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>
This commit is contained in:
Milan Broz
Alasdair G Kergon
parent
2dc5327d3a
commit
d1f9642381
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@ -8,7 +8,7 @@ Parameters: <cipher> <key> <iv_offset> <device path> <offset>
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<cipher>
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Encryption cipher and an optional IV generation mode.
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(In format cipher-chainmode-ivopts:ivmode).
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(In format cipher[:keycount]-chainmode-ivopts:ivmode).
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Examples:
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des
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aes-cbc-essiv:sha256
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@ -20,6 +20,11 @@ Parameters: <cipher> <key> <iv_offset> <device path> <offset>
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Key used for encryption. It is encoded as a hexadecimal number.
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You can only use key sizes that are valid for the selected cipher.
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<keycount>
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Multi-key compatibility mode. You can define <keycount> keys and
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then sectors are encrypted according to their offsets (sector 0 uses key0;
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sector 1 uses key1 etc.). <keycount> must be a power of two.
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<iv_offset>
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The IV offset is a sector count that is added to the sector number
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before creating the IV.
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@ -101,10 +101,9 @@ enum flags { DM_CRYPT_SUSPENDED, DM_CRYPT_KEY_VALID };
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*/
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struct crypt_cpu {
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struct ablkcipher_request *req;
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struct crypto_ablkcipher *tfm;
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/* ESSIV: struct crypto_cipher *essiv_tfm */
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void *iv_private;
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struct crypto_ablkcipher *tfms[0];
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};
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/*
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@ -143,6 +142,7 @@ struct crypt_config {
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* per_cpu_ptr() only.
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*/
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struct crypt_cpu __percpu *cpu;
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unsigned tfms_count;
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/*
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* Layout of each crypto request:
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@ -161,6 +161,7 @@ struct crypt_config {
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unsigned long flags;
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unsigned int key_size;
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unsigned int key_parts;
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u8 key[0];
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};
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@ -184,7 +185,7 @@ static struct crypt_cpu *this_crypt_config(struct crypt_config *cc)
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*/
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static struct crypto_ablkcipher *any_tfm(struct crypt_config *cc)
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{
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return __this_cpu_ptr(cc->cpu)->tfm;
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return __this_cpu_ptr(cc->cpu)->tfms[0];
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}
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/*
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@ -567,11 +568,12 @@ static void crypt_alloc_req(struct crypt_config *cc,
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struct convert_context *ctx)
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{
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struct crypt_cpu *this_cc = this_crypt_config(cc);
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unsigned key_index = ctx->sector & (cc->tfms_count - 1);
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if (!this_cc->req)
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this_cc->req = mempool_alloc(cc->req_pool, GFP_NOIO);
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ablkcipher_request_set_tfm(this_cc->req, this_cc->tfm);
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ablkcipher_request_set_tfm(this_cc->req, this_cc->tfms[key_index]);
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ablkcipher_request_set_callback(this_cc->req,
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CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
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kcryptd_async_done, dmreq_of_req(cc, this_cc->req));
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@ -1097,15 +1099,48 @@ static void crypt_encode_key(char *hex, u8 *key, unsigned int size)
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}
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}
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static void crypt_free_tfms(struct crypt_config *cc, int cpu)
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{
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struct crypt_cpu *cpu_cc = per_cpu_ptr(cc->cpu, cpu);
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unsigned i;
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for (i = 0; i < cc->tfms_count; i++)
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if (cpu_cc->tfms[i] && !IS_ERR(cpu_cc->tfms[i])) {
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crypto_free_ablkcipher(cpu_cc->tfms[i]);
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cpu_cc->tfms[i] = NULL;
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}
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}
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static int crypt_alloc_tfms(struct crypt_config *cc, int cpu, char *ciphermode)
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{
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struct crypt_cpu *cpu_cc = per_cpu_ptr(cc->cpu, cpu);
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unsigned i;
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int err;
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for (i = 0; i < cc->tfms_count; i++) {
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cpu_cc->tfms[i] = crypto_alloc_ablkcipher(ciphermode, 0, 0);
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if (IS_ERR(cpu_cc->tfms[i])) {
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err = PTR_ERR(cpu_cc->tfms[i]);
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crypt_free_tfms(cc, cpu);
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return err;
