Attached is a copy of poppassd.c which works under Solaris 2.6 running
NIS+ (prompts from /bin/passwd change under these conditions).
Compile with:
gcc -c -g poppassd.c
gcc -o poppassd -g poppassd.o
/*
* poppassd.c
*
* A Eudora and NUPOP change password server for Solaris.
*
* Graziano Sommariva
* Ansaldo Sistemi Informatici Genova Italy.
* sommariva@ansaldo.it
*
* Based on earlier versions by
* John Norstad
* j-norstad@nwu.edu
*
* Doesn't actually change any passwords itself. It simply listens for
* incoming requests, gathers the required information (user name, old
* password, new password) and executes /bin/passwd, talking to it over
* a pseudo-terminal pair. The advantage of this is that we don't need
* to have any knowledge of either the password file format (which may
* include dbx files that need to be rebuilt) or of any file locking
* protocol /bin/passwd and cohorts may use (and which isn't documented).
*
* The current version has been tested under Solaris 2.3 and used by
* Eudora 2.0.3 .
*
* Note that unencrypted passwords are transmitted over the network. If
* this bothers you, think hard about whether you want to implement the
* password changing feature. On the other hand, it's no worse than what
* happens when you run /bin/passwd while connected via telnet or rlogin.
* Well, maybe it is, since the use of a dedicated port makes it slightly
* easier for a network snooper to snarf passwords off the wire.
*
* NOTE: In addition to the security issue outlined in the above paragraph,
* you should be aware that this program is going to be run as root by
* ordinary users and it mucks around with the password file. This should
* set alarms off in your head. I think I've devised a pretty foolproof
* way to ensure that security is maintained, but I'm no security expert and
* you would be a fool to install this without first reading the code and
* ensuring yourself that what I consider safe is good enough for you. If
* something goes wrong, it's your fault, not mine.
*
*
* I made changes on the retriving of the crypted password and about
* the assigning of the pseudo-ttys.
*
* Should be owned by root, and executable only by root. It can be started
* with an entry in /etc/inetd.conf such as the following:
*
* poppassd stream tcp nowait root /usr/local/bin/poppassd poppassd
*
* and in /etc/services:
*
* poppassd 106/tcp
*
* Logs to the local2 facility. Should have an entry in /etc/syslog.conf
* like the following:
*
* local2.err /var/adm/poppassd-log
*
* 4/26/95 -
* Added AUTH_UID. This feature disables the ability of users below
* the specified UID from being able to change their passwords via
* this program.
*
* Changed #include <strings.h> to <string.h> and moved varargs.h
* above the syslog.h include.
*
* I also added a timeout during input. [mark@qualcomm.com]
*
* 2/29/96 -
* Added string for Solaris2.5 passwd program. [mark@qualcomm.com]
*
* 11/18/97
* Added strings for Solaris2.6/NIS+ passwd program. [js@cctechnol.com]
*
* 4/30/97
* Added more strings to support /bin/passwd under Solaris 2.6/NIS+.
* [sbk@fred.fhcrc.org]
*
*
*/
/* Steve Dorner's description of the simple protocol:
*
* The server's responses should be like an FTP server's responses;
* 1xx for in progress, 2xx for success, 3xx for more information
* needed, 4xx for temporary failure, and 5xx for permanent failure.
* Putting it all together, here's a sample conversation:
*
* S: 200 hello\r\n
* E: user yourloginname\r\n
* S: 300 please send your password now\r\n
* E: pass yourcurrentpassword\r\n
* S: 200 My, that was tasty\r\n
* E: newpass yournewpassword\r\n
* S: 200 Happy to oblige\r\n
* E: quit\r\n
* S: 200 Bye-bye\r\n
* S: <closes connection>
* E: <closes connection>
*/
#define VERSION "1.2b for Solaris 2.6 w/NIS+"
#define SUCCESS 1
#define FAILURE 0
#define BUFSIZE 512
#include <sys/conf.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <unistd.h>
#include <fcntl.h>
#include <varargs.h>
#include <syslog.h>
#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <errno.h>
#include <pwd.h>
#include <shadow.h>
#include <string.h>
#include <termios.h>
#include <stropts.h>
#include <dirent.h>
#include <signal.h>
/* Prompt strings expected from the "passwd" command. If you want
* to port this program to yet another flavor of UNIX, you may need to add
* more prompt strings here.
