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dm integrity: log audit events for dm-integrity target

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dm-integrity signals integrity violations by returning I/O errors
to user space. To identify integrity violations by a controlling
instance, the kernel audit subsystem can be used to emit audit
events to user space. We use the new dm-audit submodule allowing
to emit audit events on relevant I/O errors.

The construction and destruction of integrity device mappings are
also relevant for auditing a system. Thus, those events are also
logged as audit events.

Signed-off-by: Michael Weiß <michael.weiss@aisec.fraunhofer.de>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Michael Weiß 2021-09-04 11:59:29 +02:00 committed by Mike Snitzer
parent 2cc1ae4878
commit 82bb85998c
2 changed files with 22 additions and 4 deletions
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1
drivers/md/Kconfig
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@ -610,6 +610,7 @@ config DM_INTEGRITY
select CRYPTO
select CRYPTO_SKCIPHER
select ASYNC_XOR
select DM_AUDIT if AUDIT
help
This device-mapper target emulates a block device that has
additional per-sector tags that can be used for storing

25
drivers/md/dm-integrity.c
View File

@ -23,6 +23,8 @@
#include <linux/async_tx.h>
#include <linux/dm-bufio.h>
#include "dm-audit.h"
#define DM_MSG_PREFIX "integrity"
#define DEFAULT_INTERLEAVE_SECTORS 32768
@ -539,6 +541,7 @@ static int sb_mac(struct dm_integrity_c *ic, bool wr)
}
if (memcmp((__u8 *)ic->sb + (1 << SECTOR_SHIFT) - size, result, size)) {
dm_integrity_io_error(ic, "superblock mac", -EILSEQ);
dm_audit_log_target(DM_MSG_PREFIX, "mac-superblock", ic->ti, 0);
return -EILSEQ;
}
}
@ -876,8 +879,10 @@ static void rw_section_mac(struct dm_integrity_c *ic, unsigned section, bool wr)
if (likely(wr))
memcpy(&js->mac, result + (j * JOURNAL_MAC_PER_SECTOR), JOURNAL_MAC_PER_SECTOR);
else {
if (memcmp(&js->mac, result + (j * JOURNAL_MAC_PER_SECTOR), JOURNAL_MAC_PER_SECTOR))
if (memcmp(&js->mac, result + (j * JOURNAL_MAC_PER_SECTOR), JOURNAL_MAC_PER_SECTOR)) {
dm_integrity_io_error(ic, "journal mac", -EILSEQ);
dm_audit_log_target(DM_MSG_PREFIX, "mac-journal", ic->ti, 0);
}
}
}
}
@ -1782,10 +1787,15 @@ again:
if (unlikely(r)) {
if (r > 0) {
char b[BDEVNAME_SIZE];
DMERR_LIMIT("%s: Checksum failed at sector 0x%llx", bio_devname(bio, b),
(sector - ((r + ic->tag_size - 1) / ic->tag_size)));
sector_t s;
s = sector - ((r + ic->tag_size - 1) / ic->tag_size);
DMERR_LIMIT("%s: Checksum failed at sector 0x%llx",
bio_devname(bio, b), s);
r = -EILSEQ;
atomic64_inc(&ic->number_of_mismatches);
dm_audit_log_bio(DM_MSG_PREFIX, "integrity-checksum",
bio, s, 0);
}
if (likely(checksums != checksums_onstack))
kfree(checksums);
@ -1991,6 +2001,8 @@ retry_kmap:
if (unlikely(memcmp(checksums_onstack, journal_entry_tag(ic, je), ic->tag_size))) {
DMERR_LIMIT("Checksum failed when reading from journal, at sector 0x%llx",
logical_sector);
dm_audit_log_bio(DM_MSG_PREFIX, "journal-checksum",
bio, logical_sector, 0);
}
}
#endif
@ -2534,8 +2546,10 @@ static void do_journal_write(struct dm_integrity_c *ic, unsigned write_start,
integrity_sector_checksum(ic, sec + ((l - j) << ic->sb->log2_sectors_per_block),
(char *)access_journal_data(ic, i, l), test_tag);
if (unlikely(memcmp(test_tag, journal_entry_tag(ic, je2), ic->tag_size)))
if (unlikely(memcmp(test_tag, journal_entry_tag(ic, je2), ic->tag_size))) {
dm_integrity_io_error(ic, "tag mismatch when replaying journal", -EILSEQ);
dm_audit_log_target(DM_MSG_PREFIX, "integrity-replay-journal", ic->ti, 0);
}
}
journal_entry_set_unused(je2);
@ -4514,9 +4528,11 @@ try_smaller_buffer:
if (ic->discard)
ti->num_discard_bios = 1;
dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1);
return 0;
bad:
dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0);
dm_integrity_dtr(ti);
return r;
}
@ -4590,6 +4606,7 @@ static void dm_integrity_dtr(struct dm_target *ti)
free_alg(&ic->journal_mac_alg);
kfree(ic);
dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1);
}
static struct target_type integrity_target = {