1: /*
2: * Copyright (c) 1996, 1998-2005, 2007-2013
3: * Todd C. Miller <Todd.Miller@courtesan.com>
4: *
5: * Permission to use, copy, modify, and distribute this software for any
6: * purpose with or without fee is hereby granted, provided that the above
7: * copyright notice and this permission notice appear in all copies.
8: *
9: * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10: * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11: * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12: * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13: * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14: * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15: * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16: *
17: * Sponsored in part by the Defense Advanced Research Projects
18: * Agency (DARPA) and Air Force Research Laboratory, Air Force
19: * Materiel Command, USAF, under agreement number F39502-99-1-0512.
20: */
21:
22: #ifdef __TANDEM
23: # include <floss.h>
24: #endif
25:
26: #include <config.h>
27:
28: #include <sys/types.h>
29: #include <stdio.h>
30: #ifdef STDC_HEADERS
31: # include <stdlib.h>
32: # include <stddef.h>
33: #else
34: # ifdef HAVE_STDLIB_H
35: # include <stdlib.h>
36: # endif
37: #endif /* STDC_HEADERS */
38: #ifdef HAVE_STRING_H
39: # if defined(HAVE_MEMORY_H) && !defined(STDC_HEADERS)
40: # include <memory.h>
41: # endif
42: # include <string.h>
43: #endif /* HAVE_STRING_H */
44: #ifdef HAVE_STRINGS_H
45: # include <strings.h>
46: #endif /* HAVE_STRINGS_H */
47: #ifdef HAVE_UNISTD_H
48: # include <unistd.h>
49: #endif /* HAVE_UNISTD_H */
50: #include <pwd.h>
51: #include <errno.h>
52: #include <signal.h>
53: #include <fcntl.h>
54:
55: #include "sudo.h"
56: #include "sudo_plugin.h"
57:
58: static volatile sig_atomic_t signo[NSIG];
59:
60: static void tgetpass_handler(int);
61: static char *getln(int, char *, size_t, int);
62: static char *sudo_askpass(const char *, const char *);
63:
64: /*
65: * Like getpass(3) but with timeout and echo flags.
66: */
67: char *
68: tgetpass(const char *prompt, int timeout, int flags)
69: {
70: sigaction_t sa, savealrm, saveint, savehup, savequit, saveterm;
71: sigaction_t savetstp, savettin, savettou, savepipe;
72: char *pass;
73: static const char *askpass;
74: static char buf[SUDO_CONV_REPL_MAX + 1];
75: int i, input, output, save_errno, neednl = 0, need_restart;
76: debug_decl(tgetpass, SUDO_DEBUG_CONV)
77:
78: (void) fflush(stdout);
79:
80: if (askpass == NULL) {
81: askpass = getenv_unhooked("SUDO_ASKPASS");
82: if (askpass == NULL || *askpass == '\0')
83: askpass = sudo_conf_askpass_path();
84: }
85:
86: /* If no tty present and we need to disable echo, try askpass. */
87: if (!ISSET(flags, TGP_STDIN|TGP_ECHO|TGP_ASKPASS|TGP_NOECHO_TRY) &&
88: !tty_present()) {
89: if (askpass == NULL || getenv_unhooked("DISPLAY") == NULL) {
90: warningx(U_("no tty present and no askpass program specified"));
91: debug_return_str(NULL);
92: }
93: SET(flags, TGP_ASKPASS);
94: }
95:
96: /* If using a helper program to get the password, run it instead. */
97: if (ISSET(flags, TGP_ASKPASS)) {
98: if (askpass == NULL || *askpass == '\0')
99: fatalx(U_("no askpass program specified, try setting SUDO_ASKPASS"));
100: debug_return_str_masked(sudo_askpass(askpass, prompt));
101: }
102:
103: restart:
104: for (i = 0; i < NSIG; i++)
105: signo[i] = 0;
106: pass = NULL;
107: save_errno = 0;
108: need_restart = 0;
109: /* Open /dev/tty for reading/writing if possible else use stdin/stderr. */
110: if (ISSET(flags, TGP_STDIN) ||
111: (input = output = open(_PATH_TTY, O_RDWR|O_NOCTTY)) == -1) {
112: input = STDIN_FILENO;
113: output = STDERR_FILENO;
114: }
115:
116: /*
117: * If we are using a tty but are not the foreground pgrp this will
118: * generate SIGTTOU, so do it *before* installing the signal handlers.
