| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <87zjjpvq2x.fsf@devron.myhome.or.jp>
Date: Sun, 13 Apr 2014 12:57:42 +0900
From: OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
To: Conrad Meyer <cemeyer@...edu>
Cc: linux-kernel@...r.kernel.org, Conrad Meyer <cse.cem@...il.com>
Subject: Re: [PATCH v4] fs: FAT: Add support for DOS 1.x formatted volumes
Conrad Meyer <cemeyer@...edu> writes:
Hi,
Sorry for late reply.
> +
> + bd_sects = part_nr_sects_read(sb->s_bdev->bd_part);
This would be better to use i_read_size(&sb->s_bdev->bd_inode->i_size)
> + if (!fat_bpb_is_zero(b)) {
> + fat_msg(sb, KERN_ERR, "%s; DOS 2.x BPB is non-zero",
> + notdos1x);
> + brelse(bh);
> + goto out_invalid;
> + }
Please don't message if silent. While auto detection, user don't want to
see message from kernel.
> + if (sbi->options.dos1xfloppy) {
> + /* 16-bit DOS 1.x reliably wrote bootstrap short-jmp code */
> + if (b->ignored[0] != 0xeb || b->ignored[2] != 0x90) {
> + fat_msg(sb, KERN_ERR, "%s; no bootstrapping code",
> + notdos1x);
> + brelse(bh);
> + goto out_invalid;
> + }
[...]
Looks like I was not explain my suggestion correctly. I was intended to
allow dos1xfloppy by option, not allow dos1xfloppy only.
I.e.
err = read-from-bpb();
if (err == -ENOTFATFS)
if (dos1xfloppy)
err = read-from-static-bpb();
if (err)
goto error;
> + if (sbi->options.dos1xfloppy)
> + total_sectors = fdefaults->nr_sectors;
> + else
> + total_sectors = get_unaligned_le16(&b->sectors);
> if (total_sectors == 0)
> total_sectors = le32_to_cpu(b->total_sect);
Can we make 2 helpers to read from BPB and static BPB? If possible, we
would not be bothered by if (dos1xfloppy), like above crappy pseudo.
Thanks.
--
OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
> +
> + for (i = 0; i < ARRAY_SIZE(floppy_defaults); i++) {
> + if (floppy_defaults[i].nr_sectors == bd_sects) {
> + fdefaults = &floppy_defaults[i];
> + break;
> + }
> + }
> +
> + if (fdefaults == NULL) {
> + fat_msg(sb, KERN_WARNING,
> + "This looks like a DOS 1.x volume, but isn't a recognized floppy size (%llu sectors)",
> + (u64)bd_sects);
> + brelse(bh);
> + goto out_invalid;
> + }
> +
> + fat_msg(sb, KERN_INFO,
> + "This looks like a DOS 1.x volume; assuming default BPB values");
> + } else {
> + if (!b->reserved) {
> + if (!silent)
> + fat_msg(sb, KERN_ERR,
> + "bogus number of reserved sectors");
> + brelse(bh);
> + goto out_invalid;
> + }
> + if (!b->fats) {
> + if (!silent)
> + fat_msg(sb, KERN_ERR,
> + "bogus number of FAT structure");
> + brelse(bh);
> + goto out_invalid;
> + }
> }
>
> /*
> @@ -1397,6 +1510,8 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
> */
>
> media = b->media;
> + if (sbi->options.dos1xfloppy)
> + media = fdefaults->media;
> if (!fat_valid_media(media)) {
> if (!silent)
> fat_msg(sb, KERN_ERR, "invalid media value (0x%02x)",
> @@ -1404,7 +1519,10 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
> brelse(bh);
> goto out_invalid;
> }
> - logical_sector_size = get_unaligned_le16(&b->sector_size);
> + if (sbi->options.dos1xfloppy)
> + logical_sector_size = SECTOR_SIZE;
> + else
> + logical_sector_size = get_unaligned_le16(&b->sector_size);
> if (!is_power_of_2(logical_sector_size)
> || (logical_sector_size < 512)
> || (logical_sector_size > 4096)) {
> @@ -1414,7 +1532,10 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
> brelse(bh);
> goto out_invalid;
> }
> - sbi->sec_per_clus = b->sec_per_clus;
> + if (sbi->options.dos1xfloppy)
> + sbi->sec_per_clus = fdefaults->sec_per_clus;
> + else
> + sbi->sec_per_clus = b->sec_per_clus;
> if (!is_power_of_2(sbi->sec_per_clus)) {
> if (!silent)
> fat_msg(sb, KERN_ERR, "bogus sectors per cluster %u",
> @@ -1450,10 +1571,18 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
> mutex_init(&sbi->s_lock);
> sbi->cluster_size = sb->s_blocksize * sbi->sec_per_clus;
> sbi->cluster_bits = ffs(sbi->cluster_size) - 1;
> - sbi->fats = b->fats;
> + if (sbi->options.dos1xfloppy)
> + sbi->fats = 2;
> + else
> + sbi->fats = b->fats;
> sbi->fat_bits = 0; /* Don't know yet */
> - sbi->fat_start = le16_to_cpu(b->reserved);
> - sbi->fat_length = le16_to_cpu(b->fat_length);
> + if (sbi->options.dos1xfloppy) {
> + sbi->fat_start = 1;
> + sbi->fat_length = fdefaults->fat_length;
> + } else {
> + sbi->fat_start = le16_to_cpu(b->reserved);
> + sbi->fat_length = le16_to_cpu(b->fat_length);
> + }
> sbi->root_cluster = 0;
> sbi->free_clusters = -1; /* Don't know yet */
> sbi->free_clus_valid = 0;
> @@ -1515,7 +1644,10 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
> sbi->dir_per_block_bits = ffs(sbi->dir_per_block) - 1;
>
> sbi->dir_start = sbi->fat_start + sbi->fats * sbi->fat_length;
> - sbi->dir_entries = get_unaligned_le16(&b->dir_entries);
> + if (sbi->options.dos1xfloppy)
> + sbi->dir_entries = fdefaults->dir_entries;
> + else
> + sbi->dir_entries = get_unaligned_le16(&b->dir_entries);
> if (sbi->dir_entries & (sbi->dir_per_block - 1)) {
> if (!silent)
> fat_msg(sb, KERN_ERR, "bogus directory-entries per block"
> @@ -1527,7 +1659,10 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
> rootdir_sectors = sbi->dir_entries
> * sizeof(struct msdos_dir_entry) / sb->s_blocksize;
> sbi->data_start = sbi->dir_start + rootdir_sectors;
> - total_sectors = get_unaligned_le16(&b->sectors);
> + if (sbi->options.dos1xfloppy)
> + total_sectors = fdefaults->nr_sectors;
> + else
> + total_sectors = get_unaligned_le16(&b->sectors);
> if (total_sectors == 0)
> total_sectors = le32_to_cpu(b->total_sect);
--
OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists