diff options
| -rw-r--r-- | drivers/md/Kconfig | 20 | ||||
| -rw-r--r-- | drivers/md/dm-verity-target.c | 8 |
2 files changed, 28 insertions, 0 deletions
diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig index 5649d1ab0083..95de7ee56dfc 100644 --- a/drivers/md/Kconfig +++ b/drivers/md/Kconfig @@ -545,4 +545,24 @@ config DM_ANDROID_VERITY of the metadata contents are verified against the key included in the system keyring. Upon success, the underlying verity target is setup. + +config DM_ANDROID_VERITY_AT_MOST_ONCE_DEFAULT_ENABLED + bool "Verity will validate blocks at most once" + depends on DM_VERITY + ---help--- + Default enables at_most_once option for dm-verity + + Verify data blocks only the first time they are read from the + data device, rather than every time. This reduces the overhead + of dm-verity so that it can be used on systems that are memory + and/or CPU constrained. However, it provides a reduced level + of security because only offline tampering of the data device's + content will be detected, not online tampering. + + Hash blocks are still verified each time they are read from the + hash device, since verification of hash blocks is less performance + critical than data blocks, and a hash block will not be verified + any more after all the data blocks it covers have been verified anyway. + + If unsure, say N. endif # MD diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c index ceff074b3b74..d2e3abc182b3 100644 --- a/drivers/md/dm-verity-target.c +++ b/drivers/md/dm-verity-target.c @@ -1053,6 +1053,14 @@ int verity_ctr(struct dm_target *ti, unsigned argc, char **argv) goto bad; } +#ifdef CONFIG_DM_ANDROID_VERITY_AT_MOST_ONCE_DEFAULT_ENABLED + if (!v->validated_blocks) { + r = verity_alloc_most_once(v); + if (r) + goto bad; + } +#endif + v->hash_per_block_bits = __fls((1 << v->hash_dev_block_bits) / v->digest_size); |