X-Git-Url: https://git.danieliu.xyz/?a=blobdiff_plain;f=slock.c;h=5051f04eb8a70a2fc7756fd29d6950850fb4236d;hb=44ce161c139f74cac80dd77aafdfadb49a85af2a;hp=154a0918bee1b272ddd911d2c3736d08ef2b99ca;hpb=d276b9b0e01ea086e48ea8327efa0f9ebddca621;p=slock.git

diff --git a/slock.c b/slock.c
index 154a091..5051f04 100644
--- a/slock.c
+++ b/slock.c
@@ -23,6 +23,8 @@
 #include <bsd_auth.h>
 #endif
 
+#include "config.h"
+
 typedef struct {
 	int screen;
 	Window root, win;
@@ -44,32 +46,51 @@ die(const char *errstr, ...) {
 	exit(EXIT_FAILURE);
 }
 
+#ifdef __linux__
+#include <fcntl.h>
+
+static void
+dontkillme(void) {
+	int fd;
+
+	fd = open("/proc/self/oom_score_adj", O_WRONLY);
+	if (fd < 0 && errno == ENOENT)
+		return;
+	if (fd < 0 || write(fd, "-1000\n", 6) != 6 || close(fd) != 0)
+		die("cannot disable the out-of-memory killer for this process\n");
+}
+#endif
+
 #ifndef HAVE_BSD_AUTH
 static const char *
 getpw(void) { /* only run as root */
 	const char *rval;
 	struct passwd *pw;
 
+	errno = 0;
 	pw = getpwuid(getuid());
-	if(!pw)
-		die("slock: cannot retrieve password entry (make sure to suid or sgid slock)");
-	endpwent();
+	if (!pw) {
+		if (errno)
+			die("slock: getpwuid: %s\n", strerror(errno));
+		else
+			die("slock: cannot retrieve password entry (make sure to suid or sgid slock)\n");
+	}
 	rval =  pw->pw_passwd;
 
 #if HAVE_SHADOW_H
-	if (strlen(rval) >= 1) { /* kludge, assumes pw placeholder entry has len >= 1 */
+	if (rval[0] == 'x' && rval[1] == '\0') {
 		struct spwd *sp;
 		sp = getspnam(getenv("USER"));
 		if(!sp)
 			die("slock: cannot retrieve shadow entry (make sure to suid or sgid slock)\n");
-		endspent();
 		rval = sp->sp_pwdp;
 	}
 #endif
 
 	/* drop privileges */
-	if(setgid(pw->pw_gid) < 0 || setuid(pw->pw_uid) < 0)
-		die("slock: cannot 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");
 	return rval;
 }
 #endif
@@ -114,9 +135,9 @@ readpw(Display *dpy, const char *pws)
 #ifdef HAVE_BSD_AUTH
 				running = !auth_userokay(getlogin(), NULL, "auth-xlock", passwd);
 #else
-				running = strcmp(crypt(passwd, pws), pws);
+				running = !!strcmp(crypt(passwd, pws), pws);
 #endif
-				if(running != False)
+				if(running)
 					XBell(dpy, 100);
 				len = 0;
 				break;
@@ -128,7 +149,7 @@ readpw(Display *dpy, const char *pws)
 					--len;
 				break;
 			default:
-				if(num && !iscntrl((int) buf[0]) && (len + num < sizeof passwd)) { 
+				if(num && !iscntrl((int) buf[0]) && (len + num < sizeof passwd)) {
 					memcpy(passwd + len, buf, num);
 					len += num;
 				}
@@ -244,20 +265,24 @@ main(int argc, char **argv) {
 	else if(argc != 1)
 		usage();
 
+#ifdef __linux__
+	dontkillme();
+#endif
+
 	if(!getpwuid(getuid()))
-		die("slock: no passwd entry for you");
+		die("slock: no passwd entry for you\n");
 
 #ifndef HAVE_BSD_AUTH
 	pws = getpw();
 #endif
 
 	if(!(dpy = XOpenDisplay(0)))
-		die("slock: cannot open display");
+		die("slock: cannot open display\n");
 	/* Get the number of screens in display "dpy" and blank them all. */
 	nscreens = ScreenCount(dpy);
 	locks = malloc(sizeof(Lock *) * nscreens);
 	if(locks == NULL)
-		die("slock: malloc: %s", strerror(errno));
+		die("slock: malloc: %s\n", strerror(errno));
 	int nlocks = 0;
 	for(screen = 0; screen < nscreens; screen++) {
 		if ( (locks[screen] = lockscreen(dpy, screen)) != NULL)