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("$FreeBSD$"); 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 67 static MALLOC_DEFINE(M_CRED, "cred", "credentials"); 68 69 SYSCTL_DECL(_security); 70 SYSCTL_NODE(_security, OID_AUTO, bsd, CTLFLAG_RW, 0, 71 "BSD security policy"); 72 73 #ifndef _SYS_SYSPROTO_H_ 74 struct getpid_args { 75 int dummy; 76 }; 77 #endif 78 /* 79 * MPSAFE 80 */ 81 /* ARGSUSED */ 82 int 83 getpid(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_ 97 struct getppid_args { 98 int dummy; 99 }; 100 #endif 101 /* 102 * MPSAFE 103 */ 104 /* ARGSUSED */ 105 int 106 getppid(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_ 120 struct getpgrp_args { 121 int dummy; 122 }; 123 #endif 124 /* 125 * MPSAFE 126 */ 127 int 128 getpgrp(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_ 140 struct getpgid_args { 141 pid_t pid; 142 }; 143 #endif 144 /* 145 * MPSAFE 146 */ 147 int 148 getpgid(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_ 175 struct getsid_args { 176 pid_t pid; 177 }; 178 #endif 179 /* 180 * MPSAFE 181 */ 182 int 183 getsid(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_ 207 struct getuid_args { 208 int dummy; 209 }; 210 #endif 211 /* 212 * MPSAFE 213 */ 214 /* ARGSUSED */ 215 int 216 getuid(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_ 227 struct geteuid_args { 228 int dummy; 229 }; 230 #endif 231 /* 232 * MPSAFE 233 */ 234 /* ARGSUSED */ 235 int 236 geteuid(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_ 244 struct getgid_args { 245 int dummy; 246 }; 247 #endif 248 /* 249 * MPSAFE 250 */ 251 /* ARGSUSED */ 252 int 253 getgid(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_ 269 struct getegid_args { 270 int dummy; 271 }; 272 #endif 273 /* 274 * MPSAFE 275 */ 276 /* ARGSUSED */ 277 int 278 getegid(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_ 286 struct getgroups_args { 287 u_int gidsetsize; 288 gid_t *gidset; 289 }; 290 #endif 291 /* 292 * MPSAFE 293 */ 294 int 295 getgroups(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_ 316 struct setsid_args { 317 int dummy; 318 }; 319 #endif 320 /* 321 * MPSAFE 322 */ 323 /* ARGSUSED */ 324 int 325 setsid(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_ 376 struct setpgid_args { 377 int pid; /* target process id */ 378 int pgid; /* target pgrp id */ 379 }; 380 #endif 381 /* 382 * MPSAFE 383 */ 384 /* ARGSUSED */ 385 int 386 setpgid(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 } 458 done: 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_ 480 struct setuid_args { 481 uid_t uid; 482 }; 483 #endif 484 /* 485 * MPSAFE 486 */ 487 /* ARGSUSED */ 488 int 489 setuid(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_ 585 struct seteuid_args { 586 uid_t euid; 587 }; 588 #endif 589 /* 590 * MPSAFE 591 */ 592 /* ARGSUSED */ 593 int 594 seteuid(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_ 632 struct setgid_args { 633 gid_t gid; 634 }; 635 #endif 636 /* 637 * MPSAFE 638 */ 639 /* ARGSUSED */ 640 int 641 setgid(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_ 724 struct setegid_args { 725 gid_t egid; 726 }; 727 #endif 728 /* 729 * MPSAFE 730 */ 731 /* ARGSUSED */ 732 int 733 setegid(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_ 763 struct setgroups_args { 764 u_int gidsetsize; 765 gid_t *gidset; 766 }; 767 #endif 768 /* 769 * MPSAFE 770 */ 771 /* ARGSUSED */ 772 int 773 setgroups(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_ 827 struct setreuid_args { 828 uid_t ruid; 829 uid_t euid; 830 }; 831 #endif 832 /* 833 * MPSAFE 834 */ 835 /* ARGSUSED */ 836 int 837 setreuid(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_ 886 