From 79e886599e6416d0de26e8562e4464577d081c3d Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Wed, 19 Nov 2014 17:13:11 +0100 Subject: 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 Signed-off-by: Daniel Borkmann Signed-off-by: Herbert Xu --- crypto/algif_hash.c | 6 ++---- crypto/algif_skcipher.c | 3 +-- 2 files changed, 3 insertions(+), 6 deletions(-) (limited to 'crypto') diff --git a/crypto/algif_hash.c b/crypto/algif_hash.c index f75db4ce48bf..e6050396a3b3 100644 --- a/crypto/algif_hash.c +++ b/crypto/algif_hash.c @@ -258,10 +258,8 @@ static void hash_sock_destruct(struct sock *sk) struct alg_sock *ask = alg_sk(sk); struct hash_ctx *ctx = ask->private; - memzero_explicit(ctx->result, - crypto_ahash_digestsize(crypto_ahash_reqtfm(&ctx->req))); - sock_kfree_s(sk, ctx->result, - crypto_ahash_digestsize(crypto_ahash_reqtfm(&ctx->req))); + sock_kzfree_s(sk, ctx->result, + crypto_ahash_digestsize(crypto_ahash_reqtfm(&ctx->req))); sock_kfree_s(sk, ctx, ctx->len); af_alg_release_parent(sk); } diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c index 85e3bdbe214c..34389964000d 100644 --- a/crypto/algif_skcipher.c +++ b/crypto/algif_skcipher.c @@ -566,8 +566,7 @@ static void skcipher_sock_destruct(struct sock *sk) struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(&ctx->req); skcipher_free_sgl(sk); - memzero_explicit(ctx->iv, crypto_ablkcipher_ivsize(tfm)); - sock_kfree_s(sk, ctx->iv, crypto_ablkcipher_ivsize(tfm)); + sock_kzfree_s(sk, ctx->iv, crypto_ablkcipher_ivsize(tfm)); sock_kfree_s(sk, ctx, ctx->len); af_alg_release_parent(sk); } -- cgit