adb/daemon/remount_service.cpp - android-core - Git at Google

 /*
  * Copyright (C) 2008 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #define TRACE_TAG ADB

 #include "sysdeps.h"

 #include <errno.h>
 #include <fcntl.h>
 #include <mntent.h>
 #include <spawn.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/mount.h>
 #include <sys/statvfs.h>
 #include <sys/vfs.h>
 #include <unistd.h>

 #include <memory>
 #include <set>
 #include <string>
 #include <vector>

 #include <android-base/properties.h>
 #include <bootloader_message/bootloader_message.h>
 #include <cutils/android_reboot.h>
 #include <fs_mgr.h>
 #include <fs_mgr_overlayfs.h>

 #include "adb.h"
 #include "adb_io.h"
 #include "adb_unique_fd.h"
 #include "adb_utils.h"
 #include "set_verity_enable_state_service.h"

 // Returns the last device used to mount a directory in /proc/mounts.
 // This will find overlayfs entry where upperdir=lowerdir, to make sure
 // remount is associated with the correct directory.
 static std::string find_proc_mount(const char* dir) {
     std::unique_ptr<FILE, int(*)(FILE*)> fp(setmntent("/proc/mounts", "r"), endmntent);
     std::string mnt_fsname;
     if (!fp) return mnt_fsname;

     mntent* e;
     while ((e = getmntent(fp.get())) != nullptr) {
         if (strcmp(dir, e->mnt_dir) == 0) {
             mnt_fsname = e->mnt_fsname;
         }
     }
     return mnt_fsname;
 }

 // Returns the device used to mount a directory in the fstab.
 static std::string find_fstab_mount(const char* dir) {
     std::unique_ptr<fstab, decltype(&fs_mgr_free_fstab)> fstab(fs_mgr_read_fstab_default(),
                                                                fs_mgr_free_fstab);
     struct fstab_rec* rec = fs_mgr_get_entry_for_mount_point(fstab.get(), dir);
     return rec ? rec->blk_device : "";
 }

 // The proc entry for / is full of lies, so check fstab instead.
 // /proc/mounts lists rootfs and /dev/root, neither of which is what we want.
 static std::string find_mount(const char* dir, bool is_root) {
     if (is_root) {
         return find_fstab_mount(dir);
     } else {
        return find_proc_mount(dir);
     }
 }

 bool make_block_device_writable(const std::string& dev) {
     if ((dev == "overlay") || (dev == "overlayfs")) return true;
     int fd = unix_open(dev.c_str(), O_RDONLY | O_CLOEXEC);
     if (fd == -1) {
         return false;
     }

     int OFF = 0;
     bool result = (ioctl(fd, BLKROSET, &OFF) != -1);
     unix_close(fd);
     return result;
 }

 static bool can_unshare_blocks(int fd, const char* dev) {
     const char* E2FSCK_BIN = "/system/bin/e2fsck";
     if (access(E2FSCK_BIN, X_OK)) {
         WriteFdFmt(fd, "e2fsck is not available, cannot undo deduplication on %s\n", dev);
         return false;
     }

     pid_t child;
     char* env[] = {nullptr};
     const char* argv[] = {E2FSCK_BIN, "-n", "-E", "unshare_blocks", dev, nullptr};
     if (posix_spawn(&child, E2FSCK_BIN, nullptr, nullptr, const_cast<char**>(argv), env)) {
         WriteFdFmt(fd, "failed to e2fsck to check deduplication: %s\n", strerror(errno));
         return false;
     }
     int status = 0;
     int ret = TEMP_FAILURE_RETRY(waitpid(child, &status, 0));
     if (ret < 0) {
         WriteFdFmt(fd, "failed to get e2fsck status: %s\n", strerror(errno));
         return false;
     }
     if (!WIFEXITED(status)) {
         WriteFdFmt(fd, "e2fsck exited abnormally with status %d\n", status);
         return false;
     }
     int rc = WEXITSTATUS(status);
     if (rc != 0) {
         WriteFdFmt(fd,
                    "%s is deduplicated, and an e2fsck check failed. It might not "
                    "have enough free-space to be remounted as writable.\n",
                    dev);
         return false;
     }
     return true;
 }

 static unsigned long get_mount_flags(int fd, const char* dir) {
     struct statvfs st_vfs;
     if (statvfs(dir, &st_vfs) == -1) {
         // Even though we could not get the original mount flags, assume that
         // the mount was originally read-only.
         WriteFdFmt(fd, "statvfs of the %s mount failed: %s.\n", dir, strerror(errno));
         return MS_RDONLY;
     }
     return st_vfs.f_flag;
 }

