dm crypt: simplify crypt_ctr

Allocate cipher strings indpendently of struct crypt_config and move
cipher parsing and allocation into a separate function to prepare for
supporting the cryptoapi format e.g. "xts(aes)".

No functional change in this patch.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 104 insertions, 81 deletions

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 139bbe2254c..6401bfa0adf 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -107,11 +107,10 @@ struct crypt_config {
         struct workqueue_struct *io_queue;
         struct workqueue_struct *crypt_queue;
 
-        /*
-         * crypto related data
-         */
+        char *cipher;
+        char *cipher_mode;
+
         struct crypt_iv_operations *iv_gen_ops;
-        char *iv_mode;
         union {
                 struct iv_essiv_private essiv;
                 struct iv_benbi_private benbi;
@@ -135,8 +134,6 @@ struct crypt_config {
         unsigned int dmreq_start;
         struct ablkcipher_request *req;
 
-        char cipher[CRYPTO_MAX_ALG_NAME];
-        char chainmode[CRYPTO_MAX_ALG_NAME];
         struct crypto_ablkcipher *tfm;
         unsigned long flags;
         unsigned int key_size;
@@ -1032,90 +1029,102 @@ static void crypt_dtr(struct dm_target *ti)
         if (cc->dev)
                 dm_put_device(ti, cc->dev);
 
-        kfree(cc->iv_mode);
+        kzfree(cc->cipher);
+        kzfree(cc->cipher_mode);
 
         /* Must zero key material before freeing */
         kzfree(cc);
 }
 
-/*
- * Construct an encryption mapping:
- * <cipher> <key> <iv_offset> <dev_path> <start>
- */
-static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
+static int crypt_ctr_cipher(struct dm_target *ti,
+                            char *cipher_in, char *key)
 {
-        struct crypt_config *cc;
-        char *tmp;
-        char *cipher;
-        char *chainmode;
-        char *ivmode;
-        char *ivopts;
-        unsigned int key_size;
-        unsigned long long tmpll;
+        struct crypt_config *cc = ti->private;
+        char *tmp, *cipher, *chainmode, *ivmode, *ivopts;
+        char *cipher_api = NULL;
         int ret = -EINVAL;
 
-        if (argc != 5) {
-                ti->error = "Not enough arguments";
+        /* Convert to crypto api definition? */
+        if (strchr(cipher_in, '(')) {
+                ti->error = "Bad cipher specification";
                 return -EINVAL;
         }
 
-        tmp = argv[0];
+        /*
+         * Legacy dm-crypt cipher specification
+         * cipher-mode-iv:ivopts
+         */
+        tmp = cipher_in;
         cipher = strsep(&tmp, "-");
+
+        cc->cipher = kstrdup(cipher, GFP_KERNEL);
+        if (!cc->cipher)
+                goto bad_mem;
+
+        if (tmp) {
+                cc->cipher_mode = kstrdup(tmp, GFP_KERNEL);
+                if (!cc->cipher_mode)
+                        goto bad_mem;
+        }
+
         chainmode = strsep(&tmp, "-");
         ivopts = strsep(&tmp, "-");
         ivmode = strsep(&ivopts, ":");
 
         if (tmp)
-                DMWARN("Unexpected additional cipher options");
+                DMWARN("Ignoring unexpected additional cipher options");
 
-        key_size = strlen(argv[1]) >> 1;
-
-        cc = kzalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
-        if (!cc) {
-                ti->error = "Cannot allocate transparent encryption context";
-                return -ENOMEM;
-        }
-
-        ti->private = cc;
-
-        /* Compatibility mode for old dm-crypt cipher strings */
-        if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) {
+        /* Compatibility mode for old dm-crypt mappings */
+        if (!chainmode || (!strcmp(chainmode, "plain") && !ivmode)) {
+                kfree(cc->cipher_mode);
+                cc->cipher_mode = kstrdup("cbc-plain", GFP_KERNEL);
                 chainmode = "cbc";
                 ivmode = "plain";
         }
 
         if (strcmp(chainmode, "ecb") && !ivmode) {
-                ti->error = "This chaining mode requires an IV mechanism";
-                goto bad;
+                ti->error = "IV mechanism required";
+                return -EINVAL;
         }
 
-        ret = -ENOMEM;
-        if (snprintf(cc->cipher, CRYPTO_MAX_ALG_NAME, "%s(%s)",
-                     chainmode, cipher) >= CRYPTO_MAX_ALG_NAME) {
-                ti->error = "Chain mode + cipher name is too long";
-                goto bad;
+        cipher_api = kmalloc(CRYPTO_MAX_ALG_NAME, GFP_KERNEL);
+        if (!cipher_api)
+                goto bad_mem;
+
+        ret = snprintf(cipher_api, CRYPTO_MAX_ALG_NAME,
+                       "%s(%s)", chainmode, cipher);
+        if (ret < 0) {
+                kfree(cipher_api);
+                goto bad_mem;
         }
 
-        cc->tfm = crypto_alloc_ablkcipher(cc->cipher, 0, 0);
+        /* Allocate cipher */
+        cc->tfm = crypto_alloc_ablkcipher(cipher_api, 0, 0);
         if (IS_ERR(cc->tfm)) {
+                ret = PTR_ERR(cc->tfm);
                 ti->error = "Error allocating crypto tfm";
                 goto bad;
         }
 
