From: Eric Biggers ebiggers@google.com
commit 6a1faa4a43f5fabf9cbeaa742d916e7b5e73120f upstream.
CCM instances can be created by either the "ccm" template, which only allows choosing the block cipher, e.g. "ccm(aes)"; or by "ccm_base", which allows choosing the ctr and cbcmac implementations, e.g. "ccm_base(ctr(aes-generic),cbcmac(aes-generic))".
However, a "ccm_base" instance prevents a "ccm" instance from being registered using the same implementations. Nor will the instance be found by lookups of "ccm". This can be used as a denial of service. Moreover, "ccm_base" instances are never tested by the crypto self-tests, even if there are compatible "ccm" tests.
The root cause of these problems is that instances of the two templates use different cra_names. Therefore, fix these problems by making "ccm_base" instances set the same cra_name as "ccm" instances, e.g. "ccm(aes)" instead of "ccm_base(ctr(aes-generic),cbcmac(aes-generic))".
This requires extracting the block cipher name from the name of the ctr and cbcmac algorithms. It also requires starting to verify that the algorithms are really ctr and cbcmac using the same block cipher, not something else entirely. But it would be bizarre if anyone were actually using non-ccm-compatible algorithms with ccm_base, so this shouldn't break anyone in practice.
Fixes: 4a49b499dfa0 ("[CRYPTO] ccm: Added CCM mode") Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers ebiggers@google.com Signed-off-by: Herbert Xu herbert@gondor.apana.org.au Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- crypto/ccm.c | 44 ++++++++++++++++++-------------------------- 1 file changed, 18 insertions(+), 26 deletions(-)
--- a/crypto/ccm.c +++ b/crypto/ccm.c @@ -458,7 +458,6 @@ static void crypto_ccm_free(struct aead_
static int crypto_ccm_create_common(struct crypto_template *tmpl, struct rtattr **tb, - const char *full_name, const char *ctr_name, const char *mac_name) { @@ -486,7 +485,8 @@ static int crypto_ccm_create_common(stru
mac = __crypto_hash_alg_common(mac_alg); err = -EINVAL; - if (mac->digestsize != 16) + if (strncmp(mac->base.cra_name, "cbcmac(", 7) != 0 || + mac->digestsize != 16) goto out_put_mac;
inst = kzalloc(sizeof(*inst) + sizeof(*ictx), GFP_KERNEL); @@ -509,23 +509,27 @@ static int crypto_ccm_create_common(stru
ctr = crypto_spawn_skcipher_alg(&ictx->ctr);
- /* Not a stream cipher? */ + /* The skcipher algorithm must be CTR mode, using 16-byte blocks. */ err = -EINVAL; - if (ctr->base.cra_blocksize != 1) + if (strncmp(ctr->base.cra_name, "ctr(", 4) != 0 || + crypto_skcipher_alg_ivsize(ctr) != 16 || + ctr->base.cra_blocksize != 1) goto err_drop_ctr;
- /* We want the real thing! */ - if (crypto_skcipher_alg_ivsize(ctr) != 16) + /* ctr and cbcmac must use the same underlying block cipher. */ + if (strcmp(ctr->base.cra_name + 4, mac->base.cra_name + 7) != 0) goto err_drop_ctr;
err = -ENAMETOOLONG; + if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME, + "ccm(%s", ctr->base.cra_name + 4) >= CRYPTO_MAX_ALG_NAME) + goto err_drop_ctr; + if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME, "ccm_base(%s,%s)", ctr->base.cra_driver_name, mac->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME) goto err_drop_ctr;
- memcpy(inst->alg.base.cra_name, full_name, CRYPTO_MAX_ALG_NAME); - inst->alg.base.cra_flags = ctr->base.cra_flags & CRYPTO_ALG_ASYNC; inst->alg.base.cra_priority = (mac->base.cra_priority + ctr->base.cra_priority) / 2; @@ -567,7 +571,6 @@ static int crypto_ccm_create(struct cryp const char *cipher_name; char ctr_name[CRYPTO_MAX_ALG_NAME]; char mac_name[CRYPTO_MAX_ALG_NAME]; - char full_name[CRYPTO_MAX_ALG_NAME];
cipher_name = crypto_attr_alg_name(tb[1]); if (IS_ERR(cipher_name)) @@ -581,12 +584,7 @@ static int crypto_ccm_create(struct cryp cipher_name) >= CRYPTO_MAX_ALG_NAME) return -ENAMETOOLONG;
- if (snprintf(full_name, CRYPTO_MAX_ALG_NAME, "ccm(%s)", cipher_name) >= - CRYPTO_MAX_ALG_NAME) - return -ENAMETOOLONG; - - return crypto_ccm_create_common(tmpl, tb, full_name, ctr_name, - mac_name); + return crypto_ccm_create_common(tmpl, tb, ctr_name, mac_name); }
static struct crypto_template crypto_ccm_tmpl = { @@ -599,23 +597,17 @@ static int crypto_ccm_base_create(struct struct rtattr **tb) { const char *ctr_name; - const char *cipher_name; - char full_name[CRYPTO_MAX_ALG_NAME]; + const char *mac_name;
ctr_name = crypto_attr_alg_name(tb[1]); if (IS_ERR(ctr_name)) return PTR_ERR(ctr_name);
- cipher_name = crypto_attr_alg_name(tb[2]); - if (IS_ERR(cipher_name)) - return PTR_ERR(cipher_name); - - if (snprintf(full_name, CRYPTO_MAX_ALG_NAME, "ccm_base(%s,%s)", - ctr_name, cipher_name) >= CRYPTO_MAX_ALG_NAME) - return -ENAMETOOLONG; + mac_name = crypto_attr_alg_name(tb[2]); + if (IS_ERR(mac_name)) + return PTR_ERR(mac_name);
- return crypto_ccm_create_common(tmpl, tb, full_name, ctr_name, - cipher_name); + return crypto_ccm_create_common(tmpl, tb, ctr_name, mac_name); }
static struct crypto_template crypto_ccm_base_tmpl = {