1 /* 2 * Copyright (c) 1982, 1986, 1989, 1990, 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * (c) UNIX System Laboratories, Inc. 5 * All or some portions of this file are derived from material licensed 6 * to the University of California by American Telephone and Telegraph 7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8 * the permission of UNIX System Laboratories, Inc. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)kern_prot.c 8.6 (Berkeley) 1/21/94 35 * $FreeBSD: src/sys/kern/kern_prot.c,v 1.53.2.9 2002/03/09 05:20:26 dd Exp $ 36 */ 37 38 /* 39 * System calls related to processes and protection 40 */ 41 42 #include <sys/param.h> 43 #include <sys/acct.h> 44 #include <sys/systm.h> 45 #include <sys/sysproto.h> 46 #include <sys/kernel.h> 47 #include <sys/lock.h> 48 #include <sys/proc.h> 49 #include <sys/priv.h> 50 #include <sys/malloc.h> 51 #include <sys/pioctl.h> 52 #include <sys/resourcevar.h> 53 #include <sys/jail.h> 54 #include <sys/lockf.h> 55 #include <sys/spinlock.h> 56 57 #include <sys/spinlock2.h> 58 59 static MALLOC_DEFINE(M_CRED, "cred", "credentials"); 60 61 int 62 sys_getpid(struct getpid_args *uap) 63 { 64 struct proc *p = curproc; 65 66 uap->sysmsg_fds[0] = p->p_pid; 67 return (0); 68 } 69 70 int 71 sys_getppid(struct getppid_args *uap) 72 { 73 struct proc *p = curproc; 74 75 uap->sysmsg_result = p->p_ppid; 76 77 return (0); 78 } 79 80 int 81 sys_lwp_gettid(struct lwp_gettid_args *uap) 82 { 83 struct lwp *lp = curthread->td_lwp; 84 uap->sysmsg_result = lp->lwp_tid; 85 return (0); 86 } 87 88 /* 89 * Get process group ID; note that POSIX getpgrp takes no parameter 90 */ 91 int 92 sys_getpgrp(struct getpgrp_args *uap) 93 { 94 struct proc *p = curproc; 95 96 lwkt_gettoken_shared(&p->p_token); 97 uap->sysmsg_result = p->p_pgrp->pg_id; 98 lwkt_reltoken(&p->p_token); 99 100 return (0); 101 } 102 103 /* 104 * Get an arbitrary pid's process group id 105 */ 106 int 107 sys_getpgid(struct getpgid_args *uap) 108 { 109 struct proc *p = curproc; 110 struct proc *pt; 111 int error; 112 113 error = 0; 114 115 if (uap->pid == 0) { 116 pt = p; 117 PHOLD(pt); 118 } else { 119 pt = pfind(uap->pid); 120 if (pt == NULL) 121 error = ESRCH; 122 } 123 if (error == 0) { 124 lwkt_gettoken_shared(&pt->p_token); 125 uap->sysmsg_result = pt->p_pgrp->pg_id; 126 lwkt_reltoken(&pt->p_token); 127 } 128 if (pt) 129 PRELE(pt); 130 return (error); 131 } 132 133 /* 134 * Get an arbitrary pid's session id. 135 */ 136 int 137 sys_getsid(struct getsid_args *uap) 138 { 139 struct proc *p = curproc; 140 struct proc *pt; 141 int error; 142 143 error = 0; 144 145 if (uap->pid == 0) { 146 pt = p; 147 PHOLD(pt); 148 } else { 149 pt = pfind(uap->pid); 150 if (pt == NULL) 151 error = ESRCH; 152 } 153 if (error == 0) 154 uap->sysmsg_result = pt->p_session->s_sid; 155 if (pt) 156 PRELE(pt); 157 return (error); 158 } 159 160 161 /* 162 * getuid() 163 */ 164 int 165 sys_getuid(struct getuid_args *uap) 166 { 167 struct ucred *cred = curthread->td_ucred; 168 169 uap->sysmsg_fds[0] = cred->cr_ruid; 170 return (0); 171 } 172 173 /* 174 * geteuid() 175 */ 176 int 177 sys_geteuid(struct geteuid_args *uap) 178 { 179 struct ucred *cred = curthread->td_ucred; 180 181 uap->sysmsg_result = cred->cr_uid; 182 return (0); 183 } 184 185 /* 186 * getgid() 187 */ 188 int 189 sys_getgid(struct getgid_args *uap) 190 { 191 struct ucred *cred = curthread->td_ucred; 192 193 uap->sysmsg_fds[0] = cred->cr_rgid; 194 return (0); 195 } 196 197 /* 198 * Get effective group ID. The "egid" is groups[0], and could be obtained 199 * via getgroups. This syscall exists because it is somewhat painful to do 200 * correctly in a library function. 