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/vfs.h>
 #include <unistd.h>

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

 #include <android-base/properties.h>
 #include <bootloader_message/bootloader_message.h>
 #include <cutils/android_reboot.h>
 #include <ext4_utils/ext4_utils.h>

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

 // Returns the device used to mount a directory in /proc/mounts.
 static std::string find_proc_mount(const char* dir) {
     std::unique_ptr<FILE, int(*)(FILE*)> fp(setmntent("/proc/mounts", "r"), endmntent);
     if (!fp) {
         return "";
     }

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

 // 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) {
     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 fs_has_shared_blocks(const char* dev) {
     struct statfs fs;
     if (statfs(dev, &fs) == -1 || fs.f_type == EXT4_SUPER_MAGIC) {
         return false;
     }
     unique_fd fd(unix_open(dev, O_RDONLY));
     if (fd < 0) {
         return false;
     }
     struct ext4_super_block sb;
     if (lseek64(fd, 1024, SEEK_SET) < 0 || unix_read(fd, &sb, sizeof(sb)) < 0) {
         return false;
     }
     struct fs_info info;
     if (ext4_parse_sb(&sb, &info) < 0) {
         return false;
     }
     return (info.feat_ro_compat & EXT4_FEATURE_RO_COMPAT_SHARED_BLOCKS) != 0;
 }

 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 bool remount_partition(int fd, const char* dir) {
     if (!directory_exists(dir)) {
         return true;
     }
     bool is_root = strcmp(dir, "/") == 0;
     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;
     }
     if (mount(dev.c_str(), dir, "none", MS_REMOUNT | 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(int fd, void* cookie) {
     unique_fd close_fd(fd);

     const char* cmd = reinterpret_cast<const char*>(cookie);
     bool user_requested_reboot = cmd && !strcmp(cmd, "-R");

     if (getuid() != 0) {
         WriteFdExactly(fd, "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", "/vendor"};
     if (android::base::GetBoolProperty("ro.build.system_root_image", false)) {
         partitions.push_back("/");
     } else {
         partitions.push_back("/system");
     }

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

     bool verity_enabled = (system_verified || vendor_verified);

     // 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(fd, nullptr);
             }
             reboot_for_remount(fd, !dedup.empty());
             return;
         }
         WriteFdExactly(fd, "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,
                    "dm_verity is enabled on the %s%s%s partition%s.\n",
                    system_verified ? "system" : "",
                    both ? " and " : "",
                    vendor_verified ? "vendor" : "",
                    both ? "s" : "");
         WriteFdExactly(fd,
                        "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,
                        "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, partition.c_str());
     }

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

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

     if (!success) {
         WriteFdExactly(fd, "remount failed\n");
     } else {
         WriteFdExactly(fd, "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/vfs.h>
	#include <unistd.h>

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

	#include <android-base/properties.h>
	#include <bootloader_message/bootloader_message.h>
	#include <cutils/android_reboot.h>
	#include <ext4_utils/ext4_utils.h>

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

	// Returns the device used to mount a directory in /proc/mounts.
	static std::string find_proc_mount(const char* dir) {
	std::unique_ptr<FILE, int()(FILE)> fp(setmntent("/proc/mounts", "r"), endmntent);
	if (!fp) {
	return "";
	}

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

	// 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) {
	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 fs_has_shared_blocks(const char* dev) {
	struct statfs fs;
	if (statfs(dev, &fs) == -1 \|\| fs.f_type == EXT4_SUPER_MAGIC) {
	return false;
	}
	unique_fd fd(unix_open(dev, O_RDONLY));
	if (fd < 0) {
	return false;
	}
	struct ext4_super_block sb;
	if (lseek64(fd, 1024, SEEK_SET) < 0 \|\| unix_read(fd, &sb, sizeof(sb)) < 0) {
	return false;
	}
	struct fs_info info;
	if (ext4_parse_sb(&sb, &info) < 0) {
	return false;
	}
	return (info.feat_ro_compat & EXT4_FEATURE_RO_COMPAT_SHARED_BLOCKS) != 0;
	}

	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 bool remount_partition(int fd, const char* dir) {
	if (!directory_exists(dir)) {
	return true;
	}
	bool is_root = strcmp(dir, "/") == 0;
	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;
	}
	if (mount(dev.c_str(), dir, "none", MS_REMOUNT \| 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(int fd, void* cookie) {
	unique_fd close_fd(fd);

	const char* cmd = reinterpret_cast<const char*>(cookie);
	bool user_requested_reboot = cmd && !strcmp(cmd, "-R");

	if (getuid() != 0) {
	WriteFdExactly(fd, "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", "/vendor"};
	if (android::base::GetBoolProperty("ro.build.system_root_image", false)) {
	partitions.push_back("/");
	} else {
	partitions.push_back("/system");
	}

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

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

	// 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(fd, nullptr);
	}
	reboot_for_remount(fd, !dedup.empty());
	return;
	}
	WriteFdExactly(fd, "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,
	"dm_verity is enabled on the %s%s%s partition%s.\n",
	system_verified ? "system" : "",
	both ? " and " : "",
	vendor_verified ? "vendor" : "",
	both ? "s" : "");
	WriteFdExactly(fd,
	"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,
	"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, partition.c_str());
	}

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

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

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