1/*-
2 * Copyright (c) 2011-2023 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 * 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
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			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