201 */ 202 int 203 sys_getegid(struct getegid_args *uap) 204 { 205 struct ucred *cred = curthread->td_ucred; 206 207 uap->sysmsg_result = cred->cr_groups[0]; 208 return (0); 209 } 210 211 int 212 sys_getgroups(struct getgroups_args *uap) 213 { 214 struct ucred *cr; 215 u_int ngrp; 216 int error; 217 218 cr = curthread->td_ucred; 219 if ((ngrp = uap->gidsetsize) == 0) { 220 uap->sysmsg_result = cr->cr_ngroups; 221 return (0); 222 } 223 if (ngrp < cr->cr_ngroups) 224 return (EINVAL); 225 ngrp = cr->cr_ngroups; 226 error = copyout((caddr_t)cr->cr_groups, 227 (caddr_t)uap->gidset, ngrp * sizeof(gid_t)); 228 if (error == 0) 229 uap->sysmsg_result = ngrp; 230 return (error); 231 } 232 233 int 234 sys_lwp_setname(struct lwp_setname_args *uap) 235 { 236 struct proc *p = curproc; 237 struct lwp *lp; 238 char buf[LPMAP_MAXTHREADTITLE]; 239 int error; 240 size_t len; 241 242 if (uap->name != NULL) { 243 error = copyinstr(uap->name, buf, sizeof(buf), &len); 244 if (error) { 245 if (error != ENAMETOOLONG) 246 return error; 247 buf[sizeof(buf)-1] = 0; 248 len = sizeof(buf) - 1; 249 } 250 } else { 251 buf[0] = 0; 252 len = 1; 253 } 254 255 lwkt_gettoken(&p->p_token); 256 257 lp = lwpfind(p, uap->tid); 258 if (lp) { 259 lwkt_gettoken(&lp->lwp_token); 260 if (lp->lwp_lpmap == NULL) 261 lwp_usermap(lp, -1); 262 if (lp->lwp_lpmap) 263 bcopy(buf, lp->lwp_lpmap->thread_title, len); 264 lwkt_reltoken(&lp->lwp_token); 265 LWPRELE(lp); 266 error = 0; 267 } else { 268 error = ESRCH; 269 } 270 271 lwkt_reltoken(&p->p_token); 272 273 return error; 274 } 275 276 int 277 sys_setsid(struct setsid_args *uap) 278 { 279 struct proc *p = curproc; 280 struct pgrp *pg = NULL; 281 int error; 282 283 lwkt_gettoken(&p->p_token); 284 if (p->p_pgid == p->p_pid || (pg = pgfind(p->p_pid)) != NULL) { 285 error = EPERM; 286 if (pg) 287 pgrel(pg); 288 } else { 289 enterpgrp(p, p->p_pid, 1); 290 uap->sysmsg_result = p->p_pid; 291 error = 0; 292 } 293 lwkt_reltoken(&p->p_token); 294 return (error); 295 } 296 297 /* 298 * set process group (setpgid/old setpgrp) 299 * 300 * caller does setpgid(targpid, targpgid) 301 * 302 * pid must be caller or child of caller (ESRCH) 303 * if a child 304 * pid must be in same session (EPERM) 305 * pid can't have done an exec (EACCES) 306 * if pgid != pid 307 * there must exist some pid in same session having pgid (EPERM) 308 * pid must not be session leader (EPERM) 309 */ 310 int 311 sys_setpgid(struct setpgid_args *uap) 312 { 313 struct proc *curp = curproc; 314 struct proc *targp; /* target process */ 315 struct pgrp *pgrp = NULL; /* target pgrp */ 316 int error; 317 318 if (uap->pgid < 0) 319 return (EINVAL); 320 321 if (uap->pid != 0 && uap->pid != curp->p_pid) { 322 if ((targp = pfind(uap->pid)) == NULL || !inferior(targp)) { 323 if (targp) 324 PRELE(targp); 325 error = ESRCH; 326 targp = NULL; 327 goto done; 328 } 329 lwkt_gettoken(&targp->p_token); 330 /* targp now referenced and its token is held */ 331 332 if (targp->p_pgrp == NULL || 333 targp->p_session != curp->p_session) { 334 error = EPERM; 335 goto done; 336 } 337 if (targp->p_flags & P_EXEC) { 338 error = EACCES; 339 goto done; 340 } 341 } else { 342 targp = curp; 343 PHOLD(targp); 344 lwkt_gettoken(&targp->p_token); 345 } 346 if (SESS_LEADER(targp)) { 347 error = EPERM; 348 goto done; 349 } 350 if (uap->pgid == 0) { 351 uap->pgid = targp->p_pid; 352 } else if (uap->pgid != targp->p_pid) { 353 if ((pgrp = pgfind(uap->pgid)) == NULL || 354 pgrp->pg_session != curp->p_session) { 355 error = EPERM; 356 goto done; 357 } 358 } 359 error = enterpgrp(targp, uap->pgid, 0); 360 done: 361 if (pgrp) 362 pgrel(pgrp); 363 if (targp) { 364 lwkt_reltoken(&targp->p_token); 365 PRELE(targp); 366 } 367 return (error); 368 } 369 370 /* 371 * Use the clause in B.4.2.2 that allows setuid/setgid to be 4.2/4.3BSD 372 * compatible. It says that setting the uid/gid to euid/egid is a special 373 * case of "appropriate privilege". Once the rules are expanded out, this 374 * basically means that setuid(nnn) sets all three id's, in all permitted 375 * cases unless _POSIX_SAVED_IDS is enabled. In that case, setuid(getuid()) 376 * does not set the saved id - this is dangerous for traditional BSD 377 * programs. For this reason, we *really* do not want to set 378 * _POSIX_SAVED_IDS and do not want to clear POSIX_APPENDIX_B_4_2_2. 