struct setregid_args { 887 gid_t rgid; 888 gid_t egid; 889 }; 890 #endif 891 /* 892 * MPSAFE 893 */ 894 /* ARGSUSED */ 895 int 896 setregid(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_ 944 struct setresuid_args { 945 uid_t ruid; 946 uid_t euid; 947 uid_t suid; 948 }; 949 #endif 950 /* 951 * MPSAFE 952 */ 953 /* ARGSUSED */ 954 int 955 setresuid(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_ 1015 struct setresgid_args { 1016 gid_t rgid; 1017 gid_t egid; 1018 gid_t sgid; 1019 }; 1020 #endif 1021 /* 1022 * MPSAFE 1023 */ 1024 /* ARGSUSED */ 1025 int 1026 setresgid(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_ 1074 struct getresuid_args { 1075 uid_t *ruid; 1076 uid_t *euid; 1077 uid_t *suid; 1078 }; 1079 #endif 1080 /* 1081 * MPSAFE 1082 */ 1083 /* ARGSUSED */ 1084 int 1085 getresuid(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_ 1104 struct getresgid_args { 1105 gid_t *rgid; 1106 gid_t *egid; 1107 gid_t *sgid; 1108 }; 1109 #endif 1110 /* 1111 * MPSAFE 1112 */ 1113 /* ARGSUSED */ 1114 int 1115 getresgid(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_ 1134 struct issetugid_args { 1135 int dummy; 1136 }; 1137 #endif 1138 /* 1139 * MPSAFE 1140 */ 1141 /* ARGSUSED */ 1142 int 1143 issetugid(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 */ 1164 int 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 */ 1196 int 1197 groupmember(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 */ 1219 int suser_enabled = 1; 1220 SYSCTL_INT(_security_bsd, OID_AUTO, suser_enabled, CTLFLAG_RW, 1221 &suser_enabled, 0, "processes with uid 0 have privilege"); 1222 TUNABLE_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 */ 1228 int 1229 suser_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 */ 1245 int 1246 suser(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 */ 1271 int 1272 securelevel_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 1284 int 1285 securelevel_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 */ 1303 static int see_other_uids = 1; 1304 SYSCTL_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 */ 1316 static int 1317 cr_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 */ 1333 static int see_other_gids = 1; 1334 SYSCTL_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 */ 1346 static int 1347 cr_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 */ 1374 int 1375 cr_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 */ 1399 int 1400 p_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 */ 1419 static int conservative_signals = 1; 1420 SYSCTL_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 */ 1429 int 1430 cr_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 /* 1471 * Generally, permit job and terminal control 1472 * signals. 1473 */ 1474 break; 1475 default: 1476 /* Not permitted without privilege. */ 1477 error = suser_cred(cred, SUSER_ALLOWJAIL); 1478 if (error) 1479 return (error); 1480 } 1481 } 1482 1483 /* 1484 * Generally, the target credential's ruid or svuid must match the 1485 * subject credential's ruid or euid. 1486 */ 1487 if (cred->cr_ruid != proc->p_ucred->cr_ruid && 1488 cred->cr_ruid != proc->p_ucred->cr_svuid && 1489 cred->cr_uid != proc->p_ucred->cr_ruid && 1490 cred->cr_uid != proc->p_ucred->cr_svuid) { 1491 /* Not permitted without privilege. */ 1492 error = suser_cred(cred, SUSER_ALLOWJAIL); 1493 if (error) 1494 return (error); 1495 } 1496 1497 return (0); 1498 } 1499 1500 1501 /*- 1502 * Determine whether td may deliver the specified signal to p. 1503 * Returns: 0 for permitted, an errno value otherwise 1504 * Locks: Sufficient locks to protect various components of td and p 1505 * must be held. td must be curthread, and a lock must be 1506 * held for p. 1507 * References: td and p must be valid for the lifetime of the call 1508 */ 1509 int 1510 p_cansignal(struct thread *td, struct proc *p, int signum) 1511 { 1512 1513 KASSERT(td == curthread, ("%s: td not curthread", __func__)); 1514 PROC_LOCK_ASSERT(p, MA_OWNED); 1515 if (td->td_proc == p) 1516 return (0); 1517 1518 /* 1519 * UNIX signalling semantics require that processes in the same 1520 * session always be able to deliver SIGCONT to one another, 1521 * overriding the remaining protections. 1522 */ 1523 /* XXX: This will require an additional lock of some sort. */ 1524 if (signum == SIGCONT && td->td_proc->p_session == p->p_session) 1525 return (0); 1526 /* 1527 * Some compat layers use SIGTHR and higher signals for 1528 * communication between different kernel threads of the same 1529 * process, so that they expect that it's always possible to 1530 * deliver them, even for suid applications where cr_cansignal() can 1531 * deny such ability for security consideration. It should be 1532 * pretty safe to do since the only way to create two processes 1533 * with the same p_leader is via rfork(2). 1534 */ 1535 if (td->td_proc->p_leader != NULL && signum >= SIGTHR && 1536 signum < SIGTHR + 4 && td->td_proc->p_leader == p->p_leader) 1537 return (0); 1538 1539 return (cr_cansignal(td->td_ucred, p, signum)); 1540 } 1541 1542 /*- 1543 * Determine whether td may reschedule p. 1544 * Returns: 0 for permitted, an errno value otherwise 1545 * Locks: Sufficient locks to protect various components of td and p 1546 * must be held. td must be curthread, and a lock must 1547 * be held for p. 1548 * References: td and p must be valid for the lifetime of the call 1549 */ 1550 int 1551 p_cansched(struct thread *td, struct proc *p) 1552 { 1553 int error; 1554 1555 KASSERT(td == curthread, ("%s: td not curthread", __func__)); 1556 PROC_LOCK_ASSERT(p, MA_OWNED); 1557 if (td->td_proc == p) 1558 return (0); 1559 if ((error = prison_check(td->td_ucred, p->p_ucred))) 1560 return (error); 1561 #ifdef MAC 1562 if ((error = mac_check_proc_sched(td->td_ucred, p))) 1563 return (error); 1564 #endif 1565 if ((error = cr_seeotheruids(td->td_ucred, p->p_ucred))) 1566 return (error); 1567 if ((error = cr_seeothergids(td->td_ucred, p->p_ucred))) 1568 return (error); 1569 if (td->td_ucred->cr_ruid == p->p_ucred->cr_ruid) 1570 return (0); 1571 if (td->td_ucred->cr_uid == p->p_ucred->cr_ruid) 1572 return (0); 1573 if (suser_cred(td->td_ucred, SUSER_ALLOWJAIL) == 0) 1574 return (0); 1575 1576 #ifdef CAPABILITIES 1577 if (!cap_check(NULL, td, CAP_SYS_NICE, SUSER_ALLOWJAIL)) 1578 return (0); 1579 #endif 1580 1581 return (EPERM); 1582 } 1583 1584 /* 1585 * The 'unprivileged_proc_debug' flag may be used to disable a variety of 1586 * unprivileged inter-process debugging services, including some procfs 1587 * functionality, ptrace(), and ktrace(). In the past, inter-process 1588 * debugging has been involved in a variety of security problems, and sites 1589 * not requiring the service might choose to disable it when hardening 1590 * systems. 1591 * 1592 * XXX: Should modifying and reading this variable require locking? 