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-rw-r--r--Documentation/device-mapper/dm-crypt.txt21
-rw-r--r--drivers/md/dm-crypt.c49
2 files changed, 65 insertions, 5 deletions
diff --git a/Documentation/device-mapper/dm-crypt.txt b/Documentation/device-mapper/dm-crypt.txt
index 6b5c42dbbe8..2c656ae43ba 100644
--- a/Documentation/device-mapper/dm-crypt.txt
+++ b/Documentation/device-mapper/dm-crypt.txt
@@ -4,7 +4,8 @@ dm-crypt
Device-Mapper's "crypt" target provides transparent encryption of block devices
using the kernel crypto API.
-Parameters: <cipher> <key> <iv_offset> <device path> <offset>
+Parameters: <cipher> <key> <iv_offset> <device path> \
+ <offset> [<#opt_params> <opt_params>]
<cipher>
Encryption cipher and an optional IV generation mode.
@@ -37,6 +38,24 @@ Parameters: <cipher> <key> <iv_offset> <device path> <offset>
<offset>
Starting sector within the device where the encrypted data begins.
+<#opt_params>
+ Number of optional parameters. If there are no optional parameters,
+ the optional paramaters section can be skipped or #opt_params can be zero.
+ Otherwise #opt_params is the number of following arguments.
+
+ Example of optional parameters section:
+ 1 allow_discards
+
+allow_discards
+ Block discard requests (a.k.a. TRIM) are passed through the crypt device.
+ The default is to ignore discard requests.
+
+ WARNING: Assess the specific security risks carefully before enabling this
+ option. For example, allowing discards on encrypted devices may lead to
+ the leak of information about the ciphertext device (filesystem type,
+ used space etc.) if the discarded blocks can be located easily on the
+ device later.
+
Example scripts
===============
LUKS (Linux Unified Key Setup) is now the preferred way to set up disk
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index b79e7472a9b..49da55c1528 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -1574,11 +1574,17 @@ bad_mem:
static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
struct crypt_config *cc;
- unsigned int key_size;
+ unsigned int key_size, opt_params;
unsigned long long tmpll;
int ret;
+ struct dm_arg_set as;
+ const char *opt_string;
+
+ static struct dm_arg _args[] = {
+ {0, 1, "Invalid number of feature args"},
+ };
- if (argc != 5) {
+ if (argc < 5) {
ti->error = "Not enough arguments";
return -EINVAL;
}
@@ -1647,6 +1653,30 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
}
cc->start = tmpll;
+ argv += 5;
+ argc -= 5;
+
+ /* Optional parameters */
+ if (argc) {
+ as.argc = argc;
+ as.argv = argv;
+
+ ret = dm_read_arg_group(_args, &as, &opt_params, &ti->error);
+ if (ret)
+ goto bad;
+
+ opt_string = dm_shift_arg(&as);
+
+ if (opt_params == 1 && opt_string &&
+ !strcasecmp(opt_string, "allow_discards"))
+ ti->num_discard_requests = 1;
+ else if (opt_params) {
+ ret = -EINVAL;
+ ti->error = "Invalid feature arguments";
+ goto bad;
+ }
+ }
+
ret = -ENOMEM;
cc->io_queue = alloc_workqueue("kcryptd_io",
WQ_NON_REENTRANT|
@@ -1681,9 +1711,16 @@ static int crypt_map(struct dm_target *ti, struct bio *bio,
struct dm_crypt_io *io;
struct crypt_config *cc;
- if (bio->bi_rw & REQ_FLUSH) {
+ /*
+ * If bio is REQ_FLUSH or REQ_DISCARD, just bypass crypt queues.
+ * - for REQ_FLUSH device-mapper core ensures that no IO is in-flight
+ * - for REQ_DISCARD caller must use flush if IO ordering matters
+ */
+ if (unlikely(bio->bi_rw & (REQ_FLUSH | REQ_DISCARD))) {
cc = ti->private;
bio->bi_bdev = cc->dev->bdev;
+ if (bio_sectors(bio))
+ bio->bi_sector = cc->start + dm_target_offset(ti, bio->bi_sector);
return DM_MAPIO_REMAPPED;
}
@@ -1726,6 +1763,10 @@ static int crypt_status(struct dm_target *ti, status_type_t type,
DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset,
cc->dev->name, (unsigned long long)cc->start);
+
+ if (ti->num_discard_requests)
+ DMEMIT(" 1 allow_discards");
+
break;
}
return 0;
@@ -1822,7 +1863,7 @@ static int crypt_iterate_devices(struct dm_target *ti,
static struct target_type crypt_target = {
.name = "crypt",
- .version = {1, 10, 0},
+ .version = {1, 11, 0},
.module = THIS_MODULE,
.ctr = crypt_ctr,
.dtr = crypt_dtr,