From: "Darrick J. Wong" Subject: [PATCH 13/16] ext4: Calculate and verify checksums of extended attribute blocks Date: Wed, 31 Aug 2011 17:32:00 -0700 Message-ID: <20110901003200.31048.70117.stgit@elm3c44.beaverton.ibm.com> References: <20110901003030.31048.99467.stgit@elm3c44.beaverton.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: Sunil Mushran , Amir Goldstein , linux-kernel , Andi Kleen , Mingming Cao , Joel Becker , linux-fsdevel , linux-ext4@vger.kernel.org, Coly Li To: Andreas Dilger , Theodore Tso , "Darrick J. Wong" Return-path: In-Reply-To: <20110901003030.31048.99467.stgit@elm3c44.beaverton.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org Calculate and verify the checksums of extended attribute blocks. This only applies to separate EA blocks that are pointed to by inode->i_file_acl (i.e. external EA blocks); the checksum lives in the EA header. Signed-off-by: Darrick J. Wong --- fs/ext4/xattr.c | 88 ++++++++++++++++++++++++++++++++++++++++++++++--------- fs/ext4/xattr.h | 3 +- 2 files changed, 76 insertions(+), 15 deletions(-) diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c index c757adc..2825e59 100644 --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -56,6 +56,7 @@ #include #include #include +#include #include "ext4_jbd2.h" #include "ext4.h" #include "xattr.h" @@ -122,6 +123,58 @@ const struct xattr_handler *ext4_xattr_handlers[] = { NULL }; +static __le32 ext4_xattr_block_csum(struct inode *inode, + sector_t block_nr, + struct ext4_xattr_header *hdr) +{ + struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); + int offset = offsetof(struct ext4_xattr_header, h_checksum); + __u32 crc = 0; + + if (!EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb, + EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) + return 0; + + block_nr = cpu_to_le64(block_nr); + crc = crc32c_le(~0, sbi->s_es->s_uuid, sizeof(sbi->s_es->s_uuid)); + crc = crc32c_le(crc, (__u8 *)&block_nr, sizeof(block_nr)); + crc = crc32c_le(crc, (__u8 *)hdr, offset); + offset += sizeof(hdr->h_checksum); /* skip checksum */ + crc = crc32c_le(crc, (__u8 *)hdr + offset, + EXT4_BLOCK_SIZE(inode->i_sb) - offset); + return cpu_to_le32(crc); +} + +static int ext4_xattr_block_csum_verify(struct inode *inode, + sector_t block_nr, + struct ext4_xattr_header *hdr) +{ + if (EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb, + EXT4_FEATURE_RO_COMPAT_METADATA_CSUM) && + (hdr->h_checksum != ext4_xattr_block_csum(inode, block_nr, hdr))) + return 0; + return 1; +} + +static void ext4_xattr_block_csum_set(struct inode *inode, + sector_t block_nr, + struct ext4_xattr_header *hdr) +{ + if (!EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb, + EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) + return; + + hdr->h_checksum = ext4_xattr_block_csum(inode, block_nr, hdr); +} + +static inline int ext4_handle_dirty_xattr_block(handle_t *handle, + struct inode *inode, + struct buffer_head *bh) +{ + ext4_xattr_block_csum_set(inode, bh->b_blocknr, BHDR(bh)); + return ext4_handle_dirty_metadata(handle, inode, bh); +} + static inline const struct xattr_handler * ext4_xattr_handler(int name_index) { @@ -156,14 +209,21 @@ ext4_xattr_check_names(struct ext4_xattr_entry *entry, void *end) } static inline int -ext4_xattr_check_block(struct buffer_head *bh) +ext4_xattr_check_block(struct inode *inode, struct buffer_head *bh) { int error; + if (buffer_verified(bh)) + return 0; + if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) || BHDR(bh)->h_blocks != cpu_to_le32(1)) return -EIO; + if (!ext4_xattr_block_csum_verify(inode, bh->b_blocknr, BHDR(bh))) + return -EIO; error = ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size); + if (!error) + set_buffer_verified(bh); return error; } @@ -226,7 +286,7 @@ ext4_xattr_block_get(struct inode *inode, int name_index, const char *name, goto cleanup; ea_bdebug(bh, "b_count=%d, refcount=%d", atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount)); - if (ext4_xattr_check_block(bh)) { + if (ext4_xattr_check_block(inode, bh)) { bad_block: EXT4_ERROR_INODE(inode, "bad block %llu", EXT4_I(inode)->i_file_acl); @@ -370,7 +430,7 @@ ext4_xattr_block_list(struct dentry *dentry, char *buffer, size_t buffer_size) goto cleanup; ea_bdebug(bh, "b_count=%d, refcount=%d", atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount)); - if (ext4_xattr_check_block(bh)) { + if (ext4_xattr_check_block(inode, bh)) { EXT4_ERROR_INODE(inode, "bad block %llu", EXT4_I(inode)->i_file_acl); error = -EIO; @@ -489,7 +549,7 @@ ext4_xattr_release_block(handle_t *handle, struct inode *inode, EXT4_FREE_BLOCKS_FORGET); } else { le32_add_cpu(&BHDR(bh)->h_refcount, -1); - error = ext4_handle_dirty_metadata(handle, inode, bh); + error = ext4_handle_dirty_xattr_block(handle, inode, bh); if (IS_SYNC(inode)) ext4_handle_sync(handle); dquot_free_block(inode, 1); @@ -662,7 +722,7 @@ ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i, ea_bdebug(bs->bh, "b_count=%d, refcount=%d", atomic_read(&(bs->bh->b_count)), le32_to_cpu(BHDR(bs->bh)->h_refcount)); - if (ext4_xattr_check_block(bs->bh)) { + if (ext4_xattr_check_block(inode, bs->bh)) { EXT4_ERROR_INODE(inode, "bad block %llu", EXT4_I(inode)->i_file_acl); error = -EIO; @@ -725,9 +785,9 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode, if (error == -EIO) goto bad_block; if (!error) - error = ext4_handle_dirty_metadata(handle, - inode, - bs->bh); + error = ext4_handle_dirty_xattr_block(handle, + inode, + bs->bh); if (error) goto cleanup; goto inserted; @@ -796,9 +856,9 @@ inserted: ea_bdebug(new_bh, "reusing; refcount now=%d", le32_to_cpu(BHDR(new_bh)->h_refcount)); unlock_buffer(new_bh); - error = ext4_handle_dirty_metadata(handle, - inode, - new_bh); + error = ext4_handle_dirty_xattr_block(handle, + inode, + new_bh); if (error) goto cleanup_dquot; } @@ -848,8 +908,8 @@ getblk_failed: set_buffer_uptodate(new_bh); unlock_buffer(new_bh); ext4_xattr_cache_insert(new_bh); - error = ext4_handle_dirty_metadata(handle, - inode, new_bh); + error = ext4_handle_dirty_xattr_block(handle, + inode, new_bh); if (error) goto cleanup; } @@ -1190,7 +1250,7 @@ retry: error = -EIO; if (!bh) goto cleanup; - if (ext4_xattr_check_block(bh)) { + if (ext4_xattr_check_block(inode, bh)) { EXT4_ERROR_INODE(inode, "bad block %llu", EXT4_I(inode)->i_file_acl); error = -EIO; diff --git a/fs/ext4/xattr.h b/fs/ext4/xattr.h index 25b7387..b2b20af 100644 --- a/fs/ext4/xattr.h +++ b/fs/ext4/xattr.h @@ -27,7 +27,8 @@ struct ext4_xattr_header { __le32 h_refcount; /* reference count */ __le32 h_blocks; /* number of disk blocks used */ __le32 h_hash; /* hash value of all attributes */ - __u32 h_reserved[4]; /* zero right now */ + __le32 h_checksum; /* crc32c(uuid+inum+xattrblock) */ + __u32 h_reserved[3]; /* zero right now */ }; struct ext4_xattr_ibody_header {