dm crypt: add multi key capability

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@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Cc: Max Vozeler <max@hinterhof.net>

diff --git a/Documentation/device-mapper/dm-crypt.txt b/Documentation/device-mapper/dm-crypt.txt
index 524de926290d96393d17ccb4d0e004a1bdfb509a..59293ac4a5d0382abf0cd9c3afb0fef718cccf73 100644 (file)
--- 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 <keycount> keys and
+    then sectors are encrypted according to their offsets (sector 0 uses key0;
+    sector 1 uses key1 etc.).  <keycount> must be a 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 e0ebe685be6a6e3266faf688757dfdaad7abeb30..b8b9267c4dbbeace93c5d5af442c0fd9016f551e 100644 (file)
--- 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 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 *any_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);
+       unsigned 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);
+       unsigned i;
+       int 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;
 
@@ -1209,10 +1242,20 @@ 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 = strsep(&tmp, "-");
+       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)
@@ -1225,7 +1268,9 @@ 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 +1303,11 @@ 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 +1630,7 @@ static int crypt_iterate_devices(struct dm_target *ti,
 
 static struct target_type crypt_target = {
        .name   = "crypt",
-       .version = {1, 9, 0},
+       .version = {1, 10, 0},
        .module = THIS_MODULE,
        .ctr    = crypt_ctr,
        .dtr    = crypt_dtr,