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SubjectRe: [PATCH] Use kzfree in crypto API context initialization and key/iv handling
From
From: "Larry H." <research@subreption.com>
Date: Sat, 30 May 2009 19:57:20 -0700

> [PATCH] Use kzfree in crypto API context initialization and key/iv handling

Thanks for not CC:ing the crypto list, and also not CC:'ing the
crypto maintainer.

Your submissions leave a lot to be desired, on every level.

> This patch replaces the kfree() calls within the crypto API (algorithms,
> key setup and handling, etc) with kzfree(), to enforce sanitization of
> the allocated memory.
>
> This prevents such information from persisting on memory and eventually
> leak to other kernel users or during coldboot attacks.
>
> This patch replaces kfree() for context (algorithm meta-data) structures
> too. Those are initialized or released once, and remain in use during the
> lifetime of the cipher/algorithm instance, therefore no performance impact
> exists for those specific changes.
>
> This patch doesn't affect fastpaths.
>
> Signed-off-by: Larry Highsmith <research@subreption.com>
>
> ---
> crypto/ablkcipher.c | 3 +--
> crypto/aead.c | 7 +++----
> crypto/ahash.c | 3 +--
> crypto/algapi.c | 4 ++--
> crypto/algboss.c | 8 ++++----
> crypto/api.c | 13 +++++--------
> crypto/authenc.c | 4 ++--
> crypto/blkcipher.c | 13 +++++++------
> crypto/cbc.c | 2 +-
> crypto/ccm.c | 8 ++++----
> crypto/cipher.c | 3 +--
> crypto/cryptd.c | 4 ++--
> crypto/ctr.c | 2 +-
> crypto/cts.c | 2 +-
> crypto/deflate.c | 4 ++--
> crypto/ecb.c | 2 +-
> crypto/gcm.c | 10 +++++-----
> crypto/gf128mul.c | 4 ++--
> crypto/hash.c | 3 +--
> crypto/hmac.c | 2 +-
> crypto/lrw.c | 2 +-
> crypto/pcbc.c | 2 +-
> crypto/rng.c | 2 +-
> crypto/seqiv.c | 4 ++--
> crypto/shash.c | 3 +--
> crypto/xcbc.c | 2 +-
> crypto/xts.c | 2 +-
> 27 files changed, 55 insertions(+), 63 deletions(-)
>
> Index: linux-2.6/crypto/ablkcipher.c
> ===================================================================
> --- linux-2.6.orig/crypto/ablkcipher.c
> +++ linux-2.6/crypto/ablkcipher.c
> @@ -42,8 +42,7 @@ static int setkey_unaligned(struct crypt
> alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
> memcpy(alignbuffer, key, keylen);
> ret = cipher->setkey(tfm, alignbuffer, keylen);
> - memset(alignbuffer, 0, keylen);
> - kfree(buffer);
> + kzfree(buffer);
> return ret;
> }
>
> Index: linux-2.6/crypto/aead.c
> ===================================================================
> --- linux-2.6.orig/crypto/aead.c
> +++ linux-2.6/crypto/aead.c
> @@ -40,8 +40,7 @@ static int setkey_unaligned(struct crypt
> alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
> memcpy(alignbuffer, key, keylen);
> ret = aead->setkey(tfm, alignbuffer, keylen);
> - memset(alignbuffer, 0, keylen);
> - kfree(buffer);
> + kzfree(buffer);
> return ret;
> }
>
> @@ -298,7 +297,7 @@ out:
> err_drop_alg:
> crypto_drop_aead(spawn);
> err_free_inst:
> - kfree(inst);
> + kzfree(inst);
> inst = ERR_PTR(err);
> goto out;
> }
> @@ -307,7 +306,7 @@ EXPORT_SYMBOL_GPL(aead_geniv_alloc);
