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|
/*
*
* Copyright 2015, Google Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimser.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimser
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#include "src/core/security/jwt_verifier.h"
#include <string.h>
#include "src/core/httpcli/httpcli.h"
#include "src/core/security/base64.h"
#include <grpc/support/alloc.h>
#include <grpc/support/log.h>
#include <grpc/support/string_util.h>
#include <grpc/support/sync.h>
#include <openssl/pem.h>
/* --- Utils. --- */
const char *grpc_jwt_verifier_status_to_string(
grpc_jwt_verifier_status status) {
switch (status) {
case GRPC_JWT_VERIFIER_OK:
return "OK";
case GRPC_JWT_VERIFIER_BAD_SIGNATURE:
return "BAD_SIGNATURE";
case GRPC_JWT_VERIFIER_BAD_FORMAT:
return "BAD_FORMAT";
case GRPC_JWT_VERIFIER_BAD_AUDIENCE:
return "BAD_AUDIENCE";
case GRPC_JWT_VERIFIER_KEY_RETRIEVAL_ERROR:
return "KEY_RETRIEVAL_ERROR";
case GRPC_JWT_VERIFIER_TIME_CONSTRAINT_FAILURE:
return "TIME_CONSTRAINT_FAILURE";
case GRPC_JWT_VERIFIER_GENERIC_ERROR:
return "GENERIC_ERROR";
default:
return "UNKNOWN";
}
}
static const EVP_MD *evp_md_from_alg(const char *alg) {
if (strcmp(alg, "RS256") == 0) {
return EVP_sha256();
} else if (strcmp(alg, "RS384") == 0) {
return EVP_sha384();
} else if (strcmp(alg, "RS512") == 0) {
return EVP_sha512();
} else {
return NULL;
}
}
static grpc_json *parse_json_part_from_jwt(const char *str, size_t len,
gpr_slice *buffer) {
grpc_json *json;
*buffer = grpc_base64_decode_with_len(str, len, 1);
if (GPR_SLICE_IS_EMPTY(*buffer)) {
gpr_log(GPR_ERROR, "Invalid base64.");
return NULL;
}
json = grpc_json_parse_string_with_len((char *)GPR_SLICE_START_PTR(*buffer),
GPR_SLICE_LENGTH(*buffer));
if (json == NULL) {
gpr_slice_unref(*buffer);
gpr_log(GPR_ERROR, "JSON parsing error.");
}
return json;
}
static const char *validate_string_field(const grpc_json *json,
const char *key) {
if (json->type != GRPC_JSON_STRING) {
gpr_log(GPR_ERROR, "Invalid %s field [%s]", key, json->value);
return NULL;
}
return json->value;
}
static gpr_timespec validate_time_field(const grpc_json *json,
const char *key) {
gpr_timespec result = gpr_time_0(GPR_CLOCK_REALTIME);
if (json->type != GRPC_JSON_NUMBER) {
gpr_log(GPR_ERROR, "Invalid %s field [%s]", key, json->value);
return result;
}
result.tv_sec = strtol(json->value, NULL, 10);
return result;
}
/* --- JOSE header. see http://tools.ietf.org/html/rfc7515#section-4 --- */
typedef struct {
const char *alg;
const char *kid;
const char *typ;
/* TODO(jboeuf): Add others as needed (jku, jwk, x5u, x5c and so on...). */
gpr_slice buffer;
} jose_header;
static void jose_header_destroy(jose_header *h) {
gpr_slice_unref(h->buffer);
gpr_free(h);
}
/* Takes ownership of json and buffer. */
static jose_header *jose_header_from_json(grpc_json *json, gpr_slice buffer) {
grpc_json *cur;
jose_header *h = gpr_malloc(sizeof(jose_header));
memset(h, 0, sizeof(jose_header));
h->buffer = buffer;
for (cur = json->child; cur != NULL; cur = cur->next) {
if (strcmp(cur->key, "alg") == 0) {
/* We only support RSA-1.5 signatures for now.
