Messages in this thread | | | Date | Mon, 8 Jun 2020 06:07:34 -0700 | From | Jaegeuk Kim <> | Subject | Re: [f2fs-dev] [PATCH] f2fs: add F2FS_IOC_TRIM_FILE ioctl |
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On 06/08, Chao Yu wrote: > On 2020/6/8 15:19, Daeho Jeong wrote: > > Yes, I agree with you about each vendor has different implementation on discard. > > So, we might be gonna use the combination of zeroing and send discards > > for a more > > secure solution. :) > > IIRC, current solution is: > > - pin file > - get all block addresses of file > - write zero to block addresses > - issue discard > > Is that correct? > > Could we handle those logic (zero out & discard) in new interface > (may be named as {F2FS,EXT4}_IOC_SEC_TRIM_FILE)? then userspace logic > could be quite simple later, and also memcpy could be avoid to make > destruction process more efficient.
What about adding a flag to determine calling unmap and/or zero out?
> > Just raw proposal. :) > > Thanks, > > > I think we still need a discard interface to unmap from the mapping > > table of the storage device side. > > > > Thanks, > > > > 2020년 6월 8일 (월) 오후 3:57, Chao Yu <yuchao0@huawei.com>님이 작성: > >> > >> On 2020/6/8 11:36, Daeho Jeong wrote: > >>> Yes, this is for security key destruction. > >>> > >>> AFAIK, discard will unmap the data block and, after done it, > >>> we can read either zero data or garbage data from that block depending > >>> on eMMC/UFS. > >> > >> Since spec didn't restrict how vendor implement the erase interface, so > >> in order to enhance performance of discard interface, vendor could implement > >> it as an async one, which may not zero mapping entry(L1 table), instead, it > >> could set related bitmap to invalid that mapping entry, than later if device > >> allow user to access that invalid mapping entry, key info may be explosed, > >> > >> It's completely up to how vendor implement the interface, so I think there is > >> still risk to use discard. > >> > >> Thanks, > >> > >>> In a view point of read data, it might be the same with zeroing the data block. > >>> However, since we can even unmap that block, I believe discard is > >>> safer than zeroing out. > >>> > >>> 2020년 6월 8일 (월) 오전 11:46, Chao Yu <yuchao0@huawei.com>님이 작성: > >>>> > >>>> On 2020/6/5 12:27, Daeho Jeong wrote: > >>>>> From: Daeho Jeong <daehojeong@google.com> > >>>>> > >>>>> Added a new ioctl to send discard commands to whole data area of > >>>>> a regular file for security reason. > >>>> > >>>> I guess this interface is introduced for security key destruction, if I'm > >>>> right, however, IIRC, discard(erase) semantics in eMMC/UFS spec won't > >>>> guarantee that data which was discard could be zeroed out, so after discard, > >>>> the key still have risk of exposure. So instead, should we use sb_issue_zeroout()? > >>>> > >>>> Thanks, > >>>> > >>>>> > >>>>> Signed-off-by: Daeho Jeong <daehojeong@google.com> > >>>>> --- > >>>>> fs/f2fs/f2fs.h | 1 + > >>>>> fs/f2fs/file.c | 129 +++++++++++++++++++++++++++++++++++++++++++++++++ > >>>>> 2 files changed, 130 insertions(+) > >>>>> > >>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > >>>>> index c812fb8e2d9c..9ae81d0fefa0 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_TRIM_FILE _IO(F2FS_IOCTL_MAGIC, 20) > >>>>> > >>>>> #define F2FS_IOC_GET_VOLUME_NAME FS_IOC_GETFSLABEL > >>>>> #define F2FS_IOC_SET_VOLUME_NAME FS_IOC_SETFSLABEL > >>>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > >>>>> index dfa1ac2d751a..58507bb5649c 100644 > >>>>> --- a/fs/f2fs/file.c > >>>>> +++ b/fs/f2fs/file.c > >>>>> @@ -3749,6 +3749,132 @@ static int f2fs_reserve_compress_blocks(struct file *filp, unsigned long arg) > >>>>> return ret; > >>>>> } > >>>>> > >>>>> +static int f2fs_trim_file(struct file *filp) > >>>>> +{ > >>>>> + struct inode *inode = file_inode(filp); > >>>>> + struct f2fs_sb_info *sbi = F2FS_I_SB(inode); > >>>>> + struct address_space *mapping = inode->i_mapping; > >>>>> + struct bio *bio = NULL; > >>>>> + struct block_device *prev_bdev = NULL; > >>>>> + loff_t file_size; > >>>>> + pgoff_t index, pg_start = 0, pg_end; > >>>>> + block_t prev_block = 0, len = 0; > >>>>> + int ret = 0; > >>>>> + > >>>>> + if (!f2fs_hw_support_discard(sbi)) > >>>>> + return -EOPNOTSUPP; > >>>>> + > >>>>> + if (!S_ISREG(inode->i_mode) || f2fs_is_atomic_file(inode) || > >>>>> + f2fs_compressed_file(inode)) > >>>>> + return -EINVAL; > >>>>> + > >>>>> + if (f2fs_readonly(sbi->sb)) > >>>>> + return -EROFS; > >>>>> + > >>>>> + ret = mnt_want_write_file(filp); > >>>>> + if (ret) > >>>>> + return ret; > >>>>> + > >>>>> + inode_lock(inode); > >>>>> + > >>>>> + file_size = i_size_read(inode); > >>>>> + if (!file_size) > >>>>> + goto err; > >>>>> + pg_end = (pgoff_t)round_up(file_size, PAGE_SIZE) >> PAGE_SHIFT; > >>>>> + > >>>>> + 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) > >>>>> + 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; > >>>>> + } > >>>>> + } else > >>>>> + 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 = __blkdev_issue_discard(prev_bdev, > >>>>> + SECTOR_FROM_BLOCK(prev_block), > >>>>> + SECTOR_FROM_BLOCK(len), > >>>>> + GFP_NOFS, 0, &bio); > >>>>> + if (ret) > >>>>> + goto out; > >>>>> +> + len = 0; > >>>>> + } > >>>>> + } > >>>>> + > >>>>> + if (!len) { > >>>>> + prev_bdev = cur_bdev; > >>>>> + prev_block = blkaddr; > >>>>> + len = 1; > >>>>> + } > >>>>> + } > >>>>> + > >>>>> + f2fs_put_dnode(&dn); > >>>>> + } > >>>>> + > >>>>> + if (len) > >>>>> + ret = __blkdev_issue_discard(prev_bdev, > >>>>> + SECTOR_FROM_BLOCK(prev_block), > >>>>> + SECTOR_FROM_BLOCK(len), > >>>>> + GFP_NOFS, 0, &bio); > >>>>> +out: > >>>>> + if (bio) { > >>>>> + ret = submit_bio_wait(bio); > >>>>> + bio_put(bio); > >>>>> + } > >>>>> + > >>>>> + up_write(&F2FS_I(inode)->i_mmap_sem); > >>>>> + up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); > >>>>> +err: > >>>>> + inode_unlock(inode); > >>>>> + mnt_drop_write_file(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 +3961,8 @@ 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_TRIM_FILE: > >>>>> + return f2fs_trim_file(filp); > >>>>> default: > >>>>> return -ENOTTY; > >>>>> } > >>>>> @@ -4004,6 +4132,7 @@ 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_TRIM_FILE: > >>>>> break; > >>>>> default: > >>>>> return -ENOIOCTLCMD; > >>>>> > >>> . > >>> > > . > > > > > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
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