xref: /titanic_44/usr/src/cmd/cmd-inet/usr.bin/pppd/plugins/passprompt.c (revision 3f7d54a6b84904c8f4d8daa4c7b577bede7df8b9)
1 /*
2  * passprompt.c - pppd plugin to invoke an external PAP password prompter
3  *
4  * Copyright 1999 Paul Mackerras, Alan Curry.
5  *
6  *  This program is free software; you can redistribute it and/or
7  *  modify it under the terms of the GNU General Public License
8  *  as published by the Free Software Foundation; either version
9  *  2 of the License, or (at your option) any later version.
10  */
11 #include <errno.h>
12 #include <unistd.h>
13 #include <fcntl.h>
14 #include <sys/wait.h>
15 #include <syslog.h>
16 #include "pppd.h"
17 
18 static char promptprog[PATH_MAX+1];
19 
20 static option_t options[] = {
21     { "promptprog", o_string, promptprog,
22       "External PAP password prompting program",
23       OPT_STATIC, NULL, PATH_MAX },
24     { NULL }
25 };
26 
27 static int promptpass(char *user, char *passwd)
28 {
29     int p[2];
30     pid_t kid;
31     int readgood, wstat;
32     int red;
33 
34     if (promptprog[0] == 0 || access(promptprog, X_OK) < 0)
35 	return -1;	/* sorry, can't help */
36 
37     /* This occurs when we're probed for the ability to supply a password */
38     if (user != NULL && passwd == NULL)
39 	return 1;
40 
41     if (pipe(p)) {
42 	warn("Can't make a pipe for %s", promptprog);
43 	return 0;
44     }
45     if ((kid = fork()) == (pid_t) -1) {
46 	warn("Can't fork to run %s", promptprog);
47 	(void) close(p[0]);
48 	(void) close(p[1]);
49 	return 0;
50     }
51     if (kid == (pid_t)0) {
52 	/* we are the child, exec the program */
53 	char *argv[5], fdstr[32];
54 
55 	sys_close();
56 	closelog();
57 	if (detached && p[1] <= 2) {
58 	    (void) dup2(p[1], 3);
59 	    p[1] = 3;
60 	}
61 	(void) close(p[0]);
62 	if (detached) {
63 	    red = open("/etc/ppp/prompt-errors", O_WRONLY | O_APPEND | O_CREAT,
64 		0600);
65 	    (void) dup2(red, 1);
66 	    (void) dup2(red, 2);
67 	}
68 	(void) seteuid(getuid());
69 	(void) setegid(getgid());
70 	argv[0] = promptprog;
71 	argv[1] = user == NULL ? "" : user;
72 	argv[2] = remote_name;
73 	slprintf(fdstr, sizeof (fdstr), "%d", p[1]);
74 	argv[3] = fdstr;
75 	argv[4] = NULL;
76 	(void) execv(*argv, argv);
77 	_exit(127);
78     }
79 
80     /* we are the parent, read the password from the pipe */
81     (void) close(p[1]);
82     readgood = 0;
83     do {
84 	red = read(p[0], passwd + readgood, MAXSECRETLEN-1 - readgood);
85 	if (red == 0)
86 	    break;
87 	if (red < 0) {
88 	    if (errno == EINTR)
89 		continue;
90 	    error("Can't read secret from %s: %m", promptprog);
91 	    readgood = -1;
92 	    break;
93 	}
94 	readgood += red;
95     } while (readgood < MAXSECRETLEN - 1);
96     passwd[readgood] = 0;
97     (void) close(p[0]);
98 
99     /* now wait for child to exit */
100     while (waitpid(kid, &wstat, 0) < 0) {
101 	if (errno != EINTR) {
102 	    warn("error waiting for %s: %m", promptprog);
103 	    break;
104 	}
105     }
106 
107     if (readgood < 0)
108 	return 0;
109     if (readgood > 0 && passwd[--readgood] == '\n')
110 	passwd[readgood] = '\0';
111     if (!WIFEXITED(wstat))
112 	warn("%s terminated abnormally", promptprog);
113     if (WEXITSTATUS(wstat) != 0)
114 	warn("%s exited with code %d", promptprog, WEXITSTATUS(wstat));
115 
116     return 1;
117 }
118 
119 void plugin_init(void)
120 {
121     add_options(options);
122     pap_passwd_hook = promptpass;
123 }
124