[PATCH v3 03/15] crypto: dh - remove struct dh's ->q member

Nicolai Stange
2022-02-02T10:42:15Z

The only current user of the DH KPP algorithm, the
keyctl(KEYCTL_DH_COMPUTE) syscall, doesn't set the domain parameter ->q
in struct dh. Remove it and any associated (de)serialization code in
crypto_dh_encode_key() and crypto_dh_decode_key. Adjust the encoded
->secret values in testmgr's DH test vectors accordingly.

Note that the dh-generic implementation would have initialized its
struct dh_ctx's ->q from the decoded struct dh's ->q, if present. If this
struct dh_ctx's ->q would ever have been non-NULL, it would have enabled a
full key validation as specified in NIST SP800-56A in dh_is_pubkey_valid().
However, as outlined above, ->q is always NULL in practice and the full key
validation code is effectively dead. A later patch will make
dh_is_pubkey_valid() to calculate Q from P on the fly, if possible, so
don't remove struct dh_ctx's ->q now, but leave it there until that has
happened.

Signed-off-by: Nicolai Stange <nstange@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
---
crypto/dh.c | 6 ------
crypto/dh_helper.c | 17 ++++-------------
crypto/testmgr.h | 16 ++++++----------
include/crypto/dh.h | 4 ----
4 files changed, 10 insertions(+), 33 deletions(-)

diff --git a/crypto/dh.c b/crypto/dh.c
index 27e62a2a8027..abc2a72c8271 100644
--- a/crypto/dh.c
+++ b/crypto/dh.c
@@ -62,12 +62,6 @@ static int dh_set_params(struct dh_ctx *ctx, struct dh *params)
if (!ctx->p)
return -EINVAL;

- if (params->q && params->q_size) {
- ctx->q = mpi_read_raw_data(params->q, params->q_size);
- if (!ctx->q)
- return -EINVAL;
- }
-
ctx->g = mpi_read_raw_data(params->g, params->g_size);
if (!ctx->g)
return -EINVAL;
diff --git a/crypto/dh_helper.c b/crypto/dh_helper.c
index 9fd5a42eea15..aabc91e4f63f 100644
--- a/crypto/dh_helper.c
+++ b/crypto/dh_helper.c
@@ -10,7 +10,7 @@
#include <crypto/dh.h>
#include <crypto/kpp.h>

-#define DH_KPP_SECRET_MIN_SIZE (sizeof(struct kpp_secret) + 4 * sizeof(int))
+#define DH_KPP_SECRET_MIN_SIZE (sizeof(struct kpp_secret) + 3 * sizeof(int))

static inline u8 *dh_pack_data(u8 *dst, u8 *end, const void *src, size_t size)
{
@@ -28,7 +28,7 @@ static inline const u8 *dh_unpack_data(void *dst, const void *src, size_t size)

static inline unsigned int dh_data_size(const struct dh *p)
{
- return p->key_size + p->p_size + p->q_size + p->g_size;
+ return p->key_size + p->p_size + p->g_size;
}

unsigned int crypto_dh_key_len(const struct dh *p)
@@ -53,11 +53,9 @@ int crypto_dh_encode_key(char *buf, unsigned int len, const struct dh *params)
ptr = dh_pack_data(ptr, end, &params->key_size,
sizeof(params->key_size));
ptr = dh_pack_data(ptr, end, &params->p_size, sizeof(params->p_size));
- ptr = dh_pack_data(ptr, end, &params->q_size, sizeof(params->q_size));
ptr = dh_pack_data(ptr, end, &params->g_size, sizeof(params->g_size));
ptr = dh_pack_data(ptr, end, params->key, params->key_size);
ptr = dh_pack_data(ptr, end, params->p, params->p_size);
- ptr = dh_pack_data(ptr, end, params->q, params->q_size);
ptr = dh_pack_data(ptr, end, params->g, params->g_size);
if (ptr != end)
return -EINVAL;
@@ -79,7 +77,6 @@ int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params)

ptr = dh_unpack_data(&params->key_size, ptr, sizeof(params->key_size));
ptr = dh_unpack_data(&params->p_size, ptr, sizeof(params->p_size));
- ptr = dh_unpack_data(&params->q_size, ptr, sizeof(params->q_size));
ptr = dh_unpack_data(&params->g_size, ptr, sizeof(params->g_size));
if (secret.len != crypto_dh_key_len(params))
return -EINVAL;
@@ -89,7 +86,7 @@ int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params)
* some drivers assume otherwise.
*/
if (params->key_size > params->p_size ||
- params->g_size > params->p_size || params->q_size > params->p_size)
+ params->g_size > params->p_size)
return -EINVAL;

