1 /*-
2 * Copyright (c) 2011 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 * $OpenPAM: openpam_subst.c 938 2017-04-30 21:34:42Z des $
30 */
31
32 #ifdef HAVE_CONFIG_H
33 # include "config.h"
34 #endif
35
36 #include <security/pam_appl.h>
37
38 #include "openpam_impl.h"
39
40 #define subst_char(ch) do { \
41 int ch_ = (ch); \
42 if (buf && len < *bufsize) \
43 *buf++ = ch_; \
44 ++len; \
45 } while (0)
46
47 #define subst_string(s) do { \
48 const char *s_ = (s); \
49 while (*s_) \
50 subst_char(*s_++); \
51 } while (0)
52
53 #define subst_item(i) do { \
54 int i_ = (i); \
55 const void *p_; \
56 ret = pam_get_item(pamh, i_, &p_); \
57 if (ret == PAM_SUCCESS && p_ != NULL) \
58 subst_string(p_); \
59 } while (0)
60
61 /*
62 * OpenPAM internal
63 *
64 * Substitute PAM item values in a string
65 */
66
67 int
openpam_subst(const pam_handle_t * pamh,char * buf,size_t * bufsize,const char * template)68 openpam_subst(const pam_handle_t *pamh,
69 char *buf, size_t *bufsize, const char *template)
70 {
71 size_t len;
72 int ret;
73
74 ENTERS(template);
75 if (template == NULL)
76 template = "(null)";
77
78 len = 1; /* initialize to 1 for terminating NUL */
79 ret = PAM_SUCCESS;
80 while (*template && ret == PAM_SUCCESS) {
81 if (template[0] == '%') {
82 ++template;
83 switch (*template) {
84 case 's':
85 subst_item(PAM_SERVICE);
86 break;
87 case 't':
88 subst_item(PAM_TTY);
89 break;
90 case 'h':
91 subst_item(PAM_HOST);
92 break;
93 case 'u':
94 subst_item(PAM_USER);
95 break;
96 case 'H':
97 subst_item(PAM_RHOST);
98 break;
99 case 'U':
100 subst_item(PAM_RUSER);
101 break;
102 case '\0':
103 subst_char('%');
104 break;
105 default:
106 subst_char('%');
107 subst_char(*template);
108 }
109 ++template;
110 } else {
111 subst_char(*template++);
112 }
113 }
114 if (buf)
115 *buf = '\0';
116 if (ret == PAM_SUCCESS) {
117 if (len > *bufsize)
118 ret = PAM_TRY_AGAIN;
119 *bufsize = len;
120 }
121 RETURNC(ret);
122 }
123
124 /*
125 * Error codes:
126 *
127 * =pam_get_item
128 * !PAM_SYMBOL_ERR
129 * PAM_TRY_AGAIN
130 */
131
132 /**
133 * The =openpam_subst function expands a string, substituting PAM item
134 * values for all occurrences of specific substitution codes.
135 * The =template argument points to the initial string.
136 * The result is stored in the buffer pointed to by the =buf argument; the
137 * =bufsize argument specifies the size of that buffer.
138 * The actual size of the resulting string, including the terminating NUL
139 * character, is stored in the location pointed to by the =bufsize
140 * argument.
141 *
142 * If =buf is NULL, or if the buffer is too small to hold the expanded
143 * string, =bufsize is updated to reflect the amount of space required to
144 * hold the entire string, and =openpam_subst returns =PAM_TRY_AGAIN.
145 *
146 * If =openpam_subst fails for any other reason, the =bufsize argument is
147 * untouched, but part of the buffer may still have been overwritten.
148 *
149 * Substitution codes are introduced by a percent character and correspond
150 * to PAM items:
151 *
152 * %H:
153 * Replaced by the current value of the =PAM_RHOST item.
154 * %h:
155 * Replaced by the current value of the =PAM_HOST item.
156 * %s:
157 * Replaced by the current value of the =PAM_SERVICE item.
158 * %t:
159 * Replaced by the current value of the =PAM_TTY item.
160 * %U:
161 * Replaced by the current value of the =PAM_RUSER item.
162 * %u:
163 * Replaced by the current value of the =PAM_USER item.
164 *
165 * >pam_get_authtok
166 * >pam_get_item
167 * >pam_get_user
168 *
169 * AUTHOR DES
170 */
171