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Implement special parameter to define Key Usage
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This allows an application finer control on what usage will be allowed
for the key.

Fixes #285

Signed-off-by: Simo Sorce <[email protected]>
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@simo5
simo5 committed Sep 7, 2023
1 parent cd2b377 commit 559dfe3
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Showing 2 changed files with 146 additions and 27 deletions.
172 changes: 145 additions & 27 deletions src/keymgmt.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -108,6 +108,7 @@ struct key_generator {
CK_KEY_TYPE type;

P11PROV_URI *uri;
char *key_usage;

CK_MECHANISM mechanism;

Expand Down Expand Up @@ -220,6 +221,14 @@ static int p11prov_common_gen_set_params(void *genctx,
}
}

p = OSSL_PARAM_locate_const(params, P11PROV_PARAM_KEY_USAGE);
if (p) {
ret = OSSL_PARAM_get_utf8_string(p, &ctx->key_usage, 0);
if (ret != RET_OSSL_OK) {
return ret;
}
}

switch (ctx->type) {
case CKK_RSA:
p = OSSL_PARAM_locate_const(params, OSSL_PKEY_PARAM_RSA_BITS);
Expand Down Expand Up @@ -334,6 +343,112 @@ static CK_RV common_gen_callback(void *cbarg)
return CKR_OK;
}

/* Common attributes that may currently be added to the template
* CKA_ID
* CKA_LABEL
*/
#define COMMON_TMPL_SIZE 2

const CK_BBOOL val_true = CK_TRUE;
const CK_BBOOL val_false = CK_FALSE;
#define DISCARD_CONST(x) (void *)(x)

static void set_bool_val(CK_ATTRIBUTE *attr, bool val)
{
if (val) {
attr->pValue = DISCARD_CONST(&val_true);
} else {
attr->pValue = DISCARD_CONST(&val_false);
}
}

static void common_key_usage_set_attrs(CK_ATTRIBUTE *template, int tsize,
bool enc, bool sig, bool der, bool wrap)
{
for (int i = 0; i < tsize; i++) {
switch (template[i].type) {
case CKA_ENCRYPT:
case CKA_DECRYPT:
set_bool_val(&template[i], enc);
break;
case CKA_VERIFY:
case CKA_VERIFY_RECOVER:
case CKA_SIGN:
case CKA_SIGN_RECOVER:
set_bool_val(&template[i], sig);
break;
case CKA_DERIVE:
set_bool_val(&template[i], der);
break;
case CKA_WRAP:
case CKA_UNWRAP:
set_bool_val(&template[i], wrap);
break;
default:
break;
}
}
}

/*
* Takes a Key Usage string, which must be a space separated list of tokens.
* The tokens are the Key usage flag names as defined in ISO/IEC 9594-8 (X.509)
* Only the following tokens are recognized:
* - dataEncipherment
* - digitalSignature
* - keyAgreement
* - keyEncipherment
* uses: Table 25 from pkcs#11 3.1 spec for mappings for public keys
* and an analogous mapping for private keys
*/
static CK_RV common_key_usage_to_tmpl(struct key_generator *ctx,
CK_ATTRIBUTE *pubtmpl,
CK_ATTRIBUTE *privtmpl, int pubtsize,
int privtsize)
{
const char *str = NULL;
size_t len = 0;
bool enc = false;
bool sig = false;
bool der = false;
bool wrap = false;

if (!ctx->key_usage) {
/* leave defaults as set by templates */
return CKR_OK;
}

str = ctx->key_usage;
len = strlen(ctx->key_usage);
while (str) {
const char *tok = str;
size_t toklen = len;
const char *p = strchr(str, ' ');
if (p) {
toklen = p - str;
len -= toklen + 1;
p += 1;
}
str = p;
if (strncmp(tok, "dataEncipherment", toklen) == 0) {
enc = true;
} else if (strncmp(tok, "digitalSignature", toklen) == 0) {
sig = true;
} else if (strncmp(tok, "keyAgreement", toklen) == 0) {
der = true;
} else if (strncmp(tok, "keyEncipherment", toklen) == 0) {
wrap = true;
} else {
return CKR_ARGUMENTS_BAD;
}
}