/* Don't allocate memory. Set pointers to data within
@@ -97,9 +94,7 @@ int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params)
*/
params->key = (void *)ptr;
params->p = (void *)(ptr + params->key_size);
- params->q = (void *)(ptr + params->key_size + params->p_size);
- params->g = (void *)(ptr + params->key_size + params->p_size +
- params->q_size);
+ params->g = (void *)(ptr + params->key_size + params->p_size);

/*
* Don't permit 'p' to be 0. It's not a prime number, and it's subject
@@ -109,10 +104,6 @@ int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params)
if (memchr_inv(params->p, 0, params->p_size) == NULL)
return -EINVAL;

- /* It is permissible to not provide Q. */
- if (params->q_size == 0)
- params->q = NULL;
-
return 0;
}
EXPORT_SYMBOL_GPL(crypto_dh_decode_key);
diff --git a/crypto/testmgr.h b/crypto/testmgr.h
index a253d66ba1c1..6029df67486d 100644
--- a/crypto/testmgr.h
+++ b/crypto/testmgr.h
@@ -1244,17 +1244,15 @@ static const struct kpp_testvec dh_tv_template[] = {
.secret =
#ifdef __LITTLE_ENDIAN
"\x01\x00" /* type */
- "\x15\x02" /* len */
+ "\x11\x02" /* len */
"\x00\x01\x00\x00" /* key_size */
"\x00\x01\x00\x00" /* p_size */
- "\x00\x00\x00\x00" /* q_size */
"\x01\x00\x00\x00" /* g_size */
#else
"\x00\x01" /* type */
- "\x02\x15" /* len */
+ "\x02\x11" /* len */
"\x00\x00\x01\x00" /* key_size */
"\x00\x00\x01\x00" /* p_size */
- "\x00\x00\x00\x00" /* q_size */
"\x00\x00\x00\x01" /* g_size */
#endif
/* xa */
@@ -1344,7 +1342,7 @@ static const struct kpp_testvec dh_tv_template[] = {
"\xd3\x34\x49\xad\x64\xa6\xb1\xc0\x59\x28\x75\x60\xa7\x8a\xb0\x11"
"\x56\x89\x42\x74\x11\xf5\xf6\x5e\x6f\x16\x54\x6a\xb1\x76\x4d\x50"
"\x8a\x68\xc1\x5b\x82\xb9\x0d\x00\x32\x50\xed\x88\x87\x48\x92\x17",
- .secret_size = 533,
+ .secret_size = 529,
.b_public_size = 256,
.expected_a_public_size = 256,
.expected_ss_size = 256,
@@ -1353,17 +1351,15 @@ static const struct kpp_testvec dh_tv_template[] = {
.secret =
#ifdef __LITTLE_ENDIAN
"\x01\x00" /* type */
- "\x15\x02" /* len */
+ "\x11\x02" /* len */
"\x00\x01\x00\x00" /* key_size */
"\x00\x01\x00\x00" /* p_size */
- "\x00\x00\x00\x00" /* q_size */
"\x01\x00\x00\x00" /* g_size */
#else
"\x00\x01" /* type */
- "\x02\x15" /* len */
+ "\x02\x11" /* len */
"\x00\x00\x01\x00" /* key_size */
"\x00\x00\x01\x00" /* p_size */
- "\x00\x00\x00\x00" /* q_size */
"\x00\x00\x00\x01" /* g_size */
#endif
/* xa */
@@ -1453,7 +1449,7 @@ static const struct kpp_testvec dh_tv_template[] = {
"\x5e\x5a\x64\xbd\xf6\x85\x04\xe8\x28\x6a\xac\xef\xce\x19\x8e\x9a"
"\xfe\x75\xc0\x27\x69\xe3\xb3\x7b\x21\xa7\xb1\x16\xa4\x85\x23\xee"
"\xb0\x1b\x04\x6e\xbd\xab\x16\xde\xfd\x86\x6b\xa9\x95\xd7\x0b\xfd",
- .secret_size = 533,
+ .secret_size = 529,
.b_public_size = 256,
.expected_a_public_size = 256,
.expected_ss_size = 256,
diff --git a/include/crypto/dh.h b/include/crypto/dh.h
index d71e9858ab86..2585f0e6bb69 100644
--- a/include/crypto/dh.h
+++ b/include/crypto/dh.h
@@ -24,21 +24,17 @@
*
* @key: Private DH key
* @p: Diffie-Hellman parameter P
- * @q: Diffie-Hellman parameter Q
* @g: Diffie-Hellman generator G
* @key_size: Size of the private DH key
* @p_size: Size of DH parameter P
- * @q_size: Size of DH parameter Q
* @g_size: Size of DH generator G
*/
struct dh {
void *key;
void *p;
- void *q;
void *g;
unsigned int key_size;
unsigned int p_size;
- unsigned int q_size;
unsigned int g_size;
};

--
2.26.2