dm crypt: restructure essiv error path

Use kzfree for salt deallocation because it is derived from the volume key. Use a common error path in ESSIV constructor. Required by a later patch which fixes the way key material is wiped from memory. Cc: stable@kernel.org Signed-off-by: Milan Broz <mbroz@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>

dm crypt: restructure essiv error path
Use kzfree for salt deallocation because it is derived from the volume key. Use a common error path in ESSIV constructor. Required by a later patch which fixes the way key material is wiped from memory. Cc: stable@kernel.org Signed-off-by: Milan Broz <mbroz@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Milan Broz · Alasdair G Kergon
1 parent 6047359277
Showing 1 changed file with 26 additions and 20 deletions Side-by-side Diff
drivers/md/dm-crypt.c
@@ -187,15 +187,15 @@
 static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
 			      const char *opts)
 {
-	struct crypto_cipher *essiv_tfm;
-	struct crypto_hash *hash_tfm;
+	struct crypto_cipher *essiv_tfm = NULL;
+	struct crypto_hash *hash_tfm = NULL;
 	struct hash_desc desc;
 	struct scatterlist sg;
 	unsigned int saltsize;
-	u8 *salt;
+	u8 *salt = NULL;
 	int err;
  
-	if (opts == NULL) {
+	if (!opts) {
 		ti->error = "Digest algorithm missing for ESSIV mode";
 		return -EINVAL;
 	}
  
  
@@ -204,15 +204,16 @@
 	hash_tfm = crypto_alloc_hash(opts, 0, CRYPTO_ALG_ASYNC);
 	if (IS_ERR(hash_tfm)) {
 		ti->error = "Error initializing ESSIV hash";
-		return PTR_ERR(hash_tfm);
+		err = PTR_ERR(hash_tfm);
+		goto bad;
 	}
  
 	saltsize = crypto_hash_digestsize(hash_tfm);
-	salt = kmalloc(saltsize, GFP_KERNEL);
-	if (salt == NULL) {
+	salt = kzalloc(saltsize, GFP_KERNEL);
+	if (!salt) {
 		ti->error = "Error kmallocing salt storage in ESSIV";
-		crypto_free_hash(hash_tfm);
-		return -ENOMEM;
+		err = -ENOMEM;
+		goto bad;
 	}
  
 	sg_init_one(&sg, cc->key, cc->key_size);
  
  
  
  
  
  
@@ -220,39 +221,44 @@
 	desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 	err = crypto_hash_digest(&desc, &sg, cc->key_size, salt);
 	crypto_free_hash(hash_tfm);
+	hash_tfm = NULL;
  
 	if (err) {
 		ti->error = "Error calculating hash in ESSIV";
-		kfree(salt);
-		return err;
+		goto bad;
 	}
  
 	/* Setup the essiv_tfm with the given salt */
 	essiv_tfm = crypto_alloc_cipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
 	if (IS_ERR(essiv_tfm)) {
 		ti->error = "Error allocating crypto tfm for ESSIV";
-		kfree(salt);
-		return PTR_ERR(essiv_tfm);
+		err = PTR_ERR(essiv_tfm);
+		goto bad;
 	}
 	if (crypto_cipher_blocksize(essiv_tfm) !=
 	    crypto_ablkcipher_ivsize(cc->tfm)) {
 		ti->error = "Block size of ESSIV cipher does "
 			    "not match IV size of block cipher";
-		crypto_free_cipher(essiv_tfm);
-		kfree(salt);
-		return -EINVAL;
+		err = -EINVAL;
+		goto bad;
 	}
 	err = crypto_cipher_setkey(essiv_tfm, salt, saltsize);
 	if (err) {
 		ti->error = "Failed to set key for ESSIV cipher";
-		crypto_free_cipher(essiv_tfm);
-		kfree(salt);
-		return err;
+		goto bad;
 	}
-	kfree(salt);
+	kzfree(salt);
  
 	cc->iv_gen_private.essiv.tfm = essiv_tfm;
 	return 0;
+
+bad:
+	if (essiv_tfm && !IS_ERR(essiv_tfm))
+		crypto_free_cipher(essiv_tfm);
+	if (hash_tfm && !IS_ERR(hash_tfm))
+		crypto_free_hash(hash_tfm);
+	kzfree(salt);
+	return err;
 }
  