*
* Each prompt is defined as an array of pointers to alternate
* strings, terminated by an empty string. In the strings, '*'
* matches any sequence of 0 or more characters. Pattern matching
* is case-insensitive.
*/
/* UIDs below this one are not authorized to change their password */
#define AUTH_UID 99
#define LOG_FACILITY LOG_LOCAL1
static char *P1[] =
{"Old password:",
"Old password: ",
"Enter login password: ",
"Enter login(NIS) password: ",
"Enter login(NIS+) password: ",
"Changing password for *.\nOld password:",
"Changing password for * on *.\nOld password:",
"Changing NIS password for * on *.\nOld password:",
"Changing password for *\n*'s Old password:",
"passwd: Changing password for a85011\nOld password: ",
"passwd: Changing password for *\nEnter login(NIS+) password:",
"passwd: Changing password for *\nEnter login(NIS+) password: ",
"passwd: Changing password for *\nEnter login password:",
"passwd: Changing password for *\nEnter login password: ",
""};
static char *P2[] =
{"\nNew password:",
"\nNew password: ",
"\n*'s New password:",
""};
static char *P3[] =
{"\nRe-enter new password:",
"\nRe-enter new password: ",
"\nRe-enter new password:",
"\nRetype new password:",
"\nEnter the new password again:",
"\n*Re-enter *'s new password:",
"\nVerify:",
""};
static char *P4[] =
{"\n",
"NIS(YP) passwd/attributes changed on *\n",
"NIS entry changed on *\n",
"NIS+ password information changed for *\nNIS+ credential information changed for *",
"NIS+ password information changed for *\nNIS+ credential information changed for *\n",
"passwd (SYSTEM): passwd successfully changed for *",
"passwd (SYSTEM): passwd successfully changed for *\n",
""};
abortme()
{
WriteToClient ("500 Timeout. Input idle for too long.");
exit(1);
}
main (argc, argv)
int argc;
char *argv[];
{
char line[BUFSIZE];
char user[BUFSIZE];
char oldpass[BUFSIZE];
char newpass[BUFSIZE];
char emess[BUFSIZE];
char *slavedev;
struct passwd *pw, *getpwnam();
struct spwd *sp, *getspnam();
int c, master;
pid_t pid, wpid;
int wstat;
(void)signal(SIGALRM, (void *)abortme);
*user = *oldpass = *newpass = 0;
openlog ("poppassd", LOG_PID, LOG_FACILITY);
WriteToClient ("200 poppassd v%s hello, who are you?", VERSION);
ReadFromClient (line);
sscanf (line, "user %s", user) ;
if (strlen (user) == 0)
{
WriteToClient ("500 Username required.");
exit(1);
}
WriteToClient ("200 your password please.");
ReadFromClient (line);
sscanf (line, "pass %s", oldpass) ;
if (strlen (oldpass) == 0)
{
WriteToClient ("500 Password required.");
exit(1);
}
if ( ((pw = getpwnam (user)) == NULL) || ((sp = getspnam (user)) == NULL) )
{
WriteToClient ("500 Unknown user, %s.", user);
exit(1);
}
if (pw->pw_uid <= AUTH_UID)
{
syslog (LOG_ERR, "Authorization error, attempt to change password of %s", user);
WriteToClient ("500 Old password is incorrect.");
exit(1);
}
if (chkPass (user, oldpass, sp->sp_pwdp) == FAILURE)
{
WriteToClient ("500 Old password is incorrect.");
exit(1);
}
WriteToClient ("200 your new password please.");
ReadFromClient (line);
sscanf (line, "newpass %s", newpass);
/* new pass required */
if (strlen (newpass) == 0)
{
WriteToClient ("500 New password required.");
exit(1);
}
/* get pts to talk to password program */
if ((master = findpts (&slavedev)) < 0)
{
syslog (LOG_ERR, "can't find pts for master");
WriteToClient("500 Server busy - try again later.");
exit (1);
}
/* fork child process to talk to password program */
if ((pid = fork()) < 0) /* Error, can't fork */
