kern_prot.c revision 141815
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 * Copyright (c) 2000-2001 Robert N. M. Watson. All rights reserved. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 * 35 * @(#)kern_prot.c 8.6 (Berkeley) 1/21/94 36 */ 37 38/* 39 * System calls related to processes and protection 40 */ 41 42#include <sys/cdefs.h> 43__FBSDID("$FreeBSD: head/sys/kern/kern_prot.c 141815 2005-02-13 17:37:20Z sobomax $"); 44 45#include "opt_compat.h" 46#include "opt_mac.h" 47 48#include <sys/param.h> 49#include <sys/systm.h> 50#include <sys/acct.h> 51#include <sys/kdb.h> 52#include <sys/kernel.h> 53#include <sys/lock.h> 54#include <sys/mac.h> 55#include <sys/malloc.h> 56#include <sys/mutex.h> 57#include <sys/sx.h> 58#include <sys/proc.h> 59#include <sys/sysproto.h> 60#include <sys/jail.h> 61#include <sys/pioctl.h> 62#include <sys/resourcevar.h> 63#include <sys/socket.h> 64#include <sys/socketvar.h> 65#include <sys/sysctl.h> 66 67static MALLOC_DEFINE(M_CRED, "cred", "credentials"); 68 69SYSCTL_DECL(_security); 70SYSCTL_NODE(_security, OID_AUTO, bsd, CTLFLAG_RW, 0, 71 "BSD security policy"); 72 73#ifndef _SYS_SYSPROTO_H_ 74struct getpid_args { 75 int dummy; 76}; 77#endif 78/* 79 * MPSAFE 80 */ 81/* ARGSUSED */ 82int 83getpid(struct thread *td, struct getpid_args *uap) 84{ 85 struct proc *p = td->td_proc; 86 87 td->td_retval[0] = p->p_pid; 88#if defined(COMPAT_43) 89 PROC_LOCK(p); 90 td->td_retval[1] = p->p_pptr->p_pid; 91 PROC_UNLOCK(p); 92#endif 93 return (0); 94} 95 96#ifndef _SYS_SYSPROTO_H_ 97struct getppid_args { 98 int dummy; 99}; 100#endif 101/* 102 * MPSAFE 103 */ 104/* ARGSUSED */ 105int 106getppid(struct thread *td, struct getppid_args *uap) 107{ 108 struct proc *p = td->td_proc; 109 110 PROC_LOCK(p); 111 td->td_retval[0] = p->p_pptr->p_pid; 112 PROC_UNLOCK(p); 113 return (0); 114} 115 116/* 117 * Get process group ID; note that POSIX getpgrp takes no parameter. 118 */ 119#ifndef _SYS_SYSPROTO_H_ 120struct getpgrp_args { 121 int dummy; 122}; 123#endif 124/* 125 * MPSAFE 126 */ 127int 128getpgrp(struct thread *td, struct getpgrp_args *uap) 129{ 130 struct proc *p = td->td_proc; 131 132 PROC_LOCK(p); 133 td->td_retval[0] = p->p_pgrp->pg_id; 134 PROC_UNLOCK(p); 135 return (0); 136} 137 138/* Get an arbitary pid's process group id */ 139#ifndef _SYS_SYSPROTO_H_ 140struct getpgid_args { 141 pid_t pid; 142}; 143#endif 144/* 145 * MPSAFE 146 */ 147int 148getpgid(struct thread *td, struct getpgid_args *uap) 149{ 150 struct proc *p; 151 int error; 152 153 if (uap->pid == 0) { 154 p = td->td_proc; 155 PROC_LOCK(p); 156 } else { 157 p = pfind(uap->pid); 158 if (p == NULL) 159 return (ESRCH); 160 error = p_cansee(td, p); 161 if (error) { 162 PROC_UNLOCK(p); 163 return (error); 164 } 165 } 166 td->td_retval[0] = p->p_pgrp->pg_id; 167 PROC_UNLOCK(p); 168 return (0); 169} 170 171/* 172 * Get an arbitary pid's session id. 173 */ 174#ifndef _SYS_SYSPROTO_H_ 175struct getsid_args { 176 pid_t pid; 177}; 178#endif 179/* 180 * MPSAFE 181 */ 182int 183getsid(struct thread *td, struct getsid_args *uap) 184{ 185 struct proc *p; 186 int error; 187 188 if (uap->pid == 0) { 189 p = td->td_proc; 190 PROC_LOCK(p); 191 } else { 192 p = pfind(uap->pid); 193 if (p == NULL) 194 return (ESRCH); 195 error = p_cansee(td, p); 196 if (error) { 197 PROC_UNLOCK(p); 198 return (error); 199 } 200 } 201 td->td_retval[0] = p->p_session->s_sid; 202 PROC_UNLOCK(p); 203 return (0); 204} 205 206#ifndef _SYS_SYSPROTO_H_ 207struct getuid_args { 208 int dummy; 209}; 210#endif 211/* 212 * MPSAFE 213 */ 214/* ARGSUSED */ 215int 216getuid(struct thread *td, struct getuid_args *uap) 217{ 218 219 td->td_retval[0] = td->td_ucred->cr_ruid; 220#if defined(COMPAT_43) 221 td->td_retval[1] = td->td_ucred->cr_uid; 222#endif 223 return (0); 224} 225 226#ifndef _SYS_SYSPROTO_H_ 227struct geteuid_args { 228 int dummy; 229}; 230#endif 231/* 232 * MPSAFE 233 */ 234/* ARGSUSED */ 235int 236geteuid(struct thread *td, struct geteuid_args *uap) 237{ 238 239 td->td_retval[0] = td->td_ucred->cr_uid; 240 return (0); 241} 242 243#ifndef _SYS_SYSPROTO_H_ 244struct getgid_args { 245 int dummy; 246}; 247#endif 248/* 249 * MPSAFE 250 */ 251/* ARGSUSED */ 252int 253getgid(struct thread *td, struct getgid_args *uap) 254{ 255 256 td->td_retval[0] = td->td_ucred->cr_rgid; 257#if defined(COMPAT_43) 258 td->td_retval[1] = td->td_ucred->cr_groups[0]; 259#endif 260 return (0); 261} 262 263/* 264 * Get effective group ID. The "egid" is groups[0], and could be obtained 265 * via getgroups. This syscall exists because it is somewhat painful to do 266 * correctly in a library function. 267 */ 268#ifndef _SYS_SYSPROTO_H_ 269struct getegid_args { 270 int dummy; 271}; 272#endif 273/* 274 * MPSAFE 275 */ 276/* ARGSUSED */ 277int 278getegid(struct thread *td, struct getegid_args *uap) 279{ 280 281 td->td_retval[0] = td->td_ucred->cr_groups[0]; 282 return (0); 283} 284 285#ifndef _SYS_SYSPROTO_H_ 286struct getgroups_args { 287 u_int gidsetsize; 288 gid_t *gidset; 289}; 290#endif 291/* 292 * MPSAFE 293 */ 294int 295getgroups(struct thread *td, register struct getgroups_args *uap) 296{ 297 struct ucred *cred; 298 u_int ngrp; 299 int error; 300 301 cred = td->td_ucred; 302 if ((ngrp = uap->gidsetsize) == 0) { 303 td->td_retval[0] = cred->cr_ngroups; 304 return (0); 305 } 306 if (ngrp < cred->cr_ngroups) 307 return (EINVAL); 308 ngrp = cred->cr_ngroups; 309 error = copyout(cred->cr_groups, uap->gidset, ngrp * sizeof(gid_t)); 310 if (error == 0) 311 td->td_retval[0] = ngrp; 312 return (error); 313} 314 315#ifndef _SYS_SYSPROTO_H_ 316struct setsid_args { 317 int dummy; 318}; 319#endif 320/* 321 * MPSAFE 322 */ 323/* ARGSUSED */ 324int 325setsid(register struct thread *td, struct setsid_args *uap) 326{ 327 struct pgrp *pgrp; 328 int error; 329 struct proc *p = td->td_proc; 330 struct pgrp *newpgrp; 331 struct session *newsess; 332 333 error = 0; 334 pgrp = NULL; 335 336 MALLOC(newpgrp, struct pgrp *, sizeof(struct pgrp), M_PGRP, M_WAITOK | M_ZERO); 337 MALLOC(newsess, struct session *, sizeof(struct session), M_SESSION, M_WAITOK | M_ZERO); 338 339 sx_xlock(&proctree_lock); 340 341 if (p->p_pgid == p->p_pid || (pgrp = pgfind(p->p_pid)) != NULL) { 342 if (pgrp != NULL) 343 PGRP_UNLOCK(pgrp); 344 error = EPERM; 345 } else { 346 (void)enterpgrp(p, p->p_pid, newpgrp, newsess); 347 td->td_retval[0] = p->p_pid; 348 newpgrp = NULL; 349 newsess = NULL; 350 } 351 352 sx_xunlock(&proctree_lock); 