142 lines
3.6 KiB
C
142 lines
3.6 KiB
C
/*
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* This is a sample filter program, for use with pam_filter (a module
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* provided with Linux-PAM). This filter simply transposes upper and
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* lower case letters, it is intended for demonstration purposes and
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* it serves no purpose other than to annoy the user...
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*/
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#include "config.h"
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#include <ctype.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <syslog.h>
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#include <sys/time.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include "pam_filter.h"
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#include <security/pam_modutil.h>
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/* ---------------------------------------------------------------- */
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static void do_transpose(char *buffer,int len)
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{
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int i;
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for (i=0; i<len; ++i) {
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if (islower(buffer[i])) {
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buffer[i] = toupper(buffer[i]);
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} else {
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buffer[i] = tolower(buffer[i]);
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}
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}
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}
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extern char **environ;
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int main(int argc, char **argv UNUSED)
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{
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char buffer[BUFSIZ];
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fd_set readers;
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void (*before_user)(char *,int);
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void (*before_app)(char *,int);
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openlog("upperLOWER", LOG_CONS|LOG_PID, LOG_AUTHPRIV);
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#ifdef DEBUG
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{
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int i;
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fprintf(stderr,"environment :[\r\n");
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for (i=0; environ[i]; ++i) {
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fprintf(stderr,"-> %s\r\n",environ[i]);
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}
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fprintf(stderr,"]: end\r\n");
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}
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#endif
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if (argc != 1) {
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#ifdef DEBUG
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fprintf(stderr,"filter invoked as conventional executable\n");
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#else
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syslog(LOG_ERR, "filter invoked as conventional executable");
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#endif
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exit(1);
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}
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before_user = before_app = do_transpose; /* assign filter functions */
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/* enter a loop that deals with the input and output of the
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user.. passing it to and from the application */
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FD_ZERO(&readers); /* initialize reading mask */
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for (;;) {
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FD_SET(APPOUT_FILENO, &readers); /* wake for output */
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FD_SET(APPERR_FILENO, &readers); /* wake for error */
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FD_SET(STDIN_FILENO, &readers); /* wake for input */
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if ( select(APPTOP_FILE,&readers,NULL,NULL,NULL) < 0 ) {
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#ifdef DEBUG
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fprintf(stderr,"select failed\n");
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#else
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syslog(LOG_WARNING,"select failed");
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#endif
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break;
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}
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/* application errors */
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if ( FD_ISSET(APPERR_FILENO,&readers) ) {
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int got = read(APPERR_FILENO, buffer, BUFSIZ);
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if (got <= 0) {
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break;
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} else {
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/* translate to give to real terminal */
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if (before_user != NULL)
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before_user(buffer, got);
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if (pam_modutil_write(STDERR_FILENO, buffer, got) != got ) {
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syslog(LOG_WARNING,"couldn't write %d bytes?!",got);
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break;
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}
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}
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} else if ( FD_ISSET(APPOUT_FILENO,&readers) ) { /* app output */
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int got = read(APPOUT_FILENO, buffer, BUFSIZ);
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if (got <= 0) {
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break;
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} else {
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/* translate to give to real terminal */
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if (before_user != NULL)
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before_user(buffer, got);
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if (pam_modutil_write(STDOUT_FILENO, buffer, got) != got ) {
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syslog(LOG_WARNING,"couldn't write %d bytes!?",got);
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break;
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}
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}
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}
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if ( FD_ISSET(STDIN_FILENO, &readers) ) { /* user input */
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int got = read(STDIN_FILENO, buffer, BUFSIZ);
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if (got < 0) {
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syslog(LOG_WARNING,"user input junked");
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break;
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} else if (got) {
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/* translate to give to application */
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if (before_app != NULL)
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before_app(buffer, got);
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if (pam_modutil_write(APPIN_FILENO, buffer, got) != got ) {
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syslog(LOG_WARNING,"couldn't pass %d bytes!?",got);
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break;
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}
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} else {
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/* nothing received -- an error? */
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syslog(LOG_WARNING,"user input null?");
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break;
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}
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}
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}
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exit(0);
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}
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