Beware of this if we add HMAC support:
https://auth0.com/blog/2015/03/31/critical-vulnerabilities-in-json-web-token-libraries/
*/
if (cur->type != GRPC_JSON_STRING || strncmp(cur->value, "RS", 2) ||
evp_md_from_alg(cur->value) == NULL) {
gpr_log(GPR_ERROR, "Invalid alg field [%s]", cur->value);
goto error;
}
h->alg = cur->value;
} else if (strcmp(cur->key, "typ") == 0) {
h->typ = validate_string_field(cur, "typ");
if (h->typ == NULL) goto error;
} else if (strcmp(cur->key, "kid") == 0) {
h->kid = validate_string_field(cur, "kid");
if (h->kid == NULL) goto error;
}
}
if (h->alg == NULL) {
gpr_log(GPR_ERROR, "Missing alg field.");
goto error;
}
grpc_json_destroy(json);
h->buffer = buffer;
return h;
error:
grpc_json_destroy(json);
jose_header_destroy(h);
return NULL;
}
/* --- JWT claims. see http://tools.ietf.org/html/rfc7519#section-4.1 */
struct grpc_jwt_claims {
/* Well known properties already parsed. */
const char *sub;
const char *iss;
const char *aud;
const char *jti;
gpr_timespec iat;
gpr_timespec exp;
gpr_timespec nbf;
grpc_json *json;
gpr_slice buffer;
};
void grpc_jwt_claims_destroy(grpc_jwt_claims *claims) {
grpc_json_destroy(claims->json);
gpr_slice_unref(claims->buffer);
gpr_free(claims);
}
const grpc_json *grpc_jwt_claims_json(const grpc_jwt_claims *claims) {
if (claims == NULL) return NULL;
return claims->json;
}
const char *grpc_jwt_claims_subject(const grpc_jwt_claims *claims) {
if (claims == NULL) return NULL;
return claims->sub;
}
const char *grpc_jwt_claims_issuer(const grpc_jwt_claims *claims) {
if (claims == NULL) return NULL;
return claims->iss;
}
const char *grpc_jwt_claims_id(const grpc_jwt_claims *claims) {
if (claims == NULL) return NULL;
return claims->jti;
}
const char *grpc_jwt_claims_audience(const grpc_jwt_claims *claims) {
if (claims == NULL) return NULL;
return claims->aud;
}
gpr_timespec grpc_jwt_claims_issued_at(const grpc_jwt_claims *claims) {
if (claims == NULL) return gpr_inf_past(GPR_CLOCK_REALTIME);
return claims->iat;
}
gpr_timespec grpc_jwt_claims_expires_at(const grpc_jwt_claims *claims) {
if (claims == NULL) return gpr_inf_future(GPR_CLOCK_REALTIME);
return claims->exp;
}
gpr_timespec grpc_jwt_claims_not_before(const grpc_jwt_claims *claims) {
if (claims == NULL) return gpr_inf_past(GPR_CLOCK_REALTIME);
return claims->nbf;
}
/* Takes ownership of json and buffer even in case of failure. */
grpc_jwt_claims *grpc_jwt_claims_from_json(grpc_json *json, gpr_slice buffer) {
grpc_json *cur;
grpc_jwt_claims *claims = gpr_malloc(sizeof(grpc_jwt_claims));
memset(claims, 0, sizeof(grpc_jwt_claims));
claims->json = json;
claims->buffer = buffer;
claims->iat = gpr_inf_past(GPR_CLOCK_REALTIME);
claims->nbf = gpr_inf_past(GPR_CLOCK_REALTIME);
claims->exp = gpr_inf_future(GPR_CLOCK_REALTIME);
/* Per the spec, all fields are optional. */
for (cur = json->child; cur != NULL; cur = cur->next) {
if (strcmp(cur->key, "sub") == 0) {
claims->sub = validate_string_field(cur, "sub");
if (claims->sub == NULL) goto error;
} else if (strcmp(cur->key, "iss") == 0) {
claims->iss = validate_string_field(cur, "iss");
if (claims->iss == NULL) goto error;
} else if (strcmp(cur->key, "aud") == 0) {
claims->aud = validate_string_field(cur, "aud");
