kern_prot.c revision 94619
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 * 3. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the University of 22 * California, Berkeley and its contributors. 23 * 4. Neither the name of the University nor the names of its contributors 24 * may be used to endorse or promote products derived from this software 25 * without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 37 * SUCH DAMAGE. 38 * 39 * @(#)kern_prot.c 8.6 (Berkeley) 1/21/94 40 * $FreeBSD: head/sys/kern/kern_prot.c 94619 2002-04-13 23:07:05Z jhb $ 41 */ 42 43/* 44 * System calls related to processes and protection 45 */ 46 47#include "opt_compat.h" 48 49#include <sys/param.h> 50#include <sys/systm.h> 51#include <sys/acct.h> 52#include <sys/kernel.h> 53#include <sys/lock.h> 54#include <sys/malloc.h> 55#include <sys/mutex.h> 56#include <sys/sx.h> 57#include <sys/proc.h> 58#include <sys/sysproto.h> 59#include <sys/jail.h> 60#include <sys/pioctl.h> 61#include <sys/resourcevar.h> 62#include <sys/socket.h> 63#include <sys/socketvar.h> 64#include <sys/sysctl.h> 65 66static MALLOC_DEFINE(M_CRED, "cred", "credentials"); 67 68SYSCTL_DECL(_security); 69SYSCTL_NODE(_security, OID_AUTO, bsd, CTLFLAG_RW, 0, 70 "BSD security policy"); 71 72#ifndef _SYS_SYSPROTO_H_ 73struct getpid_args { 74 int dummy; 75}; 76#endif 77/* 78 * MPSAFE 79 */ 80/* ARGSUSED */ 81int 82getpid(struct thread *td, struct getpid_args *uap) 83{ 84 struct proc *p = td->td_proc; 85 int s; 86 87 s = mtx_lock_giant(kern_giant_proc); 88 td->td_retval[0] = p->p_pid; 89#if defined(COMPAT_43) || defined(COMPAT_SUNOS) 90 PROC_LOCK(p); 91 td->td_retval[1] = p->p_pptr->p_pid; 92 PROC_UNLOCK(p); 93#endif 94 mtx_unlock_giant(s); 95 return (0); 96} 97 98#ifndef _SYS_SYSPROTO_H_ 99struct getppid_args { 100 int dummy; 101}; 102#endif 103/* 104 * MPSAFE 105 */ 106/* ARGSUSED */ 107int 108getppid(struct thread *td, struct getppid_args *uap) 109{ 110 struct proc *p = td->td_proc; 111 int s; 112 113 s = mtx_lock_giant(kern_giant_proc); 114 PROC_LOCK(p); 115 td->td_retval[0] = p->p_pptr->p_pid; 116 PROC_UNLOCK(p); 117 mtx_unlock_giant(s); 118 return (0); 119} 120 121/* 122 * Get process group ID; note that POSIX getpgrp takes no parameter. 123 */ 124#ifndef _SYS_SYSPROTO_H_ 125struct getpgrp_args { 126 int dummy; 127}; 128#endif 129/* 130 * MPSAFE 131 */ 132int 133getpgrp(struct thread *td, struct getpgrp_args *uap) 134{ 135 struct proc *p = td->td_proc; 136 int s; 137 138 s = mtx_lock_giant(kern_giant_proc); 139 PROC_LOCK(p); 140 td->td_retval[0] = p->p_pgrp->pg_id; 141 PROC_UNLOCK(p); 142 mtx_unlock_giant(s); 143 return (0); 144} 145 146/* Get an arbitary pid's process group id */ 147#ifndef _SYS_SYSPROTO_H_ 148struct getpgid_args { 149 pid_t pid; 150}; 151#endif 152/* 153 * MPSAFE 154 */ 155int 156getpgid(struct thread *td, struct getpgid_args *uap) 157{ 158 struct proc *p = td->td_proc; 159 struct proc *pt; 160 int error; 161 162 mtx_lock(&Giant); 163 error = 0; 164 if (uap->pid == 0) { 165 PROC_LOCK(p); 166 td->td_retval[0] = p->p_pgrp->pg_id; 167 PROC_UNLOCK(p); 168 } else if ((pt = pfind(uap->pid)) == NULL) 169 error = ESRCH; 170 else { 171 error = p_cansee(p, pt); 172 if (error == 0) 173 td->td_retval[0] = pt->p_pgrp->pg_id; 174 PROC_UNLOCK(pt); 175 } 176 mtx_unlock(&Giant); 177 return (error); 178} 179 180/* 181 * Get an arbitary pid's session id. 182 */ 183#ifndef _SYS_SYSPROTO_H_ 184struct getsid_args { 185 pid_t pid; 186}; 187#endif 188/* 189 * MPSAFE 190 */ 191int 192getsid(struct thread *td, struct getsid_args *uap) 193{ 194 struct proc *p = td->td_proc; 195 struct proc *pt; 196 int error; 197 198 mtx_lock(&Giant); 199 error = 0; 200 if (uap->pid == 0) { 201 PROC_LOCK(p); 202 td->td_retval[0] = p->p_session->s_sid; 203 PROC_UNLOCK(p); 204 } else if ((pt = pfind(uap->pid)) == NULL) 205 error = ESRCH; 206 else { 207 error = p_cansee(p, pt); 208 if (error == 0) 209 td->td_retval[0] = pt->p_session->s_sid; 210 PROC_UNLOCK(pt); 211 } 212 mtx_unlock(&Giant); 213 return (error); 214} 215 216#ifndef _SYS_SYSPROTO_H_ 217struct getuid_args { 218 int dummy; 219}; 220#endif 221/* 222 * MPSAFE 223 */ 224/* ARGSUSED */ 225int 226getuid(struct thread *td, struct getuid_args *uap) 227{ 228 229 td->td_retval[0] = td->td_ucred->cr_ruid; 230#if defined(COMPAT_43) || defined(COMPAT_SUNOS) 231 td->td_retval[1] = td->td_ucred->cr_uid; 232#endif 233 return (0); 234} 235 236#ifndef _SYS_SYSPROTO_H_ 237struct geteuid_args { 238 int dummy; 239}; 240#endif 241/* 242 * MPSAFE 243 */ 244/* ARGSUSED */ 245int 246geteuid(struct thread *td, struct geteuid_args *uap) 247{ 248 249 td->td_retval[0] = td->td_ucred->cr_uid; 250 return (0); 251} 252 253#ifndef _SYS_SYSPROTO_H_ 254struct getgid_args { 255 int dummy; 256}; 257#endif 258/* 259 * MPSAFE 260 */ 261/* ARGSUSED */ 262int 263getgid(struct thread *td, struct getgid_args *uap) 264{ 265 266 td->td_retval[0] = td->td_ucred->cr_rgid; 267#if defined(COMPAT_43) || defined(COMPAT_SUNOS) 268 td->td_retval[1] = td->td_ucred->cr_groups[0]; 269#endif 270 return (0); 271} 272 273/* 274 * Get effective group ID. The "egid" is groups[0], and could be obtained 275 * via getgroups. This syscall exists because it is somewhat painful to do 276 * correctly in a library function. 277 */ 278#ifndef _SYS_SYSPROTO_H_ 279struct getegid_args { 280 int dummy; 281}; 282#endif 283/* 284 * MPSAFE 285 */ 286/* ARGSUSED */ 287int 288getegid(struct thread *td, struct getegid_args *uap) 289{ 290 291 td->td_retval[0] = td->td_ucred->cr_groups[0]; 292 return (0); 293} 294 295#ifndef _SYS_SYSPROTO_H_ 296struct getgroups_args { 297 u_int gidsetsize; 298 gid_t *gidset; 299}; 300#endif 301/* 302 * MPSAFE 303 */ 304int 305getgroups(struct thread *td, register struct getgroups_args *uap) 306{ 307 struct ucred *cred; 308 u_int ngrp; 309 int error; 310 311 cred = td->td_ucred; 312 if ((ngrp = uap->gidsetsize) == 0) { 313 td->td_retval[0] = cred->cr_ngroups; 314 return (0); 315 } 316 if (ngrp < cred->cr_ngroups) 317 return (EINVAL); 318 ngrp = cred->cr_ngroups; 319 error = copyout((caddr_t)cred->cr_groups, (caddr_t)uap->gidset, 320 ngrp * sizeof(gid_t)); 321 if (error == 0) 322 td->td_retval[0] = ngrp; 323 return (error); 324} 325 326#ifndef _SYS_SYSPROTO_H_ 327struct setsid_args { 328 int dummy; 329}; 330#endif 331/* 332 * MPSAFE 333 */ 334/* ARGSUSED */ 335int 336setsid(register struct thread *td, struct setsid_args *uap) 337{ 338 struct pgrp *pgrp; 339 int error; 340 struct proc *p = td->td_proc; 341 struct pgrp *newpgrp; 342 struct session *newsess; 343 344 error = 0; 345 pgrp = NULL; 346 347 mtx_lock(&Giant); 348 349 MALLOC(newpgrp, struct pgrp *, sizeof(struct pgrp), M_PGRP, M_WAITOK | M_ZERO); 350 MALLOC(newsess, struct session *, sizeof(struct session), M_SESSION, M_WAITOK | M_ZERO); 351 352 PGRPSESS_XLOCK(); 353 354 if (p->p_pgid == p->p_pid || (pgrp = pgfind(p->p_pid)) != NULL) { 355 if (pgrp != NULL) 356 PGRP_UNLOCK(pgrp); 357 error = EPERM; 358 goto fail; 359 } else { 360 (void)enterpgrp(p, p->p_pid, newpgrp, newsess); 361 td->td_retval[0] = p->p_pid; 362 error = 0; 363 } 364 PGRPSESS_XUNLOCK(); 365 mtx_unlock(&Giant); 366 return (0); 367 368fail: 369 PGRPSESS_XUNLOCK(); 370 371 FREE(newpgrp, M_PGRP); 372 FREE(newsess, M_SESSION); 373 374 mtx_unlock(&Giant); 375 return (0); 376} 377 378/* 379 * set process group (setpgid/old setpgrp) 380 * 381 * caller does setpgid(targpid, targpgid) 382 * 383 * pid must be caller or child of caller (ESRCH) 384 * if a child 385 * pid must be in same session (EPERM) 386 * pid can't have done an exec (EACCES) 387 * if pgid != pid 388 * there must exist some pid in same session having pgid (EPERM) 389 * pid must not be session leader (EPERM) 390 */ 391#ifndef _SYS_SYSPROTO_H_ 392struct setpgid_args { 393 int pid; /* target process id */ 394 int pgid; /* target pgrp id */ 395}; 396#endif 397/* 398 * MPSAFE 399 */ 400/* ARGSUSED */ 401int 402setpgid(struct thread *td, register struct setpgid_args *uap) 403{ 404 struct proc *curp = td->td_proc; 405 register struct proc *targp; /* target process */ 406 register struct pgrp *pgrp; /* target pgrp */ 407 int error; 408 struct pgrp *newpgrp; 409 410 if (uap->pgid < 0) 411 return (EINVAL); 412 413 error = 0; 414 415 mtx_lock(&Giant); 416 417 MALLOC(newpgrp, struct pgrp *, sizeof(struct pgrp), M_PGRP, M_WAITOK | M_ZERO); 418 419 PGRPSESS_XLOCK(); 420 421 if (uap->pid != 0 && uap->pid != curp->p_pid) { 422 sx_slock(&proctree_lock); 423 if ((targp = pfind(uap->pid)) == NULL) { 424 if (targp) 425 PROC_UNLOCK(targp); 426 sx_sunlock(&proctree_lock); 427 error = ESRCH; 428 goto fail; 429 } 430 if (!inferior(targp)) { 431 PROC_UNLOCK(targp); 432 sx_sunlock(&proctree_lock); 433 error = ESRCH; 434 goto fail; 435 } 436 sx_sunlock(&proctree_lock); 437 if ((error = p_cansee(curproc, targp))) { 438 PROC_UNLOCK(targp); 439 goto fail; 440 } 441 if (targp->p_pgrp == NULL || 442 targp->p_session != curp->p_session) { 443 PROC_UNLOCK(targp); 444 error = EPERM; 445 goto fail; 446 } 447 if (targp->p_flag & P_EXEC) { 448 PROC_UNLOCK(targp); 449 error = EACCES; 450 goto fail; 451 } 452 PROC_UNLOCK(targp); 453 } else 454 targp = curp; 455 if (SESS_LEADER(targp)) { 456 error = EPERM; 457 goto fail; 458 } 459 if (uap->pgid == 0) 460 uap->pgid = targp->p_pid; 461 if (uap->pgid == targp->p_pid) { 462 if (targp->p_pgid == uap->pgid) 463 goto done; 464 error = enterpgrp(targp, uap->pgid, newpgrp, NULL); 465 if (error == 0) 466 newpgrp = NULL; 467 } else { 468 if ((pgrp = pgfind(uap->pgid)) == NULL || 469 pgrp->pg_session != curp->p_session) { 470 if (pgrp != NULL) 471 PGRP_UNLOCK(pgrp); 472 error = EPERM; 473 goto fail; 474 } 475 if (pgrp == targp->p_pgrp) { 476 PGRP_UNLOCK(pgrp); 477 goto done; 478 } 479 PGRP_UNLOCK(pgrp); 480 error = enterthispgrp(targp, pgrp); 481 } 482done: 483 PGRPSESS_XUNLOCK(); 484 if (newpgrp != NULL) 485 FREE(newpgrp, M_PGRP); 486 mtx_unlock(&Giant); 487 return (0); 488 489fail: 490 PGRPSESS_XUNLOCK(); 491 492 KASSERT(newpgrp != NULL, ("setpgid failed and newpgrp is null.")); 493 KASSERT(error != 0, ("setpgid successfully failed?")); 494 FREE(newpgrp, M_PGRP); 495 496 mtx_unlock(&Giant); 497 return (error); 498} 499 500/* 501 * Use the clause in B.4.2.2 that allows setuid/setgid to be 4.2/4.3BSD 502 * compatible. It says that setting the uid/gid to euid/egid is a special 503 * case of "appropriate privilege". Once the rules are expanded out, this 504 * basically means that setuid(nnn) sets all three id's, in all permitted 505 * cases unless _POSIX_SAVED_IDS is enabled. In that case, setuid(getuid()) 506 * does not set the saved id - this is dangerous for traditional BSD 507 * programs. For this reason, we *really* do not want to set 508 * _POSIX_SAVED_IDS and do not want to clear POSIX_APPENDIX_B_4_2_2. 509 */ 510#define POSIX_APPENDIX_B_4_2_2 511 512#ifndef _SYS_SYSPROTO_H_ 513struct setuid_args { 514 uid_t uid; 515}; 516#endif 517/* 518 * MPSAFE 519 */ 520/* ARGSUSED */ 521int 522setuid(struct thread *td, struct setuid_args *uap) 523{ 524 struct proc *p = td->td_proc; 525 struct ucred *newcred, *oldcred; 526 uid_t uid; 527 int error; 528 529 mtx_lock(&Giant); 530 uid = uap->uid; 531 newcred = crget(); 532 PROC_LOCK(p); 533 oldcred = p->p_ucred; 534 535 /* 536 * See if we have "permission" by POSIX 1003.1 rules. 537 * 538 * Note that setuid(geteuid()) is a special case of 539 * "appropriate privileges" in appendix B.4.2.2. We need 540 * to use this clause to be compatible with traditional BSD 541 * semantics. Basically, it means that "setuid(xx)" sets all 542 * three id's (assuming you have privs). 543 * 544 * Notes on the logic. We do things in three steps. 545 * 1: We determine if the euid is going to change, and do EPERM 546 * right away. We unconditionally change the euid later if this 547 * test is satisfied, simplifying that part of the logic. 548 * 2: We determine if the real and/or saved uids are going to 549 * change. Determined by compile options. 