1 /* $NetBSD: authunix_prot.c,v 1.12 2000/01/22 22:19:17 mycroft Exp $ */ 2 3 /*- 4 * SPDX-License-Identifier: BSD-3-Clause 5 * 6 * Copyright (c) 2009, Sun Microsystems, Inc. 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions are met: 11 * - Redistributions of source code must retain the above copyright notice, 12 * this list of conditions and the following disclaimer. 13 * - Redistributions in binary form must reproduce the above copyright notice, 14 * this list of conditions and the following disclaimer in the documentation 15 * and/or other materials provided with the distribution. 16 * - Neither the name of Sun Microsystems, Inc. nor the names of its 17 * contributors may be used to endorse or promote products derived 18 * from this software without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 21 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE 24 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 30 * POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 /* 34 * authunix_prot.c 35 * XDR for UNIX style authentication parameters for RPC 36 * 37 * Copyright (C) 1984, Sun Microsystems, Inc. 38 */ 39 40 #include <sys/param.h> 41 #include <sys/jail.h> 42 #include <sys/libkern.h> 43 #include <sys/ucred.h> 44 45 #include <rpc/types.h> 46 #include <rpc/xdr.h> 47 #include <rpc/auth.h> 48 49 #include <rpc/rpc_com.h> 50 51 /* 52 * XDR for unix authentication parameters. 53 */ 54 bool_t 55 xdr_authunix_parms(XDR *xdrs, uint32_t *time, struct xucred *cred) 56 { 57 uint32_t namelen; 58 uint32_t supp_ngroups, i; 59 uint32_t junk; 60 char hostbuf[MAXHOSTNAMELEN]; 61 62 if (xdrs->x_op == XDR_FREE) 63 /* This function does not allocate auxiliary memory. */ 64 return (TRUE); 65 66 if (xdrs->x_op == XDR_ENCODE) { 67 getcredhostname(NULL, hostbuf, sizeof(hostbuf)); 68 namelen = strlen(hostbuf); 69 if (namelen > AUTH_SYS_MAX_HOSTNAME) 70 namelen = AUTH_SYS_MAX_HOSTNAME; 71 } else 72 namelen = 0; 73 74 if (!xdr_uint32_t(xdrs, time) || !xdr_uint32_t(xdrs, &namelen)) 75 return (FALSE); 76 77 /* 78 * Ignore the hostname on decode. 79 */ 80 if (xdrs->x_op == XDR_ENCODE) { 81 if (!xdr_opaque(xdrs, hostbuf, namelen)) 82 return (FALSE); 83 } else { 84 if (namelen > AUTH_SYS_MAX_HOSTNAME) 85 return (FALSE); 86 xdr_setpos(xdrs, xdr_getpos(xdrs) + RNDUP(namelen)); 87 } 88 89 if (!xdr_uint32_t(xdrs, &cred->cr_uid)) 90 return (FALSE); 91 92 /* 93 * Safety check: The protocol needs at least one group (access to 94 * 'cr_gid', decrementation of 'cr_ngroups' below). 95 */ 96 if (xdrs->x_op == XDR_ENCODE && cred->cr_ngroups == 0) 97 return (FALSE); 98 if (!xdr_uint32_t(xdrs, &cred->cr_gid)) 99 return (FALSE); 100 101 if (xdrs->x_op == XDR_ENCODE) { 102 /* 103 * Note that this is a 'struct xucred', which still has the 104 * historical layout where the effective GID is in cr_groups[0] 105 * and is accounted in 'cr_ngroups'. We substract 1 to obtain 106 * the number of "supplementary" groups, passed in the AUTH_SYS 107 * credentials variable-length array called gids[] in RFC 5531. 108 */ 109 MPASS(cred->cr_ngroups <= XU_NGROUPS); 110 supp_ngroups = cred->cr_ngroups - 1; 111 if (supp_ngroups > AUTH_SYS_MAX_GROUPS) 112 /* With current values, this should never execute. */ 113 supp_ngroups = AUTH_SYS_MAX_GROUPS; 114 } 115 116 if (!xdr_uint32_t(xdrs, &supp_ngroups)) 117 return (FALSE); 118 119 /* 120 * Because we cannot store more than XU_NGROUPS in total (16 at time of 121 * this writing), for now we choose to be strict with respect to RFC 122 * 5531's maximum number of supplementary groups (AUTH_SYS_MAX_GROUPS). 123 * That would also be an accidental DoS prevention measure if the 124 * request handling code didn't try to reassemble it in full without any 125 * size limits. Although AUTH_SYS_MAX_GROUPS and XU_NGROUPS are equal, 126 * since the latter includes the "effective" GID, we cannot store the 127 * last group of a message with exactly AUTH_SYS_MAX_GROUPS 128 * supplementary groups. We accept such messages so as not to violate 129 * the protocol, silently dropping the last group on the floor. 130 */ 131 132 if (xdrs->x_op != XDR_ENCODE && supp_ngroups > AUTH_SYS_MAX_GROUPS) 133 return (FALSE); 134 135 junk = 0; 136 for (i = 0; i < supp_ngroups; ++i) 137 if (!xdr_uint32_t(xdrs, i < XU_NGROUPS - 1 ? 138 &cred->cr_sgroups[i] : &junk)) 139 return (FALSE); 140 141 if (xdrs->x_op != XDR_ENCODE) 142 cred->cr_ngroups = MIN(supp_ngroups + 1, XU_NGROUPS); 143 144 return (TRUE); 145 } 146