Implement revert_unmount_magisk

loader/src/injector/files.cpp

@@ -0,0 +1,122 @@
+#include <sys/sysmacros.h>
+
+#include "files.hpp"
+#include "misc.hpp"
+
+using namespace std::string_view_literals;
+
+void file_readline(bool trim, FILE *fp, const std::function<bool(std::string_view)> &fn) {
+    size_t len = 1024;
+    char *buf = (char *) malloc(len);
+    char *start;
+    ssize_t read;
+    while ((read = getline(&buf, &len, fp)) >= 0) {
+        start = buf;
+        if (trim) {
+            while (read && "\n\r "sv.find(buf[read - 1]) != std::string::npos)
+                --read;
+            buf[read] = '\0';
+            while (*start == ' ')
+                ++start;
+        }
+        if (!fn(start))
+            break;
+    }
+    free(buf);
+}
+
+void file_readline(bool trim, const char *file, const std::function<bool(std::string_view)> &fn) {
+    if (auto fp = open_file(file, "re"))
+        file_readline(trim, fp.get(), fn);
+}
+void file_readline(const char *file, const std::function<bool(std::string_view)> &fn) {
+    file_readline(false, file, fn);
+}
+
+std::vector<mount_info> parse_mount_info(const char *pid) {
+    char buf[PATH_MAX] = {};
+    snprintf(buf, sizeof(buf), "/proc/%s/mountinfo", pid);
+    std::vector<mount_info> result;
+
+    file_readline(buf, [&result](std::string_view line) -> bool {
+        int root_start = 0, root_end = 0;
+        int target_start = 0, target_end = 0;
+        int vfs_option_start = 0, vfs_option_end = 0;
+        int type_start = 0, type_end = 0;
+        int source_start = 0, source_end = 0;
+        int fs_option_start = 0, fs_option_end = 0;
+        int optional_start = 0, optional_end = 0;
+        unsigned int id, parent, maj, min;
+        sscanf(line.data(),
+               "%u "           // (1) id
+               "%u "           // (2) parent
+               "%u:%u "        // (3) maj:min
+               "%n%*s%n "      // (4) mountroot
+               "%n%*s%n "      // (5) target
+               "%n%*s%n"       // (6) vfs options (fs-independent)
+               "%n%*[^-]%n - " // (7) optional fields
+               "%n%*s%n "      // (8) FS type
+               "%n%*s%n "      // (9) source
+               "%n%*s%n",      // (10) fs options (fs specific)
+               &id, &parent, &maj, &min, &root_start, &root_end, &target_start,
+               &target_end, &vfs_option_start, &vfs_option_end,
+               &optional_start, &optional_end, &type_start, &type_end,
+               &source_start, &source_end, &fs_option_start, &fs_option_end);
+
+        auto root = line.substr(root_start, root_end - root_start);
+        auto target = line.substr(target_start, target_end - target_start);
+        auto vfs_option =
+                line.substr(vfs_option_start, vfs_option_end - vfs_option_start);
+        ++optional_start;
+        --optional_end;
+        auto optional = line.substr(
+                optional_start,
+                optional_end - optional_start > 0 ? optional_end - optional_start : 0);
+
+        auto type = line.substr(type_start, type_end - type_start);
+        auto source = line.substr(source_start, source_end - source_start);
+        auto fs_option =
+                line.substr(fs_option_start, fs_option_end - fs_option_start);
+
+        unsigned int shared = 0;
+        unsigned int master = 0;
+        unsigned int propagate_from = 0;
+        if (auto pos = optional.find("shared:"); pos != std::string_view::npos) {
+            shared = parse_int(optional.substr(pos + 7));
+        }
+        if (auto pos = optional.find("master:"); pos != std::string_view::npos) {
+            master = parse_int(optional.substr(pos + 7));
+        }
+        if (auto pos = optional.find("propagate_from:");
+                pos != std::string_view::npos) {
+            propagate_from = parse_int(optional.substr(pos + 15));
+        }
+
+        result.emplace_back(mount_info {
+                .id = id,
+                .parent = parent,
+                .device = static_cast<dev_t>(makedev(maj, min)),
+                .root {root},
+                .target {target},
+                .vfs_option {vfs_option},
+                .optional {
+                        .shared = shared,
+                        .master = master,
+                        .propagate_from = propagate_from,
+                },
+                .type {type},
+                .source {source},
+                .fs_option {fs_option},
+        });
+        return true;
+    });
+    return result;
+}
+
+sDIR make_dir(DIR *dp) {
+    return sDIR(dp, [](DIR *dp){ return dp ? closedir(dp) : 1; });
+}
+
+sFILE make_file(FILE *fp) {
+    return sFILE(fp, [](FILE *fp){ return fp ? fclose(fp) : 1; });
+}