353 354 if (newpgrp != NULL) 355 FREE(newpgrp, M_PGRP); 356 if (newsess != NULL) 357 FREE(newsess, M_SESSION); 358 359 return (error); 360} 361 362/* 363 * set process group (setpgid/old setpgrp) 364 * 365 * caller does setpgid(targpid, targpgid) 366 * 367 * pid must be caller or child of caller (ESRCH) 368 * if a child 369 * pid must be in same session (EPERM) 370 * pid can't have done an exec (EACCES) 371 * if pgid != pid 372 * there must exist some pid in same session having pgid (EPERM) 373 * pid must not be session leader (EPERM) 374 */ 375#ifndef _SYS_SYSPROTO_H_ 376struct setpgid_args { 377 int pid; /* target process id */ 378 int pgid; /* target pgrp id */ 379}; 380#endif 381/* 382 * MPSAFE 383 */ 384/* ARGSUSED */ 385int 386setpgid(struct thread *td, register struct setpgid_args *uap) 387{ 388 struct proc *curp = td->td_proc; 389 register struct proc *targp; /* target process */ 390 register struct pgrp *pgrp; /* target pgrp */ 391 int error; 392 struct pgrp *newpgrp; 393 394 if (uap->pgid < 0) 395 return (EINVAL); 396 397 error = 0; 398 399 MALLOC(newpgrp, struct pgrp *, sizeof(struct pgrp), M_PGRP, M_WAITOK | M_ZERO); 400 401 sx_xlock(&proctree_lock); 402 if (uap->pid != 0 && uap->pid != curp->p_pid) { 403 if ((targp = pfind(uap->pid)) == NULL) { 404 error = ESRCH; 405 goto done; 406 } 407 if (!inferior(targp)) { 408 PROC_UNLOCK(targp); 409 error = ESRCH; 410 goto done; 411 } 412 if ((error = p_cansee(td, targp))) { 413 PROC_UNLOCK(targp); 414 goto done; 415 } 416 if (targp->p_pgrp == NULL || 417 targp->p_session != curp->p_session) { 418 PROC_UNLOCK(targp); 419 error = EPERM; 420 goto done; 421 } 422 if (targp->p_flag & P_EXEC) { 423 PROC_UNLOCK(targp); 424 error = EACCES; 425 goto done; 426 } 427 PROC_UNLOCK(targp); 428 } else 429 targp = curp; 430 if (SESS_LEADER(targp)) { 431 error = EPERM; 432 goto done; 433 } 434 if (uap->pgid == 0) 435 uap->pgid = targp->p_pid; 436 if ((pgrp = pgfind(uap->pgid)) == NULL) { 437 if (uap->pgid == targp->p_pid) { 438 error = enterpgrp(targp, uap->pgid, newpgrp, 439 NULL); 440 if (error == 0) 441 newpgrp = NULL; 442 } else 443 error = EPERM; 444 } else { 445 if (pgrp == targp->p_pgrp) { 446 PGRP_UNLOCK(pgrp); 447 goto done; 448 } 449 if (pgrp->pg_id != targp->p_pid && 450 pgrp->pg_session != curp->p_session) { 451 PGRP_UNLOCK(pgrp); 452 error = EPERM; 453 goto done; 454 } 455 PGRP_UNLOCK(pgrp); 456 error = enterthispgrp(targp, pgrp); 457 } 458done: 459 sx_xunlock(&proctree_lock); 460 KASSERT((error == 0) || (newpgrp != NULL), 461 ("setpgid failed and newpgrp is NULL")); 462 if (newpgrp != NULL) 463 FREE(newpgrp, M_PGRP); 464 return (error); 465} 466 467/* 468 * Use the clause in B.4.2.2 that allows setuid/setgid to be 4.2/4.3BSD 469 * compatible. It says that setting the uid/gid to euid/egid is a special 470 * case of "appropriate privilege". Once the rules are expanded out, this 471 * basically means that setuid(nnn) sets all three id's, in all permitted 472 * cases unless _POSIX_SAVED_IDS is enabled. In that case, setuid(getuid()) 473 * does not set the saved id - this is dangerous for traditional BSD 474 * programs. For this reason, we *really* do not want to set 475 * _POSIX_SAVED_IDS and do not want to clear POSIX_APPENDIX_B_4_2_2. 476 */ 477#define POSIX_APPENDIX_B_4_2_2 478 479#ifndef _SYS_SYSPROTO_H_ 480struct setuid_args { 481 uid_t uid; 482}; 483#endif 484/* 485 * MPSAFE 486 */ 487/* ARGSUSED */ 488int 489setuid(struct thread *td, struct setuid_args *uap) 490{ 491 struct proc *p = td->td_proc; 492 struct ucred *newcred, *oldcred; 493 uid_t uid; 494 struct uidinfo *uip; 495 int error; 496 497 uid = uap->uid; 498 newcred = crget(); 499 uip = uifind(uid); 500 PROC_LOCK(p); 501 oldcred = p->p_ucred; 502 503 /* 504 * See if we have "permission" by POSIX 1003.1 rules. 505 * 506 * Note that setuid(geteuid()) is a special case of 507 * "appropriate privileges" in appendix B.4.2.2. We need 508 * to use this clause to be compatible with traditional BSD 509 * semantics. Basically, it means that "setuid(xx)" sets all 510 * three id's (assuming you have privs). 511 * 512 * Notes on the logic. We do things in three steps. 513 * 1: We determine if the euid is going to change, and do EPERM 514 * right away. We unconditionally change the euid later if this 515 * test is satisfied, simplifying that part of the logic. 516 * 2: We determine if the real and/or saved uids are going to 517 * change. Determined by compile options. 518 * 3: Change euid last. (after tests in #2 for "appropriate privs") 519 */ 520 if (uid != oldcred->cr_ruid && /* allow setuid(getuid()) */ 521#ifdef _POSIX_SAVED_IDS 522 uid != oldcred->cr_svuid && /* allow setuid(saved gid) */ 523#endif 524#ifdef POSIX_APPENDIX_B_4_2_2 /* Use BSD-compat clause from B.4.2.2 */ 525 uid != oldcred->cr_uid && /* allow setuid(geteuid()) */ 526#endif 527 (error = suser_cred(oldcred, SUSER_ALLOWJAIL)) != 0) { 528 PROC_UNLOCK(p); 529 uifree(uip); 530 crfree(newcred); 531 return (error); 532 } 533 534 /* 535 * Copy credentials so other references do not see our changes. 536 */ 537 crcopy(newcred, oldcred); 538#ifdef _POSIX_SAVED_IDS 539 /* 540 * Do we have "appropriate privileges" (are we root or uid == euid) 541 * If so, we are changing the real uid and/or saved uid. 542 */ 543 if ( 544#ifdef POSIX_APPENDIX_B_4_2_2 /* Use the clause from B.4.2.2 */ 545 uid == oldcred->cr_uid || 546#endif 547 suser_cred(oldcred, SUSER_ALLOWJAIL) == 0) /* we are using privs */ 548#endif 549 { 550 /* 551 * Set the real uid and transfer proc count to new user. 552 */ 553 if (uid != oldcred->cr_ruid) { 554 change_ruid(newcred, uip); 555 setsugid(p); 556 } 557 /* 558 * Set saved uid 559 * 560 * XXX always set saved uid even if not _POSIX_SAVED_IDS, as 561 * the security of seteuid() depends on it. B.4.2.2 says it 562 * is important that we should do this. 563 */ 564 if (uid != oldcred->cr_svuid) { 565 change_svuid(newcred, uid); 566 setsugid(p); 567 } 568 } 569 570 /* 571 * In all permitted cases, we are changing the euid. 572 */ 573 if (uid != oldcred->cr_uid) { 574 change_euid(newcred, uip); 575 setsugid(p); 576 } 577 p->p_ucred = newcred; 578 PROC_UNLOCK(p); 579 uifree(uip); 580 crfree(oldcred); 581 return (0); 582} 583 584#ifndef _SYS_SYSPROTO_H_ 585struct seteuid_args { 586 uid_t euid; 587}; 588#endif 589/* 590 * MPSAFE 591 */ 592/* ARGSUSED */ 593int 594seteuid(struct thread *td, struct seteuid_args *uap) 595{ 596 struct proc *p = td->td_proc; 597 struct ucred *newcred, *oldcred; 598 uid_t euid; 599 struct uidinfo *euip; 600 int error; 601 602 euid = uap->euid; 603 newcred = crget(); 604 euip = uifind(euid); 605 PROC_LOCK(p); 606 oldcred = p->p_ucred; 607 if (euid != oldcred->cr_ruid && /* allow seteuid(getuid()) */ 608 euid != oldcred->cr_svuid && /* allow seteuid(saved uid) */ 609 (error = suser_cred(oldcred, SUSER_ALLOWJAIL)) != 0) { 610 PROC_UNLOCK(p); 611 uifree(euip); 612 crfree(newcred); 613 return (error); 614 } 615 /* 616 * Everything's okay, do it. Copy credentials so other references do 617 * not see our changes. 