550 * 3: Change euid last. (after tests in #2 for "appropriate privs") 551 */ 552 if (uid != oldcred->cr_ruid && /* allow setuid(getuid()) */ 553#ifdef _POSIX_SAVED_IDS 554 uid != oldcred->cr_svuid && /* allow setuid(saved gid) */ 555#endif 556#ifdef POSIX_APPENDIX_B_4_2_2 /* Use BSD-compat clause from B.4.2.2 */ 557 uid != oldcred->cr_uid && /* allow setuid(geteuid()) */ 558#endif 559 (error = suser_cred(oldcred, PRISON_ROOT)) != 0) { 560 PROC_UNLOCK(p); 561 crfree(newcred); 562 mtx_unlock(&Giant); 563 return (error); 564 } 565 566 crcopy(newcred, oldcred); 567#ifdef _POSIX_SAVED_IDS 568 /* 569 * Do we have "appropriate privileges" (are we root or uid == euid) 570 * If so, we are changing the real uid and/or saved uid. 571 */ 572 if ( 573#ifdef POSIX_APPENDIX_B_4_2_2 /* Use the clause from B.4.2.2 */ 574 uid == oldcred->cr_uid || 575#endif 576 suser_cred(oldcred, PRISON_ROOT) == 0) /* we are using privs */ 577#endif 578 { 579 /* 580 * Set the real uid and transfer proc count to new user. 581 */ 582 if (uid != oldcred->cr_ruid) { 583 change_ruid(newcred, uid); 584 setsugid(p); 585 } 586 /* 587 * Set saved uid 588 * 589 * XXX always set saved uid even if not _POSIX_SAVED_IDS, as 590 * the security of seteuid() depends on it. B.4.2.2 says it 591 * is important that we should do this. 592 */ 593 if (uid != oldcred->cr_svuid) { 594 change_svuid(newcred, uid); 595 setsugid(p); 596 } 597 } 598 599 /* 600 * In all permitted cases, we are changing the euid. 601 * Copy credentials so other references do not see our changes. 602 */ 603 if (uid != oldcred->cr_uid) { 604 change_euid(newcred, uid); 605 setsugid(p); 606 } 607 p->p_ucred = newcred; 608 PROC_UNLOCK(p); 609 crfree(oldcred); 610 mtx_unlock(&Giant); 611 return (0); 612} 613 614#ifndef _SYS_SYSPROTO_H_ 615struct seteuid_args { 616 uid_t euid; 617}; 618#endif 619/* 620 * MPSAFE 621 */ 622/* ARGSUSED */ 623int 624seteuid(struct thread *td, struct seteuid_args *uap) 625{ 626 struct proc *p = td->td_proc; 627 struct ucred *newcred, *oldcred; 628 uid_t euid; 629 int error; 630 631 euid = uap->euid; 632 mtx_lock(&Giant); 633 newcred = crget(); 634 PROC_LOCK(p); 635 oldcred = p->p_ucred; 636 if (euid != oldcred->cr_ruid && /* allow seteuid(getuid()) */ 637 euid != oldcred->cr_svuid && /* allow seteuid(saved uid) */ 638 (error = suser_cred(oldcred, PRISON_ROOT)) != 0) { 639 PROC_UNLOCK(p); 640 crfree(newcred); 641 mtx_unlock(&Giant); 642 return (error); 643 } 644 /* 645 * Everything's okay, do it. Copy credentials so other references do 646 * not see our changes. 647 */ 648 crcopy(newcred, oldcred); 649 if (oldcred->cr_uid != euid) { 650 change_euid(newcred, euid); 651 setsugid(p); 652 } 653 p->p_ucred = newcred; 654 PROC_UNLOCK(p); 655 crfree(oldcred); 656 mtx_unlock(&Giant); 657 return (0); 658} 659 660#ifndef _SYS_SYSPROTO_H_ 661struct setgid_args { 662 gid_t gid; 663}; 664#endif 665/* 666 * MPSAFE 667 */ 668/* ARGSUSED */ 669int 670setgid(struct thread *td, struct setgid_args *uap) 671{ 672 struct proc *p = td->td_proc; 673 struct ucred *newcred, *oldcred; 674 gid_t gid; 675 int error; 676 677 gid = uap->gid; 678 mtx_lock(&Giant); 679 newcred = crget(); 680 PROC_LOCK(p); 681 oldcred = p->p_ucred; 682 683 /* 684 * See if we have "permission" by POSIX 1003.1 rules. 685 * 686 * Note that setgid(getegid()) is a special case of 687 * "appropriate privileges" in appendix B.4.2.2. We need 688 * to use this clause to be compatible with traditional BSD 689 * semantics. Basically, it means that "setgid(xx)" sets all 690 * three id's (assuming you have privs). 691 * 692 * For notes on the logic here, see setuid() above. 693 */ 694 if (gid != oldcred->cr_rgid && /* allow setgid(getgid()) */ 695#ifdef _POSIX_SAVED_IDS 696 gid != oldcred->cr_svgid && /* allow setgid(saved gid) */ 697#endif 698#ifdef POSIX_APPENDIX_B_4_2_2 /* Use BSD-compat clause from B.4.2.2 */ 699 gid != oldcred->cr_groups[0] && /* allow setgid(getegid()) */ 700#endif 701 (error = suser_cred(oldcred, PRISON_ROOT)) != 0) { 702 PROC_UNLOCK(p); 703 crfree(newcred); 704 mtx_unlock(&Giant); 705 return (error); 706 } 707 708 crcopy(newcred, oldcred); 709#ifdef _POSIX_SAVED_IDS 710 /* 711 * Do we have "appropriate privileges" (are we root or gid == egid) 712 * If so, we are changing the real uid and saved gid. 713 */ 714 if ( 715#ifdef POSIX_APPENDIX_B_4_2_2 /* use the clause from B.4.2.2 */ 716 gid == oldcred->cr_groups[0] || 717#endif 718 suser_cred(oldcred, PRISON_ROOT) == 0) /* we are using privs */ 719#endif 720 { 721 /* 722 * Set real gid 723 */ 724 if (oldcred->cr_rgid != gid) { 725 change_rgid(newcred, gid); 726 setsugid(p); 727 } 728 /* 729 * Set saved gid 730 * 731 * XXX always set saved gid even if not _POSIX_SAVED_IDS, as 732 * the security of setegid() depends on it. B.4.2.2 says it 733 * is important that we should do this. 734 */ 735 if (oldcred->cr_svgid != gid) { 736 change_svgid(newcred, gid); 737 setsugid(p); 738 } 739 } 740 /* 741 * In all cases permitted cases, we are changing the egid. 742 * Copy credentials so other references do not see our changes. 743 */ 744 if (oldcred->cr_groups[0] != gid) { 745 change_egid(newcred, gid); 746 setsugid(p); 747 } 748 p->p_ucred = newcred; 749 PROC_UNLOCK(p); 750 crfree(oldcred); 751 mtx_unlock(&Giant); 752 return (0); 753} 754 755#ifndef _SYS_SYSPROTO_H_ 756struct setegid_args { 757 gid_t egid; 758}; 759#endif 760/* 761 * MPSAFE 762 */ 763/* ARGSUSED */ 764int 765setegid(struct thread *td, struct setegid_args *uap) 766{ 767 struct proc *p = td->td_proc; 768 struct ucred *newcred, *oldcred; 769 gid_t egid; 770 int error; 771 772 egid = uap->egid; 773 mtx_lock(&Giant); 774 newcred = crget(); 775 PROC_LOCK(p); 776 oldcred = p->p_ucred; 777 if (egid != oldcred->cr_rgid && /* allow setegid(getgid()) */ 778 egid != oldcred->cr_svgid && /* allow setegid(saved gid) */ 779 (error = suser_cred(oldcred, PRISON_ROOT)) != 0) { 780 PROC_UNLOCK(p); 781 crfree(newcred); 782 mtx_unlock(&Giant); 783 return (error); 784 } 785 crcopy(newcred, oldcred); 786 if (oldcred->cr_groups[0] != egid) { 787 change_egid(newcred, egid); 788 setsugid(p); 789 } 790 p->p_ucred = newcred; 791 PROC_UNLOCK(p); 792 crfree(oldcred); 793 mtx_unlock(&Giant); 794 return (0); 795} 796 797#ifndef _SYS_SYSPROTO_H_ 798struct setgroups_args { 799 u_int gidsetsize; 800 gid_t *gidset; 801}; 802#endif 803/* 804 * MPSAFE 805 */ 806/* ARGSUSED */ 807int 808setgroups(struct thread *td, struct setgroups_args *uap) 809{ 810 struct proc *p = td->td_proc; 811 struct ucred *newcred, *tempcred, *oldcred; 812 u_int ngrp; 813 int error; 814 815 ngrp = uap->gidsetsize; 816 if (ngrp > NGROUPS) 817 return (EINVAL); 818 mtx_lock(&Giant); 819 tempcred = crget(); 820 error = copyin((caddr_t)uap->gidset, (caddr_t)tempcred->cr_groups, 821 ngrp * sizeof(gid_t)); 822 if (error != 0) { 823 crfree(tempcred); 824 mtx_unlock(&Giant); 825 return (error); 826 } 827 newcred = crget(); 828 PROC_LOCK(p); 829 oldcred = p->p_ucred; 830 error = suser_cred(oldcred, PRISON_ROOT); 831 if (error) { 832 PROC_UNLOCK(p); 833 crfree(newcred); 834 crfree(tempcred); 835 mtx_unlock(&Giant); 836 return (error); 837 } 838 839 /* 840 * XXX A little bit lazy here. We could test if anything has 841 * changed before crcopy() and setting P_SUGID. 