From a6878d570da5f01aad25edebe244f125e6f0efb1 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Sun, 7 Sep 2014 23:23:38 +0200 Subject: [PATCH] crypto: memzero_explicit - make sure to clear out sensitive data Recently, in commit 13aa93c70e71 ("random: add and use memzero_explicit() for clearing data"), we have found that GCC may optimize some memset() cases away when it detects a stack variable is not being used anymore and going out of scope. This can happen, for example, in cases when we are clearing out sensitive information such as keying material or any e.g. intermediate results from crypto computations, etc. With the help of Coccinelle, we can figure out and fix such occurences in the crypto subsytem as well. Julia Lawall provided the following Coccinelle program: @@ type T; identifier x; @@ T x; ... when exists when any -memset +memzero_explicit (&x, -0, ...) ... when != x when strict @@ type T; identifier x; @@ T x[...]; ... when exists when any -memset +memzero_explicit (x, -0, ...) ... when != x when strict Therefore, make use of the drop-in replacement memzero_explicit() for exactly such cases instead of using memset(). Signed-off-by: Daniel Borkmann Cc: Julia Lawall Cc: Herbert Xu Cc: Theodore Ts'o Cc: Hannes Frederic Sowa Acked-by: Hannes Frederic Sowa Acked-by: Herbert Xu Signed-off-by: Theodore Ts'o --- crypto/cts.c | 3 ++- crypto/sha1_generic.c | 2 +- crypto/sha256_generic.c | 5 ++--- crypto/sha512_generic.c | 2 +- crypto/tgr192.c | 4 ++-- crypto/vmac.c | 2 +- crypto/wp512.c | 8 ++++---- 7 files changed, 13 insertions(+), 13 deletions(-) diff --git a/crypto/cts.c b/crypto/cts.c index 60b9da3fa7c1..bd9405820e8a 100644 --- a/crypto/cts.c +++ b/crypto/cts.c @@ -202,7 +202,8 @@ static int cts_cbc_decrypt(struct crypto_cts_ctx *ctx, /* 5. Append the tail (BB - Ln) bytes of Xn (tmp) to Cn to create En */ memcpy(s + bsize + lastn, tmp + lastn, bsize - lastn); /* 6. Decrypt En to create Pn-1 */ - memset(iv, 0, sizeof(iv)); + memzero_explicit(iv, sizeof(iv)); + sg_set_buf(&sgsrc[0], s + bsize, bsize); sg_set_buf(&sgdst[0], d, bsize); err = crypto_blkcipher_decrypt_iv(&lcldesc, sgdst, sgsrc, bsize); diff --git a/crypto/sha1_generic.c b/crypto/sha1_generic.c index fdf7c00de4b0..a3e50c37eb6f 100644 --- a/crypto/sha1_generic.c +++ b/crypto/sha1_generic.c @@ -64,7 +64,7 @@ int crypto_sha1_update(struct shash_desc *desc, const u8 *data, src = data + done; } while (done + SHA1_BLOCK_SIZE <= len); - memset(temp, 0, sizeof(temp)); + memzero_explicit(temp, sizeof(temp)); partial = 0; } memcpy(sctx->buffer + partial, src, len - done); diff --git a/crypto/sha256_generic.c b/crypto/sha256_generic.c index 136381bdd48d..cde0361b9075 100644 --- a/crypto/sha256_generic.c +++ b/crypto/sha256_generic.c @@ -210,10 +210,9 @@ static void sha256_transform(u32 *state, const u8 *input) /* clear any sensitive info... */ a = b = c = d = e = f = g = h = t1 = t2 = 0; - memset(W, 0, 64 * sizeof(u32)); + memzero_explicit(W, 64 * sizeof(u32)); } - static int sha224_init(struct shash_desc *desc) { struct sha256_state *sctx = shash_desc_ctx(desc); @@ -316,7 +315,7 @@ static int sha224_final(struct shash_desc *desc, u8 *hash) sha256_final(desc, D); memcpy(hash, D, SHA224_DIGEST_SIZE); - memset(D, 0, SHA256_DIGEST_SIZE); + memzero_explicit(D, SHA256_DIGEST_SIZE); return 0; } diff --git a/crypto/sha512_generic.c b/crypto/sha512_generic.c index fb2d7b8f163f..15330a121279 100644 --- a/crypto/sha512_generic.c +++ b/crypto/sha512_generic.c @@ -238,7 +238,7 @@ static int sha384_final(struct shash_desc *desc, u8 *hash) sha512_final(desc, D); memcpy(hash, D, 48); - memset(D, 0, 64); + memzero_explicit(D, 64); return 0; } diff --git a/crypto/tgr192.c b/crypto/tgr192.c index f7ed2fba396c..321bc6ff2a9d 100644 --- a/crypto/tgr192.c +++ b/crypto/tgr192.c @@ -612,7 +612,7 @@ static int tgr160_final(struct shash_desc *desc, u8 * out) tgr192_final(desc, D); memcpy(out, D, TGR160_DIGEST_SIZE); - memset(D, 0, TGR192_DIGEST_SIZE); + memzero_explicit(D, TGR192_DIGEST_SIZE); return 0; } @@ -623,7 +623,7 @@ static int tgr128_final(struct shash_desc *desc, u8 * out) tgr192_final(desc, D); memcpy(out, D, TGR128_DIGEST_SIZE); - memset(D, 0, TGR192_DIGEST_SIZE); + memzero_explicit(D, TGR192_DIGEST_SIZE); return 0; } diff --git a/crypto/vmac.c b/crypto/vmac.c index bf2d3a89845f..df76a816cfb2 100644 --- a/crypto/vmac.c +++ b/crypto/vmac.c @@ -613,7 +613,7 @@ static int vmac_final(struct shash_desc *pdesc, u8 *out) } mac = vmac(ctx->partial, ctx->partial_size, nonce, NULL, ctx); memcpy(out, &mac, sizeof(vmac_t)); - memset(&mac, 0, sizeof(vmac_t)); + memzero_explicit(&mac, sizeof(vmac_t)); memset(&ctx->__vmac_ctx, 0, sizeof(struct vmac_ctx)); ctx->partial_size = 0; return 0; diff --git a/crypto/wp512.c b/crypto/wp512.c index 253db94b5479..7ee5a043a988 100644 --- a/crypto/wp512.c +++ b/crypto/wp512.c @@ -1102,8 +1102,8 @@ static int wp384_final(struct shash_desc *desc, u8 *out) u8 D[64]; wp512_final(desc, D); - memcpy (out, D, WP384_DIGEST_SIZE); - memset (D, 0, WP512_DIGEST_SIZE); + memcpy(out, D, WP384_DIGEST_SIZE); + memzero_explicit(D, WP512_DIGEST_SIZE); return 0; } @@ -1113,8 +1113,8 @@ static int wp256_final(struct shash_desc *desc, u8 *out) u8 D[64]; wp512_final(desc, D); - memcpy (out, D, WP256_DIGEST_SIZE); - memset (D, 0, WP512_DIGEST_SIZE); + memcpy(out, D, WP256_DIGEST_SIZE); + memzero_explicit(D, WP512_DIGEST_SIZE); return 0; }