618 */ 619 crcopy(newcred, oldcred); 620 if (oldcred->cr_uid != euid) { 621 change_euid(newcred, euip); 622 setsugid(p); 623 } 624 p->p_ucred = newcred; 625 PROC_UNLOCK(p); 626 uifree(euip); 627 crfree(oldcred); 628 return (0); 629} 630 631#ifndef _SYS_SYSPROTO_H_ 632struct setgid_args { 633 gid_t gid; 634}; 635#endif 636/* 637 * MPSAFE 638 */ 639/* ARGSUSED */ 640int 641setgid(struct thread *td, struct setgid_args *uap) 642{ 643 struct proc *p = td->td_proc; 644 struct ucred *newcred, *oldcred; 645 gid_t gid; 646 int error; 647 648 gid = uap->gid; 649 newcred = crget(); 650 PROC_LOCK(p); 651 oldcred = p->p_ucred; 652 653 /* 654 * See if we have "permission" by POSIX 1003.1 rules. 655 * 656 * Note that setgid(getegid()) is a special case of 657 * "appropriate privileges" in appendix B.4.2.2. We need 658 * to use this clause to be compatible with traditional BSD 659 * semantics. Basically, it means that "setgid(xx)" sets all 660 * three id's (assuming you have privs). 661 * 662 * For notes on the logic here, see setuid() above. 663 */ 664 if (gid != oldcred->cr_rgid && /* allow setgid(getgid()) */ 665#ifdef _POSIX_SAVED_IDS 666 gid != oldcred->cr_svgid && /* allow setgid(saved gid) */ 667#endif 668#ifdef POSIX_APPENDIX_B_4_2_2 /* Use BSD-compat clause from B.4.2.2 */ 669 gid != oldcred->cr_groups[0] && /* allow setgid(getegid()) */ 670#endif 671 (error = suser_cred(oldcred, SUSER_ALLOWJAIL)) != 0) { 672 PROC_UNLOCK(p); 673 crfree(newcred); 674 return (error); 675 } 676 677 crcopy(newcred, oldcred); 678#ifdef _POSIX_SAVED_IDS 679 /* 680 * Do we have "appropriate privileges" (are we root or gid == egid) 681 * If so, we are changing the real uid and saved gid. 682 */ 683 if ( 684#ifdef POSIX_APPENDIX_B_4_2_2 /* use the clause from B.4.2.2 */ 685 gid == oldcred->cr_groups[0] || 686#endif 687 suser_cred(oldcred, SUSER_ALLOWJAIL) == 0) /* we are using privs */ 688#endif 689 { 690 /* 691 * Set real gid 692 */ 693 if (oldcred->cr_rgid != gid) { 694 change_rgid(newcred, gid); 695 setsugid(p); 696 } 697 /* 698 * Set saved gid 699 * 700 * XXX always set saved gid even if not _POSIX_SAVED_IDS, as 701 * the security of setegid() depends on it. B.4.2.2 says it 702 * is important that we should do this. 703 */ 704 if (oldcred->cr_svgid != gid) { 705 change_svgid(newcred, gid); 706 setsugid(p); 707 } 708 } 709 /* 710 * In all cases permitted cases, we are changing the egid. 711 * Copy credentials so other references do not see our changes. 712 */ 713 if (oldcred->cr_groups[0] != gid) { 714 change_egid(newcred, gid); 715 setsugid(p); 716 } 717 p->p_ucred = newcred; 718 PROC_UNLOCK(p); 719 crfree(oldcred); 720 return (0); 721} 722 723#ifndef _SYS_SYSPROTO_H_ 724struct setegid_args { 725 gid_t egid; 726}; 727#endif 728/* 729 * MPSAFE 730 */ 731/* ARGSUSED */ 732int 733setegid(struct thread *td, struct setegid_args *uap) 734{ 735 struct proc *p = td->td_proc; 736 struct ucred *newcred, *oldcred; 737 gid_t egid; 738 int error; 739 740 egid = uap->egid; 741 newcred = crget(); 742 PROC_LOCK(p); 743 oldcred = p->p_ucred; 744 if (egid != oldcred->cr_rgid && /* allow setegid(getgid()) */ 745 egid != oldcred->cr_svgid && /* allow setegid(saved gid) */ 746 (error = suser_cred(oldcred, SUSER_ALLOWJAIL)) != 0) { 747 PROC_UNLOCK(p); 748 crfree(newcred); 749 return (error); 750 } 751 crcopy(newcred, oldcred); 752 if (oldcred->cr_groups[0] != egid) { 753 change_egid(newcred, egid); 754 setsugid(p); 755 } 756 p->p_ucred = newcred; 757 PROC_UNLOCK(p); 758 crfree(oldcred); 759 return (0); 760} 761 762#ifndef _SYS_SYSPROTO_H_ 763struct setgroups_args { 764 u_int gidsetsize; 765 gid_t *gidset; 766}; 767#endif 768/* 769 * MPSAFE 770 */ 771/* ARGSUSED */ 772int 773setgroups(struct thread *td, struct setgroups_args *uap) 774{ 775 struct proc *p = td->td_proc; 776 struct ucred *newcred, *tempcred, *oldcred; 777 u_int ngrp; 778 int error; 779 780 ngrp = uap->gidsetsize; 781 if (ngrp > NGROUPS) 782 return (EINVAL); 783 tempcred = crget(); 784 error = copyin(uap->gidset, tempcred->cr_groups, ngrp * sizeof(gid_t)); 785 if (error != 0) { 786 crfree(tempcred); 787 return (error); 788 } 789 newcred = crget(); 790 PROC_LOCK(p); 791 oldcred = p->p_ucred; 792 error = suser_cred(oldcred, SUSER_ALLOWJAIL); 793 if (error) { 794 PROC_UNLOCK(p); 795 crfree(newcred); 796 crfree(tempcred); 797 return (error); 798 } 799 800 /* 801 * XXX A little bit lazy here. We could test if anything has 802 * changed before crcopy() and setting P_SUGID. 803 */ 804 crcopy(newcred, oldcred); 805 if (ngrp < 1) { 806 /* 807 * setgroups(0, NULL) is a legitimate way of clearing the 808 * groups vector on non-BSD systems (which generally do not 809 * have the egid in the groups[0]). We risk security holes 810 * when running non-BSD software if we do not do the same. 811 */ 812 newcred->cr_ngroups = 1; 813 } else { 814 bcopy(tempcred->cr_groups, newcred->cr_groups, 815 ngrp * sizeof(gid_t)); 816 newcred->cr_ngroups = ngrp; 817 } 818 setsugid(p); 819 p->p_ucred = newcred; 820 PROC_UNLOCK(p); 821 crfree(tempcred); 822 crfree(oldcred); 823 return (0); 824} 825 826#ifndef _SYS_SYSPROTO_H_ 827struct setreuid_args { 828 uid_t ruid; 829 uid_t euid; 830}; 831#endif 832/* 833 * MPSAFE 834 */ 835/* ARGSUSED */ 836int 837setreuid(register struct thread *td, struct setreuid_args *uap) 838{ 839 struct proc *p = td->td_proc; 840 struct ucred *newcred, *oldcred; 841 uid_t euid, ruid; 842 struct uidinfo *euip, *ruip; 843 int error; 844 845 euid = uap->euid; 846 ruid = uap->ruid; 847 newcred = crget(); 848 euip = uifind(euid); 849 ruip = uifind(ruid); 850 PROC_LOCK(p); 851 oldcred = p->p_ucred; 852 if (((ruid != (uid_t)-1 && ruid != oldcred->cr_ruid && 853 ruid != oldcred->cr_svuid) || 854 (euid != (uid_t)-1 && euid != oldcred->cr_uid && 855 euid != oldcred->cr_ruid && euid != oldcred->cr_svuid)) && 856 (error = suser_cred(oldcred, SUSER_ALLOWJAIL)) != 0) { 857 PROC_UNLOCK(p); 858 uifree(ruip); 859 uifree(euip); 860 crfree(newcred); 861 return (error); 862 } 863 crcopy(newcred, oldcred); 864 if (euid != (uid_t)-1 && oldcred->cr_uid != euid) { 865 change_euid(newcred, euip); 866 setsugid(p); 867 } 868 if (ruid != (uid_t)-1 && oldcred->cr_ruid != ruid) { 869 change_ruid(newcred, ruip); 870 setsugid(p); 871 } 872 if ((ruid != (uid_t)-1 || newcred->cr_uid != newcred->cr_ruid) && 873 newcred->cr_svuid != newcred->cr_uid) { 874 change_svuid(newcred, newcred->cr_uid); 875 setsugid(p); 876 } 877 p->p_ucred = newcred; 878 PROC_UNLOCK(p); 879 uifree(ruip); 880 uifree(euip); 881 crfree(oldcred); 882 return (0); 883} 884 885#ifndef _SYS_SYSPROTO_H_ 886struct setregid_args { 887 gid_t rgid; 888 gid_t egid; 889}; 890#endif 891/* 892 * MPSAFE 893 */ 894/* ARGSUSED */ 895int 896setregid(register struct thread *td, struct setregid_args *uap) 897{ 898 struct proc *p = td->td_proc; 899 struct ucred *newcred, *oldcred; 900 gid_t egid, rgid; 901 int error; 902 903 egid = uap->egid; 904 rgid = uap->rgid; 905 newcred = crget(); 906 PROC_LOCK(p); 907 oldcred = p->p_ucred; 908 if (((rgid != (gid_t)-1 && rgid != oldcred->cr_rgid && 909 rgid != oldcred->cr_svgid) || 910 (egid != (gid_t)-1 && egid != oldcred->cr_groups[0] && 911 egid != oldcred->cr_rgid && egid != oldcred->cr_svgid)) && 912 (error = suser_cred(oldcred, SUSER_ALLOWJAIL)) != 0) { 913 PROC_UNLOCK(p); 914 crfree(newcred); 915 return (error); 916 } 917 918 crcopy(newcred, oldcred); 919 if (egid != (gid_t)-1 && oldcred->cr_groups[0] != egid) { 920 change_egid(newcred, egid); 921 setsugid(p); 922 } 923 if (rgid != (gid_t)-1 && oldcred->cr_rgid != rgid) { 924 change_rgid(newcred, rgid); 925 setsugid(p); 926 } 927 if ((rgid != (gid_t)-1 || newcred->cr_groups[0] != newcred->cr_rgid) && 928 newcred->cr_svgid != newcred->cr_groups[0]) { 929 change_svgid(newcred, newcred->cr_groups[0]); 930 setsugid(p); 931 } 932 p->p_ucred = newcred; 933 PROC_UNLOCK(p); 934 crfree(oldcred); 935 return (0); 936} 937 938/* 939 * setresuid(ruid, euid, suid) is like setreuid except control over the 940 * saved uid is explicit. 941 */ 942 943#ifndef _SYS_SYSPROTO_H_ 944struct setresuid_args { 945 uid_t ruid; 946 uid_t euid; 947 uid_t suid; 948}; 949#endif 950/* 951 * MPSAFE 952 */ 953/* ARGSUSED */ 954int 955setresuid(register struct thread *td, struct setresuid_args *uap) 956{ 957 struct proc *p = td->td_proc; 958 struct ucred *newcred, *oldcred; 959 uid_t euid, ruid, suid; 960 struct uidinfo *euip, *ruip; 961 int error; 962 963 euid = uap->euid; 964 ruid = uap->ruid; 965 suid = uap->suid; 966 newcred = crget(); 967 euip = uifind(euid); 968 ruip = uifind(ruid); 969 PROC_LOCK(p); 970 oldcred = p->p_ucred; 971 if (((ruid != (uid_t)-1 && ruid != oldcred->cr_ruid && 972 ruid != oldcred->cr_svuid && 973 ruid != oldcred->cr_uid) || 974 (euid != (uid_t)-1 && euid != oldcred->cr_ruid && 975 euid != oldcred->cr_svuid && 976 euid != oldcred->cr_uid) || 977 (suid != (uid_t)-1 && suid != oldcred->cr_ruid && 978 suid != oldcred->cr_svuid && 979 suid != oldcred->cr_uid)) && 980 (error = suser_cred(oldcred, SUSER_ALLOWJAIL)) != 0) { 981 PROC_UNLOCK(p); 982 uifree(ruip); 983 uifree(euip); 984 crfree(newcred); 985 return (error); 986 } 987 988 crcopy(newcred, oldcred); 989 if (euid != (uid_t)-1 && oldcred->cr_uid != euid) { 990 change_euid(newcred, euip); 991 setsugid(p); 992 } 993 if (ruid != (uid_t)-1 && oldcred->cr_ruid != ruid) { 994 change_ruid(newcred, ruip); 995 setsugid(p); 996 } 997 if (suid != (uid_t)-1 && oldcred->cr_svuid != suid) { 998 change_svuid(newcred, suid); 999 setsugid(p); 1000 } 1001 p->p_ucred = newcred; 1002 PROC_UNLOCK(p); 1003 uifree(ruip); 1004 uifree(euip); 1005 crfree(oldcred); 1006 return (0); 1007} 1008 1009/* 1010 * setresgid(rgid, egid, sgid) is like setregid except control over the 1011 * saved gid is explicit. 1012 */ 1013 1014#ifndef _SYS_SYSPROTO_H_ 1015struct setresgid_args { 1016 gid_t rgid; 1017 gid_t egid; 1018 gid_t sgid; 1019}; 1020#endif 1021/* 1022 * MPSAFE 1023 */ 1024/* ARGSUSED */ 1025int 1026setresgid(register struct thread *td, struct setresgid_args *uap) 1027{ 1028 struct proc *p = td->td_proc; 1029 struct ucred *newcred, *oldcred; 1030 gid_t egid, rgid, sgid; 1031 int error; 1032 1033 egid = uap->egid; 1034 rgid = uap->rgid; 1035 sgid = uap->sgid; 1036 newcred = crget(); 1037 PROC_LOCK(p); 1038 oldcred = p->p_ucred; 1039 if (((rgid != (gid_t)-1 && rgid != oldcred->cr_rgid && 1040 rgid != oldcred->cr_svgid && 1041 rgid != oldcred->cr_groups[0]) || 1042 (egid != (gid_t)-1 && egid != oldcred->cr_rgid && 1043 egid != oldcred->cr_svgid && 1044 egid != oldcred->cr_groups[0]) || 1045 (sgid != (gid_t)-1 && sgid != oldcred->cr_rgid && 1046 sgid != oldcred->cr_svgid && 1047 sgid != oldcred->cr_groups[0])) && 1048 (error = suser_cred(oldcred, SUSER_ALLOWJAIL)) != 0) { 1049 PROC_UNLOCK(p); 1050 crfree(newcred); 1051 return (error); 1052 } 1053 1054 crcopy(newcred, oldcred); 1055 if (egid != (gid_t)-1 && oldcred->cr_groups[0] != egid) { 1056 change_egid(newcred, egid); 1057 setsugid(p); 1058 } 1059 if (rgid != (gid_t)-1 && oldcred->cr_rgid != rgid) { 1060 change_rgid(newcred, rgid); 1061 setsugid(p); 1062 } 1063 if (sgid != (gid_t)-1 && oldcred->cr_svgid != sgid) { 1064 change_svgid(newcred, sgid); 1065 setsugid(p); 1066 } 1067 p->p_ucred = newcred; 1068 PROC_UNLOCK(p); 1069 crfree(oldcred); 1070 return (0); 1071} 1072 1073#ifndef _SYS_SYSPROTO_H_ 1074struct getresuid_args { 1075 uid_t *ruid; 1076 uid_t *euid; 1077 uid_t *suid; 1078}; 1079#endif 1080/* 1081 * MPSAFE 1082 */ 1083/* ARGSUSED */ 1084int 1085getresuid(register struct thread *td, struct getresuid_args *uap) 1086{ 1087 struct ucred *cred; 1088 int error1 = 0, error2 = 0, error3 = 0; 1089 1090 cred = td->td_ucred; 1091 if (uap->ruid) 1092 error1 = copyout(&cred->cr_ruid, 1093 uap->ruid, sizeof(cred->cr_ruid)); 1094 if (uap->euid) 1095 error2 = copyout(&cred->cr_uid, 1096 uap->euid, sizeof(cred->cr_uid)); 1097 if (uap->suid) 1098 error3 = copyout(&cred->cr_svuid, 1099 uap->suid, sizeof(cred->cr_svuid)); 1100 return (error1 ? error1 : error2 ? error2 : error3); 1101} 1102 1103#ifndef _SYS_SYSPROTO_H_ 1104struct getresgid_args { 1105 gid_t *rgid; 1106 gid_t *egid; 1107 gid_t *sgid; 1108}; 1109#endif 1110/* 1111 * MPSAFE 1112 */ 1113/* ARGSUSED */ 1114int 1115getresgid(register struct thread *td, struct getresgid_args *uap) 