diff --git a/crypto/Kconfig b/crypto/Kconfig index 1d33beb6a1ae..c903f1832f2c 100644 --- a/crypto/Kconfig +++ b/crypto/Kconfig @@ -1567,6 +1567,7 @@ config CRYPTO_DRBG_HASH config CRYPTO_DRBG_CTR bool "Enable CTR DRBG" select CRYPTO_AES + depends on CRYPTO_CTR help Enable the CTR DRBG variant as defined in NIST SP800-90A. diff --git a/crypto/drbg.c b/crypto/drbg.c index 0aca2b908c76..4ee1a9c79420 100644 --- a/crypto/drbg.c +++ b/crypto/drbg.c @@ -258,6 +258,7 @@ static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval, const struct drbg_string *in); static int drbg_init_sym_kernel(struct drbg_state *drbg); static int drbg_fini_sym_kernel(struct drbg_state *drbg); +static int drbg_kcapi_sym_ctr(struct drbg_state *drbg, u8 *outbuf, u32 outlen); /* BCC function for CTR DRBG as defined in 10.4.3 */ static int drbg_ctr_bcc(struct drbg_state *drbg, @@ -482,35 +483,36 @@ static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed, drbg_blocklen(drbg); unsigned char *temp_p, *df_data_p; /* pointer to iterate over buffers */ unsigned int len = 0; - struct drbg_string cipherin; if (3 > reseed) memset(df_data, 0, drbg_statelen(drbg)); + if (!reseed) { + /* + * The DRBG uses the CTR mode of the underlying AES cipher. The + * CTR mode increments the counter value after the AES operation + * but SP800-90A requires that the counter is incremented before + * the AES operation. Hence, we increment it at the time we set + * it by one. + */ + crypto_inc(drbg->V, drbg_blocklen(drbg)); + + ret = crypto_skcipher_setkey(drbg->ctr_handle, drbg->C, + drbg_keylen(drbg)); + if (ret) + goto out; + } + /* 10.2.1.3.2 step 2 and 10.2.1.4.2 step 2 */ if (seed) { ret = drbg_ctr_df(drbg, df_data, drbg_statelen(drbg), seed); if (ret) goto out; - drbg_kcapi_symsetkey(drbg, drbg->C); } - drbg_string_fill(&cipherin, drbg->V, drbg_blocklen(drbg)); - /* - * 10.2.1.3.2 steps 2 and 3 are already covered as the allocation - * zeroizes all memory during initialization - */ - while (len < (drbg_statelen(drbg))) { - /* 10.2.1.2 step 2.1 */ - crypto_inc(drbg->V, drbg_blocklen(drbg)); - /* - * 10.2.1.2 step 2.2 */ - ret = drbg_kcapi_sym(drbg, temp + len, &cipherin); - if (ret) - goto out; - /* 10.2.1.2 step 2.3 and 3 */ - len += drbg_blocklen(drbg); - } + ret = drbg_kcapi_sym_ctr(drbg, temp, drbg_statelen(drbg)); + if (ret) + return ret; /* 10.2.1.2 step 4 */ temp_p = temp; @@ -522,9 +524,14 @@ static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed, /* 10.2.1.2 step 5 */ memcpy(drbg->C, temp, drbg_keylen(drbg)); - drbg_kcapi_symsetkey(drbg, drbg->C); + ret = crypto_skcipher_setkey(drbg->ctr_handle, drbg->C, + drbg_keylen(drbg)); + if (ret) + goto out; /* 10.2.1.2 step 6 */ memcpy(drbg->V, temp + drbg_keylen(drbg), drbg_blocklen(drbg)); + /* See above: increment counter by one to compensate timing of CTR op */ + crypto_inc(drbg->V, drbg_blocklen(drbg)); ret = 0; out: @@ -543,46 +550,26 @@ static int drbg_ctr_generate(struct drbg_state *drbg, unsigned char *buf, unsigned int buflen, struct list_head *addtl) { - int len = 0; - int ret = 0; - struct drbg_string data; + int ret; + int len = min_t(int, buflen, INT_MAX); /* 10.2.1.5.2 step 2 */ if (addtl && !list_empty(addtl)) { ret = drbg_ctr_update(drbg, addtl, 2); if (ret) return 0; - drbg_kcapi_symsetkey(drbg, drbg->C); } /* 10.2.1.5.2 step 4.1 */ - crypto_inc(drbg->V, drbg_blocklen(drbg)); - drbg_string_fill(&data, drbg->V, drbg_blocklen(drbg)); - while (len < buflen) { - int outlen = 0; - /* 10.2.1.5.2 step 4.2 */ - ret = drbg_kcapi_sym(drbg, drbg->scratchpad, &data); - if (ret) { - len = ret; - goto out; - } - outlen = (drbg_blocklen(drbg) < (buflen - len)) ? - drbg_blocklen(drbg) : (buflen - len); - /* 10.2.1.5.2 step 4.3 */ - memcpy(buf + len, drbg->scratchpad, outlen); - len += outlen; - /* 10.2.1.5.2 step 6 */ - if (len < buflen) - crypto_inc(drbg->V, drbg_blocklen(drbg)); - } + ret = drbg_kcapi_sym_ctr(drbg, buf, len); + if (ret) + return ret; /* 10.2.1.5.2 step 6 */ ret = drbg_ctr_update(drbg, NULL, 3); if (ret) len = ret; -out: - memset(drbg->scratchpad, 0, drbg_blocklen(drbg)); return len; } @@ -1634,10 +1621,46 @@ static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval, #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */ #ifdef CONFIG_CRYPTO_DRBG_CTR +static int drbg_fini_sym_kernel(struct drbg_state *drbg) +{ + struct