1 /* $NetBSD: openpam_subst.c,v 1.3 2017/05/06 19:50:09 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 2011 Dag-Erling Smørgrav 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. The name of the author may not be used to endorse or promote 16 * products derived from this software without specific prior written 17 * permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 * 31 * $OpenPAM: openpam_subst.c 938 2017-04-30 21:34:42Z des $ 32 */ 33 34 #ifdef HAVE_CONFIG_H 35 # include "config.h" 36 #endif 37 38 #include <sys/cdefs.h> 39 __RCSID("$NetBSD: openpam_subst.c,v 1.3 2017/05/06 19:50:09 christos Exp $"); 40 41 #include <security/pam_appl.h> 42 43 #include "openpam_impl.h" 44 45 #define subst_char(ch) do { \ 46 char ch_ = (ch); \ 47 if (buf && len < *bufsize) \ 48 *buf++ = ch_; \ 49 ++len; \ 50 } while (/*CONSTCOND*/0) 51 52 #define subst_string(s) do { \ 53 const char *s_ = (s); \ 54 while (*s_) \ 55 subst_char(*s_++); \ 56 } while (/*CONSTCOND*/0) 57 58 #define subst_item(i) do { \ 59 int i_ = (i); \ 60 const void *p_; \ 61 ret = pam_get_item(pamh, i_, &p_); \ 62 if (ret == PAM_SUCCESS && p_ != NULL) \ 63 subst_string(p_); \ 64 } while (/*CONSTCOND*/0) 65 66 /* 67 * OpenPAM internal 68 * 69 * Substitute PAM item values in a string 70 */ 71 72 int 73 openpam_subst(const pam_handle_t *pamh, 74 char *buf, size_t *bufsize, const char *template) 75 { 76 size_t len; 77 int ret; 78 79 ENTERS(template); 80 if (template == NULL) 81 template = "(null)"; 82 83 len = 1; /* initialize to 1 for terminating NUL */ 84 ret = PAM_SUCCESS; 85 while (*template && ret == PAM_SUCCESS) { 86 if (template[0] == '%') { 87 ++template; 88 switch (*template) { 89 case 's': 90 subst_item(PAM_SERVICE); 91 break; 92 case 't': 93 subst_item(PAM_TTY); 94 break; 95 case 'h': 96 subst_item(PAM_HOST); 97 break; 98 case 'u': 99 subst_item(PAM_USER); 100 break; 101 case 'H': 102 subst_item(PAM_RHOST); 103 break; 104 case 'U': 105 subst_item(PAM_RUSER); 106 break; 107 case '\0': 108 subst_char('%'); 109 break; 110 default: 111 subst_char('%'); 112 subst_char(*template); 113 } 114 ++template; 115 } else { 116 subst_char(*template++); 117 } 118 } 119 if (buf) 120 *buf = '\0'; 121 if (ret == PAM_SUCCESS) { 122 if (len > *bufsize) 123 ret = PAM_TRY_AGAIN; 124 *bufsize = len; 125 } 126 RETURNC(ret); 127 } 128 129 /* 130 * Error codes: 131 * 132 * =pam_get_item 133 * !PAM_SYMBOL_ERR 134 * PAM_TRY_AGAIN 135 */ 136 137 /** 138 * The =openpam_subst function expands a string, substituting PAM item 139 * values for all occurrences of specific substitution codes. 140 * The =template argument points to the initial string. 141 * The result is stored in the buffer pointed to by the =buf argument; the 142 * =bufsize argument specifies the size of that buffer. 143 * The actual size of the resulting string, including the terminating NUL 144 * character, is stored in the location pointed to by the =bufsize 145 * argument. 146 * 147 * If =buf is NULL, or if the buffer is too small to hold the expanded 148 * string, =bufsize is updated to reflect the amount of space required to 149 * hold the entire string, and =openpam_subst returns =PAM_TRY_AGAIN. 150 * 151 * If =openpam_subst fails for any other reason, the =bufsize argument is 152 * untouched, but part of the buffer may still have been overwritten. 153 * 154 * Substitution codes are introduced by a percent character and correspond 155 * to PAM items: 156 * 157 * %H: 158 * Replaced by the current value of the =PAM_RHOST item. 159 * %h: 160 * Replaced by the current value of the =PAM_HOST item. 161 * %s: 162 * Replaced by the current value of the =PAM_SERVICE item. 163 * %t: 164 * Replaced by the current value of the =PAM_TTY item. 165 * %U: 166 * Replaced by the current value of the =PAM_RUSER item. 167 * %u: 168 * Replaced by the current value of the =PAM_USER item. 169 * 170 * >pam_get_authtok 171 * >pam_get_item 172 * >pam_get_user 173 * 174 * AUTHOR DES 175 */ 176