1116{ 1117 struct ucred *cred; 1118 int error1 = 0, error2 = 0, error3 = 0; 1119 1120 cred = td->td_ucred; 1121 if (uap->rgid) 1122 error1 = copyout(&cred->cr_rgid, 1123 uap->rgid, sizeof(cred->cr_rgid)); 1124 if (uap->egid) 1125 error2 = copyout(&cred->cr_groups[0], 1126 uap->egid, sizeof(cred->cr_groups[0])); 1127 if (uap->sgid) 1128 error3 = copyout(&cred->cr_svgid, 1129 uap->sgid, sizeof(cred->cr_svgid)); 1130 return (error1 ? error1 : error2 ? error2 : error3); 1131} 1132 1133#ifndef _SYS_SYSPROTO_H_ 1134struct issetugid_args { 1135 int dummy; 1136}; 1137#endif 1138/* 1139 * MPSAFE 1140 */ 1141/* ARGSUSED */ 1142int 1143issetugid(register struct thread *td, struct issetugid_args *uap) 1144{ 1145 struct proc *p = td->td_proc; 1146 1147 /* 1148 * Note: OpenBSD sets a P_SUGIDEXEC flag set at execve() time, 1149 * we use P_SUGID because we consider changing the owners as 1150 * "tainting" as well. 1151 * This is significant for procs that start as root and "become" 1152 * a user without an exec - programs cannot know *everything* 1153 * that libc *might* have put in their data segment. 1154 */ 1155 PROC_LOCK(p); 1156 td->td_retval[0] = (p->p_flag & P_SUGID) ? 1 : 0; 1157 PROC_UNLOCK(p); 1158 return (0); 1159} 1160 1161/* 1162 * MPSAFE 1163 */ 1164int 1165__setugid(struct thread *td, struct __setugid_args *uap) 1166{ 1167#ifdef REGRESSION 1168 struct proc *p; 1169 1170 p = td->td_proc; 1171 switch (uap->flag) { 1172 case 0: 1173 PROC_LOCK(p); 1174 p->p_flag &= ~P_SUGID; 1175 PROC_UNLOCK(p); 1176 return (0); 1177 case 1: 1178 PROC_LOCK(p); 1179 p->p_flag |= P_SUGID; 1180 PROC_UNLOCK(p); 1181 return (0); 1182 default: 1183 return (EINVAL); 1184 } 1185#else /* !REGRESSION */ 1186 1187 return (ENOSYS); 1188#endif /* REGRESSION */ 1189} 1190 1191/* 1192 * Check if gid is a member of the group set. 1193 * 1194 * MPSAFE (cred must be held) 1195 */ 1196int 1197groupmember(gid_t gid, struct ucred *cred) 1198{ 1199 register gid_t *gp; 1200 gid_t *egp; 1201 1202 egp = &(cred->cr_groups[cred->cr_ngroups]); 1203 for (gp = cred->cr_groups; gp < egp; gp++) 1204 if (*gp == gid) 1205 return (1); 1206 return (0); 1207} 1208 1209/* 1210 * `suser_enabled' (which can be set by the security.suser_enabled 1211 * sysctl) determines whether the system 'super-user' policy is in effect. 1212 * If it is nonzero, an effective uid of 0 connotes special privilege, 1213 * overriding many mandatory and discretionary protections. If it is zero, 1214 * uid 0 is offered no special privilege in the kernel security policy. 1215 * Setting it to zero may seriously impact the functionality of many 1216 * existing userland programs, and should not be done without careful 1217 * consideration of the consequences. 1218 */ 1219int suser_enabled = 1; 1220SYSCTL_INT(_security_bsd, OID_AUTO, suser_enabled, CTLFLAG_RW, 1221 &suser_enabled, 0, "processes with uid 0 have privilege"); 1222TUNABLE_INT("security.bsd.suser_enabled", &suser_enabled); 1223 1224/* 1225 * Test whether the specified credentials imply "super-user" privilege. 1226 * Return 0 or EPERM. 1227 */ 1228int 1229suser_cred(struct ucred *cred, int flag) 1230{ 1231 1232 if (!suser_enabled) 1233 return (EPERM); 1234 if (((flag & SUSER_RUID) ? cred->cr_ruid : cred->cr_uid) != 0) 1235 return (EPERM); 1236 if (jailed(cred) && !(flag & SUSER_ALLOWJAIL)) 1237 return (EPERM); 1238 return (0); 1239} 1240 1241/* 1242 * Shortcut to hide contents of struct td and struct proc from the 1243 * caller, promoting binary compatibility. 1244 */ 1245int 1246suser(struct thread *td) 1247{ 1248 1249#ifdef INVARIANTS 1250 if (td != curthread) { 1251 printf("suser: thread %p (%d %s) != curthread %p (%d %s)\n", 1252 td, td->td_proc->p_pid, td->td_proc->p_comm, 1253 curthread, curthread->td_proc->p_pid, 1254 curthread->td_proc->p_comm); 1255#ifdef KDB 1256 kdb_backtrace(); 1257#endif 1258 } 1259#endif 1260 return (suser_cred(td->td_ucred, 0)); 1261} 1262 1263/* 1264 * Test the active securelevel against a given level. securelevel_gt() 1265 * implements (securelevel > level). securelevel_ge() implements 1266 * (securelevel >= level). Note that the logic is inverted -- these 1267 * functions return EPERM on "success" and 0 on "failure". 1268 * 1269 * MPSAFE 1270 */ 1271int 1272securelevel_gt(struct ucred *cr, int level) 1273{ 1274 int active_securelevel; 1275 1276 active_securelevel = securelevel; 1277 KASSERT(cr != NULL, ("securelevel_gt: null cr")); 1278 if (cr->cr_prison != NULL) 1279 active_securelevel = imax(cr->cr_prison->pr_securelevel, 1280 active_securelevel); 1281 return (active_securelevel > level ? EPERM : 0); 1282} 1283 1284int 1285securelevel_ge(struct ucred *cr, int level) 1286{ 1287 int active_securelevel; 1288 1289 active_securelevel = securelevel; 1290 KASSERT(cr != NULL, ("securelevel_ge: null cr")); 1291 if (cr->cr_prison != NULL) 1292 active_securelevel = imax(cr->cr_prison->pr_securelevel, 1293 active_securelevel); 1294 return (active_securelevel >= level ? EPERM : 0); 1295} 1296 1297/* 1298 * 'see_other_uids' determines whether or not visibility of processes 1299 * and sockets with credentials holding different real uids is possible 1300 * using a variety of system MIBs. 1301 * XXX: data declarations should be together near the beginning of the file. 1302 */ 1303static int see_other_uids = 1; 1304SYSCTL_INT(_security_bsd, OID_AUTO, see_other_uids, CTLFLAG_RW, 1305 &see_other_uids, 0, 1306 "Unprivileged processes may see subjects/objects with different real uid"); 1307 1308/*- 1309 * Determine if u1 "can see" the subject specified by u2, according to the 1310 * 'see_other_uids' policy. 1311 * Returns: 0 for permitted, ESRCH otherwise 1312 * Locks: none 1313 * References: *u1 and *u2 must not change during the call 1314 * u1 may equal u2, in which case only one reference is required 1315 */ 1316static int 1317cr_seeotheruids(struct ucred *u1, struct ucred *u2) 1318{ 1319 1320 if (!see_other_uids && u1->cr_ruid != u2->cr_ruid) { 1321 if (suser_cred(u1, SUSER_ALLOWJAIL) != 0) 1322 return (ESRCH); 1323 } 1324 return (0); 1325} 1326 1327/* 1328 * 'see_other_gids' determines whether or not visibility of processes 1329 * and sockets with credentials holding different real gids is possible 1330 * using a variety of system MIBs. 1331 * XXX: data declarations should be together near the beginning of the file. 1332 */ 1333static int see_other_gids = 1; 1334SYSCTL_INT(_security_bsd, OID_AUTO, see_other_gids, CTLFLAG_RW, 1335 &see_other_gids, 0, 1336 "Unprivileged processes may see subjects/objects with different real gid"); 1337 1338/* 1339 * Determine if u1 can "see" the subject specified by u2, according to the 1340 * 'see_other_gids' policy. 