379 */ 380 #define POSIX_APPENDIX_B_4_2_2 381 382 int 383 sys_setuid(struct setuid_args *uap) 384 { 385 struct proc *p = curproc; 386 struct ucred *cr; 387 uid_t uid; 388 int error; 389 390 lwkt_gettoken(&p->p_token); 391 cr = p->p_ucred; 392 393 /* 394 * See if we have "permission" by POSIX 1003.1 rules. 395 * 396 * Note that setuid(geteuid()) is a special case of 397 * "appropriate privileges" in appendix B.4.2.2. We need 398 * to use this clause to be compatible with traditional BSD 399 * semantics. Basically, it means that "setuid(xx)" sets all 400 * three id's (assuming you have privs). 401 * 402 * Notes on the logic. We do things in three steps. 403 * 1: We determine if the euid is going to change, and do EPERM 404 * right away. We unconditionally change the euid later if this 405 * test is satisfied, simplifying that part of the logic. 406 * 2: We determine if the real and/or saved uid's are going to 407 * change. Determined by compile options. 408 * 3: Change euid last. (after tests in #2 for "appropriate privs") 409 */ 410 uid = uap->uid; 411 if (uid != cr->cr_ruid && /* allow setuid(getuid()) */ 412 #ifdef _POSIX_SAVED_IDS 413 uid != crc->cr_svuid && /* allow setuid(saved gid) */ 414 #endif 415 #ifdef POSIX_APPENDIX_B_4_2_2 /* Use BSD-compat clause from B.4.2.2 */ 416 uid != cr->cr_uid && /* allow setuid(geteuid()) */ 417 #endif 418 (error = priv_check_cred(cr, PRIV_CRED_SETUID, 0))) 419 goto done; 420 421 #ifdef _POSIX_SAVED_IDS 422 /* 423 * Do we have "appropriate privileges" (are we root or uid == euid) 424 * If so, we are changing the real uid and/or saved uid. 425 */ 426 if ( 427 #ifdef POSIX_APPENDIX_B_4_2_2 /* Use the clause from B.4.2.2 */ 428 uid == cr->cr_uid || 429 #endif 430 priv_check_cred(cr, PRIV_CRED_SETUID, 0) == 0) /* we are using privs */ 431 #endif 432 { 433 /* 434 * Set the real uid and transfer proc count to new user. 435 */ 436 if (uid != cr->cr_ruid) { 437 cr = change_ruid(uid); 438 setsugid(); 439 } 440 /* 441 * Set saved uid 442 * 443 * XXX always set saved uid even if not _POSIX_SAVED_IDS, as 444 * the security of seteuid() depends on it. B.4.2.2 says it 445 * is important that we should do this. 446 */ 447 if (cr->cr_svuid != uid) { 448 cr = cratom_proc(p); 449 cr->cr_svuid = uid; 450 setsugid(); 451 } 452 } 453 454 /* 455 * In all permitted cases, we are changing the euid. 456 * Copy credentials so other references do not see our changes. 457 */ 458 if (cr->cr_uid != uid) { 459 change_euid(uid); 460 setsugid(); 461 } 462 error = 0; 463 done: 464 lwkt_reltoken(&p->p_token); 465 return (error); 466 } 467 468 int 469 sys_seteuid(struct seteuid_args *uap) 470 { 471 struct proc *p = curproc; 472 struct ucred *cr; 473 uid_t euid; 474 int error; 475 476 lwkt_gettoken(&p->p_token); 477 cr = p->p_ucred; 478 euid = uap->euid; 479 if (euid != cr->cr_ruid && /* allow seteuid(getuid()) */ 480 euid != cr->cr_svuid && /* allow seteuid(saved uid) */ 481 (error = priv_check_cred(cr, PRIV_CRED_SETEUID, 0))) { 482 lwkt_reltoken(&p->p_token); 483 return (error); 484 } 485 486 /* 487 * Everything's okay, do it. Copy credentials so other references do 488 * not see our changes. 489 */ 490 if (cr->cr_uid != euid) { 491 change_euid(euid); 492 setsugid(); 493 } 494 lwkt_reltoken(&p->p_token); 495 return (0); 496 } 497 498 int 499 sys_setgid(struct setgid_args *uap) 500 { 501 struct proc *p = curproc; 502 struct ucred *cr; 503 gid_t gid; 504 int error; 505 506 lwkt_gettoken(&p->p_token); 507 cr = p->p_ucred; 508 509 /* 510 * See if we have "permission" by POSIX 1003.1 rules. 