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Reapply "kernel: expose umount list to ioctl interface #2950"

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This reverts commit 088996da9b.
This commit is contained in:
ShirkNeko
2025-11-20 20:07:59 +08:00
parent cc78812f50
commit 8250c0ecc2
48 changed files with 257 additions and 271 deletions
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36
kernel/kernel_umount.c
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@@ -43,24 +43,6 @@ static const struct ksu_feature_handler kernel_umount_handler = {
.set_handler = kernel_umount_feature_set,
};
static bool should_umount(struct path *path)
{
if (!path) {
return false;
}
if (current->nsproxy->mnt_ns == init_nsproxy.mnt_ns) {
pr_info("ignore global mnt namespace process: %d\n", current_uid().val);
return false;
}
if (path->mnt && path->mnt->mnt_sb && path->mnt->mnt_sb->s_type) {
const char *fstype = path->mnt->mnt_sb->s_type->name;
return strcmp(fstype, "overlay") == 0;
}
return false;
}
extern int path_umount(struct path *path, int flags);
static void ksu_umount_mnt(struct path *path, int flags)
@@ -71,7 +53,7 @@ static void ksu_umount_mnt(struct path *path, int flags)
}
}
void try_umount(const char *mnt, bool check_mnt, int flags)
void try_umount(const char *mnt, int flags)
{
struct path path;
int err = kern_path(mnt, 0, &path);
@@ -85,12 +67,6 @@ void try_umount(const char *mnt, bool check_mnt, int flags)
return;
}
// we are only interest in some specific mounts
if (check_mnt && !should_umount(&path)) {
path_put(&path);
return;
}
ksu_umount_mnt(&path, flags);
}
@@ -107,8 +83,14 @@ static void umount_tw_func(struct callback_head *cb)
saved = override_creds(tw->old_cred);
}
// fixme: use `collect_mounts` and `iterate_mount` to iterate all mountpoint and
// filter the mountpoint whose target is `/data/adb`
struct mount_entry *entry;
down_read(&mount_list_lock);
list_for_each_entry(entry, &mount_list, list) {
pr_info("%s: unmounting: %s flags 0x%x\n", __func__, entry->umountable, entry->flags);
try_umount(entry->umountable, entry->flags);
}
up_read(&mount_list_lock);
ksu_umount_manager_execute_all(tw->old_cred);
if (saved)

15
kernel/kernel_umount.h
View File

@@ -2,13 +2,24 @@
#define __KSU_H_KERNEL_UMOUNT
#include <linux/types.h>
#include <linux/list.h>
#include <linux/rwsem.h>
void ksu_kernel_umount_init(void);
void ksu_kernel_umount_exit(void);
void try_umount(const char *mnt, bool check_mnt, int flags);
void try_umount(const char *mnt, int flags);
// Handler function to be called from setresuid hook
int ksu_handle_umount(uid_t old_uid, uid_t new_uid);
#endif
// for the umount list
struct mount_entry {
char *umountable;
unsigned int flags;
struct list_head list;
};
extern struct list_head mount_list;
extern struct rw_semaphore mount_list_lock;
#endif

