// SPDX-License-Identifier: GPL-2.0-or-later
/* Public-key operation keyctls
 *
 * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#include <linux/slab.h>
#include <linux/err.h>
#include <linux/key.h>
#include <linux/keyctl.h>
#include <linux/parser.h>
#include <linux/uaccess.h>
#include <keys/user-type.h>
#include "internal.h"

static void keyctl_pkey_params_free(struct kernel_pkey_params *params)
{
        kfree(params->info);
        key_put(params->key);
}

enum {
        Opt_err,
        Opt_enc,                /* "enc=<encoding>" eg. "enc=oaep" */
        Opt_hash,               /* "hash=<digest-name>" eg. "hash=sha1" */
};

static const match_table_t param_keys = {
        { Opt_enc,      "enc=%s" },
        { Opt_hash,     "hash=%s" },
        { Opt_err,      NULL }
};

/*
 * Parse the information string which consists of key=val pairs.
 */
static int keyctl_pkey_params_parse(struct kernel_pkey_params *params)
{
        unsigned long token_mask = 0;
        substring_t args[MAX_OPT_ARGS];
        char *c = params->info, *p, *q;
        int token;

        while ((p = strsep(&c, " \t"))) {
                if (*p == '\0' || *p == ' ' || *p == '\t')
                        continue;
                token = match_token(p, param_keys, args);
                if (token == Opt_err)
                        return -EINVAL;
                if (__test_and_set_bit(token, &token_mask))
                        return -EINVAL;
                q = args[0].from;
                if (!q[0])
                        return -EINVAL;

                switch (token) {
                case Opt_enc:
                        params->encoding = q;
                        break;

                case Opt_hash:
                        params->hash_algo = q;
                        break;

                default:
                        return -EINVAL;
                }
        }

        return 0;
}

/*
 * Interpret parameters.  Callers must always call the free function
 * on params, even if an error is returned.
 */
static int keyctl_pkey_params_get(key_serial_t id,
                                  const char __user *_info,
                                  struct kernel_pkey_params *params)
{
        key_ref_t key_ref;
        void *p;
        int ret;

        memset(params, 0, sizeof(*params));
        params->encoding = "raw";

        p = strndup_user(_info, PAGE_SIZE);
        if (IS_ERR(p))
                return PTR_ERR(p);
        params->info = p;

        ret = keyctl_pkey_params_parse(params);
        if (ret < 0)
                return ret;

        key_ref = lookup_user_key(id, 0, KEY_NEED_SEARCH);
        if (IS_ERR(key_ref))
                return PTR_ERR(key_ref);
        params->key = key_ref_to_ptr(key_ref);

        if (!params->key->type->asym_query)
                return -EOPNOTSUPP;

        return 0;
}

/*
 * Get parameters from userspace.  Callers must always call the free function
 * on params, even if an error is returned.
 */
static int keyctl_pkey_params_get_2(const struct keyctl_pkey_params __user *_params,
                                    const char __user *_info,
                                    int op,
                                    struct kernel_pkey_params *params)
{
        struct keyctl_pkey_params uparams;
        struct kernel_pkey_query info;
        int ret;

        memset(params, 0, sizeof(*params));
        params->encoding = "raw";

        if (copy_from_user(&uparams, _params, sizeof(uparams)) != 0)
                return -EFAULT;

        ret = keyctl_pkey_params_get(uparams.key_id, _info, params);
        if (ret < 0)
                return ret;

        ret = params->key->type->asym_query(params, &info);
        if (ret < 0)
                return ret;

        switch (op) {
        case KEYCTL_PKEY_ENCRYPT:
        case KEYCTL_PKEY_DECRYPT:
                if (uparams.in_len  > info.max_enc_size ||
                    uparams.out_len > info.max_dec_size)
                        return -EINVAL;
                break;
        case KEYCTL_PKEY_SIGN:
        case KEYCTL_PKEY_VERIFY:
                if (uparams.in_len  > info.max_sig_size ||
                    uparams.out_len > info.max_data_size)
                        return -EINVAL;
                break;
        default:
                BUG();
        }

        params->in_len  = uparams.in_len;
        params->out_len = uparams.out_len;
        return 0;
}

