mm, treewide: rename kzfree() to kfree_sensitive()

As said by Linus:

  A symmetric naming is only helpful if it implies symmetries in use.
  Otherwise it's actively misleading.

  In "kzalloc()", the z is meaningful and an important part of what the
  caller wants.

  In "kzfree()", the z is actively detrimental, because maybe in the
  future we really _might_ want to use that "memfill(0xdeadbeef)" or
  something. The "zero" part of the interface isn't even _relevant_.

The main reason that kzfree() exists is to clear sensitive information
that should not be leaked to other future users of the same memory
objects.

Rename kzfree() to kfree_sensitive() to follow the example of the recently
added kvfree_sensitive() and make the intention of the API more explicit.
In addition, memzero_explicit() is used to clear the memory to make sure
that it won't get optimized away by the compiler.

The renaming is done by using the command sequence:

  git grep -w --name-only kzfree |\
  xargs sed -i 's/kzfree/kfree_sensitive/'

followed by some editing of the kfree_sensitive() kerneldoc and adding
a kzfree backward compatibility macro in slab.h.

[akpm@linux-foundation.org: fs/crypto/inline_crypt.c needs linux/slab.h]
[akpm@linux-foundation.org: fix fs/crypto/inline_crypt.c some more]

Suggested-by: Joe Perches <joe@perches.com>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: David Howells <dhowells@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: James Morris <jmorris@namei.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Joe Perches <joe@perches.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Jason A . Donenfeld" <Jason@zx2c4.com>
Link: http://lkml.kernel.org/r/20200616154311.12314-3-longman@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

5 files changed, 12 insertions, 12 deletions

diff --git a/drivers/crypto/ccree/cc_aead.c b/drivers/crypto/ccree/cc_aead.c
index 1cf51edbc4b9..35794c7271fb 100644
--- a/drivers/crypto/ccree/cc_aead.c
+++ b/drivers/crypto/ccree/cc_aead.c
@@ -448,7 +448,7 @@ static int cc_get_plain_hmac_key(struct crypto_aead *tfm, const u8 *authkey,
 		if (dma_mapping_error(dev, key_dma_addr)) {
 			dev_err(dev, "Mapping key va=0x%p len=%u for DMA failed\n",
 				key, keylen);
-			kzfree(key);
+			kfree_sensitive(key);
 			return -ENOMEM;
 		}
 		if (keylen > blocksize) {
@@ -533,7 +533,7 @@ static int cc_get_plain_hmac_key(struct crypto_aead *tfm, const u8 *authkey,
 	if (key_dma_addr)
 		dma_unmap_single(dev, key_dma_addr, keylen, DMA_TO_DEVICE);
 
-	kzfree(key);
+	kfree_sensitive(key);
 
 	return rc;
 }
diff --git a/drivers/crypto/ccree/cc_buffer_mgr.c b/drivers/crypto/ccree/cc_buffer_mgr.c
index b2bd093e7013..a5e041d9d2cf 100644
--- a/drivers/crypto/ccree/cc_buffer_mgr.c
+++ b/drivers/crypto/ccree/cc_buffer_mgr.c
@@ -488,7 +488,7 @@ void cc_unmap_aead_request(struct device *dev, struct aead_request *req)
 	if (areq_ctx->gen_ctx.iv_dma_addr) {
 		dma_unmap_single(dev, areq_ctx->gen_ctx.iv_dma_addr,
 				 hw_iv_size, DMA_BIDIRECTIONAL);
-		kzfree(areq_ctx->gen_ctx.iv);
+		kfree_sensitive(areq_ctx->gen_ctx.iv);
 	}
 
 	/* Release pool */
@@ -559,7 +559,7 @@ static int cc_aead_chain_iv(struct cc_drvdata *drvdata,
 	if (dma_mapping_error(dev, areq_ctx->gen_ctx.iv_dma_addr)) {
 		dev_err(dev, "Mapping iv %u B at va=%pK for DMA failed\n",
 			hw_iv_size, req->iv);
-		kzfree(areq_ctx->gen_ctx.iv);
+		kfree_sensitive(areq_ctx->gen_ctx.iv);
 		areq_ctx->gen_ctx.iv = NULL;
 		rc = -ENOMEM;
 		goto chain_iv_exit;
diff --git a/drivers/crypto/ccree/cc_cipher.c b/drivers/crypto/ccree/cc_cipher.c
index 076669dc1035..d77ae981b64b 100644
--- a/drivers/crypto/ccree/cc_cipher.c
+++ b/drivers/crypto/ccree/cc_cipher.c
@@ -257,7 +257,7 @@ static void cc_cipher_exit(struct crypto_tfm *tfm)
 		&ctx_p->user.key_dma_addr);
 
