Re: [PATCH 2/2] f2fs: do more integrity verification for superblock

[Chao Yu <chao2.yu@samsung.com>]

Hi Jaegeuk,

> -----Original Message-----
> From: Jaegeuk Kim [mailto:jaegeuk@kernel.org]
> Sent: Tuesday, December 15, 2015 8:56 AM
> To: Chao Yu
> Cc: linux-f2fs-devel@lists.sourceforge.net; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH 2/2] f2fs: do more integrity verification for superblock
> 
> Hi Chao,
> 
> I also got superblock failure.
> It seems that your patch doesn't handle correctly if segment0_blkaddr is not
> zero.
> Please see below.
> 
> On Fri, Dec 11, 2015 at 04:09:23PM +0800, Chao Yu wrote:
> > Do more sanity check for superblock during ->mount.
> >
> > Signed-off-by: Chao Yu <chao2.yu@samsung.com>
> > ---
> >  fs/f2fs/super.c | 98 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 98 insertions(+)
> >
> > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> > index 5434186..624fc2c 100644
> > --- a/fs/f2fs/super.c
> > +++ b/fs/f2fs/super.c
> > @@ -926,6 +926,79 @@ static loff_t max_file_size(unsigned bits)
> >  	return result;
> >  }
> >
> > +static inline bool sanity_check_area_boundary(struct super_block *sb,
> > +					struct f2fs_super_block *raw_super)
> > +{
> > +	u32 segment0_blkaddr = le32_to_cpu(raw_super->segment0_blkaddr);
> > +	u32 cp_blkaddr = le32_to_cpu(raw_super->cp_blkaddr);
> > +	u32 sit_blkaddr = le32_to_cpu(raw_super->sit_blkaddr);
> > +	u32 nat_blkaddr = le32_to_cpu(raw_super->nat_blkaddr);
> > +	u32 ssa_blkaddr = le32_to_cpu(raw_super->ssa_blkaddr);
> > +	u32 main_blkaddr = le32_to_cpu(raw_super->main_blkaddr);
> > +	u32 segment_count_ckpt = le32_to_cpu(raw_super->segment_count_ckpt);
> > +	u32 segment_count_sit = le32_to_cpu(raw_super->segment_count_sit);
> > +	u32 segment_count_nat = le32_to_cpu(raw_super->segment_count_nat);
> > +	u32 segment_count_ssa = le32_to_cpu(raw_super->segment_count_ssa);
> > +	u32 segment_count_main = le32_to_cpu(raw_super->segment_count_main);
> > +	u32 segment_count = le32_to_cpu(raw_super->segment_count);
> > +	u32 log_blocks_per_seg = le32_to_cpu(raw_super->log_blocks_per_seg);
> > +
> > +	if (segment0_blkaddr != cp_blkaddr) {
> > +		f2fs_msg(sb, KERN_INFO,
> > +			"Mismatch start address, segment0(%u) cp_blkaddr(%u)",
> > +			segment0_blkaddr, cp_blkaddr);
> > +		return true;
> > +	}
> > +
> > +	if (cp_blkaddr + (segment_count_ckpt << log_blocks_per_seg) !=
> > +							sit_blkaddr) {
> > +		f2fs_msg(sb, KERN_INFO,
> > +			"Wrong CP boundary, start(%u) end(%u) blocks(%u)",
> > +			cp_blkaddr, sit_blkaddr,
> > +			segment_count_ckpt << log_blocks_per_seg);
> > +		return true;
> > +	}
> > +
> > +	if (sit_blkaddr + (segment_count_sit << log_blocks_per_seg) !=
> > +							nat_blkaddr) {
> > +		f2fs_msg(sb, KERN_INFO,
> > +			"Wrong SIT boundary, start(%u) end(%u) blocks(%u)",
> > +			sit_blkaddr, nat_blkaddr,
> > +			segment_count_sit << log_blocks_per_seg);
> > +		return true;
> > +	}
> > +
> > +	if (nat_blkaddr + (segment_count_nat << log_blocks_per_seg) !=
> > +							ssa_blkaddr) {
> > +		f2fs_msg(sb, KERN_INFO,
> > +			"Wrong NAT boundary, start(%u) end(%u) blocks(%u)",
> > +			nat_blkaddr, ssa_blkaddr,
> > +			segment_count_nat << log_blocks_per_seg);
> > +		return true;
> > +	}
> > +
> > +	if (ssa_blkaddr + (segment_count_ssa << log_blocks_per_seg) !=
> > +							main_blkaddr) {
> > +		f2fs_msg(sb, KERN_INFO,
> > +			"Wrong SSA boundary, start(%u) end(%u) blocks(%u)",
> > +			ssa_blkaddr, main_blkaddr,
> > +			segment_count_ssa << log_blocks_per_seg);
> > +		return true;
> > +	}
> > +
> > +	if (main_blkaddr + (segment_count_main << log_blocks_per_seg) !=
> > +				(segment_count + 1) << log_blocks_per_seg) {

