//SPDX-License-Identifier: GPL-2.0
#include <linux/bpf-cgroup.h>
#include <linux/bpf.h>
#include <linux/btf.h>
#include <linux/bug.h>
#include <linux/filter.h>
#include <linux/mm.h>
#include <linux/rbtree.h>
#include <linux/slab.h>
#include <uapi/linux/btf.h>

DEFINE_PER_CPU(struct bpf_cgroup_storage*, bpf_cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE]);

#ifdef CONFIG_CGROUP_BPF

#define LOCAL_STORAGE_CREATE_FLAG_MASK                                  \
        (BPF_F_NUMA_NODE | BPF_F_ACCESS_MASK)

struct bpf_cgroup_storage_map {
        struct bpf_map map;

        spinlock_t lock;
        struct bpf_prog *prog;
        struct rb_root root;
        struct list_head list;
};

static struct bpf_cgroup_storage_map *map_to_storage(struct bpf_map *map)
{
        return container_of(map, struct bpf_cgroup_storage_map, map);
}

static int bpf_cgroup_storage_key_cmp(
        const struct bpf_cgroup_storage_key *key1,
        const struct bpf_cgroup_storage_key *key2)
{
        if (key1->cgroup_inode_id < key2->cgroup_inode_id)
                return -1;
        else if (key1->cgroup_inode_id > key2->cgroup_inode_id)
                return 1;
        else if (key1->attach_type < key2->attach_type)
                return -1;
        else if (key1->attach_type > key2->attach_type)
                return 1;
        return 0;
}

static struct bpf_cgroup_storage *cgroup_storage_lookup(
        struct bpf_cgroup_storage_map *map, struct bpf_cgroup_storage_key *key,
        bool locked)
{
        struct rb_root *root = &map->root;
        struct rb_node *node;

        if (!locked)
                spin_lock_bh(&map->lock);

        node = root->rb_node;
        while (node) {
                struct bpf_cgroup_storage *storage;

                storage = container_of(node, struct bpf_cgroup_storage, node);

                switch (bpf_cgroup_storage_key_cmp(key, &storage->key)) {
                case -1:
                        node = node->rb_left;
                        break;
                case 1:
                        node = node->rb_right;
                        break;
                default:
                        if (!locked)
                                spin_unlock_bh(&map->lock);
                        return storage;
                }
        }

        if (!locked)
                spin_unlock_bh(&map->lock);

        return NULL;
}

static int cgroup_storage_insert(struct bpf_cgroup_storage_map *map,
                                 struct bpf_cgroup_storage *storage)
{
        struct rb_root *root = &map->root;
        struct rb_node **new = &(root->rb_node), *parent = NULL;

        while (*new) {
                struct bpf_cgroup_storage *this;

                this = container_of(*new, struct bpf_cgroup_storage, node);

                parent = *new;
                switch (bpf_cgroup_storage_key_cmp(&storage->key, &this->key)) {
                case -1:
                        new = &((*new)->rb_left);
                        break;
                case 1:
                        new = &((*new)->rb_right);
                        break;
                default:
                        return -EEXIST;
                }
        }

        rb_link_node(&storage->node, parent, new);
        rb_insert_color(&storage->node, root);

        return 0;
}

static void *cgroup_storage_lookup_elem(struct bpf_map *_map, void *_key)
{
        struct bpf_cgroup_storage_map *map = map_to_storage(_map);
        struct bpf_cgroup_storage_key *key = _key;
        struct bpf_cgroup_storage *storage;

        storage = cgroup_storage_lookup(map, key, false);
        if (!storage)
                return NULL;

        return &READ_ONCE(storage->buf)->data[0];
}

static int cgroup_storage_update_elem(struct bpf_map *map, void *_key,
                                      void *value, u64 flags)
{
        struct bpf_cgroup_storage_key *key = _key;
        struct bpf_cgroup_storage *storage;
        struct bpf_storage_buffer *new;

        if (unlikely(flags & ~(BPF_F_LOCK | BPF_EXIST | BPF_NOEXIST)))
                return -EINVAL;

        if (unlikely(flags & BPF_NOEXIST))
                return -EINVAL;

        if (unlikely((flags & BPF_F_LOCK) &&
                     !map_value_has_spin_lock(map)))
                return -EINVAL;

        storage = cgroup_storage_lookup((struct bpf_cgroup_storage_map *)map,
                                        key, false);
        if (!storage)
                return -ENOENT;

        if (flags & BPF_F_LOCK) {
                copy_map_value_locked(map, storage->buf->data, value, false);
                return 0;
        }

        new = kmalloc_node(sizeof(struct bpf_storage_buffer) +
                           map->value_size,
                           __GFP_ZERO | GFP_ATOMIC | __GFP_NOWARN,
                           map->numa_node);
        if (!new)
                return -ENOMEM;