109
kernel/supercalls.c
View File

@@ -18,6 +18,7 @@
#include "feature.h"
#include "klog.h" // IWYU pragma: keep
#include "ksud.h"
#include "kernel_umount.h"
#include "manager.h"
#include "selinux/selinux.h"
#include "objsec.h"
@@ -510,6 +511,111 @@ static int do_nuke_ext4_sysfs(void __user *arg)
return nuke_ext4_sysfs(mnt);
}
struct list_head mount_list = LIST_HEAD_INIT(mount_list);
DECLARE_RWSEM(mount_list_lock);
static int add_try_umount(void __user *arg)
{
struct mount_entry *new_entry, *entry, *tmp;
struct ksu_add_try_umount_cmd cmd;
char buf[256] = {0};
if (copy_from_user(&cmd, arg, sizeof cmd))
return -EFAULT;
switch (cmd.mode) {
case KSU_UMOUNT_WIPE: {
struct mount_entry *entry, *tmp;
down_write(&mount_list_lock);
list_for_each_entry_safe(entry, tmp, &mount_list, list) {
pr_info("wipe_umount_list: removing entry: %s\n", entry->umountable);
list_del(&entry->list);
kfree(entry->umountable);
kfree(entry);
}
up_write(&mount_list_lock);
return 0;
}
case KSU_UMOUNT_ADD: {
long len = strncpy_from_user(buf, (const char __user *)cmd.arg, 256);
if (len <= 0)
return -EFAULT;
buf[sizeof(buf) - 1] = '\0';
new_entry = kzalloc(sizeof(*new_entry), GFP_KERNEL);
if (!new_entry)
return -ENOMEM;
new_entry->umountable = kstrdup(buf, GFP_KERNEL);
if (!new_entry->umountable) {
kfree(new_entry);
return -1;
}
down_write(&mount_list_lock);
// disallow dupes
// if this gets too many, we can consider moving this whole task to a kthread
list_for_each_entry(entry, &mount_list, list) {
if (!strcmp(entry->umountable, buf)) {
pr_info("cmd_add_try_umount: %s is already here!\n", buf);
up_write(&mount_list_lock);
kfree(new_entry->umountable);
kfree(new_entry);
return -1;
}
}
// now check flags and add
// this also serves as a null check
if (cmd.flags)
new_entry->flags = cmd.flags;
else
new_entry->flags = 0;
// debug
list_add(&new_entry->list, &mount_list);
up_write(&mount_list_lock);
pr_info("cmd_add_try_umount: %s added!\n", buf);
return 0;
}
// this is just strcmp'd wipe anyway
case KSU_UMOUNT_DEL: {
long len = strncpy_from_user(buf, (const char __user *)cmd.arg, sizeof(buf) - 1);
if (len <= 0)
return -EFAULT;
buf[sizeof(buf) - 1] = '\0';
down_write(&mount_list_lock);
list_for_each_entry_safe(entry, tmp, &mount_list, list) {
if (!strcmp(entry->umountable, buf)) {
pr_info("cmd_add_try_umount: entry removed: %s\n", entry->umountable);
list_del(&entry->list);
kfree(entry->umountable);
kfree(entry);
}
}
up_write(&mount_list_lock);
return 0;
}
default: {
pr_err("cmd_add_try_umount: invalid operation %u\n", cmd.mode);
return -EINVAL;
}
} // switch(cmd.mode)
return 0;
}
// 100. GET_FULL_VERSION - Get full version string
static int do_get_full_version(void __user *arg)
{
@@ -721,7 +827,7 @@ static int do_umount_manager(void __user *arg)
switch (cmd.operation) {
case UMOUNT_OP_ADD: {
return ksu_umount_manager_add(cmd.path, cmd.check_mnt, cmd.flags, false);
return ksu_umount_manager_add(cmd.path, cmd.flags, false);
}
case UMOUNT_OP_REMOVE: {
return ksu_umount_manager_remove(cmd.path);
@@ -758,6 +864,7 @@ static const struct ksu_ioctl_cmd_map ksu_ioctl_handlers[] = {
{ .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_ADD_TRY_UMOUNT, .name = "ADD_TRY_UMOUNT", .handler = add_try_umount, .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},

20
kernel/supercalls.h
View File

@@ -89,15 +89,26 @@ 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
#define KSU_MARK_REFRESH 4
struct ksu_nuke_ext4_sysfs_cmd {
__aligned_u64 arg; // Input: mnt pointer
};
struct ksu_add_try_umount_cmd {
__aligned_u64 arg; // char ptr, this is the mountpoint
__u32 flags; // this is the flag we use for it
__u8 mode; // denotes what to do with it 0:wipe_list 1:add_to_list 2:delete_entry
};
#define KSU_UMOUNT_WIPE 0 // ignore everything and wipe list
#define KSU_UMOUNT_ADD 1 // add entry (path + flags)
#define KSU_UMOUNT_DEL 2 // delete entry, strcmp
// Other command structures
struct ksu_get_full_version_cmd {
char version_full[KSU_FULL_VERSION_STRING]; // Output: full version string
@@ -152,6 +163,7 @@ struct ksu_manual_su_cmd {
#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_WRITE, 'K', 17, 0)
#define KSU_IOCTL_ADD_TRY_UMOUNT _IOC(_IOC_WRITE, 'K', 18, 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)