 static bool remount_partition(int fd, const char* dir) {
     if (!directory_exists(dir)) {
         return true;
     }
     bool is_root = strcmp(dir, "/") == 0;
     if (is_root && !find_mount("/system", false).empty()) {
         dir = "/system";
         is_root = false;
     }
     std::string dev = find_mount(dir, is_root);
     // Even if the device for the root is not found, we still try to remount it
     // as rw. This typically only happens when running Android in a container:
     // the root will almost always be in a loop device, which is dynamic, so
     // it's not convenient to put in the fstab.
     if (dev.empty() && !is_root) {
         return true;
     }
     if (!dev.empty() && !make_block_device_writable(dev)) {
         WriteFdFmt(fd, "remount of %s failed; couldn't make block device %s writable: %s\n",
                    dir, dev.c_str(), strerror(errno));
         return false;
     }

     unsigned long remount_flags = get_mount_flags(fd, dir);
     remount_flags &= ~MS_RDONLY;
     remount_flags |= MS_REMOUNT;

     if (mount(dev.c_str(), dir, "none", remount_flags | MS_BIND, nullptr) == -1) {
         // This is useful for cases where the superblock is already marked as
         // read-write, but the mount itself is read-only, such as containers
         // where the remount with just MS_REMOUNT is forbidden by the kernel.
         WriteFdFmt(fd, "remount of the %s mount failed: %s.\n", dir, strerror(errno));
         return false;
     }
     if (mount(dev.c_str(), dir, "none", MS_REMOUNT, nullptr) == -1) {
         WriteFdFmt(fd, "remount of the %s superblock failed: %s\n", dir, strerror(errno));
         return false;
     }
     return true;
 }

 static void reboot_for_remount(int fd, bool need_fsck) {
     std::string reboot_cmd = "reboot";
     if (need_fsck) {
         const std::vector<std::string> options = {"--fsck_unshare_blocks"};
         std::string err;
         if (!write_bootloader_message(options, &err)) {
             WriteFdFmt(fd, "Failed to set bootloader message: %s\n", err.c_str());
             return;
         }

         WriteFdExactly(fd,
                        "The device will now reboot to recovery and attempt "
                        "un-deduplication.\n");
         reboot_cmd = "reboot,recovery";
     }

     sync();
     android::base::SetProperty(ANDROID_RB_PROPERTY, reboot_cmd.c_str());
 }

 void remount_service(unique_fd fd, const std::string& cmd) {
     bool user_requested_reboot = cmd == "-R";

     if (getuid() != 0) {
         WriteFdExactly(fd.get(), "Not running as root. Try \"adb root\" first.\n");
         return;
     }

     bool system_verified = !(android::base::GetProperty("partition.system.verified", "").empty());
     bool vendor_verified = !(android::base::GetProperty("partition.vendor.verified", "").empty());

     std::vector<std::string> partitions{"/",        "/odm",   "/oem", "/product_services",
                                         "/product", "/vendor"};

     bool verity_enabled = (system_verified || vendor_verified);

     // If we can use overlayfs, lets get it in place first
     // before we struggle with determining deduplication operations.
     if (!verity_enabled && fs_mgr_overlayfs_setup()) {
         std::unique_ptr<fstab, decltype(&fs_mgr_free_fstab)> fstab(fs_mgr_read_fstab_default(),
                                                                    fs_mgr_free_fstab);
         if (fs_mgr_overlayfs_mount_all(fstab.get())) {
             WriteFdExactly(fd.get(), "overlayfs mounted\n");
         }
     }

     // Find partitions that are deduplicated, and can be un-deduplicated.
     std::set<std::string> dedup;
     for (const auto& part : partitions) {
         auto partition = part;
         if ((part == "/") && !find_mount("/system", false).empty()) partition = "/system";
         std::string dev = find_mount(partition.c_str(), partition == "/");
         if (dev.empty() || !fs_mgr_has_shared_blocks(partition, dev)) {
             continue;
         }
         if (can_unshare_blocks(fd.get(), dev.c_str())) {
             dedup.emplace(partition);
         }
     }