{
syslog (LOG_ERR, "can't fork for passwd: %m");
WriteToClient ("500 Server error (can't fork passwd), get help!");
exit (1);
}
if (pid) /* Parent */
{
sleep (1); /* Make sure child is ready. Is this really needed? */
if (talktochild (master, user, oldpass, newpass, emess) == FAILURE)
{
syslog (LOG_ERR, "failed attempt by %s", user);
if (*emess == '\0') {
WriteToClient ("500 Unable to change password." );
} else {
WriteToClient ("500 %s", emess);
}
exit(1);
}
if ((wpid = waitpid (pid, &wstat, 0)) < 0)
{
syslog (LOG_ERR, "wait for /bin/passwd child failed: %m");
WriteToClient ("500 Server error (wait failed), get help!");
exit (1);
}
if (pid != wpid)
{
syslog (LOG_ERR, "wrong child (/bin/passwd waited for!");
WriteToClient ("500 Server error (wrong child), get help!");
exit (1);
}
if (WIFEXITED (wstat) == 0)
{
syslog (LOG_ERR, "child (/bin/passwd) killed?");
WriteToClient ("500 Server error (funny wstat), get help!");
exit (1);
}
if (WEXITSTATUS (wstat) != 0)
{
syslog (LOG_ERR, "child (/bin/passwd) exited abnormally");
WriteToClient ("500 Server error (abnormal exit), get help!");
exit (1);
}
syslog (LOG_ERR, "password changed for %s", user);
WriteToClient ("200 Password changed, thank-you.");
ReadFromClient (line);
if (strncmp(line, "quit", 4) != 0) {
WriteToClient("500 Quit required.");
exit (1);
}
WriteToClient("200 Bye.");
exit (0);
}
else /* Child */
{
dochild (master, slavedev, user, pw);
}
}
/*
* dochild
*
* Do child stuff - set up slave pts and execl /bin/passwd.
*
* Code adapted from "Advanced Programming in the UNIX Environment"
* by W. Richard Stevens.
*
*/
dochild (master, slavedev, user, pw)
int master;
char *slavedev, *user;
struct passwd *pw;
{
int slave;
struct termios stermios;
/* Start new session - gets rid of controlling terminal. */
if (setsid() < 0) {
syslog(LOG_ERR, "setsid failed: %m");
return(0);
}
/* Open slave pty and acquire as new controlling terminal. */
if ((slave = open(slavedev, O_RDWR)) < 0) {
syslog(LOG_ERR, "can't open slave pty %s: %m");
return(0);
}
ioctl(slave, I_PUSH, "ptem");
ioctl(slave, I_PUSH, "ldterm");
/* Close master. */
close(master);
/* Make slave stdin/out/err of child. */
if (dup2(slave, STDIN_FILENO) != STDIN_FILENO) {
syslog(LOG_ERR, "dup2 error to stdin: %m");
return(0);
}
if (dup2(slave, STDOUT_FILENO) != STDOUT_FILENO) {
syslog(LOG_ERR, "dup2 error to stdout: %m");
return(0);
}
if (dup2(slave, STDERR_FILENO) != STDERR_FILENO) {
syslog(LOG_ERR, "dup2 error to stderr: %m");
return(0);
}
if (slave > 2) close(slave);
/* Set proper terminal attributes - no echo, canonical input processing,
no map NL to CR/NL on output. */
if (tcgetattr(0, &stermios) < 0) {
syslog(LOG_ERR, "tcgetattr error: %m");
return(0);
}
stermios.c_lflag &= ~(ECHO | ECHOE | ECHOK | ECHONL);
stermios.c_lflag |= ICANON;
stermios.c_oflag &= ~(ONLCR);
if (tcsetattr(0, TCSANOW, &stermios) < 0) {
syslog(LOG_ERR, "tcsetattr error: %m");
return(0);
}
/*
* Become the user trying who's password is being changed. We're
* about to exec /bin/passwd with is setuid root anyway, but this
* way it looks to the child completely like it's being run by
* the normal user, which makes it do its own password verification
* before doing any thing. In theory, we've already verified the
* password, but this extra level of checking doesn't hurt. Besides,
* the way I do it here, if somebody manages to change somebody
* else's password, you can complain to your vendor about security
* holes, not to me!
