secdiscard.cpp - SHIFTPHONES/android_system_vold - Gitiles

 /*
  * Copyright (C) 2015 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.
  */

 #include <string>

 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <errno.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <linux/fs.h>
 #include <linux/fiemap.h>

 #define LOG_TAG "secdiscard"
 #include "cutils/log.h"

 // Deliberately limit ourselves to wiping small files.
 #define MAX_WIPE_LENGTH 4096
 #define INIT_BUFFER_SIZE 2048

 static void usage(char *progname);
 static void destroy_key(const std::string &path);
 static int file_device_range(const std::string &path, uint64_t range[2]);
 static int open_block_device_for_path(const std::string &path);
 static int read_file_as_string_atomically(const std::string &path, std::string &contents);
 static int find_block_device_for_path(
     const std::string &mounts,
     const std::string &path,
     std::string &block_device);

 int main(int argc, char **argv) {
     if (argc != 2 || argv[1][0] != '/') {
         usage(argv[0]);
         return -1;
     }
     SLOGD("Running: %s %s", argv[0], argv[1]);
     std::string target(argv[1]);
     destroy_key(target);
     if (unlink(argv[1]) != 0 && errno != ENOENT) {
         SLOGE("Unable to delete %s: %s",
             argv[1], strerror(errno));
         return -1;
     }
     return 0;
 }

 static void usage(char *progname) {
     fprintf(stderr, "Usage: %s <absolute path>\n", progname);
 }

 // BLKSECDISCARD all content in "path", if it's small enough.
 static void destroy_key(const std::string &path) {
     uint64_t range[2];
     if (file_device_range(path, range) < 0) {
         return;
     }
     int fs_fd = open_block_device_for_path(path);
     if (fs_fd < 0) {
         return;
     }
     if (ioctl(fs_fd, BLKSECDISCARD, range) != 0) {
         SLOGE("Unable to BLKSECDISCARD %s: %s", path.c_str(), strerror(errno));
         close(fs_fd);
         return;
     }
     close(fs_fd);
     SLOGD("Discarded %s", path.c_str());
 }

 // Find a short range that completely covers the file.
 // If there isn't one, return -1, otherwise 0.
 static int file_device_range(const std::string &path, uint64_t range[2])
 {
     int fd = open(path.c_str(), O_RDONLY | O_CLOEXEC);
     if (fd < 0) {
         if (errno == ENOENT) {
             SLOGD("Unable to open %s: %s", path.c_str(), strerror(errno));
         } else {
             SLOGE("Unable to open %s: %s", path.c_str(), strerror(errno));
         }
         return -1;
     }
     alignas(struct fiemap) char fiemap_buffer[offsetof(struct fiemap, fm_extents[1])];
     memset(fiemap_buffer, 0, sizeof(fiemap_buffer));
     struct fiemap *fiemap = (struct fiemap *)fiemap_buffer;
     fiemap->fm_start = 0;
     fiemap->fm_length = UINT64_MAX;
     fiemap->fm_flags = 0;
     fiemap->fm_extent_count = 1;
     fiemap->fm_mapped_extents = 0;
     if (ioctl(fd, FS_IOC_FIEMAP, fiemap) != 0) {
         SLOGE("Unable to FIEMAP %s: %s", path.c_str(), strerror(errno));
         close(fd);
         return -1;
     }
     close(fd);
     if (fiemap->fm_mapped_extents != 1) {
         SLOGE("Expecting one extent, got %d in %s", fiemap->fm_mapped_extents, path.c_str());
         return -1;
     }
     struct fiemap_extent *extent = &fiemap->fm_extents[0];
     if (!(extent->fe_flags & FIEMAP_EXTENT_LAST)) {
         SLOGE("First extent was not the last in %s", path.c_str());
         return -1;
     }
     if (extent->fe_flags &
             (FIEMAP_EXTENT_UNKNOWN | FIEMAP_EXTENT_DELALLOC | FIEMAP_EXTENT_NOT_ALIGNED)) {
         SLOGE("Extent has unexpected flags %ulx: %s", extent->fe_flags, path.c_str());
         return -1;
     }
     if (extent->fe_length > MAX_WIPE_LENGTH) {
         SLOGE("Extent too big, %llu bytes in %s", extent->fe_length, path.c_str());
         return -1;
     }
     range[0] = extent->fe_physical;
     range[1] = extent->fe_length;
     return 0;
 }