511 * 512 * Note that setgid(getegid()) is a special case of 513 * "appropriate privileges" in appendix B.4.2.2. We need 514 * to use this clause to be compatible with traditional BSD 515 * semantics. Basically, it means that "setgid(xx)" sets all 516 * three id's (assuming you have privs). 517 * 518 * For notes on the logic here, see setuid() above. 519 */ 520 gid = uap->gid; 521 if (gid != cr->cr_rgid && /* allow setgid(getgid()) */ 522 #ifdef _POSIX_SAVED_IDS 523 gid != cr->cr_svgid && /* allow setgid(saved gid) */ 524 #endif 525 #ifdef POSIX_APPENDIX_B_4_2_2 /* Use BSD-compat clause from B.4.2.2 */ 526 gid != cr->cr_groups[0] && /* allow setgid(getegid()) */ 527 #endif 528 (error = priv_check_cred(cr, PRIV_CRED_SETGID, 0))) { 529 goto done; 530 } 531 532 #ifdef _POSIX_SAVED_IDS 533 /* 534 * Do we have "appropriate privileges" (are we root or gid == egid) 535 * If so, we are changing the real uid and saved gid. 536 */ 537 if ( 538 #ifdef POSIX_APPENDIX_B_4_2_2 /* use the clause from B.4.2.2 */ 539 gid == cr->cr_groups[0] || 540 #endif 541 priv_check_cred(cr, PRIV_CRED_SETGID, 0) == 0) /* we are using privs */ 542 #endif 543 { 544 /* 545 * Set real gid 546 */ 547 if (cr->cr_rgid != gid) { 548 cr = cratom_proc(p); 549 cr->cr_rgid = gid; 550 setsugid(); 551 } 552 /* 553 * Set saved gid 554 * 555 * XXX always set saved gid even if not _POSIX_SAVED_IDS, as 556 * the security of setegid() depends on it. B.4.2.2 says it 557 * is important that we should do this. 558 */ 559 if (cr->cr_svgid != gid) { 560 cr = cratom_proc(p); 561 cr->cr_svgid = gid; 562 setsugid(); 563 } 564 } 565 /* 566 * In all cases permitted cases, we are changing the egid. 567 * Copy credentials so other references do not see our changes. 568 */ 569 if (cr->cr_groups[0] != gid) { 570 cr = cratom_proc(p); 571 cr->cr_groups[0] = gid; 572 setsugid(); 573 } 574 error = 0; 575 done: 576 lwkt_reltoken(&p->p_token); 577 return (error); 578 } 579 580 int 581 sys_setegid(struct setegid_args *uap) 582 { 583 struct proc *p = curproc; 584 struct ucred *cr; 585 gid_t egid; 586 int error; 587 588 lwkt_gettoken(&p->p_token); 589 cr = p->p_ucred; 590 egid = uap->egid; 591 if (egid != cr->cr_rgid && /* allow setegid(getgid()) */ 592 egid != cr->cr_svgid && /* allow setegid(saved gid) */ 593 (error = priv_check_cred(cr, PRIV_CRED_SETEGID, 0))) { 594 goto done; 595 } 596 if (cr->cr_groups[0] != egid) { 597 cr = cratom_proc(p); 598 cr->cr_groups[0] = egid; 599 setsugid(); 600 } 601 error = 0; 602 done: 603 lwkt_reltoken(&p->p_token); 604 return (error); 605 } 606 607 int 608 sys_setgroups(struct setgroups_args *uap) 609 { 610 struct proc *p = curproc; 611 struct ucred *cr; 612 u_int ngrp; 613 int error; 614 615 lwkt_gettoken(&p->p_token); 616 cr = p->p_ucred; 617 618 if ((error = priv_check_cred(cr, PRIV_CRED_SETGROUPS, 0))) 619 goto done; 620 ngrp = uap->gidsetsize; 621 if (ngrp > NGROUPS) { 622 error = EINVAL; 623 goto done; 624 } 625 /* 626 * XXX A little bit lazy here. We could test if anything has 627 * changed before cratom() and setting P_SUGID. 628 */ 629 cr = cratom_proc(p); 630 if (ngrp < 1) { 631 /* 632 * setgroups(0, NULL) is a legitimate way of clearing the 633 * groups vector on non-BSD systems (which generally do not 634 * have the egid in the groups[0]). We risk security holes 635 * when running non-BSD software if we do not do the same. 636 */ 637 cr->cr_ngroups = 1; 638 } else { 639 error = copyin(uap->gidset, cr->cr_groups, 640 ngrp * sizeof(gid_t)); 641 if (error) 642 goto done; 643 cr->cr_ngroups = ngrp; 644 } 645 setsugid(); 646 error = 0; 647 done: 648 lwkt_reltoken(&p->p_token); 649 return (error); 650 } 651 652 int 