> void aead_geniv_free(struct crypto_instance *inst)
> {
> crypto_drop_aead(crypto_instance_ctx(inst));
> - kfree(inst);
> + kzfree(inst);
> }
> EXPORT_SYMBOL_GPL(aead_geniv_free);
>
> Index: linux-2.6/crypto/ahash.c
> ===================================================================
> --- linux-2.6.orig/crypto/ahash.c
> +++ linux-2.6/crypto/ahash.c
> @@ -145,8 +145,7 @@ static int ahash_setkey_unaligned(struct
> alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
> memcpy(alignbuffer, key, keylen);
> ret = ahash->setkey(tfm, alignbuffer, keylen);
> - memset(alignbuffer, 0, keylen);
> - kfree(buffer);
> + kzfree(buffer);
> return ret;
> }
>
> Index: linux-2.6/crypto/algapi.c
> ===================================================================
> --- linux-2.6.orig/crypto/algapi.c
> +++ linux-2.6/crypto/algapi.c
> @@ -185,7 +185,7 @@ out:
> return larval;
>
> free_larval:
> - kfree(larval);
> + kzfree(larval);
> err:
> larval = ERR_PTR(ret);
> goto out;
> @@ -657,7 +657,7 @@ struct crypto_instance *crypto_alloc_ins
> return inst;
>
> err_free_inst:
> - kfree(inst);
> + kzfree(inst);
> return ERR_PTR(err);
> }
> EXPORT_SYMBOL_GPL(crypto_alloc_instance);
> Index: linux-2.6/crypto/algboss.c
> ===================================================================
> --- linux-2.6.orig/crypto/algboss.c
> +++ linux-2.6/crypto/algboss.c
> @@ -81,7 +81,7 @@ static int cryptomgr_probe(void *data)
> goto err;
>
> out:
> - kfree(param);
> + kzfree(param);
> module_put_and_exit(0);
>
> err:
> @@ -193,7 +193,7 @@ static int cryptomgr_schedule_probe(stru
> return NOTIFY_STOP;
>
> err_free_param:
> - kfree(param);
> + kzfree(param);
> err_put_module:
> module_put(THIS_MODULE);
> err:
> @@ -215,7 +215,7 @@ static int cryptomgr_test(void *data)
> skiptest:
> crypto_alg_tested(param->driver, err);
>
> - kfree(param);
> + kzfree(param);
> module_put_and_exit(0);
> }
>
> @@ -242,7 +242,7 @@ static int cryptomgr_schedule_test(struc
> return NOTIFY_STOP;
>
> err_free_param:
> - kfree(param);
> + kzfree(param);
> err_put_module:
> module_put(THIS_MODULE);
> err:
> Index: linux-2.6/crypto/api.c
> ===================================================================
> --- linux-2.6.orig/crypto/api.c
> +++ linux-2.6/crypto/api.c
> @@ -107,7 +107,7 @@ static void crypto_larval_destroy(struct
> BUG_ON(!crypto_is_larval(alg));
> if (larval->adult)
> crypto_mod_put(larval->adult);
> - kfree(larval);
> + kzfree(larval);
> }
>
> struct crypto_larval *crypto_larval_alloc(const char *name, u32 type, u32 mask)
> @@ -151,7 +151,7 @@ static struct crypto_alg *crypto_larval_
> up_write(&crypto_alg_sem);
>
> if (alg != &larval->alg)
> - kfree(larval);
> + kzfree(larval);
>
> return alg;
> }
> @@ -400,7 +400,7 @@ cra_init_failed:
> out_free_tfm:
> if (err == -EAGAIN)
> crypto_shoot_alg(alg);
> - kfree(tfm);
> + kzfree(tfm);
> out_err:
> tfm = ERR_PTR(err);
> out:
> @@ -497,7 +497,7 @@ cra_init_failed:
> out_free_tfm:
> if (err == -EAGAIN)
> crypto_shoot_alg(alg);
> - kfree(mem);
> + kzfree(mem);
> out_err:
> tfm = ERR_PTR(err);