*/
setuid (pw->pw_uid);
setgid (pw->pw_gid);
/* Fork /bin/passwd. */
if (execl("/bin/passwd", "passwd", user, (char*)0) < 0) {
syslog(LOG_ERR, "can't exec /bin/passwd: %m");
return(0);
}
}
/*
* findpts()
*
* Finds the first available pseudo-terminal master/slave pair. The master
* side is opened and a fd returned as the function value. A pointer to the
* name of the slave side (i.e. "/dev/pts/N" N [1 N-1]) is returned
* in the argument, which should be a char**.
* The name itself is stored in a static buffer.
*
* A negative value is returned on any sort of error.
*
* Modified by Norstad to remove assumptions about number of pts's allocated
* on this UNIX box.
*/
findpts (slave)
char **slave;
{
int master;
extern char *ptsname();
if ((master = open("/dev/ptmx", O_RDWR)) >= 1) {
grantpt(master);
unlockpt(master);
*slave = ptsname(master);
return(master);
}
return (-1);
}
/*
* writestring()
*
* Write a string in a single write() system call.
*/
writestring (fd, s)
char *s;
{
int l;
l = strlen (s);
write (fd, s, l);
}
/*
* talktochild()
*
* Handles the conversation between the parent and child (password program)
* processes.
*
* Returns SUCCESS is the conversation is completed without any problems,
* FAILURE if any errors are encountered (in which case, it can be assumed
* that the password wasn't changed).
*/
talktochild (master, user, oldpass, newpass, emess)
int master;
char *user, *oldpass, *newpass, *emess;
{
char buf[BUFSIZE];
char pswd[BUFSIZE+1];
int m, n;
*emess = 0;
if (!expect(master, P1, buf))
{
syslog (LOG_DEBUG, "fail userid");
return FAILURE;
}
sprintf(pswd, "%s\n", oldpass);
writestring(master, pswd);
if (!expect(master, P2, buf))
{
syslog (LOG_DEBUG, "fail oldpass");
return FAILURE;
}
sprintf(pswd, "%s\n", newpass);
writestring(master, pswd);
if (!expect(master, P3, buf)) {
syslog (LOG_DEBUG, "fail newpass");
getemess(master, P2, buf);
strcpy(emess, buf);
return FAILURE;
}
writestring(master, pswd);
if (!expect(master, P4, buf))
{
syslog (LOG_DEBUG, "fail 2nd newpass");
return FAILURE;
}
return SUCCESS;
}
/*
* match ()
*
* Matches a string against a pattern. Wild-card characters '*' in
* the pattern match any sequence of 0 or more characters in the string.
* The match is case-insensitive.
*
* Entry: str = string.
* pat = pattern.
*
* Exit: function result =
* 0 if no match.
* 1 if the string matches some initial segment of
* the pattern.
* 2 if the string matches the full pattern.
*/
match (str, pat)
char *str;
char *pat;
{
int result;
for (; *str && *pat && *pat != '*'; str++, pat++)
if (tolower(*str) != tolower(*pat)) return 0;
if (*str == 0) return *pat == 0 ? 2 : 1;
if (*pat == 0) return 0;
for (; *str; str++) if ((result = match(str, pat+1)) != 0) return result;
return 0;
}
/*
* expect ()
*
* Reads 'passwd' command output and compares it to expected output.
