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Message-ID: <20120107083522.25788.83355.stgit@elm3c44.beaverton.ibm.com>
Date: Sat, 07 Jan 2012 00:35:22 -0800
From: "Darrick J. Wong" <djwong@...ibm.com>
To: Andreas Dilger <adilger.kernel@...ger.ca>,
Theodore Tso <tytso@....edu>,
"Darrick J. Wong" <djwong@...ibm.com>
Cc: Sunil Mushran <sunil.mushran@...cle.com>,
Amir Goldstein <amir73il@...il.com>,
Andi Kleen <andi@...stfloor.org>,
Mingming Cao <cmm@...ibm.com>,
Joel Becker <jlbec@...lplan.org>, linux-ext4@...r.kernel.org,
Coly Li <colyli@...il.com>
Subject: [PATCH 23/51] libext2fs: Add dx_root/dx_node checksum calculation and
verification helpers
Verify and calculate checksums of htree internal node blocks.
Signed-off-by: Darrick J. Wong <djwong@...ibm.com>
---
lib/ext2fs/csum.c | 149 +++++++++++++++++++++++++++++++++++++++++++++
lib/ext2fs/ext2_err.et.in | 3 +
lib/ext2fs/ext2fs.h | 4 +
3 files changed, 156 insertions(+), 0 deletions(-)
diff --git a/lib/ext2fs/csum.c b/lib/ext2fs/csum.c
index 8a0543c..8907459 100644
--- a/lib/ext2fs/csum.c
+++ b/lib/ext2fs/csum.c
@@ -30,6 +30,155 @@
#define STATIC static
#endif
+static __u16 do_nothing16(__u16 x)
+{
+ return x;
+}
+
+static __u16 disk_to_host16(__u16 x)
+{
+ return ext2fs_le16_to_cpu(x);
+}
+
+static errcode_t __get_dx_countlimit(ext2_filsys fs,
+ struct ext2_dir_entry *dirent,
+ struct ext2_dx_countlimit **cc,
+ int *offset,
+ int need_swab)
+{
+ struct ext2_dir_entry *dp;
+ struct ext2_dx_root_info *root;
+ struct ext2_dx_countlimit *c;
+ int count_offset, max_sane_entries;
+ unsigned int rec_len;
+ __u16 (*translate)(__u16) = (need_swab ? disk_to_host16 : do_nothing16);
+
+ rec_len = translate(dirent->rec_len);
+
+ if (rec_len == fs->blocksize && translate(dirent->name_len) == 0)
+ count_offset = 8;
+ else if (rec_len == 12) {
+ dp = (struct ext2_dir_entry *)(((void *)dirent) + rec_len);
+ rec_len = translate(dp->rec_len);
+ if (rec_len != fs->blocksize - 12)
+ return EXT2_ET_DB_NOT_FOUND;
+ root = (struct ext2_dx_root_info *)(((void *)dp + 12));
+ if (root->reserved_zero ||
+ root->info_length != sizeof(struct ext2_dx_root_info))
+ return EXT2_ET_DB_NOT_FOUND;
+ count_offset = 32;
+ } else
+ return EXT2_ET_DB_NOT_FOUND;
+
+ c = (struct ext2_dx_countlimit *)(((void *)dirent) + count_offset);
+ max_sane_entries = (fs->blocksize - count_offset) /
+ sizeof(struct ext2_dx_entry);
+ if (ext2fs_le16_to_cpu(c->limit) > max_sane_entries ||
+ ext2fs_le16_to_cpu(c->count) > max_sane_entries)
+ return EXT2_ET_DIR_NO_SPACE_FOR_CSUM;
+
+ if (offset)
+ *offset = count_offset;
+ if (cc)
+ *cc = c;
+
+ return 0;
+}
+
+errcode_t ext2fs_get_dx_countlimit(ext2_filsys fs,
+ struct ext2_dir_entry *dirent,
+ struct ext2_dx_countlimit **cc,
+ int *offset)
+{
+ return __get_dx_countlimit(fs, dirent, cc, offset, 0);
+}
+
+static errcode_t ext2fs_dx_csum(ext2_filsys fs, ext2_ino_t inum,
+ struct ext2_dir_entry *dirent,
+ __u32 *crc, int count_offset, int count,
+ struct ext2_dx_tail *t)
+{
+ errcode_t retval;
+ char *buf = (char *)dirent;
+ int size;
+ __u32 old_csum, gen;
+ struct ext2_inode inode;
+
+ size = count_offset + (count * sizeof(struct ext2_dx_entry));
+ old_csum = t->dt_checksum;
+ t->dt_checksum = 0;
+
+ retval = ext2fs_read_inode(fs, inum, &inode);
+ if (retval)
+ return retval;