     // Reboot now if the user requested it (and an operation needs a reboot).
     if (user_requested_reboot) {
         if (!dedup.empty() || verity_enabled) {
             if (verity_enabled) {
                 set_verity_enabled_state_service(unique_fd(dup(fd.get())), false);
             }
             reboot_for_remount(fd.get(), !dedup.empty());
             return;
         }
         WriteFdExactly(fd.get(), "No reboot needed, skipping -R.\n");
     }

     // If we need to disable-verity, but we also need to perform a recovery
     // fsck for deduplicated partitions, hold off on warning about verity. We
     // can handle both verity and the recovery fsck in the same reboot cycle.
     if (verity_enabled && dedup.empty()) {
         // Allow remount but warn of likely bad effects
         bool both = system_verified && vendor_verified;
         WriteFdFmt(fd.get(), "dm_verity is enabled on the %s%s%s partition%s.\n",
                    system_verified ? "system" : "", both ? " and " : "",
                    vendor_verified ? "vendor" : "", both ? "s" : "");
         WriteFdExactly(fd.get(),
                        "Use \"adb disable-verity\" to disable verity.\n"
                        "If you do not, remount may succeed, however, you will still "
                        "not be able to write to these volumes.\n");
         WriteFdExactly(fd.get(),
                        "Alternately, use \"adb remount -R\" to disable verity "
                        "and automatically reboot.\n");
     }

     bool success = true;
     for (const auto& partition : partitions) {
         // Don't try to remount partitions that need an fsck in recovery.
         if (dedup.count(partition)) {
             continue;
         }
         success &= remount_partition(fd.get(), partition.c_str());
     }

     if (!dedup.empty()) {
         WriteFdExactly(fd.get(),
                        "The following partitions are deduplicated and cannot "
                        "yet be remounted:\n");
         for (const std::string& name : dedup) {
             WriteFdFmt(fd.get(), "  %s\n", name.c_str());
         }

         WriteFdExactly(fd.get(),
                        "To reboot and un-deduplicate the listed partitions, "
                        "please retry with adb remount -R.\n");
         if (system_verified || vendor_verified) {
             WriteFdExactly(fd.get(), "Note: verity will be automatically disabled after reboot.\n");
         }
         return;
     }

     if (!success) {
         WriteFdExactly(fd.get(), "remount failed\n");
     } else {
         WriteFdExactly(fd.get(), "remount succeeded\n");
     }
 }
	/*
	* Copyright (C) 2008 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#define TRACE_TAG ADB

	#include "sysdeps.h"

	#include <errno.h>
	#include <fcntl.h>
	#include <mntent.h>
	#include <spawn.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <sys/mount.h>
	#include <sys/statvfs.h>
	#include <sys/vfs.h>
	#include <unistd.h>

	#include <memory>
	#include <set>
	#include <string>
	#include <vector>

	#include <android-base/properties.h>
	#include <bootloader_message/bootloader_message.h>
	#include <cutils/android_reboot.h>
	#include <fs_mgr.h>
	#include <fs_mgr_overlayfs.h>

	#include "adb.h"
	#include "adb_io.h"
	#include "adb_unique_fd.h"
	#include "adb_utils.h"
	#include "set_verity_enable_state_service.h"

	// Returns the last device used to mount a directory in /proc/mounts.
	// This will find overlayfs entry where upperdir=lowerdir, to make sure
	// remount is associated with the correct directory.
	static std::string find_proc_mount(const char* dir) {
	std::unique_ptr<FILE, int()(FILE)> fp(setmntent("/proc/mounts", "r"), endmntent);
	std::string mnt_fsname;
	if (!fp) return mnt_fsname;

	mntent* e;
	while ((e = getmntent(fp.get())) != nullptr) {
	if (strcmp(dir, e->mnt_dir) == 0) {
	mnt_fsname = e->mnt_fsname;
	}
	}
	return mnt_fsname;
	}

	// Returns the device used to mount a directory in the fstab.
	static std::string find_fstab_mount(const char* dir) {
	std::unique_ptr<fstab, decltype(&fs_mgr_free_fstab)> fstab(fs_mgr_read_fstab_default(),
	fs_mgr_free_fstab);
	struct fstab_rec* rec = fs_mgr_get_entry_for_mount_point(fstab.get(), dir);
	return rec ? rec->blk_device : "";
	}