*
* Entry: master = fid of master pts.
* expected = pointer to array of pointers to alternate expected
* strings, terminated by an empty string.
* buf = pointer to buffer.
*
* Exit: function result = SUCCESS if output matched, FAILURE if not.
* buf = the text read from the slave.
*
* Text is read from the slave and accumulated in buf. As long as
* the text accumulated so far is an initial segment of at least
* one of the expected strings, the function continues the read.
* As soon as one of full expected strings has been read, the
* function returns SUCCESS. As soon as the text accumulated so far
* is not an initial segment of or exact match for at least one of
* the expected strings, the function returns FAILURE.
*/
expect (master, expected, buf)
int master;
char **expected;
char *buf;
{
int n, m;
char **s;
int initialSegment;
int result;
char c;
n = 0;
buf[0] = 0;
while (1) {
if (n >= BUFSIZE-1) {
syslog(LOG_ERR, "buffer overflow on read from child");
return FAILURE;
}
m = read(master, buf+n, BUFSIZE-1-n);
if (m < 0) {
syslog(LOG_ERR, "read error from child: %m");
return FAILURE;
}
n += m;
buf[n] = 0;
initialSegment = 0;
for (s = expected; **s != 0; s++) {
result = match(buf, *s);
if (result == 2) return SUCCESS;
initialSegment = initialSegment || result == 1;
}
if (!initialSegment) return FAILURE;
}
}
/*
* getemess()
*
* This function accumulates a 'passwd' command error message issued
* after the first copy of the password has been sent.
*
* Entry: master = fid of master pts.
* expected = pointer to array of pointers to alternate expected
* strings for first password prompt, terminated by an
* empty string.
* buf = pointer to buffer containing text read so far.
*
* Exit: buf = the error message read from the slave.
*
* Text is read from the slave and accumulated in buf until the text
* at the end of the buffer is an exact match for one of the expected
* prompt strings. The expected prompt string is removed from the buffer,
* returning just the error message text. Newlines in the error message
* text are replaced by spaces.
*/
getemess (master, expected, buf)
int master;
char **expected;
char *buf;
{
int n, m;
char **s;
char *p, *q;
n = strlen(buf);
while (1) {
for (s = expected; **s != 0; s++) {
for (p = buf; *p; p++) {
if (match(p, *s) == 2) {
*p = 0;
for (q = buf; *q; q++) if (*q == '\n') *q = ' ';
return;
}
}
}
if (n >= BUFSIZE-1) {
syslog(LOG_ERR, "buffer overflow on read from child");
return;
}
m = read(master, buf+n, BUFSIZE+1-n);
if (m < 0) {
syslog(LOG_ERR, "read error from child: %m");
return;
}
n += m;
buf[n] = 0;
}
}
WriteToClient (fmt, va_alist)
char *fmt;
va_dcl
{
va_list ap;
va_start (ap);
vfprintf (stdout, fmt, ap);
fputs ("\r\n", stdout );
fflush (stdout);
va_end (ap);
}
ReadFromClient (line)
char *line;
{
char *sp;
int i;
strcpy (line, "");
alarm(60);
fgets (line, BUFSIZE, stdin);
alarm(0);
if ((sp = strchr(line, '\n')) != NULL) *sp = '\0';
if ((sp = strchr(line, '\r')) != NULL) *sp = '\0';
/* convert initial keyword on line to lower case. */
for (sp = line; isalpha(*sp); sp++) *sp = tolower(*sp);
}
char *crypt(char *, char *);
int chkPass (user, pass, sp)
char *user;
char *pass;
char *sp;
{
/* Compare the supplied password with the password file entry */
if (strcmp (crypt (pass, sp), sp) != 0)
return (FAILURE);
else
return (SUCCESS);
}
This archive was generated by hypermail 2.1.2 : Fri Sep 28 2001 - 23:12:39 CDT