 static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
...	...	@@ -187,15 +187,15 @@
187	187	static int crypt_iv_essiv_ctr(struct crypt_config cc, struct dm_target ti,
188	188	const char *opts)
189	189	{
190		- struct crypto_cipher *essiv_tfm;
191		- struct crypto_hash *hash_tfm;
	190	+ struct crypto_cipher *essiv_tfm = NULL;
	191	+ struct crypto_hash *hash_tfm = NULL;
192	192	struct hash_desc desc;
193	193	struct scatterlist sg;
194	194	unsigned int saltsize;
195		- u8 *salt;
	195	+ u8 *salt = NULL;
196	196	int err;
197	197
198		- if (opts == NULL) {
	198	+ if (!opts) {
199	199	ti->error = "Digest algorithm missing for ESSIV mode";
200	200	return -EINVAL;
201	201	}
202	202
203	203
...	...	@@ -204,15 +204,16 @@
204	204	hash_tfm = crypto_alloc_hash(opts, 0, CRYPTO_ALG_ASYNC);
205	205	if (IS_ERR(hash_tfm)) {
206	206	ti->error = "Error initializing ESSIV hash";
207		- return PTR_ERR(hash_tfm);
	207	+ err = PTR_ERR(hash_tfm);
	208	+ goto bad;
208	209	}
209	210
210	211	saltsize = crypto_hash_digestsize(hash_tfm);
211		- salt = kmalloc(saltsize, GFP_KERNEL);
212		- if (salt == NULL) {
	212	+ salt = kzalloc(saltsize, GFP_KERNEL);
	213	+ if (!salt) {
213	214	ti->error = "Error kmallocing salt storage in ESSIV";
214		- crypto_free_hash(hash_tfm);
215		- return -ENOMEM;
	215	+ err = -ENOMEM;
	216	+ goto bad;
216	217	}
217	218
218	219	sg_init_one(&sg, cc->key, cc->key_size);
219	220
220	221
221	222
222	223
223	224
224	225
...	...	@@ -220,39 +221,44 @@
220	221	desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
221	222	err = crypto_hash_digest(&desc, &sg, cc->key_size, salt);
222	223	crypto_free_hash(hash_tfm);
	224	+ hash_tfm = NULL;
223	225
224	226	if (err) {
225	227	ti->error = "Error calculating hash in ESSIV";
226		- kfree(salt);
227		- return err;
	228	+ goto bad;
228	229	}
229	230
230	231	/* Setup the essiv_tfm with the given salt */
231	232	essiv_tfm = crypto_alloc_cipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
232	233	if (IS_ERR(essiv_tfm)) {
233	234	ti->error = "Error allocating crypto tfm for ESSIV";
234		- kfree(salt);
235		- return PTR_ERR(essiv_tfm);
	235	+ err = PTR_ERR(essiv_tfm);
	236	+ goto bad;
236	237	}
237	238	if (crypto_cipher_blocksize(essiv_tfm) !=
238	239	crypto_ablkcipher_ivsize(cc->tfm)) {
239	240	ti->error = "Block size of ESSIV cipher does "
240	241	"not match IV size of block cipher";
241		- crypto_free_cipher(essiv_tfm);
242		- kfree(salt);
243		- return -EINVAL;
	242	+ err = -EINVAL;
	243	+ goto bad;
244	244	}
245	245	err = crypto_cipher_setkey(essiv_tfm, salt, saltsize);
246	246	if (err) {
247	247	ti->error = "Failed to set key for ESSIV cipher";
248		- crypto_free_cipher(essiv_tfm);
249		- kfree(salt);
250		- return err;
	248	+ goto bad;
251	249	}
252		- kfree(salt);
	250	+ kzfree(salt);
253	251
254	252	cc->iv_gen_private.essiv.tfm = essiv_tfm;
255	253	return 0;
	254	+
	255	+bad:
	256	+ if (essiv_tfm && !IS_ERR(essiv_tfm))
	257	+ crypto_free_cipher(essiv_tfm);
	258	+ if (hash_tfm && !IS_ERR(hash_tfm))
	259	+ crypto_free_hash(hash_tfm);
	260	+ kzfree(salt);
	261	+ return err;
256	262	}
257	263
258	264	static int crypt_iv_essiv_gen(struct crypt_config cc, u8 iv, sector_t sector)