 	/* Free key buffer in context */
-	kzfree(ctx_p->user.key);
+	kfree_sensitive(ctx_p->user.key);
 	dev_dbg(dev, "Free key buffer in context. key=@%p\n", ctx_p->user.key);
 }
 
@@ -881,7 +881,7 @@ static void cc_cipher_complete(struct device *dev, void *cc_req, int err)
 		/* Not a BACKLOG notification */
 		cc_unmap_cipher_request(dev, req_ctx, ivsize, src, dst);
 		memcpy(req->iv, req_ctx->iv, ivsize);
-		kzfree(req_ctx->iv);
+		kfree_sensitive(req_ctx->iv);
 	}
 
 	skcipher_request_complete(req, err);
@@ -994,7 +994,7 @@ static int cc_cipher_process(struct skcipher_request *req,
 
 exit_process:
 	if (rc != -EINPROGRESS && rc != -EBUSY) {
-		kzfree(req_ctx->iv);
+		kfree_sensitive(req_ctx->iv);
 	}
 
 	return rc;
diff --git a/drivers/crypto/ccree/cc_hash.c b/drivers/crypto/ccree/cc_hash.c
index d5310783af15..683c9a430e11 100644
--- a/drivers/crypto/ccree/cc_hash.c
+++ b/drivers/crypto/ccree/cc_hash.c
@@ -764,7 +764,7 @@ static int cc_hash_setkey(struct crypto_ahash *ahash, const u8 *key,
 		if (dma_mapping_error(dev, ctx->key_params.key_dma_addr)) {
 			dev_err(dev, "Mapping key va=0x%p len=%u for DMA failed\n",
 				ctx->key_params.key, keylen);
-			kzfree(ctx->key_params.key);
+			kfree_sensitive(ctx->key_params.key);
 			return -ENOMEM;
 		}
 		dev_dbg(dev, "mapping key-buffer: key_dma_addr=%pad keylen=%u\n",
@@ -913,7 +913,7 @@ out:
 			&ctx->key_params.key_dma_addr, ctx->key_params.keylen);
 	}
 
-	kzfree(ctx->key_params.key);
+	kfree_sensitive(ctx->key_params.key);
 
 	return rc;
 }
@@ -950,7 +950,7 @@ static int cc_xcbc_setkey(struct crypto_ahash *ahash,
 	if (dma_mapping_error(dev, ctx->key_params.key_dma_addr)) {
 		dev_err(dev, "Mapping key va=0x%p len=%u for DMA failed\n",
 			key, keylen);
-		kzfree(ctx->key_params.key);
+		kfree_sensitive(ctx->key_params.key);
 		return -ENOMEM;
 	}
 	dev_dbg(dev, "mapping key-buffer: key_dma_addr=%pad keylen=%u\n",
@@ -999,7 +999,7 @@ static int cc_xcbc_setkey(struct crypto_ahash *ahash,
 	dev_dbg(dev, "Unmapped key-buffer: key_dma_addr=%pad keylen=%u\n",
 		&ctx->key_params.key_dma_addr, ctx->key_params.keylen);
 
-	kzfree(ctx->key_params.key);
+	kfree_sensitive(ctx->key_params.key);
 
 	return rc;
 }
diff --git a/drivers/crypto/ccree/cc_request_mgr.c b/drivers/crypto/ccree/cc_request_mgr.c
index 1d7649ecf44e..33fb27745d52 100644
--- a/drivers/crypto/ccree/cc_request_mgr.c
+++ b/drivers/crypto/ccree/cc_request_mgr.c
@@ -107,7 +107,7 @@ void cc_req_mgr_fini(struct cc_drvdata *drvdata)
 	/* Kill tasklet */
 	tasklet_kill(&req_mgr_h->comptask);
 #endif
-	kzfree(req_mgr_h);
+	kfree_sensitive(req_mgr_h);
 	drvdata->request_mgr_handle = NULL;
 }