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kern_prot.c revision 1.117 
      1 /*	$NetBSD: kern_prot.c,v 1.117 2013/11/25 16:28:20 rmind Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1982, 1986, 1989, 1990, 1991, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  * (c) UNIX System Laboratories, Inc.
      7  * All or some portions of this file are derived from material licensed
      8  * to the University of California by American Telephone and Telegraph
      9  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
     10  * the permission of UNIX System Laboratories, Inc.
     11  *
     12  * Redistribution and use in source and binary forms, with or without
     13  * modification, are permitted provided that the following conditions
     14  * are met:
     15  * 1. Redistributions of source code must retain the above copyright
     16  *    notice, this list of conditions and the following disclaimer.
     17  * 2. Redistributions in binary form must reproduce the above copyright
     18  *    notice, this list of conditions and the following disclaimer in the
     19  *    documentation and/or other materials provided with the distribution.
     20  * 3. Neither the name of the University nor the names of its contributors
     21  *    may be used to endorse or promote products derived from this software
     22  *    without specific prior written permission.
     23  *
     24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     34  * SUCH DAMAGE.
     35  *
     36  *	@(#)kern_prot.c	8.9 (Berkeley) 2/14/95
     37  */
     38 
     39 /*
     40  * System calls related to processes and protection
     41  */
     42 
     43 #include <sys/cdefs.h>
     44 __KERNEL_RCSID(0, "$NetBSD: kern_prot.c,v 1.117 2013/11/25 16:28:20 rmind Exp $");
     45 
     46 #include "opt_compat_43.h"
     47 
     48 #include <sys/param.h>
     49 #include <sys/acct.h>
     50 #include <sys/systm.h>
     51 #include <sys/ucred.h>
     52 #include <sys/proc.h>
     53 #include <sys/timeb.h>
     54 #include <sys/times.h>
     55 #include <sys/pool.h>
     56 #include <sys/prot.h>
     57 #include <sys/syslog.h>
     58 #include <sys/uidinfo.h>
     59 #include <sys/kauth.h>
     60 
     61 #include <sys/mount.h>
     62 #include <sys/syscallargs.h>
     63 
     64 int	sys_getpid(struct lwp *, const void *, register_t *);
     65 int	sys_getpid_with_ppid(struct lwp *, const void *, register_t *);
     66 int	sys_getuid(struct lwp *, const void *, register_t *);
     67 int	sys_getuid_with_euid(struct lwp *, const void *, register_t *);
     68 int	sys_getgid(struct lwp *, const void *, register_t *);
     69 int	sys_getgid_with_egid(struct lwp *, const void *, register_t *);
     70 
     71 /* ARGSUSED */
     72 int
     73 sys_getpid(struct lwp *l, const void *v, register_t *retval)
     74 {
     75 	struct proc *p = l->l_proc;
     76 
     77 	*retval = p->p_pid;
     78 	return (0);
     79 }
     80 
     81 /* ARGSUSED */
     82 int
     83 sys_getpid_with_ppid(struct lwp *l, const void *v, register_t *retval)
     84 {
     85 	struct proc *p = l->l_proc;
     86 
     87 	retval[0] = p->p_pid;
     88 	retval[1] = p->p_ppid;
     89 	return (0);
     90 }
     91 
     92 /* ARGSUSED */
     93 int
     94 sys_getppid(struct lwp *l, const void *v, register_t *retval)
     95 {
     96 	struct proc *p = l->l_proc;
     97 
     98 	*retval = p->p_ppid;
     99 	return (0);
    100 }
    101 
    102 /* Get process group ID; note that POSIX getpgrp takes no parameter */
    103 int
    104 sys_getpgrp(struct lwp *l, const void *v, register_t *retval)
    105 {
    106 	struct proc *p = l->l_proc;
    107 
    108 	mutex_enter(proc_lock);
    109 	*retval = p->p_pgrp->pg_id;
    110 	mutex_exit(proc_lock);
    111 	return (0);
    112 }
    113 
    114 /*
    115  * Return the process group ID of the session leader (session ID)
    116  * for the specified process.