/*
 * Query information about an asymmetric key.
 */
long keyctl_pkey_query(key_serial_t id,
                       const char __user *_info,
                       struct keyctl_pkey_query __user *_res)
{
        struct kernel_pkey_params params;
        struct kernel_pkey_query res;
        long ret;

        ret = keyctl_pkey_params_get(id, _info, &params);
        if (ret < 0)
                goto error;

        ret = params.key->type->asym_query(&params, &res);
        if (ret < 0)
                goto error;

        ret = -EFAULT;
        if (copy_to_user(_res, &res, sizeof(res)) == 0 &&
            clear_user(_res->__spare, sizeof(_res->__spare)) == 0)
                ret = 0;

error:
        keyctl_pkey_params_free(&params);
        return ret;
}

/*
 * Encrypt/decrypt/sign
 *
 * Encrypt data, decrypt data or sign data using a public key.
 *
 * _info is a string of supplementary information in key=val format.  For
 * instance, it might contain:
 *
 *      "enc=pkcs1 hash=sha256"
 *
 * where enc= specifies the encoding and hash= selects the OID to go in that
 * particular encoding if required.  If enc= isn't supplied, it's assumed that
 * the caller is supplying raw values.
 *
 * If successful, the amount of data written into the output buffer is
 * returned.
 */
long keyctl_pkey_e_d_s(int op,
                       const struct keyctl_pkey_params __user *_params,
                       const char __user *_info,
                       const void __user *_in,
                       void __user *_out)
{
        struct kernel_pkey_params params;
        void *in, *out;
        long ret;

        ret = keyctl_pkey_params_get_2(_params, _info, op, &params);
        if (ret < 0)
                goto error_params;

        ret = -EOPNOTSUPP;
        if (!params.key->type->asym_eds_op)
                goto error_params;

        switch (op) {
        case KEYCTL_PKEY_ENCRYPT:
                params.op = kernel_pkey_encrypt;
                break;
        case KEYCTL_PKEY_DECRYPT:
                params.op = kernel_pkey_decrypt;
                break;
        case KEYCTL_PKEY_SIGN:
                params.op = kernel_pkey_sign;
                break;
        default:
                BUG();
        }

        in = memdup_user(_in, params.in_len);
        if (IS_ERR(in)) {
                ret = PTR_ERR(in);
                goto error_params;
        }

        ret = -ENOMEM;
        out = kmalloc(params.out_len, GFP_KERNEL);
        if (!out)
                goto error_in;

        ret = params.key->type->asym_eds_op(&params, in, out);
        if (ret < 0)
                goto error_out;

        if (copy_to_user(_out, out, ret) != 0)
                ret = -EFAULT;

error_out:
        kfree(out);
error_in:
        kfree(in);
error_params:
        keyctl_pkey_params_free(&params);
        return ret;
}

/*
 * Verify a signature.
 *
 * Verify a public key signature using the given key, or if not given, search
 * for a matching key.
 *
 * _info is a string of supplementary information in key=val format.  For
 * instance, it might contain:
 *
 *      "enc=pkcs1 hash=sha256"
 *
 * where enc= specifies the signature blob encoding and hash= selects the OID
 * to go in that particular encoding.  If enc= isn't supplied, it's assumed
 * that the caller is supplying raw values.
 *
 * If successful, 0 is returned.
 */
long keyctl_pkey_verify(const struct keyctl_pkey_params __user *_params,
                        const char __user *_info,
                        const void __user *_in,
                        const void __user *_in2)
{
        struct kernel_pkey_params params;
        void *in, *in2;
        long ret;

        ret = keyctl_pkey_params_get_2(_params, _info, KEYCTL_PKEY_VERIFY,
                                       &params);
        if (ret < 0)
                goto error_params;

        ret = -EOPNOTSUPP;
        if (!params.key->type->asym_verify_signature)
                goto error_params;

        in = memdup_user(_in, params.in_len);
        if (IS_ERR(in)) {
                ret = PTR_ERR(in);
                goto error_params;
        }

        in2 = memdup_user(_in2, params.in2_len);
        if (IS_ERR(in2)) {
                ret = PTR_ERR(in2);
                goto error_in;
        }

        params.op = kernel_pkey_verify;
        ret = params.key->type->asym_verify_signature(&params, in, in2);

        kfree(in2);
error_in:
        kfree(in);
error_params:
        keyctl_pkey_params_free(&params);
        return ret;
}