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/thread2.h> 58 #include <sys/spinlock2.h> 59 60 static MALLOC_DEFINE(M_CRED, "cred", "credentials"); 61 62 int 63 sys_getpid(struct getpid_args *uap) 64 { 65 struct proc *p = curproc; 66 67 uap->sysmsg_fds[0] = p->p_pid; 68 return (0); 69 } 70 71 int 72 sys_getppid(struct getppid_args *uap) 73 { 74 struct proc *p = curproc; 75 76 uap->sysmsg_result = p->p_ppid; 77 78 return (0); 79 } 80 81 int 82 sys_lwp_gettid(struct lwp_gettid_args *uap) 83 { 84 struct lwp *lp = curthread->td_lwp; 85 uap->sysmsg_result = lp->lwp_tid; 86 return (0); 87 } 88 89 /* 90 * Get process group ID; note that POSIX getpgrp takes no parameter 91 */ 92 int 93 sys_getpgrp(struct getpgrp_args *uap) 94 { 95 struct proc *p = curproc; 96 97 lwkt_gettoken_shared(&p->p_token); 98 uap->sysmsg_result = p->p_pgrp->pg_id; 99 lwkt_reltoken(&p->p_token); 100 101 return (0); 102 } 103 104 /* 105 * Get an arbitrary pid's process group id 106 */ 107 int 108 sys_getpgid(struct getpgid_args *uap) 109 { 110 struct proc *p = curproc; 111 struct proc *pt; 112 int error; 113 114 error = 0; 115 116 if (uap->pid == 0) { 117 pt = p; 118 PHOLD(pt); 119 } else { 120 pt = pfind(uap->pid); 121 if (pt == NULL) 122 error = ESRCH; 123 } 124 if (error == 0) { 125 lwkt_gettoken_shared(&pt->p_token); 126 uap->sysmsg_result = pt->p_pgrp->pg_id; 127 lwkt_reltoken(&pt->p_token); 128 } 129 if (pt) 130 PRELE(pt); 131 return (error); 132 } 133 134 /* 135 * Get an arbitrary pid's session id. 136 */ 137 int 138 sys_getsid(struct getsid_args *uap) 139 { 140 struct proc *p = curproc; 141 struct proc *pt; 142 int error; 143 144 error = 0; 145 146 if (uap->pid == 0) { 147 pt = p; 148 PHOLD(pt); 149 } else { 150 pt = pfind(uap->pid); 151 if (pt == NULL) 152 error = ESRCH; 153 } 154 if (error == 0) 155 uap->sysmsg_result = pt->p_session->s_sid; 156 if (pt) 157 PRELE(pt); 158 return (error); 159 } 160 161 162 /* 163 * getuid() 164 */ 165 int 166 sys_getuid(struct getuid_args *uap) 167 { 168 struct ucred *cred = curthread->td_ucred; 169 170 uap->sysmsg_fds[0] = cred->cr_ruid; 171 return (0); 172 } 173 174 /* 175 * geteuid() 176 */ 177 int 178 sys_geteuid(struct geteuid_args *uap) 179 { 180 struct ucred *cred = curthread->td_ucred; 181 182 uap->sysmsg_result = cred->cr_uid; 183 return (0); 184 } 185 186 /* 187 * getgid() 188 */ 189 int 190 sys_getgid(struct getgid_args *uap) 191 { 192 struct ucred *cred = curthread->td_ucred; 193 194 uap->sysmsg_fds[0] = cred->cr_rgid; 195 return (0); 196 } 197 198 /* 199 * Get effective group ID. The "egid" is groups[0], and could be obtained 200 * via getgroups. This syscall exists because it is somewhat painful to do 201 * correctly in a library function. 202 */ 203 int 204 sys_getegid(struct getegid_args *uap) 205 { 206 struct ucred *cred = curthread->td_ucred; 207 208 uap->sysmsg_result = cred->cr_groups[0]; 209 return (0); 210 } 211 212 int 213 sys_getgroups(struct getgroups_args *uap) 214 { 215 struct ucred *cr; 216 u_int ngrp; 217 int error; 218 219 cr = curthread->td_ucred; 220 if ((ngrp = uap->gidsetsize) == 0) { 221 uap->sysmsg_result = cr->cr_ngroups; 222 return (0); 223 } 224 if (ngrp < cr->cr_ngroups) 225 return (EINVAL); 226 ngrp = cr->cr_ngroups; 227 error = copyout((caddr_t)cr->cr_groups, 228 (caddr_t)uap->gidset, ngrp * sizeof(gid_t)); 229 if (error == 0) 230 uap->sysmsg_result = ngrp; 231 return (error); 232 } 233 234 int 235 sys_lwp_setname(struct lwp_setname_args *uap) 236 { 237 struct proc *p = curproc; 238 char comm0[MAXCOMLEN + 1]; 239 const char *comm = NULL; 240 struct lwp *lp; 241 int error; 242 243 if (uap->name != NULL) { 244 error = copyinstr(uap->name, comm0, sizeof(comm0), NULL); 