loader/src/injector/files.hpp

@@ -0,0 +1,56 @@
+#include <dirent.h>
+#include <functional>
+#include <string>
+#include <vector>
+
+struct mount_info {
+    unsigned int id;
+    unsigned int parent;
+    dev_t device;
+    std::string root;
+    std::string target;
+    std::string vfs_option;
+    struct {
+        unsigned int shared;
+        unsigned int master;
+        unsigned int propagate_from;
+    } optional;
+    std::string type;
+    std::string source;
+    std::string fs_option;
+};
+
+void file_readline(bool trim, FILE *fp, const std::function<bool(std::string_view)> &fn);
+void file_readline(bool trim, const char *file, const std::function<bool(std::string_view)> &fn);
+void file_readline(const char *file, const std::function<bool(std::string_view)> &fn);
+
+std::vector<mount_info> parse_mount_info(const char *pid);
+
+using sFILE = std::unique_ptr<FILE, decltype(&fclose)>;
+using sDIR = std::unique_ptr<DIR, decltype(&closedir)>;
+sDIR make_dir(DIR *dp);
+sFILE make_file(FILE *fp);
+
+static inline sDIR open_dir(const char *path) {
+    return make_dir(opendir(path));
+}
+
+static inline sDIR xopen_dir(const char *path) {
+    return make_dir(opendir(path));
+}
+
+static inline sDIR xopen_dir(int dirfd) {
+    return make_dir(fdopendir(dirfd));
+}
+
+static inline sFILE open_file(const char *path, const char *mode) {
+    return make_file(fopen(path, mode));
+}
+
+static inline sFILE xopen_file(const char *path, const char *mode) {
+    return make_file(fopen(path, mode));
+}
+
+static inline sFILE xopen_file(int fd, const char *mode) {
+    return make_file(fdopen(fd, mode));
+}

loader/src/injector/hook.cpp

@@ -17,7 +17,7 @@
 #include "zygisk.hpp"
 #include "memory.hpp"
 #include "module.hpp"
-#include "misc.hpp"
+#include "files.hpp"
 
 using namespace std;
 using jni_hook::hash_map;
@@ -219,7 +219,11 @@ DCL_HOOK_FUNC(int, unshare, int flags) {
         // Simply avoid doing any unmounts for SysUI to avoid potential issues.
         (g_ctx->info_flags & PROCESS_IS_SYS_UI) == 0) {
         if (g_ctx->flags[DO_REVERT_UNMOUNT]) {
-            revert_unmount();
+            if (g_ctx->info_flags & PROCESS_ROOT_IS_KSU) {
+                revert_unmount_ksu();
+            } else if (g_ctx->info_flags & PROCESS_ROOT_IS_MAGISK) {
+                revert_unmount_magisk();
+            }
         }
 
         /* Zygisksu changed: No umount app_process */

loader/src/injector/misc.cpp

@@ -23,17 +23,6 @@ int parse_int(std::string_view s) {
     return val;
 }
 
-void parse_mnt(const char* file, const std::function<void(mntent*)>& fn) {
-    auto fp = sFILE(setmntent(file, "re"), endmntent);
-    if (fp) {
-        mntent mentry{};
-        char buf[PATH_MAX];
-        while (getmntent_r(fp.get(), &mentry, buf, sizeof(buf))) {
-            fn(&mentry);
-        }
-    }
-}
-
 std::list<std::string> split_str(std::string_view s, std::string_view delimiter) {
     std::list<std::string> ret;
     size_t pos = 0;
@@ -58,11 +47,3 @@ std::string join_str(const std::list<std::string>& list, std::string_view delimi
     }
     return ret;
 }
-
-sDIR make_dir(DIR *dp) {
-    return sDIR(dp, [](DIR *dp){ return dp ? closedir(dp) : 1; });
-}
-
-sFILE make_file(FILE *fp) {
-    return sFILE(fp, [](FILE *fp){ return fp ? fclose(fp) : 1; });
-}

loader/src/injector/misc.hpp

@@ -1,12 +1,8 @@
 #pragma once
 
-#include <dirent.h>
-#include <functional>
 #include <list>
 #include <memory>
-#include <mntent.h>
 #include <pthread.h>
-#include <stdio.h>
 #include <string>
 #include <string_view>
 
@@ -39,12 +35,6 @@ int new_daemon_thread(thread_entry entry, void *arg);
 static inline bool str_contains(std::string_view s, std::string_view ss) {
     return s.find(ss) != std::string_view::npos;
 }
-static inline bool str_starts(std::string_view s, std::string_view ss) {
-    return s.size() >= ss.size() && s.compare(0, ss.size(), ss) == 0;
-}
-static inline bool str_ends(std::string_view s, std::string_view ss) {
-    return s.size() >= ss.size() && s.compare(s.size() - ss.size(), std::string_view::npos, ss) == 0;
-}
 
 template<typename T, typename Impl>
 class stateless_allocator {
@@ -61,35 +51,6 @@ public:
     bool operator!=(const stateless_allocator&) { return false; }
 };
 