1593 * XXX: data declarations should be together near the beginning of the file. 1594 */ 1595 static int unprivileged_proc_debug = 1; 1596 SYSCTL_INT(_security_bsd, OID_AUTO, unprivileged_proc_debug, CTLFLAG_RW, 1597 &unprivileged_proc_debug, 0, 1598 "Unprivileged processes may use process debugging facilities"); 1599 1600 /*- 1601 * Determine whether td may debug p. 1602 * Returns: 0 for permitted, an errno value otherwise 1603 * Locks: Sufficient locks to protect various components of td and p 1604 * must be held. td must be curthread, and a lock must 1605 * be held for p. 1606 * References: td and p must be valid for the lifetime of the call 1607 */ 1608 int 1609 p_candebug(struct thread *td, struct proc *p) 1610 { 1611 int credentialchanged, error, grpsubset, i, uidsubset; 1612 1613 KASSERT(td == curthread, ("%s: td not curthread", __func__)); 1614 PROC_LOCK_ASSERT(p, MA_OWNED); 1615 if (!unprivileged_proc_debug) { 1616 error = suser_cred(td->td_ucred, SUSER_ALLOWJAIL); 1617 if (error) 1618 return (error); 1619 } 1620 if (td->td_proc == p) 1621 return (0); 1622 if ((error = prison_check(td->td_ucred, p->p_ucred))) 1623 return (error); 1624 #ifdef MAC 1625 if ((error = mac_check_proc_debug(td->td_ucred, p))) 1626 return (error); 1627 #endif 1628 if ((error = cr_seeotheruids(td->td_ucred, p->p_ucred))) 1629 return (error); 1630 if ((error = cr_seeothergids(td->td_ucred, p->p_ucred))) 1631 return (error); 1632 1633 /* 1634 * Is p's group set a subset of td's effective group set? This 1635 * includes p's egid, group access list, rgid, and svgid. 1636 */ 1637 grpsubset = 1; 1638 for (i = 0; i < p->p_ucred->cr_ngroups; i++) { 1639 if (!groupmember(p->p_ucred->cr_groups[i], td->td_ucred)) { 1640 grpsubset = 0; 1641 break; 1642 } 1643 } 1644 grpsubset = grpsubset && 1645 groupmember(p->p_ucred->cr_rgid, td->td_ucred) && 1646 groupmember(p->p_ucred->cr_svgid, td->td_ucred); 1647 1648 /* 1649 * Are the uids present in p's credential equal to td's 1650 * effective uid? This includes p's euid, svuid, and ruid. 1651 */ 1652 uidsubset = (td->td_ucred->cr_uid == p->p_ucred->cr_uid && 1653 td->td_ucred->cr_uid == p->p_ucred->cr_svuid && 1654 td->td_ucred->cr_uid == p->p_ucred->cr_ruid); 1655 1656 /* 1657 * Has the credential of the process changed since the last exec()? 1658 */ 1659 credentialchanged = (p->p_flag & P_SUGID); 1660 1661 /* 1662 * If p's gids aren't a subset, or the uids aren't a subset, 1663 * or the credential has changed, require appropriate privilege 1664 * for td to debug p. For POSIX.1e capabilities, this will 1665 * require CAP_SYS_PTRACE. 1666 */ 1667 if (!grpsubset || !uidsubset || credentialchanged) { 1668 error = suser_cred(td->td_ucred, SUSER_ALLOWJAIL); 1669 if (error) 1670 return (error); 1671 } 1672 1673 /* Can't trace init when securelevel > 0. */ 1674 if (p == initproc) { 1675 error = securelevel_gt(td->td_ucred, 0); 1676 if (error) 1677 return (error); 1678 } 1679 1680 /* 1681 * Can't trace a process that's currently exec'ing. 1682 * XXX: Note, this is not a security policy decision, it's a 1683 * basic correctness/functionality decision. Therefore, this check 1684 * should be moved to the caller's of p_candebug(). 1685 */ 1686 if ((p->p_flag & P_INEXEC) != 0) 1687 return (EAGAIN); 1688 1689 return (0); 1690 } 1691 1692 /*- 1693 * Determine whether the subject represented by cred can "see" a socket. 1694 * Returns: 0 for permitted, ENOENT otherwise. 1695 */ 1696 int 1697 cr_canseesocket(struct ucred *cred, struct socket *so) 1698 { 1699 int error; 1700 1701 error = prison_check(cred, so->so_cred); 1702 if (error) 1703 return (ENOENT); 1704 #ifdef MAC 1705 SOCK_LOCK(so); 1706 error = mac_check_socket_visible(cred, so); 1707 SOCK_UNLOCK(so); 1708 if (error) 1709 return (error); 1710 #endif 1711 if (cr_seeotheruids(cred, so->so_cred)) 1712 return (ENOENT); 1713 if (cr_seeothergids(cred, so->so_cred)) 1714 return (ENOENT); 1715 1716 return (0); 1717 } 1718 1719 /* 1720 * Allocate a zeroed cred structure. 