1 files changed, 94 insertions, 0 deletions
diff --git a/src/securetty.c b/src/securetty.c
new file mode 100644
index 00000000..f1505076
--- /dev/null
+++ b/src/securetty.c
@@ -0,0 +1,94 @@
+
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <syslog.h>
+#include <unistd.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;
+        char *buf, *pos;
+        struct stat sbuf;
+        
+        fd = open_and_lock_securetty();
+        if (fd == -1)
+                return 1;
+        if (fstat(fd, &sbuf) == -1) {
+                close(fd);
+                syslog(LOG_ERR, "Couldn't stat /etc/securetty: %s",strerror(errno));
+                return 1;
+        }
+        buf = malloc(sbuf.st_size + 1);
+        if (read(fd, buf, sbuf.st_size) != sbuf.st_size) {
+                close(fd);
+                syslog(LOG_ERR, "Couldn't read /etc/securetty: %s",strerror(errno));
+                return 1;
+        }
+        if (!strncmp(buf,terminal,strlen(terminal)) && buf[strlen(terminal)] == '\n')
+                goto out_ok;
+        if ((pos = strstr(buf, terminal))) {
+                if (pos[strlen(terminal)] == '\n' && *(pos-1) == '\n')
+                        goto out_ok;
+        }
+        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);
+out_ok:
+        close(fd);
+        return 0;
+}
+
+int main(int argc, char **argv) {
+        if (argc < 2 ) {
+                fprintf(stderr, "Usage: securetty <device>\n");
+                exit(1);
+        }
+        openlog("securetty", LOG_CONS, LOG_DAEMON);
+        return rewrite_securetty(argv[1]);
+}