653 sys_setreuid(struct setreuid_args *uap) 654 { 655 struct proc *p = curproc; 656 struct ucred *cr; 657 uid_t ruid, euid; 658 int error; 659 660 lwkt_gettoken(&p->p_token); 661 cr = p->p_ucred; 662 663 ruid = uap->ruid; 664 euid = uap->euid; 665 if (((ruid != (uid_t)-1 && ruid != cr->cr_ruid && 666 ruid != cr->cr_svuid) || 667 (euid != (uid_t)-1 && euid != cr->cr_uid && 668 euid != cr->cr_ruid && euid != cr->cr_svuid)) && 669 (error = priv_check_cred(cr, PRIV_CRED_SETREUID, 0)) != 0) { 670 goto done; 671 } 672 673 if (euid != (uid_t)-1 && cr->cr_uid != euid) { 674 cr = change_euid(euid); 675 setsugid(); 676 } 677 if (ruid != (uid_t)-1 && cr->cr_ruid != ruid) { 678 cr = change_ruid(ruid); 679 setsugid(); 680 } 681 if ((ruid != (uid_t)-1 || cr->cr_uid != cr->cr_ruid) && 682 cr->cr_svuid != cr->cr_uid) { 683 cr = cratom_proc(p); 684 cr->cr_svuid = cr->cr_uid; 685 setsugid(); 686 } 687 error = 0; 688 done: 689 lwkt_reltoken(&p->p_token); 690 return (error); 691 } 692 693 int 694 sys_setregid(struct setregid_args *uap) 695 { 696 struct proc *p = curproc; 697 struct ucred *cr; 698 gid_t rgid, egid; 699 int error; 700 701 lwkt_gettoken(&p->p_token); 702 cr = p->p_ucred; 703 704 rgid = uap->rgid; 705 egid = uap->egid; 706 if (((rgid != (gid_t)-1 && rgid != cr->cr_rgid && 707 rgid != cr->cr_svgid) || 708 (egid != (gid_t)-1 && egid != cr->cr_groups[0] && 709 egid != cr->cr_rgid && egid != cr->cr_svgid)) && 710 (error = priv_check_cred(cr, PRIV_CRED_SETREGID, 0)) != 0) { 711 goto done; 712 } 713 714 if (egid != (gid_t)-1 && cr->cr_groups[0] != egid) { 715 cr = cratom_proc(p); 716 cr->cr_groups[0] = egid; 717 setsugid(); 718 } 719 if (rgid != (gid_t)-1 && cr->cr_rgid != rgid) { 720 cr = cratom_proc(p); 721 cr->cr_rgid = rgid; 722 setsugid(); 723 } 724 if ((rgid != (gid_t)-1 || cr->cr_groups[0] != cr->cr_rgid) && 725 cr->cr_svgid != cr->cr_groups[0]) { 726 cr = cratom_proc(p); 727 cr->cr_svgid = cr->cr_groups[0]; 728 setsugid(); 729 } 730 error = 0; 731 done: 732 lwkt_reltoken(&p->p_token); 733 return (error); 734 } 735 736 /* 737 * setresuid(ruid, euid, suid) is like setreuid except control over the 738 * saved uid is explicit. 739 */ 740 int 741 sys_setresuid(struct setresuid_args *uap) 742 { 743 struct proc *p = curproc; 744 struct ucred *cr; 745 uid_t ruid, euid, suid; 746 int error; 747 748 lwkt_gettoken(&p->p_token); 749 cr = p->p_ucred; 750 751 ruid = uap->ruid; 752 euid = uap->euid; 753 suid = uap->suid; 754 if (((ruid != (uid_t)-1 && ruid != cr->cr_ruid && 755 ruid != cr->cr_svuid && ruid != cr->cr_uid) || 756 (euid != (uid_t)-1 && euid != cr->cr_ruid && 757 euid != cr->cr_svuid && euid != cr->cr_uid) || 758 (suid != (uid_t)-1 && suid != cr->cr_ruid && 759 suid != cr->cr_svuid && suid != cr->cr_uid)) && 760 (error = priv_check_cred(cr, PRIV_CRED_SETRESUID, 0)) != 0) { 761 goto done; 762 } 763 if (euid != (uid_t)-1 && cr->cr_uid != euid) { 764 cr = change_euid(euid); 765 setsugid(); 766 } 767 if (ruid != (uid_t)-1 && cr->cr_ruid != ruid) { 768 cr = change_ruid(ruid); 769 setsugid(); 770 } 771 if (suid != (uid_t)-1 && cr->cr_svuid != suid) { 772 cr = cratom_proc(p); 773 cr->cr_svuid = suid; 774 setsugid(); 775 } 776 error = 0; 777 done: 778 lwkt_reltoken(&p->p_token); 779 return (error); 780 } 781 782 /* 783 * setresgid(rgid, egid, sgid) is like setregid except control over the 784 * saved gid is explicit. 