245 if (error) { 246 if (error != ENAMETOOLONG) 247 return error; 248 /* Truncate */ 249 comm0[MAXCOMLEN] = '\0'; 250 } 251 comm = comm0; 252 } else { 253 /* Restore to the default name, i.e. process name. */ 254 comm = p->p_comm; 255 } 256 257 lwkt_gettoken(&p->p_token); 258 259 lp = lwp_rb_tree_RB_LOOKUP(&p->p_lwp_tree, uap->tid); 260 if (lp != NULL) { 261 strlcpy(lp->lwp_thread->td_comm, comm, 262 sizeof(lp->lwp_thread->td_comm)); 263 error = 0; 264 } else { 265 error = ESRCH; 266 } 267 268 lwkt_reltoken(&p->p_token); 269 return error; 270 } 271 272 int 273 sys_setsid(struct setsid_args *uap) 274 { 275 struct proc *p = curproc; 276 struct pgrp *pg = NULL; 277 int error; 278 279 lwkt_gettoken(&p->p_token); 280 if (p->p_pgid == p->p_pid || (pg = pgfind(p->p_pid)) != NULL) { 281 error = EPERM; 282 if (pg) 283 pgrel(pg); 284 } else { 285 enterpgrp(p, p->p_pid, 1); 286 uap->sysmsg_result = p->p_pid; 287 error = 0; 288 } 289 lwkt_reltoken(&p->p_token); 290 return (error); 291 } 292 293 /* 294 * set process group (setpgid/old setpgrp) 295 * 296 * caller does setpgid(targpid, targpgid) 297 * 298 * pid must be caller or child of caller (ESRCH) 299 * if a child 300 * pid must be in same session (EPERM) 301 * pid can't have done an exec (EACCES) 302 * if pgid != pid 303 * there must exist some pid in same session having pgid (EPERM) 304 * pid must not be session leader (EPERM) 305 */ 306 int 307 sys_setpgid(struct setpgid_args *uap) 308 { 309 struct proc *curp = curproc; 310 struct proc *targp; /* target process */ 311 struct pgrp *pgrp = NULL; /* target pgrp */ 312 int error; 313 314 if (uap->pgid < 0) 315 return (EINVAL); 316 317 if (uap->pid != 0 && uap->pid != curp->p_pid) { 318 if ((targp = pfind(uap->pid)) == NULL || !inferior(targp)) { 319 if (targp) 320 PRELE(targp); 321 error = ESRCH; 322 targp = NULL; 323 goto done; 324 } 325 lwkt_gettoken(&targp->p_token); 326 /* targp now referenced and its token is held */ 327 328 if (targp->p_pgrp == NULL || 329 targp->p_session != curp->p_session) { 330 error = EPERM; 331 goto done; 332 } 333 if (targp->p_flags & P_EXEC) { 334 error = EACCES; 335 goto done; 336 } 337 } else { 338 targp = curp; 339 PHOLD(targp); 340 lwkt_gettoken(&targp->p_token); 341 } 342 if (SESS_LEADER(targp)) { 343 error = EPERM; 344 goto done; 345 } 346 if (uap->pgid == 0) { 347 uap->pgid = targp->p_pid; 348 } else if (uap->pgid != targp->p_pid) { 349 if ((pgrp = pgfind(uap->pgid)) == NULL || 350 pgrp->pg_session != curp->p_session) { 351 error = EPERM; 352 goto done; 353 } 354 } 355 error = enterpgrp(targp, uap->pgid, 0); 356 done: 357 if (pgrp) 358 pgrel(pgrp); 359 if (targp) { 360 lwkt_reltoken(&targp->p_token); 361 PRELE(targp); 362 } 363 return (error); 364 } 365 366 /* 367 * Use the clause in B.4.2.2 that allows setuid/setgid to be 4.2/4.3BSD 368 * compatible. It says that setting the uid/gid to euid/egid is a special 369 * case of "appropriate privilege". Once the rules are expanded out, this 370 * basically means that setuid(nnn) sets all three id's, in all permitted 371 * cases unless _POSIX_SAVED_IDS is enabled. In that case, setuid(getuid()) 372 * does not set the saved id - this is dangerous for traditional BSD 373 * programs. For this reason, we *really* do not want to set 374 * _POSIX_SAVED_IDS and do not want to clear POSIX_APPENDIX_B_4_2_2. 375 */ 376 #define POSIX_APPENDIX_B_4_2_2 377 378 int 379 sys_setuid(struct setuid_args *uap) 380 { 381 struct proc *p = curproc; 382 struct ucred *cr; 383 uid_t uid; 384 int error; 385 386 lwkt_gettoken(&p->p_token); 387 cr = p->p_ucred; 388 389 /* 390 * See if we have "permission" by POSIX 1003.1 rules. 