Disable recalculating if we use internal_hash or journal_hash with a key and we don't have the "legacy_recalculate" flag.
This may break activations of volumes that were created by an older kernel and that are not yet fully recalculated - if this happens, the user should add the "legacy_recalculate" flag to constructor parameters. Signed-off-by: Mikulas Patocka <[email protected]> Reported-by: Daniel Glockner <[email protected]> Index: linux-2.6/drivers/md/dm-integrity.c =================================================================== --- linux-2.6.orig/drivers/md/dm-integrity.c +++ linux-2.6/drivers/md/dm-integrity.c @@ -257,8 +257,9 @@ struct dm_integrity_c { bool journal_uptodate; bool just_formatted; bool recalculate_flag; - bool fix_padding; bool discard; + bool fix_padding; + bool legacy_recalculate; struct alg_spec internal_hash_alg; struct alg_spec journal_crypt_alg; @@ -386,6 +387,14 @@ static int dm_integrity_failed(struct dm return READ_ONCE(ic->failed); } +static bool dm_integrity_disable_recalculate(struct dm_integrity_c *ic) +{ + if ((ic->internal_hash_alg.key || ic->journal_mac_alg.key) && + !ic->legacy_recalculate) + return true; + return false; +} + static commit_id_t dm_integrity_commit_id(struct dm_integrity_c *ic, unsigned i, unsigned j, unsigned char seq) { @@ -3140,6 +3149,7 @@ static void dm_integrity_status(struct d arg_count += !!ic->journal_crypt_alg.alg_string; arg_count += !!ic->journal_mac_alg.alg_string; arg_count += (ic->sb->flags & cpu_to_le32(SB_FLAG_FIXED_PADDING)) != 0; + arg_count += ic->legacy_recalculate; DMEMIT("%s %llu %u %c %u", ic->dev->name, ic->start, ic->tag_size, ic->mode, arg_count); if (ic->meta_dev) @@ -3163,6 +3173,8 @@ static void dm_integrity_status(struct d } if ((ic->sb->flags & cpu_to_le32(SB_FLAG_FIXED_PADDING)) != 0) DMEMIT(" fix_padding"); + if (ic->legacy_recalculate) + DMEMIT(" legacy_recalculate"); #define EMIT_ALG(a, n) \ do { \ @@ -3792,7 +3804,7 @@ static int dm_integrity_ctr(struct dm_ta unsigned extra_args; struct dm_arg_set as; static const struct dm_arg _args[] = { - {0, 15, "Invalid number of feature args"}, + {0, 16, "Invalid number of feature args"}, }; unsigned journal_sectors, interleave_sectors, buffer_sectors, journal_watermark, sync_msec; bool should_write_sb; @@ -3940,6 +3952,8 @@ static int dm_integrity_ctr(struct dm_ta ic->discard = true; } else if (!strcmp(opt_string, "fix_padding")) { ic->fix_padding = true; + } else if (!strcmp(opt_string, "legacy_recalculate")) { + ic->legacy_recalculate = true; } else { r = -EINVAL; ti->error = "Invalid argument"; @@ -4243,6 +4257,14 @@ try_smaller_buffer: } } + if (ic->sb->flags & cpu_to_le32(SB_FLAG_RECALCULATING) && + le64_to_cpu(ic->sb->recalc_sector) < ic->provided_data_sectors && + dm_integrity_disable_recalculate(ic)) { + ti->error = "Recalculating with HMAC is disabled for security reasons - if you really need it, use the argument \"legacy_recalculate\""; + r = -EOPNOTSUPP; + goto bad; + } + ic->bufio = dm_bufio_client_create(ic->meta_dev ? ic->meta_dev->bdev : ic->dev->bdev, 1U << (SECTOR_SHIFT + ic->log2_buffer_sectors), 1, 0, NULL, NULL); if (IS_ERR(ic->bufio)) { Index: linux-2.6/Documentation/admin-guide/device-mapper/dm-integrity.rst =================================================================== --- linux-2.6.orig/Documentation/admin-guide/device-mapper/dm-integrity.rst +++ linux-2.6/Documentation/admin-guide/device-mapper/dm-integrity.rst @@ -177,14 +177,20 @@ bitmap_flush_interval:number The bitmap flush interval in milliseconds. The metadata buffers are synchronized when this interval expires. +allow_discards + Allow block discard requests (a.k.a. TRIM) for the integrity device. + Discards are only allowed to devices using internal hash. + fix_padding Use a smaller padding of the tag area that is more space-efficient. If this option is not present, large padding is used - that is for compatibility with older kernels. -allow_discards - Allow block discard requests (a.k.a. TRIM) for the integrity device. - Discards are only allowed to devices using internal hash. +legacy_recalculate + Allow recalculating of volumes with HMAC keys. This is disabled by + default for security reasons - an attacker could modify the volume, + set recalc_sector to zero, and the kernel would not detect the + modification. The journal mode (D/J), buffer_sectors, journal_watermark, commit_time and allow_discards can be changed when reloading the target (load an inactive integrity-hmac-superblock.patch -- dm-devel mailing list [email protected] https://www.redhat.com/mailman/listinfo/dm-devel
