diff options
Diffstat (limited to 'fs/ext4/super.c')
| -rw-r--r-- | fs/ext4/super.c | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/fs/ext4/super.c b/fs/ext4/super.c index e2bdf93693a6..dd4ff9c87358 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -37,12 +37,14 @@ #include <linux/quotaops.h> #include <linux/seq_file.h> #include <linux/log2.h> +#include <linux/crc16.h> #include <asm/uaccess.h> #include "xattr.h" #include "acl.h" #include "namei.h" +#include "group.h" static int ext4_load_journal(struct super_block *, struct ext4_super_block *, unsigned long journal_devnum); @@ -1308,6 +1310,43 @@ static int ext4_setup_super(struct super_block *sb, struct ext4_super_block *es, return res; } +__le16 ext4_group_desc_csum(struct ext4_sb_info *sbi, __u32 block_group, + struct ext4_group_desc *gdp) +{ + __u16 crc = 0; + + if (sbi->s_es->s_feature_ro_compat & + cpu_to_le32(EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) { + int offset = offsetof(struct ext4_group_desc, bg_checksum); + __le32 le_group = cpu_to_le32(block_group); + + crc = crc16(~0, sbi->s_es->s_uuid, sizeof(sbi->s_es->s_uuid)); + crc = crc16(crc, (__u8 *)&le_group, sizeof(le_group)); + crc = crc16(crc, (__u8 *)gdp, offset); + offset += sizeof(gdp->bg_checksum); /* skip checksum */ + /* for checksum of struct ext4_group_desc do the rest...*/ + if ((sbi->s_es->s_feature_incompat & + cpu_to_le32(EXT4_FEATURE_INCOMPAT_64BIT)) && + offset < le16_to_cpu(sbi->s_es->s_desc_size)) + crc = crc16(crc, (__u8 *)gdp + offset, + le16_to_cpu(sbi->s_es->s_desc_size) - + offset); + } + + return cpu_to_le16(crc); +} + +int ext4_group_desc_csum_verify(struct ext4_sb_info *sbi, __u32 block_group, + struct ext4_group_desc *gdp) +{ + if ((sbi->s_es->s_feature_ro_compat & + cpu_to_le32(EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) && + (gdp->bg_checksum != ext4_group_desc_csum(sbi, block_group, gdp))) + return 0; + + return 1; +} + /* Called at mount-time, super-block is locked */ static int ext4_check_descriptors (struct super_block * sb) { @@ -1362,6 +1401,14 @@ static int ext4_check_descriptors (struct super_block * sb) i, inode_table); return 0; } + if (!ext4_group_desc_csum_verify(sbi, i, gdp)) { + ext4_error(sb, __FUNCTION__, + "Checksum for group %d failed (%u!=%u)\n", i, + le16_to_cpu(ext4_group_desc_csum(sbi, i, + gdp)), + le16_to_cpu(gdp->bg_checksum)); + return 0; + } first_block += EXT4_BLOCKS_PER_GROUP(sb); gdp = (struct ext4_group_desc *) ((__u8 *)gdp + EXT4_DESC_SIZE(sb)); |