391 * 392 * Note that setuid(geteuid()) is a special case of 393 * "appropriate privileges" in appendix B.4.2.2. We need 394 * to use this clause to be compatible with traditional BSD 395 * semantics. Basically, it means that "setuid(xx)" sets all 396 * three id's (assuming you have privs). 397 * 398 * Notes on the logic. We do things in three steps. 399 * 1: We determine if the euid is going to change, and do EPERM 400 * right away. We unconditionally change the euid later if this 401 * test is satisfied, simplifying that part of the logic. 402 * 2: We determine if the real and/or saved uid's are going to 403 * change. Determined by compile options. 404 * 3: Change euid last. (after tests in #2 for "appropriate privs") 405 */ 406 uid = uap->uid; 407 if (uid != cr->cr_ruid && /* allow setuid(getuid()) */ 408 #ifdef _POSIX_SAVED_IDS 409 uid != crc->cr_svuid && /* allow setuid(saved gid) */ 410 #endif 411 #ifdef POSIX_APPENDIX_B_4_2_2 /* Use BSD-compat clause from B.4.2.2 */ 412 uid != cr->cr_uid && /* allow setuid(geteuid()) */ 413 #endif 414 (error = priv_check_cred(cr, PRIV_CRED_SETUID, 0))) 415 goto done; 416 417 #ifdef _POSIX_SAVED_IDS 418 /* 419 * Do we have "appropriate privileges" (are we root or uid == euid) 420 * If so, we are changing the real uid and/or saved uid. 421 */ 422 if ( 423 #ifdef POSIX_APPENDIX_B_4_2_2 /* Use the clause from B.4.2.2 */ 424 uid == cr->cr_uid || 425 #endif 426 priv_check_cred(cr, PRIV_CRED_SETUID, 0) == 0) /* we are using privs */ 427 #endif 428 { 429 /* 430 * Set the real uid and transfer proc count to new user. 431 */ 432 if (uid != cr->cr_ruid) { 433 cr = change_ruid(uid); 434 setsugid(); 435 } 436 /* 437 * Set saved uid 438 * 439 * XXX always set saved uid even if not _POSIX_SAVED_IDS, as 440 * the security of seteuid() depends on it. B.4.2.2 says it 441 * is important that we should do this. 442 */ 443 if (cr->cr_svuid != uid) { 444 cr = cratom_proc(p); 445 cr->cr_svuid = uid; 446 setsugid(); 447 } 448 } 449 450 /* 451 * In all permitted cases, we are changing the euid. 452 * Copy credentials so other references do not see our changes. 453 */ 454 if (cr->cr_uid != uid) { 455 change_euid(uid); 456 setsugid(); 457 } 458 error = 0; 459 done: 460 lwkt_reltoken(&p->p_token); 461 return (error); 462 } 463 464 int 465 sys_seteuid(struct seteuid_args *uap) 466 { 467 struct proc *p = curproc; 468 struct ucred *cr; 469 uid_t euid; 470 int error; 471 472 lwkt_gettoken(&p->p_token); 473 cr = p->p_ucred; 474 euid = uap->euid; 475 if (euid != cr->cr_ruid && /* allow seteuid(getuid()) */ 476 euid != cr->cr_svuid && /* allow seteuid(saved uid) */ 477 (error = priv_check_cred(cr, PRIV_CRED_SETEUID, 0))) { 478 lwkt_reltoken(&p->p_token); 479 return (error); 480 } 481 482 /* 483 * Everything's okay, do it. Copy credentials so other references do 484 * not see our changes. 485 */ 486 if (cr->cr_uid != euid) { 487 change_euid(euid); 488 setsugid(); 489 } 490 lwkt_reltoken(&p->p_token); 491 return (0); 492 } 493 494 int 495 sys_setgid(struct setgid_args *uap) 496 { 497 struct proc *p = curproc; 498 struct ucred *cr; 499 gid_t gid; 500 int error; 501 502 lwkt_gettoken(&p->p_token); 503 cr = p->p_ucred; 504 505 /* 506 * See if we have "permission" by POSIX 1003.1 rules. 507 * 508 * Note that setgid(getegid()) is a special case of 509 * "appropriate privileges" in appendix B.4.2.2. We need 510 * to use this clause to be compatible with traditional BSD 511 * semantics. Basically, it means that "setgid(xx)" sets all 512 * three id's (assuming you have privs). 513 * 514 * For notes on the logic here, see setuid() above. 515 */ 516 gid = uap->gid; 517 if (gid != cr->cr_rgid && /* allow setgid(getgid()) */ 518 #ifdef _POSIX_SAVED_IDS 519 gid != cr->cr_svgid && /* allow setgid(saved gid) */ 520 #endif 521 #ifdef POSIX_APPENDIX_B_4_2_2 /* Use BSD-compat clause from B.4.2.2 */ 522 gid != cr->cr_groups[0] && /* allow setgid(getegid()) */ 523 #endif 524 (error = priv_check_cred(cr, PRIV_CRED_SETGID, 0))) { 525 goto done; 526 } 527 528 #ifdef _POSIX_SAVED_IDS 529 /* 530 * Do we have "appropriate privileges" (are we root or gid == egid) 531 * If so, we are changing the real uid and saved gid. 532 */ 533 if ( 534 #ifdef POSIX_APPENDIX_B_4_2_2 /* use the clause from B.4.2.2 */ 535 gid == cr->cr_groups[0] || 536 #endif 537 priv_check_cred(cr, PRIV_CRED_SETGID, 0) == 0) /* we are using privs */ 538 #endif 539 { 540 /* 541 * Set real gid 542 */ 543 if (cr->cr_rgid != gid) { 544 cr = cratom_proc(p); 545 cr->cr_rgid = gid; 546 setsugid(); 547 } 548 /* 549 * Set saved gid 550 * 551 * XXX always set saved gid even if not _POSIX_SAVED_IDS, as 552 * the security of setegid() depends on it. B.4.2.2 says it 553 * is important that we should do this. 554 */ 555 if (cr->cr_svgid != gid) { 556 cr = cratom_proc(p); 557 cr->cr_svgid = gid; 558 setsugid(); 559 } 560 } 561 /* 562 * In all cases permitted cases, we are changing the egid. 563 * Copy credentials so other references do not see our changes. 564 */ 565 if (cr->cr_groups[0] != gid) { 566 cr = cratom_proc(p); 567 cr->cr_groups[0] = gid; 568 setsugid(); 569 } 570 error = 0; 571 done: 572 lwkt_reltoken(&p->p_token); 573 return (error); 574 } 575 576 int 577 sys_setegid(struct setegid_args *uap) 578 { 579 struct proc *p = curproc; 580 struct ucred *cr; 581 gid_t egid; 582 int error; 583 584 lwkt_gettoken(&p->p_token); 585 cr = p->p_ucred; 586 egid = uap->egid; 587 if (egid != cr->cr_rgid && /* allow setegid(getgid()) */ 588 egid != cr->cr_svgid && /* allow setegid(saved gid) */ 589 (error = priv_check_cred(cr, PRIV_CRED_SETEGID, 0))) { 590 goto done; 591 } 592 if (cr->cr_groups[0] != egid) { 593 cr = cratom_proc(p); 594 cr->cr_groups[0] = egid; 595 setsugid(); 596 } 597 error = 0; 598 done: 599 lwkt_reltoken(&p->p_token); 600 return (error); 601 } 602 603 int 604 sys_setgroups(struct setgroups_args *uap) 605 { 606 struct proc *p = curproc; 607 struct ucred *cr; 608 u_int ngrp; 609 int error; 610 611 lwkt_gettoken(&p->p_token); 612 cr = p->p_ucred; 613 614 if ((error = priv_check_cred(cr, PRIV_CRED_SETGROUPS, 0))) 615 goto done; 616 ngrp = uap->gidsetsize; 617 if (ngrp > NGROUPS) { 618 error = EINVAL; 619 goto done; 620 } 621 /* 622 * XXX A little bit lazy here. We could test if anything has 623 * changed before cratom() and setting P_SUGID. 624 */ 625 cr = cratom_proc(p); 626 if (ngrp < 1) { 627 /* 628 * setgroups(0, NULL) is a legitimate way of clearing the 629 * groups vector on non-BSD systems (which generally do not 630 * have the egid in the groups[0]). We risk security holes 631 * when running non-BSD software if we do not do the same. 632 */ 633 cr->cr_ngroups = 1; 634 } else { 635 error = copyin(uap->gidset, cr->cr_groups, 636 ngrp * sizeof(gid_t)); 637 if (error) 638 goto done; 639 cr->cr_ngroups = ngrp; 640 } 641 setsugid(); 642 error = 0; 643 done: 644 lwkt_reltoken(&p->p_token); 645 return (error); 646 } 647 648 int 649 sys_setreuid(struct setreuid_args *uap) 650 { 651 struct proc *p = curproc; 652 struct ucred *cr; 653 uid_t ruid, euid; 654 int error; 655 656 lwkt_gettoken(&p->p_token); 657 cr = p->p_ucred; 658 659 ruid = uap->ruid; 660 euid = uap->euid; 661 if (((ruid != (uid_t)-1 && ruid != cr->cr_ruid && 662 ruid != cr->cr_svuid) || 663 (euid != (uid_t)-1 && euid != cr->cr_uid && 664 euid != cr->cr_ruid && euid != cr->cr_svuid)) && 665 (error = priv_check_cred(cr, PRIV_CRED_SETREUID, 0)) != 