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
openpam_subst(const pam_handle_t * pamh,char * buf,size_t * bufsize,const char * template)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