On Mon, Oct 23, 2023 at 04:31:22PM +0200, Ahmad Fatoum wrote:
> diff --git a/crypto/jwt.c b/crypto/jwt.c
> new file mode 100644
> index 000000000000..146ddeff1e8b
> --- /dev/null
> +++ b/crypto/jwt.c
> +struct jwt *jwt_decode(const char *token, const struct jwt_key *key)
> +{
> + const char *alg_name = jwt_alg_names[key->alg];
> + enum hash_algo hash_algo;
> + const char *payload, *signature, *end;
> + u8 *sigbin;
> + size_t sig_len, sigbin_len;
> + struct jwt *jwt;
> + u8 *hash;
> + int ret;
> +
> + token = jwt_split(token, &payload, &signature, &end);
> + if (IS_ERR(token))
> + return ERR_CAST(token);
> +
> + sig_len = end - signature;
> +
> + switch (key->alg) {
> + case JWT_ALG_RS256:
> + case JWT_ALG_RS384:
> + case JWT_ALG_RS512:
> + if (sig_len == 0)
> + return ERR_PTR(-EILSEQ);
> +
> + sigbin = xzalloc(sig_len);
> + sigbin_len = decode_base64url(sigbin, sig_len, signature);
> +
> + hash_algo = digest_algo_by_jwt_alg(key->alg);
> + hash = do_hash(token, signature - token - 1, hash_algo);
> + if (IS_ERR(hash)) {
> + free(sigbin);
> + return ERR_CAST(hash);
> + }
> +
> + ret = rsa_verify(key->material.rsa_pub, sigbin, sigbin_len, hash,
> + hash_algo);
> + free(hash);
> + free(sigbin);
> + if (ret < 0) {
> + pr_debug("%s signature does not match: %pe\n",
> + alg_name, ERR_PTR(ret));
> + return ERR_PTR(ret);
> + }
> +
> + break;
> + default:
> + return ERR_PTR(-ENOSYS);
> + }
> +
> + pr_debug("verification for algo %s ok\n", alg_name);
> +
> + jwt = xzalloc(sizeof(*jwt));
> +
> + ret = jwt_part_parse(&jwt->header, token, payload - token - 1);
> + if (ret || !jwt_header_ok(jwt, key->alg)) {
> + ret = ret ?: -EINVAL;
> + pr_debug("failed to parse header: %pe\n", ERR_PTR(ret));
> + goto err;
> + }
> +
> + ret = jwt_part_parse(&jwt->payload, payload, signature - payload - 1);
> + if (ret) {
> + ret = ret ?: -EINVAL;
Dropped this superfluous line while applying.
Sascha
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