[dm-devel] [PATCH 2/3] dm crypt: add multi-key capability
Milan Broz
mbroz at redhat.com
Thu Jan 6 20:04:01 UTC 2011
This patch adds generic multikey handling to be used
in following patch for Loop-AES mode compatibility.
This patch extends mapping table to optional keycount and
implements generic multi-key capability.
With more keys defined the <key> string is divided into
several <keycount> sections and these are used for tfms.
The tfm is used according to sector offset
(sector 0->tfm[0], sector 1->tfm[1], sector N->tfm[N modulo keycount])
(only power of two values supported for keycount here).
Because of tfms per-cpu allocation, this mode can be take
a lot of memory on large smp systems.
Signed-off-by: Milan Broz <mbroz at redhat.com>
CC: Max Vozeler <max at hinterhof.net>
---
Documentation/device-mapper/dm-crypt.txt | 7 ++-
drivers/md/dm-crypt.c | 85 +++++++++++++++++++++++-------
2 files changed, 71 insertions(+), 21 deletions(-)
diff --git a/Documentation/device-mapper/dm-crypt.txt b/Documentation/device-mapper/dm-crypt.txt
index 524de92..6ed2312 100644
--- a/Documentation/device-mapper/dm-crypt.txt
+++ b/Documentation/device-mapper/dm-crypt.txt
@@ -8,7 +8,7 @@ Parameters: <cipher> <key> <iv_offset> <device path> <offset>
<cipher>
Encryption cipher and an optional IV generation mode.
- (In format cipher-chainmode-ivopts:ivmode).
+ (In format cipher[:keycount]-chainmode-ivopts:ivmode).
Examples:
des
aes-cbc-essiv:sha256
@@ -20,6 +20,11 @@ Parameters: <cipher> <key> <iv_offset> <device path> <offset>
Key used for encryption. It is encoded as a hexadecimal number.
You can only use key sizes that are valid for the selected cipher.
+<keycount>
+ Multi-key compatibility mode - you can define different keys and
+ the sectors are according its offset (sector 0 -> key0, 1 -> key1 etc).
+ Keycount value must be power of two.
+
<iv_offset>
The IV offset is a sector count that is added to the sector number
before creating the IV.
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 9678701..eba9b43 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -101,10 +101,9 @@ enum flags { DM_CRYPT_SUSPENDED, DM_CRYPT_KEY_VALID };
*/
struct crypt_cpu {
struct ablkcipher_request *req;
- struct crypto_ablkcipher *tfm;
-
/* ESSIV: struct crypto_cipher *essiv_tfm */
void *iv_private;
+ struct crypto_ablkcipher *tfms[0];
};
/*
@@ -143,6 +142,7 @@ struct crypt_config {
* per_cpu_ptr() only.
*/
struct crypt_cpu __percpu *cpu;
+ unsigned int tfms_count;
/*
* Layout of each crypto request:
@@ -161,6 +161,7 @@ struct crypt_config {
unsigned long flags;
unsigned int key_size;
+ unsigned int key_parts;
u8 key[0];
};
@@ -184,7 +185,7 @@ static struct crypt_cpu *this_crypt_config(struct crypt_config *cc)
*/
static struct crypto_ablkcipher *this_tfm(struct crypt_config *cc)
{
- return __this_cpu_ptr(cc->cpu)->tfm;
+ return __this_cpu_ptr(cc->cpu)->tfms[0];
}
/*
@@ -567,11 +568,12 @@ static void crypt_alloc_req(struct crypt_config *cc,
struct convert_context *ctx)
{
struct crypt_cpu *this_cc = this_crypt_config(cc);
+ unsigned key_index = ctx->sector & (cc->tfms_count - 1);
if (!this_cc->req)
this_cc->req = mempool_alloc(cc->req_pool, GFP_NOIO);
- ablkcipher_request_set_tfm(this_cc->req, this_cc->tfm);
+ ablkcipher_request_set_tfm(this_cc->req, this_cc->tfms[key_index]);
ablkcipher_request_set_callback(this_cc->req,
CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
kcryptd_async_done, dmreq_of_req(cc, this_cc->req));
@@ -1097,15 +1099,48 @@ static void crypt_encode_key(char *hex, u8 *key, unsigned int size)
