// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2023 Isovalent */

#include <linux/bpf.h>
#include <linux/bpf_mprog.h>

static int bpf_mprog_link(struct bpf_tuple *tuple,
                          u32 id_or_fd, u32 flags,
                          enum bpf_prog_type type)
{
        struct bpf_link *link = ERR_PTR(-EINVAL);
        bool id = flags & BPF_F_ID;

        if (id)
                link = bpf_link_by_id(id_or_fd);
        else if (id_or_fd)
                link = bpf_link_get_from_fd(id_or_fd);
        if (IS_ERR(link))
                return PTR_ERR(link);
        if (type && link->prog->type != type) {
                bpf_link_put(link);
                return -EINVAL;
        }

        tuple->link = link;
        tuple->prog = link->prog;
        return 0;
}

static int bpf_mprog_prog(struct bpf_tuple *tuple,
                          u32 id_or_fd, u32 flags,
                          enum bpf_prog_type type)
{
        struct bpf_prog *prog = ERR_PTR(-EINVAL);
        bool id = flags & BPF_F_ID;

        if (id)
                prog = bpf_prog_by_id(id_or_fd);
        else if (id_or_fd)
                prog = bpf_prog_get(id_or_fd);
        if (IS_ERR(prog))
                return PTR_ERR(prog);
        if (type && prog->type != type) {
                bpf_prog_put(prog);
                return -EINVAL;
        }

        tuple->link = NULL;
        tuple->prog = prog;
        return 0;
}

static int bpf_mprog_tuple_relative(struct bpf_tuple *tuple,
                                    u32 id_or_fd, u32 flags,
                                    enum bpf_prog_type type)
{
        bool link = flags & BPF_F_LINK;
        bool id = flags & BPF_F_ID;

        memset(tuple, 0, sizeof(*tuple));
        if (link)
                return bpf_mprog_link(tuple, id_or_fd, flags, type);
        /* If no relevant flag is set and no id_or_fd was passed, then
         * tuple link/prog is just NULLed. This is the case when before/
         * after selects first/last position without passing fd.
         */
        if (!id && !id_or_fd)
                return 0;
        return bpf_mprog_prog(tuple, id_or_fd, flags, type);
}

static void bpf_mprog_tuple_put(struct bpf_tuple *tuple)
{
        if (tuple->link)
                bpf_link_put(tuple->link);
        else if (tuple->prog)
                bpf_prog_put(tuple->prog);
}

/* The bpf_mprog_{replace,delete}() operate on exact idx position with the
 * one exception that for deletion we support delete from front/back. In
 * case of front idx is -1, in case of back idx is bpf_mprog_total(entry).
 * Adjustment to first and last entry is trivial. The bpf_mprog_insert()
 * we have to deal with the following cases:
 *
 * idx + before:
 *
 * Insert P4 before P3: idx for old array is 1, idx for new array is 2,
 * hence we adjust target idx for the new array, so that memmove copies
 * P1 and P2 to the new entry, and we insert P4 into idx 2. Inserting
 * before P1 would have old idx -1 and new idx 0.
 *
 * +--+--+--+     +--+--+--+--+     +--+--+--+--+
 * |P1|P2|P3| ==> |P1|P2|  |P3| ==> |P1|P2|P4|P3|
 * +--+--+--+     +--+--+--+--+     +--+--+--+--+
 *
 * idx + after:
 *
 * Insert P4 after P2: idx for old array is 2, idx for new array is 2.
 * Again, memmove copies P1 and P2 to the new entry, and we insert P4
 * into idx 2. Inserting after P3 would have both old/new idx at 4 aka
 * bpf_mprog_total(entry).
 *
 * +--+--+--+     +--+--+--+--+     +--+--+--+--+
 * |P1|P2|P3| ==> |P1|P2|  |P3| ==> |P1|P2|P4|P3|
 * +--+--+--+     +--+--+--+--+     +--+--+--+--+
 */
static int bpf_mprog_replace(struct bpf_mprog_entry *entry,
                             struct bpf_mprog_entry **entry_new,
                             struct bpf_tuple *ntuple, int idx)
{
        struct bpf_mprog_fp *fp;
        struct bpf_mprog_cp *cp;
        struct bpf_prog *oprog;