        memcpy(&new->data[0], value, map->value_size);
        check_and_init_map_lock(map, new->data);

        new = xchg(&storage->buf, new);
        kfree_rcu(new, rcu);

        return 0;
}

int bpf_percpu_cgroup_storage_copy(struct bpf_map *_map, void *_key,
                                   void *value)
{
        struct bpf_cgroup_storage_map *map = map_to_storage(_map);
        struct bpf_cgroup_storage_key *key = _key;
        struct bpf_cgroup_storage *storage;
        int cpu, off = 0;
        u32 size;

        rcu_read_lock();
        storage = cgroup_storage_lookup(map, key, false);
        if (!storage) {
                rcu_read_unlock();
                return -ENOENT;
        }

        /* per_cpu areas are zero-filled and bpf programs can only
         * access 'value_size' of them, so copying rounded areas
         * will not leak any kernel data
         */
        size = round_up(_map->value_size, 8);
        for_each_possible_cpu(cpu) {
                bpf_long_memcpy(value + off,
                                per_cpu_ptr(storage->percpu_buf, cpu), size);
                off += size;
        }
        rcu_read_unlock();
        return 0;
}

int bpf_percpu_cgroup_storage_update(struct bpf_map *_map, void *_key,
                                     void *value, u64 map_flags)
{
        struct bpf_cgroup_storage_map *map = map_to_storage(_map);
        struct bpf_cgroup_storage_key *key = _key;
        struct bpf_cgroup_storage *storage;
        int cpu, off = 0;
        u32 size;

        if (map_flags != BPF_ANY && map_flags != BPF_EXIST)
                return -EINVAL;

        rcu_read_lock();
        storage = cgroup_storage_lookup(map, key, false);
        if (!storage) {
                rcu_read_unlock();
                return -ENOENT;
        }

        /* the user space will provide round_up(value_size, 8) bytes that
         * will be copied into per-cpu area. bpf programs can only access
         * value_size of it. During lookup the same extra bytes will be
         * returned or zeros which were zero-filled by percpu_alloc,
         * so no kernel data leaks possible
         */
        size = round_up(_map->value_size, 8);
        for_each_possible_cpu(cpu) {
                bpf_long_memcpy(per_cpu_ptr(storage->percpu_buf, cpu),
                                value + off, size);
                off += size;
        }
        rcu_read_unlock();
        return 0;
}

static int cgroup_storage_get_next_key(struct bpf_map *_map, void *_key,
                                       void *_next_key)
{
        struct bpf_cgroup_storage_map *map = map_to_storage(_map);
        struct bpf_cgroup_storage_key *key = _key;
        struct bpf_cgroup_storage_key *next = _next_key;
        struct bpf_cgroup_storage *storage;

        spin_lock_bh(&map->lock);

        if (list_empty(&map->list))
                goto enoent;

        if (key) {
                storage = cgroup_storage_lookup(map, key, true);
                if (!storage)
                        goto enoent;

                storage = list_next_entry(storage, list);
                if (!storage)
                        goto enoent;
        } else {
                storage = list_first_entry(&map->list,
                                         struct bpf_cgroup_storage, list);
        }

        spin_unlock_bh(&map->lock);
        next->attach_type = storage->key.attach_type;
        next->cgroup_inode_id = storage->key.cgroup_inode_id;
        return 0;

enoent:
        spin_unlock_bh(&map->lock);
        return -ENOENT;
}

static struct bpf_map *cgroup_storage_map_alloc(union bpf_attr *attr)
{
        int numa_node = bpf_map_attr_numa_node(attr);
        struct bpf_cgroup_storage_map *map;
        struct bpf_map_memory mem;
        int ret;

        if (attr->key_size != sizeof(struct bpf_cgroup_storage_key))
                return ERR_PTR(-EINVAL);

        if (attr->value_size == 0)
                return ERR_PTR(-EINVAL);

        if (attr->value_size > PAGE_SIZE)
                return ERR_PTR(-E2BIG);

        if (attr->map_flags & ~LOCAL_STORAGE_CREATE_FLAG_MASK ||
            !bpf_map_flags_access_ok(attr->map_flags))
                return ERR_PTR(-EINVAL);

        if (attr->max_entries)
                /* max_entries is not used and enforced to be 0 */
                return ERR_PTR(-EINVAL);

        ret = bpf_map_charge_init(&mem, sizeof(struct bpf_cgroup_storage_map));
        if (ret < 0)
                return ERR_PTR(ret);

        map = kmalloc_node(sizeof(struct bpf_cgroup_storage_map),
                           __GFP_ZERO | GFP_USER, numa_node);
        if (!map) {
                bpf_map_charge_finish(&mem);
                return ERR_PTR(-ENOMEM);
        }

        bpf_map_charge_move(&map->map.memory, &mem);

        /* copy mandatory map attributes */
        bpf_map_init_from_attr(&map->map, attr);

        spin_lock_init(&map->lock);
        map->root = RB_ROOT;
        INIT_LIST_HEAD(&map->list);

        return &map->map;
}

static void cgroup_storage_map_free(struct bpf_map *_map)
{
        struct bpf_cgroup_storage_map *map = map_to_storage(_map);

        WARN_ON(!RB_EMPTY_ROOT(&map->root));
        WARN_ON(!list_empty(&map->list));

        kfree(map);
}

static int cgroup_storage_delete_elem(struct bpf_map *map, void *key)
{
        return -EINVAL;
}

static int cgroup_storage_check_btf(const struct bpf_map *map,
                                    const struct btf *btf,
                                    const struct btf_type *key_type,
                                    const struct btf_type *value_type)
{
        struct btf_member *m;
        u32 offset, size;

        /* Key is expected to be of struct bpf_cgroup_storage_key type,
         * which is:
         * struct bpf_cgroup_storage_key {
         *      __u64   cgroup_inode_id;
         *      __u32   attach_type;
         * };
         */

        /*
         * Key_type must be a structure with two fields.
         */
        if (BTF_INFO_KIND(key_type->info) != BTF_KIND_STRUCT ||
            BTF_INFO_VLEN(key_type->info) != 2)
                return -EINVAL;

        /*
         * The first field must be a 64 bit integer at 0 offset.
         */
        m = (struct btf_member *)(key_type + 1);
        size = FIELD_SIZEOF(struct bpf_cgroup_storage_key, cgroup_inode_id);
        if (!btf_member_is_reg_int(btf, key_type, m, 0, size))
                return -EINVAL;

        /*
         * The second field must be a 32 bit integer at 64 bit offset.
         */
        m++;
        offset = offsetof(struct bpf_cgroup_storage_key, attach_type);
        size = FIELD_SIZEOF(struct bpf_cgroup_storage_key, attach_type);
        if (!btf_member_is_reg_int(btf, key_type, m, offset, size))
                return -EINVAL;

        return 0;
}

static void cgroup_storage_seq_show_elem(struct bpf_map *map, void *_key,
                                         struct seq_file *m)
{
        enum bpf_cgroup_storage_type stype = cgroup_storage_type(map);
        struct bpf_cgroup_storage_key *key = _key;
        struct bpf_cgroup_storage *storage;
        int cpu;

        rcu_read_lock();
        storage = cgroup_storage_lookup(map_to_storage(map), key, false);
        if (!storage) {
                rcu_read_unlock();
                return;
        }

        btf_type_seq_show(map->btf, map->btf_key_type_id, key, m);
        stype = cgroup_storage_type(map);
        if (stype == BPF_CGROUP_STORAGE_SHARED) {
                seq_puts(m, ": ");
                btf_type_seq_show(map->btf, map->btf_value_type_id,
                                  &READ_ONCE(storage->buf)->data[0], m);
                seq_puts(m, "\n");
        } else {
                seq_puts(m, ": {\n");
                for_each_possible_cpu(cpu) {
                        seq_printf(m, "\tcpu%d: ", cpu);
                        btf_type_seq_show(map->btf, map->btf_value_type_id,
                                          per_cpu_ptr(storage->percpu_buf, cpu),
                                          m);
                        seq_puts(m, "\n");
                }
                seq_puts(m, "}\n");
        }
        rcu_read_unlock();
}

const struct bpf_map_ops cgroup_storage_map_ops = {
        .map_alloc = cgroup_storage_map_alloc,
        .map_free = cgroup_storage_map_free,
        .map_get_next_key = cgroup_storage_get_next_key,
        .map_lookup_elem = cgroup_storage_lookup_elem,
        .map_update_elem = cgroup_storage_update_elem,
        .map_delete_elem = cgroup_storage_delete_elem,
        .map_check_btf = cgroup_storage_check_btf,
        .map_seq_show_elem = cgroup_storage_seq_show_elem,
};

int bpf_cgroup_storage_assign(struct bpf_prog *prog, struct bpf_map *_map)
{
        enum bpf_cgroup_storage_type stype = cgroup_storage_type(_map);
        struct bpf_cgroup_storage_map *map = map_to_storage(_map);
        int ret = -EBUSY;

        spin_lock_bh(&map->lock);

        if (map->prog && map->prog != prog)
                goto unlock;
        if (prog->aux->cgroup_storage[stype] &&
            prog->aux->cgroup_storage[stype] != _map)
                goto unlock;

        map->prog = prog;
        prog->aux->cgroup_storage[stype] = _map;
        ret = 0;
unlock:
        spin_unlock_bh(&map->lock);