119: */
120: if (!ISSET(flags, TGP_ECHO)) {
121: if (ISSET(flags, TGP_MASK))
122: neednl = term_cbreak(input);
123: else
124: neednl = term_noecho(input);
125: }
126:
127: /*
128: * Catch signals that would otherwise cause the user to end
129: * up with echo turned off in the shell.
130: */
131: memset(&sa, 0, sizeof(sa));
132: sigemptyset(&sa.sa_mask);
133: sa.sa_flags = SA_INTERRUPT; /* don't restart system calls */
134: sa.sa_handler = tgetpass_handler;
135: (void) sigaction(SIGALRM, &sa, &savealrm);
136: (void) sigaction(SIGINT, &sa, &saveint);
137: (void) sigaction(SIGHUP, &sa, &savehup);
138: (void) sigaction(SIGQUIT, &sa, &savequit);
139: (void) sigaction(SIGTERM, &sa, &saveterm);
140: (void) sigaction(SIGTSTP, &sa, &savetstp);
141: (void) sigaction(SIGTTIN, &sa, &savettin);
142: (void) sigaction(SIGTTOU, &sa, &savettou);
143:
144: /* Ignore SIGPIPE in case stdin is a pipe and TGP_STDIN is set */
145: sa.sa_handler = SIG_IGN;
146: (void) sigaction(SIGPIPE, &sa, &savepipe);
147:
148: if (prompt) {
149: if (write(output, prompt, strlen(prompt)) == -1)
150: goto restore;
151: }
152:
153: if (timeout > 0)
154: alarm(timeout);
155: pass = getln(input, buf, sizeof(buf), ISSET(flags, TGP_MASK));
156: alarm(0);
157: save_errno = errno;
158:
159: if (neednl || pass == NULL) {
160: if (write(output, "\n", 1) == -1)
161: goto restore;
162: }
163:
164: restore:
165: /* Restore old tty settings and signals. */
166: if (!ISSET(flags, TGP_ECHO))
167: term_restore(input, 1);
168: (void) sigaction(SIGALRM, &savealrm, NULL);
169: (void) sigaction(SIGINT, &saveint, NULL);
170: (void) sigaction(SIGHUP, &savehup, NULL);
171: (void) sigaction(SIGQUIT, &savequit, NULL);
172: (void) sigaction(SIGTERM, &saveterm, NULL);
173: (void) sigaction(SIGTSTP, &savetstp, NULL);
174: (void) sigaction(SIGTTIN, &savettin, NULL);
175: (void) sigaction(SIGTTOU, &savettou, NULL);
176: (void) sigaction(SIGTTOU, &savepipe, NULL);
177: if (input != STDIN_FILENO)
178: (void) close(input);
179:
180: /*
181: * If we were interrupted by a signal, resend it to ourselves
182: * now that we have restored the signal handlers.
183: */
184: for (i = 0; i < NSIG; i++) {
185: if (signo[i]) {
186: kill(getpid(), i);
187: switch (i) {
188: case SIGTSTP:
189: case SIGTTIN:
190: case SIGTTOU:
191: need_restart = 1;
192: break;
193: }
194: }
195: }
196: if (need_restart)
197: goto restart;
198:
199: if (save_errno)
200: errno = save_errno;
201:
202: debug_return_str_masked(pass);
203: }
204:
205: /*
206: * Fork a child and exec sudo-askpass to get the password from the user.