1341 * Returns: 0 for permitted, ESRCH otherwise 1342 * Locks: none 1343 * References: *u1 and *u2 must not change during the call 1344 * u1 may equal u2, in which case only one reference is required 1345 */ 1346static int 1347cr_seeothergids(struct ucred *u1, struct ucred *u2) 1348{ 1349 int i, match; 1350 1351 if (!see_other_gids) { 1352 match = 0; 1353 for (i = 0; i < u1->cr_ngroups; i++) { 1354 if (groupmember(u1->cr_groups[i], u2)) 1355 match = 1; 1356 if (match) 1357 break; 1358 } 1359 if (!match) { 1360 if (suser_cred(u1, SUSER_ALLOWJAIL) != 0) 1361 return (ESRCH); 1362 } 1363 } 1364 return (0); 1365} 1366 1367/*- 1368 * Determine if u1 "can see" the subject specified by u2. 1369 * Returns: 0 for permitted, an errno value otherwise 1370 * Locks: none 1371 * References: *u1 and *u2 must not change during the call 1372 * u1 may equal u2, in which case only one reference is required 1373 */ 1374int 1375cr_cansee(struct ucred *u1, struct ucred *u2) 1376{ 1377 int error; 1378 1379 if ((error = prison_check(u1, u2))) 1380 return (error); 1381#ifdef MAC 1382 if ((error = mac_check_cred_visible(u1, u2))) 1383 return (error); 1384#endif 1385 if ((error = cr_seeotheruids(u1, u2))) 1386 return (error); 1387 if ((error = cr_seeothergids(u1, u2))) 1388 return (error); 1389 return (0); 1390} 1391 1392/*- 1393 * Determine if td "can see" the subject specified by p. 1394 * Returns: 0 for permitted, an errno value otherwise 1395 * Locks: Sufficient locks to protect p->p_ucred must be held. td really 1396 * should be curthread. 1397 * References: td and p must be valid for the lifetime of the call 1398 */ 1399int 1400p_cansee(struct thread *td, struct proc *p) 1401{ 1402 1403 /* Wrap cr_cansee() for all functionality. */ 1404 KASSERT(td == curthread, ("%s: td not curthread", __func__)); 1405 PROC_LOCK_ASSERT(p, MA_OWNED); 1406 return (cr_cansee(td->td_ucred, p->p_ucred)); 1407} 1408 1409/* 1410 * 'conservative_signals' prevents the delivery of a broad class of 1411 * signals by unprivileged processes to processes that have changed their 1412 * credentials since the last invocation of execve(). This can prevent 1413 * the leakage of cached information or retained privileges as a result 1414 * of a common class of signal-related vulnerabilities. However, this 1415 * may interfere with some applications that expect to be able to 1416 * deliver these signals to peer processes after having given up 1417 * privilege. 1418 */ 1419static int conservative_signals = 1; 1420SYSCTL_INT(_security_bsd, OID_AUTO, conservative_signals, CTLFLAG_RW, 1421 &conservative_signals, 0, "Unprivileged processes prevented from " 1422 "sending certain signals to processes whose credentials have changed"); 1423/*- 1424 * Determine whether cred may deliver the specified signal to proc. 1425 * Returns: 0 for permitted, an errno value otherwise. 1426 * Locks: A lock must be held for proc. 1427 * References: cred and proc must be valid for the lifetime of the call. 1428 */ 1429int 1430cr_cansignal(struct ucred *cred, struct proc *proc, int signum) 1431{ 1432 int error; 1433 1434 PROC_LOCK_ASSERT(proc, MA_OWNED); 1435 /* 1436 * Jail semantics limit the scope of signalling to proc in the 1437 * same jail as cred, if cred is in jail. 1438 */ 1439 error = prison_check(cred, proc->p_ucred); 1440 if (error) 1441 return (error); 1442#ifdef MAC 1443 if ((error = mac_check_proc_signal(cred, proc, signum))) 1444 return (error); 1445#endif 1446 if ((error = cr_seeotheruids(cred, proc->p_ucred))) 1447 return (error); 1448 if ((error = cr_seeothergids(cred, proc->p_ucred))) 1449 return (error); 1450 1451 /* 1452 * UNIX signal semantics depend on the status of the P_SUGID 1453 * bit on the target process. If the bit is set, then additional 1454 * restrictions are placed on the set of available signals. 1455 */ 1456 if (conservative_signals && (proc->p_flag & P_SUGID)) { 1457 switch (signum) { 1458 case 0: 1459 case SIGKILL: 1460 case SIGINT: 1461 case SIGTERM: 1462 case SIGALRM: 1463 case SIGSTOP: 1464 case SIGTTIN: 1465 case SIGTTOU: 1466 case SIGTSTP: 1467 case SIGHUP: 1468 case SIGUSR1: 1469 case SIGUSR2: 1470 case SIGTHR: 1471 /* 1472 * Generally, permit job and terminal control 1473 * signals. 1474 */ 1475 break; 1476 default: 1477 /* Not permitted without privilege. */ 1478 error = suser_cred(cred, SUSER_ALLOWJAIL); 1479 if (error) 1480 return (error); 1481 } 1482 } 1483 1484 /* 1485 * Generally, the target credential's ruid or svuid must match the 1486 * subject credential's ruid or euid. 1487 */ 1488 if (cred->cr_ruid != proc->p_ucred->cr_ruid && 1489 cred->cr_ruid != proc->p_ucred->cr_svuid && 1490 cred->cr_uid != proc->p_ucred->cr_ruid && 1491 cred->cr_uid != proc->p_ucred->cr_svuid) { 1492 /* Not permitted without privilege. */ 1493 error = suser_cred(cred, SUSER_ALLOWJAIL); 1494 if (error) 1495 return (error); 1496 } 1497 1498 return (0); 1499} 1500 1501 1502/*- 1503 * Determine whether td may deliver the specified signal to p. 1504 * Returns: 0 for permitted, an errno value otherwise 1505 * Locks: Sufficient locks to protect various components of td and p 1506 * must be held. td must be curthread, and a lock must be 1507 * held for p. 1508 * References: td and p must be valid for the lifetime of the call 1509 */ 1510int 1511p_cansignal(struct thread *td, struct proc *p, int signum) 1512{ 1513 1514 KASSERT(td == curthread, ("%s: td not curthread", __func__)); 1515 PROC_LOCK_ASSERT(p, MA_OWNED); 1516 if (td->td_proc == p) 1517 return (0); 1518 1519 /* 1520 * UNIX signalling semantics require that processes in the same 1521 * session always be able to deliver SIGCONT to one another, 1522 * overriding the remaining protections. 