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      1 /*
      2  * CDDL HEADER START
      3  *
      4  * The contents of this file are subject to the terms of the
      5  * Common Development and Distribution License (the "License").
      6  * You may not use this file except in compliance with the License.
      7  *
      8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
      9  * or http://www.opensolaris.org/os/licensing.
     10  * See the License for the specific language governing permissions
     11  * and limitations under the License.
     12  *
     13  * When distributing Covered Code, include this CDDL HEADER in each
     14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
     15  * If applicable, add the following below this CDDL HEADER, with the
     16  * fields enclosed by brackets "[]" replaced with your own identifying
     17  * information: Portions Copyright [yyyy] [name of copyright owner]
     18  *
     19  * CDDL HEADER END
     20  */
     21 /*
     22  * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
     23  * Use is subject to license terms.
     24  */
     25 
     26 /*	Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T	*/
     27 /*	  All Rights Reserved  	*/
     28 
     29 /*
     30  * Portions of this source code were derived from Berkeley 4.3 BSD
     31  * under license from the Regents of the University of California.
     32  */
     33 
     34 #pragma ident	"@(#)access.c	1.12	07/12/26 SMI"
     35 
     36 #include <sys/param.h>
     37 #include <sys/isa_defs.h>
     38 #include <sys/types.h>
     39 #include <sys/sysmacros.h>
     40 #include <sys/cred_impl.h>
     41 #include <sys/systm.h>
     42 #include <sys/errno.h>
     43 #include <sys/pathname.h>
     44 #include <sys/vnode.h>
     45 #include <sys/uio.h>
     46 #include <sys/cmn_err.h>
     47 #include <sys/debug.h>
     48 #include <sys/file.h>
     49 #include <fs/fs_subr.h>
     50 #include <c2/audit.h>
     51 
     52 /*
     53  * Determine accessibility of file.
     54  */
     55 
     56 #define	E_OK	010	/* use effective ids */
     57 #define	R_OK	004
     58 #define	W_OK	002
     59 #define	X_OK	001
     60 
     61 static int
     62 caccess(char *fname, int fmode, vnode_t *startvp)
     63 {
     64 	vnode_t *vp;
     65 	cred_t *tmpcr;
     66 	int error;
     67 	int mode;
     68 	int eok;
     69 	cred_t *cr;
     70 	int estale_retry = 0;
     71 
     72 	if (fmode & ~(E_OK|R_OK|W_OK|X_OK))
     73 		return (set_errno(EINVAL));
     74 
     75 	mode = ((fmode & (R_OK|W_OK|X_OK)) << 6);
     76 
     77 	cr = CRED();
     78 
     79 	/* OK to use effective uid/gid, i.e., no need to crdup(CRED())? */
     80 	eok = (fmode & E_OK) ||
     81 	    (cr->cr_uid == cr->cr_ruid && cr->cr_gid == cr->cr_rgid);
     82 
     83 	if (eok)
     84 		tmpcr = cr;
     85 	else {
     86 		tmpcr = crdup(cr);
     87 		tmpcr->cr_uid = cr->cr_ruid;
     88 		tmpcr->cr_gid = cr->cr_rgid;
     89 		tmpcr->cr_ruid = cr->cr_uid;
     90 		tmpcr->cr_rgid = cr->cr_gid;
     91 	}
     92 
     93 lookup:
     94 	if (error = lookupnameat(fname, UIO_USERSPACE, FOLLOW, NULLVPP, &vp,
     95 	    startvp)) {
     96 		if ((error == ESTALE) && fs_need_estale_retry(estale_retry++))
     97 			goto lookup;
     98 		if (!eok)
     99 			crfree(tmpcr);
    100 		return (set_errno(error));
    101 	}
    102 
    103 	if (mode) {
    104 		error = VOP_ACCESS(vp, mode, 0, tmpcr, NULL);
    105 		if (error) {
    106 			if ((error == ESTALE) &&
    107 			    fs_need_estale_retry(estale_retry++)) {
    108 				VN_RELE(vp);
    109 				goto lookup;
    110 			}
    111 			(void) set_errno(error);
    112 		}
    113 	}
    114 
    115 	if (!eok)
    116 		crfree(tmpcr);
    117 	VN_RELE(vp);
    118 	return (error);
    119 }
    120 
    121 int
    122 access(char *fname, int fmode)
    123 {
    124 	return (caccess(fname, fmode, NULL));
    125 }
    126 
    127 int
    128 accessat(int fd, char *fname, int fmode)
    129 {
    130 	file_t *dirfp;
    131 	vnode_t *dirvp;
    132 	int error;
    133 	char startchar;
    134 
    135 	if (fd == AT_FDCWD && fname == NULL)
    136 		return (set_errno(EFAULT));
    137 
    138 	if (fname != NULL) {
    139 		if (copyin(fname, &startchar, sizeof (char)))
    140 			return (set_errno(EFAULT));
    141 	} else
    142 		startchar = '\0';
    143 
    144 	if (fd == AT_FDCWD) {
    145 		dirvp = NULL;
    146 	} else {
    147 		if (startchar != '/') {
    148 			if ((dirfp = getf(fd)) == NULL) {
    149 				return (set_errno(EBADF));
    150 			}
    151 			dirvp = dirfp->f_vnode;
    152 			VN_HOLD(dirvp);
    153 			releasef(fd);
    154 		} else {
    155 			dirvp = NULL;
    156 		}
    157 	}
    158 
    159 	if (audit_active)
    160 		audit_setfsat_path(1);
    161 
    162 	error = caccess(fname, fmode, dirvp);
    163 	if (dirvp != NULL)
    164 		VN_RELE(dirvp);
    165 
    166 	return (error);
    167 }
    168