    117  */
    118 int
    119 sys_getsid(struct lwp *l, const struct sys_getsid_args *uap, register_t *retval)
    120 {
    121 	/* {
    122 		syscalldarg(pid_t) pid;
    123 	} */
    124 	pid_t pid = SCARG(uap, pid);
    125 	struct proc *p;
    126 	int error = 0;
    127 
    128 	mutex_enter(proc_lock);
    129 	if (pid == 0)
    130 		*retval = l->l_proc->p_session->s_sid;
    131 	else if ((p = proc_find(pid)) != NULL)
    132 		*retval = p->p_session->s_sid;
    133 	else
    134 		error = ESRCH;
    135 	mutex_exit(proc_lock);
    136 
    137 	return error;
    138 }
    139 
    140 int
    141 sys_getpgid(struct lwp *l, const struct sys_getpgid_args *uap, register_t *retval)
    142 {
    143 	/* {
    144 		syscallarg(pid_t) pid;
    145 	} */
    146 	pid_t pid = SCARG(uap, pid);
    147 	struct proc *p;
    148 	int error = 0;
    149 
    150 	mutex_enter(proc_lock);
    151 	if (pid == 0)
    152 		*retval = l->l_proc->p_pgid;
    153 	else if ((p = proc_find(pid)) != NULL)
    154 		*retval = p->p_pgid;
    155 	else
    156 		error = ESRCH;
    157 	mutex_exit(proc_lock);
    158 
    159 	return error;
    160 }
    161 
    162 /* ARGSUSED */
    163 int
    164 sys_getuid(struct lwp *l, const void *v, register_t *retval)
    165 {
    166 
    167 	*retval = kauth_cred_getuid(l->l_cred);
    168 	return (0);
    169 }
    170 
    171 /* ARGSUSED */
    172 int
    173 sys_getuid_with_euid(struct lwp *l, const void *v, register_t *retval)
    174 {
    175 
    176 	retval[0] = kauth_cred_getuid(l->l_cred);
    177 	retval[1] = kauth_cred_geteuid(l->l_cred);
    178 	return (0);
    179 }
    180 
    181 /* ARGSUSED */
    182 int
    183 sys_geteuid(struct lwp *l, const void *v, register_t *retval)
    184 {
    185 
    186 	*retval = kauth_cred_geteuid(l->l_cred);
    187 	return (0);
    188 }
    189 
    190 /* ARGSUSED */
    191 int
    192 sys_getgid(struct lwp *l, const void *v, register_t *retval)
    193 {
    194 
    195 	*retval = kauth_cred_getgid(l->l_cred);
    196 	return (0);
    197 }
    198 
    199 /* ARGSUSED */
    200 int
    201 sys_getgid_with_egid(struct lwp *l, const void *v, register_t *retval)
    202 {
    203 
    204 	retval[0] = kauth_cred_getgid(l->l_cred);
    205 	retval[1] = kauth_cred_getegid(l->l_cred);
    206 	return (0);
    207 }
    208 
    209 /*
    210  * Get effective group ID.  The "egid" is groups[0], and could be obtained
    211  * via getgroups.  This syscall exists because it is somewhat painful to do
    212  * correctly in a library function.