+
+ inum = ext2fs_cpu_to_le32(inum);
+ gen = ext2fs_cpu_to_le32(inode.i_generation);
+ *crc = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)&inum,
+ sizeof(inum));
+ *crc = ext2fs_crc32c_le(*crc, (unsigned char *)&gen, sizeof(gen));
+ *crc = ext2fs_crc32c_le(*crc, (unsigned char *)buf, size);
+ *crc = ext2fs_crc32c_le(*crc, (unsigned char *)t,
+ sizeof(struct ext2_dx_tail));
+ t->dt_checksum = old_csum;
+
+ return 0;
+}
+
+static int ext2fs_dx_csum_verify(ext2_filsys fs, ext2_ino_t inum,
+ struct ext2_dir_entry *dirent)
+{
+ __u32 calculated;
+ errcode_t retval;
+ struct ext2_dx_countlimit *c;
+ struct ext2_dx_tail *t;
+ int count_offset, limit, count;
+
+ retval = __get_dx_countlimit(fs, dirent, &c, &count_offset, 1);
+ if (retval)
+ return 1;
+ limit = ext2fs_le16_to_cpu(c->limit);
+ count = ext2fs_le16_to_cpu(c->count);
+ if (count_offset + (limit * sizeof(struct ext2_dx_entry)) >
+ fs->blocksize - sizeof(struct ext2_dx_tail))
+ return 0;
+ /* htree structs are accessed in LE order */
+ t = (struct ext2_dx_tail *)(((struct ext2_dx_entry *)c) + limit);
+ retval = ext2fs_dx_csum(fs, inum, dirent, &calculated, count_offset,
+ count, t);
+ if (retval)
+ return 0;
+
+ return ext2fs_le32_to_cpu(t->dt_checksum) == calculated;
+}
+
+static errcode_t ext2fs_dx_csum_set(ext2_filsys fs, ext2_ino_t inum,
+ struct ext2_dir_entry *dirent)
+{
+ __u32 crc;
+ errcode_t retval = 0;
+ struct ext2_dx_countlimit *c;
+ struct ext2_dx_tail *t;
+ int count_offset, limit, count;
+
+ retval = __get_dx_countlimit(fs, dirent, &c, &count_offset, 1);
+ if (retval)
+ return retval;
+ limit = ext2fs_le16_to_cpu(c->limit);
+ count = ext2fs_le16_to_cpu(c->count);
+ if (count_offset + (limit * sizeof(struct ext2_dx_entry)) >
+ fs->blocksize - sizeof(struct ext2_dx_tail))
+ return EXT2_ET_DIR_NO_SPACE_FOR_CSUM;
+ t = (struct ext2_dx_tail *)(((struct ext2_dx_entry *)c) + limit);
+
+ /* htree structs are accessed in LE order */
+ retval = ext2fs_dx_csum(fs, inum, dirent, &crc, count_offset, count, t);
+ if (retval)
+ return retval;
+ t->dt_checksum = ext2fs_cpu_to_le32(crc);
+ return retval;
+}
+
#define EXT3_EXTENT_TAIL_OFFSET(hdr) (sizeof(struct ext3_extent_header) + \
(sizeof(struct ext3_extent) * ext2fs_le16_to_cpu((hdr)->eh_max)))
diff --git a/lib/ext2fs/ext2_err.et.in b/lib/ext2fs/ext2_err.et.in
index 9019026..1e51384 100644
--- a/lib/ext2fs/ext2_err.et.in
+++ b/lib/ext2fs/ext2_err.et.in
@@ -452,4 +452,7 @@ ec EXT2_ET_INODE_BITMAP_CSUM_INVALID,
ec EXT2_ET_EXTENT_CSUM_INVALID,
"Extent block checksum does not match extent block"
+ec EXT2_ET_DIR_NO_SPACE_FOR_CSUM,
+ "Directory block does not have space for checksum"
+
end
diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index 5fa809a..5943ecc 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -943,6 +943,10 @@ extern __u32 ext2fs_crc32c_be(__u32 crc, unsigned char const *p, size_t len);
extern __u32 ext2fs_crc32c_le(__u32 crc, unsigned char const *p, size_t len);
/* csum.c */
+extern errcode_t ext2fs_get_dx_countlimit(ext2_filsys fs,
+ struct ext2_dir_entry *dirent,
+ struct ext2_dx_countlimit **cc,
+ int *offset);
extern errcode_t ext2fs_extent_block_csum_set(ext2_filsys fs,
ext2_ino_t inum,
struct ext3_extent_header *eh);
--
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