Oh, zone aligned start offset 'segment0_blkaddr' was calculated based on zone
size, sector size, total sectors. So here it's wrong to use constant '1'.
Sorry for my mistake.

Thanks for your explanation below! :) I will resend the v2 patch.

Thanks,

> 
> This should be
> 		segment_count << log_blocks_per_seg + segment0_blkaddr) {
> 
> 
> =========================================================================
>                            '- main_blkaddr
>     `- segment0_blkaddr
>                            |-------------- segment_count_main ----------|
> 
>     |-------------------------- segment_count --------------------------|
> 
> 
> Thanks,
> 
> > +		f2fs_msg(sb, KERN_INFO,
> > +			"Wrong MAIN_AREA boundary, start(%u) end(%u) blocks(%u)",
> > +			main_blkaddr,
> > +			(segment_count + 1) << log_blocks_per_seg,
> > +			segment_count_main << log_blocks_per_seg);
> > +		return true;
> > +	}
> > +
> > +	return false;
> > +}
> > +
> >  static int sanity_check_raw_super(struct super_block *sb,
> >  			struct f2fs_super_block *raw_super)
> >  {
> > @@ -955,6 +1028,14 @@ static int sanity_check_raw_super(struct super_block *sb,
> >  		return 1;
> >  	}
> >
> > +	/* check log blocks per segment */
> > +	if (le32_to_cpu(raw_super->log_blocks_per_seg) != 9) {
> > +		f2fs_msg(sb, KERN_INFO,
> > +			"Invalid log blocks per segment (%u)\n",
> > +			le32_to_cpu(raw_super->log_blocks_per_seg));
> > +		return 1;
> > +	}
> > +
> >  	/* Currently, support 512/1024/2048/4096 bytes sector size */
> >  	if (le32_to_cpu(raw_super->log_sectorsize) >
> >  				F2FS_MAX_LOG_SECTOR_SIZE ||
> > @@ -973,6 +1054,23 @@ static int sanity_check_raw_super(struct super_block *sb,
> >  			le32_to_cpu(raw_super->log_sectorsize));
> >  		return 1;
> >  	}
> > +
> > +	/* check reserved ino info */
> > +	if (le32_to_cpu(raw_super->node_ino) != 1 ||
> > +		le32_to_cpu(raw_super->meta_ino) != 2 ||
> > +		le32_to_cpu(raw_super->root_ino) != 3) {
> > +		f2fs_msg(sb, KERN_INFO,
> > +			"Invalid Fs Meta Ino: node(%u) meta(%u) root(%u)",
> > +			le32_to_cpu(raw_super->node_ino),
> > +			le32_to_cpu(raw_super->meta_ino),
> > +			le32_to_cpu(raw_super->root_ino));
> > +		return 1;
> > +	}
> > +
> > +	/* check CP/SIT/NAT/SSA/MAIN_AREA area boundary */
> > +	if (sanity_check_area_boundary(sb, raw_super))
> > +		return 1;
> > +
> >  	return 0;
> >  }
> >
> > --
> > 2.6.3
> >


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