0) { 666 goto done; 667 } 668 669 if (euid != (uid_t)-1 && cr->cr_uid != euid) { 670 cr = change_euid(euid); 671 setsugid(); 672 } 673 if (ruid != (uid_t)-1 && cr->cr_ruid != ruid) { 674 cr = change_ruid(ruid); 675 setsugid(); 676 } 677 if ((ruid != (uid_t)-1 || cr->cr_uid != cr->cr_ruid) && 678 cr->cr_svuid != cr->cr_uid) { 679 cr = cratom_proc(p); 680 cr->cr_svuid = cr->cr_uid; 681 setsugid(); 682 } 683 error = 0; 684 done: 685 lwkt_reltoken(&p->p_token); 686 return (error); 687 } 688 689 int 690 sys_setregid(struct setregid_args *uap) 691 { 692 struct proc *p = curproc; 693 struct ucred *cr; 694 gid_t rgid, egid; 695 int error; 696 697 lwkt_gettoken(&p->p_token); 698 cr = p->p_ucred; 699 700 rgid = uap->rgid; 701 egid = uap->egid; 702 if (((rgid != (gid_t)-1 && rgid != cr->cr_rgid && 703 rgid != cr->cr_svgid) || 704 (egid != (gid_t)-1 && egid != cr->cr_groups[0] && 705 egid != cr->cr_rgid && egid != cr->cr_svgid)) && 706 (error = priv_check_cred(cr, PRIV_CRED_SETREGID, 0)) != 0) { 707 goto done; 708 } 709 710 if (egid != (gid_t)-1 && cr->cr_groups[0] != egid) { 711 cr = cratom_proc(p); 712 cr->cr_groups[0] = egid; 713 setsugid(); 714 } 715 if (rgid != (gid_t)-1 && cr->cr_rgid != rgid) { 716 cr = cratom_proc(p); 717 cr->cr_rgid = rgid; 718 setsugid(); 719 } 720 if ((rgid != (gid_t)-1 || cr->cr_groups[0] != cr->cr_rgid) && 721 cr->cr_svgid != cr->cr_groups[0]) { 722 cr = cratom_proc(p); 723 cr->cr_svgid = cr->cr_groups[0]; 724 setsugid(); 725 } 726 error = 0; 727 done: 728 lwkt_reltoken(&p->p_token); 729 return (error); 730 } 731 732 /* 733 * setresuid(ruid, euid, suid) is like setreuid except control over the 734 * saved uid is explicit. 735 */ 736 int 737 sys_setresuid(struct setresuid_args *uap) 738 { 739 struct proc *p = curproc; 740 struct ucred *cr; 741 uid_t ruid, euid, suid; 742 int error; 743 744 lwkt_gettoken(&p->p_token); 745 cr = p->p_ucred; 746 747 ruid = uap->ruid; 748 euid = uap->euid; 749 suid = uap->suid; 750 if (((ruid != (uid_t)-1 && ruid != cr->cr_ruid && 751 ruid != cr->cr_svuid && ruid != cr->cr_uid) || 752 (euid != (uid_t)-1 && euid != cr->cr_ruid && 753 euid != cr->cr_svuid && euid != cr->cr_uid) || 754 (suid != (uid_t)-1 && suid != cr->cr_ruid && 755 suid != cr->cr_svuid && suid != cr->cr_uid)) && 756 (error = priv_check_cred(cr, PRIV_CRED_SETRESUID, 0)) != 0) { 757 goto done; 758 } 759 if (euid != (uid_t)-1 && cr->cr_uid != euid) { 760 cr = change_euid(euid); 761 setsugid(); 762 } 763 if (ruid != (uid_t)-1 && cr->cr_ruid != ruid) { 764 cr = change_ruid(ruid); 765 setsugid(); 766 } 767 if (suid != (uid_t)-1 && cr->cr_svuid != suid) { 768 cr = cratom_proc(p); 769 cr->cr_svuid = suid; 770 setsugid(); 771 } 772 error = 0; 773 done: 774 lwkt_reltoken(&p->p_token); 775 return (error); 776 } 777 778 /* 779 * setresgid(rgid, egid, sgid) is like setregid except control over the 780 * saved gid is explicit. 781 */ 782 int 783 sys_setresgid(struct setresgid_args *uap) 784 { 785 struct proc *p = curproc; 786 struct ucred *cr; 787 gid_t rgid, egid, sgid; 788 int error; 789 790 lwkt_gettoken(&p->p_token); 791 cr = p->p_ucred; 792 rgid = uap->rgid; 793 egid = uap->egid; 794 sgid = uap->sgid; 795 if (((rgid != (gid_t)-1 && rgid != cr->cr_rgid && 796 rgid != cr->cr_svgid && rgid != cr->cr_groups[0]) || 797 (egid != (gid_t)-1 && egid != cr->cr_rgid && 798 egid != cr->cr_svgid && egid != cr->cr_groups[0]) || 799 (sgid != (gid_t)-1 && sgid != cr->cr_rgid && 800 sgid != cr->cr_svgid && sgid != cr->cr_groups[0])) && 801 (error = priv_check_cred(cr, PRIV_CRED_SETRESGID, 0)) != 0) { 802 goto done; 803 } 804 805 if (egid != (gid_t)-1 && cr->cr_groups[0] != egid) { 806 cr = cratom_proc(p); 807 cr->cr_groups[0] = egid; 