * cmpxchg8b when available. There is no op without release 725 * semantic. 726 */ 727 for (i = 0; i < num; i++) 728 atomic_store_rel_64(&dst[start + i], src[i]); 729 return (0); 730 } 731 732 static int 733 i386_ldt_grow(struct thread *td, int len) 734 { 735 struct mdproc *mdp; 736 struct proc_ldt *new_ldt, *pldt; 737 caddr_t old_ldt_base; 738 int old_ldt_len; 739 740 mtx_assert(&dt_lock, MA_OWNED); 741 742 if (len > MAX_LD) 743 return (ENOMEM); 744 if (len < NLDT + 1) 745 len = NLDT + 1; 746 747 mdp = &td->td_proc->p_md; 748 old_ldt_base = NULL_LDT_BASE; 749 old_ldt_len = 0; 750 751 /* Allocate a user ldt. */ 752 if ((pldt = mdp->md_ldt) == NULL || len > pldt->ldt_len) { 753 new_ldt = user_ldt_alloc(mdp, len); 754 if (new_ldt == NULL) 755 return (ENOMEM); 756 pldt = mdp->md_ldt; 757 758 if (pldt != NULL) { 759 if (new_ldt->ldt_len <= pldt->ldt_len) { 760 /* 761 * We just lost the race for allocation, so 762 * free the new object and return. 763 */ 764 mtx_unlock_spin(&dt_lock); 765 pmap_trm_free(new_ldt->ldt_base, 766 new_ldt->ldt_len * sizeof(union descriptor)); 767 free(new_ldt, M_SUBPROC); 768 mtx_lock_spin(&dt_lock); 769 return (0); 770 } 771 772 /* 773 * We have to substitute the current LDT entry for 774 * curproc with the new one since its size grew. 775 */ 776 old_ldt_base = pldt->ldt_base; 777 old_ldt_len = pldt->ldt_len; 778 pldt->ldt_sd = new_ldt->ldt_sd; 779 pldt->ldt_base = new_ldt->ldt_base; 780 pldt->ldt_len = new_ldt->ldt_len; 781 } else 782 mdp->md_ldt = pldt = new_ldt; 783 #ifdef SMP 784 /* 785 * Signal other cpus to reload ldt. We need to unlock dt_lock 786 * here because other CPU will contest on it since their 787 * curthreads won't hold the lock and will block when trying 788 * to acquire it. 789 */ 790 mtx_unlock_spin(&dt_lock); 791 smp_rendezvous(NULL, set_user_ldt_rv, NULL, 792 td->td_proc->p_vmspace); 793 #else 794 set_user_ldt_locked(&td->td_proc->p_md); 795 mtx_unlock_spin(&dt_lock); 796 #endif 797 if (old_ldt_base != NULL_LDT_BASE) { 798 pmap_trm_free(old_ldt_base, old_ldt_len * 799 sizeof(union descriptor)); 800 free(new_ldt, M_SUBPROC); 801 } 802 mtx_lock_spin(&dt_lock); 803 } 804 return (0); 805 } 806