common_key_usage_set_attrs(pubtmpl, pubtsize, enc, sig, der, wrap);
common_key_usage_set_attrs(privtmpl, privtsize, enc, sig, der, wrap);

return CKR_OK;
}

static void *p11prov_common_gen(struct key_generator *ctx,
CK_ATTRIBUTE *pubkey_template,
CK_ATTRIBUTE *privkey_template, int pubtsize,
Expand All @@ -351,6 +466,13 @@ static void *p11prov_common_gen(struct key_generator *ctx,
CK_ATTRIBUTE label = { 0 };
CK_RV ret;

ret = common_key_usage_to_tmpl(ctx, pubkey_template, privkey_template,
pubtsize, privtsize);
if (ret != CKR_OK) {
P11PROV_raise(ctx->provctx, ret, "Failed to map Key Usage");
return NULL;
}

if (ctx->uri) {
cka_id = p11prov_uri_get_id(ctx->uri);
label = p11prov_uri_get_label(ctx->uri);
Expand Down Expand Up @@ -483,29 +605,27 @@ static void *p11prov_rsa_gen_init(void *provctx, int selection,
static void *p11prov_rsa_gen(void *genctx, OSSL_CALLBACK *cb_fn, void *cb_arg)
{
struct key_generator *ctx = (struct key_generator *)genctx;
CK_BBOOL val_true = CK_TRUE;
/* CK_BBOOL val_false = CK_FALSE; */

/* always leave space for CKA_ID and CKA_LABEL */
#define RSA_PUBKEY_TMPL_SIZE 6
CK_ATTRIBUTE pubkey_template[RSA_PUBKEY_TMPL_SIZE + 2] = {
{ CKA_ENCRYPT, &val_true, sizeof(val_true) },
{ CKA_VERIFY, &val_true, sizeof(val_true) },
{ CKA_WRAP, &val_true, sizeof(val_true) },
{ CKA_TOKEN, &val_true, sizeof(CK_BBOOL) },
CK_ATTRIBUTE pubkey_template[RSA_PUBKEY_TMPL_SIZE + COMMON_TMPL_SIZE] = {
{ CKA_ENCRYPT, DISCARD_CONST(&val_true), sizeof(CK_BBOOL) },
{ CKA_VERIFY, DISCARD_CONST(&val_true), sizeof(CK_BBOOL) },
{ CKA_WRAP, DISCARD_CONST(&val_true), sizeof(CK_BBOOL) },
{ CKA_TOKEN, DISCARD_CONST(&val_true), sizeof(CK_BBOOL) },
{ CKA_MODULUS_BITS, &ctx->data.rsa.modulus_bits,
sizeof(ctx->data.rsa.modulus_bits) },
{ CKA_PUBLIC_EXPONENT, &ctx->data.rsa.exponent,
ctx->data.rsa.exponent_size },
};
#define RSA_PRIVKEY_TMPL_SIZE 6
CK_ATTRIBUTE privkey_template[RSA_PRIVKEY_TMPL_SIZE + 2] = {
{ CKA_TOKEN, &val_true, sizeof(CK_BBOOL) },
{ CKA_PRIVATE, &val_true, sizeof(CK_BBOOL) },
{ CKA_SENSITIVE, &val_true, sizeof(CK_BBOOL) },
{ CKA_DECRYPT, &val_true, sizeof(CK_BBOOL) },
{ CKA_SIGN, &val_true, sizeof(CK_BBOOL) },
{ CKA_UNWRAP, &val_true, sizeof(CK_BBOOL) },
CK_ATTRIBUTE privkey_template[RSA_PRIVKEY_TMPL_SIZE + COMMON_TMPL_SIZE] = {
{ CKA_TOKEN, DISCARD_CONST(&val_true), sizeof(CK_BBOOL) },
{ CKA_PRIVATE, DISCARD_CONST(&val_true), sizeof(CK_BBOOL) },
{ CKA_SENSITIVE, DISCARD_CONST(&val_true), sizeof(CK_BBOOL) },
{ CKA_DECRYPT, DISCARD_CONST(&val_true), sizeof(CK_BBOOL) },
{ CKA_SIGN, DISCARD_CONST(&val_true), sizeof(CK_BBOOL) },
{ CKA_UNWRAP, DISCARD_CONST(&val_true), sizeof(CK_BBOOL) },
/* TODO?
* CKA_SUBJECT
* CKA_COPYABLE = true ?
Expand Down Expand Up @@ -1019,26 +1139,24 @@ static void *p11prov_ec_gen_init(void *provctx, int selection,
static void *p11prov_ec_gen(void *genctx, OSSL_CALLBACK *cb_fn, void *cb_arg)
{
struct key_generator *ctx = (struct key_generator *)genctx;
CK_BBOOL val_true = CK_TRUE;
/* CK_BBOOL val_false = CK_FALSE; */