842 */ 843 crcopy(newcred, oldcred); 844 if (ngrp < 1) { 845 /* 846 * setgroups(0, NULL) is a legitimate way of clearing the 847 * groups vector on non-BSD systems (which generally do not 848 * have the egid in the groups[0]). We risk security holes 849 * when running non-BSD software if we do not do the same. 850 */ 851 newcred->cr_ngroups = 1; 852 } else { 853 bcopy(tempcred->cr_groups, newcred->cr_groups, 854 ngrp * sizeof(gid_t)); 855 newcred->cr_ngroups = ngrp; 856 } 857 setsugid(p); 858 p->p_ucred = newcred; 859 PROC_UNLOCK(p); 860 crfree(tempcred); 861 crfree(oldcred); 862 mtx_unlock(&Giant); 863 return (0); 864} 865 866#ifndef _SYS_SYSPROTO_H_ 867struct setreuid_args { 868 uid_t ruid; 869 uid_t euid; 870}; 871#endif 872/* 873 * MPSAFE 874 */ 875/* ARGSUSED */ 876int 877setreuid(register struct thread *td, struct setreuid_args *uap) 878{ 879 struct proc *p = td->td_proc; 880 struct ucred *newcred, *oldcred; 881 uid_t euid, ruid; 882 int error; 883 884 euid = uap->euid; 885 ruid = uap->ruid; 886 mtx_lock(&Giant); 887 newcred = crget(); 888 PROC_LOCK(p); 889 oldcred = p->p_ucred; 890 if (((ruid != (uid_t)-1 && ruid != oldcred->cr_ruid && 891 ruid != oldcred->cr_svuid) || 892 (euid != (uid_t)-1 && euid != oldcred->cr_uid && 893 euid != oldcred->cr_ruid && euid != oldcred->cr_svuid)) && 894 (error = suser_cred(oldcred, PRISON_ROOT)) != 0) { 895 PROC_UNLOCK(p); 896 crfree(newcred); 897 mtx_unlock(&Giant); 898 return (error); 899 } 900 crcopy(newcred, oldcred); 901 if (euid != (uid_t)-1 && oldcred->cr_uid != euid) { 902 change_euid(newcred, euid); 903 setsugid(p); 904 } 905 if (ruid != (uid_t)-1 && oldcred->cr_ruid != ruid) { 906 change_ruid(newcred, ruid); 907 setsugid(p); 908 } 909 if ((ruid != (uid_t)-1 || newcred->cr_uid != newcred->cr_ruid) && 910 newcred->cr_svuid != newcred->cr_uid) { 911 change_svuid(newcred, newcred->cr_uid); 912 setsugid(p); 913 } 914 p->p_ucred = newcred; 915 PROC_UNLOCK(p); 916 crfree(oldcred); 917 mtx_unlock(&Giant); 918 return (0); 919} 920 921#ifndef _SYS_SYSPROTO_H_ 922struct setregid_args { 923 gid_t rgid; 924 gid_t egid; 925}; 926#endif 927/* 928 * MPSAFE 929 */ 930/* ARGSUSED */ 931int 932setregid(register struct thread *td, struct setregid_args *uap) 933{ 934 struct proc *p = td->td_proc; 935 struct ucred *newcred, *oldcred; 936 gid_t egid, rgid; 937 int error; 938 939 egid = uap->egid; 940 rgid = uap->rgid; 941 mtx_lock(&Giant); 942 newcred = crget(); 943 PROC_LOCK(p); 944 oldcred = p->p_ucred; 945 if (((rgid != (gid_t)-1 && rgid != oldcred->cr_rgid && 946 rgid != oldcred->cr_svgid) || 947 (egid != (gid_t)-1 && egid != oldcred->cr_groups[0] && 948 egid != oldcred->cr_rgid && egid != oldcred->cr_svgid)) && 949 (error = suser_cred(oldcred, PRISON_ROOT)) != 0) { 950 PROC_UNLOCK(p); 951 crfree(newcred); 952 mtx_unlock(&Giant); 953 return (error); 954 } 955 956 crcopy(newcred, oldcred); 957 if (egid != (gid_t)-1 && oldcred->cr_groups[0] != egid) { 958 change_egid(newcred, egid); 959 setsugid(p); 960 } 961 if (rgid != (gid_t)-1 && oldcred->cr_rgid != rgid) { 962 change_rgid(newcred, rgid); 963 setsugid(p); 964 } 965 if ((rgid != (gid_t)-1 || newcred->cr_groups[0] != newcred->cr_rgid) && 966 newcred->cr_svgid != newcred->cr_groups[0]) { 967 change_svgid(newcred, newcred->cr_groups[0]); 968 setsugid(p); 969 } 970 p->p_ucred = newcred; 971 PROC_UNLOCK(p); 972 crfree(oldcred); 973 mtx_unlock(&Giant); 974 return (0); 975} 976 977/* 978 * setresuid(ruid, euid, suid) is like setreuid except control over the 979 * saved uid is explicit. 980 */ 981 982#ifndef _SYS_SYSPROTO_H_ 983struct setresuid_args { 984 uid_t ruid; 985 uid_t euid; 986 uid_t suid; 987}; 988#endif 989/* 990 * MPSAFE 991 */ 992/* ARGSUSED */ 993int 994setresuid(register struct thread *td, struct setresuid_args *uap) 995{ 996 struct proc *p = td->td_proc; 997 struct ucred *newcred, *oldcred; 998 uid_t euid, ruid, suid; 999 int error; 1000 1001 euid = uap->euid; 1002 ruid = uap->ruid; 1003 suid = uap->suid; 1004 mtx_lock(&Giant); 1005 newcred = crget(); 1006 PROC_LOCK(p); 1007 oldcred = p->p_ucred; 1008 if (((ruid != (uid_t)-1 && ruid != oldcred->cr_ruid && 1009 ruid != oldcred->cr_svuid && 1010 ruid != oldcred->cr_uid) || 1011 (euid != (uid_t)-1 && euid != oldcred->cr_ruid && 1012 euid != oldcred->cr_svuid && 1013 euid != oldcred->cr_uid) || 1014 (suid != (uid_t)-1 && suid != oldcred->cr_ruid && 1015 suid != oldcred->cr_svuid && 1016 suid != oldcred->cr_uid)) && 1017 (error = suser_cred(oldcred, PRISON_ROOT)) != 0) { 1018 PROC_UNLOCK(p); 1019 crfree(newcred); 1020 mtx_unlock(&Giant); 1021 return (error); 1022 } 1023 1024 crcopy(newcred, oldcred); 1025 if (euid != (uid_t)-1 && oldcred->cr_uid != euid) { 1026 change_euid(newcred, euid); 1027 setsugid(p); 1028 } 1029 if (ruid != (uid_t)-1 && oldcred->cr_ruid != ruid) { 1030 change_ruid(newcred, ruid); 1031 setsugid(p); 1032 } 1033 if (suid != (uid_t)-1 && oldcred->cr_svuid != suid) { 1034 change_svuid(newcred, suid); 1035 setsugid(p); 1036 } 1037 p->p_ucred = newcred; 1038 PROC_UNLOCK(p); 1039 crfree(oldcred); 1040 mtx_unlock(&Giant); 1041 return (0); 1042} 1043 1044/* 1045 * setresgid(rgid, egid, sgid) is like setregid except control over the 1046 * saved gid is explicit. 