1523 */ 1524 /* XXX: This will require an additional lock of some sort. */ 1525 if (signum == SIGCONT && td->td_proc->p_session == p->p_session) 1526 return (0); 1527 1528 return (cr_cansignal(td->td_ucred, p, signum)); 1529} 1530 1531/*- 1532 * Determine whether td may reschedule p. 1533 * Returns: 0 for permitted, an errno value otherwise 1534 * Locks: Sufficient locks to protect various components of td and p 1535 * must be held. td must be curthread, and a lock must 1536 * be held for p. 1537 * References: td and p must be valid for the lifetime of the call 1538 */ 1539int 1540p_cansched(struct thread *td, struct proc *p) 1541{ 1542 int error; 1543 1544 KASSERT(td == curthread, ("%s: td not curthread", __func__)); 1545 PROC_LOCK_ASSERT(p, MA_OWNED); 1546 if (td->td_proc == p) 1547 return (0); 1548 if ((error = prison_check(td->td_ucred, p->p_ucred))) 1549 return (error); 1550#ifdef MAC 1551 if ((error = mac_check_proc_sched(td->td_ucred, p))) 1552 return (error); 1553#endif 1554 if ((error = cr_seeotheruids(td->td_ucred, p->p_ucred))) 1555 return (error); 1556 if ((error = cr_seeothergids(td->td_ucred, p->p_ucred))) 1557 return (error); 1558 if (td->td_ucred->cr_ruid == p->p_ucred->cr_ruid) 1559 return (0); 1560 if (td->td_ucred->cr_uid == p->p_ucred->cr_ruid) 1561 return (0); 1562 if (suser_cred(td->td_ucred, SUSER_ALLOWJAIL) == 0) 1563 return (0); 1564 1565#ifdef CAPABILITIES 1566 if (!cap_check(NULL, td, CAP_SYS_NICE, SUSER_ALLOWJAIL)) 1567 return (0); 1568#endif 1569 1570 return (EPERM); 1571} 1572 1573/* 1574 * The 'unprivileged_proc_debug' flag may be used to disable a variety of 1575 * unprivileged inter-process debugging services, including some procfs 1576 * functionality, ptrace(), and ktrace(). In the past, inter-process 1577 * debugging has been involved in a variety of security problems, and sites 1578 * not requiring the service might choose to disable it when hardening 1579 * systems. 1580 * 1581 * XXX: Should modifying and reading this variable require locking? 1582 * XXX: data declarations should be together near the beginning of the file. 1583 */ 1584static int unprivileged_proc_debug = 1; 1585SYSCTL_INT(_security_bsd, OID_AUTO, unprivileged_proc_debug, CTLFLAG_RW, 1586 &unprivileged_proc_debug, 0, 1587 "Unprivileged processes may use process debugging facilities"); 1588 1589/*- 1590 * Determine whether td may debug p. 1591 * Returns: 0 for permitted, an errno value otherwise 1592 * Locks: Sufficient locks to protect various components of td and p 1593 * must be held. td must be curthread, and a lock must 1594 * be held for p. 1595 * References: td and p must be valid for the lifetime of the call 1596 */ 1597int 1598p_candebug(struct thread *td, struct proc *p) 1599{ 1600 int credentialchanged, error, grpsubset, i, uidsubset; 1601 1602 KASSERT(td == curthread, ("%s: td not curthread", __func__)); 1603 PROC_LOCK_ASSERT(p, MA_OWNED); 1604 if (!unprivileged_proc_debug) { 1605 error = suser_cred(td->td_ucred, SUSER_ALLOWJAIL); 1606 if (error) 1607 return (error); 1608 } 1609 if (td->td_proc == p) 1610 return (0); 1611 if ((error = prison_check(td->td_ucred, p->p_ucred))) 1612 return (error); 1613#ifdef MAC 1614 if ((error = mac_check_proc_debug(td->td_ucred, p))) 1615 return (error); 1616#endif 1617 if ((error = cr_seeotheruids(td->td_ucred, p->p_ucred))) 1618 return (error); 1619 if ((error = cr_seeothergids(td->td_ucred, p->p_ucred))) 1620 return (error); 1621 1622 /* 1623 * Is p's group set a subset of td's effective group set? This 1624 * includes p's egid, group access list, rgid, and svgid. 1625 */ 1626 grpsubset = 1; 1627 for (i = 0; i < p->p_ucred->cr_ngroups; i++) { 1628 if (!groupmember(p->p_ucred->cr_groups[i], td->td_ucred)) { 1629 grpsubset = 0; 1630 break; 1631 } 1632 } 1633 grpsubset = grpsubset && 1634 groupmember(p->p_ucred->cr_rgid, td->td_ucred) && 1635 groupmember(p->p_ucred->cr_svgid, td->td_ucred); 1636 1637 /* 1638 * Are the uids present in p's credential equal to td's 1639 * effective uid? This includes p's euid, svuid, and ruid. 1640 */ 1641 uidsubset = (td->td_ucred->cr_uid == p->p_ucred->cr_uid && 1642 td->td_ucred->cr_uid == p->p_ucred->cr_svuid && 1643 td->td_ucred->cr_uid == p->p_ucred->cr_ruid); 1644 1645 /* 1646 * Has the credential of the process changed since the last exec()? 1647 */ 1648 credentialchanged = (p->p_flag & P_SUGID); 1649 1650 /* 1651 * If p's gids aren't a subset, or the uids aren't a subset, 1652 * or the credential has changed, require appropriate privilege 1653 * for td to debug p. For POSIX.1e capabilities, this will 1654 * require CAP_SYS_PTRACE. 1655 */ 1656 if (!grpsubset || !uidsubset || credentialchanged) { 1657 error = suser_cred(td->td_ucred, SUSER_ALLOWJAIL); 1658 if (error) 1659 return (error); 1660 } 1661 1662 /* Can't trace init when securelevel > 0. */ 1663 if (p == initproc) { 1664 error = securelevel_gt(td->td_ucred, 0); 1665 if (error) 1666 return (error); 1667 } 1668 1669 /* 1670 * Can't trace a process that's currently exec'ing. 1671 * XXX: Note, this is not a security policy decision, it's a 1672 * basic correctness/functionality decision. Therefore, this check 1673 * should be moved to the caller's of p_candebug(). 1674 */ 1675 if ((p->p_flag & P_INEXEC) != 0) 1676 return (EAGAIN); 1677 1678 return (0); 1679} 1680 1681/*- 1682 * Determine whether the subject represented by cred can "see" a socket. 1683 * Returns: 0 for permitted, ENOENT otherwise. 1684 */ 1685int 1686cr_canseesocket(struct ucred *cred, struct socket *so) 1687{ 1688 int error; 1689 1690 error = prison_check(cred, so->so_cred); 1691 if (error) 1692 return (ENOENT); 1693#ifdef MAC 1694 SOCK_LOCK(so); 1695 error = mac_check_socket_visible(cred, so); 1696 SOCK_UNLOCK(so); 1697 if (error) 1698 return (error); 1699#endif 1700 if (cr_seeotheruids(cred, so->so_cred)) 1701 return (ENOENT); 1702 if (cr_seeothergids(cred, so->so_cred)) 1703 return (ENOENT); 1704 1705 return (0); 1706} 1707 1708/* 1709 * Allocate a zeroed cred structure. 1710 * MPSAFE 1711 */ 1712struct ucred * 1713crget(void) 1714{ 1715 register struct ucred *cr; 1716 1717 MALLOC(cr, struct ucred *, sizeof(*cr), M_CRED, M_WAITOK | M_ZERO); 1718 cr->cr_ref = 1; 1719 cr->cr_mtxp = mtx_pool_find(mtxpool_sleep, cr); 1720#ifdef MAC 1721 mac_init_cred(cr); 1722#endif 1723 return (cr); 1724} 1725 1726/* 1727 * Claim another reference to a ucred structure. 1728 * MPSAFE 1729 */ 1730struct ucred * 1731crhold(struct ucred *cr) 1732{ 1733 1734 mtx_lock(cr->cr_mtxp); 1735 cr->cr_ref++; 1736 mtx_unlock(cr->cr_mtxp); 1737 return (cr); 1738} 1739 1740/* 1741 * Free a cred structure. 1742 * Throws away space when ref count gets to 0. 1743 * MPSAFE 1744 */ 1745void 1746crfree(struct ucred *cr) 1747{ 1748 struct mtx *mtxp = cr->cr_mtxp; 1749 1750 mtx_lock(mtxp); 1751 KASSERT(cr->cr_ref > 0, ("bad ucred refcount: %d", cr->cr_ref)); 1752 if (--cr->cr_ref == 0) { 1753 mtx_unlock(mtxp); 1754 /* 1755 * Some callers of crget(), such as nfs_statfs(), 1756 * allocate a temporary credential, but don't 1757 * allocate a uidinfo structure. 