24
kernel/umount_manager.c
View File

@@ -17,7 +17,7 @@ static struct umount_manager g_umount_mgr = {
static void try_umount_path(struct umount_entry *entry)
{
try_umount(entry->path, entry->check_mnt, entry->flags);
try_umount(entry->path, entry->flags);
}
static struct umount_entry *find_entry_locked(const char *path)
@@ -39,21 +39,19 @@ static int init_default_entries(void)
const struct {
const char *path;
bool check_mnt;
int flags;
} defaults[] = {
{ "/odm", true, 0 },
{ "/system", true, 0 },
{ "/vendor", true, 0 },
{ "/product", true, 0 },
{ "/system_ext", true, 0 },
{ "/data/adb/modules", false, MNT_DETACH },
{ "/debug_ramdisk", false, MNT_DETACH },
{ "/odm", 0 },
{ "/system", 0 },
{ "/vendor", 0 },
{ "/product", 0 },
{ "/system_ext", 0 },
{ "/data/adb/modules", MNT_DETACH },
{ "/debug_ramdisk", MNT_DETACH },
};
for (int i = 0; i < ARRAY_SIZE(defaults); i++) {
ret = ksu_umount_manager_add(defaults[i].path,
defaults[i].check_mnt,
ret = ksu_umount_manager_add(defaults[i].path,
defaults[i].flags,
true); // is_default = true
if (ret) {
@@ -93,7 +91,7 @@ void ksu_umount_manager_exit(void)
pr_info("Umount manager cleaned up\n");
}
int ksu_umount_manager_add(const char *path, bool check_mnt, int flags, bool is_default)
int ksu_umount_manager_add(const char *path, int flags, bool is_default)
{
struct umount_entry *entry;
unsigned long irqflags;
@@ -127,7 +125,6 @@ int ksu_umount_manager_add(const char *path, bool check_mnt, int flags, bool is_
}
strncpy(entry->path, path, sizeof(entry->path) - 1);
entry->check_mnt = check_mnt;
entry->flags = flags;
entry->state = UMOUNT_STATE_IDLE;
entry->is_default = is_default;
@@ -234,7 +231,6 @@ int ksu_umount_manager_get_entries(struct ksu_umount_entry_info __user *entries,
memset(&info, 0, sizeof(info));
strncpy(info.path, entry->path, sizeof(info.path) - 1);
info.check_mnt = entry->check_mnt;
info.flags = entry->flags;
info.is_default = entry->is_default;
info.state = entry->state;

5
kernel/umount_manager.h
View File

@@ -16,7 +16,6 @@ enum umount_entry_state {
struct umount_entry {
struct list_head list;
char path[256];
bool check_mnt;
int flags;
enum umount_entry_state state;
bool is_default;
@@ -40,7 +39,6 @@ enum umount_manager_op {
struct ksu_umount_manager_cmd {
__u32 operation;
char path[256];
__u8 check_mnt;
__s32 flags;
__u32 count;
__aligned_u64 entries_ptr;
@@ -48,7 +46,6 @@ struct ksu_umount_manager_cmd {
struct ksu_umount_entry_info {
char path[256];
__u8 check_mnt;
__s32 flags;
__u8 is_default;
__u32 state;
@@ -57,7 +54,7 @@ struct ksu_umount_entry_info {
int ksu_umount_manager_init(void);
void ksu_umount_manager_exit(void);
int ksu_umount_manager_add(const char *path, bool check_mnt, int flags, bool is_default);
int ksu_umount_manager_add(const char *path, int flags, bool is_default);
int ksu_umount_manager_remove(const char *path);
void ksu_umount_manager_execute_all(const struct cred *cred);
int ksu_umount_manager_get_entries(struct ksu_umount_entry_info __user *entries, u32 *count);