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 * from: @(#)sys_machdep.c 5.5 (Berkeley) 1/19/91
32 */
33
34 #include <sys/cdefs.h>
35 #include "opt_capsicum.h"
36 #include "opt_kstack_pages.h"
37 #include "opt_ktrace.h"
38
39 #include <sys/param.h>
40 #include <sys/capsicum.h>
41 #include <sys/systm.h>
42 #include <sys/ktrace.h>
43 #include <sys/lock.h>
44 #include <sys/malloc.h>
45 #include <sys/mutex.h>
46 #include <sys/priv.h>
47 #include <sys/proc.h>
48 #include <sys/smp.h>
49 #include <sys/sysproto.h>
50
51 #include <vm/vm.h>
52 #include <vm/pmap.h>
53 #include <vm/vm_map.h>
54 #include <vm/vm_extern.h>
55
56 #include <machine/atomic.h>
57 #include <machine/cpu.h>
58 #include <machine/pcb.h>
59 #include <machine/pcb_ext.h>
60 #include <machine/proc.h>
61 #include <machine/sysarch.h>
62
63 #include <security/audit/audit.h>
64
65 #include <vm/vm_kern.h> /* for kernel_map */
66
67 #define MAX_LD 8192
68 #define LD_PER_PAGE 512
69 #define NEW_MAX_LD(num) rounddown2(num + LD_PER_PAGE, LD_PER_PAGE)
70 #define SIZE_FROM_LARGEST_LD(num) (NEW_MAX_LD(num) << 3)
71 #define NULL_LDT_BASE ((caddr_t)NULL)
72
73 #ifdef SMP
74 static void set_user_ldt_rv(void *arg);
75 #endif
76 static int i386_set_ldt_data(struct thread *, int start, int num,
77 union descriptor *descs);
78 static int i386_ldt_grow(struct thread *td, int len);
79
80 void
fill_based_sd(struct segment_descriptor * sdp,uint32_t base)81 fill_based_sd(struct segment_descriptor *sdp, uint32_t base)
82 {
83
84 sdp->sd_lobase = base & 0xffffff;
85 sdp->sd_hibase = (base >> 24) & 0xff;
86 sdp->sd_lolimit = 0xffff; /* 4GB limit, wraps around */
87 sdp->sd_hilimit = 0xf;
88 sdp->sd_type = SDT_MEMRWA;
89 sdp->sd_dpl = SEL_UPL;
90 sdp->sd_p = 1;
91 sdp->sd_xx = 0;
92 sdp->sd_def32 = 1;
93 sdp->sd_gran = 1;
94 }
95
96 /*
97 * Construct special descriptors for "base" selectors. Store them in
98 * the PCB for later use by cpu_switch(). Store them in the GDT for
99 * more immediate use. The GDT entries are part of the current
100 * context. Callers must load related segment registers to complete
101 * setting up the current context.
102 */
103 void
set_fsbase(struct thread * td,uint32_t base)104 set_fsbase(struct thread *td, uint32_t base)
105 {
106 struct segment_descriptor sd;
107
108 fill_based_sd(&sd, base);
109 critical_enter();
110 td->td_pcb->pcb_fsd = sd;
111 if (td == curthread)
112 PCPU_GET(fsgs_gdt)[0] = sd;
113 critical_exit();
114 }
115
116 void
set_gsbase(struct thread * td,uint32_t base)117 set_gsbase(struct thread *td, uint32_t base)
118 {
119 struct segment_descriptor sd;
120
121 fill_based_sd(&sd, base);
122 critical_enter();
123 td->td_pcb->pcb_gsd = sd;
124 if (td == curthread)
125 PCPU_GET(fsgs_gdt)[1] = sd;
126 critical_exit();
127 }
128
129 #ifndef _SYS_SYSPROTO_H_
130 struct sysarch_args {
131 int op;
132 char *parms;
133 };
134 #endif
135
136 int
sysarch(struct thread * td,struct sysarch_args * uap)137 sysarch(struct thread *td, struct sysarch_args *uap)
138 {
139 int error;
140 union descriptor *lp;
141 union {
142 struct i386_ldt_args largs;
143 struct i386_ioperm_args iargs;
144 struct i386_get_xfpustate xfpu;
145 } kargs;
146 uint32_t base;
147 struct segment_descriptor *sdp;
148
149 AUDIT_ARG_CMD(uap->op);
150
151 #ifdef CAPABILITY_MODE
152 /*
153 * When adding new operations, add a new case statement here to
154 * explicitly indicate whether or not the operation is safe to
155 * perform in capability mode.