}
}
+static void crypt_free_tfms(struct crypt_config *cc, int cpu)
+{
+ struct crypt_cpu *cpu_cc = per_cpu_ptr(cc->cpu, cpu);
+ int i;
+
+ for (i = 0; i < cc->tfms_count; i++)
+ if (cpu_cc->tfms[i] && !IS_ERR(cpu_cc->tfms[i])) {
+ crypto_free_ablkcipher(cpu_cc->tfms[i]);
+ cpu_cc->tfms[i] = NULL;
+ }
+}
+
+static int crypt_alloc_tfms(struct crypt_config *cc, int cpu, char *ciphermode)
+{
+ struct crypt_cpu *cpu_cc = per_cpu_ptr(cc->cpu, cpu);
+ int i, err;
+
+ for (i = 0; i < cc->tfms_count; i++) {
+ cpu_cc->tfms[i] = crypto_alloc_ablkcipher(ciphermode, 0, 0);
+ if (IS_ERR(cpu_cc->tfms[i])) {
+ err = PTR_ERR(cpu_cc->tfms[i]);
+ crypt_free_tfms(cc, cpu);
+ return err;
+ }
+ }
+
+ return 0;
+}
+
static int crypt_setkey_allcpus(struct crypt_config *cc)
{
- int cpu, err = 0, r;
+ unsigned subkey_size = cc->key_size >> ilog2(cc->tfms_count);
+ int cpu, err = 0, i, r;
for_each_possible_cpu(cpu) {
- r = crypto_ablkcipher_setkey(per_cpu_ptr(cc->cpu, cpu)->tfm,
- cc->key, cc->key_size);
- if (r)
- err = r;
+ for (i = 0; i < cc->tfms_count; i++) {
+ r = crypto_ablkcipher_setkey(
+ per_cpu_ptr(cc->cpu, cpu)->tfms[i],
+ cc->key + (i * subkey_size), subkey_size);
+ if (r)
+ err = r;
+ }
}
return err;
@@ -1158,8 +1193,7 @@ static void crypt_dtr(struct dm_target *ti)
cpu_cc = per_cpu_ptr(cc->cpu, cpu);
if (cpu_cc->req)
mempool_free(cpu_cc->req, cc->req_pool);
- if (cpu_cc->tfm)
- crypto_free_ablkcipher(cpu_cc->tfm);
+ crypt_free_tfms(cc, cpu);
}
if (cc->bs)
@@ -1192,8 +1226,7 @@ static int crypt_ctr_cipher(struct dm_target *ti,
char *cipher_in, char *key)
{
struct crypt_config *cc = ti->private;
- struct crypto_ablkcipher *tfm;
- char *tmp, *cipher, *chainmode, *ivmode, *ivopts;
+ char *tmp, *cipher, *chainmode, *ivmode, *ivopts, *keycount;
char *cipher_api = NULL;
int cpu, ret = -EINVAL;
@@ -1209,11 +1242,23 @@ static int crypt_ctr_cipher(struct dm_target *ti,
/*
* Legacy dm-crypt cipher specification
- * cipher-mode-iv:ivopts
+ * cipher[:keycount]-mode-iv:ivopts
*/
tmp = cipher_in;
cipher = strsep(&tmp, "-");
+ keycount = cipher;
+ cipher = strsep(&keycount, ":");
+
+ if (!keycount)
+ cc->tfms_count = 1;
+ else if (sscanf(keycount, "%u", &cc->tfms_count) != 1 ||
+ !is_power_of_2(cc->tfms_count)) {
+ ti->error = "Bad cipher key count specification";
+ return -EINVAL;
+ }
+ cc->key_parts = cc->tfms_count;
+
cc->cipher = kstrdup(cipher, GFP_KERNEL);
if (!cc->cipher)
goto bad_mem;
@@ -1225,7 +1270,9 @@ static int crypt_ctr_cipher(struct dm_target *ti,
if (tmp)
DMWARN("Ignoring unexpected additional cipher options");
- cc->cpu = alloc_percpu(struct crypt_cpu);
+ cc->cpu = __alloc_percpu(sizeof(*(cc->cpu)) +
+ cc->tfms_count * sizeof(*(cc->cpu->tfms)),
+ __alignof__(struct crypt_cpu));
if (!cc->cpu) {
ti->error = "Cannot allocate per cpu state";
goto bad_mem;
@@ -1258,13 +1305,11 @@ static int crypt_ctr_cipher(struct dm_target *ti,
/* Allocate cipher */
for_each_possible_cpu(cpu) {
- tfm = crypto_alloc_ablkcipher(cipher_api, 0, 0);
- if (IS_ERR(tfm)) {
- ret = PTR_ERR(tfm);
+ ret = crypt_alloc_tfms(cc, cpu, cipher_api);
+ if (ret < 0) {
ti->error = "Error allocating crypto tfm";
goto bad;
}
- per_cpu_ptr(cc->cpu, cpu)->tfm = tfm;
}
/* Initialize and set key */
@@ -1587,7 +1632,7 @@ static int crypt_iterate_devices(struct dm_target *ti,
static struct target_type crypt_target = {
.name = "crypt",
- .version = {1, 7, 0},
+ .version = {1, 8, 0},
.module = THIS_MODULE,
.ctr = crypt_ctr,
.dtr = crypt_dtr,
--
1.7.2.3
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