 // Given a file path, look for the corresponding
 // block device in /proc/mounts and open it.
 static int open_block_device_for_path(const std::string &path)
 {
     std::string mountsfile("/proc/mounts");
     std::string mounts;
     if (read_file_as_string_atomically(mountsfile, mounts) < 0) {
         return -1;
     }
     std::string block_device;
     if (find_block_device_for_path(mounts, path, block_device) < 0) {
         return -1;
     }
     SLOGD("For path %s block device is %s", path.c_str(), block_device.c_str());
     int res = open(block_device.c_str(), O_RDWR | O_LARGEFILE | O_CLOEXEC);
     if (res < 0) {
         SLOGE("Failed to open device %s: %s", block_device.c_str(), strerror(errno));
         return -1;
     }
     return res;
 }

 // Read a file into a buffer in a single gulp, for atomicity.
 // Null-terminate the buffer.
 // Retry until the buffer is big enough.
 static int read_file_as_string_atomically(const std::string &path, std::string &contents)
 {
     ssize_t buffer_size = INIT_BUFFER_SIZE;
     while (true) {
         int fd = open(path.c_str(), O_RDONLY | O_CLOEXEC);
         if (fd < 0) {
             SLOGE("Failed to open %s: %s", path.c_str(), strerror(errno));
             return -1;
         }
         contents.resize(buffer_size);
         ssize_t read_size = read(fd, &contents[0], buffer_size);
         if (read_size < 0) {
             SLOGE("Failed to read from %s: %s", path.c_str(), strerror(errno));
             close(fd);
             return -1;
         }
         close(fd);
         if (read_size < buffer_size) {
             contents.resize(read_size);
             return 0;
         }
         SLOGD("%s too big for buffer of size %zu", path.c_str(), buffer_size);
         buffer_size <<= 1;
     }
 }

 // Search a string representing result from /proc/mounts
 // for the mount point of a particular file by prefix matching
 // and return the corresponding block device as a
 // pointer into the mounts string.
 // This destroys the mounts string.
 static int find_block_device_for_path(
     const std::string &mounts,
     const std::string &path,
     std::string &block_device)
 {
     auto line_begin = mounts.begin();
     size_t best_prefix = 0;
     std::string::const_iterator line_end;
     while (line_begin != mounts.end()) {
         line_end = std::find(line_begin, mounts.end(), '\n');
         if (line_end == mounts.end()) {
             break;
         }
         auto device_end = std::find(line_begin, line_end, ' ');;
         if (device_end == line_end) {
             break;
         }
         auto mountpoint_begin = device_end +1;
         auto mountpoint_end = std::find(mountpoint_begin, line_end, ' ');
         if (mountpoint_end == line_end) {
             break;
         }
         if (std::find(line_begin, mountpoint_end, '\\') != mountpoint_end) {
             // We don't correctly handle escape sequences
             // and we don't expect to encounter any
             // so fail if we do.
             break;
         }
         size_t mountpoint_len = mountpoint_end - mountpoint_begin;
         if (mountpoint_len > best_prefix &&
                 mountpoint_len < path.length() &&
                 path[mountpoint_len] == '/' &&
                 std::equal(mountpoint_begin, mountpoint_end, path.begin())) {
             block_device = std::string(line_begin, device_end);
             best_prefix = mountpoint_len;
         }
         line_begin = line_end +1;
     }
     // All of the "break"s above are fatal parse errors.
     if (line_begin != mounts.end()) {
         SLOGE("Unable to parse line in %s: %s",
             path.c_str(), std::string(line_begin, line_end).c_str());
         return -1;
     }
     if (best_prefix == 0) {
         SLOGE("No prefix found for path: %s", path.c_str());
         return -1;
     }
     return 0;
 }
	/*
	* Copyright (C) 2015 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.
	*/