156 */
157 if (IN_CAPABILITY_MODE(td)) {
158 switch (uap->op) {
159 case I386_GET_LDT:
160 case I386_SET_LDT:
161 case I386_GET_IOPERM:
162 case I386_GET_FSBASE:
163 case I386_SET_FSBASE:
164 case I386_GET_GSBASE:
165 case I386_SET_GSBASE:
166 case I386_GET_XFPUSTATE:
167 break;
168
169 case I386_SET_IOPERM:
170 default:
171 #ifdef KTRACE
172 if (KTRPOINT(td, KTR_CAPFAIL))
173 ktrcapfail(CAPFAIL_SYSCALL, NULL, NULL);
174 #endif
175 return (ECAPMODE);
176 }
177 }
178 #endif
179
180 switch (uap->op) {
181 case I386_GET_IOPERM:
182 case I386_SET_IOPERM:
183 if ((error = copyin(uap->parms, &kargs.iargs,
184 sizeof(struct i386_ioperm_args))) != 0)
185 return (error);
186 break;
187 case I386_GET_LDT:
188 case I386_SET_LDT:
189 if ((error = copyin(uap->parms, &kargs.largs,
190 sizeof(struct i386_ldt_args))) != 0)
191 return (error);
192 break;
193 case I386_GET_XFPUSTATE:
194 if ((error = copyin(uap->parms, &kargs.xfpu,
195 sizeof(struct i386_get_xfpustate))) != 0)
196 return (error);
197 break;
198 default:
199 break;
200 }
201
202 switch (uap->op) {
203 case I386_GET_LDT:
204 error = i386_get_ldt(td, &kargs.largs);
205 break;
206 case I386_SET_LDT:
207 if (kargs.largs.descs != NULL) {
208 if (kargs.largs.num > MAX_LD)
209 return (EINVAL);
210 lp = malloc(kargs.largs.num * sizeof(union descriptor),
211 M_TEMP, M_WAITOK);
212 error = copyin(kargs.largs.descs, lp,
213 kargs.largs.num * sizeof(union descriptor));
214 if (error == 0)
215 error = i386_set_ldt(td, &kargs.largs, lp);
216 free(lp, M_TEMP);
217 } else {
218 error = i386_set_ldt(td, &kargs.largs, NULL);
219 }
220 break;
221 case I386_GET_IOPERM:
222 error = i386_get_ioperm(td, &kargs.iargs);
223 if (error == 0)
224 error = copyout(&kargs.iargs, uap->parms,
225 sizeof(struct i386_ioperm_args));
226 break;
227 case I386_SET_IOPERM:
228 error = i386_set_ioperm(td, &kargs.iargs);
229 break;
230 case I386_VM86:
231 error = vm86_sysarch(td, uap->parms);
232 break;
233 case I386_GET_FSBASE:
234 sdp = &td->td_pcb->pcb_fsd;
235 base = sdp->sd_hibase << 24 | sdp->sd_lobase;
236 error = copyout(&base, uap->parms, sizeof(base));
237 break;
238 case I386_SET_FSBASE:
239 error = copyin(uap->parms, &base, sizeof(base));
240 if (error == 0) {
241 /*
242 * Construct the special descriptor for fsbase
243 * and arrange for doreti to load its selector
244 * soon enough.
245 */
246 set_fsbase(td, base);
247 td->td_frame->tf_fs = GSEL(GUFS_SEL, SEL_UPL);
248 }
249 break;
250 case I386_GET_GSBASE:
251 sdp = &td->td_pcb->pcb_gsd;
252 base = sdp->sd_hibase << 24 | sdp->sd_lobase;
253 error = copyout(&base, uap->parms, sizeof(base));
254 break;
255 case I386_SET_GSBASE:
256 error = copyin(uap->parms, &base, sizeof(base));
257 if (error == 0) {
258 /*
259 * Construct the special descriptor for gsbase.
260 * The selector is loaded immediately, since we
261 * normally only reload %gs on context switches.