crypto_cipher *tfm = + (struct crypto_cipher *)drbg->priv_data; + if (tfm) + crypto_free_cipher(tfm); + drbg->priv_data = NULL; + + if (drbg->ctr_handle) + crypto_free_skcipher(drbg->ctr_handle); + drbg->ctr_handle = NULL; + + if (drbg->ctr_req) + skcipher_request_free(drbg->ctr_req);; + drbg->ctr_req = NULL; + + kfree(drbg->ctr_null_value_buf); + drbg->ctr_null_value = NULL; + + return 0; +} + +static void drbg_skcipher_cb(struct crypto_async_request *req, int error) +{ + struct drbg_state *drbg = req->data; + + if (error == -EINPROGRESS) + return; + drbg->ctr_async_err = error; + complete(&drbg->ctr_completion); +} + +#define DRBG_CTR_NULL_LEN 128 static int drbg_init_sym_kernel(struct drbg_state *drbg) { - int ret = 0; struct crypto_cipher *tfm; + struct crypto_skcipher *sk_tfm; + struct skcipher_request *req; + unsigned int alignmask; + char ctr_name[CRYPTO_MAX_ALG_NAME]; tfm = crypto_alloc_cipher(drbg->core->backend_cra_name, 0, 0); if (IS_ERR(tfm)) { @@ -1647,16 +1670,41 @@ static int drbg_init_sym_kernel(struct drbg_state *drbg) } BUG_ON(drbg_blocklen(drbg) != crypto_cipher_blocksize(tfm)); drbg->priv_data = tfm; - return ret; -} -static int drbg_fini_sym_kernel(struct drbg_state *drbg) -{ - struct crypto_cipher *tfm = - (struct crypto_cipher *)drbg->priv_data; - if (tfm) - crypto_free_cipher(tfm); - drbg->priv_data = NULL; + if (snprintf(ctr_name, CRYPTO_MAX_ALG_NAME, "ctr(%s)", + drbg->core->backend_cra_name) >= CRYPTO_MAX_ALG_NAME) { + drbg_fini_sym_kernel(drbg); + return -EINVAL; + } + sk_tfm = crypto_alloc_skcipher(ctr_name, 0, 0); + if (IS_ERR(sk_tfm)) { + pr_info("DRBG: could not allocate CTR cipher TFM handle: %s\n", + ctr_name); + drbg_fini_sym_kernel(drbg); + return PTR_ERR(sk_tfm); + } + drbg->ctr_handle = sk_tfm; + + req = skcipher_request_alloc(sk_tfm, GFP_KERNEL); + if (!req) { + pr_info("DRBG: could not allocate request queue\n"); + drbg_fini_sym_kernel(drbg); + return PTR_ERR(req); + } + drbg->ctr_req = req; + skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, + drbg_skcipher_cb, drbg); + + alignmask = crypto_skcipher_alignmask(sk_tfm); + drbg->ctr_null_value_buf = kzalloc(DRBG_CTR_NULL_LEN + alignmask, + GFP_KERNEL); + if (!drbg->ctr_null_value_buf) { + drbg_fini_sym_kernel(drbg); + return -ENOMEM; + } + drbg->ctr_null_value = (u8 *)PTR_ALIGN(drbg->ctr_null_value_buf, + alignmask + 1); + return 0; } @@ -1680,6 +1728,43 @@ static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval, crypto_cipher_encrypt_one(tfm, outval, in->buf); return 0; } + +static int drbg_kcapi_sym_ctr(struct drbg_state *drbg, u8 *outbuf, u32 outlen) +{ + struct scatterlist sg_in; + + sg_init_one(&sg_in, drbg->ctr_null_value, DRBG_CTR_NULL_LEN); + + while (outlen) { + u32 cryptlen = min_t(u32, outlen, DRBG_CTR_NULL_LEN); + struct scatterlist sg_out; + int ret; + + sg_init_one(&sg_out, outbuf, cryptlen); + skcipher_request_set_crypt(drbg->ctr_req, &sg_in, &sg_out, + cryptlen, drbg->V); + ret = crypto_skcipher_encrypt(drbg->ctr_req); + switch (ret) { + case 0: + break; + case -EINPROGRESS: + case -EBUSY: + ret = wait_for_completion_interruptible( + &drbg->ctr_completion); + if (!ret && !drbg->ctr_async_err) { + reinit_completion(&drbg->ctr_completion); + break; + } + default: + return ret; + } + init_completion(&drbg->ctr_completion); + + outlen -= cryptlen; + } + + return 0; +} #endif /* CONFIG_CRYPTO_DRBG_CTR */ /*************************************************************** diff --git a/include/crypto/drbg.h b/include/crypto/drbg.h index d961b2b16f55..b2fe15d1ceba 100644 --- a/include/crypto/drbg.h +++ b/include/crypto/drbg.h @@ -43,6 +43,7 @@ #include #include #include +#include #include #include #include @@ -115,6 +116,14 @@ struct drbg_state { /* some memory the DRBG can use for its operation */ unsigned char *scratchpad; void *priv_data; /* Cipher handle */ + + struct crypto_skcipher *ctr_handle; /* CTR mode cipher handle */ + struct skcipher_request *ctr_req; /* CTR mode request handle */ + __u8 *ctr_null_value_buf; /* CTR mode unaligned buffer */ + __u8 *ctr_null_value; /* CTR mode aligned zero buf */ + struct completion ctr_completion; /* CTR mode async handler */ + int ctr_async_err; /* CTR mode async error */ + bool seeded; /* DRBG fully seeded? */ bool pr; /* Prediction resistance enabled? */ struct work_struct seed_work; /* asynchronous seeding support */