Annotation of src/usr.bin/ssh/readpass.c, Revision 1.47
1.47 ! deraadt 1: /* $OpenBSD: readpass.c,v 1.46 2006/08/01 23:22:47 stevesk Exp $ */
1.1 deraadt 2: /*
1.26 markus 3: * Copyright (c) 2001 Markus Friedl. All rights reserved.
1.8 deraadt 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: *
1.26 markus 14: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
1.6 deraadt 24: */
1.35 stevesk 25:
26: #include <sys/types.h>
27: #include <sys/wait.h>
1.19 markus 28:
1.42 stevesk 29: #include <errno.h>
1.40 stevesk 30: #include <fcntl.h>
1.34 stevesk 31: #include <paths.h>
1.19 markus 32: #include <readpassphrase.h>
1.41 stevesk 33: #include <stdarg.h>
1.46 stevesk 34: #include <stdio.h>
1.45 stevesk 35: #include <stdlib.h>
1.44 stevesk 36: #include <string.h>
1.43 stevesk 37: #include <unistd.h>
1.1 deraadt 38:
39: #include "xmalloc.h"
1.29 djm 40: #include "misc.h"
1.15 markus 41: #include "pathnames.h"
42: #include "log.h"
43: #include "ssh.h"
1.38 markus 44: #include "uidswap.h"
1.15 markus 45:
1.18 itojun 46: static char *
1.16 mouring 47: ssh_askpass(char *askpass, const char *msg)
1.15 markus 48: {
49: pid_t pid;
50: size_t len;
1.23 markus 51: char *pass;
1.24 djm 52: int p[2], status, ret;
1.15 markus 53: char buf[1024];
54:
55: if (fflush(stdout) != 0)
56: error("ssh_askpass: fflush: %s", strerror(errno));
57: if (askpass == NULL)
58: fatal("internal error: askpass undefined");
1.21 markus 59: if (pipe(p) < 0) {
60: error("ssh_askpass: pipe: %s", strerror(errno));
1.28 markus 61: return NULL;
1.21 markus 62: }
63: if ((pid = fork()) < 0) {
64: error("ssh_askpass: fork: %s", strerror(errno));
1.28 markus 65: return NULL;
1.21 markus 66: }
1.15 markus 67: if (pid == 0) {
1.39 markus 68: permanently_drop_suid(getuid());
1.15 markus 69: close(p[0]);
70: if (dup2(p[1], STDOUT_FILENO) < 0)
71: fatal("ssh_askpass: dup2: %s", strerror(errno));
72: execlp(askpass, askpass, msg, (char *) 0);
73: fatal("ssh_askpass: exec(%s): %s", askpass, strerror(errno));
74: }
75: close(p[1]);
1.24 djm 76:
77: len = ret = 0;
78: do {
79: ret = read(p[0], buf + len, sizeof(buf) - 1 - len);
80: if (ret == -1 && errno == EINTR)
81: continue;
82: if (ret <= 0)
83: break;
84: len += ret;
85: } while (sizeof(buf) - 1 - len > 0);
86: buf[len] = '\0';
87:
1.15 markus 88: close(p[0]);
89: while (waitpid(pid, &status, 0) < 0)
90: if (errno != EINTR)
91: break;
1.24 djm 92:
1.28 markus 93: if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
94: memset(buf, 0, sizeof(buf));
95: return NULL;
96: }
97:
1.23 markus 98: buf[strcspn(buf, "\r\n")] = '\0';
1.15 markus 99: pass = xstrdup(buf);
100: memset(buf, 0, sizeof(buf));
101: return pass;
102: }
103:
1.7 markus 104: /*
1.19 markus 105: * Reads a passphrase from /dev/tty with echo turned off/on. Returns the
106: * passphrase (allocated with xmalloc). Exits if EOF is encountered. If
107: * RP_ALLOW_STDIN is set, the passphrase will be read from stdin if no
108: * tty is available
1.12 markus 109: */
1.5 markus 110: char *
1.19 markus 111: read_passphrase(const char *prompt, int flags)
1.1 deraadt 112: {
1.19 markus 113: char *askpass = NULL, *ret, buf[1024];
114: int rppflags, use_askpass = 0, ttyfd;
1.15 markus 115:
1.19 markus 116: rppflags = (flags & RP_ECHO) ? RPP_ECHO_ON : RPP_ECHO_OFF;
1.30 djm 117: if (flags & RP_USE_ASKPASS)
118: use_askpass = 1;
119: else if (flags & RP_ALLOW_STDIN) {
1.33 markus 120: if (!isatty(STDIN_FILENO)) {
1.32 dtucker 121: debug("read_passphrase: stdin is not a tty");
1.15 markus 122: use_askpass = 1;
1.33 markus 123: }
1.15 markus 124: } else {
1.19 markus 125: rppflags |= RPP_REQUIRE_TTY;
1.25 markus 126: ttyfd = open(_PATH_TTY, O_RDWR);
1.15 markus 127: if (ttyfd >= 0)
128: close(ttyfd);
1.32 dtucker 129: else {
130: debug("read_passphrase: can't open %s: %s", _PATH_TTY,
131: strerror(errno));
1.15 markus 132: use_askpass = 1;
1.32 dtucker 133: }
1.15 markus 134: }
1.30 djm 135:
136: if ((flags & RP_USE_ASKPASS) && getenv("DISPLAY") == NULL)
137: return (flags & RP_ALLOW_EOF) ? NULL : xstrdup("");
1.15 markus 138:
139: if (use_askpass && getenv("DISPLAY")) {
140: if (getenv(SSH_ASKPASS_ENV))
141: askpass = getenv(SSH_ASKPASS_ENV);
142: else
143: askpass = _PATH_SSH_ASKPASS_DEFAULT;
1.28 markus 144: if ((ret = ssh_askpass(askpass, prompt)) == NULL)
145: if (!(flags & RP_ALLOW_EOF))
146: return xstrdup("");
147: return ret;
1.15 markus 148: }
149:
1.27 markus 150: if (readpassphrase(prompt, buf, sizeof buf, rppflags) == NULL) {
151: if (flags & RP_ALLOW_EOF)
152: return NULL;
1.20 markus 153: return xstrdup("");
1.27 markus 154: }
1.19 markus 155:
156: ret = xstrdup(buf);
157: memset(buf, 'x', sizeof buf);
158: return ret;
1.31 djm 159: }
160:
161: int
162: ask_permission(const char *fmt, ...)
163: {
164: va_list args;
165: char *p, prompt[1024];
166: int allowed = 0;
167:
168: va_start(args, fmt);
169: vsnprintf(prompt, sizeof(prompt), fmt, args);
170: va_end(args);
171:
172: p = read_passphrase(prompt, RP_USE_ASKPASS|RP_ALLOW_EOF);
173: if (p != NULL) {
174: /*
175: * Accept empty responses and responses consisting
176: * of the word "yes" as affirmative.
177: */
178: if (*p == '\0' || *p == '\n' ||
179: strcasecmp(p, "yes") == 0)
180: allowed = 1;
181: xfree(p);
182: }
183:
184: return (allowed);
1.1 deraadt 185: }