1 /*
2 * Copyright 2009 Sun Microsystems, Inc. All rights reserved.
3 * Use is subject to license terms.
4 */
5
6 /*
7 * Copyright (c) 2001 Markus Friedl. All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29
30 #include "includes.h"
31 RCSID("$OpenBSD: readpass.c,v 1.27 2002/03/26 15:58:46 markus Exp $");
32
33 #include "xmalloc.h"
34 #include "readpass.h"
35 #include "pathnames.h"
36 #include "log.h"
37 #include "ssh.h"
38 #include <langinfo.h>
39
40 static char *
ssh_askpass(char * askpass,const char * msg)41 ssh_askpass(char *askpass, const char *msg)
42 {
43 pid_t pid;
44 size_t len;
45 char *pass;
46 int p[2], status, ret;
47 char buf[1024];
48
49 if (fflush(stdout) != 0)
50 error("ssh_askpass: fflush: %s", strerror(errno));
51 if (askpass == NULL)
52 fatal("internal error: askpass undefined");
53 if (pipe(p) < 0) {
54 error("ssh_askpass: pipe: %s", strerror(errno));
55 return xstrdup("");
56 }
57 if ((pid = fork()) < 0) {
58 error("ssh_askpass: fork: %s", strerror(errno));
59 return xstrdup("");
60 }
61 if (pid == 0) {
62 seteuid(getuid());
63 setuid(getuid());
64 close(p[0]);
65 if (dup2(p[1], STDOUT_FILENO) < 0)
66 fatal("ssh_askpass: dup2: %s", strerror(errno));
67 execlp(askpass, askpass, msg, (char *) 0);
68 fatal("ssh_askpass: exec(%s): %s", askpass, strerror(errno));
69 }
70 close(p[1]);
71
72 len = ret = 0;
73 do {
74 ret = read(p[0], buf + len, sizeof(buf) - 1 - len);
75 if (ret == -1 && errno == EINTR)
76 continue;
77 if (ret <= 0)
78 break;
79 len += ret;
80 } while (sizeof(buf) - 1 - len > 0);
81 buf[len] = '\0';
82
83 close(p[0]);
84 while (waitpid(pid, &status, 0) < 0)
85 if (errno != EINTR)
86 break;
87
88 buf[strcspn(buf, "\r\n")] = '\0';
89 pass = xstrdup(buf);
90 memset(buf, 0, sizeof(buf));
91 return pass;
92 }
93
94 /*
95 * Reads a passphrase from /dev/tty with echo turned off/on. Returns the
96 * passphrase (allocated with xmalloc). Exits if EOF is encountered. If
97 * RP_ALLOW_STDIN is set, the passphrase will be read from stdin if no
98 * tty is available
99 */
100 char *
read_passphrase(const char * prompt,int flags)101 read_passphrase(const char *prompt, int flags)
102 {
103 char *askpass = NULL, *ret, buf[1024];
104 int rppflags, use_askpass = 0, ttyfd;
105
106 rppflags = (flags & RP_ECHO) ? RPP_ECHO_ON : RPP_ECHO_OFF;
107 if (flags & RP_ALLOW_STDIN) {
108 if (!isatty(STDIN_FILENO))
109 use_askpass = 1;
110 } else {
111 rppflags |= RPP_REQUIRE_TTY;
112 ttyfd = open(_PATH_TTY, O_RDWR);
113 if (ttyfd >= 0)
114 close(ttyfd);
115 else
116 use_askpass = 1;
117 }
118
119 if (use_askpass && getenv("DISPLAY")) {
120 if (getenv(SSH_ASKPASS_ENV))
121 askpass = getenv(SSH_ASKPASS_ENV);
122 else
123 askpass = _PATH_SSH_ASKPASS_DEFAULT;
124 return ssh_askpass(askpass, prompt);
125 }
126
127 if (readpassphrase(prompt, buf, sizeof buf, rppflags) == NULL) {
128 if (flags & RP_ALLOW_EOF)
129 return NULL;
130 return xstrdup("");
131 }
132
133 ret = xstrdup(buf);
134 memset(buf, 'x', sizeof buf);
135 return ret;
136 }
137
138 int
ask_permission(const char * fmt,...)139 ask_permission(const char *fmt, ...)
140 {
141 va_list args;
142 char *p, prompt[1024];
143 int allowed = 0;
144 char *yeschar = nl_langinfo(YESSTR);
145
146 va_start(args, fmt);
147 vsnprintf(prompt, sizeof(prompt), fmt, args);
148 va_end(args);
149
150 p = read_passphrase(prompt, RP_USE_ASKPASS|RP_ALLOW_EOF);
151 if (p != NULL) {
152 /*
153 * Accept empty responses and responses consisting
154 * of the word "yes" as affirmative.
155 */
156 if (*p == '\0' || *p == '\n' ||
157 strncasecmp(p, yeschar, 1) == 0)
158 allowed = 1;
159 xfree(p);
160 }
161
162 return (allowed);
163 }
164