if (claims->aud == NULL) goto error;
} else if (strcmp(cur->key, "jti") == 0) {
claims->jti = validate_string_field(cur, "jti");
if (claims->jti == NULL) goto error;
} else if (strcmp(cur->key, "iat") == 0) {
claims->iat = validate_time_field(cur, "iat");
if (gpr_time_cmp(claims->iat, gpr_time_0(GPR_CLOCK_REALTIME)) == 0)
goto error;
} else if (strcmp(cur->key, "exp") == 0) {
claims->exp = validate_time_field(cur, "exp");
if (gpr_time_cmp(claims->exp, gpr_time_0(GPR_CLOCK_REALTIME)) == 0)
goto error;
} else if (strcmp(cur->key, "nbf") == 0) {
claims->nbf = validate_time_field(cur, "nbf");
if (gpr_time_cmp(claims->nbf, gpr_time_0(GPR_CLOCK_REALTIME)) == 0)
goto error;
}
}
return claims;
error:
grpc_jwt_claims_destroy(claims);
return NULL;
}
grpc_jwt_verifier_status grpc_jwt_claims_check(const grpc_jwt_claims *claims,
const char *audience) {
gpr_timespec skewed_now;
int audience_ok;
GPR_ASSERT(claims != NULL);
skewed_now =
gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), grpc_jwt_verifier_clock_skew);
if (gpr_time_cmp(skewed_now, claims->nbf) < 0) {
gpr_log(GPR_ERROR, "JWT is not valid yet.");
return GRPC_JWT_VERIFIER_TIME_CONSTRAINT_FAILURE;
}
skewed_now =
gpr_time_sub(gpr_now(GPR_CLOCK_REALTIME), grpc_jwt_verifier_clock_skew);
if (gpr_time_cmp(skewed_now, claims->exp) > 0) {
gpr_log(GPR_ERROR, "JWT is expired.");
return GRPC_JWT_VERIFIER_TIME_CONSTRAINT_FAILURE;
}
if (audience == NULL) {
audience_ok = claims->aud == NULL;
} else {
audience_ok = claims->aud != NULL && strcmp(audience, claims->aud) == 0;
}
if (!audience_ok) {
gpr_log(GPR_ERROR, "Audience mismatch: expected %s and found %s.",
audience == NULL ? "NULL" : audience,
claims->aud == NULL ? "NULL" : claims->aud);
return GRPC_JWT_VERIFIER_BAD_AUDIENCE;
}
return GRPC_JWT_VERIFIER_OK;
}
/* --- verifier_cb_ctx object. --- */
typedef struct {
grpc_jwt_verifier *verifier;
grpc_pollset *pollset;
jose_header *header;
grpc_jwt_claims *claims;
char *audience;
gpr_slice signature;
gpr_slice signed_data;
void *user_data;
grpc_jwt_verification_done_cb user_cb;
} verifier_cb_ctx;
/* Takes ownership of the header, claims and signature. */
static verifier_cb_ctx *verifier_cb_ctx_create(
grpc_jwt_verifier *verifier, grpc_pollset *pollset, jose_header *header,
grpc_jwt_claims *claims, const char *audience, gpr_slice signature,
const char *signed_jwt, size_t signed_jwt_len, void *user_data,
grpc_jwt_verification_done_cb cb) {
verifier_cb_ctx *ctx = gpr_malloc(sizeof(verifier_cb_ctx));
memset(ctx, 0, sizeof(verifier_cb_ctx));
ctx->verifier = verifier;
ctx->pollset = pollset;
ctx->header = header;
ctx->audience = gpr_strdup(audience);
ctx->claims = claims;
ctx->signature = signature;
ctx->signed_data = gpr_slice_from_copied_buffer(signed_jwt, signed_jwt_len);
ctx->user_data = user_data;
ctx->user_cb = cb;
return ctx;
}
void verifier_cb_ctx_destroy(verifier_cb_ctx *ctx) {
if (ctx->audience != NULL) gpr_free(ctx->audience);
if (ctx->claims != NULL) grpc_jwt_claims_destroy(ctx->claims);
gpr_slice_unref(ctx->signature);
gpr_slice_unref(ctx->signed_data);
jose_header_destroy(ctx->header);
/* TODO: see what to do with claims... */
gpr_free(ctx);
}
/* --- grpc_jwt_verifier object. --- */
/* Clock skew defaults to one minute. */
