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Date: Thu, 11 Jun 2020 16:54:32 +0800
From: Chao Yu <yuchao0@...wei.com>
To: Daeho Jeong <daeho43@...il.com>, <linux-kernel@...r.kernel.org>,
<linux-f2fs-devel@...ts.sourceforge.net>, <kernel-team@...roid.com>
CC: Daeho Jeong <daehojeong@...gle.com>
Subject: Re: [f2fs-dev] [PATCH v2] f2fs: add F2FS_IOC_SEC_TRIM_FILE ioctl
On 2020/6/11 11:16, Daeho Jeong wrote:
> From: Daeho Jeong <daehojeong@...gle.com>
>
> Added a new ioctl to send discard commands or/and zero out
> to whole data area of a regular file for security reason.
>
> Signed-off-by: Daeho Jeong <daehojeong@...gle.com>
> ---
> fs/f2fs/f2fs.h | 8 +++
> fs/f2fs/file.c | 143 +++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 151 insertions(+)
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index c812fb8e2d9c..ca139fac5a73 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -434,6 +434,7 @@ static inline bool __has_cursum_space(struct f2fs_journal *journal,
> _IOR(F2FS_IOCTL_MAGIC, 18, __u64)
> #define F2FS_IOC_RESERVE_COMPRESS_BLOCKS \
> _IOR(F2FS_IOCTL_MAGIC, 19, __u64)
> +#define F2FS_IOC_SEC_TRIM_FILE _IOW(F2FS_IOCTL_MAGIC, 20, __u32)
>
> #define F2FS_IOC_GET_VOLUME_NAME FS_IOC_GETFSLABEL
> #define F2FS_IOC_SET_VOLUME_NAME FS_IOC_SETFSLABEL
> @@ -453,6 +454,13 @@ static inline bool __has_cursum_space(struct f2fs_journal *journal,
> #define F2FS_GOING_DOWN_METAFLUSH 0x3 /* going down with meta flush */
> #define F2FS_GOING_DOWN_NEED_FSCK 0x4 /* going down to trigger fsck */
>
> +/*
> + * Flags used by F2FS_IOC_SEC_TRIM_FILE
> + */
> +#define F2FS_TRIM_FILE_DISCARD 0x1 /* send discard command */
> +#define F2FS_TRIM_FILE_ZEROOUT 0x2 /* zero out */
> +#define F2FS_TRIM_FILE_MASK 0x3
> +
> #if defined(__KERNEL__) && defined(CONFIG_COMPAT)
> /*
> * ioctl commands in 32 bit emulation
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index dfa1ac2d751a..ba9b7ec5d6bf 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -3749,6 +3749,146 @@ static int f2fs_reserve_compress_blocks(struct file *filp, unsigned long arg)
> return ret;
> }
>
> +static int f2fs_secure_erase(struct block_device *bdev, block_t block,
> + block_t len, u32 flags)
> +{
> + struct request_queue *q = bdev_get_queue(bdev);
> + sector_t sector = SECTOR_FROM_BLOCK(block);
> + sector_t nr_sects = SECTOR_FROM_BLOCK(len);
> + int ret = 0;
> +
> + if (!q)
> + return -ENXIO;
> +
> + if (flags & F2FS_TRIM_FILE_DISCARD)
> + ret = blkdev_issue_discard(bdev, sector, nr_sects, GFP_NOFS,
> + blk_queue_secure_erase(q) ?
> + BLKDEV_DISCARD_SECURE : 0);
> +
> + if (!ret && (flags & F2FS_TRIM_FILE_ZEROOUT))
> + ret = blkdev_issue_zeroout(bdev, sector, nr_sects, GFP_NOFS, 0);
> +
> + return ret;
> +}
> +
> +static int f2fs_sec_trim_file(struct file *filp, unsigned long arg)
> +{
> + struct inode *inode = file_inode(filp);
> + struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
> + struct address_space *mapping = inode->i_mapping;
> + struct block_device *prev_bdev = NULL;
> + pgoff_t index, pg_start = 0, pg_end;
> + block_t prev_block = 0, len = 0;
> + u32 flags;
> + int ret = 0;
> +
> + if (!(filp->f_mode & FMODE_WRITE))
> + return -EBADF;
> +
> + if (get_user(flags, (u32 __user *)arg))
> + return -EFAULT;
> + if (flags == 0 || (flags & ~F2FS_TRIM_FILE_MASK))
> + return -EINVAL;
> +
> + if ((flags & F2FS_TRIM_FILE_DISCARD) && !f2fs_hw_support_discard(sbi))
> + return -EOPNOTSUPP;
> +
> + file_start_write(filp);
Now, I'm a little confused about when we need to call __mnt_want_write_file(),
you know, vfs_write() still will call this function when updating time.