1047 */ 1048 1049#ifndef _SYS_SYSPROTO_H_ 1050struct setresgid_args { 1051 gid_t rgid; 1052 gid_t egid; 1053 gid_t sgid; 1054}; 1055#endif 1056/* 1057 * MPSAFE 1058 */ 1059/* ARGSUSED */ 1060int 1061setresgid(register struct thread *td, struct setresgid_args *uap) 1062{ 1063 struct proc *p = td->td_proc; 1064 struct ucred *newcred, *oldcred; 1065 gid_t egid, rgid, sgid; 1066 int error; 1067 1068 egid = uap->egid; 1069 rgid = uap->rgid; 1070 sgid = uap->sgid; 1071 mtx_lock(&Giant); 1072 newcred = crget(); 1073 PROC_LOCK(p); 1074 oldcred = p->p_ucred; 1075 if (((rgid != (gid_t)-1 && rgid != oldcred->cr_rgid && 1076 rgid != oldcred->cr_svgid && 1077 rgid != oldcred->cr_groups[0]) || 1078 (egid != (gid_t)-1 && egid != oldcred->cr_rgid && 1079 egid != oldcred->cr_svgid && 1080 egid != oldcred->cr_groups[0]) || 1081 (sgid != (gid_t)-1 && sgid != oldcred->cr_rgid && 1082 sgid != oldcred->cr_svgid && 1083 sgid != oldcred->cr_groups[0])) && 1084 (error = suser_cred(oldcred, PRISON_ROOT)) != 0) { 1085 PROC_UNLOCK(p); 1086 crfree(newcred); 1087 mtx_unlock(&Giant); 1088 return (error); 1089 } 1090 1091 crcopy(newcred, oldcred); 1092 if (egid != (gid_t)-1 && oldcred->cr_groups[0] != egid) { 1093 change_egid(newcred, egid); 1094 setsugid(p); 1095 } 1096 if (rgid != (gid_t)-1 && oldcred->cr_rgid != rgid) { 1097 change_rgid(newcred, rgid); 1098 setsugid(p); 1099 } 1100 if (sgid != (gid_t)-1 && oldcred->cr_svgid != sgid) { 1101 change_svgid(newcred, sgid); 1102 setsugid(p); 1103 } 1104 p->p_ucred = newcred; 1105 PROC_UNLOCK(p); 1106 crfree(oldcred); 1107 mtx_unlock(&Giant); 1108 return (0); 1109} 1110 1111#ifndef _SYS_SYSPROTO_H_ 1112struct getresuid_args { 1113 uid_t *ruid; 1114 uid_t *euid; 1115 uid_t *suid; 1116}; 1117#endif 1118/* 1119 * MPSAFE 1120 */ 1121/* ARGSUSED */ 1122int 1123getresuid(register struct thread *td, struct getresuid_args *uap) 1124{ 1125 struct ucred *cred; 1126 int error1 = 0, error2 = 0, error3 = 0; 1127 1128 cred = td->td_ucred; 1129 if (uap->ruid) 1130 error1 = copyout((caddr_t)&cred->cr_ruid, 1131 (caddr_t)uap->ruid, sizeof(cred->cr_ruid)); 1132 if (uap->euid) 1133 error2 = copyout((caddr_t)&cred->cr_uid, 1134 (caddr_t)uap->euid, sizeof(cred->cr_uid)); 1135 if (uap->suid) 1136 error3 = copyout((caddr_t)&cred->cr_svuid, 1137 (caddr_t)uap->suid, sizeof(cred->cr_svuid)); 1138 return (error1 ? error1 : error2 ? error2 : error3); 1139} 1140 1141#ifndef _SYS_SYSPROTO_H_ 1142struct getresgid_args { 1143 gid_t *rgid; 1144 gid_t *egid; 1145 gid_t *sgid; 1146}; 1147#endif 1148/* 1149 * MPSAFE 1150 */ 1151/* ARGSUSED */ 1152int 1153getresgid(register struct thread *td, struct getresgid_args *uap) 1154{ 1155 struct ucred *cred; 1156 int error1 = 0, error2 = 0, error3 = 0; 1157 1158 cred = td->td_ucred; 1159 if (uap->rgid) 1160 error1 = copyout((caddr_t)&cred->cr_rgid, 1161 (caddr_t)uap->rgid, sizeof(cred->cr_rgid)); 1162 if (uap->egid) 1163 error2 = copyout((caddr_t)&cred->cr_groups[0], 1164 (caddr_t)uap->egid, sizeof(cred->cr_groups[0])); 1165 if (uap->sgid) 1166 error3 = copyout((caddr_t)&cred->cr_svgid, 1167 (caddr_t)uap->sgid, sizeof(cred->cr_svgid)); 1168 return (error1 ? error1 : error2 ? error2 : error3); 1169} 1170 1171#ifndef _SYS_SYSPROTO_H_ 1172struct issetugid_args { 1173 int dummy; 1174}; 1175#endif 1176/* 1177 * NOT MPSAFE? 1178 */ 1179/* ARGSUSED */ 1180int 1181issetugid(register struct thread *td, struct issetugid_args *uap) 1182{ 1183 struct proc *p = td->td_proc; 1184 1185 /* 1186 * Note: OpenBSD sets a P_SUGIDEXEC flag set at execve() time, 1187 * we use P_SUGID because we consider changing the owners as 1188 * "tainting" as well. 1189 * This is significant for procs that start as root and "become" 1190 * a user without an exec - programs cannot know *everything* 1191 * that libc *might* have put in their data segment. 1192 */ 1193 PROC_LOCK(p); 1194 td->td_retval[0] = (p->p_flag & P_SUGID) ? 1 : 0; 1195 PROC_UNLOCK(p); 1196 return (0); 1197} 1198 1199/* 1200 * MPSAFE 1201 */ 1202int 1203__setugid(struct thread *td, struct __setugid_args *uap) 1204{ 1205#ifdef REGRESSION 1206 struct proc *p; 1207 1208 p = td->td_proc; 1209 switch (uap->flag) { 1210 case 0: 1211 mtx_lock(&Giant); 1212 PROC_LOCK(p); 1213 p->p_flag &= ~P_SUGID; 1214 PROC_UNLOCK(p); 1215 mtx_unlock(&Giant); 1216 return (0); 1217 case 1: 1218 mtx_lock(&Giant); 1219 PROC_LOCK(p); 1220 p->p_flag |= P_SUGID; 1221 PROC_UNLOCK(p); 1222 mtx_unlock(&Giant); 1223 return (0); 1224 default: 1225 return (EINVAL); 1226 } 1227#else /* !REGRESSION */ 1228 1229 return (ENOSYS); 1230#endif /* REGRESSION */ 1231} 1232 1233/* 1234 * Check if gid is a member of the group set. 1235 * 1236 * MPSAFE (cred must be held) 1237 */ 1238int 1239groupmember(gid_t gid, struct ucred *cred) 1240{ 1241 register gid_t *gp; 1242 gid_t *egp; 1243 1244 egp = &(cred->cr_groups[cred->cr_ngroups]); 1245 for (gp = cred->cr_groups; gp < egp; gp++) 1246 if (*gp == gid) 1247 return (1); 1248 return (0); 1249} 1250 1251/* 1252 * `suser_enabled' (which can be set by the security.suser_enabled 1253 * sysctl) determines whether the system 'super-user' policy is in effect. 1254 * If it is nonzero, an effective uid of 0 connotes special privilege, 1255 * overriding many mandatory and discretionary protections. If it is zero, 1256 * uid 0 is offered no special privilege in the kernel security policy. 1257 * Setting it to zero may seriously impact the functionality of many 1258 * existing userland programs, and should not be done without careful 1259 * consideration of the consequences. 1260 */ 1261int suser_enabled = 1; 1262SYSCTL_INT(_security_bsd, OID_AUTO, suser_enabled, CTLFLAG_RW, 1263 &suser_enabled, 0, "processes with uid 0 have privilege"); 1264TUNABLE_INT("security.bsd.suser_enabled", &suser_enabled); 1265 1266/* 1267 * Test whether the specified credentials imply "super-user" privilege. 1268 * Return 0 or EPERM. The flag argument is currently used only to 1269 * specify jail interaction. 1270 */ 1271int 1272suser_cred(struct ucred *cred, int flag) 1273{ 1274 1275 if (!suser_enabled) 1276 return (EPERM); 1277 if (cred->cr_uid != 0) 1278 return (EPERM); 1279 if (jailed(cred) && !(flag & PRISON_ROOT)) 1280 return (EPERM); 1281 return (0); 1282} 1283 1284/* 1285 * Shortcut to hide contents of struct td and struct proc from the 1286 * caller, promoting binary compatibility. 