	// The proc entry for / is full of lies, so check fstab instead.
	// /proc/mounts lists rootfs and /dev/root, neither of which is what we want.
	static std::string find_mount(const char* dir, bool is_root) {
	if (is_root) {
	return find_fstab_mount(dir);
	} else {
	return find_proc_mount(dir);
	}
	}

	bool make_block_device_writable(const std::string& dev) {
	if ((dev == "overlay") \|\| (dev == "overlayfs")) return true;
	int fd = unix_open(dev.c_str(), O_RDONLY \| O_CLOEXEC);
	if (fd == -1) {
	return false;
	}

	int OFF = 0;
	bool result = (ioctl(fd, BLKROSET, &OFF) != -1);
	unix_close(fd);
	return result;
	}

	static bool can_unshare_blocks(int fd, const char* dev) {
	const char* E2FSCK_BIN = "/system/bin/e2fsck";
	if (access(E2FSCK_BIN, X_OK)) {
	WriteFdFmt(fd, "e2fsck is not available, cannot undo deduplication on %s\n", dev);
	return false;
	}

	pid_t child;
	char* env[] = {nullptr};
	const char* argv[] = {E2FSCK_BIN, "-n", "-E", "unshare_blocks", dev, nullptr};
	if (posix_spawn(&child, E2FSCK_BIN, nullptr, nullptr, const_cast<char**>(argv), env)) {
	WriteFdFmt(fd, "failed to e2fsck to check deduplication: %s\n", strerror(errno));
	return false;
	}
	int status = 0;
	int ret = TEMP_FAILURE_RETRY(waitpid(child, &status, 0));
	if (ret < 0) {
	WriteFdFmt(fd, "failed to get e2fsck status: %s\n", strerror(errno));
	return false;
	}
	if (!WIFEXITED(status)) {
	WriteFdFmt(fd, "e2fsck exited abnormally with status %d\n", status);
	return false;
	}
	int rc = WEXITSTATUS(status);
	if (rc != 0) {
	WriteFdFmt(fd,
	"%s is deduplicated, and an e2fsck check failed. It might not "
	"have enough free-space to be remounted as writable.\n",
	dev);
	return false;
	}
	return true;
	}

	static unsigned long get_mount_flags(int fd, const char* dir) {
	struct statvfs st_vfs;
	if (statvfs(dir, &st_vfs) == -1) {
	// Even though we could not get the original mount flags, assume that
	// the mount was originally read-only.
	WriteFdFmt(fd, "statvfs of the %s mount failed: %s.\n", dir, strerror(errno));
	return MS_RDONLY;
	}
	return st_vfs.f_flag;
	}

	static bool remount_partition(int fd, const char* dir) {
	if (!directory_exists(dir)) {
	return true;
	}
	bool is_root = strcmp(dir, "/") == 0;
	if (is_root && !find_mount("/system", false).empty()) {
	dir = "/system";
	is_root = false;
	}
	std::string dev = find_mount(dir, is_root);
	// Even if the device for the root is not found, we still try to remount it
	// as rw. This typically only happens when running Android in a container:
	// the root will almost always be in a loop device, which is dynamic, so
	// it's not convenient to put in the fstab.
	if (dev.empty() && !is_root) {
	return true;
	}
	if (!dev.empty() && !make_block_device_writable(dev)) {
	WriteFdFmt(fd, "remount of %s failed; couldn't make block device %s writable: %s\n",
	dir, dev.c_str(), strerror(errno));
	return false;
	}

	unsigned long remount_flags = get_mount_flags(fd, dir);
	remount_flags &= ~MS_RDONLY;
	remount_flags \|= MS_REMOUNT;

	if (mount(dev.c_str(), dir, "none", remount_flags \| MS_BIND, nullptr) == -1) {
	// This is useful for cases where the superblock is already marked as
	// read-write, but the mount itself is read-only, such as containers
	// where the remount with just MS_REMOUNT is forbidden by the kernel.
	WriteFdFmt(fd, "remount of the %s mount failed: %s.\n", dir, strerror(errno));
	return false;
	}
	if (mount(dev.c_str(), dir, "none", MS_REMOUNT, nullptr) == -1) {
	WriteFdFmt(fd, "remount of the %s superblock failed: %s\n", dir, strerror(errno));
	return false;
	}
	return true;
	}

	static void reboot_for_remount(int fd, bool need_fsck) {
	std::string reboot_cmd = "reboot";
	if (need_fsck) {
	const std::vector<std::string> options = {"--fsck_unshare_blocks"};
	std::string err;
	if (!write_bootloader_message(options, &err)) {
	WriteFdFmt(fd, "Failed to set bootloader message: %s\n", err.c_str());
	return;
	}