/* always leave space for CKA_ID and CKA_LABEL */
#define EC_PUBKEY_TMPL_SIZE 5
CK_ATTRIBUTE pubkey_template[EC_PUBKEY_TMPL_SIZE + 2] = {
{ CKA_TOKEN, &val_true, sizeof(CK_BBOOL) },
{ CKA_DERIVE, &val_true, sizeof(val_true) },
{ CKA_VERIFY, &val_true, sizeof(val_true) },
{ CKA_WRAP, &val_true, sizeof(val_true) },
CK_ATTRIBUTE pubkey_template[EC_PUBKEY_TMPL_SIZE + COMMON_TMPL_SIZE] = {
{ CKA_TOKEN, DISCARD_CONST(&val_true), sizeof(CK_BBOOL) },
{ CKA_DERIVE, DISCARD_CONST(&val_true), sizeof(CK_BBOOL) },
{ CKA_VERIFY, DISCARD_CONST(&val_true), sizeof(CK_BBOOL) },
{ CKA_WRAP, DISCARD_CONST(&val_true), sizeof(CK_BBOOL) },
{ CKA_EC_PARAMS, (CK_BYTE *)ctx->data.ec.ec_params,
ctx->data.ec.ec_params_size },
};
#define EC_PRIVKEY_TMPL_SIZE 6
CK_ATTRIBUTE privkey_template[EC_PRIVKEY_TMPL_SIZE + 2] = {
{ CKA_TOKEN, &val_true, sizeof(CK_BBOOL) },
{ CKA_PRIVATE, &val_true, sizeof(CK_BBOOL) },
{ CKA_SENSITIVE, &val_true, sizeof(CK_BBOOL) },
{ CKA_SIGN, &val_true, sizeof(CK_BBOOL) },
{ CKA_UNWRAP, &val_true, sizeof(CK_BBOOL) },
CK_ATTRIBUTE privkey_template[EC_PRIVKEY_TMPL_SIZE + COMMON_TMPL_SIZE] = {
{ CKA_TOKEN, DISCARD_CONST(&val_true), sizeof(CK_BBOOL) },
{ CKA_PRIVATE, DISCARD_CONST(&val_true), sizeof(CK_BBOOL) },
{ CKA_SENSITIVE, DISCARD_CONST(&val_true), sizeof(CK_BBOOL) },
{ CKA_SIGN, DISCARD_CONST(&val_true), sizeof(CK_BBOOL) },
{ CKA_UNWRAP, DISCARD_CONST(&val_true), sizeof(CK_BBOOL) },
/* TODO?
* CKA_SUBJECT
* CKA_COPYABLE = true ?
Expand Down
1 change: 1 addition & 0 deletions src/provider.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -58,6 +58,7 @@
#define P11PROV_DESCS_RAND "PKCS11 Random Generator"

#define P11PROV_PARAM_URI "pkcs11_uri"
#define P11PROV_PARAM_KEY_USAGE "pkcs11_key_usage"
#define P11PROV_PARAM_SLOT_ID "pkcs11_slot_id"

typedef struct p11prov_ctx P11PROV_CTX;
Expand Down

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