1758 */ 1759 if (cr->cr_uidinfo != NULL) 1760 uifree(cr->cr_uidinfo); 1761 if (cr->cr_ruidinfo != NULL) 1762 uifree(cr->cr_ruidinfo); 1763 /* 1764 * Free a prison, if any. 1765 */ 1766 if (jailed(cr)) 1767 prison_free(cr->cr_prison); 1768#ifdef MAC 1769 mac_destroy_cred(cr); 1770#endif 1771 FREE(cr, M_CRED); 1772 } else { 1773 mtx_unlock(mtxp); 1774 } 1775} 1776 1777/* 1778 * Check to see if this ucred is shared. 1779 * MPSAFE 1780 */ 1781int 1782crshared(struct ucred *cr) 1783{ 1784 int shared; 1785 1786 mtx_lock(cr->cr_mtxp); 1787 shared = (cr->cr_ref > 1); 1788 mtx_unlock(cr->cr_mtxp); 1789 return (shared); 1790} 1791 1792/* 1793 * Copy a ucred's contents from a template. Does not block. 1794 * MPSAFE 1795 */ 1796void 1797crcopy(struct ucred *dest, struct ucred *src) 1798{ 1799 1800 KASSERT(crshared(dest) == 0, ("crcopy of shared ucred")); 1801 bcopy(&src->cr_startcopy, &dest->cr_startcopy, 1802 (unsigned)((caddr_t)&src->cr_endcopy - 1803 (caddr_t)&src->cr_startcopy)); 1804 uihold(dest->cr_uidinfo); 1805 uihold(dest->cr_ruidinfo); 1806 if (jailed(dest)) 1807 prison_hold(dest->cr_prison); 1808#ifdef MAC 1809 mac_copy_cred(src, dest); 1810#endif 1811} 1812 1813/* 1814 * Dup cred struct to a new held one. 1815 * MPSAFE 1816 */ 1817struct ucred * 1818crdup(struct ucred *cr) 1819{ 1820 struct ucred *newcr; 1821 1822 newcr = crget(); 1823 crcopy(newcr, cr); 1824 return (newcr); 1825} 1826 1827/* 1828 * Fill in a struct xucred based on a struct ucred. 1829 * MPSAFE 1830 */ 1831void 1832cru2x(struct ucred *cr, struct xucred *xcr) 1833{ 1834 1835 bzero(xcr, sizeof(*xcr)); 1836 xcr->cr_version = XUCRED_VERSION; 1837 xcr->cr_uid = cr->cr_uid; 1838 xcr->cr_ngroups = cr->cr_ngroups; 1839 bcopy(cr->cr_groups, xcr->cr_groups, sizeof(cr->cr_groups)); 1840} 1841 1842/* 1843 * small routine to swap a thread's current ucred for the correct one 1844 * taken from the process. 1845 * MPSAFE 1846 */ 1847void 1848cred_update_thread(struct thread *td) 1849{ 1850 struct proc *p; 1851 struct ucred *cred; 1852 1853 p = td->td_proc; 1854 cred = td->td_ucred; 1855 PROC_LOCK(p); 1856 td->td_ucred = crhold(p->p_ucred); 1857 PROC_UNLOCK(p); 1858 if (cred != NULL) 1859 crfree(cred); 1860} 1861 1862/* 1863 * Get login name, if available. 1864 */ 1865#ifndef _SYS_SYSPROTO_H_ 1866struct getlogin_args { 1867 char *namebuf; 1868 u_int namelen; 1869}; 1870#endif 1871/* 1872 * MPSAFE 1873 */ 1874/* ARGSUSED */ 1875int 1876getlogin(struct thread *td, struct getlogin_args *uap) 1877{ 1878 int error; 1879 char login[MAXLOGNAME]; 1880 struct proc *p = td->td_proc; 1881 1882 if (uap->namelen > MAXLOGNAME) 1883 uap->namelen = MAXLOGNAME; 1884 PROC_LOCK(p); 1885 SESS_LOCK(p->p_session); 1886 bcopy(p->p_session->s_login, login, uap->namelen); 1887 SESS_UNLOCK(p->p_session); 1888 PROC_UNLOCK(p); 1889 error = copyout(login, uap->namebuf, uap->namelen); 1890 return(error); 1891} 1892 1893/* 1894 * Set login name. 1895 */ 1896#ifndef _SYS_SYSPROTO_H_ 1897struct setlogin_args { 1898 char *namebuf; 1899}; 1900#endif 1901/* 1902 * MPSAFE 1903 */ 1904/* ARGSUSED */ 1905int 1906setlogin(struct thread *td, struct setlogin_args *uap) 1907{ 1908 struct proc *p = td->td_proc; 1909 int error; 1910 char logintmp[MAXLOGNAME]; 1911 1912 error = suser_cred(td->td_ucred, SUSER_ALLOWJAIL); 1913 if (error) 1914 return (error); 1915 error = copyinstr(uap->namebuf, logintmp, sizeof(logintmp), NULL); 1916 if (error == ENAMETOOLONG) 1917 error = EINVAL; 1918 else if (!error) { 1919 PROC_LOCK(p); 1920 SESS_LOCK(p->p_session); 1921 (void) memcpy(p->p_session->s_login, logintmp, 1922 sizeof(logintmp)); 1923 SESS_UNLOCK(p->p_session); 1924 PROC_UNLOCK(p); 1925 } 1926 return (error); 1927} 1928 1929void 1930setsugid(struct proc *p) 1931{ 1932 1933 PROC_LOCK_ASSERT(p, MA_OWNED); 1934 p->p_flag |= P_SUGID; 1935 if (!(p->p_pfsflags & PF_ISUGID)) 1936 p->p_stops = 0; 1937} 1938 1939/*- 1940 * Change a process's effective uid. 1941 * Side effects: newcred->cr_uid and newcred->cr_uidinfo will be modified. 1942 * References: newcred must be an exclusive credential reference for the 1943 * duration of the call. 1944 */ 1945void 1946change_euid(struct ucred *newcred, struct uidinfo *euip) 1947{ 1948 1949 newcred->cr_uid = euip->ui_uid; 1950 uihold(euip); 1951 uifree(newcred->cr_uidinfo); 1952 newcred->cr_uidinfo = euip; 1953} 1954 1955/*- 1956 * Change a process's effective gid. 1957 * Side effects: newcred->cr_gid will be modified. 1958 * References: newcred must be an exclusive credential reference for the 1959 * duration of the call. 1960 */ 1961void 1962change_egid(struct ucred *newcred, gid_t egid) 1963{ 1964 1965 newcred->cr_groups[0] = egid; 1966} 1967 1968/*- 1969 * Change a process's real uid. 1970 * Side effects: newcred->cr_ruid will be updated, newcred->cr_ruidinfo 1971 * will be updated, and the old and new cr_ruidinfo proc 1972 * counts will be updated. 1973 * References: newcred must be an exclusive credential reference for the 1974 * duration of the call. 1975 */ 1976void 1977change_ruid(struct ucred *newcred, struct uidinfo *ruip) 1978{ 1979 1980 (void)chgproccnt(newcred->cr_ruidinfo, -1, 0); 1981 newcred->cr_ruid = ruip->ui_uid; 1982 uihold(ruip); 1983 uifree(newcred->cr_ruidinfo); 1984 newcred->cr_ruidinfo = ruip; 1985 (void)chgproccnt(newcred->cr_ruidinfo, 1, 0); 1986} 1987 1988/*- 1989 * Change a process's real gid. 1990 * Side effects: newcred->cr_rgid will be updated. 1991 * References: newcred must be an exclusive credential reference for the 1992 * duration of the call. 1993 */ 1994void 1995change_rgid(struct ucred *newcred, gid_t rgid) 1996{ 1997 1998 newcred->cr_rgid = rgid; 1999} 2000 2001/*- 2002 * Change a process's saved uid. 2003 * Side effects: newcred->cr_svuid will be updated. 2004 * References: newcred must be an exclusive credential reference for the 2005 * duration of the call. 2006 */ 2007void 2008change_svuid(struct ucred *newcred, uid_t svuid) 2009{ 2010 2011 newcred->cr_svuid = svuid; 2012} 2013 2014/*- 2015 * Change a process's saved gid. 2016 * Side effects: newcred->cr_svgid will be updated. 2017 * References: newcred must be an exclusive credential reference for the 2018 * duration of the call. 2019 */ 2020void 2021change_svgid(struct ucred *newcred, gid_t svgid) 2022{ 2023 2024 newcred->cr_svgid = svgid; 2025} 2026