262 */
263 set_gsbase(td, base);
264 load_gs(GSEL(GUGS_SEL, SEL_UPL));
265 }
266 break;
267 case I386_GET_XFPUSTATE:
268 if (kargs.xfpu.len > cpu_max_ext_state_size -
269 sizeof(union savefpu))
270 return (EINVAL);
271 npxgetregs(td);
272 error = copyout((char *)(get_pcb_user_save_td(td) + 1),
273 kargs.xfpu.addr, kargs.xfpu.len);
274 break;
275 default:
276 error = EINVAL;
277 break;
278 }
279 return (error);
280 }
281
282 int
i386_extend_pcb(struct thread * td)283 i386_extend_pcb(struct thread *td)
284 {
285 int i, offset;
286 u_long *addr;
287 struct pcb_ext *ext;
288 struct soft_segment_descriptor ssd = {
289 0, /* segment base address (overwritten) */
290 ctob(IOPAGES + 1) - 1, /* length */
291 SDT_SYS386TSS, /* segment type */
292 0, /* priority level */
293 1, /* descriptor present */
294 0, 0,
295 0, /* default 32 size */
296 0 /* granularity */
297 };
298
299 ext = pmap_trm_alloc(ctob(IOPAGES + 1), M_WAITOK | M_ZERO);
300 /* -16 is so we can convert a trapframe into vm86trapframe inplace */
301 ext->ext_tss.tss_ss0 = GSEL(GDATA_SEL, SEL_KPL);
302 /*
303 * The last byte of the i/o map must be followed by an 0xff byte.
304 * We arbitrarily allocate 16 bytes here, to keep the starting
305 * address on a doubleword boundary.
306 */
307 offset = PAGE_SIZE - 16;
308 ext->ext_tss.tss_ioopt =
309 (offset - ((unsigned)&ext->ext_tss - (unsigned)ext)) << 16;
310 ext->ext_iomap = (caddr_t)ext + offset;
311 ext->ext_vm86.vm86_intmap = (caddr_t)ext + offset - 32;
312
313 addr = (u_long *)ext->ext_vm86.vm86_intmap;
314 for (i = 0; i < (ctob(IOPAGES) + 32 + 16) / sizeof(u_long); i++)
315 *addr++ = ~0;
316
317 ssd.ssd_base = (unsigned)&ext->ext_tss;
318 ssd.ssd_limit -= ((unsigned)&ext->ext_tss - (unsigned)ext);
319 ssdtosd(&ssd, &ext->ext_tssd);
320
321 KASSERT(td == curthread, ("giving TSS to !curthread"));
322 KASSERT(td->td_pcb->pcb_ext == 0, ("already have a TSS!"));
323
324 /* Switch to the new TSS. */
325 critical_enter();
326 ext->ext_tss.tss_esp0 = PCPU_GET(trampstk);
327 td->td_pcb->pcb_ext = ext;
328 PCPU_SET(private_tss, 1);
329 *PCPU_GET(tss_gdt) = ext->ext_tssd;
330 ltr(GSEL(GPROC0_SEL, SEL_KPL));
331 critical_exit();
332
333 return 0;
334 }
335
336 int
i386_set_ioperm(struct thread * td,struct i386_ioperm_args * uap)337 i386_set_ioperm(struct thread *td, struct i386_ioperm_args *uap)
338 {
339 char *iomap;
340 u_int i;
341 int error;
342
343 if ((error = priv_check(td, PRIV_IO)) != 0)
344 return (error);
345 if ((error = securelevel_gt(td->td_ucred, 0)) != 0)
346 return (error);
347 /*
348 * XXX
349 * While this is restricted to root, we should probably figure out
350 * whether any other driver is using this i/o address, as so not to
351 * cause confusion. This probably requires a global 'usage registry'.
352 */
353
354 if (td->td_pcb->pcb_ext == 0)
355 if ((error = i386_extend_pcb(td)) != 0)
356 return (error);
357 iomap = (char *)td->td_pcb->pcb_ext->ext_iomap;
358
359 if (uap->start > uap->start + uap->length ||
360 uap->start + uap->length > IOPAGES * PAGE_SIZE * NBBY)
361 return (EINVAL);
362
363 for (i = uap->start; i < uap->start + uap->length; i++) {
364 if (uap->enable)
365 iomap[i >> 3] &= ~(1 << (i & 7));
366 else
367 iomap[i >> 3] |= (1 << (i & 7));
368 }
369 return (error);
370 }
371
372 int
i386_get_ioperm(struct thread * td,struct i386_ioperm_args * uap)373 i386_get_ioperm(struct thread *td, struct i386_ioperm_args *uap)
374 {
375 int i, state;
376 char *iomap;
377
378 if (uap->start >= IOPAGES * PAGE_SIZE * NBBY)
379 return (EINVAL);
380
381 if (td->td_pcb->pcb_ext == 0) {
382 uap->length = 0;
383 goto done;
384 }
385
386 iomap = (char *)td->td_pcb->pcb_ext->ext_iomap;
387
388 i = uap->start;
389 state = (iomap[i >> 3] >> (i & 7)) & 1;
390 uap->enable = !state;
391 uap->length = 1;
392
393 for (i = uap->start + 1; i < IOPAGES * PAGE_SIZE * NBBY; i++) {
394 if (state != ((iomap[i >> 3] >> (i & 7)) & 1))
395 break;
396 uap->length++;
397 }
398
399 done:
400 return (0);
401 }
402
403 /*
404 * Update the GDT entry pointing to the LDT to point to the LDT of the
405 * current process. Manage dt_lock holding/unholding autonomously.
406 */
407 static void
set_user_ldt_locked(struct mdproc * mdp)408 set_user_ldt_locked(struct mdproc *mdp)
409 {
410 struct proc_ldt *pldt;
411 int gdt_idx;
412
413 mtx_assert(&dt_lock, MA_OWNED);
414
415 pldt = mdp->md_ldt;
416 gdt_idx = GUSERLDT_SEL;
417 gdt_idx += PCPU_GET(cpuid) * NGDT; /* always 0 on UP */
418 gdt[gdt_idx].sd = pldt->ldt_sd;
419 lldt(GSEL(GUSERLDT_SEL, SEL_KPL));
420 PCPU_SET(currentldt, GSEL(GUSERLDT_SEL, SEL_KPL));
421 }
422
423 void
set_user_ldt(struct mdproc * mdp)424 set_user_ldt(struct mdproc *mdp)
425 {
426
427 mtx_lock_spin(&dt_lock);
428 set_user_ldt_locked(mdp);
429 mtx_unlock_spin(&dt_lock);
430 }
431
432 #ifdef SMP
433 static void
set_user_ldt_rv(void * arg)434 set_user_ldt_rv(void *arg)
435 {
436 struct proc *p;
437
438 p = curproc;
439 if (arg == p->p_vmspace)
440 set_user_ldt(&p->p_md);
441 }
442 #endif
443
444 /*
445 * dt_lock must be held. Returns with dt_lock held.
446 */
447 struct proc_ldt *
user_ldt_alloc(struct mdproc * mdp,int len)448 user_ldt_alloc(struct mdproc *mdp, int len)
449 {
450 struct proc_ldt *pldt, *new_ldt;
451
452 mtx_assert(&dt_lock, MA_OWNED);
453 mtx_unlock_spin(&dt_lock);
454 new_ldt = malloc(sizeof(struct proc_ldt), M_SUBPROC, M_WAITOK);
455
456 new_ldt->ldt_len = len = NEW_MAX_LD(len);
457 new_ldt->ldt_base = pmap_trm_alloc(len * sizeof(union descriptor),
458 M_WAITOK | M_ZERO);
459 new_ldt->ldt_refcnt = 1;
460 new_ldt->ldt_active = 0;
461
462 mtx_lock_spin(&dt_lock);
463 gdt_segs[GUSERLDT_SEL].ssd_base = (unsigned)new_ldt->ldt_base;
464 gdt_segs[GUSERLDT_SEL].ssd_limit = len * sizeof(union descriptor) - 1;
465 ssdtosd(&gdt_segs[GUSERLDT_SEL], &new_ldt->ldt_sd);
466
467 if ((pldt = mdp->md_ldt) != NULL) {
468 if (len > pldt->ldt_len)
469 len = pldt->ldt_len;
470 bcopy(pldt->ldt_base, new_ldt->ldt_base,
471 len * sizeof(union descriptor));
472 } else
473 bcopy(ldt, new_ldt->ldt_base, sizeof(union descriptor) * NLDT);
474
475 return (new_ldt);
476 }
477
478 /*
479 * Must be called with dt_lock held. Returns with dt_lock unheld.