> out:
> @@ -580,20 +580,17 @@ EXPORT_SYMBOL_GPL(crypto_alloc_tfm);
> void crypto_destroy_tfm(void *mem, struct crypto_tfm *tfm)
> {
> struct crypto_alg *alg;
> - int size;
>
> if (unlikely(!mem))
> return;
>
> alg = tfm->__crt_alg;
> - size = ksize(mem);
>
> if (!tfm->exit && alg->cra_exit)
> alg->cra_exit(tfm);
> crypto_exit_ops(tfm);
> crypto_mod_put(alg);
> - memset(mem, 0, size);
> - kfree(mem);
> + kzfree(mem);
> }
> EXPORT_SYMBOL_GPL(crypto_destroy_tfm);
>
> Index: linux-2.6/crypto/authenc.c
> ===================================================================
> --- linux-2.6.orig/crypto/authenc.c
> +++ linux-2.6/crypto/authenc.c
> @@ -461,7 +461,7 @@ err_drop_enc:
> err_drop_auth:
> crypto_drop_spawn(&ctx->auth);
> err_free_inst:
> - kfree(inst);
> + kzfree(inst);
> out_put_auth:
> inst = ERR_PTR(err);
> goto out;
> @@ -473,7 +473,7 @@ static void crypto_authenc_free(struct c
>
> crypto_drop_skcipher(&ctx->enc);
> crypto_drop_spawn(&ctx->auth);
> - kfree(inst);
> + kzfree(inst);
> }
>
> static struct crypto_template crypto_authenc_tmpl = {
> Index: linux-2.6/crypto/blkcipher.c
> ===================================================================
> --- linux-2.6.orig/crypto/blkcipher.c
> +++ linux-2.6/crypto/blkcipher.c
> @@ -136,9 +136,11 @@ err:
> if (walk->iv != desc->info)
> memcpy(desc->info, walk->iv, crypto_blkcipher_ivsize(tfm));
> if (walk->buffer != walk->page)
> - kfree(walk->buffer);
> - if (walk->page)
> + kzfree(walk->buffer);
> + if (walk->page) {
> + memset(walk->page, 0, PAGE_SIZE);
> free_page((unsigned long)walk->page);
> + }
>
> return err;
> }
> @@ -373,8 +375,7 @@ static int setkey_unaligned(struct crypt
> alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
> memcpy(alignbuffer, key, keylen);
> ret = cipher->setkey(tfm, alignbuffer, keylen);
> - memset(alignbuffer, 0, keylen);
> - kfree(buffer);
> + kzfree(buffer);
> return ret;
> }
>
> @@ -661,7 +662,7 @@ out:
> err_drop_alg:
> crypto_drop_skcipher(spawn);
> err_free_inst:
> - kfree(inst);
> + kzfree(inst);
> inst = ERR_PTR(err);
> goto out;
> }
> @@ -670,7 +671,7 @@ EXPORT_SYMBOL_GPL(skcipher_geniv_alloc);
> void skcipher_geniv_free(struct crypto_instance *inst)
> {
> crypto_drop_skcipher(crypto_instance_ctx(inst));
> - kfree(inst);
> + kzfree(inst);
> }
> EXPORT_SYMBOL_GPL(skcipher_geniv_free);
>
> Index: linux-2.6/crypto/cbc.c
> ===================================================================
> --- linux-2.6.orig/crypto/cbc.c
> +++ linux-2.6/crypto/cbc.c
> @@ -264,7 +264,7 @@ out_put_alg:
> static void crypto_cbc_free(struct crypto_instance *inst)
> {
> crypto_drop_spawn(crypto_instance_ctx(inst));
> - kfree(inst);
> + kzfree(inst);
> }
>
> static struct crypto_template crypto_cbc_tmpl = {
> Index: linux-2.6/crypto/ccm.c
> ===================================================================
> --- linux-2.6.orig/crypto/ccm.c
> +++ linux-2.6/crypto/ccm.c
> @@ -565,7 +565,7 @@ err_drop_ctr:
> err_drop_cipher:
> crypto_drop_spawn(&ictx->cipher);
> err_free_inst:
> - kfree(inst);
> + kzfree(inst);
> out_put_cipher:
> inst = ERR_PTR(err);
> goto out;
> @@ -600,7 +600,7 @@ static void crypto_ccm_free(struct crypt
>
> crypto_drop_spawn(&ctx->cipher);
> crypto_drop_skcipher(&ctx->ctr);
> - kfree(inst);
> + kzfree(inst);
> }
>
> static struct crypto_template crypto_ccm_tmpl = {
> @@ -831,7 +831,7 @@ out:
> out_drop_alg:
> crypto_drop_aead(spawn);
> out_free_inst:
> - kfree(inst);
> + kzfree(inst);
> inst = ERR_PTR(err);
> goto out;
> }
> @@ -839,7 +839,7 @@ out_free_inst:
> static void crypto_rfc4309_free(struct crypto_instance *inst)
> {
> crypto_drop_spawn(crypto_instance_ctx(inst));
> - kfree(inst);
> + kzfree(inst);
> }
>
> static struct crypto_template crypto_rfc4309_tmpl = {
> Index: linux-2.6/crypto/cipher.c
> ===================================================================
> --- linux-2.6.orig/crypto/cipher.c
> +++ linux-2.6/crypto/cipher.c
> @@ -37,8 +37,7 @@ static int setkey_unaligned(struct crypt
> alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
> memcpy(alignbuffer, key, keylen);
> ret = cia->cia_setkey(tfm, alignbuffer, keylen);
> - memset(alignbuffer, 0, keylen);
> - kfree(buffer);
> + kzfree(buffer);
> return ret;
>
> }
> Index: linux-2.6/crypto/cryptd.c
> ===================================================================
> --- linux-2.6.orig/crypto/cryptd.c
> +++ linux-2.6/crypto/cryptd.c
> @@ -225,7 +225,7 @@ out:
> return inst;
>
> out_free_inst:
> - kfree(inst);
> + kzfree(inst);
> inst = ERR_PTR(err);
> goto out;
> }
> @@ -527,7 +527,7 @@ static void cryptd_free(struct crypto_in
> struct cryptd_instance_ctx *ctx = crypto_instance_ctx(inst);
>
> crypto_drop_spawn(&ctx->spawn);
> - kfree(inst);
> + kzfree(inst);
> }
>
> static struct crypto_template cryptd_tmpl = {
> Index: linux-2.6/crypto/ctr.c
> ===================================================================
> --- linux-2.6.orig/crypto/ctr.c
> +++ linux-2.6/crypto/ctr.c
> @@ -231,7 +231,7 @@ out_put_alg:
> static void crypto_ctr_free(struct crypto_instance *inst)
> {
> crypto_drop_spawn(crypto_instance_ctx(inst));
> - kfree(inst);
> + kzfree(inst);
> }
>
> static struct crypto_template crypto_ctr_tmpl = {
> Index: linux-2.6/crypto/cts.c
> ===================================================================
> --- linux-2.6.orig/crypto/cts.c
> +++ linux-2.6/crypto/cts.c
> @@ -326,7 +326,7 @@ out_put_alg:
> static void crypto_cts_free(struct crypto_instance *inst)
> {
> crypto_drop_spawn(crypto_instance_ctx(inst));
> - kfree(inst);
> + kzfree(inst);
> }
>
> static struct crypto_template crypto_cts_tmpl = {
> Index: linux-2.6/crypto/deflate.c
> ===================================================================
> --- linux-2.6.orig/crypto/deflate.c
> +++ linux-2.6/crypto/deflate.c
> @@ -86,7 +86,7 @@ static int deflate_decomp_init(struct de
> out:
> return ret;
> out_free:
> - kfree(stream->workspace);
> + kzfree(stream->workspace);
> goto out;
> }
>
> @@ -99,7 +99,7 @@ static void deflate_comp_exit(struct def
> static void deflate_decomp_exit(struct deflate_ctx *ctx)
> {
> zlib_inflateEnd(&ctx->decomp_stream);
> - kfree(ctx->decomp_stream.workspace);