-using sFILE = std::unique_ptr<FILE, decltype(&fclose)>;
-using sDIR = std::unique_ptr<DIR, decltype(&closedir)>;
-sDIR make_dir(DIR *dp);
-sFILE make_file(FILE *fp);
-
-static inline sDIR open_dir(const char *path) {
-    return make_dir(opendir(path));
-}
-
-static inline sDIR xopen_dir(const char *path) {
-    return make_dir(opendir(path));
-}
-
-static inline sDIR xopen_dir(int dirfd) {
-    return make_dir(fdopendir(dirfd));
-}
-
-static inline sFILE open_file(const char *path, const char *mode) {
-    return make_file(fopen(path, mode));
-}
-
-static inline sFILE xopen_file(const char *path, const char *mode) {
-    return make_file(fopen(path, mode));
-}
-
-static inline sFILE xopen_file(int fd, const char *mode) {
-    return make_file(fdopen(fd, mode));
-}
-
 template <typename T>
 class reversed_container {
 public:
@@ -126,8 +87,6 @@ struct StringCmp {
  */
 int parse_int(std::string_view s);
 
-void parse_mnt(const char* file, const std::function<void(mntent*)>& fn);
-
 std::list<std::string> split_str(std::string_view s, std::string_view delimiter);
 
 std::string join_str(const std::list<std::string>& list, std::string_view delimiter);

loader/src/injector/module.hpp

@@ -111,6 +111,8 @@ namespace {
         PROCESS_GRANTED_ROOT = zygisk::StateFlag::PROCESS_GRANTED_ROOT,
         PROCESS_ON_DENYLIST = zygisk::StateFlag::PROCESS_ON_DENYLIST,
 
+        PROCESS_ROOT_IS_KSU = (1u << 29),
+        PROCESS_ROOT_IS_MAGISK = (1u << 30),
         PROCESS_IS_SYS_UI = (1u << 31),
 
         PRIVATE_MASK = PROCESS_IS_SYS_UI

loader/src/injector/unmount.cpp

@@ -1,5 +1,7 @@
+#include <mntent.h>
 #include <sys/mount.h>
 
+#include "files.hpp"
 #include "logging.h"
 #include "misc.hpp"
 #include "zygisk.hpp"
@@ -7,7 +9,13 @@
 using namespace std::string_view_literals;
 
 namespace {
-    constexpr auto KSU_MODULE_DIR = "/data/adb/ksu/modules"sv;
+    constexpr auto KSU_MODULE_DIR = "/data/adb/ksu/modules";
+
+    struct overlay_backup {
+        std::string target;
+        std::string vfs_option;
+        std::string fs_option;
+    };
 
     void lazy_unmount(const char* mountpoint) {
         if (umount2(mountpoint, MNT_DETACH) != -1) {
@@ -24,37 +32,44 @@ namespace {
         return true;            \
     }
 
-void revert_unmount() {
+void revert_unmount_ksu() {
     std::string ksu_loop;
     std::vector<std::string> targets;
-    std::list<std::pair<std::string, std::string>> backups;
+    std::list<overlay_backup> backups;
 
     // Unmount ksu module dir last
     targets.emplace_back(KSU_MODULE_DIR);
-    parse_mnt("/proc/self/mounts", [&](mntent* mentry) {
-        if (mentry->mnt_dir == KSU_MODULE_DIR) {
-            ksu_loop = mentry->mnt_fsname;
-            return;
+
+    for (auto& info: parse_mount_info("self")) {
+        if (info.target == KSU_MODULE_DIR) {
+            ksu_loop = info.source;
+            continue;
         }
         // Unmount everything on /data/adb except ksu module dir
-        if (str_starts(mentry->mnt_dir, "/data/adb")) {
-            targets.emplace_back(mentry->mnt_dir);
+        if (info.target.starts_with("/data/adb")) {
+            targets.emplace_back(info.target);
         }
         // Unmount ksu overlays
-        if (mentry->mnt_type == "overlay"sv) {
-            if (str_contains(mentry->mnt_opts, KSU_MODULE_DIR)) {
-                targets.emplace_back(mentry->mnt_dir);
+        if (info.type == "overlay") {
+            LOGV("Overlay: %s (%s)", info.target.data(), info.fs_option.data());
+            if (str_contains(info.fs_option, KSU_MODULE_DIR)) {
+                targets.emplace_back(info.target);
             } else {
-                backups.emplace_back(mentry->mnt_dir, mentry->mnt_opts);
+                auto backup = overlay_backup{
+                        .target = info.target,
+                        .vfs_option = info.vfs_option,
+                        .fs_option = info.fs_option,
+                };
+                backups.emplace_back(backup);
             }
         }
-    });
-    // Unmount everything from ksu loop except ksu module dir
-    parse_mnt("/proc/self/mounts", [&](mntent* mentry) {
-        if (mentry->mnt_fsname == ksu_loop && mentry->mnt_dir != KSU_MODULE_DIR) {
-            targets.emplace_back(mentry->mnt_dir);
+    }
+    for (auto& info: parse_mount_info("self")) {
+        // Unmount everything from ksu loop except ksu module dir
+        if (info.source == ksu_loop && info.target != KSU_MODULE_DIR) {
+            targets.emplace_back(info.target);
         }
-    });
+    }
 
