Add mount namespace mode

jni/magiskhide/hide_daemon.c

@@ -56,7 +56,6 @@ int hide_daemon() {
 	// When an error occurs, report its failure to main process
 	err_handler = hide_daemon_err;
 	
-	int fd;
 	char buffer[4096], cache_block[256], *line;
 	struct vector mount_list;
 	
@@ -73,13 +72,8 @@ int hide_daemon() {
 		manage_selinux();
 		relink_sbin();
 
-		snprintf(buffer, sizeof(buffer), "/proc/%d/ns/mnt", pid);
+		if (switch_mnt_ns(pid))
-		if(access(buffer, F_OK) == -1) continue; // Maybe process died..
+			continue;
-
-		fd = xopen(buffer, O_RDONLY);
-		// Switch to its namespace
-		xsetns(fd, 0);
-		close(fd);
 
 		snprintf(buffer, sizeof(buffer), "/proc/%d/mounts", pid);
 		vec_init(&mount_list);

jni/utils/misc.c

@@ -1,6 +1,7 @@
 /* misc.c - Store all functions that are unable to be catagorized clearly
  */
 
+#define _GNU_SOURCE
 #include <string.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -10,6 +11,7 @@
 #include <pwd.h>
 #include <signal.h>
 #include <errno.h>
+#include <sched.h>
 #include <sys/types.h>
 #include <sys/ioctl.h>
 #include <sys/mount.h>
@@ -457,3 +459,17 @@ int resize_img(const char *img, int size) {
 	snprintf(buffer, PATH_MAX, "e2fsck -yf %s; resize2fs %s %dM;", img, img, size);
 	return system(buffer);
 }
+
+int switch_mnt_ns(int pid) {
+	char mnt[32];
+	snprintf(mnt, sizeof(mnt), "/proc/%d/ns/mnt", pid);
+	if(access(mnt, R_OK) == -1) return 1; // Maybe process died..
+
+	int fd, ret;
+	fd = xopen(mnt, O_RDONLY);
+	if (fd < 0) return 1;
+	// Switch to its namespace
+	ret = setns(fd, 0);
+	close(fd);
+	return ret;
+}

jni/utils/utils.h

@@ -94,5 +94,6 @@ void get_client_cred(int fd, struct ucred *cred);
 int create_img(const char *img, int size);
 int get_img_size(const char *img, int *used, int *total);
 int resize_img(const char *img, int size);
+int switch_mnt_ns(int pid);
 
 #endif