> + kzfree(ctx->decomp_stream.workspace);
> }
>
> static int deflate_init(struct crypto_tfm *tfm)
> Index: linux-2.6/crypto/ecb.c
> ===================================================================
> --- linux-2.6.orig/crypto/ecb.c
> +++ linux-2.6/crypto/ecb.c
> @@ -160,7 +160,7 @@ out_put_alg:
> static void crypto_ecb_free(struct crypto_instance *inst)
> {
> crypto_drop_spawn(crypto_instance_ctx(inst));
> - kfree(inst);
> + kzfree(inst);
> }
>
> static struct crypto_template crypto_ecb_tmpl = {
> Index: linux-2.6/crypto/gcm.c
> ===================================================================
> --- linux-2.6.orig/crypto/gcm.c
> +++ linux-2.6/crypto/gcm.c
> @@ -242,7 +242,7 @@ static int crypto_gcm_setkey(struct cryp
> err = -ENOMEM;
>
> out:
> - kfree(data);
> + kzfree(data);
> return err;
> }
>
> @@ -507,7 +507,7 @@ out:
> out_put_ctr:
> crypto_drop_skcipher(&ctx->ctr);
> err_free_inst:
> - kfree(inst);
> + kzfree(inst);
> inst = ERR_PTR(err);
> goto out;
> }
> @@ -540,7 +540,7 @@ static void crypto_gcm_free(struct crypt
> struct gcm_instance_ctx *ctx = crypto_instance_ctx(inst);
>
> crypto_drop_skcipher(&ctx->ctr);
> - kfree(inst);
> + kzfree(inst);
> }
>
> static struct crypto_template crypto_gcm_tmpl = {
> @@ -762,7 +762,7 @@ out:
> out_drop_alg:
> crypto_drop_aead(spawn);
> out_free_inst:
> - kfree(inst);
> + kzfree(inst);
> inst = ERR_PTR(err);
> goto out;
> }
> @@ -770,7 +770,7 @@ out_free_inst:
> static void crypto_rfc4106_free(struct crypto_instance *inst)
> {
> crypto_drop_spawn(crypto_instance_ctx(inst));
> - kfree(inst);
> + kzfree(inst);
> }
>
> static struct crypto_template crypto_rfc4106_tmpl = {
> Index: linux-2.6/crypto/gf128mul.c
> ===================================================================
> --- linux-2.6.orig/crypto/gf128mul.c
> +++ linux-2.6/crypto/gf128mul.c
> @@ -352,8 +352,8 @@ void gf128mul_free_64k(struct gf128mul_6
> int i;
>
> for (i = 0; i < 16; i++)
> - kfree(t->t[i]);
> - kfree(t);
> + kzfree(t->t[i]);
> + kzfree(t);
> }
> EXPORT_SYMBOL(gf128mul_free_64k);
>
> Index: linux-2.6/crypto/hash.c
> ===================================================================
> --- linux-2.6.orig/crypto/hash.c
> +++ linux-2.6/crypto/hash.c
> @@ -42,8 +42,7 @@ static int hash_setkey_unaligned(struct
> alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
> memcpy(alignbuffer, key, keylen);
> ret = alg->setkey(crt, alignbuffer, keylen);
> - memset(alignbuffer, 0, keylen);
> - kfree(buffer);
> + kzfree(buffer);
> return ret;
> }
>
> Index: linux-2.6/crypto/hmac.c
> ===================================================================
> --- linux-2.6.orig/crypto/hmac.c
> +++ linux-2.6/crypto/hmac.c
> @@ -218,7 +218,7 @@ static void hmac_exit_tfm(struct crypto_
> static void hmac_free(struct crypto_instance *inst)
> {
> crypto_drop_spawn(crypto_instance_ctx(inst));
> - kfree(inst);
> + kzfree(inst);
> }
>
> static struct crypto_instance *hmac_alloc(struct rtattr **tb)
> Index: linux-2.6/crypto/lrw.c
> ===================================================================
