1/*-
2 * Copyright (c) 2011 Dag-Erling Sm��rgrav
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 * in this position and unchanged.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 *
27 * $Id: openpam_subst.c 461 2011-11-02 14:00:38Z des $
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
65int
66openpam_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 ++template;
108 } else {
109 subst_char(*template++);
110 }
111 }
112 if (buf)
113 *buf = '\0';
114 if (ret == PAM_SUCCESS) {
115 if (len > *bufsize)
116 ret = PAM_TRY_AGAIN;
117 *bufsize = len;
118 }
119 RETURNC(ret);
120}
121
122/*
123 * Error codes:
124 *
125 * =pam_get_item
126 * !PAM_SYMBOL_ERR
127 * PAM_TRY_AGAIN
128 */
129
130/**
131 * The =openpam_subst function expands a string, substituting PAM item
132 * values for all occurrences of specific substitution codes.
133 * The =template argument points to the initial string.
134 * The result is stored in the buffer pointed to by the =buf argument; the
135 * =bufsize argument specifies the size of that buffer.
136 * The actual size of the resulting string, including the terminating NUL
137 * character, is stored in the location pointed to by the =bufsize
138 * argument.
139 *
140 * If =buf is NULL, or if the buffer is too small to hold the expanded
141 * string, =bufsize is updated to reflect the amount of space required to
142 * hold the entire string, and =openpam_subst returns =PAM_TRY_AGAIN.
143 *
144 * If =openpam_subst fails for any other reason, the =bufsize argument is
145 * untouched, but part of the buffer may still have been overwritten.
146 *
147 * Substitution codes are introduced by a percent character and correspond
148 * to PAM items:
149 *
150 * %H:
151 * Replaced by the current value of the =PAM_RHOST item.
152 * %h:
153 * Replaced by the current value of the =PAM_HOST item.
154 * %s:
155 * Replaced by the current value of the =PAM_SERVICE item.
156 * %t:
157 * Replaced by the current value of the =PAM_TTY item.
158 * %U:
159 * Replaced by the current value of the =PAM_RUSER item.
160 * %u:
161 * Replaced by the current value of the =PAM_USER item.
162 *
163 * >pam_get_authtok
164 * >pam_get_item
165 * >pam_get_user
166 *
167 * AUTHOR DES
168 */