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}
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}
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return 0;
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}
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static int crypt_setkey_allcpus(struct crypt_config *cc)
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{
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int cpu, err = 0, r;
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unsigned subkey_size = cc->key_size >> ilog2(cc->tfms_count);
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int cpu, err = 0, i, r;
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for_each_possible_cpu(cpu) {
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r = crypto_ablkcipher_setkey(per_cpu_ptr(cc->cpu, cpu)->tfm,
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cc->key, cc->key_size);
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if (r)
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err = r;
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for (i = 0; i < cc->tfms_count; i++) {
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r = crypto_ablkcipher_setkey(per_cpu_ptr(cc->cpu, cpu)->tfms[i],
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cc->key + (i * subkey_size), subkey_size);
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if (r)
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err = r;
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}
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}
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return err;
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@ -1158,8 +1193,7 @@ static void crypt_dtr(struct dm_target *ti)
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cpu_cc = per_cpu_ptr(cc->cpu, cpu);
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if (cpu_cc->req)
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mempool_free(cpu_cc->req, cc->req_pool);
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if (cpu_cc->tfm)
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crypto_free_ablkcipher(cpu_cc->tfm);
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crypt_free_tfms(cc, cpu);
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}
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if (cc->bs)
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@ -1192,8 +1226,7 @@ static int crypt_ctr_cipher(struct dm_target *ti,
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char *cipher_in, char *key)
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{
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struct crypt_config *cc = ti->private;
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struct crypto_ablkcipher *tfm;
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char *tmp, *cipher, *chainmode, *ivmode, *ivopts;
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char *tmp, *cipher, *chainmode, *ivmode, *ivopts, *keycount;
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char *cipher_api = NULL;
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int cpu, ret = -EINVAL;
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@ -1209,10 +1242,20 @@ static int crypt_ctr_cipher(struct dm_target *ti,
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/*
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* Legacy dm-crypt cipher specification
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* cipher-mode-iv:ivopts
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* cipher[:keycount]-mode-iv:ivopts
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*/
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tmp = cipher_in;
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cipher = strsep(&tmp, "-");
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keycount = strsep(&tmp, "-");
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cipher = strsep(&keycount, ":");
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if (!keycount)
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cc->tfms_count = 1;
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else if (sscanf(keycount, "%u", &cc->tfms_count) != 1 ||
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!is_power_of_2(cc->tfms_count)) {
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ti->error = "Bad cipher key count specification";
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return -EINVAL;
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}
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cc->key_parts = cc->tfms_count;
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cc->cipher = kstrdup(cipher, GFP_KERNEL);
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if (!cc->cipher)
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@ -1225,7 +1268,9 @@ static int crypt_ctr_cipher(struct dm_target *ti,
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if (tmp)
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DMWARN("Ignoring unexpected additional cipher options");
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cc->cpu = alloc_percpu(struct crypt_cpu);
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cc->cpu = __alloc_percpu(sizeof(*(cc->cpu)) +
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cc->tfms_count * sizeof(*(cc->cpu->tfms)),
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__alignof__(struct crypt_cpu));
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if (!cc->cpu) {
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ti->error = "Cannot allocate per cpu state";
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goto bad_mem;
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@ -1258,13 +1303,11 @@ static int crypt_ctr_cipher(struct dm_target *ti,
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/* Allocate cipher */
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for_each_possible_cpu(cpu) {
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tfm = crypto_alloc_ablkcipher(cipher_api, 0, 0);
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if (IS_ERR(tfm)) {
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ret = PTR_ERR(tfm);
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ret = crypt_alloc_tfms(cc, cpu, cipher_api);
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if (ret < 0) {
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ti->error = "Error allocating crypto tfm";
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goto bad;
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}
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per_cpu_ptr(cc->cpu, cpu)->tfm = tfm;
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}
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/* Initialize and set key */
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@ -1587,7 +1630,7 @@ static int crypt_iterate_devices(struct dm_target *ti,
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static struct target_type crypt_target = {
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.name = "crypt",
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.version = {1, 9, 0},
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.version = {1, 10, 0},
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.module = THIS_MODULE,
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.ctr = crypt_ctr,
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.dtr = crypt_dtr,
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