/*
 * Copyright (C) 2017 Netronome Systems, Inc.
 *
 * This software is licensed under the GNU General License Version 2,
 * June 1991 as shown in the file COPYING in the top-level directory of this
 * source tree.
 *
 * THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS"
 * WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING,
 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE
 * OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME
 * THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
 */

#include <linux/bpf.h>
#include <linux/bpf_verifier.h>
#include <linux/debugfs.h>
#include <linux/kernel.h>
#include <linux/mutex.h>
#include <linux/rtnetlink.h>
#include <net/pkt_cls.h>

#include "netdevsim.h"

#define pr_vlog(env, fmt, ...)  \
        bpf_verifier_log_write(env, "[netdevsim] " fmt, ##__VA_ARGS__)

struct nsim_bpf_bound_prog {
        struct nsim_dev *nsim_dev;
        struct bpf_prog *prog;
        struct dentry *ddir;
        const char *state;
        bool is_loaded;
        struct list_head l;
};

#define NSIM_BPF_MAX_KEYS               2

struct nsim_bpf_bound_map {
        struct netdevsim *ns;
        struct bpf_offloaded_map *map;
        struct mutex mutex;
        struct nsim_map_entry {
                void *key;
                void *value;
        } entry[NSIM_BPF_MAX_KEYS];
        struct list_head l;
};

static int nsim_bpf_string_show(struct seq_file *file, void *data)
{
        const char **str = file->private;

        if (*str)
                seq_printf(file, "%s\n", *str);

        return 0;
}
DEFINE_SHOW_ATTRIBUTE(nsim_bpf_string);

static int
nsim_bpf_verify_insn(struct bpf_verifier_env *env, int insn_idx, int prev_insn)
{
        struct nsim_bpf_bound_prog *state;
        int ret = 0;

        state = env->prog->aux->offload->dev_priv;
        if (state->nsim_dev->bpf_bind_verifier_delay && !insn_idx)
                msleep(state->nsim_dev->bpf_bind_verifier_delay);

        if (insn_idx == env->prog->len - 1) {
                pr_vlog(env, "Hello from netdevsim!\n");

                if (!state->nsim_dev->bpf_bind_verifier_accept)
                        ret = -EOPNOTSUPP;
        }

        return ret;
}

static int nsim_bpf_finalize(struct bpf_verifier_env *env)
{
        return 0;
}

static bool nsim_xdp_offload_active(struct netdevsim *ns)
{
        return ns->xdp_hw.prog;
}

static void nsim_prog_set_loaded(struct bpf_prog *prog, bool loaded)
{
        struct nsim_bpf_bound_prog *state;

        if (!prog || !bpf_prog_is_offloaded(prog->aux))
                return;

        state = prog->aux->offload->dev_priv;
        state->is_loaded = loaded;
}

static int
nsim_bpf_offload(struct netdevsim *ns, struct bpf_prog *prog, bool oldprog)
{
        nsim_prog_set_loaded(ns->bpf_offloaded, false);

        WARN(!!ns->bpf_offloaded != oldprog,
             "bad offload state, expected offload %sto be active",
             oldprog ? "" : "not ");
        ns->bpf_offloaded = prog;
        ns->bpf_offloaded_id = prog ? prog->aux->id : 0;
        nsim_prog_set_loaded(prog, true);

        return 0;
}

int nsim_bpf_setup_tc_block_cb(enum tc_setup_type type,
                               void *type_data, void *cb_priv)
{
        struct tc_cls_bpf_offload *cls_bpf = type_data;
        struct bpf_prog *prog = cls_bpf->prog;
        struct netdevsim *ns = cb_priv;
        struct bpf_prog *oldprog;

        if (type != TC_SETUP_CLSBPF) {
                NSIM_EA(cls_bpf->common.extack,
                        "only offload of BPF classifiers supported");
                return -EOPNOTSUPP;
        }

        if (!tc_cls_can_offload_and_chain0(ns->netdev, &cls_bpf->common))
                return -EOPNOTSUPP;

        if (cls_bpf->common.protocol != htons(ETH_P_ALL)) {
                NSIM_EA(cls_bpf->common.extack,
                        "only ETH_P_ALL supported as filter protocol");
                return -EOPNOTSUPP;
        }

        if (!ns->bpf_tc_accept) {
                NSIM_EA(cls_bpf->common.extack,
                        "netdevsim configured to reject BPF TC offload");
                return -EOPNOTSUPP;
        }
        /* Note: progs without skip_sw will probably not be dev bound */
        if (prog && !prog->aux->offload && !ns->bpf_tc_non_bound_accept) {
                NSIM_EA(cls_bpf->common.extack,
                        "netdevsim configured to reject unbound programs");
                return -EOPNOTSUPP;
        }

        if (cls_bpf->command != TC_CLSBPF_OFFLOAD)
                return -EOPNOTSUPP;

        oldprog = cls_bpf->oldprog;

        /* Don't remove if oldprog doesn't match driver's state */
        if (ns->bpf_offloaded != oldprog) {
                oldprog = NULL;
                if (!cls_bpf->prog)
                        return 0;
                if (ns->bpf_offloaded) {
                        NSIM_EA(cls_bpf->common.extack,
                                "driver and netdev offload states mismatch");
                        return -EBUSY;
                }
        }

        return nsim_bpf_offload(ns, cls_bpf->prog, oldprog);
}

int nsim_bpf_disable_tc(struct netdevsim *ns)
{
        if (ns->bpf_offloaded && !nsim_xdp_offload_active(ns))
                return -EBUSY;
        return 0;
}

static int nsim_xdp_offload_prog(struct netdevsim *ns, struct netdev_bpf *bpf)
{
        if (!nsim_xdp_offload_active(ns) && !bpf->prog)
                return 0;
        if (!nsim_xdp_offload_active(ns) && bpf->prog && ns->bpf_offloaded) {
                NSIM_EA(bpf->extack, "TC program is already loaded");
                return -EBUSY;
        }

        return nsim_bpf_offload(ns, bpf->prog, nsim_xdp_offload_active(ns));
}

static int
nsim_xdp_set_prog(struct netdevsim *ns, struct netdev_bpf *bpf,
                  struct xdp_attachment_info *xdp)
{
        int err;

        if (bpf->command == XDP_SETUP_PROG && !ns->bpf_xdpdrv_accept) {
                NSIM_EA(bpf->extack, "driver XDP disabled in DebugFS");
                return -EOPNOTSUPP;
        }
        if (bpf->command == XDP_SETUP_PROG_HW && !ns->bpf_xdpoffload_accept) {
                NSIM_EA(bpf->extack, "XDP offload disabled in DebugFS");
                return -EOPNOTSUPP;
        }

        if (bpf->command == XDP_SETUP_PROG_HW) {
                err = nsim_xdp_offload_prog(ns, bpf);
                if (err)
                        return err;
        }

        xdp_attachment_setup(xdp, bpf);

        return 0;
}

static int nsim_bpf_create_prog(struct nsim_dev *nsim_dev,
                                struct bpf_prog *prog)
{
        struct nsim_bpf_bound_prog *state;
        char name[16];
        int ret;

        state = kzalloc_obj(*state);
        if (!state)
                return -ENOMEM;

        state->nsim_dev = nsim_dev;
        state->prog = prog;
        state->state = "verify";

        /* Program id is not populated yet when we create the state. */
        sprintf(name, "%u", nsim_dev->prog_id_gen++);
        state->ddir = debugfs_create_dir(name, nsim_dev->ddir_bpf_bound_progs);
        if (IS_ERR(state->ddir)) {
                ret = PTR_ERR(state->ddir);
                kfree(state);
                return ret;
        }

        debugfs_create_u32("id", 0400, state->ddir, &prog->aux->id);
        debugfs_create_file("state", 0400, state->ddir,
                            &state->state, &nsim_bpf_string_fops);
        debugfs_create_bool("loaded", 0400, state->ddir, &state->is_loaded);

        mutex_lock(&nsim_dev->progs_list_lock);
        list_add_tail(&state->l, &nsim_dev->bpf_bound_progs);
        mutex_unlock(&nsim_dev->progs_list_lock);

        prog->aux->offload->dev_priv = state;

        return 0;
}

static int nsim_bpf_verifier_prep(struct bpf_prog *prog)
{
        struct nsim_dev *nsim_dev =
                        bpf_offload_dev_priv(prog->aux->offload->offdev);

        if (!nsim_dev->bpf_bind_accept)
                return -EOPNOTSUPP;

        return nsim_bpf_create_prog(nsim_dev, prog);
}

static int nsim_bpf_translate(struct bpf_prog *prog)
{
        struct nsim_bpf_bound_prog *state = prog->aux->offload->dev_priv;

        state->state = "xlated";
        return 0;
}

static void nsim_bpf_destroy_prog(struct bpf_prog *prog)
{
        struct nsim_bpf_bound_prog *state;
        struct nsim_dev *nsim_dev;

        state = prog->aux->offload->dev_priv;
        nsim_dev = state->nsim_dev;
        WARN(state->is_loaded,
             "offload state destroyed while program still bound");
        debugfs_remove_recursive(state->ddir);
        mutex_lock(&nsim_dev->progs_list_lock);
        list_del(&state->l);
        mutex_unlock(&nsim_dev->progs_list_lock);
        kfree(state);
}

static const struct bpf_prog_offload_ops nsim_bpf_dev_ops = {
        .insn_hook      = nsim_bpf_verify_insn,
        .finalize       = nsim_bpf_finalize,
        .prepare        = nsim_bpf_verifier_prep,
        .translate      = nsim_bpf_translate,
        .destroy        = nsim_bpf_destroy_prog,
};

static int nsim_setup_prog_checks(struct netdevsim *ns, struct netdev_bpf *bpf)
{
        if (bpf->prog && bpf->prog->aux->offload) {
                NSIM_EA(bpf->extack, "attempt to load offloaded prog to drv");
                return -EINVAL;
        }
        if (bpf->prog && !bpf->prog->aux->xdp_has_frags &&
            ns->netdev->mtu > NSIM_XDP_MAX_MTU) {
                NSIM_EA(bpf->extack, "MTU too large w/ XDP enabled");
                return -EINVAL;
        }
        return 0;
}

static int
nsim_setup_prog_hw_checks(struct netdevsim *ns, struct netdev_bpf *bpf)
{
        struct nsim_bpf_bound_prog *state;

        if (!bpf->prog)
                return 0;

        if (!bpf_prog_is_offloaded(bpf->prog->aux)) {
                NSIM_EA(bpf->extack, "xdpoffload of non-bound program");
                return -EINVAL;
        }

        state = bpf->prog->aux->offload->dev_priv;
        if (WARN_ON(strcmp(state->state, "xlated"))) {
                NSIM_EA(bpf->extack, "offloading program in bad state");
                return -EINVAL;
        }
        return 0;
}

static bool
nsim_map_key_match(struct bpf_map *map, struct nsim_map_entry *e, void *key)
{
        return e->key && !memcmp(key, e->key, map->key_size);
}

static int nsim_map_key_find(struct bpf_offloaded_map *offmap, void *key)
{
        struct nsim_bpf_bound_map *nmap = offmap->dev_priv;
        unsigned int i;

        for (i = 0; i < ARRAY_SIZE(nmap->entry); i++)
                if (nsim_map_key_match(&offmap->map, &nmap->entry[i], key))
                        return i;

        return -ENOENT;
}

static int
nsim_map_alloc_elem(struct bpf_offloaded_map *offmap, unsigned int idx)
{
        struct nsim_bpf_bound_map *nmap = offmap->dev_priv;

        nmap->entry[idx].key = kmalloc(offmap->map.key_size,
                                       GFP_KERNEL_ACCOUNT | __GFP_NOWARN);
        if (!nmap->entry[idx].key)
                return -ENOMEM;
        nmap->entry[idx].value = kmalloc(offmap->map.value_size,
                                         GFP_KERNEL_ACCOUNT | __GFP_NOWARN);
        if (!nmap->entry[idx].value) {
                kfree(nmap->entry[idx].key);
                nmap->entry[idx].key = NULL;
                return -ENOMEM;
        }

        return 0;
}

static int
nsim_map_get_next_key(struct bpf_offloaded_map *offmap,
                      void *key, void *next_key)
{
        struct nsim_bpf_bound_map *nmap = offmap->dev_priv;
        int idx = -ENOENT;

        mutex_lock(&nmap->mutex);

        if (key)
                idx = nsim_map_key_find(offmap, key);
        if (idx == -ENOENT)
                idx = 0;
        else
                idx++;

        for (; idx < ARRAY_SIZE(nmap->entry); idx++) {
                if (nmap->entry[idx].key) {
                        memcpy(next_key, nmap->entry[idx].key,
                               offmap->map.key_size);
                        break;
                }
        }

        mutex_unlock(&nmap->mutex);

        if (idx == ARRAY_SIZE(nmap->entry))
                return -ENOENT;
        return 0;
}

static int
nsim_map_lookup_elem(struct bpf_offloaded_map *offmap, void *key, void *value)
{
        struct nsim_bpf_bound_map *nmap = offmap->dev_priv;
        int idx;

        mutex_lock(&nmap->mutex);

        idx = nsim_map_key_find(offmap, key);
        if (idx >= 0)
                memcpy(value, nmap->entry[idx].value, offmap->map.value_size);

        mutex_unlock(&nmap->mutex);

        return idx < 0 ? idx : 0;
}

static int
nsim_map_update_elem(struct bpf_offloaded_map *offmap,
                     void *key, void *value, u64 flags)
{
        struct nsim_bpf_bound_map *nmap = offmap->dev_priv;
        int idx, err = 0;

        mutex_lock(&nmap->mutex);

        idx = nsim_map_key_find(offmap, key);
        if (idx < 0 && flags == BPF_EXIST) {
                err = idx;
                goto exit_unlock;
        }
        if (idx >= 0 && flags == BPF_NOEXIST) {
                err = -EEXIST;
                goto exit_unlock;
        }

        if (idx < 0) {
                for (idx = 0; idx < ARRAY_SIZE(nmap->entry); idx++)
                        if (!nmap->entry[idx].key)
                                break;
                if (idx == ARRAY_SIZE(nmap->entry)) {
                        err = -E2BIG;
                        goto exit_unlock;
                }

                err = nsim_map_alloc_elem(offmap, idx);
                if (err)
                        goto exit_unlock;
        }

        memcpy(nmap->entry[idx].key, key, offmap->map.key_size);
        memcpy(nmap->entry[idx].value, value, offmap->map.value_size);
exit_unlock:
        mutex_unlock(&nmap->mutex);

        return err;
}

static int nsim_map_delete_elem(struct bpf_offloaded_map *offmap, void *key)
{
        struct nsim_bpf_bound_map *nmap = offmap->dev_priv;
        int idx;

        if (offmap->map.map_type == BPF_MAP_TYPE_ARRAY)
                return -EINVAL;

        mutex_lock(&nmap->mutex);

        idx = nsim_map_key_find(offmap, key);
        if (idx >= 0) {
                kfree(nmap->entry[idx].key);
                kfree(nmap->entry[idx].value);
                memset(&nmap->entry[idx], 0, sizeof(nmap->entry[idx]));
        }

        mutex_unlock(&nmap->mutex);

        return idx < 0 ? idx : 0;
}

static const struct bpf_map_dev_ops nsim_bpf_map_ops = {
        .map_get_next_key       = nsim_map_get_next_key,
        .map_lookup_elem        = nsim_map_lookup_elem,
        .map_update_elem        = nsim_map_update_elem,
        .map_delete_elem        = nsim_map_delete_elem,
};

static int
nsim_bpf_map_alloc(struct netdevsim *ns, struct bpf_offloaded_map *offmap)
{
        struct nsim_bpf_bound_map *nmap;
        int i, err;

        if (WARN_ON(offmap->map.map_type != BPF_MAP_TYPE_ARRAY &&
                    offmap->map.map_type != BPF_MAP_TYPE_HASH))
                return -EINVAL;
        if (offmap->map.max_entries > NSIM_BPF_MAX_KEYS)
                return -ENOMEM;
        if (offmap->map.map_flags)
                return -EINVAL;

        nmap = kzalloc_obj(*nmap, GFP_KERNEL_ACCOUNT);
        if (!nmap)
                return -ENOMEM;

        offmap->dev_priv = nmap;
        nmap->ns = ns;
        nmap->map = offmap;
        mutex_init(&nmap->mutex);

        if (offmap->map.map_type == BPF_MAP_TYPE_ARRAY) {
                for (i = 0; i < ARRAY_SIZE(nmap->entry); i++) {
                        u32 *key;

                        err = nsim_map_alloc_elem(offmap, i);
                        if (err)
                                goto err_free;
                        key = nmap->entry[i].key;
                        *key = i;
                        memset(nmap->entry[i].value, 0, offmap->map.value_size);
                }
        }

        offmap->dev_ops = &nsim_bpf_map_ops;
        list_add_tail(&nmap->l, &ns->nsim_dev->bpf_bound_maps);

        return 0;

err_free:
        while (--i >= 0) {
                kfree(nmap->entry[i].key);
                kfree(nmap->entry[i].value);
        }
        kfree(nmap);
        return err;
}

static void nsim_bpf_map_free(struct bpf_offloaded_map *offmap)
{
        struct nsim_bpf_bound_map *nmap = offmap->dev_priv;
        unsigned int i;

        for (i = 0; i < ARRAY_SIZE(nmap->entry); i++) {
                kfree(nmap->entry[i].key);
                kfree(nmap->entry[i].value);
        }
        list_del_init(&nmap->l);
        mutex_destroy(&nmap->mutex);
        kfree(nmap);
}

int nsim_bpf(struct net_device *dev, struct netdev_bpf *bpf)
{
        struct netdevsim *ns = netdev_priv(dev);
        int err;

        ASSERT_RTNL();

        switch (bpf->command) {
        case XDP_SETUP_PROG:
                err = nsim_setup_prog_checks(ns, bpf);
                if (err)
                        return err;

                return nsim_xdp_set_prog(ns, bpf, &ns->xdp);
        case XDP_SETUP_PROG_HW:
                err = nsim_setup_prog_hw_checks(ns, bpf);
                if (err)
                        return err;

                return nsim_xdp_set_prog(ns, bpf, &ns->xdp_hw);
        case BPF_OFFLOAD_MAP_ALLOC:
                if (!ns->bpf_map_accept)
                        return -EOPNOTSUPP;

                return nsim_bpf_map_alloc(ns, bpf->offmap);
        case BPF_OFFLOAD_MAP_FREE:
                nsim_bpf_map_free(bpf->offmap);
                return 0;
        default:
                return -EINVAL;
        }
}

int nsim_bpf_dev_init(struct nsim_dev *nsim_dev)
{
        int err;

        INIT_LIST_HEAD(&nsim_dev->bpf_bound_progs);
        INIT_LIST_HEAD(&nsim_dev->bpf_bound_maps);

        nsim_dev->ddir_bpf_bound_progs = debugfs_create_dir("bpf_bound_progs",
                                                            nsim_dev->ddir);
        if (IS_ERR(nsim_dev->ddir_bpf_bound_progs))
                return PTR_ERR(nsim_dev->ddir_bpf_bound_progs);

        nsim_dev->bpf_dev = bpf_offload_dev_create(&nsim_bpf_dev_ops, nsim_dev);
        err = PTR_ERR_OR_ZERO(nsim_dev->bpf_dev);
        if (err)
                return err;

        nsim_dev->bpf_bind_accept = true;
        debugfs_create_bool("bpf_bind_accept", 0600, nsim_dev->ddir,
                            &nsim_dev->bpf_bind_accept);
        debugfs_create_u32("bpf_bind_verifier_delay", 0600, nsim_dev->ddir,
                           &nsim_dev->bpf_bind_verifier_delay);
        nsim_dev->bpf_bind_verifier_accept = true;
        debugfs_create_bool("bpf_bind_verifier_accept", 0600, nsim_dev->ddir,
                            &nsim_dev->bpf_bind_verifier_accept);
        return 0;
}

void nsim_bpf_dev_exit(struct nsim_dev *nsim_dev)
{
        WARN_ON(!list_empty(&nsim_dev->bpf_bound_progs));
        WARN_ON(!list_empty(&nsim_dev->bpf_bound_maps));
        bpf_offload_dev_destroy(nsim_dev->bpf_dev);
}

int nsim_bpf_init(struct netdevsim *ns)
{
        struct dentry *ddir = ns->nsim_dev_port->ddir;
        int err;

        err = bpf_offload_dev_netdev_register(ns->nsim_dev->bpf_dev,
                                              ns->netdev);
        if (err)
                return err;

        debugfs_create_u32("bpf_offloaded_id", 0400, ddir,
                           &ns->bpf_offloaded_id);

        ns->bpf_tc_accept = true;
        debugfs_create_bool("bpf_tc_accept", 0600, ddir,
                            &ns->bpf_tc_accept);
        debugfs_create_bool("bpf_tc_non_bound_accept", 0600, ddir,
                            &ns->bpf_tc_non_bound_accept);
        ns->bpf_xdpdrv_accept = true;
        debugfs_create_bool("bpf_xdpdrv_accept", 0600, ddir,
                            &ns->bpf_xdpdrv_accept);
        ns->bpf_xdpoffload_accept = true;
        debugfs_create_bool("bpf_xdpoffload_accept", 0600, ddir,
                            &ns->bpf_xdpoffload_accept);

        ns->bpf_map_accept = true;
        debugfs_create_bool("bpf_map_accept", 0600, ddir,
                            &ns->bpf_map_accept);

        return 0;
}

void nsim_bpf_uninit(struct netdevsim *ns)
{
        WARN_ON(ns->xdp.prog);
        WARN_ON(ns->xdp_hw.prog);
        WARN_ON(ns->bpf_offloaded);
        bpf_offload_dev_netdev_unregister(ns->nsim_dev->bpf_dev, ns->netdev);
}