    213  */
    214 /* ARGSUSED */
    215 int
    216 sys_getegid(struct lwp *l, const void *v, register_t *retval)
    217 {
    218 
    219 	*retval = kauth_cred_getegid(l->l_cred);
    220 	return (0);
    221 }
    222 
    223 int
    224 sys_getgroups(struct lwp *l, const struct sys_getgroups_args *uap, register_t *retval)
    225 {
    226 	/* {
    227 		syscallarg(int) gidsetsize;
    228 		syscallarg(gid_t *) gidset;
    229 	} */
    230 
    231 	*retval = kauth_cred_ngroups(l->l_cred);
    232 	if (SCARG(uap, gidsetsize) == 0)
    233 		return 0;
    234 	if (SCARG(uap, gidsetsize) < (int)*retval)
    235 		return EINVAL;
    236 
    237 	return kauth_cred_getgroups(l->l_cred, SCARG(uap, gidset), *retval,
    238 	    UIO_USERSPACE);
    239 }
    240 
    241 int
    242 sys_setsid(struct lwp *l, const void *v, register_t *retval)
    243 {
    244 	struct proc *p = l->l_proc;
    245 	int error;
    246 
    247 	error = proc_enterpgrp(p, p->p_pid, p->p_pid, true);
    248 	*retval = p->p_pid;
    249 	return (error);
    250 }
    251 
    252 
    253 /*
    254  * set process group (setpgid/old setpgrp)
    255  *
    256  * caller does setpgid(targpid, targpgid)
    257  *
    258  * pgid must be in valid range (EINVAL)
    259  * pid must be caller or child of caller (ESRCH)
    260  * if a child
    261  *	pid must be in same session (EPERM)
    262  *	pid can't have done an exec (EACCES)
    263  * if pgid != pid
    264  * 	there must exist some pid in same session having pgid (EPERM)
    265  * pid must not be session leader (EPERM)
    266  *
    267  * Permission checks now in proc_enterpgrp()
    268  */
    269 int
    270 sys_setpgid(struct lwp *l, const struct sys_setpgid_args *uap,
    271     register_t *retval)
    272 {
    273 	/* {
    274 		syscallarg(int) pid;
    275 		syscallarg(int) pgid;
    276 	} */
    277 	struct proc *p = l->l_proc;
    278 	pid_t targp, pgid;
    279 
    280 	if (SCARG(uap, pgid) < 0)
    281 		return EINVAL;
    282 	if ((targp = SCARG(uap, pid)) == 0)
    283 		targp = p->p_pid;
    284 	if ((pgid = SCARG(uap, pgid)) == 0)
    285 		pgid = targp;
    286 
    287 	return proc_enterpgrp(p, targp, pgid, false);
    288 }
    289 
    290 /*
    291  * Set real, effective and saved uids to the requested values.
    292  * non-root callers can only ever change uids to values that match
    293  * one of the processes current uid values.
    294  * This is further restricted by the flags argument.
    295  */
    296 
    297 int
    298 do_setresuid(struct lwp *l, uid_t r, uid_t e, uid_t sv, u_int flags)
    299 {
    300 	struct proc *p = l->l_proc;
    301 	kauth_cred_t cred, ncred;
    302 
    303 	ncred = kauth_cred_alloc();
    304 
    305 	/* Get a write lock on the process credential. */
    306 	proc_crmod_enter();
    307 	cred = p->p_cred;
    308 
    309 	/*
    310 	 * Check that the new value is one of the allowed existing values,
    311 	 * or that we have root privilege.
    312 	 */
    313 	if ((r != -1
    314 	    && !((flags & ID_R_EQ_R) && r == kauth_cred_getuid(cred))
    315 	    && !((flags & ID_R_EQ_E) && r == kauth_cred_geteuid(cred))
    316 	    && !((flags & ID_R_EQ_S) && r == kauth_cred_getsvuid(cred))) ||
    317 	    (e != -1
    318 	    && !((flags & ID_E_EQ_R) && e == kauth_cred_getuid(cred))
    319 	    && !((flags & ID_E_EQ_E) && e == kauth_cred_geteuid(cred))
    320 	    && !((flags & ID_E_EQ_S) && e == kauth_cred_getsvuid(cred))) ||
    321 	    (sv != -1
    322 	    && !((flags & ID_S_EQ_R) && sv == kauth_cred_getuid(cred))
    323 	    && !((flags & ID_S_EQ_E) && sv == kauth_cred_geteuid(cred))
    324 	    && !((flags & ID_S_EQ_S) && sv == kauth_cred_getsvuid(cred)))) {
    325 		int error;
    326 
    327 		error = kauth_authorize_process(cred, KAUTH_PROCESS_SETID,
    328 		    p, NULL, NULL, NULL);
    329 		if (error != 0) {
    330 		 	proc_crmod_leave(cred, ncred, false);
    331 			return error;
    332 		}
    333 	}
    334 
    335 	/* If nothing has changed, short circuit the request */
    336 	if ((r == -1 || r == kauth_cred_getuid(cred))
    337 	    && (e == -1 || e == kauth_cred_geteuid(cred))
    338 	    && (sv == -1 || sv == kauth_cred_getsvuid(cred))) {
    339 		proc_crmod_leave(cred, ncred, false);
    340 		return 0;
    341 	}
    342 
    343 	kauth_cred_clone(cred, ncred);
    344 
    345 	if (r != -1 && r != kauth_cred_getuid(ncred)) {
    346 		u_long nlwps;
    347 
    348 		/* Update count of processes for this user. */
    349 		(void)chgproccnt(kauth_cred_getuid(ncred), -1);
    350 		(void)chgproccnt(r, 1);
    351 
    352 		/* The first LWP of a process is excluded. */
    353 		KASSERT(mutex_owned(p->p_lock));
    354 		nlwps = p->p_nlwps - 1;
    355 		(void)chglwpcnt(kauth_cred_getuid(ncred), -nlwps);
    356 		(void)chglwpcnt(r, nlwps);
    357 
    358 		kauth_cred_setuid(ncred, r);
    359 	}
    360 	if (sv != -1)
    361 		kauth_cred_setsvuid(ncred, sv);
    362 	if (e != -1)
    363 		kauth_cred_seteuid(ncred, e);
    364 
    365 	/* Broadcast our credentials to the process and other LWPs. */
    366  	proc_crmod_leave(ncred, cred, true);
    367 
    368 	return 0;
    369 }
    370 
    371 /*
    372  * Set real, effective and saved gids to the requested values.