1287 */ 1288int 1289suser(struct thread *td) 1290{ 1291 1292 return (suser_cred(td->td_ucred, 0)); 1293} 1294 1295/* 1296 * Test the active securelevel against a given level. securelevel_gt() 1297 * implements (securelevel > level). securelevel_ge() implements 1298 * (securelevel >= level). Note that the logic is inverted -- these 1299 * functions return EPERM on "success" and 0 on "failure". 1300 * 1301 * MPSAFE 1302 */ 1303int 1304securelevel_gt(struct ucred *cr, int level) 1305{ 1306 int active_securelevel; 1307 1308 active_securelevel = securelevel; 1309 KASSERT(cr != NULL, ("securelevel_gt: null cr")); 1310 if (cr->cr_prison != NULL) { 1311 mtx_lock(&cr->cr_prison->pr_mtx); 1312 active_securelevel = imax(cr->cr_prison->pr_securelevel, 1313 active_securelevel); 1314 mtx_unlock(&cr->cr_prison->pr_mtx); 1315 } 1316 return (active_securelevel > level ? EPERM : 0); 1317} 1318 1319int 1320securelevel_ge(struct ucred *cr, int level) 1321{ 1322 int active_securelevel; 1323 1324 active_securelevel = securelevel; 1325 KASSERT(cr != NULL, ("securelevel_ge: null cr")); 1326 if (cr->cr_prison != NULL) { 1327 mtx_lock(&cr->cr_prison->pr_mtx); 1328 active_securelevel = imax(cr->cr_prison->pr_securelevel, 1329 active_securelevel); 1330 mtx_unlock(&cr->cr_prison->pr_mtx); 1331 } 1332 return (active_securelevel >= level ? EPERM : 0); 1333} 1334 1335/* 1336 * 'see_other_uids' determines whether or not visibility of processes 1337 * and sockets with credentials holding different real uids is possible 1338 * using a variety of system MIBs. 1339 * XXX: data declarations should be together near the beginning of the file. 1340 */ 1341static int see_other_uids = 1; 1342SYSCTL_INT(_security_bsd, OID_AUTO, see_other_uids, CTLFLAG_RW, 1343 &see_other_uids, 0, 1344 "Unprivileged processes may see subjects/objects with different real uid"); 1345 1346/*- 1347 * Determine if u1 "can see" the subject specified by u2, according to the 1348 * 'see_other_uids' policy. 1349 * Returns: 0 for permitted, ESRCH otherwise 1350 * Locks: none 1351 * References: *u1 and *u2 must not change during the call 1352 * u1 may equal u2, in which case only one reference is required 1353 */ 1354static int 1355cr_seeotheruids(struct ucred *u1, struct ucred *u2) 1356{ 1357 1358 if (!see_other_uids && u1->cr_ruid != u2->cr_ruid) { 1359 if (suser_cred(u1, PRISON_ROOT) != 0) 1360 return (ESRCH); 1361 } 1362 return (0); 1363} 1364 1365/*- 1366 * Determine if u1 "can see" the subject specified by u2. 1367 * Returns: 0 for permitted, an errno value otherwise 1368 * Locks: none 1369 * References: *u1 and *u2 must not change during the call 1370 * u1 may equal u2, in which case only one reference is required 1371 */ 1372int 1373cr_cansee(struct ucred *u1, struct ucred *u2) 1374{ 1375 int error; 1376 1377 if ((error = prison_check(u1, u2))) 1378 return (error); 1379 if ((error = cr_seeotheruids(u1, u2))) 1380 return (error); 1381 return (0); 1382} 1383 1384/*- 1385 * Determine if p1 "can see" the subject specified by p2. 1386 * Returns: 0 for permitted, an errno value otherwise 1387 * Locks: Sufficient locks to protect p1->p_ucred and p2->p_ucred must 1388 * be held. Normally, p1 will be curproc, and a lock must be held 1389 * for p2. 1390 * References: p1 and p2 must be valid for the lifetime of the call 1391 */ 1392int 1393p_cansee(struct proc *p1, struct proc *p2) 1394{ 1395 1396 /* Wrap cr_cansee() for all functionality. */ 1397 return (cr_cansee(p1->p_ucred, p2->p_ucred)); 1398} 1399 1400/*- 1401 * Determine whether cred may deliver the specified signal to proc. 1402 * Returns: 0 for permitted, an errno value otherwise. 1403 * Locks: A lock must be held for proc. 1404 * References: cred and proc must be valid for the lifetime of the call. 1405 */ 1406int 1407cr_cansignal(struct ucred *cred, struct proc *proc, int signum) 1408{ 1409 int error; 1410 1411 /* 1412 * Jail semantics limit the scope of signalling to proc in the 1413 * same jail as cred, if cred is in jail. 1414 */ 1415 error = prison_check(cred, proc->p_ucred); 1416 if (error) 1417 return (error); 1418 error = cr_seeotheruids(cred, proc->p_ucred); 1419 if (error) 1420 return (error); 1421 1422 /* 1423 * UNIX signal semantics depend on the status of the P_SUGID 1424 * bit on the target process. If the bit is set, then additional 1425 * restrictions are placed on the set of available signals. 1426 */ 1427 if (proc->p_flag & P_SUGID) { 1428 switch (signum) { 1429 case 0: 1430 case SIGKILL: 1431 case SIGINT: 1432 case SIGTERM: 1433 case SIGSTOP: 1434 case SIGTTIN: 1435 case SIGTTOU: 1436 case SIGTSTP: 1437 case SIGHUP: 1438 case SIGUSR1: 1439 case SIGUSR2: 1440 /* 1441 * Generally, permit job and terminal control 1442 * signals. 1443 */ 1444 break; 1445 default: 1446 /* Not permitted without privilege. */ 1447 error = suser_cred(cred, PRISON_ROOT); 1448 if (error) 1449 return (error); 1450 } 1451 } 1452 1453 /* 1454 * Generally, the target credential's ruid or svuid must match the 1455 * subject credential's ruid or euid. 1456 */ 1457 if (cred->cr_ruid != proc->p_ucred->cr_ruid && 1458 cred->cr_ruid != proc->p_ucred->cr_svuid && 1459 cred->cr_uid != proc->p_ucred->cr_ruid && 1460 cred->cr_uid != proc->p_ucred->cr_svuid) { 1461 /* Not permitted without privilege. */ 1462 error = suser_cred(cred, PRISON_ROOT); 1463 if (error) 1464 return (error); 1465 } 1466 1467 return (0); 1468} 1469 1470 1471/*- 1472 * Determine whether p1 may deliver the specified signal to p2. 1473 * Returns: 0 for permitted, an errno value otherwise 1474 * Locks: Sufficient locks to protect various components of p1 and p2 1475 * must be held. Normally, p1 will be curproc, and a lock must 1476 * be held for p2. 1477 * References: p1 and p2 must be valid for the lifetime of the call 1478 */ 1479int 1480p_cansignal(struct proc *p1, struct proc *p2, int signum) 1481{ 1482 1483 if (p1 == p2) 1484 return (0); 1485 1486 /* 1487 * UNIX signalling semantics require that processes in the same 1488 * session always be able to deliver SIGCONT to one another, 1489 * overriding the remaining protections. 1490 */ 1491 if (signum == SIGCONT && p1->p_session == p2->p_session) 1492 return (0); 1493 1494 return (cr_cansignal(p1->p_ucred, p2, signum)); 1495} 1496 1497/*- 1498 * Determine whether p1 may reschedule p2. 