Patch for kernel side changes of checksum feature.I used kernel's crc32c library for calculating the checksum.
Signed-off-by: Pratik Shinde <[email protected]> --- fs/erofs/erofs_fs.h | 5 +++-- fs/erofs/internal.h | 2 +- fs/erofs/super.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++---- 3 files changed, 50 insertions(+), 7 deletions(-) diff --git a/fs/erofs/erofs_fs.h b/fs/erofs/erofs_fs.h index b1ee565..bab5506 100644 --- a/fs/erofs/erofs_fs.h +++ b/fs/erofs/erofs_fs.h @@ -17,6 +17,7 @@ */ #define EROFS_FEATURE_INCOMPAT_LZ4_0PADDING 0x00000001 #define EROFS_ALL_FEATURE_INCOMPAT EROFS_FEATURE_INCOMPAT_LZ4_0PADDING +#define EROFS_FEATURE_SB_CHKSUM 0x0001 /* 128-byte erofs on-disk super block */ struct erofs_super_block { @@ -37,8 +38,8 @@ struct erofs_super_block { __u8 uuid[16]; /* 128-bit uuid for volume */ __u8 volume_name[16]; /* volume name */ __le32 feature_incompat; - - __u8 reserved2[44]; + __le32 chksum_blocks; /* number of blocks used for checksum */ + __u8 reserved2[40]; }; /* diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h index 544a453..cd3af45 100644 --- a/fs/erofs/internal.h +++ b/fs/erofs/internal.h @@ -86,7 +86,7 @@ struct erofs_sb_info { u8 uuid[16]; /* 128-bit uuid for volume */ u8 volume_name[16]; /* volume name */ u32 feature_incompat; - + u32 features; unsigned int mount_opt; }; diff --git a/fs/erofs/super.c b/fs/erofs/super.c index 0e36949..94e1d6a 100644 --- a/fs/erofs/super.c +++ b/fs/erofs/super.c @@ -9,6 +9,7 @@ #include <linux/statfs.h> #include <linux/parser.h> #include <linux/seq_file.h> +#include <linux/crc32c.h> #include "xattr.h" #define CREATE_TRACE_POINTS @@ -46,6 +47,45 @@ void _erofs_info(struct super_block *sb, const char *function, va_end(args); } +static int erofs_validate_sb_chksum(struct erofs_super_block *dsb, + struct super_block *sb) +{ + u32 disk_chksum = le32_to_cpu(dsb->checksum); + u32 nblocks = le32_to_cpu(dsb->chksum_blocks); + u32 crc; + struct erofs_super_block *dsb2; + char *buf; + unsigned int off = 0; + void *kaddr; + struct page *page; + int i, ret = -EINVAL; + + buf = kmalloc(nblocks * EROFS_BLKSIZ, GFP_KERNEL); + if (!buf) + goto out; + for (i = 0; i < nblocks; i++) { + page = erofs_get_meta_page(sb, i); + if (IS_ERR(page)) + goto out; + kaddr = kmap_atomic(page); + (void) memcpy(buf + off, kaddr, EROFS_BLKSIZ); + kunmap_atomic(kaddr); + unlock_page(page); + /* first page will be released by erofs_read_superblock */ + if (i != 0) + put_page(page); + off += EROFS_BLKSIZ; + } + dsb2 = (struct erofs_super_block *)(buf + EROFS_SUPER_OFFSET); + dsb2->checksum = 0; + crc = crc32c(0, buf, nblocks * EROFS_BLKSIZ); + if (crc != disk_chksum) + goto out; + ret = 0; +out: kfree(buf); + return ret; +} + static void erofs_inode_init_once(void *ptr) { struct erofs_inode *vi = ptr; @@ -109,18 +149,20 @@ static int erofs_read_superblock(struct super_block *sb) erofs_err(sb, "cannot read erofs superblock"); return PTR_ERR(page); } - sbi = EROFS_SB(sb); - data = kmap_atomic(page); dsb = (struct erofs_super_block *)(data + EROFS_SUPER_OFFSET); - ret = -EINVAL; if (le32_to_cpu(dsb->magic) != EROFS_SUPER_MAGIC_V1) { erofs_err(sb, "cannot find valid erofs superblock"); goto out; } - + if (dsb->feature_compat & EROFS_FEATURE_SB_CHKSUM) { + if (erofs_validate_sb_chksum(dsb, sb)) { + erofs_err(sb, "super block checksum incorrect"); + goto out; + } + } blkszbits = dsb->blkszbits; /* 9(512 bytes) + LOG_SECTORS_PER_BLOCK == LOG_BLOCK_SIZE */ if (blkszbits != LOG_BLOCK_SIZE) { -- 2.9.3