    373  * non-root callers can only ever change gids to values that match
    374  * one of the processes current gid values.
    375  * This is further restricted by the flags argument.
    376  */
    377 
    378 int
    379 do_setresgid(struct lwp *l, gid_t r, gid_t e, gid_t sv, u_int flags)
    380 {
    381 	struct proc *p = l->l_proc;
    382 	kauth_cred_t cred, ncred;
    383 
    384 	ncred = kauth_cred_alloc();
    385 
    386 	/* Get a write lock on the process credential. */
    387 	proc_crmod_enter();
    388 	cred = p->p_cred;
    389 
    390 	/*
    391 	 * check new value is one of the allowed existing values.
    392 	 * otherwise, check if we have root privilege.
    393 	 */
    394 	if ((r != -1
    395 	    && !((flags & ID_R_EQ_R) && r == kauth_cred_getgid(cred))
    396 	    && !((flags & ID_R_EQ_E) && r == kauth_cred_getegid(cred))
    397 	    && !((flags & ID_R_EQ_S) && r == kauth_cred_getsvgid(cred))) ||
    398 	    (e != -1
    399 	    && !((flags & ID_E_EQ_R) && e == kauth_cred_getgid(cred))
    400 	    && !((flags & ID_E_EQ_E) && e == kauth_cred_getegid(cred))
    401 	    && !((flags & ID_E_EQ_S) && e == kauth_cred_getsvgid(cred))) ||
    402 	    (sv != -1
    403 	    && !((flags & ID_S_EQ_R) && sv == kauth_cred_getgid(cred))
    404 	    && !((flags & ID_S_EQ_E) && sv == kauth_cred_getegid(cred))
    405 	    && !((flags & ID_S_EQ_S) && sv == kauth_cred_getsvgid(cred)))) {
    406 		int error;
    407 
    408 		error = kauth_authorize_process(cred, KAUTH_PROCESS_SETID,
    409 		    p, NULL, NULL, NULL);
    410 		if (error != 0) {
    411 		 	proc_crmod_leave(cred, ncred, false);
    412 			return error;
    413 		}
    414 	}
    415 
    416 	/* If nothing has changed, short circuit the request */
    417 	if ((r == -1 || r == kauth_cred_getgid(cred))
    418 	    && (e == -1 || e == kauth_cred_getegid(cred))
    419 	    && (sv == -1 || sv == kauth_cred_getsvgid(cred))) {
    420 	 	proc_crmod_leave(cred, ncred, false);
    421 		return 0;
    422 	}
    423 
    424 	kauth_cred_clone(cred, ncred);
    425 
    426 	if (r != -1)
    427 		kauth_cred_setgid(ncred, r);
    428 	if (sv != -1)
    429 		kauth_cred_setsvgid(ncred, sv);
    430 	if (e != -1)
    431 		kauth_cred_setegid(ncred, e);
    432 
    433 	/* Broadcast our credentials to the process and other LWPs. */
    434  	proc_crmod_leave(ncred, cred, true);
    435 
    436 	return 0;
    437 }
    438 
    439 /* ARGSUSED */
    440 int
    441 sys_setuid(struct lwp *l, const struct sys_setuid_args *uap, register_t *retval)
    442 {
    443 	/* {
    444 		syscallarg(uid_t) uid;
    445 	} */
    446 	uid_t uid = SCARG(uap, uid);
    447 
    448 	return do_setresuid(l, uid, uid, uid,
    449 			    ID_R_EQ_R | ID_E_EQ_R | ID_S_EQ_R);
    450 }
    451 
    452 /* ARGSUSED */
    453 int
    454 sys_seteuid(struct lwp *l, const struct sys_seteuid_args *uap, register_t *retval)