1499 * Returns: 0 for permitted, an errno value otherwise 1500 * Locks: Sufficient locks to protect various components of p1 and p2 1501 * must be held. Normally, p1 will be curproc, and a lock must 1502 * be held for p2. 1503 * References: p1 and p2 must be valid for the lifetime of the call 1504 */ 1505int 1506p_cansched(struct proc *p1, struct proc *p2) 1507{ 1508 int error; 1509 1510 if (p1 == p2) 1511 return (0); 1512 if ((error = prison_check(p1->p_ucred, p2->p_ucred))) 1513 return (error); 1514 if ((error = cr_seeotheruids(p1->p_ucred, p2->p_ucred))) 1515 return (error); 1516 if (p1->p_ucred->cr_ruid == p2->p_ucred->cr_ruid) 1517 return (0); 1518 if (p1->p_ucred->cr_uid == p2->p_ucred->cr_ruid) 1519 return (0); 1520 if (suser_cred(p1->p_ucred, PRISON_ROOT) == 0) 1521 return (0); 1522 1523#ifdef CAPABILITIES 1524 if (!cap_check(NULL, p1, CAP_SYS_NICE, PRISON_ROOT)) 1525 return (0); 1526#endif 1527 1528 return (EPERM); 1529} 1530 1531/* 1532 * The 'unprivileged_proc_debug' flag may be used to disable a variety of 1533 * unprivileged inter-process debugging services, including some procfs 1534 * functionality, ptrace(), and ktrace(). In the past, inter-process 1535 * debugging has been involved in a variety of security problems, and sites 1536 * not requiring the service might choose to disable it when hardening 1537 * systems. 1538 * 1539 * XXX: Should modifying and reading this variable require locking? 1540 * XXX: data declarations should be together near the beginning of the file. 1541 */ 1542static int unprivileged_proc_debug = 1; 1543SYSCTL_INT(_security_bsd, OID_AUTO, unprivileged_proc_debug, CTLFLAG_RW, 1544 &unprivileged_proc_debug, 0, 1545 "Unprivileged processes may use process debugging facilities"); 1546 1547/*- 1548 * Determine whether p1 may debug p2. 1549 * Returns: 0 for permitted, an errno value otherwise 1550 * Locks: Sufficient locks to protect various components of p1 and p2 1551 * must be held. Normally, p1 will be curproc, and a lock must 1552 * be held for p2. 1553 * References: p1 and p2 must be valid for the lifetime of the call 1554 */ 1555int 1556p_candebug(struct proc *p1, struct proc *p2) 1557{ 1558 int credentialchanged, error, grpsubset, i, uidsubset; 1559 1560 if (!unprivileged_proc_debug) { 1561 error = suser_cred(p1->p_ucred, PRISON_ROOT); 1562 if (error) 1563 return (error); 1564 } 1565 if (p1 == p2) 1566 return (0); 1567 if ((error = prison_check(p1->p_ucred, p2->p_ucred))) 1568 return (error); 1569 if ((error = cr_seeotheruids(p1->p_ucred, p2->p_ucred))) 1570 return (error); 1571 1572 /* 1573 * Is p2's group set a subset of p1's effective group set? This 1574 * includes p2's egid, group access list, rgid, and svgid. 1575 */ 1576 grpsubset = 1; 1577 for (i = 0; i < p2->p_ucred->cr_ngroups; i++) { 1578 if (!groupmember(p2->p_ucred->cr_groups[i], p1->p_ucred)) { 1579 grpsubset = 0; 1580 break; 1581 } 1582 } 1583 grpsubset = grpsubset && 1584 groupmember(p2->p_ucred->cr_rgid, p1->p_ucred) && 1585 groupmember(p2->p_ucred->cr_svgid, p1->p_ucred); 1586 1587 /* 1588 * Are the uids present in p2's credential equal to p1's 1589 * effective uid? This includes p2's euid, svuid, and ruid. 1590 */ 1591 uidsubset = (p1->p_ucred->cr_uid == p2->p_ucred->cr_uid && 1592 p1->p_ucred->cr_uid == p2->p_ucred->cr_svuid && 1593 p1->p_ucred->cr_uid == p2->p_ucred->cr_ruid); 1594 1595 /* 1596 * Has the credential of the process changed since the last exec()? 1597 */ 1598 credentialchanged = (p2->p_flag & P_SUGID); 1599 1600 /* 1601 * If p2's gids aren't a subset, or the uids aren't a subset, 1602 * or the credential has changed, require appropriate privilege 1603 * for p1 to debug p2. For POSIX.1e capabilities, this will 1604 * require CAP_SYS_PTRACE. 1605 */ 1606 if (!grpsubset || !uidsubset || credentialchanged) { 1607 error = suser_cred(p1->p_ucred, PRISON_ROOT); 1608 if (error) 1609 return (error); 1610 } 1611 1612 /* Can't trace init when securelevel > 0. */ 1613 if (p2 == initproc) { 1614 error = securelevel_gt(p1->p_ucred, 0); 1615 if (error) 1616 return (error); 1617 } 1618 1619 /* 1620 * Can't trace a process that's currently exec'ing. 1621 * XXX: Note, this is not a security policy decision, it's a 1622 * basic correctness/functionality decision. Therefore, this check 1623 * should be moved to the caller's of p_candebug(). 1624 */ 1625 if ((p2->p_flag & P_INEXEC) != 0) 1626 return (EAGAIN); 1627 1628 return (0); 1629} 1630 1631/*- 1632 * Determine whether the subject represented by cred can "see" a socket. 1633 * Returns: 0 for permitted, ENOENT otherwise. 1634 */ 1635int 1636cr_canseesocket(struct ucred *cred, struct socket *so) 1637{ 1638 int error; 1639 1640 error = prison_check(cred, so->so_cred); 1641 if (error) 1642 return (ENOENT); 1643 if (cr_seeotheruids(cred, so->so_cred)) 1644 return (ENOENT); 1645#ifdef MAC 1646 /* XXX: error = mac_cred_check_seesocket() here. */ 1647#endif 1648 1649 return (0); 1650} 1651 1652/* 1653 * Allocate a zeroed cred structure. 1654 */ 1655struct ucred * 1656crget(void) 1657{ 1658 register struct ucred *cr; 1659 1660 MALLOC(cr, struct ucred *, sizeof(*cr), M_CRED, M_WAITOK | M_ZERO); 1661 cr->cr_ref = 1; 1662 cr->cr_mtxp = mtx_pool_find(cr); 1663 return (cr); 1664} 1665 1666/* 1667 * Claim another reference to a ucred structure. 1668 */ 1669struct ucred * 1670crhold(struct ucred *cr) 1671{ 1672 1673 mtx_lock(cr->cr_mtxp); 1674 cr->cr_ref++; 1675 mtx_unlock(cr->cr_mtxp); 1676 return (cr); 1677} 1678 1679/* 1680 * Free a cred structure. 1681 * Throws away space when ref count gets to 0. 1682 */ 1683void 1684crfree(struct ucred *cr) 1685{ 1686 struct mtx *mtxp = cr->cr_mtxp; 1687 1688 mtx_lock(mtxp); 1689 KASSERT(cr->cr_ref > 0, ("bad ucred refcount: %d", cr->cr_ref)); 1690 if (--cr->cr_ref == 0) { 1691 /* 1692 * Some callers of crget(), such as nfs_statfs(), 1693 * allocate a temporary credential, but don't 1694 * allocate a uidinfo structure. 1695 */ 1696 mtx_unlock(mtxp); 1697 mtx_lock(&Giant); 1698 if (cr->cr_uidinfo != NULL) 1699 uifree(cr->cr_uidinfo); 1700 if (cr->cr_ruidinfo != NULL) 1701 uifree(cr->cr_ruidinfo); 1702 /* 1703 * Free a prison, if any. 1704 */ 1705 if (jailed(cr)) 1706 prison_free(cr->cr_prison); 1707 FREE((caddr_t)cr, M_CRED); 1708 mtx_unlock(&Giant); 1709 } else { 1710 mtx_unlock(mtxp); 1711 } 1712} 1713 1714/* 1715 * Check to see if this ucred is shared. 