> --- linux-2.6.orig/crypto/lrw.c
> +++ linux-2.6/crypto/lrw.c
> @@ -287,7 +287,7 @@ out_put_alg:
> static void free(struct crypto_instance *inst)
> {
> crypto_drop_spawn(crypto_instance_ctx(inst));
> - kfree(inst);
> + kzfree(inst);
> }
>
> static struct crypto_template crypto_tmpl = {
> Index: linux-2.6/crypto/pcbc.c
> ===================================================================
> --- linux-2.6.orig/crypto/pcbc.c
> +++ linux-2.6/crypto/pcbc.c
> @@ -270,7 +270,7 @@ out_put_alg:
> static void crypto_pcbc_free(struct crypto_instance *inst)
> {
> crypto_drop_spawn(crypto_instance_ctx(inst));
> - kfree(inst);
> + kzfree(inst);
> }
>
> static struct crypto_template crypto_pcbc_tmpl = {
> Index: linux-2.6/crypto/rng.c
> ===================================================================
> --- linux-2.6.orig/crypto/rng.c
> +++ linux-2.6/crypto/rng.c
> @@ -42,7 +42,7 @@ static int rngapi_reset(struct crypto_rn
>
> err = crypto_rng_alg(tfm)->rng_reset(tfm, seed, slen);
>
> - kfree(buf);
> + kzfree(buf);
> return err;
> }
>
> Index: linux-2.6/crypto/seqiv.c
> ===================================================================
> --- linux-2.6.orig/crypto/seqiv.c
> +++ linux-2.6/crypto/seqiv.c
> @@ -43,7 +43,7 @@ static void seqiv_complete2(struct skcip
> memcpy(req->creq.info, subreq->info, crypto_ablkcipher_ivsize(geniv));
>
> out:
> - kfree(subreq->info);
> + kzfree(subreq->info);
> }
>
> static void seqiv_complete(struct crypto_async_request *base, int err)
> @@ -69,7 +69,7 @@ static void seqiv_aead_complete2(struct
> memcpy(req->areq.iv, subreq->iv, crypto_aead_ivsize(geniv));
>
> out:
> - kfree(subreq->iv);
> + kzfree(subreq->iv);
> }
>
> static void seqiv_aead_complete(struct crypto_async_request *base, int err)
> Index: linux-2.6/crypto/shash.c
> ===================================================================
> --- linux-2.6.orig/crypto/shash.c
> +++ linux-2.6/crypto/shash.c
> @@ -44,8 +44,7 @@ static int shash_setkey_unaligned(struct
> alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
> memcpy(alignbuffer, key, keylen);
> err = shash->setkey(tfm, alignbuffer, keylen);
> - memset(alignbuffer, 0, keylen);
> - kfree(buffer);
> + kzfree(buffer);
> return err;
> }
>
> Index: linux-2.6/crypto/xcbc.c
> ===================================================================
> --- linux-2.6.orig/crypto/xcbc.c
> +++ linux-2.6/crypto/xcbc.c
> @@ -346,7 +346,7 @@ out_put_alg:
> static void xcbc_free(struct crypto_instance *inst)
> {
> crypto_drop_spawn(crypto_instance_ctx(inst));
> - kfree(inst);
> + kzfree(inst);
> }
>
> static struct crypto_template crypto_xcbc_tmpl = {
> Index: linux-2.6/crypto/xts.c
> ===================================================================
> --- linux-2.6.orig/crypto/xts.c
> +++ linux-2.6/crypto/xts.c
> @@ -264,7 +264,7 @@ out_put_alg:
> static void free(struct crypto_instance *inst)
> {
> crypto_drop_spawn(crypto_instance_ctx(inst));
> - kfree(inst);
> + kzfree(inst);
> }
>
> static struct crypto_template crypto_tmpl = {
> --
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