785 */ 786 int 787 sys_setresgid(struct setresgid_args *uap) 788 { 789 struct proc *p = curproc; 790 struct ucred *cr; 791 gid_t rgid, egid, sgid; 792 int error; 793 794 lwkt_gettoken(&p->p_token); 795 cr = p->p_ucred; 796 rgid = uap->rgid; 797 egid = uap->egid; 798 sgid = uap->sgid; 799 if (((rgid != (gid_t)-1 && rgid != cr->cr_rgid && 800 rgid != cr->cr_svgid && rgid != cr->cr_groups[0]) || 801 (egid != (gid_t)-1 && egid != cr->cr_rgid && 802 egid != cr->cr_svgid && egid != cr->cr_groups[0]) || 803 (sgid != (gid_t)-1 && sgid != cr->cr_rgid && 804 sgid != cr->cr_svgid && sgid != cr->cr_groups[0])) && 805 (error = priv_check_cred(cr, PRIV_CRED_SETRESGID, 0)) != 0) { 806 goto done; 807 } 808 809 if (egid != (gid_t)-1 && cr->cr_groups[0] != egid) { 810 cr = cratom_proc(p); 811 cr->cr_groups[0] = egid; 812 setsugid(); 813 } 814 if (rgid != (gid_t)-1 && cr->cr_rgid != rgid) { 815 cr = cratom_proc(p); 816 cr->cr_rgid = rgid; 817 setsugid(); 818 } 819 if (sgid != (gid_t)-1 && cr->cr_svgid != sgid) { 820 cr = cratom_proc(p); 821 cr->cr_svgid = sgid; 822 setsugid(); 823 } 824 error = 0; 825 done: 826 lwkt_reltoken(&p->p_token); 827 return (error); 828 } 829 830 int 831 sys_getresuid(struct getresuid_args *uap) 832 { 833 struct ucred *cr; 834 int error1 = 0, error2 = 0, error3 = 0; 835 836 /* 837 * copyout's can fault synchronously so we cannot use a shared 838 * token here. 839 */ 840 cr = curthread->td_ucred; 841 if (uap->ruid) 842 error1 = copyout((caddr_t)&cr->cr_ruid, 843 (caddr_t)uap->ruid, sizeof(cr->cr_ruid)); 844 if (uap->euid) 845 error2 = copyout((caddr_t)&cr->cr_uid, 846 (caddr_t)uap->euid, sizeof(cr->cr_uid)); 847 if (uap->suid) 848 error3 = copyout((caddr_t)&cr->cr_svuid, 849 (caddr_t)uap->suid, sizeof(cr->cr_svuid)); 850 return error1 ? error1 : (error2 ? error2 : error3); 851 } 852 853 int 854 sys_getresgid(struct getresgid_args *uap) 855 { 856 struct ucred *cr; 857 int error1 = 0, error2 = 0, error3 = 0; 858 859 cr = curthread->td_ucred; 860 if (uap->rgid) 861 error1 = copyout(&cr->cr_rgid, uap->rgid, 862 sizeof(cr->cr_rgid)); 863 if (uap->egid) 864 error2 = copyout(&cr->cr_groups[0], uap->egid, 865 sizeof(cr->cr_groups[0])); 866 if (uap->sgid) 867 error3 = copyout(&cr->cr_svgid, uap->sgid, 868 sizeof(cr->cr_svgid)); 869 return error1 ? error1 : (error2 ? error2 : error3); 870 } 871 872 873 /* 874 * NOTE: OpenBSD sets a P_SUGIDEXEC flag set at execve() time, 875 * we use P_SUGID because we consider changing the owners as 876 * "tainting" as well. 877 * This is significant for procs that start as root and "become" 878 * a user without an exec - programs cannot know *everything* 879 * that libc *might* have put in their data segment. 880 */ 881 int 882 sys_issetugid(struct issetugid_args *uap) 883 { 884 uap->sysmsg_result = (curproc->p_flags & P_SUGID) ? 1 : 0; 885 return (0); 886 } 887 888 /* 889 * Check if gid is a member of the group set. 890 */ 891 int 892 groupmember(gid_t gid, struct ucred *cred) 893 { 894 gid_t *gp; 895 gid_t *egp; 896 897 egp = &(cred->cr_groups[cred->cr_ngroups]); 898 for (gp = cred->cr_groups; gp < egp; gp++) { 899 if (*gp == gid) 900 return (1); 901 } 902 return (0); 903 } 904 905 /* 906 * Test whether the specified credentials have the privilege 907 * in question. 908 * 909 * A kernel thread without a process context is assumed to have 910 * the privilege in question. In situations where the caller always 911 * expect a cred to exist, the cred should be passed separately and 912 * priv_check_cred() should be used instead of priv_check(). 913 * 914 * Returns 0 or error. 915 */ 916 int 917 priv_check(struct thread *td, int priv) 918 { 919 if (td->td_lwp != NULL) 920 return priv_check_cred(td->td_ucred, priv, 0); 921 return (0); 922 } 923 924 /* 925 * Check a credential for privilege. 926 * 927 * A non-null credential is expected unless NULL_CRED_OKAY is set. 928 */ 929 int 930 priv_check_cred(struct ucred *cred, int priv, int flags) 931 { 932 int error; 933 934 KASSERT(PRIV_VALID(priv), ("priv_check_cred: invalid privilege")); 935 936 KASSERT(cred != NULL || (flags & NULL_CRED_OKAY), 937 ("priv_check_cred: NULL cred!")); 938 939 if (cred == NULL) { 940 if (flags & NULL_CRED_OKAY) 941 return (0); 942 else 943 return (EPERM); 944 } 945 if (cred->cr_uid != 0) 946 return (EPERM); 947 948 error = prison_priv_check(cred, priv); 949 if (error) 950 return (error); 951 952 /* NOTE: accounting for suser access (p_acflag/ASU) removed */ 953 return (0); 954 } 955 956 /* 957 * Return zero if p1 can fondle p2, return errno (EPERM/ESRCH) otherwise. 