1716 */ 1717int 1718crshared(struct ucred *cr) 1719{ 1720 int shared; 1721 1722 mtx_lock(cr->cr_mtxp); 1723 shared = (cr->cr_ref > 1); 1724 mtx_unlock(cr->cr_mtxp); 1725 return (shared); 1726} 1727 1728/* 1729 * Copy a ucred's contents from a template. Does not block. 1730 */ 1731void 1732crcopy(struct ucred *dest, struct ucred *src) 1733{ 1734 1735 KASSERT(crshared(dest) == 0, ("crcopy of shared ucred")); 1736 bcopy(&src->cr_startcopy, &dest->cr_startcopy, 1737 (unsigned)((caddr_t)&src->cr_endcopy - 1738 (caddr_t)&src->cr_startcopy)); 1739 uihold(dest->cr_uidinfo); 1740 uihold(dest->cr_ruidinfo); 1741 if (jailed(dest)) 1742 prison_hold(dest->cr_prison); 1743} 1744 1745/* 1746 * Dup cred struct to a new held one. 1747 */ 1748struct ucred * 1749crdup(struct ucred *cr) 1750{ 1751 struct ucred *newcr; 1752 1753 newcr = crget(); 1754 crcopy(newcr, cr); 1755 return (newcr); 1756} 1757 1758#ifdef DIAGNOSTIC 1759void 1760cred_free_thread(struct thread *td) 1761{ 1762 struct ucred *cred; 1763 1764 cred = td->td_ucred; 1765 td->td_ucred = NULL; 1766 if (cred != NULL) 1767 crfree(cred); 1768} 1769#endif 1770 1771/* 1772 * Fill in a struct xucred based on a struct ucred. 1773 */ 1774void 1775cru2x(struct ucred *cr, struct xucred *xcr) 1776{ 1777 1778 bzero(xcr, sizeof(*xcr)); 1779 xcr->cr_version = XUCRED_VERSION; 1780 xcr->cr_uid = cr->cr_uid; 1781 xcr->cr_ngroups = cr->cr_ngroups; 1782 bcopy(cr->cr_groups, xcr->cr_groups, sizeof(cr->cr_groups)); 1783} 1784 1785/* 1786 * small routine to swap a thread's current ucred for the correct one 1787 * taken from the process. 1788 */ 1789void 1790cred_update_thread(struct thread *td) 1791{ 1792 struct proc *p; 1793 struct ucred *cred; 1794 1795 p = td->td_proc; 1796 cred = td->td_ucred; 1797 mtx_lock(&Giant); 1798 PROC_LOCK(p); 1799 td->td_ucred = crhold(p->p_ucred); 1800 PROC_UNLOCK(p); 1801 if (cred != NULL) 1802 crfree(cred); 1803 mtx_unlock(&Giant); 1804} 1805 1806/* 1807 * Get login name, if available. 1808 */ 1809#ifndef _SYS_SYSPROTO_H_ 1810struct getlogin_args { 1811 char *namebuf; 1812 u_int namelen; 1813}; 1814#endif 1815/* 1816 * MPSAFE 1817 */ 1818/* ARGSUSED */ 1819int 1820getlogin(struct thread *td, struct getlogin_args *uap) 1821{ 1822 int error; 1823 char login[MAXLOGNAME]; 1824 struct proc *p = td->td_proc; 1825 1826 mtx_lock(&Giant); 1827 if (uap->namelen > MAXLOGNAME) 1828 uap->namelen = MAXLOGNAME; 1829 PROC_LOCK(p); 1830 SESS_LOCK(p->p_session); 1831 bcopy(p->p_session->s_login, login, uap->namelen); 1832 SESS_UNLOCK(p->p_session); 1833 PROC_UNLOCK(p); 1834 error = copyout((caddr_t) login, (caddr_t) uap->namebuf, uap->namelen); 1835 mtx_unlock(&Giant); 1836 return(error); 1837} 1838 1839/* 1840 * Set login name. 1841 */ 1842#ifndef _SYS_SYSPROTO_H_ 1843struct setlogin_args { 1844 char *namebuf; 1845}; 1846#endif 1847/* 1848 * MPSAFE 1849 */ 1850/* ARGSUSED */ 1851int 1852setlogin(struct thread *td, struct setlogin_args *uap) 1853{ 1854 struct proc *p = td->td_proc; 1855 int error; 1856 char logintmp[MAXLOGNAME]; 1857 1858 error = suser_cred(td->td_ucred, PRISON_ROOT); 1859 if (error) 1860 return (error); 1861 error = copyinstr((caddr_t) uap->namebuf, (caddr_t) logintmp, 1862 sizeof(logintmp), (size_t *)0); 1863 if (error == ENAMETOOLONG) 1864 error = EINVAL; 1865 else if (!error) { 1866 PROC_LOCK(p); 1867 SESS_LOCK(p->p_session); 1868 (void) memcpy(p->p_session->s_login, logintmp, 1869 sizeof(logintmp)); 1870 SESS_UNLOCK(p->p_session); 1871 PROC_UNLOCK(p); 1872 } 1873 return (error); 1874} 1875 1876void 1877setsugid(struct proc *p) 1878{ 1879 p->p_flag |= P_SUGID; 1880 if (!(p->p_pfsflags & PF_ISUGID)) 1881 p->p_stops = 0; 1882} 1883 1884/*- 1885 * Change a process's effective uid. 1886 * Side effects: newcred->cr_uid and newcred->cr_uidinfo will be modified. 1887 * References: newcred must be an exclusive credential reference for the 1888 * duration of the call. 1889 */ 1890void 1891change_euid(struct ucred *newcred, uid_t euid) 1892{ 1893 1894 newcred->cr_uid = euid; 1895 uifree(newcred->cr_uidinfo); 1896 newcred->cr_uidinfo = uifind(euid); 1897} 1898 1899/*- 1900 * Change a process's effective gid. 1901 * Side effects: newcred->cr_gid will be modified. 1902 * References: newcred must be an exclusive credential reference for the 1903 * duration of the call. 1904 */ 1905void 1906change_egid(struct ucred *newcred, gid_t egid) 1907{ 1908 1909 newcred->cr_groups[0] = egid; 1910} 1911 1912/*- 1913 * Change a process's real uid. 1914 * Side effects: newcred->cr_ruid will be updated, newcred->cr_ruidinfo 1915 * will be updated, and the old and new cr_ruidinfo proc 1916 * counts will be updated. 1917 * References: newcred must be an exclusive credential reference for the 1918 * duration of the call. 1919 */ 1920void 1921change_ruid(struct ucred *newcred, uid_t ruid) 1922{ 1923 1924 (void)chgproccnt(newcred->cr_ruidinfo, -1, 0); 1925 newcred->cr_ruid = ruid; 1926 uifree(newcred->cr_ruidinfo); 1927 newcred->cr_ruidinfo = uifind(ruid); 1928 (void)chgproccnt(newcred->cr_ruidinfo, 1, 0); 1929} 1930 1931/*- 1932 * Change a process's real gid. 1933 * Side effects: newcred->cr_rgid will be updated. 1934 * References: newcred must be an exclusive credential reference for the 1935 * duration of the call. 1936 */ 1937void 1938change_rgid(struct ucred *newcred, gid_t rgid) 1939{ 1940 1941 newcred->cr_rgid = rgid; 1942} 1943 1944/*- 1945 * Change a process's saved uid. 1946 * Side effects: newcred->cr_svuid will be updated. 1947 * References: newcred must be an exclusive credential reference for the 1948 * duration of the call. 1949 */ 1950void 1951change_svuid(struct ucred *newcred, uid_t svuid) 1952{ 1953 1954 newcred->cr_svuid = svuid; 1955} 1956 1957/*- 1958 * Change a process's saved gid. 1959 * Side effects: newcred->cr_svgid will be updated. 1960 * References: newcred must be an exclusive credential reference for the 1961 * duration of the call. 1962 */ 1963void 1964change_svgid(struct ucred *newcred, gid_t svgid) 1965{ 1966 1967 newcred->cr_svgid = svgid; 1968} 1969