        bpf_mprog_read(entry, idx, &fp, &cp);
        oprog = READ_ONCE(fp->prog);
        bpf_mprog_write(fp, cp, ntuple);
        if (!ntuple->link) {
                WARN_ON_ONCE(cp->link);
                bpf_prog_put(oprog);
        }
        *entry_new = entry;
        return 0;
}

static int bpf_mprog_insert(struct bpf_mprog_entry *entry,
                            struct bpf_mprog_entry **entry_new,
                            struct bpf_tuple *ntuple, int idx, u32 flags)
{
        int total = bpf_mprog_total(entry);
        struct bpf_mprog_entry *peer;
        struct bpf_mprog_fp *fp;
        struct bpf_mprog_cp *cp;

        peer = bpf_mprog_peer(entry);
        bpf_mprog_entry_copy(peer, entry);
        if (idx == total)
                goto insert;
        else if (flags & BPF_F_BEFORE)
                idx += 1;
        bpf_mprog_entry_grow(peer, idx);
insert:
        bpf_mprog_read(peer, idx, &fp, &cp);
        bpf_mprog_write(fp, cp, ntuple);
        bpf_mprog_inc(peer);
        *entry_new = peer;
        return 0;
}

static int bpf_mprog_delete(struct bpf_mprog_entry *entry,
                            struct bpf_mprog_entry **entry_new,
                            struct bpf_tuple *dtuple, int idx)
{
        int total = bpf_mprog_total(entry);
        struct bpf_mprog_entry *peer;

        peer = bpf_mprog_peer(entry);
        bpf_mprog_entry_copy(peer, entry);
        if (idx == -1)
                idx = 0;
        else if (idx == total)
                idx = total - 1;
        bpf_mprog_entry_shrink(peer, idx);
        bpf_mprog_dec(peer);
        bpf_mprog_mark_for_release(peer, dtuple);
        *entry_new = peer;
        return 0;
}

/* In bpf_mprog_pos_*() we evaluate the target position for the BPF
 * program/link that needs to be replaced, inserted or deleted for
 * each "rule" independently. If all rules agree on that position
 * or existing element, then enact replacement, addition or deletion.
 * If this is not the case, then the request cannot be satisfied and
 * we bail out with an error.
 */
static int bpf_mprog_pos_exact(struct bpf_mprog_entry *entry,
                               struct bpf_tuple *tuple)
{
        struct bpf_mprog_fp *fp;
        struct bpf_mprog_cp *cp;
        int i;

        for (i = 0; i < bpf_mprog_total(entry); i++) {
                bpf_mprog_read(entry, i, &fp, &cp);
                if (tuple->prog == READ_ONCE(fp->prog))
                        return tuple->link == cp->link ? i : -EBUSY;
        }
        return -ENOENT;
}

static int bpf_mprog_pos_before(struct bpf_mprog_entry *entry,
                                struct bpf_tuple *tuple)
{
        struct bpf_mprog_fp *fp;
        struct bpf_mprog_cp *cp;
        int i;

        for (i = 0; i < bpf_mprog_total(entry); i++) {
                bpf_mprog_read(entry, i, &fp, &cp);
                if (tuple->prog == READ_ONCE(fp->prog) &&
                    (!tuple->link || tuple->link == cp->link))
                        return i - 1;
        }
        return tuple->prog ? -ENOENT : -1;
}

static int bpf_mprog_pos_after(struct bpf_mprog_entry *entry,
                               struct bpf_tuple *tuple)
{
        struct bpf_mprog_fp *fp;
        struct bpf_mprog_cp *cp;
        int i;

        for (i = 0; i < bpf_mprog_total(entry); i++) {
                bpf_mprog_read(entry, i, &fp, &cp);
                if (tuple->prog == READ_ONCE(fp->prog) &&
                    (!tuple->link || tuple->link == cp->link))
                        return i + 1;
        }
        return tuple->prog ? -ENOENT : bpf_mprog_total(entry);
}

