kernel: Add nuke_ext4_sysfs interface

kernel/ksud.c

@@ -103,14 +103,14 @@ void on_post_fs_data(void)
 }
 
 extern void ext4_unregister_sysfs(struct super_block *sb);
-static void nuke_ext4_sysfs(void)
+int nuke_ext4_sysfs(const char* mnt)
 {
 #ifdef CONFIG_EXT4_FS
     struct path path;
-    int err = kern_path("/data/adb/modules", 0, &path);
+    int err = kern_path(mnt, 0, &path);
     if (err) {
         pr_err("nuke path err: %d\n", err);
-        return;
+        return err;
     }
 
     struct super_block *sb = path.dentry->d_inode->i_sb;
@@ -118,18 +118,19 @@ static void nuke_ext4_sysfs(void)
     if (strcmp(name, "ext4") != 0) {
         pr_info("nuke but module aren't mounted\n");
         path_put(&path);
-        return;
+        return -EINVAL;
     }
 
     ext4_unregister_sysfs(sb);
     path_put(&path);
+
+    return 0;
 #endif
 }
 
 void on_module_mounted(void){
     pr_info("on_module_mounted!\n");
     ksu_module_mounted = true;
-    nuke_ext4_sysfs();
 }
 
 void on_boot_completed(void){

kernel/ksud.h

@@ -14,6 +14,8 @@ void on_boot_completed(void);
 
 bool ksu_is_safe_mode(void);
 
+int nuke_ext4_sysfs(const char* mnt);
+
 extern u32 ksu_file_sid;
 extern bool ksu_module_mounted;
 extern bool ksu_boot_completed;

kernel/supercalls.c

@@ -1,5 +1,3 @@
-#include "supercalls.h"
-
 #include <linux/anon_inodes.h>
 #include <linux/capability.h>
 #include <linux/cred.h>
@@ -14,6 +12,7 @@
 #include <linux/uaccess.h>
 #include <linux/version.h>
 
+#include "supercalls.h"
 #include "arch.h"
 #include "allowlist.h"
 #include "feature.h"
@@ -564,6 +563,36 @@ static int do_manage_mark(void __user *arg)
     return 0;
 }
 
+static int do_nuke_ext4_sysfs(void __user *arg)
+{
+    struct ksu_nuke_ext4_sysfs_cmd cmd;
+    char mnt[256];
+    long ret;
+
+    if (copy_from_user(&cmd, arg, sizeof(cmd)))
+        return -EFAULT;
+
+    if (!cmd.arg)
+        return -EINVAL;
+
+    memset(mnt, 0, sizeof(mnt));
+
+    ret = strncpy_from_user(mnt, cmd.arg, sizeof(mnt));
+    if (ret < 0) {
+        pr_err("nuke ext4 copy mnt failed: %ld\\n", ret);
+        return -EFAULT;   // 或者 return ret;
+    }
+
+    if (ret == sizeof(mnt)) {
+        pr_err("nuke ext4 mnt path too long\\n");
+        return -ENAMETOOLONG;
+    }
+
+    pr_info("do_nuke_ext4_sysfs: %s\n", mnt);
+
+    return nuke_ext4_sysfs(mnt);
+}
+
 // 100. GET_FULL_VERSION - Get full version string
 static int do_get_full_version(void __user *arg)
 {
@@ -784,6 +813,7 @@ static const struct ksu_ioctl_cmd_map ksu_ioctl_handlers[] = {
     { .cmd = KSU_IOCTL_SET_FEATURE, .name = "SET_FEATURE", .handler = do_set_feature, .perm_check = manager_or_root },
     { .cmd = KSU_IOCTL_GET_WRAPPER_FD, .name = "GET_WRAPPER_FD", .handler = do_get_wrapper_fd, .perm_check = manager_or_root },
     { .cmd = KSU_IOCTL_MANAGE_MARK, .name = "MANAGE_MARK", .handler = do_manage_mark, .perm_check = manager_or_root },
+    { .cmd = KSU_IOCTL_NUKE_EXT4_SYSFS, .name = "NUKE_EXT4_SYSFS", .handler = do_nuke_ext4_sysfs, .perm_check = manager_or_root },
     { .cmd = KSU_IOCTL_GET_FULL_VERSION,.name = "GET_FULL_VERSION", .handler = do_get_full_version, .perm_check = always_allow},
     { .cmd = KSU_IOCTL_HOOK_TYPE,.name = "GET_HOOK_TYPE", .handler = do_get_hook_type, .perm_check = manager_or_root},
     { .cmd = KSU_IOCTL_ENABLE_KPM, .name = "GET_ENABLE_KPM", .handler = do_enable_kpm, .perm_check = manager_or_root},

kernel/supercalls.h

@@ -89,6 +89,10 @@ struct ksu_manage_mark_cmd {
     __u32 result; // Output: for get operation - mark status or reg_count
 };
 
+struct ksu_nuke_ext4_sysfs_cmd {
+    __aligned_u64 arg; // Input: mnt pointer
+};
+
 #define KSU_MARK_GET 1
 #define KSU_MARK_MARK 2
 #define KSU_MARK_UNMARK 3
@@ -147,6 +151,7 @@ struct ksu_manual_su_cmd {
 #define KSU_IOCTL_SET_FEATURE _IOC(_IOC_WRITE, 'K', 14, 0)
 #define KSU_IOCTL_GET_WRAPPER_FD _IOC(_IOC_WRITE, 'K', 15, 0)
 #define KSU_IOCTL_MANAGE_MARK _IOC(_IOC_READ|_IOC_WRITE, 'K', 16, 0)
+#define KSU_IOCTL_NUKE_EXT4_SYSFS _IOC(_IOC_READ|_IOC_WRITE, 'K', 17, 0)
 // Other IOCTL command definitions
 #define KSU_IOCTL_GET_FULL_VERSION _IOC(_IOC_READ, 'K', 100, 0)
 #define KSU_IOCTL_HOOK_TYPE _IOC(_IOC_READ, 'K', 101, 0)