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, 25 insertions, 25 deletions

diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c
index 1c898055a476..7b0e13ce7dc7 100644
--- a/security/apparmor/domain.c
+++ b/security/apparmor/domain.c
@@ -40,8 +40,8 @@ void aa_free_domain_entries(struct aa_domain *domain)
 			return;
 
 		for (i = 0; i < domain->size; i++)
-			kzfree(domain->table[i]);
-		kzfree(domain->table);
+			kfree_sensitive(domain->table[i]);
+		kfree_sensitive(domain->table);
 		domain->table = NULL;
 	}
 }
diff --git a/security/apparmor/include/file.h b/security/apparmor/include/file.h
index aff26fc71407..d4f8948517d9 100644
--- a/security/apparmor/include/file.h
+++ b/security/apparmor/include/file.h
@@ -72,7 +72,7 @@ static inline void aa_free_file_ctx(struct aa_file_ctx *ctx)
 {
 	if (ctx) {
 		aa_put_label(rcu_access_pointer(ctx->label));
-		kzfree(ctx);
+		kfree_sensitive(ctx);
 	}
 }
 
diff --git a/security/apparmor/policy.c b/security/apparmor/policy.c
index af4f50fda9e3..4c010c9a6af1 100644
--- a/security/apparmor/policy.c
+++ b/security/apparmor/policy.c
@@ -187,9 +187,9 @@ static void aa_free_data(void *ptr, void *arg)
 {
 	struct aa_data *data = ptr;
 
-	kzfree(data->data);
-	kzfree(data->key);
-	kzfree(data);
+	kfree_sensitive(data->data);
+	kfree_sensitive(data->key);
+	kfree_sensitive(data);
 }
 
 /**
@@ -217,19 +217,19 @@ void aa_free_profile(struct aa_profile *profile)
 	aa_put_profile(rcu_access_pointer(profile->parent));
 
 	aa_put_ns(profile->ns);
-	kzfree(profile->rename);
+	kfree_sensitive(profile->rename);
 
 	aa_free_file_rules(&profile->file);
 	aa_free_cap_rules(&profile->caps);
 	aa_free_rlimit_rules(&profile->rlimits);
 
 	for (i = 0; i < profile->xattr_count; i++)
-		kzfree(profile->xattrs[i]);
-	kzfree(profile->xattrs);
+		kfree_sensitive(profile->xattrs[i]);
+	kfree_sensitive(profile->xattrs);
 	for (i = 0; i < profile->secmark_count; i++)
-		kzfree(profile->secmark[i].label);
-	kzfree(profile->secmark);
-	kzfree(profile->dirname);
+		kfree_sensitive(profile->secmark[i].label);
+	kfree_sensitive(profile->secmark);
+	kfree_sensitive(profile->dirname);
 	aa_put_dfa(profile->xmatch);
 	aa_put_dfa(profile->policy.dfa);
 
@@ -237,14 +237,14 @@ void aa_free_profile(struct aa_profile *profile)
 		rht = profile->data;
 		profile->data = NULL;
 		rhashtable_free_and_destroy(rht, aa_free_data, NULL);
-		kzfree(rht);
+		kfree_sensitive(rht);
 	}
 
-	kzfree(profile->hash);
+	kfree_sensitive(profile->hash);
 	aa_put_loaddata(profile->rawdata);
 	aa_label_destroy(&profile->label);
 
-	kzfree(profile);
+	kfree_sensitive(profile);
 }
 
 /**
diff --git a/security/apparmor/policy_ns.c b/security/apparmor/policy_ns.c
index d7ef540027a5..70921d95fb40 100644
--- a/security/apparmor/policy_ns.c
+++ b/security/apparmor/policy_ns.c
@@ -121,9 +121,9 @@ static struct aa_ns *alloc_ns(const char *prefix, const char *name)
 	return ns;
 
 fail_unconfined:
-	kzfree(ns->base.hname);
+	kfree_sensitive(ns->base.hname);
 fail_ns:
-	kzfree(ns);
+	kfree_sensitive(ns);
 	return NULL;
 }
 
@@ -145,7 +145,7 @@ void aa_free_ns(struct aa_ns *ns)
 
 	ns->unconfined->ns = NULL;
 	aa_free_profile(ns->unconfined);
-	kzfree(ns);
+	kfree_sensitive(ns);
 }
 
 /**
diff --git a/security/apparmor/policy_unpack.c b/security/apparmor/policy_unpack.c
index b67322abcc33..dc345ac93205 100644
--- a/security/apparmor/policy_unpack.c
+++ b/security/apparmor/policy_unpack.c
@@ -163,10 +163,10 @@ static void do_loaddata_free(struct work_struct *work)
 		aa_put_ns(ns);
 	}
 
-	kzfree(d->hash);
-	kzfree(d->name);
+	kfree_sensitive(d->hash);
+	kfree_sensitive(d->name);
 	kvfree(d->data);
-	kzfree(d);
+	kfree_sensitive(d);
 }
 
 void aa_loaddata_kref(struct kref *kref)
@@ -894,7 +894,7 @@ static struct aa_profile *unpack_profile(struct aa_ext *e, char **ns_name)
 		while (unpack_strdup(e, &key, NULL)) {
 			data = kzalloc(sizeof(*data), GFP_KERNEL);
 			if (!data) {
-				kzfree(key);
+				kfree_sensitive(key);
 				goto fail;
 			}
 
@@ -902,8 +902,8 @@ static struct aa_profile *unpack_profile(struct aa_ext *e, char **ns_name)
 			data->size = unpack_blob(e, &data->data, NULL);
 			data->data = kvmemdup(data->data, data->size);
 			if (data->size && !data->data) {
-				kzfree(data->key);
-				kzfree(data);
+				kfree_sensitive(data->key);
+				kfree_sensitive(data);
 				goto fail;
 			}
 
@@ -1037,7 +1037,7 @@ void aa_load_ent_free(struct aa_load_ent *ent)
 		aa_put_profile(ent->old);
 		aa_put_profile(ent->new);
 		kfree(ent->ns_name);
-		kzfree(ent);
+		kfree_sensitive(ent);
 	}
 }