-        strcpy(cc->cipher, cipher);
-        strcpy(cc->chainmode, chainmode);
-
-        ret = crypt_set_key(cc, argv[1]);
+        /* Initialize and set key */
+        ret = crypt_set_key(cc, key);
         if (ret < 0) {
                 ti->error = "Error decoding and setting key";
                 goto bad;
         }
 
-        /*
-         * Choose ivmode. Valid modes: "plain", "essiv:<esshash>", "benbi".
-         * See comments at iv code
-         */
-        ret = -EINVAL;
+        /* Initialize IV */
+        cc->iv_size = crypto_ablkcipher_ivsize(cc->tfm);
+        if (cc->iv_size)
+                /* at least a 64 bit sector number should fit in our buffer */
+                cc->iv_size = max(cc->iv_size,
+                                  (unsigned int)(sizeof(u64) / sizeof(u8)));
+        else if (ivmode) {
+                DMWARN("Selected cipher does not support IVs");
+                ivmode = NULL;
+        }
+
+        /* Choose ivmode, see comments at iv code. */
         if (ivmode == NULL)
                 cc->iv_gen_ops = NULL;
         else if (strcmp(ivmode, "plain") == 0)
@@ -1129,6 +1138,7 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
         else if (strcmp(ivmode, "null") == 0)
                 cc->iv_gen_ops = &crypt_iv_null_ops;
         else {
+                ret = -EINVAL;
                 ti->error = "Invalid IV mode";
                 goto bad;
         }
@@ -1151,20 +1161,45 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
                 }
         }
 
-        cc->iv_size = crypto_ablkcipher_ivsize(cc->tfm);
-        if (cc->iv_size)
-                /* at least a 64 bit sector number should fit in our buffer */
-                cc->iv_size = max(cc->iv_size,
-                                  (unsigned int)(sizeof(u64) / sizeof(u8)));
-        else {
-                if (cc->iv_gen_ops) {
-                        DMWARN("Selected cipher does not support IVs");
-                        if (cc->iv_gen_ops->dtr)
-                                cc->iv_gen_ops->dtr(cc);
-                        cc->iv_gen_ops = NULL;
-                }
+        ret = 0;
+bad:
+        kfree(cipher_api);
+        return ret;
+
+bad_mem:
+        ti->error = "Cannot allocate cipher strings";
+        return -ENOMEM;
+}
+
+/*
+ * Construct an encryption mapping:
+ * <cipher> <key> <iv_offset> <dev_path> <start>
+ */
+static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
+{
+        struct crypt_config *cc;
+        unsigned int key_size;
+        unsigned long long tmpll;
+        int ret;
+
+        if (argc != 5) {
+                ti->error = "Not enough arguments";
+                return -EINVAL;
         }
 
+        key_size = strlen(argv[1]) >> 1;
+
+        cc = kzalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
+        if (!cc) {
+                ti->error = "Cannot allocate encryption context";
+                return -ENOMEM;
+        }
+
+        ti->private = cc;
+        ret = crypt_ctr_cipher(ti, argv[0], argv[1]);
+        if (ret < 0)
+                goto bad;
+
         ret = -ENOMEM;
         cc->io_pool = mempool_create_slab_pool(MIN_IOS, _crypt_io_pool);
         if (!cc->io_pool) {
@@ -1217,17 +1252,6 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
         cc->start = tmpll;
 
         ret = -ENOMEM;
-        if (ivmode && cc->iv_gen_ops) {
-                if (ivopts)
-                        *(ivopts - 1) = ':';
-                cc->iv_mode = kstrdup(ivmode, GFP_KERNEL);
-                if (!cc->iv_mode) {
-                        ti->error = "Error kmallocing iv_mode string";
-                        goto bad;
-                }
-        } else
-                cc->iv_mode = NULL;
-
         cc->io_queue = create_singlethread_workqueue("kcryptd_io");
         if (!cc->io_queue) {
                 ti->error = "Couldn't create kcryptd io queue";
@@ -1273,7 +1297,7 @@ static int crypt_map(struct dm_target *ti, struct bio *bio,
 static int crypt_status(struct dm_target *ti, status_type_t type,
                         char *result, unsigned int maxlen)
 {
-        struct crypt_config *cc = (struct crypt_config *) ti->private;
+        struct crypt_config *cc = ti->private;
         unsigned int sz = 0;
 
         switch (type) {
@@ -1282,11 +1306,10 @@ static int crypt_status(struct dm_target *ti, status_type_t type,
                 break;
 
         case STATUSTYPE_TABLE:
-                if (cc->iv_mode)
-                        DMEMIT("%s-%s-%s ", cc->cipher, cc->chainmode,
-                               cc->iv_mode);
+                if (cc->cipher_mode)
+                        DMEMIT("%s-%s ", cc->cipher, cc->cipher_mode);
                 else
-                        DMEMIT("%s-%s ", cc->cipher, cc->chainmode);
+                        DMEMIT("%s ", cc->cipher);
 
                 if (cc->key_size > 0) {
                         if ((maxlen - sz) < ((cc->key_size << 1) + 1))