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/*
* Copyright (c) 2008 Red Hat, Inc. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License, version 2,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
*/
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
void alarm_handler(int num) {
return;
}
int open_and_lock_securetty() {
int fd;
struct flock lock;
struct sigaction act, oldact;
lock.l_type = F_WRLCK;
lock.l_whence = SEEK_SET;
lock.l_start = 0;
lock.l_len = 0;
fd = open("/etc/securetty", O_RDWR);
if (fd == -1) {
syslog(LOG_ERR, "Couldn't open /etc/securetty: %s",strerror(errno));
return -1;
}
act.sa_handler = alarm_handler;
act.sa_flags = 0;
sigaction(SIGALRM, &act, &oldact);
alarm(2);
while (fcntl(fd, F_SETLKW, &lock) == -1) {
if (errno == EINTR) {
syslog(LOG_ERR, "Couldn't lock /etc/securetty: Timeout exceeded");
} else {
syslog(LOG_ERR, "Couldn't lock /etc/securetty: %s",strerror(errno));
}
return -1;
}
alarm(0);
sigaction(SIGALRM, &oldact, NULL);
return fd;
}
int rewrite_securetty(char *terminal) {
int fd;
fd = open_and_lock_securetty();
if (fd == -1)
return 1;
if (lseek(fd, 0, SEEK_END) == -1) {
close(fd);
syslog(LOG_ERR, "Couldn't seek to end of /etc/securetty: %s",strerror(errno));
return 1;
}
write(fd, terminal, strlen(terminal));
write(fd, "\n", 1);
close(fd);
return 0;
}
int check_securetty(char *terminal) {
int fd, rc = 1;
char *buf, term[PATH_MAX];
struct stat sb;
fd = open("/etc/securetty", O_RDONLY);
if (fd == -1)
goto out;
fstat(fd, &sb);
buf = mmap(NULL, sb.st_size, PROT_READ, MAP_SHARED, fd, 0);
if (buf == ((caddr_t) -1)) {
close(fd);
return 1;
}
snprintf(term,PATH_MAX,"%s\n",terminal);
if (!strncmp(buf,term,strlen(term))) {
rc = 0;
goto out_unmap;
}
snprintf(term,PATH_MAX,"\n%s\n",terminal);
if (strstr(buf,term)) {
rc = 0;
goto out_unmap;
}
out_unmap:
munmap(buf, sb.st_size);
out:
close(fd);
return rc;
}
int main(int argc, char **argv) {
if (argc < 2 ) {
fprintf(stderr, "Usage: securetty <device>\n");
exit(1);
}
openlog("securetty", LOG_CONS, LOG_DAEMON);
if (check_securetty(argv[1]))
return rewrite_securetty(argv[1]);
else
return 0;
}
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