	#include <string>

	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <errno.h>
	#include <sys/types.h>
	#include <sys/stat.h>
	#include <fcntl.h>
	#include <linux/fs.h>
	#include <linux/fiemap.h>

	#define LOG_TAG "secdiscard"
	#include "cutils/log.h"

	// Deliberately limit ourselves to wiping small files.
	#define MAX_WIPE_LENGTH 4096
	#define INIT_BUFFER_SIZE 2048

	static void usage(char *progname);
	static void destroy_key(const std::string &path);
	static int file_device_range(const std::string &path, uint64_t range[2]);
	static int open_block_device_for_path(const std::string &path);
	static int read_file_as_string_atomically(const std::string &path, std::string &contents);
	static int find_block_device_for_path(
	const std::string &mounts,
	const std::string &path,
	std::string &block_device);

	int main(int argc, char **argv) {
	if (argc != 2 \|\| argv[1][0] != '/') {
	usage(argv[0]);
	return -1;
	}
	SLOGD("Running: %s %s", argv[0], argv[1]);
	std::string target(argv[1]);
	destroy_key(target);
	if (unlink(argv[1]) != 0 && errno != ENOENT) {
	SLOGE("Unable to delete %s: %s",
	argv[1], strerror(errno));
	return -1;
	}
	return 0;
	}

	static void usage(char *progname) {
	fprintf(stderr, "Usage: %s <absolute path>\n", progname);
	}

	// BLKSECDISCARD all content in "path", if it's small enough.
	static void destroy_key(const std::string &path) {
	uint64_t range[2];
	if (file_device_range(path, range) < 0) {
	return;
	}
	int fs_fd = open_block_device_for_path(path);
	if (fs_fd < 0) {
	return;
	}
	if (ioctl(fs_fd, BLKSECDISCARD, range) != 0) {
	SLOGE("Unable to BLKSECDISCARD %s: %s", path.c_str(), strerror(errno));
	close(fs_fd);
	return;
	}
	close(fs_fd);
	SLOGD("Discarded %s", path.c_str());
	}

	// Find a short range that completely covers the file.
	// If there isn't one, return -1, otherwise 0.
	static int file_device_range(const std::string &path, uint64_t range[2])
	{
	int fd = open(path.c_str(), O_RDONLY \| O_CLOEXEC);
	if (fd < 0) {
	if (errno == ENOENT) {
	SLOGD("Unable to open %s: %s", path.c_str(), strerror(errno));
	} else {
	SLOGE("Unable to open %s: %s", path.c_str(), strerror(errno));
	}
	return -1;
	}
	alignas(struct fiemap) char fiemap_buffer[offsetof(struct fiemap, fm_extents[1])];
	memset(fiemap_buffer, 0, sizeof(fiemap_buffer));
	struct fiemap fiemap = (struct fiemap )fiemap_buffer;
	fiemap->fm_start = 0;
	fiemap->fm_length = UINT64_MAX;
	fiemap->fm_flags = 0;
	fiemap->fm_extent_count = 1;
	fiemap->fm_mapped_extents = 0;
	if (ioctl(fd, FS_IOC_FIEMAP, fiemap) != 0) {
	SLOGE("Unable to FIEMAP %s: %s", path.c_str(), strerror(errno));
	close(fd);
	return -1;
	}
	close(fd);
	if (fiemap->fm_mapped_extents != 1) {
	SLOGE("Expecting one extent, got %d in %s", fiemap->fm_mapped_extents, path.c_str());
	return -1;
	}
	struct fiemap_extent *extent = &fiemap->fm_extents[0];
	if (!(extent->fe_flags & FIEMAP_EXTENT_LAST)) {
	SLOGE("First extent was not the last in %s", path.c_str());
	return -1;
	}
	if (extent->fe_flags &
	(FIEMAP_EXTENT_UNKNOWN \| FIEMAP_EXTENT_DELALLOC \| FIEMAP_EXTENT_NOT_ALIGNED)) {
	SLOGE("Extent has unexpected flags %ulx: %s", extent->fe_flags, path.c_str());
	return -1;
	}
	if (extent->fe_length > MAX_WIPE_LENGTH) {
	SLOGE("Extent too big, %llu bytes in %s", extent->fe_length, path.c_str());
	return -1;
	}
	range[0] = extent->fe_physical;
	range[1] = extent->fe_length;
	return 0;
	}

