clear passwords with explicit_bzero

[slock.git] / slock.c

diff --git a/slock.c b/slock.c
index df2d3c6beb2fa2af394bab7202aa0bc5493436b7..a00fbb9a8f37bbca4d40b04ed40cba525d183781 100644 (file)
--- a/slock.c
+++ b/slock.c
@@ -23,6 +23,8 @@
 #include <bsd_auth.h>
 #endif
 
+#include "util.h"
+
 enum {
        INIT,
        INPUT,
@@ -52,6 +54,7 @@ die(const char *errstr, ...)
 {
        va_list ap;
 
+       fputs("slock: ", stderr);
        va_start(ap, errstr);
        vfprintf(stderr, errstr, ap);
        va_end(ap);
@@ -60,28 +63,20 @@ die(const char *errstr, ...)
 
 #ifdef __linux__
 #include <fcntl.h>
-#include <linux/oom.h>
 
 static void
 dontkillme(void)
 {
        int fd;
-       int length;
-       char value[64];
 
        fd = open("/proc/self/oom_score_adj", O_WRONLY);
-       if (fd < 0 && errno == ENOENT)
+       if (fd < 0 && errno == ENOENT) {
                return;
-
-       /* convert OOM_SCORE_ADJ_MIN to string for writing */
-       length = snprintf(value, sizeof(value), "%d\n", OOM_SCORE_ADJ_MIN);
-
-       /* bail on truncation */
-       if (length >= sizeof(value))
-               die("buffer too small\n");
-
-       if (fd < 0 || write(fd, value, length) != length || close(fd) != 0)
-               die("cannot disable the out-of-memory killer for this process\n");
+       }
+       if (fd < 0 || write(fd, "-1000\n", (sizeof("-1000\n") - 1)) !=
+           (sizeof("-1000\n") - 1) || close(fd) != 0) {
+               die("can't tame the oom-killer. is suid or sgid set?\n");
+       }
 }
 #endif
 
@@ -96,9 +91,9 @@ getpw(void)
        errno = 0;
        if (!(pw = getpwuid(getuid()))) {
                if (errno)
-                       die("slock: getpwuid: %s\n", strerror(errno));
+                       die("getpwuid: %s\n", strerror(errno));
                else
-                       die("slock: cannot retrieve password entry\n");
+                       die("cannot retrieve password entry\n");
        }
        rval = pw->pw_passwd;
 
@@ -106,7 +101,7 @@ getpw(void)
        if (rval[0] == 'x' && rval[1] == '\0') {
                struct spwd *sp;
                if (!(sp = getspnam(getenv("USER"))))
-                       die("slock: cannot retrieve shadow entry (make sure to suid or sgid slock)\n");
+                       die("cannot retrieve shadow entry (make sure to suid or sgid slock)\n");
                rval = sp->sp_pwdp;
        }
 #endif
@@ -114,7 +109,7 @@ getpw(void)
        /* drop privileges */
        if (geteuid() == 0 &&
            ((getegid() != pw->pw_gid && setgid(pw->pw_gid) < 0) || setuid(pw->pw_uid) < 0))
-               die("slock: cannot drop privileges\n");
+               die("cannot drop privileges\n");
        return rval;
 }
 #endif
@@ -142,7 +137,7 @@ readpw(Display *dpy, const char *pws)
         * timeout. */
        while (running && !XNextEvent(dpy, &ev)) {
                if (ev.type == KeyPress) {
-                       buf[0] = 0;
+                       explicit_bzero(&buf, sizeof(buf));
                        num = XLookupString(&ev.xkey, buf, sizeof(buf), &ksym, 0);
                        if (IsKeypadKey(ksym)) {
                                if (ksym == XK_KP_Enter)
@@ -168,14 +163,16 @@ readpw(Display *dpy, const char *pws)
                                        XBell(dpy, 100);
                                        failure = True;
                                }
+                               explicit_bzero(&passwd, sizeof(passwd));
                                len = 0;
                                break;
                        case XK_Escape:
+                               explicit_bzero(&passwd, sizeof(passwd));
                                len = 0;
                                break;
                        case XK_BackSpace:
                                if (len)
-                                       --len;
+                                       passwd[len--] = 0;
                                break;
                        default:
                                if (num && !iscntrl((int)buf[0]) && (len + num < sizeof(passwd))) {
@@ -295,10 +292,11 @@ main(int argc, char **argv) {
        Display *dpy;
        int screen;
 
-       if ((argc == 2) && !strcmp("-v", argv[1]))
-               die("slock-%s, © 2006-2015 slock engineers\n", VERSION);
+       if ((argc >= 2) && !strcmp("-v", argv[1]))
+               die("version %s, © 2006-2016 slock engineers\n", VERSION);
 
-       if ((argc == 2) && !strcmp("-h", argv[1]))
+       /* treat first argument starting with a '-' as option */
+       if ((argc >= 2) && argv[1][0] == '-')
                usage();
 
 #ifdef __linux__
@@ -306,19 +304,19 @@ main(int argc, char **argv) {
 #endif
 
        if (!getpwuid(getuid()))
-               die("slock: no passwd entry for you\n");
+               die("no passwd entry for you\n");
 
 #ifndef HAVE_BSD_AUTH
        pws = getpw();
 #endif
 
        if (!(dpy = XOpenDisplay(0)))
-               die("slock: cannot open display\n");
+               die("cannot open display\n");
        rr = XRRQueryExtension(dpy, &rrevbase, &rrerrbase);
        /* Get the number of screens in display "dpy" and blank them all. */
        nscreens = ScreenCount(dpy);
        if (!(locks = malloc(sizeof(Lock*) * nscreens)))
-               die("slock: malloc: %s\n", strerror(errno));
+               die("Out of memory.\n");
        int nlocks = 0;
        for (screen = 0; screen < nscreens; screen++) {
                if ((locks[screen] = lockscreen(dpy, screen)) != NULL)
@@ -337,7 +335,7 @@ main(int argc, char **argv) {
                if (dpy)
                        close(ConnectionNumber(dpy));
                execvp(argv[1], argv+1);
-               die("slock: execvp %s failed: %s\n", argv[1], strerror(errno));
+               die("execvp %s failed: %s\n", argv[1], strerror(errno));
        }
 
        /* Everything is now blank. Now wait for the correct password. */