[PATCH 3/3] dm crypt: log aead integrity violations to audit subsystem

From: Michael Weiß
Date: Thu Aug 12 2021 - 10:58:37 EST


Since dm-crypt target can be stacked on dm-integrity targets to
provide authenticated encryption, integrity violations are recognized
here during aead computation. We use the dm-audit submodule to
signal those events to user space, too.

The construction and destruction of crypt device mappings are also
logged as audit events.

Signed-off-by: Michael Weiß <michael.weiss@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/dm-crypt.c | 23 +++++++++++++++++++----
1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 50f4cbd600d5..343aef4dcf5e 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -41,6 +41,8 @@

#include <linux/device-mapper.h>

+#include "dm-audit.h"
+
#define DM_MSG_PREFIX "crypt"

/*
@@ -1122,6 +1124,7 @@ static bool crypt_integrity_hmac(struct crypt_config *cc)
return crypt_integrity_aead(cc) && cc->key_mac_size;
}

+
/* Get sg containing data */
static struct scatterlist *crypt_get_sg_data(struct crypt_config *cc,
struct scatterlist *sg)
@@ -1362,8 +1365,12 @@ static int crypt_convert_block_aead(struct crypt_config *cc,

if (r == -EBADMSG) {
char b[BDEVNAME_SIZE];
- DMERR_LIMIT("%s: INTEGRITY AEAD ERROR, sector %llu", bio_devname(ctx->bio_in, b),
- (unsigned long long)le64_to_cpu(*sector));
+ sector_t s = le64_to_cpu(*sector);
+
+ DMERR_LIMIT("%s: INTEGRITY AEAD ERROR, sector %llu",
+ bio_devname(ctx->bio_in, b), s);
+ dm_audit_log_bio(DM_MSG_PREFIX, "integrity-aead",
+ ctx->bio_in, s, 0);
}

if (!r && cc->iv_gen_ops && cc->iv_gen_ops->post)
@@ -2173,8 +2180,12 @@ static void kcryptd_async_done(struct crypto_async_request *async_req,

if (error == -EBADMSG) {
char b[BDEVNAME_SIZE];
- DMERR_LIMIT("%s: INTEGRITY AEAD ERROR, sector %llu", bio_devname(ctx->bio_in, b),
- (unsigned long long)le64_to_cpu(*org_sector_of_dmreq(cc, dmreq)));
+ sector_t s = le64_to_cpu(*org_sector_of_dmreq(cc, dmreq));
+
+ DMERR_LIMIT("%s: INTEGRITY AEAD ERROR, sector %llu",
+ bio_devname(ctx->bio_in, b), s);
+ dm_audit_log_bio(DM_MSG_PREFIX, "integrity-aead",
+ ctx->bio_in, s, 0);
io->error = BLK_STS_PROTECTION;
} else if (error < 0)
io->error = BLK_STS_IOERR;
@@ -2729,6 +2740,8 @@ static void crypt_dtr(struct dm_target *ti)
dm_crypt_clients_n--;
crypt_calculate_pages_per_client();
spin_unlock(&dm_crypt_clients_lock);
+
+ dm_audit_log_target(DM_MSG_PREFIX, "dtr", ti, 1);
}

static int crypt_ctr_ivmode(struct dm_target *ti, const char *ivmode)
@@ -3357,9 +3370,11 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
ti->num_flush_bios = 1;
ti->limit_swap_bios = true;

+ dm_audit_log_target(DM_MSG_PREFIX, "ctr", ti, 1);
return 0;

bad:
+ dm_audit_log_target(DM_MSG_PREFIX, "ctr", ti, 0);
crypt_dtr(ti);
return ret;
}
--
2.20.1