808 setsugid(); 809 } 810 if (rgid != (gid_t)-1 && cr->cr_rgid != rgid) { 811 cr = cratom_proc(p); 812 cr->cr_rgid = rgid; 813 setsugid(); 814 } 815 if (sgid != (gid_t)-1 && cr->cr_svgid != sgid) { 816 cr = cratom_proc(p); 817 cr->cr_svgid = sgid; 818 setsugid(); 819 } 820 error = 0; 821 done: 822 lwkt_reltoken(&p->p_token); 823 return (error); 824 } 825 826 int 827 sys_getresuid(struct getresuid_args *uap) 828 { 829 struct ucred *cr; 830 int error1 = 0, error2 = 0, error3 = 0; 831 832 /* 833 * copyout's can fault synchronously so we cannot use a shared 834 * token here. 835 */ 836 cr = curthread->td_ucred; 837 if (uap->ruid) 838 error1 = copyout((caddr_t)&cr->cr_ruid, 839 (caddr_t)uap->ruid, sizeof(cr->cr_ruid)); 840 if (uap->euid) 841 error2 = copyout((caddr_t)&cr->cr_uid, 842 (caddr_t)uap->euid, sizeof(cr->cr_uid)); 843 if (uap->suid) 844 error3 = copyout((caddr_t)&cr->cr_svuid, 845 (caddr_t)uap->suid, sizeof(cr->cr_svuid)); 846 return error1 ? error1 : (error2 ? error2 : error3); 847 } 848 849 int 850 sys_getresgid(struct getresgid_args *uap) 851 { 852 struct ucred *cr; 853 int error1 = 0, error2 = 0, error3 = 0; 854 855 cr = curthread->td_ucred; 856 if (uap->rgid) 857 error1 = copyout(&cr->cr_rgid, uap->rgid, 858 sizeof(cr->cr_rgid)); 859 if (uap->egid) 860 error2 = copyout(&cr->cr_groups[0], uap->egid, 861 sizeof(cr->cr_groups[0])); 862 if (uap->sgid) 863 error3 = copyout(&cr->cr_svgid, uap->sgid, 864 sizeof(cr->cr_svgid)); 865 return error1 ? error1 : (error2 ? error2 : error3); 866 } 867 868 869 /* 870 * NOTE: OpenBSD sets a P_SUGIDEXEC flag set at execve() time, 871 * we use P_SUGID because we consider changing the owners as 872 * "tainting" as well. 873 * This is significant for procs that start as root and "become" 874 * a user without an exec - programs cannot know *everything* 875 * that libc *might* have put in their data segment. 876 */ 877 int 878 sys_issetugid(struct issetugid_args *uap) 879 { 880 uap->sysmsg_result = (curproc->p_flags & P_SUGID) ? 1 : 0; 881 return (0); 882 } 883 884 /* 885 * Check if gid is a member of the group set. 886 */ 887 int 888 groupmember(gid_t gid, struct ucred *cred) 889 { 890 gid_t *gp; 891 gid_t *egp; 892 893 egp = &(cred->cr_groups[cred->cr_ngroups]); 894 for (gp = cred->cr_groups; gp < egp; gp++) { 895 if (*gp == gid) 896 return (1); 897 } 898 return (0); 899 } 900 901 /* 902 * Test whether the specified credentials have the privilege 903 * in question. 904 * 905 * A kernel thread without a process context is assumed to have 906 * the privilege in question. In situations where the caller always 907 * expect a cred to exist, the cred should be passed separately and 908 * priv_check_cred() should be used instead of priv_check(). 909 * 910 * Returns 0 or error. 911 */ 912 int 913 priv_check(struct thread *td, int priv) 914 { 915 if (td->td_lwp != NULL) 916 return priv_check_cred(td->td_ucred, priv, 0); 917 return (0); 918 } 919 920 /* 921 * Check a credential for privilege. 922 * 923 * A non-null credential is expected unless NULL_CRED_OKAY is set. 924 */ 925 int 926 priv_check_cred(struct ucred *cred, int priv, int flags) 927 { 928 int error; 929 930 KASSERT(PRIV_VALID(priv), ("priv_check_cred: invalid privilege")); 931 932 KASSERT(cred != NULL || (flags & NULL_CRED_OKAY), 933 ("priv_check_cred: NULL cred!")); 934 935 if (cred == NULL) { 936 if (flags & NULL_CRED_OKAY) 937 return (0); 938 else 939 return (EPERM); 940 } 941 if (cred->cr_uid != 0) 942 return (EPERM); 943 944 error = prison_priv_check(cred, priv); 945 if (error) 946 return (error); 947 948 /* NOTE: accounting for suser access (p_acflag/ASU) removed */ 949 return (0); 950 } 951 952 /* 953 * Return zero if p1 can fondle p2, return errno (EPERM/ESRCH) otherwise. 