     // Do unmount
     for (auto& s: reversed(targets)) {
@@ -62,18 +77,18 @@ void revert_unmount() {
     }
 
     // Affirm unmounted system overlays
-    parse_mnt("/proc/self/mounts", [&](mntent* mentry) {
-        if (mentry->mnt_type == "overlay"sv) {
-            backups.remove_if([&](auto& mnt) {
-                return mnt.first == mentry->mnt_dir && mnt.second == mentry->mnt_opts;
+    for (auto& info: parse_mount_info("self")) {
+        if (info.type == "overlay") {
+            backups.remove_if([&](overlay_backup& mnt) {
+                return mnt.target == info.target && mnt.fs_option == info.fs_option;
             });
         }
-        return true;
-    });
+    }
 
     // Restore system overlays
     for (auto& mnt: backups) {
-        auto opts = split_str(mnt.second, ",");
+        auto opts = split_str(mnt.vfs_option, ",");
+        opts.splice(opts.end(), split_str(mnt.fs_option, ","));
         unsigned long flags = 0;
         opts.remove_if([&](auto& opt) {
             PARSE_OPT(MNTOPT_RO, MS_RDONLY)
@@ -82,10 +97,27 @@ void revert_unmount() {
             return false;
         });
         auto mnt_data = join_str(opts, ",");
-        if (mount("overlay", mnt.first.data(), "overlay", flags, mnt_data.data()) != -1) {
-            LOGD("Remounted (%s)", mnt.first.data());
+        if (mount("overlay", mnt.target.data(), "overlay", flags, mnt_data.data()) != -1) {
+            LOGD("Remounted (%s)", mnt.target.data());
         } else {
-            PLOGE("Remount (%s, %s)", mnt.first.data(), mnt_data.data());
+            PLOGE("Remount (%s, %s)", mnt.target.data(), mnt.fs_option.data());
         }
     }
 }
+
+void revert_unmount_magisk() {
+    std::vector<std::string> targets;
+
+    // Unmount dummy skeletons and MAGISKTMP
+    // since mirror nodes are always mounted under skeleton, we don't have to specifically unmount
+    for (auto& info: parse_mount_info("self")) {
+        if (info.source == "magisk" || info.source == "worker" || // magisktmp tmpfs
+            info.root.starts_with("/adb/modules")) { // bind mount from data partition
+            targets.push_back(info.target);
+        }
+    }
+
+    for (auto& s: targets) {
+        lazy_unmount(s.data());
+    }
+}

loader/src/injector/zygisk.hpp

@@ -8,4 +8,7 @@ extern void *self_handle;
 
 void hook_functions();
 
-void revert_unmount();
+void revert_unmount_ksu();
+
+void revert_unmount_magisk();
+

zygiskd/src/constants.rs

@@ -51,4 +51,6 @@ pub enum DaemonSocketAction {
 // Zygisk process flags
 pub const PROCESS_GRANTED_ROOT: u32 = 1 << 0;
 pub const PROCESS_ON_DENYLIST: u32 = 1 << 1;
+pub const PROCESS_ROOT_IS_KSU: u32 = 1 << 29;
+pub const PROCESS_ROOT_IS_MAGISK: u32 = 1 << 30;
 pub const PROCESS_IS_SYSUI: u32 = 1 << 31;

zygiskd/src/zygiskd.rs

@@ -201,6 +201,11 @@ fn handle_daemon_action(mut stream: UnixStream, context: &Context) -> Result<()>
             if root_impl::uid_on_denylist(uid) {
                 flags |= constants::PROCESS_ON_DENYLIST;
             }
+            match root_impl::get_impl() {
+                root_impl::RootImpl::KernelSU => flags |= constants::PROCESS_ROOT_IS_KSU,
+                root_impl::RootImpl::Magisk => flags |= constants::PROCESS_ROOT_IS_MAGISK,
+                _ => ()
+            }
             // TODO: PROCESS_IS_SYSUI?
             stream.write_u32(flags)?;
         }