480 */
481 void
user_ldt_free(struct thread * td)482 user_ldt_free(struct thread *td)
483 {
484 struct mdproc *mdp;
485 struct proc_ldt *pldt;
486
487 mtx_assert(&dt_lock, MA_OWNED);
488 mdp = &td->td_proc->p_md;
489 if ((pldt = mdp->md_ldt) == NULL) {
490 mtx_unlock_spin(&dt_lock);
491 return;
492 }
493
494 if (td == curthread) {
495 lldt(_default_ldt);
496 PCPU_SET(currentldt, _default_ldt);
497 }
498
499 mdp->md_ldt = NULL;
500 user_ldt_deref(pldt);
501 }
502
503 void
user_ldt_deref(struct proc_ldt * pldt)504 user_ldt_deref(struct proc_ldt *pldt)
505 {
506
507 mtx_assert(&dt_lock, MA_OWNED);
508 if (--pldt->ldt_refcnt == 0) {
509 mtx_unlock_spin(&dt_lock);
510 pmap_trm_free(pldt->ldt_base, pldt->ldt_len *
511 sizeof(union descriptor));
512 free(pldt, M_SUBPROC);
513 } else
514 mtx_unlock_spin(&dt_lock);
515 }
516
517 /*
518 * Note for the authors of compat layers (linux, etc): copyout() in
519 * the function below is not a problem since it presents data in
520 * arch-specific format (i.e. i386-specific in this case), not in
521 * the OS-specific one.
522 */
523 int
i386_get_ldt(struct thread * td,struct i386_ldt_args * uap)524 i386_get_ldt(struct thread *td, struct i386_ldt_args *uap)
525 {
526 struct proc_ldt *pldt;
527 char *data;
528 u_int nldt, num;
529 int error;
530
531 #ifdef DEBUG
532 printf("i386_get_ldt: start=%u num=%u descs=%p\n",
533 uap->start, uap->num, (void *)uap->descs);
534 #endif
535
536 num = min(uap->num, MAX_LD);
537 data = malloc(num * sizeof(union descriptor), M_TEMP, M_WAITOK);
538 mtx_lock_spin(&dt_lock);
539 pldt = td->td_proc->p_md.md_ldt;
540 nldt = pldt != NULL ? pldt->ldt_len : NLDT;
541 if (uap->start >= nldt) {
542 num = 0;
543 } else {
544 num = min(num, nldt - uap->start);
545 bcopy(pldt != NULL ?
546 &((union descriptor *)(pldt->ldt_base))[uap->start] :
547 &ldt[uap->start], data, num * sizeof(union descriptor));
548 }
549 mtx_unlock_spin(&dt_lock);
550 error = copyout(data, uap->descs, num * sizeof(union descriptor));
551 if (error == 0)
552 td->td_retval[0] = num;
553 free(data, M_TEMP);
554 return (error);
555 }
556
557 int
i386_set_ldt(struct thread * td,struct i386_ldt_args * uap,union descriptor * descs)558 i386_set_ldt(struct thread *td, struct i386_ldt_args *uap,
559 union descriptor *descs)
560 {
561 struct mdproc *mdp;
562 struct proc_ldt *pldt;
563 union descriptor *dp;
564 u_int largest_ld, i;
565 int error;
566
567 #ifdef DEBUG
568 printf("i386_set_ldt: start=%u num=%u descs=%p\n",
569 uap->start, uap->num, (void *)uap->descs);
570 #endif
571 error = 0;
572 mdp = &td->td_proc->p_md;
573
574 if (descs == NULL) {
575 /* Free descriptors */
576 if (uap->start == 0 && uap->num == 0) {
577 /*
578 * Treat this as a special case, so userland needn't
579 * know magic number NLDT.