    455 {
    456 	/* {
    457 		syscallarg(uid_t) euid;
    458 	} */
    459 
    460 	return do_setresuid(l, -1, SCARG(uap, euid), -1, ID_E_EQ_R | ID_E_EQ_S);
    461 }
    462 
    463 int
    464 sys_setreuid(struct lwp *l, const struct sys_setreuid_args *uap, register_t *retval)
    465 {
    466 	/* {
    467 		syscallarg(uid_t) ruid;
    468 		syscallarg(uid_t) euid;
    469 	} */
    470 	kauth_cred_t cred = l->l_cred;
    471 	uid_t ruid, euid, svuid;
    472 
    473 	ruid = SCARG(uap, ruid);
    474 	euid = SCARG(uap, euid);
    475 
    476 	if (ruid == -1)
    477 		ruid = kauth_cred_getuid(cred);
    478 	if (euid == -1)
    479 		euid = kauth_cred_geteuid(cred);
    480 
    481 	/* Saved uid is set to the new euid if the ruid changed */
    482 	svuid = (ruid == kauth_cred_getuid(cred)) ? -1 : euid;
    483 
    484 	return do_setresuid(l, ruid, euid, svuid,
    485 			    ID_R_EQ_R | ID_R_EQ_E |
    486 			    ID_E_EQ_R | ID_E_EQ_E | ID_E_EQ_S |
    487 			    ID_S_EQ_R | ID_S_EQ_E | ID_S_EQ_S);
    488 }
    489 
    490 /* ARGSUSED */
    491 int
    492 sys_setgid(struct lwp *l, const struct sys_setgid_args *uap, register_t *retval)
    493 {
    494 	/* {
    495 		syscallarg(gid_t) gid;
    496 	} */
    497 	gid_t gid = SCARG(uap, gid);
    498 
    499 	return do_setresgid(l, gid, gid, gid,
    500 			    ID_R_EQ_R | ID_E_EQ_R | ID_S_EQ_R);
    501 }
    502 
    503 /* ARGSUSED */
    504 int
    505 sys_setegid(struct lwp *l, const struct sys_setegid_args *uap, register_t *retval)
    506 {
    507 	/* {
    508 		syscallarg(gid_t) egid;
    509 	} */
    510 
    511 	return do_setresgid(l, -1, SCARG(uap, egid), -1, ID_E_EQ_R | ID_E_EQ_S);
    512 }
    513 
    514 int
    515 sys_setregid(struct lwp *l, const struct sys_setregid_args *uap, register_t *retval)
    516 {
    517 	/* {
    518 		syscallarg(gid_t) rgid;
    519 		syscallarg(gid_t) egid;
    520 	} */
    521 	kauth_cred_t cred = l->l_cred;
    522 	gid_t rgid, egid, svgid;
    523 
    524 	rgid = SCARG(uap, rgid);
    525 	egid = SCARG(uap, egid);
    526 
    527 	if (rgid == -1)
    528 		rgid = kauth_cred_getgid(cred);
    529 	if (egid == -1)
    530 		egid = kauth_cred_getegid(cred);
    531 
    532 	/* Saved gid is set to the new egid if the rgid changed */
    533 	svgid = rgid == kauth_cred_getgid(cred) ? -1 : egid;
    534 
    535 	return do_setresgid(l, rgid, egid, svgid,
    536 			ID_R_EQ_R | ID_R_EQ_E |
    537 			ID_E_EQ_R | ID_E_EQ_E | ID_E_EQ_S |
    538 			ID_S_EQ_R | ID_S_EQ_E | ID_S_EQ_S);
    539 }
    540 
    541 int
    542 sys_issetugid(struct lwp *l, const void *v, register_t *retval)
    543 {
    544 	struct proc *p = l->l_proc;
    545 
    546 	/*
    547 	 * Note: OpenBSD sets a P_SUGIDEXEC flag set at execve() time,
    548 	 * we use PK_SUGID because we consider changing the owners as
    549 	 * "tainting" as well.