	// Given a file path, look for the corresponding
	// block device in /proc/mounts and open it.
	static int open_block_device_for_path(const std::string &path)
	{
	std::string mountsfile("/proc/mounts");
	std::string mounts;
	if (read_file_as_string_atomically(mountsfile, mounts) < 0) {
	return -1;
	}
	std::string block_device;
	if (find_block_device_for_path(mounts, path, block_device) < 0) {
	return -1;
	}
	SLOGD("For path %s block device is %s", path.c_str(), block_device.c_str());
	int res = open(block_device.c_str(), O_RDWR \| O_LARGEFILE \| O_CLOEXEC);
	if (res < 0) {
	SLOGE("Failed to open device %s: %s", block_device.c_str(), strerror(errno));
	return -1;
	}
	return res;
	}

	// Read a file into a buffer in a single gulp, for atomicity.
	// Null-terminate the buffer.
	// Retry until the buffer is big enough.
	static int read_file_as_string_atomically(const std::string &path, std::string &contents)
	{
	ssize_t buffer_size = INIT_BUFFER_SIZE;
	while (true) {
	int fd = open(path.c_str(), O_RDONLY \| O_CLOEXEC);
	if (fd < 0) {
	SLOGE("Failed to open %s: %s", path.c_str(), strerror(errno));
	return -1;
	}
	contents.resize(buffer_size);
	ssize_t read_size = read(fd, &contents[0], buffer_size);
	if (read_size < 0) {
	SLOGE("Failed to read from %s: %s", path.c_str(), strerror(errno));
	close(fd);
	return -1;
	}
	close(fd);
	if (read_size < buffer_size) {
	contents.resize(read_size);
	return 0;
	}
	SLOGD("%s too big for buffer of size %zu", path.c_str(), buffer_size);
	buffer_size <<= 1;
	}
	}

	// Search a string representing result from /proc/mounts
	// for the mount point of a particular file by prefix matching
	// and return the corresponding block device as a
	// pointer into the mounts string.
	// This destroys the mounts string.
	static int find_block_device_for_path(
	const std::string &mounts,
	const std::string &path,
	std::string &block_device)
	{
	auto line_begin = mounts.begin();
	size_t best_prefix = 0;
	std::string::const_iterator line_end;
	while (line_begin != mounts.end()) {
	line_end = std::find(line_begin, mounts.end(), '\n');
	if (line_end == mounts.end()) {
	break;
	}
	auto device_end = std::find(line_begin, line_end, ' ');;
	if (device_end == line_end) {
	break;
	}
	auto mountpoint_begin = device_end +1;
	auto mountpoint_end = std::find(mountpoint_begin, line_end, ' ');
	if (mountpoint_end == line_end) {
	break;
	}
	if (std::find(line_begin, mountpoint_end, '\\') != mountpoint_end) {
	// We don't correctly handle escape sequences
	// and we don't expect to encounter any
	// so fail if we do.
	break;
	}
	size_t mountpoint_len = mountpoint_end - mountpoint_begin;
	if (mountpoint_len > best_prefix &&
	mountpoint_len < path.length() &&
	path[mountpoint_len] == '/' &&
	std::equal(mountpoint_begin, mountpoint_end, path.begin())) {
	block_device = std::string(line_begin, device_end);
	best_prefix = mountpoint_len;
	}
	line_begin = line_end +1;
	}
	// All of the "break"s above are fatal parse errors.
	if (line_begin != mounts.end()) {
	SLOGE("Unable to parse line in %s: %s",
	path.c_str(), std::string(line_begin, line_end).c_str());
	return -1;
	}
	if (best_prefix == 0) {
	SLOGE("No prefix found for path: %s", path.c_str());
	return -1;
	}
	return 0;
	}