git: 90ffac35b778 - stable/13 - eli: Zero pad bytes that arise when certain auth algorithms are used

[Mark Johnston]

The branch stable/13 has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=90ffac35b778564d1b4cb8ec7d2ff92ccc8e56dd

commit 90ffac35b778564d1b4cb8ec7d2ff92ccc8e56dd
Author:     Mark Johnston <markj at FreeBSD.org>
AuthorDate: 2021-07-15 16:23:04 +0000
Commit:     Mark Johnston <markj at FreeBSD.org>
CommitDate: 2021-07-29 12:12:22 +0000

    eli: Zero pad bytes that arise when certain auth algorithms are used
    
    When authentication is configured, GELI ensures that the amount of data
    per sector is a multiple of 16 bytes.  This is done in
    eli_metadata_softc().  When the digest size is not a multiple of 16
    bytes, this leaves some extra pad bytes at the end of every sector, and
    they were not being zeroed before being written to disk.  In particular,
    this happens with the HMAC/SHA1, HMAC/RIPEMD160 and HMAC/SHA384 data
    authentication algorithms.
    
    This change ensures that they are zeroed before being written to disk.
    
    Reported by:    KMSAN
    Reviewed by:    delphij, asomers
    Sponsored by:   The FreeBSD Foundation
    
    (cherry picked from commit 0fcafe8516d170852aa73f029a6a28bed1e29292)
---
 sys/geom/eli/g_eli_integrity.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/sys/geom/eli/g_eli_integrity.c b/sys/geom/eli/g_eli_integrity.c
index 4cf982e3ddfa..d9ac0a2a3d72 100644
--- a/sys/geom/eli/g_eli_integrity.c
+++ b/sys/geom/eli/g_eli_integrity.c
@@ -510,6 +510,17 @@ g_eli_auth_run(struct g_eli_worker *wr, struct bio *bp)
 			if (bp->bio_cmd == BIO_WRITE)
 				memset(data + sc->sc_alen + data_secsize, 0,
 				    encr_secsize - sc->sc_alen - data_secsize);
+		} else if (data_secsize + sc->sc_alen != encr_secsize) {
+			/*
+			 * If the HMAC size is not a multiple of 128 bits, the
+			 * per-sector data size is rounded down to ensure that
+			 * encryption can be performed without requiring any
+			 * padding.  In this case, each sector contains unused
+			 * bytes.
+			 */
+			if (bp->bio_cmd == BIO_WRITE)
+				memset(data + sc->sc_alen + data_secsize, 0,
+				    encr_secsize - sc->sc_alen - data_secsize);
 		}
 
 		if (bp->bio_cmd == BIO_WRITE) {