1721 * MPSAFE 1722 */ 1723 struct ucred * 1724 crget(void) 1725 { 1726 register struct ucred *cr; 1727 1728 MALLOC(cr, struct ucred *, sizeof(*cr), M_CRED, M_WAITOK | M_ZERO); 1729 cr->cr_ref = 1; 1730 cr->cr_mtxp = mtx_pool_find(mtxpool_sleep, cr); 1731 #ifdef MAC 1732 mac_init_cred(cr); 1733 #endif 1734 return (cr); 1735 } 1736 1737 /* 1738 * Claim another reference to a ucred structure. 1739 * MPSAFE 1740 */ 1741 struct ucred * 1742 crhold(struct ucred *cr) 1743 { 1744 1745 mtx_lock(cr->cr_mtxp); 1746 cr->cr_ref++; 1747 mtx_unlock(cr->cr_mtxp); 1748 return (cr); 1749 } 1750 1751 /* 1752 * Free a cred structure. 1753 * Throws away space when ref count gets to 0. 1754 * MPSAFE 1755 */ 1756 void 1757 crfree(struct ucred *cr) 1758 { 1759 struct mtx *mtxp = cr->cr_mtxp; 1760 1761 mtx_lock(mtxp); 1762 KASSERT(cr->cr_ref > 0, ("bad ucred refcount: %d", cr->cr_ref)); 1763 if (--cr->cr_ref == 0) { 1764 mtx_unlock(mtxp); 1765 /* 1766 * Some callers of crget(), such as nfs_statfs(), 1767 * allocate a temporary credential, but don't 1768 * allocate a uidinfo structure. 1769 */ 1770 if (cr->cr_uidinfo != NULL) 1771 uifree(cr->cr_uidinfo); 1772 if (cr->cr_ruidinfo != NULL) 1773 uifree(cr->cr_ruidinfo); 1774 /* 1775 * Free a prison, if any. 1776 */ 1777 if (jailed(cr)) 1778 prison_free(cr->cr_prison); 1779 #ifdef MAC 1780 mac_destroy_cred(cr); 1781 #endif 1782 FREE(cr, M_CRED); 1783 } else { 1784 mtx_unlock(mtxp); 1785 } 1786 } 1787 1788 /* 1789 * Check to see if this ucred is shared. 1790 * MPSAFE 1791 */ 1792 int 1793 crshared(struct ucred *cr) 1794 { 1795 int shared; 1796 1797 mtx_lock(cr->cr_mtxp); 1798 shared = (cr->cr_ref > 1); 1799 mtx_unlock(cr->cr_mtxp); 1800 return (shared); 1801 } 1802 1803 /* 1804 * Copy a ucred's contents from a template. Does not block. 1805 * MPSAFE 1806 */ 1807 void 1808 crcopy(struct ucred *dest, struct ucred *src) 1809 { 1810 1811 KASSERT(crshared(dest) == 0, ("crcopy of shared ucred")); 1812 bcopy(&src->cr_startcopy, &dest->cr_startcopy, 1813 (unsigned)((caddr_t)&src->cr_endcopy - 1814 (caddr_t)&src->cr_startcopy)); 1815 uihold(dest->cr_uidinfo); 1816 uihold(dest->cr_ruidinfo); 1817 if (jailed(dest)) 1818 prison_hold(dest->cr_prison); 1819 #ifdef MAC 1820 mac_copy_cred(src, dest); 1821 #endif 1822 } 1823 1824 /* 1825 * Dup cred struct to a new held one. 1826 * MPSAFE 1827 */ 1828 struct ucred * 1829 crdup(struct ucred *cr) 1830 { 1831 struct ucred *newcr; 1832 1833 newcr = crget(); 1834 crcopy(newcr, cr); 1835 return (newcr); 1836 } 1837 1838 /* 1839 * Fill in a struct xucred based on a struct ucred. 1840 * MPSAFE 1841 */ 1842 void 1843 cru2x(struct ucred *cr, struct xucred *xcr) 1844 { 1845 1846 bzero(xcr, sizeof(*xcr)); 1847 xcr->cr_version = XUCRED_VERSION; 1848 xcr->cr_uid = cr->cr_uid; 1849 xcr->cr_ngroups = cr->cr_ngroups; 1850 bcopy(cr->cr_groups, xcr->cr_groups, sizeof(cr->cr_groups)); 1851 } 1852 1853 /* 1854 * small routine to swap a thread's current ucred for the correct one 1855 * taken from the process. 1856 * MPSAFE 1857 */ 1858 void 1859 cred_update_thread(struct thread *td) 1860 { 1861 struct proc *p; 1862 struct ucred *cred; 1863 1864 p = td->td_proc; 1865 cred = td->td_ucred; 1866 PROC_LOCK(p); 1867 td->td_ucred = crhold(p->p_ucred); 1868 PROC_UNLOCK(p); 1869 if (cred != NULL) 1870 crfree(cred); 1871 } 1872 1873 /* 1874 * Get login name, if available. 