958 */ 959 int 960 p_trespass(struct ucred *cr1, struct ucred *cr2) 961 { 962 if (cr1 == cr2) 963 return (0); 964 if (!PRISON_CHECK(cr1, cr2)) 965 return (ESRCH); 966 if (cr1->cr_ruid == cr2->cr_ruid) 967 return (0); 968 if (cr1->cr_uid == cr2->cr_ruid) 969 return (0); 970 if (cr1->cr_ruid == cr2->cr_uid) 971 return (0); 972 if (cr1->cr_uid == cr2->cr_uid) 973 return (0); 974 if (priv_check_cred(cr1, PRIV_PROC_TRESPASS, 0) == 0) 975 return (0); 976 return (EPERM); 977 } 978 979 static __inline void 980 _crinit(struct ucred *cr) 981 { 982 cr->cr_ref = 1; 983 } 984 985 void 986 crinit(struct ucred *cr) 987 { 988 bzero(cr, sizeof(*cr)); 989 _crinit(cr); 990 } 991 992 /* 993 * Allocate a zeroed cred structure. 994 */ 995 struct ucred * 996 crget(void) 997 { 998 struct ucred *cr; 999 1000 cr = kmalloc(sizeof(*cr), M_CRED, M_WAITOK|M_ZERO); 1001 _crinit(cr); 1002 return (cr); 1003 } 1004 1005 /* 1006 * Claim another reference to a ucred structure. Can be used with special 1007 * creds. 1008 * 1009 * It must be possible to call this routine with spinlocks held, meaning 1010 * that this routine itself cannot obtain a spinlock. 1011 */ 1012 struct ucred * 1013 crhold(struct ucred *cr) 1014 { 1015 if (cr != NOCRED && cr != FSCRED) 1016 atomic_add_long(&cr->cr_ref, 1); 1017 return(cr); 1018 } 1019 1020 /* 1021 * Drop a reference from the cred structure, free it if the reference count 1022 * reaches 0. 1023 * 1024 * NOTE: because we used atomic_add_int() above, without a spinlock, we 1025 * must also use atomic_subtract_int() below. A spinlock is required 1026 * in crfree() to handle multiple callers racing the refcount to 0. 1027 */ 1028 void 1029 crfree(struct ucred *cr) 1030 { 1031 if (cr->cr_ref <= 0) 1032 panic("Freeing already free credential! %p", cr); 1033 if (atomic_fetchadd_long(&cr->cr_ref, -1) == 1) { 1034 /* 1035 * Some callers of crget(), such as nfs_statfs(), 1036 * allocate a temporary credential, but don't 1037 * allocate a uidinfo structure. 1038 */ 1039 if (cr->cr_uidinfo != NULL) { 1040 uidrop(cr->cr_uidinfo); 1041 cr->cr_uidinfo = NULL; 1042 } 1043 if (cr->cr_ruidinfo != NULL) { 1044 uidrop(cr->cr_ruidinfo); 1045 cr->cr_ruidinfo = NULL; 1046 } 1047 1048 /* 1049 * Destroy empty prisons 1050 */ 1051 if (jailed(cr)) 1052 prison_free(cr->cr_prison); 1053 cr->cr_prison = NULL; /* safety */ 1054 1055 kfree((caddr_t)cr, M_CRED); 1056 } 1057 } 1058 1059 /* 1060 * Atomize a cred structure so it can be modified without polluting 1061 * other references to it. 1062 * 1063 * MPSAFE (however, *pcr must be stable) 1064 */ 1065 struct ucred * 1066 cratom(struct ucred **pcr) 1067 { 1068 struct ucred *oldcr; 1069 struct ucred *newcr; 1070 1071 oldcr = *pcr; 1072 if (oldcr->cr_ref == 1) 1073 return (oldcr); 1074 newcr = crget(); /* this might block */ 1075 oldcr = *pcr; /* re-cache after potentially blocking */ 1076 *newcr = *oldcr; 1077 uihold(newcr->cr_uidinfo); 1078 uihold(newcr->cr_ruidinfo); 1079 if (jailed(newcr)) 1080 prison_hold(newcr->cr_prison); 1081 newcr->cr_ref = 1; 1082 crfree(oldcr); 1083 *pcr = newcr; 1084 1085 return (newcr); 1086 } 1087 1088 /* 1089 * Called with a modifying token held, but must still obtain p_spin to 1090 * actually replace p_ucred to handle races against syscall entry from 1091 * other threads which cache p_ucred->td_ucred. 1092 * 1093 * (the threads will only get the spin-lock, and they only need to in 1094 * the case where td_ucred != p_ucred so this is optimal). 