954 */ 955 int 956 p_trespass(struct ucred *cr1, struct ucred *cr2) 957 { 958 if (cr1 == cr2) 959 return (0); 960 if (!PRISON_CHECK(cr1, cr2)) 961 return (ESRCH); 962 if (cr1->cr_ruid == cr2->cr_ruid) 963 return (0); 964 if (cr1->cr_uid == cr2->cr_ruid) 965 return (0); 966 if (cr1->cr_ruid == cr2->cr_uid) 967 return (0); 968 if (cr1->cr_uid == cr2->cr_uid) 969 return (0); 970 if (priv_check_cred(cr1, PRIV_PROC_TRESPASS, 0) == 0) 971 return (0); 972 return (EPERM); 973 } 974 975 static __inline void 976 _crinit(struct ucred *cr) 977 { 978 cr->cr_ref = 1; 979 } 980 981 void 982 crinit(struct ucred *cr) 983 { 984 bzero(cr, sizeof(*cr)); 985 _crinit(cr); 986 } 987 988 /* 989 * Allocate a zeroed cred structure. 990 */ 991 struct ucred * 992 crget(void) 993 { 994 struct ucred *cr; 995 996 cr = kmalloc(sizeof(*cr), M_CRED, M_WAITOK|M_ZERO); 997 _crinit(cr); 998 return (cr); 999 } 1000 1001 /* 1002 * Claim another reference to a ucred structure. Can be used with special 1003 * creds. 1004 * 1005 * It must be possible to call this routine with spinlocks held, meaning 1006 * that this routine itself cannot obtain a spinlock. 1007 */ 1008 struct ucred * 1009 crhold(struct ucred *cr) 1010 { 1011 if (cr != NOCRED && cr != FSCRED) 1012 atomic_add_long(&cr->cr_ref, 1); 1013 return(cr); 1014 } 1015 1016 /* 1017 * Drop a reference from the cred structure, free it if the reference count 1018 * reaches 0. 1019 * 1020 * NOTE: because we used atomic_add_int() above, without a spinlock, we 1021 * must also use atomic_subtract_int() below. A spinlock is required 1022 * in crfree() to handle multiple callers racing the refcount to 0. 1023 */ 1024 void 1025 crfree(struct ucred *cr) 1026 { 1027 if (cr->cr_ref <= 0) 1028 panic("Freeing already free credential! %p", cr); 1029 if (atomic_fetchadd_long(&cr->cr_ref, -1) == 1) { 1030 /* 1031 * Some callers of crget(), such as nfs_statfs(), 1032 * allocate a temporary credential, but don't 1033 * allocate a uidinfo structure. 1034 */ 1035 if (cr->cr_uidinfo != NULL) { 1036 uidrop(cr->cr_uidinfo); 1037 cr->cr_uidinfo = NULL; 1038 } 1039 if (cr->cr_ruidinfo != NULL) { 1040 uidrop(cr->cr_ruidinfo); 1041 cr->cr_ruidinfo = NULL; 1042 } 1043 1044 /* 1045 * Destroy empty prisons 1046 */ 1047 if (jailed(cr)) 1048 prison_free(cr->cr_prison); 1049 cr->cr_prison = NULL; /* safety */ 1050 1051 kfree((caddr_t)cr, M_CRED); 1052 } 1053 } 1054 1055 /* 1056 * Atomize a cred structure so it can be modified without polluting 1057 * other references to it. 1058 * 1059 * MPSAFE (however, *pcr must be stable) 1060 */ 1061 struct ucred * 1062 cratom(struct ucred **pcr) 1063 { 1064 struct ucred *oldcr; 1065 struct ucred *newcr; 1066 1067 oldcr = *pcr; 1068 if (oldcr->cr_ref == 1) 1069 return (oldcr); 1070 newcr = crget(); /* this might block */ 1071 oldcr = *pcr; /* re-cache after potentially blocking */ 1072 *newcr = *oldcr; 1073 uihold(newcr->cr_uidinfo); 1074 uihold(newcr->cr_ruidinfo); 1075 if (jailed(newcr)) 1076 prison_hold(newcr->cr_prison); 1077 newcr->cr_ref = 1; 1078 crfree(oldcr); 1079 *pcr = newcr; 1080 1081 return (newcr); 1082 } 1083 1084 /* 1085 * Called with a modifying token held, but must still obtain p_spin to 1086 * actually replace p_ucred to handle races against syscall entry from 1087 * other threads which cache p_ucred->td_ucred. 1088 * 1089 * (the threads will only get the spin-lock, and they only need to in 1090 * the case where td_ucred != p_ucred so this is optimal). 