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authorDaniel Borkmann <dborkman@redhat.com>2014-11-19 17:13:11 +0100
committerHerbert Xu <herbert@gondor.apana.org.au>2014-11-25 22:50:39 +0800
commit79e886599e6416d0de26e8562e4464577d081c3d (patch)
tree83a545d589f1bb7ba5de28cc768ce549598fd0b2 /net
parent5d26a105b5a73e5635eae0629b42fa0a90e07b7b (diff)
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crypto: algif - add and use sock_kzfree_s() instead of memzero_explicit()
Commit e1bd95bf7c25 ("crypto: algif - zeroize IV buffer") and 2a6af25befd0 ("crypto: algif - zeroize message digest buffer") added memzero_explicit() calls on buffers that are later on passed back to sock_kfree_s(). This is a discussed follow-up that, instead, extends the sock API and adds sock_kzfree_s(), which internally uses kzfree() instead of kfree() for passing the buffers back to slab. Having sock_kzfree_s() allows to keep the changes more minimal by just having a drop-in replacement instead of adding memzero_explicit() calls everywhere before sock_kfree_s(). In kzfree(), the compiler is not allowed to optimize the memset() away and thus there's no need for memzero_explicit(). Both, sock_kfree_s() and sock_kzfree_s() are wrappers for __sock_kfree_s() and call into kfree() resp. kzfree(); here, __sock_kfree_s() needs to be explicitly inlined as we want the compiler to optimize the call and condition away and thus it produces e.g. on x86_64 the _same_ assembler output for sock_kfree_s() before and after, and thus also allows for avoiding code duplication. Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Daniel Borkmann <dborkman@redhat.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'net')
-rw-r--r--net/core/sock.c24
1 files changed, 20 insertions, 4 deletions
diff --git a/net/core/sock.c b/net/core/sock.c
index 15e0c67b1069..04ce26a996bd 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1713,18 +1713,34 @@ void *sock_kmalloc(struct sock *sk, int size, gfp_t priority)
}
EXPORT_SYMBOL(sock_kmalloc);
-/*
- * Free an option memory block.
+/* Free an option memory block. Note, we actually want the inline
+ * here as this allows gcc to detect the nullify and fold away the
+ * condition entirely.
*/
-void sock_kfree_s(struct sock *sk, void *mem, int size)
+static inline void __sock_kfree_s(struct sock *sk, void *mem, int size,
+ const bool nullify)
{
if (WARN_ON_ONCE(!mem))
return;
- kfree(mem);
+ if (nullify)
+ kzfree(mem);
+ else
+ kfree(mem);
atomic_sub(size, &sk->sk_omem_alloc);
}
+
+void sock_kfree_s(struct sock *sk, void *mem, int size)
+{
+ __sock_kfree_s(sk, mem, size, false);
+}
EXPORT_SYMBOL(sock_kfree_s);
+void sock_kzfree_s(struct sock *sk, void *mem, int size)
+{
+ __sock_kfree_s(sk, mem, size, true);
+}
+EXPORT_SYMBOL(sock_kzfree_s);
+
/* It is almost wait_for_tcp_memory minus release_sock/lock_sock.
I think, these locks should be removed for datagram sockets.
*/