580 */
581 uap->start = NLDT;
582 uap->num = MAX_LD - NLDT;
583 }
584 mtx_lock_spin(&dt_lock);
585 if ((pldt = mdp->md_ldt) == NULL ||
586 uap->start >= pldt->ldt_len) {
587 mtx_unlock_spin(&dt_lock);
588 return (0);
589 }
590 largest_ld = uap->start + uap->num;
591 if (largest_ld > pldt->ldt_len)
592 largest_ld = pldt->ldt_len;
593 for (i = uap->start; i < largest_ld; i++)
594 atomic_store_rel_64(&((uint64_t *)(pldt->ldt_base))[i],
595 0);
596 mtx_unlock_spin(&dt_lock);
597 return (0);
598 }
599
600 if (uap->start != LDT_AUTO_ALLOC || uap->num != 1) {
601 /* verify range of descriptors to modify */
602 largest_ld = uap->start + uap->num;
603 if (uap->start >= MAX_LD || largest_ld > MAX_LD)
604 return (EINVAL);
605 }
606
607 /* Check descriptors for access violations */
608 for (i = 0; i < uap->num; i++) {
609 dp = &descs[i];
610
611 switch (dp->sd.sd_type) {
612 case SDT_SYSNULL: /* system null */
613 dp->sd.sd_p = 0;
614 break;
615 case SDT_SYS286TSS: /* system 286 TSS available */
616 case SDT_SYSLDT: /* system local descriptor table */
617 case SDT_SYS286BSY: /* system 286 TSS busy */
618 case SDT_SYSTASKGT: /* system task gate */
619 case SDT_SYS286IGT: /* system 286 interrupt gate */
620 case SDT_SYS286TGT: /* system 286 trap gate */
621 case SDT_SYSNULL2: /* undefined by Intel */
622 case SDT_SYS386TSS: /* system 386 TSS available */
623 case SDT_SYSNULL3: /* undefined by Intel */
624 case SDT_SYS386BSY: /* system 386 TSS busy */
625 case SDT_SYSNULL4: /* undefined by Intel */
626 case SDT_SYS386IGT: /* system 386 interrupt gate */
627 case SDT_SYS386TGT: /* system 386 trap gate */
628 case SDT_SYS286CGT: /* system 286 call gate */
629 case SDT_SYS386CGT: /* system 386 call gate */
630 return (EACCES);
631
632 /* memory segment types */
633 case SDT_MEMEC: /* memory execute only conforming */
634 case SDT_MEMEAC: /* memory execute only accessed conforming */
635 case SDT_MEMERC: /* memory execute read conforming */
636 case SDT_MEMERAC: /* memory execute read accessed conforming */
637 /* Must be "present" if executable and conforming. */
638 if (dp->sd.sd_p == 0)
639 return (EACCES);
640 break;
641 case SDT_MEMRO: /* memory read only */
642 case SDT_MEMROA: /* memory read only accessed */
643 case SDT_MEMRW: /* memory read write */
644 case SDT_MEMRWA: /* memory read write accessed */
645 case SDT_MEMROD: /* memory read only expand dwn limit */
646 case SDT_MEMRODA: /* memory read only expand dwn lim accessed */
647 case SDT_MEMRWD: /* memory read write expand dwn limit */
648 case SDT_MEMRWDA: /* memory read write expand dwn lim acessed */
649 case SDT_MEME: /* memory execute only */
650 case SDT_MEMEA: /* memory execute only accessed */
651 case SDT_MEMER: /* memory execute read */
652 case SDT_MEMERA: /* memory execute read accessed */
653 break;
654 default:
655 return (EINVAL);
656 }
657
658 /* Only user (ring-3) descriptors may be present. */
659 if (dp->sd.sd_p != 0 && dp->sd.sd_dpl != SEL_UPL)
660 return (EACCES);
661 }
662
663 if (uap->start == LDT_AUTO_ALLOC && uap->num == 1) {
664 /* Allocate a free slot */
665 mtx_lock_spin(&dt_lock);
666 if ((pldt = mdp->md_ldt) == NULL) {
667 if ((error = i386_ldt_grow(td, NLDT + 1))) {
668 mtx_unlock_spin(&dt_lock);
669 return (error);
670 }
671 pldt = mdp->md_ldt;
672 }
673 again:
674 /*
675 * start scanning a bit up to leave room for NVidia and
676 * Wine, which still user the "Blat" method of allocation.