    550 	 * This is significant for procs that start as root and "become"
    551 	 * a user without an exec - programs cannot know *everything*
    552 	 * that libc *might* have put in their data segment.
    553 	 */
    554 	*retval = (p->p_flag & PK_SUGID) != 0;
    555 	return (0);
    556 }
    557 
    558 /* ARGSUSED */
    559 int
    560 sys_setgroups(struct lwp *l, const struct sys_setgroups_args *uap, register_t *retval)
    561 {
    562 	/* {
    563 		syscallarg(int) gidsetsize;
    564 		syscallarg(const gid_t *) gidset;
    565 	} */
    566 	kauth_cred_t ncred;
    567 	int error;
    568 
    569 	ncred = kauth_cred_alloc();
    570 	error = kauth_cred_setgroups(ncred, SCARG(uap, gidset),
    571 	    SCARG(uap, gidsetsize), -1, UIO_USERSPACE);
    572 	if (error != 0) {
    573 		kauth_cred_free(ncred);
    574 		return error;
    575 	}
    576 
    577 	return kauth_proc_setgroups(l, ncred);
    578 }
    579 
    580 /*
    581  * Get login name, if available.
    582  */
    583 /* ARGSUSED */
    584 int
    585 sys___getlogin(struct lwp *l, const struct sys___getlogin_args *uap, register_t *retval)
    586 {
    587 	/* {
    588 		syscallarg(char *) namebuf;
    589 		syscallarg(size_t) namelen;
    590 	} */
    591 	struct proc *p = l->l_proc;
    592 	char login[sizeof(p->p_session->s_login)];
    593 	int namelen = SCARG(uap, namelen);
    594 
    595 	if (namelen > sizeof(login))
    596 		namelen = sizeof(login);
    597 	mutex_enter(proc_lock);
    598 	memcpy(login, p->p_session->s_login, namelen);
    599 	mutex_exit(proc_lock);
    600 	return (copyout(login, (void *)SCARG(uap, namebuf), namelen));
    601 }
    602 
    603 /*
    604  * Set login name.
    605  */
    606 /* ARGSUSED */
    607 int
    608 sys___setlogin(struct lwp *l, const struct sys___setlogin_args *uap, register_t *retval)
    609 {
    610 	/* {
    611 		syscallarg(const char *) namebuf;
    612 	} */
    613 	struct proc *p = l->l_proc;
    614 	struct session *sp;
    615 	char newname[sizeof sp->s_login + 1];
    616 	int error;
    617 
    618 	if ((error = kauth_authorize_process(l->l_cred, KAUTH_PROCESS_SETID,
    619 	    p, NULL, NULL, NULL)) != 0)
    620 		return (error);
    621 	error = copyinstr(SCARG(uap, namebuf), newname, sizeof newname, NULL);
    622 	if (error != 0)
    623 		return (error == ENAMETOOLONG ? EINVAL : error);
    624 
    625 	mutex_enter(proc_lock);
    626 	sp = p->p_session;
    627 	if (sp->s_flags & S_LOGIN_SET && p->p_pid != sp->s_sid &&
    628 	    strncmp(newname, sp->s_login, sizeof sp->s_login) != 0)
    629 		log(LOG_WARNING, "%s (pid %d) changing logname from "
    630 		    "%.*s to %s\n", p->p_comm, p->p_pid,
    631 		    (int)sizeof sp->s_login, sp->s_login, newname);
    632 	sp->s_flags |= S_LOGIN_SET;
    633 	strncpy(sp->s_login, newname, sizeof sp->s_login);
    634 	mutex_exit(proc_lock);
    635 	return (0);
    636 }
    637