gpr_timespec grpc_jwt_verifier_clock_skew = {60, 0, GPR_TIMESPAN};
/* Max delay defaults to one minute. */
gpr_timespec grpc_jwt_verifier_max_delay = {60, 0, GPR_TIMESPAN};
typedef struct {
char *email_domain;
char *key_url_prefix;
} email_key_mapping;
struct grpc_jwt_verifier {
email_key_mapping *mappings;
size_t num_mappings; /* Should be very few, linear search ok. */
size_t allocated_mappings;
grpc_httpcli_context http_ctx;
};
static grpc_json *json_from_http(const grpc_httpcli_response *response) {
grpc_json *json = NULL;
if (response == NULL) {
gpr_log(GPR_ERROR, "HTTP response is NULL.");
return NULL;
}
if (response->status != 200) {
gpr_log(GPR_ERROR, "Call to http server failed with error %d.",
response->status);
return NULL;
}
json = grpc_json_parse_string_with_len(response->body, response->body_length);
if (json == NULL) {
gpr_log(GPR_ERROR, "Invalid JSON found in response.");
}
return json;
}
static const grpc_json *find_property_by_name(const grpc_json *json,
const char *name) {
const grpc_json *cur;
for (cur = json->child; cur != NULL; cur = cur->next) {
if (strcmp(cur->key, name) == 0) return cur;
}
return NULL;
}
static EVP_PKEY *extract_pkey_from_x509(const char *x509_str) {
X509 *x509 = NULL;
EVP_PKEY *result = NULL;
BIO *bio = BIO_new(BIO_s_mem());
BIO_write(bio, x509_str, strlen(x509_str));
x509 = PEM_read_bio_X509(bio, NULL, NULL, NULL);
if (x509 == NULL) {
gpr_log(GPR_ERROR, "Unable to parse x509 cert.");
goto end;
}
result = X509_get_pubkey(x509);
if (result == NULL) {
gpr_log(GPR_ERROR, "Cannot find public key in X509 cert.");
}
end:
BIO_free(bio);
if (x509 != NULL) X509_free(x509);
return result;
}
static BIGNUM *bignum_from_base64(const char *b64) {
BIGNUM *result = NULL;
gpr_slice bin;
if (b64 == NULL) return NULL;
bin = grpc_base64_decode(b64, 1);
if (GPR_SLICE_IS_EMPTY(bin)) {
gpr_log(GPR_ERROR, "Invalid base64 for big num.");
return NULL;
}
result = BN_bin2bn(GPR_SLICE_START_PTR(bin), GPR_SLICE_LENGTH(bin), NULL);
gpr_slice_unref(bin);
return result;
}
static EVP_PKEY *pkey_from_jwk(const grpc_json *json, const char *kty) {
const grpc_json *key_prop;
RSA *rsa = NULL;
EVP_PKEY *result = NULL;
GPR_ASSERT(kty != NULL && json != NULL);
if (strcmp(kty, "RSA") != 0) {
gpr_log(GPR_ERROR, "Unsupported key type %s.", kty);
goto end;
}
rsa = RSA_new();
if (rsa == NULL) {
gpr_log(GPR_ERROR, "Could not create rsa key.");
goto end;
}
for (key_prop = json->child; key_prop != NULL; key_prop = key_prop->next) {
if (strcmp(key_prop->key, "n") == 0) {
rsa->n = bignum_from_base64(validate_string_field(key_prop, "n"));
if (rsa->n == NULL) goto end;
} else if (strcmp(key_prop->key, "e") == 0) {
rsa->e = bignum_from_base64(validate_string_field(key_prop, "e"));
if (rsa->e == NULL) goto end;
}
}
if (rsa->e == NULL || rsa->n == NULL) {
gpr_log(GPR_ERROR, "Missing RSA public key field.");
goto end;
}
result = EVP_PKEY_new();
EVP_PKEY_set1_RSA(result, rsa); /* uprefs rsa. */
end:
if (rsa != NULL) RSA_free(rsa);
return result;
}
static EVP_PKEY *find_verification_key(const grpc_json *json,
const char *header_alg,
const char *header_kid) {
const grpc_json *jkey;
const grpc_json *jwk_keys;
/* Try to parse the json as a JWK set:
https://tools.ietf.org/html/rfc7517#section-5. */
jwk_keys = find_property_by_name(json, "keys");
if (jwk_keys == NULL) {
/* Use the google proprietary format which is:
{ <kid1>: <x5091>, <kid2>: <x5092>, ... } */
const grpc_json *cur = find_property_by_name(json, header_kid);
if (cur == NULL) return NULL;
return extract_pkey_from_x509(cur->value);
}
if (jwk_keys->type != GRPC_JSON_ARRAY) {
gpr_log(GPR_ERROR,
"Unexpected value type of keys property in jwks key set.");
return NULL;
}
/* Key format is specified in:
https://tools.ietf.org/html/rfc7518#section-6. */
for (jkey = jwk_keys->child; jkey != NULL; jkey = jkey->next) {
grpc_json *key_prop;
const char *alg = NULL;
const char *kid = NULL;
const char *kty = NULL;
if (jkey->type != GRPC_JSON_OBJECT) continue;
for (key_prop = jkey->child; key_prop != NULL; key_prop = key_prop->next) {
if (strcmp(key_prop->key, "alg") == 0 &&
key_prop->type == GRPC_JSON_STRING) {
alg = key_prop->value;
} else if (strcmp(key_prop->key, "kid") == 0 &&
key_prop->type == GRPC_JSON_STRING) {
kid = key_prop->value;
} else if (strcmp(key_prop->key, "kty") == 0 &&
key_prop->type == GRPC_JSON_STRING) {
kty = key_prop->value;
}
}
if (alg != NULL && kid != NULL && kty != NULL &&
strcmp(kid, header_kid) == 0 && strcmp(alg, header_alg) == 0) {
return pkey_from_jwk(jkey, kty);
}
}
gpr_log(GPR_ERROR,
"Could not find matching key in key set for kid=%s and alg=%s",
header_kid, header_alg);
return NULL;
}
static int verify_jwt_signature(EVP_PKEY *key, const char *alg,
gpr_slice signature, gpr_slice signed_data) {
EVP_MD_CTX *md_ctx = EVP_MD_CTX_create();
const EVP_MD *md = evp_md_from_alg(alg);
int result = 0;
GPR_ASSERT(md != NULL); /* Checked before. */
if (md_ctx == NULL) {
gpr_log(GPR_ERROR, "Could not create EVP_MD_CTX.");
goto end;
}
if (EVP_DigestVerifyInit(md_ctx, NULL, md, NULL, key) != 1) {
gpr_log(GPR_ERROR, "EVP_DigestVerifyInit failed.");
goto end;
}
if (EVP_DigestVerifyUpdate(md_ctx, GPR_SLICE_START_PTR(signed_data),
GPR_SLICE_LENGTH(signed_data)) != 1) {
gpr_log(GPR_ERROR, "EVP_DigestVerifyUpdate failed.");
goto end;
}
if (EVP_DigestVerifyFinal(md_ctx, GPR_SLICE_START_PTR(signature),
GPR_SLICE_LENGTH(signature)) != 1) {
gpr_log(GPR_ERROR, "JWT signature verification failed.");
goto end;
}
result = 1;
end:
if (md_ctx != NULL) EVP_MD_CTX_destroy(md_ctx);
return result;
}
static void on_keys_retrieved(void *user_data,
const grpc_httpcli_response *response) {
grpc_json *json = json_from_http(response);
verifier_cb_ctx *ctx = (verifier_cb_ctx *)user_data;
EVP_PKEY *verification_key = NULL;
grpc_jwt_verifier_status status = GRPC_JWT_VERIFIER_GENERIC_ERROR;
grpc_jwt_claims *claims = NULL;
if (json == NULL) {
status = GRPC_JWT_VERIFIER_KEY_RETRIEVAL_ERROR;
goto end;
}
verification_key =
find_verification_key(json, ctx->header->alg, ctx->header->kid);
if (verification_key == NULL) {
gpr_log(GPR_ERROR, "Could not find verification key with kid %s.",
ctx->header->kid);
status = GRPC_JWT_VERIFIER_KEY_RETRIEVAL_ERROR;
goto end;
}
if (!verify_jwt_signature(verification_key, ctx->header->alg, ctx->signature,
ctx->signed_data)) {
status = GRPC_JWT_VERIFIER_BAD_SIGNATURE;
goto end;
}
status = grpc_jwt_claims_check(ctx->claims, ctx->audience);
if (status == GRPC_JWT_VERIFIER_OK) {