677 */
678 dp = &((union descriptor *)(pldt->ldt_base))[NLDT];
679 for (i = NLDT; i < pldt->ldt_len; ++i) {
680 if (dp->sd.sd_type == SDT_SYSNULL)
681 break;
682 dp++;
683 }
684 if (i >= pldt->ldt_len) {
685 if ((error = i386_ldt_grow(td, pldt->ldt_len+1))) {
686 mtx_unlock_spin(&dt_lock);
687 return (error);
688 }
689 goto again;
690 }
691 uap->start = i;
692 error = i386_set_ldt_data(td, i, 1, descs);
693 mtx_unlock_spin(&dt_lock);
694 } else {
695 largest_ld = uap->start + uap->num;
696 mtx_lock_spin(&dt_lock);
697 if (!(error = i386_ldt_grow(td, largest_ld))) {
698 error = i386_set_ldt_data(td, uap->start, uap->num,
699 descs);
700 }
701 mtx_unlock_spin(&dt_lock);
702 }
703 if (error == 0)
704 td->td_retval[0] = uap->start;
705 return (error);
706 }
707
708 static int
i386_set_ldt_data(struct thread * td,int start,int num,union descriptor * descs)709 i386_set_ldt_data(struct thread *td, int start, int num,
710 union descriptor *descs)
711 {
712 struct mdproc *mdp;
713 struct proc_ldt *pldt;
714 uint64_t *dst, *src;
715 int i;
716
717 mtx_assert(&dt_lock, MA_OWNED);
718
719 mdp = &td->td_proc->p_md;
720 pldt = mdp->md_ldt;
721 dst = (uint64_t *)(pldt->ldt_base);
722 src = (uint64_t *)descs;
723
724 /*
725 * Atomic(9) is used only to get 64bit atomic store with
726 * cmpxchg8b when available. There is no op without release
727 * semantic.
728 */
729 for (i = 0; i < num; i++)
730 atomic_store_rel_64(&dst[start + i], src[i]);
731 return (0);
732 }
733
734 static int
i386_ldt_grow(struct thread * td,int len)735 i386_ldt_grow(struct thread *td, int len)
736 {
737 struct mdproc *mdp;
738 struct proc_ldt *new_ldt, *pldt;
739 caddr_t old_ldt_base;
740 int old_ldt_len;
741
742 mtx_assert(&dt_lock, MA_OWNED);
743
744 if (len > MAX_LD)
745 return (ENOMEM);
746 if (len < NLDT + 1)
747 len = NLDT + 1;
748
749 mdp = &td->td_proc->p_md;
750 old_ldt_base = NULL_LDT_BASE;
751 old_ldt_len = 0;
752
753 /* Allocate a user ldt. */
754 if ((pldt = mdp->md_ldt) == NULL || len > pldt->ldt_len) {
755 new_ldt = user_ldt_alloc(mdp, len);
756 if (new_ldt == NULL)
757 return (ENOMEM);
758 pldt = mdp->md_ldt;
759
760 if (pldt != NULL) {
761 if (new_ldt->ldt_len <= pldt->ldt_len) {
762 /*
763 * We just lost the race for allocation, so
764 * free the new object and return.
765 */
766 mtx_unlock_spin(&dt_lock);
767 pmap_trm_free(new_ldt->ldt_base,
768 new_ldt->ldt_len * sizeof(union descriptor));
769 free(new_ldt, M_SUBPROC);
770 mtx_lock_spin(&dt_lock);
771 return (0);
772 }
773
774 /*
775 * We have to substitute the current LDT entry for
776 * curproc with the new one since its size grew.
777 */
778 old_ldt_base = pldt->ldt_base;
779 old_ldt_len = pldt->ldt_len;
780 pldt->ldt_sd = new_ldt->ldt_sd;
781 pldt->ldt_base = new_ldt->ldt_base;
782 pldt->ldt_len = new_ldt->ldt_len;
783 } else
784 mdp->md_ldt = pldt = new_ldt;
785 #ifdef SMP
786 /*
787 * Signal other cpus to reload ldt. We need to unlock dt_lock
788 * here because other CPU will contest on it since their
789 * curthreads won't hold the lock and will block when trying
790 * to acquire it.
791 */
792 mtx_unlock_spin(&dt_lock);
793 smp_rendezvous(NULL, set_user_ldt_rv, NULL,
794 td->td_proc->p_vmspace);
795 #else
796 set_user_ldt_locked(&td->td_proc->p_md);
797 mtx_unlock_spin(&dt_lock);
798 #endif
799 if (old_ldt_base != NULL_LDT_BASE) {
800 pmap_trm_free(old_ldt_base, old_ldt_len *
801 sizeof(union descriptor));
802 free(new_ldt, M_SUBPROC);
803 }
804 mtx_lock_spin(&dt_lock);
805 }
806 return (0);
807 }
808