From: "Darrick J. Wong" Subject: [PATCH 18/23] jbd2: Checksum journal superblock Date: Sat, 07 Jan 2012 00:29:53 -0800 Message-ID: <20120107082953.21970.97151.stgit@elm3c44.beaverton.ibm.com> References: <20120107082751.21970.84856.stgit@elm3c44.beaverton.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: Sunil Mushran , Martin K Petersen , Greg Freemyer , 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: <20120107082751.21970.84856.stgit@elm3c44.beaverton.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org Calculate and verify a checksum covering the journal superblock. Signed-off-by: Darrick J. Wong --- fs/jbd2/journal.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/jbd2.h | 3 +++ 2 files changed, 53 insertions(+), 0 deletions(-) diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c index bb7f03f..bc80533 100644 --- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -109,6 +109,34 @@ int jbd2_verify_csum_type(journal_t *j, journal_superblock_t *sb) return sb->s_checksum_type == JBD2_CRC32C_CHKSUM; } +static __u32 jbd2_superblock_csum(journal_t *j, journal_superblock_t *sb) +{ + __u32 csum, old_csum; + + old_csum = sb->s_checksum; + sb->s_checksum = 0; + csum = jbd2_chksum(j, ~0, (char *)sb, sizeof(journal_superblock_t)); + sb->s_checksum = old_csum; + + return cpu_to_be32(csum); +} + +int jbd2_superblock_csum_verify(journal_t *j, journal_superblock_t *sb) +{ + if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2)) + return 1; + + return sb->s_checksum == jbd2_superblock_csum(j, sb); +} + +void jbd2_superblock_csum_set(journal_t *j, journal_superblock_t *sb) +{ + if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2)) + return; + + sb->s_checksum = jbd2_superblock_csum(j, sb); +} + /* * Helper function used to manage commit timeouts */ @@ -1178,6 +1206,7 @@ void jbd2_journal_update_superblock(journal_t *journal, int wait) sb->s_sequence = cpu_to_be32(journal->j_tail_sequence); sb->s_start = cpu_to_be32(journal->j_tail); sb->s_errno = cpu_to_be32(journal->j_errno); + jbd2_superblock_csum_set(journal, sb); read_unlock(&journal->j_state_lock); BUFFER_TRACE(bh, "marking dirty"); @@ -1295,6 +1324,17 @@ static int journal_get_superblock(journal_t *journal) } } + /* Check superblock checksum */ + if (!jbd2_superblock_csum_verify(journal, sb)) { + printk(KERN_ERR "JBD: journal checksum error\n"); + goto out; + } + + /* Precompute checksum seed for all metadata */ + if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2)) + journal->j_csum_seed = jbd2_chksum(journal, ~0, sb->s_uuid, + sizeof(sb->s_uuid)); + set_buffer_verified(bh); return 0; @@ -1581,6 +1621,13 @@ int jbd2_journal_set_features (journal_t *journal, unsigned long compat, return 0; } } + + /* Precompute checksum seed for all metadata */ + if (JBD2_HAS_INCOMPAT_FEATURE(journal, + JBD2_FEATURE_INCOMPAT_CSUM_V2)) + journal->j_csum_seed = jbd2_chksum(journal, ~0, + sb->s_uuid, + sizeof(sb->s_uuid)); } /* If enabling v1 checksums, downgrade superblock */ @@ -1591,6 +1638,7 @@ int jbd2_journal_set_features (journal_t *journal, unsigned long compat, sb->s_feature_compat |= cpu_to_be32(compat); sb->s_feature_ro_compat |= cpu_to_be32(ro); sb->s_feature_incompat |= cpu_to_be32(incompat); + jbd2_journal_update_superblock(journal, 0); return 1; #undef COMPAT_FEATURE_ON @@ -1621,6 +1669,7 @@ void jbd2_journal_clear_features(journal_t *journal, unsigned long compat, sb->s_feature_compat &= ~cpu_to_be32(compat); sb->s_feature_ro_compat &= ~cpu_to_be32(ro); sb->s_feature_incompat &= ~cpu_to_be32(incompat); + jbd2_journal_update_superblock(journal, 0); } EXPORT_SYMBOL(jbd2_journal_clear_features); @@ -1669,6 +1718,7 @@ static int journal_convert_superblock_v1(journal_t *journal, sb->s_nr_users = cpu_to_be32(1); sb->s_header.h_blocktype = cpu_to_be32(JBD2_SUPERBLOCK_V2); + jbd2_superblock_csum_set(journal, sb); journal->j_format_version = 2; bh = journal->j_sb_buffer; diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h index 5b2abf9..51d4a0b 100644 --- a/include/linux/jbd2.h +++ b/include/linux/jbd2.h @@ -969,6 +969,9 @@ struct journal_s /* Reference to checksum algorithm driver via cryptoapi */ struct crypto_shash *j_chksum_driver; + + /* Precomputed journal UUID checksum for seeding other checksums */ + __u32 j_csum_seed; }; /*