Magisk/jni/magiskhide/hide.c

#include "magiskhide.h"

int hideMagisk() {
	close(pipefd[1]);
	
	int pid, fd;
	char cache_block[256];
	cache_block[0] = '\0';

	while(1) {
		read(pipefd[0], &pid, sizeof(pid));
		// Termination called
		if(pid == -1) break;

		manage_selinux();

		snprintf(buffer, sizeof(buffer), "/proc/%d/ns/mnt", pid);
		if((fd = open(buffer, O_RDONLY)) == -1) continue; // Maybe process died..
		if(setns(fd, 0) == -1) {
			fprintf(logfile, "MagiskHide: Unable to change namespace for pid=%d\n", pid);
			continue;
		}
		close(fd);

		snprintf(buffer, sizeof(buffer), "/proc/%d/mounts", pid);
		FILE *mount_fp = fopen(buffer, "r");
		if (mount_fp == NULL) {
			fprintf(logfile, "MagiskHide: Error opening mount list!\n");
			continue;
		}

		int mount_size;
		char **mount_list = file_to_str_arr(mount_fp, &mount_size);

		// Find the cache block name if not found yet
		if (strlen(cache_block) == 0) {
			for(i = 0; i < mount_size; ++i) {
				if (strstr(mount_list[i], " /cache ")) {
					sscanf(mount_list[i], "%256s", cache_block);
					break;
				}
			}
		}
		
		// First unmount the dummy skeletons, cache mounts, and /sbin links
		for(i = mount_size - 1; i >= 0; --i) {
			if (strstr(mount_list[i], "tmpfs /system") || strstr(mount_list[i], "tmpfs /vendor")
				|| strstr(mount_list[i], "tmpfs /sbin")
				|| (strstr(mount_list[i], cache_block) && strstr(mount_list[i], "/system/")) ) {
				sscanf(mount_list[i], "%*s %512s", buffer);
				lazy_unmount(buffer);
			}
			free(mount_list[i]);
		}
		free(mount_list);

		// Re-read mount infos
		fseek(mount_fp, 0, SEEK_SET);
		mount_list = file_to_str_arr(mount_fp, &mount_size);
		fclose(mount_fp);

		// Unmount loop mounts
		for(i = mount_size - 1; i >= 0; --i) {
			if (strstr(mount_list[i], "/dev/block/loop") && !strstr(mount_list[i], DUMMYPATH)) {
				sscanf(mount_list[i], "%*s %512s", buffer);
				lazy_unmount(buffer);
			}
			free(mount_list[i]);
		}
		free(mount_list);

		// Send resume signal
		kill(pid, SIGCONT);
	}

	// Should never go here
	return 1;
}