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Subject[PATCH 2/5] KEYS: user_defined: sanitize key payloads
Date
From: Eric Biggers <ebiggers@google.com>

Zero the payloads of user and logon keys before freeing them. This
prevents sensitive key material from being kept around in the slab
caches after a key is released.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
security/keys/user_defined.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/security/keys/user_defined.c b/security/keys/user_defined.c
index 26605134f17a..3d8c68eba516 100644
--- a/security/keys/user_defined.c
+++ b/security/keys/user_defined.c
@@ -86,10 +86,18 @@ EXPORT_SYMBOL_GPL(user_preparse);
*/
void user_free_preparse(struct key_preparsed_payload *prep)
{
- kfree(prep->payload.data[0]);
+ kzfree(prep->payload.data[0]);
}
EXPORT_SYMBOL_GPL(user_free_preparse);

+static void user_free_payload_rcu(struct rcu_head *head)
+{
+ struct user_key_payload *payload;
+
+ payload = container_of(head, struct user_key_payload, rcu);
+ kzfree(payload);
+}
+
/*
* update a user defined key
* - the key's semaphore is write-locked
@@ -112,7 +120,7 @@ int user_update(struct key *key, struct key_preparsed_payload *prep)
prep->payload.data[0] = NULL;

if (zap)
- kfree_rcu(zap, rcu);
+ call_rcu(&zap->rcu, user_free_payload_rcu);
return ret;
}
EXPORT_SYMBOL_GPL(user_update);
@@ -130,7 +138,7 @@ void user_revoke(struct key *key)

if (upayload) {
rcu_assign_keypointer(key, NULL);
- kfree_rcu(upayload, rcu);
+ call_rcu(&upayload->rcu, user_free_payload_rcu);
}
}

@@ -143,7 +151,7 @@ void user_destroy(struct key *key)
{
struct user_key_payload *upayload = key->payload.data[0];

- kfree(upayload);
+ kzfree(upayload);
}

EXPORT_SYMBOL_GPL(user_destroy);
--
2.12.2
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