        return ret;
}

void bpf_cgroup_storage_release(struct bpf_prog *prog, struct bpf_map *_map)
{
        enum bpf_cgroup_storage_type stype = cgroup_storage_type(_map);
        struct bpf_cgroup_storage_map *map = map_to_storage(_map);

        spin_lock_bh(&map->lock);
        if (map->prog == prog) {
                WARN_ON(prog->aux->cgroup_storage[stype] != _map);
                map->prog = NULL;
                prog->aux->cgroup_storage[stype] = NULL;
        }
        spin_unlock_bh(&map->lock);
}

static size_t bpf_cgroup_storage_calculate_size(struct bpf_map *map, u32 *pages)
{
        size_t size;

        if (cgroup_storage_type(map) == BPF_CGROUP_STORAGE_SHARED) {
                size = sizeof(struct bpf_storage_buffer) + map->value_size;
                *pages = round_up(sizeof(struct bpf_cgroup_storage) + size,
                                  PAGE_SIZE) >> PAGE_SHIFT;
        } else {
                size = map->value_size;
                *pages = round_up(round_up(size, 8) * num_possible_cpus(),
                                  PAGE_SIZE) >> PAGE_SHIFT;
        }

        return size;
}

struct bpf_cgroup_storage *bpf_cgroup_storage_alloc(struct bpf_prog *prog,
                                        enum bpf_cgroup_storage_type stype)
{
        struct bpf_cgroup_storage *storage;
        struct bpf_map *map;
        gfp_t flags;
        size_t size;
        u32 pages;

        map = prog->aux->cgroup_storage[stype];
        if (!map)
                return NULL;

        size = bpf_cgroup_storage_calculate_size(map, &pages);

        if (bpf_map_charge_memlock(map, pages))
                return ERR_PTR(-EPERM);

        storage = kmalloc_node(sizeof(struct bpf_cgroup_storage),
                               __GFP_ZERO | GFP_USER, map->numa_node);
        if (!storage)
                goto enomem;

        flags = __GFP_ZERO | GFP_USER;

        if (stype == BPF_CGROUP_STORAGE_SHARED) {
                storage->buf = kmalloc_node(size, flags, map->numa_node);
                if (!storage->buf)
                        goto enomem;
                check_and_init_map_lock(map, storage->buf->data);
        } else {
                storage->percpu_buf = __alloc_percpu_gfp(size, 8, flags);
                if (!storage->percpu_buf)
                        goto enomem;
        }

        storage->map = (struct bpf_cgroup_storage_map *)map;

        return storage;

enomem:
        bpf_map_uncharge_memlock(map, pages);
        kfree(storage);
        return ERR_PTR(-ENOMEM);
}

static void free_shared_cgroup_storage_rcu(struct rcu_head *rcu)
{
        struct bpf_cgroup_storage *storage =
                container_of(rcu, struct bpf_cgroup_storage, rcu);

        kfree(storage->buf);
        kfree(storage);
}

static void free_percpu_cgroup_storage_rcu(struct rcu_head *rcu)
{
        struct bpf_cgroup_storage *storage =
                container_of(rcu, struct bpf_cgroup_storage, rcu);

        free_percpu(storage->percpu_buf);
        kfree(storage);
}

void bpf_cgroup_storage_free(struct bpf_cgroup_storage *storage)
{
        enum bpf_cgroup_storage_type stype;
        struct bpf_map *map;
        u32 pages;

        if (!storage)
                return;

        map = &storage->map->map;

        bpf_cgroup_storage_calculate_size(map, &pages);
        bpf_map_uncharge_memlock(map, pages);

        stype = cgroup_storage_type(map);
        if (stype == BPF_CGROUP_STORAGE_SHARED)
                call_rcu(&storage->rcu, free_shared_cgroup_storage_rcu);
        else
                call_rcu(&storage->rcu, free_percpu_cgroup_storage_rcu);
}

void bpf_cgroup_storage_link(struct bpf_cgroup_storage *storage,
                             struct cgroup *cgroup,
                             enum bpf_attach_type type)
{
        struct bpf_cgroup_storage_map *map;

        if (!storage)
                return;

        storage->key.attach_type = type;
        storage->key.cgroup_inode_id = cgroup->kn->id.id;

        map = storage->map;

        spin_lock_bh(&map->lock);
        WARN_ON(cgroup_storage_insert(map, storage));
        list_add(&storage->list, &map->list);
        spin_unlock_bh(&map->lock);
}

void bpf_cgroup_storage_unlink(struct bpf_cgroup_storage *storage)
{
        struct bpf_cgroup_storage_map *map;
        struct rb_root *root;

        if (!storage)
                return;

        map = storage->map;

        spin_lock_bh(&map->lock);
        root = &map->root;
        rb_erase(&storage->node, root);

        list_del(&storage->list);
        spin_unlock_bh(&map->lock);
}

#endif