/* Pass ownership. */
claims = ctx->claims;
ctx->claims = NULL;
}
end:
if (json != NULL) grpc_json_destroy(json);
if (verification_key != NULL) EVP_PKEY_free(verification_key);
ctx->user_cb(ctx->user_data, status, claims);
verifier_cb_ctx_destroy(ctx);
}
static void on_openid_config_retrieved(void *user_data,
const grpc_httpcli_response *response) {
const grpc_json *cur;
grpc_json *json = json_from_http(response);
verifier_cb_ctx *ctx = (verifier_cb_ctx *)user_data;
grpc_httpcli_request req;
const char *jwks_uri;
/* TODO(jboeuf): Cache the jwks_uri in order to avoid this hop next time.*/
if (json == NULL) goto error;
cur = find_property_by_name(json, "jwks_uri");
if (cur == NULL) {
gpr_log(GPR_ERROR, "Could not find jwks_uri in openid config.");
goto error;
}
jwks_uri = validate_string_field(cur, "jwks_uri");
if (jwks_uri == NULL) goto error;
if (strstr(jwks_uri, "https://") != jwks_uri) {
gpr_log(GPR_ERROR, "Invalid non https jwks_uri: %s.", jwks_uri);
goto error;
}
jwks_uri += 8;
req.use_ssl = 1;
req.host = gpr_strdup(jwks_uri);
req.path = strchr(jwks_uri, '/');
if (req.path == NULL) {
req.path = "";
} else {
*(req.host + (req.path - jwks_uri)) = '\0';
}
grpc_httpcli_get(
&ctx->verifier->http_ctx, ctx->pollset, &req,
gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), grpc_jwt_verifier_max_delay),
on_keys_retrieved, ctx);
grpc_json_destroy(json);
gpr_free(req.host);
return;
error:
if (json != NULL) grpc_json_destroy(json);
ctx->user_cb(ctx->user_data, GRPC_JWT_VERIFIER_KEY_RETRIEVAL_ERROR, NULL);
verifier_cb_ctx_destroy(ctx);
}
static email_key_mapping *verifier_get_mapping(grpc_jwt_verifier *v,
const char *email_domain) {
size_t i;
if (v->mappings == NULL) return NULL;
for (i = 0; i < v->num_mappings; i++) {
if (strcmp(email_domain, v->mappings[i].email_domain) == 0) {
return &v->mappings[i];
}
}
return NULL;
}
static void verifier_put_mapping(grpc_jwt_verifier *v, const char *email_domain,
const char *key_url_prefix) {
email_key_mapping *mapping = verifier_get_mapping(v, email_domain);
GPR_ASSERT(v->num_mappings < v->allocated_mappings);
if (mapping != NULL) {
gpr_free(mapping->key_url_prefix);
mapping->key_url_prefix = gpr_strdup(key_url_prefix);
return;
}
v->mappings[v->num_mappings].email_domain = gpr_strdup(email_domain);
v->mappings[v->num_mappings].key_url_prefix = gpr_strdup(key_url_prefix);
v->num_mappings++;
GPR_ASSERT(v->num_mappings <= v->allocated_mappings);
}
/* Takes ownership of ctx. */
static void retrieve_key_and_verify(verifier_cb_ctx *ctx) {
const char *at_sign;
grpc_httpcli_response_cb http_cb;
char *path_prefix = NULL;
const char *iss;
grpc_httpcli_request req;
memset(&req, 0, sizeof(grpc_httpcli_request));
req.use_ssl = 1;
GPR_ASSERT(ctx != NULL && ctx->header != NULL && ctx->claims != NULL);
iss = ctx->claims->iss;
if (ctx->header->kid == NULL) {
gpr_log(GPR_ERROR, "Missing kid in jose header.");
goto error;
}
if (iss == NULL) {
gpr_log(GPR_ERROR, "Missing iss in claims.");
goto error;
}
/* This code relies on:
https://openid.net/specs/openid-connect-discovery-1_0.html
Nobody seems to implement the account/email/webfinger part 2. of the spec
so we will rely instead on email/url mappings if we detect such an issuer.