1875 */ 1876 #ifndef _SYS_SYSPROTO_H_ 1877 struct getlogin_args { 1878 char *namebuf; 1879 u_int namelen; 1880 }; 1881 #endif 1882 /* 1883 * MPSAFE 1884 */ 1885 /* ARGSUSED */ 1886 int 1887 getlogin(struct thread *td, struct getlogin_args *uap) 1888 { 1889 int error; 1890 char login[MAXLOGNAME]; 1891 struct proc *p = td->td_proc; 1892 1893 if (uap->namelen > MAXLOGNAME) 1894 uap->namelen = MAXLOGNAME; 1895 PROC_LOCK(p); 1896 SESS_LOCK(p->p_session); 1897 bcopy(p->p_session->s_login, login, uap->namelen); 1898 SESS_UNLOCK(p->p_session); 1899 PROC_UNLOCK(p); 1900 error = copyout(login, uap->namebuf, uap->namelen); 1901 return(error); 1902 } 1903 1904 /* 1905 * Set login name. 1906 */ 1907 #ifndef _SYS_SYSPROTO_H_ 1908 struct setlogin_args { 1909 char *namebuf; 1910 }; 1911 #endif 1912 /* 1913 * MPSAFE 1914 */ 1915 /* ARGSUSED */ 1916 int 1917 setlogin(struct thread *td, struct setlogin_args *uap) 1918 { 1919 struct proc *p = td->td_proc; 1920 int error; 1921 char logintmp[MAXLOGNAME]; 1922 1923 error = suser_cred(td->td_ucred, SUSER_ALLOWJAIL); 1924 if (error) 1925 return (error); 1926 error = copyinstr(uap->namebuf, logintmp, sizeof(logintmp), NULL); 1927 if (error == ENAMETOOLONG) 1928 error = EINVAL; 1929 else if (!error) { 1930 PROC_LOCK(p); 1931 SESS_LOCK(p->p_session); 1932 (void) memcpy(p->p_session->s_login, logintmp, 1933 sizeof(logintmp)); 1934 SESS_UNLOCK(p->p_session); 1935 PROC_UNLOCK(p); 1936 } 1937 return (error); 1938 } 1939 1940 void 1941 setsugid(struct proc *p) 1942 { 1943 1944 PROC_LOCK_ASSERT(p, MA_OWNED); 1945 p->p_flag |= P_SUGID; 1946 if (!(p->p_pfsflags & PF_ISUGID)) 1947 p->p_stops = 0; 1948 } 1949 1950 /*- 1951 * Change a process's effective uid. 1952 * Side effects: newcred->cr_uid and newcred->cr_uidinfo will be modified. 1953 * References: newcred must be an exclusive credential reference for the 1954 * duration of the call. 1955 */ 1956 void 1957 change_euid(struct ucred *newcred, struct uidinfo *euip) 1958 { 1959 1960 newcred->cr_uid = euip->ui_uid; 1961 uihold(euip); 1962 uifree(newcred->cr_uidinfo); 1963 newcred->cr_uidinfo = euip; 1964 } 1965 1966 /*- 1967 * Change a process's effective gid. 1968 * Side effects: newcred->cr_gid will be modified. 1969 * References: newcred must be an exclusive credential reference for the 1970 * duration of the call. 1971 */ 1972 void 1973 change_egid(struct ucred *newcred, gid_t egid) 1974 { 1975 1976 newcred->cr_groups[0] = egid; 1977 } 1978 1979 /*- 1980 * Change a process's real uid. 1981 * Side effects: newcred->cr_ruid will be updated, newcred->cr_ruidinfo 1982 * will be updated, and the old and new cr_ruidinfo proc 1983 * counts will be updated. 1984 * References: newcred must be an exclusive credential reference for the 1985 * duration of the call. 1986 */ 1987 void 1988 change_ruid(struct ucred *newcred, struct uidinfo *ruip) 1989 { 1990 1991 (void)chgproccnt(newcred->cr_ruidinfo, -1, 0); 1992 newcred->cr_ruid = ruip->ui_uid; 1993 uihold(ruip); 1994 uifree(newcred->cr_ruidinfo); 1995 newcred->cr_ruidinfo = ruip; 1996 (void)chgproccnt(newcred->cr_ruidinfo, 1, 0); 1997 } 1998 1999 /*- 2000 * Change a process's real gid. 2001 * Side effects: newcred->cr_rgid will be updated. 2002 * References: newcred must be an exclusive credential reference for the 2003 * duration of the call. 2004 */ 2005 void 2006 change_rgid(struct ucred *newcred, gid_t rgid) 2007 { 2008 2009 newcred->cr_rgid = rgid; 2010 } 2011 2012 /*- 2013 * Change a process's saved uid. 2014 * Side effects: newcred->cr_svuid will be updated. 2015 * References: newcred must be an exclusive credential reference for the 2016 * duration of the call. 2017 */ 2018 void 2019 change_svuid(struct ucred *newcred, uid_t svuid) 2020 { 2021 2022 newcred->cr_svuid = svuid; 2023 } 2024 2025 /*- 2026 * Change a process's saved gid. 2027 * Side effects: newcred->cr_svgid will be updated. 2028 * References: newcred must be an exclusive credential reference for the 2029 * duration of the call. 2030 */ 2031 void 2032 change_svgid(struct ucred *newcred, gid_t svgid) 2033 { 2034 2035 newcred->cr_svgid = svgid; 2036 } 2037