ANDROID: Incremental fs: Protect get_fill_block, and add a field

Since INCFS_IOC_GET_FILLED_BLOCKS potentially leaks information about usage
patterns, and is only useful to someone filling the file, best protect it in
the same way as INCFS_IOC_FILL_BLOCKS.

Add useful field data_block_out as well

Test: incfs_test passes
Bug: 152983639
Signed-off-by: Paul Lawrence <paullawrence@google.com>
Change-Id: I126a8cf711e56592479093e9aadbfd0e7f700752
Git-commit: ecd6f86bed
Git-repo: https://android.googlesource.com/kernel/common/
Signed-off-by: Sayali Lokhande <sayalil@codeaurora.org>

fs/incfs/data_mgmt.c

@@ -437,6 +437,7 @@ int incfs_get_filled_blocks(struct data_file *df,
 	if (end_index > df->df_total_block_count)
 		end_index = df->df_total_block_count;
 	arg->total_blocks_out = df->df_total_block_count;
+	arg->data_blocks_out = df->df_data_block_count;
 
 	if (df->df_header_flags & INCFS_FILE_COMPLETE) {
 		pr_debug("File marked full, fast get_filled_blocks");

fs/incfs/vfs.c

@@ -1447,6 +1447,9 @@ static long ioctl_get_filled_blocks(struct file *f, void __user *arg)
 	if (!df)
 		return -EINVAL;
 
+	if ((uintptr_t)f->private_data != CAN_FILL)
+		return -EPERM;
+
 	if (copy_from_user(&args, args_usr_ptr, sizeof(args)) > 0)
 		return -EINVAL;
 

include/uapi/linux/incrementalfs.h

@@ -328,6 +328,9 @@ struct incfs_get_filled_blocks_args {
 	/* Actual number of blocks in file */
 	__u32 total_blocks_out;
 
+	/* The  number of data blocks in file */
+	__u32 data_blocks_out;
+
 	/* Number of bytes written to range buffer */
 	__u32 range_buffer_size_out;
 

tools/testing/selftests/filesystems/incfs/incfs_test.c

@@ -2189,12 +2189,29 @@ static int validate_ranges(const char *mount_dir, struct test_file *file)
 	int error = TEST_SUCCESS;
 	int i;
 	int range_cnt;
+	int cmd_fd = -1;
+	struct incfs_permit_fill permit_fill;
 
 	fd = open(filename, O_RDONLY);
 	free(filename);
 	if (fd <= 0)
 		return TEST_FAILURE;
 
+	error = ioctl(fd, INCFS_IOC_GET_FILLED_BLOCKS, &fba);
+	if (error != -1 || errno != EPERM) {
+		ksft_print_msg("INCFS_IOC_GET_FILLED_BLOCKS not blocked\n");
+		error = -EPERM;
+		goto out;
+	}
+
+	cmd_fd = open_commands_file(mount_dir);
+	permit_fill.file_descriptor = fd;
+	if (ioctl(cmd_fd, INCFS_IOC_PERMIT_FILL, &permit_fill)) {
+		print_error("INCFS_IOC_PERMIT_FILL failed");
+		return -EPERM;
+		goto out;
+	}
+
 	error = ioctl(fd, INCFS_IOC_GET_FILLED_BLOCKS, &fba);
 	if (error && errno != ERANGE)
 		goto out;
@@ -2212,6 +2229,11 @@ static int validate_ranges(const char *mount_dir, struct test_file *file)
 		goto out;
 	}
 
+	if (fba.data_blocks_out != block_cnt) {
+		error = -EINVAL;
+		goto out;
+	}
+
 	range_cnt = (block_cnt + 3) / 4;
 	if (range_cnt > 128)
 		range_cnt = 128;
@@ -2282,6 +2304,7 @@ static int validate_ranges(const char *mount_dir, struct test_file *file)
 
 out:
 	close(fd);
+	close(cmd_fd);
 	return error;
 }
 
@@ -2392,6 +2415,7 @@ failure:
 
 static int validate_hash_ranges(const char *mount_dir, struct test_file *file)
 {
+	int block_cnt = 1 + (file->size - 1) / INCFS_DATA_FILE_BLOCK_SIZE;
 	char *filename = concat_file_name(mount_dir, file->name);
 	int fd;
 	struct incfs_filled_range ranges[128];
@@ -2402,6 +2426,8 @@ static int validate_hash_ranges(const char *mount_dir, struct test_file *file)
 	int error = TEST_SUCCESS;
 	int file_blocks = (file->size + INCFS_DATA_FILE_BLOCK_SIZE - 1) /
 			  INCFS_DATA_FILE_BLOCK_SIZE;
+	int cmd_fd = -1;
+	struct incfs_permit_fill permit_fill;
 
 	if (file->size <= 4096 / 32 * 4096)
 		return 0;
@@ -2411,10 +2437,35 @@ static int validate_hash_ranges(const char *mount_dir, struct test_file *file)
 	if (fd <= 0)
 		return TEST_FAILURE;
 
+	error = ioctl(fd, INCFS_IOC_GET_FILLED_BLOCKS, &fba);
+	if (error != -1 || errno != EPERM) {
+		ksft_print_msg("INCFS_IOC_GET_FILLED_BLOCKS not blocked\n");
+		error = -EPERM;
+		goto out;
+	}
+
+	cmd_fd = open_commands_file(mount_dir);
+	permit_fill.file_descriptor = fd;
+	if (ioctl(cmd_fd, INCFS_IOC_PERMIT_FILL, &permit_fill)) {
+		print_error("INCFS_IOC_PERMIT_FILL failed");
+		return -EPERM;
+		goto out;
+	}
+
 	error = ioctl(fd, INCFS_IOC_GET_FILLED_BLOCKS, &fba);
 	if (error)
 		goto out;
 
+	if (fba.total_blocks_out <= block_cnt) {
+		error = -EINVAL;
+		goto out;
+	}
+
+	if (fba.data_blocks_out != block_cnt) {
+		error = -EINVAL;
+		goto out;
+	}
+
 	if (fba.range_buffer_size_out != sizeof(struct incfs_filled_range)) {
 		error = -EINVAL;
 		goto out;
@@ -2427,6 +2478,7 @@ static int validate_hash_ranges(const char *mount_dir, struct test_file *file)
 	}
 
 out:
+	close(cmd_fd);
 	close(fd);
 	return error;
 }