Commit 476189c0 authored by Tetsuhiro Kohada's avatar Tetsuhiro Kohada Committed by Namjae Jeon
Browse files

exfat: add boot region verification 



Add Boot-Regions verification specified in exFAT specification.
Note that the checksum type is strongly related to the raw structure,
so the'u32 'type is used to clarify the number of bits.

Signed-off-by: default avatarTetsuhiro Kohada <kohada.t2@gmail.com>
Reviewed-by: default avatarSungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: default avatarNamjae Jeon <namjae.jeon@samsung.com>
parent 33404a15

fs/exfat/exfat_fs.h

+1 −0
Original line number Diff line number Diff line
@@ -514,6 +514,7 @@ void exfat_set_entry_time(struct exfat_sb_info *sbi, struct timespec64 *ts, 
		u8 *tz, __le16 *time, __le16 *date, u8 *time_cs);

unsigned short exfat_calc_chksum_2byte(void *data, int len,

		unsigned short chksum, int type);

u32 exfat_calc_chksum32(void *data, int len, u32 chksum, int type);

void exfat_update_bh(struct super_block *sb, struct buffer_head *bh, int sync);

void exfat_chain_set(struct exfat_chain *ec, unsigned int dir,

		unsigned int size, unsigned char flags);

fs/exfat/misc.c

+14 −0
Original line number Diff line number Diff line
@@ -151,6 +151,20 @@ unsigned short exfat_calc_chksum_2byte(void *data, int len, 
	return chksum;

}



u32 exfat_calc_chksum32(void *data, int len, u32 chksum, int type)

{

	int i;

	u8 *c = (u8 *)data;



	for (i = 0; i < len; i++, c++) {

		if (unlikely(type == CS_BOOT_SECTOR &&

			     (i == 106 || i == 107 || i == 112)))

			continue;

		chksum = ((chksum << 31) | (chksum >> 1)) + *c;

	}

	return chksum;

}



void exfat_update_bh(struct super_block *sb, struct buffer_head *bh, int sync)

{

	set_bit(EXFAT_SB_DIRTY, &EXFAT_SB(sb)->s_state);

fs/exfat/super.c

+50 −0
Original line number Diff line number Diff line
@@ -491,6 +491,50 @@ static int exfat_read_boot_sector(struct super_block *sb) 
	return 0;

}



static int exfat_verify_boot_region(struct super_block *sb)

{

	struct buffer_head *bh = NULL;

	u32 chksum = 0;

	__le32 *p_sig, *p_chksum;

	int sn, i;



	/* read boot sector sub-regions */

	for (sn = 0; sn < 11; sn++) {

		bh = sb_bread(sb, sn);

		if (!bh)

			return -EIO;



		if (sn != 0 && sn <= 8) {

			/* extended boot sector sub-regions */

			p_sig = (__le32 *)&bh->b_data[sb->s_blocksize - 4];

			if (le32_to_cpu(*p_sig) != EXBOOT_SIGNATURE)

				exfat_warn(sb, "Invalid exboot-signature(sector = %d): 0x%08x",

					   sn, le32_to_cpu(*p_sig));

		}



		chksum = exfat_calc_chksum32(bh->b_data, sb->s_blocksize,

			chksum, sn ? CS_DEFAULT : CS_BOOT_SECTOR);

		brelse(bh);

	}



	/* boot checksum sub-regions */

	bh = sb_bread(sb, sn);

	if (!bh)

		return -EIO;



	for (i = 0; i < sb->s_blocksize; i += sizeof(u32)) {

		p_chksum = (__le32 *)&bh->b_data[i];

		if (le32_to_cpu(*p_chksum) != chksum) {

			exfat_err(sb, "Invalid boot checksum (boot checksum : 0x%08x, checksum : 0x%08x)",

				  le32_to_cpu(*p_chksum), chksum);

			brelse(bh);

			return -EINVAL;

		}

	}

	brelse(bh);

	return 0;

}



/* mount the file system volume */

static int __exfat_fill_super(struct super_block *sb)

{
@@ -503,6 +547,12 @@ static int __exfat_fill_super(struct super_block *sb) 
		goto free_bh;

	}



	ret = exfat_verify_boot_region(sb);

	if (ret) {

		exfat_err(sb, "invalid boot region");

		goto free_bh;

	}



	ret = exfat_create_upcase_table(sb);

	if (ret) {

		exfat_err(sb, "failed to load upcase table");

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