int bpf_mprog_attach(struct bpf_mprog_entry *entry,
                     struct bpf_mprog_entry **entry_new,
                     struct bpf_prog *prog_new, struct bpf_link *link,
                     struct bpf_prog *prog_old,
                     u32 flags, u32 id_or_fd, u64 revision)
{
        struct bpf_tuple rtuple, ntuple = {
                .prog = prog_new,
                .link = link,
        }, otuple = {
                .prog = prog_old,
                .link = link,
        };
        int ret, idx = -ERANGE, tidx;

        if (revision && revision != bpf_mprog_revision(entry))
                return -ESTALE;
        if (bpf_mprog_exists(entry, prog_new))
                return -EEXIST;
        ret = bpf_mprog_tuple_relative(&rtuple, id_or_fd,
                                       flags & ~BPF_F_REPLACE,
                                       prog_new->type);
        if (ret)
                return ret;
        if (flags & BPF_F_REPLACE) {
                tidx = bpf_mprog_pos_exact(entry, &otuple);
                if (tidx < 0) {
                        ret = tidx;
                        goto out;
                }
                idx = tidx;
        } else if (bpf_mprog_total(entry) == bpf_mprog_max()) {
                ret = -ERANGE;
                goto out;
        }
        if (flags & BPF_F_BEFORE) {
                tidx = bpf_mprog_pos_before(entry, &rtuple);
                if (tidx < -1 || (idx >= -1 && tidx != idx)) {
                        ret = tidx < -1 ? tidx : -ERANGE;
                        goto out;
                }
                idx = tidx;
        }
        if (flags & BPF_F_AFTER) {
                tidx = bpf_mprog_pos_after(entry, &rtuple);
                if (tidx < -1 || (idx >= -1 && tidx != idx)) {
                        ret = tidx < 0 ? tidx : -ERANGE;
                        goto out;
                }
                idx = tidx;
        }
        if (idx < -1) {
                if (rtuple.prog || flags) {
                        ret = -EINVAL;
                        goto out;
                }
                idx = bpf_mprog_total(entry);
                flags = BPF_F_AFTER;
        }
        if (idx >= bpf_mprog_max()) {
                ret = -ERANGE;
                goto out;
        }
        if (flags & BPF_F_REPLACE)
                ret = bpf_mprog_replace(entry, entry_new, &ntuple, idx);
        else
                ret = bpf_mprog_insert(entry, entry_new, &ntuple, idx, flags);
out:
        bpf_mprog_tuple_put(&rtuple);
        return ret;
}

static int bpf_mprog_fetch(struct bpf_mprog_entry *entry,
                           struct bpf_tuple *tuple, int idx)
{
        int total = bpf_mprog_total(entry);
        struct bpf_mprog_cp *cp;
        struct bpf_mprog_fp *fp;
        struct bpf_prog *prog;
        struct bpf_link *link;

        if (idx == -1)
                idx = 0;
        else if (idx == total)
                idx = total - 1;
        bpf_mprog_read(entry, idx, &fp, &cp);
        prog = READ_ONCE(fp->prog);
        link = cp->link;
        /* The deletion request can either be without filled tuple in which
         * case it gets populated here based on idx, or with filled tuple
         * where the only thing we end up doing is the WARN_ON_ONCE() assert.
         * If we hit a BPF link at the given index, it must not be removed
         * from opts path.
         */
        if (link && !tuple->link)
                return -EBUSY;
        WARN_ON_ONCE(tuple->prog && tuple->prog != prog);
        WARN_ON_ONCE(tuple->link && tuple->link != link);
        tuple->prog = prog;
        tuple->link = link;
        return 0;
}

int bpf_mprog_detach(struct bpf_mprog_entry *entry,
                     struct bpf_mprog_entry **entry_new,
                     struct bpf_prog *prog, struct bpf_link *link,
                     u32 flags, u32 id_or_fd, u64 revision)
{
        struct bpf_tuple rtuple, dtuple = {
                .prog = prog,
                .link = link,
        };
        int ret, idx = -ERANGE, tidx;

