RFC follow-up to https://lkml.kernel.org/r/CAGXu5j+bpLK=EQ9LHkO8V=sdaQwt==6fbGhgn2Vi1E9_WxSGRQ@xxxxxxxxxxxxxx The core API changes: struct crypto_sync_skcipher crypto_alloc_sync_skcipher() crypto_free_sync_skcipher() crypto_sync_skcipher_setkey() skcipher_request_set_sync_tfm() SKCIPHER_REQUEST_ON_STACK type check and a single user's refactoring as an example: drivers/crypto/ccp/ccp-crypto.h drivers/crypto/ccp/ccp-crypto-aes-xts.c Does this look correct? If so, I can continue and do the other 60 instances of SKCIPHER_REQUEST_ON_STACK(). Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> --- crypto/skcipher.c | 24 +++++++++++++++++ drivers/crypto/ccp/ccp-crypto-aes-xts.c | 10 ++++---- drivers/crypto/ccp/ccp-crypto.h | 2 +- include/crypto/skcipher.h | 34 ++++++++++++++++++++++++- 4 files changed, 63 insertions(+), 7 deletions(-) diff --git a/crypto/skcipher.c b/crypto/skcipher.c index 0bd8c6caa498..4caab81d2d02 100644 --- a/crypto/skcipher.c +++ b/crypto/skcipher.c @@ -949,6 +949,30 @@ struct crypto_skcipher *crypto_alloc_skcipher(const char *alg_name, } EXPORT_SYMBOL_GPL(crypto_alloc_skcipher); +struct crypto_sync_skcipher *crypto_alloc_sync_skcipher( + const char *alg_name, u32 type, u32 mask) +{ + struct crypto_skcipher *tfm; + + /* Only sync algorithms allowed. */ + mask |= CRYPTO_ALG_ASYNC; + + tfm = crypto_alloc_tfm(alg_name, &crypto_skcipher_type2, type, mask); + + /* + * Make sure we do not allocate something that might get used with + * an on-stack request: check the request size. + */ + if (!IS_ERR(tfm) && WARN_ON(crypto_skcipher_reqsize(tfm) > + MAX_SYNC_SKCIPHER_REQSIZE)) { + crypto_free_skcipher(tfm); + return ERR_PTR(-EINVAL); + } + + return (struct crypto_sync_skcipher *)tfm; +} +EXPORT_SYMBOL_GPL(crypto_alloc_sync_skcipher); + int crypto_has_skcipher2(const char *alg_name, u32 type, u32 mask) { return crypto_type_has_alg(alg_name, &crypto_skcipher_type2, diff --git a/drivers/crypto/ccp/ccp-crypto-aes-xts.c b/drivers/crypto/ccp/ccp-crypto-aes-xts.c index 94b5bcf5b628..983c921736b4 100644 --- a/drivers/crypto/ccp/ccp-crypto-aes-xts.c +++ b/drivers/crypto/ccp/ccp-crypto-aes-xts.c @@ -102,7 +102,7 @@ static int ccp_aes_xts_setkey(struct crypto_ablkcipher *tfm, const u8 *key, ctx->u.aes.key_len = key_len / 2; sg_init_one(&ctx->u.aes.key_sg, ctx->u.aes.key, key_len); - return crypto_skcipher_setkey(ctx->u.aes.tfm_skcipher, key, key_len); + return crypto_sync_skcipher_setkey(ctx->u.aes.tfm_skcipher, key, key_len); } static int ccp_aes_xts_crypt(struct ablkcipher_request *req, @@ -156,7 +156,7 @@ static int ccp_aes_xts_crypt(struct ablkcipher_request *req, /* Use the fallback to process the request for any * unsupported unit sizes or key sizes */ - skcipher_request_set_tfm(subreq, ctx->u.aes.tfm_skcipher); + skcipher_request_set_sync_tfm(subreq, ctx->u.aes.tfm_skcipher); skcipher_request_set_callback(subreq, req->base.flags, NULL, NULL); skcipher_request_set_crypt(subreq, req->src, req->dst, @@ -203,12 +203,12 @@ static int ccp_aes_xts_decrypt(struct ablkcipher_request *req) static int ccp_aes_xts_cra_init(struct crypto_tfm *tfm) { struct ccp_ctx *ctx = crypto_tfm_ctx(tfm); - struct crypto_skcipher *fallback_tfm; + struct crypto_sync_skcipher *fallback_tfm; ctx->complete = ccp_aes_xts_complete; ctx->u.aes.key_len = 0; - fallback_tfm = crypto_alloc_skcipher("xts(aes)", 0, + fallback_tfm = crypto_alloc_sync_skcipher("xts(aes)", 0, CRYPTO_ALG_ASYNC | CRYPTO_ALG_NEED_FALLBACK); if (IS_ERR(fallback_tfm)) { @@ -226,7 +226,7 @@ static void ccp_aes_xts_cra_exit(struct crypto_tfm *tfm) { struct ccp_ctx *ctx = crypto_tfm_ctx(tfm); - crypto_free_skcipher(ctx->u.aes.tfm_skcipher); + crypto_free_sync_skcipher(ctx->u.aes.tfm_skcipher); } static int ccp_register_aes_xts_alg(struct list_head *head, diff --git a/drivers/crypto/ccp/ccp-crypto.h b/drivers/crypto/ccp/ccp-crypto.h index b9fd090c46c2..28819e11db96 100644 --- a/drivers/crypto/ccp/ccp-crypto.h +++ b/drivers/crypto/ccp/ccp-crypto.h @@ -88,7 +88,7 @@ static inline struct ccp_crypto_ahash_alg * /***** AES related defines *****/ struct ccp_aes_ctx { /* Fallback cipher for XTS with unsupported unit sizes */ - struct crypto_skcipher *tfm_skcipher; + struct crypto_sync_skcipher *tfm_skcipher; /* Cipher used to generate CMAC K1/K2 keys */ struct crypto_cipher *tfm_cipher; diff --git a/include/crypto/skcipher.h b/include/crypto/skcipher.h index 2f327f090c3e..4435f3a3d621 100644 --- a/include/crypto/skcipher.h +++ b/include/crypto/skcipher.h @@ -65,6 +65,10 @@ struct crypto_skcipher { struct crypto_tfm base; }; +struct crypto_sync_skcipher { + struct crypto_skcipher base; +}; + /** * struct skcipher_alg - symmetric key cipher definition * @min_keysize: Minimum key size supported by the transformation. This is the @@ -139,9 +143,17 @@ struct skcipher_alg { struct crypto_alg base; }; +#define MAX_SYNC_SKCIPHER_REQSIZE 384 +/* + * This performs a type-check against the "tfm" argument to make sure + * all users have the correct skcipher tfm for doing on-stack requests. + */ #define SKCIPHER_REQUEST_ON_STACK(name, tfm) \ char __##name##_desc[sizeof(struct skcipher_request) + \ - crypto_skcipher_reqsize(tfm)] CRYPTO_MINALIGN_ATTR; \ + MAX_SYNC_SKCIPHER_REQSIZE + \ + (!(sizeof((struct crypto_sync_skcipher *)1 == \ + (typeof(tfm))1))) \ + ] CRYPTO_MINALIGN_ATTR; \ struct skcipher_request *name = (void *)__##name##_desc /** @@ -197,6 +209,9 @@ static inline struct crypto_skcipher *__crypto_skcipher_cast( struct crypto_skcipher *crypto_alloc_skcipher(const char *alg_name, u32 type, u32 mask); +struct crypto_sync_skcipher *crypto_alloc_sync_skcipher(const char *alg_name, + u32 type, u32 mask); + static inline struct crypto_tfm *crypto_skcipher_tfm( struct crypto_skcipher *tfm) { @@ -212,6 +227,11 @@ static inline void crypto_free_skcipher(struct crypto_skcipher *tfm) crypto_destroy_tfm(tfm, crypto_skcipher_tfm(tfm)); } +static inline void crypto_free_sync_skcipher(struct crypto_sync_skcipher *tfm) +{ + crypto_free_skcipher(&tfm->base); +} + /** * crypto_has_skcipher() - Search for the availability of an skcipher. * @alg_name: is the cra_name / name or cra_driver_name / driver name of the @@ -401,6 +421,12 @@ static inline int crypto_skcipher_setkey(struct crypto_skcipher *tfm, return tfm->setkey(tfm, key, keylen); } +static inline int crypto_sync_skcipher_setkey(struct crypto_sync_skcipher *tfm, + const u8 *key, unsigned int keylen) +{ + return crypto_skcipher_setkey(&tfm->base, key, keylen); +} + static inline unsigned int crypto_skcipher_default_keysize( struct crypto_skcipher *tfm) { @@ -500,6 +526,12 @@ static inline void skcipher_request_set_tfm(struct skcipher_request *req, req->base.tfm = crypto_skcipher_tfm(tfm); } +static inline void skcipher_request_set_sync_tfm(struct skcipher_request *req, + struct crypto_sync_skcipher *tfm) +{ + skcipher_request_set_tfm(req, &tfm->base); +} + static inline struct skcipher_request *skcipher_request_cast( struct crypto_async_request *req) { -- 2.17.1 -- Kees Cook Pixel Security