1095 */ 1096 struct ucred * 1097 cratom_proc(struct proc *p) 1098 { 1099 struct ucred *oldcr; 1100 struct ucred *newcr; 1101 1102 oldcr = p->p_ucred; 1103 if (oldcr->cr_ref == 1) 1104 return(oldcr); 1105 1106 newcr = crget(); /* this might block */ 1107 oldcr = p->p_ucred; /* so re-cache oldcr (do not re-test) */ 1108 *newcr = *oldcr; 1109 uihold(newcr->cr_uidinfo); 1110 uihold(newcr->cr_ruidinfo); 1111 if (jailed(newcr)) 1112 prison_hold(newcr->cr_prison); 1113 newcr->cr_ref = 1; 1114 1115 spin_lock(&p->p_spin); 1116 p->p_ucred = newcr; 1117 spin_unlock(&p->p_spin); 1118 crfree(oldcr); 1119 1120 return newcr; 1121 } 1122 1123 /* 1124 * Dup cred struct to a new held one. 1125 */ 1126 struct ucred * 1127 crdup(struct ucred *cr) 1128 { 1129 struct ucred *newcr; 1130 1131 newcr = crget(); 1132 *newcr = *cr; 1133 uihold(newcr->cr_uidinfo); 1134 uihold(newcr->cr_ruidinfo); 1135 if (jailed(newcr)) 1136 prison_hold(newcr->cr_prison); 1137 newcr->cr_ref = 1; 1138 return (newcr); 1139 } 1140 1141 /* 1142 * Fill in a struct xucred based on a struct ucred. 1143 */ 1144 void 1145 cru2x(struct ucred *cr, struct xucred *xcr) 1146 { 1147 1148 bzero(xcr, sizeof(*xcr)); 1149 xcr->cr_version = XUCRED_VERSION; 1150 xcr->cr_uid = cr->cr_uid; 1151 xcr->cr_ngroups = cr->cr_ngroups; 1152 bcopy(cr->cr_groups, xcr->cr_groups, sizeof(cr->cr_groups)); 1153 } 1154 1155 /* 1156 * Get login name, if available. 1157 */ 1158 int 1159 sys_getlogin(struct getlogin_args *uap) 1160 { 1161 struct proc *p = curproc; 1162 char buf[MAXLOGNAME]; 1163 int error; 1164 1165 if (uap->namelen > MAXLOGNAME) /* namelen is unsigned */ 1166 uap->namelen = MAXLOGNAME; 1167 bzero(buf, sizeof(buf)); 1168 lwkt_gettoken_shared(&p->p_token); 1169 bcopy(p->p_pgrp->pg_session->s_login, buf, uap->namelen); 1170 lwkt_reltoken(&p->p_token); 1171 1172 error = copyout(buf, uap->namebuf, uap->namelen); 1173 return (error); 1174 } 1175 1176 /* 1177 * Set login name. 1178 */ 1179 int 1180 sys_setlogin(struct setlogin_args *uap) 1181 { 1182 struct thread *td = curthread; 1183 struct proc *p; 1184 struct ucred *cred; 1185 char buf[MAXLOGNAME]; 1186 int error; 1187 1188 cred = td->td_ucred; 1189 p = td->td_proc; 1190 1191 if ((error = priv_check_cred(cred, PRIV_PROC_SETLOGIN, 0))) 1192 return (error); 1193 bzero(buf, sizeof(buf)); 1194 error = copyinstr(uap->namebuf, buf, sizeof(buf), NULL); 1195 if (error == ENAMETOOLONG) 1196 error = EINVAL; 1197 if (error == 0) { 1198 lwkt_gettoken_shared(&p->p_token); 1199 memcpy(p->p_pgrp->pg_session->s_login, buf, sizeof(buf)); 1200 lwkt_reltoken(&p->p_token); 1201 } 1202 return (error); 1203 } 1204 1205 void 1206 setsugid(void) 1207 { 1208 struct proc *p = curproc; 1209 1210 KKASSERT(p != NULL); 1211 lwkt_gettoken(&p->p_token); 1212 p->p_flags |= P_SUGID; 1213 if (!(p->p_pfsflags & PF_ISUGID)) 1214 p->p_stops = 0; 1215 lwkt_reltoken(&p->p_token); 1216 } 1217 1218 /* 1219 * Helper function to change the effective uid of a process 1220 */ 1221 struct ucred * 1222 change_euid(uid_t euid) 1223 { 1224 struct proc *p = curproc; 1225 struct ucred *cr; 1226 1227 KKASSERT(p != NULL); 1228 lf_count_adjust(p, 0); 1229 cr = cratom_proc(p); 1230 cr->cr_uid = euid; 1231 uireplace(&cr->cr_uidinfo, uifind(euid)); 1232 lf_count_adjust(p, 1); 1233 return (cr); 1234 } 1235 1236 /* 1237 * Helper function to change the real uid of a process 1238 * 1239 * The per-uid process count for this process is transfered from 1240 * the old uid to the new uid. 1241 */ 1242 struct ucred * 1243 change_ruid(uid_t ruid) 1244 { 1245 struct proc *p = curproc; 1246 struct ucred *cr; 1247 1248 KKASSERT(p != NULL); 1249 1250 cr = cratom_proc(p); 1251 chgproccnt(cr->cr_ruidinfo, -1, 0); 1252 cr->cr_ruid = ruid; 1253 uireplace(&cr->cr_ruidinfo, uifind(ruid)); 1254 chgproccnt(cr->cr_ruidinfo, 1, 0); 1255 return (cr); 1256 } 1257