1 /*- 2 * Copyright (c) 2011-2023 Dag-Erling Smørgrav 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. The name of the author may not be used to endorse or promote 14 * products derived from this software without specific prior written 15 * permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30 #ifdef HAVE_CONFIG_H 31 # include "config.h" 32 #endif 33 34 #include <security/pam_appl.h> 35 36 #include "openpam_impl.h" 37 38 #define subst_char(ch) do { \ 39 int ch_ = (ch); \ 40 if (buf && len < *bufsize) \ 41 *buf++ = ch_; \ 42 ++len; \ 43 } while (0) 44 45 #define subst_string(s) do { \ 46 const char *s_ = (s); \ 47 while (*s_) \ 48 subst_char(*s_++); \ 49 } while (0) 50 51 #define subst_item(i) do { \ 52 int i_ = (i); \ 53 const void *p_; \ 54 ret = pam_get_item(pamh, i_, &p_); \ 55 if (ret == PAM_SUCCESS && p_ != NULL) \ 56 subst_string(p_); \ 57 } while (0) 58 59 /* 60 * OpenPAM internal 61 * 62 * Substitute PAM item values in a string 63 */ 64 65 int 66 openpam_subst(const pam_handle_t *pamh, 67 char *buf, size_t *bufsize, const char *template) 68 { 69 size_t len; 70 int ret; 71 72 ENTERS(template); 73 if (template == NULL) 74 template = "(null)"; 75 76 len = 1; /* initialize to 1 for terminating NUL */ 77 ret = PAM_SUCCESS; 78 while (*template && ret == PAM_SUCCESS) { 79 if (template[0] == '%') { 80 ++template; 81 switch (*template) { 82 case 's': 83 subst_item(PAM_SERVICE); 84 break; 85 case 't': 86 subst_item(PAM_TTY); 87 break; 88 case 'h': 89 subst_item(PAM_HOST); 90 break; 91 case 'u': 92 subst_item(PAM_USER); 93 break; 94 case 'H': 95 subst_item(PAM_RHOST); 96 break; 97 case 'U': 98 subst_item(PAM_RUSER); 99 break; 100 case '\0': 101 subst_char('%'); 102 break; 103 default: 104 subst_char('%'); 105 subst_char(*template); 106 } 107 if (*template) 108 ++template; 109 } else { 110 subst_char(*template++); 111 } 112 } 113 if (buf) 114 *buf = '\0'; 115 if (ret == PAM_SUCCESS) { 116 if (len > *bufsize) 117 ret = PAM_TRY_AGAIN; 118 *bufsize = len; 119 } 120 RETURNC(ret); 121 } 122 123 /* 124 * Error codes: 125 * 126 * =pam_get_item 127 * !PAM_SYMBOL_ERR 128 * PAM_TRY_AGAIN 129 */ 130 131 /** 132 * The =openpam_subst function expands a string, substituting PAM item 133 * values for all occurrences of specific substitution codes. 134 * The =template argument points to the initial string. 135 * The result is stored in the buffer pointed to by the =buf argument; the 136 * =bufsize argument specifies the size of that buffer. 137 * The actual size of the resulting string, including the terminating NUL 138 * character, is stored in the location pointed to by the =bufsize 139 * argument. 140 * 141 * If =buf is NULL, or if the buffer is too small to hold the expanded 142 * string, =bufsize is updated to reflect the amount of space required to 143 * hold the entire string, and =openpam_subst returns =PAM_TRY_AGAIN. 144 * 145 * If =openpam_subst fails for any other reason, the =bufsize argument is 146 * untouched, but part of the buffer may still have been overwritten. 147 * 148 * Substitution codes are introduced by a percent character and correspond 149 * to PAM items: 150 * 151 * %H: 152 * Replaced by the current value of the =PAM_RHOST item. 153 * %h: 154 * Replaced by the current value of the =PAM_HOST item. 155 * %s: 156 * Replaced by the current value of the =PAM_SERVICE item. 157 * %t: 158 * Replaced by the current value of the =PAM_TTY item. 159 * %U: 160 * Replaced by the current value of the =PAM_RUSER item. 161 * %u: 162 * Replaced by the current value of the =PAM_USER item. 163 * 164 * >pam_get_authtok 165 * >pam_get_item 166 * >pam_get_user 167 * 168 * AUTHOR DES 169 */ 170