207: */
208: static char *
209: sudo_askpass(const char *askpass, const char *prompt)
210: {
211: static char buf[SUDO_CONV_REPL_MAX + 1], *pass;
212: sigaction_t sa, saved_sa_pipe;
213: int pfd[2];
214: pid_t pid;
215: debug_decl(sudo_askpass, SUDO_DEBUG_CONV)
216:
217: if (pipe(pfd) == -1)
218: fatal(U_("unable to create pipe"));
219:
220: if ((pid = fork()) == -1)
221: fatal(U_("unable to fork"));
222:
223: if (pid == 0) {
224: /* child, point stdout to output side of the pipe and exec askpass */
225: if (dup2(pfd[1], STDOUT_FILENO) == -1) {
226: warning("dup2");
227: _exit(255);
228: }
229: if (setuid(ROOT_UID) == -1)
230: warning("setuid(%d)", ROOT_UID);
231: if (setgid(user_details.gid)) {
232: warning(U_("unable to set gid to %u"), (unsigned int)user_details.gid);
233: _exit(255);
234: }
235: if (setuid(user_details.uid)) {
236: warning(U_("unable to set uid to %u"), (unsigned int)user_details.uid);
237: _exit(255);
238: }
239: closefrom(STDERR_FILENO + 1);
240: execl(askpass, askpass, prompt, (char *)NULL);
241: warning(U_("unable to run %s"), askpass);
242: _exit(255);
243: }
244:
245: /* Ignore SIGPIPE in case child exits prematurely */
246: memset(&sa, 0, sizeof(sa));
247: sigemptyset(&sa.sa_mask);
248: sa.sa_flags = SA_INTERRUPT;
249: sa.sa_handler = SIG_IGN;
250: (void) sigaction(SIGPIPE, &sa, &saved_sa_pipe);
251:
252: /* Get response from child (askpass) and restore SIGPIPE handler */
253: (void) close(pfd[1]);
254: pass = getln(pfd[0], buf, sizeof(buf), 0);
255: (void) close(pfd[0]);
256: (void) sigaction(SIGPIPE, &saved_sa_pipe, NULL);
257:
258: if (pass == NULL)
259: errno = EINTR; /* make cancel button simulate ^C */
260:
261: debug_return_str_masked(pass);
262: }
263:
264: extern int term_erase, term_kill;
265:
266: static char *
267: getln(int fd, char *buf, size_t bufsiz, int feedback)
268: {
269: size_t left = bufsiz;
270: ssize_t nr = -1;
271: char *cp = buf;
272: char c = '\0';
273: debug_decl(getln, SUDO_DEBUG_CONV)
274:
275: if (left == 0) {
276: errno = EINVAL;
277: debug_return_str(NULL); /* sanity */
278: }
279:
280: while (--left) {
281: nr = read(fd, &c, 1);
282: if (nr != 1 || c == '\n' || c == '\r')
283: break;
284: if (feedback) {
285: if (c == term_kill) {
286: while (cp > buf) {
287: if (write(fd, "\b \b", 3) == -1)
288: break;
289: --cp;
290: }
291: left = bufsiz;
292: continue;
293: } else if (c == term_erase) {
294: if (cp > buf) {
295: if (write(fd, "\b \b", 3) == -1)
296: break;
297: --cp;
298: left++;
299: }
300: continue;
301: }
302: ignore_result(write(fd, "*", 1));
303: }
304: *cp++ = c;
305: }
306: *cp = '\0';
307: if (feedback) {
308: /* erase stars */
309: while (cp > buf) {
310: if (write(fd, "\b \b", 3) == -1)
311: break;
312: --cp;
313: }
314: }
315:
316: debug_return_str_masked(nr == 1 ? buf : NULL);
317: }
318:
319: static void
320: tgetpass_handler(int s)
321: {
322: if (s != SIGALRM)
323: signo[s] = 1;
324: }
325:
326: int
327: tty_present(void)
328: {
329: int fd;
330: debug_decl(tty_present, SUDO_DEBUG_UTIL)
331:
332: if ((fd = open(_PATH_TTY, O_RDWR|O_NOCTTY)) != -1)
333: close(fd);
334: debug_return_bool(fd != -1);
335: }
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