- __generic_file_write_iter
- file_update_time
- __mnt_want_write_file
And previously, f2fs ioctl uses mnt_{want,drop}_write_file() whenever there is
any updates on fs/file, if Eric is correct, we need to clean up most of ioctl
interface as well.
> + inode_lock(inode);
> +
> + if (!S_ISREG(inode->i_mode) || f2fs_is_atomic_file(inode) ||
> + f2fs_compressed_file(inode)) {
> + ret = -EINVAL;
> + goto err;
> + }
> +
> + if (!inode->i_size)
> + goto err;
> + pg_end = DIV_ROUND_UP(inode->i_size, PAGE_SIZE);
> +
> + ret = f2fs_convert_inline_inode(inode);
> + if (ret)
> + goto err;
> +
> + down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
> + down_write(&F2FS_I(inode)->i_mmap_sem);
> +
> + ret = filemap_write_and_wait(mapping);
> + if (ret)
> + goto out;
> +
> + truncate_inode_pages(mapping, 0);
> +
> + for (index = pg_start; index < pg_end;) {
> + struct dnode_of_data dn;
> + unsigned int end_offset;
> +
> + set_new_dnode(&dn, inode, NULL, NULL, 0);
> + ret = f2fs_get_dnode_of_data(&dn, index, LOOKUP_NODE);
> + if (ret)
if (ret == -ENOENT) {
index = f2fs_get_next_page_offset(&dn, index);
continue;
}
> + goto out;
> +
> + end_offset = ADDRS_PER_PAGE(dn.node_page, inode);
> + if (pg_end < end_offset + index)
> + end_offset = pg_end - index;
> +
> + for (; dn.ofs_in_node < end_offset;
> + dn.ofs_in_node++, index++) {
> + struct block_device *cur_bdev;
> + block_t blkaddr = f2fs_data_blkaddr(&dn);
> +
> + if (__is_valid_data_blkaddr(blkaddr)) {
> + if (!f2fs_is_valid_blkaddr(F2FS_I_SB(inode),
> + blkaddr, DATA_GENERIC_ENHANCE)) {
> + ret = -EFSCORRUPTED;
> + goto out;
if we goto out label here, we will miss to call f2fs_put_dnode()?
> + }
> + } else
How about this?
if (!__is_valid_data_blkaddr())
continue;
if (!f2fs_is_valid_blkaddr(F2FS_I_SB(inode), blkaddr, DATA_GENERIC_ENHANCE)) {
ret = -EFSCORRUPTED;
goto out;
}
> + continue;
> +
> + cur_bdev = f2fs_target_device(sbi, blkaddr, NULL);
> + if (f2fs_is_multi_device(sbi)) {
> + int i = f2fs_target_device_index(sbi, blkaddr);
> +
> + blkaddr -= FDEV(i).start_blk;
> + }
> +
> + if (len) {
> + if (prev_bdev == cur_bdev &&
> + blkaddr == prev_block + len) {
> + len++;
> + } else {
> + ret = f2fs_secure_erase(prev_bdev,
> + prev_block, len, flags);
> + if (ret)
> + goto out;
Ditto,
Thanks,
> +
> + len = 0;
> + }
> + }
> +
> + if (!len) {
> + prev_bdev = cur_bdev;
> + prev_block = blkaddr;
> + len = 1;
> + }
> + }
> +
> + f2fs_put_dnode(&dn);
> + }
> +
> + if (len)
> + ret = f2fs_secure_erase(prev_bdev, prev_block, len, flags);
> +out:
> + up_write(&F2FS_I(inode)->i_mmap_sem);
> + up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
> +err:
> + inode_unlock(inode);
> + file_end_write(filp);
> +
> + return ret;
> +}
> +
> long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> {
> if (unlikely(f2fs_cp_error(F2FS_I_SB(file_inode(filp)))))
> @@ -3835,6 +3975,8 @@ long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> return f2fs_release_compress_blocks(filp, arg);
> case F2FS_IOC_RESERVE_COMPRESS_BLOCKS:
> return f2fs_reserve_compress_blocks(filp, arg);
> + case F2FS_IOC_SEC_TRIM_FILE:
> + return f2fs_sec_trim_file(filp, arg);
> default:
> return -ENOTTY;
> }
> @@ -4004,6 +4146,7 @@ long f2fs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
> case F2FS_IOC_GET_COMPRESS_BLOCKS:
> case F2FS_IOC_RELEASE_COMPRESS_BLOCKS:
> case F2FS_IOC_RESERVE_COMPRESS_BLOCKS:
> + case F2FS_IOC_SEC_TRIM_FILE:
> break;
> default:
> return -ENOIOCTLCMD;
>
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