        if (flags & BPF_F_REPLACE)
                return -EINVAL;
        if (revision && revision != bpf_mprog_revision(entry))
                return -ESTALE;
        if (!bpf_mprog_total(entry))
                return -ENOENT;
        ret = bpf_mprog_tuple_relative(&rtuple, id_or_fd, flags,
                                       prog ? prog->type :
                                       BPF_PROG_TYPE_UNSPEC);
        if (ret)
                return ret;
        if (dtuple.prog) {
                tidx = bpf_mprog_pos_exact(entry, &dtuple);
                if (tidx < 0) {
                        ret = tidx;
                        goto out;
                }
                idx = tidx;
        }
        if (flags & BPF_F_BEFORE) {
                tidx = bpf_mprog_pos_before(entry, &rtuple);
                if (tidx < -1 || (idx >= -1 && tidx != idx)) {
                        ret = tidx < -1 ? tidx : -ERANGE;
                        goto out;
                }
                idx = tidx;
        }
        if (flags & BPF_F_AFTER) {
                tidx = bpf_mprog_pos_after(entry, &rtuple);
                if (tidx < -1 || (idx >= -1 && tidx != idx)) {
                        ret = tidx < 0 ? tidx : -ERANGE;
                        goto out;
                }
                idx = tidx;
        }
        if (idx < -1) {
                if (rtuple.prog || flags) {
                        ret = -EINVAL;
                        goto out;
                }
                idx = bpf_mprog_total(entry);
                flags = BPF_F_AFTER;
        }
        if (idx >= bpf_mprog_max()) {
                ret = -ERANGE;
                goto out;
        }
        ret = bpf_mprog_fetch(entry, &dtuple, idx);
        if (ret)
                goto out;
        ret = bpf_mprog_delete(entry, entry_new, &dtuple, idx);
out:
        bpf_mprog_tuple_put(&rtuple);
        return ret;
}

int bpf_mprog_query(const union bpf_attr *attr, union bpf_attr __user *uattr,
                    struct bpf_mprog_entry *entry)
{
        u32 __user *uprog_flags, *ulink_flags;
        u32 __user *uprog_id, *ulink_id;
        struct bpf_mprog_fp *fp;
        struct bpf_mprog_cp *cp;
        struct bpf_prog *prog;
        const u32 flags = 0;
        u32 id, count = 0;
        u64 revision = 1;
        int i, ret = 0;

        if (attr->query.query_flags || attr->query.attach_flags)
                return -EINVAL;
        if (entry) {
                revision = bpf_mprog_revision(entry);
                count = bpf_mprog_total(entry);
        }
        if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags)))
                return -EFAULT;
        if (copy_to_user(&uattr->query.revision, &revision, sizeof(revision)))
                return -EFAULT;
        if (copy_to_user(&uattr->query.count, &count, sizeof(count)))
                return -EFAULT;
        uprog_id = u64_to_user_ptr(attr->query.prog_ids);
        uprog_flags = u64_to_user_ptr(attr->query.prog_attach_flags);
        ulink_id = u64_to_user_ptr(attr->query.link_ids);
        ulink_flags = u64_to_user_ptr(attr->query.link_attach_flags);
        if (attr->query.count == 0 || !uprog_id || !count)
                return 0;
        if (attr->query.count < count) {
                count = attr->query.count;
                ret = -ENOSPC;
        }
        for (i = 0; i < bpf_mprog_max(); i++) {
                bpf_mprog_read(entry, i, &fp, &cp);
                prog = READ_ONCE(fp->prog);
                if (!prog)
                        break;
                id = prog->aux->id;
                if (copy_to_user(uprog_id + i, &id, sizeof(id)))
                        return -EFAULT;
                if (uprog_flags &&
                    copy_to_user(uprog_flags + i, &flags, sizeof(flags)))
                        return -EFAULT;
                id = cp->link ? cp->link->id : 0;
                if (ulink_id &&
                    copy_to_user(ulink_id + i, &id, sizeof(id)))
                        return -EFAULT;
                if (ulink_flags &&
                    copy_to_user(ulink_flags + i, &flags, sizeof(flags)))
                        return -EFAULT;
                if (i + 1 == count)
                        break;
        }
        return ret;
}