1091 */ 1092 struct ucred * 1093 cratom_proc(struct proc *p) 1094 { 1095 struct ucred *oldcr; 1096 struct ucred *newcr; 1097 1098 oldcr = p->p_ucred; 1099 if (oldcr->cr_ref == 1) 1100 return(oldcr); 1101 1102 newcr = crget(); /* this might block */ 1103 oldcr = p->p_ucred; /* so re-cache oldcr (do not re-test) */ 1104 *newcr = *oldcr; 1105 uihold(newcr->cr_uidinfo); 1106 uihold(newcr->cr_ruidinfo); 1107 if (jailed(newcr)) 1108 prison_hold(newcr->cr_prison); 1109 newcr->cr_ref = 1; 1110 1111 spin_lock(&p->p_spin); 1112 p->p_ucred = newcr; 1113 spin_unlock(&p->p_spin); 1114 crfree(oldcr); 1115 1116 return newcr; 1117 } 1118 1119 /* 1120 * Dup cred struct to a new held one. 1121 */ 1122 struct ucred * 1123 crdup(struct ucred *cr) 1124 { 1125 struct ucred *newcr; 1126 1127 newcr = crget(); 1128 *newcr = *cr; 1129 uihold(newcr->cr_uidinfo); 1130 uihold(newcr->cr_ruidinfo); 1131 if (jailed(newcr)) 1132 prison_hold(newcr->cr_prison); 1133 newcr->cr_ref = 1; 1134 return (newcr); 1135 } 1136 1137 /* 1138 * Fill in a struct xucred based on a struct ucred. 1139 */ 1140 void 1141 cru2x(struct ucred *cr, struct xucred *xcr) 1142 { 1143 1144 bzero(xcr, sizeof(*xcr)); 1145 xcr->cr_version = XUCRED_VERSION; 1146 xcr->cr_uid = cr->cr_uid; 1147 xcr->cr_ngroups = cr->cr_ngroups; 1148 bcopy(cr->cr_groups, xcr->cr_groups, sizeof(cr->cr_groups)); 1149 } 1150 1151 /* 1152 * Get login name, if available. 1153 */ 1154 int 1155 sys_getlogin(struct getlogin_args *uap) 1156 { 1157 struct proc *p = curproc; 1158 char buf[MAXLOGNAME]; 1159 int error; 1160 1161 if (uap->namelen > MAXLOGNAME) /* namelen is unsigned */ 1162 uap->namelen = MAXLOGNAME; 1163 bzero(buf, sizeof(buf)); 1164 lwkt_gettoken_shared(&p->p_token); 1165 bcopy(p->p_pgrp->pg_session->s_login, buf, uap->namelen); 1166 lwkt_reltoken(&p->p_token); 1167 1168 error = copyout(buf, uap->namebuf, uap->namelen); 1169 return (error); 1170 } 1171 1172 /* 1173 * Set login name. 1174 */ 1175 int 1176 sys_setlogin(struct setlogin_args *uap) 1177 { 1178 struct thread *td = curthread; 1179 struct proc *p; 1180 struct ucred *cred; 1181 char buf[MAXLOGNAME]; 1182 int error; 1183 1184 cred = td->td_ucred; 1185 p = td->td_proc; 1186 1187 if ((error = priv_check_cred(cred, PRIV_PROC_SETLOGIN, 0))) 1188 return (error); 1189 bzero(buf, sizeof(buf)); 1190 error = copyinstr(uap->namebuf, buf, sizeof(buf), NULL); 1191 if (error == ENAMETOOLONG) 1192 error = EINVAL; 1193 if (error == 0) { 1194 lwkt_gettoken_shared(&p->p_token); 1195 memcpy(p->p_pgrp->pg_session->s_login, buf, sizeof(buf)); 1196 lwkt_reltoken(&p->p_token); 1197 } 1198 return (error); 1199 } 1200 1201 void 1202 setsugid(void) 1203 { 1204 struct proc *p = curproc; 1205 1206 KKASSERT(p != NULL); 1207 lwkt_gettoken(&p->p_token); 1208 p->p_flags |= P_SUGID; 1209 if (!(p->p_pfsflags & PF_ISUGID)) 1210 p->p_stops = 0; 1211 lwkt_reltoken(&p->p_token); 1212 } 1213 1214 /* 1215 * Helper function to change the effective uid of a process 1216 */ 1217 struct ucred * 1218 change_euid(uid_t euid) 1219 { 1220 struct proc *p = curproc; 1221 struct ucred *cr; 1222 1223 KKASSERT(p != NULL); 1224 lf_count_adjust(p, 0); 1225 cr = cratom_proc(p); 1226 cr->cr_uid = euid; 1227 uireplace(&cr->cr_uidinfo, uifind(euid)); 1228 lf_count_adjust(p, 1); 1229 return (cr); 1230 } 1231 1232 /* 1233 * Helper function to change the real uid of a process 1234 * 1235 * The per-uid process count for this process is transfered from 1236 * the old uid to the new uid. 1237 */ 1238 struct ucred * 1239 change_ruid(uid_t ruid) 1240 { 1241 struct proc *p = curproc; 1242 struct ucred *cr; 1243 1244 KKASSERT(p != NULL); 1245 1246 cr = cratom_proc(p); 1247 chgproccnt(cr->cr_ruidinfo, -1, 0); 1248 cr->cr_ruid = ruid; 1249 uireplace(&cr->cr_ruidinfo, uifind(ruid)); 1250 chgproccnt(cr->cr_ruidinfo, 1, 0); 1251 return (cr); 1252 } 1253