	WriteFdExactly(fd,
	"The device will now reboot to recovery and attempt "
	"un-deduplication.\n");
	reboot_cmd = "reboot,recovery";
	}

	sync();
	android::base::SetProperty(ANDROID_RB_PROPERTY, reboot_cmd.c_str());
	}

	void remount_service(unique_fd fd, const std::string& cmd) {
	bool user_requested_reboot = cmd == "-R";

	if (getuid() != 0) {
	WriteFdExactly(fd.get(), "Not running as root. Try \"adb root\" first.\n");
	return;
	}

	bool system_verified = !(android::base::GetProperty("partition.system.verified", "").empty());
	bool vendor_verified = !(android::base::GetProperty("partition.vendor.verified", "").empty());

	std::vector<std::string> partitions{"/", "/odm", "/oem", "/product_services",
	"/product", "/vendor"};

	bool verity_enabled = (system_verified \|\| vendor_verified);

	// If we can use overlayfs, lets get it in place first
	// before we struggle with determining deduplication operations.
	if (!verity_enabled && fs_mgr_overlayfs_setup()) {
	std::unique_ptr<fstab, decltype(&fs_mgr_free_fstab)> fstab(fs_mgr_read_fstab_default(),
	fs_mgr_free_fstab);
	if (fs_mgr_overlayfs_mount_all(fstab.get())) {
	WriteFdExactly(fd.get(), "overlayfs mounted\n");
	}
	}

	// Find partitions that are deduplicated, and can be un-deduplicated.
	std::set<std::string> dedup;
	for (const auto& part : partitions) {
	auto partition = part;
	if ((part == "/") && !find_mount("/system", false).empty()) partition = "/system";
	std::string dev = find_mount(partition.c_str(), partition == "/");
	if (dev.empty() \|\| !fs_mgr_has_shared_blocks(partition, dev)) {
	continue;
	}
	if (can_unshare_blocks(fd.get(), dev.c_str())) {
	dedup.emplace(partition);
	}
	}

	// Reboot now if the user requested it (and an operation needs a reboot).
	if (user_requested_reboot) {
	if (!dedup.empty() \|\| verity_enabled) {
	if (verity_enabled) {
	set_verity_enabled_state_service(unique_fd(dup(fd.get())), false);
	}
	reboot_for_remount(fd.get(), !dedup.empty());
	return;
	}
	WriteFdExactly(fd.get(), "No reboot needed, skipping -R.\n");
	}

	// If we need to disable-verity, but we also need to perform a recovery
	// fsck for deduplicated partitions, hold off on warning about verity. We
	// can handle both verity and the recovery fsck in the same reboot cycle.
	if (verity_enabled && dedup.empty()) {
	// Allow remount but warn of likely bad effects
	bool both = system_verified && vendor_verified;
	WriteFdFmt(fd.get(), "dm_verity is enabled on the %s%s%s partition%s.\n",
	system_verified ? "system" : "", both ? " and " : "",
	vendor_verified ? "vendor" : "", both ? "s" : "");
	WriteFdExactly(fd.get(),
	"Use \"adb disable-verity\" to disable verity.\n"
	"If you do not, remount may succeed, however, you will still "
	"not be able to write to these volumes.\n");
	WriteFdExactly(fd.get(),
	"Alternately, use \"adb remount -R\" to disable verity "
	"and automatically reboot.\n");
	}

	bool success = true;
	for (const auto& partition : partitions) {
	// Don't try to remount partitions that need an fsck in recovery.
	if (dedup.count(partition)) {
	continue;
	}
	success &= remount_partition(fd.get(), partition.c_str());
	}

	if (!dedup.empty()) {
	WriteFdExactly(fd.get(),
	"The following partitions are deduplicated and cannot "
	"yet be remounted:\n");
	for (const std::string& name : dedup) {
	WriteFdFmt(fd.get(), " %s\n", name.c_str());
	}

	WriteFdExactly(fd.get(),
	"To reboot and un-deduplicate the listed partitions, "
	"please retry with adb remount -R.\n");
	if (system_verified \|\| vendor_verified) {
	WriteFdExactly(fd.get(), "Note: verity will be automatically disabled after reboot.\n");
	}
	return;
	}

	if (!success) {
	WriteFdExactly(fd.get(), "remount failed\n");
	} else {
	WriteFdExactly(fd.get(), "remount succeeded\n");
	}
	}