Part 4, on the other hand is implemented by both google and salesforce. */
/* Very non-sophisticated way to detect an email address. Should be good
enough for now... */
at_sign = strchr(iss, '@');
if (at_sign != NULL) {
email_key_mapping *mapping;
const char *email_domain = at_sign + 1;
GPR_ASSERT(ctx->verifier != NULL);
mapping = verifier_get_mapping(ctx->verifier, email_domain);
if (mapping == NULL) {
gpr_log(GPR_ERROR, "Missing mapping for issuer email.");
goto error;
}
req.host = gpr_strdup(mapping->key_url_prefix);
path_prefix = strchr(req.host, '/');
if (path_prefix == NULL) {
gpr_asprintf(&req.path, "/%s", iss);
} else {
*(path_prefix++) = '\0';
gpr_asprintf(&req.path, "/%s/%s", path_prefix, iss);
}
http_cb = on_keys_retrieved;
} else {
req.host = gpr_strdup(strstr(iss, "https://") == iss ? iss + 8 : iss);
path_prefix = strchr(req.host, '/');
if (path_prefix == NULL) {
req.path = gpr_strdup(GRPC_OPENID_CONFIG_URL_SUFFIX);
} else {
*(path_prefix++) = 0;
gpr_asprintf(&req.path, "/%s%s", path_prefix,
GRPC_OPENID_CONFIG_URL_SUFFIX);
}
http_cb = on_openid_config_retrieved;
}
grpc_httpcli_get(
&ctx->verifier->http_ctx, ctx->pollset, &req,
gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), grpc_jwt_verifier_max_delay),
http_cb, ctx);
gpr_free(req.host);
gpr_free(req.path);
return;
error:
ctx->user_cb(ctx->user_data, GRPC_JWT_VERIFIER_KEY_RETRIEVAL_ERROR, NULL);
verifier_cb_ctx_destroy(ctx);
}
void grpc_jwt_verifier_verify(grpc_jwt_verifier *verifier,
grpc_pollset *pollset, const char *jwt,
const char *audience,
grpc_jwt_verification_done_cb cb,
void *user_data) {
const char *dot = NULL;
grpc_json *json;
jose_header *header = NULL;
grpc_jwt_claims *claims = NULL;
gpr_slice header_buffer;
gpr_slice claims_buffer;
gpr_slice signature;
size_t signed_jwt_len;
const char *cur = jwt;
GPR_ASSERT(verifier != NULL && jwt != NULL && audience != NULL && cb != NULL);
dot = strchr(cur, '.');
if (dot == NULL) goto error;
json = parse_json_part_from_jwt(cur, dot - cur, &header_buffer);
if (json == NULL) goto error;
header = jose_header_from_json(json, header_buffer);
if (header == NULL) goto error;
cur = dot + 1;
dot = strchr(cur, '.');
if (dot == NULL) goto error;
json = parse_json_part_from_jwt(cur, dot - cur, &claims_buffer);
if (json == NULL) goto error;
claims = grpc_jwt_claims_from_json(json, claims_buffer);
if (claims == NULL) goto error;
signed_jwt_len = (size_t)(dot - jwt);
cur = dot + 1;
signature = grpc_base64_decode(cur, 1);
if (GPR_SLICE_IS_EMPTY(signature)) goto error;
retrieve_key_and_verify(
verifier_cb_ctx_create(verifier, pollset, header, claims, audience,
signature, jwt, signed_jwt_len, user_data, cb));
return;
error:
if (header != NULL) jose_header_destroy(header);
if (claims != NULL) grpc_jwt_claims_destroy(claims);
cb(user_data, GRPC_JWT_VERIFIER_BAD_FORMAT, NULL);
}
grpc_jwt_verifier *grpc_jwt_verifier_create(
const grpc_jwt_verifier_email_domain_key_url_mapping *mappings,
size_t num_mappings) {
grpc_jwt_verifier *v = gpr_malloc(sizeof(grpc_jwt_verifier));
memset(v, 0, sizeof(grpc_jwt_verifier));
grpc_httpcli_context_init(&v->http_ctx);
/* We know at least of one mapping. */
v->allocated_mappings = 1 + num_mappings;
v->mappings = gpr_malloc(v->allocated_mappings * sizeof(email_key_mapping));
verifier_put_mapping(v, GRPC_GOOGLE_SERVICE_ACCOUNTS_EMAIL_DOMAIN,
GRPC_GOOGLE_SERVICE_ACCOUNTS_KEY_URL_PREFIX);
/* User-Provided mappings. */
if (mappings != NULL) {
size_t i;
for (i = 0; i < num_mappings; i++) {
verifier_put_mapping(v, mappings[i].email_domain,
mappings[i].key_url_prefix);
}
}
return v;
}
void grpc_jwt_verifier_destroy(grpc_jwt_verifier *v) {
size_t i;
if (v == NULL) return;
grpc_httpcli_context_destroy(&v->http_ctx);
if (v->mappings != NULL) {
for (i = 0; i < v->num_mappings; i++) {
gpr_free(v->mappings[i].email_domain);
gpr_free(v->mappings[i].key_url_prefix);
}
gpr_free(v->mappings);
}
gpr_free(v);
}
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